| 摘要 |
PROBLEM TO BE SOLVED: To reduce the noise generated in a car room by Helmhortz resonance of a luggage room. SOLUTION: A cave shape front reinforce 10 and rear reinforce 20 provided on an upper back panel 3 along the car width direction are sealed up and also partation plates 12, 22 for forming a divided cave divided along the car width direction are inserted in these reinforces. An opening communicating to a luggage room is formed on the end of oneside divided cave. Communication parts 12c, 22c for communicating the divided cave of both sides are formed on the end of the opposite side to the opening side of the partition plates 12, 22. Partition walls 14, 24 are formed on the way position of the other divided cave folded back by the communication parts 12c, 22c from oneside divided cave. The length between the opening part and partition wall 14,24 is set to 1/4 wave length of the resonance noise generated in response to the volume of the luggage room.
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