JP3328804B2 - Noise separation type silencer and low noise type equipment using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the reduction of noise in exhaust ducts, intake ducts, mechanical equipment, etc. used in local exhaust systems, dust collectors, exhaust gas treatment systems, air-conditioning ventilation systems, etc., in which noise and airflow are mixedly discharged. The noise reduction type silencer, which is effective in reducing the working environment noise and factory noise at factories and offices, and reducing the noise at the boundary of the premises, helps to ensure a comfortable working environment and a comfortable living environment in the neighborhood and uses it. Low-noise equipment.

[0002]

2. Description of the Related Art Reducing the operating noise of equipment in factories, offices and the like is an important issue in securing a comfortable working environment and a comfortable living environment near the factories and offices. The permissible noise levels in the working environment and living environment are as follows: Occupational Safety and Health Regulations, Noise Regulation Law, Noise Regulation Standards for Specific Factories, Noise Regulation Standards for Specific Construction Work, Environmental Standards, Environmental Standards for Aircraft Noise and Shinkansen Railways, Prefectures It is regulated or instructed by municipal ordinances by use area and by time of day.

[0003] The main characteristics of the airflow are that the airflow flows at a lower pressure and a pressure loss is caused by the resistance of the passage.
On the other hand, the main feature of noise is that it travels straight at short distances, attenuates when it hits the object surface, and its residual noise is reflected at the same angle as the incident angle. The attenuated noise energy, which is the difference between the incident noise and the residual noise reflected, is the energy that the object vibrates and absorbs and the energy that penetrates the object, and is generally referred to as transmission loss, but the silencer of the present invention utilizes the former. Since the latter is minimized, it is called collision damping silence. The effect of the collision damping and silencing is greater as the collision angle is closer to a right angle. In addition, the object vibrates due to the collision of noise, and noise (secondary noise) is generated again. By suppressing the vibration of this object, it is possible to suppress the generation of secondary noise. This is called vibration damping silencing.
Further, when the object colliding with noise is a sound absorbing material such as a fibrous or porous material, the vibration damping and silencing of the constituent fibrous or porous material object and the viscosity of the air in these minute spaces are usually used. It has a greater noise reduction effect than the collision attenuation noise reduction.
This is called sound absorption attenuation muffling. The effect of the sound absorption damping and silencing is greater as the collision angle is closer to a right angle and as the thickness is greater.

[0004] Noise is a longitudinal wave, and a phase difference occurs depending on a difference in a passing path and a distance. When noises having different phases are combined, the noise is attenuated. This is called phase difference attenuation muffling. The noise is attenuated farther from the source. This is called distance attenuation muffling. In the case of a single point sound source, the noise source proximity r
_The attenuation of the distance attenuation from ₁ m to r ₂ m is (dB) = 20 log
Approximate to r ₂ / r ₁ , most of the noise has a dominant frequency of several hundred Hz
Is a collection of many frequency bands centered on 2KHz, and low-frequency noise below several hundreds Hz is more likely to reach a distance over barriers than high-frequency noise. Is difficult, and it is easy to cause discomfort to the human body. Also, the relationship between the noise level and the sense of life makes it difficult to talk at around 70 dB, and hinders sleep at around 50 dB.

For example, the noise generated from a 1-horsepower blower is said to be 82 ± 5 dB in design. Therefore, it can be seen that a comfortable working environment and a comfortable living environment are likely to be hindered in and around a factory, business establishment, or the like where such a blower is used. For this reason, silencers have a large noise reduction effect even in the low frequency band and have a wide range of common use for noise emitted from individual exhaust ducts and intake ducts of factories, business offices, etc. and noise generated from equipment. The development of is strongly desired.

[0006] As noise silencers, there are new revisions and anti-pollution measures of the Industrial Environment Management Association of Japan, including hollow type (expansion type), sound absorbing duct type, right angle bent type, sound absorbing chamber, resonance type (side branch, Helmholtz, perforated), interference type, etc. are introduced in detail. However, none of the silencers uses a large number of the above-described silencing principles in a complex and overlapping manner, and therefore, there is no single silencer having an even silencing effect from a low frequency band to a high frequency band. For example, as typical examples, there are a muffler for a hollow duct having a neck and a volume in the duct, and a muffler for a tubular sound absorption duct in which a layer of a fibrous sound absorbing material such as a glass mat is provided in the duct. However, these silencers have the following disadvantages.

(1) The muffling effect in the general size range of the muffler for a hollow duct is as follows: muffler body diameter D ₂ / duct diameter D ₁ × 4.
There is a relationship between dB and a silencing effect of 0 at an even multiple Hz of the frequency f (= sound speed / 4 body length). Therefore, the muffler for hollow duct becomes very large with respect to the diameter of the exhaust duct, and there are some frequency bands that do not have a muffling effect. In addition, it is necessary to analyze the frequency of each noise source in advance and design a special dimension. There are drawbacks such as. (2) The muffler for a tubular sound-absorbing duct is a miniaturized silencer for a hollow duct using a sound-absorbing material. In many cases, the muffler having a length of 1 m has a noise reduction effect of 10 m at an all-pass noise level.
It is about 13 dB. The sound-absorbing material has a low noise reduction effect in the low frequency band of 250 Hz or less.
Ducts that discharge fumes, dust, and the like have drawbacks such as adsorption of these and a reduction in the noise reduction effect and an increase in pressure loss. Further, since the conventional silencer has a structure that is difficult to disassemble and disassemble, there is a disadvantage that the inside of the silencer cannot be cleaned and the sound absorbing material cannot be replaced.

(3) Since these conventional silencers for ducts do not have a function of discharging rainfall and snowfall that enters from the end of the duct, as shown in FIG. It is necessary to attach an umbrella 5 to the exhaust discharge port 4 from which the noise is muffled, and to release the rainfall snowfall 6 by directing the duct downward as shown in FIG. When the exhaust air stream collides with the umbrella 5 or the bent portion of the duct, a new noise is generated, and the exhaust air stream emitted from the end of the duct collides with the still air outside the duct to generate a new noise, so-called air flow collision noise. There is a disadvantage that the newly generated airflow collision noise and the residual noise of the silencer 7 are combined and emitted downward, increasing ground noise. In FIGS. 10 and 11, reference numeral 8 denotes residual noise and airflow collision noise.

