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. 13, 2007
Filed:
Jan. 06, 2006
Keiichi Enoki, Tokyo, JP;
Kuen Yehliu, Tokyo, JP;
Keiichi Enoki, Tokyo, JP;
Kuen Yehliu, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A device includes: downstream air-fuel ratio feedback control unit that performs feedback control of an upstream target air-fuel ratio so that a downstream air-fuel ratio detected by a downstream air-fuel ratio detecting unit coincides with a downstream target air-fuel ratio; a target air-fuel ratio varying unit that varies the upstream target air-fuel ratio at the time of diagnosing degradation of a ternary catalyst; and a catalyst degradation judging unit that judges catalyst degradation from the behavior of the downstream air-fuel ratio at the time of diagnosing degradation of the ternary catalyst. When diagnosing degradation of the ternary catalyst, the downstream air-fuel ratio feedback control unit is stopped or its control constant is set at a smaller value. Thus, when varying the air-fuel ratio for diagnosing catalyst degradation, interference between downstream air-fuel ratio feedback and upstream air-fuel ratio feedback is prevented and catalyst degradation is accurately diagnosed.