Patent GB-872053-A (GB)
Title: Improvements in self-regulating reciprocating pumps, and in particular in fuel injection pumps for internal combustion engines
IPC: F02M59/32
Filed: 1957-09-17
Abstract: 872,053. Fuel injection pumps. BESSIERE, P. E. Sept. 17, 1957 [Oct. 3, 1956 ; Nov. 6, 1956 ; Jan. 3, 1957 ; Jan. 10, 1957 ; Aug. 9, 1957], No. 29268/57. Class 102(1). A fuel injection pump includes a reciprocating piston 5 acting as a means for regulating the pump delivery, the piston being moved upwards against spring pressure 6 by the fuel delivered by the main piston or a diaphragm 2 of the pump until the piston 5 opens a bypass 17 to end the pump delivery. During the suction stroke of the main piston the piston 5 moves under the action of the spring to drive fuel through a throttled conduit 9 which includes a slide valve 12 moved to close the conduit 9 at the beginning of the delivery stroke of the main piston and which moves to open the conduit 9 during the suction stroke under the control of a throttle H whereby this movement of the slide valve is braked. When the speed of the main piston exceeds a predetermined value the piston 5 or both the slide valve 12 and the piston do not complete their downward stroke thereby reducing the quantity of fuel delivered by the pump. In the embodiment shown in Fig. 1, the piston 2 first delivers fuel past non-return valve E to move the valve 12 to close conduit 9 and then delivers the fuel past non-return valve 11 to actuate the piston 5 whereby fuel in an upper chamber 7b is delivered through outlet 15. During the suction stroke of the main piston 2 the piston 5 first moves to close the by-pass 17 and is then held in this position until the slide valve 12, moving downwards under the control of throttle H, opens the conduit 9. The piston 5 then moves downwards transferring the fuel from chamber 7a through conduit 9 to chamber 7b under the control of throttle 8. In a modification the slide valve may open a passage by-passing the throttle H when the valve is about to open the conduit 9 thus providing a sudden opening of this conduit. In a further modification the throttle 8 may be omitted, the groove in the valve 12 providing the throttle in the conduit 9. To avoid any possible suction effect on the return movement of the valve 12 the fuel passing through the throttle H may be returned to the fuel tank instead of the main cylinder 1. Further the slide valve may be controlled by a separate piston moving in synchronism with the main piston or may be actuated by a fluid pressure supply controlled by grooves on the main piston. In a further modification fuel may be fed direct to the chamber 7b through a branch conduit leading from the inlet 4 and contain a non-return valve. In a modified form of pump, Fig 4, the main piston 2 delivers fuel directly to the outlet 15 through conduits 10, 27 containing a throttle 28 until the piston 5 opens the by-pass 17. The slide valve A is controlled as before by conduit H and the piston 5 returns the fuel in chamber 7a through conduit 9 and throttle 8 to the main cylinder 1. The fuel from the chamber 7a and/or the fuel delivered by the valve past throttle H may be led to the fuel tank instead of the main cylinder 1 to avoid suction effects. In Fig. 12 the pump is of a similar type to that shown in Fig. 1, but the valve 12 is actuated mechanically through a cam 74 and push rod 75 to close the conduit 9 at the beginning of the delivery stroke of the main piston 2. The slide valve 12 is connected to a piston member 77 which during the closing movement of the valve 12 opens a liquid pressure supply line 79. During the suction stroke of the piston 2 the push rod 75 moves from the valve 12 which moves to open the conduit 9 under the effect of flow of liquid past the throttle H, the opening of the conduit by the valve providing the necessary throttling of the conduit 9. Specifications 861,754 and 872,055 are referred to.