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. 16, 1999
Filed:
Jun. 20, 1997
Satoru Taniguchi, Okazaki, JP;
Kazunori Katoh, Nagoya, JP;
Koichi Mizutani, Toyota, JP;
Hideo Mori, Toyota, JP;
Toyota Jidosha Kabushiki Kaisha, Toyota, JP;
Abstract
In the present invention, the cooling water temperature sensor is diagnosed using a warming up counter WCT. The value of WCT is increased by the increment WCTINC at predetermined intervals after the engine is started. The increment value WCTINC is determined in accordance with the engine operating parameters affecting the rising rate of the cooling water temperature such as the cooling water temperature when the engine is started, the ambient temperature and the engine load. Therefore, the value of the warming up counter accurately corresponds to the actual cooling water temperature. In the diagnosis operation, when the value of the counter WCT reaches a predetermined setting value, the cooling water temperature detected by the cooling water temperature sensor is compared with a reference temperature which corresponds to the setting value of the warming up counter. If the detected cooling water temperature is lower than the reference temperature, the cooling water temperature sensor is determined to have failed. Since the warming up counter which increases at a rate corresponding to the actual rising rate of the cooling water temperature is used, an accurate diagnosis of the cooling water temperature sensor is performed.