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. 11, 2008
Filed:
Aug. 07, 2006
Kenji Tashiro, Toyota, JP;
Kenji Tashiro, Toyota, JP;
Toyota Jidosha Kabushiki Kaisha, Toyota-shi, JP;
Abstract
An air-fuel ratio sensor has an exhaust-side electrode and an atmosphere-side electrode. The atmosphere-side electrode is disposed in an atmosphere layer that communicates with the atmosphere. Since the air-fuel ratio sensor is disposed in an exhaust passage, exhaust gas enters the atmosphere layer if a sensor crack occurs. Ordinarily, forward voltage is applied to the air-fuel ratio sensor to obtain an output thereof in accordance with the air-fuel ratio. Immediately after the applied voltage is switched to reverse voltage, sensor current iin accordance with the impedance flows, regardless of the presence/absence of a sensor crack. After that, the sensor current converges to a value ithat is in accordance with the oxygen concentration in the atmosphere layer. The presence/absence of a sensor crack is determined by comparing the value obtained by correcting iby i, with a criterion value.