Panel that absorbs acoustic energy at low, medium and high frequencies, particularly at frequencies ranging from 400 Hz to 5,000 Hz

• US 5,493,081 A
• Filed: 07/29/1994
• Issued: 02/20/1996
• Est. Priority Date: 08/06/1993
• Status: Expired due to Term

• Current Assignee: Olympus Holding BV
• Original Assignee: Roth Freres SA (Adient plc)
• Inventors: Manigold, Alain
• Primary Examiner(s): Dang, Khanh
• Application Number:
  US08/282,460
• Time in Patent Office: 571 Days
• Field of Search: 181/286, 181/290, 181/291, 181/294, 428/309.9, 428/311.5, 428/315.7, 428/316.6
• US Class Current: 181/286
• CPC Class Codes: E04B 2001/8461 layered
• CPC Class Codes: G10K 11/168 Plural layers of different materials, e.g. sandwiches
• CPC Class Codes: Y10T 428/249981 Plural void-containing components

Abstract

A panel absorbing acoustical energy at low, medium and high frequencies, particularly at frequencies ranging from 400 Hz to 5,000 Hz, is essentially constituted by a plate (1) of semi-rigid foam with open communicating cells and by a layer (2) of bonded fibers or by a flexible cellular material. The assembly acts according to a mass-spring principle. The plate (1) of semi-rigid foam with open communicating cells constitutes the mass of the assembly functioning according to the mass-spring principle, while the layer (2) of bonded fibers or of flexible cellular material constitutes the spring of this assembly. The foam comprising the plate (1) is preferably a semi-rigid polyurethane foam of a density ranging from 20 kg/m³ to 50 Kg/m³, of a thickness comprised between 5 mm and 15 mm and whose permeability to air is comprised between 5 liters per minute and 45 liters per minute for a specimen 80 mm in diameter. The layer (2) constituting the spring has a stiffness ranging from 0.007 MPa to 0.05 MPa and a thickness ranging from 4 mm to 10 mm.

Claims

1. A panel absorbing acoustical energy at low, medium and high frequencies ranging from 400 Hz to 5,000 Hz, which comprises a plate (1) of semi-rigid foam with open communicating cells and a layer (2) of bonded fibers or a flexible cellular material superposed on and secured to said plate (1) to form an assembly, the assembly acting according to a mass-spring principle, or wherein the foam of the plate (1) is a semi-rigid polyurethane foam of a density ranging from 20 Kg/m³ to 50 Kg/M³, of a thickness ranging from 5 mm to 15 mm and whose permeability to air ranges from 5 liters per minute to 45 liters per minute for a specimen 80 mm in diameter.

2. A panel according to claim 1, wherein the plate (1) of semi-rigid foam with open communicating cells constitutes the mass of the assembly functioning according to the mass-spring principle, while the layer (2) of bonded fibers or of flexible cellular material constitutes the spring of this assembly.

3. A panel according to claim 1, wherein the layer (2) forming the spring is a cellular material selected from the group consisting of flexible polyurethane foam, latex foam rubber and foam rubber.

4. A panel according to claim 1, wherein the layer (2) forming a spring is bonded fibers.

5. A panel absorbing acoustical energy at low, medium and high frequencies ranging from 400 Hz to 5,000 Hz, which comprises a plate (1) of semi-rigid foam with open communicating cells and a layer (2) of bonded fibers or a flexible cellular material superposed on and secured to said plate (1) to form an assembly, the assembly acting according to a mass-spring principle, or wherein the layer (2) constituting the spring and formed by a sheet of bonded fibers or by a flexible cellular material, has a stiffness ranging from 0.007 MPa to 0.05 MPa and a thickness ranging from 4 mm to 10 mm.

6. A panel according to claim 5, wherein the layer (2) forming the spring is a cellular material selected from the group consisting of flexible polyurethane foam, latex foam rubber and foam rubber.

7. A panel according to claim 5, wherein the layer (2) forming a spring is bonded fibers.

8. A panel absorbing acoustical energy at low, medium and high frequencies ranging from 400 Hz to 5,000 Hz, which comprises a plate (1) of semi-rigid foam with open communicating cells and a layer (2) of bonded fibers or a flexible cellular material superposed on and secured to said plate (1) to form an assembly, the assembly acting according to a mass-spring principle, or wherein said layer (2) is 40% to 80% of polyester fibers having a titre ranging from 4 decitex to 20 decitex, and 20% to 60% of thermofusible fibers having a titre ranging from 4 decitex to 20 decitex.

9. A panel according to claim 8, wherein the layer (2) is about 70% polyester fibers having a titre of 6.7 decitex and about 30% of thermofusible fibers having a titre of 4 decitex.