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  1. Advanced Patent Search
Publication numberUSRE32140 E
Publication typeGrant
Application numberUS 06/509,769
Publication dateMay 6, 1986
Filing dateJun 30, 1983
Priority dateSep 21, 1977
Also published asDE2840706A1, DE2840706C2, US4276601
Publication number06509769, 509769, US RE32140 E, US RE32140E, US-E-RE32140, USRE32140 E, USRE32140E
InventorsHiroastu Tokuda, Shigeki Morinaga, Hideo Nakamura
Original AssigneeHitachi, Ltd.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electronic engine control apparatus
US RE32140 E
Abstract
An electronic engine control apparatus in which the timing of the ignition and the fuel injection are calculated from a negative pressure in the intake manifold of the engine or the flow rate of suction air and the rotational speed of the engine. A reference register group is constituted of registers for storing the result of the calculation while an instantaneous register group is made up of registers for storing the instantaneous states of actuators. One of the registers of the reference register group and one of the registers of the instantaneous register group are selected according to a stage timing signal so that the contents of the two registers selected are compared with each other.
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Claims(56)
What we claim is:
1. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine for which a plurality of sensors produce signals representative of operating conditions of said engine and being coupled to actuator means for controlling respective energy conversion functions of said engine in response to control signals applied thereto;
an improved control apparatus comprising, in combination:
first means for generating an engine control timing signal pattern through which operational events of .[.said.]. .Iadd.the .Iaddend.engine are controlled;
second means for storing engine control codes coupled thereto;
third means, coupled to said first means, for generating respective engine timing codes the values of which are selectively modified by said engine control timing .Iadd.signal .Iaddend.pattern;
fourth means, coupled to said second and third means, for comparing respective ones of said engine control codes with respective ones of said engine timing codes and producing respective output signals when said respective engine control codes define a prescribed relationship with respect to said engine timing codes; and
fifth means, coupled to said fourth means, for producing control signals to be coupled to .[.said.]. .Iadd.the .Iaddend.actuator means in response to the output signals produced by said fourth means.
2. An improved control apparatus according to claim 1, wherein said prescribed relationship is such that the value of a respective engine timing code is greater than or equal to the value of a corresponding respective engine control code.
3. An improved control apparatus according to claim 1, further comprising sixth means, coupled to said third means, for supplying .[.coupling.]. to said processor at least one of said engine timing codes.
4. An improved control apparatus according to claim 3, wherein said sixth means includes means for coupling to said processor those engine timing codes that are indicative of at least one of engine speed and vehicle speed.
5. An improved control apparatus according to claim 4, wherein the supplied engine timing codes are indicative of both engine speed and vehicle speed.
6. An improved control apparatus according to claim 1, wherein said third means comprises
a plurality of storage devices for storing respective engine timing codes, and
means, coupled to said plurality of storage devices, for controllably modifying the engine timing codes in accordance with said engine control timing .Iadd.signal .Iaddend.pattern.
7. An improved control apparatus according to claim 6, wherein said controllably modifying means comprises
means for selectively incrementing the data value of a respective engine timing code by a prescribed value in response to receipt of a respective portion of said engine control timing signal pattern that is associated with that engine timing code.
8. An improved control apparatus according to claim 7, wherein said incrementing means comprises
means for temporarily storing the engine timing code stored by each respective one of said storage devices, and
means for receiving the engine timing code from said temporarily storing means and selectively incrementing the data value of said code and causing the engine timing code stored in said respective one of said storage devices to be replaced by said code the data value of which has been selectively incremented.
9. An improved control apparatus according to claim 7, wherein said incrementing means comprises
means for reading out the engine timing code stored by each respective one of said storage devices and temporarily storing said read-out engine timing code during a first interval of time, and
means for receiving the engine timing code from said temporarily storing means and selectively incrementing the data value of said code and causing the engine timing code stored in said respective one of said storage devices to be replaced by said code the data value of which has been selectively incremented during a second interval of time subsequent to said first interval of time.
10. An improved control apparatus according to claim 6, wherein said fifth means includes
a first plurality of storage means for selectively storing the respective output signals produced by said fourth means; and
a second plurality of storage means, coupled to the respective ones of said first plurality of storage means, for receiving and storing the output signals stored by said first plurality of storage means.
11. An improved control apparatus according to claim 10, wherein said controllably modifying means includes means, coupled to said fifth means, for controllably modifying the engine timing codes stored in said plurality of storage devices in dependence upon the output signals stored said second plurality of storage means.
12. An improved control apparatus according to claim 11, wherein said fifth means further includes means for causing a respective storage means of said first plurality of storage means to store a respective output signal produced by said fourth means during a first interval of time and thereafter causing a corresponding respective storage means of said second plurality of storage means to receive and store said respective output signal stored in said respective storage means of said first plurality of storage means during a second interval of time subsequent to said first interval of time.
13. An improved control apparatus according to claim 12, wherein said controllably modifying means comprises
means for selectively incrementing the data value of a respective engine timing code by a prescribed value in response to receipt of a respective portion of said engine control timing signal pattern that is associated with that engine timing code.
14. An improved control apparatus according to claim 13, wherein said incrementing means comprises
means for reading out the engine timing code stored by each respective one of said storage devices and temporarily storing said read-out engine timing code during a first interval of time, and
means for receiving the engine timing code from said temporarily storing means and selectively incrementing the data value of said code and causing the engine timing code stored in said respective one of said storage devices to be replaced by said code the data value of which has been selectively incremented during a second interval of time subsequent to said first interval of time.
15. An improved control apparatus according to claim 6, .[.wherein said ∫ .Iadd.further comprising a .Iaddend.plurality of sensors .[.include.]. .Iadd.including .Iaddend.rotation timing signal generating means for generating rotation timing signals in synchronization with rotation of the engine shaft,
.Iadd.wherein .Iaddend.said third means further includes synchronization circuit means coupled to said rotation timing signal generating means, for synchronizing the engine control timing signals of said engine control timing signal pattern with said rotation timing signals, and
.Iadd.further wherein .Iaddend.said controllably modifying means is coupled to controllably modify said engine timing codes in response to the output of said synchronization circuit means.
16. An improved control apparatus according to claim 1, wherein .[.said.]. .Iadd.the .Iaddend.energy conversion functions include at least one of fuel supply, ignition, exhaust gas return and idle condition of the engine.
17. An improved control apparatus accordint to claim 16, wherein engine control timing signals of said .Iadd.engine control timing signal .Iaddend.pattern include engine control timing signals of relatively different frequencies.
18. An improved control apparatus according to claim 17, wherein engine control timing signals of said .Iadd.engine control timing signal .Iaddend.pattern which relate to fuel supply and ignition of the engine have a frequency relatively high compared to the frequency of engine control timing signals of said .Iadd.engine control timing signal .Iaddend.pattern which relate to exhaust gas return and idle condition of the engine.
19. An improved control apparatus according to claim 16, wherein the engine control timing signals of said .Iadd.engine control timing signal .Iaddend.pattern include signals representative of a prescribed angle of rotation of the engine crankshaft INTL, the number of cycles of the engine CYL, advance ADV, dwell DWL, vehicle speed VSP, engine speed RPM, time of fuel injection INJ, exhaust gas return EGR, and idle condition NIDL.
20. An improved control apparatus according to claim 19, wherein the generation of said engine control timing signals follows the order INTL, CYL, INJ, ADV, DWL, EGR, NIDL.
21. An improved control apparatus according to claim 1, wherein
.[.said.]. .Iadd.the .Iaddend.actuator means include an exhaust gas recycle means for controlling the exhaust gas recycle condition in accordance with prescribed pulse intervals and pulse durations;
said second means includes means for storing engine control codes defining said prescribed pulse interval and said prescribed pulse duration; and
said third means includes means for generating respective engine timing codes corresponding to said prescribed pulse interval and said prescribed pulse duration.
22. An improved apparatus according to claim 1, wherein
.[.said.]. .Iadd.the .Iaddend.actuator means include an air regulator for controlling the quantity of air flowing into the engine,
said second means includes means for storing an engine control code defining a prescribed air regulator control pulse interval and an engine control code defining the duration of said prescribed air regulator control pulse; and
said third means includes means for generating respective engine timing codes corresponding to said prescribed air regulator control pulse interval and the duration of said prescribed air regulator control pulse.
23. An improved control apparatus according to claim, wherein said second means includes means for storing an engine control code representative of the angular rotation of the crankshaft of the engine from its position at which the conduction of primary current in an ignition coil is to be initiated, and wherein said third means includes means for generating an engine timing code that is modified in accordance with the ignition timing.
24. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine for which a plurality of sensors produce signals representative of operating conditions of said engine and adapted to be coupled to actuator means for controlling respective energy conversion functions of said engine in response to control signals applied thereto;
an improved control apparatus comprising, in combination:
first means, responsive to engine control codes coupled thereto for producing respective engine timing codes the values of which are sequentially modified;
second means, coupled to said first means, for producing respective output signals upon the values of said respective engine timing codes reaching defined limits;
third means, coupled to said second means, for storing said output signals for application to .[.said.]. .Iadd.the .Iaddend.actuator means; and
fourth means, coupled to said first and third means, for causing the values of said respective engine timing codes to be modified in dependence upon the output signals stored by said third means.
25. An improved control apparatus according to claim 24, wherein .[.said.]. .Iadd.the .Iaddend.energy conversion functions include at least one of fuel supply, ignition, exhaust gas return and idle condition of the engine.
26. An improved control apparatus according to claim 24, wherein said third means includes
a first plurality of storage means for storing the respective output signals produced by said second means, and
a second plurality of storage means, coupled to the respective ones of said first plurality of storage means, for receiving and storing the output signals stored by said first plurality of storage means.
27. An improved control apparatus according to claim 26, wherein said third means further includes means for causing a respective storage means of said first plurality of storage means to store a respective output signal produced by said second means during a first interval of time and thereafter causing a corresponding respective storage means of said second plurality of storage means to receive and store said respective output signals stored in said respective storage means of said first plurality of storage means during a second interval of time subsequent to said first interval of time.
28. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine for which a plurality of sensors produce signals representative of operating conditions of said engine and being adapted to be coupled to actuator means for controlling respective energy conversion functions of said engine in response to control signals applied thereto;
an improved control apparatus comprising, in combination:
first means for generating an engine control timing signal pattern through which operational events of said engine are controlled;
second means, coupled to said first means, for generating respective engine timing codes the values of which are selectively modified by said engine control timing signal pattern, so as to produce respective output signals to be coupled to said actuator means, and
third means, coupled to said second means, for coupling to said processor at least one engine timing code generated by said second means.
29. An improved control apparatus according to claim 28, wherein the signals produced by those sensors, among .[.said.]. .Iadd.the .Iaddend.plurality of sensors, which are representative of at least one of engine speed and vehicle speed are coupled to said second means, whereby engine control data processing operations carried out by said processor that involves data relating to at least one of engine speed and vehicle speed are accomplished in response to the output of said third means.
30. An improved control apparatus according to claim 29, wherein said third means includes means for coupling to said processor those engine timing codes generated by said second means that are indicative of at least one of engine speed and vehicle speed.
31. An improved control apparatus according to claim 29, wherein said third means includes means for coupling to said data processor those engine timing codes generated by said second means that are indicative of both engine speed and vehicle speed.
32. An improved control apparatus according to claim 28, wherein .[.said.]. .Iadd.the .Iaddend.energy conversion functions include at least one of fuel supply, ignition, exhaust gas return and idle condition of the engine.
33. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine for which a plurality of sensors produce signals representative of operating conditions of the engine and being adapted to be coupled to actuators for controlling said engine;
a control apparatus for generating pulses for driving said actuators in accordance with processor-generated engine control data, said actuators controlling said engine in accordance with the pulses delivered from said control apparatus;
said control apparatus comprising, in combination:
a first plurality of storage means for storing outputs of .[.said.]. .Iadd.a .Iaddend.processor .Iadd.coupled to said control apparatus.Iaddend.;
counting means for generating a plurality of digital codes .Iadd.in accordance with timing signals produced by the processor for .Iaddend.representing instantaneous states of .[.said.]. .Iadd.the .Iaddend.actuators and .[.said.]. .Iadd.the .Iaddend.engine, said counting means including a second plurality of storage means corresponding to said first plurality of storage means for storing said digital codes;
a comparator for comparing the digital code of each of the storage means of said first plurality with the content of the corresponding storage means of said second plurality;
a third plurality of storage means, corresponding to the storage means of said first plurality, for storing each of the respective outputs of said comparator;
first transfer means for transferring to .[.said.]. .Iadd.the .Iaddend.actuators the outputs of said third plurality of storage means; and
stage signal generating means for generating stage signals corresponding to said first plurality of storage means, said stage signals determining the timing of the operation of .[.said pulse outputs means.]. .Iadd.control apparatus for generating pulses.Iaddend.; and
wherein each of said second plurality of storage means and the corresponding storage means of said third plurality is respectively selected in accordance with said stage signals, and the digital codes of the storage means of said second plurality corresponding to said stage signals are compared with the respective contents of the storage means of said first plurality by said comparator, with the results, of the comparison being stored in said third plurality of storage means, and said engine is controlled on the basis of the stored results.
34. A control apparatus according to claim 33, wherein said counting means comprises
increment means for receiving digital codes from the storage means of said second plurality selected in accordance with said stage signals and for incrementing said codes by a constant value; and
setting means for setting the output data of said increment means into said selected storage means of said second plurality.
35. A control apparatus according to claim 34, wherein
said sensors include rotation pulse generating means for generating pulses in synchronization with the engine shaft rotation; and wherein
said increment means includes
synchronization circuit means coupled to said stage signal generating means for synchronizing the output pulses of said rotating pulse generating means with the stage signals, and
an increment circuit for increasing the output of a selected one of said second storage means in response to the output of said synchronization circuit means.
36. A control apparatus according to claIm 33, wherein
one of said sensors is composed of pulse generating means for generating pulses in synchronism with a predetermined rotation angle of said engine; and
said counting means comprises
increment means for receiving the digital codes stored in the storage means of said second plurality selected in accordance with said stage signals and for incrementing said codes by a constant value in response to the output of said pulse generating means, and
data setting means for setting the output of said increment means into said selected storage means of said second plurality.
37. A control apparatus according to claim 33, wherein
one of said sensors is composed of a pulse generating means for generating pulses in synchronism with a predetermined rotation angle of a vehicle wheel; and
said counting means comprises
increment means for receiving the digital codes stored in the storage means of said second plurality selected in accordance with said stage signals and for incrementing said codes by a constant value in response to the output of said pulse generating means; and
data setting means for setting the output of said increment means into said selected storage means of said second plurality.
38. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine having an output shaft driven by mechanical energy converted from heat energy released by the combustion of fuel, said engine including igniting means for igniting the fuel to generate heat energy in accordance with conditions of said engine, said igniting means initiating the charging of ignition energy at energy charging timing and igniting the fuel at ignition timing, and for which a plurality of sensors produce signals representative of operating conditions of the engine and having digital converting means for converting the outputs of the sensors into corresponding digital signals;
a control apparatus for generating output pulses to drive said igniting means in accordance with the digital outputs of said processor,
said control apparatus comprising, in combination:
