Double wall structure

Abstract

A double wall structure capable of suppressing an increase in a sound transmission amount with regard to sound with a specified frequency and stably exhibiting a sound insulation performance for sound with various frequencies is provided. A double wall structure 1 is assumed to be a door serving as a part of an automobile. The double wall structure 1 is provided with plate-like bodies 2 and 3 arranged in parallel and opposing to each other with leaving a predetermined distance. The plate-like bodies 2 and 3 are formed in a rectangular shape with one direction being slightly longer. Between the two plate-like bodies 2 and 3 opposing to each other is formed an internal chamber 4 . Side plates 5 are provided so as to connect the plate-like bodies 2 and 3 to each other, and thereby the internal chamber 4 is almost closed. At a position where a sound pressure is increased in the internal chamber 4 is provided a sound absorbing chamber structure 6 having a porous surface 6 a on one surface in a rectangular parallelepiped.

1 . A double wall structure having plate-like bodies opposing to each other, a completely or almost closed internal chamber being formed between said plate-like bodies, comprising:
 a sound absorbing chamber forming shell forming a sound absorbing chamber provided in at least one plate-like body among said plate-like bodies, the sound absorbing chamber forming shell being adjacent to said plate-like body and isolated from said internal chamber; and   a sound pressure reducing portion for reducing a sound pressure in said internal chamber, the sound pressure reducing portion having a number of through portions passing through said sound absorbing chamber forming shell or said plate-like bodies so as to open said sound absorbing chamber to said internal chamber.   
     
     
         2 . The double wall structure according to  claim 1 , wherein said sound absorbing chamber forming shell is provided in an inner surface of said plate-like bodies, and said sound pressure reducing portion is provided in at least a part of said sound absorbing chamber forming shell. 
     
     
         3 . The double wall structure according to  claim 1 , wherein said sound absorbing chamber forming shell is provided in an outer surface of said plate-like bodies, and said sound pressure reducing portion is provided in at least a part of said plate-like bodies. 
     
     
         4 . The double wall structure according to  claim 1 , wherein at least one plate-like body among said plate-like bodies is provided with a perforated member in which an opening for opening said internal chamber to the outside is formed, and a closing member attached to said perforated member so as to close said opening, and said sound absorbing chamber forming shell is provided in said closing member. 
     
     
         5 . The double wall structure according to  claim 4 , wherein said closing member includes a vibration damping member formed of a structure or a material having a vibration damping property. 
     
     
         6 . The double wall structure according to  claim 4 , wherein said closing member includes a concavity and convexity shape. 
     
     
         7 . The double wall structure according to  claim 4 , wherein said closing member includes a structure or a material having a sound absorbing property. 
     
     
         8 . The double wall structure according to  claim 4 , wherein said closing member comprises a porous body. 
     
     
         9 . The double wall structure according to  claim 1 , wherein a plurality of said sound absorbing chamber forming shells are provided in one of said plate-like bodies, and a plurality of sound absorbing chambers are formed by said sound absorbing chamber forming shells. 
     
     
         10 . The double wall structure according to  claim 1 , wherein said sound absorbing chamber forming shell is provided with a partition member, and said sound absorbing chamber is partitioned into a plurality of small chambers by said partition member. 
     
     
         11 . The double wall structure according to  claim 1 , wherein said sound absorbing chamber forming shell includes a concavity and convexity shape.