GB734307A - Improvements in or relating to pumps and control systems therefor - Google Patents

Abstract

734,307. Fluid-pressure servomotor-control systems. BENDIX AVIATION CORPORATION. Jan. 23, 1953 [March 22, 1952], No. 2057/53. Class 135. [Also in Groups XXVI and XXVIII] The delivery of a constant stroke fluid pump is controlled by variably regulating the fluid pressure differential established across the check valves 28 controlling the pump discharge ports 33 so as to vary the period of time the check valves are seated during the suction-stroke of the pump. Fig. 1 shows a swash-plate pump 10 for supplying liquid fuel to the burners of a gas turbine or jet propulsion engine past a throttle or control device 58. The pump 10 (see Group XXVIII) comprises a swash-plate 471 driven from the engine through a shaft 48 and adapted to reciprocate pump plungers 18 in pumping chambers 23 having inlet ports 24 and discharge ports 33. The fuel passing the valves 28 flows through ports 34<SP>1</SP>, 36 to a common chamber 37 connected to the pump delivery pipe 39. The valves 28 are loaded in the closing direction by springs 41 and the chambers 40 at the rear of the valves communicate with the pump delivery pressure by restricted orifices 42 in the valves themselves or by a bleed between the chamber 37 and an annular manifold 44 connected to the chambers 40 by ports 43. The manifold 44 is connected by conduit 45 to a regulating device comprising a valve 60 actuated by a spring-loaded diaphragm 61 subject to the pressure drop across the throttle 58. The valve 60 is adapted to connect the conduit 45 to the low-pressure side of the pump through a further conduit 71. The pressure drop across the valve 60 is regulated by a further valve 72 actuated by a spring-loaded diaphragm 73 and having ports 70 in a hollow sliding valve member. The passage 45 is connected to a chamber 74 on one side of the diaphragm 73 by a passage 75 with a calibrated restriction 75<SP>1</SP>. This arrangement limits the rate of response of the valve 72 and serves to prevent surges in the main delivery pipe 39.