JP2000074471A - Muffler for air duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce passing resistance of fluid by bonding a barrier wall made of a high sound transmittance material, e.g. hard urethane, to the convex surface of an acoustic material through adhesive thereby isolating a fluid channel surrounded by the barrier wall from a muffler section. SOLUTION: A shell 3 manufactured by welding is provided, in the opposite faces thereof, with a fluid inlet 7 and a fluid outlet 8 and a partitioning plate 9 having openings similar to the fluid inlet 7 and the fluid outlet 8 is fixed to the inside of the shell 3 thus forming a plurality of muffler sections 13. Between the fluid inlet 7 and the fluid outlet 8, a barrier wall 1 made of a high sound transmittance material, e.g. hard urethane, is bonded to the fluid inlet 7, the fluid outlet 8 and the partitioning plate 9 through adhesive on the convex surface of an acoustic material 2 thus isolating a fluid channel 12 surrounded by the barrier wall 1 from the muffler section 13. According to the structure, passing resistance of fluid can be reduced even if the volume at the muffler section 13 is varied or irregularities are present in the acoustic material 2 or the muffler section 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler used for an air duct.

[0002]

2. Description of the Related Art Conventionally, as an air duct silencer, (a) a sound absorbing material is applied to the inner surface of a straight pipe air duct, and a sound absorbing material is subjected to a scattering prevention treatment on a fluid contact surface of the sound absorbing material so that the sound absorbing material is not scattered by an air flow. Duct applied inside the silencer. (B) A cell type in which the fluid flow path of the air duct is divided, a sound absorbing material is attached to each inner surface, and the sound absorbing material is subjected to a scattering prevention treatment on the fluid contact surface so that the sound absorbing material is not scattered by the air flow. Silencer (c) A sound-absorbing elbow with the air bend elbow formed with a right angle at the outer bend and a sound-absorbing material attached to the inner surface, and a sound-absorbing material that has a fluid-contacting surface that prevents the sound-absorbing material from scattering due to airflow. . (2) Provide a chamber in the middle, branch, or bend of the air duct, apply a sound absorbing material to the inner surface, and apply a scattering prevention treatment to the fluid contact surface of the sound absorbing material so that the sound absorbing material does not scatter due to airflow. There was a silencing chamber.

[0003]

This has the following disadvantages. (A) The sound-absorbing inner duct has to be long in order to increase the surface area of the sound-absorbing material because the sound-absorbing material is applied to the inner surface of a straight pipe air duct having a separately determined cross-sectional size. (B) The surface of the sound-absorbing inner duct is large because the surface of the sound-absorbing material duct has large irregularities due to the sound-absorbing material scattering prevention treatment and the sound-absorbing material fixing tool. If so, the passage resistance would be even greater. (C) Further, as a characteristic of the sound deadening inner duct, as the cross-section becomes larger, the sound deadening effect tends to decrease drastically. Often, it was necessary to increase the sound absorbing area, which further increased the flow resistance of the fluid and increased the production cost.

[0004] The cell type silencer is divided into smaller sections in order to improve the characteristic that the noise reduction effect is drastically reduced when the section of the duct inside the silencer becomes larger. This type of silencer has a large fluid passage resistance because the passage resistance of the muffler is large.

(A) The sound-absorbing elbow has a rectangular outer bent portion, and the fluid contact surface treated to prevent the sound-absorbing material from scattering has large irregularities on the surface by means of a sound-absorbing material fixing device. It was a passing resistance. (B) In addition, the part where the sound absorption processing of the silence elbow is performed is limited to the inner surface of the elbow, which is the limit of the silence. (C) Further, the airflow of the silencing elbow was disturbed due to the right angle of the outer curved portion, which also became a large resistance to the passage of the fluid.

(A) The silencing chamber has a large cross-sectional change at the fluid inlet / outlet, which causes a large passage resistance of the fluid. (B) Large cross-sectional changes at the fluid inlet and outlet of the silencing chamber often caused a pulsation of fluid pressure, which vibrated the outer shell of the silencing chamber and became a noise source. (C) Unless the fluid inlet and outlet of the silencing chamber were provided on the same surface of the outer shell, part of the noise that entered the silencing chamber went directly out of the other mouth without being silenced.

The anti-scattering treatment applied to the sound absorbing material inside duct, the sound absorbing elbow and the sound absorbing chamber has reduced the sound absorbing function of the sound absorbing material.

[0008] The main source of noise to be silenced in the air duct is a blower which is a fluid carrier, but the fluid carrier pressure must be increased due to the silencer having a high resistance to fluid passage. In order to achieve this, it is necessary to increase the rotation of the blower, and if the rotation is increased, the required power is further increased, and at the same time, the generated noise is also increased, and the silencing volume to be processed is increased.

