Patent ID: 6568656
Filing Date: 2003-05-27
Classification: F16K

Abstract:
A flow control valve for a refrigeration system, the valve comprising:(a) a body including an inlet, an outlet, and a passage communicating between said inlet and outlet and a valve chamber; (b) a valve port in the passage defined by a valve seat; (c) a valve assembly movably mounted in the valve chamber, the valve assembly including a piston movable throughout a valve stroke between a closed position in which a piston seat is in abutment with the valve seat and an open position in which the piston seat is spaced from the valve seat, the piston being capable of modulation and subject to imbalance forces throughout the valve stroke; and (d) actuator means for moving the valve assembly toward and away from the valve seat; (e) said piston and said valve seat defining a zone of pressure lower than the inlet pressure when said piston is in the open position, said piston having an equalization passage with an upper port and a lower port, the upper port communicating with the valve chamber during modulation, and the lower port being located to communicate with the zone of lower pressure to reduce imbalance forces experienced by the piston throughout the valve stroke.