| 摘要 |
<p>PURPOSE:To promote activation of catalyst by constructing such that a portion of exhaust gas is led to the inlet of catalyst while detouring the discharge turbine under such operating region where the temperature of exhaust gas is low even if the supercharge pressure exceeds over the setting level. CONSTITUTION:A discharge bypath 7 detouring a supercharge exhaust gas turbine provided in the downstream of an exhaust path 3 is branched from the exhaust path 3 and controlled through an exhaust bypass valve unit 8. Said valve unit 8 is constructed with a swing valve 13 for opening/closing the valve port section 12 of the bypath 7 and a negative pressure actuator 14 for opening/closing said valve 13. Under low load region when starting the engine, intake air of high negative pressure is led into the pressure chamber 18 to move the second diaphragm 17 to the left against a spring 24 thus to open the valve 13. Consequently, a portion of exhaust gas is led to the inlet of catalyst in the downstream of the exhaust gas turbine thus to activate the catalyst.</p> |
