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Publication numberUS3742919 A
Publication typeGrant
Publication dateJul 3, 1973
Filing dateDec 14, 1970
Priority dateDec 12, 1969
Also published asDE2061242A1, DE2061242B2, DE2061242C3
Publication numberUS 3742919 A, US 3742919A, US-A-3742919, US3742919 A, US3742919A
InventorsSuda S
Original AssigneeHitachi Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Injection type fuel feeder
US 3742919 A
Abstract
An injection type fuel feeder for automotive vehicles in which the injection time of the fuel is computed on the basis of conditional signals from the engine, which include engine revolutions per minute, temperature, etc., in combination with a saw-tooth current, characterized in that the rate of change of the saw-tooth current is controlled in accordance with the engine manifold negative pressure and the temperature of the engine, whereby compensation of the engine output and temperature can be accomplished in proportion to the other conditional signals.
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111111 States atent 1191 1111 3,242,919 Suda 1 .iuiy 3, 1973 [541 INJECTION TYPE FUEL FEEDER 3.372680 3/1968 SChOII 123/32 EA 75 I I S 3,456,628 7/1969 131158616161. 123/32 EA I I memo Sud, M110 v 3,464,396 9 1969 Scholl 123/32 EA [731 Assignee: Hitachi, Ltd., Tokyo, Japan [22] Filed: 14 1970 Primary Examiner-Laurence M. Goodridge Assistant Examiner-Cort Flint Attorney-Craig, Antonelli, Stewart & Hill [30] Foreign Application Priority Data Dec. 12, 1969 Japan .......44/99435 [57] ABSTRACT I An injection type fuel feeder for automotive vehicles in [52] [1.8. CL... 123/32 EA, 123/119 R, 123/140 M which the injection time of the fuel is computed on the [51] Int. Cl. FOZd 5/00 basis of Conditional Signals from the engine which Field of Search l d gi l ti p i t t p t t in combination with a saw-tooth current, characterized R in that the rate of change of the saw-tooth current is [56] eferences Cited controlled in accordance with the engine manifold neg- UNITED STATES PATENTS ative pressure and the temperature of the engine, 3,612,009 10/1971 Kamazuka 123/32 EA whereby compensation of the engine output and tem- 36 5240 2/1972 np tit 3/3 A perature can be accomplished in proportion to the Douglas other onditional signals 3,272,187 9/1966 Westbrook et al.. 123/32 EA 3,314,407 4/1967 Schneider 123/148 E 11 Claims, 10 Drawing Figures I 1 7 NEG PRESS ADDED SIG LE- M FUEL INJ DETECTING VEL DETECTING VALVE 1 REV NO.

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SEun SuDn BY l gx RM} HTTO RN EYS INJECTION TYPE FUEL FEEDER BACKGROUND OF THE INVENTION This invention relates to injection type fuel feeders for automotive vehicle engines and more specifically to injection fuel feeders capable of effectively adjusting the fuel feed from an economical output region to the high output region of such engines to compensate for various engine conditions.

Generally, the injection fuel feeder associated with electrical control means is operated in such a manner that the conditions for determining the fuel feed to an internal combustion engine are converted into electric signals, from which an output signal having a time width corresponding to the amount of fuel to be supplied to the engine is derived through computation, the fuel injection valve then being opened by said output signal to insure that an adequate amount of fuel is sup plied to the engine based on a function of time.

The present invention provides such an injection fuel feeder arrangement which serves to control the amount of fuel supplied to the engine as a function of time in accordance with such engine conditions as engine speed in revolutions per minute, engine temperature and manifold pressure. More particularly, the present invention provides such control over the fuel injection by relatively simple and reliable means which effect a smooth control on a continuous basis between respective feed rates based on manifold pressure.

It is an object of the present invention to provide a fuel injection control system of the type described which provides for improved performance over those systems known heretofore.

It is another object of the present invention to provide a fuel injection control system which is capable of effecting smooth control on a continuous basis with switching between first and second fuel rates in response to manifold pressure.

It is a further object of the present invention to provide a fuel injection control system which is capable of response to a plurality of conditions, but is simple, reliable and inexpensive.

