JP5688538B2 - Sound absorbing structure - Google Patents

Description

  The present invention relates to a sound absorbing structure applied to a silencer provided at an intake port of a turbocharger for a diesel engine, for example.

  2. Description of the Related Art In an axial exhaust turbocharger for a diesel engine, an intake silencer incorporating a plurality of intake elements is arranged on the compressor inlet side (see Patent Documents 1 and 2).

JP 2006-194161 A JP 2005-069228 A

  The intake silencer provided on the intake side of the compressor of such a turbocharger requires high sound absorption performance in a wide frequency range (1/3 octave band center frequency) from 0.63 to 3.15 kHz and from midrange to high range. Is done. In order to ensure high sound absorption performance from the mid-range to the high-frequency range with conventional sound-absorbing materials, it is necessary to increase the thickness of the sound-absorbing material. As the frequency increases, the sound absorption performance in the high sound range tends to decrease.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a sound absorbing structure capable of realizing suitable sound absorbing performance in a wide frequency band while suppressing thickness.

In order to solve the above problems, a sound absorbing structure of the present invention includes a first sound absorbing material and a second sound absorbing material disposed on both surfaces of the first sound absorbing material, and the first sound absorbing material. The bulk density of the second sound absorbing material is larger than the bulk density of the second sound absorbing material, and the second sound absorbing material sandwiches the first sound absorbing material by folding the second sound absorbing material formed integrally. A first fixing member that fixes the end portion of the first sound absorbing material and the both end portions of the second sound absorbing material to each other on the side where both end portions of the second sound absorbing material face each other; The first sound absorbing material and the second sound absorbing material are bent and formed in a convex shape from the first fixing member side toward the side where the second sound absorbing material is bent. To do.

  According to such a configuration, sound absorption is performed by two types of sound absorbing materials having different bulk densities, so that sound can be absorbed in a wide frequency band (medium / high sound range (0.63 to 3.15 kHz)) while suppressing thickness. In addition, sound waves are first input to the second sound absorbing material having a low bulk density, and then input to the first sound absorbing material having a high bulk density, so that the sound waves are emitted from the second sound absorbing material and the first sound absorbing material. Since much sound incident energy is converted into thermal energy when entering the sound absorbing material, more suitable sound absorbing performance can be realized.

The sound absorbing structure further includes a nonwoven fabric or film disposed on a surface of the second sound absorbing material opposite to the first sound absorbing material, and the nonwoven fabric or film is integrally formed. The first sound absorbing material and the second sound absorbing material are sandwiched by bending a nonwoven fabric or a film, and the first fixing member may be configured to further fix both ends of the nonwoven fabric or film. .

  According to such a configuration, it is possible to ensure sound absorption performance in a wide frequency band mid to high range (0.63 to 3.15 kHz) while suppressing the thickness of the second sound absorbing material. Moreover, since various processes, such as a water-repellent process, can be given to the outer surface of a nonwoven fabric or a film, the durability performance of a sound absorption structure can be improved.

In addition, the sound absorbing structure includes a pair of surface protective materials that can transmit sound waves, disposed on a surface of the second sound absorbing material opposite to the first sound absorbing material, and the first fixing member. A pair of second fixing members that fix the first sound absorbing material and the second sound absorbing material and the pair of surface protective materials fixed at both ends of the surface protective material , The pair of surface protective materials are bent and formed in a convex shape, and the first sound absorbing material and the second sound absorbing material are bent and formed in a convex shape by being sandwiched between the pair of surface protective materials. It may be a configuration.

  According to such a configuration, it is possible to suitably protect the first sound absorbing material and the second sound absorbing material from an object collision or the like. In addition, what is necessary is just to arrange | position a nonwoven fabric or a film between a 2nd sound-absorbing material and a surface protection material, when employ | adopting both a nonwoven fabric or a film and a surface protection material.

  The first sound absorbing material may be composed of a plurality of layers.

  According to such a configuration, even when the surface protective material has a curved surface shape, the alongness of the assembly of the first sound absorbing material and the second sound absorbing material with respect to the surface protective material can be improved.

  The first sound absorbing material and the second sound absorbing material may be formed of polymer fibers.

According to this configuration, the sound absorbing structure can be thinned while ensuring sound absorbing performance.
Moreover, the structure by which the notch extended in the direction orthogonal to a convex shape may be formed in the convex side surface of said 1st sound-absorbing material may be sufficient.

  ADVANTAGE OF THE INVENTION According to this invention, suitable sound absorption performance is realizable in a wide frequency band, suppressing thickness.