According to the present invention, the sound absorbing material has a large area,
Even if the volume of the sound-absorbing part changes, or if the sound-absorbing material or the sound-absorbing part has irregularities, it reduces the fluid's passage resistance. It is an object of the present invention to provide a muffler for an air duct which does not reduce the noise and a method for manufacturing the same.

[0010]

In order to achieve the above object, in the silencer of the present invention, the surface area of the sound absorbing material is increased, and the sound absorbing portion is formed in various shapes to increase the sound absorbing effect. Therefore, when the fluid passage resistance becomes large, a noise-reducing portion and the fluid passage are separated by a material having good sound permeability, and a smooth fluid passage having a small fluid passage resistance is provided.

A straightening vane is provided in a sharply curved portion of the fluid flow path to provide a smooth fluid flow path having a small resistance to fluid passage, but a sound-transmitting part is provided in a portion where the straightening vane impairs the sound deadening performance. A rectifying vane that does not impair the sound-absorbing performance is manufactured by using a good material or a material having excellent sound absorption.

Further, a part of the fluid passage is made of a material having good sound insulation and another part is made of a material having good sound permeability so that noise entering the silencer does not directly come out of the opening of another fluid inlet / outlet. A fluid flow path is formed so as to have a smooth shape with low fluid passage resistance.

When the pressure of the fluid is large, a pressure equalizer is provided on the material separating the muffling section and the fluid flow path to reduce the pressure difference between the inside and outside of the fluid flow path, and the muffler is connected to the fluid flow path. Avoid stress on the separating material.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings based on embodiments. (A) In FIG. 1 and FIG.
A fluid inlet 7 and a fluid outlet 8 are provided on opposing surfaces, and a partition plate 9 having the same opening as the fluid inlet 7 or the fluid outlet 8 is provided inside the outer shell. Is attached to the outer shell 3 by, for example, welding using the same steel plate as the outer shell 3, for example, and a plurality of sections of the silencer 13 are provided. (B) The sound absorbing material 2 of, for example, a glass fiber molded plate is adhered to the inner surface of the section with, for example, an adhesive to form the sound deadening portion 13. (C) Between the fluid inlet 7 and the fluid outlet 8, the partition 1 made of a material having good sound transmission properties, such as hard urethane, is used. To separate the fluid passage 12 surrounded by the partition 1 from the muffling section 13. (D) When the partition walls 1 are separately mounted, the partition walls 1 are also fixed to each other by, for example, an adhesive. (E) When the strength of the partition 1 is low, for example, 1.2
An expanded metal made of a steel plate having a thickness of mm is buried in the inside of the partition wall 1 as a reinforcing material, or attached to the outside of the surface to which pressure is applied by, for example, an adhesive. (F) Further, as shown in FIG. 25, a pressure equalizer 10 made of, for example, a nylon non-woven fabric is fitted into the opening of the partition wall 1 that has been pre-punched without any gap, and both sides of the pressure equalizer are made of, for example, a stainless steel mesh of about 3 mm mesh. It is sandwiched between the partition walls 1 by the fixture 11. The pressure equalizer fixture 11 is attached around the hole of the partition wall 1 with, for example, an adhesive. (G) Mufflers 1 of multiple sections around the entire periphery of the fluid flow path
4, the sound absorbing material 2 of a glass fiber molded plate was adhered to the outer shell 3 with an adhesive, for example, as in the non-stepped surface of FIG. The fluid passage 12 may be used as the sound absorbing surface 5. (H) The cross-sectional shape of the fluid flow path 12 and the outer shell 3 can be a rectangular cross-section as shown in this figure, other circular, oval, elliptical, or various cross-sectional shapes. There can be more than one.

(A) In the embodiment shown in FIG. 3, the outer appearance is the same as that of FIG. 1, and the outer shell 3 is made of, for example, a steel plate having a thickness of 0.5 mm to 1 mm, for example, by welding, and the outer surface is formed on the opposite surface. A fluid inlet 7 and a fluid outlet 8 are provided. (B) As a sound absorbing material 2, for example, a glass fiber pipe insulation tube is used as the sound absorbing material 2 on the inner surface of the outer shell 3, and the sound absorbing member 13 is fixed to the outer shell 3 with, for example, an adhesive. (C) A partition 1 made of a material having good sound transmission properties, such as hard urethane, is fixed to the convex surface of the sound absorbing material 2 with, for example, an adhesive, and a fluid flow path 12 surrounded by the partition 1 and the sound deadening section 1 are fixed.
Separate three. (D) The direction of the sound absorbing material 2 can be reversed, and the convex surface can be directed to the outer shell 3. (E) The sound absorbing material 2 also has a role of supporting the partition 1. (F) When the strength of the partition wall 1 is low, for example, 1.2
An expanded metal made of a steel plate having a thickness of mm is buried in the inside of the partition wall 1 as a reinforcing material, or attached to the outside of the surface to which pressure is applied by, for example, an adhesive. (G) The cross-sectional shape of the fluid flow path and the outer shell 3 can be a rectangular cross-section as shown in this figure, other circular, oval, elliptical, or various cross-sectional shapes. You can also

