Patent ID: 8561580

Claim:
An engine cooling device for cooling an internal combustion engine by circulating cooling water, and in which at least a part of cooling water flowing out of the internal combustion engine is used as a heat source for heating a fluid to be heated, wherein in the internal combustion engine, a block-side flow path and a head-side flow path are provided, the block-side flow path being for circulating cooling water for cooling a cylinder block and the head-side flow path being for circulating cooling water for cooling a cylinder head, the engine cooling device comprising: a cooling water pressure-feed unit disposed to pressure-feed cooling water to the block-side flow path and the head-side flow path; a first flow amount changing portion configured to change a flow amount of at least cooling water used as a heat source for heating the fluid, in the cooling water flowing out of the block-side flow path; a heat-radiation heat exchanger disposed to radiate heat from cooling water flowing out of the head-side flow path and cooling water flowing out of the block-side flow path to the outside air and for causing the cooling water to flow out to a suction side of the cooling water pressure-feed unit; a bypass passage provided to guide cooling water flowing out of the head-side flow path and cooling water flowing out of the block-side flow path to the suction side of the cooling water pressure-feed unit while bypassing the heat radiation heat exchanger; a second flow amount changing portion configured to change a bypass flow amount of cooling water flowing through the bypass passage, a first heating heat exchanger disposed to heat the fluid, the first heating heat exchanger being coupled to the head-side flow path such that cooling water flowing out of the head-side flow path flows into the first heating heat exchanger; and a second heating heat exchanger disposed at a downstream side of the first heating heat exchanger in a flow direction of the fluid to heat the fluid, the second heating heat exchanger being coupled to the first flow amount changing portion such that cooling water flowing out of the block-side flow path flows into the second heating heat exchanger, wherein the second flow amount changing portion changes the bypass flow amount so that a suction-side temperature of cooling water on the suction side of the cooling water pressure-feed unit approaches a reference suction-side temperature, the first flow amount changing portion changes the flow amount of cooling water for the heat source so that a block-side outlet temperature of cooling water flowing out of the block-side flow path approaches a reference block-side outlet temperature, the reference block-side outlet temperature has a value higher than the reference suction-side temperature, and cooling water outlets of the first and second heating heat exchangers are connected to one of a suction side of the cooling water pressure-feed unit and an inlet side of the heat radiation heat exchanger.