Patent ID: 8201525

Claim:
A cooling device for an engine, comprising: a radiator flow channel for circulation, in order, from an engine via a radiator to a directional control valve of a thermostat; a heater flow channel for circulation, in order, from the engine via a heater core to the directional control valve of the thermostat; a bypass flow channel for circulation, in order, from the engine through an electronically controlled valve to the directional control valve of the thermostat are arranged in series; and a pump that causes a cooling water to circulate, wherein the radiator flow channel, the heater flow channel, and the bypass flow channel merge in the directional control valve of the thermostat and form a common flow channel between the directional control valve of the thermostat and the engine, wherein the pump is provided in the common flow channel, wherein, at the start of the warm-up period and during the warm-up operation, the circulation in the radiator flow channel is substantially stopped by the directional control valve of the thermostat, wherein cooling water circulation is actuated in the bypass flow channel, and an opening degree of the electronically controlled valve is gradually increased from a minimum as the cooling water temperature rises, wherein, at the end of the warm-up period, circulation is actuated in the radiator flow channel, and because the directional control valve of the thermostat is closed although an opening-closing valve of the electronically controlled valve is completely open, a state is established in which the circulation is substantially stopped in the bypass flow channel, wherein the electronically controlled valve is not completely closed even when operated to closed, and the electronically controlled valve is open to a certain degree from an initial stage of the warm-up period, thereby causing a part of the cooling water to flow in the bypass flow channel.