Electrically regenerable diesel particulate trap

Claim 1

A diesel particulate filter comprising (a) a casing having at least two ends; (b) means for connecting said at least two ends of said casing to an exhaust system; (c) means for supporting at least one tube; (d) at least one substantially rigid tube extending between said at least two ends of said casing, said at least one tube having two ends, an outer surface, and perforations that provide a perforated area, said at least one tube being supported by said supporting means; (e) at least one filtering element within said casing, said at least one filtering element comprising inorganic yarn, said inorganic yarn being substantially helically cross-wound around said at least one tube to cover said perforations, wherein said inorganic yarn comprises a core from which at least one of loops of continuous fibers or fiber segments extend outwardly, wherein successive convolutions are oppositely wound in each layer to provide interwoven cores, cores of successive convolutions of each successive layer are radially aligned to provide walls that are spaced to define four-sided openings, said walls providing stabilization to said filtering element against exhaust forces, wherein said convolutions of said yarn at said perforated area of said at least one tube extend at an angle in the range from about 30° to about 70° to the axis of said tube in each winding direction, and wherein said at least one of loops of fibers or said fiber segments project into each of said four-sided openings, with at least one of loops of fibers or fiber segments of adjacent convolutions being intermeshed to provide with each of said four-sided openings a trap for diesel exhaust particulates; (f) at least one electrically resistive expanded metal sheet having two major faces, wherein substantially each major face of said at least one expanded metal sheet is in contact with said at least one filtering element, said at least one expanded metal sheet being sufficiently electrically resistive such that when a voltage is applied across said expanded meal, said expanded metal heats to a temperature sufficient to burn soot particles trapped in said at least one filter element after use; (g) means for forcing exhaust gases to pass through both said at least one filtering element and said at least one expanded metal sheet; and (h) means for applying a voltage across said at least one expanded metal sheet to heat it above the combustion point of entrapped diesel exhaust particulates.