It is a partially broken perspective view which shows the supercharger which concerns on embodiment of this invention. It is a disassembled perspective view which shows the intake silencer of FIG. It is a disassembled perspective view which shows the sound absorption structure of FIG. It is a side view which shows the sound absorption structure of FIG. It is a side view which shows the assembly of the 1st sound absorption material of the sound absorption structure which concerns on other embodiment of this invention, the 2nd sound absorption material, and a nonwoven fabric. It is a graph which shows the sound absorption rate of the 1st Example of this invention. It is a graph which shows the sound absorption rate of the 2nd Example of this invention. It is a graph which shows the sound absorption rate of the 3rd Example of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate, taking as an example the case where the sound absorbing structure of the present invention is applied to an intake silencer provided at the intake port of a turbocharger for a diesel engine. Similar parts are denoted by the same reference numerals, and redundant description is omitted.

≪Supercharger≫
As shown in FIG. 1, a supercharger 1 according to an embodiment of the present invention is an axial exhaust turbocharger applied to a diesel engine, and an exhaust turbine casing 11 including a casing 11a and a casing 11b. And a compressor casing 12, a turbine shaft 13 extending between the exhaust turbine casing 11 and the compressor casing 12, and an intake silencer 20 provided on the intake port side of the compressor casing 12. The turbine shaft 13 is rotatably supported around an axis by a bearing (not shown). A turbine disk 13 a having turbine blades is attached to the end of the turbine shaft 13 on the exhaust turbine casing 11 side, and a compressor wheel 13 b is attached to the end of the compressor casing 12 side. The turbocharger 1 rotates the turbine shaft 13 by the exhaust gas supplied into the casing 11b, compresses the air supplied to the intake port side of the compressor casing 12 via the intake silencer 20, and compresses the compressed air into the compressor casing. It discharges from 12 discharge ports 12a.

≪Intake silencer≫
As shown in FIG. 2, the intake silencer 20 according to the embodiment of the present invention includes a holding body 21, a cylindrical portion (punching plate) 22, a cylindrical portion (filter mat) 23, lashing belts 24 a to 24 c, The sound absorbing structures 30, 30,.

  The holding body 21 includes a pair of disc portions 21a and 21b arranged to face each other and a plurality of wall portions (ribs) 21c, 21c,... That connect these disc portions 21a and 21b. A plurality of holes 21b1, 21b1,... For inserting the sound absorbing structure 30 are formed in the disc portion 21b. The wall portions (ribs) 21c are provided along the radial direction of the disk portions 21a and 21b, and are bent so as to protrude toward the rotation direction R of the turbine shaft 13 (see FIG. 1). The cylindrical portion (punching plate) 22 has an inner diameter substantially the same as the outer diameter of the disk portions 21 a and 21 b formed to the same diameter, and the cylindrical portion (filter mat) 23 is substantially the same as the outer diameter of the cylindrical portion 22. Presents the inner diameter. That is, the holding body 21, the cylindrical portion 22, and the cylindrical portion 23 are arranged in this order from the inside. The cylindrical portion (punching plate) 22 is fixed to the holding body 21 by a turnbuckle (not shown), and the cylindrical portion (filter mat) 23 is provided by lashing belts 24 a to 24 c provided on the outer periphery of the cylindrical portion 23. The holder 21 and the cylindrical portion (punching plate) 22 are fixed to the assembly.

  The plurality of sound absorbing structures 30, 30,... Mainly absorb noise generated in the compressor casing 12, and are accommodated in the holding body 21 from the plurality of holes formed in the disk portion 21b. The The sound absorbing structure 30 is formed so as to be convex toward the rotation direction R (see FIG. 2) of the turbine shaft 13 (see FIG. 1), similarly to the wall 21c (see FIG. 1). This is a measure for facilitating the flow of air supplied to the compressor casing 12.

≪Sound absorption structure≫
As shown in FIGS. 3 and 4, the sound absorbing structure 30 includes a first sound absorbing material 31, a second sound absorbing material 32, a nonwoven fabric 33, and a pair of surface protection materials 34 and 34.

  The first sound absorbing material 31 is a flat plate member made of polymer fibers such as polyester, and can absorb sound by converting the sound incident energy of sound waves input from both surfaces into heat energy.

  The second sound absorbing material 32 is a flat plate member made of polymer fibers such as polyester and disposed on both surfaces of the first sound absorbing material 31, and the sound incident energy of sound waves input from both surfaces is used as thermal energy. Sound can be absorbed by conversion. In the present embodiment, the second sound absorbing material 32 is arranged so as to be bent and sandwich the first sound absorbing material 31.

