Engine cooling system having coolant temperature sensor

An engine cooling system having a plurality of coolant temperature sensors, the plurality of coolant temperature sensors including a first coolant temperature sensor to sense a second coolant temperature corresponding to a coolant outlet side of an engine, and a second coolant temperature sensor to sense a third coolant temperature corresponding to a coolant outlet side of a radiator, the engine cooling system comprising:

• a coolant control valve unit disposed in the engine cooling system to control a flow of coolant passed through the radiator and a flow of coolant discharged from the engine by an opening rate of the coolant control valve unit;
• and
• a control unit programmed to control the coolant control valve unit according to an operation condition of the engine and each of the sensed second coolant temperature and the sensed third coolant temperature,
• wherein the control unit calculates:
• a first coolant temperature corresponding to a coolant inlet side of the engine, the calculated first coolant temperature being based on a heat transfer amount of the engine, the flow of coolant discharged from the engine, and each of the sensed second coolant temperature and the sensed third coolant temperature, and
• a valve opening rate of the coolant control valve unit, the calculated valve opening rate being based on each of the calculated first coolant temperature, the sensed second coolant temperature, and the sensed third coolant temperature;
• and
• wherein the control unit executes a feed-forward control of the coolant control valve unit in order to reach the calculated valve opening rate.