| 摘要 |
A flow-quantity control valve controlling hot-water flow to a heat exchanger and a bypass circuit allowing hot water to bypass the heat exchanger are provided along with a pressure-actuated valve in the bypass circuit which is responsive to a pressure increase of hot water from an engine. Inlet-side opening portions, outlet-side opening portions, and a bypass-side opening portion are provided in a control passage of a valve body of the flow-quantity control valve. Main flow of dynamic pressure of hot water sprayed from portions on a small opening-degree side act upon a valve body side of the pressure-actuated valve. Due to this, dynamic pressure of the hot water in a small opening-degree region of the flow-quantity control valve can be effectively used to increase a valve-lift quantity of the pressure-actuated valve, thereby reducing a fluctuation range of blown-air temperature of the heat exchanger. Also, the flow may be bent so that hot-water flow having a high dynamic-pressure component from the hot-water inlet pipe is not applied directly to the valve body of the differential-pressure valve; thus, lift of the differential-pressure valve can be prevented from becoming excessive, and a drop in heat-exchanger blown-air temperature at a predetermined opening-degree position of a flow-quantity control valve can effectively be suppressed.
|
