Hydraulically-controlled changeover valve for hydraulic medium - acts as reinforcement to electromagnetically controlled valve to increase amt. of medium which can be controlled

摘要

A movable valve ring (13) base (41) has circular collars (40a,40b). The sealing surfaces of the ring (13) are formed through the end surfaces (39a,39b) of the collars. A sealing groove (23a,23b) is worked into each valve seat (6a,6b) to serve to introduce or lead away the hydraulic medium. The width of each of these grooves over the double seat covering is smaller than that of the collars of the movable valve part. No hydrostatic force acts on the control piston (15) when the movable valve part (12) is at the control bore (29) connected to the control chamber of an electromagnet. If the electromagnetic valve switches over, control pressure reaches the control piston chamber (31) via bores (29,30). The hydrostatic power now applied to the piston overcomes the reaction of the return spring ring (10). ADVANTAGE - Reinforcement factor in the range of 50 without switching-over time exceeding a millisecond.