| 摘要 |
PURPOSE:To provide excellent supercharging performance through improvement of turbine efficiency in a low speed range, according to the method wherein, during low speed running of an engine, the opening timing of an exhaust valve is delayed, and a valve opening period is shortened. CONSTITUTION:In a low speed range, a second exhaust valve 10 is not opened, and is opened at a late timing EO1 after a bottom dead point BDC by a first exhaust valve 9 (curved line I). The second exhaust valve is closed at a closing timing EC1 after a top dead center, and is delayed in an opening timing to shorten a valve opening period. In a middle and a high area, operation of the two exhaust valves 9 and 10 are controlled, the valves and are opened at an early opening timing EO2 before a bottom dead point BDC by the second exhaust valve 10 (curved line II), and closed at a closing timing EC2 after the top dead center DTC.
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