| 摘要 |
PROBLEM TO BE SOLVED: To provide an outdoor hood having high sound-absorbing performance, without having to increase the size of a cover. SOLUTION: A noise reducing material 10 is provided with an air trunk body part constituted of a first air trunk part 9a, a bent part 9b and a second air trunk part 9d, and an air-trunk expanding part added thereto. The air-trunk expanding part has a first expanding part 9c, formed in a state of extending to the depth in the first direction on a side opposite to the first air trunk part 9a of the bent part 9b, and a second expanding part 9f, formed in a state of extending in a direction opposite to that of the second air-trunk part 9d from a side part of the first extending part, in a region at a depth side in the first direction, with respect to a communication opening of the bent part 9b and the second air-trunk part 9d. Consequently, the number of times of collision with the noise reducing material of noise is increased; damping effect is increased; high noise reducing effect can be attained; and the influence from the deterioration of pressure loss performance due to sudden expansion and sudden contraction of a circulation cross-sectional area can be reduced, since the circulation cross-sectional area of the air trunk body part does not suddenly expand or contract. COPYRIGHT: (C)2011,JPO&INPIT
|
