JP2004085641A - Acoustic material and blower with sound absorption apparatus using acoustic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic material which is made into sound absorption ducts having good sound absorption performance and reduces the space for transportation and storage. <P>SOLUTION: The acoustic material 1 is formed by alternately gluing laminated incombustible boards 5 and 7 for sound absorption varying in height onto an outer surface cladding material 3 of a rectangular shape. When the acoustic material 1 is used as the sound absorption duct, the recesses of a rugged surface produced by the boards 5 and 7 are made into air layers 15 of the cavities of a sectionally triangular shape long in the longitudinal direction of the sound absorption duct and since these air layers 15 are disposed over the entire periphery in the duct, the sound absorption coefficient of low-frequency components is improved. Also, the acoustic material is a flat plate shape of the rectangular shape in the developed state before being assembled to the sound absorption duct and therefore the space for transportation and storage is made smaller. <P>COPYRIGHT: (C)2004,JPO

Description

なお、比較例１は上記の実施の形態の吸音装置付送風装置２９で用いられた送風機２７と同様の送風機２７単体のみで吸音材を使用していない場合である。比較例２は同様の送風機２７の周囲に吸音材が設けられ、この吸音材は専用の型に材料を充填して焼結する従来型の円筒型焼結成形吸音材である。比較例３は同様の送風機２７の周囲に吸音材が設けられ、この吸音材は板状に展開時に円筒形状の内面側表面が平滑な円筒型積層成形吸音材である。
【００５７】
また、比較例２，比較例３及びこの実施の形態の例の吸音材は、いずれも密度４０Ｋｇ／ｍ^３で、外形、内径、長さの外形寸法が同一寸法である。
【００５８】
以上の表１の結果から分かるように、この実施の形態の例の場合は、他の比較例と比べて周波数２５０〜１０００ＨＺの間の低周波数領域において吸音効果向上があることが明らかである。
【００５９】
なお、この発明は前述した実施の形態に限定されることなく、適宜な変更を行うことによりその他の態様で実施し得るものである。
【００６０】
【発明の効果】
以上のごとき発明の実施の形態の説明から理解されるように、請求項１の発明によれば、吸音材が吸音ダクトとして使用されるとき、高い方の吸音用ボードが吸音ダクトの厚みとなるので、厚手の吸音性能の良い吸音ダクトとなる。また、吸音用ボードの凹凸面の凹部が、断面三角形状で吸音ダクトの長手方向に長い空洞の空気層となるので、この空気層により低周波成分の吸音率を向上できる。
【００６１】
また、吸音材に凹凸面を設けたので、円筒形状の円周方向に沿ってフレキシビリティを増大せしめ、組立の作業性を向上できる。さらに、空気層の形成部分の材料を歩留まり良く削減できるのでコストダウンを図ることができる。
【００６２】
また、吸音ダクトに組み立てられる前の展開された状態では矩形状の平板形状であるので、輸送や保管のスペースを小さくできる。
【００６３】
請求項２の発明によれば、高い方の吸音用ボードの内側表面を吸音ダクトの送風流路にでき、高さの異なる吸音用ボードの凹凸面の凹部により断面三角形状で吸音ダクトの長手方向に長い空洞の空気層を形成できる。ダクト内の全周に亘って設けられる空気層により低周波成分の吸音率を向上できる。
【００６４】
請求項３の発明によれば、空気流入側では圧力損失が少なく、空気流出側では圧力回収を図ることができる。
【００６５】
請求項４の発明によれば、吸音ダクト形状にされた高さの異なる吸音用ボードの中に送風機を装着すると、この送風機の騒音は吸音用ボードと、断面三角形状で吸音ダクトの長手方向に長い空洞の空気層とから、低周波成分を効率よく吸音できる。
【図面の簡単な説明】
【図１】この発明の実施の形態の吸音材が展開された状態の斜視図である。
【図２】この発明の実施の形態の高さの異なる積層された吸音用ボードの部分的な斜視図である。
【図３】図１の吸音材をロール状にして吸音ダクトに形成する過程の斜視図である。
【図４】図１の吸音材をロール状に形成した吸音ダクトの縦断面である。
【図５】図４の左側面図である。
【図６】ベルマウス形状部と円錐形状部とを備えた吸音材をロール状に形成した吸音ダクトの縦断面である。
【図７】この発明の実施の形態の吸音材を用いた吸音装置付送風装置の縦断面図である。
【図８】図７で用いられる吸音材が展開された状態の斜視図である。
【符号の説明】
１，１７，２３　吸音材
３　外側表被材
５　内外径構成吸音材（高い方の吸音用ボード）
７　スペーサ吸音材（低い方の吸音用ボード）
９　内側表被材
１３　送風流路
１５　空気層
２５　凹み部
２７　送風機
２９　吸音装置付送風装置
３１　チャンバ（外筒）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sound-absorbing material to be used as a product of a sound-absorbing duct and a silencer component for reducing noise generated from a blower, and a blower with a sound-absorbing device using the sound-absorbing material.