(A) In the embodiment shown in FIG. 4, the outer appearance is the same as that of FIG. 1, and the outer shell 3 is made of, for example, a steel plate having a thickness of 0.5 mm to 1 mm, for example, by welding. (B) The sound absorbing material 2 made of, for example, a glass fiber molded plate is attached to the inner surface of two opposing surfaces of the outer shell 3 in a stepwise manner. (C) The top of the inner surface of the sound absorbing material 2 and the partition 1 made of a material having good sound transmission properties, such as hard urethane, are fixed with, for example, an adhesive to form a fluid flow path 12. It also has the role of supporting 1 as in the previous section. (2) In order to increase the strength of the step-like sound damping material 2, for example, an expanded metal manufactured from a steel plate having a thickness of 1.2 mm is formed in a step-like manner and attached to the outer shell 3 by welding, for example. As a backup material for the silencer 2, the staircase-like silencer 2 is fixed to the inner side of the expanded metal silencer with, for example, an adhesive. (E) On the other two surfaces inside the outer shell 3, the sound absorbing material 2 made of, for example, a glass fiber molded plate is attached to the outer shell 3 with an adhesive, for example, and the inner side of the sound absorbing material 2 is made of, for example, glass cloth. The sound absorbing surface 5 which has been subjected to the scattering prevention processing is used as the fluid flow path surface. (F) A sound absorbing material having the shape shown in FIG. 3 and a sound absorbing material having the shape described in this section are mixed and attached to two opposing surfaces of the outer shell 3, or one surface is formed as a sound absorbing material having the shape shown in FIG. A sound absorbing material having the shape of No. 3 can also be used.

In the embodiment shown in FIG. 5, the fluid inlet 7 is provided at two places and the fluid outlet 8 is provided at one place, and the other portions are the same as those shown in FIG. 1, FIG. 2, FIG. 3 or FIG. Further, the fluid inlet 7 may be one place and the fluid outlet 8 may be two places.

In the embodiment shown in FIG. 6, the mounting surfaces of the plurality of fluid inlets 7 are provided on different surfaces. However, a plurality of fluid outlets may be provided and the mounting surfaces may be provided on different surfaces. Others are the same as FIG. 1, FIG. 2, FIG. 3, or FIG.

In the embodiment shown in FIG. 7, the sizes of the fluid inlet 7 and the fluid outlet 8 are different. Others are the same as FIG. 1, FIG. 2, FIG. 3, or FIG.

FIG. 8 shows the silencer of the embodiment shown in FIGS.
Although it is shaped like a letter, it can also be shaped like a letter U or letter S. The embodiments of FIGS. 3, 4, 5, 6 or 7 can likewise be L-shaped, U-shaped or S-shaped. Further, a fluid rectifying vane similar to that shown in FIGS. 15, 17 and 19 can be attached to the bent portion of the fluid flow path.

(A) In FIG. 10 and FIG.
For example, a steel plate having a thickness of 0.5 mm to 1.2 mm is manufactured by welding, for example, and a fluid inlet 7 and a fluid outlet 8 are provided on adjacent surfaces at an angle of 90 degrees. (B) Inside the outer shell, a partition plate 9 having the same opening as the fluid inlet 7 or the fluid outlet 8 is attached to the outer shell 3 by, for example, welding with the same steel plate as the outer shell 3 to provide a plurality of partitions. (C) The sound absorbing material 2 of, for example, a glass fiber molded plate is adhered to the inner surface of the section with, for example, an adhesive to form the sound deadening portion 13. (D) Two opposing curved surfaces of the fluid flow path 12 between the fluid inlet 7 and the fluid outlet 8 are made of the partition wall 1 of a material having good sound permeability such as hard urethane, and the fluid is fluidized with an adhesive, for example. Attach to inlet 7, fluid outlet 8, and partition plate 9. (E) When the strength of the partition 1 is low, for example, 1.2
An expanded metal made of a steel plate having a thickness of mm is buried in the inside of the partition wall 1 as a reinforcing material, or attached to the outside of the surface to which pressure is applied by, for example, an adhesive. (F) Further, a pressure equalizer 10 can be provided on the partition 1 in the same manner as in the case of FIG. (G) The other two surfaces are made of, for example, a sound absorbing material 2 of a glass fiber molded plate.
Is attached to the outer shell 3 with an adhesive, for example, in a plane, and the inner surface of the muffler of the sound absorbing material 2 is a fluid passage surface as a sound absorbing surface 5 which has been subjected to scattering treatment with, for example, a glass cloth. (H) Further, the sizes of the fluid inlet 7 and the fluid outlet 8 can be changed. Further, the cross-sectional shape of the fluid flow channel 12 and the outer shell 3 may be a rectangular cross-section as shown in this figure, a circular shape, an oval shape, an elliptical shape, or various cross-sectional shapes.

