| 摘要 |
PROBLEM TO BE SOLVED: To provide large sound absorbing and sound shutting-off effects from a low frequency zone to a high frequency zone by specifying an average interval between an engine and an engine cover and installing a sound absorbing material having a surface material made of a particular material in a space formed by the engine and the engine cover. SOLUTION: Because of an engine cover 1 formed to cover at least the upper surface of an engine and the engine upper surface and one side face, the overall value of an average sound pressure level in a space formed by the engine and the engine cover 1 is at least 1.3 times larger compared with that of no engine cover 1. An average interval between the engine and the engine cover 1 is set in the range of 5 to 10mm. A sound absorbing material 2 made of a surface material 3 and an inner material 4 is set in the space, but the surface material 3 is formed to have a high polymer unwoven cloth having a tensile strength of 1 to 10kgf/mm<2> and a thickness of 0.1 to 5mm, and/or a high polymer film having a tensile strength of 5 to 30kgf/mm<2> and a thickness of 5 to 50μm.
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