stage signal generating means for repetitively generating at least first and second stage signals corresponding to prescribed engine timing operations,
a first plurality of registers including at least first and second registers coupled to said stage signal generating means, said first register storing outputs of said processor defining said charging timing and selected in response to said first stage signals for providing stored data, said second register storing the output of said processor defining said ignition timing and selected in response to said second stage signal for providing stored data,
counter means including at least first and second counters for storing respective codes representative of the instantaneous condition of said igniting means and coupled to said stage signal generating means, said first counter being selected in response to said first stage signal, said second counter being selected in response to said second stage signal,
a comparator for comparing the contents of a selected one of said first plurality of registers with the contents of a selected one of said second plurality of registers, and
output means including a plurality of storage means for storing the outputs of said comparator and delivering the output to the igniting means, said output means being coupled to the stage signal generating means and to one of said storage means being selected in response to a stage signal for receiving an output of said comparator.
39. A control apparatus according to claim 38, wherein
.[.said.]. .Iadd.the .Iaddend.sensor includes rotation pulse generating means for generating pulses in synchronization with the engine shaft rotation, and wherein
said counter means includes synchronization circuit means coupled to said stage signal generating means and to said rotation pulse generating means for generating pulses in synchronization with said stage signals of said stage signal generating means and in response to the output pulses of said rotation pulse generating means, said first and second counters being controlled in response to outputs of said synchronization circuit means.
40. A control according to claim 38, wherein
said sensors include rotation pulse generating means for generating position pulses and reference pulses in synchronization with the engine shaft rotation, a plurality of position pulses being generated between said successive reference pulses, and wherein
said counter means include first and second synchronization circuit means, said first synchronization circuit means being coupled to said stage signal generating means and to said rotation pulse generating for synchronizing the position pulses of said rotation pulse generating means with the stage signals of said stages signal generating means, said second synchronization circuit means being coupled to said stage signal generating means and to said rotation pulse generating means for synchronizing the reference pulses of said rotation pulse generating means with the stage signals of said stage signal generating means, said second counter being incremented in response to outputs of said first synchronization circuit means and being initiated in response to the output of said second synchronization circuit means.
41. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine having an output shaft driven by mechanical energy converted from heat energy released by the combustion of fuel, said engine including igniting means for igniting the fuel to generate heat energy in accordance with conditions of said engine, said igniting means initiating the charging of ignition energy at energy charging timing and igniting the fuel at ignition timing, said apparatus including a plurality of sensors for detecting operating conditions of said engine at selected instants in time during the operation of said engine, said sensors including rotation pulse generating means for generating position pulses and reference pulses in synchronization with engine shaft rotation, said position pulses being generated for relatively short intervals of engine shaft rotation and said reference pulse being generated for relatively large intervals of engine shaft rotation, and digital converting means for converting the outputs of said sensors into corresponding digital signals,
a control apparatus for generating output pulses to drive .[.said.]. .Iadd.the .Iaddend.igniting means in accordance with outputs of said processor, said control apparatus comprising, in combination:
stage signal generating means for repetitively generating at least first and second stage signals representative of prescribed engine timing operations,
a first register for storing digital signals representative of energy charging timings coupled from said processor, said first register being coupled to said stage signal generating means and selected in response to said second stage signals,
a second register for storing digital signals representative of ignition timing coupled from said processor, said second register being coupled to said stage signal generating means and selected in response to said second stage signals,
first synchronization circuit means for synchronizing position pulses of said rotation pulse generating means with stage signals of said stage signal generating means,
second synchronization circuit means for synchronizing reference pulses to said rotation pulse generating means with stage signals of said stage signal generating means,
a first counter the contents of which are incremented in response to the output of said first synchronization circuit means, and first counter being coupled to said stage signal generating means and selected in response to said first stage signals,
a second counter the contents of which are incremented in response to the output of said first synchronization circuit means, said second counter being coupled to said signal generating means and selected in response to said second stage signals,
a comparator for comparing the output of a selected register with the output of a selected counter, and
output means, including a plurality of storage means for storing outputs of said comparator and coupling the outputs to the igniting means in accordance with the stored outputs of said comparator, said output means being coupled to the stage signal generating means and to one of said storage means being selected in response to a stage signal for receiving outputs of said comparator.
42. A control apparatus according to claim 41, wherein said output means includes
first storing means, selected in response to said first stage signals, for storing outputs of said comparator,
second storing means, selected in response to said second stage signals, for storing outputs of said comparator and
wherein said first and second counters include control means, coupled to said second synchronization circuit means and coupled to said second storing means, for starting the incrementing of said first counter in response to the output of said second storing means and for starting the incrementing of said second counter in response to the output of said second synchronization circuit means.
43. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine having an output shaft driven by mechanical energy converted from heat energy released by the combustion of fuel, said engine including igniting means for igniting the fuel to generate the heat energy in accordance with conditions of said engine, said igniting means initiating the charging of ignition energy at energy charging timing and igniting the fuel at ignition timing, said apparatus including a plurality of sensors for detecting operating conditions of said engine at selected instants in time during the operation of said engine, said sensors including rotation pulse generating means for generating position pulses and reference pulses in synchronization with the engine shaft rotation, said position pulses being generated at relatively small intervals of engine shaft rotation and said reference pulses being generated at relatively large intervals of engine shaft rotation, digital converting means for converting the outputs of said sensors into corresponding digital signals,
a control apparatus for generating output pulses to drive said igniting means in accordance with outputs of said processor;
said control apparatus comprising, in combination:
stage signal generating means for repetitively generating at least first, second, and third stage signals representative of prescribed engine timing operation,
first synchronization circuit means, coupled to said rotation pulse generating means and to said stage signal generating means, for synchronizing the position pulses with the stage signals,
second synchronization circuit means, coupled to said rotation pulse generating means and to said stage signal generating means, for synchronizing the reference pulses with the stage signals,
a first plurality of registers including first, second, and third registers coupled to said stage signal generating means, said first register storing a predetermined value and being selected in response to said first stage signals, said second register storing data defining an energy charging timing signal coupled from said processor and selected in response to said second stage signals, said third register storing data defining an ignition timing signal coupled from said processor and selected in response to said third stage signals,
a second plurality of registers including at least first, second, and third registers and being coupled to said stage signal generating means the first, second, or third register of said second plurality being selected in response to said first, second, or third stage signals, respectively,
incrementor means, coupled to said first synchronization circuit means and said second plurality of registers, for incrementing the data stored in the selected register of said second plurality of registers in response to outputs of said first synchronization circuit means, so that the combination of said incrementor means and each register of said second plurality of registers operates as a counter the contents of which are increased in response to the outputs of said first synchronization circuit means,
a comparator for comparing the output of the selected register of said first plurality of registers with the counted data of the selected register of said second plurality of registers,
output means, including first, second, and third storing means, for storing outputs of said comparator and coupling output pulses to the igniting means in accordance with the stored outputs of said comparator, said output means being coupled to said stage signal generating means, and said first, second, and third storing means being selected in response to said first, second, and third stage signals of said stage signal generating means respectively, and
incrementor control means, coupled to said first and second synchronization circuit means and to said incrementor means, for starting the counting operation of the combination of said first registers of said second plurality of registers and said incrementor means, in response to the output of said second synchronization circuit means, for starting the counting operation of the combination of the second register of said second plurality of registers and said incrementor means in response to the output of said third storing means of said output means, and for starting the counting operation of the combination of the third register of said second plurality of registers and said incrementor means in response to the output of first storing means.
44. A control apparatus according to claim 43, wherein said actuators further include an exhaust gas recycle means for controlling the exhaust gas recycle condition in accordance with prescribed pulse intervals and pulse durations;
wherein said first plurality of registers include a register for storing data defining said prescribed pulse interval, and a register for storing data defining said prescribed pulse duration; and
wherein said output means outputs pulses to said exhaust gas recycle means in accordance with the stored contents of said output means.
45. A control apparatus according to claim 43, wherein said actuators include an air regulator for controlling the quantity of air flowing into the engine in accordance with prescribed input pulses from said pulse output means, said first plurality of registers includes a register for storing data defining an input pulse interval and a register for storing data defining the pulse duration of said input pulses, and said output means outputs pulses in accordance with the data stored therein.
46. A control apparatus according to claim 43, wherein
said actuators further comprise at least fuel supply means for supplying fuel into engine,
said first plurality of registers includes a register for storing data representative of the duration of fuel supply.
47. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine for which a plurality of sensors produce signals indicative of operating conditions of the engine and adapted to be coupled to at least one actuator for controlling an energy conversion function of the engine;
a control apparatus adapted to receive sensed signals from said sensors and to deliver control signals to said actuator, comprising in combination:
a stage pulse generator for producing a plurality of stage pulses each repeatedly generated at predetermined time intervals;
a plurality of register means connected to said stage pulse generator to receive a stage pulse, one of said register means being selected in response to said stage pulse and delivering data set therein;
a plurality of counter means for counting up signals indicative of conditions of the engine as of a selected instant in the time during which the engine is operative, said counter means being connected to said stage pulse generator to receive a stage pulse which selects one of said counter means to deliver its count value;
a comparator means connected to said register means and counter means to receive the set data of the selected one of said register means and the count value of the selected one of said counter means, and producing an output signal when received one of inputs is equal to or greater than the other; and
an output circuit means connected to said comparator to receive the comparison result, for producing a control signal applied to said actuator.
48. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine for which a plurality of sensor produce signals representative of operating conditions of said engine and being coupled to actuator means for controlling respective energy conversion functions of said engine in response to control signals applied thereto;
an improved control apparatus comprising, in combination:
first means for generating an engine control timing signal pattern;
second means, responsive to processor-generated engine control codes coupled thereto for producing respective engine timing codes the values of which are sequentially modified;
third means, coupled to said second means, for producing respective output signals upon the values of said respective engine timing codes reaching defined limits; and
a plurality of first storage devices coupled to said first means and to said third means, one of said storage devices being selected in accordance with said engine control timing signal pattern for storing output signals of said third means for application to said actuator means.
49. An improved control apparatus according to claim 48, wherein said second means comprises
a plurality of second storage devices for storing respective ones of said engine timing codes, and
means, coupled to said plurality of second storage devices, for controllably modifying the engine timing codes in accordance with said engine control timing signal pattern.
50. An improved control apparatus according to claim 49, wherein said controllably modifying means comprises means, coupled to said first storage devices, for controllably modifying the engine timing codes stored in said plurality of second storage devices in dependence upon the output signals stored said first plurality of storage devices.
51. An improved control apparatus according to claim 50, wherein said controllably modifying means includes a plurality of gate means, coupled to said first means and said plurality of first storage devices, for producing and output in accordance with one of the outputs of said first storage devices which is selected by respective ones of said enging timing codes; and
means for selectively modifying the data value of a respective engine timing code by a prescribed value in response to the output of said gate means.
52. An improved control apparatus according to claim 48, wherein each of said first storage devices has a first terminal, coupled to said third means, for receiving the output of said third means, and a second terminal for receiving a prescribed signal produced by the engine control timing signal pattern.
53. An improved control apparatus according to claim 52, further comprising fourth means for producing a first interval time signal φ1, and wherein said each of said first storage devices further includes gate means, coupled with said first means and said fourth means, for producing said prescribed signal which is applied to said second terminal. .Iadd.
54. For use in a processor-controlled apparatus for controlling the operation of an internal combustion engine for which a plurality of sensors produce signals representative of operating conditions of the engine and being coupled to actuator means which respond to control signals applied thereto for controlling respective energy conversion functions of said engine, an improved control apparatus comprising, in combination:
first means for generating engine control timing signals through which operational events of the engine are controlled;
second means for storing engine control data;
third means for producing sequentially changing engine timing data;
fourth means for comparing respective engine control data stored by said second means with engine timing data produced by said third means in accordance with said engine control timing signals generated by said first means and producing a respective output signal in response to respective engine control data defining a prescribed relationship with respect to engine timing data produced by said third means; and
fifth means for producing a respective control signal to be coupled to an actuator means in response to a respective output signal produced by said fourth means..Iaddend. .Iadd.55. An improved control apparatus according to claim 54, wherein said fifth means comprises:
a plurality of storage means coupled to said first means and the actuator means, one of said storage means being selected in accordance with an engine timing signal for storing signals in response to the output of said fourth means for application to the actuator means..Iaddend. .Iadd.56. An improved control apparatus according to claim 54, wherein said third means comprises a counter..Iaddend. .Iadd.57. An improved control apparatus according to claim 56, wherein said second means comprises a plurality of registers and further wherein said fourth means includes means for comparing engine timing data produced by said counter in common with data respectively stored in each of said plurality of registers..Iaddend. .Iadd.58. An improved control apparatus according to claim 56, further comprising a clock pulse generator coupled to said counter to produce clock pulses for controlling the timing of the generation of said engine
timing data produced by said counter..Iaddend. .Iadd.59. An improved control apparatus according to claim 58, wherein said counter counts each clock pulse generated by said clock pulse generator during a predetermined time interval..Iaddend. .Iadd.60. An improved control apparatus according to claim 59, wherein said clock pulse generator produces said clock pulses in accordance with a timing signal produced by a CPU coupled to said control apparatus..Iaddend. .Iadd.61. An improved control apparatus according to claim 56, further comprising a clock pulse generator coupled to said first means and to said counter to produce clock pulses to commonly control the timing of the generation of the engine control timing signals produced by the first means and the generation of the engine timing data produced by said counter..Iaddend. .Iadd.62. An improved control apparatus according to claim 61, wherein said clock pulse generator produces said clock pulses in accordance with a timing signal produced by a CPU coupled to said control apparatus..Iaddend. .Iadd.63. An improved control apparatus according to claim 54, wherein the fifth means comprises at least a first register and a second register with said first register being coupled to receive the output of said fourth means and said second register being coupled between an output of said first register and said actuator means, and further comprising means for generating first and second clock signals which do not overlap each other wherein said first clock signal is applied to said first register to control entry of output signals from said fourth means to said first register and wherein said second clock signal is applied to said second register to control entry of output signals from said first register into said second register..Iaddend.
Description
CROSS REFERENCE TO RELATED APPLICATIONS