[0009]

According to the first aspect of the present invention, the noise is separated from the airflow by utilizing the characteristics of the noise and the airflow, the airflow is discharged to an exhaust discharge port, and the noise collides many times inside the silencer. By reflecting, the sound damping principle of collision damping, vibration damping, distance damping, and phase difference damping is combined and used to muffle sound.The sound damping effect is large from low frequency band to high frequency band, and the pressure loss is small. The present invention provides a noise separating type silencer which has a wide range of application to general exhaust, mist exhaust, and clean room intake / exhaust, has a simple structure, is small and inexpensive. The invention described in claim 2 is the invention described in claim 1.
Structure to further increase the number of noise collisions
To provide a noise-separating silencer with excellent silencing effect
You. The third aspect of the present invention provides a noise separating type silencer which is excellent in the sound absorbing and attenuating effect, and furthermore excellent in the sound absorbing effect, in addition to the first and second aspects. According to a fourth aspect of the present invention, in addition to the first, second and third aspects of the present invention, a structure in which rainfall and snowfall entering from an exhaust outlet are discharged to the outside of the muffler system enables vertical exhaustion, The noise generated when the residual noise of the noise separation type silencer and the exhaust air flow collide with the umbrella at the end of the duct, the bent portion of the duct, and the still air is discharged in any direction, such as vertically above, and the distance attenuation sound is added. Provided is a noise separation type silencer that prevents an increase in noise.

According to a fifth aspect of the present invention, in addition to the fourth aspect of the present invention, a rainfall / snowfall discharge function is provided by connecting to a conventional silencer having no rainfall / snowfall discharge function.
Provide a noise separation type silencer capable of vertical exhaust. Claim 6
The described invention has a large noise reduction effect from a low frequency band to a high frequency band, a small pressure loss, a wide range of application, a simple structure, and a small and inexpensive noise separating type silencer having a structure. Provide a noise type equipment.

[0011]

SUMMARY OF THE INVENTION The present invention provides a rectangular or cylindrical outer shell having an exhaust inlet and an exhaust outlet so as to be oblique to noise and airflow entering from the exhaust inlet. In the noise separation type silencer where the noise reflector is inclined with respect to the outer shell bottom, a projection is provided on the outer shell bottom opposite to the noise reflector, and airflow passes through the upper end of the noise reflector Make a blank space, and attach a polygonal noise reflecting material from the lower end to the upper end of the inner surface of the outer shell through this blank portion, noise reflector, protrusion, polygonal noise reflecting material and A polygonal space is provided between the upper part of the inner surface of the outer shell,
Exhaust air flow is emitted to the exhaust outlet through the polygonal space as a passage, and noise is collided with the noise reflector, and the remaining noise reflected is repeatedly impact-reflected at the protrusion, polygonal noise reflector, and upper part of the outer shell, and is silenced. The present invention relates to a noise separation type silencer configured to perform the above method. The present invention also relates to a noise separator, a projection, a polygonal noise reflector, and a noise separating type silencer using a sound absorbing material on a part or the entire inner surface of an outer shell.

[0012] The present invention also relates to a noise separating type silencer comprising a rainfall / snowfall discharge port provided at a lower end of a noise reflector or a lower end of an outer shell opposed thereto. The present invention also relates to a noise separation type silencer in which a shell and a noise reflector have a divided structure that can be disassembled and assembled. In addition, the present invention relates to a noise separating type silencer which is formed by connecting the above noise separating type silencer and a noise separating type silencer having no function of discharging rainfall and snow, or by connecting and integrating both. Further, the present invention relates to a low-noise facility apparatus in which the above-mentioned noise separating type silencer is integrated with or provided inside a facility apparatus of a noise source.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a noise separating type silencer according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing the principle of silencing of a noise separating type silencer according to the present invention. FIG. 1 (a) is a sectional view and FIG. 1 (b) is a sectional view taken along line AA. In FIG. 1, the noise 2 of the noise 2 and the airflow 3 entering from the exhaust inlet 1 collides with the noise reflector 9, so that the collision attenuation and the vibration attenuation are performed.
The remaining noise 10 is reflected at an angle equal to the incident angle,
It collides with the projection 11. After that, like the noise reflection line 13,
Noise reflector 9, protrusion 11, polygonal noise reflector 12
In addition, the inner surface of the outer shell inner surface upper portion 14 is repeatedly collided and reflected, so that the collision attenuation and the vibration attenuation are performed. In addition, the phase difference between the remaining noises 10 is combined to perform the phase difference attenuation and noise reduction.

The noise reflector 9, the projection 11, the polygonal noise reflector 12, and the sound absorbing material 16 extending from the upper part 14 to the lower part of the inner surface of the outer shell are provided. Adds silencing effect. Further, the remaining noise 10 remaining up to the exhaust discharge port 4 is discharged in an arbitrary direction such as a vertical direction, and is attenuated and silenced according to the distance. On the other hand, the airflow 3 is separated from the noise 2 on the surface of the noise reflector 9,
The gas flows toward the exhaust discharge port 4 having a low atmospheric pressure and is discharged outside the muffler system. Also, rainfall and snowfall that enters from the exhaust discharge port 4 while the exhaust is stopped is collected on the upper surface of the noise reflector 9 and the outer shell 18 is collected.
Is discharged from the rainfall / snowfall discharge port 19 through the silencer. In FIG. 1, 15 is a polygonal space, 20 is an eave, and 21 is a damping material.

As described above, the noise-separating silencer according to the present invention has a single rectangular or cylindrical outer shell 18 which is capable of reducing a collision damping, a vibration damping, a phase difference damping, and a sound absorption damping. By repeating the four kinds of silencing principles, a great silencing effect is exhibited. Furthermore, the remaining noise 10 and the airflow 3 emitted from the exhaust discharge port 4 emit airflow collision noise newly generated by colliding with the umbrella at the tip of the duct, the bent portion of the duct, and the still air, in any direction such as vertical. In addition, the ground noise is prevented from increasing by utilizing the distance attenuation muffling, which is the fifth kind of silencing principle.

