|Publication number||US3646915 A|
|Publication date||Mar 7, 1972|
|Filing date||Jun 16, 1970|
|Priority date||Jun 16, 1970|
|Also published as||CA940620A1, DE2128064A1, DE2128064B2|
|Publication number||US 3646915 A, US 3646915A, US-A-3646915, US3646915 A, US3646915A|
|Inventors||Todd L Rachel|
|Original Assignee||Bendix Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (15), Classifications (8), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent Rachel Mar. 7, 1972  COLD START AUXILIARY CIRCUIT 3,504,657 4/1970 Eichler et al. ..123/119 R X FOR LE TR NI FUEL CONTROL 3,533,381 10/1970 Schmid... ..123/32 EA SYSTEM 3,513,815 5/1970 Mair ..l23/32 EA  lnventor: Todd L. Rachel, Elmira, NY.
 Assignee: The Bendix Corporation  Filed: June 16, 1970  Appl. No.: 46,706
 US. Cl. ..l23/32 EA, 123/139 E, 123/179 G, 123/ 187.5 R
 Int. Cl ..F02m 51/00  Field oiSearch.... ..123/32 EA, 119,179 A  References Cited UNITED STATES PATENTS 2,807,244 9/1957 Barclay ..123/32 EA T0 COLD START C/RC'U/T Primary Examiner-Laurence M. Goodridge Attorney-Robert A. Benziger and Plante, Hartz, Smith and Thompson  ABSTRACT An auxiliary circuit means is disclosed herein for controlling actuation of an injector valve means to provide for cold starting of an engine. The circuit and injector means are energized when a vehicle ignition system is energized and the fuel for cold starting is provided during the period of time required for a selected voltage value to raise to a threshold value. The threshold value is determined by a voltage divider including a temperature-responsive element sensing engine temperature. Means are provided to render the auxiliary circuit insensitive to supply voltage variations.
9 Claims, 3 Drawing Figures PAIENTEDMAR 7 m2 SHEET 1 UF 2 To COLD START WITNESS: 5%. m
ATTORNEY PATENTEBHAR 1 m2 3,646,915
' SHEET 2 UF 2 12$ gioa 76 70 73 g l 4% A 10 7 57-3 I I INVEN'IUR.
WITNESS B ATTORZVE Y COLD START AUXILIARY CIRCUIT FOR ELECTRONIC FUEL CONTROL SYSTEM CROSS-REFERENCE TO RELATED APPLICATIONS The present case is related to copending, commonly assigned application Ser. No. 46,681, Cold Start Auxiliary Circuit for Electronic Fuel Control System, by John R. Nagy et al., filed on June 16, 1970, and Ser. No. 46,705, Auxiliary Circuit for Electronic Fuel Control System to Facilitate Cold Starting, by John R. Nagy, Filed on June 16, 1970.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in electronic fuel control systems and particularly to improvements in automotive electronic fuel control systems whereby the cold start function is provided. In particular, the present invention provides a cold start circuit which is more reliable than previous circuits in that it is resistant to variations in the supply voltage and to false triggering.
2. Description of the Prior Art The known electronic fuel control systems currently rely upon the input information from their various parameter sensors to provide the information required by an electronic fuel control main computing system to provide cold start enrichment. These sensors, generally, sense the engine temperature which may be the temperature of the water jacket, to indicate the operating temperature of the engine, the engine speed to determine timing and engine fuel requirements, the intake manifold pressure to sense the load on the engine, and various other parameters as needed or desired.
For the purpose of this specification a cold" engine is one which, in attempting to assume ambient air temperature, has
cooled to a temperature below a selected level. This selected level may be empirically determined and is the temperature below which the difficulty of starting is increased beyond the capability of the main computing system to handle efficiently. The present electronic fuel control systems rely upon the engine temperature sensor input (or an equivalent such as ambient air temperature and cylinder head temperature) to vary the duration of injector valve open time sufficiently to provide fuel for the startup of the engine when the engine is cold. However, investigation has shown that this means of providing sufficient fuel for cold starting of an associated engine is not always adequate. It is, therefore, an objective of the present invention to provide control circuitry in addition to the electronic fuel control system to control provision of sufficient quantities of fuel for cold starting of an associated engine. It is a further object of the present invention to provide control circuitry for an electronic fuel control system which is capable of providing sufficient fuel for starting of an associated engine over a broad range of environmental temperatures.