The present application relates to subject matter described in the co-pending applications listed below: U.S. Ser. Nos.

951,509 Filed: Oct. 16, 1978 Shigeki Morinaga et al.Iadd., now abandoned .Iaddend. 952,275 Filed: Oct. 18, 1978 Masao Takato et al.Iadd., now U.S. Pat. No. 4,280,189 .Iaddend.

952,276 Filed: Oct. 18, 1978 Hiroastu Tokuda et al.Iadd., now U.S. Pat. No. 4,277,829 .Iaddend.

952,279 Filed: Oct. 18, 1978 Hiroastu Tokuda et al.Iadd., now U.S. Pat. No. 4,309,759 .Iaddend.

952,326 Filed: Oct. 18, 1978 Masumi Imai et al.Iadd., now U.S. Pat. No. 4,310,889 .Iaddend.

952,531 Filed: Oct. 18, 1978 Masumi Imai et al.Iadd., now U.S. Pat. No. 4,312,038 .Iaddend.

952,532 Filed: Oct. 18, 1978 Hiroastu Tokuda et al.Iadd., now U.S. Pat. No. 4,274,141 .Iaddend.

952,533 Filed: Oct. 18, 1978 Masumi Imai et al.Iadd., now U.S. Pat. No. 4,282,573 .Iaddend.

011,845 Filed: Feb. 13, 1979 Toshio Furuhashi et al.Iadd., now U.S. Pat. No. 4,310,888 .Iaddend.

059,029 Filed: July 19, 1979 Sanshiro Obara et al.Iadd., now U.S. Pat. No. 4,276,602 .Iaddend.

060,751 Filed: July 26, 1979 Toshio Furuhashi et al.Iadd., now U.S. Pat. No. 4,296,722 .Iaddend.

064,431 Filed: Aug. 7, 1979 Toshio Furuhashi.Iadd., now U.S. Pat. No. 4,274,142 .Iaddend.

073,085 Filed: Sept. 6, 1979 Masumi Imai et al.Iadd., now U.S. Pat. No. 4,408,279 .Iaddend.

FIELD OF THE INVENTION

This invention relates to an apparatus for controlling an internal combustion engine for use especially on an automobile.

BACKGROUND OF THE INVENTION

With the continuing demand for automobiles as means of transportation, there have arisen several social problems. Among them are air pollution and the consumption of fossil fuels, especially petroleum.

Some measures have been taken to reduce the amount of harmful substances in exhaust gas, but this has also caused a degradation of the overall efficiency of the internal combustion engine (hereinafter referred to simply as engine). For the purpose of preventing a degradation of the operating efficiency of the engine and improving measures against exhaust gases, an electronic control apparatus has been employed which has an improved precision in control. For example, there have been proposed an electronically controlled fuel injection apparatus and an electronically controlled ignition timing apparatus, and most recently an ignition apparatus controlled by a microprocessor.

The conventional trend in such a control apparatus is toward the mere replacement of mechanical control by an electric one and therefore the individual controlled objects must be provided with the associated electronic control units.

The control of an engine should suppress the harmful components in exhaust gases and operate the engine with a high efficiency. The assembly of the separate electronic control units provided for the controlled objects, e.g. the electronically controlled fuel injection apparatus and the electronically controlled ignition timing apparatus, as described above, provides a poor interrelation among the control units so that a close control of the overall control system is impossible. Moreover, such a composite control system must be accompanied by very complicated circuits. For example, a circuit for detecting the irregular output of a sensor is required such as an angular position sensor.

SUMMARY OF THE INVENTION

The object of this invention is to provide a control apparatus which is a combination of comparatively simple circuits and which is capable of controlling an engine.

According to this invention, input information indicative of the operating conditions of an engine is used and processed through calculations, and plural registers are provided to hold the respective processed contents and to hold data representing the preset values constantly. The common feature of the data held in these registers is that they are used as reference values for a comparison operation. Therefore, the registers mentioned above are referred to hereafter as reference registers constituting a reference register group and the data held in the reference registers is referred to as reference data.

On the other hand, plural registers are provided to hold data representing the instantaneous conditions of the engine and other mechanisms and these registers are referred to hereafter as instantaneous registers constituting an instantaneous register group.

This invention comprises a reference register group, an instantaneous register group, comparison circuits, an incrementor, an incrementor controller, a comparison result holding circuit and a stage counter. According to this invention with the combination of these circuit elements, the stage counter causes the respective stages to be sequentially operated for processing in a predetermined order. For the particular processing in each stage, desired registers are successively selected from among the reference and instantaneous register groups to send the reference data and the instantaneous data from the selected registers to the associated comparison circuit. The result of the comparison, i.e. the output of the comparison circuit, is held in a comparison result holding circuit.

Concerning the stages, the instantaneous data held in each instantaneous register corresponding to a stage is rewritten according to the actually instantaneous condition of the engine or other mechanisms. The rewriting operation is controlled by the incrementor and the incrementor controller.

Namely, the incrementor controller determines whether or not the data representing the angular position of a crank shaft (in this specification, the term "crank shaft" is applied to the rotary shaft of not only a reciprocating engine but also a rotary engine) has increased in accordance with a crank angular position signal and a timing signal. The incrementor then increases the data by a certain unit in accordance with the result of the determination. In this way, the data is renewed continuously and the renewed data is used for actual comparison.

With this constitution, complex control can be realized by a relatively simple circuit configuration and the pulse signals received irregularly are detected after they have been synchronized, so that the pulse signals can be accurately detected and therefore the incrementor can be operated with precision.

The above and other objects, features and advantages of the present invention will be more clear from the following description with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an arrangement plan of sensors and actuators in an embodiment of this invention;

FIG. 2 (A-G) is a diagram for explaining the operation of the circuits shown in FIG. 1;

FIG. 3 shows the detail of the control circuit shown in FIG. 1;

FIG. 4 shows a partial detail of the input/output circuit shown in FIG. 3;

FIG. 5 (A-L) is a diagram for explaining the operation of the circuit shown in FIG. 4;

FIG. 6 shows the detail of the stage counter shown in FIG. 4;

FIG. 7 shows in detail concrete examples of the reference and the instantaneous register groups shown in FIG. 4;

FIG. 8 shows in detail concrete examples of the first and the second comparison output register groups 502 and 504;

FIG. 9 shows in detail a synchronizing circuit:

FIG. 10 (A-I) is a diagram for explaining the operation of the circuit shown in FIG. 9;

FIG. 11 shows in detail a concrete example of the incrementor 478 shown in FIG. 4;

FIGS. 12A and 12B show in detail an incrementor controller;

FIG. 13 (A-E) shows the waveforms useful in explaining the processing of the fuel injection signal;

FIG. 14 (A-F) shows the waveforms useful in explaining the ignition timing control;

FIG. 15 (A-C) shows the waveforms useful in explaining the processing by EGR or NIDL; and

FIG. 16 (A-D) shows the signal waveform useful in explaining the detection of the rotational speed RPM of engine or the speed VSP of vehicle.

DETAILED DESCRIPTION

The present invention will now be described by way of one embodiment with the aid of attached drawings. FIG. 1 shows the main structure of an electronic engine control apparatus. Air sucked in through an air cleaner 12 is passed through an air-flow meter 14 to measure the flow rate thereof and the air-flow-meter 14 delivers an output QA indicating the flow rate of air to a control circuit 10. A temperature sensor 16 is provided in the air-flow meter 14 so as to detect the temperature of the sucked air and the output TA of the sensor 16, indicating the temperature of the sucked air, is also supplied to the control circuit 10.

The air flowing through the air-flow meter 14 is further passed through a throttle chamber 18, an intake manifold 26 and a suction or intake valve 32 to the combustion chamber 34 of an engine 30. The quantity of air drawn into the combustion chamber 34 is controlled by changing the aperture of a throttle valve 20 provided in the throttle chamber 18 and interlocked with an accelerator pedal 22. The aperture or opening of the throttle valve 20 is detected by detecting the valve position of the throttle valve 20 by a throttle valve position detector 24 and the signal QTH representing the valve position of the throttle valve 20 is supplied from the throttle valve position detector 24 to the control circuit 10.

