US2954020A

US2954020A - Fuel injection system

Info

Publication number: US2954020A
Application number: US752002A
Authority: US
Inventors: Thomas M Ball
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1958-07-30
Filing date: 1958-07-30
Publication date: 1960-09-27
Anticipated expiration: 1977-09-27

Description

Sept. 27,- 1960 T. M. BALL 2,954,020

FUEL INJECTION SYSTEM Filed July so, 1958 INVENTOR. 7/?077744 M547] United States Patent 2,954,020 FUEL INJECTION. SYSTEM Filed July 30, 1958, Ser. No. 752,002

18 Claims. (Cl. 123-119 This invention relates to fuel systems for internal combustion engines and in particular to an idle boost control device to be used in conjunction with a speed metering unit of a fuel injection system for providing additional fuel to the engine at speeds below the normal idle speed to prevent engine stalling.

The particular fuel injection system shown herein is disclosed in part in the copending application Serial No. 751,999, filed July 30, 1958, of Thomas M. Ball et al., and assigned to applicants assignee.

In fuel systems of the type generally used on internal combustion engines the problem of providing some means to prevent engine stalling during idling is encountered. Whether the system be based on carburetion or fuel injection, a sudden and unexpected decrease at idle in'engine speed and intake manifold vacuum will usually result in a leaning out of the fuel-air mixture and cause the engine to stall. This sudden drop in engine speed and vacuum is a usual occurrence in modern automotive vehicles resulting from a reverse surge of the fluid transmissions caused by sudden stopping of the vehicle which places a reverse load on the engine tending to decrease its speed. Such a drop may also occur due to a momental-y misfire o-r malfunctioning of the ignition system.

Heretofore various means, such as secondary fuel jets,

have been employed to furnish an additional fuel boost to the engine to offset the aforementioned manifold pressure and engine speed decrease. been entirely satisfactory since their operation and efiiciency depends directly on intake manifold vacuum which normally functions to suck an additional quantity of fuel into the intake manifold and, as mentioned above, the intake manifold vacuum may experience a sudden and unexpected drop of sufficient extent to negate the utility of these jets.

The present invention utilizes a fluid flow control or fuel boost control means to maintain a sufiicient fuel flow to the engine to prevent it from stalling when the engine speed and vacuum decrease below their normal idle level. This is accomplished by connecting an idle boost chamber of a fuel injection speed metering unit to the intake manifold of the engine by afluid conduit and placing a manifold pressure responsive fluid flow control means in the conduit to limit the amount of manifold vacuum transmittable to said idle boost chamber and thereby provide an excess pressure differential between said manifold and said chamber to establish a vacuum buffer against sudden loss of manifold vacuum.

An object of this invention is to provide an improved fuel boost means for use on liquid fuel systems of internal combustion engines to prevent leaning out of said engines at idle.

7 Another object is to provide a return flow fuel injection system of an internal combustion engine with a fuel boost means to control the return flow of fuel at idle and prevent said engine from stalling at idle due to a sudden partial loss of manifold vacuum;

These jets have not a A further object is to provide a speed fuel metering v unit of a fuel injection system of an internal combustion engine with a means to supplement the fuel flow when engine speed and vacuum drop below their normal idle levels. 4

Further objects and advantages will become apparent from the following specification and drawings, in which:

The figure represents a view partly in cross section of the complete fuel injectionsystem. i

In the drawing is shown a fuel injection meteringsysterm for an internal combustion engine 10 having heads 12 each provided with exhaust manifold banks 14. The metering system comprises a fuel speed metering unit 16, a fuel load metering unit 18, and a fuel supply 21. The fuel speed metering unit 16 is provided with four housing portions 22, 24, 26, and 28 separated from each other by di-aphragms 30, 32, and 34 respectively to pmvide chambers 36, 38, 40, and 42. Chamber 36 communicates with fuel supply 21 through conduit 44. A fuel pump 46 in said conduit supplies a substantially constant volume of fuel through filter 48 to chamber 36 during the operation of the engine regardless of the engine load or speed. A return flow metering orifice 50 in housing portion 22- connects chamber 36 with a return flow conduit 52. A return flow metering needle 56 having a tapered point 58 is secured to each of the diaphragms 30, 32, and 34 by suitable grommets 60.

