| 摘要 |
PURPOSE: A noise-damping and frequency-changing prepositional muffler is provided to effectively reduce noise by changing the noise-damping frequency depending on the RPM(Revolutions Per Minute) change of an engine. CONSTITUTION: A prepositional muffler filled with sound-absorbing glass wool(2) includes a case(1) installed on the middle of an exhaust system. A first internal pipe(10) and a second internal pipe(20) are inserted to the case, while the one pipe is laid over the other pipe. The second internal pipe is made of a material shrinking and expanding depending on the temperature change. Many first holes(11) and second holes(21) are respectively formed in the overlapped portions of the first and second pipes. According to the length change of the second internal pipe, the sectional area of the holes communicated with the glass wool changes. Thus, the noise-damping frequency is changed.
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