The throttle chamber 18 is provided with a bypass 42 for idling the engine and an idle adjust screw 44 for adjusting the flow of air through the bypass 42. When the throttle valve 20 is completely closed, the engine is operated in the idling condition. The sucked air past the air-flow meter flows via the bypass 42 and drawn into the combustion chamber 34. Accordingly, the flow of the air sucked in under the idling condition is changed by adjusting the idle adjust screw 44. The energy created in the combustion chamber 34 is determined substantially depending on the flow rate of the air drawn through the bypass 42 so that the rotational speed of the engine under the idling condition can be adjusted to be optimal by controlling the flow rate of air drawn into the combustion chamber by adjusting the idle adjust screw 44.

The throttle chamber 18 is also provided with another bypass 46 and an air regulator 48. The air regulator 48 controls the flow rate of the air through the bypass 46 in accordance with the output signal NIDL of the control circuit 10, so as to control the rotational speed of the engine during the warming-up operation and to properly supply air into the combustion chamber at a sudden change, especially a sudden closing, in the valve position of the throttle valve 20. The air regulator 48 can also change the flow rate of air during the idling operation.

Next, the fuel supply system will be described. Fuel stored in a fuel tank 50 is sucked out to a fuel damper 54 by means of a fuel pump 52. The fuel damper 54 absorbs the pressure undulation of the fuel supplied from the fuel pump 52 so that fuel having a constant pressure can be supplied through a fuel filter 56 to a fuel pressure regulator 62. The fuel past the fuel pressure regulator 62 is sent by pressure to a fuel injector 66 through a fuel pipe 60 and the output INJ of the control circuit 10 causes the fuel injector 66 to be actuated to inject the fuel into the intake manifold 26.

The quantity of the fuel injected by the fuel injector 66 is determined by the period during which the fuel injector 66 is opened and by the difference between the pressure of the fuel supplied to the injector and the pressure in the intake manifold 26 into which the pressurized fuel is injected. It is however preferable that the quantity of the injected fuel should depend only on the period for which the injector is opened and which is determined by the signal supplied from the control circuit 10. Accordingly, the pressure of the fuel supplied by the fuel pressure regulator 62 to the fuel injector 66 is controlled in such a manner that the difference between the pressure of the fuel supplied to the fuel injector 66 and the pressure in the intake manifold 26 is always kept constant during any driving condition. The pressure in the intake manifold 26 is applied to the fuel pressure regulator 62 through a pressure conducting pipe 64. When the pressure of the fuel in the fuel pipe 60 exceeds the pressure upon the regulator 62 by a predetermined level, the fuel pipe 60 communicates with a fuel return pipe 58 so that the excessive fuel corresponding to the excessive pressure is returned through the fuel return pipe 58 to the fuel tank 50. Thus, the difference between the pressure of the fuel in the fuel pipe 60 and the pressure in the intake manifold 26 is kept always constant.

The fuel tank 50 is also provided with a pipe 68 connected to a canister 70 provided for the suction of vaporized fuel or fuel gas. When the engine is operating, air is sucked in through an open air inlet 74 to send the fuel gas into the intake manifold 26 and therefore into the engine 30 via a pipe 72. In the case of a stopped engine, the fuel gas is exhausted through active carbon filled in the canister 70.

As described above, the fuel is injected by the fuel injector 66, the suction valve 32 is opened in synchronism with the motion of a piston 75, and a mixture gas of air and fuel is sucked into the combustion chamber 34. The mixture gas is compressed and fired by the spark generated by an ignition plug 36 so that the energy created through the combustion of the mixture gas is converted to mechanical energy.

The exhaust gas produced as a result of the combustion of the mixture gas is discharged into the open air through an exhaust valve (not shown), an exhaust pipe 76, a catalytic converter 82 and a muffler 86. The exhaust pipe 76 is provided with an exhaust gas recycle pipe 78 (hereafter referred to as an EGR pipe), through which a part of the exhaust gas is fed into the intake manifold 26, that is, the part of the exhaust gas is circulated to the suction side of the engine. The quantity of the circulated exhaust gas is determined depending on the aperture of the valve of an exhaust gas recycle apparatus 28. The aperture is controlled by the output EGR of the control circuit 10 and the valve position of the apparatus 28 is converted to an electric signal QE to be supplied as an input to the control circuit 10.

A λ sensor 80 is provided in the exhaust pipe 78 to detect the fuel-air mixture ratio of the mixture gas sucked into the combustion chamber 34. An oxygen sensor (O2 sensor) is usually used as the λ sensor 80 and detects the concentration of oxygen contained in the exhaust gas so as to generate a voltage V.sub.λ corresponding to the concentration of the oxygen contained in the exhaust gas. The output V.sub.λ of the λ sensor 80 is supplied to the control circuit 10. The catalytic converter 82 is provided with a temperature sensor 84 for detecting the temperature of the exhaust gas in the converter 82 and the output TE of the sensor 84 corresponding to the temperature of the exhaust gas in the converter 84 is supplied to the control circuit 10.

The control circuit 10 has a negative power source terminal 88 and a positive power source terminal 90. The control circuit 10 supplies the signal IGN, for causing the ignition plug 36 to spark, to the primary winding of an ignition coil 40. As a result, a high voltage is induced in the secondary winding of the ignition coil 40 and supplied through a distributor 38 to the ignition plug 36 so that the plug 36 fires to cause the combustion of the mixture gas in the combustion chamber 34. The mechanism of the firing of the ignition plug 36 will be further detailed. The ignition coil 40 has a positive power source terminal 92 and the control circuit 10 also has a power transistor for controlling the primary current through the primary winding of the ignition coil 40. The series circuit of the primary winding of the ignition coil 40 and the power transistor is connected between the positive power source terminal 92 of the ignition coil 40 and the negative power source terminal 88 of the control circuit 10. When the power transistor is conducting, electromagnetic energy is stored in the ignition coil 40 and when the power transistor is cut off, the stored electromagnetic energy is released as a high voltage to the ignition plug 36.

The engine 30 is provided with a temperature sensor 96 for detecting the temperature of the water 94 as coolant in the water jacket and the temperature sensor 96 delivers to the control circuit 10 a signal TW corresponding to the temperature of the water 94. The engine 30 is further provided with an angular position sensor 98 for detecting the angular position of the rotary shaft of the engine and the sensor 98 generates a reference signal PR in synchronism with the rotation of the engine, e.g. every 120° of the rotation, and an angular position signal each time the engine rotates through a constant, predetermined angle (e.g. 0.5°). The reference signal PR and the angular position signal PC are both supplied to the control circuit 10.

In the system shown in FIG. 1, the air-flow meter 14 may be replaced by a negative pressure sensor. Such a negative pressure sensor 100 is depicted by dashed line and the negative pressure sensor 100 will supply to the control circuit 10 a voltage VD corresponding to the negative pressure in the intake manifold 26. A semiconductor negative pressure sensor is practically used as such a negative pressure sensor 100. One side of the silicon chip of the semiconductor is acted on by the boost pressure of the intake manifold while the atmospheric or a constant pressure is exerted on the other side of the chip. The constant pressure may be vacuum as the case may be. With this construction, a voltage VD corresponding to the pressure in the intake manifold is generated, which is to be supplied to the control circuit 10.

FIG. 2 illustrates the relationships between the firing timing and the crank angular position and between the fuel injection timing and the crank angular position, where a six-cylinder engine is used. In FIG. 2, diagram A represents the crank angular position and indicates that a reference signal PR is delivered by the angular position sensor 98 every 120° of the crank angle. The reference signal PR is therefore supplied to the control circuit 10 at 0°, 120°, 240°, 360°, 480°, 600°, 720° etc. of the angular position of the crank shaft.

Diagrams B, C, D, E, F and G correspond respectively to the 1st cylinder, the 5th cylinder, the 3rd cylinder, the 6th cylinder, the 2nd cylinder and the 4th cylinder. J1 -J6 designate respectively the periods for which the suction valves of the corresponding cylinders are open. The periods are shifted by 120° of crank angle from one another. The beginning and the durations of the periods at which the suction valve is open are generally as shown in FIG. 2 through somewhat different depending upon the type of engine used.

A1 -A5 indicates the periods for which the valve of the fuel injector 66 is open, i.e. fuel injection periods. The lengths JD of the periods A1 -A5 can be considered to be the quantities of fuel injected at a time by the fuel injectors 66. The injectors 66, provided for the respective cylinders, are connected in parallel with the drive circuit in the control circuit 10. Accordingly, the signal INJ from the control circuit 10 opens the valves of the fuel injectors 66 simultaneously so that all the fuel injectors 66 simultaneously inject fuel. Now, the first cylinder will be taken as an example for description. The output signal INJ from the control circuit 10 is applied to the fuel injectors 66 provided respectively in the manifold or inlet ports of the respective cylinders in timing with the reference signal INTIS generated at 360° of crank angle. As a result, fuel is injected in by the injector 66 for the length JD of time calculated by the control circuit 10, as shown as A2 in FIG. 2. However, since the suction valve of the 1st cylinder is closed, the injected fuel at A2 is not sucked into the 1st cylinder, but kept stagnant near the inlet port of the 1st cylinder. In response to the next reference signal INTIS generated at 720° of crank angle, the control circuit 10 again sends a signal to the respective fuel injectors 66 to perform the fuel injections as shown at A3 in FIG. 2. Simultaneously almost with the fuel injections, the suction valve of the 1st cylinder is opened to cause the fuel injected at A2 and the fuel injected at A3 to be sucked into the combustion chamber of the 1st cylinder. The other cylinders will be also subjected to similar series of operations. For example, in case of the 5th cylinder corresponding to the diagram C, the fuel injected at A2 and A3 is sucked in at the period J5 for which the suction valve of the 5th cylinder is opened. In case of the 3rd cylinder corresponding to the diagram D, a part of the fuel injected at A2, the fuel injected at A3 and a part of the fuel injected at A4 are sucked in together while the suction valve is open for the period J3. The part of the fuel injected at A2 plus the part of the fuel injected at A4 equals a quantity of fuel injected by a fuel injector at a single actuation. Therefore, also during the suction step of the 3rd cylinder, the quanity of fuel equal to the total quantities supplied through double actuations of the fuel injector will be sucked in. Also, in case of the 6th, 2nd or 4th cylinder as shown in the diagram E, F or G, the double quantity of fuel is sucked in during a single step of suction. As apparent from the above description, the quantity of fuel determined by the fuel injection signal INJ from the control circuit 10 is equal to half the quantity of fuel to be sucked into the combustion chamber. Namely, the necessary quantity of fuel corresponding to the quantity of air sucked into the combustion chamber 34 will be supplied through the double actuations of the fuel injector 66.

Throughout the diagrams A to G in FIG. 2, G1 -G6 indicate the ignition times associated respectively with the 1st to 6th cylinders. When the power transistor provided in the control circuit 10 is cut off, the primary current of the ignition coil 40 is interrupted so that a high voltage is induced across the secondary winding. The induction of the high voltage takes place in timing with the ignition epochs G1, G5, G3, G6, G2 and G4. The induced high voltage is distributed to the spark plugs provided in the respective cylinders by means of a distributor 38. Accordingly, the spark plugs of the 1st, 5th, 3rd, 6th, 2nd and 4th cylinders fire successively in this order to inflame the combustible mixture of fuel and air.

FIG. 3 shows an example of the detail of the control circuit 10 shown in FIG. 1. The positive power source terminal 90 of the control circuit 10 is connected with the positive electrode 110 of a battery to provide a voltage VB for the control circuit 10. The power source voltage VB is adjusted to a constant voltage PVCC of, for example, 5 volts by a constant voltage circuit 112. This constant voltage PVCC is applied to a central processor unit (hereinafter referred to as CPU), a random access memory (hereafter referred to as RAM) and a read-only memory (hereafter referred to as ROM). The output PCVV of the constant voltage circuit 112 is supplied also to an input/output circuit 120.

The input/output circuit 120 includes therein a multiplexer 122, an analog-digital converter 124, a pulse output circuit 126, a pulse input circuit 128 and a discrete input/output circuit 130.

The multiplexer 122 receives plural analog signals, selects one of the analog signals in accordance with the instruction from the CPU, and sends the selected signal to the A/D converter 124. The analog signal inputs applied through filters 132 to 144 to the multiplexer 122 are the outputs of the various sensors shown in FIG. 1; the analog signal TW from the sensor 96 representing the temperature of the cooling water in the water jacket of the engine, the analog signal TA from the sensor 16 representing the temperature of the sucked air, the analog signal TE from the sensor 84 representing the temperature of the exhaust gas, the analog signal QTH from the throttle aperture detector 24 representing the aperture of the throttle valve 20, the analog signal QE from the exhaust recycle apparatus 28 representing the aperture of the valve of the apparatus 28, the analog signal V.sub.λ from the λ sensor 80 representing the air-excess rate of the sucked mixture of fuel and air, and the analog signal QA from the air-flow meter 14 representing the flow rate of air. The output V80 of the λ sensor 80 above is supplied through an amplifier with a filter circuit to the multiplexer 122.

