GB935364A - New or improved control means for hydraulic actuated apparatus - Google Patents

Abstract

935,364. Fluid-pressure servomotor control systems. INDUSTRIEWERKE KARLMARX-STADT VEB. Dec. 12, 1959, No. 42336/59. Class 135. A control means for the piston 10 of an hydraulic actuator comprises a cylinder 1 in which is slidably-mounted a control piston 2 connected to a piston 3, by a loaded coupling spring 9 so that the force exerted by the spring in conjunction with the applied pressure of the hydraulic medium determines the displacement of the piston valve. In operation, with the control means in the position shown, pressurized fluid is fed via a valve through a port 17 into a chamber 16 thereby acting on the control piston 2 to move it against the action of the spring 9 so that ports 23, 24 are uncovered, the piston 3 remaining stationary due to its connection with a cam-slot 11 in the actuator piston 10. Pressurized oil is then able to flow through a port 18 into a chamber 5 and thence via the port 23 to act on one side of the piston 10, exhaust oil on the other side flowing to a reservoir via port 24, chamber 6 and ports 19, 20; upon movement of the piston 10 the piston 3 is moved together with the control piston until ports 23, 24 are again closed and the movement of the piston 10 ceases. Further successive admissions of control fluid into the chamber 16 causes the piston 10 to be moved until.it reaches the end of its stroke; by successively reducing the pressure in the chamber 16, the piston 10 may be returned to its normal central position. To move the piston 10 in the opposite direction, the control fluid is fed into the chamber 12 thereby acting on the control piston so that the ports 23, 24 are uncovered, the pressurized oil then flowing via port 18, chamber 5, port 24 to act on the opposite side of the piston 10. Further operation is as described above. A reduction gearing, such as a differential lever, may be connected between the cam 11 and piston 3.