A flyweig-ht support 62 pivotally supports flyweights 64 and 66 and is secured to a flexible shaft 68 which is operatively connected to the engine 10 to rotate at'a speed directly proportional to engine speed. Flyweights 64 and 66 have projections 70 and 72 respectively thereon which abut the end of needle 56 as said flyweights pivot outwardly in response to rotation of shaft 68 to'urge needle 56 toward orifice 50 against the force applied in the opposite direction against diaphragm 30 by the fuel in chamber 36.

A conduit 74 connects chamber 36 to the upstream chamber 76 of the load sensor 18 which upstream chamber communicates with a downstream fuel distribution chamber 78 of the load sensor across a load metering orifice 8 0. A tapered load metering needle 82 having a tapered end 84 positioned in orifice is operatively con"- nected to piston 86 reciprocably mounted in cylinder 88, a

which cylinder 'operatively communicates with the low pressure portions of each intake manifold 90 on said en gine through conduit 92. 7 Low pressure transmitted through conduit 92 will cause piston 86' to be drawn upwardly against the force of spring 94 to thereby urge the tapered end of needle 82 into closer proximity to' the sides of orifice 80 and conversely high pressure in the intake manifolds will tend to urge needle 82 to a more open position with respect to orifice 80. A plurality of nozzle feed conduits 96 extend from chamber 78 of the load sensor to an equal number of fuel injection'nozzles 98 located upstream of the throttle valves 100 of the individual intake manifold sections 90. The atomizing air supply to the nozzles 98 is obtained from pump 102 through intakes 104 and 106 and is transmitted toth'c branch air conduits 108 of said nozzles 'by'a main' air conduit 110. p Chamber 78 of the load sensor is connected to chamber 38 of the speed sensor by conduit 112 to provide an adjustment of the return flow metering needle 56 with respect to orifice 50 based on the pressure differential existing across orifice 80 of the load sensor.

In addition to chamber -40, as' explained below, manifold pressure responsive means for adjusting the idle fuel flow includes an idle boost or fluid conduit. 114. The latter communicates with one of said manifold sections 90 at a pointadjacent the edge of the throttle valve 100 of that section and with the chamber 40 .of the speed sensor. Forming a part ofconduit 114 is .3 chamber 116 formed by a section 118 of a fluid flow control means or fuel boost control means designated generally as 120. A manifold pressure orifice 122 and an idle boost orifice 124 in section 118 form part of conduit 114. A flexible diaphragm 126 secured in airtight relationship to section 113 and section 128 by suitable bolt means 130 is secured to and movably carries a fluid metering member 132 which regulates the flow of fluid through orifice 122 according to the pressure differential across diaphragm 126. Since section 128 of the fuel boost control means and section 28 of the speed metering unit are both vented to atmosphere through bleed apertures 134 and 136 respectively the pressures in chambers 116 and 40 are always equal. Adjustment means comprising springs 138 and 140 and screw 142 may be provided in the fuel boost control means 120 to adjust the .same to allow a maximum vacuum to be transmitted to idle boost chamber 40. A fluid bleed 144 of any desired size may be provided in conduit 114, as shown, or in chamber '40 to maintain a continuous fluid flow through orifice 122 rather than allow a static pressure condition to exist in chambers 116 and 40 when the manifold vaccum becomes greater than the aforementioned maximum. This bleed also allows the idle fuel boost pressure on member 56 to be relieved when the engine is stopped.

The operation of the fuel injection metering unit will be described in relation to a change in static engine operating conditions, that is, constant engine speed and load. Under said static operating conditions, the combined forces exerted by flyweights 64 and 66 and the fuel in chamber 38 is balanced by the force exerted by the fuel in chamber 36 and the return flow metering member 56 is maintained stationary at a distance away from orifice 50. In this static condition, the amount of fuel delivered to the distributing chamber '78 is constant and is equal to the constant amount of fuel being delivered to the system by the pump less the constant amount of fuel being returned to the fuel tank through the return flow conduit 52. If this static condition represents the engine during normal driving speed, the pressure in chamber 42 has no noticeable effect on the operation of the unit and may be disregarded. It is only during idling and very low engine speeds that the pressure diflerential across diaphragm 34 becomes signficant.