The analog signal VPA from an atmospheric pressure sensor 146 representing the atmospheric pressure is also supplied to the multiplexer 122. The voltage VB is applied from the positive power source terminal 90 to a series circuit of resistors 150, 152 and 154 through a resistor 160. The series circuit of the resistors 150, 152 and 154 is shunted with a Zener diode 148 to keep the voltage across it constant. To the multiplexer 122 are applied the voltages VH and VL at the junction points 156 and 158 respectively between the resistors 150 and 152 and between the resistors 152 and 154.

The CPU 114, the RAM 116, the ROM 118 and the input/output circuit 120 are interconnected respectively by a data bus 162, an address bus 164 and a control bus 166. A clock signal E is supplied from the CPU to the RAM, ROM and input/output circuit 120 and the data transfer takes place through the data bus 162 in timing with the clock signal E.

The multiplexer 122 of the input/output circuit 120 receives as its analog inputs the cooling water temperature TW, the temperature TA of the sucked air, the temperature TE of the exhaust gas, the throttle valve aperture QTH, the quantity QE of recycle exhaust gas, the output V80 of the λ sensor, the atmospheric pressure VPA, the quantity QA of the sucked air and the reference voltages VH and VL. The quantity QA of the sucked air may be replaced by the negative pressure VD in the intake manifold. The CPU 114 specifies the address of each of these analog inputs through the address bus 164 in accordance with the instruction program stored in the ROM 118 and the analog input having a specified address is taken in. The analog input taken in is sent through the multiplexer 122 to the analog/digital converter 124 and the output of the converter 124, i.e., the digital-converted value, is held in the associated register. The stored value is coupled, if desired, to the CPU 114 or RAM 116 in response to the instruction sent from the CPU 114 through the control bus 166.

The pulse input circuit 128 receives as inputs a reference pulse signal PR and an angular position signal PC both in the form of a pulse train from the angular position sensor 98 through a filter 168. A pulse train of pulses PS having a repetition frequency corresponding to the speed of the vehicle is supplied from a vehicle speed sensor 170 to the pulse input circuit 128 through a filter 172. The signals processed by the CPU 114 are held in the pulse output circuit 126. The output of the pulse output circuit 126 is sent to a power amplifying circuit 186 and the fuel injector 66 is controlled by the output signal of the power amplifying circuit 186.

Power amplifying circuits 188, 194 and 198 respectively control the primary current of the ignition coil 40, the aperture of the exhaust recycle apparatus 28 and the aperture of the air regulator 48 in accordance with the output pulses of the pulse output circuit 126. The discrete input/output circuit 130 receives signals from a switch 174 for detecting the completely closed state of the throttle valve 20, from a starter switch 176, and from a gear switch 178 indicating that the transmission gear is in the top position, respectively through filters 180, 182 and 184 and holds the signals. The discrete input/output circuit 130 also receives and holds the processed signals from the central processor unit CPU 114. The discrete input/output circuit 130 treats the signals the content of each of which can be represented with a single bit. In response to the signal from the central processor unit CPU 114, the discrete input/output circuit 130 sends signals respectively to the power amplifying circuits 196, 200, 202 and 204 so that the exhaust recycle apparatus 28 is closed to stop the recycle of exhaust gas, the fuel pump is controlled, the abnormal temperature of the catalyzer is indicated by a lamp 208 and the overheat condition of the engine is displayed by a lamp 210.

FIG. 4 shows in detail a concrete example of the pulse output circuit 126. A register group 470 comprises reference registers which serve to hold the data processed by the CPU 114 and the data representing the predetermined fixed values. These pieces of data are transferred from the CPU 114 to the reference register group 470 through the data bus 162. Each of the registers is specified through the address bus 164 to receive and hold the associated data.

A register group 472 comprises instantaneous registers which serve to hold the instantaneous states of the engine and the associated mechanisms. The instantaneous register group 472, a latch circuit 476 and an incrementor 478 form a counter.

An output register group 474 comprises, for example, a register 430 for holding the rotational speed of the engine and a register 432 for holding the vehicle speed. The registers 430 and 432 hold the values by taking in the contents of the instantaneous registers when certain conditions are satisfied. Each register of the output register group 474 is selected by the signal sent from the CPU 114 through an address bus and the content of the selected register is sent to the CPU 114 through the data bus 162.

A comparator 480 receives, for comparison, at its input terminals 482 and 484 the reference data from selected registers of the reference register group and the instantaneous data from selected registers of the instantaneous register group. The result of the comparison by the comparator 480 is delivered at its output terminal 486. The output delivered at the output terminal 486 is set in the selected registers of a first comparison output register group 502 serving as a comparison result holding circuit, and then set in the corresponding registers of a second comparison output register group 504.

The operations of accessing, i.e. reading out of or writing in, the reference register group 470, the instantaneous register group 472 and the output register group 474, the operations of the incrementor 478 and the comparator 480, and the operations of setting the output of the comparator 480 in the first and second comparison output register groups 502 and 504 are all processed within a predetermined period of time. Other various processing operations are performed in a time sequential manner or in a time-division manner in accordance with the order of the stages instructed by a stage counter 572. In each stage, one of the registers constituting the reference register group 470, one of the registers of the instantaneous register group 472, one of the registers of the first comparison result register group 502, one of the registers of the second comparison result register group 504 and, if necessary, one of the registers of the output register groups 474 are selected. The incrementor 478 and the comparator 480 are used in common.

FIG. 5 shows diagrams useful in explaining the operation of the circuit in FIG. 4. The clock signal E, shown in the diagram A, is supplied from the CPU 114 to the input/output circuit 120. Two clock signals φ1 and φ2, as shown in the diagram B and C, having no overlap with each other are derived from the clock signal E by means of a pulse generating circuit 574. The circuit shown in FIG. 4 is operated by these clock signals φ1 and φ2.

The diagram D in FIG. 5 depicts a stage signal which is switched over during the rising transient of the clock signal φ2. The processing in each stage is performed in synchronism with the clock signal φ2. In FIG. 5, "THROUGH" indicates that the latch circuit and the register circuits are in their enabled conditions and that the outputs of these circuits depend on the inputs thereto. Also, "LATCH" means that these circuits hold certain data and that the outputs therefrom are independent of the inputs thereto.

The stage signal shown in the diagram D serves to read data out of the reference register group 470 and the instantaneous register group 472, that is, to read out the contents of certain selected registers of the groups. The diagrams E and F represent the operations of the reference and instantaneous register groups 470 and 472, respectively. These operations are performed in synchronism with the clock signal φ1.

The diagram G indicates the operation of the latch circuit 476. The latch circuit 476 is in the THROUGH state when the clock signal φ2 is at high level, serving to take in the content of a particular register selected from among the instantaneous register group 472. When the clock signal φ2 is at low level, on the other hand, the latch circuit 476 is in the LATCH state. Thus, the latch circuit 476 serves to hold the content of the specific register of the instantaneous register group selected in accordance with the stage assumed then. The data held in the latch circuit 476 is increased or not on the basis of external conditions by means of the incrementor 478 operated out of timing with the clock signal.

The incrementor 478 performs the following functions in response to the signal from the incrementor controller 490. The first function is the function of incrementing, to increase by unity the value of the input data. The second is the function of non-incrementing, to pass the input without any change. The third is the function of resetting, to change the entire input into data representing the value 0 (zero).

As seen from the flow of data through the instantaneous register group 472, one register of the group 472 is selected by the stage counter 572 and the data held by the selected register is supplied to the comparator 480 through the latch circuit 476 and the incrementor 478. Further, there is provided a return loop for the signal from the output of the incrementor 478 to the selected register, a complete closed loop being formed. Therefore, since the incrementor has a function of increasing the data by unity, the closed loop functions as a counter. However, if the data delivered from the particular register selected from the instantaneous register group is again received by the particular register as an input by coming back through the return loop, an erroneous operation will easily take place. The latch circuit 476 is provided to block unwanted data. Namely, the latch circuit 476 assumes the THROUGH state in timing with the clock signal φ2 while the THROUGH state in which input data is to be written in the instantaneous registers is in timing with the clock signal φ1. Therefore, data is interrupted or cut at the offset between the clock signals φ1 and φ2. Namely, even if the content of any specific register of the group 472 is changed, the output of the latch circuit 476 remains unchanged.

The comparator 480, just like the incrementor 478, operates out of timing with the clock signals. The comparator 480 receives as its inputs the data held in a register selected from among the reference register group 470 and the data held in a register selected from among the instantaneous register group 472 and sent through the latch circuit 476 and the incrementor 478. The result of the comparison of both data is set in the first comparison result register group 502 which takes the THROUGH state in timing with the clock signal φ1. The set data is further set in the second comparison result register group 504 which assumes the THROUGH state in synchronism with the clock signal φ2. The outputs of the register group 504 are the signals for controlling the various functions of the incrementor and the signals for driving the fuel injectors, the ignition coil and the exhaust gas recycle apparatus.

Also, in response to the signals, the results of the measurements of the rotational speed of the engine and the vehicle speed are transferred from the instantaneous register group 472 to the output register group 474 in every stage. For example, in the case of writing the rotational speed of the engine, a signal indicating that a preset time has elapsed is held in the register RPMWBF 552 of the second comparison result register group 504 and the data held in the register 462 of the instantaneous register group 472 is transferred to the register 430 of the output register group 474 in response to the output of the register 552 in the RPM stage listed in the table 1 given later.

On the other hand, unless a signal indicating the elapse of the preset time is set in the register RPMWBF 552, the operation to transfer the data held in the register 462 to the register 430 never takes place even in the RPM stage.

The data held in the register 468 of the group 472 and representing the vehicle speed VSP is transferred to the output register 432 of the group 474 in response to the signal from the register VSPWBF 556 of the group 504 in the VSP stage.

The writing of the data representing the rotational speed RPM of the engine or the vehicle speed VSP in the output register group 474 is performed as follows. Reference should be had again to FIG. 5. When the stage signal STG is in the RPM or VSP mode, the data from the register 462 or 468 of the instantaneous register group 472 is written in the latch circuit 476 if the clock signal φ2 is at a high level since the latch circuit 476 takes the THROUGH state when the clock signal φ2 is at high level. And when the clock signal φ2 is at low level, the written data is in the latched state. The thus held data is then written in the output register group 474 in timing with the high level of the clock signal φ1 in response to the signal from the register RPMWBF 552 or VSPWBF 556 since the output register group 474 assumes the THROUGH state when the clock signal φ1 is at high level, as indicated at the diagram K of FIG. 5. The written data is latched at the low level of the clock signal φ1.

In the case of reading the data held in the output register group 474 by the CPU 114, the CPU 114 first selects one of the registers 430 and 432 of the group 474 through the address bus 164 and then takes in the content of the selected register in timing with the clock signal E shown in the diagram A of FIG. 5.

FIG. 6 shows an example of a circuit for generating the stage signal STG shown in the diagram D of FIG. 5. The contents of a stage counter SC570 are incremented in response to the signal φ1 sent from the pulse generating circuit 574 which is per se well-known. The outputs C0 -C6 of the stage counter SC570 and the outputs of the T register shown in FIG. 4 are supplied as inputs to a stage decoder SDC. The stage decoder SDC delivers as its outputs signals 01-017 and the signals 01-017 are written in a stage latch circuit STGL in timing with the clock signal φ2.

The reset input terminal of the stage latch circuit STGL receives a signal GO of bit 2° from the mode register shown in FIG. 4 and when the signal GO of bit 2° takes its low level, all the outputs of the stage latch circuit STGL are at the low level to stop all the processing operations. If, on the other hand, the signal GO resumes the high level, the stage signals STG are successively delivered again in the predetermined order to perform the corresponding processings.

The above stage decoder SDC can be easily realized by the use of, for example, a ROM (read-only memory). The table 1 given below lists up the details of the contents 00-7F of the stage signals STG delivered as outputs from the stage latch circuit STGL.

