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:
Oct. 28, 1997
Filed:
Sep. 05, 1995
Kenji Harima, Susono, JP;
Toyota Jidosha Kabushiki Kaisha, Aichi, JP;
Abstract
This invention is concerned with a fuel-vapor treatment method and apparatus for an internal combustion engine that do not introduce perturbations in the air/fuel ratio during purge-on or purge-off operations. According to the method and apparatus disclosed herein, a sensor output voltage .alpha. (for example, 4.5 V) is set that indicates a catalyst atmosphere neither rich nor lean, or in other words, at stoichiometry. When the present output voltage of a sub O.sub.2 sensor is greater than .alpha., indicating a rich atmosphere, a purge-off operation which entails enrichment is prohibited and a purge-on operation which entails making the atmosphere lean is allowed. Conversely, when the present output voltage of the sub O.sub.2 sensor is not greater than .alpha., indicating a lean atmosphere, a purge-on operation which entails making the atmosphere lean is prohibited and a purge-off operation which entails enrichment is allowed.