| 摘要 |
<p>1,112,618. Hydraulic apparatus. FAWICK CORPORATION. Jan.13, 1966 [Jan. 29, 1965], No.1669/66. Heading F1P. In a hydraulic system in which a pump 12 supplies fluid to one or other end of an actuator 10, 11 through a changeover spool valve 14, the velocity of the actuator is controlled by the degree of displacement of the spool 22 and a compensating valve 36 subject to the pressure drop across the valve 14 maintains the flow of fluid to the actuator constant irrespective of fluctuations in the pump output or actuator load. The compensating valve 36 comprises a housing having a bore 45 in which is slidable a valve piston 49 controlling communication between an inlet port 42 connected to the pump output and an outlet by-pass port 43. The piston valve 49 is urged towards its closed position by a spring 55 and by the pressure of fluid admitted to a valve chamber 48 connected through a line 35 and a shuttle valve 34 to whichever of the inlet lines 30 or 31 is pressurized. If the load on the motor decreases or the pump output increases, the input flow to the valve 14 and hence the pressure drop thereacross increases to cause movement of the compensating valve to the right thereby increasing the amount of fluid by-passed through ports 42, 43.</p> |