In the present invention, the noise reduction effect increases as the size of the muffler increases. With a muffler of the same size, the number of collisions of the noise 2 and the residual noise 10 increases, and the closer the collision angle is to a right angle, the larger the number of collisions increases. When the residual noise 10 with little noise is emitted to the exhaust emission port 4, the noise becomes small. Further, when the noise 2 and the residual noise 10 flow backward to the exhaust inlet 1, the noise load on the duct and the equipment connected to the exhaust inlet 1 increases. Therefore, the relationship between the angle and length of each position of the noise reflector 9, the angle of the protrusion 11, and the angle and distance between the polygonal noise reflector 12 and the upper portion 14 of the outer shell surface are important. The most basic angle of the rear half of the noise reflector 9 is preferably in the range of 20 to 40 degrees, and is preferably in the range of 25 to 35 from the relationship between the pressure loss of the airflow and the noise reduction effect.
A range of degrees is more preferred. Curving the tip of the noise reflector 9 is effective in preventing the generation of wind noise.

Furthermore, it is desirable that the angle of the first half of the noise reflector 9 be an angle at which the residual noise 10 does not flow back to the exhaust inlet 1. The protrusion 11 has a remarkable effect in increasing the number of collisions of the residual noise 10, preventing backflow to the exhaust inlet 1 and preventing discharge to the exhaust outlet 4. The shape of the protruding portion 11 may be any of a circular shape and a rectangular shape, and is not particularly limited. However, a rectangular shape is preferable in terms of ease of grasping a reflection angle and manufacturing. In addition, the effect of the phase difference attenuation noise reduction is as follows: wavelength λ / 2 and wavelength λ / 4.
Since up to become near the spatial distance, the reflected distance noise 2 and residual noise 10 is preferably set in consideration of this fact.

The noise separating type silencer according to the present invention comprises a polygonal space 15 formed between a noise reflector 9, a projection 11, a polygonal noise reflector 12 and an upper portion 14 of the inner surface of the outer shell.
Since various spatial distances can be set, an ideal silencing space is obtained for noise that is an aggregate of various wavelengths and frequency bands. The noise reflection line 13 is an important means for judging the number of collisions and an appropriate angle, position, distance, etc. of each of these parts.
This is a new method that cannot be found in conventional documents.

The rainfall snowfall 6 entering from the exhaust outlet 4 is
It is collected by the noise reflector 9 and discharged from the rainfall and snow discharge outlet 19. Accordingly, the umbrella or the bent portion of the duct at the end of the exhaust outlet 4 is not necessarily required, and the exhaust airflow 3 and the residual noise 10 are emitted in the vertical direction, and the distance attenuation is reduced, thereby preventing an increase in ground noise. Generally, when horizontal exhaust is changed to vertical exhaust, there is an effect of reducing noise in the horizontal direction by 10 dB. Leakage of the residual noise 10 from the rainfall / snowfall discharge port 19 corresponds to the residual noise 1
By designing the zero collision location to avoid the rainfall and snow discharge outlet 19, the level becomes negligible. If vertical exhaust is not performed, it is not always necessary to provide the rainfall and snow discharge outlet 19. When the noise reflector 9 or the outer shell 18 having a small mass is used, attaching the vibration damping material 21 has an effect of absorbing vibration and suppressing generation of secondary noise.

Here, the sound absorbing and attenuating and silencing effect increases as the sound absorbing material 16 is thicker. In addition, the larger the hole opening ratio of the punching metal 17 and the smaller the width of the bar, the greater the sound absorbing and damping effect. Since a perforated member such as the punching metal 17 has no rigidity and easily vibrates, it is preferable to reinforce it at an appropriate interval. In the present invention, the protrusion 11
May be provided in other places, or the polygonal space 15 may be finely partitioned to increase the number of collisions of the noise 2 and the residual noise 10, or the polygonal noise reflecting material 12 may be used as a layer of the sound absorbing material 16. A small hole is provided, a back space is provided between the layer of the sound absorbing material 16 and the outer shell 18, a structure for guiding the noise 2 and the residual noise 10 in the polygonal space 15 to the back space, or a sound absorbing structure. The material 16 may be used for a part or the whole inside the silencer. Further, in the present invention, the noise reflection line 1 indicating the traveling direction of the noise 2 and the residual noise 10
It is preferable that the majority of 3 does not reach the exhaust outlet 4 and the exhaust inlet 1 or the number of collision reflections until reaching the exhaust outlet 4 is 4 or more on average.

In FIG. 1, the flow velocity of the air flow 3 in the noise separation type silencer affects generation of new noise and pressure loss.
For this reason, the flow velocity of the air flow 3 is preferably 15 m / sec or less.
More preferably, it is not more than m / sec. The length of the noise reflector 9 is preferably longer than the length of the exhaust inlet 1. The noise reduction effect increases as the length of the noise reflector 9 becomes longer than the length of the exhaust inlet 1, and the pressure loss increases. Becomes Further, if the cross-sectional area of the space through which the airflow 3 passes is made larger than the cross-sectional area of the exhaust inlet 1, the pressure loss becomes smaller. Therefore, these are set according to the purpose of use. Furthermore, when the end of the silencer is formed in a flange structure or a super-numbered structure and fastened with bolts, snap locks or the like, the inside of the silencer can be cleaned and the sound absorbing material 16 can be replaced, so that the initial silencing performance can be maintained.

Next, the material of the members constituting the noise separating type silencer of the present invention will be described. Exhaust inlet 1, Exhaust outlet 4, Noise reflector 9, Punched metal 17, Outer shell 18
Select from steel plates, plated steel plates, stainless steel, aluminum alloys, reinforced plastics, wood boards, etc. Rigid walls that totally reflect noise 2 will hinder the use of collision damping and vibration damping. Damping material 2 between steel plates
1 is also effective.

The sound absorbing material 16 is made of glass fiber, rock wool, metal fiber, ceramic fiber, mica piece, organic artificial fiber, pulp, natural fiber, carbide, etc. in the form of a mat, a board, a woven fabric, a nonwoven fabric, or the like. Fix things with punching metal, wire mesh, reinforced plastic with holes, etc. These are selected in consideration of the temperature of the exhaust gas stream and the durability against the contained components. For applications that discharge paint mist, oil smoke, fumes, dust, etc., dismantling cleaning and replacement of sound absorbing materials are performed depending on the state of adsorption of these substances. For this reason, it is desirable that the silencer has a structure that can be easily disassembled and assembled. In the case of exhaust with odor, activated carbon fiber or the like can be used as a sound absorbing material and a deodorizing material.