These and other objects, features and advantages of the present invention will become more apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a block diagram showing a conventional electric control system for an injection type fuel feeder;

FIG. 2 is a schematic circuit diagram showing a conventional control computing means;

FIGS. 3(a) and 3(b) are characteristic diagrams explaining the operation of the circuit of FIG. 2;

FIG. 4 is a diagram showing the characteristics of fuel feed versus engine manifold negative pressure;

FIG. 5 is a schematic circuit diagram showing another conventional control computing means;

FIG. 6 is a diagram showing the fuel feed characteristics of an injection fuel feeder embodying this invention;

FIG. 7(a) and 7( b) are diagrams which aid in explanation of the control operation characteristics of the present invention; and

FIG. 8 is a schematic circuit diagram of a control arrangement in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, there is shown a fuel feeder including a plurality of engine condition detectors comprising a negative pressure detector 1 for converting the engine manifold negative pressure P into an electric condition signal; an engine speed detector 2 for converting the number of engine revolutions per minute (r.p.m.) N into an electric condition signal; a temperature detector 3 for converting the engine temperature T into an electric condition signal; a trigger pulse generator 4 for generating a signal at a desired time for triggering the condition signals of detectors 1, 2 and 3 to start fuel injection into the engine; and a time signal generator 5 actuated by the trigger signal of generator 4 to generate a sawtooth wave time signal. An adding signal level detector 6 receives the outputs from the detectors 1, 2 and 3, and is also supplied with the time signal from the generator 5, thus producing an output with a time width starting from the time at which the trigger signal is generated to the time at which the sum of the condition signals and time signal reaches a particular detection level. A fuel injection valve 7 is opened in response to the output signal from the detector 6, whereby the necessary amount of fuel is supplied to the engine.

In the above-described arrangement, a circuit comprising an Esaki diode 8 and a transistor 9, as shown in FIG. 2, is effectively used for said level detector 6. The Esaki diode 8 is connected in parallel between the base and emitter of the grounded-emitter transistor 9 with the same polarity direction. The collector of transistor 9 is connected to an output terminal 10 and also to a power source circuit 12 via a resistor 11; and, the base of the transistor is connected to an input terminal 13, to which a negative detection signal voltage E revolution number detection signal voltage E temperature detection signal voltage E and time signal voltage E, are applied via resistors 14, 15, 16, and 17. In addition, a trigger signal terminal 4' receiving the output of pulse generator 4 is connected to the input terminal 13.

When the current flowing to the base of transistor 9 and through diode 8 due to the conditional signal voltages relating to the engine conditions being monitored is smaller than the peak value of the Esaki diode 8, the forward impedance of the Esaki diode will be very small and, accordingly, the current due to the conditional signals can be added together without interfering with each other. Also, because the terminal voltage across the diode is small, compared with the barrier voltage of the transistor 9, the collector voltage will be high, and an output voltage can be derived from the output terminal 10.

In the above circuit, when the time signal voltage E, is made zero by the trigger signal at a desired time for starting fuel injection and, at the same time, the current flowing in the Esaki diode due to the combined conditional signal voltages is maintained at a level lower than its peak value, an output signal is derived at the output terminal 10 and the fuel injection valve 7 is opened. However, when the combined current flowing due to the added conditional signal voltages and the time signal voltage E which increases with time, becomes more than the peak value of the Esaki diode 8, the transistor 9 immediately becomes sufficiently biased to turn on and thus becomes conductive, whereby the supply fuel is stopped because the output voltage at the output terminal which controls the fuel injection valve 7 vanishes. Thus, the duration of the fuel feeding period depends on the level of the conditional signal current, and hence, the amount of the injected fuel supply can be controlled according to the conditions of the engine. This operation will be more specifically described with reference to FIGS. 3(a) and 3(b).

In FIG. 3(a), it is assumed that I, denotes the signal current flowing for the period t from the time at which the fuel injection is desired to be started, and I, indicates the conditional signal current. Then, the combined current (I, I,) flowing into the Esaki diode 8 form the input terminal 13 should become I,,. When the time is zero at the start of fuel injection, operated in the region within the peak value I by the trigger signal. Therefore, an output signal voltage E is delivered at the output terminal 10 as shown in FIG. 3(b), in the region wherein the combined current I is smaller than the peak value I,,. When the combined current I reaches the peak value 1,, of the Esaki diode 8, the terminal voltage across the Esaki diode 8 is rapidly increased, and the base-emitter bias of the transistor 9 becomes sufficiently large to render the transistor 9 conductive. At this time t the output signal voltage B vanishes. Thus, the amount of fuel supply can be determined as a function of time t,.

