US3774580A

US3774580A - Linearized electronic fuel injection system

Info

Publication number: US3774580A
Application number: US00191183A
Authority: US
Inventors: J Mcgavic
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1971-10-21
Filing date: 1971-10-21
Publication date: 1973-11-27
Anticipated expiration: 1990-11-27
Also published as: JPS4850121A; GB1340307A; DE2251587A1; CA965506A

Abstract

In synchronization with the speed of an internal combustion engine, a control voltage having a substantially constant amplitude is applied across an inductor to develop through the inductor a control current having a linearly varying magnitude. The inductance of the inductor is determined as a linear function of at least one engine operating parameter thereby to define the constant rate of change in the magnitude of the control current. Fuel is applied to the engine in an amount directly related to the rate of change in the magnitude of the control current so that the total quantity of fuel delivered to the engine is linearly related to the engine operating parameter.

Description

United States Patent McGavic I Nov. 27, 1973 {22] Filed:

[ LINEARIZED ELECTRONIC FUEL INJECTION SYSTEM [75] Inventor: John P. McGavic, Lake Park, Fla.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

Oct. 2], 1971 [21] Appl. No.: 191,183

[52] US. Cl. 123/32 EA, 123/119 R [51] Int. C1. F02d'5/02, F0211] 51/00 [58] Field Of Search 123/32 AB, 32 EA, 123/1 19 R [56] References Cited UNITED STATES PATENTS 3,203,410 8/1965 SCl'lOll 123/32 EA 3,338,221 8/1967 SChOll 123/32 EA 3,448,728 6/1969 SChOll 123/32 EA 3,583,374 6/1971 SChOll 123/32 EA Primary ExaminerLaurence M. Goodridge Assistant ExaminerCort Flint Attorney-E. E. Christen et al.

[5 7 ABSTRACT In synchronization with the speed of an internal combustion engine, a control voltage having a substantially constant amplitude is applied across an inductor to develop through the inductor a control current having a linearly varying magnitude. The inductance of the inductor is determined as a linear function of at least one engine operating parameter thereby to define the constant rate of change in the magnitude of the control current. Fuel is applied to the engine in an amount directly related to the rate of change in the magnitude of the control current so that the total quantity of fuel delivered to the engine is linearly related to the engine operating parameter.

6 Claims, 2 Drawing Figures IGNITION I CIRCUIT PRESSURE SENSOR l l/J l ,-//6' a, I

INJECTOR CDISEIUEIT 9/ Patented Nov. 27, 1973 3.774580 2 Sheets-Sheet 1 PRESSURE SENSOR I id l ,//6' 87 l INJECTOR DRIVE ATTORNEY 2 Sheets-Sheet F:

INVENTOR.

ATTORNEY LINEARIZED ELECTRONIC FUEL INJECTION SYSTEM This invention relates to a linearized electronic fuel injection system for an internal combustion engine.

More particularly, the invention relates to an electronic fuel injection system in which the total quantity of fuel delivered to the engine is a linear function of at least one engine operating parameter.

According to one aspect of the invention, a control voltage having a substantially constant amplitude is applied in synchronization with the speed of the engine across an inductor having an inductance which is determined as a linear function of at least one engine operating parameter. As a result, a control current is developed through the inductor having a magnitude which linearly varies at a constant rate of change proportional to the engine operating parameter. Fuel is applied to the engine in an amount determined by the rate of change in the magnitude of the control current so that the total quantity of fuel delivered to the engine is linearly related to the engine operating parameter.

In another aspect of the invention, the control voltage is applied across the inductor by a transistor which is connected in an emitter-follower configuration between the inductor and at least one resistor. Consequently, the control current developed through the inductor is also drawn through the resistor to generate a control voltage across the resistor having a magnitude which linearly varies from a peak level to a reference level at a constant rate of change defined by the constant rate of change in the magnitude of the control current. The amount of fuel applied to the engine is determined in direct relation to the time period defined between the departure of the control voltage from the peak level and the arrival of the control voltage at the reference level so that fuel is metered to the engine at a linear function of the engine operating parameter.

These and other aspects and advantages of the invention may be best understood by reference to the following detail description of a preferred embodiment when considered in conjunction with the accompanying drawing.

