| 摘要 |
PROBLEM TO BE SOLVED: To effectively absorb low-order noise of a voltage transformer or the like as an electric apparatus. SOLUTION: A sheet of low-frequency sound absorbing material 2 is adhered in the external surface side of a cabinet 1 of the transformer as an electric apparatus. The low-frequency sound absorbing material sheet 2 includes a vibration controlling layer 21 provided at the external surface side of the cabinet 1, a low-frequency sound absorbing material 22 laminated in the external surface side of the vibration controlling layer 21, and a rear rigid wall layer 23 (iron plate) allocated in the external surface side of the low-frequency sound absorbing material 22. The vibration controlling layer 21 is provided with a bonding layer 21a formed of a two-pack epoxy resin to be coated on an external wall of the cabinet 1, and a metallic binding plate 21b (iron plate) attached to the external surface side of the bonding layer 21a. The low frequency sound absorbing material 22 is provided with a first porous material layer 22a laminated in the external surface side of the metallic binding plate 21b, a film 22b formed of a silicone rubber including non-organic compound laminated in the external surface side of the first porous material layer 22a, and a second porous material layer 22c laminated in the external surface side of the film 22b. COPYRIGHT: (C)2008,JPO&INPIT
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