| 摘要 |
PURPOSE:To effectively suppress noise which is produced by pulsated exhaust gas flowing through an exhaust pipe by regenerating the pressure of exhaust gas inside the exhaust pipe which is detected by a sensor in the form of a pressure wave having a reverse phase and sending the pressure wave into the exhaust pipe. CONSTITUTION:A pressure sensor 6 which is positioned at the upstream side of an exhaust pipe 4 detects an exhaust pressure. Because of sequential explosions by burning inside the cylinders of an engine 1, a plurality of pressure waves are produced at the upstream side of the exhaust pipe 4 and the varying pressures are detected by the pressure sensor 6. The detected output is reversed by a phase reversing circuit 7 and then sent to an amplifier 8. Resulting pressure waves having a phase reverse to said detected output are sent into the exhaust pipe 4 by a diaphragm 10 which is driven via an electromagnetic solenoid 9 by the amplifier 8. Cancelling the pulsated exhaust gas by the pressure waves having the reverse phase may dissolve the problem of noise of exhaust gas which is emitted from the wall of the exhaust pipe 4. |
