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:
Apr. 03, 1990
Filed:
Jan. 11, 1988
Masaaki Uchida, Yokosuka, JP;
Shisei Kai, Yokosuka, JP;
Nissan Motor Company Limited, Yokohama, JP;
Abstract
An air-fuel ratio control system for controlling the air-fuel ratio of air-fuel mixture to be inducted into an automotive engine in order to accomplish feedback control of the air-fuel ratio into a stoichiometric level of feedforward control of the air-fuel ratio into a lean level. The air-fuel ratio control system is comprised of a control unit which is electrically connected to an oxygen sensor for detecting the air-fuel ratio and to a variety of sensors for detecting engine operating condition. The control unit is adapted to calculate an air-fuel ratio correction coefficient in accordance with the detected air-fuel ratio. The feedback control of the air-fuel ratio is accomplished in accordance with the air-fuel ratio correction coefficient. The control unit is further adapted to form a plurality of learning areas defined respectively by engine operating conditions. Learning is made in each learning area. At least a part of each learning area is under the feedback control. The control unit is adapted to further calculate a learning coefficient for the learning area corresponding to the detected engine operating condition, in accordance with the air-fuel ratio correction coefficient under the feedback control. The learning coefficient is memorized in the above-mentioned at least a part of each learning area. The feedforward control of the air-fuel ratio is accomplished in accordance with the learning coefficient in the learning area corresponding to the detected engine operating condition, thereby improving the precision of control in the feedforward control of the air-fuel ratio.