Pilot-operated quick exhaust valve

摘要

A fluid flow control device has an inlet, an outlet and an exhaust port all for an operating fluid. A pilot inlet receives a pilot pressure signal which operates a valve stem actuator via a piston. The valve stem is operable to open a supply valve between the inlet and outlet and, to open an exhaust valve disposed between the outlet and the exhaust. In a further position both the valves are closed. A first fluid leak path is provided between the valve stem and the supply valve for allowing fluid to leak through the supply valve chamber when the supply valve is open and a second fluid leak path is defined by the exhaust valve for allowing fluid to leak through the exhaust valve chamber. The leak paths provide for a force balancing arrangement. A quick exhaust feature allows exhaust flow through the device.

主权项

1. A pilot-operated quick exhaust valve for exhausting fluid from a fluid actuator and comprising:
a housing; the housing defining an inlet port for connection to an exhaust of the fluid actuator, a pilot control port for receipt of a pilot control signal and at least one exhaust port; a valve assembly reciprocal within the housing and comprising a piston connected to a valve member; the piston being disposed in the housing to define on a first side of the piston a variable volume pilot pressure chamber in fluid communication with the pilot port and, on a second side of the piston, a variable volume inlet pressure chamber in fluid communication with the inlet port, such that the piston is moveable in response to a pressure difference between the pilot port and the inlet port; the valve member being moveable with the piston between a first position in which it blocks fluid communication between the at least one exhaust port and the inlet port and a second position in which it opens the at least one exhaust port to allow for a maximum flow from the inlet and out through the at least one exhaust port; an elongate valve stem; wherein the piston is fixed to the valve stem and the valve member is movable relative thereto in the direction of a longitudinal axis of the stem; and wherein the valve member is biased to the first position by a biasing member, and movement of the piston in a direction such that the pilot pressure chamber decreases in volume moves the valve member towards the second position against the biasing force applied by the biasing member.