GB978116A - Liquid fuel injection pumps for internal combustion engines - Google Patents

Abstract

978,116. Fuel-injection pumps. C.A.V. Ltd. July 26, 1963 [Aug. 2, 1962], No. 29698/62. Heading F1A. [Also in Division G3] In a combined fuel-injection pump and distributer comprising a revolving distributer shaft 7 housing opposed pumping pistons 9 supplied by a feed pump 2 via a metering piston 22 and engaging a cam track 11, injection timing is controlled by angular adjustment of cam track 11 by a piston 29 subjected to the feed pump output pressure controlled by a valve 34 which is axially movable by the manually or governor-controlled pump output regulating member 26. In the embodiment of Fig. 1, valve 34 controls a port 37 communicating with a passage 33 feeding control piston 29, the lower side of valve 34 being subjected to the feed pump output pressure via a distributer groove 19. A passage 38 connects the valve chamber to the feed pump inlet. In operation, movement of regulating member 26 to reduce the quantity of fuel delivered, moves abutment 35 to reduce the spring force on valve 34 so that the valve is raised by the feed pump output pressure to uncover port 37 to connect feed pump pressure to piston 29 to alter the timing. As the pressure on the upper side of valve 34 increases, the valve is moved back to cover port 37. In the embodiment of Fig. 6, a stepped valve member 40, having a restricted throughpassage 40a, controls a spill port 41 so that the combined force due to spring 36 and the timing control piston-actuating pressure acting on the wider end of valve 40 is balanced by the feed pump output pressure acting on the narrower end of the valve. In the embodiment of Fig. 7, valve 42 has a restricted passage 43 and controls a spill port 44, as in the Fig. 6 embodiment. In the embodiment of Fig. 8, valve chamber 32 has a baffle 46 with a restricted orifice 47, and valve 45 controls a port 48 communicating with passage 38, so that the valve is subjected to the timing piston-actuating pressure only. In the embodiment of Fig. 10, the valve has a central land controlling a port 56 communicating with timing piston 29 and the space beneath the valve, and has grooves communicating with the feed pump outlet and inlet via passages 57 and 58, respectively. The upper end of the valve is connected to the feed pump inlet and is biased by a spring 60. In this embodiment, regulating member 26 is replaced by a plunger 50 having cam surfaces 54, 55 controlling metering piston 22 and the valve, and movable by the feed pump pressure acting against a manually adjustable spring 52.