# US 6,720,069 B1 · Sound absorbing structure > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,720,069 B1 - Document ID: US6720069B1 - Status: Granted - Kind: B1 - Application number: 09/482,731 - Filed: 2000-01-14 - Granted: 2004-04-13 - Earliest claimed: 1999-01-14 - Assignees: Nichias Corporation - Inventors: Atsushi Murakami; Shuuchirou Wada; Kazuo Nishimoto; Takahiro Niwa; Hiroto Sugai; Haruko Sasaki - Web page: https://patentgrep.com/patent/US6720069B1 ## CPC - G10K 11/16: Methods or devices for protecting against, or for damping, noise or other acoustic waves in general (G10K11/36 takes precedence) - B29C 44/5627: {by mechanical deformation, e.g. crushing, embossing, stretching} - B29K 2105/04: cellular or porous - B29L 2009/00: Layered products - Y10T 428/24273: including aperture - Y10T 428/24298: Noncircular aperture [e.g., slit, diamond, rectangular, etc.] - Y10T 428/24364: with transparent or protective coating - Y10T 428/24405: Polymer or resin [e.g., natural or synthetic rubber, etc.] - Y10T 428/24479: including variation in thickness - Y10T 428/24496: Foamed or cellular component - Y10T 428/24512: Polyurethane - Y10T 428/24983: Hardness - Y10T 428/24992: Density or compression of components - Y10T 428/249991: Synthetic resin or natural rubbers - Y10T 428/249992: Linear or thermoplastic - G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS - B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A sound absorbing structure comprising at least one porous member including a plurality of holes, and the holes are at least one kind of through holes and non-through holes. It is preferable that a plurality of porous members are stacked. It is also preferable that the holes of porous members are formed as diameter-varied holes, and an area of opening of each diameter-varied hole formed in the surface opposite to a sound source is largest and the area of opening of each the diameter-varied hole is reduced in a direction of the thickness of the porous member. Moreover, it is also preferable that the sound absorbing structure further comprises a coating film formed on at least a surface of the porous member which is opposite to a sound source wherein the holes penetrates the coating film and the porous member. ## Claims ### Claim 1 A sound absorbing structure comprising at least one porous member including a plurality of holes, wherein said holes are at least one kind of through holes, that penetrate through the porous member, and/or non-through holes, that extend into but do not penetrate through the porous member, wherein 25%-compressive hardness of said porous member is 0.5 N/cm2 or lower, the sound absorbing structure further comprising a coating film formed on at least a surface of said porous member which is opposite to a sound source wherein said holes penetrate said coating film and said porous member, wherein a main component of said porous member is one of urethane foam and a molded fibrous material. ### Claim 2 (depends on 1) The sound absorbing structure according to claim 1, wherein said porous member includes a structure formed by mixing open-cells and closed-cells. ### Claim 3 (depends on 1) The sound absorbing structure according to claim 1, wherein said through holes and non-through holes have plural type of diameters, shape of openings and depths. ### Claim 4 (depends on 1) The sound absorbing structure according to claim 1, wherein the coefficient of water absorption of said porous member is in the range between 0.01 g/cm3 and 0.2 g/cm3, and the bulk density before said holes are provided is in the range between 20 kg/m3 and 400 kg/m3. ### Claim 5 (depends on 1) The sound absorbing structure according to claim 1, wherein a thickness of said porous member varies according to the position, and at least any one of the diameter, the shape of opening, the depth and the position of said holes of said porous member varies according to the thickness. ### Claim 6 (depends on 1) An engine cover comprising a sound absorbing structure according to claim 1. ### Claim 7 (depends on 1) The sound absorbing structure according to claim 1, wherein said holes of porous members are formed as diameter-varied holes, and an area of opening of each said diameter-varied hole formed in the surface opposite to a sound source is largest and the area of opening of each said diameter-varied hole is reduced in a direction of the thickness of said porous member. ### Claim 8 (depends on 7) The sound absorbing structure according to claim 7, wherein the sum of the areas of opening of said diameter-varied holes formed in the surface opposite to the sound source is in the range between 1% and 70%. ### Claim 9 (depends on 7) The sound absorbing structure according to claim 7, wherein the coefficient of water absorption of said porous member is in the range between 0.01 g/cm3 and 0.2 g/cm3, and the bulk density is in the range between 20 kg/m3 and 400 kg/m3. ### Claim 10 (depends on 7) The sound absorbing structure according to claim 7, wherein the thickness of said porous member varies according to the position, and at least any one of the shape of opening, the depth, and the position of each of said diameter-varied holes is varied according to the thickness. ### Claim 11 (depends on 7) An engine cover for an automobile comprising a sound absorbing structure according to claim 7. ### Claim 12 (depends on 