As the damping material 21, a damping sheet or the like used for damping and noise control of automobiles and Shinkansen Nozomi can exhibit excellent effects. When they are attached to the surface of the noise reflector 9 or the outer shell 18 where the noise collides, they exert a sound absorbing function in addition to a vibration damping function. The vibration damping material 21 may be a mixture of asphalt, rubber, various synthetic resins, and the like, pulp, organic fibers,
Various fibers such as inorganic fibers and calcium carbonate, mica powder,
Mineral fillers such as fly ash, rice husk ash, and iron powder are added, kneaded and formed into a sheet. In addition, a sound insulating material obtained by adding a filler of a mineral substance to a synthetic resin such as rubber or vinyl chloride can be used.

Generally, the members constituting the noise separating type silencer have different resonance characteristics, different coincidence effects,
That is, there is a frequency band in which the noise is reduced. Considering this, when selecting the components to be configured, it is preferable to confirm the material characteristics in advance, or to complement each other by combining different components. The damping sheet or the like of the above-described vibration damping material 21 is designed to reduce the coincidence effect of various members by mixing various materials, and good vibration damping characteristics and sound absorbing characteristics can be obtained. The noise separating type silencer according to the present invention preferably has a structure in which the outer shell side surface on the polygonal noise reflecting material 12 side can move back and forth.

[0026]

Embodiments of the present invention will be described below. Embodiment 1 FIG. 2A is a cross-sectional view of a noise separating type silencer for mist exhaust according to an embodiment of the present invention, FIG. 2B is a cross-sectional view taken along the line BB, and FIG. FIG. 7 is a schematic diagram showing a flow of a noise reflection line when noise is vertically incident using the noise separation type silencers in FIGS. The noise separation type silencer shown in FIGS. 2A, 2B and 2C is a steel plate having a thickness of 1.6 mm and a width (dimension a) 200 mm × length (dimension opening) 571 mm.
A square outer shell 18 having a height (dimension c) of 440 mm is formed, and an exhaust inlet 1 and an upper end having a diameter (dimension d) of 100 mm (φ) are formed at the lower end of the square outer shell 18. The exhaust outlets 4 each having a diameter (dimension e) of 120 mm (φ) were provided. Further, a noise reflector 9 having a thickness of 1.6 mm, a steel plate having a thickness of 75 mm and a length of 350 mm, which rises obliquely at an angle of 25 degrees, is provided at a height of 80 mm from the lower end of the rectangular outer shell 18. Formed. Further, one end in the longitudinal direction of the noise reflector 9 was bent from the end to 50 mm at a radius R (dimension) of 50 mm.

The width of the noise reflector 9 is 4 mm from the top end.
An empty space of 1.5 mm is provided, and the thickness of the outer shell 18 from the lower end to the upper end is 1.
The polygonal noise reflector 12 is attached with a 6 mm steel plate, and the thickness is 1.6 mm from the upper part 14 to the lower part of the inner surface of the outer shell.
Was attached. On the other hand, a steel plate having a thickness of 1.6 mm is provided on the bottom surface of the outer shell 18 facing the noise reflector 9 and a slope of 2 mm.
7.5 degrees, top height 80 mm and bottom length 27
A 5.5 mm square protrusion 11 was provided between the exhaust inlet 1 and the lower end of the polygonal noise reflector 12. The minimum sectional area of the space through which the airflow 3 inside the obtained noise separation type silencer passed was 105% with respect to the sectional area of the exhaust gas inlet 1. In the noise separation type silencer, when the noise 2 is vertically incident, the average number of collisions among the eight representative noise incidences is 15
It was times.

Embodiment 2 FIG. 3 (a) is a cross-sectional view of a noise separating silencer for general exhaust according to another embodiment of the present invention, FIG. 3 (b) is a cross-sectional view taken along line CC of FIG. (c) is a schematic diagram showing the flow of a noise reflection line when noise is vertically incident using the noise separation type silencer in (a) and (b). A 1.6 mm thick steel plate is used on the upper surface in place of the noise reflector 9 of Example 1, and a 75 mm thick rock wool sound absorbing material 16 is fixed on the lower surface with a punching metal 17 of 8 mm in diameter and 10 pitch width. The rectangular projection 11 is made of a rock wool sound-absorbing material 16 by a punching metal 1 having a diameter of 8 mm and a pitch of 10 as described above.
7 and formed.

Further, the polygonal noise reflecting material 12 has a rising portion of the rock wool sound absorbing material 1 having a thickness of 100 mm.
6 and the upper part thereof is gradually thickened. This is fixed with a punching metal 17 having a diameter of 8 mm and a pitch of 10 and a thickness of 75 mm from the upper inner surface 14 of the outer shell to a lower part thereof. 16 is 10 with 8mm diameter
A noise separation type silencer having the same dimensions and structure as in Example 1 was obtained, except that it was fixed with a punching metal 17 having a pitch width. The minimum sectional area of the space through which the air flow 3 inside the obtained noise separation type silencer passes is 1 to the sectional area of the exhaust inlet 1.
05%. In this noise separation type silencer, noise 2
The average number of collisions out of the eight representative noise incidences when was vertically incident was 15 times.

Comparative Example 1 FIG. 9A is a cross-sectional view of a conventional noise separating silencer for mist exhaust, FIG. 9B is a cross-sectional view taken along line FF, and FIG. 9C is a cross-sectional view of FIGS. FIG. 4 is a schematic diagram showing a flow of a noise reflection line when noise is vertically incident using the noise separation type silencer in FIG. 5A, and a circular noise reflection material is used instead of the polygonal noise reflection material 12 of the first embodiment. A noise separating type silencer having the same dimensions and structure as in Example 1 was obtained except that the space 15 'was used instead of the 12' and the polygonal space 15. The minimum sectional area of the space through which the airflow 3 inside the obtained noise separation type silencer passed was 105% with respect to the sectional area of the exhaust gas inlet 1. In the noise separation type silencer, when the noise 2 was vertically incident, the average number of collisions among the eight representative noise incidences was 11 times.

Next, the noise separating type silencer obtained in Example 1 and Example 2 and the noise separating type silencer obtained in Comparative Example 1 and the silencer were 200 mm in width and 200 mm in length, and the exhaust inlet and Conventional tubular sound-absorbing silencers each having a length of 1000 mm including an exhaust / discharge port were connected to the noise / airflow generator 22 shown in FIG. 4, respectively, and the noise and the airflow were supplied to measure the exhaust sound and the pressure loss. The noise airflow generating device 22 shown in FIG. 4 is manufactured as a standard noise generating device for measuring the noise reduction performance of the silencer 7, and its specifications, measuring instruments and measurement conditions are shown below. Table 1 shows the measurement results. In FIG. 4, 23
Is a speaker, 24 is a fan, and 25 is a test silencer.

