Hydraulic valve arrangement with an annular check valve element

摘要

A valve arrangement includes a valve body (20) with a bore (21) within which a spool (44) slides to control fluid flow between first and second ports. The bore has an annular recess (29) into which the first port opens and in which is located a check valve band (83) formed by a strip with overlapping ends. Pressure in the first port causes the check valve band to contract and expand circumferentially to open and close the first port. A stop (95,114,214,312) is located near one end of the strip and is engaged by the other end to limit the amount of contraction of the check valve band. Thus the diameter of the check valve band cannot contract smaller than the diameter of the bore, thereby retaining the check valve ring in the annular recess. The check valve band optionally has a plurality of tabs (88) projecting from each edge and engaging side walls of the annular recess.