JP4624871B2 - Silencer for ventilation opening - Google Patents

Description

  The present invention relates to a ventilation silencer that prevents outdoor road traffic noise, railway noise, aircraft noise, factory noise, and the like from being propagated indoors through a ventilation opening.

  Conventionally, ventilation vents for taking in outside air have been provided with ventilation hoods for the purpose of covering the entrance to prevent rain and dust from entering, but they are not equipped with soundproofing effects. Propagation indoors through the vents was a problem. This problem has become more and more apparent as the sound environment in the room has been improved by high performance soundproof sashes and soundproof doors.

  In order to solve the above problem, several ventilation silencers have been proposed in which a soundproofing effect is added to the ventilation hood. For example, in Patent Document 1 below, as shown in FIG. 14, a silencer disposed in a ventilation opening of a building, which has an outdoor opening 52 defined by walls and communicated with each other via a passage 51. A plurality of rooms including a first room 53 that communicates with the atmosphere through and a last room 55 that communicates with the room via a room-side opening 54. The room-side opening 54 extends in the axial direction of the passage that leads to the last room 55. The indoor side opening 54 and a wall positioned in front of the traveling direction of the sound wave traveling from the passage 51 toward the indoor side opening 54. Disclosed is a vent silencer that is displaceable without changing the volume of the last room 55 to change the distance between them. Such a silencer for a vent is intended to mute the noise that has entered the passage of the first room through the opening and is rapidly expanded in the last room.

Further, in Patent Document 2 below, as shown in FIG. 15, a hollow housing 58 having a gas inlet 56 and an outlet 57 and partition means 59 provided inside the housing 58, Partitioning means 59 that separates the flow of gas flowing in from the inlet 56 into two flows directed in opposite directions, and makes the separated two flows opposite to each other. Thus, a silencer that flows out from the outlet 57 is disclosed.
Japanese Patent Publication No. 2-60944 JP-A-3-217615

  However, in the invention described in Patent Document 1, there is a drawback that the noise reduction effect is reduced for the noise of a specific component due to the resonance in the first room 53. If the last room 55 is not enlarged, a sufficient effect cannot be exerted, so that it is not suitable as a silencer in a limited space such as a ventilation opening. Further, the invention described in Patent Document 2 is an interference silencer, and the interference silencer is effective for noise with a particularly high level of a specific frequency component in a relatively low sound portion. There is a drawback that the effect cannot be obtained in silencing frequency components other than the components.

  On the other hand, in the inventions described in Patent Documents 1 and 2, no consideration is given to the maintenance inside the silencer, and a structure that can easily perform the internal maintenance is desired.

  Accordingly, a main problem of the present invention is to provide a ventilator silencer capable of silencing a wide range of frequency components of outdoor noise while having a compact structure and capable of simple maintenance inside the silencer. It is in.

In order to solve the above-mentioned problem, the present invention according to claim 1 is a ventilator silencer which is a vertically long shape of a substantially rectangular parallelepiped and is attached to a wall surface in a vertical direction,
The ventilation silencer has a rear outer plate attached to the rear side of a U-shaped casing composed of a thin flat side outer plate and a front outer plate, and the upper and lower portions of the casing are made of cast aluminum. And an external air passage is formed in a space surrounded by the front plate, the side outer plate, the rear outer plate, the upper cover, and the lower cover, and is externally provided at one end of the lower cover. An open air inlet is formed,
The outside air passage is formed adjacent to the first passage through a first partition plate so that the outside air flowing in from the intake port goes straight, and is folded in a U-turn shape from the end of the first passage . And a second passage through which the outside air folded back in a U-turn shape goes straight, and is formed adjacent to the second passage through a second partition plate so as to be folded back in a U-turn shape from the end of the second passage . And an outside air passage composed of a third passage through which the outside air folded back in a U-turn shape goes straight, and a chamber space formed at the end of the third passage and having a ventilation port communicating with the room, Each passage of the outside air passage is arranged along the vertical direction, and the chamber space is provided in an upper portion of the outside air passage,
In the outside air passage, a sound absorbing material is stretched on two opposing surfaces of the inner surface of the front plate and the inner surface of the rear outer plate, and the second passage side of the second partition plate and the second surface plate of the side outer plate. A sound absorbing material is stretched on the three passage sides, and no sound absorbing material is stretched on the first passage side of the first partition plate and the first passage side of the side surface outer plate, and the first passage end There is provided a silencer for a ventilator, characterized in that a sound absorbing material is stretched on each of the outside air collision surface and the outside air collision surface at the end of the second passage, and a sound absorbing material is stretched over the entire chamber space. .

