| 摘要 |
1514658 Fluid-pressure servomotor systems DEERE & CO 29 Dec 1976 [29 Dec 1975] 54263/76 Heading G3P A hydraulic system comprises a variable displacement pump 10 with a displacement control device 36 spring biased to increase displacement and an output line 16 connected to a motor 18, 20 via a motor control valve 26 or 28, a control line 50 connected between the pump and the device 36 to increase pump displacement against the spring bias, a demand valve 42 to block the control line in response to pressurized fluid conveyed by a pilot line 61 from a point between a motor 18 or 20 and its control valve 26 or 28, and a flow responsive valve 80 so connected with the pilot line 61, the output line 16, and the sump 14 that in response to decreased flow through the output line it provides connection of the pilot line to a sump whereas, in response to increased flow through the output line, it does not provide this connection. The device 80 includes a piston 90 having a groove 100 containing a ring 102 which is moved slightly to the right as the piston is displaced against a spring 91 by increasing pump output. During this movement, lines 84 and 86 remain unconnected but during reverse movement of the piston 90 with decreasing pump output pressure connection is temporarily established in consequence of the altered position of the ring 102 (see Fig. 2, not shown). Pressure in the pilot line 61 due to failure of a motor control valve to return fully to neutral position is thus relieved and the return of the pump 10 to no-load condition is ensured. The system also includes a priority valve 72, a relief valve 58 and a feedback lever 30 for the valve 28 and motor 20. |
