GB764618A - Improvements in fuel injection pumps for internal combustion engines - Google Patents

Abstract

764,618. Starting direct-injection engines. BOSCH GES., R. Oct 19, 1954 [Nov. 17, 1953]. No. 30019/54. Class 7 (3). [Also in Group XXVIII] In a fuel injection pump having a spring- loaded accumulator piston 10 which, during the delivery stroke of the plunger 5, is forced upwards and displaces fuel from a space 42 through an aperture 40 into a fuel supply chamber 25, the aperture 40 is closed at starting speeds by a spring-loaded valve member 46 to prevent the accumulator piston rising, whereby the pump delivers at starting a quantity of fuel exceeding the normal full load supply. Fuel is supplied by a supply pump 26 to the chamber 25 which is connected to the pump inlet port 8 and, through a non-return valve 22, to the space 42 above the accumulator piston 10. At normal running the pressure in the space 25 is sufficient to force the member 46 down against its loading spring 31 to uncover the escape port 40 leading to space 42 and the pump spill port 9 which is connected to the fuel tank 44. The pump 26 supplies excess fuel to the chamber 25, the excess escaping through a bore 34 in the valve 46 which, when the valve is in its normal running position, is connected directly to an escape port 45 by a port 37. During starting the pressure in chamber 25 is insufficient to depress the valve 46 which rises to the position shown, blocking the ports 40, 9, whereby a full charge of fuel exceeding the full-load charge is delivered on each pump stroke. In the raised position of the valve 46, the excess fuel escape bore 34 in the valve is connected to the escape port 45 by a port 36 to which the fuel flows through a restricted orifice 35 in the bore 34. When the engine speed rises after starting, the increased supply from the pump 26 to the space 25 produces, due to the orifice 35, a rise in pressure in the space 25 which forces the valve down to its normal running position.