One of the principal difficulties with the presently proposed methods of providing a cold-starting charge of fuel is that failure of the engine to start will permit excess quantities of fuel to be injected, resting in engine flooding. This problem also occurs upon too-frequent actuation of the cold start injector valve means. It is therefore an object of the present invention to provide a cold start auxiliary circuit which will not cause a flooding problem. More particularly it is a further object of the present invention to provide such a circuit which is adapted to energize an injector valve means a predetermined number of times for each energization of the starting motor. It is a still further object of the present invention to provide control circuitry to control the injection of a quantity of fuel sufficient to permit starting of a cold engine, which quantity of fuel may vary as a function of the temperature drop below a predetermined threshold value but which is independent of engine cranking. It is also an object of the present invention to provide a cold start circuit which prevents too-frequent actuation of the cold start injector valve means.
It is believed that many of the difiiculties encountered by the present method of cold starting are caused by the low r.p.m. of the associated engine during the cranking cycle and the proximity of the main injector nozzles to the intake ports of the engine to be started. It is, therefore, an object of the present invention to provide a circuit, in addition to the main electronic fuel control computing circuit, responsive to temperature for controlling an injector nozzle or valve means which may be situated independently of the main injector nozzles. It is a still further object of the present invention to provide a cold start fuel controlling circuit which may control the provision of a charge of fuel to the engine to be started independent of the engine cranking speed.
In the commonly assigned copending application MOC 69/ 18-3, a circuit for providing the desired colt start function is shown and described. However, the embodiment described therein, which includes two successively triggered monostable multivibrators, is known to be sensitive to variations in the level of the B+ voltage and to susceptible to premature, or false, triggering. These difficulties arise out of the use of successively triggered multivibrators so that it becomes a still further object of the present invention to provide a cold start circuit having the above-described advantages which does not employ multivibrators. It is an object of the present invention to provide a cold start auxiliary circuit whose output signal is relatively insensitive to variation of the supply over a wide range of voltages. It is still a further object of the present invention to provide a cold start auxiliary circuit which is insensitive to false triggering signals. In order to accomplish the last enumerated objective, it is an object of the present invention to provide a cold start auxiliary circuit for electronic fuel injection in which a substantial period of off", or inactive, time is required to enable the circuit to be reenergized.
SUMMARY OF THE PRESENT INVENTION The present invention provides a special function (cold start) auxiliary circuit for an electronic fuel control system capable of providing the improved cold start function. The cold start auxiliary circuit is adapted to provide an output signal of variable duration with the duration being a function of the drop of engine temperature below a selected level. The signal can be applied to-an injector nozzle or valve which may be situated independently from the main injector nozzles of the associated engine. The circuit is further adapted to be selfdisabling after generating a single pulse for each energization of the starting circuit of the associated engine to thereby prevent flooding of the engine. The inventive circuit is characterized by providing an output signal whose duration is substantially independent of the supply voltage. The circuit is further characterized by the fact that the circuit can be activated to energize the associated injector means only once for each application of supply voltage, after which time the supply voltage must be removed for a period of time.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows, in diagrammatic circuit form, an electronic fuel control system main computation circuit as adapted, for instance, for automotive use.
FIG. 2 shows, in diagrammatic circuit form, an auxiliary circuit according to the present invention for providing the cold start function.
FIG. 3 shows the relationship of the present invention to an automotive electrical system.
