Patent GB-669762-A (GB)
Title: Improvements in piston pumps for the injection of fuel into internal combustion engines
IPC: F02M59/00
Filed: 1949-04-12
Abstract: 669,762. Fuel-injection pumps. PRECISION MECANIQUE. April 12, 1949 [April 14, 1948; Dec. 18, 1948; March 17, 1949], Nos. 9927/49, 9928/49 and 9929/49. Class 102 (i) In a fuel injection pump in which a speed regulating valve member 2, disposed in the delivery passage, is movable in a bore 3 against the action of a spring 6 and has at least one longitudinal channel 81, for the passage of fuel ; the end of the channel co-operates with a regulating surface 10 in the bore, and the valve member is angularly adjustable about its axis for varying the cross sectional flow area at the end of the channel whereby the speed above which the member tends. to move along the bore, to cause a reduction in delivery by a sucking back action, can be varied. The valve member is rotatable by an arm 15 and has a head 5 co-operating with a seat 7 on a member 26 in which the bore and regulating surface are formed. The channel 81 extends to the valve head and is used at starting to provide excess fuel whilst a second channel 8 of different axial spacing is used for normal running. The leading edge of the plunger 1 closes an inlet port 17 to commence delivery past the valve 2 to a chamber 9 which communicates through passages 20, 21 and a groove in the plunger with an outlet 22. A groove 18 in the plunger, communicating with the pump chamber 4 through a bore 18 degrees, uncovers the inlet port to terminate injection and on the return stroke a quantity of fuel delivered past the valve 2 is sucked back into the pump chamber before the head 5 closes. The leading edge and the groove 18 may be formed obliquely to the axis of the plunger and the latter may then be rotatable for varying the delivery and timing. A separate spill port may be used to prevent turbulence, and this port may be put in communication with the passage 20, which may have a check valve, at the end of the delivery stroke to prevent dribbling. The plunger is actuated by a cam 19 which may be designed to effect a rapid plunger acceleration and uniform injection stroke. In another embodiment, Fig. 3, the valve member is adjustable axially relative to its head for varying the axial opening h of the channels. In a a further embodiment, Fig. 4, the valve member 2 carries a ball 24 seating on an orifice 25. The regulating surface 10 may be varied relatively to the lower end of the channels by using different thicknesses of packing 13 or by using an elastic packing which may be more or less compressed by a screw cap 29, Fig. 1. In other embodiments the channels 8, 81 may be of identical axial spacing but of different depths, and they may have a varying cross section throughout their lengths. The member 26 may have both upper and lower oblique regulating surfaces or the latter may be of other shapes, e.g., curvilinear. Specifications 490,547, 496,967, 523,163, 634,085 and 669,761 are referred to. The Specification as open to inspection under Sect. 91 describes a pump in which the regulating valve is in the form of a non-adjustable accumulator piston and in which the delivery and spill passages are arranged to prevent a parasitic injection. This subject-matter does not appear in the Specification as accepted.