  According to the first aspect of the present invention, when passing through each outside air passage and chamber space, the effect of sound absorption by the lined sound absorbing material, the effect of sound interference due to collision with the wall surface, By having a sound absorbing function that has both the effect of increasing the sound absorbing area of the sound absorbing material and the distance attenuation by increasing the length of the road, it is possible to mute noise of a wide range of frequency components.

  As the present invention according to claim 2, the passage length of the first passage is based on the tube length l obtained by the primary acoustic mode formula of one end open / closed end of the following formula (1) with an acoustic frequency of 500 Hz as a basic length. The silencer for a ventilation opening according to claim 1, which is set.

  The invention described in claim 2 provides a structure for effectively silencing the noise in the 500 Hz band, which is the most difficult to mute, in this type of silencer for a ventilation opening. When the first passage and the second passage are compared with one end open and other end closed pipes, the sound pressure is maximized at the closed end in the primary acoustic mode with one end open and the other end closed. By disposing, noise in the 500 Hz band can be effectively silenced, and as a result, it is possible to have a silencing effect in a wide band of frequency components. The tube length l calculated by the above equation (1) is 17.0 cm. Accordingly, the passage length of the first passage is set to about 17 cm.

  According to a third aspect of the present invention, the ventilator silencer includes an outer casing and an inner casing, the outside air passage and the chamber space are formed in the inner casing, and the inner casing is formed in the outer casing. A silencer for a ventilator according to any one of claims 1 and 2, which is detachable from the vent, is provided.

  In the third aspect of the present invention, the inner casing in which the outside air passage and the chamber space are formed is detachable from the outer casing, so that dirt due to intrusion of fine dust into the silencer for the ventilation opening and moisture caused by moisture can be prevented. With respect to the deterioration of the sound absorbing performance due to the generation and the secular change of the sound absorbing material, the maintenance can be easily performed by replacing the inner casing.

  The present invention according to claim 4 is characterized in that an air layer is formed at least at the front side boundary and the side side boundary between the outer casing and the inner casing, respectively. An apparatus is provided.

  According to the fourth aspect of the present invention, the noise transmitted through the casing and propagating into the silencer can be reduced, and the silencer performance of the ventilator silencer can be improved.

  According to a fifth aspect of the present invention, there is provided the silencer for a ventilator according to any one of the first to fourth aspects, wherein the first passage, the second passage, and the third passage are set to have a substantially constant passage cross-sectional area. Provided.

  In the fifth aspect of the present invention, since the first passage, the second passage, and the third passage are set to substantially the same passage cross-sectional area, a required air flow rate can be ensured.

  As described above in detail, according to the present invention, while having a compact structure, it is possible to mute a wide range of frequency components of outdoor noise, and simple maintenance inside the muffler can be performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First embodiment]
1 is a rear view of a ventilating silencer 1 according to the present invention, FIG. 2 is a side view thereof, FIG. 3 is a bottom view thereof, FIG. 4 is a sectional view taken along line IV-IV in FIG. -V sectional view and FIG. 6 is a VI-VI sectional view of FIG.

  As shown in FIG. 6, the ventilator silencer 1 (hereinafter simply referred to as a silencer) is a rear surface of a casing 4 having a U-shaped cross section composed of a thin flat side plate 2 and a front plate 3. On the side, a rear outer plate 5 having a circular ventilation port 8 formed at the center upper portion is screwed, and an aluminum front plate 12 is located in the front side of the side outer plates 2 and 2. It is provided so that it may latch on the protrusion 2a ... extended from the inner surface of the side surface outer plate 2,2.