(1) Specifications of Noise Airflow Generator Noise Source: Noise Signal Generator; Rion SF-05. Pink noise. Speaker; Lion SS-02. Blower: 48m noise level at 1m of duct exit when wind speed is 10m / sec. (2) Measuring instrument Sound level meter: Precision sound level meter Lion NA-27. 1/1 octave band. Anemometer: Anemomaster. Differential pressure gauge: manometer. (3) Measurement conditions Measurement method: Noise level A measurement. Noise outlet to distance 1m. Measurement wind speed: 10 m / sec. Measurement environment: 48dB background noise, open environment outdoors.

[0033]

[Table 1]

As shown in Table 1, the noise reduction effect of the all-pass noise of the noise separating type silencer for mist exhaust of Comparative Example 1 was -9.5 dB, and-at a center frequency of 125 Hz.
4.6dB, -10.7dB at 250Hz,-at 500Hz
8.5 dB, -8.8 dB at 1 KHz, -15.8 at 2 KHz
dB, -10.7 dB at 4 KHz, -14.8 dB at 8 KHz, and a remarkable noise reduction effect was obtained at a center frequency of 250 Hz or more. Above all, the silencing effect at a center frequency of 250 Hz, 2 KHz, and 8 KHz is greater than the frequency bands before and after, and is a phenomenon that cannot be seen with a general tubular sound-absorbing duct silencer. This phenomenon is presumed to be due to the effect of the phase difference attenuation sound reduction.

On the other hand, the noise separating type silencer for mist exhaustion of Comparative Example 1 has a noise reduction type of -15.9 dB for the all-pass noise of the noise separating type silencer for exhausting mist of Example 1 having the projection. Compared to the device, it was further improved by -6.4 dB. At a center frequency of 250 Hz, -12.9 dB, and at a center frequency of 500 Hz,-
14.5dB, -17.1dB at 1KHz, -1 at 2KHz
6.9dB, -12.1dB at 4KHz, -15.
The silencing effect was improved to 0 dB, and the silencing effect was even at a center frequency of 250 Hz or more. It can be said that the reason for this is that the average number of noise collisions increased from 11 to 15 due to the provision of the projections, and the phase difference attenuation and noise reduction frequency band expanded due to the diversification of the collision reflection distance. .

Further, the all-pass noise of the noise separating silencer for general exhaust shown in Embodiment 2 in which a part of the inner surface structure of the noise separating silencer for mist exhaust is formed of rock wool sound absorbing material and punching metal. Is -22.8dB
As compared with the noise separation type silencer for exhausting the mist of the first embodiment, the noise was further improved by -6.9 dB. Center frequency 125Hz
-4.9dB, 250Hz -12.9dB, 500Hz
-18.9dB, -19.9dB at 1KHz, -23.1dB at 2KHz, -21.6dB at 4KHz, -2 at 8KHz
It was 3.2 dB, and the noise reduction effect especially at 500 Hz or more was greatly improved. This factor can be said to be the effect of rock wool, in which the sound absorption coefficient increases at 500 Hz or higher. On the other hand, the silencing effect at the center frequency of 250 Hz is -12.9 dB, which is the same value as the noise separating type silencer according to the present invention for mist. Therefore, it can be said that the noise reduction effect at the center frequency of 250 Hz is mainly an effect of increasing the average number of collisions of noise and expanding the phase difference attenuation noise reduction frequency band by diversifying the collision reflection distance mainly due to the protrusions.

The noise reduction effect of all-pass noise of the conventional tubular sound-absorbing silencer is -12.1 dB.
The noise reduction effect is smaller than that of the noise separation type muffler, and -8.8 dB at 250 Hz and -15.8 dB at 500 Hz.
It can be seen that the noise reduction effect is small at -17.1 dB at 1 KHz, -12.8 dB at 2 KHz, -10.2 dB at 4 KHz, and -8.0 dB at 8 KHz.

From the above results, the noise separating silencers for general exhaust and mist exhaust according to the present invention are both the noise separating silencer for mist exhaust of Comparative Example 1 and the conventional tubular sound absorbing silencer. It is apparent that the device has a small and epoch-making noise-reducing effect as compared with the case of FIG. In addition, it was found that the pressure loss of the noise separating type silencer according to the present invention, the noise separating type silencer of Comparative Example 1, and the pressure loss of the conventional tubular sound absorbing type silencer were 8 mmAq or less, and there was no significant difference.

Embodiment 3 FIG. 5 (a) is a cross-sectional view of a noise separating type silencer for general exhaust according to another embodiment of the present invention, FIG. 5 (b) is a cross-sectional view taken along line DD of FIG. (c) is a schematic diagram showing the flow of a noise reflection line when the noise is vertically incident using the noise separation type silencer in (a) and (b), and (d) is the noise in (a) and (b) FIG. 4E is a schematic diagram showing the flow of noise reflection lines when noise is incident at 80 degrees using the separation type silencer, and FIG. 7E shows that noise is 100 degrees using the noise separation type silencer in FIGS. It is a schematic diagram showing a flow of a noise reflection line when it is incident on a.

The noise separating type silencers shown in FIGS. 5A, 5B, 5C, 5D and 5E have a width (dimension g) of 24.
0mm x length (dimensions) 715mm x height (dimensions) 440
mm square outer shell 18 and the square outer shell 18
An exhaust inlet 1 and an exhaust outlet 4 each having a diameter (dimension) of 150 mm (φ) were provided at the upper and lower ends, respectively. Further, a steel plate having a thickness of 2.3 mm is used on the upper surface, and a rock wool sound-absorbing material 16 having a thickness of 75 mm is used on the lower surface at a height of 80 mm from the lower end of the rectangular outer shell 18, and the lower surface is made of a 8 mm diameter. 75mm wide x 400mm long fixed with 10 pitch width punching metal 17
Thus, the noise reflector 9 rising obliquely at an angle of 27.5 degrees was formed. Further, a portion of one end in the longitudinal direction of the noise reflector 9 from the end to 50 mm is R (dimension) of 50 mm.
It was curved to the curvature of.

