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. 22, 1988
Filed:
Sep. 10, 1986
Tomohiko Kawanabe, Wako, JP;
Masahiko Asakura, Wako, JP;
Katsuhiko Kimura, Wako, JP;
Minoru Muroya, Wako, JP;
Honda Giken Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
An air/fuel ratio control system for an internal combustion engine having an air supply system for controlling the air/fuel ratio of mixture to be supplied to the engine, and an oxygen concentration sensing device for sensing the oxygen concentration in the exhaust gas of the internal combustion engine. The oxygen concentration sensing device includes a pair of solid electrolyte members operating as an oxygen pump element to which a pump current is supplied, and a sensor cell element. An open/close valve is provided in the air supply system and controlled by a duty ratio control circuit which causes the open/close valve to be opened for a calculated valve open time period in each of successive predetermined cycles in response to a result of detection of air/fuel ratio. When the calculated valve open time period exceeds a predetermined upper limit, the supply of the pump current is stopped so that the blackening phenomenon of the solid electrolyte members is avoided.