  The first sound absorbing material 31 and the second sound absorbing material 32 may be formed from a polymer foamed material such as flexible urethane foam, and further, inorganic fibers such as glass wool and rock wool. It may be formed from a metal material or a metal fiber material, or may be formed from a metal foam material such as aluminum.

The nonwoven fabric 33 is disposed between the second sound absorbing material 32 and the surface protective material 34. The nonwoven fabric 33 may be made of a polymer material such as polyester, polyethylene or nylon, or may be a paper nonwoven such as Japanese paper. In the present embodiment, the nonwoven fabric 33 is heat-sealed to the entire outer surface of the second sound absorbing material 32 using a hot melt material. The hot melt material is a powder, network or fiber formed from a polymer material such as polyester, nylon, polypropylene or olefin, and has a surface weight of 20 to 200 g / m ² having a flow resistance of 0.5 × 10 ^{4 to} 5 × 10 ⁴ N · sec / m ⁴ and a melting point of 70 to 180 ° C. can be suitably used. In particular, a spunbonded nonwoven fabric having a flow resistance of 3.5 × 10 ^{5 to} 7.0 × 10 ⁶ N · sec / m ⁴ can be suitably used as the nonwoven fabric 33 according to this embodiment. Moreover, the nonwoven fabric 33 is not limited to one layer, The structure which has several layers comprised from the different nonwoven fabric may be sufficient. Moreover, the structure by which the water repellent process, the flame retardant process, the weather resistance process, the light resistance process, the antifouling process, etc. were given to the outer surface of the nonwoven fabric 33 may be sufficient. According to this configuration, the durability performance of the sound absorbing structure 30 can be improved.

  In addition, it may replace with the nonwoven fabric 33 and the structure by which a film is arrange | positioned between the 2nd sound-absorbing material 32 and the surface protection material 34 may be sufficient. As such a film, a film formed from a polymer material such as polyester, nylon, polyethylene, and vinyl chloride can be suitably used. The thickness of the film is preferably 25 μm or less so as not to affect the sound absorption performance in the high sound range.

  The pair of surface protection members 34, 34 emit sound waves through a plurality of openings 34 a, 34 a disposed on the outer surface of the second sound absorbing material 32 (the surface opposite to the first sound absorbing material 31). It is a permeable member, and is bent so as to be convex toward the rotation direction R (see FIG. 2) of the turbine shaft 13 (see FIG. 1), like the wall 21c (see FIG. 1). As the surface protective material 34, a metal member having an opening, such as a wire mesh or a punching metal, can be preferably used, and the opening ratio is desirably 20% or more.

  Here, the manufacturing method of the sound absorbing structure 30 according to the present embodiment will be briefly described. First, the nonwoven fabric 33 is thermally fused to one surface of the second sound absorbing material 32. Subsequently, by bending the second sound absorbing material 32 with the nonwoven fabric 33 so that the nonwoven fabric 33 becomes the outer surface, the first sound absorbing material 31 is sandwiched, and on the side where both ends of the second sound absorbing material 32 face each other, The first sound absorbing material 31 and the second sound absorbing material 32 (with the nonwoven fabric 33) are fixed by the fixing member A1. Subsequently, the surface protection members 34 and 34 are arranged on both surfaces of the assembly obtained in the above process, and the assembly and the surface protection members 34 and 34 are fixed by the pair of fixing members A2 and A3.

  The second sound absorbing material 32 is preferably in a longitudinal orientation (fibers are arranged so as to extend in the thickness direction of the second sound absorbing material 32). According to such a configuration, the first sound absorbing material 31 can be suitably deformed when bent so as to be sandwiched or bent along the surface protective material 34. In addition, by forming a cut 31a extending in a direction perpendicular to the convex shape on the convex side surface of the first sound absorbing material 31, the cut 31a is opened at the time of bending, and is easily bent along the surface protective material 34. There may be.