DETAILED DESCRIPTION Referring now to FIG. 1, an electronic fuel control system main computation circuit 10 is shown. The circuit is shown as being energized by a voltage supply designated as B+ at the various locations noted. In the application of this system to an automotive engine fuel control system, the voltage supply could be the battery and/or battery charging system conventionally used as the vehicles electric power source. The man skilled in the art will recognize that the electrical polarity of the voltage supply could readily be reversed.
The circuit receives, along with the voltage supply, various sensory inputs, in the form of voltage signals in this instance, indicative of various operating parameters of the associated engine. Intake manifold pressure sensor 12 supplies a voltage indicative of manifold pressure, temperature sensor 14 is operative to vary the voltage across the parallel resistance associated therewith to provide a voltage signal indicative of engine temperature and voltage signals indicative of engine speed are received at circuit input port 16. This signal may be derived from any source indicative of engine crank angle but is preferably from the engines ignition distributor, not shown.
The circuit 10 is operative to provide two consecutive pulses, of variable duration, through sequential networks to circuit location 18 to thereby control the on time of transistor 20. The first pulse is provided via resistor 22 from that portion of circuit 10 having inputs indicative of engine crank angle and intake manifold pressure. The termination of this pulse initiates a second pulse which is provided via resistor 24 from that portion of the circuit 10 having aninput from the temperature sensor 14. These pulses, received sequentially at circuit location 18, served to turn transistor on (that is, transistor 20 is triggered into the conduction state) and a relatively low voltage signal is present at circuit output port 26. This port may be connected, through suitable inverters and/or amplifiers (not shown) to the injector means (shown as 78 in FIG. 3) such that the selected injector means are energized whenever the transistor 20 is on. It is the current practice to use switching means to control which of the injector valve means are coupled to circuit location 26 when the system is used for actuation of less than all injector valve means at any one time. Because the injector valve means are relatively slow acting, compared with the speed of electronic devices, the successive pulses at circuit point 18 will result in the injector valve means remaining open until after the termination of the second pulse.
The duration of the first pulse is controlled by the monostable multivibrator network associated with transistors 28 and 30. The presence of a pulse received via input port 16 will trigger the multivibrator into its unstable state with transistor 28 in the conducting state and transistor 30 blocked (or in the nonconducting state). The period of time during which transistor 28 is conducting will be controlled by the voltage signal from manifold pressure sensor 12. Conduction of transistor 28 will cause the collector 28C thereof to assume a relatively low voltage close to the ground or common voltage. This low voltage will cause the base of 34b of transistor 34 to assume a low voltage below that required for transistor 34 to be triggered into the conduction state, thus causing transistor 34 to be turned off. The voltage at the collector 34c will, therefore, rise toward the B+ value and will be communicated via resistor 22 to circuit location 18 where it will trigger transistor 20 into the on" or conduction state thus imposing a relatively low voltage at circuit port 26. As hereinbefore stated, the presence of a low voltage signal at circuit port 26 will cause the selected injector valve means to open. When the voltage from the manifold pressure sensor 12 has decayed to the value necessary for the multivibrator to relax or return to its stable condition, transistor 30 will be triggered on and transistor 28 will be turned off. This will, in turn, cause transistor 34 to turn on, transistor 20 to turn off and thereby remove the injector control signal from circuit port 26.
During the period of time that transistor 34 has been held in the nonconducting, or off state, the relatively high voltage at collector 34c has been applied to the base of transistor 36, triggering the transistor 36 on". The resistor network 38, connected to the voltage supply, acts with transistor 36 as a current source and current flows through the conducting transistor 36 and begins to charge capacitor 40. Simultaneously, transistor 42 has been biased on and, with the resistor network 44, constitutes a second current source. Currents from both sources flow into the base of transistor 46 thereby holding this transistor on which results in a low voltage at the collector 460. This low voltage is communicated to the base of transistor 20 via resistor 24.