In the drawing:

FIG. 1 is a schematic diagram of an electronic fuel injection system incorporating the principles of the invention.

FIG. 2 is a graphic diagram of several waveforms useful in explaining the operation of the electronic fuel injection system illustrated in FIG. 1.

Referring to FIG. 1, an internal combustion engine for an automotive vehicle includes a combustion chamber or cylinder 12. A piston 14 is mounted for reciprocation within the cylinder 12. A crankshaft 16 is supported for rotation within the engine 10. A connecting rod 18 is pivotally connected between the piston 14 and the crankshaft 16 for rotating the crankshaft within the engine 10 when the piston 14 is reciprocated within the cylinder 12.

An intake manifold 20 is connected with the cylinder 12 through an intake port 22. An exhaust manifold 24 i is connected with the cylinder 12 through an exhaust port 26. An intake valve 28 is slidably mounted within the top of the cylinder 12 in cooperation with the intake port 22 for regulating the entry of combustion ingredients into the cylinder l2.from the intake manifold 20. A spark plug 30 is mounted in the top of the cylinder 12 for igniting the combustion ingredients within the cylinder 12 when the spark plug 30 is-energized. An exhaust valve 32 is slidably mounted in the top of the cylinder 12 in cooperation with the exhaust port 26 for regulating the exit of combustion products from the cylinder 12 into the exhaust manifold 24. The intake valve 28 and the exhaust valve 32 are driven through a suitable linkage 34 which conventionally includes rocker arms, lifters and camshaft.

An electrical power source is provided by the vehicle batter 36. An ignition switch 38 connects the battery 36 between a power line 40 and a ground line 42. When the ignition switch 38 is closed, the battery 36 applies a supply voltage to the power line 40. A conventional ignition circuit 44 is electrically connected to the power line 40 and is mechanically connected with the crankshaft 16 of the engine 10. Further, the ignition circuit 44 is connected through a spark cable 46 to the spark plug 30. In a conventional manner, the ignition circuit 44 energizes the spark plug 30 in synchronization with the rotation of the crankshaft 16 of the engine 10. Hence, the ignition circuit 44 combines with the ignition switch 38 and the spark plug 30 to form an ignition system.

A fuel injector .48 includes a housing 50 having a fixed metering orifice 52. A plunger 54 is supported within the housing 50 for reciprocation between a fully opened position and a fully closed position. In the fully opened position, the forward end of the plunger 54 is opened away from the orifice 52. In the fully closed position, the forward end of the plunger 54 is closed against the orifice 52. A bias spring 56 is seated between the rearward end of the plunger 54 and the housing 50 for normally maintaining the plunger 54 in the fully closed position. A solenoid or winding 58 is electromagnetically coupled with plunger 54 for driving the plunger 54 to the fully opened position against the action of the bias spring 56 when the winding 58 is energized. The bias spring 56 drives the plunger 54 to the fully closed position when the winding 58 is deenergized. The fuel injector 48 is mounted on the intake manifold20 at a constant flow rate through the metering orifice 52 when the plunger 54 is in the fully opened position. Notwithstanding the illustrated structure, it is to be noted that the fuel injector 48 may be provided by virtually any suitable constant flow rate valve.

A fuel pump 60 is connected to the fuel injector 48 by a conduit 62 and to the vehicle fuel tank 64 by a conduit 66 for pumping fuel from the fuel tank 64 to the fuel injector 48. Preferably, the fuel pump 60 is connected to'the power line 40 to be electrically driven from the vehicle battery 36. Alternatively, the fuel pump 60 could be connected to the crankshaft 16 to be mechanically driven from the engine 10. A pressure regulator 68 is connected to the conduit 62 by a conduit 70 and is connected to the fuel tank 64 by a conduit 72 for defining the pressure of the fuel applied to the fuel injector 48. Thus, the fuel injector 48 combines with the fuel tank 64, the fuel pump 60 and the prestween the accelerator pedal 78 and the reference surface. As the accelerator pedal 78 is depressed, the throttle valve 74 is moved to a more opened position to increase the flow of air into the intake manifold 20. Conversely, as the accelerator pedal 78 is released, the throttle valve 74 is moved to a less opened position to decrease the flow of air into the intake manifold 20.

