US3625191A

US3625191A - Fuel injection apparatus

Info

Publication number: US3625191A
Application number: US876276A
Authority: US
Inventors: John Kammerer Harding
Original assignee: Dowty Technical Developments Ltd
Current assignee: Dowty Technical Developments Ltd
Priority date: 1968-12-12
Filing date: 1969-11-13
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: DE1962222A1; FR2026017A1; SE351893B; GB1281693A; NL6918727A

Abstract

A fuel injection apparatus for a multicylinder internal combustion engine comprising an integrated unit formed in two easily separable parts of which the first part comprises a drive shaft for connection to the engine, a fuel pump, a fuel-metering device and a distributing valve to distribute the metered fuel to the engine injectors, and the second part comprises control means responding to the operating conditions of the engine and a mechanical adjuster set by the control means, the attachment together of the two parts being such as to connect the adjuster to the metering device for adjustment of the latter in accordance with the operating conditions of the engine.

Description

tlnited States Patent [72] Inventor John Kammerer Harding Charlton Kings, England [2 I] Appl. No. 876,276 [22] Filed Nov. 13, 1969 [45] Patented Dec. 7, 1971 [73] Assignee Dowty Technical Development Limited Cheltenham, England [32] Priority Dec. 12, 1968 [3 3] Great Britain 1 l 1 59,047/68 [54] FUEL INJECTION APPARATUS 2 Claims, 4 Drawing Figs. [52] 11.8.0 ..l23/139AM,

[51] Int. Cl ..F02m 59/32 [50] Field of Search 123/1 19,

139, 139.11 A, 139.17, 139.18, 14OMC [5 6] References Cited UNlTED STATES PATENTS 2,876,755 3/1956 Gold et a1. 123/140 MC Primary Examiner- Laurence M. Goodridge Au0rneyYoung & Thompson ABSTRACT: A fuel injection apparatus for a multicylinder internal combustion engine comprising an integrated unit formed in two easily separable parts of which the first part comprises a drive shaft for connection to the engine, a fuel pump, a fuel-metering device and a distributing valve to distribute the metered fuel to the engine injectors, and the second part comprises control means responding to the operating conditions of the engine and a mechanical adjuster set by the control means, the attachment together of the two parts being such as to connect the adjuster to the metering device for adjustment of the latter in accordance with the operating conditions of the engine.

PATENTEDBEB (I971 3.625191 SHEET 1 or 2 IN V E N TO R Joy/v humus: Mmwva ATTORNEYS FUEL INJECTION APPARATUS This invention relates to a fuel injection apparatus for a multicylinder internal combustion engine and more particularly although not exclusively it relates to such apparatus for use with a multicylinder spark-ignition internal combustion engine.

In accordance with the present invention a fuel injection apparatus for a multicylinder internal combustion engine comprises an integrated unit formed in two easily separable parts of which the first part comprises a drive shaft for connection to the engine, a fuel pump, a fuel-metering device and a distributing valve to distribute metered fuel to the engine injectors, and the second part comprises control means responding to the operating conditions of the engine and a mechanical adjuster set by the control means, the attachment together of the two parts being such as to connect the adjuster to the metering device for adjustment of the latter in accordance with the operating conditions of the engine. By this invention it is possible to provide a standard fuel pump and fuel-metering device and to attach to it a control means responding to a desired engine-operating condition or conditions. In this way the fuel injection apparatus may be easily modified to obtain particular kinds of engine operation such for example as large power output, moderate power output with fuel economy, or a clean exhaust.

The fuel-metering device may comprise a free piston movable with an adjustable stroke and a commutating valve for feeding fuel from the pump to cause alternate movements of the piston and for connecting fuel displaced by the piston to the distributing valve.

The commutating valve and the distributing valve functions may be performed by a single rotary valve connected to the drive shaft. e 1

The mechanical adjuster in the second part may comprise means to adjust one stop in the first part which determines the stroke of the piston.

