GB781677A - Improvements in or relating to fuel injection pumps for internal combustion engines - Google Patents

Abstract

781,677. Starting direct injection engines. BOSCH GES., R. Dec. 9, 1955 [Dec. 11, 1954], No. 35341/55. Addition to 764,618. Class 7(3) [Also in Group XXVIII] A fuel injection pump is provided with a spring-loaded accumulator piston 10 subjected to the pressure of fuel in a space 42 connected to the delivery pipe 59 of a fuel supply pump 51 and provided with a relief aperture 61 which is throttled at starting speeds, whereby the pressure in space 42 prevents the piston 10 lifting so that excess fuel is provided for starting, and is opened by the delivery pressure of the supply pump 51 at normal running speeds. The aperture 61 is controlled by a ball valve 62 actuated by a spring-loaded control member 64 provided with a throttling aperture 71 and with a number of by-pass grooves 70. At starting speeds the pressure in space 42, acting only upon the ball valve 62, causes very small lifting of the valve 62 so that the fuel delivered by the pump 51 passes through the throttling orifice 71 and the high pressure maintained in space 42 prevents piston 10 lifting. At normal running the higher pressure developed initially by the pump 51 moves ball valve 62 sufficiently to allow the pressure to act on the head of member 64 and move it further to the right to bring the grooves 70 into communication with the exhaust ports 72 leading to the fuel tank. The pressure in space 42 is thereby reduced permitting the piston 10 to lift and displace the fuel in chamber 42 through aperture 61 when the injection piston 5 rises, thus reducing the delivery per stroke of the piston 5.