| 摘要 |
PURPOSE:To prevent an engine output from being lowered in a low speed region by providing on an exhaust passage a throttle valve opened and closed in responce to the number of engine revolutions and further providing a check valve on the bypass passage of the throttle valve. CONSTITUTION:The captioned structure includes a control valve 5 provided on the exhaust passage 2 of an engine, a second exhaust passage 6 bypassing the control valve 5, and a lead valve 7 for stopping a counterflow of exhaust gas to the upstream side. In an engine slow revolution region, the control valve 5 is fully closed, and exhaust gas is allowed to flow through the second exhaust passage 6. Hereby, an overlap period with an air intake valve 3 is reduced by apparent effect such as reduction of a degree of opening of the exhaust valve 4, preventing the exhaust gas from blowing back and away. Further, an output of the engine is prevented from being reduced. |
