JP4257960B2 - Silencer duct - Google Patents

Description

  The present invention relates to a noise reduction duct for noise reduction, which is attached to an intake port or an exhaust port of an electronic device or OA device having a blower for cooling a substrate inside the device.

  Conventionally, in various electronic devices and OA devices, cooling air is blown by a blower in order to air-cool the substrate inside the device. However, noise from the blower is large, which is a problem. This noise is generated by the sound generated by the blower propagating in the intake air passage or the exhaust air passage, and a part of the noise is emitted from the intake or exhaust port. Further, a part of the noise emitted from the intake port or the exhaust port is reflected in the air passage. When a member that absorbs acoustic energy, such as a sound absorbing material, is arranged in the air passage, the sound energy is absorbed by the member, such as the sound absorbing material, when the sound generated by the blower propagates in the air passage. Thus, the acoustic energy emitted from the intake port or the exhaust port is reduced. Moreover, the acoustic energy reflected in the air path from the intake port or the exhaust port is also absorbed by the member such as the sound absorbing material. When there is no member that absorbs acoustic energy such as a sound absorbing material, the acoustic energy is not attenuated, and in some cases, resonance amplification may occur in the air path. Therefore, in general, a silencer duct using a sound absorbing material is attached to an inlet or an outlet of cooling air in various electronic devices and OA devices.

  5 and 6 show the flow of cooling air and the structure of the silencer duct in a conventional electronic device. As shown in FIG. 5, the conventional electronic device 110 includes an exhaust-side silencer duct 101 attached to the exhaust port 107 and an intake-side silencer duct 102 attached to the intake port 117. In general, in the case of electronic equipment and OA equipment, there is no room in the equipment, and as shown in FIGS. 5 and 6, some of the walls constituting the exhaust-side silencer duct 101 and the intake-side silencer duct 102 are The sound absorbing walls 105 and 115 are composed of the sound absorbing ducts 101 and 102, and the other walls of the silencer ducts 101 and 102 are composed of the rigid walls 103, 104, 113, and 114, the main body casing top plate 121, and the main body casing bottom plate 109. ing. In addition, as described above, in the case of electronic equipment and OA equipment, since there is no room in the equipment, thick sound-absorbing walls 105 and 115 that can be reduced to a low-frequency band are used. It is not possible. In other words, in conventional electronic equipment and OA equipment, if the noise generated by the blower is sufficiently reduced to the low frequency band, the product must be enlarged, and conversely, the product should be made compact. Then, there was a problem that noise countermeasures had to be sacrificed.

  The present invention has been made to solve the above-described problems, and has an object to provide a silencer duct that is compact and can reduce noise in a wide band including noise in a low frequency band. To do.

The invention of claim 1 in order to attain the above objects, the muffler duct is attached to the intake port or exhaust port of the electronic equipment and OA equipment with blower for substrate cooling internal equipment, Ya the electronic apparatus in the muffler duct A part or all of the partition wall with the inside of the OA device is constituted by an acoustic transmission wall that transmits sound but does not transmit air flow, and the acoustic transmission wall is a cloth or a cloth covered with a film. It is affixed to the frame .

According to a second aspect of the present invention, there is provided a silencer duct attached to an inlet or an exhaust port of an electronic device or OA device having a blower for cooling a substrate inside the device, wherein the silencer duct is partitioned from the inside of the electronic device or OA device. A part or all of the wall is constituted by a sound transmission wall that transmits sound but does not transmit air flow , and the sound transmission wall has a film attached to a frame .

According to a third aspect of the present invention, there is provided a silencer duct attached to an inlet or an exhaust port of an electronic device or OA device having a blower for cooling a substrate inside the device, wherein the silencer duct is partitioned from the inside of the electronic device or OA device. Part or all of the wall is composed of an acoustic transmission wall that transmits sound but not air flow. The acoustic transmission wall is a cloth, a cloth covered with a film, or a film attached to a perforated plate. It is a thing.

According to a fourth aspect of the present invention, there is provided a silencer duct attached to an inlet or an exhaust port of an electronic device or OA device having a blower for cooling a substrate inside the device, wherein the silencer duct is partitioned from the inside of the electronic device or OA device. Part or all of the wall is composed of an acoustically permeable wall that transmits sound but not air flow, and the acoustically permeable wall includes a cloth, a cloth covered with a film, or a film sandwiched between perforated plates. Is.