                                  TABLE 1__________________________________________________________________________HexadecimalC3 -C6C0 -C2    0   1    2   3    4   5   6   7__________________________________________________________________________0   EGRP   NIDLP        --  RPMW ENST                     --  --  --1   INTL   INTL INTL            INTL INTL                     INTL                         INTL                             INTL2   CYL CYL  CYL CYL  CYL CYL CYL CYL3   ADV ADV  ADV ADV  ADV ADV ADV ADV4   DWL DWL  DWL DWL  DWL DWL DWL DWL5   VSP VSP  VSP VSP  VSP VSP VSP VSP6   RPM RPM  RPM RPM  RPM RPM RPM RPM7   INJ INJ  INJ INJ  INJ INJ INJ INJ__________________________________________________________________________C3 -C6C0 -C2    8   9    A   B    C   D   E   F__________________________________________________________________________0   EGRD   NIDLD        --  VSPW INTV                     --  --  --1   INTL   INTL INTL            INTL INTL                     INTL                         INTL                             INTL2   CYL CYL  CYL CYL  CYL CYL CYL CYL3   ADV ADV  ADV ADV  ADV ADV ADV ADV4   DWL DWL  DWL DWL  DWL DWL DWL DWL5   VSP VSP  VSP VSP  VSP VSP VSP VSP6   RPM RPM  RPM RPM  RPM RPM RPM RPM7   INJ INJ  INJ INJ  INJ INJ INJ INJ__________________________________________________________________________

First, a general reset signal GR is received at the reset terminal R of the stage counter SC570 shown in FIG. 6 so that all the outputs C0 -C6 of the stage counter SC570 become "0" (zero). The general reset signal is delivered from the CPU at the time of starting the control circuit 10. Under the above condition, if the clock signal φ2 is received, a stage signal EGRPSTG is delivered in timing with the rising transcient of the signal φ2. According to the stage signal EGRPSTG, a processing EGRP is performed. Upon reception of a pulse of the clock signal φ1, the stage counter SC570 counts up to increase its content by unity and then the arrival of the clock signal φ2 causes the next stage signal INTLSTG to be delivered. A processing INTL is performed according to the stage signal INTLSTG. Thereafter, a stage signal CYLSTG is delivered for the execution of a processing CYL and then a stage signal ADVSTG for a processing ADV. In like manner, as the stage counter SC570 continues to count up in timing with the clock signal φ1, other stage signals STG are delivered in timing with the clock signal φ2 and the processings according to the stage signals STG are executed.

When all the outputs C0 -C6 of the stage counter SC570 become "1", a stage signal INJSTG is delivered for the execution of a processing INJ, which terminates the whole processings listed in the above table 1. Upon reception of the next clock signal φ1, all the outputs C0 -C6 of the stage counter SC570 becomes zero and the stage signal EGRPSTG is delivered again for the execution of the processing EGRP. In this way, the processings listed in the table 1 will be repeated.

The processings in the respective stages, listed in the table 1 will be detailed in the following table 2.

              TABLE 2______________________________________Stage    Type of Processing Operation Corresponding toSignal   Stage Signal______________________________________EGRPSTG  to determine whether or not the period of time    determined by the data held in the register    418 has elapsed, so as to determine the period    of the pulse current for driving the valve    of the exhaust gas recycle apparatus.INTLSTG  to determine whether or not the engine has    rotated through an angle corresponding to the    data held in the register 406, on the basis    of the reference signal PR from the angular    position sensor, so as to generate a reference    signal INTLS.CYLSTG   to determine whether or not the reference signals    INTLS represented by the data held in the    register 404 have been generated, so as to    generate a signal CYL indicating a single    rotation of the crank shaft.ADVSTG   to determine whether or not the engine has    rotated through an angle corresponding to    the data held in the register 414, on the    basis of the reference signal, so as to    generate an ignition timing signal.DWLSTG   to determine whether or not the engine has    rotated through an angle corresponding to    the data held in the register 416, after    the generation of the immediately previous    reference signal, so as to generate a signal    indicating the initial conduction point of    the primary current through the ignition    coil.VSPSTG   to hold, for detecting the vehicle speed,    the data corresponding to the actually    measured vehicle speed in the output register    when the lapse of a predetermined period    of time is ascertained on the basis of the    signal (output of VSPWBF) representing the    lapse of the predetermined period of time and    to continue to further count the vehicle    speed pulses when the predetermined period    of time has not yet elapsed.RPMSTG   to hold, for detecting the rotational speed    of the engine, the data corresponding to    the actually measured vehicle speed in the    output register when the lapse of a predeter-    mined period of time is ascertained on the    basis of the signal (output of RPMBF) represent-    ing the lapse of the predetermined period    of time and to continue to further count    the angular position signals when the pre-    determined period of time has not yet elapsed.INJSTG   to determine whether or not the time    corresponding to the data held in the register    412 has elapsed, on the basis of the signal CYL, so    as to produce a signal INJ representing the    valve opening period for the fuel injector.NIDLPSTG to determine whether or not the time    corresponding to the data held in the register    422 has elapsed, so as to determine the period    of the pulse current for driving the air regulator.RPMWSTG  to determine whether or not a predetermined    period of time for which the pulses synchronous    with the rotation of the engine are to be    counted has elapsed, so as to measure the    rotational speed of the engine.ENSTSTG  to detect the condition that there is no    signal delivered from the angular position    sensor for a preset period of time, so as    to detect an accidental stopping of engine.EGRDSTG  to determine whether or not the duration of the    pulse of the pulse current for driving the    valve of the exhaust gas recycle apparatus    has become coindicent with the value corres-    ponding to the data held in the register 420.NIDLDSTG to determine whether or not the pulse duration    of the pulse current for driving the air    regulator has become coincident with the value    corresponding to the data held in the register    424.VSPWSTG  to determine whether or not a preset period of    time for which the pulses synchronous with    the vehicle speed are to be counted has lapsed,    so as to measure the vehicle speed.INTVSTG  to determine whether or not the period of time    corresponding to the data held in the register    408 has elapsed.______________________________________

In the stage latch circuit STGL shown in FIG. 6, the circuit components associated with the output signals STG0 and STG7 serve to synchronize externally supplied signals with the clock signal produced in the input/output circuit 120. The output STG0 is delivered when all the outputs C0 -C2 of the stage counter SC570 are zero "0" while the output STG7 is delivered when all the outputs C0 -C2 are one "1".

Examples of the external signals are the reference signal PR generated in timing with the rotation of the engine, the angular position signal and the vehicle speed pulse signal PS generated in synchronism with the rotation of the wheel. The periods of these signals, which are pulse signals, vary to a considerable extent and therefore the signals, if not controlled, are by no means synchronous with the clock signals φ1 and φ2. Accordingly, there is no determination of whether the increment operation is performed or not, in the stage ADVSTG, VSPSTG or RPMSTG in the table 1.

It is therefore necessary to synchronize the external pulse signal, for example, a sensor and the stage of the input/output circuit. For the improvement in the detection accuracy, the angular position signal PC and the vehicle speed signal PS must have their rising and falling transient synchronized with the stage while the reference signal PR must have its rising edge synchronized with the stage.

FIG. 7 shows the details of the register groups 470 and 472.

First, the input of data to the reference register group will be described. Input data is supplied to a latch circuit 802 through the data bus 162. Simultaneously, a read/write signal R/W and a signal VMA are supplied from the CPU through the control bus 166. The register in the input/output circuit are selected through the address bus 164. As is well known, a technique of selecting the registers is to decode the data sent through the address bus into the signals corresponding to the respective registers and the decoding is effected by an Address Decoder 804. The outputs of the decoder 804 are connected with the registers specified by the sumbols labeled at the respective outputs (wiring is omitted). In accordance with the above mentioned read/write signal R/W, signal VMA and the address bus bit A15 corresponding to the input/output circuit, the select chip write and the select chip read signals CSW and CSR are sent through gates 806 and 808 respectively.

In the case of the writing of the data from the CPU, the select chip write signal CSW is delivered and applied to the input side of the registers. Now, the select chip read signal CSR is not delivered and therefore the gate 810 is closed and the tri-state buffer 812 is closed.

The data sent through the data bus 162 is latched by the latch circuit WDL 802 in timing with the clock signal φ2. The data latched in the latch circuit 802 is transferred through the write bus driver WBD to the respective registers of the reference register group 470 and written in the registers selected by the address decoder in timing with the signal φ1. The registers 408, 410, 412, 414, 416, 426 and 428 of the group 470 have 10 bits each and both the CPU and the data bus are designed to treat data of 8 bits, so that the upper two bits and the lower eight bits of the ten-bit data are given two different addresses. Accordingly, the transfer of data to the 10-bit register takes place twice per data.

On the other hand, the reading process is contrary to this. The chip select gate 808 is selected by the output sent through the control bus and the buffer 812 is opened by the output of the gate 810 in timing with the signal E. Since at this time a desired register is selected by the address signal sent through the address bus 164, the data in the selected register is delivered through the tri-state (three-state) buffer 812 onto the data bus 162.

Next, description will be made of the operation to select the reference register and the instantaneous register in accordance with the stage signal. The reference and instantaneous register groups 470 and 472 receive the stage signals. In response to the stage signals, the corresponding registers are selected in the respective stages. Of the reference register group 470, the registers 412, 414 and 416 do not receive the stage signals and therefore are not selected, when the corresponding outputs INJBF, ADVBF and DWLBF are delivered from the comparison result holding register group 504. Instead, when the signals INJBF, ADVBF and DWLBF are received, the zero register 402 is selected in the stages INJ, ADV and DWL. Concerning the instantaneous register group 472, the register 456 receives the stage signals EGRP and EGRD and the register 458 receives the stage signals NIDLP and NIDLD. Thus, the register 456 is selected together with the reference register 418 or 420 in the stage EGRPSTG or EGRDSTG, respectively. And the register 458 is selected together with the reference register 422 or 424 in the stage NIDLPSTG or NIDLDSTG, respectively.

FIG. 8 shows in detail the first and second comparison output register groups 502 and 504 shown in FIG. 4. The output of the comparator 480 is divided into a signal indicating an EQUAL condition and a signal indicating a LARGER condition and both the signals are sent to the NOR gate 832. Accordingly, the output of the NOR gate 832 indicates an EQUAL OR LARGER condition. Since the NAND gate 830 receives the EQUAL signal from the comparator 480 and the signal for selecting the ZERO register 402, the signal indicating the EQUAL condition is blockied by the NAND gate 830 is the ZERO register 402 is selected. As a result, the output of the NOR gate 832 is only the signal indicating the LARGER condition. It is necessary to select the respective registers of the first comparison output register group 502 in timing with the respective registers of the reference and instantaneous register groups. Therefore, the registers of the group 502 receives the clock signal φ1 and the corresponding stage signals to be set in synchronism with the corresponding reference and instantaneous registers. As a result, the result of comparison made in each stage is latched in the associated register of the first comparison output register group in timing with the clock signal φ1. Since the second comparison output register group 504 receives the clock signal φ2 for its set timing, the above result of comparison is set in the second comparison output register group in timing with the clock signal φ2 delayed with respect to the clock signal φ1. Then, the registers of the group 504 deliver their respective BF outputs.

The registers 512, 528, 552, 556, 516 and 520 of the second comparison output register group 504 are provided respectively with the waveform shaping circuits 840, 832, 844, 846, 848 and 850, which respectively deliver pulses INTLD, ADVD, RPMWD, VSPWD, INTVD and ENSTD performing their duties only during the period from the instant that the register group 504 is set to the next arrival of the stage signal ZEROSTG.

For the purpose of detecting the pulse train signals supplied from the various sensors to the input/output circuit, it is necessary to synchronize these pulse train signals with the operation of the input/output circuit. For, since the periods or the pulse durations of these pulse train signals vary depending on, for example, the rotational speed of the engine and the vehicle speed to considerable extents, each lengthened period may equal several times the period of the corresponding stage while each shortened period may be too short in comparison with that of the corresponding stage to exist until the corresponding stage signal is received. Therefore, if these pulse train signals are not suitably controlled, the exact counting of the pulse trains will be impossible.

FIG. 9 shows an example of a synchronizing circuit for synchronizing the external pulse train signals with the stage signals in the input/output circuit and FIG. 10 shows a timing chart useful in explaining the operation of the synchronizing circuit shown in FIG. 9.

The external input pulse signals from the various sensors, such as the reference pulses PR, the angular position signal PC and the vehicle speed signal PS are latched respectively in the latch circuits 600, 602, 604 in response to the output STG0 shown in FIG. 6.

In FIG. 10, the diagram A corresponds to the waveform of the clock signal φ2, B to the clock signal φ1, and C and D to the stage signals STG7 and STG0. These stage signals are generated in timing with the clock signal φ2. The signal waveform of the diagram E is of the output pulse from the angular position sensor or the vehicle speed sensor, corresponding to the reference pulse PR or the angular position pulse PC or the vehicle speed pulse PS. The time of occurrence, the duty cycle and the period of the signal shown in the diagram E are irregular, the signal being received independent of the corresponding stage signal.

