CA1110735A - Deceleration fuel control in fuel injection system - Google Patents
Deceleration fuel control in fuel injection systemInfo
- Publication number
- CA1110735A CA1110735A CA277,591A CA277591A CA1110735A CA 1110735 A CA1110735 A CA 1110735A CA 277591 A CA277591 A CA 277591A CA 1110735 A CA1110735 A CA 1110735A
- Authority
- CA
- Canada
- Prior art keywords
- engine
- manifold pressure
- function
- injection system
- fuel injection
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/04—Introducing corrections for particular operating conditions
- F02D41/12—Introducing corrections for particular operating conditions for deceleration
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/30—Controlling fuel injection
- F02D41/32—Controlling fuel injection of the low pressure type
- F02D41/36—Controlling fuel injection of the low pressure type with means for controlling distribution
- F02D41/365—Controlling fuel injection of the low pressure type with means for controlling distribution with means for controlling timing and distribution
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A fuel injection system for an internal combustion, spark ignited engine, including injectors disposed in proximity to the engine intake valves, employs an R-C time circuit for generating actuating pulses to the injectors. The capacitor of the time circuit is charged to a voltage which is a function of the manifold pressure, and upon receipt of a triggering signal, generated in timed relation to the engine operation, discharges through the resistance of the time circuit which is varied as a function of other engine operating parameters. To modify the charge of fuel that is provided to the engine during deceleration, the capacitor differentiates a voltage from a sensor measuring manifold pressure and controls the conductivity of a transistor shunting the resistance in the discharge path of the time circuit. In an alternative embodiment, a resis-tance element in the discharge path of a pulse generating time circuit is varied by a mechanical differentiator device having an element positioned as a function of the rate of decrease in manifold pressure.
A fuel injection system for an internal combustion, spark ignited engine, including injectors disposed in proximity to the engine intake valves, employs an R-C time circuit for generating actuating pulses to the injectors. The capacitor of the time circuit is charged to a voltage which is a function of the manifold pressure, and upon receipt of a triggering signal, generated in timed relation to the engine operation, discharges through the resistance of the time circuit which is varied as a function of other engine operating parameters. To modify the charge of fuel that is provided to the engine during deceleration, the capacitor differentiates a voltage from a sensor measuring manifold pressure and controls the conductivity of a transistor shunting the resistance in the discharge path of the time circuit. In an alternative embodiment, a resis-tance element in the discharge path of a pulse generating time circuit is varied by a mechanical differentiator device having an element positioned as a function of the rate of decrease in manifold pressure.
Description
73~
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to fuel injection systems for an internal combustion, spark ignited engine including means for modifying the fuel charge supplied to the engine during deceleration.
BACKGROUND OF THE INVENTION
1. Field of the Invention This invention relates to fuel injection systems for an internal combustion, spark ignited engine including means for modifying the fuel charge supplied to the engine during deceleration.
2. Prior Art Fuel injection systems for internal combustion, spark ignited engines have been developed which provide each cylinder with a measured quantity of fuel during each engine cycle. The systems employ sensors for mani-fold pressure, engine temperature, and other engine operating parameters, and control the fuel charcJe as a function of these parameters. These systems were initially ~devised to improve the fuel economy and performance of the engine relative to that obtainable with a conventional carburetor and their popularity has increased in the last few years because of their ability to minimize engine emission pollutants through accurate control of the fuel-20 air ratio. The systems typically measure manifold pressure, engine temperature and other parameters, and provide the ;' engine with a suEficient charge of fuel at a desired fuel-air ratio. The fuel charge is provided to the inta~e system of the engine at intervals bearing a timedrelation-ship to the engine operation, such as once per engine cycle.
~ y U.S. Patent 4,05g,709 discloses a fuel injection system wherein the injectors take the form of normally closed, electrically energized, valves 30 that provide fuel to the immediate vicinity of the intake valves externally of -the cylinders. In order to maximize the vaporization of this liqùid fuel charge before it is admitted to the cylinder, the in]ection time is preferably controlled to -lA-~3;.
;
~ y U.S. Patent 4,05g,709 discloses a fuel injection system wherein the injectors take the form of normally closed, electrically energized, valves 30 that provide fuel to the immediate vicinity of the intake valves externally of -the cylinders. In order to maximize the vaporization of this liqùid fuel charge before it is admitted to the cylinder, the in]ection time is preferably controlled to -lA-~3;.
;
3~
closely follow the closing of the engine intake val~e. The charge is then heated by the intake valve to promote vaporization before the engine intake valve opens. The highly vaporized charge burns more completely.
The fuel injection system thus measures the engine parameters at one instant once per engine cycle and injects a quantity of fuel based upon those measurements. If the engine air flow is substantially constant Erom cycle to cycle, the injected quantity of fuel should be correct to produce the desired fuel-air ratio, but if the engine air flow varies more than a predetermined a~.ount during an engine cycle, such as during deceleration, the previously injected fuel quantity will cause the ~uel-air ratio to var~ from a desired optimum.
