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:
Jul. 14, 1998
Filed:
Jun. 04, 1996
Nippondenso Co., Ltd., Kariya, JP;
Abstract
An oxygen sensor has a detecting device unit for outputting a sensor current such as a limiting current of which a value is constant even though a sensing voltage applied to the oxygen sensor changes in a limiting current generating region and corresponds to an air-fuel ratio of a combustion gas and a heater for heating the detecting device unit to keep a resistance of the detecting device unit even though the oxygen sensor is degraded. When the sensing voltage is changed to a second sensing voltage of a resistance governing region, a current peak occurs in the sensor current, and a peak current value is detected. Because the peak current value decreases as the oxygen sensor is gradually degraded, when the peak current value is lower than a degradation judging value, it is judged that the oxygen sensor is degraded. Therefore, the diagnosis of the degradation of the oxygen sensor can be performed with a high accuracy.