  On the other hand, an upper lid 6 and a lower lid 7 are screwed to the upper and lower portions of the casing 4, respectively, to form a substantially rectangular parallelepiped box having six sides surrounded by the front plate 12, the side outer plates 2, 2, An outside air passage 30 is formed in a space surrounded by the back outer plate 5, the upper lid 6, and the lower lid 7, and sound absorbing materials 41 to 47 are stretched to add a silencing function.

  A ventilation cylinder 9 is attached to the ventilation port 8 portion of the back outer plate 5. The ventilation cylinder 9 includes a flange flange 9a on one end side along the outer periphery, and the flange flange 9a is attached to the back outer plate 5 by screws.

  An air inlet 10 that is open to the outside is formed at one end of the lower lid 7, and a mesh-like insectproof and dustproof net 11 is disposed in the air inlet 10. Further, the upper lid 6 and the lower lid 7 are provided with upright walls 6a, 7a in which screw holes 6b,.

  The casing 4 and the back outer plate 5 are preferably made of aluminum having excellent weather resistance, moldability, etc., and the upper lid 6 and the lower lid 7 have a low sound range in addition to weather resistance, moldability, etc. In order to obtain a silencing effect, it is desirable to use a heavy aluminum casting.

  Hereinafter, the arrangement of the outside air passage 30 and the sound absorbing materials 41 to 47 will be described in detail.

  As shown in FIG. 4, an outside air passage 30 is formed in the casing 4 by partition plates 13 to 15 provided extending from the front plate 12 toward the back outer plate 5. Specifically, a first passage 31 in which the outside air flowing in from the intake port 10 advances straight, and is formed adjacent to the first passage 31 so as to be folded back in a U-turn shape from the end of the first passage 31. A second passage 32 in which the outside air folded back in a straight line is formed, and is formed adjacent to the second passage 32 so as to be folded back in a U-turn shape from the end of the second passage 32, and the outside air folded back in a U-turn shape Is formed with an outside air passage 30 including a third passage 33 that goes straight, and a chamber space 34 that is continuous with the end of the third passage 33 and has a ventilation port communicating with the room. The first passage 31, the second passage 32 and the third passage 33 are set to have substantially the same passage cross-sectional area, and the opening areas of the folded portions 31a and 32a at the passage boundaries are also substantially the same. Is set.

On the other hand, in the arrangement of the sound absorbing material, sound absorbing materials 41 and 42 are stretched over the entire inner surface of the front plate 12 and the entire inner surface of the back outer plate 5. In addition, a sound absorbing material 43 is stretched over a range from the outside air collision surface at the end of the first passage 31 to the second passage 32, that is, the lower surface side of the partition member 13, and one side surface of the second passage 32, that is, A sound absorbing material 44 is stretched on the surface of the partition member 15 on the second passage 32 side. Further, a sound absorbing material 45 is stretched over the range from the outside air collision surface at the end of the second passage 32 to the third passage 33, that is, the upper surface of the lower lid 7 excluding the first passage, and one of the third passages 33 is provided. A sound absorbing material 46 is stretched on the side surface, that is, the surface of the side surface outer plate 2 on the third passage side 33. In the chamber space 34, sound absorbing materials 47, 47,.

  In the silencer 1, in the sound absorbing materials 41 to 47, the first passage 31 to the third passage 33 have sound absorbing materials (41 on at least two opposing surfaces so as to have an attenuation effect due to repeated reflection. , 42), and the sound absorbing materials 43, 45 need to be stretched on the outside air collision surface at the end of the first passage 31 and the outside air collision surface at the end of the second passage 32, respectively. Further, it is necessary that a sound absorbing material is stretched over the entire chamber space 34.

  In addition, when there is a margin in the size of the silencer 1, it is clear that it is desirable to provide a sound absorbing material on the entire surface around the first passage 31 to the third passage 33 in terms of the noise reduction effect. The flow path is narrowed by the thickness of the material, and there may be harmful effects such as wind noise due to the increase in flow velocity in an attempt to maintain sufficient airflow. As described above, the minimum sound absorbing material tensioning range is defined so that a sufficient amount of ventilation can be secured.

  Further, it is desirable that the passage length L of the first passage 31 is set with the tube length l obtained by the primary acoustic mode equation with one end open and the other end closed in the following equation (1) as the basic length with an acoustic frequency of 500 Hz. .