[0002]
[Prior art]
2. Description of the Related Art Generally, a blower used for ventilation of a house or a non-residential space, an air conditioner, or the like generates noise and propagates from a piping duct to a room and outdoors. In particular, facilities such as conference rooms, offices, schools, hospitals, and broadcasting stations require quiet ventilation, and thus require a sound absorbing device for reducing the noise.
[0003]
As a conventional sound absorbing device, as shown in Japanese Patent Application Laid-Open No. 2000-283098, a glass fiber-based sound absorbing material having a constant density is provided on an outer peripheral portion of a passage on an upstream side of a blower. Surrounded by shells. In this case, in order to reduce noise at the suction port of the blower, the diameter of the passage of the sound absorbing material is made smaller than the suction port of the fan of the blower, and the diameter of the passage near the suction port is gradually increased to the diameter of the suction port of the fan.
[0004]
Further, as another conventional sound absorbing device, as shown in JP-A-10-103728, two types of sound absorbing materials having different densities are provided on the outer peripheral portion of a ventilation path on an upstream side of a blower, A large sound absorbing material is provided inside, and a low density sound absorbing material is provided outside.
[0005]
[Problems to be solved by the invention]
By the way, in the former conventional sound absorbing device disclosed in Japanese Patent Application Laid-Open No. 2000-283098, the sound absorbing effect is enhanced by deforming the shape of the passage of the sound absorbing material, so that the shape is complicated. Has to be formed in accordance with the size of the blower or the pipe duct, and there is a problem that productivity is not good.
[0006]
As described in the former publication, there is a problem that the sound absorbing effect is not good in a general conventional sound absorbing device in which the passage diameter of the sound absorbing material is the same as the suction port of the blower.
[0007]
Further, in the latter sound absorbing device disclosed in Japanese Patent Application Laid-Open No. 10-103728, two types of sound absorbing materials having different densities are sintered and formed, so that the number of members to be formed by sintering increases, so that productivity is improved. There was no problem.
[0008]
In the conventional sound absorbing device, both the former and the latter are formed in advance into a semi-cylindrical shape or a cylindrical shape by a method such as sintering. There is a problem that a large space is required for storage.
[0009]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a sound-absorbing duct having good sound-absorbing performance and a sound-absorbing material capable of reducing the space for transportation and storage, and a sound-absorbing device using the sound-absorbing material. An object of the present invention is to provide a blowing device.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the sound absorbing material of the present invention according to claim 1 is obtained by alternately bonding laminated nonflammable sound absorbing boards having different heights on at least a rectangular outer covering material. It is characterized by the following.
[0011]
Therefore, when the sound-absorbing material is used as a sound-absorbing duct, the higher sound-absorbing board has the thickness of the sound-absorbing duct, so that the sound-absorbing duct is thick and has good sound-absorbing performance. In addition, the concave portion of the uneven surface generated by the sound absorbing boards having different heights becomes an air layer of a cavity having a triangular cross section and being long in the longitudinal direction of the sound absorbing duct, and this air layer is provided over the entire circumference in the duct, The sound absorption of low frequency components is improved.
[0012]
Further, since the sound absorbing material is provided with the uneven surface, the flexibility increases along the circumferential direction of the cylindrical shape, and the workability of assembly is good. Further, the material for the portion where the air layer is formed is reduced with a good yield, resulting in cost reduction.
[0013]
Further, since the unfolded state before being assembled into the sound absorbing duct has a rectangular flat plate shape, the space for transportation and storage is reduced.
[0014]
The sound absorbing material of the present invention according to claim 2 is the sound absorbing material according to claim 1, wherein the width and the height of the higher sound absorbing board and the lower sound absorbing board are such that the outer covering material is outside. When formed into a cylindrical shape, the inner surface of the higher sound absorbing board is set to be connected in the inner circumferential direction of the cylindrical shape.
