| 摘要 |
<p>PROBLEM TO BE SOLVED: To raise the temperature of a catalyst by heating of an electric heater in a short time without increasing buttery load when the emission temperature is low. SOLUTION: An oxidizing catalyst 5 provided with an electric heater 5a is provided on an exhaust passage 3 of a diesel engine 1, and a bypass passage 6 for connecting the upstream part to the downstream part from the oxidizing catalyst of the exhaust passage is provided. A bypass control valve 8 for opening and closing the bypass passage 6 is provided on the bypass passage 6, and a catalyst temperature sensor 10 for detecting the catalyst floor temperature is provided on the oxidizing catalyst 5. An engine control circuit(ECU) 20 calculates the emission temperature from the engine accelerator opening and the engine speed. When both the exhaust gas temperature and the catalyst temperature are not more than the prescribed value, the bypass control valve 8 is opened, the flow rate of the emissions to flow to the oxidizing catalyst is decreased, and the electric heater 5a is electrified. Therefore, the temperature of the oxidizing catalyst can be raised to the activation temperature without taking heat of the heater by low-temperature exhaust gas.</p> |