(A) FIG. 12 shows an example in which the sound absorbing material 2 of the example of FIG. 11 uses a glass fiber pipe heat insulating cylinder, and other details are the same as those of FIG. (B) Alternatively, the shape of the sound absorbing material 2 may be the same as the sound absorbing material of FIG.

(A) FIGS. 13 and 14 show a fan-shaped outer shell 3 having a fan shape, and a sound deadening material 2 similar to that shown in FIG. Lumber 2
The partition wall 1 formed in an arc shape is attached to the inner surface side vertex of the fluid flow path 12 to form two surfaces. (B) The details of the partition 1, the other two surfaces of the fluid flow path, the partition 1, and the outer shell 3 are the same as those in FIG.

(A) FIGS. 15 and 16 show a case where the fluid rectifying vanes 4 are provided inside the fluid flow paths of FIGS. 11, 12 and 13. FIG. (B) The fluid rectifying vane 4 is made of a material having excellent sound absorbing and sound transmitting properties, such as a 1.6 mm thick aluminum fiber molded plate, or a sound transmitting material, such as hard urethane having a small bulk weight. It can be made of good material. (C) Alternatively, the outer shell 3 may be made of the same steel plate. (D) The number of fluid rectifying vanes in this example is two, but it can be one or several, and these fluid rectifying vanes are mixed with those manufactured from the various materials described above. Can also be used.

(A) FIGS. 17 and 18 show the fluid flow paths of FIGS. 11, 12 and 13 which are bent at substantially right angles.
A fluid straightening vane for right-angled bending is attached to the bent portion. (B) The fluid rectifying vane can use the same material as in FIG. (C) As shown in FIG. 19, the fluid rectifying vane 4 can be formed in a simple shape.

FIG. 20 shows two fluid inlets or outlets, the details of which are the same as in FIGS. 11, 12 and 13. Also, a fluid flow vane similar to that shown in FIG. 15 can be attached to the fluid flow path, and the bent shape of the fluid flow path and the internal fluid flow vane can be the same as those shown in FIGS.

(A) In FIGS. 21 and 22, the outer shell 3 having a large internal space is, for example, 0.5 mm to 1.
A steel plate having a thickness of 6 mm is manufactured by welding, for example, and the outer shell 3 is formed.
Are provided with a fluid inlet 7 and a fluid outlet 8 on the required surface. (B) The sound absorbing material 2 of, for example, a glass fiber molded plate is adhered to the inner surface of the outer shell 3 with, for example, an adhesive to form the sound deadening portion 13. (C) The fluid flow path 12 between the fluid inlet 7 and the fluid outlet 8 is formed of a partition wall 1 made of a material having good sound permeability such as hard urethane.
For example, it is made of the same steel plate as the outer shell 3 and made of a material 6 that does not transmit sound. (D) The part using the material 6 which does not transmit sound is the fluid inlet 7
It is used so that sound does not directly reach between the fluid and the eight fluid outlets, and the portion is made as small as possible in area. (E) The fluid flow path 12 is made of a fluid
Attach to fluid outlet 8. (F) When the strength of the partition wall 1 is low, for example, 1.2
An expanded metal made of a steel plate having a thickness of mm is buried in the inside of the partition wall 1 as a reinforcing material, attached to the outside of the surface to which pressure is applied by, for example, an adhesive, or a pressure equalizer 10 is provided as in the case of FIG. (G) Further, as shown in FIG.
The fluid passage 12 can be supported by being fixed to the outer shell 3 by, for example, welding between the fluid inlet 7 and the fluid outlet 8. (I) The cross-sectional shape of the fluid flow path and the outer shell 3 can be a rectangular cross-section as shown in this figure, other circular, oval, elliptical, or various cross-sectional shapes. Can also be multiple. (V) The size of the fluid outlet 8 and the fluid inlet 7 may be changed, or both or either of the fluid outlet 8 and the fluid inlet 7 may be provided in plural. (L) The fluid flow path can be manufactured without using the material 6 that does not transmit sound. (ヲ) In the bent portion of the fluid flow path, FIG.
A fluid rectifying vane 4 similar to that of FIG.

(A) FIGS. 22 and 23 show the sound absorbing material 2 of the muffler of the preceding paragraph which is a glass fiber pipe insulation tube and has two inlets or outlets. The other details are shown in FIGS. 21 and 22. The same shall apply. (B) The shape of the sound absorbing material 2 may be the same as that of the sound absorbing material of FIG. 4, or the shape of FIG.
The same shape as the sound absorbing material 2 can be used.

[0029]

Since the present invention is configured as described above, it has the following effects.

The silencer 13 and a part of the fluid channel 12 or
All are made of a material having good sound transmission properties, and are separated by smooth-shaped partitions, so that the following effects can be obtained in the sound absorbing portion.