[0015]
Therefore, the inner surface of the higher sound-absorbing board serves as a ventilation channel for the sound-absorbing duct, and the concave portion of the uneven surface generated by the sound-absorbing boards having different heights has a triangular cross section and a long air space in the longitudinal direction of the sound absorbing duct. Become. Since this air layer is provided over the entire circumference in the duct, the sound absorption of low frequency components is improved.
[0016]
The sound-absorbing material of the present invention according to claim 3 is the sound-absorbing material according to claim 1 or 2, wherein the uneven surface side of the sound absorbing board is cut into an arc or oblique straight line, and is rolled into a cylindrical shape. The arc-shaped cut portion is formed in a bell mouth shape portion.
[0017]
Therefore, pressure loss is small on the air inflow side, and pressure recovery is achieved on the air outflow side.
[0018]
The blower with a sound absorbing device of the present invention according to claim 4 is an outer cylinder that covers an upstream side and a downstream side of a blower so as to form a ventilation channel, and an outer covering material that contacts an inner peripheral surface of the outer cylinder, A laminated non-combustible sound absorbing board having a different height configured to be alternately bonded in a circumferential direction to an inner circumferential surface of the outer covering material, and an inner surface of the higher sound absorbing board as an inner circumferential surface. A triangular air layer formed by a ventilation passage formed so as to be connected in the direction, a side surface of the higher sound absorbing board adjacent to each other and an inner surface of the lower sound absorbing board, and the sound absorbing board. , And a blower attached to the inside of the recess.
[0019]
Therefore, when the blower is installed in a sound absorbing board of different height in the shape of a sound absorbing duct, the noise of the blower is generated from the sound absorbing board and the air layer of a hollow having a triangular cross section and a long length in the longitudinal direction of the sound absorbing duct. , Low frequency components are efficiently absorbed.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
Referring to FIG. 1 to FIG. 3, the sound absorbing material 1 according to this embodiment is provided with a rectangular outer covering material 3 located on the outer peripheral side when the sound absorbing material 1 has a cylindrical or half-cylindrical shape. On the outer cover material 3, for example, a higher sound absorbing material 5 having a higher inner and outer diameter and a lower sound absorbing material 7 as a non-combustible sound absorbing board having different heights are alternately bonded. .
[0022]
Further, the surface on the uneven surface side of the sound absorbing board composed of the plurality of inner and outer diameter constituent sound absorbing materials 5 and the spacer sound absorbing material 7 is adhered and covered with a generally rectangular inner covering material 9. I have. Actually, the inner cover material 9 is stuck to the surface of the inner and outer diameter sound absorbing material 5, but the spacer sound absorbing material 7 is not stuck because it is located in the concave portion. In this embodiment, each side edge of the inner cover material 9 is provided with a folded portion 11 that is folded back and attached to the side surface of the inner and outer diameter sound absorbing material 5.
[0023]
More specifically, as the outer covering material 3, for example, a material obtained by laminating an aluminum foil having a thickness of 7 μm and a PE warif (a high-density polyethylene nonwoven fabric) having a thickness of 15 μm is used. This material has good adhesiveness and excellent tensile strength during bending.
[0024]
As an adhesive between the outer cover material 3 and the sound absorbing board, for example, a synthetic rubber / synthetic resin-based solvent-type adhesive for glass wool bonding is used.
[0025]
Also, as shown in FIG. 2, the inner and outer diameter sound absorbing material 5 is cut out from a plate-shaped sound absorbing board having a thickness t1 and a length L as a material and having a width L1 so as to form a rod having a rectangular cross section. Alternatively, L1 is a height of the sound absorbing material 1 and t1 is a part of a width of the sound absorbing material 1.
[0026]
Further, as shown in FIG. 2, the spacer sound absorbing material 7 is cut out from a plate-shaped sound absorbing board having a thickness t2 and a length L as a material and cut into a width L2 so as to form a rod having a rectangular cross section or cut or pressed. The t2 is a height dimension of the sound absorbing material 1, and the L2 is a part of a width size of the sound absorbing material 1.
[0027]
In this embodiment, both the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 are made of glass wool having a density of 40 kg / m ³ , for example, laminated at t1 = 50 mm and t2 = 25 mm.
