US3116728A

US3116728A - Liquid fuel pumps

Info

Publication number: US3116728A
Application number: US249751A
Authority: US
Inventors: Evans Fraser Mackie
Original assignee: CAV Ltd
Current assignee: CAV Ltd
Priority date: 1963-01-07
Filing date: 1963-01-07
Publication date: 1964-01-07
Anticipated expiration: 1981-01-07

Description

Jan. 7, 1964 F. M. EVANS 3,116,728

LIQUID FUEL PUMPS Filed Jan. 7, 1963 /8 Fig-2 United States Patent 3,116,728 LIQUID FUEL PUMPS Fraser Mackie Evans, Uxbridge, England, assignor to (LAN. Limited, London, England Filed Jan. 7, 1963, Ser. No. 249,751 2 Claims. (Cl. 123139) This invention relates to liquid fuel pumps for internal combustion engines, and of the kind comprising in combination a rotary distributor adapted to be driven by the engine, a rotor at one end of the distributor, said rotor having therein a transversely extending bore, at least one plunger in the bore, means for feeding fuel intermittently as the distributor rotates to the bore in the rotor so as to move the plunger outwardly, an annular cam surrounding the rotor and adapted to impart inward movements to the plunger as the rotor rotates and thereby deliver fuel through the distributor to the engine cylinders in turn, and a fluid operable piston for imparting angular movements to the cam to vary the timing of the delivery of fuel to the engine.

The object of the invention is to provide such a pump in an improved form.

According to the invention, a pump of the kind specified comprises in combination a cylindrical chamber extending parallel to a tangent to the annular cam and accommodating the fluid operable piston, a passage in the piston through which liquid at a pressure dependent on the speed of the engine can flow to and from one end of the chamber, a spring urging the piston towards said one end of the chamber, a valve for controlling the flow of liquid through said passage, said valve being arranged to be urged towards an open position by the pressure of liquid flowing to or from said one end of the chamber, a radial arm on the annular cam extending into a space in the piston adjacent a part of, or adapted to act on, the closure member of the valve, the arrangement being such that in operation the reaction on the annular cam during its actuation of the plunger will cause the valve to be closed, and thereby form a hydraulic lock in said one end of the chamber to resist angular movement of the cam.

In the accompanying drawings:

FIGURE 1 is a part sectional side elevation of a liquid fuel pump to which the invention is applied and FIGURE 2 is a sectional end elevation on the line 22 of FIGURE 1.

Referring to the drawings there is provided a body part 1 which at one end contains a feed pump 2 of the kind comprising a rotary impeller provided with vanes. The inlet 2 and outlet 2 of the pump 2 are interconnected through a relief valve 3 which regulates the feed pressure in a manner dependent on the speed of this pump. At the other end of the body part is contained the fuel injection pump comprising a rotary head 4 formed at one end of a distributor 5 serving to interconnect the rotary parts of the feed and injection pumps. In the head is a transverse bore 6 containing a pair of reciprocatory plungers 7 which through rollers 8 at their outer ends co-operate with a surrounding annular cam 9.

Fuel from the feed pump 2 is fed through a passage 10 in the body part to an annular groove 11 in the periphery of the distributor 5 and thence by way of a throttle valve 12 to a passage 13 in the body part which registers in turn, as the distributor rotates, with a plurality of radially disposed passages 14 in the distributor. The passages 14 are in communication with an axial passage 15 in the distributor which opens at one end into the bore 6. Also leading from the axial passage 15 is a radial passage 16 which is adapted to register in turn, as the distributor rotates with a plurality of ports 17, in the body part which are adapted for connection to the injection nozzles (not shown) of the engine cylinders.

3,116,728 Patented Jan. 7, 1964 The pump so far described is well known and operates in the following manner. Fuel from the feed pump 2 is fed intermittently by way of the throttle valve 12 to the axial passage 15 and thus serves to move the plungers 7 of the injection pump outwardly. At appropriate instants in the cycle the plungers are moved inwardly by the action of the cam 9, and thereby serve to discharge fuel in turn to the engine cylinders.

In applying the present invention to a pump as above described, a cylindrical chamber 18 is formed in the body part adjacent the injection pump with its axis extending parallel to a tangent to the annular cam 9. In the chamber is a piston 19 which is loaded towards one end of the chamber by means of a coiled compression spring 20 interposed between the other end of the chamber and an abutment in the form of a disc 21 which is located against an annular shoulder 22 within a hollow part 19* of the piston, into which the spring extends. In the other end of the piston there is a stepped cylindrical axial bore 23, the narrower part of which is in communication with a space at the end of the chamber towards which the piston is loaded by the spring. The bore contains a valve closure member in the form of a stepped cylindrical piston 24, the narrower end of which is conical and can seat against a complementary shoulder between the wider and narrower parts of the bore to prevent flow of liquid between the bore and the adjacent end of the chamber. The annular space 25 surrounding the narrower part of the valve member is connected to the outlet of the feed pump 2 through passages 25 25 in the piston and the wall of the chamber respectively, so that the pressure of fuel in the annular space will act on the annular shoulder between the two parts of the valve member 24 so as to urge the latter towards an open position.