In operation, fuel and air are combined within the intake manifold 20 to form an air/fuel mixture. The fuel is injected into the intake manifold 20 at a constant flow rate by the fuel injector 48 in response to energization. The precise amount of fuel deposited within the intake manifold 20 is regulated by a fuel supply control system which will be described later. The air enters the intake manifold 20 from the air intake system (not shown) which conventionally includes an air filter. The precise amount of air admitted into the intake manifold 20 is determined by the position of the throttle valve 74. As previously described, the position of the accelerator pedal 78 controls the position of th throttle valve 74.

As the piston 14 initially moves downward within the cylinder 12 on the intake stroke, the intake valve 28 is opened away from the intake port 22 and the exhaust valve 32 is closed against the exhaust port 26. Accordingly, combustion ingredients in the form of the air/fuel mixture within the intake manifold 20 are drawn by negative pressure through the intake port 22 into the cylinder 12. As the piston 14 subsequently moves upward within the cylinder 12 on the compression stroke, the intake valve 28 is closed against the intake port 22 so that the air/fuel mixture is compressed between the top of the piston 14 and the top of the cylinder 12. When the piston 14 reaches the end of its upward travel on the compression stroke, the spark plug 30 is energized by the ignition circuit 44 to ignite the air/fuel mixture. The ignition of the air/fuel mixture starts a combustion reaction which drives the piston 14 downward within the cylinder 12 on the power stroke. As the piston 14 moves upward within the cylinder 12 on the exhaust stroke, the exhaust valve 32 is opened away from the exhaust port 26. As a result, the combustion products in the form of various exhaust gases are pushed by positive pressure out of the cylinder 12 through the exhaust port 26 into the exhaust manifold 24. The exhaust gases pass out of the exhaust manifold 24 into the exhaust system (not shown) which conventionally includes a muffler and an exhaust pipe.

Although the structure and operation of only a single combustion chamber or cylinder 12 has been described, it will be readily appreciated that the illustrated internal combustion engine may include additional cylinders 12 as desired. Similarly, additional fuel injectors 48 may be provided as required. However, as long as the fuel injectors 48 are mounted on the intake manifold 20, the number of additional fuel injectors 48 need not necessarily bear any fixed relation to the number of additional cylinders 12. Alternately, the fuel injector 48 may be directly mounted on the cylinder 12 so as to inject fuel directly into the cylinder 12. In such instance, the number of additional fuel injectors 48 would necessarily equal the number of additional cylinders 12. At this point, it is to be understood that the illustrated internal combustion engine 10, together with all of its associated equipment, is shown only to facilitate a more complete understanding of the inventive electronic control system.

A timing pulse generator is connected with the crankshaft 16 for developing rectangular timing pulses having a frequency which is proportional to and synchronized with the rotating speed of the crankshaft 16. The rectangular timing pulses are applied to a timing line 82. Preferably, the timing pulse generator 80 is some type of inductive speed transducer coupled with a switching circuit. However, the timing pulse generator 80 may be provided by virtually any suitable pulse producing device such as a multiple contact rotary switch.

An injector drive circuit 84 is connected to the power line 40 and to the timing line 82. Further, the injector drive circuit 84 is connected through an injection line 86 to the fuel injector 48. The injector drive circuit 84 is responsive to the timing pulses produced by the timing pulse generator 80 to energize the fuel injector valve 48 in synchronization with the rotating speed or frequency of the crankshaft 16 in much the same manner as the ignition circuit 44 energizes the spark plug 30. The time period for which the fuel injector 48 is energized by the drive circuit 84 is determined by the length or duration of rectangular control pulses pro duced by a modulator or control pulse generator 88 which will be more fully described later. The control pulses are applied by the control pulse generator 88 to the injector drive circuit 84 over a control line 90 in synchronization with the timing pulses produced by the timing pulse generator 80. In other words, the injector drive circuit 84 is responsive to the coincidence of a timing pulse and a control pulse to energize the fuel injector 48 for the length or duration of the control pulse.

