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:
Nov. 02, 2004
Filed:
Oct. 22, 2002
Brian W. Geiser, Shelby Township, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
An engine includes cams for actuating intake and exhaust valves controlling transport of air and combustion products to and from a combustion chamber of the engine. The cams have valve opening and closing curves capable of being timed so that the intake valve opening curve partially overlaps the exhaust valve closing curve, allowing retention of some combustion products in the combustion chamber with an incoming air charge. At least one of the cams has variable timing to vary the valve overlap for controlling the amount of exhaust gas retention or recirculation (EGR). The overlapping portions of the cam opening and closing curves are extended to provide a relatively linear variation in valve overlap area over the range of cam variable timing. Thus, variation of exhaust gas retention in the combustion chamber becomes a relatively constant function of the duration of valve overlap in each engine cycle and control of the amount of EGR is improved.