As the throttle valves 100 are moved to a more open position by the depression of the engine accelerator, an increase in manifold pressure is transmitted to the load sensor piston through conduit 92 and moves said piston down to thereby move the load metering needle 82 to a more open position with respect to the load metering orifice 80. The pressure differential existing across said orifice is consequently decreased as more fuel is allowed to flow into chamber 78. This decrease in pressure differential causes the flow through orifice 80 to deviate from the desirable flow which is substantially directly proportional to engine speed. To correct this condition and bring the pressure differential across said orifice up to a value where the flow of fuel therethrough is substantially directly proportional to engine speed, the fuel pressure in fuel supply pressure chamber 36 and load sensor upstream chamber 76 communicating therewith is increased. This increase in pressure is accomplished by moving the return flow metering member 56 closer to orifice 50 by the increased force transmitted by the flyweights 64 and 66 as the engine speed is increased and by the increased pressure in chamber 38 caused by the increased flow of fuel into the downstream chamber 78 of the load sensor. When the forces transmitted by said flyweights and the fuel in said chamber 38 once again balance the force transmitted in the opposite direction by the fuel in chamber 36, the flow of fuel through orifice 80 will be substantially directly proportional to the speed of the engine and will correspond to the flow of air into the intake manifold.

In the operation of fuel boost means 120 during engine idle, engine manifold vacuum from is transmitted to chamber 116 and establishes a pressure differential across diaphragm 126 which diaphragm is preset in position by the aforementioned adjustment means to cause member 132 to cut off or retard the flow of fluid from chamber 40 to manifold 99 at a preselected vacuum in chamber 40. As the vacuum in manifold 90 increases beyond said preselected value to some maximum value, member 132 maintains the boost vacuum in chamber 40 constant at said preselected value which establishes through the force of diaphragm 34 on return flow metering member 56 a constant fuel pressure in chamber 36 and a resultant constant fuel flow to the engine. As the vacuum in manifold 90 decreases due to an unde sired and sudden decrease in engine speed, member 132 will not allow a fluid flow from said: manifold into chamber 40 through the interval of manifold vacuum decrease from said maximum manifold vacuum value to said preselected vacuum value. Thus the aforementioned constant fuel flow may check the engine speed decrease at idle during this interval before the vacuum in manifold 90 decreases to a value which, when allowed to be transmitted to chamber 40 through orifice 122, is ineffective to cause sufficient fuel flow to maintain the engine in operation. Fuel boost means provides, in other words, a buffer against sudden and unexpected manifold pressure increases during idling of the engine which pressure increases would normally cause an opening of return flow orifice 50 and result in a leaning out of the engine.

I claim:

1. In an adjustable fuel flow control system for an internal combustion engine having an intake manifold, pressure responsive means operatively connected with said system and manifold to adjust the fuel fiow to said engine as a function of the manifold pressure imparted to said pressure responsive means, and fiow control means responsive to an operating parameter of said engine and operatively connected with said pressure responsive means to maintain the manifold pressure imparted thereto at a substantially constant value appreciably above the minimum manifold pressure developed during certain engine operating conditions.

2. In an adjustable fuel flow control system for an internal combustion engine having an intake manifold, pressure responsive means operatively connected with said system and manifold to adjust the fuel flow to said engine at idle as a function of the manifold pressure imparted to said pressure responsive means, and flow control means responsive to the pressure of said manifold and operatively connected with said pressure responsive means to maintain the manifold pressure imparted thereto at a substantially constant value intermediate the maximum and minimum manifold pressures during engine operation at idle.

