Patent GB-840527-A (GB)
Title: Improvements in or relating to reciprocating action liquid pumps, for example, fuel injection pumps
IPC: F02M59/36
Filed: 1957-11-18
Abstract: 840,527. Fuel injection pumps. BESSIERE, P. E. Nov. 18, 1957 [Nov. 29, 1956], No. 35883/57. Class 102(1). A fuel injection pump comprises a regulating member arranged to be displaced in a chamber against the action of a return force by a stream of fuel fed through the chamber at a speed proportional to the speed of the pump, the internal cross-sectional area of the chamber being greater than the cross-sectional area of the regulating member and wherein an abutment is provided to arrest the movement of the member through the chamber, such arrest causing an interruption of the flow through the chamber, whereby the delivery of the pump is reduced in proportion to the reduction in the lag of the speed of the member behind the flow of liquid. In the embodiment shown in Fig. 1, a piston 2 working in a cylinder 1 delivers fuel through a chamber 7 and conduit 14 to the outlet conduit 5. The regulating member is in the form of a ball 8 which is moved upward by the delivery of the piston 2 against the return force of gravity until the ball contacts seat 13 which ends the delivery to the injectors. If at this stage the piston 2 has not completed its upward stroke, the excess delivery is absorbed by movement of a spring loaded piston 18. On the suction stroke of the piston 2 excess fuel absorbed by movement of the piston 8 is drawn into the cylinder and the ball 8 returns under gravity, the chamber 7 remaining filled with fuel. As the speed of the piston 2 increases so will the time taken for the ball 8 to reach its upper seat 13 decreases and hence the quantity of fuel delivered is decreased. Further since the time taken for the ball 8 to return under gravity is constant a speed of the piston can be reached where the delivery stroke of the piston 2 commences before the ball 8 has returned to its seat 10, thus providing an additional regulation effect. The ball 8 may be also under the action of a spring, and the chamber 7 may be tapered to increase the speed of the ball as it approaches the upper seat 13. The speed of the ball may be varied by a second passage leading from the cylinder to the upper part of the chamber 7, this passage being provided with an adjustable throttle as in Fig. 3 (not shown). The excess delivery of the piston 2 may be by-passed back to the supply tank. In the embodiment shown in Fig. 6, the regulating member 8d controls the quantity of fuel delivered to the pumping chamber 39a of the pump. A piston 2 working in a cylinder 1 delivers fuel through conduits 42, 41, 44, past non-return valve 45 to chamber 7d and hence to the pumping chamber 39a until the ball 8d contacts the seat 13d to interrupt the flow through the chamber 7d. The remainder of the delivery of piston 2 then acts on a piston 40 to deliver the fuel in the chamber 39a until this piston opens the by-pass conduit 43. The quantity of fuel fed to the chamber 39a is a function of the speed of the piston 2 as described above. On the suction stroke of the piston 2 the valve 45 remains closed and the fuel in the chamber 39b below the piston 40 is returned to the cylinder 1. To vary the speed of the ball 8d a valve 49 may be provided which throttles the conduit 44 and a conduit 48. This valve may also provide excess fuel for stating by opening conduit 48 and closing conduit 44. Further by positioning the valve to close conduits 44 and 48 and at the same time closing the communication between conduits 41, 42 no fuel is delivered by the pump the delivery from the piston 2 being past non-return valve 53 to the by-pass conduit 43. In a modified form the regulating member may be in the piston 40, as in Figs. 7 and 8 (not shown). Fig. 9 shows an alternative form of regulating member 60 provided at each end with conical portions 61, 62 co-operating with seats 63, 64. The member 60 is provided with longitudinal grooves 65 to provide the necessary difference in cross-sectional area between the member 60 and the cylinder 7.