The width of the noise reflector 9 is 10 mm from the top end.
A space of 0 mm is formed, and a rock-wool sound-absorbing material 16 having a thickness of 100 mm from the lower end to the upper end of the inner surface of the outer shell 18 on the opposite side is formed through this space,
Above that, the thickness is gradually increased, and this has a diameter of 8
The polygonal noise reflecting material 12 is fixed by fixing with a punching metal 17 having a pitch of 10 mm and a rock wool sound absorbing material 16 having a thickness of 100 mm from the upper part 14 to the lower part of the inner surface of the outer shell. It was fixed with a punching metal 17.

On the other hand, the outer shell 1 facing the noise reflector 9
8 with a slope of 27.5 degrees and a vertex height of 100 mm
Rock wool sound-absorbing material 16 formed to the size of
Is fixed by a punching metal 17 having a 10-pitch width, and a square-shaped protrusion 11 having a bottom length of 415 mm
From the lower end of the polygonal noise reflector 12. The minimum cross-sectional area of the space through which the airflow 3 inside the obtained noise separation type silencer passes is 113% of the cross-sectional area of the exhaust inlet 1.
Met. In this noise separation type silencer, the average number of collisions is eight out of eight representatives of noise incidence when noise 2 is vertically (90 degrees) incident, and eight out of eight representatives of noise incidence when incident at 80 degrees. The average number of collisions was 11 and the average number of collisions was 1 out of the eight representative noise incidences at 100 degrees.
Three times.

Next, the noise separation type silencer according to the present invention obtained above is connected to the noise airflow generator 22 shown in FIG.
The noise and air current were supplied to measure the exhaust noise and pressure loss. Table 2 shows the measurement results. The specifications and the measuring device are the same as above, and the measuring wind speed is 6 m / sec under the measuring conditions.
Same as above except for 10 m / sec, 12.5 m / sec and 15 m / sec.

[0044]

[Table 2]

As shown in Table 2, the relationship between the wind speed of the air flow and the noise reduction effect of the all-pass noise is -2 at a wind speed of 6 m / sec.
There was a great noise reduction effect of 2.9 dB, -22.8 dB at 10 m / sec, -22.6 dB at 12.5 m / sec, and -22.1 dB at 15 m / sec. The difference between the wind speed of 6 m and 12.5 m / s is small at -0.3 dB, but the difference between the wind speed of 12.5 m / s and 15 m / s is -0.5 dB. It is expected to decrease somewhat. Note that the silencing effect of −22.8 dB at a wind speed of 10 m / sec is the same as the silencing effect of the noise separation type silencer according to the present invention for general exhaust in Embodiment 2, and is silenced by silencers of different sizes. The effect has been reproduced.

The silencing effect of the frequency analysis at a wind speed of 10 m / sec is as follows: -6.8 dB at a center frequency of 125 Hz, -15.3 dB at 250 Hz, -22.8 dB at 500 Hz, and -2 at 1 KHz.
In contrast to 9.0 dB, the noise reduction effect of the noise separation type silencer for general exhaust according to the second embodiment of the present invention is -4.9 dB at 125 Hz, -12.9 dB at 250 Hz, and -18.000 at 500 Hz. It is -99.9 dB at 9 dB and 1 KHz, and it can be seen from the result that the noise reduction effect in the low frequency band of 500 Hz or less is improved. This is because the noise separation type silencer according to the third embodiment has a longer collision reflection distance of the noise and residual noise 10 than the noise separation type silencer according to the second embodiment, and it is easy to obtain a phase difference attenuation sound reduction in a low frequency band. it is conceivable that.

On the other hand, the relationship between the wind speed of the air flow and the pressure loss is 1.5 mmAq at a wind speed of 6 m / sec and 3.5 mmA at 10 m / sec.
q, it is 7.0 mmAq at 12.5 m / sec and 9.0 mmAq at 15 m / sec, and the pressure loss tends to increase temporarily when the wind speed becomes 12.5 m / sec or more. However, the general right angle duct 1
Small enough to correspond to individual pressure loss. Therefore, the noise separating type silencer according to the present invention proves to have a large silencing effect over a wide frequency band from a low frequency band to a high frequency band, and to have a low pressure loss.

Embodiment 4 FIG. 6 is a sectional view of a two-stage noise separation type silencer for general exhaust according to another embodiment of the present invention. More specifically, the general exhaust system according to the third embodiment of the present invention shown in FIG. 5 is provided on the noise separating type silencer for general exhaust system according to the second embodiment of the present invention shown in FIG. This is a two-stage noise separation type silencer with an effective length of 880 mm, which is directly connected to a noise separation type silencer for use. The two-stage noise separation type silencer was connected to the noise airflow generator 22 shown in FIG. 4, and the noise and the airflow were supplied to measure the exhaust sound and the pressure loss. Table 3 shows the results. For reference, the silencing effect of the third embodiment will be summarized. The specifications, measuring instrument and measurement conditions are the same as described above.

[0049]

[Table 3]

As shown in Table 3, the noise reduction effect of the all-pass noise of the noise separating type silencer of the fourth embodiment is as follows.
In the case of m / sec, a large noise reduction effect of -28.1 dB was obtained.
A comparison of the noise reduction effect of the noise separation type silencer of the fourth embodiment and the noise separation type silencer of the third embodiment is as follows. That is, in the noise reduction effect of the all-pass noise, the noise separation type silencer of the fourth embodiment is improved by -5.2 dB, and the frequency analysis is naturally significantly improved. Among them, center frequency 12
At 5 Hz, it is improved by -5.4 dB, and the muffling effect at that time is -1.
Reaching 3.1 dB and reaching -4.5 dB at 63 Hz is a noteworthy effect. When the exhaust outlet of the general-purpose noise separating silencer of the second embodiment is directly connected to the exhaust inlet of the general exhaust noise separating silencer of the third embodiment, the inflowing airflow and residual noise are rectified. If rectification is carried out using, further silencing effect and lower pressure loss can be expected. Also, it goes without saying that in the practical use of the two-stage type, it will be manufactured with an integral structure.

Embodiment 5 FIG. 7A is a cross-sectional view of a general-purpose exhaust noise separation type silencer according to another embodiment of the present invention, FIG. 7B is a cross-sectional view taken along line EE of FIG. (c) is a schematic diagram showing the flow of a noise reflection line when noise is vertically incident using the noise separation type silencer in (a) and (b).

