GB2096710A

GB2096710A - Fuel injection pumping apparatus

Info

Publication number: GB2096710A
Application number: GB8207185A
Authority: GB
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1981-04-11
Filing date: 1982-03-11
Publication date: 1982-10-20
Also published as: GB2096710B

Abstract

A fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine comprises a plurality of plungers 10, 11, 12 equal in number to half the number of engine cylinders. The bores which accommodate the plungers are each provided with a pair of outlet ports 33 each leading to an engine injection nozzle. The outlet ports 33 are brought into communication with inlet ports 24, 25 by means of plunger grooves 31, 32 during the inward movement of the associated plunger, the inward movement of the plungers being effected one at a time by cams 13, 14, 15 driven by the engine. Valve means 28, 29 is provided to direct the fuel displaced by a plunger to one or the other of the inlet ports 24, 25 associated with that plunger. <IMAGE>

Description

SPECIFICATION Fuel injection pumping apparatus This invention relates to fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine.

It is known to provide pumping apparatus with individual injection pumps for supplying fuel to the engine cylinders respectively. In such an apparatus the pumps are actuated in timed relationship by respective cams mounted on a cam shaft. Each pump has a quantity control member and the individual control members are connected together to a common control member. For an engine with a considerable number of cylinders the cam shaft is long and therefore requires more than two bearings and must also be of sufficient strength to resist torsional deflection. It is also known to having a single injection pump which through a distributor member supplies fuel to the engine cylinders in turn. A disadvantaye of this arrangement is that the injection pump has to operate more quickly and this can cause problems with fuel flow.

The object of the present invention is to provide a pumping apparatus which has half the number of injection pumps as there are engine cylinders and with improved control of the timing of delivery of fuel and the quanitity of fuel supplied by the apparatus.

According to the invention a fuel injection pumping apparatus for supplying fuel to a multi cylinder internal combustion engine comprises a plurality of pumping plungers housed in respective bores, the number of plungers being equal to half the number of engine cylinders, cam means driven in use by the associated engine for effecting inward movement of the plungers within the bores, a pair of outlet ports extending from each bore for connection in use to two injection nozzles respectively of the associated engine, a pair of inlet ports extending into each bore and groove means on the plungerforconnecting the inlet ports to the outlet ports respectively as the associated plungers are moved inwardly, each inlet port being connected to an inlet port associated with another plunger and valve means for connecting one or the other of said inlet ports to receive fuel displaced by the pumping plungers during their inward movement.

In the accompanying drawings: Figure 1 is a diagrammatic view of one example of an apparatus in accordance with the inventipn, Figure 2 is a view similar to Figure 1 showing another example of an apparatus in accordance with the invention and Figure 3 is a view similar to Figures 1 and 2 showing a further example of an apparatus in accordance with the invention.

The examples shown in the drawings are for supplying fuel to a six cylinder compression ignition engine and one of the common features of the different forms of the apparatus is the fact that only three pumping plungers are employed. Each plunger besides performing its pumping action when it is moved in one direction, acts to connect a pair of outlets which in use are connected to a pair of injection nozzles of the associated engine respectively, to a pair of conduits. The plungers do not rotate during their movement.

Referring now to Figure 1 three pumping plungers 10, 11 and 12 are shown which are movable inwardly by cams 1 3, 14, 1 5 respectively mounted upon a cam shaft 1 6 which is driven in timed relationship with the associated engine. The apparatus illustrated is diagrammatic and in a practical embodiment springs would be provided to urge the plungers outwardly following their inward movement by the cams and furthermore, cam followers would be provided between the plungers and the cams. Each bore has in its side wall a feed port 1 7 and the ports connect with a supply of fuel at low pressure. The ports are positioned to be covered by the plungers during their inward movement.Moreover, each bore is provided with an outlet port 1 8 and these are connected to a chamber 1 9 which can be connected to a drain 20 when a valve 21 is opened, the valve being controlled by an electromagnetic device 22. For communication with the ports 18 during the inward movement of the plungers, each plunger is provided with an axial drilling 23 which terminates in a radial drilling arranged to be uncovered to the respective port 1 8 before the plunger covers the respective inlet port 1 7.

Formed in the wall of each bore is a pair of inlet ports 24, 25. The ports 24 are connected to a manifold 26 and the ports 25 are connected to a manifold 27. These manifolds communicate with the chamber 19 by way of valves 28, 29 respectively. The valves are coupled together so that when one valve is open the other is closed and they are operated by an electro-magnetic device 30.

Each plunger is provided with a pair of flats and formed in the wall of each bore are a pair of outlet ports each of which is referenced 33. The outlet ports 33 are connected to respective injection nozzles of the associated engine and in Figure 1 it will be noted that each outlet port 33 has adjacent to it a single digit number indicative of the cylinder number of the engine in the example, with which that outlet is associated.

