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. 03, 1995
Filed:
Jul. 29, 1994
Satoshi Ishii, Toyota, JP;
Takao Akatsuka, Aichi, JP;
Toyota Jidosha Kabushiki Kaisha, Aichi, JP;
Abstract
A plurality of air-fuel ratio sensors having a temperature characteristic are disposed in an exhaust passage in an engine, with heaters respectively provided in the sensors. The heaters generate heat when energized. An electronic control unit controls the energization of each heater in accordance with the driving conditions of the engine and the temperature condition of the exhaust passage, thereby controlling the amount of generated heat of each heater. As a result, the temperature of each sensor is controlled. When driving conditions allow an interruption to the energization of the individual heaters, the electronic control unit forcibly stops the energization of all the heaters for a predetermined period of time regardless of the energizing status of each heater. Thereafter, the electronic control unit restarts the energization of the heaters one after another, compares the value of the current flowing through each heater in the energizing state with a reference value, and determines the deterioration of the performance of each heater based on the comparison result.