The control means may be arranged to respond to any of a number of engine operation conditions such as for example as engine inlet manifold pressure, ambient air temperature and exhaust back pressure.

One embodiment of the invention will now be particularly described with reference to the accompanying drawings in which,

FIG. I is a circuit diagram of a fuel injection apparatus in accordance with the invention,

FIG. 2 is a longitudinal cross section through the fuel injection apparatus of FIG. I, and

FIGS. 3 and 4 are views of the face valve member surface and cooperating static surface incorporated in FIG. 2.

These drawings are also used to illustrate the invention contained in our copending application No. 844,790.

Reference is made initially to FIG. I. The apparatus is intended for use with a six-cylinder spark-ignition engine. Fuel is drawn from the fuel tank 1 by an engine-driven gear pump 2 and its delivery pressure is controlled by a relief valve 3 which passes excess fuel back to the fuel tank. A restrictor 4 in series with the relief valve 3 ensures that the delivery pressure of the pump 2 will increase with increased engine speed. The fuel delivered from the pump 2 is fed to either end of a cylinder 5 containing a free piston 6 by means of a rotary commutator valve 7. Fuel displaced from the opposite end of cylinder 5 to that fed with liquid is again fed through the rotary valve 7 to a distributor valve 8 which delivers the fuel to the injectors associated with the cylinders of the engine in a regularly recurring sequence.

The travel of the free piston 6 is limited by two stops 9 and II. The stop 9 is manually adjustable by lever I2 to provide a rich mixture for starting. The stop 11 is restrained by a cam 13 which is moved by two evacuated bellows l4 and 15. The bellows 14 is mounted in a casing and subjected to engine inlet manifold pressure. The bellows I5 is enclosed in another casing and is subjected to engine exhaust back pressure in the engine exhaust manifold. While FIG. 1 shows that both stops 9 and 11 are adjustable it is within the scope of the invention for one of the stops to be fixed and for all adjustments to be effected on the other stop.

The rotary valve 7 and distributor valve 8 are mechanically driven from the engine and the arrangement is such that for every two complete rotations of the engine the free piston will move six times between stops 9 and II to displace six discrete quantities of fuel. The distributor valve 8 will direct these six discrete quantities of fuel in correct sequence to the six injectors associated with the cylinders of the engine. The inlet manifold pressure in the engine will be determined by the setting of the engine inlet throttle, the engine speed and also by the ambient atmospheric pressure. Principally the pressure is determined by the setting of the throttle which will then determine the movement applied from the bellows 14 to the cam 13. At the same time the exhaust back pressure acts in a contrary sense to reduce partially the movement given by bellows 14 to the cam 13. The principal function of the bellows I5 is to compensate for the characteristics of different exhaust systems which might be operative on different engines fitted with the illustrated injection system. It is normal that the injectors for the cylinders are arranged in the inlet manifold immediately adjacent to the cylinder inlet valves and the period over which the injection of fuel lasts for any injector is preferably arranged to coincide with the normal induction stroke of each engine piston in its cylinder. In the case of a four-or six-cylinder engine it can be arranged that the delivery of the gear pump 2 is continuously or almost continuously fed to one or other injector.

Reference is now made to FIGS. 2, 3 and 4 of the drawings. These drawings show in practical detail the apparatus embodying the circuit arrangement of FIG. 1. The drive shaft 16 (FIG. 2) protrudes from the right-hand end of the apparatus and is driven at half engine speed by a bevel drive from the distributor shaft of the engine, or alternatively it may be driven by a toothed belt from the crank shaft or the cam shaft. Within the body of the device the drive shaft is connected to drive the gear pump 2 which is normally arranged to pump fuel at a rate of about four times the maximum rate at which the engine normally uses fuel thereby providing an adequate excess of fuel for starting. The pump 2 delivers its fuel into a chamber 17 within the device. The pump delivery pressure is controlled by a relief valve (not shown) in FIG. 2 but arranged as described in FIG. I. The shaft extends to the valve chamber 17 where it is coupled to the rotaryvalve member 18 of a face valve. The rotary member is loaded by spring 19 and also by fuel pump pressure to engage the static valve face 23 formed on the static member 21. This static member is conveniently a part of a fixed casing of the apparatus. The

