| 摘要 |
PURPOSE: A muffler is provided to effectively reduce engine noise in all frequency section through an extended pipe part and a resonance pipe part. CONSTITUTION: A muffler comprises a perforated pipe part(B), an extended pipe part(A), and a resonance pipe part(C). The perforated pipe part reduces middle and high frequency noise with a changed cross section formed on the inner surface of a pipe. The extended pipe part is extended from one end of the perforated pipe part, and reduces low frequency noise by offsetting the phase difference of sound waves. The extended pipe part comprises a wavelength as much as the quarter of firing frequencies. The resonance pipe part is connected to the other end of the perforated pipe part, and reduces the low frequency noise through Helmholtz resonance. |
