Dual flow and dual stage lubricant filter assembly

Abstract

A filter assembly for an internal combustion engine includes inner and outer coaxial filter elements disposed in a spin-on canister which is detachably secured to a mounting adaptor. Oil from the crankcase is filtered by the outer filter element and a substantial volume of the filtered oil flows to the primary lubricating circuit of the engine. A small percentage of the filtered oil is subjected to further filtration by the inner filter element and is returned directly to the crankcase. A tubular fitting extends between end caps on the two coaxial filter elements to establish communication between the inner filter and the mounting adaptor, to separate the two flow circuits, and to maintain a fixed axial spacing between the two filter elements.