Patent ID: 8794194

Claim:
A combustion state control apparatus for controlling a combustion state of an internal combustion engine of a vehicle having the internal combustion engine, an automatic transmission capable of automatically changing a gear ratio, a radiator in which a coolant flowing through the internal combustion engine is to circulate to lower a temperature of the coolant, a flow rate adjusting unit for adjusting a flow rate of the coolant to the radiator, a coolant temperature detecting unit for detecting the temperature of the coolant, an engine speed detecting unit for detecting an engine speed of the internal combustion engine, and a load detecting unit for detecting a load of the internal combustion engine, the combustion state control apparatus comprising: an opening degree adjusting unit configured to increase an opening degree of the flow rate adjusting unit, as the temperature of the coolant detected by the coolant temperature detecting unit rises; and a gear ratio changing unit configured to change the gear ratio of the automatic transmission to a gear ratio to be used when the vehicle runs at a slow speed, and to change to said gear ratio when all of the following conditions are present: the temperature of the coolant detected by the coolant temperature detecting unit when the opening degree adjusting unit sets the opening degree of the flow rate adjusting unit to a maximum opening degree is equal to or higher than a threshold temperature, the engine speed of the internal combustion engine detected by the engine speed detecting unit is slower than a preset engine speed, and the load on the internal combustion engine detected by the load detecting unit is larger than a preset load.