Fluid flow control device
First Claim
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.
1 Assignment
0 Petitions
Accused Products
Abstract
A fluid flow control device such as a volume booster 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 diaphragm assembly. The valve stem is operable to open a supply valve between the inlet and outlet and, separately and independently, to open an exhaust valve disposed between the outlet and the exhaust. In a further position both the valves are closed. Movement of the stem in a reciprocal manner by the diaphragm assembly causes a respective annular shoulder to engage a respective valve and lift it off a valve seat against the force of a biasing spring. 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 that allows the valve stem to move easily and the diaphragm assembly to be reduced in size. The arrangement allows the exhaust port to be positioned on the same side of the diaphragm assembly as the inlet and outlet so that fluid can be vented through the exhaust at flow volume comparative to the operating fluid flow in the inlet and outlet.
24 Citations
31 Claims
-
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
- a housing defining an inlet, an outlet and an exhaust port all for an operating fluid;
Specification