The dif~erence between the actual injected fuel quantity and the calculated optimum quantity is a function of both the engine speed and the rate of change of engine speed. At high speeds, relatively little time elapses between the calculation of the desired fuel charge and its passage into the cylinder, but the delay is greater at lower speeds. A rapid deceleration occurring at a lower engine speed may result in an appreciable departure in the injected fuel quantity from the optimum in rela-tion to instantaneous engine air flow. During deceleration, the engine may receive too large a fuel charge and the engine emis-sions will sharply increase temporarily. Additionally, this overly rich charge will combine with all of the air admitted to the engine cylinder during combustion and if the engine is equipped with a catalytlc converter the exhaust will not contain sufficient uncombined oxygen to allow proper converter operation, further increasing the emission pollutants.
SUMMARY OF T~E INVENTION
The present invention is directed toward a fuel injec-tion system that modifies the fuel charge provided to the engine )73S
during deceleration to bring the delivered fuel charge into closer correlation with the charge required at the time of intake into the engine cylinder than would otherwise occur, and more particu-larly to a system that modifies the fuel charge in proportion to the rate of deceleration of the engine on a per cycle basis to prevent the supply of an excessive fuel charge which would cause a momentary increase in undesirable engine emissions.
A preferred embodiment of the invention, which will subsequently be disclosed in detail, employs electromagnetically actuated injectors, which are actuated once each engine cycle for a period of time determined by an electric pulse generated by a circuit. The circuit employs a capacitor which is charged to a voltage that is a function of the manifold pressure, and upon receipt of a trigge~ing signal, discharges through a resis-tance. The value of the resistance and the voltage level imposed at the end of the resistance opposite to the capacitor, are determined by other engine operating parameters. An injector actuating pulse is generated during the discharge of the capa-citor.
To modify the pulse duration as a function of the rate of deceleration of the vehicle, a discharge resistor is shunted by the emitter-collector circuit of a transistor and the state of conduction of the transistor is controlled by the voltage on one end of a capacitor that receives a voltage proportional to the rate of change of the manifold pressure at its other end.
As the engine decelerates, the manifold pressure decreases and applies an increasing voltage to the capacitor. The capacitor couples this changing voltage to the base of the transistor, increasing its conduction to effectively decrease the value of the discharge resistance and decrease the discharge time.
In an alternative embodiment of the inventivn, the ; 3 3~i manifold pressure is imposed on a diaphragm connected to a movable arm of a potentiometer. A decrease in manifold pressure causes the diaphragm to move and a vent then allows ~he pressure to equalize across the diaphragm, allowing the diaphragm to return to its original position. The potentiometer signal in combina-tion with a transistor shunts the discharge resistance in the pulse generating circuit.
The present invention thus modifies the actuating pulse duration to the injectors in response to a decreasing maniEold pressure signal, thereby decreasing the quantity oE fuel provided to the enginé during deceleration to prevent transient increases in emission pollutants. The present invention is extremely simple, so as to be low in cost and reliable ln operation.
Other objectives, advantages and applications of the : present invention will be made apparent by the follo~ling detailed description of a preferred embodiment of the invention. The description makes reference to the accompanyin~ drawings in which:
DESCRIPTION OF THE DRAWINGS
-FIGURE 1 is a partially schematic, partially block diagram of a fuel injection system having a preferred embodiment of the present invention, detailing components associated with a single engine cy:Linder;
FIGURE ~ is a schematic diagram of ~he variable width pulse generator used with the system of FIGURE 1 and incorporating : fuel charge modification means for decreasing the injector actuat-ing pulse duration during engine deceleration; and FIGURE 3 is an illustration of an alternative embodiment of deceleration sensor useful with the systesn of FIGURE 1.
DETAILED DESCRIPT:tON
Referring to the drawings, FIGURE 1 illustrates an ignition and fuel injection system associated ~:ith a c.ingle 3~
cylinder 10 of an internal combustion, spark ignited engine for a vehicle, such as that disclosed in my Canadian Patent 1,075,987~ A fuel charge admitted to the cylinder 10 through an engine intake valve 12 is ignited at an appropriate time in the engine cycle by a spark plug 14. The spark plug 14 is energized through a distributor 16 having its rotor 17 connected to -the secondary circuit of an ignition coil 18. The rotor 17 is driven in timed relation to the engine rotation. The other dis-tributor contacts are connected to spark plugs associatedwith other engine cylinders (not shown).
The primary circuit of the ignition coil 18 is energized in timed relation to the engine operation by a vehicle battery 20 through breaker points 22. A capacitor 24 shunts the breaker points 22.
The primary circuit of the ignition coil 18 is also connected to a multi-stage counter 26 so that the counter 26 receives an electric pulse each time the breaker points 22 are actuated by the engine. The counter 20 26 has a plurality of output lines 28 and these are sequentially energized as the counter 26 is advanced by the input pulses from the ignition primary circuit.
One of the counter output lines 28 is provided as a triggering input to a variable width pulse genera-tor 30 and the other counter outputs are provided to similar pulse genera-tors associated with the other engine cylinders (not shown). The variable width pulse generator 30 also receives outputs from a group of engine sensors 32 which may measure engine tempera-ture, and other engine and 30 and environmental parameters. The engine sensors 32 provide controlling signals to the pulse generator 30 as _5_ ` ' ?