The surface scattering treatment by the air current of the sound absorbing material 2 becomes unnecessary, and the sound absorbing performance inherent to the sound absorbing material is not impaired by the surface treatment.

The influence of the airflow of the sound absorbing material is eliminated, and the strength of the sound absorbing material and the strength of fixing the sound absorbing material to the outer shell can be reduced as compared with the conventional case. A glass fiber molded plate of cubic m or less can be used as the sound absorbing material, and the fixing of the sound absorbing material is simple and economical.

Conventionally, part or all of the sound absorbing material is peeled off,
Although scattered and carried by the airflow, it caused a wide range of pollution damage and blocked the fluid flow path, but the partition wall 1 prevents the separated and scattered sound absorbing material from entering the fluid flow path.

The necessity of the surface scattering treatment of the sound absorbing material is eliminated, and the influence of the surface shape on the fluid passage resistance is eliminated, and the sound receiving surface of the sound absorbing material can be formed into a shape with unevenness and unevenness.

The sound absorbing material having a concave and convex shape has a large sound receiving surface and also has a resonance sound absorbing structure, which promotes an increase in sound deadening volume and makes it easy and economical to manufacture a silencer excellent in sound deadening performance. be able to.

Also, by making the surface of the outer side of the sound absorbing material uneven and uneven, a back air layer for improving sound absorbing performance can be constructed, and a silencer having excellent sound absorbing performance can be easily formed. , Can be manufactured economically.

The need for the surface scattering treatment of the sound absorbing material is eliminated, and the influence of the surface shape on the fluid passage resistance is eliminated. For example, a pipe insulation tube made of glass fiber or rock wool can be used as the sound absorbing material. It is possible to easily and economically construct a sound deadening portion having excellent sound deadening performance in a shape with irregularities and uneven shapes.

The noise entering from the inlet or the outlet of the silencer passes through the partition wall 1 having good sound permeability and hits the sound absorbing material having the improved sound absorbing performance. Is guided to the fluid flow path formed by the smooth-shaped partition, and exits from the muffler outlet with a small passage resistance.

The fluid flow path having a smooth shape eliminates noise generated when the fluid passes, and the smooth shape bend has a silencing function due to the shape itself, which further improves the silencing performance of the silencer.

By providing a fluid rectifying vane at the bent portion of the fluid flow path, the fluid passage resistance can be further reduced, and the fluid rectifying vane can be made of a material having good sound transmission properties or a material having good sound deadening properties. , The silencing performance is further improved.

When the fluid passage resistance is reduced, the number of revolutions of the fluid carrier can be reduced, the noise generated by the fluid carrier is also reduced, and the volume to be processed is also reduced.

Further, the transfer power is reduced, and the equipment cost and the operation cost are reduced.

By providing a pressure equalizer at a key point of the partition wall separating the sound deadening portion and the fluid passage portion, the pressure between the sound deadening portion and the fluid flow path can be balanced, and the partition wall can be protected from the stress caused by the pressure difference. be able to.

The silencer of FIG. 2 of the present invention, the center frequency of the conventional silencer inside duct from 63 Hz to 4 KHz, the silencing volume in the A characteristic and the B characteristic, and the fluid passage resistance in the case of standard air. Are compared under the following conditions. (A) The size of each of the fluid flow paths is a rectangular section of 0.2 m on each side, and the length of each of the fluid flow paths is 0.8 m.
The fluid flow rate is set to 500 m3 / h. (B) The sound-absorbing material for the conventional sound-absorbing duct is 32 kg.
/ Glass fiber molded plate with bulk density of cubic m, thickness 25
The surface of the fluid flow path side is made of glass cloth by using an object of mm. (C) The material of the partition wall 1 of the muffler of FIG. 2 is 35 kg / cubic m.
A hard urethane having a bulk density of 5 mm is used, a sound absorbing material is a glass fiber molded plate having a bulk density of 32 kg / cubic m, and a material having a thickness of 25 mm is used. The distance (depth) of the sound absorbing portion between the fluid flow path surface of the partition 1 and the inner surface of the outer shell 3 is set to 0.2 m in all four turns. (2) The silencer of FIG. 2 has three partition plates 9 and divides the section of the sound absorbing section into four sections of equal intervals of 0.2 m.

The silencing volume of the silencer of FIG. 2 of the present invention is obtained under the conditions described in the preceding section. (A) Noise entering the silencer from one mouth passes through the four compartments of condition (2) one after another and is silenced, while the other fluid passes through the interior of the fluid flow path from the inlet to the outlet. I will (B) Each of the four sections is regarded as a hollow silencer or a silencing chamber, and the silencing volume is determined. (C) Since the length of the cavity cross section is 0.6 m, the wavelength of 63 Hz to 500 Hz, which is a frequency of 0.6 m or more, is regarded as a hollow silencer, and the frequency of 1000 Hz or more is regarded as a silencing chamber. Calculate the silencing volume. (D) The sound transmission loss of the partition 1 can be obtained by the following equation (1).

