Valve means for controlling operation of a fluid motor

摘要

1,045,764. Hydraulic control circuits. HYDRAULIC UNIT SPECIALTIES CO. May 1, 1964 [May 16, 1963], No. 18193/64. Heading F1P. The hydraulic fluid supply duct 27, Fig. 1 (not shown), connecting a pump 11 to a distributing valve unit 18 which in turn is connected by ducts 42, 43 to a double-acting motor 10 may be by-passed and the pump delivery returned to a reservoir 12 by a cupshaped valve 35 having metering slots 112 leading from the underside of its lower end 109, Fig. 3 (not shown), to the by-pass 32 and return duct 331 and having a narrow central bore 107 leading to the valve chamber 106 which is connected by a duct 104 to an open centre spool valve unit 20 which when in the near neutral position connects chamber 106 to reservoir 12 through the return duct 331 and allows valve 35 to open against a biasing spring 108 to an extent governed by the obturation of the opencentre passage 88, 89, 90 of spool 85 at unit 20. Excess pressure which may develop in valve inlet chamber 30 when the valve 35 is closed is released through a duct 117 containing a plunger 120 which unseats a valve 114 thereby connecting said chamber 30 to the by-pass duct 32. The distributing valve unit 18 comprises an inlet 28 connected to service ducts 42, 43 by ports 401, 411 controlled by a pair of supply check valves 45, 46 and by a pair of exhaust check valves 47, 48 which are open or closed according to whether chambers 60 behind valve actuators 62 are connected by the spool valve member 85 to the exhaust duct 331 or to supply duct 104. A radial port 76 in each check valve 45-48 allows fluid to be exhausted from the valve interior during actuation by 62 and in the case of the exhaust check valves 47, 48 allows fluid to pass through an axial passage 78, Fig. 4 (not shown) and an eccentric passage 80 and through ducts 70, 73 to the spool valve and the return duct 331. The spool 85 has metering slots 102 at each end of each land which following a small axial displacement of the spoolserve to provide fine control of supply and exhaust of fluid through the distributing valve resulting in fine control of the speed of the motor in both directions.