GB1244727A - Liquid fuel injection pumping apparatus - Google Patents

Abstract

1,244,727. Fuel injection pumps. C.A.V. Ltd. Dec.2, 1968 [Dec.8, 1967], No.55857/67. Heading F1A. [Also in Division G3] A liquid fuel injection pumping apparatus comprises an injection pump 1 which is operated by a cam rotatable by a shaft 70 supplying fuel through an accumulator 3, a rotatable distributer member 44 which has a delivery passage 12 which registers in turn and as the distributer rotates with four outlet ports 14, and four feed passages 76 which register with a feed port 10. There are also provided four relief passages 13 registering in turn with a relief port 15. A predetermined quantity of fuel is delivered by the pump 1 to the accumulator 3 and the pressure causes the valve member 4 to be raised to establish communication between ports 5, 8 and fuel flows to an outlet port 14 via the delivery passage 12 and a feed passage 76. Injection of fuel continues until the pressure within the accumulator 3 has fallen and the valve member 4 lowers to close port 8 and place the outlet port 14 in communication with the constant pressure valve 17 via relief passages 13, port 15 and the groove formed between lauds D, E. The quantity of fuel delivered is hence dependant upon the effective stroke of the pump 1. The outer ends of the feed passages 76 are formed as helically disposed grooves 11 of varying depth as shown in Fig. 2 and which in conjunction with port 10 forms a variable orifice to apply a differential pressure to a pressure control valve 47 to control the initial rate of injection of fuel. Movement of the rack bar 19 effects angular adjustment of the plunger 1, and hence varies the quantity of fuel injected, and imparts axial movement to the shaft 25. Valve member 28 is slidable axially relative to the shaft 25 and is biased by a coil spring against the action of centrifugally operable weights 26. Liquid pressure supplied by a constant pressure source 35 is applied via pipe 45 to one end of the distributer member to alter its axial setting and hence the timing. This pressure is made speed dependant as a result of the action of the governor weights on the valve member 28. Pressure is also applied to the other end of the distributer which is load dependant. The pressure in the pipe 45 also controls a piston 21 which modifies the maximum delivery of fuel by the pump 1.