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:
May. 22, 2001
Filed:
Mar. 21, 2000
Nissan Motor Co., Ltd., Yokohama, JP;
Abstract
A primary deterioration diagnosis of a front catalyst (,) is performed based on the air-fuel ratio of the exhaust gas downstream of the front catalyst (,) detected in a first period each time the first period elapses when the engine (,) is running in a diagnosis region. A secondary deterioration diagnosis of the front catalyst (,) is performed based on the air-fuel ratio of the exhaust gas downstream of the front catalyst (,) detected in a second period longer than the first period each time the second period elapses when the engine (,) is running in the diagnosis region. When SOx discharge control is performed, primary diagnosis and secondary diagnosis are prohibited, and if it is determined in the primary diagnosis that the front catalyst (,) has deteriorated, SOx discharge control is prohibited to provide an opportunity for secondary diagnosis. In this way, the deterioration diagnosis of the front catalyst (,) can be precisely performed even if there are few opportunities for diagnosis due to lean air-fuel ratio running or SOx discharge control.