Patent ID: 7594483

Claim:
An internal combustion engine cooling system comprising: an engine water jacket of an internal combustion engine; a coolant circulation passage fluidly connecting a water jacket outlet of the engine water jacket to a water jacket inlet of the engine water jacket; a radiator disposed in the coolant circulation passage between the water jacket outlet and the water jacket inlet; a thermostat valve disposed in the coolant circulation passage between an inlet side of the radiator and the water jacket outlet to close the coolant circulation passage leading to the radiator when a coolant temperature of a cooling medium is lower than a prescribed temperature and to open the coolant circulation passage leading to the radiator when the coolant temperature of the cooling medium is equal to or higher than a prescribed temperature; a bypass passage branching from the coolant circulation passage at a position located between the water jacket outlet and the thermostat valve and connecting to the coolant circulation passage on an outlet side of the radiator for bypassing the thermostat valve and the radiator; a bridge passage connecting an intermediate portion of the bypass passage to an intermediate portion of the coolant circulation passage located downstream of the radiator and upstream of a merging position where the bypass passage merges with the coolant circulation passage for establishing communication between the intermediate portions of the bypass passage and the coolant circulation passage; a circulation passage resistance generating section arranged in a portion of the coolant circulation passage located downstream of a position where the bridge passage connects to the coolant circulation passage and upstream of the merging position where the bypass passage merges with the coolant circulation passage; and an oil heat exchanger arranged in the bridge passage to exchange heat between the cooling medium and transmission oil passing therethrough.