, ~ . .
a function of these parameters. The variable width ~ `
pulse generator 30 receives another electrical signal, proportional to the pressure in the engine intake mani~
fold 34, either a vacuum with ,~ :
`:
;~:
~ ~5A- ` :
3~ii reference to atmospheric pressure or an absolute pressure, ~rom a pressure sensor 36 associated with the manifold 34. In a preferred embodiment, a differential pressure sensor is used to measure manifold pressure. In alternative embodiments of the invention, the outputs of the sensor 36 may be proportional to the absolute pressure in the manifold 34 as opposed to the differ-ential pressure between the pressure in manifold 34 and atmos-pheric pressure in normally aspirated engines.
The output of the pressure sensor 36 is also provided to a differentiator circuit 38 which generates an electric output signal proportional to the rate of change of decreasing manifold pressure and provides such output to the variable width pulse generator 30.
Upon receipt of a triggering pulse on line 28, the variable width pulse generator 30 generates an electric output pulse on line 40 having a duration that is a function of the inputs from sensors 32 and 36 and the differential circuit 38.
This signal on line 40 is applied to the coil 42 of an electro-magnetically operated injector 44. The injector 44 is connected to a constant pressure fuel source 46 and is preferably disposed so as to dispense fuel to the area of the intake valve 12, exter-nally of the engine cylinder 10. The volume of fuel dispensed by the injector 44 will be proport.ional to the duration o~ a pulse received on line ~0~ The timing of the pulse on lîne 40 is such that the injector 44 is usually actuated once per engine cycle, although it may be actuated more often, particularly during engine start-up.
This single injector pulse per engine cycle is prefer-ably timed to occur immediately after closing of the intake valve 12 so that the injected charge may be heated to a ma:Kimum degree by the intake valve 12 before being admitted to the cylinder.
)7~5 The system of FIGURE 1 differs from conventional fuelinjection systems primarily in the provision of the circuit 38 for differentiating the output of the pressure sensor 36, and in the provision of a variable width pulse generator 30 that is sensitive to the output of the circuit 38 t:o decrease the duration of the output pulse on line 40 as a function of the rate of decrease in manifold pressure above a predetermined rate of decreaser i.e. in addition to the normal decrease inherently provided by the pressure sensor 36. This decrease occurs during deceleration of the engine and the resultant diminished fuel charge is thus more closely tailored to the engine requirements during deceleration when the intake valve 12 opens, and the fuel c~arge is admitted to the cylinder 10, a time interval after the occurrence of the injector pulse.
FIGURE 2 is a detailed schematic diagram of a preferred form of the variable width pulse generator 30, the pressure sensor 36 and the differential circuit 38.
The triggering pulses to the variable width pulse generator 30, from the counter 26, on line 28, take the form of sharp-edged, negative-going pulses. These pulses are applied to the base of a PNP translstor 48 having its emitter connected to the positive side of the power supply through resistor 50. The collector of the transistor 48 is connected to one side of a capacitor 52 forming part of a resistance-capacitance circuit.
The discharge resistance of the circuit is formed by the series combination of a resistor 54 and an engine sensor 56, part of the sensor group 32 designated in FIGU~E 1, which acts in some respects like a variable resistor, and is schematically desig-nated as such. The sensor 56 is primarily sensitive to engine temperature and may be a thermistor.
The collector of transistor 48 is also connected 73~ ` :
through a resistor 58 to the variable terminal of a potentlometer60 having its resistance element connected between the positive terminal of the voltage supply and ground. The position of the variable contact of the potentiometer 60 is controlled by the manifold pressure sensor 36. The sensor 36 is schematically illustrated as a piston 62 movable within a cylinder 64 and biased by a spring 66 disposed within the cylinder 64. The mani-fold 34 is connected to the spring end of the cylinder 64 by a conduit 68. The position of the piston 62 is thus a function of the differential pressure between the manifold 34 and atmospheric pressure. The pressure differential biases the spring 66 toward its compressed condition. The piston 62 is connected to the mov-able contact of the potentiometer 60 so that the voltage at one side of the capacitor 52 is a function of the manifold differen-tial pressure.
The junction of the capacitor 52 and the resistor 54 is connected to the base of a second PNP transistor 70 having its emitter connected to the emitter of transistor 48 and its collector connected to ground through a pair of resistors 77 and 78. The mid-point of these two resistors 77 and 78 is connected to a driver amplifier 79 and represents the output of the variable width pulse generator 30.
Considering the operation of the pulse generator 30, a triggering pulse on line 28 takes the form of a negative-going pulse, and in the absence of this triggering pulse the transis-tor 48 operates in a saturated conduction region. Transistor 70 is similarly conductive at this time so the voltage on capacitor 52 is substantially equal to the emitter voltage of transistor 70. Vpon receipt of a negative-going pulse on line 28, transis-tor 48 is switched out of conduction, allowing the capacitor 52to charge to a voltage dependent upon the difference between 3~ ~
the emitter voltage of transistor 70 and the voltage provided by the manifold pressure potentiometer 60, through resistor 58.
