JP2006257993A - Soundproof cover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress secondary noise caused by the vibration of a sound insulating layer while preventing a leakage of noise by maintaining a high sealing performance obtained by the compression of a sound absorbing layer. <P>SOLUTION: The sound insulating layer 1 includes a soft portion 11 of a soft flexible material and a hard portion 10 harder than the soft portion 11. The sound insulating layer 1 is attached to a noise source via the hard portion 10 which also acts as a compressing portion. Force of attachment applied to the hard portion 10 also acting as the compressing portion is certainly transmitted to the sound absorbing layer 2. The sound absorbing layer 2 is attached in such a surely compressed state so that the sealing performance can be secured. Since the sound insulating layer 1 includes the soft portion 11 of the soft flexible material, the vibration of the sound insulating layer 1 is prevented by a damping function of the soft portion 11, thereby further lowering a noise level in a frequency band in the vicinity of 500 Hz or 630 Hz. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a soundproof cover for preventing leakage of noise generated from a noise source such as an engine.

  In recent automobiles, a soundproof cover is provided to shield noise from the engine. As shown in, for example, Japanese Patent Application Laid-Open No. 10-205352, this soundproof cover includes a hard plate-like sound insulation layer made of resin or steel plate, and a polymer foam such as urethane foam laminated on the engine side surface of the sound insulation layer. And a sound absorbing layer. In this soundproof cover, the sound insulation layer shields the sound from the engine and enhances the appearance design. The sound absorbing layer absorbs sound from the engine, and the sound wave is prevented from reaching the sound insulating layer and vibrating the sound insulating layer. The soundproof cover is fixed to the engine or in the vicinity of the engine via a vibration isolation member such as a rubber mount, thereby preventing the vibration of the engine from being transmitted to the sound insulation layer.

  Urethane foam widely used as a polymer foam has a low closed cell ratio of about several percent, and is mostly open-celled, so that it has excellent sound absorption characteristics but low sound insulation characteristics. Therefore, when the sound absorbing layer is formed from urethane foam, there is a problem that noise is transmitted through the inside of the sound absorbing layer. On the other hand, if the closed cell ratio is increased, the sound absorption characteristics are lowered and the original soundproof effect of the soundproof cover cannot be obtained.

  Therefore, conventionally, for example, as described in Japanese Patent Application Laid-Open No. 08-270889, etc., urethane foam, which is mostly open-celled, is used as a sound-absorbing layer and is attached in a compressed state by pressing it against a noise source. Has been done. For example, as shown in FIG. 8, the soundproof cover includes a sound insulating layer 100 made of a metal plate and a sound absorbing layer 200 made of urethane foam, and the cylinder block 300 has a grommet 101 held by the sound insulating layer 100. The boss portion 301 is fixed with bolts 302. The sound insulating layer 100 has a vertical wall 102 that is bent at a substantially right angle at the periphery, and the vertical wall 102 covers the side peripheral surface of the sound absorbing layer 200. The tightening margin of the bolt 302 is smaller than the thickness of the sound absorbing layer 200, and the sound absorbing layer 200 is held in a compressed state between the sound insulating layer 100 and the cylinder block 300.

  That is, since the sound absorbing layer 200 is deformed in the direction perpendicular to the thickness direction by the vertical wall 102, it is compressed in the thickness direction by the bolt 302, and since the sound insulating layer 100 is hard, the fastening force of the bolt 302 is Since the sound-absorbing layer 200 is uniformly transmitted to the peripheral portion of the sound-absorbing layer 200, the sound-absorbing layer 200 elastically contacts the cylinder block 300 at least at the peripheral portion. As a result, a sealing property is exhibited, and leakage of noise from between the sound absorbing layer 200 and the cylinder block 300 can be prevented. Moreover, since the cell is deformed so as to be crushed by compressing the urethane foam, it is possible to prevent the transmission of sound waves, and to suppress the leakage of noise transmitted through the sound absorbing layer 200. Since the soundproof cover is fixed to the cylinder block 300 via the rubber grommet 101, the vibration of the cylinder block 300 is prevented from being transmitted to the hard sound insulation layer 100, and the sound insulation layer 100 vibrates. The generation of secondary noise due to this is suppressed.

