GB837114A - Fluid-actuated valves - Google Patents

Abstract

837,114. Valves. INDUSTRIAL GUARDING EQUIPMENT Ltd. Feb. 11, 1958 [Feb. 26, 1957], No. 6397/57. Class 135. In a fluid-actuated valve comprising inlet, outlet and exhaust ports 11, 13 and 14, Fig. 1, respectively, a main closure 15 for connecting the outlet port 13 to the inlet or exhaust ports, a pair of pistons 16, 17 for moving the closure 15, and electromagnetic valves 21, 25 for controlling the supply of actuating fluid to the pistons, it is arranged that when both electromagnetic valves are energized fluid is supplied to one piston and when both of these valves are de-energized fluid is supplied to the other piston. Valve 21 has an inlet passage 22 through the solenoid core, which is closed when the solenoid is energized, whilst an associated exhaust passage 23 is closed when the solenoid is deenergized. The inlet and exhaust passages 27, 26 of valve 25 are similar to those of valve 21 but are closed upon de-energization and energization, respectively, of the valve solenoid; the inlet 27 is in permanent communication with the'rear surface of piston 17 via a passage 28. The valve solenoid S1, S2, Provisional drawing, are in a circuit comprising switches E, O responsive to the pressure acting on pistons 16, 17 respectively, and relay R1, R2, the former having normally open contacts R1a, R1b, Rlc, and the latter having a normally open contact R2a and a normally closed contact R2b. Upon closing a switch C, the relay R1 is energized and solenoid S1 is energized over contact R1b; the consequent pressure drop in the fluid acting on piston 16 moves the switch E to cause energization of solenoid S2, the resulting admission of fluid on to piston 17 causes switch O to open. Opening of the switch C de-energizes the solenoids, the reduced pressure acting on piston 17 and the increased pressure acting on piston 16 enabling the switches O, E and relay contacts to return to the position shown. The main valve will always return to the closed position with ports 13, 14 in communication should there be a failure of one or both electromagnetic valves or of the electrical control circuit.