1) The sound absorbing structure according to claim 1, wherein said porous member includes continued voids. ### Claim 13 (depends on 1) The sound absorbing structure according to claim 1, wherein a ratio of areas of openings of said holes opened in the surface having said coating film formed thereon is in the range of 1% and 70%. ### Claim 14 (depends on 1) A sound insulation cover comprising a sound absorbing member according to claim 1. ### Claim 15 (depends on 1) The sound absorbing structure according to claim 1, wherein said holes are holes that penetrate through the porous member, said holes extending through the sound absorbing structure. ### Claim 16 (depends on 1) The sound absorbing structure according to claim 1, wherein the sound absorbing structure is without a rear air layer. ### Claim 17 A sound absorbing structure comprising at least one porous member including a plurality of holes, wherein said holes are at least one kind of through holes, that penetrate through the porous member, and/or non-through holes, that extend into but do not penetrate through the porous member, wherein 25%-compressive hardness of said porous member is 0.5 N/cm2 or lower, wherein a plurality of porous members are stacked, the sound absorbing structure further comprising a coating film formed on at least a surface of said porous member which is opposite to a sound source wherein said holes penetrate said coating film and said porous member, wherein a main component of said porous member is one of urethane foam and a molded fibrous material. ### Claim 18 (depends on 17) The sound absorbing structure according to claim 17, wherein said porous member includes a structure formed by mixing open-cells and closed-cells. ### Claim 19 (depends on 17) The sound absorbing structure according to claim 17, wherein said porous members are stacked along at least one interface of the porous members such that either of said porous members is not secured to another porous member. ### Claim 20 (depends on 17) The sound absorbing structure according to claim 17, wherein said porous members are stacked along at least one interface of the porous members such that either of said porous members is partially secured to another porous member. ### Claim 21 (depends on 20) The sound absorbing structure according to claim 20, wherein the sum of areas with which said porous members are secured to each other is not larger than 50% of the area of the interface. ### Claim 22 (depends on 20) The sound absorbing structure according to claim 20, wherein said porous members are secured to each other by fixing using one of a plurality of pins and sewing. ### Claim 23 (depends on 17) The sound absorbing structure according to claim 17, wherein the coefficient of water absorption of said porous member is in the range between 0.01 g/cm3 and 0.2 g/cm3. ### Claim 24 (depends on 17) The sound absorbing structure according to claim 17, wherein the bulk density of said porous member is in the range between 20 kg/m3 and 400 kg/m3. ### Claim 25 (depends on 17) An engine cover for an automobile comprising a sound absorbing structure according to claim 17. ### Claim 26 (depends on 25) The engine cover according to claim 25, wherein said sound absorbing structure is secured to a cover body using at least one of pins, covering with a net, and sewing. ### Claim 27 (depends on 17) The sound absorbing structure according to claim 17, wherein said porous members include plural types of diameter-varied holes, the areas of opening of which are different from one another, and said through holes are positioned coaxially. ### Claim 28 (depends on 27) The sound absorbing structure according to claim 27, wherein the sum of the areas of opening of said diameter-varied holes formed in the surface opposite to the sound source is in the range between 1% and 70%. ### Claim 29 (depends on 27) The sound absorbing structure according to claim 27, wherein the coefficient of water absorption of said porous member is in the range between 0.01 g/cm3 and 0.2 g/cm3, and the bulk density is in the range between 20 kg/m3 and 400 kg/m3. ### Claim 30 (depends on 27) The sound absorbing structure according to claim 27, wherein the thickness of said porous member varies according to the position, and at least any one of the shape of opening, the depth and the position of each of said diameter-varied holes is varied according to the thickness. ### Claim 31 (depends on 27) An engine cover for an automobile comprising a sound absorbing structure according to claim 27. ### Claim 32 (depends on 17) The sound absorbing structure according to claim 17, wherein a total area of openings of said holes of said sound absorbing member disposed nearest the sound source is largest, the total area of openings of said through holes is gradually reduced as the distance form the sound source is increased and said through holes have the same center. ### Claim 33 (depends on 17) The sound absorbing structure according to claim 17, wherein said porous member includes continued voids. ### Claim 34 (depends on 17) The sound absorbing structure according to claim 17, wherein a ratio of areas of openings of said holes opened in the surface having said coating film formed thereon is in the range of 1% and 70%. ### Claim 35 (depends on 17) A sound insulation cover comprising a sound absorbing member according to claim 17.