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:
Aug. 02, 1994
Filed:
Mar. 31, 1993
Tokiji Itoh, Toyota, JP;
Toyota Jidosha Kabushiki Kaisha, Toyota, JP;
Abstract
A secondary air supplier supplies secondary air to an exhaust passage, when an engine is in a predetermined condition. An oxygen sensor detects the air-fuel ratio (A/F) in the exhaust gas. The air-fuel ratio indicates either a rich condition or a lean condition. When the engine is cold, a time counter measures a lean period of time, while secondary air is supplied. When the lean period exceeds a predetermined period of time, a diagnostic system determines that the secondary air supplier is functioning properly. If the oxygen sensor detects that the ratio (A/F) indicates a rich condition during the diagnosis, then the time counter stops measuring the lean period, with keeping the total measured lean period. When the engine is hot, the ratio of the lean period to a predetermined period for the secondary air supply could be smaller than a predetermined ratio, and the diagnostic system determines that the air supplier is malfunctioning.