Patent ID: 9534527
Date: 2017-01-03
CPC Classifications: F01P

Claim:
1. A thermostat failure detection device for detecting a failure of a thermostat provided in a cooling water flow passage of an internal combustion engine system, comprising: a normal-time minimum water temperature calculator for sequentially calculating an engine water temperature, the engine water temperature is referred to as a “normal-time minimum water temperature” hereinafter, on an assumption that the thermostat is normal and an internal combustion engine is operated in a state where a radiator shutter is fully open; a failure-time maximum water temperature calculator for sequentially calculating the engine water temperature, the engine water temperature is referred to as a “failure-time maximum water temperature” hereinafter, on an assumption that the thermostat is in a stuck-open failure state and the internal combustion engine is operated in a state where the radiator shutter is fully closed; and a determiner for determining the failure of the thermostat if the engine water temperature is lower than the normal-time minimum water temperature, determining the normality of the thermostat if the engine water temperature is higher than the failure-time maximum water temperature and determining that the engine water temperature is not within the range that enables failure and normality determination if the engine water temperature is between the normal-time minimum water temperature and the failure-time maximum water temperature.