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:
Feb. 05, 2002
Filed:
Nov. 23, 1999
Toyota Jidosha Kabushiki Kaisha, Toyota, JP;
Abstract
Under normal conditions, the temperature of an oxygen ion-conductive element provided in a sensor body is about 700° C., and the element impedance is about 30 &OHgr;. If there is a fault in the sensor body or a sensor body drive circuit, the current becomes zero and the element impedance becomes infinite. If a heater has deteriorated, the element temperature rises only up to, for example, about 550° C., and the element impedance becomes about 150 &OHgr;. If there is a fault in the heater or the heater drive circuit, the element is heated only by exhaust gas, so that the element temperature rises only up to about the temperature of exhaust gas and the element impedance becomes a value corresponding to an element temperature of about 300° C. Three reference values Z1, Z2, Z3 are set for comparison with the detected value of element impedance in order to perform fault diagnosis.