When the negative-going pulse to the base of transis-tor 48 terminates, the transistor 4~ immediately becomes con-ductive again and the voltage at the base of transistor 70 goes sharply positive by an amount proportional to the charge on the capacitor 52, turning off transistor 70. Capacitor 52 then begins to discharge through resistor 54 and the equivalent resis~
tance provided by the device 56. This discharge continues until the voltage across capacitor 52 reaches the emitter voltage of transistor 70, causing the transistor 70 to turn on and to clamp the voltage on capacitor 52 to a value substantially equal to the emitter voltage of transistor 70.
The time during which transistor 70 is turned off is therefore dependent upon the variable voltage provided by the potentiometer 60, which controls the voltage to which the capa-citor 52 charges during the off time of transistor 48, and to the variable resistance provided by the device 56 in cornbination with resistor 54, which controls the rate at which the capacitor 52 discharges after the transistor 48 becomes conductive.
This time is modified by the differentiator circuit 38 which takes the form of a resistor 71 and a capacitor 72 connected between the variable contact of the potentiometer 60 and the base of an NPN transistor 74. The emitter-collector circuit of tran-sistor 74 shunts resistor 54. The base of transistor 74 is connected to ground through a resistance 7~. The capacitor 72 acts to differentiate the voltage across the movable contact of the potentiometer 60 so as to provide a~ signal to the base of transistor 74 when a decreasing change occurs in ma:nifold differ-ential pressure above a predetermined rate of change in pressure.As the manifold differential pressure decreases, during decele-_ g ~a ~
ration of the engine, the voltage applied to capacitor 72increases, and the transistor 74 is rendered more conductive, decreasing the effective resistance in the discharge path of capacitor 52 and shortening the time required for the capacitor 52 to discharge. This effectively decreases the injector pulse time during engine decelera~ion. If ~he deceleration is suddenly terminated and the engine is accelerated, the resultant change of voltage will cause the capacitor 72 to discharge through potentiometer 60 and thus terminate the pulse shortening effect immediateiy.
In another embodiment of the present invention, a separate mechanical device may be used in place of the manifold pressure sensor 36 and the differentiator 38 as illustrated in FIGURES 1 and 2. The device, generally indicated at 80, comprises a closed housing 82 having an elastic diaphragm 84 dividing it into a pair of compartments 86 and 88. The diaphragm 84 is biased in the direction of compartment 88 by a compression spring 90.
A conduit 92 connects the chamber 88 to the engine intake manifold 34. The chambers 86 and 88 are connected by a vent device 94 which by-passes the diaphragm 84 and has a restriction 96 which controls the rate of air flow ~etween the chambers 86 and 88.
The diaphragm 84 is connected to the movable contact of a potentiometer 98 connected between the positive terminal of the power supply and ground. The movable contact of the poten~
tiometer 98 is connected to the base of a transistor 100 which is the equivalent of transistor 74 in FIGURE 2, having its emitter-collector circuit shuntin~ the resistor 54 in the dis-charge path of the R-C circuit.
When the manifold pressure decreases, the pressure in chamber 88 is decreased and the diaphragm 84 is moved toward chamber 88, expanding the spring 90. This causes a movement of the movable contact of the potentiometer 98, and increases the voltage at the base of NPN transistor 100, increasing its con-ductivity, and decreasing the effective resistance of the discharge path of the R-C circuit. Thus, the duration oE a pulse generated by the circuit 36 is decreased. The effect is transient, however, because the decrease in pressure in chamber 86 causes air to bleed through the by~pass 94 and restriction 96, into the chamber 88, and thus restore the pressure balance on the diaphragm 84. An increase in manifold pressure, resulting from an acceleration of the vehicle, tends to increase the resis-tance of the emitter-collector path of transistor 100, restoring the normal discharge path of the R-C circuit and the normal dura-tion of the injector pulse.
closely follow the closing of the engine intake val~e. The charge is then heated by the intake valve to promote vaporization before the engine intake valve opens. The highly vaporized charge burns more completely.
The fuel injection system thus measures the engine parameters at one instant once per engine cycle and injects a quantity of fuel based upon those measurements. If the engine air flow is substantially constant Erom cycle to cycle, the injected quantity of fuel should be correct to produce the desired fuel-air ratio, but if the engine air flow varies more than a predetermined a~.ount during an engine cycle, such as during deceleration, the previously injected fuel quantity will cause the ~uel-air ratio to var~ from a desired optimum.
The dif~erence between the actual injected fuel quantity and the calculated optimum quantity is a function of both the engine speed and the rate of change of engine speed. At high speeds, relatively little time elapses between the calculation of the desired fuel charge and its passage into the cylinder, but the delay is greater at lower speeds. A rapid deceleration occurring at a lower engine speed may result in an appreciable departure in the injected fuel quantity from the optimum in rela-tion to instantaneous engine air flow. During deceleration, the engine may receive too large a fuel charge and the engine emis-sions will sharply increase temporarily. Additionally, this overly rich charge will combine with all of the air admitted to the engine cylinder during combustion and if the engine is equipped with a catalytlc converter the exhaust will not contain sufficient uncombined oxygen to allow proper converter operation, further increasing the emission pollutants.
