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:
Jun. 13, 1995
Filed:
Jul. 16, 1993
Koichi Namiki, Kyoto, JP;
Takuya Matsumoto, Kyoto, JP;
Toru Hashimoto, Kyoto, JP;
Yasuhisa Yoshida, Okazaki, JP;
Mitsubishi Jidosha Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
A failure determination method for an O.sub.2 sensor is provided wherein the air-fuel ratio of a mixture is maintained at a value which produces a leaner or richer air-fuel ratio than a stoichiometric ratio by a predetermined value, for a predetermined time after an engine starts operating in an idle region, to thereby make the oxygen concentration of exhaust gas surrounding the O.sub.2 sensor uniform. Subsequently, the air-fuel ratio is forcibly subjected to an oscillatory change with a predetermined amplitude of .+-.10 to 15% of the stoichiometric ratio with respect to the stoichiometric ratio at a predetermined frequency of several Hz, to determine abnormality of the O.sub.2 sensor based on the change of the output voltage of the O.sub.2 sensor.