GB845997A - Improvements in fluid control valves - Google Patents

Abstract

845,997. Valves. BROADBENT, S. Nov. 2, 1956 [Nov. 8, 1955], No. 33491/56. Class 135. A fluid-control-valve having a sliding control member which is pilot-actuated by means of fluid-pressure controlled by solenoid-operated pilot valves comprises, as shown in Fig. 1, a valve casing 1 having ports 4, 5 and 6 for inlet, outlet and exhaust connections, respectively, communicating via passages 7, 8 and 9, respectively, with a valve bore having a ported liner 11 in which reciprocates a piston valve member 14. The solenoid pilot valves 17 are enclosed within tubular magnetic casings 18 that are mounted in the valve end covers 2 and protrude into cylindrical piston chambers 19 formed in the ends of the piston 14, the casings having sealing-rings 24 engaging the walls of the piston chambers. The solenoid pilot valves comprise a tubular armature casing 20 containing a spring-loaded armature 21, fitted with a seating insert 23, operable by energizing the solenoid 22, but normally seating on an outlet orifice formed in a bushing 25 having an enlarged stem portion 26 to support a sealing-ring 39 for sealing against a radial face 40 of the end cover 2. The piston chambers 19 have bleed holes 37 communicating with the pressure-fluid inlet passage 7, so that the piston chambers are fully pressurized and the piston 14 is balanced in each operative position. Pressure fluid also enters the armature chamber through the passageway 38; thus, on energizing one of the solenoids 22, the armature will retract to unseat the seating element 23 from the bush 25 so that fluidpressure in the communicating-piston chamber is released and the fluid pressure in the other piston chamber will force the piston into its opposite operative position. The projecting part of the bush 25 provides a manual control operating independently of the solenoid. The valve may be manually operated by depression of the bush which retracts the armature and allows pressure fluid to escape through the clearance 41. An alternative embodiment, Fig. 2, has a single solenoid-actuated valve, where the piston 14 acts under the differential pressure between the solenoid valve casing 18 acting in the piston chamber 19 and a piston 49 formed on the end cover remote from the solenoid acting in the smaller chamber 51. Pressure-fluid is fed to the pilot valve through a tubular stem 52 protruding from the solenoid structure through the piston 14 into the chamber 51 where a bore 59 communicates with the inlet passage 7. A modified armature 21 has seating members 23 at each end and a return-spring 47 acting on a shoulder 48. As shown, chamber 19 is open to exhaust via holes 56 in the solenoid casing, slot 57 in the armature and a bore in bushing 42, while pressure-fluid acts in the chamber 51. If the solenoid is energized the outlet is sealed by the armature 21 and pressure-fluid is allowed to enter the chamber 19, the differential force moving the valve to its other operative position. A further modification, Fig. 3, has three positional control where the action of the armature is reversed to that shown in Fig. 2 and manual control is provided by bushings similar to those shown in Fig. 1. The central position, shown, is provided by having subsidiary plungers 60, acting in a bore 62 in the piston, normally held apart by pressure within the chamber 63, so that stop-faces 66 on the plungers engage the end faces 67 of the solenoid casings 18, when the stop-faces 65 in the piston limit the expansion of the plungers. Energizing one solenoid 18 will exhaust the adiacent chamber 19 and the resulting pressure differential will move the valve to one extreme position, energizing the other solenoid will move the valve to the other extreme position, and energizing both solenoids will select the central position.