The injector drive circuit 84 may be virtually any amplifier circuit capable of logically executing the desired coincident pulse operation. However, where additional fuel injectors 48 are provided, it may be necessary that the injector drive circuit 84 also select which one or ones of the fuel injectors 48 are to be energized in response to each respective timing pulse. As an example, the fuel injectors 48 may be divided into separate groups which are successively energized in response to successive ones of the timing pulses. Conversely, the timing pulses may be applied to operate a counter circuit of a logic circuit which individuallyselects the fuel injectors 48 for energization.

The control pulse generator. 88 comprises a control circuit 92 and a switching circuit 94. The control circuit 92 includes a voltage regulator provided by an N PN junction transistor 96. The collector electrode of the transistor 96 is connected directly to a junction 98. A pair of biasing

resistors

100 and 102 are connected in series beween the power line 40 and the junction 98. A clamping switch is provided by an NPN junction transistor 104. The collector electrode of the transistor 104 is connected directly to the junction 98. The emitter electrode of the transistor 104 is connected directly to the ground line 42. A biasing resistor 106 is connected between the base electrode of the transistor 104 and a junction 108.

A control transducer 110 includes an inductor or winding 112 connected between the emitter electrode of the transistor 96 and the ground line 42. Further, the control transducer 110 includes a movable magnetizable core 114 which is inductively coupled with the winding 1 12. The deeper the core 1 14 is inserted within the winding 112, the greater the inductance L of the winding 112. The movable core 114 is mechanically connected through a suitable linkage 116 with a pressure sensor 118. The pressure sensor 118 communicates with the intake manifold 20 of the engine downstream from the throttle valve 74 through a suitable conduit 120 for monitoring the negative pressure or vacuum within the intake manifold 20. The pressure sensor 118 moves the core 114 within the winding 112 to regulate the inductance of the winding 112 in direct proportion to the pressure within the intake manifold 20. Therefore, as the pressure within the manifold increases in response to opening of the throttle valve 74, the core 114 is inserted deeper within the winding 112 to proportionately increase the inductance of the winding 1 12.

A biasing circuit 122 is connected with the base electrode of the transistor 96. The biasing circuit 122 includes

NPN junction transistors

124, 126 and 128 and a PNP junction transistor 130. A biasing resistor 131 is connected between the base electrode of the transistor 124 and a junction 132. The emitter electrode of the transistor 124 is connected directly to ground line 42. The collector electrode of the transistor 124 is connected together with the base electrode of the transistor 126 at a junction 134. A biasing resistor 136 is connected between the power line 40 and the junction 134. A pair of biasing

resistors

138 and 140 are connected in series between the power line 40 and the collector electrode .of the transistor 126.

The base electrode of the transistor 128 is connected directly to the emitter electrode of the transistor 126. The emitter electrode of the transistor 128 is connected directly to the ground line 42. A biasing resistor 142 is connected in series with a control diode 144 between a junction 146 and the collector electrode of the transistor 128. A biasing resistor 148 is connected in series with a control diode 150 between the junction 146 and the collector electrode of the transistor 130. A biasing resistor 152 is connected between the base electrode of the transistor 130 and a junction 154 located between the biasing

resistors

138 and 140. The

emitter electrode of the transistor 130 is connected di- 7 rectly to the power line 40. The base electrode of the transistor 96 is connected directly to the junction 146.

The switching circuit 94 includes a differential switch 156 including

NPN junction transistors

158, 160 and 162. The emitter electrode of the transistor 158 is connected directly to the ground line 42. The base electrode of the transistor 158 is connected to a junction 164. A current reference diode 166 is connected be- I tween the junction 164 and the ground line 42. A biasing resistor 168 is connected between the junction 164 and the power line 40. The collector electrode of the transistor 158 is connected to a junction 170 between the emitter electrodes of the transistors 160 and 162. The base electrode of the transistor 162 is connected directly to a junction 17. A biasing resistor 174 is connected between the junction 172 and the power line 40. Similarly, a biasing resistor 176 is connected between the junction 172 and the ground line 42. The base electrode of the transistor 160 is connected directly to a junction 178 located between the biasing

resistors

100 and 102. The collector electrode of the transistor 162 is connected directly to a junction 180. A biasing resistor 182 is connected between the junction 180 and the power line 40. The collector electrode of the transistor 162 is connected directly to the power line 40.

