GB675840A - Improvements in and relating to variable stroke rotary fluid pumps - Google Patents

Abstract

675,840. Rotary pumps. GENERAL MOTORS CORPORATION. Jan. 10, 1951 [Jan. 24, 1950], No. 684/51. Class 110(ii) [Also in Group XXXI] A variable-stroke pump P of the outwardly-sliding vane type, has a slideable stator 10 subjected to the pump discharge pressure in spaces 122, 124 and additional pressure from a spring 18 in the space 124. Fluid pressures in spaces 122, 124, are controlled automatically through a valve 110, and/or by external mechanical means, e.g. as shown in Fig. 6 where the accelerator pedal of a motor vehicle acts through linkage on a stem 115 of the valve 110. A second valve 120 controls the fluid flow to an auxiliary unit at a pressure lower than that determined by the valve 110. As a shaft 1, rotor 12 and vanes 11 rotate, fluid is drawn into a passage 107 and delivered into a passage 108. these passages being connected laterally with the working chamber 108<SP>1</SP>. Fluid under delivery pressure from 108 passes through passages 140 in valve 110, passages 21, 22 and port 125 into space 124 to force the stator 10 upwards, aided by the spring 18, to full-stroke position. Undue rise in delivery pressure forces the valve 110 against its spring 111 and when a port 141 lines up with a passage 123, fluid under pressure flows to the space 122. the supply port 21 leading to the space 124 is cut off and the stator moves downward to decrease the pump capacity. A drain 127 for the valve bore 102, is closed off when the edge 142, of the valve, moves to the left. An auxiliary lower pressure feed is regulated by the valve 120 which is supplied by the pump through a port 132, which is positioned to receive fluid at less than delivery pressure. Port 132 is open to the pump chamber 108<SP>1</SP> only after the ring 10 has moved a certain distance, say one third of its travel. If the pressure above valve 120, in space 128, exceeds a certain value, then the valve is forced downwards and closes off the port 132. The auxiliary feed passes to a line by way of a port 136. Fig. 6 shows the pump P on a motor vehicle wherein the pump delivery 105 is connected to a servo control mechanism V and the .auxiliary reduced pressure line 150 is connected between port 132 and the working :space of a fluid coupling A. The vehicle engine E has 4 shaft l driving the coupling A connected by a gear box T to the driven shaft O. The mechanism V controls the speed ratio of the transmission T in known manner. The outlet pressure of the pump P, for controlling the speed ratio through the servo mechanism V, can be varied by use of an accelerator pedal acting on a rod 155, lost-motion device D and links acting on an end 151 of the valve stem 115. The rod 155 may act through a spring or directly on a link 154. The pump pressure may be used to operate a clutch or brakes or both in an epicyclic gearing. In a modification, Fig. 8, (not shown), the stem 115 is moved to the right under external fluid pressure acting through a floating piston.