GB560818A - Improvements in or relating to fuel-injection pumps for internal-combustion engines - Google Patents

Abstract

560,818. Fluid pressure servomotor control systems. LOVESEY, A. C., and DAVIES, K. R. July 17, 1942, No. 9996. [Class 135] An engine-driven reciprocating fuel pump for supercharged fuel injection internal-combustion engines is provided with means for varying the effective stroke of the pump to provide a predetermined or constant fuel-air mixture-ratio over the normal working range of boost-pressure and automatically to change the ratio to enrich the mixture at very high boost-pressures and when the engine is idling. In the arrangement shown in the Figure, the stroke varying mechanism is adjusted by a rod 14 actuated by a single-acting piston 10 loaded by a spring 15. Pressure fluid is supplied to the power cylinder through a pipe 12 fitted with a restriction 13 and controlled by a hinged leak-off valve 18. This valve is actuated by a diaphragm 21 which may be loaded in accordance with the temperature of the induction system and the exhaust back-pressure, is subject to the boost-pressure of the engine. The diaphragm is loaded by a spring 23 bearing against a movable abutment 27 moved by a lever 25 pivoted to a rod 24 on the piston 10. During cruising the lever turns about an adjustable fulcrum 29, during highpower conditions about an adjustable fulcrum 28 and during idling about an adjustable fulcrum 30. In another form, in place of the fulcrum 30, the rod 14 acts through a lever turning on a fixed fulcrum and arranged to increase the leverage during the idling range. And in a further modification, in place of the fulcrum 30, a second adjustable loading spring, 'associated with the spring 23, is brought into action during the idling range.