GB2147954A - Fuel pumping apparatus - Google Patents

Abstract

A fuel pumping apparatus for supplying fuel to an internal combustion engine includes a plunger 11 reciprocable within a bore 10 the inner end of which communicates with a fuel injection nozzle 14. Rotary valves 18, 19 control the supply of fuel to the bore and the spillage of fuel from the bore, the rotary valves being driven by servo motors 23, 24 respectively or by epicyclic mechanism which includes servo motors The motors are controlled by an electronic control unit 25 whereby the quantity of fuel supplied to the nozzle and its timing can be controlled in accordance with various engine operating parameters. <IMAGE>

Description

SPECIFICATION Fuel pumping apparatus This invention relates to fuel pumping apparatus for supplying fuel to an internal combustion engine and of the kind comprising a plunger reciprocable within a bore defined in a body part, cam means operable in use to impart inward movement to the plunger to displace fuel from one end of the bore in timed relationship with an associated engine, said one end of the bore communicating at least during inward movement of the plunger, with an outlet connected in use to a fuel injection nozzle of the associated engine and valve means operable to control the timing and duration of fuel delivery through the outlet.

The object of the invention is to provide such an apparatus in a simple and convenient form.

According to the invention said valve means comprises a pair of rotary valves mounted in the body part, said valves controlling flow of fuel in respective passages connected with said outlet, means for driving said rotary valves in timed relationship with the engine and means for adjusting the timing of operation of said valves relative to each other and relative to the engine.

Examples of apparatus in accordance with he invention will now be described with reference to the accompanying drawings in which Figure 1 is a diagrammatic iliustration of one example of the apparatus, Figure 2 is a diagrammatic illustration of another form of apparatus, and Figure 3 is a perspective view of a valve forming part of the apparatus of Figs. 1 and 2.

Referring to Fig. 1 of the drawings the apparatus comprises a bore 10 in which is mounted a reciprocable pumping plunger 11.

The plunger is biased outwardly away from one end of the bore by means of a coiled compression spring 1 2 and is movable inwardly by the action of a rotary cam 1 3 which is driven in timed relationship with an associated engine.

The aforesaid one end of the bore 10 is connected to the inlet of a fuel injection nozzle generally indicated at 14 and which includes as is well known in the art, a resiliently loaded valve member 1 5 which controls fuel flow through outlet orifices 1 6. The passage 1 7 which connects the one end of the bore with the nozzle is connected by branch passages respectively to a pair of rotary valves 18, 19 the valve 18 is able to connect its associated branch passage with a low pressure fuel source 20 and the valve 1 9 is able to connect its associated passage to the same source 20 or alternatively to a drain.

The rotary valves as shown in Fig. 3, include a rotary member 21 housed in a bore.

Substantially half the rotary member is cut away and the remaining portion of the valve member controls communication between its associated branch passage 22 and a circum ferentiai groove defined in the rotary member the groove communicating depending on which valve is considered, with the source 20 or drain.

The valves are rotated by servo motors 23, 24 respectively and are driven at the same speed as the cam 1 3. The motors are controlled by an electronic control unit 25 which is responsive to various engine operating parameters such for example as the engine speed and engine crankshaft position and the fuel demand.

The operation of the apparatus will now be described starting from the position in which the various parts are shown in Fig. 1. As will be noted from Fig. 1 the cam is moving the plunger inwardly so that fuel is being displaced from the bore 10. Both valves are closed so that fuel is being delivered to the injection nozzle to lift the valve member to allow fuel flow through the outlet orifices 1 6.

As the cam 1 3 continues to rotate the valves which operate in synchronism with the cam, also rotate and the valve 1 9 opens to allow fuel flow from the bore to the surface 20 or the drain. The effect of this is to lower the pressure in the passage 1 7 thereby allowing the nozzle 1 4 to close. The fuel displaced during the remaining inward movement of the plunger 11 flows to the source or the drain and at some point the valve 1 8 also opens.

During outward movement of the plunger 11 fuel is drawn into the bore 10 through both valves and the first valve to reclose is the valve 1 9. The valve 18 however will remain open for a period after closure of the valve 1 9 and will be open during the initial inward movement of the plunger 11. Initial displacement of fuel by the plunger 11 is therefore back to the low pressure source 20. However.

when the valve 1 8 closes delivery of fuel will take place to the nozzle. The valve 1 8 therefore controls the timing of the commencement of fuel flow to the nozzle and the valve 1 9 controls the termination of fuel flow. The amount of fuel which flows to the nozzle therefore depends upon the relative timing of the valves 1 8 and 1 9 while the timing of the commencement of fuel delivery depends upon the timing of the valve 18 relative to the cam.

The control circuit 25 can effect variation of the relative timing of the valves so that the desired quantity of fuel is supplied to the engine and is also able to adjust the timing of both valves relative to the cam so that the timing of fuel delivery can be adjusted.

