| 摘要 |
PURPOSE:To realize normal purification of exhaust gas by putting a selector value on the bypass passage side so as to prevent exhaust gas from being cooled through heat exchange with cooling water in case the temperature of a catalytic converter is lower than the predetermined temperature. CONSTITUTION:The function of a control circuit 24 is such that, during cooling operation a selector valve 12 is put on the heat exchanger 10 side according to signals from a blower switch 7 and water temperature sensor 27 so as to open an opening/closing valve 13, and cooling water is heated by means of an engine E through driving the first water pump and further heated in an exhaust gas passage 9, then room heating is expedited by means of a heater core 5 and warming up operation is expedited. As the warming up operation progresses, the selector valve 12 is put on te bypass 11 side to prevent overheat of the engine E. Further, when catalytic converter CA is detected to have the temperature lower than the temperature capable of purification by means of a temperature sensor 28, cooling of exhaust gas is stopped by putting said valve on the bypass passage side, while overheat is prevented by putting said valve on the heat exchanger 10 side in case the temperature of said converter CA grows abnormally high. Thus, purification of the exhaust gas can be performed normally and overheat of the engine can be prevented. |