On the periphery of the annular cam is a radial arm 26 which projects laterally through a gap in the piston wall into a space between the abutment 21 and a thrust pad 27 on the wider end of the valve member 24, which projects into the hollow part of the piston. The freedom of movement of the radial arm 26 between the abutment 21 and thrust pad 27 when the valve member 24 is closed is sufficient to allow the valve member to be opened, but small enough to restrict the angular movement of the annular cam, caused by opening of the valve member, to tolerable limits.

When the pump is in operation, the plungers 7 exert a torque on the annular cam during the injection strokes. This causes the radial arm 26 to move the valve member 24 into its closed position, thus forming a hydraulic lock in the end of the chamber so that further movement of the annular cam during the injection strokes is prevented. Between the injection strokes the torque on the annular cam is negligible and the valve member v24 is moved to an open position by the pressure of fuel in the annular space 25. If the engine speed is increasing, the pressure in the annular space just before the valve member opens will be greater than the pressure in the adjacent end of the chamber. Consequently, when the valve opens, fuel will flow into the said end of the chamber and move the piston 19 axially against the action of the spring 20 and the annular cam 9 will be moved angularly so as to advance the timing of the injection strokes. If, on the other hand, the engine speed is falling, the pressure in the annular space 25 just before the valve member opens will be less than the pressure in the adjacent end of the chamber and the piston 19 will be urged by the spring 20 in the other direction so as to retard the timing of the injection strokes, the fuel in the end of the chamber escaping into the annular space during this movement and thence through the

passages

25, 25 in the piston and the wall of the chamber respectively to the outlet of the feed pump.

Having thus described -my invention what I claim as new and desire to secure by Letters Patent is:

l. A liquid fuel injection pump for supplying fuel to an internal combustion engine, comprising in combination a body in which is formed a cylindrical bore, a plurality of equi-angulari spaced fuel delivery ports in said body in communication with said bore, a fuel inlet port in said body in communication with the bore at a point axially spaced from said delivery ports, a rotary distributor in said bore, a longitudinal passage in said distributor, a plurality of equi-angularly spaced fuel inlet passages extending outwardly from said longitudinal passage for registering in turn with the fuel inlet passage as the distributor rotates, a delivery passage extending outwardly from said longitudinal passage for registering in turn, as the distributor rotates, with said delivery ports during at least a part of the period when said inlet port is out of register with one of said inlet passages, a rotor at one end of the distributor and rotatable therewith, a transverse bore in said rotor, said bore communicating with said longitudinal passage, at least one plunger in said bore, an annular cam surrounding therotor for imparting inward movements to the plunger as the rotor rotates, means for supplying fuel at a pressure dependent upon the speed of rotation of the distributor to said inlet port for moving the plunger outwardly as permitted by the cam when the inlet port is in register with one of said inlet passages, a cylindrical chamber in the 'body, the axis of said chamber extending parallel to a tangent to the annular cam, a piston slidable in said chamber, a projection on said cam engaging the piston whereby axial movement of the piston will impart angular movement to the cam, to vary the angular positions of the rotor at which inward movements are imparted to the plunger, passage means in the piston connecting one end of the chamber with said fuel supply means, a spring urging said piston towards said one end of the chamber, and valve means for controlling the flow of fuel through said passage means said valve being urged towards an open position by fuel flowing to and from said one end of the chamber, said projection acting on said valve means to interrupt communication between said end of the chamber and said fuel supply means as a result of the reaction on the cam during inward movements of the plunger.

2. A liquid fuel injection pump for supplying fuel to an internal combustion engine, comprising in combination a body in which is formed a cylindrical bore, a plurality of equi-angularly spaced fuel delivery ports in said body in communication with said bore, a fuel inlet port in said body in communication with the bore at a point axially spaced from said delivery ports, a rotary distributor in said bore, a longitudinal passage in said distributor, a plurality of equi-ang-ularly spaced fuel inlet passages extending outwardly from said longitudinal passage for registering in turn with the fuel inlet passage as the distributor rotates, a delivery passage extending outwardly from said longitudinal passage for registering in turn, as the distributor rotates, with said delivery ports during at least a part of the period when said inlet port is out of register with one of said inlet passages, a rotor at one end of the distributor and rotatable therewith, a transverse bore in said rotor, said bore communicating with said longitudinal passage, at least one plunger in said bore, an annular cam surrounding the rotor for imparting inward movements to the plunger as the rotor rotates, a feed pump at the other end of the rotor, said feed pump having an inlet in the body, a feed pump outlet in the body in communication with said inlet port, a relief valve interconnecting the inlet and outlet of the pump whereby the pressure of fuel at said feed pump outlet will be dependent upon the speed of rotation of the feed pump, a cylindrical chamber in the body, the axis of said chamber extending parallel to a tangent to the annular cam, a piston slidable in said chamber, a projection on said cam engaging the piston whereby axial movement of the piston will impart angular movement to the cam, to vary the angular positions of the rotor at which inward movements are imparted to the plunger, passage means in the piston connecting one end of the chamber with said fuel supply means, a spring urging said piston towards said one end of the chamber, an axial bore in said piston forming part of said passage means, a seating in the bore, a valve member slidablc in said bore, said valve member being shaped to co-operate with said seating, said valve member being urged towards an open position by fuel flowing into and out of said chamber, said projection acting on said valve member to interrupt communication between said end of the chamber and said fuel supply means as a result of the reaction on the annular cam during inward movement of the plunger.

