| 摘要 |
PROBLEM TO BE SOLVED: To provide an engine cooling system achieving reduction of fuel consumption in cold starting and also suppressing response delay of valve opening operation of a thermostat valve when shifting to a high load operation immediately after cold starting. SOLUTION: This engine cooling system 1 includes: a first thermostat valve 25 arranged upstream of a water pump 15 in a main cooling water circuit 85, circulating cooling water to the side of a main cooling water passage when the valve is opened, and circulating the cooling water to the side of a first bypass passage 17 when the valve is closed; and a second thermostat valve 27 arranged downstream of the water pump 15, circulating the cooling water to the side of the main cooling water passage when the valve is opened, and circulating the cooling water to the side of a second bypass passage 23 when the valve is closed. The valve opening start temperature of the first thermostat valve 25 and the fully opening temperature thereof are set respectively higher than those of the second thermostat valve 27. When the temperature of the cooling water is below a first predetermined temperature T1, a rate of change in a cooling water flow rate when the second thermostat valve 27 is opened is set lower than that when the temperature of the cooling water is higher than the first predetermined temperature T1. COPYRIGHT: (C)2009,JPO&INPIT
|