When the conditional signal current T, is changed to a conditional signal current I, due to a condition change of the engine, the combined current I is accordingly changed to I,,. As a result, the time t, taken for the Esaki diode 8 to reach its peak value I, is changed to and the amount of fuel supply is also changed due to the resulting variation in the period of opening of the injection valve 7. In other words, the fuel feed is controlled according to engine conditions.

The fuel feed Q at an engine manifold negative pressure P should be controlled so as to be increased in the region of small engine manifold negative pressure P, as seen in FIG. 4. More specifically, the region in which the engine manifold negative pressure P is relatively large represents the medium output region or, in other words, this region is the normal operating region of the motor vehicle engine. In this region, the fuel feed Q is determined from an economical point of view. On the other hand, the region in which the engine manifold negative pressure is small is indicative of the need for a large output form the engine. In this region, therefore Q is determined so as to be able to deliver the maximum output without taking requirements of economy into consideration.

The desired characteristics for a fuel feed operation as described above can be obtained through the arrangement as illustrated in FIG. 5, wherein the resistors 14 and for applying a negative pressure detection signal voltage [3,, and revolution number detection signal voltage E to the input terminal 13 are changed over to the resistors 14' and 15', respectively, by the switching contacts 18 and I9 actuated in accordance with the engine manifold negative pressure P, and the fuel feed is controlled according to the resistance values of the resistors 14 and 15'. In this arrangement, the conversion coefficient of the conditional signal current can be changed by changing said resistance values. On the other hand, however, the absolute value of the conversion coefficient is inevitably changed abruptly with this arrangement to thereby cause a skip in the control and introduce a shock into the normal flow of fuel.

To avoid this, it is necessary to provide an arrangement wherein a bias signal voltage E in addition to the conditional signal, is applied thereto and this bias signal voltage is switched from the resistor 21 to the resistor 21' by way of contact 20, whereby the skip is reduced. This arrangement, however, requires a large number of switching contacts and is unavoidably complicated in composition and short in life. Furthermore, this type of conventional device is undesirable from the standpoint of reliability because shocks are still generated due to this discontinuous operation.

The principles and an embodiment of the present invention will be described below by referring to FIGS. 6 through 8. The fuel feed characteristics which have been described by referring to FIG. 4 are ones determined from design requirements. Substantially, the fuel feed characteristics at the engine manifold negative pressure P for the maximum output is indicated by the dotted line 1 and for the economical output by the dotted line 12, as shown in FIG. 6. Therefore, to change over the operating characteristics from for the maximum output to another for economical output at the engine manifold negative pressure P,, it is ideal to employ the characteristic shown by the full line It is desirable that the characteristic change-over from the dotted lines 1 to 12 be done continuously with a certain time lag so as not to cause an operating shock. This fuel feed characteristic change-over can be realized by suitably deterrnining the conversion coefficient of the time signal versus time lapse in the manner described above with reference to FIGS. 1 through 3. For example, the conversion coefficient of the time signal is changed over at the engine manifold negative pressure P, so that the time signal current I, is switched to I, as shown in FIG. 7(a), and the conversion coefficient of the time signal current I, is determined so that the fuel feed characteristics at the engine manifold negative pressure P take the form of the dotted line 1 and that of I, is determined so that the fuel feed characteristics take the form of 12. By this arrangement, the time taken for the Esaki diode 8 to reach its peak value I from the combined current I of the conditional current I, and time signal current I,(I,') at the engine manifold negative pressure P, is changed over to t from t,, and thus an output signal voltage E as shown in FIG. 7(b) is obtained.

When the time signal current I, is changed over to I, continuously with a time lag, then the characteristic change-over can be accomplished without causing a shock.

This change-over operation will be more specifically described by referring to FIG. 8 wherein an exemplary embodiment of the detector 5 in accordance with this invention is illustrated. The reference 22 denotes a PNP transistor controlled at a constant current. The emitter of this transistor is connected to a power source line 24 via a resistor 23, and the collector is connected to an output terminal 25 and also to ground via a capacitor 26. The base of transistor 22 is connected to the power source line 24 via a resistor 27 and also to the voltage dividing point between voltage dividing resistors 29 and 30 via a zener diode 28, the resistors 29 and 30 being connected in series between the power line 24 and ground. A compensating resistor 31 is connected in parallel to the voltage dividing resistor 29 through switch 32, which is closed when the engine manifold negative pressure P is below the value P, by a diaphragm 33 operated by the engine manifold negative pressure P. A delay capacitor 34 is connected in parallel to the voltage dividing resistor 30. The purpose of this delay capacitor is to prevent abrupt voltage variation produced at the voltage dividing point when the switch 32 is actuated. The numeral 35 represents an NPN transistor for returning the voltage at the time signal output terminal to zero at a desired time so as to start fuel injection again; the collector is connected to the power line 24 via a resistor 36 and is connected in the forward direction to the collector of the transistor 22 via a diode 37. The base of the transistor is connected to a trigger input terminal 39 via a resistor 38.