According to the first to fourth aspects of the present invention, part or all of the partition wall with the inside of the electronic device or the OA device is constituted by an acoustic transmission wall that transmits sound but does not transmit air flow. Here, since the sound transmission wall has an action of transmitting the acoustic energy in the air passage of the silencer duct to the inside of the device main body and attenuating it inside the clogged substrate or the like, as described above, the electronic device or OA By configuring part or all of the partition wall with the inside of the equipment as a sound transmission wall, noise generated by the blower escapes to the inside of the equipment through the sound transmission wall and does not easily reach the intake or exhaust port. . That is, noise emitted from the intake port or the exhaust port can be reduced. Further, the sound reflected from the intake port or the exhaust port into the silencer duct is transmitted through the sound transmitting wall into the device, and is not confined or resonated in the air passage. Therefore, the noise emitted from the intake port or the exhaust port can be significantly reduced by configuring part or all of the partition wall from the inside of the device with the sound transmission wall. In addition, a normal sound absorbing wall needs a certain thickness to absorb sound up to low frequency sound, but the sound transmitting wall only transmits sound waves, so even a thin sound transmitting wall has a low frequency band. It is possible to transmit and attenuate a wide band sound including the sound of the sound inside the device. Therefore, it is possible to reduce the noise in a wide band including the noise in the low frequency band while making the entire apparatus using the silencer duct a compact configuration.

  The best mode for carrying out the present invention will be described with reference to the drawings. The embodiments described below do not cover the present invention, and the present invention is not limited to the following modes. The silencer duct according to the present embodiment is an exhaust-side silencer duct and an intake-side silencer duct of an electronic device.

  FIG. 1 shows a flow of cooling air in an electronic device 10 including an exhaust-side silencer duct 1 and an intake-side silencer duct 2 that are silencer ducts according to the present embodiment. FIG. 2 shows the configuration of the exhaust-side silencer duct 1 described above. As shown in FIG. 1, the electronic device 10 includes an exhaust-side silencer duct 1 attached to the exhaust port 7 and an intake-side silencer duct 2 attached to the intake port 17. The exhaust-side silencer duct 1 is configured by sound transmission walls 3 and 4 that transmit sound but do not transmit air flow through a part of the partition wall with the inside of the device. Therefore, a part of the air path in the exhaust side silencing duct 1 is constituted by the sound transmission walls 3 and 4. The exhaust-side silencer duct 1 exhausts the sound-absorbing wall 5 made of a sound-absorbing material capable of absorbing acoustic energy in addition to the sound transmitting walls 3 and 4 and the hot air after cooling the electronic board 20 inside the device. It has the exhaust fan 6 for doing. The exhaust blower 6 is an axial fan type blower. As shown in FIG. 2, the air path in the muffler duct 1 includes sound transmitting walls 3 and 4, a sound absorbing wall 5, an exhaust blower 6, a main body casing bottom plate 9, and a main body casing top plate 21. ing. Also, the intake-side silencer duct 2 shown in FIG. 1 has the same configuration as the exhaust-side silencer duct 1 described above.

  In the exhaust-side silencing duct 1 and the intake-side silencing duct 2 described above, the conventional exhaust-side silencing duct 101 and the intake-side silencing duct 102 (see FIGS. 5 and 6) are rigid because a sound-absorbing wall cannot be installed due to space. A part of the partition walls with the walls 103, 104, 113, and 114, which are separated from the inside of the apparatus, are designated as sound transmission walls 3, 4, 13, and 14. Here, the acoustic transmission walls 3, 4, 13, and 14 transmit the acoustic energy in the air path of the exhaust-side silencer duct 1 or the intake-side silencer duct 2 to the inside of the device, and inside the electronic board 20 or the like. Since there is a function of attenuating, the noise generated in the exhaust blower 6 or the intake blower 16 by configuring a part of the partition wall with the inside of the equipment as the sound transmission walls 3, 4, 13, 14 as described above. Escapes to the inside of the device through the sound transmission walls 3, 4, 13, and 14 and does not easily reach the exhaust port 7 or the intake port 17. That is, noise emitted from the intake port 17 or the exhaust port 7 can be reduced. Further, the sound reflected from the intake port 17 or the exhaust port 7 into the intake-side muffler duct 2 or the exhaust-side muffler duct 1 is also transmitted through the sound transmitting walls 3, 4, 13, and 14 into the apparatus, and the air path There is no longer any stagnation or resonance inside. Therefore, the noise emitted from the exhaust port 7 or the intake port 17 can be greatly reduced by configuring a part of the partition wall with the inside of the apparatus by the sound transmission walls 3, 4, 13, and 14.

  In addition, a normal sound absorbing wall needs a certain thickness to absorb sound up to low frequency sound. However, the above sound transmitting walls 3, 4, 13, and 14 transmit only sound waves, so they can be thin. A wide band sound including a low frequency band sound can be transmitted through the apparatus and attenuated. Therefore, it is possible to reduce the noise in a wide band including the noise in the low frequency band while making the entire apparatus using the exhaust side silencing duct 1 and the intake side silencing duct 2 compact.

