Pressure control valve

摘要

A valve of the present invention has housing and a piston member. The piston member is housed in the housing so that it moves between first and positions. The housing includes a piston chamber for guiding the piston member between first and second positions while keeping a sealing engagement with the piston chamber. First and second chambers are positioned adjacent to opposite ends of the piston member so that volumes of first and second chambers are changed depending upon a movement of the piston member. First and second ports are connected when the piston member takes the first position but disconnected when the piston member takes the second position. Third port is connected with the first and second chambers but disconnected from the first and second ports when the piston member takes the first position but connected with the second port when the piston member takes the second position. A partition is defined between the first and second chambers. Also, the partition has an orifice for connecting between the first chamber and the third port.