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Flow sensitive hydraulic control valve

A hydraulic directional control valve for supplying fluid to a hydraulic motor and incorporating one or more fluid flow sensing valves and a hydraulic latching mechanism. The latching mechanism holds the control valve in a selected operative position until the hydraulic motor completes its working stroke, the flow sensing valves determining when flow to the hydraulic motor ceases and permitting the application of fluid pressure to unlatch the latching mechanism and allowing the automatic return of the control valve to a neutral position. The flow sensing valves also function as check valves to prevent the return of fluid into the fluid supply line. It is an object of the present invention to provide a hydraulic control valve with a flow sensitive latching mechanism for directing fluid to a hydraulic cylinder, the flow sensitive structure being effective to keep the control valve from unlatching and returning to a neutral position until the piston reaches the end of its stroke, even if the system pressure approaches relief valve pressure during a piston stroke. It is also an object to provide a control valve of the type described, the operation of which is substantially independent of the system pressure, thus permitting system designers to utilize work cylinders smaller in size than heretofore used in systems for a given application. It is another object to provide a control valve that is nearly universal in application and can be used in many systems regardless of the absolute magnitude of the system pressure or of the maximum relief valve pressure. It is an additional object to provide flow sensitive control valves as described that also function as check valves to prevent the return of fluid to the fluid supply line. In summary, the flow sensitive valves prevent the control valve from unlatching and returning to neutral until the work piston reaches a limit of its stroke, even if the system pressure rises to the maximum relief valve pressure during a piston stroke. since the operation is independent of the system relief valve pressure, the control valve of the present invention can be used in nearly any similar hydraulic system. The provision of the flow sensitive valves eliminate the need for a separate reverse flow check valve because the flow sensitive valves block the return flow of fluid into the fluid inlet conduits. such valves may be similarly integrated into a closed center valve as well as the open center system herein disclosed.

                                                                                                    Shanghai Remy Valve Manufacturing Co., Ltd 

2012-01-20 06:31

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