Composite sound-absorbing device with built in resonant cavity

Abstract

The composite sound-absorbing device of the present invention includes a perforated board having a number of first pores thereon, a back board and side boards, the perforated board, back board and side boards forming a closed cavity, wherein: at least one or more of the resonant cavities being located within the closed cavity; at least one or more of second pores being located on the resonant cavities; at least one of the second pores being connected with the closed cavity; the resonant cavity having a volume of V=10 mm 3 −1×10 10 mm 3 , having a thickness of 0.05 mm-10 mm, the second pores having an aperture of d′=0.05-100 mm, with a perforation rate σ′=0.01%-30%. The present invention is beneficial to improve the effect of sound-absorbing and expand the frequency band of sound-absorbing.

1 . A composite sound-absorbing device with built-in resonant cavity, including: a perforated board having a number of first pores thereon, a back board and side boards, said perforated board, back board and side boards forming a closed cavity, wherein: at least one or more independent said resonant cavities being located within said closed cavity randomly; said resonant cavities being in a shape of sphere, ellipsoid or polyhedron; at least one or more of second pores being located on said resonant cavities; and at least one of said second pores being connected with said closed cavity;
 said resonant cavity having a volume of V=10 mm 3 -1×10 10  mm 3 , the thickness of the wall of the cavity being 0.05 mm-10 mm, said second pores having an aperture of d′=0.05-100 mm, with a perforation rate σ′=0.01%-30%.   
     
     
         2 . The composite sound-absorbing device of  claim 1 , wherein the number of said resonant cavities is more than one, which are located within said closed cavity directly or fixed within said closed cavity separately partitioned by a number of partition boards. 
     
     
         3 . (canceled) 
     
     
         4 . The composite sound-absorbing device of  claim 1 , wherein said second pores are connected to said closed cavity directly. 
     
     
         5 . The composite sound-absorbing device of  claim 1 , wherein said second pores are connected to said closed cavity via tubes. 
     
     
         6 . The composite sound-absorbing device of  claim 1 , wherein said first or second pores are connected to one end of said tubes and said tubes are located within said closed cavity for increasing acoustical impedance. 
     
     
         7 . The composite sound-absorbing device of  claim 6 , wherein the other end of said tubes on said second pores are connected to said closed cavity, said second pores on another resonant cavity or said first pores on said perforated board. 
     
     
         8 . The composite sound-absorbing device of  claim 6 , wherein said tubes are made of metal, glass, plastic or rubber, with a length of 1-5000 mm and diameter of 0.1-100 mm;
 when said tubes are made of rubber, they are connected to said first pores or second pores via binding, or they are connected to said first pores via a first transition joint at the ends of said tubes, or they are connected to said second pores via a second transition joint at the ends of said tubes;   when said tubes are made of metal, glass or plastic, they are connected to said first pores or second pores via binding, welding, thread connection or injection, or they are connected to said first pores via a first transition joint at the ends of said tubes, or they are connected to said second pores via a second transition joint at the ends of said tubes.   
     
     
         9 . The composite sound absorptive device of  claim 1 , wherein said perforated board has a thickness of 0.5-10 mm, the diameter of said first pores on said perforated board d being 0.1-5 mm, with a perforation rate of 6′=0.1%-30%; said closed cavity having a depth of D=10-2000 mm, and said closed cavity having a shape of cylinder composed by one side board or polyhedron composed by a plurality of side boards;
 said first pores on said perforated board are arranged in a shape of regular triangle or square or are arranged irregularly. 
 
     
     
         10 . The composite sound-absorbing device of  claim 1 , wherein the back side of said perforated board is coated with a layer of porous sound-absorbing material, said layer of porous sound-absorbing material being located within said closed cavity, with a thickness of 0.1 mm-200 mm.