Now, let it be assumed that the signal as shown in the diagram E is received by the latch circuits 600, 602 and 604. Then, they are latched in response to the stage signal STG0 (pulse S1 in diagram D). Accordingly, the outputs A1, A2 and A3 take the high level at an instant S2, as shown in diagram F. Also, since the input signals PR, PC and PS are at the high level when the stage signal STG0 represented by the pulse S3 is received, the high level is latched in the latch circuits 600, 602 and 604. On the other hand, since the input signals PR, PC and PS are at the low level when the stage signal STG0 represented by the pulse S4 is received, the low level is latched in the latch circuits 600, 602 and 604. As a result, the outputs A1, A2 and A3 of the latch circuits 600, 602 and 604 are as shown in the diagram F of FIG. 10. Since the latch circuits 606, 608 and 610 respectively latch the outputs A1, A2 and A3 of the latch circuits 600, 602 and 604 in response to the stage signal STG7 represented by the pulse S5 shown in the diagram C, the outputs B1, B2 and B3 of the latch circuits 606, 608 and 610 rise at the instant S6. Also, since they latch the high level when the stage signal STG7 represented by the pulse S7 is received, they continue to deliver the high level output. Therefore, the output signals B1, B2 and B3 of the latch circuit 606, 608 and 610 are as shown in the diagram G of FIG. 10.

The NOR circuit 612 receives the signal B1 and the inverted version of the signal A1 through the inverter 608 and delivers the synchronized reference signal PRS as shown in the diagram H of FIG. 10. This synchronized reference signal PRS is generated in response to the leading edge of the stage signal STG0 under the condition that the reference signal PR has changed from a low level to a high level and disappears in response to the leading edge of the stage signal STG7 and so has a pulse duration from the leading edge of the stage signal STG0 to the leading edge of the stage signal STG7. The exclusive OR circuits 614 and 616 receive the signals A2 and B2 and the signals A3 and B3. The signal S8 is generated in response to the leading edge of the stage signal STG0 when the stage signal STG0 is generated after the signal PC or PS is changed from a low to a high level and disappears in response to the leading edge of the stage signal STG7, while the signal S9 is generated in response to the leading edge of the stage signal STG0 when the signal STG0 is generated after the signal PC or PS is changed from a high to a low level and disappears in response to the leading edge of the stage signal STG7. The duty cycles of the signals S8 and S9 are equal to that of the signal shown in the diagram H of FIG. 10, and therefore determined by the stage signals STG0 and STG7.

In the above description, it is assumed that the signals PR, PC and PS have the same duty cycle and that they are simultaneously received. In practice, however, they have different duty cycles and are received at different instants. Further, each signal itself has its period and duty cycle varied with time.

The synchronizing circuit shown in FIG. 9 serves to render the irregular duration of the signal constant. The constant pulse duration is determined by the difference between the rising instants of the stage signals STG0 and STG7. Therefore, the pulse widths or durations can be controlled by controlling the stage signals applied to the latch circuits 600, 602, 604, 606, 608 and 610.

The pulse durations are determined depending on the timing of the stages listed in the table 1. Namely, as seen from the table 1, the stage INTL corresponds to the condition that the outputs of the counters C0 -C2 and the outputs of the counters C3 -C6 are respectively 1 and 0, i.e. (C0 -C2, C3 -C6)=(1, 0) and further the conditions that (C0 -C2, C3 -C6)=(1, 1), (1, 2), (1, 3) . . . , thus the stage INTL appears every eighth stage.

Since each stage is processed in 1 μsec, the stage INTL appears every 8 μsec. In the stage INTL, the angular position signal PC must be detected to control the incrementor and when the output PC of the angular position sensor 98 is supplied to the synchronizing circuit shown in FIG. 9, the circuit generates the synchronizing pulses which coincide in timing with the stage INTL so that the incrementor controller is controlled by the synchronizing pulses PCS in the stage INTL.

The sychronizing pulse signal PCS is detected also in the stage ADV or RPM. The stage ADV or RPM appears whenever each of the values of the outputs C3 -C6 is incremented by unity while each of the values of the outputs C0 -C2 is 3 or 6, respectively. Each of the stages ADV and RPM reappears at a period of 8 μsec.

The signal STG0 shown in FIG. 9 is delivered when the values of the outputs C0 -C2 of the stage counter SC570 are 0 while the signal STG7 is delivered when the bits C0 -C2 have a decimal value of 7. The stage signals STG0 and STG7 are generated independent of the outputs C3 -C6. As seen from FIG. 10, the synchronized signal PCS necessarily has its pulse duration existing while the outputs C0 -C2 of the stage counter change from 0 to 6. The incrementor controller is controlled by detecting the signal in the stages INTL, ADV and RPM.

In like manner, the stage CYL for detecting the synchronized reference signal PRS takes place when the outputs C0 -C2 of the stage counter SC570 are 2. When the angular position sensor 98 delivers the reference pulse PR, it is necessary to deliver the synchronized reference signal PRS when the outputs C0 -C2 are 2. This requirement is satisfied by the circuit shown in FIG. 9 since the circuit delivers the pulse signal whose pulse duration lasts from the stage signal STG0 to the stage signal STG7.

The stage VSP for detecting the vehicle speed takes place only when the outputs C0 -C2 of the stage counter are 5. It is therefore only necessary to deliver the synchronized signal PSS while the outputs C0 -C2 are 5. The requirement is also satisfied by the circuit shown in FIG. 9 since with the circuit the outputs C0 -C2 have the values from 0 to 6. In the circuit shwon in FIG. 9, the stage signals STG0 and STG7 may be replaced respectively by the stage signal STG4 delivered when the outputs C0 -C2 have the value of 4 and the stage signal STG6 delivered when the outputs C0 -C2 are 6. In this case, if the signal PS is received, the synchronized signal PSS is always delivered when the outputs C0 -C2 are 4 and 5.

Now, the cycles of the stages will be referred to. As shown in the above given table 1, 128 stage signals are produced corresponding to the values 0-127 of the outputs C0 -C6 of the stage counter SC570. When all these 128 stage signals have been generated, a major cycle is completed to be followed by a next major cycle. Each major cycle is constituted of 16 minor cycles and each minor cycle consists of 8 stage signals. The minor cycle corresponds to the values 0 to 7 of the outputs C0 -C2 of the stage counter and is finished in 8 μsec.

To exactly synchronize the pulse signals PR, PC and PS and to exactly generate the synchronized pulses PRS, PCS and PSS, it is necessary for the outputs of the sensors to have a pulse duration longer than the period of the minor cycle. For example, the duration of the angular position pulse PC is shortened as the rotational speed of engine increases. It is about 9 μsec. for 9000 rpm. It is therefore necessary to make the period of the minor cycle shorter than 9 μsec. so as to exactly perform the synchronizing operation even at 9000 rpm. In this embodiment, the period of the minor cycle is chosen to be 8 μsec.

FIG. 11 shows in detail an example of the incrementor 478 shown in FIG. 4. The input terminals A0-A9 respectively receive the 10-bit data from one of the registers of the instantaneous register group, selected in accordance with the corresponding stage signal.

First, description will be made of the bit A0, i.e. signal received at the input terminal A0. The bit A0 and the count signal is supplied to the exclusive OR circuit 850. If the bit A0 is 0 (zero) and the count signal has the zero (L) level, then the signal 0 (zero) is delivered by the circuit 850. On the other hand, if the bit A0 is 1 and the count signal is the L level, the value 1 is delivered. Namely, when the count signal is 0, bit A0 is passed without any change.

If the count signal has the 1(H) level, the bit A0 is inverted; the output of the circuit 850 is 0 when the bit A0 is 1 and when the bit A0 is 0. With respect to the bit A0, the value is counted up by unity in accordance with the count signal. When the bit A0 and the level of the count signal are both 1, a carry signal is supplied to the processing gate 854 for the upper bit A1.

The NOR gate 852 serves to detect the above said carry signal and only when there is the carry signal, the bit A1 is inverted to be delivered as an output B1. When there is no carry signal, the output B1 is the same as the bit A1. in like manner, the NOR gates 856, 860, 864, 868, 872, 876, 880 and 884 detect the corresponding carry signals and the input bits A2-A9 are supplied, as inverted versions or without change, to the exclusive OR circuits 858, 862, 866, 870, 874, 878, 882 and 886. Namely, if there are the corresponding carry signals, the bits A2-A9 are inverted to form the outputs B2-B9, respectively. In the presence of the count signal, therefore, the input bits A0-A9 are each counted up by unity to produce the output signals B0-B9.

AND gates 890-908 serve as reset mechanisms. Upon reception of a reset signal, the outputs B0-B9 become all zero, irrespective of the outputs of the exclusive OR circuits 850-886. The count signal and the reset signal for controlling the incrementor whose detail is shown in FIG. 11 are generated by the incrementor controller 490 shown in FIG. 4.

FIGS. 12A and 12B show the details of the incrementor controller 490, FIG. 12A showing a circuit for generating the count signal COUNT and the reset signal RESET for controlling the incrementor 478 and FIG. 12B showing a circuit for generating a signal MOVE for transferring data to the output register groups 430 and 432. As described before, the incrementor has three functions: the first function is to increase the value of the input data by unity, the second is to reset the input data, and the third is to pass the input data without change. The increment function, i.e. the first function to increase the value of the input data by unity, is performed in response to the count signal COUNT and the reset function in response to the reset signal RESET. When the count signal is at the high level, the increment function is performed while the non-increment is performed when the count signal is at the low level. When the reset signal is at the high level, the reset function is carried out. The reset signal is given a preference over the count signal.

The various conditions are selected in response to the stage signals specified by the respective processings. The conditions refer to the synchronized external inputs and the outputs from the second comparison output register group 504. The condition for transferring data to the output register group 474 are the same as that for the control of the incrementor.

FIG. 13 illustrates a processing operation according to the fuel injection signal INJ. Since the time of starting the injection of fuel varies depending on the number of cylinder used, the initial angular positon pulses INTLD derived from the reference signal PRS are counted by the register 442 serving as a CYL counter. The result of the counting is compared with the content of the CYL register 404 holding a value corresponding to the number of the cylinders. When the result of counting is greater than or equal to the content of the register 404, "1" is set in the CYL FF 506 of the first comparison output register group 502 and further in the CYLBF 508 of the second group 504. The CYL counter 442 is reset if the content of the CYLBF equals 1. Also, for CYLBF=1, the INJ timer 450 for measuring the fuel injection duration is reset. The content of the timer 450 is always increased unconditionally with time and compared with the content of the INJD register 412 holding the data corresponding to the fuel injection duration. When the content of the timer 450 is greater than or equal to the content of the register 412, "1" is set in the INJFF 522 of the first group 502 and further in the INJBF 524 of the second group 504. The unconditional increment with time is inhibited for INJBF=1. The inverted version of the content of the register INJBF is the fuel injection duration, i.e. the valve opening period of the fuel injector.

FIG. 14 illustrates a processing according to the signal for controlling the ignition. The register 452 serving as the ADV counter is reset by the initial angular position pulse INTLD. The content of the register 452 is increased while the synchronized angular position signal PC is at the high level. The increased content of the register 452 is compared with the content of the register ADV 414 holding the data corresponding to the ignition angle. If the former is greater than or equal to the latter, "1" is set in the register ADVFF 526 of the first group 502 and further in the register ADVBF 528 of the second group 504. The signal ADVD indicating the rising part of the output of the ADVBF resets the DWL counter 454 for instructing the start of conduction. The content of the DWL counter 454 is increased while the synchronized angular position signal PC is at the high level, and then compared with the content of the DWL register 416 holding the data representing the angular position at which the electric conduction takes place, relative to the previous ignition angle. If the former is greater than or equal to the latter, "1" is set in the register DWLFF 530 of the first group 502 and further in the register DWLBF 532 of the second group 504. The output of the DWLBF 532 is the ignition control signal ING1.

FIG. 15 illustrates a processing according to the signal EGR(NIDL). The circuit elements 28 for controlling EGR, to which the signal EGR is supplied, employs a proportional solenoid and therefore the control of EGR is effected by controlling the duty cycles of the input signal. They are the EGRP register 418 for holding the period and the EGRD register 420 for holding the on-duration. The timer used in this processing is the EGR timer 456. During the processing in the stage EGRPSTG, the increment is unconditional. If the content of the EGR timer 456 proves to be greater or equal to the content of the EGRP register 418 as the result of comparison, "1" is set in the EGRPFF 534 of the first register group 502 and further in the EGRPBF 536 of the second register group 504.