  In particular, the acoustic frequency band of 500 Hz (mainly in the range of 300 Hz to 700 Hz) is a band in which the silencing effect is difficult to occur, as shown in the examples described later, and the first passage 31 is compared to a tube with one end open and the other closed. Since the sound pressure is maximized at the closed end in the primary acoustic mode, the sound absorbing materials 43 and 45 are disposed at the position, so that the noise in the 500 Hz band is effectively silenced, resulting in a wide range. It is possible to provide a silencing effect in a frequency band of a large frequency. The tube length l calculated by the above equation (1) is 17.0 cm. Therefore, it is desirable to set the passage length of the first passage 31 to about 17 cm ± 5 cm, preferably about 17 cm ± 3 cm.

  Examples of the sound absorbing materials 41 to 47 include porous sound absorbing materials such as glass wool, rock wool, slag wool, felt, open cell foamed resin, sprayed fiber, wood wool / wood piece cement board, perforated soft fiber board, woven fabric, and flocked product. Materials are preferably used. The density and thickness of the sound-absorbing material can be arbitrarily set as long as a sufficient amount of ventilation can be secured. Further, the surface of the sound absorbing material may be flat or may have a shape with unevenness so that the sound absorbing area increases.

  In order to install the silencer 1 on a wall surface, as shown in FIG. 7, a ventilation hole 16 is formed in advance in a wall portion H that separates the room from the outside. It installs so that the ventilation cylinder 9 of the silencer 1 may be inserted from the outside. At this time, in order to seal the gap around the ventilation cylinder 9, it is desirable to wind a tight material 17 made of polyethylene foam or the like and fill the other gap with mortar or the like. Then, the upper lid 6 and the lower lid 7 are fixed to each other by screws formed on the standing walls 6a and 7a and screwed into the screw holes 6b and 7b.

  Next, the silencing effect of the silencing device 1 according to the present invention will be described with reference to FIG.

  By operating a ventilating fan or the like indoors, the inside of the room becomes a negative pressure compared to the outside, so that a flow of outside air from the air inlet 10 toward the air vent 8 is generated inside the silencer 1. The noise that has entered from the air inlet 10 through the insect-proof and dust-proof net 11 and the outside air that has entered the ventilation silencer 1 passes through the passages 31 to 33 and the chamber space 34, and is lined with the sound absorbing material. The sound absorption effect by 41 to 47, the effect of sound interference due to the collision with the wall surface, and the effect of increasing the sound absorption area and the distance attenuation of the sound absorbing material by taking a long channel length can mute with a wide range of frequency components. Intended to reach the room.

  The noise-removing function of each part will be described in detail along the flow of air. The noise that has entered from the air inlet 10 is lined on the front surface and the back surface of the first passage 31 when going straight through the first passage 31. The sound absorbing materials 41 and 42 absorb noise of frequency components corresponding to the properties of the sound absorbing material. Generally, high frequency noise is absorbed as a frequency component that can be absorbed by the sound absorbing material. Then, when the sound pressure of the noise I reaches the maximum at the end of the first passage 31, it collides with the sound absorbing material 43 and the sound pressure is attenuated. Further, in the process of repeatedly changing the course of the reflection by the folded portion 31a, the sound is absorbed by the sound absorbing material 43 lined on the side surface, and is canceled by the interference with the reflected wave N due to the collision. The sound absorbing action by the above-described sound absorbing material and the sound deadening action by interference are similarly performed in the second passage 32 and reach the chamber space 34 through the third passage 33. In the silencer 1, by increasing the flow path length of the outside air passage 30, the sound absorbing area of the sound absorbing material can be increased, the sound absorbing action can be improved, and the sound deadening effect can be increased by distance attenuation. It is known that the effect of noise reduction due to distance attenuation generally increases widely from a low frequency to a high frequency as the duct size decreases, and thereby noise of a wide range of frequency components can be silenced. When the sound wave reaches the wide chamber space 34, the energy is reduced by the expansion, and then flows into the room through the ventilation port 8.

