Tire valve assembly for central tire inflation system

A tire valve assembly for a central tire inflation system, said tire valve assembly having only two fluid connections thereto, said fluid connections comprising first connection means for fluid connection to a selectively pressurized and exhausted first fluid conduit and second connection means for fluid connection to a second fluid conduit communicating with the interior pressurized chamber of an inflatable tire, said tire valve assembly actuated solely by sensed pressure in said first and second conduits, said valve assembly automatically responsive to fluid pressure in said first conduit exceeding a first reference value and fluid pressure in said second conduit exceeding a minimum tire pressure reference value to establish fluid communication between said first and second conduits, said valve assembly automatically responsive to fluid pressure in said second conduit failing to exceed said minimum tire pressure reference value to block fluid communication between said first and second conduits, said assembly automatically responsive to fluid pressure in said second conduit exceeding a maximum tire pressure reference value to establish fluid communication between said first and second conduits, and said assembly automatically responsive to fluid pressure in said second conduit failing to exceed said maximum tire pressure reference value and fluid pressure in said first conduit failing to exceed said first reference value to block fluid communication between said first and second conduits, said assembly comprising:

• a control valve having a first port fluidly connected to said first conduit, a second port fluidly connected to said second conduit, a first valve seat interposed said first and second ports, a first valve member movable into and out of sealing engagement with said first valve seat, and first resilient means constantly urging said first valve member into sealing engagement with said first valve seat, said first valve member defining a first surface constantly in fluid communication with said first conduit, a second valve surface constantly in fluid communication with said second conduit and a third valve surface having a surface area greater than the surface area of said second valve surface, fluid pressure on said first and second surfaces urging said first valve member out of sealing engagement with said first valve seat and fluid pressure on said third surface urging said first valve member into sealing engagement with said first valve seat, and
• a low tire pressure shut-off valve responsive to fluid pressure in said second conduit, said low tire pressure shut-off valve including a second valve seat interposed said first conduit and said third surface and a second valve member normally biased by fluid pressure in said second conduit to sealingly engage said second valve seat and effective to establish fluid communication between said first conduit and said third valve surface if fluid pressure in said second conduit is not equal to or greater than said minimum tire pressure reference value.

An on-board central tire inflation system comprising a selectively pressurized and exhausted first fluid conduit, a second fluid conduit communicating with the interior pressurized chamber of an inflatable tire, and a tire valve assembly, said tire valve assembly having only two fluid connections thereto, said fluid connections comprising first connection means for fluid connection to said selectively pressurized and exhausted first fluid conduit and second connection means for fluid connection to said second fluid conduit communicating with the interior pressurized chamber of an inflatable tire, said tire valve assembly actuated solely by sensed pressure in said first and second conduits, said valve assembly including valve means automatically responsive solely to fluid pressure in said first and second conduits to:

• (a) establish fluid communication between said first and second conduits if pressure in said first conduit exceeds a first reference valve and pressure in said second conduit exceeds a minimum tire pressure reference value,
• (b) establish fluid communication between said first and second conduits if pressure in said second conduit exceeds a maximum tire pressure reference value,
• (c) block fluid communication between said first and second conduit if pressure in said second conduit fails to exeeed said minimum tire pressure reference value, and
• (d) to block fluid communication between said first and second fluid conduits if fluid pressure in said second conduit fails to exceed said maximum tire pressure reference value and fluid pressure in said first conduit fails to exceed said first reference value.

An on-board central tire inflation system comprising a selectively pressurized and exhausted first fluid conduit, a second fluid conduit communicating with the interior pressurized chamber of an inflatable tire and a tire valve assembly, said tire valve assembly having only two fluid connections thereto, said fluid connections comprising first connection means for fluid connection to said selectively pressurized and exhausted first fluid conduit and second connection means for fluid connection to said second fluid conduit communicating with the interior pressurized chamber of an inflatable tire, said tire valve assembly automatically responsive solely to fluid pressure in said first and second fluid conduits and comprising first valve means responsive to pressurization of said first conduit to at least a first reference pressure and pressurization in said second conduit to at least a predetermined minimum pressurization reference value to establish a fluid communication between said first and second conduits and responsive to exhausting of said first conduit to block fluid communication between said first and second conduit, second valve means constantly communicating with said second conduit and responsive solely to pressurization in said second conduit being less than said predetermined minimum pressurization reference value to retain said first valve means in said blocking condition thereof upon pressurization of said first conduit, said first and second valve means normally communicating to atmosphere only through said first conduit means;

• said first valve means comprising a valve seat located in the path of fluid communication between said first and second conduits and sealed by a valve member resiliently biased by a resilient biasing member thereagainst, a first valve surface having a first surface area constantly exposed to fluid pressure in said first conduit, fluid pressure acting on said first valve surface effective to move said valve member in opposition to said resilient biasing member away from sealing engagement with said valve seat, a second valve surface opposed to said first valve surface and of a second surface area greater than said first surface area, said second valve means effective to establish or block fluid communication between said first conduit and said second valve surface.