One-piece anti-drainback and relief valve

Claim 1

A fluid filter comprising: a. an outer container having a central axis, a closed end and an open end; b. an end plate secured within the open end of said container, said end plate having a central fluid outlet port and plural fluid inlet ports disposed around the outlet port; c. a hollow, cylindrical filter element enclosed within said container and said end plate; d. a one-piece, combination anti-drainback and relief valve including: i. a cylindrical sleeve movable along the central axis of said container with respect to said end plate, one end thereof being disposed within said filter element, and the other end thereof terminating in a pair of radially spaced, inner and outer tubular extensions, the distal end of said outer extension being spaced from said end plate and the distal end of said inner extension normally engaging said end plate at a position radially inwardly of said inlet ports, said inner extension including a plurality of radially oriented, circumferentially spaced relief ports in communication with said fluid outlet port, wherein said relief ports are normally blocked by an annular, resilient internal lip seal secured to the inner surface of said sleeve, so that when the pressure at said inlet ports exceeds a predetermined amount, said internal lip seal will be deformed radially inwardly, allowing the flow of fluid through said relief ports and exiting through said outlet port; and ii. a resilient annular lip extending from the outer extension of said sleeve to normally engage the end plate radially outwardly of said inlet ports; and e. biasing means disposed within said filter element for normally urging the cylindrical sleeve of said valve into engagement with said end plate.