Patent GB-904518-A (GB)
Title: Improvements in self-regulating reciprocating pumps, in particular for the injectionof fuel into internal combustion engines
IPC: F02M59/36
Filed: 1959-05-06
Abstract: 904,518. Fuel injection pumps. BESSIERE, P. E. May 6, 1959 [May 9, 1958; Aug. 14, 1958], No. 15592/59. Class 102(1). A fuel-injection pump is provided with a by-pass conduit which is opened and closed by a shuttle piston acting as a slide valve in which the shuttle piston is moved in one direction against a resilient force by liquid delivered by an auxiliary pump, in synchronism with the injection pump, and then the shuttle piston is returned by the resilient force it delivers liquid through a throttled outflow conduit. In Fig. 1 the main piston 2 reciprocates in a cylinder 1 and receives fuel from a supply pump through conduit 4 and delivers the fuel to the engine cylinders through a delivery conduit 5. An auxiliary piston 2a working in cylinder la delivers liquid through a conduit 18 to chamber 16 to move the shuttle piston 8-8a against a spring load 10 until the portion 8a opens a discharge conduit 20 in which position the by-pass conduit 7 leading from the main pumping chamber 1 is opened by the portion 8 and injection ceases. The chamber 11 above the piston 8 is also fed from the feed pump through the conduit 12. On the return stroke of the pistons 2 and 2a the shuttle piston 8-8a is moved by the spring 10 and the fuel in chamber 11 is forced past a throttled passage 13 which brakes the return movement such that when the speed of the pump increases above a predetermined valve the shuttle piston does not complete its return stroke before it is again moved by the liquid from the auxiliary pump, thus the quantity of fuel subsequently injected is reduced as the speed further increases. In a modification shown in Fig. 3 the auxiliary piston 2a delivers liquid past a non-return valve 24 to the chamber 23 to actuate the shuttle piston 8 and on the return stroke the piston 8 is braked by the delivery of liquid from chamber 23, through conduit 12 containing the throttled passage 13, to the auxiliary cylinder 1a. The throttled passage 13 may be varied in accordance with engine speed by a governor 28 or by manual control. The shuttle piston 8 formed with a groove 25 may be provided with an oblique edge portion 41 such that rotation of the shuttle piston varies the distance the piston has to be moved to open the by-pass conduits 7. When the delivery from the chamber 23 is to an outside source a valve is provided in the conduit 12 which is closed during the delivery strokes of the pistons. The invention may also be applied to pump where the piston 2 Fig. 4 rotates and reciprocates and delivers fuel to separate delivery conduits 5. The piston is provided with grooves 13, 39 which connect the auxiliary chamber 1a to the combined conduits 12, 18 leading to the chamber 23, the groove 13 acts as the throttled passage when the shuttle piston is returning the liquid from the chamber 23 to the auxiliary cylinder 1a. Instead of the one discharge passage 20 provided on the above pumps, this discharge passage may be arranged as two passages the first of which is throttled so that at low speeds all the delivery from the auxiliary pump is discharged before the by-pass is opened. Such an arrangement may be provided by a second throttled conduit opened before the conduit 20 or by a bottom portion of the shuttle piston being of reduced diameter which connects the chamber 23 to the conduit 20 through the gap between this portion and the cylinder.