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:
Jun. 22, 1993
Filed:
Aug. 26, 1991
Noriaki Kurita, Nagoya, JP;
Katsuhiko Nakabayashi, Handa, JP;
Nippondenso Co., Ltd., Kariya, JP;
Abstract
Deterioration of a catalyst of a catalytic converter of an internal combustion engine is detected, during negative feedback control of the air-fuel ratio based on an output signal from at least one of a pair of O.sub.2 sensors disposed respectively upstream and downstream from the catalyst in the exhaust system. Detection is executed after changing the feedback period, which is the period of alternation of a feedback correction coefficient used to control the fuel injection quantity, with the change in period being such as to provide improved accuracy of detection of catalyst deterioration. The change may consist of a single step change, in which the feedback period is set to a specific predetermined value at which the output signal amplitude from the downstream sensor, or the phase difference between the two sensor output signals, should be within predetermined limits if the catalyst is in satisfactory condition.