In Figure 1, the plunger 11 is shown to be completing its inward movement and fuel is being displaced through the outlet 1 8 to the chamber 19. As it happens the valve 21 is open so that the fuel which is thus displaced is allowed to flow to a drain. Assuming however that the valve 21 is closed the fuel will flow from the chamber 19 by way of the valve 29 to the manifold 27. The inlet ports 24 which are formed in the bores associated with the plungers 10 and 12 are closed but the port 24 which is associated with the plunger 11 is open to the outlet 33 by way of the flat 31 on the plunger. Until the valve 21 was opened therefore fuel was being delivered to this outlet. The delivery of fuel in this manner ceases when the valve 21 is opened and the surplus fuel flows to the drain.It should be noted that the ports 24 and 25 associated with the bores accommodating the other plungers, are both closed by the respective plungers.

The next engine cylinder to receive fuel is that numbered 5 and the respective port 33 is formed in the bore which accommodates the plunger 12.

As the cam shaft 1 6 rotates the plunger 11 will move outwardly and when the port 17 is uncovered by the end of the plunger, fuel will flow into the pumping chamber. Some fuel may in fact flow to the chamber through the passage 23, the fuel being drawn from the chamber 1 9. As soon as the plunger has moved outwardly a sufficient extent to obturate the port 1 8, this flow of fuel ceases and furthermore, the flats 31,32 of the plunger 11 move out of register with the ports 24, 25 so that these are now closed. Inward movement of the plunger 12 then takes place. As the plunger moves the port 1 7 is gradually closed and the port 18 opened to the passage 23. As soon as the port 1 7 is fully closed fuel will flow to the chamber 19.Since fuel is required to flow to cylinder number 5, the setting of the valves 28 and 29 is not altered and the start of delivery of fuel through the outlet takes place when the valve 21 is closed. Thus the closure of the valve 21 determines the start of delivery of fuel and the quantity of fuel delivered is determined by the time considered in terms of degrees of cam shaft rotation, during which the valve 21 is closed.

The next cylinder requiring fuel is that numbered 2 and the supply of fuel to this cylinder is achieved by movement of the plunger 1 0. It should also be noted that the outlet 33 which is associated with number 2 cylinder of the engine is associated with the manifold 26 and therefore it is necessary for the setting of the valves 28 and 29 to be reversed from the setting shown in the drawing. The control of the valve 21 and in particular the electro-magnetic device 22 is effected by an electronic control circuit which receives signals indicative of engine speed, engine position, and the demand placed upon the engine by the operator. The electro-magnetic device 30 can be controlled by the same circuit but if desired, the valves 28 and 29 may be controlled by a cam mounted on the cam shaft 1 6.

Referring now to Figure 2 the apparatus shown therein is somewhat similar to the apparatus shown in Figure 1 and where possible, the same reference numerals have been utilized. In the arrangement shown in Figure 2 however the passages 23 in the plungers are omitted as also are the ports 18, the chamber 19 and the valves 28,29. Each manifold 26,27 is connected by way of a valve controlled inlet, to each of the bores accommodating the plungers so that each bore has associated with it two valves operated in synchronism by an electro-magnetic device. In the drawing the valves associated with the bore containing the plunger 10 are referenced 34, 35 and the associated electro-magnetic device is referenced 36.The equivalent items associated with the bore containing the plunger 11 are referenced 37, 38 and 39 and those items associated with the bore containing the plunger 12 are referenced 40, 41 and 42.

The various parts in Figure 2 are shown in a position corresponding to the position of the parts in Figure 1 hence plunger 11 is being moved inwardly and fuel is being displaced from the bore by way of the valve 37 to the manifold 27. The fuel is flowing through the inlet port 24 associated with the plunger 11, to the outlet 33 which is connected to the nozzle associated with no. 3 cylinder of the engine. It will be noted that the gallery 27 is filled with fuel under pressure since the valves 34 and 40 are closed.In order to terminate delivery of fuel to the engine one or the other of these valves is opened so that the fuel is spilled into the bore associated therewith and can flow to the associated fuel inlet 1 7. As with the previous example, pressurisation of the fuel can only occur when the inwardly moving plunger closes the port 1 7 and delivery of fuel takes place only when the valves 34 and 40 are closed. Thus one or the other of these valves can be utilized to determine the start of injection of fuel. As with the previous example, the next port 33 which requires fuel is that which is associated with no. 5 cylinder of the engine and this is the port associated with plunger 12.This plunger is therefore the next plunger to move inwardly after the plunger 11 has moved outwardly its maximum extent if the valve 40 was opened to terminate delivery of fuel from the bore associated with the plunger 11 then this valve can remain in the open position since it is through the port with which this valve is associated that the fuel will flow to the port 24 and outlet 33. The delivery of fuel to the outlet 33 will only take place when the valves 34 and 37 are closed. Since the valve 37 was previously open to permit delivery of fuel to the outlet 33 associated with number 3 cylinder of the engine it is convenient to close this valve in order to achieve delivery of fuel. Again as with the previous example, the next cylinder which requires fuel is number 2 and the injection nozzle of this cylinder is connected to the port 33 associated with the plunger 10.In tfiis case however it is the manifold 26 which is pressurised with fuel and the valves 38 and 41 must be closed to permit delivery of fuel. As previously mentioned the valves are operated by electro-magnetic devices. It is possible for one pair of valves for example valves 34 and 35, to be operated by mearls of a cam mounted on the cam shaft. This clearly requires that the remaining two devices operate more frequently to control the start and end of delivery of fuel.

