GB813572A - A device for automatically regulating the supply of pressure fluid to apparatus in which a continuous flow is required - Google Patents

Abstract

813,572. Vehicle power steering. REIS, S. Sept. 16, 1955 [Sept. 17, 1954], No. 26579/55. Class 79(5) [Also in Group XXIX] A valve device for automatically regulating the rate of supply of pressure fluid from a pump to an apparatus to keep the supply thereto substantially constant or at least to prevent excessive variation thereof under varying conditions of pump speed and/or resistance to fluid flow, comprises a valve body 1 having an inlet 3 receiving fluid from the pump, a first outlet 6 connected to the apparatus, e.g. a servo vehicle steering mechanism, and a second outlet 10 for the escape of excess fluid to the suction side of the pump. Communication between the inlet 3 and the outlet 6 is controlled by a first valve member 12 having limited sliding movement between stops 17, 19 in a second valve member 5 which controls communication between the inlet and the outlet 10. Springs 7, 16 abutting either side of the stop 17 load the valve members. At low pump speeds, i.e. low engine and vehicle speeds, the valve member 5 is seated against a body shoulder 8 and the valve member 12 fully open to allow adequate flow of fluid to the apparatus. On increasing pump speed and hence pump output pressure the pressure difference on the two sides of the valve member 12 increases such that the valve member 12 moves against the spring 16 to throttle the flow of fluid to the apparatus. The rate of the spring 16 is chosen to maintain a substantially constant flow rate through the valve member 12. At higher pump speeds, the valve member 12 abuts the stop 17 with the valve member remaining partially open. At still higher pump speeds, i.e. high engine and vehicle speeds, both valve members are moved against the spring 7, the valve member 12 remaining partially open to supply the apparatus and the valve member 5 opening to expel fluid excess of requirements. A spring- loaded relief valve 20 is fitted to relieve excessive presure. The springs 7, 16 are rated so that for every pump speed within the designed range there is a corresponding equilibrium position of the valve members 5 and 12. Specification 783,467 is referred to.