GB1601006A - Fuel injection pumping apparatus - Google Patents

Description

(54) FUEL INJECTION PUMPING APPARATUS (71) We, LUCAS INDUSTRIES LI MITED, a British Company of Great King Street, Birmingham B19 2XF, England, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to a fuel injection pumping apparatus for supplying fuel to an injection nozzle of an internal combustion engine and of the kind comprising a piston means contained within a bore, an outlet from one end of the bore, said outlet in use communicating with an inlet of the nozzle, a fuel inlet to said one end of the bore connected in use to a source of fuel under pressure, a valve operable to prevent flow of fuel through said inlet during delivery of fuel through said outlet, a reciprocable plunger contained within a cylinder, cam means for urging the plunger towards one end of the cylinder, passage means connecting said one end of the cylinder with the other end of said bore whereby liquid displaced during movement of the plunger by the cam will act on said piston means to urge the piston to displace fuel through said outlet and a non-return valve in said passage means to prevent flow of liquid from said bore to said cylinder.

One example of such an apparatus is shown in the specification of British Patent 861754. In this case the delivery of fuel through the outlet always occurs at the same position of the cam irrespective of the speed of the associated engine and the quantity of fuel being supplied thereto. Moreover, the control of the amount of fuel supplied by the system is effected using a variable orifice through which fuel passes to the inlet of the bore. In this case the means of inducing a flow of fuel into the bore is by means of a spring which acts on the piston means.

Adjustment of the timing of delivery of fuel is necessary in order to achieve correct operation of the associated engine and the method of controlling the amount of fuel supplied described in the aforesaid specification has disadvantages when the associated engine has a wide speed range.

A modification of the apparatus is shown in the specification of British Patent 1306422. In this case an electromagnetic valve is provided to allow liquid to escape from between the plunger and piston means as the plunger is moved by the cam. This enables the timing of the delivery of fuel to be adjusted. Moreover, there is also provided a solenoid operated valve which controls the amount of fuel supplied to the bore. The control of the maximum fuel which can be delivered to the engine is effected by an adjustable stop which limits by its engagement with the piston, the maximum movement of the piston. The stop is adjustable by means of a rotary solenoid.

The system shown in specification 1306422 has important advantages over the system shown in specification 861754 in that it is possible to provide electronic control.

There is however no indication of the amount of fuel being supplied to the engine and the system requires three solenoid operated devices to provide the required degree of control.

The object of the present invention is to provide a system of the kind specified in an improved form in which improved control of the quantity of fuel supplied by the apparatus is obtained using a solenoid operated valve with the same valve being utilized to enable variation of the timing of delivery of fuel to be obtained.

According to the invention an apparatus of the kind specified comprises a solenoid controlled valve operable to allow flow of liquid from the other end of said bore, a transducer for providing a signal indicative of the position of said piston means, a control circuit for controlling the operation of said valve, said control circuit receiving the signal from the transducer, first means for providing a signal to said control circuit, indicative of the amount of fuel to be delivered to the engine, and second means for providing an engine position and speed signal to said control circuit, whereby during movement of the plunger by the cam the valve is closed at a position to cause delivery of fuel at the desired time, and whereby during filling of the bore the valve is closed when the piston means attains a position appropriate to the amount of fuel to be delivered to the engine.

The accompanying drawing is a diagrammatic representation of one example of an apparatus according to the invention.

With reference to the drawing a piston 10 is provided and which is movable in a bore 11 the latter having a reduced portion 12 in which is located a further piston 13 which is engaged by the piston 10. Moreover, located in the bore 12 is a valve body 14 having a head 15. The head 15 is of larger diameter than the main portion of the valve body and it is urged by means of a coiled compression spring 16 into contact with a seating defined about an enlarged portion 17 of the bore 12. An annular space is defined between the valve body 14 and the enlarged portion 17 of the bore and this space communicates with a source 18 of liquid fuel. Moreover, formed in the body of the valve is a longitudinal passage 19 which communicates with the outlet 20.

The outlet 20 communicates with the fuel inlet of a fuel injection nozzle 21 which itself includes a spring loaded valve member 22 which controls the flow of fuel derived from the outlet 20, through outlet orifices 23 the latter in use, being open to the combustion chamber of the associated engine.

A cylinder 33 is provided and in this cylinder is located a pumping plunger 24 which is acted upon by means of a cam 25 which is driven at half engine speed and in timed relationship thereto. The cylinder communicates with the bore 11 by way of a non-return valve 35 located in a passage 34 and by way of a non-return valve 27 in a passage 26. with a source 28 of fuel under pressure.

The chamber of the injector 21 which contains the spring is preferably connected to a drain as also is an annular space defined between the piston 13 and the bore 11.

A branch passage 29 communicates with the bore 11 and can be placed in communication with a drain by means of a valve 30 which is closed by a valve operator in the form of an electromagnetic device 31. The valve is closed when a solenoid of the device is energised. The supply of electric current to the device 31 is controlled by a control circuit 31a to which as will be explained, are also fed signals representing engine speed, position, actual fuel quantity and the de manded fuel.

