Patent ID: 6220271
Filing Date: 2001-04-24
Classification: B60T,F04F,G05D,Y10T

Abstract:
A check valve apparatus for maintaining negative pressure in an operating system, said check valve comprising:an inlet connectable to an operating system requiring a negative pressure, and an outlet connectable to a system producing a negative pressure;a main air channel establishing an air flow path between said inlet and said outlet;a first check valve disposed in said main air channel;an outside air channel having one end in communication with said main air channel at a location downstream of said first check valve in a direction of air flow through said main air channel to said outlet, said outside air channel in communication with atmospheric pressure at an opposite end thereof;a cross-sectional narrowing defined in said outside air channel with a venturi channel disposed between said cross-sectional narrowing and said main air channel;a second check valve disposed in communication between said main air channel and said cross-sectional narrowing;an automatic shut off valve disposed in said outside air channel to alternately isolate and open said outside air channel to atmospheric pressure as a function of system pressure in the operating system; anda sensor disposed to sense operating system pressure and a control device in communication with said sensor and said shut off valve to control said shut valve in response to sensed operating system pressure.