Filter elements and filter assemblies with thermal seal

Claim 1

A filter assembly having a filter element in sealing relationship in the assembly through a seal that is thermally expanded at operating temperatures, comprising, in combination, a housing; a fluid chamber in the housing; a fluid inlet and a fluid outlet in the housing in flow communication with the fluid chamber; a cylindrical filter element disposed in the fluid chamber across the line of flow of fluid from the inlet to the outlet through the filter assembly and having a filter sheet in the form of a cylinder whose open ends are capped by end caps having open central passages therethrough; the thermally expanded seal being effected between components consisting of a first cylindrical sealing component operatively associated with each of the end caps of the filter element comprising an annular axial flange extending axially and outwardly from the end caps about the central passages thereof; and a second cylindrical sealing component operatively associated with the filter housing and comprising cylindrical adaptors having on one side a first annular recess into which the annular flanges of the end caps fit; the end cap annular flanges and annular adaptor together constituting first and second thermally sealing components having cylindrical and concentric portions whose opposed mating cylindrical concentric side surfaces are side-to-side sealing surfaces, one adaptor having on its other side a second annular recess; an annular projection on the housing extending into the second annular recess; the second adaptor and annular recess and the housing projection together constituting another set of first and second thermally sealing components having cylindrical and concentric portions whose opposed mating cylindrical concentric side surfaces are side-to-side sealing surfaces; and another adaptor having on its other side a portion keyed with a mating portion on the housing to locate the other side of the filter element with respect to the housing; there being a small clearance between each set of such cylindrical sealing surfaces within the range from about 0.0004 to about 0.002 inch at a first relatively lower nonoperating temperature, and a leak-tight seal between each set of such cylindrical sealing surfaces upon radial expansion of the sealing components at a second relatively higher operating temperature, each of the first and second cylindrical sealing components of each thermal seal having a differential thermal expansion coefficient ΔK t larger than about 1.5×10 -6 per ° C.