Relief valve assembly; piston member from same and filter head assembly

Abstract

A filter head assembly includes a relief valve assembly therein, and is adapted for use in a spin-on filter or the like. When the relief valve assembly is in a closed mode of operation, fluid flow through the filter head, and an associated filter, results in conventional filtration. When the relief valve assembly is in open mode of operation, the filter is substantially bypassed permitting fluid to flow directly through the filter head, with filtration. The relief valve assembly includes a movable piston member therein, which opens and closes for the respective flow passage outwardly from a lateral takeoff port. Any substantial, undesirable, lateral forces acting upon a piston member may be substantially reduced by means of a lateral pressure release system provided according to the present invention. Generally, the lateral pressure-relief system comprises an annular recess formed in the piston member. The preferred piston member is cup-shaped and has an outer sidewall slide portion which forms a slip fit with a valve body relief valve. The preferred slide member includes groove means therein, facilitating movement. Also, preferably, a first end of the piston member includes an annular portion thereon providing an extension of a first end of the piston member to increase surface area against which fluid pressure may act.