Sound waves are input to both sides of the sound absorbing structure 30 according to the present embodiment. The input sound wave is input to the second sound absorbing material 32 via the surface protective material 34 and the nonwoven fabric 33, and the sound incident energy of the sound wave is converted into heat energy by the second sound absorbing material 32. Of the sound wave input to the second sound absorbing material 32, the portion not converted into thermal energy is subsequently input to the first sound absorbing material 31, and the first has a bulk density higher than that of the second sound absorbing material 32. The sound absorbing material 31 converts the acoustic incident energy of the sound wave into heat energy. Thus, since the sound absorbing structure 30 according to the embodiment of the present invention absorbs sound by the two types of sound absorbing materials 31 and 32 having different bulk densities, the sound absorbing structure 30 can absorb sound in a wide frequency band while suppressing the thickness. In addition, sound waves are emitted from the second sound absorbing material 32 by first being input to the second sound absorbing material 32 having a low bulk density and then input to the first sound absorbing material 31 having a large bulk density. Therefore, when a large amount of sound incident energy is converted into thermal energy when entering the first sound absorbing material 31, more suitable sound absorbing performance can be realized. In addition, the sound absorbing structure 30 according to the present embodiment absorbs sound by converting the sound incident energy of sound waves input from both sides thereof into thermal energy, and thus is suitable for the intake silencer 20 in which air flows on both sides. is there.
The bulk density of the first sound absorbing material 31 is preferably 25 to 90 kg / m ³ , and the bulk density of the second sound absorbing material 32 is desirably 5 to ³⁰ kg / m ³ . According to this configuration, the first sound absorbing material 31 absorbs sound waves in a relatively middle sound range (0.63 to 1.25 kHz), and the second sound absorbing material 32 has a high sound frequency range (1.00 to 4.00 kHz). While absorbing sound waves, the sound absorbing effect can be enhanced by the interaction of the first sound absorbing material 31 and the second sound absorbing material 32, so that suitable sound absorbing performance is realized in a wide frequency band of 0.63 to 3.15 kHz. can do.

  In addition, in the said embodiment, although the 1st sound absorption material 31 is comprised from the single layer, as shown in FIG. 5, the 1st sound absorption material 31 may be comprised from the multiple layer. In FIG. 5 (a), the first sound absorbing material 31 is composed of a six-layer plate member, and in FIG. 5 (b), the first sound absorbing material 31 is composed of a seven-layer plate member. Has been. Of the plurality of layers of plate-like members, the central one is long and the ones at both ends are short, so that the first sound-absorbing material 31 and the second sound-absorbing material for the surface protecting material 34 having a curved surface shape are formed. The alongness of the assembly of 32 and the nonwoven fabric 33 can be improved, and the resistance of the assembly to the surface protective material 34 can be reduced. In FIG. 5, the thickness of the sound absorbing structure 30 is exaggerated in order to explain the multi-layer structure.

  Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a graph showing the sound absorption rate of the first embodiment of the present invention. FIG. 7 is a graph showing the sound absorption rate of the second embodiment of the present invention. FIG. 8 is a graph showing the sound absorption rate of the third embodiment of the present invention.

In the first embodiment, a plate member made of polyester having a bulk density of about 80 kg / m ³ and a thickness of about 10 mm is used as the first sound absorbing material 31, and a bulk density of about 10 kg is used as the second sound absorbing material 32. / M ³ , a polyester plate-like member having a thickness of about 10 mm, and a non-woven fabric 33 having a thickness of about 0.3 mm and a flow resistance of 5.0 × 10 ⁵ N · sec / m ⁴ made of polyester. Is used to manufacture a sample of the sound absorbing structure 30 having a thickness of about 30 mm and a diameter of 100 mm, and the sound absorption coefficient at 1/3 octave band frequency of the sound absorbing structure 30 is reflected by incident sound waves perpendicularly to the sample. The energy of the sound wave was measured, and the sound absorption coefficient was calculated based on the difference between the energy of the incident sound wave and the energy of the reflected sound wave.
In the comparative example, the sound absorption coefficient at 1/3 octave band frequency of a conventional sound absorbing structure made of glass wool having a bulk density of about 50 kg / m ³ and a thickness of about 30 mm was measured by a normal incidence method.
As shown in FIG. 6, the sound absorbing structure 30 according to the first embodiment exhibits higher sound absorbing performance than the sound absorbing structure according to the comparative example in the middle and high sound range (0.63 to 3.15 kHz). I understood.

In the second embodiment, a polyester plate-like member having a bulk density of about 80 kg / m ³ and a thickness of about 10 mm is used as the first sound absorbing material 31, and a bulk density of about 10 kg is used as the second sound absorbing material 32. / M ³ , a plate member made of polyester having a thickness of about 10 mm, a polyethylene film having a thickness of 25 μm as a film instead of the nonwoven fabric 33, and a sound absorbing structure 30 having a thickness of about 30 mm and a diameter of about 100 mm The sound absorption coefficient at 1/3 octave band frequency of the sound absorbing structure 30 was measured by the normal incidence method.
In the comparative example, the sound absorption coefficient at 1/3 octave band frequency of a conventional sound absorbing structure made of glass wool having a bulk density of about 50 kg / m ³ and a thickness of about 30 mm was measured by a normal incidence method.
As shown in FIG. 7, the sound absorbing structure 30 according to the second embodiment exhibits higher sound absorbing performance than the sound absorbing structure according to the comparative example in the middle and high sound range (0.63 to 3.15 kHz). I understood.

