Abstract: A radiator cap is connected to a circulating circuit at a connecting point located upstream of a water pump in a flow direction of coolant and that regulates a pressure in the circulating circuit to be within a predetermined pressure range that is higher than or equal to an atmospheric pressure at the connecting point. A rotary valve is disposed in the circulating circuit at upstream of the connecting point of the radiator cap in the flow direction of coolant. Accordingly, a cavitation is restricted from occurring, and the water pump can perform enough efficiency. A communication passage that has an upstream end and a downstream end connected to the circulating circuit may be disposed instead of the radiator cap. In this case, a pressure regulating valve is disposed in the communication passage.

Abstract: A radiator cap is connected to a circulating circuit at a connecting point located upstream of a water pump in a flow direction of coolant and that regulates a pressure in the circulating circuit to be within a predetermined pressure range that is higher than or equal to an atmospheric pressure at the connecting point. A rotary valve is disposed in the circulating circuit at upstream of the connecting point of the radiator cap in the flow direction of coolant. Accordingly, a cavitation is restricted from occurring, and the water pump can perform enough efficiency. A communication passage that has an upstream end and a downstream end connected to the circulating circuit may be disposed instead of the radiator cap. In this case, a pressure regulating valve is disposed in the communication passage.

Abstract: A fuel cell is used for generating driving energy for a vehicle. The reserve-tank inlet valve is located between a suction side of the coolant pump and a position in the coolant circuit at which a pressure of the coolant controlled by the reserve-tank inlet valve is an intermediate value between a discharge pressure of the coolant pump and a suction pressure of the coolant pump during an operation of the coolant pump. Even if the fuel cell is stopped generating electric power, the coolant pump is made continue operating even when the vehicle is traveling in a case that a coolant temperature exceeds a predetermined temperature. The coolant pump is made stop rotating after the coolant temperature becomes lower than or equal to the predetermined temperature.