When transistor 28 turns off" signalling termination of the first pulse, transistor 34 turns on and the potential at the col lector 34c falls to a low value. The current from the current source, comprised of transistor 36 and resistor network 38, now flows through the base of transistor 36 and the capacitor 40 ceases to charge. The capacitor will then have been charged, with the polarity shown in FIG. 1, to a value representative of the duration of the first pulse. However, at the end of the pulse when transistor 34 is turned on, the collector-base junction of transistor 36 is forward biased, thus making the positive side of capacitor 40 only slightly positive with respect to ground since several PN junctions separate it from ground. This will impose a negative voltage on circuit location 48 which will reverse bias diode 50 and transistor 46 will be turned off. This will initiate a high voltage signal from the collector of transistor 46 to circuit location 18 via resistor 24 which signal will retrigger transistor 20 on" and a second injector means control pulse will appear at circuit port 26. The time duration between first and second pulses will be sufficiently short so that the injector means will not respond to the brief lack of signal.
While the diode 50 is reverse biased, the current from the current source comprised of transistor 42 and resistor network 44 will be flowing through circuit location 48 and into the capacitor 40 to charge the capacitor to the point that circuit location 48 will again be positive. This will then forward bias diode 50 and transistor 46 will turn back on. This will ter minate the second pulse and the injector valve means, not shown, will subsequently close.
The duration of the second pulse will be a function of the time required for circuit location 48 to become sufficiently positive for diode 50 to be forward biased. This in turn is a function of the charge on capacitor 40 and the magnitude of the charging current supplied by the current source comprised of transistor .42 and resistor network 44. The charge on capacitor 40 is, of course, a function of the duration of the first pulse. However, the rate of charge (i.e., magnitude of the charging current) is a function of the base voltage at transistor 42. This value is controlled by the voltage divider networks 52 and 54 with the effect of network 54 being variably controlled by the engine temperature sensor 14.
Referring now to FIGS. 1 and 2, and particularly to FIG. 2, a circuit is shown for providing the desired colt start characteristic. The circuit 100 is also energized by B+ as noted. Circuit 100 receives a temperature input at circuit location A from the correspondingly designated portion of control circuit 10. Alphabetic designations are used herein to denote points common to circuits in several figures. The temperature input or signal is comprised of a variable voltage whose value is controlled by the engine temperature sensor 14, shown as a thermistor in FIG. 1. The cold start circuit 100 is adapted to provide a single injection control pulse at circuit location 102 to control energization of the cold start injector valve means, shown as 76 in FIG. 3, which is preferably physically remote from the main electromechanical valve means. The cold start auxiliary circuit 100 includes zener diode 104, an emitter coupled pair of transistors 106, 108 and transistor switches and 112. The circuit also includes various resistor, capacitor and diode combinations to provide the desired voltage and current levels.
When power is applied at B+, as for instance by turning on of the ignition switch the base 106b of transistor 106 will be at the ground potential. The base 108!) of transistor 108 will be at some positive voltage level due to the temperature indication signal applied at point A due to the thermistor network shown in FIG. 1. This will cause transistor 108 to be conducting while transistor 106 is in the nonconducting state. The conduction of transistor 108 will cause a current flow through resistor 114 which will cause a voltage drop to appear across the emitter-base junction of transistor switch 110 which will cause transistor 110 to conduct. Conduction of transistor 110 will apply a voltage to the base 1l2b of transistor switch 112 which will, in turn, cause transistor 112 to conduct, thereby applying a voltage signal to circuit location 102 for application to the cold start injector means. During this time period the 13+ voltage via resistors 116 and 118 has been charging capacitor 120, thereby causing the voltage at base 106k of transistor 106 to increase. When the voltage at base l06b exceeds the voltage at base 108b, transistor 106 will turn on and transistor 108 will turn off. The turning off of transistor 108 will cause transistor switches 110 and 112 to switch ofi, thereby terminating cold start injection. The magnitude of the voltage signal applied at circuit point A is related to the temperature drop below. a selected level such that an engine temperature of 20 F. will produce a substantially greater magnitude signal than will an engine temperature of 50 F. By
proper tailoring of the rate at which the voltage at the base.