  Furthermore, since a part of the air path in the exhaust side silencing duct 1 and the intake side silencing duct 2 is constituted by the sound absorbing walls 5 and 15, noise generated in the exhaust air blower 6 or the intake air blower 16 is reduced. When propagating through the air path in 1 or the intake-side silencer duct 2, acoustic energy can be absorbed by the sound absorbing walls 5, 15, so that noise emitted from the intake port 17 or the exhaust port 7 can be further reduced. Can be reduced. Further, the noise reflected from the intake port 17 or the exhaust port 7 into the intake side silencing duct 2 or the exhaust side silencing duct 1 can be further reduced by using the sound absorbing walls 5 and 15.

  FIGS. 3A to 3E show examples of the configuration of the acoustic transmission walls 3, 4, 13, and 14. In these drawings, 3 represents the sound transmitting walls 3, 4, 13, and 14 collectively. The sound transmission wall 3 shown in (a) is obtained by attaching a clogged cloth 41 to a frame 42. The sound transmission wall 3 shown in (b) is obtained by attaching a cloth 41 covered with a thin film 43 to a frame 42. The sound transmission wall 3 shown in (c) is obtained by attaching a thin film 43 to a frame 42. The sound transmission wall 3 shown in (d) is obtained by attaching a cloth 41 covered with a thin film 43 to a perforated plate 44. The sound transmission wall 3 shown in (e) is obtained by sandwiching a cloth 41 clogged with a porous plate 44.

  The configurations shown in FIGS. 3A to 3E are merely examples of the configuration of the sound transmission wall 3, and various modifications are possible. For example, in the sound transmission wall 3 shown in (d), an example in which the cloth 41 covered with the thin film 43 is attached to the porous plate 44 is shown. It may be attached, or only the thin film 43 may be attached to the porous plate 44. Moreover, in the sound transmission wall 3 shown in (e), an example in which the cloth 41 clogged with the eyes is sandwiched between the porous plates 44 is shown, but a thin film 43 may be sandwiched between the porous plates 44, or a thin film The cloth 41 covered with 43 may be sandwiched between the perforated plates 44. That is, the sound transmission wall 3 may take any configuration as long as it satisfies the condition that sound is transmitted but air flow is not transmitted.

  Next, with reference to FIG. 4, the effect of reducing the noise from the exhaust port 7 by using the acoustic transmission walls 3 and 4 will be described. The broken line 51 in the figure is the case where the air passage in the duct is configured by using the sound transmitting walls 3 and 4 and the sound absorbing wall 5 as in the exhaust side silencing duct 1 of the present embodiment shown in FIG. The measured value of the sound pressure level of the noise radiated from the exhaust port 7 is shown for each frequency band. Further, the broken line 52 is an exhaust port 107 when the air passage in the duct is configured by using the rigid walls 103 and 104 and the sound absorbing wall 105 as in the conventional exhaust side silencing duct 101 shown in FIG. The actual measurement value of the sound pressure level of the noise radiated from is shown for each frequency band. Furthermore, the broken line 53 shows the measured value of the sound pressure level of the noise radiated from the exhaust port for each frequency band when the air passage in the duct is configured using only a rigid wall. Even when a part of the air passage in the duct is configured by the sound absorbing wall 105 as indicated by the broken line 52, the air passage in the duct indicated by the broken line 53 is configured by using only a rigid wall. In comparison, noise in the low frequency band cannot be sufficiently reduced. This is because, in the case of electronic equipment, there is no room in the equipment, and therefore, it is not possible to use a thick sound absorbing wall 105 that can be reduced to a low frequency band sound. On the other hand, as shown by the broken line 51, when the air path in the duct is configured using the sound transmitting walls 3, 4 and the sound absorbing wall 5, the air path in the duct indicated by the broken line 53 is used. Compared with the case where only the rigid wall is used and the case where the air path in the duct indicated by the broken line 52 is constituted using the rigid walls 103 and 104 and the sound absorbing wall 105, the noise is also reduced in the low frequency band. Can be sufficiently reduced.

  Note that OA in the figure represents an overall level. The overall level is the sound pressure level of the sound of all frequency components. A in the figure represents the A characteristic correction noise level. The A characteristic correction noise level is a sound pressure level as a result of frequency correction according to the characteristics of human hearing. In the figure, the unit of the A characteristic correction noise level is dBA, but the unit of the sound pressure level for each frequency band is dB.

  The sound transmitting walls 3 and 4 in the exhaust-side silencer duct 1 used for collecting the data indicated by the broken line 51 have a cloth 41 clogged as shown in FIG. Of the type. The cloth 41 constituting the sound transmission walls 3 and 4 used for collecting the data is a felt-like cloth having a thickness of about 1 mm.