3. In an adjustable fuel flow control system for an internal combustion engine having an intake manifold, pressure responsive means operatively connected with said system 'to adjust the idle fuel flow to said engine responsive to changes in the pressure actuating said pressure responsive means, conduit means connecting said manifold and pressure responsive means to actuate the latter responsive to pressure changes in the former, and flow control means operatively connected with said conduit means to regulate the pressure actuating said pressure responsive means at a substantially constant value during operation of said engine at idle, said value being appreciably above the minimum pressure in said manifold during operation of said engine at idle, thereby to maintain said idle fuel flow to said engine at a predetermined rate regardless of variations in said manifold pressure below said constant value.

4. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel metering unit adapted to be operatively connected to said engine and to a fuel source, said unit carrying an adjustable fuel metering valve, an idle boost chamber in said fuel metering unit defined in part by a manifold pressure responsive member, a fluid conduit operatively connecting said idle boost chamber to said intake manifold, said pressure responsive member being operatively connected to said adjustable fuel metering valve to adjust the same in response to manifold pressure to allow a fuel flow to the engine at idle proportional to manifold pressure at idle, and fluid flow control means in said conduit for automatically maintaining the pressure in said idle boost chamber below a predetermined maximum value to prevent the fuel flow from decreasing at manifold pressures greater than exist at engine idle speed, said control means comprising a diaphragm actuated fluid valve.

5. In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit adapted to be operatively connected to said engine and to a fuel source, a fuel metering valve means in said conduit for regulating the flow of fuel to said engine, an idle boost chamber having a manifold pressure responsive member, a fluid conduit operatively connecting said idle boost chamber to said intake manifold for transmitting manifold pressure to said pressure responsive member, said pressure responsive member being operatively connected to said valve means to adjust same, and fluid flow control means in said fluid conduit for automatically limiting the flow of fluid from said manifold to said idle boost chamber in response to a pressure increase in said manifold.

6 In a fuel injection system for an internal combustion engine having an intake manifold, a fuel feed conduit adapted. to be operatively connected to said engine and to a fuel source, a fuel metering valve means in said conduit for regulating the flow of fuel to said engine, an idle boost chamber defined in part by a manifold pressure responsive member, a fluid conduit operatively connecting said idle boost chamber to said intake manifold for transmitting manifold pressure to said pressure responsive member, said pressure responsive member being operatively connected to said valve means to adjust same, and fluid flow control means in said fluid conduit for automatically limiting the flow of fluid from said manifold to said idle boost chamber in response to a pressure increase in said manifold, said control means comprising a diaphragm actuated fluid valve.

7. In a fuel injection system for an internal combustion engine having an intake manifold, a speed metering unit communicating with said engine and a fuel source, said unit carrying an adjustable fuel metering member, said member adapted to be operatively connected to a drive portion of said engine and responsive to engine speed to regulate the flow of fuel to said engine in accordance with said engine speed, an idle boost chamber in said speed metering unit defined in part by a movable diaphragm, a fluid conduit operatively connecting said idle boost chamber to said intake manifold to transmit manifold pressure to said diaphragm, said diaphragm being operatively connected to said adjustable fuel metering member to adjust the same in response to manifold pressure to allow a fuel flow to said engine at idle proportional to manifold pressure at idle, and fluid flow control means in said conduit for automatically prohibiting at idle any pressure increase in said idle boost chamber resulting from a pressure increase in said manifold.

8. In a fuel injection system for an internal combustion engine having an intake manifold, a speed metering unit communicating with said engine and a fuel source, said unit carrying an adjustable fuel metering member, said member adapted to be operatively connected to a drive portion of said engine and responsive to engine speed to regulate the flow of fuel to said engine in accordance with said engine speed, an idle boost chamber in said speed metering unit defined in part by a movable diaphragm, a fluid conduit operativelyconnecting said idle I boost chamber to said intake manifold to transmit manifold pressure to said diaphragm, said diaphragm being operatively connected to said adjustable fuel metering member to adjust the same in response to manifold pressure to allow a fuel flow to said engine at normal engine speed proportional to manifold pressure at normal idle, and fluid flow control means in said conduit for automatically maintaining normal engine idle manifold pressure within said idle boost chamber as engine speed and manifold vacuum drop below their normal idle values.

