Patent GB-1068601-A (GB)
Title: Improvements in and relating to fluid control valves
Inventor: JORDAN ROBERT DALE
IPC: F16D67/04
Filed: 1964-04-02
Abstract: 1,068,601. Presses. MINSTER MACHINE CO. April 2, 1964, No. 13657/64. Heading B5F. [Also in Division F2] General arrangement.-The connection of a flywheel 18, Fig. 2, to the crank-shaft of a press is controlled by a friction clutch 30, 32 and a brake 42, 44 oppositely engaged and disengaged by a common annular piston 36 the fluid supply to which is controlled by a pair of main valves 50, 52 arranged in series flow and operated through pilot valves 58, 60 the positions of which are determined by solenoids S1 S2, respectively; the main valves are arranged in parallel to control the exhaust path from the piston and are of magnetic material, and the valve positions are detected by change in coupling of differential transformers 205. Electric circuit.-The electrical control circuit consists of power supply L1, L2 (Fig. 5, not shown) between which is a contactor CR1, a contact 200 of another contactor CR2, and contacts 204 of relays 215, 217 which are part of the valve position detector. The coil of CR1 has a holding circuit through one of its own contacts 206 and a press-actuated limit-switch LS1. The coil of CR2 is in circuit with the contact 208 of CR1 and in parallel with the coil of CR2 are the pilot-valve solenoids S1 S2. A holding circuit for the coil of CR2 is established through another press limit-switch LS2, and contacts 214 of relays 215, 217. The differential-detecting transformers 219, 221 are connected to an oscillating circuit which includes transistors Q3, Q4, battery 216, coil 218, coils of relay 215, 217, and condensers C1 C3. This circuit provides for automatic cyclicoperation of the press. The differential transformer may be positionally adjustable to control the sensitivity. The transformer may be replaced by an electromagnetically-actuated proximity-switch each of which is associated with two transistors which amplify the current sufficiently to operate the detector coils. Logic circuit.-With both solenoids S1, S2 (Fig. 8, not shown) de-energized and valve position switches SW1, SW2 open an "'on" voltage is supplied to all three input terminals of " and " component 408 which supplies an "on" voltage to an " and " component 414 which remains in an " on " condition even when the signal from 408 is interrupted. The other terminal of 414 is supplied with an " on " voltage over press limit-switch LS1 and component 414 supplies an " on " voltage to one terminal of an " and " component 410. Upon depressing switches 402, 404 the circuit to the other terminal of 410 is completed whereby valve amplifiers 420, 422 are turned on to energize the solenoids; one amplifier only may be used. Actuation of switches 402, 404 turns. "off" the "and" component 408 but component 414 remains " on " because of a seal 438. Press limit-switch LS2 now closes and supplies a signal to " and " component 418 and if switches SW1, SW2 have been operated then resulting signals in " and " component 418 will maintain the amplifier 420, 422 turned "on". Press limit-switch LS1 now opens and turns "off" components 414, 410 whilst later opening of switch LS2 turns "off" component 418 and hence amplifier 420, 422 to de-energize the solenoids. The cycle then recommences if the valves have operated correctly. In a modification, each valve has its own separate logic circuit. Switch operated components 424, 426 comprise resistances between a D.C. source and earth.