Further, when the desired degree of clogging of the cloth 41 constituting the acoustic transmission walls 3 and 4 is expressed numerically using the flow resistance Rf, Rf = 0.25 × ρc to 1 × ρc (ρ: air density) (Kg / m ³ ), c: speed of sound (m / s)). Here, the flow resistance Rf = ΔP / U (U: flow velocity of the air flowing perpendicularly to the cloth (close flow velocity) (m / s), ΔP: pressure difference (Pa) upstream and downstream of the cloth at that time) Yes, U is assumed to have a slow flow rate of several cm / s. The flow resistance Rf indicates the difficulty of air flow through the cloth. Further, as shown in FIGS. 3B and 3D, when the cloth 41 is covered with the film 43, the flow is almost acoustically not bad (without making sound difficult to transmit). The resistance Rf can be made almost infinite (the air flow can be prevented from passing through).

  In the above description, the configuration of the exhaust side silencing duct 1 and its noise reduction effect have been mainly described. However, the configuration of the intake side silencing duct 2 and its noise reduction effect are also the same as those of the exhaust side silencing duct 1. .

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above-described embodiment, an example in which an axial fan type blower is used as the exhaust blower 6 and the intake blower 16 is shown. However, a centrifugal fan type blower may be used as the exhaust blower and the intake blower. Moreover, although the example in the case where the air path in a duct was comprised using the sound transmission walls 3 and 4 and the sound absorption wall 5 was shown in the said embodiment, a sound absorption wall is not necessarily required. Therefore, the air path in the duct may be configured using the sound transmission wall and the rigid wall, or may be configured using only the sound transmission wall. Furthermore, in the above-described embodiment, an example in which the silencer duct of the present invention is attached to an intake port or an exhaust port of an electronic device having a fan for cooling the substrate is shown. You may attach to the inlet port or exhaust port of OA equipment which has an air blower.

1 is a cross-sectional view of an electronic apparatus including an exhaust-side silencer duct and an intake-side silencer duct according to an embodiment of the present invention. The perspective view which a part of exhaust port periphery part of the said electronic device fractured | ruptured. (A), (b), (c), (d), and (e), respectively, when the cloth is affixed to the frame, when the cloth covered with the film is affixed to the frame, and when the film is affixed to the frame FIG. 6 is a configuration diagram of a sound transmission wall when a cloth covered with a film is attached to a perforated plate and when the cloth is sandwiched between perforated plates. Noise when the air passage in the exhaust-side silencer duct is configured with sound transmission walls and sound absorbing walls, with rigid walls and sound absorbing walls, or with only rigid walls The graph which showed the actual value of the sound pressure level of according to frequency band. Sectional drawing of the electronic device containing the conventional exhaust side silencing duct and the intake side silencing duct. FIG. 6 is a partially broken perspective view of a peripheral portion of an exhaust port of a conventional electronic device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust side muffler duct 2 Intake side muffler duct 3 Sound transmission wall 4 Sound transmission wall 5 Sound absorption wall 6 Exhaust fan 7 Exhaust port 10 Electronic device 13 Sound transmission wall 14 Sound transmission wall 15 Sound absorption wall 16 Exhaust fan 17 Inlet port 41 Cloth 42 Frame 43 Film 44 Perforated plate

Claims (4)

In the silencer duct attached to the intake or exhaust port of an electronic device or OA device having a blower for cooling the substrate inside the device,
A part or all of the partition wall between the electronic device and the OA device in the muffler duct is constituted by a sound transmitting wall that transmits sound but does not transmit air flow ,
The muffler duct , wherein the sound transmission wall is a cloth or a cloth covered with a film attached to a frame . In the silencer duct attached to the intake or exhaust port of an electronic device or OA device having a blower for cooling the substrate inside the device,
  A part or all of the partition wall between the electronic device and the OA device in the muffler duct is constituted by a sound transmitting wall that transmits sound but does not transmit air flow,
  The muffler duct, wherein the sound transmission wall is a film attached to a frame. In the silencer duct attached to the intake or exhaust port of an electronic device or OA device having a blower for cooling the substrate inside the device,
  A part or all of the partition wall between the electronic device and the OA device in the muffler duct is constituted by a sound transmitting wall that transmits sound but does not transmit air flow,
  The muffler duct, wherein the sound transmission wall is a cloth, a cloth covered with a film, or a film attached to a perforated plate. In the silencer duct attached to the intake or exhaust port of an electronic device or OA device having a blower for cooling the substrate inside the device,
  A part or all of the partition wall between the electronic device and the OA device in the muffler duct is constituted by a sound transmitting wall that transmits sound but does not transmit air flow,
  The muffler duct, wherein the sound transmission wall is a cloth, a cloth covered with a film, or a film sandwiched between perforated plates.

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