| 摘要 |
PURPOSE:To reduce dilution from dead volume by providing two exhaust valves to each cylinder while providing a block valve to one exhaust path and quickening the closing time of an exhaust valve communicatable with the exhaust path provided with the block valve when compared with the other. CONSTITUTION:A block valve 6 is provided in an exhaust path 8 communicatable with secondary exhaust valve 5 of engine having two exhaust valves 4, 5 for every cylinder and closed under intermediate or high speed. The closing time of said valve 5 is set earier than that of primary exhaust valve 4. The exhaust gas entered into the dead volume between the block valve 6 and the secondary exhaust valve 5 is confined in said volume by closing the secondary exhaust valve then the primary exhaust valve is closed, thereby counterflow of the exhaust gas from the dead volume is prevented to reduce the dilution. |