SUMMARY OF T~E INVENTION
The present invention is directed toward a fuel injec-tion system that modifies the fuel charge provided to the engine )73S
during deceleration to bring the delivered fuel charge into closer correlation with the charge required at the time of intake into the engine cylinder than would otherwise occur, and more particu-larly to a system that modifies the fuel charge in proportion to the rate of deceleration of the engine on a per cycle basis to prevent the supply of an excessive fuel charge which would cause a momentary increase in undesirable engine emissions.
A preferred embodiment of the invention, which will subsequently be disclosed in detail, employs electromagnetically actuated injectors, which are actuated once each engine cycle for a period of time determined by an electric pulse generated by a circuit. The circuit employs a capacitor which is charged to a voltage that is a function of the manifold pressure, and upon receipt of a trigge~ing signal, discharges through a resis-tance. The value of the resistance and the voltage level imposed at the end of the resistance opposite to the capacitor, are determined by other engine operating parameters. An injector actuating pulse is generated during the discharge of the capa-citor.
To modify the pulse duration as a function of the rate of deceleration of the vehicle, a discharge resistor is shunted by the emitter-collector circuit of a transistor and the state of conduction of the transistor is controlled by the voltage on one end of a capacitor that receives a voltage proportional to the rate of change of the manifold pressure at its other end.
As the engine decelerates, the manifold pressure decreases and applies an increasing voltage to the capacitor. The capacitor couples this changing voltage to the base of the transistor, increasing its conduction to effectively decrease the value of the discharge resistance and decrease the discharge time.
In an alternative embodiment of the inventivn, the ; 3 3~i manifold pressure is imposed on a diaphragm connected to a movable arm of a potentiometer. A decrease in manifold pressure causes the diaphragm to move and a vent then allows ~he pressure to equalize across the diaphragm, allowing the diaphragm to return to its original position. The potentiometer signal in combina-tion with a transistor shunts the discharge resistance in the pulse generating circuit.
The present invention thus modifies the actuating pulse duration to the injectors in response to a decreasing maniEold pressure signal, thereby decreasing the quantity oE fuel provided to the enginé during deceleration to prevent transient increases in emission pollutants. The present invention is extremely simple, so as to be low in cost and reliable ln operation.
Other objectives, advantages and applications of the : present invention will be made apparent by the follo~ling detailed description of a preferred embodiment of the invention. The description makes reference to the accompanyin~ drawings in which:
DESCRIPTION OF THE DRAWINGS
-FIGURE 1 is a partially schematic, partially block diagram of a fuel injection system having a preferred embodiment of the present invention, detailing components associated with a single engine cy:Linder;
FIGURE ~ is a schematic diagram of ~he variable width pulse generator used with the system of FIGURE 1 and incorporating : fuel charge modification means for decreasing the injector actuat-ing pulse duration during engine deceleration; and FIGURE 3 is an illustration of an alternative embodiment of deceleration sensor useful with the systesn of FIGURE 1.
DETAILED DESCRIPT:tON
Referring to the drawings, FIGURE 1 illustrates an ignition and fuel injection system associated ~:ith a c.ingle 3~
cylinder 10 of an internal combustion, spark ignited engine for a vehicle, such as that disclosed in my Canadian Patent 1,075,987~ A fuel charge admitted to the cylinder 10 through an engine intake valve 12 is ignited at an appropriate time in the engine cycle by a spark plug 14. The spark plug 14 is energized through a distributor 16 having its rotor 17 connected to -the secondary circuit of an ignition coil 18. The rotor 17 is driven in timed relation to the engine rotation. The other dis-tributor contacts are connected to spark plugs associatedwith other engine cylinders (not shown).
The primary circuit of the ignition coil 18 is energized in timed relation to the engine operation by a vehicle battery 20 through breaker points 22. A capacitor 24 shunts the breaker points 22.
The primary circuit of the ignition coil 18 is also connected to a multi-stage counter 26 so that the counter 26 receives an electric pulse each time the breaker points 22 are actuated by the engine. The counter 20 26 has a plurality of output lines 28 and these are sequentially energized as the counter 26 is advanced by the input pulses from the ignition primary circuit.
One of the counter output lines 28 is provided as a triggering input to a variable width pulse genera-tor 30 and the other counter outputs are provided to similar pulse genera-tors associated with the other engine cylinders (not shown). The variable width pulse generator 30 also receives outputs from a group of engine sensors 32 which may measure engine tempera-ture, and other engine and 30 and environmental parameters. The engine sensors 32 provide controlling signals to the pulse generator 30 as _5_ ` ' ?
