Valve assembly

Claim 1

A valve assembly comprising an elongated body having an axial bore defining an annular valve seat; axially apertured end caps sealed over and secured to opposite ends of said body; said body having a pressure port, cylinder ports and exhaust ports; a valve spool loosely and reciprocally nested within said bore and at its ends sealed and movably supported within said bore, for controlling flow of pressure fluid through the respective ports; a coil spring seated within one end cap and biased against one end of said spool, urging said spool to one control position at one end of said bore; the other end cap adapted for connection to a source of pressurized pilot operating air for moving said spool when energized, to a second control position at the other end of said bore; said spool including an axial portion and a plurality of spaced radially projecting axially spaced valve seal supporting portions intermediate its ends, there being a series of longitudinally spaced pairs of annular grooves in said valve seal supporting portions, each defining an axial seal support of predetermined length; and an annular apertured valve seal of flexible material loosely nested in each groove, and loosely mounted upon said axial supports, respectively; the base of each seal having an axial width less than the length of each axial seal support; each seal having an annular rim portion of decreasing width towards its periphery and transversely rounded at its outer edge, and of a diameter greater than said bore for flexing sealing engagement with said valve seat relative to said ports to form a fluid-tight contact with said bore; said rim portions of said seals being movable over said valve seal with a minimum of friction and said seal bases adapted for limited axial movement on said axial supports, reducing the resistance of said spool to reciprocal control movements thereof, said seal rim outer edges rolling on said body to facilitate break-away therefrom, air pressure applied to said pressure port operatively acting upon the adjacent seals expanding them against said valve seat, creating a bubble-tight seal on said bore; the sealing and supporting of said spool including annular channels adjacent opposite ends of said spool; and a flexible O-ring nested in each channel and projecting radially outward of said spool spacing said spool from said valve seat and serving as the sole support of said spool within said bore, said spool floating within said bore; the rim of each valve seal being of low resiliency hard frictionless material of high Durometer creating a diaphragm action, the base of each seal being of increased resiliency and of a lower Durometer for ease of flexiblity and expansion upon its axial support.