| 摘要 |
PROBLEM TO BE SOLVED: To attain a sufficient radial sound reducing effect by sliding motion in a simple construction, in a pipe body for passage of gas flowing in the inside, such as an exhaust pipe. SOLUTION: A cylindrical body 14 of a pseudo-cylindrical concave polyhedron (PCCP) is fitted and arranged in the pipe body 4. With this, ridges RL1, RL2 of the pseudo-cylindrical concave polyhedron are bent and a linear contact state (herein, the linear contact state in a helical and mesh-like manner) to the inner peripheral face 4a of the pipe body 4 is achieved. In such a linear contact state, sliding motion with sufficiently strong friction is easily caused between the pipe body 4 and the cylindrical body 14 by pressure oscillation due to the gas flowing inside such as exhaust gas and the pressure oscillation of the gas is efficiently converted to thermal energy and absorbed. Further, a number of separated spaces RS are formed between the pipe body 4 and the cylindrical body 14 by the linear contact in the mesh-like manner, and the oscillation energy is expended by volume variations of the spaces RS during film oscillation of the cylindrical body 14. COPYRIGHT: (C)2011,JPO&INPIT
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