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. 25, 1992
Filed:
Dec. 13, 1990
Nippondenso Co., Ltd., Kariya, JP;
Abstract
An air-fuel ratio control apparatus for an engine for controlling a fuel injection amount so that an air-fuel ratio of a mixture gas which is supplied to the engine is set to a stoichiometric air-fuel ratio is disclosed. The apparatus has a first oxygen concentration sensor on the upstream side of a catalyst arranged in an exhaust pipe of the engine and a second oxygen concentration sensor on the downstream side, respectively. The first sensor gives to the apparatus a first linear detection signal for the air-fuel ratio of the mixture gas. The second sensor gives to the apparatus a second detection signal indicating whether the air-fuel ratio of the mixture gas is rich or lean for the stoichiometric air-fuel ratio. A target air-fuel ratio is set in accordance with the second detection signal and the first detection signal and the target air-fuel ratio are compared, thereby controlling a fuel injection amount. Thus, a deviation between the actual air-fuel ratio and the first detection signal can be accurately corrected and the air-fuel ratio can be accurately controlled to a value in a region where a high purification factor of the catalyst is derived.