[0052] Figure 7 of (a), noise separator silencer as shown in (b) and (c), width (dimension Le) 5 0 0 mm × length (dimension wo) 938mm × height (dimension Wa) 800 mm And an exhaust inlet 1 and an exhaust outlet 4 each having a size (dimensions) of 350 mm in width × 350 mm in depth are provided at the upper and lower ends of the rectangular outer shell 18. Was. Further, a steel plate having a thickness of 2.3 mm is used on the upper surface and a rock wool sound-absorbing material 16 having a thickness of 75 mm is formed on a lower surface of the rectangular outer shell 18 at a height of 100 mm from the lower end thereof. Fixed with a 10 pitch width punching metal 17, width 100mm x length 500mm
Thus, the noise reflector 9 rising obliquely at an angle of 27.5 degrees was formed. Further, one end of the noise reflector 9 in the longitudinal direction from the end to 50 mm from the end was curved to a curvature of R (dimension) 50 mm.

The noise reflector 9 has a width of 22 from the upper end.
An empty space of 8 mm is formed, and from the lower end to the upper end of the inner surface of the outer shell 18 on the opposite side through this empty space, a rock wool sound-absorbing material 16 having a thickness of a rising portion of 120 mm is formed.
Above that, the thickness is gradually increased, and this has a diameter of 8
Fix with a punching metal 17 of 10 pitch width in mm,
A polygonal noise reflecting material 12 was attached, and a rock wool sound absorbing material 16 having a thickness of 100 mm extending from the upper portion 14 to the lower portion of the inner surface of the outer shell was fixed with a punching metal 17 having a diameter of 8 mm and a pitch of 10 pitches.

On the other hand, the outer shell 1 facing the noise reflector 9
8 with a slope of 37.5 degrees and a peak height of 150 mm
Rock wool sound-absorbing material 16 formed to the size of
And a rectangular projection 11 having a bottom surface of 424.6 mm was provided between the exhaust inlet 1 and the lower end of the polygonal noise reflector 12 with a 10 pitch width punching metal 17. The minimum sectional area of the space through which the air flow 3 inside the obtained noise separation type silencer passes is 1 to the sectional area of the exhaust inlet 1.
05%. In this noise separation type silencer, noise 2
The average number of collisions out of the eight representative noise incidences when the light was vertically incident was six.

Since the noise separating type silencer obtained above is used in a direct connection type with a fan, the emission direction of the noise 2 from the fan is deflected, which may affect the average number of collisions of the noise 2. . Therefore, the exhaust inlet 1 of the noise separation type silencer
Grid-shaped current plate 2 with a length of 100 mm and a thickness of 2.3 mm
6 were provided. Also, the steel plate in contact with the starting point of the inclined portion of the noise reflector 9 and the perforated metal 17, the rock wool sound absorbing material 16 and the outer shell 18 inside the noise reflector 9 have a height of 20 mm throughout the width of the noise separating type silencer. An outlet 19 for rainfall and snowfall is provided and a width of 15 mm and an angle of 30 mm are provided at the top of the inner surface of the outer shell.
A degree of eaves 20 is provided to prevent raindrops etc. from being transmitted to the inner surface of the outer shell and falling. In addition, a flange structure that can open and close the inner surface of the outer shell and one surface of the outer shell 18 is provided so that the interior of the noise separating type silencer can be cleaned and the sound absorbing material 16 can be replaced.

Next, the noise separating type silencer for general exhaust obtained according to the present invention obtained above is connected to the noise airflow generator 2 shown in FIG.
2 and the noise and the air current were supplied to measure the emission noise.
Table 4 shows the measurement results. FIG. 8A shows the exhaust noise of the fan having an exhaust capacity of 70 m ³ / min. The connection direction of the noise separation type silencer is parallel to the longitudinal direction of the fan, and FIG.
The emission sound was measured while changing the direction (b) in the right angle direction and (c) in the extension direction. Table 5 shows the measurement results. The specifications, measuring instrument and measurement conditions are the same as described above.

[0057]

[Table 4]

[0058]

[Table 5]

As shown in Table 4, when the noise separating type silencer for general exhaust according to the present invention was measured by a noise airflow generator, the all-pass silencing effect was -23.5 dB, and the exhaust capacity shown in Table 5 was 70 m. The all-pass silencing effect when directly connected to the ³ / min fan is -24.0 dB when the noise separation type silencer is installed parallel to the longitudinal direction of the fan, and in the direction perpendicular to the longitudinal direction of the fan. -2 if installed
3.2 dB and -23.1 dB when the fan is installed in the extension direction with respect to the longitudinal direction of the fan, which are not much different from each other. The difference between the installation direction of the noise separation type silencer and the noise reduction effect with respect to the longitudinal direction of the fan is as small as 0.9 dB. This is considered to be due to the large noise reduction effect of the noise separation type silencer according to the present invention, and the effect of providing a flow straightening plate at the exhaust gas inlet of the noise separation type silencer and rectifying the noise entry direction.

In the frequency analysis, the center frequency is 250 Hz.
From -21.2 dB to -23.6 dB, it can be said that this is a noteworthy silencing effect. This silencing effect is a value that greatly exceeds −15.3 dB when the wind speed is 10 m / sec in the third embodiment.
The main reason was that the reflection distance of the noise in the silencer was larger than that of the third embodiment despite the fact that the average number of collisions was as small as 6, and the phase difference attenuation sound reduction distance suitable for the wavelength of the center frequency of 250 Hz was obtained. Conceivable. As described above, the silencing at the center frequency of 250 Hz is a low frequency band in which silencing is difficult with the conventional silencer for a tubular sound-absorbing duct, and is a great feature of the silencing effect of the noise separating silencer of the present invention. is there. The leakage noise at a distance of 1 m from the outlet for rainfall and snowfall is 50.9 dB, which is a negligible level when the background noise is 48 dB.

[0061]

According to the first aspect of the present invention, the noise separating type silencer uses the three types of silencing principle of collision damping, vibration damping, and phase difference damping, and has a large all-pass damping effect. In addition, the sound absorption effect is large in the high frequency band as well as in the low frequency band such as the center frequency 250Hz, 125Hz, etc., which is difficult to muffle with the conventional tubular sound absorbing silencer, etc., the pressure loss is small, and it is used for general exhaust and mist exhaust. It can be used for a wide range of applications, including clean air intake / exhaust systems that do not like the incorporation of dust from materials, has a simple structure, is small, and can be manufactured at low cost. The noise separating type silencer according to claim 2 has the same effect as the noise separating type silencer according to claim 1, and further utilizes the fourth type of sound absorbing principle, namely, the sound absorption attenuation and noise reduction, so that the noise having a center frequency of 500 Hz or more is obtained. Is more excellent in noise reduction effect. The noise separating type silencer according to the third aspect has the effects of the noise separating type silencer according to the first and second aspects, and furthermore, since the rainfall and snowfall can be discharged out of the system, the exhaust and the residual noise can be removed in any direction such as vertical. And the combined use of the fifth type of silencing principle, distance attenuation silencing, is effective in significantly reducing ground noise and the like.

