Cooling system for an internal combustion engine

Abstract

An opening and closing condition of a thermostat is optimized. In a cooling system for an internal combustion engine in which a cooling water, in which its specific heat becomes larger at a predetermined temperature than at other temperatures, is caused to circulates through a cooling water passage, there are provided a radiator, a bypass passage that bypasses the radiator, and a thermostat that interrupts the circulation of the cooling water to the radiator and circulates the cooling water to the bypass passage when it closes, and circulates the cooling water to at least the radiator when it opens, wherein the thermostat is set to open at the time when the temperature of the cooling water is higher than a predetermined temperature.

1 . A cooling system for an internal combustion engine in which a cooling water, in which its specific heat becomes larger at a predetermined temperature than at other temperatures, is caused to circulates through a cooling water passage, said cooling system comprising:
 a radiator that is arranged in said cooling water passage and takes heat from said cooling water;   a bypass passage that bypasses said radiator; and   a thermostat that interrupts the circulation of the cooling water to said radiator and circulates the cooling water to said bypass passage when it closes, and circulates the cooling water to at least said radiator when it opens;   wherein said cooling system is provided with:   an operation region in which said thermostat opens when the temperature of the cooling water flowing out of said internal combustion engine into said cooling water passage is equal to or more than a prescribed temperature which is higher than said predetermined temperature, and when the temperature of the cooling water flowing out of said cooling water passage into said internal combustion engine is higher than said predetermined temperature, said operation region being decided by the number of engine revolutions per unit time and the engine load; and   an operation region in which at least one of the number of engine revolutions per minute and the engine load is higher than that in said first-mentioned operation region, and in which said thermostat opens when the temperature of the cooling water flowing out of said internal combustion engine into said cooling water passage is equal to or more than a prescribed temperature which is higher than said predetermined temperature, and when the temperature of the cooling water flowing out of said cooling water passage into said internal combustion engine is lower than said predetermined temperature.   
     
     
         2 - 4 . (canceled)