In the region in which the engine manifold negative pressure P is larger than the set value P,, the terminal voltage of the voltage dividing resistor 29 is large. Ac-

p cordingly, the base potential of the transistor 22 to which the voltage divided through the resistor 27 and zener diode 28 is applied is kept constant at a relatively small value. Now, since the emitter of the transistor 22 is connected to the power line 24 via a resistor 23, the collector current takes the form of a constant current from which the capacitor 26 is charged. Under this condition, when a positive pulse voltage is applied to the terminal 39 from generator 4 at a desired time so as to restart the fuel injection, the transistor 35 is rendered conductive and the charge across the capacitor 26 is discharged to ground via the diode 37 and the transistor 35. As a result, the time signal voltage E at the output terminal 25 becomes zero. Then, when the transistor 35 becomes nonconducting, the capacitor 26 is charged by the constant collector current of the transistor 22, the terminal voltage is increased, and the time signal voltage E is delivered as a function of time from the time signal output terminal 25.

Following this operation, when the engine manifold negative pressure P is'reduced below the set value P,, the diaphragm device 33 is actuated to close the switch 32, the resistor 31 is connected in parallel to the voltage dividing resistor 29, and the terminal voltage of the resistor 31 is reduced. The reduced value of this terminal voltage serves to increase the base potential of the transistor 22. Consequently, the set value of the constant current flowing in the collector of the transistor 22 is reduced, the voltage charge across the capacitor 26 (namely, the output voltage E at the output terminal 25) is also reduced, and thus the time signal current conversion from I, to I, occurs, as shown in FIG. 7(a). However, with this operation, the voltage variation at the voltage dividing point of the resistors 29 and 30 is not changed abruptly, but is delayed by the capacitor 34. In other words, by suitably determining the value of the capacitor 34, it becomes possible to smoothly change over the fuel feed characteristics without causing shock.

In the foregoing circuit an Esaki diode and transistors are used as the adding level detector 6. Instead, a circuit, such as an operational amplifier circuit, capable of adding a plurality of input signals, such as a conditional signal or signals and a time signal, may be used as the level detecting circuit 6 with the present invention, or a circuit in which either the time signal or conditional signal is used for biasing the detected level may be used.

Also, the time signal generating means used for the above-described embodiment may be modified according to the requirements of a particular application other than the one mentioned herein.

According to this invention, as has been described, the conversion coefficient of the time signal versus time lapse is changed by the use of a specific engine manifold negative pressure, and thus the fuel feed characteristics can be compensated by simple procedures.

While the principles of the invention have been described above in connection with a specific embodiment and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What is claim is: 1. A fuel feed control system for controlling the supply of fuel fed to an engine in accordance with at least one engine operating condition, comprising condition detecting means for generating an electrical condition signal corresponding to the level of engine manifold pressure,

timing means for periodically generating a timing signal having a linearly increasing amplitude with time, and

level detecting means responsive to the sum of said condition and timing signals for generating a fuel control signal whose duration equals the time required for the sum of said condition and timing signals to reach a prescribed value,

said timing means including control means responsive to one given value of engine manifold pressure forming a critical point between the economical output region and the high output region of the engine operating characteristic for adjusting the rate of change of said timing signal from a first value to a second value.

2. A fuel feed control system as defined in claim 1, wherein said level detecting means includes summing means for summing said condition signal and said timing signal and switching means responsive to said summed signal value for providing said fuel control signal for all levels of said summed signal value below a given limit.

3. A fuel feed control system as defined in claim 2, wherein said condition detecting means generates a plurality of condition signals relating to different engine conditions and said summing means sums all of said condition signals with said timing signal.

4. A fuel feed control system as defined in claim 1, wherein said control means in said timing means includes delay means for gradually adjusting the rate of change of said timing signal upon detection of said given value of engine manifold pressure.

