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:
Mar. 08, 1988
Filed:
Mar. 12, 1987
Katsunori Terasaka, Yokosuka, JP;
Makoto Saitoh, Yokohama, JP;
Nissan Motor Co., Ltd., Yokohama, JP;
Abstract
The invention relates to a control system for feedback control of the air/fuel ratio in an internal combustion engine which uses a three-way catalyst to purify the exhaust gas, and which may be an automotive engine, by using an exhaust sensor to detect actual values of air/fuel ratio in the engine. The control system has the function of varying the target value of air/fuel ratio according to operating conditions of the engine such that the target value becomes super-stoichiometric at least in a portion of a steady zone of the engine operating conditions. The control system includes means to detect the temperature of the three-way catalyst and means to vary the feed of fuel or air to the engine when the catalyst temperature is above a predetermined level, e.g. 750.degree. C., while the target value of the air/fuel ratio is super-stoichiometric such that the actual air/fuel ratio decreases to a predetermined value, e.g. stoichiometric value, which is optimum for the activities of the three-way catalyst, or to a still lower value. Such intentional change in the air/fuel ratio under the high exhaust temperature condition is effective in preventing early deterioration of the three-way catalyst.