[0046]

(Equation 1)

The silencing volume of the hollow silencer can be calculated by Equation 2, and the silencing volume of the silencing chamber can be calculated by Equation 3.

[0048]

(Equation 2)

[0049]

(Equation 3)

The calculation results of the transmission loss of the partition wall 1 are shown in Table 1. From 63 Hz to 1 KHz, the result is negative, and it can be seen that the sound passes without loss. So from 63Hz to 1
The results of calculating the silencing volume at frequencies up to KHz using the formula in the previous section (b) and the literature (air conditioning and sanitation technology data book)
I. of the 2nd edition Techno Ryowa). Table 2 shows the volume of the muffled sound of the prior art muffler under the above-mentioned conditions of Chart I-32 on page 15. Although the silencer of FIG. 2 has a silencing volume for 2 kHz or higher, the calculation is complicated, which is disadvantageous in the evaluation of the present invention, but it is considered that there is no silencing volume.

[0051]

[Table 1]

[0052]

[Table 2]

Comparing the muffled sound volume of the conventional muffler inside duct and the muffler of FIG. 2 of the present invention, the muffler of FIG. 2 wins with a difference of 10 db or more in the A characteristic and the B characteristic which are comprehensive evaluations. It can be seen from the comparison of the silencing volume of each frequency that the sound is excellent in a low frequency range where silencing is difficult.

Regarding the passage resistance of the fluid, it can be considered that the silencer sticking duct of the prior art and the silencer of FIG. 2 of the present invention are almost equal due to the same shape of the fluid flow path.

The fluid passage resistance of the silencer having the same shape as that of the silencer shown in FIG. 2 and having no partition wall 1 increases as the fluid flow path expands and contracts continuously.
/ H, a pressure loss of about 4 mmAq is obtained. However, in the case of the silencer shown in FIG. 2, only a pressure loss of 0.1 mmAq and a percentage of only 2.5% is required. Is remarkable.

The silencer of FIG. 11 of the present invention and the silence elbow of the prior art of FIG. 9 will be compared under the following conditions. (A) The sound absorbing material is a glass fiber molded plate having a thickness of 25 mm and a bulk density of 48 kg / m 3, and both entrances and exits have a rectangular cross section of 0.45 m on each side. In both cases, the outer dimensions of the outer shell are 0.75 m in length and width, the height is 0.5 m, and the fluid flow velocity is 7.5 m / s at the entrance and exit. (B) The sound-absorbing material of the conventional sound-absorbing elbow is a glass fiber molded plate having a bulk density of 32 kg / cubic m, and a thickness of 25 mm.
A glass cloth holder is used to prevent scattering on the fluid flow path side surface. (C) The material of the partition wall 1 of the silencer shown in FIG. 11 is a hard urethane having a bulk density of 35 kg / m 3 and a thickness of 5 mm.

The silencing volume of the silencing elbow according to the prior art under the above conditions is described in the literature (air conditioning and sanitary technology data book No. 2).
Edition of Techno Ryowa edition). Chart I on page 17
Use a value of -35. (A) Since the condition of the partition wall 1 of the silencer of FIG. 11 is the same as that of the partition wall 1 of the silencer of FIG. 2, it is considered that the silencing volume of the frequency from 63 Hz to 1 KHz is the same as the silencing volume of the silencing elbow of the prior art. However, the sound-absorbing elbow of the prior art has a sound-absorbing material surface that is subjected to scattering treatment with a glass cloth, and has a sound-absorbing volume value affected by the scattering treatment. (B) Since the surface of the sound absorbing material of FIG. 11 of the present invention does not have a glass cloth treatment, the effect of the glass cloth treatment is corrected from the sound attenuation of the conventional sound deadening elbow to obtain the sound attenuation of the silencer of FIG. . (C) Further, actually, the sound absorbing material 2 of the silencer shown in FIG. 11 has a surface area on the sound receiving side larger than the surface area of the sound absorbing elbow of the conventional technology on the sound receiving side, and a shape capable of expecting a resonance sound absorbing effect. It will be louder than the silence elbow of the technology,
Although it is not convenient for the evaluation of the present invention because the calculation becomes complicated, it is not included. (D) In FIG. 11, for frequencies above 2 KHz, calculation becomes complicated, which is disadvantageous in the evaluation of the present invention. However, it is assumed that the partition wall 1 has no sound transmission and the sound absorbing material does not have a sound absorbing effect. Only the silencing volume is described in the literature (Air Conditioning and Sanitary Technology Data Book 2nd Edition Techno Ryowa Ed.) Mute Use the value in Chart I-39 on page 19 to count.

