Patent ID: 7085671

Claim:
An abnormality detection apparatus of an engine temperature adjusting thermostat in which a temperature of cooling water of an engine is compared with a predetermined limit temperature to detect abnormality in operation of said thermostat for opening and closing a cooling water circulation passage of said engine, said apparatus comprising: a heat amount parameter detection section for detecting an operating condition related to an amount of heat generated by said engine as a heat amount parameter; an abnormality determination section for comparing said temperature of cooling water with a predetermined allowable lower limit to determine abnormality of said thermostat when said heat amount parameter reaches a reference heat amount; a small heat amount determination section for determining whether the amount of heat generated by said engine is in a small amount state; a large heat amount determination section for determining whether the amount of heat generated by said engine is in a large amount state; and an abnormality determination prohibition section for disabling said abnormality determination section when at least one of the small amount state and the large amount state of said amount of heat is determined, wherein said heat amount parameter detection section detects the amount of intake air of said engine as said heat amount parameter; said small heat amount determination section compares a first reference intake air amount related to at least one of said starting time cooling water temperature and said intake air temperature of said engine with the amount of intake air of said engine, and determines said small amount state of said heat amount when the amount of intake air being not greater than said first reference intake air amount is detected said first predetermined number of times or more within said first predetermined period of time; and said large heat amount determination section compares a second reference intake air amount related to at least one of said starting time cooling water temperature and said intake air temperature of said engine with the amount of intake air of said engine, and determines the large amount state of said heat amount when the amount of intake air being not less than said second reference intake air amount is detected said second predetermined number of times or more within said second predetermined period of time.