Thermostat with failure diagnosis function and mehod for failure diagnosis of thermostat using the same

A method for diagnosing a failure in a thermostat, wherein the thermostat is to be installed between an engine and a radiator to control cooling water to bypass back to the engine or to circulate to the radiator by means of a valve operated depending on temperatures in the cooling water circulated between the engine and the radiator and measured by water temperature sensors installed before and after the valve, the method comprising:

• performing closed completion estimation by comparing a temperature in the cooling water at a side to which the cooling water is introduced from the engine with a closed completion temperature at which the valve of the thermostat is set to be fully closed;
• performing closed-failing determination in which, if the temperature in the cooling water introduced from the engine is lower than the closed completion temperature at the performing of the closed completion estimation, a difference of the temperatures in the cooling water before and after the valve is compared with a closed-failing determination temperature;
• and
• performing closed-failing confirmation in which, if the difference of the temperatures in the cooling water before and after the valve is lower than the closed-failing determination temperature at the performing of the closed-failing determination, the valve is confirmed to be closed-failing which is not closed despite of being closed.

A method for diagnosing a failure in a thermostat, wherein the thermostat is to be installed between an engine and a radiator to control cooling water to bypass back to the engine or to circulate to the radiator by means of a valve operated depending on temperatures in the cooling water circulated between the engine and the radiator and measured by water temperature sensors installed before and after the valve, the method comprising:

• performing open completion estimation by comparing a temperature in the cooling water at a side to which the cooling water is introduced from the engine with an open completion temperature at which the valve of the thermostat is set to be fully opened;
• performing open-failing determination in which, if the temperature in the cooling water introduced from the engine is higher than the open completion temperature at the performing of the open completion estimation, a difference of the temperatures in the cooling water before and after the valve is compared with an open-failing determination temperature;
• and
• performing open-failing confirmation in which, if the difference of the temperatures in the cooling water before and after the valve is higher than the open-failing determination temperature at the performing of the open-failing determination, the valve is confirmed to be open-failing which is not opened despite of being opened.