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. 19, 1991
Filed:
Jun. 21, 1990
Shinpei Nakaniwa, Gunma, JP;
Japan Electronic Control Systems Co., Ltd., Isezaki, JP;
Abstract
A system and method for controlling an air/fuel mixture ratio of an air mixture fuel sucked into an internal combustion engine are disclosed in which an operating variable (PL, PR) of an air/fuel mixture ratio feedback correction coefficient (LAMBDA) is controlled so as to compensate for the deviation of the air/fuel mixture ratio (an average air/fuel mixture ratio) from a target air/fuel mixture ratio (stoichiometric air/fuel mixture ratio) according to an output characteristic variation of an oxygen sensor installed in an exhaust passage, the oxygen sensor outputting a voltage according to the air/fuel mixture ratio. A degree of deterioration of the oxygen sensor, i.e., the output characteristic variation of the oxygen sensor is determined according to a response balance between a rich side response and lean side response of the oxygen sensor, the response balance being determined on the basis of at least one of a plurality of parameters, a first parameter being a speed of change in the output voltage of the oxygen sensor, a second parameter being a duration of time during which the air/fuel mixture ratio is started to change toward the target air/fuel mixture ratio, and a third parameter bein the rich and lean control durations of time during which the system controls the air/fuel mixture ratio toward the target air/fuel mixture ratio with the feedback correction coefficient (LAMBDA).