Multi-stage fluid filter, and methods of making and using same

Abstract

A fluid filter increases the useful life of the filtered fluid by removing contaminants therefrom, and may optionally provide for in-line delivery of additives to the filtered fluid. The filter may be an oil filter, a fuel filter, or other fluid filter. The fluid filter includes a casing which defines a hollow space therein, a mechanically active filter element within that space, and a chemically active filter element also retained within the hollow space proximate the mechanically active filter element. The chemically active filter element includes a nonwoven web made up of a plurality of fibers. Each fiber has a longitudinally extending internal cavity formed therein, and a corresponding longitudinally extending slot opening from that internal cavity to the outer surface of the fiber. Preferably each fiber as multiple lobes extending radially outwardly from a central stem, and each lobe cooperates with an adjacent lobe to define a longitudinally extending internal cavity and a corresponding slot therebetween. In order to remove contaminants or to supply additives to lubricating oil, the internal cavities, of each of the chemically active filter fibers, are supplied with a chemical reagent therein.