GB761160A - Improvements in or relating to pressure reducing valves - Google Patents

Abstract

761,160. Fluid-actuated valves. BENDIX AVIATION CORPORATION. March 30, 1954 [April 13, .1953], No. 9307/54. Class 135. A pressure-reducing valve comprises a valve body 10, Fig. 1, having inlet, outlet and return ports 11, 12, 13 respectively, a fixed two-part sleeve 16, 17 and a piston valve 26 slidable in the sleeve and urged by a spring 32 towards the outlet port 12 and its fully open position. The sleeve part 16 is formed at its ends with counterbores 16a, 16b mounting the sleeve part 17 and a spring-loaded dashpot piston 45 respectively and intermediate its ends with inlet ports 21. Annular recesses 24, 27, Fig. 2, in the sleeve part 17 and the piston valve 26 respectively are shaped and piston valve ports 25 inclined so that the momentum force of the fluid flowing through the valve is reversed in direction to assist the spring 32 in opposition to the outlet pressure acting on the right-hand end of the piston valve. This momentum force increases with increased flow rate through the valve so that increased assistance to the spring overcomes in part the objection to the increasing rate of the spring as the valve piston moves towards closed position. Sudden movement of the valve in the opening direction is prevented by the dashpot piston 45, movement of the latter being restricted by slow leakage of the fluid around the piston 45 and a notch 26b in the valve piston. Instead of a falling output pressure with increasing flow rate which is usual, the valve maintains a substantially constant output pressure for. all rates of flow through the valve and the output pressure may even rise with increasing flow rate. A venturi passage adjacent the outlet port 12 increases the pressure at the outlet and on an increasing rate of flow through the valve the difference in pressure at the two ends of the venturi also increases so that the valve opens wider at higher flow rates than would otherwise be the case. On the occurrence of an excessive pressure in the outlet radial ports 30 in the valve piston are uncovered to connect the outlet port 12 with the return port 13.