, ~ . .
a function of these parameters. The variable width ~ `
pulse generator 30 receives another electrical signal, proportional to the pressure in the engine intake mani~
fold 34, either a vacuum with ,~ :
`:
;~:
~ ~5A- ` :
3~ii reference to atmospheric pressure or an absolute pressure, ~rom a pressure sensor 36 associated with the manifold 34. In a preferred embodiment, a differential pressure sensor is used to measure manifold pressure. In alternative embodiments of the invention, the outputs of the sensor 36 may be proportional to the absolute pressure in the manifold 34 as opposed to the differ-ential pressure between the pressure in manifold 34 and atmos-pheric pressure in normally aspirated engines.
The output of the pressure sensor 36 is also provided to a differentiator circuit 38 which generates an electric output signal proportional to the rate of change of decreasing manifold pressure and provides such output to the variable width pulse generator 30.
Upon receipt of a triggering pulse on line 28, the variable width pulse generator 30 generates an electric output pulse on line 40 having a duration that is a function of the inputs from sensors 32 and 36 and the differential circuit 38.
This signal on line 40 is applied to the coil 42 of an electro-magnetically operated injector 44. The injector 44 is connected to a constant pressure fuel source 46 and is preferably disposed so as to dispense fuel to the area of the intake valve 12, exter-nally of the engine cylinder 10. The volume of fuel dispensed by the injector 44 will be proport.ional to the duration o~ a pulse received on line ~0~ The timing of the pulse on lîne 40 is such that the injector 44 is usually actuated once per engine cycle, although it may be actuated more often, particularly during engine start-up.
This single injector pulse per engine cycle is prefer-ably timed to occur immediately after closing of the intake valve 12 so that the injected charge may be heated to a ma:Kimum degree by the intake valve 12 before being admitted to the cylinder.
)7~5 The system of FIGURE 1 differs from conventional fuelinjection systems primarily in the provision of the circuit 38 for differentiating the output of the pressure sensor 36, and in the provision of a variable width pulse generator 30 that is sensitive to the output of the circuit 38 t:o decrease the duration of the output pulse on line 40 as a function of the rate of decrease in manifold pressure above a predetermined rate of decreaser i.e. in addition to the normal decrease inherently provided by the pressure sensor 36. This decrease occurs during deceleration of the engine and the resultant diminished fuel charge is thus more closely tailored to the engine requirements during deceleration when the intake valve 12 opens, and the fuel c~arge is admitted to the cylinder 10, a time interval after the occurrence of the injector pulse.
FIGURE 2 is a detailed schematic diagram of a preferred form of the variable width pulse generator 30, the pressure sensor 36 and the differential circuit 38.
The triggering pulses to the variable width pulse generator 30, from the counter 26, on line 28, take the form of sharp-edged, negative-going pulses. These pulses are applied to the base of a PNP translstor 48 having its emitter connected to the positive side of the power supply through resistor 50. The collector of the transistor 48 is connected to one side of a capacitor 52 forming part of a resistance-capacitance circuit.
The discharge resistance of the circuit is formed by the series combination of a resistor 54 and an engine sensor 56, part of the sensor group 32 designated in FIGU~E 1, which acts in some respects like a variable resistor, and is schematically desig-nated as such. The sensor 56 is primarily sensitive to engine temperature and may be a thermistor.
The collector of transistor 48 is also connected 73~ ` :
through a resistor 58 to the variable terminal of a potentlometer60 having its resistance element connected between the positive terminal of the voltage supply and ground. The position of the variable contact of the potentiometer 60 is controlled by the manifold pressure sensor 36. The sensor 36 is schematically illustrated as a piston 62 movable within a cylinder 64 and biased by a spring 66 disposed within the cylinder 64. The mani-fold 34 is connected to the spring end of the cylinder 64 by a conduit 68. The position of the piston 62 is thus a function of the differential pressure between the manifold 34 and atmospheric pressure. The pressure differential biases the spring 66 toward its compressed condition. The piston 62 is connected to the mov-able contact of the potentiometer 60 so that the voltage at one side of the capacitor 52 is a function of the manifold differen-tial pressure.
The junction of the capacitor 52 and the resistor 54 is connected to the base of a second PNP transistor 70 having its emitter connected to the emitter of transistor 48 and its collector connected to ground through a pair of resistors 77 and 78. The mid-point of these two resistors 77 and 78 is connected to a driver amplifier 79 and represents the output of the variable width pulse generator 30.
Considering the operation of the pulse generator 30, a triggering pulse on line 28 takes the form of a negative-going pulse, and in the absence of this triggering pulse the transis-tor 48 operates in a saturated conduction region. Transistor 70 is similarly conductive at this time so the voltage on capacitor 52 is substantially equal to the emitter voltage of transistor 70. Vpon receipt of a negative-going pulse on line 28, transis-tor 48 is switched out of conduction, allowing the capacitor 52to charge to a voltage dependent upon the difference between 3~ ~
the emitter voltage of transistor 70 and the voltage provided by the manifold pressure potentiometer 60, through resistor 58.
When the negative-going pulse to the base of transis-tor 48 terminates, the transistor 4~ immediately becomes con-ductive again and the voltage at the base of transistor 70 goes sharply positive by an amount proportional to the charge on the capacitor 52, turning off transistor 70. Capacitor 52 then begins to discharge through resistor 54 and the equivalent resis~
tance provided by the device 56. This discharge continues until the voltage across capacitor 52 reaches the emitter voltage of transistor 70, causing the transistor 70 to turn on and to clamp the voltage on capacitor 52 to a value substantially equal to the emitter voltage of transistor 70.