5. A fuel feed control system as defined in claim 4, wherein said timing means includes a pulse generator and a timing signal generating circuit responsive to the output of said pulse generator for generating a sawtooth wave timing signal.

6. A fuel feed control system as defined in claim 5, wherein said timing signal generating circuit includes a timing capacitor connected to a constant current source and means responsive to the output of said pulse generator for periodically discharging said timing capacitor, said control means including means responsive to said change'in engine manifold pressure for changing the level of the current generated by said constant current source.

7. A fuel feed control system as defined in claim 6, wherein said level detecting means includes summing means for summing said condition signal and said timing signal and switching means responsive to said summed signal value for providing said fuel control signal for all levels of said summed signal value below a given limit.

8. A fuel feed control system as defined in claim 7, wherein said condition detecting means generates a plurality of condition signals relating to different engine conditions and said summary means sums all of said condition signals with said timing signal.

9. A fuel feed control system as defined in claim 1, wherein said level detecting means comprises a plurality of resistances connecting a plurality of input terminals to a common summing point, an Esaki diode connected between said summing point and ground, and a transistor having its base connected to said summing point, its collector connected through a resistance to a power source and its emitter connected to ground, said timing means being connected to apply said timing signal to one of said input terminals and said condition detecting means applying a plurality of condition signals relating to different engine conditions to the remaining input terminals.

10. A fuel feed control system as defined in claim 9, wherein said timing means comprises a timing capacitor connected in series with a transistor constant current source, a pulse generator, a transistor switch connected to said pulse generator and said timing capacitor for periodically discharging said timing capacitor, and means for changing the level of said constant current source including a delay capacitor for effecting a delay in the change of current level of said constant current source.

l l. A fuel feed control system for controlling the supply of fuel fed to an engine in accordance with at least one engine operating condition, comprising condition detecting means for generating an electrical condition signal corresponding to said engine operating condition, said condition signal corresponding to a condition selected from the group consisting of manifold pressure, engine temperature and engine speed,

timing means for periodically generating a timing signal having a linearly increasing amplitude with time, said timing means including a pulse generator and a timing signal generating circuit responsive to the output of said pulse generator for generating a sawtooth wave timing signal, and

level detecting means responsive to the sum of said condition and timing signals for generating a fuel control signal whose duration equals the time required for the sum of said condition and timing signals to reach a prescribed value,

said timing means further including control means responsive to one given value of engine manifold pressure forming a critical point between the economical output region and the high output region of the engine operating characteristic for adjusting the rate of change of said timing signal from a first value for said economical output region to a second value for said high output region, said control means including delay means for gradually transferring the rate of said timing signal upon detection of said critical point from said first value for said economical output region to said second value for said high output region.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2644094 *Apr 27, 1949Jun 30, 1953Kellogg M W CoPulse generator
US3272187 *Sep 8, 1964Sep 13, 1966Ass Eng LtdFuel injection systems for internal combustion engines
US3314407 *Sep 28, 1964Apr 18, 1967Holley Carburetor CoElectronic advance for engine ignition systems
US3372680 *Feb 8, 1966Mar 12, 1968Bosch Gmbh RobertTime control circuit for fuel injection system
US3456628 *Apr 11, 1967Jul 22, 1969Sopromi Soc Proc Modern InjectHigh-speed fuel injection system
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3919981 *Jan 20, 1972Nov 18, 1975Bendix CorpCircuit for providing electronic enrichment fuel compensation in an electronic fuel control system
US3971348 *Apr 23, 1975Jul 27, 1976International Harvester CompanyComputer means for sequential fuel injection
US4015563 *Aug 27, 1975Apr 5, 1977Robert Bosch G.M.B.H.Stabilized fuel injection system
US4157701 *Jun 15, 1977Jun 12, 1979Hewitt John TDiesel engine control means
US4314538 *Feb 25, 1974Feb 9, 1982The Bendix CorporationElectronic fuel control system including electronic means for providing a continuous variable correction factor
US4811231 *Oct 19, 1987Mar 7, 1989Mazda Motor CorporationApparatus for controlling fuel injection and swirl motion of air in internal combustion engine
USRE29060 *May 20, 1974Dec 7, 1976The Bendix CorporationCircuit for providing electronic warm-up enrichment fuel compensation which is independent of intake manifold pressure in an electronic fuel control system
Classifications
U.S. Classification123/485, 123/492, 123/478
International ClassificationF02D41/32
Cooperative ClassificationF02D41/32
European ClassificationF02D41/32