Electrically regenerable diesel particulate trap

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.degree. to about 70.degree. 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 having strands wherein each strand has a cross-sectional area in the range from about 0.002 to about 0.25 mm.sup.2 ;
• (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.

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.degree. to about 70.degree. 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 configured to have, when energized, a power concentration in the range from about 2 to about 10 watts/cm.sup.2 ;
• (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.

A diesel particulate filter comprising

• (a) a casing having two ends;
• (b) means for connecting said at least two ends of said casing to an exhaust system;
• (c) at least one filtering element within said casing, said at least one filtering element comprising a plurality of parallel, hollow tubes positioned in a layer, said layer being wound in a spiral, each tube comprising one of woven, braided, or knitted inorganic yarn, said tubes extending between said two ends of said casing said tubes being open at one end and blocked at the other, each of said tubes being integral with one other tube by means of a fold;
• (d) at least one electrically resistive expanded metal sheet, wherein substantially the entire area of each 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 metal, said expanded metal heats to a temperature sufficient to burn soot particles trapped in said at least one filter element after use;
• (e) means for restricting flow of exhaust gases along channels between said adjacent ones of said parallel tubes and between said at least one filtering element and said casing;
• and
• (f) 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.

A diesel particulate filter comprising

• (a) a casing having two ends;
• (b) means for connecting said at least two ends of said casing to an exhaust system;
• (c) at least one filtering element within said casing, said at least one filtering element comprising a continuous hollow tube comprising one of woven, braided, or knitted inorganic yarn, said tube being folded in a zig-zag pattern to provide a layer comprising a plurality of parallel tube segments, wherein ends of said tube segments are defined by folds, said layer being spirally wound such that said ends of said tube segments extend between said two ends of said casing;
• (d) at least one electrically resistive expanded metal sheet, wherein substantially the entire area of each 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 metal, said expanded metal heats to a temperature sufficient to burn soot particles trapped in said at least one filter element after use;
• (e) means for restricting flow of exhaust gases along channels between adjacent ones of said parallel tube segments and between said at least one filtering element and said casing;
• and
• (f) 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.

A diesel particulate filter comprising

• (a) a casing having an inlet end and an outlet end;
• (b) means for connecting said inlet and outlet ends of said casing to an exhaust system;
• (c) at least one filtering element within said casing, said at least one filtering element comprising a plurality of parallel, hollow tubes, each tube comprising one of woven, braided, or knitted inorganic yarn, said tubes extending between said at least two ends of said casing in layers, said tubes being open at one of said inlet end or said outlet end of said casing, and said tubes being blocked at one of said outlet end or said inlet end of said casing;
• (d) at least one electrically resistive expanded metal sheet, wherein substantially the entire area of each 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 metal, said expanded metal heats to a temperature sufficient to burn soot particles trapped in said at least one filter element after use;
• (e) means for restricting flow of exhaust gases along channels between adjacent ones of said parallel tubes and between said at least one filtering element and said casing;
• and
• (f) 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.

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 a plurality of tubes;
• (d) a plurality of substantially rigid tubes extending between said at least two ends of said casing, said tubes each having two ends, an outer surface, and perforations that provide a perforated area, said tubes being supported by said supporting means, wherein said tubes are concentrically spaced and substantially fill said casing radially, and wherein means are provided for blocking alternative spaces adjacent ones of said tubes at ends of said tubes, with each space between said tubes being blocked adjacent to one of said at least tow ends of said casing;
• (e) filtering elements comprising inorganic yarn being substantially helically wound around said tubes to cover said perforations;
• (f) at least one electrically resistive expanded metal sheet, wherein substantially the entire area of each 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 metal, 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 a filtering element and an 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.