| 摘要 |
PURPOSE:To improve exhaust efficiency in a range of from a low speed region to a high speed region, by a method wherein a cavity and an on-off valve are installed to the exhaust valve of an engine, operation of the valve is controlled depending on the number of revolutions of an engine, and the effective volume of a muffler is changed over. CONSTITUTION:A cavity 2 and a valve 3, opening and closing the cavity, are attached to an exhaust system including a muffler 1 of an engine, and the number of revolutions of an engine is detected to control operation of the valve 3 depending on a speed region. In a high speed region, the valve 3 is closed by means of a timer circuit 7 on the high speed side, and in a low speed region, the valve 3 is opened by means of a timer 6 on the low speed side, and resonance frequency of the exhaust system is changed over to improve exhaust efficiency. |
