| 主权项 |
1. A cooling system for an internal combustion engine comprising:
a radiator which is provided for a cooling water passage of the internal combustion engine and which deprives heat from cooling water; a bypass passage which bypasses the radiator; an electronically-controlled thermostat which shuts off flow of the cooling water to the radiator so that the cooling water is allowed to flow to the bypass passage in a valve closed state and which allows the cooling water to flow through at least the radiator in a valve open state; a sensor which detects a temperature of the cooling water; and a control unit which has program logic to open and close the thermostat based on the detected value of the sensor and program logic to change a valve opening temperature of the thermostat, the control unit including program logic to (a) forbid valve opening of the thermostat and (b) estimate, based on transition of the temperature of the cooling water detected by the sensor, whether (i) a first cooling water is used, the first cooling water containing a substance that undergoes structural phase transition at a predetermined temperature, thereby absorbing or releasing heat with temperature change so as to have changeable specific heat, or (ii) a second cooling water is used, the second cooling water being without a substance that undergoes structural phase transition at a predetermined temperature to absorb or release heat with temperature change, wherein, when the valve opening is forbidden, if the temperature of the cooling water becomes constant, the control unit estimates that (i) the first cooling water is used and (ii) the temperature at which the temperature of the first cooling water is constant is the temperature of change of the specific heat of the first cooling water, and wherein, when the valve opening is forbidden, if the temperature of the cooling water does not become constant, the control unit estimates that the second cooling water is used. |