Turning now to Figure 3, the apparatus shown can be regarded as being a modification of the apparatus shown in Figure 2 and hence wherever possible, the parts which perform the same function have been allotted the reference numerals used in Figure 2. It will be noted that whilst the inlet port 24 and 25 of each bore are connected as in the example of Figure 2, by way of the valves associated with that bore, to the end of the bore from which fuel is delivered, they are not connected to separate manifolds. Instead the inlet ports 24 and 25 of each bore are inter-connected in a single manifold thus the port 24 associated with the plunger 10 is connected to the port 25 associated with the plunger 12 and the port 24 associated with the plunger 12 is connected to the port 25 associated with the plunger 11.The port 24 associated with the plunger 11 is connected to the port 25 associated with the plunger 10. In Figure 3 the parts are shown in corresponding positions to the parts of Figures 1 and 2 so that the plunger 11 is being moved inwardly. The valve 38 is closed whilst the valve 37 is open and also closed is the valve 35 so that fuel can flow by way of the port 24 and outlet 33 associated with the plunger 11 , to the injection nozzle associated with number 3 cylinder of the engine. In order to terminate delivery of fuel and also control the start of delivery, the valve 35 may be opened or closed or it is possible for the valves 37 and 38 to be moved to the alternative position. This is not preferred however since the valve 40 must also be open.

The next engine cylinder which requires fuel is that numbered 5 and this is connected to the outlet 33 associated with the plunger 12. In order for fuel to be delivered through this outlet the plunger 12 is therefore moved inwardly with the valve 40 open and the delivery of fuel being controlled preferably by the valve 38. As with the previous examples, it is possible for one pair of valves to be operated by a cam on the cam shaft 16.

Claims

1. A fuel injection pumping apparatus for supplying fuel to a multi cylinder internal combustion engine comprising a plurality of pumping plungers housed in respective bores, the number of plungers being equal to half the number of engine cylinders, cam means driven in use by the associated engine for effecting inward movement of the plungers within the bores, a pair of outlet ports extending from each bore for connection in use to two injection nozzles respectively of the associated engine, a pair of inlet ports extending into each bore and groove means on the plunger for connecting the inlet ports to the outlet ports respectively as the associated plungers are moved inwardly each inlet port being connected to an inlet port associated with another plunger and valve means for connecting one or the other of said inlet ports to receive fuel displaced by the pumping plungers during their inward movement.

2. An apparatus according to Claim 1 including feed ports in the walls of the bores respectively, said feed ports being connected in use to a source of fuel and the ports being positioned to be covered by the plungers during inward movement thereof.

3. An apparatus according to Claim 1 or Claim 2 in which one inlet port of each bore is connected to a first manifold and the other inlet of each bore is connected to a second manifold, said valve means acting to direct fuel flowing from a bore during the inward movement of the associated plunger to one of said manifolds.

4. An apparatus according to Claim 3 in which said valve means comprises a pair of valves operable to connect one of the other of said manifolds to a chamber, and a further valve operable to allow fuel flow from said chamber to a drain whereby the quantity of fuel supplied to the associated engine during inward movement of a plunger can be controlled.

5. An apparatus according to Claim 4 including outlet ports in the bore, said outlet ports communicating with said chamber, and drillings in the plungers which are brought into communication with said outlet ports during inward movement of the plungers whereby the fuel displaced by said plungers is supplied to said chamber.

6. An apparatus according to Claim 3 in which said valve means comprises a pair of valves associated with each bore, each pair of valves being arranged so that one or the other of said manifolds is connected to the inner end of the associated bore, the quantity of fuel supplied to the engine being controlled by operating a pair of valves associated with a plunger which is not undergoing inward movement.

7. An apparatus according to Claim 2 in which said valve means comprises a pair of valves associated with each bore, the quantity of fuel supplied to the engine being controlled by operating a pair of valves associated with a plunger which is not undergoing inward movement.

8. An apparatus according to any one of the preceding Claims in which said valve means is operated by an electromagnetic device.

9. A fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine comprising the combination and arrangement of parts substantially as herein described with reference to Figure 1 of the accompanying drawings.

10. A fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine comprising the combination and arrangement of parts substantially as herein described with reference to Figure 2 of the accompanying drawings.

11. A fuel injection pumping apparatus for supplying fuel to a multi-cylinder internal combustion engine comprising the combination and arrangement to parts substantially as herein described with reference to Figure 3 of the accompanying drawings.