[Second embodiment]
In the first embodiment, the outside air passage 30 is formed in the casing 4 surrounded by the front plate 12, the side plates 2, 2, the back plate 5, the upper lid 6 and the lower lid 7, and the sound absorbing material is directly applied to the inner surface thereof. Although the lining is used, it may be necessary to replace the sound-absorbing material due to the occurrence of dirt and moisture caused by the intrusion of fine dust, and the deterioration of sound-absorbing performance due to aging of the sound-absorbing material. It is desirable that the outer casing and the inner casing are formed, the outside air passage and the chamber space are formed in the inner casing, and the inner casing is detachable from the outer casing.

  Specifically, as shown in FIG. 9, a circular ventilation port 8 is formed at the center upper portion on the back surface of the casing 4 having a U-shaped cross section composed of the thin side plates 2 and 2 and the front outer plate 3. The outer casing 18A closed in the circumferential direction by screwing the rear panel 5 is screwed, and a rectangular tube having a rectangular cross section constituted by the front panel 12, the side panels 19, 19 and the rear panel 20 is used as the inner casing 18B. And The internal structure of the inner casing 18B is exactly the same as that of the first embodiment.

  When the inner casing 18B is inserted into the outer casing 18A, the protruding piece of the front plate 12 of the inner casing 18B is locked to the locking pieces 2a and 2a extending from the inner surfaces of the side plates 2 and 2 of the outer casing 18A. In this way, by removing the upper lid 6 or the lower lid 7, it can be removed from the upper and lower openings of the outer casing 18A.

  Air layers 21 and 22 are formed at the front side boundary and the side side boundary between the outer casing 18A and the inner casing 18B, respectively. The air layers 21 and 22 serve as finger insertion spaces when the inner casing 18B is removed, and the air layers 21 and 22 have an effect of blocking sound waves propagating from the outer casing 18A to the inner casing 18B.

  Next, it verified in experiment about the noise reduction performance of the silencer 1 for ventilation openings.

  The performance of the ventilator 1 was evaluated by measuring the transmission loss based on the sound transmission loss measurement method for small building parts proposed by the Architectural Institute of Japan. The outline is described below.

  The structure of the test body is as follows. Example 1 is the structure of the silencer 1 which concerns on this invention shown in FIGS. In the second embodiment, as shown in FIG. 10A, a sound absorbing material 49 is lined on the inner surface of the side plate 2 of the first passage 31 with respect to the first embodiment. In the first comparative example, as shown in FIG. 10 (B), the chamber space is configured such that the air that has entered from the air inlet 10 advances straight, and the outside air is bent at a right angle and flows in at the end of the passage. It is the structure which consists of. As shown in FIG. 10C, the comparative example 2 has a structure including the first passage 31 to the third passage 33 and the chamber space 34 as in the first embodiment. The sound absorbing material is lined only on the bottom surface of the folded portion 32a communicating with the three passages 33 and the lower surface of the upper lid 6 of the chamber. As shown in FIG. 10 (D), the third comparative example removes the partition plate 14 of the first passage 31 and the second passage 32 from the structure of the first embodiment, and is wide and adjacent to the intake port 10. This is a structure in which one chamber space is formed and communicated with the chamber space 34 via the third passage 33. Comparative Examples 4 and 5 are commercially available silencers.

  The results of transmission loss measurement for each of the above examples and comparative examples are shown in Table 1 and shown in FIG. Table 1 shows the calculated transmission loss (in dB) for each 1/3 octave band frequency in each example and comparative example. FIG. 11 shows the horizontal axis as 1/3 octave band frequency (in Hz) and the vertical axis. Is represented in a graph with transmission loss (unit: dB). In FIG. 11, T-2, T-3, and T-4 represent the sound insulation class according to the specifications of JIS A 4706 and JIS A 4702. In the present invention, the T-4 class is the sound insulation class of the high-performance soundproof sash. The goal was to satisfy the line. According to JIS A 4706 and JIS A 4702, when the sound transmission loss at 16 points from 125 Hz to 4000 Hz exceeds all applicable sound insulation grade lines, the sound insulation grade is judged by the grade indicated by the grade line. To do. In addition, when the sum of the values below the corresponding sound insulation grade line in each frequency band is 3 dB or less, it is determined as the sound insulation grade.

