Patent ID: 7325447
Filing Date: 2008-02-05
Classification: F01P

Abstract:
1. A cooling apparatus for an internal combustion engine, the cooling apparatus comprising: a radiator through which a coolant passes; a thermostat operating in such a manner as to control a supply of the coolant to the radiator; a temperature detector detecting a temperature of the coolant; an estimating section estimating a reference temperature corresponding to the temperature of the coolant on the basis of at least a vehicle speed; an diagnosing section diagnosing an operating state of the thermostat on the basis of a comparison between the detected temperature and the reference temperature in the case that a predetermined diagnosis condition is established; and an inhibiting section inhibiting the diagnosis of the operating state of the thermostat in the case that any one of the following conditions i) to iii) is satisfied. i) a rate of a descending slope traveling time with respect to a time until the diagnosis condition is established from the start of the internal combustion engine is greater than or equal to a determination value, in which the descending slope traveling time indicates a time for which a vehicle is under the descending slope traveling state; ii) a rate of the descending slope traveling time with respect to a general traveling time is greater than or equal to a determination value, in which the general traveling time indicates a time for which the vehicle is under any traveling state other than the descending slope traveling state; and iii) a rate of a time of a specific state with respect to the time until the diagnosis condition is established from the start of the internal combustion engine is greater than or equal to a determination value, in which the specific state indicates a state in which a speed of the vehicle is greater than or equal to a reference vehicle speed and a load of the internal combustion engine is less than a reference load.