[0028]
As the inner cover material 9, for example, a nonwoven fabric of polyester having a weight of 50 g / m ² and a thickness of 0.3 mm is used as a material having good sound permeability and preventing scattering of sound absorbing material fibers of the sound absorbing board. However, a fiber fixing material such as spraying of maltprene rubber may be used. In this embodiment, the inner cover material 9 is provided. However, even if the inner cover material 9 is not provided, the function as the sound absorbing material 1 is satisfied, so that the inner cover material 9 may be omitted. However, it is desirable that the inner covering material 9 be provided in order to prevent scattering of the sound absorbing material fibers of the sound absorbing board.
[0029]
As a method of manufacturing the sound absorbing material 1, a rod-shaped inner and outer diameter sound absorbing material 5 and a spacer sound absorbing material 7 constituting the sound absorbing material 1 are alternately arranged in a jig mold for manufacturing. A step for mounting the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 is provided in advance in the jig mold for manufacturing so that the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 are in one plane. I have. The rectangular outer covering material 3 is adhered to the entire surface of the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 located on the upper surface of the jig formwork by the adhesive.
[0030]
Thereafter, the jig form for manufacturing is turned over, and the sound absorbing board to which the outer cover material 3 is adhered is taken out of the jig form. Therefore, as the sound absorbing board, the side of the outer cover material 3 has a smooth surface, and the opposite surface has a regular uneven surface. The rectangular inner covering material 9 is entirely adhered to the uneven surface. That is, in practice, the inner cover material 9 is adhered to the surface of the higher inner / outer diameter sound absorbing material 5 and is not adhered to the lower spacer sound absorbing material 7.
[0031]
Referring also to FIG. 3 to FIG. 5, the sound absorbing material 1 as described above is rolled so that the uneven surface of the sound absorbing board is on the inside and the groove of the unevenness is parallel to the center of the cylinder. Thereby, it becomes a product of a cylindrical sound absorbing duct or a silencer part.
[0032]
At this time, the inner surface of the higher sound absorbing material 5 having the inner and outer diameters is connected in the inner circumferential direction of the cylindrical shape to form the inner circumferential wall surface of the sound absorbing duct, in other words, the air flow passage 13. The concave portion of the uneven surface becomes a hollow air layer 15 having a triangular cross section and being long in the longitudinal direction of the duct as shown in FIG. 5, and the air layer 15 is provided over the entire circumference of the duct. Note that the inner cover material 9 located above the spacer sound absorbing material 7 is housed in the triangular air layer 15 as shown in FIGS.
[0033]
Therefore, the dimensions of the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 are set according to the diameter of the duct used. Therefore, for example, the specification of the sound absorbing duct to be manufactured is such that the outer diameter of the cylinder is D1, the inner diameter of the cylinder is D2, the length in the direction of the cylindrical axis is L, and one of the inner and outer diameter sound absorbing materials 5 at the time of molding the cylinder. When the compression allowance is α, a method for setting the dimensions of the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 will be described.
[0034]
The dimensions of the inner and outer diameter sound absorbing material 5 are as follows, assuming that the number of inner and outer diameter forming sound absorbing materials 5 used in a cylinder is n1.
L1 = (D1-D2) / 2 (1)
α = (n1 · t1−π · D2) / n1 (2)
Is required.
[0035]
As described above, t1 and t2 are the thickness t1 as the material of the inner and outer diameter sound absorbing material 5 and the thickness t2 as the material of the spacer sound absorbing material 7. Accordingly, the number n1 of the inner and outer diameter sound absorbing members 5 used is set by the inner diameter of the cylindrical shape, since the thickness t1 of the inner and outer diameter sound absorbing material 5 as a material is related to the circumferential length of the inner diameter of the cylindrical shape.
[0036]
Further, by setting the compression allowance α, it is possible to adjust the repulsion to a good workability. The repulsive force varies depending on the type and size of the sound absorbing material. As an example, a glass wool having a density of 40 kg / m ³ is used as a sound absorbing board, and a cylindrical inner diameter D2 = 300 mm and a cylindrical length L = 1000 mm. In the case of (1), the compression margin α is desirably 0 to 5 mm from the viewpoint that workability is good.
[0037]
The size of the spacer sound-absorbing material 7 is n2 when the number of used spacer sound-absorbing materials 7 in a cylinder is n2.