During the processing in the stage EGRDSTG, the unconditional non-increment takes place and the EGR timer 456 is reset for EGRPBF=1. If, as a result of comparison, the content of the EGR timer 456 is greater than or equal to the content of the EGRD register 420, "1" is set in the EGRD register 538 of the first group 502 and further in the EGRD register 540 of the second group 504. The inversion of the output of the EGRD register 540 is the control signal EGR.

FIG. 16 illustrates the way of measuring the rotational speed of engine RPM (or vehicle speed VSP) and the processing of the measured results. The measurement is performed by determining a certain measurement duration by the RPMW timer 460 and also by counting the synchronized angular position pulses PC within the determined duration by the same counter.

The content of the RPMW timer 460 for measuring the measurement duration is increased unconditionally and reset when the content of the RPMWBF 552 is "1". If, as a result of comparison, the content of the RPMW timer 460 is greater than or equal to the content of the RPMW register 426, "1" is set in the RPMWFF 550.

In response to the signal RPMWD representing the rising part of the output signal of the RPMWBF 552, the content of the RPM counter 462 representing the result of the count of the pulses PC is transferred to the RPM register 430 of the output register group 474. The RPM counter 462 is reset when the content of the RPMWBF 552 is "1". The processing in the stage VSPSTG is similar to that described above.

The functions of the registers used in the embodiment of this invention will be particularized below in the following table 3.

              TABLE 3______________________________________No. ofregister   function of register______________________________________402        to hold the digital value corresponding(ZERO . REG)      to zero and to transfer the value to the      comparator when required.404        to hold the data CYL representing the(CYL . REG)      number of the used cylinders, the data      CYL being used, for example, to produce      a signal representing the rotation of the      crank shaft through 360°.406        to hold the data INTL representing the(INTL . REG)      crank angle and the angle between a pre-      determined crank angular position and the      angular position of the sensor for generating      the reference signal INTLS. The reference      signal PR from the sensor 98 is shifted      by a predetermined value in accordance with      the data INTL so as to correspond to the      predetermined crank angular position.408        to hold, as a timer, the data INTV re-(INTV . REG)      presenting the time to measure. If the      data INTV is set in the register 408,      an interruption signal can be delivered      after the lapse of the time.410        to hold the data ENST representing the(ENST . REG)      time used to detect the accidental stopping      of the engine.412        to hold the data INJD representing the(INJD . REG)      valve opening period of the fuel injector.414        to hold the data ADV representing the crank(ADV . REG)      angle range measured from the reference      angle at which the reference signal is      generated to the primary current cut-off      angle of the ignition coil.416        to hold the data DWL representing the crank(DWL . REG)      angle range from the angle at which the      immediately previous reference signal is      generated to the angle at which the primary      current is conducted through the ignition      coil, in which range the primary current      is kept cut off.418        to hold the data EGRP representing the(EGRP . REG)      pulse period of the pulse current signal      EGR for controlling the aperture of the      valve of the EGR apparatus.420        to hold the data EGRD representing the(EGRD . REG)      pulse duration of the pulse current signal      EGR for controlling the aperture of the      valve of the EGR apparatus.422        to hold the data NIDLP representing the(NIDLP . REG)      period of the pulse current signal NIDL      for controlling the air regulator provided      to control the flow of air through the      bypass of the throttle chamber.424        to hold the data NIDLD representing the(NIDLD . REG)      pulse duration of the pulse current signal      NIDL.426        to hold the data RPMW representing the(RPMW . REG)      constant period of time used to detect      the rotational speed of the engine.428        to hold the data VSPW representing the(VSPW . REG)      constant period of time used to detect the      vehicle speed.442        to hold the instantaneous number representing(CYLC . REG)      the number of arrivals of the reference      signal pulses.444        to hold the number of the crank angle(INTLC . REG)      pulses delivered after the delivery of      the reference pulse from the angular      position sensor 98.446        to hold the instantaneous value of the(INTVT . REG)      variable which increases at regular      intervals, e.g. every 1024 μsec, after the      proper data has been set in the INTV      register 408.448        to hold the instantaneous value of the(ENST . REG)      variable which increases at regular inter-      vals, e.g. every 1024 μsec, after the      reference pulse has been delivered from      the angular position sensor 98. The content      of the register 448 is reduced to zero      upon reception of the reference pulse.450        to hold the instantaeous value of the(INJT . REG)      variable which increases at regular inter-      vals, e.g. every 8 μsec, 16 μsec, 32 μsec,      65 μsec, 128 μsec or 256 μsec, after the      CYL signal has been delivered. The above      interval of time is chosen by the T register.452        to hold the instantaneous value of the(ADVC . REG)      variable which increases each time the      angular position sensor 98 delivers the      signal PC representing the rotation of      a fixed crank angle, e.g. 0.5 degree,      after the reference signal INTLS has been      delivered.454        to hold the instantaneous value of the(DWLC . REG)      variable which increases each time the      angular position sensor 98 delivers the      crank angle position signal PC after the      immediately previous signal INTLS has been      delivered.456        to hold the instantaneous value of the(EGRT . REG)      variable which increases at regular inter-      vals, e.g. every 256 μsec, after the signal      EGRP has been delivered.458        to hold the instantaneous value of the(INDLT . REG)      varialbe which increases at regular      intervals, e.g. every 256 μsec, after the signal      NIDLP has been delivered.460        to hold the instantaneous value of the(RPMWT . REG)      variable which increases at regular intervals      of time after the second comparison result      holding register 552 has delivered an output      pulse.462        to hold the instantaneous value of the(RPMC . REG)      variable which increases each time the      angular position sensor 98 delivers the      angular position signal PC representing      a fixed crank angle, after the second      comparison result holding register 552      has delivered an output pulse.430        to hold the data transferred from the(RPM . REG)      register 462 in response to the output      signal from the second comparison result      holding register 552. The data is delivered      onto the data but in accordance with the      address signal and the control instruction      from the CPU 114.464        to hold the instantaneous value of the(VSPWT . REG)      variable which increases at regular intervals      of time after the second comparison result      holding register 556 has delivered an      output.468        to hold the instantaneous values of the(VSPC . REG)      variable increases each time one of      the pulses corresponding to the rotational      speed of the wheel is generated, after the      second comparison result holding register      556 has delivered an output pulse.432        to hold the data transferred to the(VSP . REG)      register 468 in response to the output      signal of the second comparison holding      register 556. The data is delivered onto      the data bus in accordance with the address      signal and the control instruction from      the CPU 114.506        to have "1" set in if the data of the(CYLFF)    register 404 is less than or equal to the      data of the register 442.508        to have the signal from the register 506(CYLBF)    set in in timing with the clock signal φ2.518        to have "1" set in if the data of the(ENSTFF)   register 410 is less than or equal to the      data of the register 448.520        to have the signal from the register 518(ENSTBF)   set in in timing with the clock signal φ2.522        to have "1" set in if the data of the(INJFF)    register 412 is less than or equal to the      data of the register 450.524        to have the signal from the register 522(INJBF)    set in in timing with the clock signal      φ2.526        to have "1" set in if the data of the(ADVFF)    register 414 is less than or equal to the      data of the register 452.528        to have the signal from the register 526(ADVBF)    set in in timing with the clock signal φ2.530        to have "1" set in if the data of the(DWLFF)    register 416 is less than or equal to      the data of the register 454.532        to have the signal from the register 530(DWLBF)    set in in timing with the clock signal φ2.534        to have "1" set in if the data of the(EGRPFF)   register 418 is less than or equal to the      data of the register 456.536        to have the signal from the register 534(EGRPBF)   set in in timing with the clock signal φ2.538        to have "1" set in if the data of the(EGRDFF)   register 420 is less than or equal to the      data of the register 456.540        to have the signal from the register 538(EGRDBF)   set in in timing with the clock signal φ2.542        to have "1" set in if the data of the(NIDLPFF)  register 422 is less than or equal to the      data of the register 458.544        to have the signal from the register 542(NIDLPBF)  set in in timing with the clock signal φ2.546        to have "1" set in if the data of the(NIDLDFF)  register 424 is less than or equal to the      data of the register 458.548        to have the signal from the register 546(NIDLDBF)  set in in timing with the clock signal φ2.550        to have "1" set in if the data of the(RPMWFF)   register 426 is less than or equal to the      data of the register 460.552        to have the signal from the register 550(RPMWBF)   set in in timing with the clock signal φ2.554        to have "1" set in if the data of the(YSPWFF)   register 428 is less than or equal to the      data of the register 464.556        to have the signal from the register 556(VSPWBF)   set in in timing with the clock signal φ2.______________________________________

Now, description will be made of how the reference data is set in the reference register group 470. The registers 402, 404, 406 and 410 have their data set at the time of starting the apparatus as the embodiment of this invention. The values of the data are never changed once they have been set in the registers. The setting of data in the register 408 is performed according to the programmed processing.

The register 412 receives the data INJD representing the valve opening duration of the fuel injector 66. The data INJD is determined, for example, as follows. The output signal QA of the air-flow meter 14 is sent through the multiplexer 122 to the analog/digital converter 124. The digital data delivered from the A/D converter 124 is held in a register (not shown). The load data TP is obtained from the above data representing the quantity of sucked air and the data held in the register 430 shown in FIG. 4, through arithmetic operations or on the basis of the information stored in a map fashion. The outputs of the sensor 16 for the temperature of the sucked air, the sensor for the temperature of the cooling water and the sensor for the atmospheric pressure are converted to digital quantities, which are corrected according to the load data TP and the condition of the engine at operation. Let the factor of such a correction be K1. The voltage of the battery is also converted to a digital quantity. The digital version of the battery voltage is also corrected according to the load data TP. Let the correction factor in this case be TS. Next, the correction by the λ sensor 80 takes place and let the correction factor associated be α. Therefore, the data INJD is given by the following expression.

INJD=α(K1 ·TP+TS)

Thus, the valve opening duration of the fuel injector is determined. The above method of determining the data INJD is merely an example and other methods may be employed.

The data ADV representing the ignition timing is set in the register 414. The data ADV is made up, for example, as follows. The map-like ignition data QIG with the data TP and the rotational speed as factors is held in the ROM 118. The data QIG is then subjected to starting correction, water temperature correction and acceleration correction. After these corrections, the data ADV is obtained.

The data DWL for controlling the charging period for the primary current through the ignition coil is set in the register 416. This data DWL is obtained through arithmetic operation from the data ADV and the digital value of the battery voltage.

The data EGRP representing the period of the signal EGR and the data NIDLP representing the period of the signal NIDL are set respectively in the registers 418 and 422. The data EGRP and NIDLP are predetermined.

The data EGRD representing the duration of opening the valve of the EGR (exhaust gas recurrent) apparatus is set in the register 420. As the duration increases, the aperture of the valve increases to increase the rate of recurrence of exhaust gas. The data EGRD is held in the ROM 118 in the form of, for example, a map-like data with the load data TP and the rotational speed as factors. The data is further corrected in accordance with the temperature of the cooling water.

The data NIDLD representing the duration of energizing the air regulator 48 is set in the register 424. The data NIDLD is determined, for example, as a feedback signal derived from such a feedback control that the rotational speed of the engine under no load condition always equals a preset fixed valve.

The data RPMW and VSPW representing fixed periods of time are set respectively in the registers 426 and 428 at the beginning of the operation of the apparatus.

In the foregoing description of the embodiment of this invention, the output of the air-flow meter is used to control the amount of injected fuel, the advance of ignition angle and the recycle rate of exhaust gas. Any sensor other than the air-flow meter, however, may be employed to detect the condition of the sucked air. For example, a pressure sensor for detecting the pressure in the intake manifold may be used for that purpose.

As described above, according to this invention, the pulse signals received irregularly with respect to the stage cycle are synchronized so that exact detections can be assured.

Further, in the embodiment of this invention described above, since the stage cycle is constituted of major cycles each of which consists of minor cycles, the detection cycle can be controlled in accordance with the precision required. Moreover, since the stages for detecting the synchronized signals are processed for a period in the order of a minor cycle, exact detections can be assured even when the engine is operating at a high speed.

Furthermore, the above described embodiment of this invention has a reference register group, an instantaneous register group and a comparison result holding register group and a register is selected from each of the register groups and connected with the comparator in accordance with the outputs of the stage counter, so that so many control functions can be effected by a relatively simple circuit.

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Classifications
U.S. Classification701/115, 701/103, 123/480, 701/123, 123/339.14, 123/406.65, 123/487, 701/109
International ClassificationF02P5/15, F02D21/08, F02M25/07, F02D41/24
Cooperative ClassificationF02D2041/2027, Y02T10/46, Y02T10/47, F02D41/0077, F02P5/1502, F02M25/0772, F02D41/28
European ClassificationF02D41/28, F02P5/15B, F02D41/00F6V