Patent ID: 8205632
Filing Date: 2012-06-26
Classification: F15B,F16K,Y10T

Abstract:
1. A fluid flow control device comprising: a housing defining an inlet, an outlet and an exhaust port all for an operating fluid; a pilot inlet for receipt of a pilot signal; a supply path in said housing that extends between the inlet and outlet; an exhaust flow path in the housing that extends between the outlet and the exhaust port; a supply valve chamber interrupting the supply path, a supply valve supported in the supply valve chamber for movement between an open position in which it permits fluid to flow through the supply valve chamber from the inlet to the outlet and a closed position where it prevents significant fluid flow through the valve chamber to the outlet; an exhaust valve chamber in the exhaust path, an exhaust valve in the exhaust valve chamber for movement between an open position in which it permits fluid to flow through the exhaust valve chamber from the outlet to the exhaust port and a closed position where it prevents significant fluid flow through the valve chamber to the exhaust port; a reciprocal actuating member in the housing and engageable with the supply valve and the exhaust valve for moving the supply and exhaust valves between the open and closed positions, the actuating member being movable in response to a difference between the pilot signal and the outlet fluid pressure between a first position in which supply valve is closed and exhaust valve is closed, a second position in which the supply valve is open and the exhaust valve is closed, and a third position in which the exhaust valve is open and the supply valve is closed; wherein there is a first fluid leak path defined by the supply valve for allowing fluid to leak through the supply valve chamber when the supply valve is open, a second fluid leak path defined by exhaust valve for allowing fluid to leak through the exhaust valve chamber.