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.

Date of Patent:
Feb. 25, 1997

Filed:

Oct. 20, 1994
Applicant:
Inventors:

Yoichi Iwata, Wako, JP;

Yoshiharu Ave, Wako, JP;

Takayoshi Nakayama, Tochigi-ken, JP;

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
F01N / ;
U.S. Cl.
CPC ...
60276 ; 60285 ;
Abstract

An air-fuel ratio control system for an internal combustion engine comprises upstream and downstream O2 sensors arranged in the exhaust system of the engine at respective locations upstream and downstream of a catalytic converter, for detecting concentration of oxygen in exhaust gases from the engine. An ECU sets a control variable having a value proportional to the difference between an output from the downstream O2 sensor and a first predetermined reference value, and compares between an output from the upstream O2 sensor and a second predetermined reference value, to thereby calculate an air-fuel ratio correction coefficient, based on results of comparison and the set control variable. The air-fuel ratio of an air-fuel mixture supplied to the engine is controlled based on the calculated air-fuel ratio correction coefficient.


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