  However, even with the above-mentioned soundproof cover, it is difficult to reliably prevent vibration of the sound insulation layer 100, and secondary noise due to surface resonance is inevitable, and the noise level in the frequency range around 500 Hz or 630 Hz is unavoidable. Further reduction was necessary.

  Therefore, as described in JP-A-2002-273795, if the sound insulation layer is formed of an elastic body such as rubber, the vibration of the sound insulation layer can be suppressed by the vibration control action. In this way, as described in JP-A-2004-198801, the grommet can be integrally formed with the sound insulation layer, and the cost can be reduced by reducing the number of parts.

However, when the sound insulation layer is formed from an elastic body such as rubber, the attachment force is absorbed by the sound insulation layer, so that it is difficult to attach the sound absorption layer to the noise source in a state of being reliably compressed. Further, the sound insulating layer may be deformed following the deformation of the sound absorbing layer, and the compression of the sound absorbing layer is released. That is, there is a problem that the sealing performance is deteriorated, and it is difficult to express the original soundproofing characteristics due to the leakage of noise from between the noise source and the sound absorbing layer.
JP-A-10-205352 JP 08-270889 JP 2002-273795 JP 2004-198801

  The present invention has been made in view of the above-described circumstances, and solves the problem of reliably suppressing secondary vibration of the sound insulation layer while maintaining high sealing performance due to compression of the sound absorption layer to prevent noise leakage. It should be a challenge.

  The soundproof cover of the present invention that solves the above-described problems is characterized by comprising a plate-like sound insulation layer and a soft sound absorption layer disposed on the back surface of the sound insulation layer, at least the sound absorption layer being compressed and closely contacting the noise source A soundproof cover attached to a noise source in a state where an annular seal portion is formed, wherein the sound insulation layer includes at least a soft portion made of a soft elastic body and having a damping effect, and is partly provided on at least one of the sound insulation layer and the sound absorption layer. It is to be attached to the noise source through a rigid compression / compression part that is formed in accordance with the shape of the seal part.

  The sound insulating layer has a hard part capable of maintaining its own shape, and the hard part can also have a structure also serving as a compression / compression part. The compression / compression unit is preferably formed in a lattice shape.

  According to the soundproof cover of the present invention, since it is attached to the noise source through the hard compressing portion corresponding to the shape of the seal portion, the mounting force applied to the compressing portion is reliably transmitted to the sound absorbing layer. Installed securely in a compressed state. Therefore, leakage of noise from between the noise source and the sound absorbing layer can be surely prevented, and sealing performance can be ensured. And since the sound insulation layer is made of a soft elastic body and has a soft part that has a damping effect, the surface resonance of the sound insulation layer is suppressed by the damping action by the soft part, and the noise level in the frequency range around 500 Hz or 630 Hz is reduced. Further reduction can be achieved.

  And if the sound insulation layer has a hard part that can hold its own shape and the hard part also serves as a compression / compression part, the number of parts can be reduced and the thickness of the sound insulation layer can be reduced without making the sound absorption layer thin. Therefore, it is possible to seal without impairing the sound absorption effect.

  In addition, if the compression part is formed in a lattice shape, the mounting force applied to the compression part is uniformly transmitted to the sound absorbing layer, so that the deterioration of the sealing performance due to the release of compression can be suppressed and the durability of the soundproofing effect is improved. To do.

  The soundproof cover of the present invention includes a plate-like sound insulation layer and a sound absorption layer. The sound insulation layer includes at least a soft portion made of a soft elastic body and having a vibration damping action. The soft portion needs to have a vibration damping property that can prevent surface resonance of the sound insulation layer, and can be formed of a soft material such as rubber or thermoplastic elastomer. The hardness of the soft part is preferably in the range of HS40-80. When the hardness is higher than this range, the vibration damping property is lowered and surface resonance occurs. When the hardness is lower than this range, the shape retention property is lowered and the compression of the sound absorbing layer may be released.