106b of transistor 106 will increase, the cold start injection period may be suitably tailored for various engines and various operating conditions.
Zener diode 104 is operative to maintain the voltage across resistor 118 and capacitor 120 at a fixed value regardless of the magnitude of B+. This, therefore, provides a stability of operation over a wide range of operating voltage levels such that the charging rate of capacitor 120 is maintained uniform for all values of B+. In addition, in extreme situations where B+ drops below the zener diode threshold level, capacitor-120 will charge more slowly. This is of advantage in lengthening cold start injection in those extreme situations where an electromechanical injector valve is energized by 8+ and is sluggish due to the low instantaneous value of B+. This configuration is of additional advantage in that once capacitor 120 is charged to the thermistor network threshold value, the transistor switches are maintained off while capacitor 120 continues to charge. Since capacitor 120 is provided with a discharge path via resistors 118 and 122 and the thermistor network (of FIG. 1), switching off of the supply voltage will permit the capacitor to discharge at a rate which, depending on the value of the capacitor and the various resistive values, will be sufiiciently slow to prevent false, or premature, triggering of the cold start injector valve means.
Referring'now to FIG. 3, the relationship of my invention to an automotive electrical system is illustrated. The computing circuit 10 andthe cold-starting auxiliary circuit 40 are shown as being connected to a vehicle battery 70 through switch 72 which may be, for instance, the vehicle ignition switch. In addition, fuel pumping means 74 is also shown as being connected to the electrical system such that closure of switch 72 will energize computing circuit 10, cold-starting circuit 100 and fuel pumping means 74. Circuits 10 and 100 are shown connected to fuel injector means 76 and 78 and control the energization thereof. As will be apparent from a consideration of FIGS. 2 and 3, once the injector valve means 76 has been energized and turned off, the cold start circuit will be in a charged up configuration and injector valve means 76 will not be reenergizable until after the circuit 100 has been deenergized for a period of time, as for instance by opening switch 72.
The cold start injection auxiliary circuit accomplishes its stated objectives. An output pulse is generated at circuit location 102 for application to the cold start injector valve means, not shown. The pulse duration is a function of the temperature drop of the associated engine below a selected level, independent of the supply voltage. Furthermore, the circuit is insensitive to false triggering since the circuit must be without power from the voltage supply (B+) for a period of time sufiicient to permit stored energy to be drained off before the cold start injector valve control switches 110 and 112 may be switched back on.
1. In combination with a battery-energizable internal combustion engine fuel control system, wherein battery energization is variable, of the type having engine-operating parameter sensor means including engine temperature sensor means operative to generate a signal having a level which increases in response to decreased in sensed engine temperature, a computing means responsive to the engine sensor means for controlling the actuation of injector valve means where the quantity of fuel delivered to the engine is controlled, the improvement comprising circuit means responsive to the engine temperature sensor operative to produce an output pulse having a duration related to the level of sensed signal whereby injector valve means may be energized by the pulse to provide a quantity of fuel in proportion to pulse duration for cold starting of the engine, said circuit including inhibiting means operative to limit said circuit means output pulse production to a predetermined maximum number of pulses per fuel system energization and further including energization level establishing means operative to maintain energization of said circuit means at a preselected level for battery variations above the preselected level and to variably energize said circuit means in proportion to battery variations below the preselected level.
2. The system as claimed in claim 1 wherein said predetermined maximum number of pulses is one.
3. The system as claimed in claim 1 including further time delay means operative to maintain the circuit means in an inhibited state for a predeterminable period of time following deenergization of said circuit means.
4. The system as claimed in claim 3 wherein said time delay means comprise a chargeable electrical element and a discharge path having a value which permits only a slow discharge of said element.
