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. 26, 2002
Filed:
Sep. 18, 2000
Shigeki Nakayama, Susono, JP;
Hiroki Matsuoka, Susono, JP;
Kohei Igarashi, Susono, JP;
Hiroshi Suwahara, Toyota, JP;
Toyota Jidosha Kabushiki Kaisha, Toyota, JP;
Abstract
A three-way catalyst device having an oxygen absorbing/releasing capability is provided in an exhaust passage of an internal combustion engine. An upstream-side air-fuel ratio sensor that outputs an output value in accordance with the air-fuel ratio of exhaust gas is provided in the exhaust passage upstream of the three-way catalyst device. A downstream-side air-fuel ratio sensor that outputs an output value in accordance with the air-fuel ratio of exhaust gas is provided in the exhaust passage downstream of the three-way catalyst device. A comparison value is calculated by comparing the length of an output locus formed by output values of the upstream-side air-fuel ratio sensor and the length of an output locus formed by output values of the downstream-side air-fuel ratio sensor. By comparing the comparison value with a predetermined criterion, it is determined whether the three-way catalyst device has deteriorated. At least one of the downstream-side air-fuel ratio sensor output value and the predetermined criterion is corrected in accordance with the downstream-side air-fuel ratio sensor output value. Therefore, deterioration of the three-way catalyst device can be determined with high precision.