Wheel end valve for central tire inflation system

Claim 1

A wheel end valve assembly for a central tire inflation system comprising a valve body having a first fluid connection defined by a first port for connection to a selectively pressurized and exhausted conduit, a second fluid connection defined by a second port for connection to the interior pressurized chamber of an inflatable tire, said valve assembly comprising first valve means responsive to pressurization of said selectively pressurized and exhausted conduit to assume a first position for establishing fluid communication between said first and second ports and responsive to exhausting to atmosphere of said selectively pressurized and exhausted conduit to assume a second position for blocking fluid communication between said first and second ports thereof, said first valve means comprising a valve member having a first surface exposed to fluid pressure at said first port and an opposed second larger surface, said valve assembly comprising second valve means constantly in fluid communication with said second port and responsive to a sensed pressurization of said interior chamber of said tire being less than a predetermined minimum reference pressure and an isolation circuit to conduct fluid from said first port past said second valve means to said second large surface to maintain said first valve means in said second position thereof in response to said sensed pressurization of said tire being less than said minimum reference pressure, said assembly characterized by: a normally opened third valve means in fluid communication with said first port and said isolation circuit thereby maintaining a zero reference pressure differential between said first port and said second larger surface, said third valve means being responsive to a rapid increase in pressure at said first port to close said third valve means and thereby permit said first valve means to open.