The parts of the apparatus are shown in the position they occupy during the delivery of fuel to the associated engine. The pump ing plunger 24 is being moved downwardly and the valve 30 is closed so that a high pressure exists in the space between the plunger 24 and the piston 10. The latter is therefore moving at a greater rate than the plunger 24 because its diameter is smaller than that of the plunger and similar move ment is being imparted to the piston 13. This latter piston displaces fuel from the bore 12 through the passage 19 to the outlet 20 and the high pressure at the outlet 20 is shown to have lifted the valve member of the injec tion nozzle away from its seating to permit fuel flow through the outlet orifices 23.

As the cam further rotates a position will be reached at which the piston 13 engages the body of the valve 14 to physically lift the head 15 of the valve away from the seating.

When this occurs the pressure at the outlet 20 falls and the valve member 22 of the injection nozzle moves onto its seating to prevent further flow of fuel through the outlet orifices. The surplus fuel displaced from the bore 12 flows to the source 18 and the surplus fuel displaced by the plunger 24 flows to drain through the port 36 when the latter has been uncovered by the piston 10.

After the inward movement of the plun ger 24 has ceased and the cam 25 has moved angularly fuel flows from the source 28 past the non-return valve 27 to intermediate the piston 10 and the plunger 24 and the latter is moved rearwardly to maintain e engagement with the cam. The valve 35 is set so that it cannot be opened by the pressure of fuel of the source 28.

Filling of the bore 12 with fuel takes place at any convenient time before the next delivery of fuel is required. To achieve filling, the valve 30 is opened to allow fuel flow from the source 18, between the head of the valve 14 and the seating, through the bore 19 in the valve and into the bore 12 thus displacing the pistons 13 and 10. The valve 14 is maintained in the open position because whilst the pistons move, the valve is not pressure balanced. The extent of move ment of these pistons is sensed by means of a sensing transducer 32 positioned about the piston 10. As soon as the signal from the sensing coil of the transducer indicates that the pistons 13 and 10 have moved in the opposite direction to the direction in which they move during fuel delivery by a suffi cient amount, the valve 30 is closed and the pressure in the portion of the bore 11 and cylinder between the piston 10 and the plunger 24 rises to a pressure which is above drain pressure and as a result the pressure in the bore 12 also rises. This increase in pressure permits the valve 14 to close so that no further fuel is admitted to the bore 12.

When the plunger 24 starts to move under the action of the cam and starts to generate a pressure intermediate the piston 10 and plunger 24, the valve 30 is opened and fuel flows from intermediate the plunger 24 and the piston. The point at which the valve 30 is opened may be varied with speed to ensure that the pressure between piston 10 and plunger 24 is high enough to prevent the pressure of fuel of the source 18 opening the valve 14 and pushing plungers 10 and 13 upwards. No movement of the piston 10 occurs until the valve 30 is closed. Thereafter the cycle of operation as described, is repeated.

It is possible to obtain pilot injection of fuel by momentarily closing the valve 30 sufficient to effect a small movement of the pistons 10 and 13.

It will be understood that the supply of electric current to the electromagnetic device 31 which controls the valve 30 must be carefully controlled and for this purpose the electronic control circuit is provided. Signals must also be supplied to the control circuit 31a for processing therein in addition to the signal provided by the sensing transducer 32. A signal is required indicative of the position of the cam 25 but since this is driven in timed relationship with the associated engine, a suitable signal may be obtained from the fly wheel or some other rotary part of the associated engine. This latter signal is also required so that the instant of the commencement of delivery of fuel takes place at the correct time and which is appropriate to various engine operating parameters such as the amount of fuel being supplied to the engine and the speed of the engine.In addition a signal must be provided to the control circuit which is indicative of the quantity of fuel it is desired to supply to the engine and the control system may be arranged so that the governing of the idling speed of the engine together with the maximum speed of the engine is obtained. Such a governor arrangement is termed in the art a "two-speed governor". It is also possible to arrange that the governor is of the type known in the art as an 'all speed" governor.

The system described uses an engine driven pump for generating the pressure which is required to effect injection but it has the advantage that the timing of the start of fuel delivery can be readily altered to suit particular engine operating parameters.

WHAT WE CLAIM IS: 1. A fuel injection pumping apparatus for supplying fuel to an injection nozzle of an internal combustion engine comprising piston means contained within a bore, an outlet from one end of the bore, said outlet in use communicating with an inlet of the nozzle, a fuel inlet to said one end of the bore connected in use to a source of fuel under pressure, a valve operable to prevent flow of fuel through said inlet during delivery of fuel through said outlet, a reciprocable plunger contained within a cylinder, cam means for urging the plunger towards one end of the cylinder, passage means connecting said one end of the cylinder with the other end of said bore whereby liquid displaced during movement of the plunger by the cam will act on said piston means to urge the piston to displace fuel through said outlet, a non-return valve in said passage means to prevent flow of liquid from said bore to said cylinder, a solenoid controlled valve operable to allow flow of liquid from the other end of said bore. a transducer for providing a signal indicative of the position of said piston means, a control circuit for controlling the operation of said valve, said control circuit receiving the signal from the transducer, first means for providing a signal to said control circuit indicative of the amount of fuel to be delivered to the engine and second means for providing an engine position and speed signal to said control circuit, whereby during movement of the plunger by the cam the valve is closed at a position to cause delivery of fuel at the desired time, and whereby during filling of the bore, the valve is closed when the piston means attains a position appropriate to the amount of fuel to be delivered to the engine.