The time during which transistor 70 is turned off is therefore dependent upon the variable voltage provided by the potentiometer 60, which controls the voltage to which the capa-citor 52 charges during the off time of transistor 48, and to the variable resistance provided by the device 56 in cornbination with resistor 54, which controls the rate at which the capacitor 52 discharges after the transistor 48 becomes conductive.
This time is modified by the differentiator circuit 38 which takes the form of a resistor 71 and a capacitor 72 connected between the variable contact of the potentiometer 60 and the base of an NPN transistor 74. The emitter-collector circuit of tran-sistor 74 shunts resistor 54. The base of transistor 74 is connected to ground through a resistance 7~. The capacitor 72 acts to differentiate the voltage across the movable contact of the potentiometer 60 so as to provide a~ signal to the base of transistor 74 when a decreasing change occurs in ma:nifold differ-ential pressure above a predetermined rate of change in pressure.As the manifold differential pressure decreases, during decele-_ g ~a ~
ration of the engine, the voltage applied to capacitor 72increases, and the transistor 74 is rendered more conductive, decreasing the effective resistance in the discharge path of capacitor 52 and shortening the time required for the capacitor 52 to discharge. This effectively decreases the injector pulse time during engine decelera~ion. If ~he deceleration is suddenly terminated and the engine is accelerated, the resultant change of voltage will cause the capacitor 72 to discharge through potentiometer 60 and thus terminate the pulse shortening effect immediateiy.
In another embodiment of the present invention, a separate mechanical device may be used in place of the manifold pressure sensor 36 and the differentiator 38 as illustrated in FIGURES 1 and 2. The device, generally indicated at 80, comprises a closed housing 82 having an elastic diaphragm 84 dividing it into a pair of compartments 86 and 88. The diaphragm 84 is biased in the direction of compartment 88 by a compression spring 90.
A conduit 92 connects the chamber 88 to the engine intake manifold 34. The chambers 86 and 88 are connected by a vent device 94 which by-passes the diaphragm 84 and has a restriction 96 which controls the rate of air flow ~etween the chambers 86 and 88.
The diaphragm 84 is connected to the movable contact of a potentiometer 98 connected between the positive terminal of the power supply and ground. The movable contact of the poten~
tiometer 98 is connected to the base of a transistor 100 which is the equivalent of transistor 74 in FIGURE 2, having its emitter-collector circuit shuntin~ the resistor 54 in the dis-charge path of the R-C circuit.
When the manifold pressure decreases, the pressure in chamber 88 is decreased and the diaphragm 84 is moved toward chamber 88, expanding the spring 90. This causes a movement of the movable contact of the potentiometer 98, and increases the voltage at the base of NPN transistor 100, increasing its con-ductivity, and decreasing the effective resistance of the discharge path of the R-C circuit. Thus, the duration oE a pulse generated by the circuit 36 is decreased. The effect is transient, however, because the decrease in pressure in chamber 86 causes air to bleed through the by~pass 94 and restriction 96, into the chamber 88, and thus restore the pressure balance on the diaphragm 84. An increase in manifold pressure, resulting from an acceleration of the vehicle, tends to increase the resis-tance of the emitter-collector path of transistor 100, restoring the normal discharge path of the R-C circuit and the normal dura-tion of the injector pulse.
Claims (12)
1. A fuel injection system comprising: means for sensing engine manifold pressure, means for sensing other engine operating parameters, and means for providing fuel to the engine as a function of the sensed engine operating parameters, wherein the improvement comprises:
means for sensing the rate of decrease of engine manifold pressure and means for modifying the fuel charge provided to the engine solely as a continuous function of the rate of decrease of engine manifold pressure while manifold pressure is decreasing above a predetermined rate.
means for sensing the rate of decrease of engine manifold pressure and means for modifying the fuel charge provided to the engine solely as a continuous function of the rate of decrease of engine manifold pressure while manifold pressure is decreasing above a predetermined rate.
2. A fuel injection system as recited in claim 1, wherein said modifying means varies the fuel charge as a direct function of the rate of change of decreasing engine manifold pressure.
3. A fuel injection system as recited in claim 1, wherein said means for providing fuel to the engine as a function of the sensed engine parameters comprises:
a source of pressurized fuel, electrically actuated injec-tion means, and means for generating an electric pulse operative to actuate said injector means, said electric pulse having a duration which is a function of the sensed engine operating parameters at intervals occurring in timed relation to the operation of the engine, and wherein said modifying means comprises means for decreasing the duration of said electric pulse as a function of the rate of change of decreasing engine manifold pressure.
a source of pressurized fuel, electrically actuated injec-tion means, and means for generating an electric pulse operative to actuate said injector means, said electric pulse having a duration which is a function of the sensed engine operating parameters at intervals occurring in timed relation to the operation of the engine, and wherein said modifying means comprises means for decreasing the duration of said electric pulse as a function of the rate of change of decreasing engine manifold pressure.