No references cited.

Claims

1. A LIQUID FUEL INJECTION PUMP FOR SUPPLYING FUEL TO AN INTERNAL COMBUSTION ENGINE, COMPRISING IN COMBINATION A BODY IN WHICH IS FORMED A CYLINDRICAL BORE, A PLURALITY OF EQUI-ANGULARLY SPACED FUEL DELIVERY PORTS IN SAID BODY IN COMMUNICATION WITH SAID BORE, A FUEL INLET PORT IN SAID BODY IN COMMUNICATION WITH THE BORE AT A POINT AXIALLY SPACED FROM SAID DELIVERY PORTS, A ROTARY DISTRIBUTOR IN SAID BORE, A LONGITUDINAL PASSAGE IN SAID DISTRIBUTOR, A PLURALITY OF EQUI-ANGULARLY SPACED FUEL INLET PASSAGES EXTENDING OUTWARDLY FROM SAID LONGITUDINAL PASSAGE FOR REGISTERING IN TURN WITH THE FUEL INLET PASSAGE AS THE DISTRIBUTOR ROTATES, A DELIVERY PASSAGE EXTENDING OUTWARDLY FROM SAID LONGITUDINAL PASSAGE FOR REGISTERING IN TURN, AS THE DISTRIBUTOR ROTATES, WITH SAID DELIVERY PORTS DURING AT LEAST A PART OF THE PERIOD WHEN SAID INLET PORT IS OUT OF REGISTER WITH ONE OF SAID INLET PASSAGES, A ROTOR AT ONE END OF THE DISTRIBUTOR AND ROTATABLE THEREWITH, A TRANSVERSE BORE IN SAID ROTOR, SAID BORE COMMUNICATING WITH SAID LONGITUDINAL PASSAGE, AT LEAST ONE PLUNGER IN SAID BORE, AN ANNULAR CAM SURROUNDING THE ROTOR FOR IMPARTING INWARD MOVEMENTS TO THE PLUNGER AS THE ROTOR ROTATES, MEANS FOR SUPPLYING FUEL AT A PRESSURE DEPENDENT UPON THE SPEED OF ROTATION OF THE DISTRIBUTOR TO SAID INLET PORT FOR MOVING THE PLUNGER OUTWARDLY AS PERMITTED BY THE CAM WHEN THE INLET PORT IS IN REGISTER WITH ONE OF SAID INLET PASSAGES, A CYLINDRICAL CHAMBER IN THE BODY, THE AXIS OF SAID CHAMBER EXTENDING PARALLEL TO A TANGENT TO THE ANNULAR CAM, A PISTON SLIDABLE IN SAID CHAMBER, A PROJECTION ON SAID CAM ENGAGING THE PISTON WHEREBY AXIAL MOVEMENT OF THE PISTON WILL IMPART ANGULAR MOVEMENT TO THE CAM, TO VARY THE ANGULAR POSITIONS OF THE ROTOR AT WHICH INWARD MOVEMENTS ARE IMPARTED TO THE PLUNGER, PASSAGE MEANS IN THE PISTON CONNECTING ONE END OF THE CHAMBER WITH SAID FUEL SUPPLY MEANS, A SPRING URGING SAID PISTON TOWARDS SAID ONE END OF THE CHAMBER, AND VALVE MEANS FOR CONTROLLING THE FLOW OF FUEL THROUGH SAID PASSAGE MEANS SAID VALVE BEING URGED TOWARDS AN OPEN POSITION BY FUEL FLOWING TO AND FROM SAID ONE END OF THE CHAMBER, SAID PROJECTION ACTING ON SAID VALVE MEANS TO INTERRUPT COMMUNICATION BETWEEN SAID END OF THE CHAMBER AND SAID FUEL SUPPLY MEANS AS A RESULT OF THE REACTION ON THE CAM DURING INWARD MOVEMENTS OF THE PLUNGER.