2. An apparatus according to claim 1 including an inlet for liquid to said one end of the cylinder, a non-return valve in said inlet, said inlet in use being connected to a source of liquid under pressure, to urge the plunger into contact with the cam when the non-return valve in said passage means is closed.

3. An apparatus according to claim 1 or claim 2 including a spill port in the wall of said bore, said spill port being uncovered by said piston means at a predetermined position during the movement of the piston means towards said one end of the bore.

4. A fuel injection pumping apparatus comprising the combination and arrangement of parts substantially as herein before described with reference to the accompanying drawing.

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

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. drain pressure and as a result the pressure in the bore 12 also rises. This increase in pressure permits the valve 14 to close so that no further fuel is admitted to the bore 12. When the plunger 24 starts to move under the action of the cam and starts to generate a pressure intermediate the piston 10 and plunger 24, the valve 30 is opened and fuel flows from intermediate the plunger 24 and the piston. The point at which the valve 30 is opened may be varied with speed to ensure that the pressure between piston 10 and plunger 24 is high enough to prevent the pressure of fuel of the source 18 opening the valve 14 and pushing plungers 10 and 13 upwards. No movement of the piston 10 occurs until the valve 30 is closed. Thereafter the cycle of operation as described, is repeated. It is possible to obtain pilot injection of fuel by momentarily closing the valve 30 sufficient to effect a small movement of the pistons 10 and 13. It will be understood that the supply of electric current to the electromagnetic device 31 which controls the valve 30 must be carefully controlled and for this purpose the electronic control circuit is provided. Signals must also be supplied to the control circuit 31a for processing therein in addition to the signal provided by the sensing transducer 32. A signal is required indicative of the position of the cam 25 but since this is driven in timed relationship with the associated engine, a suitable signal may be obtained from the fly wheel or some other rotary part of the associated engine. This latter signal is also required so that the instant of the commencement of delivery of fuel takes place at the correct time and which is appropriate to various engine operating parameters such as the amount of fuel being supplied to the engine and the speed of the engine.In addition a signal must be provided to the control circuit which is indicative of the quantity of fuel it is desired to supply to the engine and the control system may be arranged so that the governing of the idling speed of the engine together with the maximum speed of the engine is obtained. Such a governor arrangement is termed in the art a "two-speed governor". It is also possible to arrange that the governor is of the type known in the art as an 'all speed" governor. The system described uses an engine driven pump for generating the pressure which is required to effect injection but it has the advantage that the timing of the start of fuel delivery can be readily altered to suit particular engine operating parameters. WHAT WE CLAIM IS:

1. A fuel injection pumping apparatus for supplying fuel to an injection nozzle of an internal combustion engine comprising piston means contained within a bore, an outlet from one end of the bore, said outlet in use communicating with an inlet of the nozzle, a fuel inlet to said one end of the bore connected in use to a source of fuel under pressure, a valve operable to prevent flow of fuel through said inlet during delivery of fuel through said outlet, a reciprocable plunger contained within a cylinder, cam means for urging the plunger towards one end of the cylinder, passage means connecting said one end of the cylinder with the other end of said bore whereby liquid displaced during movement of the plunger by the cam will act on said piston means to urge the piston to displace fuel through said outlet, a non-return valve in said passage means to prevent flow of liquid from said bore to said cylinder, a solenoid controlled valve operable to allow flow of liquid from the other end of said bore. a transducer for providing a signal indicative of the position of said piston means, a control circuit for controlling the operation of said valve, said control circuit receiving the signal from the transducer, first means for providing a signal to said control circuit indicative of the amount of fuel to be delivered to the engine and second means for providing an engine position and speed signal to said control circuit, whereby during movement of the plunger by the cam the valve is closed at a position to cause delivery of fuel at the desired time, and whereby during filling of the bore, the valve is closed when the piston means attains a position appropriate to the amount of fuel to be delivered to the engine.

2. An apparatus according to claim 1 including an inlet for liquid to said one end of the cylinder, a non-return valve in said inlet, said inlet in use being connected to a source of liquid under pressure, to urge the plunger into contact with the cam when the non-return valve in said passage means is closed.

3. An apparatus according to claim 1 or claim 2 including a spill port in the wall of said bore, said spill port being uncovered by said piston means at a predetermined position during the movement of the piston means towards said one end of the bore.

4. A fuel injection pumping apparatus comprising the combination and arrangement of parts substantially as herein before described with reference to the accompanying drawing.