  Moreover, it is also preferable that the sound insulation layer has a hard part capable of maintaining its own shape, and the hard part also serves as the compression / compression part. This hard part should just have the hardness which can hold | maintain its own shape, and can be formed from hard resin, a metal, etc. The area ratio between the hard part and the soft part is not particularly limited, but the vibration damping improves as the soft part increases, so that the generation of noise due to the secondary vibration of the sound insulation layer can be further prevented. However, on the other hand, there is a problem that the characteristic of maintaining the shape of the sound absorbing layer is deteriorated. In general, therefore, it is desirable that the area ratio of the soft part to the entire sound insulation layer be in the range of 20% to 80%. If the area of the soft part is less than 20%, secondary noise is likely to be generated due to surface resonance, and if it exceeds 80%, there may be a problem in the shape retention of the sound absorbing layer.

  Further, the part forming the soft part and its shape are also important. That is, it is desirable that at least the entire periphery of the sound insulating layer is a frame-like hard part, or the hard part is formed in a lattice shape. Thereby, shape retainability can be maintained high, ensuring the area of a soft part.

  The sound-absorbing layer can be formed from a foam made of a polymer such as polyurethane, polyolefin, and foamed rubber. Among them, urethane foam, in which open cells occupy most, is particularly preferable.

  The sound absorbing layer and the sound insulating layer may be bonded to each other or may be simply laminated without bonding. In the case of a sound absorbing layer made of urethane foam, it is preferable to integrate the sound absorbing layer by foam molding in a state where the sound insulating layer is disposed in the foam mold.

  The greatest feature of the soundproof cover according to the present invention is that at least one of the sound insulation layer and the sound absorption layer has a hard compression portion corresponding to the shape of the seal portion, and is attached to a noise source via the compression portion. There is. For example, if the compression / compression unit is formed by embedding or covering a metal plate or a resin plate in a part of the sound absorption layer, the sound absorption layer between the compression unit and the noise source is attached to the noise source via the compression / compression unit. Can be compressed, and sealing performance can be secured. However, in this case, another part is required for forming the compression / compression section, and there is a problem that the number of parts increases. Further, since the sound absorbing layer between the compression unit and the sound insulating layer is not compressed, the sound absorbing characteristics may be deteriorated depending on the shape.

  Therefore, it is desirable that the sound insulation layer has a hard part capable of maintaining its own shape, and that the hard part also serves as a compression / compression part. As a result, the number of parts can be reduced, and the thickness can be secured without making the sound absorbing layer thinner, so that the sound absorbing effect can be sealed without impairing the sound absorbing effect. In addition, it is easy to form the compression / compression section in a lattice shape, and the shape retaining property of the sound absorbing layer can be maintained high while ensuring the area of the soft section.

  The soundproof cover of the present invention is attached to the noise source in a state where the peripheral portion of the sound absorbing layer is compressed to form an annular seal portion that is in close contact with the noise source. For example, the sound insulation layer has a hard part that can hold its own shape, and when the hard part also serves as a compression / compression part, if a frame-like part that covers the periphery of the sound absorbing layer is formed on the hard part, the attachment part Since the applied attachment force is transmitted to the peripheral portion via the hard portion and the peripheral portion of the sound absorbing layer can be compressed in an annular shape, the frame-shaped portion also serves as the compressing portion. Moreover, when forming a compression part in a sound absorption layer, it is desirable for a compression part to be made into the shape corresponding to the shape of a seal part. In this case, the compression / compression section may be formed in an endless annular shape, or if the sound absorption layer is deformed when the sound absorption layer is compressed to form an annular seal portion, it is not endless but partially interrupted. It may be. In any case, the position of the attachment portion of the compression / compression portion using a bolt or the like is not particularly restricted.

