GB869105A - Improved hydraulic actuators - Google Patents

Abstract

869,105. Hydraulic apparatus. RECHERCHES ETUDES PRODUCTION. Dec. 8, 1959 [Dec. 8, 1958 ; June 3, 1959], No. 41779/59. Class 69 (2). [Also in Group XXVIII] An hydraulic double-acting jack 5, Fig. 1, comprises an electrically-operated generator 1 of hydraulic energy, and an electrically-controlled distributer having a moving mass 10 actuating two exhaust valves 106, 206, each of the two chambers 105, 205 of the jack being coupled to the generator and to an exhaust valve. The generator 1 has a coil which is supplied with alternating current from a supply 2 and reciprocates a mass 3 having pistons 101, 201 which draw fluid through ports 102, 202 from a chamber 4 and pump it past valves 103, 203 to lines 104, 204 leading to the chambers of the jack. Pressure in the chambers is controlled by the exhaust valves 106, 206 which, in turn, are controlled by a mass 10 movable to the right or left by an electromagnetic device 6 operated by alternating or direct current from a source 9. The valves 106, 206 are spring-urged to the open position when the device 6 is not energized. A signal proportional to the displacement of the piston of the jack from its central position may be obtained from an energized coil 12 movable with the piston-rod between fixed coils 107, 207 which are mounted in a magnetic circuit 14 and connected to terminals 108, 208. In another embodiment, the distributer comprises two reciprocatable masses, one controlling a pair of inlet valves and the other a pair of exhaust valves, one inlet and one exhaust valve being connected to each chamber of the jack. The valves may be of the ball, sliding or conical type. In a further embodiment, the generator pistons 101, 201, Fig. 3, are reciprocated by the electromagnetic device 1, and the exhaust valves 106, 206 are controlled by solenoids 111, 211. With both solenoids de-energized, both valves are closed and the piston of the jack is locked in position. The piston can be moved to its lowermost position without employing the generator 1 by deenergizing a solenoid 214 which permits the seating 212 of the valve 206 to move and open the valve. The same signal de-energizing the solenoid 214 may de-energize a solenoid 23 which releases a latch 22 to allow the spring- urged piston 20 of an accumulator 19 to supply fluid under pressure to the chamber 105 of the jack. The seating 112 of the valve 106 is movable against a spring 113 to open the valve in the event of excess pressure occurring in the chamber 105; the valve 206 may be similarly arranged.