A buffer switch 184 is provided by a PNP junction transistor 186 and an NPN junction transistor 188. A n output switch is provided by an NPN junction transistor 190. The base electrode of the transistor 186 is connected directly to the junction 180. The emitter electrode of the transistor 186 is connected together with the collector electrode of the transistor 188 directly to the power line 40. The collector electrode of the transistor 186 is connected directly to the base electrode of the transistor 188. A biasing resistor 192 is connected between the emitter electrode of the transistor 188 and a junction 194. A biasing resistor 196 is connected between the junction 194 and the ground line 42. A biasing resistor 198 is connected between the base electrode of the transistor 190 and the junction 194. A biasing resistor 200 is connected between the collector electrode of the transistor 190 and the power line 40. The emitter electrode of the transistor 190 is connected directly to the ground line 42.

A trigger pulse former 202 is connected between the timing line 82 and the

junctions

132, 108 and 194 of the control pulse generator 88 for developing negative trigger pulses or voltage spikes in response to the rectangular timing pulses produced by the timing pulse generator 80. More specifically, the trigger pulse former 202 provides a trigger pulse in coincidence with the initiation of each of the timing pulses on the timing line 82. Thus, the trigger pulses have the same frequency as the timing pulses. The trigger pulse former 202 may be provided by a simple RC differentiator or any other suitable pulse forming circuit. Together, the trigger pulse former 202 and the timing pulse generator comprise a timing apparatus for producing trigger pulses having a frequency proportional to the output speed of the engine 10.

Referring to FIGS. 1 and 2, the control circuit 92 produces a control voltage K at the junction 178. The amplitude of the control voltage K varies in a manner which will be more fully described later. In the switching circuit 94, the resistors 174 and 176 form a voltage divider network for providing a reference voltage R at the junction 172. The amplitude of the reference voltage R is substantially constant at a reference level V, determined by the ratio of the resistances of the resistors 174 and 176. In the conventional manner, the differential switch 156 is operable between first and second states. More particularly, the differential switch 156 shifts the the first state when the amplitude of the reference voltage R exceeds the amplitude of the control voltage K. Conversely, the differential switch 156 shifts to the second state when the amplitude of the control voltage K-exceeds the amplitude of the reference voltage R. The transistor 158 combines with the diode 166 and the resistor 168 to provide a constant current sink for the differential switch 156 at the junction 170. 7

Initially, it is assumed that the amplitude of the reference voltage R exceeds the amplitude of the control voltage K so that the differential switch shifts to the first state. In the first state, the transistor 162 is rendered fully conductive and the transistor is rendered fully nonconductive. With the transistor 162 turned on, the

transistors

186 and 188 in the buffer switch 184 are rendered fully conductive through the biasing action of the resistor 182 and the transistors 158 and 162. With the

buffer transistors

186 and 188 turned on, the clamping transistor 104 is rendered fully conductive through the biasing action of the

resistors

192, 196 and 106. With the transistor 104 turned on, the junction 98 is effectively connected to the ground line 42 through the transistor 104. As a result, the amplitude of the control voltage K at the junction 178 is effectively clamped at an initial level or a lower level V primarily defined by the voltage divider action of the

resistors

100 and 102. The lower level V of the control voltage K is below the reference level V of the reference voltage R so that the differential switch 156 remains in the first state.

Further, with the

buffer transistors

186 and 188 turned on, the biasing transistor 124 is rendered fully conductivethrough the biasing action of the

resistors

192, 196 and 130. With the transistor 124 turned on, the

transistors

126, 128 and 130 in the biasing circuit 122 are rendered fully nonconductive. Moreover, with the

buffer transistors

186 and 188 turned on, the output transistor 190 is rendered fully conductive through the biasing action of the

resistors

192, 196 and 198. With the transistor 190 turned on, the control line 90 is effectively connected to the ground line 42 through the transistor 190. Thus, no control pulse C is developed on the timing line 90.

As previously described, the trigger pulse former 202 applies negative trigger pulses P to the

junctions

132, 108 and 194 at a frequency defined in direct relation to the speed of the engine 10. When a trigger pulse P arrives at the junction 194, it instantaneously renders the transistor 190 fully nonconductive. With the output transistor 190 turned off, the control line 90 is effectively disconnected from the ground line 42. Accordingly, a control pulse C is initiated on the control line 90. The voltage level of the control pulse C is primarily determined by the supply potential on the power line 40.