4. A fuel injection system as recited in claim 3, wherein said pulse generating means comprises a circuit having a resistance and a capacitance, and wherein said pulse decreasing means comprises means for modifying the resistance of the resistance-capacitance circuit as a continuous function of the rate of decrease of engine manifold pressure.
5. A fuel injection system as recited in claim 4, wherein said resistance modifying means comprises a variable resistance element shunting the resistance component of said circuit, and means for varying the resistance of said variable resistance element as a function of the rate of decrease of engine manifold pressure.
6. A fuel injection system as recited in claim 5,wherein said variable resistance element comprises a transistor.
7. A fuel injection system as recited in claim 5, wherein said means for varying the resistance of the variable resistance element comprises a capacitance connec-ted to said transistor for receiving an electrical signal proportional to the rate of change of decreasing engine manifold pressure.
8. A fuel injection system as recited in claim 5, wherein said means for sensing engine manifold pressure comprises a physically movable element which changes po-sition as a function of engine manifold pressure.
9. A fuel injection system as recited in claim 5, wherein said circuit further comprises means for charging said capacitance to a voltage as a function of engine manifold pressure.
10. A fuel injection system as recited in claim 8, wherein said means for sensing manifold pressure com-prises a potentiometer having its movable arm positioned as a function of engine manifold pressure.
11. A fuel injection system as recited in claim 3, wherein said pulse generating means comprises a resistance-capacitance circuit having connections for charging said capacitance to a voltage inversely proportional to engine manifold pressure and said pulse decreasing means comprises means for decreasing said resistance in said circuit as a function of the decrease in engine manifold pressure.
12. A fuel injection system as recited in claim 11, wherein said resistance decreasing means comprises a transistor having its emitter-collector path shunting said resistance of said circuit, and a capacitance connected to receive the manifold pressure signal and connected to the base of said transistor.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US68270276A | 1976-05-03 | 1976-05-03 | |
| US682,702 | 1976-05-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1110735A true CA1110735A (en) | 1981-10-13 |
Family
ID=24740780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA277,591A Expired CA1110735A (en) | 1976-05-03 | 1977-05-02 | Deceleration fuel control in fuel injection system |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS52133418A (en) |
| CA (1) | CA1110735A (en) |
| DE (1) | DE2719476A1 (en) |
| ES (1) | ES458672A1 (en) |
| FR (1) | FR2350465A2 (en) |
| GB (1) | GB1567044A (en) |
| SE (1) | SE7704660L (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5828568A (en) * | 1981-08-13 | 1983-02-19 | Toyota Motor Corp | Fuel supply control of internal combustion engine |
| JPS58133435A (en) * | 1982-02-02 | 1983-08-09 | Toyota Motor Corp | Electronically controlled fuel injection method of internal-combustion engine |
| JPS58158330A (en) * | 1982-03-15 | 1983-09-20 | Mitsubishi Electric Corp | Reducing method of fuel and controller therefor |
| JPS5934429A (en) * | 1982-08-23 | 1984-02-24 | Japan Electronic Control Syst Co Ltd | Electronically controlled fuel injection device of internal-combustion engine |
| JPH0623550B2 (en) * | 1983-02-16 | 1994-03-30 | トヨタ自動車株式会社 | Fuel injection control method for internal combustion engine |
| JPS6321336A (en) * | 1986-07-14 | 1988-01-28 | Fuji Heavy Ind Ltd | Electronically controlled fuel injection device |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3032025A (en) * | 1959-07-14 | 1962-05-01 | Bendix Corp | Fuel supply system |
| GB1107989A (en) * | 1963-09-09 | 1968-03-27 | Ass Eng Ltd | Fuel injection systems for internal combustion engines |
| US3673989A (en) * | 1969-10-22 | 1972-07-04 | Nissan Motor | Acceleration actuating device for fuel injection system |
| NL7112211A (en) * | 1971-09-04 | 1973-03-06 | ||
| US3794003A (en) * | 1972-01-13 | 1974-02-26 | Bendix Corp | Pressure dependent deceleration cutoff for an internal combustion engine fuel delivery system |
-
1977
- 1977-04-22 GB GB1695877A patent/GB1567044A/en not_active Expired
- 1977-04-22 SE SE7704660A patent/SE7704660L/en not_active Application Discontinuation
- 1977-05-02 CA CA277,591A patent/CA1110735A/en not_active Expired
- 1977-05-02 JP JP5112177A patent/JPS52133418A/en active Pending
- 1977-05-02 DE DE19772719476 patent/DE2719476A1/en not_active Ceased
- 1977-05-03 ES ES458672A patent/ES458672A1/en not_active Expired
- 1977-05-03 FR FR7713416A patent/FR2350465A2/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| ES458672A1 (en) | 1978-08-01 |
| SE7704660L (en) | 1977-11-04 |
| GB1567044A (en) | 1980-05-08 |
| JPS52133418A (en) | 1977-11-08 |
| FR2350465A2 (en) | 1977-12-02 |
| DE2719476A1 (en) | 1977-11-24 |
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