The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 14, 1990
Filed:
Aug. 23, 1988
Hans Erdmannsdorfer, Ludwigsburg, DE;
Helmuth Fischer, Ludwigsburg, DE;
Helmut Rocker, Lochgau, DE;
Hartmut Wolff, Remseck, DE;
Fritz Zundel, Besigheim, DE;
Filterwerk Mann & Hummel GmbH, Ludwigsburg, DE;
Abstract
A process is described for producing filter elements which contain a cross-wound yarn as the filter material, wherein twisted yarn of fine individual fibers is roughened to enhance its filtering action. The yarn may be heat-resistant and the filter element may be used as a soot filter in the exhaust gas stream of an internal combustion engine. Before the yarn is wound up, fiber tufts are broken up by pulling the yarn under tension over a moving roughening surface, the direction of movement of the roughening surface differing by an angle alpha from the direction of movement of the yarn in the area of contact between the yarn and the roughening surface, and the angle alpha being selected in relation to the twist of the yarn, particularly so that the threads of the yarn in contact with the roughening surface are oriented transversely to the direction of movement of the roughening surface. The process produces a roughened yarn which provides the required high filter performance for a soot filter.