Further when a trigger pulse P arrives at the junction 108, it instantaneously renders the transistor. 104 fully nonconductive. With the clamping transistor 104 turned off, the junction 98 is effectively disconnected from the ground line 42. Consequently, the amplitude of the control voltage K at the junction 178 jumps from the lower level V, to a peak level or an upper level V,, primarily defined by the supply potential on the power line 40. The upper level V, of the control voltage K is above the reference level V, of the reference voltage R so that the differential switch 156 shifts to the second state. In the second state, the transistor 160 is rendered fully conductive and the transistor 162 is rendered fully nonconductive. With the transistor 162 turned off, the

transistors

186 and 188 in the buffer, switch 184 are rendered fully nonconductive through the biasing action of the resistor 182. With the

buffer transistors

186 and 188 turned off, the output transistor 190 is maintained turned off.

The transistor 124 is initially turned off in response to the occurrence of a trigger pulse P at the junction 132 and is subsequently maintained turned off while the

buffer transistors

186 and 188 are turned off. With the transistor 124 turned off, the transistor 126 is rendered fully conductive through the biasing action of the resistor 136. With the transistor 126 turned on, the transistor 128 is rendered fully conductive through the biasing action of the

resistors

138 and 140, and the transistor 130 is rendered fully conductive through the biasing action of the

resistors

138, 140 and 152. With the

transistors

128 and 130 turned on, the

resistors

142 and 148 form a voltage divider network for developing an energizing voltage E at the junction 146. The amplitude of the energizing voltage E is substantially constant at an energizing level V,. which is primarily defined by the ratio of the resistances of the

resistors

142 and 148.

The control transistor 96 operates as an emitterfollower to apply the energizing voltage E across the winding 112 of the control transducer 110. lnresponse to the application of the energizing voltage E across the winding 112, a control current J is developed through the winding 112. The magnitude of the control current J linearly increases from a base level or a lower level L, to a reference level or an upper level 1,, at a constant rate of change directly proportional to the amplitude V of the energizing voltage E and inversely proportional to the inductance L of the winding 112. As the magnitude of the control current J increases, the effective resistance between the collector electrode and the emitter electrode of the transistor 96 decreases to maintain the energizing voltage E substantially constant at the energizing level V across the winding 112. Of course, the energizing level V of the energizing voltage E is slightly reduced by the voltage drop across the base-emitter junction of the transistor 96. Since the inductance L of the winding 112 is directly proportional to the pressure within the intake manifold 20, the rate of change in the magnitude of the control current J is inversely proportional to the intake pressure of the engine 10. That is, as the intake pressure of the engine 10 increases, the rate of change in the magnitude of the control current J decreases.

The control current J which is developed through the winding 112 is also drawn through the

resistors

100 and 102. Accordingly, the control voltage K at the junction 178 linearly decreases from the upper level V at a constant rate of change defined by the constant rate of change in the magnitude of the control current J. Thus, the rate of change in the amplitude of the control voltage K is also inversely proportional to the pressure within thetintake manifold 20 in the engine 10. When the amplitude of the control voltage K reaches the reference level V, of the reference voltageR, the differential switch 156 shifts to the first state to terminate the control pulse C on the control line as previously described.

It will now be appreciated that the duration of the control pulses C is equal to the time period defined between the departure of the control voltage K from the upper level V, and the arrival of the control voltage K at the reference level V,. Since this time period is inversely proportional to the rate of change in the amplitude of the control voltage K, the duration of the control pulses C is a direct linear function of the pressure within the intake manifold 20. Hence, as the intake pressure of the engine 10 increases the duration of the control pulses C increases in a linearly proportional manner. Since the fuel injector 46 is energized for the duration of the control pulses C, the total quantity of fuel applied to the engine 10 is linearly related to the pressure within the intake manifold 20.