(A) From the above, Table 3 shows a comparison between the silencing volume of the silencer of FIG. 11 of the present invention and the silencing volume of the silencing elbow of the prior art. The factors of the noise generated must also be considered. (B) The amount of noise generated by the conventional noise reduction elbow is described in the literature (Air Conditioning and Sanitation Technology Data Book 2nd Edition Techno Ryowa)
18 I. Table 4 shows the values of Chart I-37 on the mute page. (C) In the muffler of FIG. 11 of the present invention, since the fluid flow path having a smooth bend is constituted by the partition wall 1, there is a noise reduction effect due to the bend shape, but there is no generated noise.

[0059]

[Table 3]

[0060]

[Table 4]

(A) According to the above two tables, FIG.
It can be seen that the muffling volume of the muffler 1 is superior to the muffling volume of the muffling elbow of the prior art at a frequency of 1 KHz or less where muffling processing is difficult. (B) On the other hand, regarding the generated noise, in the A characteristic, 22.
6db, 36.2db in C characteristics, and FIG.
Silencer has won greatly. (C) Further, regarding the fluid passage resistance, the value of the resistance coefficient の of the sound-absorbing elbow of the technology is described in I.C. It is 0.8 from the chart I-36 on page 17 of the muffling,
The value of the resistance coefficient ζ of the silencer in E. Duct 9
0.22 is obtained from the chart E-8 on the page. The fluid passage resistance is 27.5% of that of the conventional silence elbow, and the silencer shown in FIG. It can be seen that the overall performance of was excellent.

A comparison will be made between the muffler shown in FIG. 21 of the present invention and the muffle chamber of the prior art under the following conditions. (A) The sound absorbing material is a glass fiber molded plate having a thickness of 50 mm and a bulk density of 32 kg / cubic m. Both entrances and exits have a rectangular cross section of 0.4 m on each side, and the positions are the same. The outer dimensions of the outer shell of the muffler of FIG.
1, the long side is 2.1 m, the short side and the height are both 1.5 m, and the outer shell dimensions of the conventional silencing chamber are the same. Further, both fluid flow rates are 3,300 m3 / h. (B) As a process for preventing the sound absorbing material from scattering in the sound deadening chamber of the prior art, the surface of the fluid flow path side is made of glass cloth. (C) The material of the partition wall 1 of the muffler shown in FIG. 21 is 5 kg of hard urethane having a bulk density of 35 kg / cubic m. (2) The material shown in FIGS. 21 and 22 is used to prevent sound from directly reaching the outlet from the inlet by using a material 6 having good sound insulation.

Under the above-mentioned conditions, the silencing volume of the muffling chamber of the prior art and the silencing volume of the silencer of FIG. 21 of the present invention are determined by the mathematical formula for calculating the silencing volume of the silencing chamber of Equation (3). (A) Since the condition of the partition wall 1 of the silencer of FIG. 21 is the same as that of the partition wall 1 of the silencer of FIG. 2, it is considered that the silencing volume of the frequency from 63 Hz to 1 KHz is the same as the silencing volume of the conventional silencing chamber. However, for frequencies above 2 KHz, the calculation is complicated, which is disadvantageous in the evaluation of the present invention. However, it is not included, and only the noise reduction effect depending on the shape is described in the literature (Air conditioning and sanitation technology data book 2nd edition Techno Ryowa edition) I. Mute 1
Figures are calculated using the values in Chart I-39 on page 9.

Table 5 is a comparison table of the silencing volume of the silencing chamber of the prior art and the silencing volume of the silencer of FIG. 21 of the present invention calculated under the above conditions.

[0065]

[Table 5]

(A) The overall muffling evaluation is 14.3 db for the A characteristic and 16.2 db for the C characteristic. The muffler of FIG. 21 of the present invention is superior. (B) Further, regarding the fluid passage resistance, the fluid passage resistance of the silencer of the prior art is about 1.99 mmAq, while the fluid passage resistance of the silencer of FIG. 21 of the present invention is 0.88.
The mmAq was 44% as a percentage, indicating that the fluid passage resistance was significantly superior.

In general, when comparing the various types of the silencers of the prior art with the muffler of the present invention, the results are inferior to those of the prior art at a frequency of 2 kHz or more. 1 also includes an element of calculation assuming that the sound transmission amount is not at this frequency. Actually, there is passage of the sound, and the passed sound is naturally silenced in the silencer, but is omitted because the calculation is complicated. Therefore, when these factors are taken into consideration, the difference in muffling volume with various mufflers of the prior art is also reduced.

Further, high-frequency noise of 2 KHz or more has a damping effect due to the normal bending of the duct system and the shape of the interrupting branch. Even if the muffler is not used, there is noise reduction due to the natural attenuation of the duct system. The noise generated by the dampers and the branch part of the system is smaller in the high frequency range than in the low frequency range.

Therefore, in the noise reduction plan of the duct system, the noise in the high frequency range is not so much a problem, and it is difficult to muffle the noise, and the countermeasure against the noise in the low frequency range, which generates a large amount of noise in the duct system, is always a problem. The excellent performance of the various types of silencers in the low frequency range has a great effect on improving the silencing function of the duct system.

