Patent ID: 8881693

Claim:
An engine cooling system incorporated into an engine cooling circuit comprising a pump for circulating a coolant of an engine and a radiator for cooling the coolant of the engine, the engine cooling system comprising: a rotary valve that comprises a first passage portion through which the coolant of the engine flows, and which is provided between the engine and a coolant outlet of the pump at a location downstream of the coolant outlet of the pump and upstream of the engine, relative to a single cooling cycle of the engine cooling system; a second passage portion through which the coolant of the engine flows, and which is provided between the radiator and a coolant inlet of the pump at a location downstream of the radiator and upstream of the coolant inlet of the pump, relative to the single cooling cycle of the engine cooling system; and a rotary valve disc interposed in the first and second passage portions, and being rotatable so as to simultaneously control the coolant flowing through the first passage portion and the coolant flowing through the second passage portion, the rotary valve being an electric motor driven type, and the engine cooling system further comprising a control portion controlling the rotary valve, the second passage portion communicating with the radiator at an upstream side of the rotary valve disc, and the rotary valve disc restricting a flow rate of the coolant flowing through the second passage from an upstream side to a downstream side of the rotary valve disc such that the rotary valve restricts a flow rate of the coolant flowing through the radiator, the rotary valve further comprising a first thermostat that opens when a temperature of the coolant of the engine is higher than a first predetermined value, the second passage portion communicating with the radiator through the first thermostat at the downstream side of the rotary valve disc, and the control portion controlling the rotary valve to restrict the flow rate of the coolant flowing through the second passage portion from the upstream side to the downstream side of the rotary valve disc, when the temperature of the coolant of the engine is significantly lower than the first predetermined value, the rotary valve further comprising a second thermostat that opens when the temperature of the coolant of the engine is higher than a second predetermined value, the second passage portion communicating with the radiator through the second thermostat at the upstream side of the rotary valve disc, and the second predetermined value being set lower than the first predetermined value.