In the third embodiment, as the first sound absorbing material 31, a multi-layer structure is formed by using two plate members made of polyester having a bulk density of about 80 kg / m ³ and a thickness of about 5 mm. A plate member made of polyester having a bulk density of about 10 kg / m ³ and a thickness of about 10 mm is used as the sound absorbing material 32, and a thickness of about 0.3 mm and a flow resistance of 5.0 × 10 ⁵ N · sec / A sample of a sound absorbing structure 30 having a thickness of about 30 mm and a diameter of about 100 mm is manufactured using a spun-pound nonwoven fabric made of polyester of m ⁴ , and the sound absorption coefficient at 1/3 octave band frequency of the sound absorbing structure 30 is determined by a normal incidence method Measured with.
In the comparative example, the sound absorption coefficient at 1/3 octave band frequency of a conventional sound absorbing structure made of glass wool having a bulk density of about 50 kg / m ³ and a thickness of about 30 mm was measured by a normal incidence method.
As shown in FIG. 8, the sound absorbing structure 30 according to the third embodiment exhibits higher sound absorbing performance than the sound absorbing structure according to the comparative example in the middle and high sound range (0.63 to 3.15 kHz). I understood.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A design change is possible suitably in the range which does not deviate from the summary of this invention. The sound absorbing structure 30 of the present invention can be applied to a turbocharger such as an axial exhaust turbocharger applied to a diesel engine used for power generation on a ship or land. Further, the sound absorbing structure 30 of the present invention is replaced with a configuration in which the first sound absorbing material 31 is sandwiched by bending the second sound absorbing material 32, and the first sound absorbing structure 32 is formed by two flat plate-like second sound absorbing materials 32. The sound absorbing material 31 may be sandwiched.

DESCRIPTION OF SYMBOLS 1 Supercharger 20 Intake silencer 30 Sound absorption structure 31 First sound absorption material 32 Second sound absorption material 33 Nonwoven fabric (or film)
34 Surface protective material

Claims (6)

A first sound absorbing material;
A second sound absorbing material disposed on both sides of the first sound absorbing material;
With
The bulk density of the first sound absorbing material is greater than the bulk density of the second sound absorbing material ,
The second sound absorbing material sandwiches the first sound absorbing material by bending the second sound absorbing material formed integrally,
On the side where both end portions of the second sound absorbing material face each other, the first sound absorbing material end portion and the second sound absorbing material both end portions are provided with a first fixing member for fixing each other,
The first sound absorbing material and the second sound absorbing material are bent and formed in a convex shape from the first fixing member side toward the side where the second sound absorbing material is bent. Sound absorbing structure. A non-woven fabric or a film disposed on the surface of the second sound absorbing material opposite to the first sound absorbing material ;
The non-woven fabric or film sandwiches the first sound absorbing material and the second sound absorbing material by folding the integrally formed non-woven fabric or film,
The sound absorbing structure according to claim 1, wherein the first fixing member further fixes both ends of the nonwoven fabric or film . A pair of surface protective materials that are disposed on a surface of the second sound absorbing material opposite to the first sound absorbing material and are capable of transmitting sound waves ;
A pair of second fixing members for fixing the first sound absorbing material and the second sound absorbing material fixed by the first fixing member and the pair of surface protective materials at both ends of the surface protective material; ,
Further comprising a,
The pair of surface protection materials are formed to be bent in a convex shape,
It said first sound absorbing material and the second sound absorbing material, by being sandwiched with the pair of the surface protective material, according to claim 1, characterized in <br/> Rukoto which is bent in a convex shape Sound absorbing structure. The sound absorbing structure according to any one of claims 1 to 3, wherein the first sound absorbing material includes a plurality of layers. The sound absorbing structure according to any one of claims 1 to 4, wherein the first sound absorbing material and the second sound absorbing material are formed of polymer fibers.   A notch extending in a direction orthogonal to the convex shape is formed on the convex side surface of the first sound absorbing material.
  The sound absorbing structure according to any one of claims 1 to 5, wherein the sound absorbing structure is provided.

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