Patent GB-576309-A (GB)
Title: Control valve for hydraulic systems
IPC: F16K11/07
Filed: 1943-07-19
Abstract: 576,309. Hydraulic control valves. HYDRAULIC CONTROL ENGINEERING CO. July 19, 1943, No. 11730. Convention date, June 30, 1942. [Class 135] A control valve for a hydraulic mechanism comprises a housing 10, Fig. 2, a plunger 26 slidable in a bore in the housing, the plunger being hollow and formed with parts 60, 62, 66 and a groove 58 which cooperate'with passages 74, 76, 88, 90 intersecting the bore in the housing, and a check valve 68 carried in the hollow part of the plunger. The open end of the plunger is closed by a plug 48 and a spring 46 held between this plug and a shoulder 50 on the plunger also presses on a plug 40 closing the bore in the housing to hold the valve in the neutral position shown. A sealing gasket 42 is provided for the plug 40. The housing may accommodate two valves which control separate rams &c., and, in the neutral position, pressure fluid enters by passage 74, flows past groove 58 into passage 76, and thence past groove 58<1> in the second valve and out through passage 78 back to the reservoir. When the first valve is moved to the right, the land portion of the plunger will cut off communication between inlet 74 and passage 76, and ports 60 will coincide with inlet 74 so that the pressure fluid enters the hollow in the plunger, pushes back valve 68 against its loading spring 70, and passes out through ports 66 into passage 88 leading to the rum &c. On moving the valve to the left, return fluid from the ram flows from passage 88 though ports 62 into the plunger, pushes back valve 68, and flows out through ports 66 into a chamber 52 which communicates with the reservoir through a passage 54. The ports 60, 62 are staggered round the valve plunger so that fluid is not suddenly applied to or exhausted from the ram &c. Seals 38 for the plungers are provided, together with a passage 84 leading to the reservoir to prevent highpressure fluid from reaching the corresponding seal. A spring-loaded relief valve 106, Fig. 3, for the hydraulic system, is situated in a conduit connecting the inlet 74 with the exhaust passage 78, and its setting is adjusted by a gauging block 118 which is held in engagement with the adjusting screw 114 by a plug 120 screwed into a further plug 116 closing the end of the conduit in which the valve is situated. The valve head 106 has cut-away sides and seats against a sleeve 100 held in position in the conduit by a set-screw 102 which engages a groove in the sleeve. A composite valve housing comprises a bottom section 194, Fig. 6, provided with a relief valve 192, one or more intermediate sections 196 provided with doubleended valves 190 for operating a double-acting ram or two single-acting rams, and a top section 186, the sections being secured by bolts 200. The valve plunger in the bottom section is shown as having a blind right-hand end. In the neutral positions shown, pressure fluid enters through ports 206, 208, flows into passages 212, 214, past grooves 216, 218 in the first valve plunger, into passages 224, 226, past the grooves in the second valve plunger and into a chamber 234 which communicates with low-pressure return passages 250, 254. The plungers are chamfered at 252 to shut off the oil gradually and give a cushion effect. Specification 517,467 is referred to.