  In order to fix the soundproof cover of the present invention to a noise source, it may be fixed via a grommet or a rubber mount, but the surface resonance of the sound insulation layer is suppressed by the vibration control action of the soft part of the sound insulation layer. Further, it is possible to eliminate the need for a damping member such as a grommet or a rubber mount, and to directly fix the noise source directly through the compression / compression unit.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
1 and 2 show a soundproof cover of this embodiment. This soundproof cover is composed of a resin-made plate-like sound insulation layer 1 and a urethane foam sound absorption layer 2 joined to the surface of the sound insulation layer 1, and the sound absorption layer 2 is a cylinder block 30 as shown in FIG. It is attached in a compressed state opposite to. A boss 31 projects integrally with the cylinder block 30, and the sound insulation layer 2 is compressed to the cylinder block 30 by fixing the sound insulation layer 1 to the boss 31 with a bolt 33 through a rubber grommet 32. Is retained.

  The sound insulation layer 1 is formed in a substantially box shape having a vertical wall 15 bent at a substantially right angle at the peripheral portion, a hard portion 10 made of hard resin formed at the peripheral portion, and a thermoplastic urethane formed at the inner peripheral portion. And made of soft part 11. The hard part 10 and the soft part 11 are integrally joined. In addition, the hard part 10 holds grommets 32 at four corners.

  The sound absorbing layer 2 is formed by inserting the sound insulating layer 1 in a foaming mold and performing foam molding, and is integrally joined to the back side of the sound insulating layer 1.

  In the soundproof cover of the present embodiment, the hard part 10 holding the grommet 32 functions as a compression / compression part, and the fastening force by the bolt 33 is the entire circumference of the sound absorbing layer 2 via the frame-like hard part 10 at the peripheral part. Acts as a compressive force. Therefore, since the sound absorbing layer 2 is compressed in the entire circumference and is held in a state where an annular seal portion elastically contacting the cylinder block 30 is formed at least at the peripheral portion, noise from between the cylinder block 30 and the sound absorbing layer 2 is retained. Leakage can be reliably prevented and sealing performance can be ensured. And since the sound insulation layer 1 has the soft part 11 made of a soft elastic body in a wide area, the vibration of the sound insulation layer 1 is suppressed by the vibration control action of the soft part 11, and the noise level in the frequency range near 500 Hz or 630 Hz. Can be reduced.

(Example 2)
FIG. 3 shows the sound insulation layer 1 of the soundproof cover of this embodiment. This soundproof cover is the same as that of Example 1 except that the structure of the sound insulation layer 1 is different. The sound insulation layer 1 is composed of a hard resin hard portion 10 having a frame-like periphery and a lattice-like inside, and a thermoplastic urethane soft portion 11 formed between the hard portion 10 lattices. Grommets 32 are held at the intersections of the lattices of the hard part 10.

  The soundproof cover of this embodiment is attached to the cylinder block 30 in a state where the sound absorbing layer 2 is compressed as in the first embodiment. At this time, the hard portion 10 holding the grommet 32 functions as a compressing portion, and the fastening force by the bolt 33 acts as a compressive force on the entire sound absorbing layer 2 via the hard portion 10. Therefore, since the sound absorbing layer 2 is compressed at least at the peripheral edge and is held in a compressed state on almost the entire surface, leakage of noise from between the cylinder block 30 and the sound absorbing layer 2 can be surely prevented and the seal Sex can be secured. And since the sound insulation layer 1 has the soft part 11 in a wide area, the vibration of the sound insulation layer 1 is suppressed by the vibration control action by the soft part 11, and the noise level in the frequency range near 500 Hz or 630 Hz can be reduced. it can.

(Example 3)
The soundproof cover of this embodiment shown in FIGS. 4 and 5 is the same as that of Embodiment 1 except that the structure of the sound insulation layer 1 is different and the grommet 32 is not used. The sound insulation layer 1 includes a hard resin hard portion 10 formed in a lattice shape at the periphery and inside, and a thermoplastic urethane soft portion 11 formed between the hard portion 10 lattices. Mounting holes 12 are formed at the intersections of the grids.

