| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high sound absorbing performance with a simple structure without increasing in size by providing a sound absorbing material at an inside of a cover, and providing a sound absorbing means having a sound insulation plate for reflecting a sound in a hood and the material for absorbing the sound in combination oppositely directly to a duct. SOLUTION: The hood 1 comprises a duct 2 having a vent port 2a, a flange 2c connected to the port 2a, and a cover 1b mounted at the flange 2c to cover the port 2a and opened at its lower part. In this case, a foamed urethane sound absorbing material 4a having a thickness of about 40 mm is adhered to an inside of the cover 1b. A sound insulation plate 3 is installed oppositely directly to forward of the port 2a, and a sound absorbing material 5b having a thickness of about 10 mm is adhered to the duct 2 side. Air ducts 7 for generating an air flow can be formed between the plate 3 and the cover 1b and between the plate 3 and the port 2a. |