L2 = (π · D1-n1 · t1) / n2 (3)
Is required. The used number n2 of the spacer sound absorbing materials 7 is alternately arranged with the inner and outer diameter sound absorbing materials 5, and when the inner and outer diameter sound absorbing materials 5 are used in the cylindrical abutting portion, (n1-1) pieces are used. It becomes. However, the same number (n1 = n2) of the inner and outer diameter constituting sound absorbing material 5 and the spacer sound absorbing material 7 may be used.
[0038]
As described above, the width and height dimensions of the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 are determined when the outer covering material 3 is formed in a cylindrical shape with the outer covering material 3 positioned outside. The surface is preset so as to be connected in the inner circumferential direction of the cylindrical shape.
[0039]
According to the above configuration, when the sound absorbing material 1 is formed in a cylindrical shape with the uneven surface side inside as shown in FIGS. 4 and 5, and used as a sound absorbing duct incorporated in a blower unit, the inner and outer diameters are reduced. The height of the sound absorbing material 5 becomes the thickness of the sound absorbing duct, and the sound absorbing duct becomes thick and has good sound absorbing performance.
[0040]
In addition, the concave portion of the uneven surface becomes a hollow air layer 15 having a triangular cross section and being long in the longitudinal direction of the sound absorbing duct, and since the air layer 15 is provided over the entire circumference in the duct, the sound absorbing coefficient of low frequency components is improved. I do. For example, sound absorption performance is improved in the noise spectrum range of 250 to 1000 Hz. Details regarding this point will be described later.
[0041]
Further, when the sound absorbing material 1 is assembled as a sound absorbing duct, since the concave portion is formed, the compression allowance of the inner surface of the duct is small, so that the sound absorbing material 1 and the inner skin material are well bonded without wrinkling of the inner skin material. In addition to being firmly adhered, the appearance is also good.
[0042]
Further, since the sound absorbing material 1 is provided with the uneven surface of the sound absorbing material 1, the flexibility increases along the circumferential direction of the cylindrical shape, and the workability of assembly is good. Further, since the material of the portion where the air layer 15 is formed is reduced with good yield, the cost of the components of the sound absorbing material 1 is reduced.
[0043]
Further, since the sound absorbing material 1 has a rectangular shape before assembly, there is an advantage that a space for transportation and storage can be effectively used.
[0044]
The cylindrical shape of the sound absorbing material 1 is held by the tension of the outer skin material adhered to the sound absorbing material and the repulsive force against the compression of the inner sound absorbing material. In this case, the difference in thickness in the center direction between the two types of inner and outer diameter sound absorbing materials 5 and the spacer sound absorbing material 7 in the center direction of the cylinder is set to an appropriate size, and irregularities are provided inside the cylinder. The repulsive force generated by the compression of the inner peripheral surface side of the inner and outer diameter sound absorbing material 5 can be adjusted. Therefore, since the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 are set in advance to dimensions that can obtain the above-described appropriate repulsive force, handling of roll forming at the time of assembly is simplified.
[0045]
Referring to FIG. 6, a sound absorbing material 17 according to another embodiment of the present invention is substantially the same as sound absorbing material 1 of the above-described embodiment, and the same members will be described with the same reference numerals. The difference will be described in particular. When the sound absorbing material 17 is rolled into a cylindrical shape, the concave and convex surfaces of the inner and outer diameter sound absorbing material 5 and the spacer sound absorbing material 7 are cut into an arc shape or an oblique straight line. As shown in FIG. 6, the arcuate cut portion becomes the bell mouth shape portion 19, and the linear cut portion becomes the conical portion 21 as shown in FIG. The side view of the sound absorbing duct is similar to that of FIG.
[0046]
With the sound absorbing duct having the bell mouth-shaped portion 19 and the conical portion 21 as described above, pressure loss is small on the air inflow side, and pressure recovery is achieved on the air outflow side, thereby contributing to energy saving.
[0047]
Referring to FIG. 7, a sound absorbing material 23 according to another embodiment of the present invention is substantially the same as the sound absorbing material 1 according to the above-described embodiment. Will be described.
[0048]
This sound absorbing material 23 is basically formed with a concave portion 25 for mounting a blower 27 on the uneven surface side of the inner and outer diameter constituting sound absorbing material 5 and the spacer sound absorbing material 7 of the above-described sound absorbing material 1. The recess 25 is cut into a shape along the outer shape of the blower 27 incorporated as shown in FIG. The inner cover material 9 is not adhered to the concave portion 25 but is adhered to the uneven surface side other than the concave portion 25 with an adhesive.