When the differential switch 156 shifts to the first state to terminate the control pulse C, the

transistors

104 and 124 are turned on so that the transistor 96 is rendered fully nonconductive. As the transistor 96 turns off, the winding 1 12 of the control transducer 1 10 is effectively open circuited. Consequently, a flyback voltage is developed across the winding 112. The polarity of the flyback voltage is opposite to-the polarity of the energizing voltage E so that the flyback voltage tends to maintain the flow of current through the winding 112. However, once the transistor 96 is turned off, the flyback voltage is unable to draw any additional current through the winding 1 12. The diode 150 blocks the flow of current from the transistor 130 through the resistor 148 and the base-emitter diode of the transistor 96. The flow of current from the transistor 128 through the diode 144, the resistor I42 and the base-emitter diode of the transistor 96 is blocked by the basecollector diode of the transistor [28. Similarly, the base-collector diode of the transistor 96 blocks the flow of current through the transistor 96. Under these conditions, the flyback voltage has a minimum duration which is primarily defined by eddy currents induced within the magnetizable core 114.

It will now be appreciated that the present invention provides a simple but effective technique for regulating the amount of fuel applied to an internal combustion engine as a linear function of at least one engine operating parameter. However, it will be understood that the illustrated embodiment of the invention is shown for demostration purposes only. Accordingly, various alterations and modifications may be made to the preferred embodiment without departing from the spirit and scope of the invention. Thus, in addition manifold pressure, the duration of the control pulses C may be determined as a function of other engine operating parameters such as air temperature, output speed, battery voltage, etc. This may be accomplished by selectively shifting the level of the energizing voltage E at the junction 146, the reference voltage R at the junction 172 or the control voltage K at the junction 178 What is claimed is:

1. In an internal combustion engine, the combination comprising: means including an inductor having an inductance determined as a linear function of an engine operating parameter; means for applying in synchronization with the operation of the engine a control voltage having a substantially constant amplitude across the inductor to develop through the inductor a control current having a linearly varying magnitude so that the constant rate of change in the magnitude of the control current is proportional to the inductance of the inductor; and means for applying fuel to the engine in an amount determined by the rate of change in the magnitude of the control current; whereby the total quantity of fuel delivered to the engine is a linear function of the engine operating parameter.

2. In an internal combustion engine, the combination comprising: means including an inductor having an inductance determined as a linear function of an engine operating parameter; means for applying across the inductor in synchronization with the speed of the engine a control voltage having a substantially constant amplitude to develop through the inductor a control current having a linearly varying magnitude which increases from a base level to a reference level at a constant rate inversely proportional to the inductance of the inductor; and means for applying fuel to the engine in an amount directly related to the time period defined between the departure of the control current from the base level and the arrival of the control current at the reference level; whereby the total quantity of fuel delivered to the engine is a linear function of the engine operating parameter.

3. In an internal combustion engine, the combination comprising: means including an inductor having an inductance determined as a linear function of at least one engine operating parameter; means including a transistor connected with the inductor in an emitter-follower configuration for applying across the inductor in synchronization with the operation of the engine a control voltage having a substantially constant amplitude to develop through the inductor a control current having a linearly varying magnitude which increases from a base level to a reference level at a constant rate determined as an inverse function of the inductance of the inductor; and means for applying fuel to the engine in an amount determined in direct relation to the time period defined between when the control current departs from the base level and when the control current arrives at the reference level; whereby the total quantity of fuel delivered to the engine is linearly related to the engine operating parameter.

4. In an internal combustion engine, the combination comprising: means including an inductor having an inductance determined as a linear function of at least one engine operating parameter; means including at least one resistor having a fixed resistance; means including a junction transistor connected in an emitter-follower configuration between the inductor and the resistor to apply across the inductor in synchronization with the operation of the engine a control voltage having a substantiallyconstant amplitude to generate through the inductor and through the resistor a control current having a linearly varying magnitude to develop across the resistor a control voltage having a linearly varying amplitude which decreases from a peak level to a reference level at a rate inversely proportional to the inductance of the inductor; and means for applying fuel to the engine in an amount defined by the time period extending between the departure of the control voltage from the peak level and the arrival of the control voltage at the reference level; whereby the total quantity of fuel delivered to the engine is linearly related to the engine operating parameter.

