Check valve structure

Claim 1

A self cleaning check valve that permits fluid that may have solid particles entrained therewith to flow from a first zone to a second zone when the pressure on fluid in said first zone exceeds a predetermined magnitude, said check valve including: a. a valve body that has first and second passages and an elongate confined space defined therein that communicate with one another, said first passage and confined space axially aligned, a circular valve seat of semi-circular transverse cross section inside said body in which said first passage terminates, and said first and second passages in communication with said first and second zones; b. (a) an elongate cylindrical valve member slidably movable in said confined space, said valve member having first and second ends, said first end partially defined by a circular rib of hook shape transverse cross section, said rib having a transverse passage therein, and a circumferential recess on the exterior of said valve member that communicates with said passage; c. a head supported from said first end and situated within and radially spaced from said rib, said head defined by a generally cylindrical sidewall and an end face that intersect to provide a circular knife edge of such diameter that said knife edge is centered on said valve seat when said valve member is in a first position, said head formed from a rigid material harder than said particles, and said knife edge either severing or displacing those of said particles deposited on said valve seat when said valve member is in said first position; d. deformed spring means in said confined space that maintain said valve member in said first position until the pressure of fluid of said predetermined magnitude in said first zone exerts a force on said face of said head that is greater than the force exerted by said spring means on said valve member; and e. a first resilient sealing ring that grips said side wall and is disposed in a circumferential space defined on said first end of said valve member between said rib and side wall of said head, said valve member due to said recess having a dynamic lift imparted thereto that disposed said valve member at a second position substantially within said confined space where said sealing ring is exposed to a minimum abrasive action by said particles when said fluid flows at high velocity through said first passage, valve seat and second passage upon said fluid in said first zone exceeding said predetermined magnitude in pressure, with said valve member being moved by said spring means from said second to said first position when said pressure of said fluid in said first zone falls below said predetermined magnitude, with pressurized fluid in said second zone after said valve member returns to said first position flowing into said recess and through said passage into said circumferential space to exert an inwardly directed pressure on said first sealing ring to increase the force that urges said first sealing ring into sealing contact with said valve seat.