| CPC F01P 11/16 (2013.01) [F01P 7/16 (2013.01); G01N 25/72 (2013.01); F01P 2031/32 (2013.01)] | 20 Claims |
|
1. An abnormality diagnosis device of a thermostat that opens and closes a cooling water passage, according to a temperature of cooling water of an engine, and switches between availability and unavailability of flow of the cooling water to a heat release device, comprising:
a temperature detection module that detects the temperature of the cooling water on a basis of a sensor signal of a cooling water temperature sensor;
an abnormality determination module that detects an abnormality of the thermostat, when the temperature of the cooling water reaches a first reference temperature at which warm-up of the engine is completed and thereafter decreases from the first reference temperature to fall below an abnormality determination reference temperature that is lower than the first reference temperature; and
a cooling water temperature adjustment module that prevents decrease of the temperature of the cooling water to the abnormality determination reference temperature before the temperature of the cooling water reaches the abnormality determination reference temperature, when the temperature of the cooling water first reaches the first reference temperature at which the warm-up of the engine is completed and thereafter decreases from the first reference temperature to fall below a second reference temperature, wherein
the second reference temperature is set to start a control to prevent the decrease of the temperature of the cooling water, and
the second reference temperature is lower than the first reference temperature and is higher than the abnormality determination reference temperature.
|