5. The system as claimed in claim 1 wherein said circuit means comprises:
an emitter coupled pair of transistors having a pair of bases,
one of said bases receiving the variable level signal indicative of sensed engine temperature;
capacitive means for applying a second variable level signal to the other of said bases, said second signal having a level which varies with time in a predeterrninable manner;
said transistors arranged for mutually exclusive conduction;
switching means responsive to the conductive state of one of said transistors to control actuation of the injector valve means; and
voltage regulator means for controlling the maximum voltage applied to said capacitive means. 6. The system as claimed in claim 5 wherein said capacitive means include a capacitor chargeable to a value in excess of said variable level engine temperature signal and resistive means for providing a slow discharge path for said capacitor whereby said other transistor base will be suitably biased for conduction for a period of time following removal of energization to prevent too frequent actuation of the associated injector valve means.
7. A fuel control system for engines having energizing means comprising in combination:
sensory means operative to sense at least one operating parameter of the engine, including engine temperature sensor means operative to generate a signal having a level which varies in relation to sensed engine temperature;
first energizable circuit means responsive to said sensory means operative to generate an output signal, said signal being comprised of a plurality of pulses having a duration indicative of the engine fuel requirement;
injection valve means; at least a portion of said injection valve means adapted to receive said output signal and to be periodically intermittently energized in response thereto to control fuel delivery to the engine;
second energizable circuit means, including means responsive to engine temperature, operative to generate a variable duration control pulse for application to at least a portion of said injection valve means upon energization of said second circuit means when sensed engine temperature is below a preselected level; and
inhibitory means coupled to said second circuit means operative to prevent reenergization of said second circuit means until said second circuit has been deenergized for a predeterminable period of time.
tive of engine temperature and a second signal which varies as a function of time from second circuit energization; I
first switching means responsive to said comparison means having a conducting state and a nonconducting state and operative to be in one of said states when said first signal is larger than said second signal and to be in the other of said states when said second signal is larger than said first signal; and
power follower switch means responsive to said first switch operative to change state with said first switch and to thereby generate a power output signal.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2807244 *||Oct 10, 1956||Sep 24, 1957||Bendix Aviat Corp||Cold start overspeed control for fuel injection system|
|US3504657 *||May 16, 1968||Apr 7, 1970||Bosch Gmbh Robert||System for enriching the fuel mixture on cold starts in an electrically controlled injection system for an internal combustion engine|
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|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3771502 *||Jan 20, 1972||Nov 13, 1973||Bendix Corp||Circuit for providing electronic warm-up enrichment fuel compensation which is independent of intake manifold pressure in an electronic fuel control system|
|US3786344 *||Oct 4, 1971||Jan 15, 1974||Motorola Inc||Voltage and current regulator with automatic switchover|
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|US5469825 *||Sep 19, 1994||Nov 28, 1995||Chrysler Corporation||Fuel injector failure detection circuit|
|US7121245 *||Dec 7, 2005||Oct 17, 2006||Yanmar Co., Ltd.||Injection control device for fuel injection pump|
|US20060112936 *||Dec 7, 2005||Jun 1, 2006||Masamichi Tanaka||Injection control device for fuel injection pump|
|USRE29060 *||May 20, 1974||Dec 7, 1976||The Bendix Corporation||Circuit for providing electronic warm-up enrichment fuel compensation which is independent of intake manifold pressure in an electronic fuel control system|
|USRE31391 *||Jan 14, 1976||Sep 20, 1983||Motorola, Inc.||Voltage and current regulator with automatic switchover|
|EP0315745A2 *||Aug 31, 1988||May 17, 1989||WALBRO CORPORATION (Corporation of Delaware)||Cold-start engine priming and air purging system|
|EP1645739A1 *||Apr 28, 2004||Apr 12, 2006||Yanmar Co. Ltd.||Fuel injection control device for fuel injection pump|
|U.S. Classification||123/491, 261/DIG.800, 123/179.16, 261/39.5|
|Cooperative Classification||F02D41/064, Y10S261/08|
|Dec 7, 1988||AS||Assignment|
Owner name: SIEMENS-BENDIX AUTOMOTIVE ELECTRONICS L.P., A LIMI
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:ALLIED-SIGNAL INC.;REEL/FRAME:005006/0282
Effective date: 19881202