cooperating surfaces

22 and 23 of the moving and stationary members of the face valve are shown by FIGS. 4 and 3 respectively. The rotating valve member has seven ports opening into its face 22. Six of these

ports

24, 25, 26, 27, 28 and 29 lie on the same comparatively small pitch circle and are equidistantly spaced from one another. The remaining port 31 is located on a larger pitch circle. The three

ports

24, 26 and 28 pass completely through the member 18 and communicate with the chamber I7. All of the four

ports

25, 27, 29 and 31 extend only partially through the member 18 and are internally all connected together by means of passages 32 within the member I8. The stationary face 23 includes two diametrically opposed ports 33 and 34 on the smaller pitch circle and six equally

spaced ports

35, 36, 37, 38, 39 and 41 on the larger pitch circle. The two inner ports 33 and 34 are connected by internal passages to the two ends of the metering cylinder 5. The ports 35 to 41 are individually connected to screw-threaded connections 42 in the body of the device from which pipes extend to the injectors in the engine inlet manifold adjacent to the engine inlet valves.

During rotation of the engine and of the drive shaft I6 the pump 2 will pump fuel at pressure into the valve chamber I7. The rotary valve by the cooperation of the ports 24 to 29 and 33 and 34 will feed fuel alternately to the ends of the metering cylinder 5 and will connect the liquid delivered from the metering cylinder 5 to the passage 32 in the member 18 which is then fed to the distributor portion of the valve for distribution to the injectors. The ports on the smaller pitch circle i.e. the ports 24 to 29 and 33 and 34 together form the commutating portion of the valve and the ports 31, 35 to 41 form the distributing portion of the valve.

The elements of FIG. 2 so far described are contained in the right-hand part of the apparatus indicated generally by reference numeral 51. This part terminates at a plane surface 52 extending at right angles to the axis of the cylinder 5. The stop 11 is located centrally of the surface 52. The left-hand unit 53 of the apparatus may be detachably secured by a plane surface 54 to the surface 52, the means being any conventional means such as screw-threaded bolts 50. Within the part 53 the bellows 14 is located in a chamber 44 connected through connection 45 to the inlet manifold of the engine. Also within the part 53 the bellows 15 is located in a chamber 46 connected by connection 47 to the exhaust manifold of the engine. The cam 13 is located in a chamber 55 which lies between

chambers

44 and 46, this cam being formed on a rod 56 which interconnects the two bellows. Chamber 55 is vented to atmosphere. A cam follower 43 is slidably mounted in the part 53 so as to project from the surface 54 and to be capable of engaging the stop 11 when the two

parts

51 and 53 are secured together. The cam follower 43 engages the cam 13 and the movement of the cam by the two bellows will adjust the follower and the stop 11. For convenience a diaphragm 57 is clamped in position between the two surfaces 52 and 54 so that any slight leakage of fuel from the end of cylinder 5 containing stop 11 may be collected and fed through the return connection back to the fuel tank.

The movement of the stop 11 will be proportional to intake manifold absolute pressure less a constant multiplied by exhaust manifold absolute pressure. The correct value of this constant depends on engine design, particularly compression ratio and the exhaust pressure correction of the fuel injection apparatus can be changed by changing the effective area of the bellows 15. Small corrections can also be made by changing the diameter of the rod 56 which connects the two bellows.

By leaving a small amount of gas in the bellows l4 and arranging that some air flows through the bellows chamber 44 to the inlet manifold it is also possible to correct for a change in intake air temperature.