In a general duct system, two silence elbows and one silence chamber of the prior art are required, but the fluid passage resistance thereof is about 10 mmAq. It accounts for about 15% of the resistance.

If the muffler of the present invention is substituted, the fluid passage resistance of the muffler is about 2.5 mmAq, the total resistance of the duct and the heat exchange coil is about 7.5 mmAq, and the duct and the heat exchange coil are about 11%. Etc. are reduced.

A main source of noise to be silenced in a general duct system is a blower which is a fluid carrier, but if the fluid carrying pressure of the blower can be reduced to 11% lower, the rotation speed of the blower is reduced by about 20%. As a result, the generated noise is reduced by 1 to 2 db, and the whole duct system is greatly improved. This is also the effect of the silencer of the present invention.

When the rotation speed of the blower is reduced by about 20%, the required power is also reduced accordingly, and it can be seen that the present invention is remarkably excellent even from the viewpoint of energy saving.

[Brief description of the drawings]

FIG. 1 is a perspective view of the appearance of a muffler.

FIG. 2 is a plan sectional view of the muffler of FIG.

FIG. 3 is a diagram of the muffler of FIG. 2 in which a shape of a sound absorbing material is changed.
The upper figure is a plan view and a plan sectional view of a part of the muffler, and the lower figure is a sectional view taken along the arrow in the upper figure.

FIG. 4 is a plan view and a plan cross-sectional view of a part of the muffler, and the lower figure is a cross-sectional view taken along the arrow in the upper figure.

FIG. 5 is a plan sectional view of the muffler of FIG. 2 in a case where the shape of a fluid flow path is changed.

FIG. 6 is a partial cross-sectional view of the silencer of FIG. 2 when the shape of the fluid flow path is changed.

FIG. 7 is a cross-sectional plan view of the muffler of FIG. 2 when the shape of the fluid flow path is changed.

FIG. 8 is a plan sectional view when the shape of the silencer of FIG. 2 is changed.

FIG. 9 is a perspective view of a conventional silencing elbow.

FIG. 10 is a perspective view of the appearance of the muffler.

11 is a plan sectional view of the muffler of FIG. 10, and the lower figure is a sectional view of the upper figure taken along an arrow.

12 is a diagram in which the shape of a sound absorbing material of the silencer of FIG. 11 is changed, wherein the upper figure is a plan view and a partial plan sectional view of the silencer, and the lower figure is a sectional view taken along the arrow in the upper figure.

FIG. 13 is a plan view and a partial plan cross-sectional view of the muffler of FIG. 11 when the shape of the muffler is changed.

FIG. 14 is a cross-sectional view of the muffler of FIG.

FIG. 15 is a cross-sectional plan view of the fluid flow path of FIGS. 11, 12 and 13 with a rectifying vane.

16 is a sectional view taken in the direction of the arrow in FIG. 15;

FIG. 17 is a plan cross-sectional view of a steep turn silencer with rectifying vanes.

18 is a sectional view taken in the direction of the arrow in FIG. 17;

FIG. 19 is a plan sectional view of a fluid flow path in which the shape of the rectifying vane in FIG. 17 is changed.

FIG. 20 is a cross-sectional plan view of the muffler.

FIG. 21 is a plan sectional view and a transverse sectional view of the silencer.

22 is a sectional view taken in the direction of the arrow in FIG. 21.

FIG. 23 is a plan cross-sectional view and a cross-sectional view of the muffler of FIG. 21 in which the shapes of the sound absorbing material and the fluid flow path are changed.

24 is a sectional view taken in the direction of the arrow in FIG.

FIG. 25 is a mounting diagram of a pressure equalizer.

FIG. 26 is a view showing a method of supporting a fluid flow path.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Partition wall 2 Sound absorbing material 3 Outer shell 4 Straightening vane 5 Sound absorption surface which performed scatter treatment 6 Sound insulation material 7 Fluid inlet 8 Fluid outlet 9 Partition plate 10 Pressure equalizer 11 Pressure equalizer fixture 12 Fluid flow path 13 Sound absorbing part 14 Fluid Channel support

Claims (5)

[Claims] 1. A silencer for an air duct, wherein the outer shell (3) is provided with a partition wall (1) made of a material having good sound permeability, and the fluid passage 12 and the silencer 13 are separated from each other. 2. The muffler for an air duct according to claim 1, wherein a part of the partition (1) separating the muffling section (13) and the fluid flow path (12) is used in combination with a material (6) having good sound insulation properties. 3. The muffler for an air duct according to claim 1, wherein a rectifying vane (4) is provided in a bent portion of the fluid flow path (12). 4. A pressure equalizer (10) is provided on a partition (1) separating the muffling section 13 and the fluid flow path 12.
And a muffler for an air duct according to claim 2. 5. A silencer for an air duct, wherein a rectifying vane (4) made of a material having good sound permeability is provided at a bent portion of the fluid flow path 12.