[0049]
The blower 29 with the sound absorbing device in which the blower 27 is incorporated in the recess 25 of the sound absorbing material 23 is an outer cylinder that covers the entire device in order to form the blower flow path 13 on the upstream side and the downstream side of the blower 27. A chamber 31 made of, for example, a steel plate is provided. The chamber 31 is, for example, formed into a cylindrical shape by combining two semi-cylindrical chambers 31A and 31B, and each of the semi-cylindrical chambers 31A and 31B has a flange portion (not shown) at a longitudinal side edge. Is provided.
[0050]
After the outer covering material 3 of the sound absorbing material 23 is laid so as to be inscribed in the inner circumferential surface of one semi-cylindrical chamber 31A, the outer covering material 3 is mounted so that the outer circumferential surface of the blower 27 is fitted into the semicircular concave portion 25. Is done.
[0051]
Next, the remaining portion of the sound absorbing board is formed in a cylindrical shape so that the remaining concave portion 25 is fitted into and covers the remaining outer peripheral surface of the blower 27, and the two side edges of the sound absorbing material 23 are abutted. The portions are connected by an adhesive tape to maintain a cylindrical shape. Therefore, the air flow path 13 is formed by connecting the cylindrical inner surface of the inner and outer diameter constituting sound absorbing material 5 in the inner circumferential direction of the cylindrical shape.
[0052]
In this embodiment, the blower 27 is mounted on an apparatus main body 33 having a suction diameter of 315 mm, a motor 37 supported at a central portion in the apparatus main body 33 via a bracket 35, and a rotating shaft of the motor 37. And a mixed flow fan 27 comprising a fan 39.
[0053]
Next, after another semi-cylindrical chamber 31B is put on the outer peripheral surface of the remaining outer covering material 3 of the sound absorbing material 23, the flange portions at the side edges of the two semi-cylindrical chambers 31A and 31B are butted. The flange is connected by, for example, a plurality of bolts. A side view of the sound absorbing duct at this time is in a state similar to FIG.
[0054]
Further, a doughnut-shaped round panel 41 made of, for example, a steel plate is attached to a side surface of the cylindrical chamber 31 on the suction side and the sound absorbing material 23 of the blower 29 with the sound absorber, and a discharge side of the blower 29 with the sound absorber. A round panel 43 is similarly attached to the side surfaces of the cylindrical chamber 31 and the sound absorbing material 23.
[0055]
In order to investigate the sound absorbing effect of the blower 29 with the sound absorbing device configured as described above, comparison was made with Comparative Examples 1 to 3 as shown in Table 1. When the noise spectrum center frequency (HZ) is in the range of 63 to 8000, the sound pressure value after passing through the duct [unit: dB (A)] is measured with respect to the noise spectrum generated from the blower 27 of the sound source. It was done.
[0056]
[Table 1]

Note that Comparative Example 1 is a case where only the same blower 27 as the blower 27 used in the blower 29 with the sound absorbing device of the above embodiment does not use the sound absorbing material. In Comparative Example 2, a sound absorbing material is provided around the same blower 27, and this sound absorbing material is a conventional cylindrical sintered molded sound absorbing material in which a dedicated mold is filled with a material and sintered. In Comparative Example 3, a sound absorbing material is provided around the same blower 27, and the sound absorbing material is a cylindrical laminated molded sound absorbing material whose inner surface on the cylindrical shape is smooth when it is developed into a plate shape.
[0057]
The sound absorbing materials of Comparative Examples 2 and 3 and the example of this embodiment all have a density of 40 kg / m ³ and the same outer dimensions such as outer shape, inner diameter, and length.
[0058]
As can be seen from the results of Table 1 above, in the case of the example of this embodiment, it is clear that the sound absorbing effect is improved in the low frequency range between 250 and 1000 HZ as compared with the other comparative examples.
[0059]
The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes.
[0060]
【The invention's effect】
As understood from the above description of the embodiment of the invention, according to the invention of claim 1, when the sound absorbing material is used as the sound absorbing duct, the higher sound absorbing board has the thickness of the sound absorbing duct. Therefore, a thick sound absorbing duct having good sound absorbing performance is obtained. In addition, since the concave portion of the concave-convex surface of the sound absorbing board becomes a hollow air layer having a triangular cross section and being long in the longitudinal direction of the sound absorbing duct, the air layer can improve the sound absorption coefficient of low frequency components.
