Anti-cavitation and overload relief valve for a hydraulic system

摘要

A hydraulic system including at least one hydraulic cylinder is provided with an anti-cavitation and overload relief valve having a housing, a first chamber within the housing in fluid communication with one end of the cylinder, and a second chamber within the housing in fluid communication with a fluid reservoir. A fluid passageway within the valve housing connects the first and second chambers. A movable valve assembly is positioned within the fluid passageway for operating in a first mode to block fluid flow between the first and second chambers, for operating in a second mode to permit fluid flow from the first chamber to the second chamber only when the pressure in the first chamber exceeds the pressure in the second chamber by a first predetermined amount, and for operating in a third mode to permit fluid flow from the second chamber to the first chamber only when the pressure in the second chamber exceeds the pressure in the first chamber by a second predetermined amount. The valve includes a stationary portion positioned within the fluid passageway between the first and second chambers having a valve seat. The movable valve assembly includes a movable valve element having a sealing portion for engaging the valve seat of the stationary portion when the movable valve assembly is operating in the first and second modes. The movable valve assembly further has a valve seat and a poppet mechanism is provided for sealingly engaging the valve seat of the movable valve element when the movable valve assembly is operating in the first and third modes.