9. In a fuel injection system for an internal combustion engine having an intake manifold, a speed metering unit adapted to be operatively connected to said engine and to a fuel source, a return flow conduit communicating with said unit and said fuel source, said unit carrying an adjustable fuel metering member responsive to engine speed changes to vary the flow of fuel through said return flow conduit to said fuel source in accordance with said speed changes, an idle boost chamber in said speed metering unit defined in part by a movable diaphragm, a fluid conduit operatively connecting said idle boost chamber to said intake manifold, said diaphragm being operatively connected to said adjustable fuel metering member to adjust the same in response to pressure in said manifold,

and diaphragm actuated fluid flow control means in saidconduit responsive to pressure drops in said manifold to automatically limit the pressure drop in said idle boost chamber.

source, said unit carrying adjustable fuel metering means operatively connected to a drive portion of said engine and responsive to engine speed to vary the flow of fuel to said engine in proportion to said speed, an idle boost chamber in said speed metering unit defined in part by a movable pressure responsive member, a fluid conduit operatively connecting said idle boost chamber to said intake manifold, said member being operatively connected to said fuel metering means to adjust same in response to manifold pressure, and fluid flow control means in said fluid conduit for automatically limiting the ,pressure decrease in said idle boost chamber resulting from a pressure decrease in said manifold, said control means comprising a fluid metering member connected to a flexible diaphragm and responsive to movement of said diaphragm to vary the effective size of said fluid conduit to adjust the flow of fluid therethrough.

11. In a fuel injection system for an internal combus-. tion engine having an intake manifold, a speed metering flow of fuel to said engine in accordance with said speed changes, an idle boost chamber in said speed metering unit having a movable diaphragm, said diaphragm being operatively connected to said fuel metering member to move therewith, a fluid conduit operatively connecting said idle boost chamber to said intake manifold, and fluid flow control means in said conduit for automatically limiting the pressure drop in said idle boost chamber resulting from a pressure drop in said manifold, said control means comprising a pressure chamber having a manifold orifice and an idle boost orifice, a fluid metering member connected to a flexible diaphragm, said member and said diaphragm adapted to shift with respect to said idle boost orifice to limit the flow of fluid from said idle boost chamber to said intake manifold in response to a pressure drop in said intake manifold. j

12. In a fuelinjection system for an internal combus- -tion engine, said engine having an intake manifold and a throttle pivotally mounted therein, a fuel feed conduit duit to regulate the flow of fuel therethrough to said engine, fluid pressure responsive fuel boost means associated with said valve to adjust the same, fluid conduit means connecting said fuel boost means with said manifold to transmit pressure from said manifold to said fuel boost means, and adjustable fuel boost control means in said fluid conduit means, said control means being adjustable in response to the intake manifold pressure at normal engine idle speed to limit the transmission of fluid from said fuel boost means to said manifold to thereby maintain a reserve pressure differential between said manifold and said boost means to maintain a substantially constant fuel boost when said engine speed drops below the minimum allowable engine idle speed and adjust thereby said valve to allow more fuel to flow to said engine and maintain said minimum allowable idle speed.

13. In a fuel injection system for an internal combustion engine, said engine having an intake manifold and a throttle pivotally mounted therein, a fuel feed conduit connected to a fuel supply and communicating with said manifold, an adjustable fuel metering valve in said conduit to regulate the flow of fuel therethrough to said engine, fluid pressure responsive fuel boost means associated with said valve to adjust the same, fluid conduit means connecting said fuel boost means with said manifold to transmit pressure from said manifold to said fuel boost means, and adjustable fluid flow control means in said fluid conduit means, said control means comprising an adjustable flexible diaphragm and valve member secured thereto, said valve member being shiftable by movement of said diaphragm into constricting engagement with said fluid conduit means, said diaphragm and said valve member being adjustable in response to the intake manifold pressure at normal engine idle speed to limit the transmission of fluid from said fuel boost means to said manifold to thereby maintain a reserve pressure differential between said manifold and said boost means to maintain a substantially constant fuel boost when said engine speed drops below the minimum allowable engine idle speed and adjust thereby said valve to allow more fuel to flow to said engine and maintain said minimum allowable idle speed.

