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:
Feb. 26, 2002
Filed:
Nov. 30, 1998
Pierre Bonny, Hamburg, DE;
Thomas Huelsberg, Rosengarten, DE;
DaimlerChrysler AG, Stuttgart, DE;
Abstract
A method for manufacturing an air-gap-insulated exhaust pipe having a branch stub, as well as an exhaust pipe produced according to such a method and a tool for forming such an exhaust pipe. Two tubes are inserted into one another to form a double tube. The double tube is placed in a first internal high-pressure shaping tool, and exposed to internal high pressure fluid such that it expands to match the contours of the engraving of the first shaping tool, and a double-walled branch stub is blown out of the double tube. The partially formed double tube is then placed in a second internal high-pressure shaping tool, with the double tube being surrounded, between the two ends including the branch stub, circumferentially and throughout by a corresponding design of the engraving, by an expansion chamber. The outer tube is expanded between the outer tube and inner tube under high pressure up to a precise fit with the engraving of the second shaping tool to form an insulating air gap, with the end of the branch stub being supported externally without yielding via a second counterpunch. The finished double tube is removed from the second shaping tool and a cap area of the branch stub, containing the end, is cut off to form a through opening between the interior of the inner tube and the ambient environment outside the air-gap-insulated exhaust pipe.