5. In an internal combustion engine, the combination comprising: means including a junction transistor having base, emitter and collector electrodes; means connected to the emitter electrode of the transistor and including an inductor having an inductance determined as a'linear function of at least one engine operating parameter; means connected with the collector electrode of the transistor and including at least one resistor having' a resistance which is substantially constant; means connected to the base electrode of the transistor for periodically operating the transistor as an emitterfollower in synchronization with the operation of the engine to apply across the inductor a control voltage having an amplitude which is substantially constant to generate through the inductor and through the resistor a control current having a magnitude which linearly increases to develop across the resistor a control voltage having an amplitude which linearly decreases from a peak level to a reference level at a constant rate inversely proportional to the inductance of the inductor; and means for applying fuel to the engine in an amount directly related to the time period extending between the departure of the control voltage from the peak level and the arrival of the control voltage at the reference level; whereby the total quantity of fuel delivered to the engine is a linear function of the engine operating parameter.

6. In an internal combustion engine, the combination comprising: means including a timing generator connected with the engine for producing trigger pulses occurring at a frequency proportional to the speed of the engine; means including a junction transistor having base, emitter and collector electrodes; means connected to the emitter electrode of the transistor and including an inductor having an inductance determined as a linear function of at least one engine operating parameter; means connected to the collector electrode of the transistor and including at least one resistor having a resistance which is substantially constant; means connected to the base electrode of the transistor and to the timing generator for periodically rendering the transistor conductive in an emitter-follower configuration in response to the occurrence of each trigger pulse to apply across the inductor a control voltage having an amplitude which is substantially constant to develop through the inductor and through the resistor a control current having a magnitude which linearly increases to generate across the resistor a control voltage having an amplitude which linearly decreases from a peak level to a reference level at a constant rate determined in proportion to the inductance of the inductor; means including a differential switch for shifting from a first state to a second state when the control voltage reaches the reference level; means connected to the timing generator and to the differential switch for producing a control pulse which is initiated in response to the occurrence of each trigger pulse and which is terminated when the differential switch shifts to the second state; and means for applying fuel to the engine at a constant rate for the duration of the control pulse; whereby the total quantity of fuel delivered to the engine is a linear function of the engine operating parameter.

UNITED STATES PATENT O FFICE 7 CERTIFICATE OF CORRECTION Patent No. 3,774,580 Dated November 27, 1973 Inventor Lil-.1511 P McGavic It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Column'B, line 20 "th" should read the Column 5, line 57 "17 should read 172. Column 6, line 49 "the the" should read tothe si ed and sealed this 30th day of July 197 (SEAL) Attest:

MCCOY M. GIBSON, JR; H c. MARSHALL DANN Attesting Officer Commissioner of Patents

Claims

4. In an internal combustion engine, the combination comprising: means including an inductor having an inductance determined as a linear function of at least one engine operating parameter; means including at least one resistor having a fixed resistance; means including a junction transistor connected in an emitter-follower configuration between the inductor and the resistor to apply across the inductor in synchronization with the operation of the engine a control voltage having a substantially constant amplitude to generate through the inductor and through the resistor a control current having a linearly varying magnitude to develop across the resistor a control voltage having a linearly varying amplitude which decreases from a peak level to a reference level at a rate inversely proportional to the inductance of the inductor; and means for applying fuel to the engine in an amount defined by the time period extending between the departure of the control voltage from the peak level and the arrival of the control voltage at the reference level; whereby the total quantity of fuel delivered to the engine is linearly related to the engine operating parameter.

5. In an internal combustion engine, the combination comprising: means including a junction transistor having base, emitter and collector electrodes; means connected to the emitter electrode of the transistor and including an inductor having an inductance determined as a linear function of at least one engine operating parameter; means connected with the collector electrode of the transistor and including at least one resistor having a resistance which is substantially constant; means conNected to the base electrode of the transistor for periodically operating the transistor as an emitter-follower in synchronization with the operation of the engine to apply across the inductor a control voltage having an amplitude which is substantially constant to generate through the inductor and through the resistor a control current having a magnitude which linearly increases to develop across the resistor a control voltage having an amplitude which linearly decreases from a peak level to a reference level at a constant rate inversely proportional to the inductance of the inductor; and means for applying fuel to the engine in an amount directly related to the time period extending between the departure of the control voltage from the peak level and the arrival of the control voltage at the reference level; whereby the total quantity of fuel delivered to the engine is a linear function of the engine operating parameter.