| 摘要 |
<p>981,782. Valves. SHAFER VALVE CO. Jan. 25, 1962 [Feb. 2, 1961], No. 2810/62. Heading F2V. [Also in Division G3] The subject matter is similar to that described in Specification 989,957 but the oscillating piston and rotary valve may be replaced by a double-acting power device 13, Fig. 1, and a gate valve 10. Additionally the lower end of tank 43 is connected by conduits 46, 47 through a valve 48 to the lower end of the device 13 whilst the lower end of tank 45 is connected by conduits 49, 50 through a similar valve 51 to the upper end of the device 13. Each valve 48, 51 is of identical construction and comprises a chamber 56, Fig. 2, with a seat 57 leading to conduit 46 or 49 whilst a movable valve closure 59 coacts with the seat. The closure 59 includes a head of resilient material and a stem 60 passing into a chamber 66 where it is provided with a piston 65, the chamber 66 being open to a conduit 71 or 77 connected to the upper end of tank 43 or 45; the diameter of stem 60 is of greater crosssectional area than that of the part of the head which engages the seat 57. A port 62 in the side of chamber 56 leads to conduit 47 or 50; the closure 59 is urged to the closed position by an adjustable spring 73. The upper part of chamber 66 is vented. If pressure fluid is supplied to a conduit 44, Fig. 1, the oil pressure in tank 45 acts through conduit 49 directly and the closure 59, Fig. 2, to unseat it and permit the air to flow via conduit 50 to the top of the power device. Concomitantly the pressure in conduit 77, Fig. 1, lifts the piston 65, Fig. 2, of the other valve 48 and unseats its closure member so allowing oil from the bottom of the device to exhaust the rough conduits 47, 46, Fig. 1, into the bottom of tank 43. The operation is reversed when pressure is supplied to conduit 41. Should the device 13 be stopped at an intermediate position the valve 48 acts to hold it in that position. If the oil in the device is subjected to extremes of temperature the closure 59 acts on a relief valve in response to pressure variations in chamber 56. A double check-valve 17 is connected across the gate valve 10, Fig. 1, and the supply for the control system is obtained from a point between the check valve elements. A piston 34, which actuates the control valves 20, is moved by pressure in lines 31, 32, which pressure is a measure of the flow in the line controlled by the gate valve; each line 31, 32 embodies a valve 38 for retrieving the pressures on the piston 34 whereby the piston and control valves 20 return to the neutral position after each operation.</p> |