14. In a fuel injection system for an internal combustion engine, said engine having an intake manifold and a throttle pivotally mounted therein, a fuel feed conduit connected to a fuel supply and communicating with said manifold, an adjustable fuel metering valve in said conduit to regulate the flow of fuel therethrough to said engine, fluid pressure responsive fuel boost means associated with said valve to adjust the same, bleed means on said fuel boost means to maintain a dynamic fluid condition therein, fluid conduit means connecting said fuel boost means with said manifold to transmit pressure from said manifold to said fuel boost means, and adjustable fluid flow control means communicating with said fluid conduit means across a fuel orifice, said control means comprising an adjustable flexible diaphragm and valve member secured thereto, said valve member being shiftable by movement of said diaphragm into constricting engagement with said orifice, said diaphragm and said valve member being adjustable in response to the intake manifold pressure at normal engine idle speed to limit the transmission of fluid from said fuel boost means to said manifold to thereby maintain a reserve pressure differential between said manifold and said boost means to maintain a substantially constant fuel boost when said engine speed drops below the minimum allowable engine idle speed and adjust thereby said valve to allow more fuel to flow to said engine and maintain said minimum allowable idle speed.

15. In a fuel injection system for an internal combustion engine, said engine having an intake manifold and a throttle pivotally mounted therein, a fuel feed conduit connected to a fuel supply and communicating with said manifold, an adjustable fuel metering valve in said conduit to regulate the flow of fuel therethrough to said engine, said valve being operatively connected to a drive portion of said engine by a speed responsive means, said speed responsive means being operative in response to engine speed to adjust said valve, fluid pressure responsive means associated with said valve to further adjust the same, fluid conduit means connecting said fluid pressure responsive means with said manifold to transmit pressure variations from said manifold to said pressure responsive means, and adjustable fluid flow control means in said fluid conduit means, said control means being adjustable in response to the intake manifold pressure at normal engine idle speed to limit the transmission of fluid from said fuel boost means to said manifold to thereby maintain a reserve pressure differential between said manifold and said boost means to maintain a substantially constant fuel boost when said engine speed drops below the minimum allowable engine idle speed and adjust thereby said valve to allow more fuel to flow to said engine and maintain said minimum allowable idle speed.

16. In a fuel injection system for an internal combustion engine, said engine having an intake manifold and a throttle pivotally mounted therein, a fuel feed conduit connected to a fuel supply and communicating with said manifold, said system also having a return flow conduit connecting said fuel supply and said fuel feed conduit, an adjustable fuel metering valve in said return flow conduit to regulate the flow of fuel therethrough to said fuel supply, fluid pressure responsive means associated with said valve to adjust the same, fluid conduit means connecting said fluid pressure responsive means with said manifold to transmit pressure variations from said manifold to said pressure responsive means, and adjustable fluid flow control means in said fluid conduit means, said control means being adjustable in response to the intake manifold pressure at normal engine idle speed to limit the transmission of fluid from said fuel boost means to said manifold to thereby maintain a reserve pressure differential between said manifold and said boost means to maintain a substantially constant fuel boost when said engine speed drops below the minimum allowable engine idle speed and adjust thereby said valve to allow more fuel to flow to said engine and maintain said minimum allowable idle speed.

17. In an internal combustion engine having an intake system, a fuel supply system comprising fuel metering means, pressure responsive means operatively associated with said metering means and the intake system of said engine and adapted to adjust said metering means in response to changes in the intake suction of said engine, and suction control means operatively associated with said pressure responsive means for maintaining a substantially constant suction force thereon during certain engine operating conditions.

18. A fuel supply system for an internal combustion engine having a combustion charge intake system, said fuel supply system comprising fuel metering means, pressure responsive means operatively connected to said metering means, suction control means operatively connecting said pressure responsive means to said combustion charge intake system, said suction control means being responsive to pressure variations in said combustion charge intake system to maintain substantially constant the suction force on said pressure responsive means throughout a predetermined range of pressures within said combustion charge intake system.

References Cited in the file of this patent UNITED STATES PATENTS Wirth Mar. 7, 1950 4 r. A M