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:
Jul. 04, 2006
Filed:
Dec. 02, 2004
Hideki Takubo, Tokyo, JP;
Akira Demizu, Tokyo, JP;
Hideki Takubo, Tokyo, JP;
Akira Demizu, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
To obtain an air-fuel ration control apparatus for an internal combustion engine capable of maintaining an NOx purification rate at a high level when a catalyst is in a deteriorated condition. The air-fuel ratio control apparatus includes: an oxygen concentration sensor for detecting an oxygen concentration at a position upstream of a catalyst; an oxygen concentration sensor for detecting an oxygen concentration at a position downstream of the catalyst; an injector drive unit for adjusting an amount of a fuel supplied to an internal combustion engine; a first air-fuel ratio control unit for controlling the injector drive unit such that the air fuel ratio at the position upstream of the catalyst matches a first target air-fuel ratio; a second air-fuel ratio control unit for setting the first target ratio such that the air fuel ratio at the position downstream of the catalyst matches a second target air-fuel ratio; and a target air-fuel ratio setting unit for setting the second target air-fuel ratio. The target air-fuel ratio setting unit sets the second target air-fuel ratio at a value on a rich side of a stoichiometric air-fuel ratio such that an NOx purification rate is a maximum in view of NOx purification rate characteristics when the catalyst is in a deteriorated condition.