Patent ID: 8220421

Claim:
A cooling system for cooling an internal combustion engine, comprising: a first portion forming a first fluid chamber through which a cooling medium passes as the cooling medium flows from the internal combustion engine to a heater that utilizes heat generated by the internal combustion engine; a second portion forming a second fluid chamber through which the cooling medium passes as the cooling medium flows from the heater to the internal combustion engine, the second fluid chamber being arranged adjacent to the first fluid chamber; and a bypass valve arranged inside the first fluid chamber and the second fluid chamber to form a bypass flow passage connecting the first fluid chamber and the second fluid chamber with the bypass flow passage having a flow resistance smaller than a flow resistance occurring when the cooling medium flows from the first fluid chamber to the second fluid chamber through the heater, the bypass valve being configured and arranged to automatically close the bypass flow passage when a temperature of the cooling medium is equal to or higher than a first prescribed temperature.