| 摘要 |
A heater core supplied with hot water by a cooling water recirculating passageway of an internal combustion engine, and having a plurality of parallel tubes arranged between first and second tanks. The heater core forms a first cooling water flow circuit for creating a U-shaped flow whereby the cooling water from the first tank is introduced into the second tank via a group of tubes and then introduced into the first tank via a different group of tubes, and a second cooling water flow circuit for creating a straight flow from the first tank and second tank. A flow switching valve is provided and is usually switched to the first cooling water flow circuit. Upon a drop in the engine rotational speed to an idling speed, wherein the amount of hot water supplied to the heater core is small, the second cooling water flow circuit creating a one-directional flow from the first tank to the second tank is selected, whereby the flow resistance is lowered, and accordingly, the amount of heat emitted from the heater core increased, to thus maintain a desired heating performance during the engine idling condition.
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