[0061]
In addition, since the uneven surface is provided on the sound absorbing material, the flexibility can be increased along the circumferential direction of the cylindrical shape, and the workability of assembly can be improved. Further, since the material of the portion where the air layer is formed can be reduced with a good yield, the cost can be reduced.
[0062]
In addition, since the unfolded state before being assembled into the sound absorbing duct has a rectangular flat plate shape, the space for transportation and storage can be reduced.
[0063]
According to the second aspect of the present invention, the inner surface of the higher sound absorbing board can be used as a ventilation channel of the sound absorbing duct, and the recessed portion of the uneven surface of the sound absorbing board having a different height has a triangular cross section and a longitudinal direction of the sound absorbing duct. A long cavity air layer can be formed at a high speed. The air layer provided over the entire circumference in the duct can improve the sound absorption of low frequency components.
[0064]
According to the third aspect of the invention, the pressure loss is small on the air inflow side, and the pressure can be recovered on the air outflow side.
[0065]
According to the invention of claim 4, when the blower is mounted in the sound absorbing boards having different heights in the shape of the sound absorbing duct, the noise of the blower is generated by the sound absorbing board and the triangular cross section in the longitudinal direction of the sound absorbing duct. The low-frequency component can be efficiently absorbed from the air layer having a long cavity.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a state in which a sound absorbing material according to an embodiment of the present invention is developed.
FIG. 2 is a partial perspective view of stacked sound absorbing boards having different heights according to the embodiment of the present invention.
FIG. 3 is a perspective view of a process of forming the sound absorbing material of FIG. 1 into a roll to form a sound absorbing duct.
FIG. 4 is a longitudinal section of a sound absorbing duct in which the sound absorbing material of FIG. 1 is formed in a roll shape.
FIG. 5 is a left side view of FIG. 4;
FIG. 6 is a longitudinal sectional view of a sound-absorbing duct in which a sound-absorbing material having a bellmouth shape portion and a conical shape portion is formed in a roll shape.
FIG. 7 is a longitudinal sectional view of a blower with a sound absorbing device using the sound absorbing material according to the embodiment of the present invention.
FIG. 8 is a perspective view showing a state where the sound absorbing material used in FIG. 7 is developed.
[Explanation of symbols]
1,17,23 Sound absorbing material 3 Outer covering material 5 Inner / outer diameter sound absorbing material (higher sound absorbing board)
7 Spacer sound absorbing material (lower sound absorbing board)
9 Inner surface covering material 13 Ventilation flow path 15 Air layer 25 Depression 27 Blower 29 Blower 31 with sound absorbing device 31 Chamber (outer cylinder)

Claims (4)

A sound-absorbing material comprising laminated non-combustible sound-absorbing boards of different heights alternately bonded on at least a rectangular outer cover material. The width and height dimensions of the higher sound-absorbing board and the lower sound-absorbing board are such that, when the outer covering material is formed outside and in a cylindrical shape, the inner surface of the higher sound-absorbing board is 2. The sound-absorbing material according to claim 1, wherein the sound-absorbing material is set so as to be connected in the inner circumferential direction of the cylindrical shape. 2. The sound absorbing board according to claim 1, wherein the concave-convex surface side of the sound absorbing board is cut into an arc shape or an oblique straight line, and the cut portion in the arc shape is formed into a bell mouth shape portion when rolled into a cylindrical shape. Or the sound absorbing material according to 2. An outer cylinder that covers the upstream side and the downstream side of the blower to form a blowing channel, an outer covering material that contacts an inner peripheral surface of the outer cylinder, and an inner peripheral surface of the outer covering material that extends in a circumferential direction. A stacked non-combustible sound absorbing board having a different height configured to be alternately bonded, and an air flow path formed by connecting an inner surface of the higher sound absorbing board in an inner circumferential direction; A triangular air layer formed by the side surface of the higher sound absorbing board adjacent to each other and the inner surface of the lower sound absorbing board; a recess provided on the inner peripheral surface side of the sound absorbing board; A blower with a sound absorbing device, comprising: a blower mounted inside the unit.

Images