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.

Date of Patent:
Aug. 28, 2001

Filed:

Dec. 11, 1997
Applicant:
Inventors:

Tatsuya Oka, Kariya, JP;

Keiji Wakahara, Kariya, JP;

Akira Ichikawa, Chiryu, JP;

Assignee:

Denso Corporation, Kariya, JP;

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01M 1/500 ;
U.S. Cl.
CPC ...
G01M 1/500 ;
Abstract

Malfunction of an engine coolant thermostat is detected from the engine side coolant temperature by the subsequent behavior of the coolant temperature. When an open-malfunction occurs, the coolant temperature becomes considerably different from that normally expected for times at which the thermostat is expected to be closed. When a closure-malfunction occurs, the coolant temperature becomes considerably different from that normally expected for times at which the thermostat is expected to be opened. Alternatively, the malfunction may be detected from the difference between the engine side coolant temperature and the radiator side coolant temperature.


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