| 摘要 |
PROBLEM TO BE SOLVED: To reduce a pressure loss of an exhaust passage and to dispense with an exclusive selector valve for switching a turbine bypass passage 16 and a non-bypass passage 19.SOLUTION: A first catalyst 14 is arranged in a non-bypass passage 19 in which an exhaust turbine 5 is provided, a second catalyst 18 is arranged in a turbine bypass passage 16 which bypasses the exhaust turbine 5, and the first catalyst 14 and the second catalyst 18 are provided in parallel with each other. Since a turbine wheel of the exhaust turbine 5 acts as exhaust resistance, an exhaust gas is preferentially flows into the turbine bypass passage 16 when a waste gate valve 17 is largely opened immediately after a cold start, the second catalyst 18 can be activated in an early stage, and a cleaning capacity of the exhaust gas can be enhanced in an early stage. Since the first catalyst 14 and the second catalyst 18 are arranged in parallel with each other, a pressure loss can be reduced. Since a ratio of an exhaust gas amount passing through the exhaust turbine 5 and an exhaust gas amount bypassing the exhaust turbine 5 can be controlled by the waste gate valve 17, an exclusive selector valve can be obviated.SELECTED DRAWING: Figure 1 |
