Patent GB-915114-A (GB)
Title: Improvements in or relating to control valves for fluid pressure operated mechanisms
IPC: F15B13/08
Filed: 1959-03-12
Abstract: 915,114. Valves. HYDRAULIC UNIT SPECIALTIES CO. March 12, 1959, No. 8660/59. Class 135. A rectangular valve casing 5, Fig. 3, incorporates three parallel bores 12, 13, 14 in a common vertical plane, the two latter housing sliding closure members 16, 17 respectively; the casing has an inlet 19 whilst bore 13 embodies grooves 20<SP>1</SP>, 21<SP>1</SP> leading to outlets 20, 21, Fig. 4, e.g. connected to a double-acting ram. Another pair of outlets lead to grooves 22<SP>1</SP>, 23<SP>1</SP>, Fig. 3, in the bore 14 to control another similar ram or, if one of the outlets is closed-off, as shown, a single acting ram. The inlet 19, near the top of the casing, communicates directly with an exhaust outlet 26 near the bottom of the casing via a passage 29 from which leads a U-shaped exhaust 35, both limbs 36, 37 of which intersect the bores 12, 13, 14. The bore 13 is also provided with grooves 42<SP>1</SP>, 43<SP>1</SP> that are interconnected by a U-shaped passage 39, Fig. 4, which is connected to the inlet 19 by a check valve 54 and a vertical feeder bore; grooves 44, 45, Fig. 3, in bore 14 are similarly arranged and supplied with fluid from inlet 19. Member 16 incorporates annular grooves 58, 60, 61 and member 17, annular grooves 59, 62. In the neutral position fluid flows from the inlet to the outlet 26 by passage 29 and grooves 58, 59. Upon moving member 16 leftwardly the passage 29 is cut-off from the outlet 26 and bore grooves 201, 421 are interconnected via groove 60 whilst bore groove 21<SP>1</SP> is open to the exhaust 35 by limb 36; the pressure builds up in the feeder and the check valve 54 is unseated whereby pressure fluid is supplied to outlet 20 through passage 39 and grooves 20<SP>1</SP>, 421. Exhaust from the ram enters the outlet 21 and flows through exhaust limb 36 by way of groove 61. If the member 16 is moved from rightwardly from its neutral position, pressure fluid is supplied to the ram from outlet 21 and the ram exhaust enters the limb 37 via outlet 20. Upon moving the member 17 rightwardly the passage 29 is cut-off from the exhaust outlet 26 and groove 62 interconnects bore grooves 45, 23<SP>1</SP>; the resulting pressure builds up in the feeder, unseats the check valve in the associated U-shaped passage whereby fluid flows into the groove 23<SP>1</SP> and thence through an outlet 23 to the single-acting ram. When the member 17 is moved leftwards from its neutral position, fluid is exhausted from the ram by outlet 23, groove 62 and exhaust limb 36. Both rams may be simultaneously operated. The members 16, 17 may be provided with centring springs 65. A relief valve in bore 12 comprises a sleeve 66 with ports which open the inlet 19 to the sleeve interior, a stem 67 with a head slidable in the sleeve and a closure member 68 that seats on the right-hand end of the sleeve; the member 68 is loaded by a spring 69. When the pressure of the fluid in inlet exceeds a given value the member 68 is unseated and connects the inlet 19 with the exhaust limb 37. In a modification, two bores 71, Fig. 5, which joins the passage 39 with the passages 79 leading to the ram outlets, each contain a spring- loaded plunger 72 normally positioned as shown, and having an annular groove 77 connected by an angled channel 78 to an axial hole that receives a pin 76. When the member 16 is moved to cause a pressure build-up in passage 39 both plungers 72 are thereby moved out of the passage 39, then grooves 77 then putting the outlets in communication with the bore grooves 20<SP>1</SP>, 21<SP>1</SP>. If the fluid exhausting from the ram is at too high e.g. due to the ram load descending too fast, a pressure then the associated plunger 72 is moved thereby to cause its groove 77 to throttle the passage 79 until the inlet pressure and combined exhaust pressure and spring forces acting on the plunger are rebalanced. When the valve, e.g. member 17, Fig. 3, controls a single-acting ram then only one plunger 72 is needed. In another modification, the ram exhaust pressure is controlled by means of a spring- loaded plunger 86, Fig. 7, slidable transversely of the passage 79; the plunger is moved to throttle the passage 79 in dependence upon the pressure differential thereacross since the outlet end of the plunger has a reduced diameter extension 87 and the resulting annulus is subjected to pressure from the outlet, e.g. 23 via a channel 89 embodying a variable restriction 90 whilst the inner end of the plunger is acted upon by pressure in passage 79. Passages 92 interconnect both sides of the plunger 86. In a further embodiment, Fig. 8, not shown, the axial lengths of grooves 60<SP>1</SP>, 611 are insufficient to connect the associated body grooves and exhaust limbs, the ram exhaust being returned to the latter through metering passages in the sliding closure member itself. In a final embodiment, Fig. 9, not shown, the closure members may be arranged in series so that only one ram may be operated at any given time; in this case the feeder passage is omitted and the U-shaped passages 39 are individually connected to the passage 29. Specification 915,116 is referred to.