| 摘要 |
<p>1,267,310. Fluid-pressure servomotor systems. BENDIX CORP. July 24, 1970 [Aug. 19, 1969], No. 36048/70. Heading G3P. A hydraulic circuit breaker comprises a housing 10 with a main valve piston member 18 which is actuated to isolate a utilization outlet 16 to an actuator from a pressure inlet 12 in the event of abnormal loss of pressure either between the outlet and the actuator or in a return conduit 69 from the actuator which passes through the housing. Mounted within the main piston is an auxiliary valve piston having at least two piston elements on a common rod 30. One element 28 is responsive on opposite sides through ports 22, 24 to the pressures on the upstream and downstream sides of a flow restriction formed by a ridge 20 on the main piston. Loss of pressure downstream of the outlet moves the auxiliary piston to the right at a rate controlled by a dashpot piston 38 having an orifice 42, to a position where a second piston element 32 exhausts pressure from the left hand side of the main piston through a chamber 52 and passage 74 to the return conduit, so allowing the main piston to move to the left and shut off the outlet 16. As shown, a third piston element 34 in operated position places the right hand end of the main piston in communication with one side of the element 28. In the event of loss of pressure in the return conduit 69, a separate control piston 62, which is subjected to the pressure upstream of a check valve 68 through a passage 64, is moved to relieve the loading of a spring 58 and the auxiliary piston again operates to cause closure of the main valve piston.</p> |