  As a result, it was found that the noise in the 500 Hz band could not be reduced in the case of a structure that does not have a plurality of folded outside air passages as in Comparative Example 1 (FIG. 10B). This is considered to be caused by a resonance phenomenon in the passage. In Comparative Example 2 (FIG. 10 (C)), it was demonstrated that the transmission loss in the 500 Hz band can be slightly improved by adopting a structure that flows from the intake port 10 through the outside air passage 30 and flows into the chamber space 34. This can be presumed to be due to the effect of sound absorption by the sound absorbing material and the effect of noise interference when passing through the outside air passage several times, but the results are still insufficient to satisfy the T-4 grade line. became. Although Comparative Example 3 (FIG. 10D) was found to reduce noise in the 500 Hz band as compared with the other Comparative Examples, the results were still insufficient to satisfy the T-4 grade line. . Furthermore, it was found that neither Comparative Example 4 nor Comparative Example 5 in the commercial product was satisfactory even with the T-2 grade line.

  In contrast to these comparative examples, in Example 1, in addition to noise in the 500 Hz band, low-frequency and high-frequency noises were also absorbed and silenced to satisfy the sound insulation grade T-4. Further, in the second embodiment, the sound absorbing material 49 is lined on the side surface of the first passage 31 with respect to the structure of the first embodiment, so that the transmission loss is slightly increased and the sound insulation grade T-4 is sufficiently satisfied. There was found.

  Next, as a test of the ventilation performance of the ventilator silencer 1, the relationship between the pressure difference and the ventilation rate was experimentally measured for Examples 1 and 2 and Comparative Examples 1, 4, and 5. The outline is described below.

Each test specimen was attached to a ventilation port provided on the wall between adjacent chambers, and the amount of air passing through the test specimen and the wind speed when a pressure difference was applied between the chambers were measured. As the pressure difference between the chambers, the increase and decrease were reciprocated up to 100 Pa, and the air flow rate (unit m ³ / h) and the wind speed (unit m / s) when the pressure difference was 10, 30, 50, 100 Pa were measured. The results are shown in Table 2 and FIG. Table 2 shows measured values in each Example and Comparative Example, and FIG. 12 is a logarithmic graph with the horizontal axis representing the pressure difference (unit Pa) and the vertical axis representing the air flow rate (unit m ³ / h). is there.

  As a result, it was confirmed from Table 2 and FIG. 12 that the silencer 1 can secure a functionally sufficient air flow rate and logarithmically increase the air flow rate against the pressure difference. Moreover, it became clear from Table 2 that the wind speed of the silencer 1 can be reduced as compared with the comparative example. Thereby, it can be expected that secondary noise such as wind noise can be prevented by increasing the wind speed inside the silencer.

[Other examples]
(1) In the above embodiment, the present silencer is the vertical silencer 1 that is vertically mounted on the wall surface. However, due to installation space limitations and the like, the silencer is a horizontal lateral silencer as shown in FIG. 1A. Structurally, it is basically the same as the first embodiment, and is provided with an intake port 10 on the bottom surface, a first passage 31 in which the outside air flowing in from the intake port 10 goes straight, and a U-turn shape from the end of the first passage 31 The second passage 32 is formed adjacent to the first passage 31 so as to be folded back and the outside air folded back in a U-turn shape goes straight, and the second passage 32 is folded back in a U-turn shape from the end of the second passage 32. A ventilation passage which is formed adjacent to the two passages 32 and which is continuous with the end of the third passage 33 and communicates with the interior of the third passage 33. The internal structure includes a chamber space 34 in which the mouth 8 is formed.

  When the horizontal silencer 1A has the same passage width as that of the vertical silencer 1, the overall passage length of the outside air passage 30 is shortened, but the volume of the chamber space 34 can be increased. Further, compared to the vertical silencer 1, the number of times outside air traveling in the outside air passage collides with the wall surface can be increased. That is, in the first embodiment, the chamber space 34 is located immediately above the third passage 33. However, in the second embodiment, the portion directly above the third passage 33 becomes a wall, and the number of collisions can be increased by one.

