| 摘要 |
PURPOSE:To prevent an internal exhaust-gas-recirculation rate from increasing, by bypassing both up- and downstreams at the exhaust side of a pressure wave supercharger simultaneously in the case where a suction pressure wave is propagated to the pressure wave supercharger when suddenly opening a throttle valve at the time of acceleration or the like. CONSTITUTION:At the time of sudden acceleration or the like, if a throttle valve 16 is suddenly opened, suction pressure at the downstream side of this throttle valve 16 is propagated to a suction passage 4 at the upstream side of the throttle valve 16, namely, a suction discharge port 9 of a pressure wave supercharger 6. Therefore, pressure balance at each of suction and exhaust sides of the pressure wave supercharger comes down, so that an internal EGR rate increases, that is, exhaust gas is apt to mix in the suction discharge port 9 from an exhaust intake port 10. In this case, when suction pressure inside the suction passage 4 at the upstream of the throttle valve 16 becomes more than the specified value, it is detected by a suction pressure sensor 26, and at the initial stage of acceleration, a valve 23 of an exhaust bypass passage 22 is opened by a control circuit 30 via an actuator 29. With this constitution, pressure at the exhaust side in the pressure wave supercharger 6 is reduced, thus the desired end comes to fruition. |
