Patent GB-871152-A (GB)
Title: Hydraulic pressure control valve
Inventor: ROYLE JOSEPH KENNETH
IPC: F15B11/02
Filed: 1957-07-04
Abstract: 871,152. Fluid-pressure servomotor systems; regulating fluid flow; valves. NATIONAL RESEARCH DEVELOPMENT CORPORATION. July 28, 1958 [July 4, 1957], No. 21237/57. Class 135. A pressure-control valve device comprises a first spool, the rotational setting of which determines the proportion of an inlet pressure which appears at an outlet (to establish the desired operating pressure), such outlet pressure being applied to exert a longitudinal thrust on a second spool whose longitudinal position regulates the flow of pressure fluid to a utilization outlet, the pressure in this latter outlet being applied to the second spool to balance the longitudinal thrust thereon, whereby the pressure in the outlet is maintained constant. In the embodiment according to Figs. 1 and 2 the first spool 8 is formed with a pair of diametrically opposed pressure-regulating ports 12, 13, the pressure in which is governed by their angular setting in relation to opposed pressure inlet ports 14, 16 and exhaust ports 15, 17. Such pressure is communicated from ports 12, 13 to an annular space 26 to act upon the left-hand face of spool 8. The latter is integral with a second spool 28 of the same diameter, and whose longitudinal position controls the connection of an outlet 36 to the operated power member (ram, motor, &c.) with the motive fluid inlet port 33 or exhaust port 34. The outlet port 36 communicates via a passage 38, incorporating a restriction 43, with a space 40 at the right-hand face of spool 28, so that the spool assembly takes up a position in which the pressures in the spaces 26, 40 are equal, movement to the right increasing, and movement to the left decreasing, the pressure in space 40. Such pressure equalization occurs irrespective of the rate of flow of the motive fluid. The arrangement shown includes a second spool 27 of similar construction to spool 8 but discharging into the outlet 36, to permit a restricted flow of pressure fluid when spool 28 cuts off the main supply from port 33. The embodiment according to Fig. 3 comprises a spool 51 similar to spool 8 of the previous arrangement, the regulated pressure fluid from which is fed by a pipe 96 to a second spool 69 controlling the connection of utilization outlet 81 with a pressure fluid inlet port 78, or exhaust port 79. The fixed casing 67 for spool 68 is engaged by a freely sliding projection 75 at the end of a movable casing 68 divided into two compartments and housing a spool 71 integral with spool 69, and a fixed piston 93, respectively. Spool 71 controls the supply of fluid to the opposite sides of piston 93 through connections 88, 89, inlet port 86 and exhaust ports 87, 87a, whereby movement of spool 69 in either direction is accompanied by an equal movement in the same direction of casing 68. By this means the volume of chamber 97, to which the pressure fluid from pipe 96 is fed, is maintained substantially constant, thus preventing undue pressure variations in the chamber due to sudden movements of spool 69 in response to changes in motive fluid demands. This follow-up device forms part of the subjectmatter of divisional Specification 871,153.