It is a rear view of the silencer 1 for ventilation openings which concerns on this invention. It is the side view. It is the bottom view. It is IV-IV sectional drawing of FIG. VV cross-sectional view of FIG. It is VI-VI sectional drawing of FIG. It is a longitudinal cross-sectional view which shows the installation state of the silencer 1 for ventilation openings. It is a silencing effect explanatory drawing of the silencer 1 which concerns on this invention. The modification of the silencer 1 is shown, (A) is a cross-sectional view, (B) is a longitudinal front view, and (C) is a longitudinal side view. The test body structure in an Example is shown, (A) is Example 2, (B) is Comparative Example 1, (C) is Comparative Example 2, and (D) is Comparative Example 3. It is a graph of the calculated value (unit dB) of the transmission loss for every 1/3 octave band frequency. It is a graph represented on a log-log graph with the horizontal axis representing the pressure difference (unit Pa) and the vertical axis representing the air flow rate (unit m ³ / h). In the case of the horizontal silencer 1A, (A) is a transverse side view, (B) is a longitudinal front view, and (C) is a horizontal cross-sectional view. It is a vertical front view which shows the conventional silencer for ventilation openings. It is a schematic perspective view which shows the conventional silencer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Silent device for ventilation opening, 2 ... Outer side plate, 3 ... Front outer plate, 4 ... Casing, 5 ... Rear outer plate, 6 ... Upper lid, 7 ... Lower lid, 8 ... Ventilation port, 9 ... Ventilation tube, 10 DESCRIPTION OF SYMBOLS ... Air inlet, 11 ... Insect and dust net, 12 ... Front plate, 13-15 ... Partition plate, 16 ... Wall ventilation hole, 17 ... Tight material, 18A ... External casing, 18B ... Internal casing, 30 ... Outside air passage, 31 ... 1st passage, 32 ... 2nd passage, 33 ... 3rd passage, 34 ... Chamber space, 41-49 ... Sound-absorbing material

Claims (5)

It is a vertically long shape of a substantially rectangular parallelepiped, and is a silencer for a ventilation opening that is attached to a wall surface in a vertical direction,
The ventilation silencer has a rear outer plate attached to the rear side of a U-shaped casing composed of a thin flat side outer plate and a front outer plate, and the upper and lower portions of the casing are made of cast aluminum. And an external air passage is formed in a space surrounded by the front plate, the side outer plate, the rear outer plate, the upper cover, and the lower cover, and is externally provided at one end of the lower cover. An open air inlet is formed,
The outside air passage is formed adjacent to the first passage through a first partition plate so that the outside air flowing in from the intake port goes straight, and is folded in a U-turn shape from the end of the first passage . And a second passage through which the outside air folded back in a U-turn shape goes straight, and is formed adjacent to the second passage through a second partition plate so as to be folded back in a U-turn shape from the end of the second passage . And an outside air passage composed of a third passage through which the outside air folded back in a U-turn shape goes straight, and a chamber space formed at the end of the third passage and having a ventilation port communicating with the room, Each passage of the outside air passage is arranged along the vertical direction, and the chamber space is provided in an upper portion of the outside air passage,
In the outside air passage, a sound absorbing material is stretched on two opposing surfaces of the inner surface of the front plate and the inner surface of the rear outer plate, and the second passage side of the second partition plate and the second surface plate of the side outer plate. A sound absorbing material is stretched on the three passage sides, and no sound absorbing material is stretched on the first passage side of the first partition plate and the first passage side of the side surface outer plate, and the first passage end A sound-absorbing material for a vent opening, wherein a sound absorbing material is stretched on each of the outside air collision surface and the outside air collision surface at the end of the second passage, and a sound absorbing material is stretched over the entire chamber space. 2. The passage length of the first passage is set as a basic length with a tube length l obtained by a primary acoustic mode equation with one end opened and the other end closed in the following equation (1) with an acoustic frequency of 500 Hz. Silencer for ventilation openings.

  The ventilator silencer comprises an outer casing and an inner casing, wherein the outer air passage and chamber space are formed in the inner casing, and the inner casing is detachable from the outer casing. The silencer for a vent according to any one of 1 and 2.   The silencer for a ventilator according to any one of claims 1 to 3, wherein an air layer is formed in at least a front side boundary and a side side boundary between the outer casing and the inner casing.   The ventilation silencer according to any one of claims 1 to 4, wherein the first passage, the second passage, and the third passage are set to have substantially the same passage cross-sectional area.

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