| 摘要 |
<p>1406174 Fluid-pressure servomotor systems SANDERS ASSOCIATES Inc 16 March 1973 [3 April 1972] 12829/73 Heading G3P A valve spool 53 having lands 67, 68 controlling communication between load ports 46, 47 and supply and exhaust ports 76, 45 is displaced by an increase in pressure in a space 54 or 55 produced by a pilot valve 36, the fluid at increased pressure flowing through a passage 81 or 82 into the load until the pressures in the spaces 54, 55 are again equal. Check-valves 75 and 85, 86 prevent flow from the load into the supply line 75 or into the spaces 54, 55. The pilot valve is supplied with pressure at a higher value than the pressure in the line 44 and may consist of a spool valve operated by a force motor (113), Fig. 6 (not shown) or a pair of single-beat lift valves operated through a loot-motion coupling by a torque motor (91), Fig. 5, (not shown) operation of the valve causing increased flow through one of a pair of restrictions 73, 74 and thus a higher pressure in one of the spaces 54, 55. The spool 53 is constructed as an open-centre valve and connected by conduits 26, 27 to further similar valves as shown in Fig. 1 and to a pump 21 and a tank 22. Each spool is controlled by a separate pilot valve which may be connected to the pump 21 through a common pressure booster. Alternatively, a pressure reducer may be inserted in a line 25 supplying the spools 53. Specification 1273297 is referred to.</p> |
