Patent GB-1421184-A (GB)
Title: Hydraulic control valve assembly
IPC: F15B13/00
Filed: 1972-12-29
Abstract: 1421184 Valves KAYABA KOGYO KK 29 Dec 1972 [29 Dec 1971 18 Feb 1972 26 Feb 1972] 60058/72 Heading F2V [Also in Division G3] A control valve for an hydraulic system comprises a slidable valve spool 14, Fig. 1, movable initially in response to a pressure drop across a restriction 28 due to pilot flow through a passage 35, to communicate an aperture 25 with passage 10 or 11 and thereby control main flow between a port 31 and ports 12, 13. Thereafter the position of the spool 14 is influenced by the pressure of the main flow. The valve spool is biased to the neutral position shown by a spring 23. Shock due to switching is damped by transfer-flow through restriction 30. The restriction 28 may be of screw-threaded adjustable form, Fig. 2 (not shown). A restriction 37 may be provided in the main flow path, and may be in the form of a sleeve (41), Figs. 3A, 3B (not shown), having transverse bores and movable axially in the direction of flow to vary its effective flow crosssection when the flow direction is reversed. A flow control valve assembly, Figs. 4 and 5 (not shown), is formed by the provision of a pilot flow control valve (43) in a line (42) connecting the pilot passage 35 of the basic valve described above to a main line (44) which is connected to supply and return ports 12, 13 and is provided with a flow-direction switching valve therein, the pilot valve providing constant flow through the pilot passage and thereby constant main flow. The flow control pilot valve may be replaced by a throttle valve. A distribution and collection valve assembly is formed by arranging two valves of the basic type in tandem, Fig. 6 (not shown), with common supply and return ports and with the two pilot passages connected to a selector valve (48) for common communication with either the pressure supply line or the return line. The basic valve may be adapted for use as a pressure relief valve assembly, Fig. 7 (not shown), by providing a pilot relief valve (51) in a line connecting the pilot passage 35 to a reservoir (50). Two pressure relief valve assemblies may be used in tandem in an overload mechanism in an hydraulic motor circuit, Fig. 10 (not shown), each valve assembly being associated with a respective side of the motor to relieve overpressure. A reducing valve assembly is formed by the provision of a pilot reducing valve (52), Figs. 8 and 9 (not shown), in a line connecting the pilot passage 35 to the main supply or return line. In another tandem arrangement for controlling an hydraulic motor, Fig. 11 (not shown), an auxiliary switch-over valve (57) may be moved into a " float " position wherein the two pilot passages are interconnected and are connected with a reservoir, whereby external loading on the motor automatically appropriately connects the opposite sides of the motor to the supply and return lines. In a single or tandem arrangement of the basic valve, flow to and from the pilot passage or passages may be controlled by a direction control pilot valve (58, 59), Figs. 12 and 13 (not shown), to thereby control the supply and return flows to and from the motor. Anothe tandem arrangement, Fig. 14 (not shown), has a directional control valve (59), overload relief valve (51), flow control valve (43) and a reducing valve (52) in the pilot lines. A modified form of the basic valve may be used to control flow to, and automatic unloading of, an actuating circuit 164, Fig. 15. In the position of the spool 114 shown, the circuit 164 is supplied with actuating fluid from a source 149 via passages 131, 160. Movement of pilot valve 165 to its other position causes flow through pilot passage 135 to reservoir 150 and thereby a pressure drop across orifice 128, resulting in raising of spool 114 and consequent unloading by a connection to reservoir 150 via passages 162, 110 and ports 125, 112. Abnormal pressure in circuit 164 when on load, causes opening of pilot relief valve 166 and consequent raising of spool 114 to vent the abnormal pressure. In Fig. 16 (not shown), the valve 165 and the port 112 instead discharge to another point of use during the unloaded state. The connections to the second point of use may include non-return valves (168, 169), Fig. 17 (not shown), and the spool may be provided with an additional port (167) which communicates directly with the reservoir 150 when the spool is raised beyond the level at which it unloads to a second point of use. To avoid overpressure at the second point of use from adversely affecting the operation of the primary valve arrangement, a pressure-actuated switching valve (170), Fig. 18 (not shown), is provided in the pilot line to switch the pilot flow to the reservoir. This also causes the spool to lift sufficiently to open the port 167 and thereby unload the first point of use directly to the reservoir. The pilot line may also include a mechanically or electricallyactuated switching valve (171), Figs. 19 and 20 (not shown), for switching the flows from the reservoir to the second point of use when required. The construction of the main valve housing of a tandem control valve arrangement, in particular with regard to the location of the many bores and passages in the housing body and top and bottom covers therefor, is described with reference to Figs. 21 to 37 (not shown). Moreover, a twin relief pilot valve unit and a twin flow control pilot valve unit for use with a tandem main control valve are described with reference to Figs. 38 and 39 (not shown), the units (470), Fig. 41 (not shown), being stacked on and secured to the main valve housing together with a solenoid pilot valve unit (500). Two such assemblies may be bolted together for combined operation, Figs. 42, 43 (not shown). Another control valve construction, Fig. 44, is somewhat similar to the one shown in Fig. 15 but incorporates pilot flow passages 358, 347 communicating with return groove 309. A relief valve unit (470) and a solenoid valve unit may be stacked on and secured to the valve housing 301 so that the solenoid valve when energized permits flow from inlet 312 through pilot passage 307, the inlet of valve unit (470), the solenoid valve, the outlet of valve unit (470), the pilot passages 358, 347 and groove 309 to the reservoir. The control valve may include an additional pilot return groove (309a), Fig. 51 (not shown). Two or more control valves of different designs, with or without their respective pilot valves, may be bolted together, Figs. 49 and 57 to 60 (not shown), and special connecting plates, Figs. 61 and 62 (not shown), may be used between the main control and pilot valves. In a final embodiment, Fig. 63, a main control valve 201a has a number of pilot valves and a solenoid servo valve 500a stacked thereon, the degree of opening of the valve 500a being dependent on the electrical signal applied thereto to permit pilot flow therethrough and through orifice 228. The pressure on one side of orifice 228 is communicated to the chamber 216 below the spool 214, whereas the pressure communicated to the chamber 217 above the spool 214 is taken from one side of orifice 502a in the solenoid valve 500a.