The right-hand stop is adjustable by means of a rotary cam 45 connected to an adjustable handle. For the position shown in FIG. 2, stop 9 allows the largest amount of movement of the free piston 6 and thus the greatest displacement of fuel which corresponds to the fuel flow required for starting the engine. For normal running the cam 45 is rotated to a predetermined position to urge the stop 9 inwardly into the cylinder to limit the travel of the piston 6.

it is also within the scope of the invention that the stop 9 should be fixed in position and that cam 45 or the equivalent should be included within the part 53 so that all control adjustment is effected by adjustment of the stop 11.

The described fuel injection apparatus may provide very simply for the feeding of fuel to a spark-ignition multicylinder internal combustion engine such that under substantially all conditions of operation a correct mixture strength may be obtained depending on the performance required from the engine which may be for example either maximum power output or alternatively maximum economy of operation. Conventional carburetor systems for supplying fuel to a spark-ignition engine cannot give an accurately constant control of mixture strength, either to the individual cylinders or to the overall flow of air to the engine. Conventional fuel injection systems overcome these defects but tend to be complicated and not to correct fully for variations in operating conditions of the engine. The described embodiment in FIG. 2 is simple and compact and can be arranged to give accurate control of mixture strength within the engine particularly by virtue of the fact that control of fuel is in accordance with the absolute values of pressure in the engine inlet manifold and in the exhaust manifold. The described embodiment of FIG. 2 provides the one basic part 51 of the apparatus containing the fuel pump, the fuel-metering device means and the fuel-distributing valve and the part 53 which may be easily substituted can be so made as to obtain the desired operation of the engine, be it maximum power output or maximum economy of operation.

While the described invention is particularly intended for use with a multicylinder spark-ignition engine it is usable with minor modifications for supplying fuel to the injectors of a compression ignition engine. With such an engine the constancy of the mixture strength is irrelevant but the combination of rotary face valve member and free piston metering device forms a compact fuel injection unit usable with such an engine. Of course the injectors would operate directly into the engine cylinders and the timing of the fuel injection would be accurately controlled in accordance with normal compression ignition practice.

I claim:

1. Fuel injection apparatus for a multicylinder internal combustion engine, comprising an integrated unit formed in two separable parts, joinable together at plane attachment surfaces, of which the first part comprises a drive shaft for connection to the engine, a gear pump for pumping fuel to pressure, a fuel pressure chamber receiving fuel at pressure from the pump, a rotary disc valve mounted in said chamber, injector connections for the cylinders of the engine, a metering cylinder, a reciprocatory free piston located in the metering cylinder, a pair of stops in said cylinder determining limits of movement of the free piston, one of said stops being adjustable and extending to the said plane attachment surface, and passage means interconnecting the rotary disc valve with the metering cylinder and the injector connections so that, during rotation of the shaft, the valve commutates fuel to the metering cylinder to reciprocate the piston between the stops and distributes fuel from the cylinder to the injector connections, and of which the second part includes a linearly moving cam mounted for sliding movement parallel to said attachment surface, a cam follower slidably mounted for movement at right angles to said attachment surface in engagement with said cam and also in engagement with said adjustable stop when the two parts are secured together, a first closed chamber, an evacuated bellows in said first closed chamber, means adapting said first closed chamber for connection to the inlet manifold of the engine and spring loading to hold the cam against the bellows whereby movement of the bellows following change in manifold pressure is communicated to said cam and to the cam follower to adjust the position of said adjustable stop.

2. A fuel injection apparatus as claimed in claim I, wherein said second part includes a second closed chamber for connection to the exhaust manifold of the engine, a second evacuated bellows mounted in said second chamber and spring loading arranged to urge the second bellows against the cam to effect linear movement thereof in opposition to the first bellows movement.

Claims

2. A fuel injection apparatus as claimed in claim 1, wherein said second part includes a second closed chamber for connection to the exhaust manifold of the engine, a second evacuated bellows mounted in said second chamber and spring loading arranged to urge the second bellows against the cam to effect linear movement thereof in opposition to the first bellows movement.