| 摘要 |
<p>PURPOSE:To improve attenuation of sound over a relatively wide frequency band by arranging a cylindrical foam aluminum sound absorber at the inside of a tubular casing and varying the interval between the casing and the sound absorber in step in longitudinal direction. CONSTITUTION:A muffler has a double cylindrical structure of a cylindrical stepped casing 1 and a cylindrical foam aluminum sound absorber 2 arranged at the inside of the casing 1 coaxially therewith. The inside of the sound absorber 2 serves as a path 4 for exhaust gas and the like. Inner diameter of the casing 1 is increased sequentially in step for every predetermined length. Consequently, the interval between the casing 1 and the sound absorber 2 is increased sequentially in step for every predetermined length.</p> |