The noise separating type silencer according to the fourth aspect has the effects of the noise separating type silencer according to the first, second and third aspects,
In addition, the structure enables disassembly and assembly, so that dust and mist adhering to the noise separation type silencer can be cleaned and the sound absorbing material can be replaced, preventing a reduction in noise reduction performance and an increase in pressure loss, and improving initial performance. Can be maintained. The noise separating type silencer according to the fifth aspect has the effects of the noise separating type silencer according to the first, second, third and fourth aspects, and further uses a conventional silencer having no function of discharging rainfall and snowfall. Can be used. The low-noise type equipment device according to claim 6 has a large noise-reducing effect from a low frequency band to a high frequency band, has a small pressure loss, and can be used in a clean room or the like in which mist and dust of a sound absorbing material are not mixed. This is a low-noise facility device having a wide, simple structure, and a small and inexpensive noise / air separation type silencer.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of silencing of a noise separation type silencer according to the present invention;
(A) is a sectional view and (b) is a sectional view taken along line AA.

2A is a sectional view of a noise separating type silencer for exhausting mist according to an embodiment of the present invention, FIG. 2B is a sectional view taken along line BB, and FIG. 2C is a sectional view of FIGS. It is the schematic which shows the flow of the noise reflection line when noise is perpendicularly incident using the noise separation type silencer in b).

FIG. 3A is a cross-sectional view of a noise separating silencer for general exhaust according to another embodiment of the present invention, FIG. 3B is a cross-sectional view taken along line CC, and FIG. 3C is a cross-sectional view of FIG. It is the schematic which shows the flow of the noise reflection line when noise is perpendicularly incident using the noise separation type silencer in (b).

FIG. 4 is a front view showing a noise airflow generation device for measuring a noise reduction performance of the noise separation type noise reduction device.

FIG. 5A is a cross-sectional view of a general exhaust noise separation type silencer according to another embodiment of the present invention, and FIG.
(C) is a schematic diagram showing the flow of a noise reflection line when noise is vertically incident using the noise separating type silencer in (a) and (b), and (d) is (a) and (a). (B) is a schematic diagram showing the flow of a noise reflection line when noise is incident at 80 degrees using the noise separation type silencer in (b), and (e) uses the noise separation type muffler in (a) and (b). FIG. 5 is a schematic diagram showing a flow of a noise reflection line when noise enters at 100 degrees.

FIG. 6 is a cross-sectional view of a two-stage noise separation type silencer for general exhaust according to another embodiment of the present invention.

7A is a cross-sectional view of a noise separating type silencer for general exhaust according to another embodiment of the present invention, FIG. 7B is a cross-sectional view taken along the line EE, and FIG. It is the schematic which shows the flow of the noise reflection line when noise is perpendicularly incident using the noise separation type silencer in (b).

8A is a front view in which the noise separation type silencer for general exhaust shown in FIGS. 7A, 7B and 7C is installed in a direction parallel to the longitudinal direction of the fan; FIG. (b) is a front view installed in a right angle direction, and (c) is a front view installed in an extension direction.

9A is a cross-sectional view of a conventional noise separating silencer for mist exhaust, FIG. 9B is a cross-sectional view taken along line FF, and FIG. 9C is a noise separating silencer in FIGS. It is the schematic which shows the flow of the noise reflection line when noise is perpendicularly incident using the device.

FIG. 10 shows a conventional sound absorber for a sound-absorbing duct with an umbrella.

FIG. 11 shows a conventional sound-absorbing silencer in which the tip of a conventional duct is bent downward.

[Explanation of symbols]

Reference Signs List 1 exhaust inlet 2 noise 3 airflow 4 exhaust outlet 5 umbrella 6 rainfall snowfall 7 silencer 8 residual noise, airflow collision noise 9 noise reflector 10 residual noise 11 protrusion 12 polygonal noise reflector, 12 'circular shape Noise reflection material 13 Noise reflection line 14 Upper part of inner surface of outer shell 15 Polygonal space, 15 'space 16 Sound absorbing material 17 Punched metal 18 Outer shell 19 Rainfall and snowfall outlet 20 Eave 21 Damping material 22 Noise airflow generator 23 Speaker 24 Fan 25 Test silencer 26 Commutator plate 27 Inspection door

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F24F 13/02 G10K 11/16 F01N 1/08

Claims (6)

(57) [Claims] 1. A noise and airflow separation type silencer, wherein a noise reflector is provided in a square or cylindrical outer shell having an exhaust inlet and an exhaust outlet at an angle to noise and airflow. One or more protrusions are provided on the outer shell facing the reflector, and there are various spatial distances between the noise reflector, the protrusions, and the inner surface of the outer shell
Polygonal space provided that the airflow is discharged to the exhaust outlet of said polygonal space as a passage, noise is collided with the noise reflector
After being separated from the airflow , the projections , the noise reflector , and the inner surface of the outer shell are repeatedly impact-reflected to increase the number of noise collisions.
Collision damping, vibration damping, distance damping, phase difference
Improve the sound-muffling effect by using the sound-reduction principle of damping sound muffled
From a low frequency band in a polygonal space with various spatial distances
A noise separation type silencer that attenuates phase difference attenuation up to the high frequency band . 2. The polygonal space is finely partitioned to prevent noise.
The noise component according to claim 1, wherein the number of times of collision is further increased.
Release silencer. 3. A noise reflector, a projection, an inner surface of a shell, and a polygon.
The noise separating type silencer according to claim 1 or 2 , wherein a sound absorbing material is used for a part or the whole of the partition of the space . 4. A rainfall / snowfall discharge port is provided at a lower end of a noise reflector or a lower end of an outer shell opposed thereto.
Or the noise separation type silencer according to 3 . 5. A noise separating type silencer according to claim 4, wherein the noise separating type silencer is connected to a silencer having no function of discharging rain and snow, or both are connected and integrated. 6. A low noise type equipment comprising the noise separation type muffler according to claim 1, 2, 3, 4 or 5 integrated with or provided inside a noise source equipment.