Turning now to Fig. 2 an alternative form of apparatus is illustrated which comprises a rotary distributor member 26 mounted in a body 27. The distributor member is arranged to be driven in timed relationship with the associated engine and is provided with a pair of interconnected bores 28 in which are mounted pumping plungers 29. Located at the outer ends of the plungers are cam followers including rollers which engage with the internal peripheral surface of an annular cam ring 30. The interconnected bores communicate with a longitudinal passage 31 formed in the distributor member and which at one point communicates with a radially disposed delivery passage 32. The passage 32 is arranged to register in turn with a plurality of outlets 33 connected to the injection nozzles 14 respectively.The cam ring is provided with cam lobes equal in number to the number of outlets 33, the lobes being disposed in diametrically disposed pairs.

The passage 31 also communicates with a radial passage 34 which communicates with a circumferential groove formed on the periphery of the distributor member and connected to the valves 18 and 19. The valves are connected as in the example of Fig. 1. In this example the valves 1 8 and 1 9 rotate in the case of a four cylinder engine, at a speed which is four times that of the distributor member 26 and fuel is therefore fed to the outlets 33 in turn, the delivery passage 32 registering with an outlet 33 during the whole time the plungers are moved inwardly by the action of the cam lobes.

As described the valves 1 8 and 1 9 are operated by servo motors 23, 24. They may however be driven mechanically by respective epicyclic mechanisms, the adjustments for timing and fuel quantity being effected by rotating one of the components of the epicyclic mechanism for example the annulus.

Such adjustment can be effected electrically using a servo motor.

CLAMS 1. A fuel pumping apparatus for supplying fuel to an internal combustion engine comprising a plunger reciprocable within a bore defined in a body part, cam means operable in use to impart inward movement to the plunger to displace fuel from one end of the bore in timed relationship with an associated engine, said one end of the bore communicating at least during inward movement of the plunger, with an outlet conncted in use to a fuel injection nozzle of the associated engine and valve means operable to control the timing and duration of fuel delivery through the outlet, said valve means comprising a pair of rotary valves mounted in the body part, said valves controlling flow of fuel in respective passages connected with said outlet, means for driving said rotary valves in timed relationship with the engine and means for adjusting the timing of operation of said valves relative to each other and relative to the engine.

2. An apparatus according to Claim 1 in which said valves are driven by servo motors respectively, the apparatus including an electronic control unit for controlling the operation of said servo motors, said control unit being responsive to various engine operating parameters to adjust the relative timing of the valves and the timing of both valves relative to the cam means.

3. An apparatus according to Claim 1 including means for driving said rotary valves and servo motors operable to adjust the timing of the valves respectively.

4. An apparatus according to Claim 3 in which said valves are driven through respective epicyclic mechanisms, said servo motors being operable to rotate one component of the respective mechanisms.

5. A fuel pumping apparatus for supplying fuel to an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. body 27. The distributor member is arranged to be driven in timed relationship with the associated engine and is provided with a pair of interconnected bores 28 in which are mounted pumping plungers 29. Located at the outer ends of the plungers are cam followers including rollers which engage with the internal peripheral surface of an annular cam ring 30. The interconnected bores communicate with a longitudinal passage 31 formed in the distributor member and which at one point communicates with a radially disposed delivery passage 32. The passage 32 is arranged to register in turn with a plurality of outlets 33 connected to the injection nozzles 14 respectively. The cam ring is provided with cam lobes equal in number to the number of outlets 33, the lobes being disposed in diametrically disposed pairs. The passage 31 also communicates with a radial passage 34 which communicates with a circumferential groove formed on the periphery of the distributor member and connected to the valves 18 and 19. The valves are connected as in the example of Fig. 1. In this example the valves 1 8 and 1 9 rotate in the case of a four cylinder engine, at a speed which is four times that of the distributor member 26 and fuel is therefore fed to the outlets 33 in turn, the delivery passage 32 registering with an outlet 33 during the whole time the plungers are moved inwardly by the action of the cam lobes. As described the valves 1 8 and 1 9 are operated by servo motors 23, 24. They may however be driven mechanically by respective epicyclic mechanisms, the adjustments for timing and fuel quantity being effected by rotating one of the components of the epicyclic mechanism for example the annulus. Such adjustment can be effected electrically using a servo motor. CLAMS

1. A fuel pumping apparatus for supplying fuel to an internal combustion engine comprising a plunger reciprocable within a bore defined in a body part, cam means operable in use to impart inward movement to the plunger to displace fuel from one end of the bore in timed relationship with an associated engine, said one end of the bore communicating at least during inward movement of the plunger, with an outlet conncted in use to a fuel injection nozzle of the associated engine and valve means operable to control the timing and duration of fuel delivery through the outlet, said valve means comprising a pair of rotary valves mounted in the body part, said valves controlling flow of fuel in respective passages connected with said outlet, means for driving said rotary valves in timed relationship with the engine and means for adjusting the timing of operation of said valves relative to each other and relative to the engine.

2. An apparatus according to Claim 1 in which said valves are driven by servo motors respectively, the apparatus including an electronic control unit for controlling the operation of said servo motors, said control unit being responsive to various engine operating parameters to adjust the relative timing of the valves and the timing of both valves relative to the cam means.

3. An apparatus according to Claim 1 including means for driving said rotary valves and servo motors operable to adjust the timing of the valves respectively.

4. An apparatus according to Claim 3 in which said valves are driven through respective epicyclic mechanisms, said servo motors being operable to rotate one component of the respective mechanisms.

5. A fuel pumping apparatus for supplying fuel to an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.