| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently reduce noise without using any sound absorbing material in an under cover for engine to be provided on the lower side of an engine loaded on an automobile by forming a number of small projections or small dents on the engine-side inner surface wall. SOLUTION: A number of small projections 6 are formed on the inner wall surface 4 consisting of a front inclined surface 4a, a horizontal surface 4b and a rear inclined surface 4c of an under cover 2 opposed to an engine 1. The small projections 6 are formed semicircularly, and they may be regularly arranged close together or irregularly arranged. Small dents may be formed instead of the small projections 6. Further, the inner wall surface 4 may be curved. According to the above structure, since the noises generated from the engine 1 are irregularly reflected by the small projections 6, the respective reflected sounds are mutually interfered and cancelled. Thus, the noise can be reduced without using a sound absorbing material to provide a silencing effect.
|
