Electrohydraulic valve device several ways to control provisions mining shoring subterranea

摘要

A three-port, two-position electrohydraulic valve has an elongated valve member reciprocatably guided in a bore of the valve housing only by two sealing rings of small friction and including only two further sealing rings cooperating with sealing edges respectively provided on the valve member and the housing for controlling fluid flow between the three ports. The valve member is reciprocated between two end positions against the force of a return spring by an electromagnet. Such a valve requires only small forces for reciprocation of its elongated valve member, so that a small electromagnet is sufficient. The valve of the present invention favorably differs from known electrohydraulic three-port, two-position valves which are constructed as seat valves and operated in opening direction by an electromagnet of long stroke and which require also considerable forces during operation, due to large friction forces inherent with seat valves.