  In the soundproof cover of this embodiment, the hard portion 10 having the attachment hole 12 functions as a compression / compression portion, and the hard portion 10 is fixed to the boss 31 with a bolt 33 through the attachment hole 12 as shown in FIG. Thus, the sound absorbing layer 2 is held in a compressed state in the cylinder block 30. Thus, even if the grommet 32 is not required, since the area of the hard part 10 is small and the soft part 11 is present in a wide area, the surface resonance of the sound insulation layer 1 is suppressed by the damping action of the soft part 10, and 500 Hz or The noise level in the frequency range near 630 Hz can be reduced.

Example 4
The soundproof cover of this embodiment shown in FIGS. 6 and 7 is made of a soft thermoplastic elastomer, a plate-like sound insulating layer 1, a sound absorbing layer 2 made of urethane foam joined to the surface of the sound insulating layer 1, and a sound absorbing layer. The compression member 4 is made of metal and embedded in 2, and the compression member 4 is fixed to a boss 31 protruding from the cylinder block 30 with a bolt 33. The thickness from the compression member 4 to the lower surface of the sound absorbing layer 2 is thicker than the tightening of the bolt 33, and the sound absorbing layer 2 is attached to the cylinder block 30 in a compressed state.

  The compression member 4 is formed in a frame shape corresponding to the shape of the peripheral edge of the sound absorbing layer 2, and is fixed to the boss 31 with bolts 33 through attachment holes 40 formed at four locations. Therefore, the fastening force by the bolt 33 is transmitted to the peripheral portion of the sound absorbing layer 2 via the compression member 4, and at least the peripheral portion of the sound absorbing layer 2 is in elastic contact with the cylinder block 30 to form an annular seal portion. ing.

  Further, the sound insulation layer 1 has a bolt hole 13 passing through the position of the boss 31. Therefore, the sound insulation layer 1 is held only by the bonding force with the sound absorption layer 2. However, since the deformation of the sound absorbing layer 2 is restricted by the peripheral wall 15, an annular seal portion is reliably formed in the sound absorbing layer 2. And since the sound insulation layer 1 is a soft part as a whole, surface resonance is suppressed, and the noise level in the frequency range near 500 Hz or 630 Hz can be reduced.

  The soundproof cover of the present invention can be used as a soundproof cover such as an intake manifold and an intake duct, an under cover, etc. in addition to a cylinder block cover.

It is a top view of the sound insulation layer of the soundproof cover of one Example of this invention. It is sectional drawing shown in the state which assembled | attached the soundproof cover of one Example of this invention to the noise source. It is a top view of the sound insulation layer of the soundproof cover of the 2nd example of the present invention. It is a top view of the sound insulation layer of the soundproof cover of the 3rd example of the present invention. It is sectional drawing shown in the state which assembled | attached the soundproof cover of the 3rd Example of this invention to the noise source. It is sectional drawing of the sound absorption layer of the soundproof cover of the 4th Example of this invention. It is sectional drawing shown in the state which assembled | attached the soundproof cover of the 4th Example of this invention to the noise source. It is sectional drawing shown in the state which assembled | attached the conventional soundproof cover to the noise source.

Explanation of symbols

1: Sound insulation layer 2: Sound absorption layer 10: Hard part
11: Soft part 32: Grommet

Claims (3)

The sound source comprises a plate-like sound insulation layer and a soft sound absorption layer disposed on the back surface of the sound insulation layer, and at least the sound absorption layer is compressed to form an annular seal portion in close contact with the noise source. A soundproof cover to be attached,
The sound insulation layer comprises at least a soft part made of a soft elastic body and having a vibration damping action,
A soundproof cover, which is attached to the noise source through a hard compression / compression part that is partially formed on at least one of the sound insulation layer and the sound absorption layer and corresponds to the shape of the seal part.   The soundproof cover according to claim 1, wherein the sound insulating layer has a hard portion capable of maintaining its own shape, and the hard portion also serves as the compressing portion.   The soundproof cover according to claim 1 or 2, wherein the compressing section is formed in a lattice shape.

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