JPH11247646A - Silencer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise generated by air to be delivered, with a good efficiency. SOLUTION: Air delivered from an adsorption system is led into an inner cylinder 102, the air flows out from a slit 104, and the air is passed a noise eliminating material 106 while rounding about an outer peripheral surface of the slit 104. The air if led to a hole part 108 formed on an opposite side of the slit 104, and is guided to a main cylinder 22 bypassing a communicating port 26. The air is passed a first noise eliminating material 20 while rounding about an outer peripheral surface of a core body 18, and is delivered to the atmosphere from a delivery port 28 formed on the main cylinder 22. The air is bypassed to the outer peripheral surface of the core body 18, a distance where the air is passed on the first noise eliminating material 20 is gained, respective air passed while rounding about in the vicinity of the delivery port 28 are interfered with each other, energy is reduced, and thereby, a noise eliminating effect is improved. A present noise eliminator 100 is just only mounted on a case 24, and thereby, a noise eliminating effect is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer for reducing noise due to shock waves generated by air discharged from an adsorption device or the like.

[0002]

2. Description of the Related Art In a suction device 10 shown in FIG. 12, compressed air is introduced by a hose 13 connected to a suction port 11, a suction force is generated at a suction port 12, and air is discharged from an exhaust port 14. Has become. At this time, noise is generated at the exhaust port 14 because the air is rapidly released to the atmosphere. Therefore, a silencer 100 is attached to the exhaust port 14 for the purpose of reducing noise. As shown in FIGS. 13 and 14, the silencer 100
2 is discharged from a slit 104 provided in the inner cylinder 102, passes through a silencer 106 covering the outer peripheral surface of the inner cylinder 102, and passes through a hole 108 provided on the opposite side of the slit 104. The noise can be reduced from about 104 dB to 74 dB by being discharged.

However, the noise should be as small as possible. However, simply increasing the size of the silencer 100 to increase the distance that the air comes into contact with the silencing material 106 in order to enhance the noise reduction effect will cause the suction generated at the suction port 12 by air resistance. The power drops. For this reason, the current silencer 100 has a limit of reducing noise to about 74 dB.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a silencer capable of efficiently reducing noise generated by exhausted air in consideration of the above fact.

[0005]

According to the first aspect of the present invention, the outer peripheral surface of the columnar core is covered with the first sound absorbing material,
The first silencer is housed in the main cylinder to close the main cylinder. A case capable of accommodating an existing silencer is provided on the outer peripheral surface of the main cylinder, and a communication port is formed between the case and the main cylinder. The air discharged from the hole of the outer cylinder of the muffler flows into the first muffler through the communication port. In addition, a discharge port is formed in the main cylinder at a position facing the communication port, and discharges air that has passed through the first silencer.

As described above, according to the first aspect of the present invention, the muffling effect can be improved only by attaching the existing muffler to the case.

[0007] Here, air is introduced into the inner cylinder of the silencer,
The flow of the air from the outlet to the outlet will be described.

When air is introduced into the inner cylinder through a discharge port of the suction device, the air flows through the slit to the hole formed on the opposite side of the slit while passing around the outer peripheral surface of the inner cylinder. At this time, the air is absorbed by the sound absorbing material covering the outer peripheral surface of the inner cylinder, and is guided from the hole to the main cylinder through the communication port.

[0009] The air guided to the main cylinder passes through the first silencer while passing around the outer peripheral surface of the core body, is absorbed, and is discharged to the atmosphere from the outlet of the main cylinder.

As described above, the air is turned to the outer peripheral surface of the core body to increase the passage distance in the first sound deadening material, and the air sneaking around the discharge port interferes with each other to reduce the energy, thereby reducing the noise. Is improved.

According to the second aspect of the present invention, the outer peripheral surface of the columnar core is covered with the first silencer, and the first silencer is housed in the main cylinder to close the main cylinder. The main cylinder and the hole of the outer cylinder are connected by a connecting means, and an opening is formed in the main cylinder on the side connected to the outer cylinder. The air discharged from the hole of the outer cylinder of the silencer flows into the first silencer through the opening. In addition, a discharge port is formed in the main cylinder at a position facing the opening, and discharges air that has passed through the first silencer.

As described above, according to the second aspect of the present invention, the silencing effect can be improved only by connecting the main cylinder to the conventional silencer via the coupling means, and the outer cylinder and the main cylinder are directly connected. Therefore, the silencer can be made more compact.

According to the third aspect of the present invention, the outer peripheral surface of the cylinder in which the slit is formed along the longitudinal direction is covered with the first silencer, and the first silencer is housed in the middle cylinder.
This middle cylinder is arranged on a concentric circle of the inner cylinder, and a slit formed in the longitudinal direction is provided in the middle cylinder on the opposite side to the slit formed in the inner cylinder. The outer peripheral surface of the middle cylinder is covered with a second silencing material, and the second silencing material is housed in the outer cylinder to close the outer cylinder. The outer cylinder is arranged on a concentric circle of the inner cylinder, and a discharge port is formed on the side opposite to the slit formed in the middle cylinder.

Here, the flow of air from when air is introduced into the inner cylinder of the silencer to when it is discharged from the discharge port will be described.

When air is introduced into the inner cylinder from the discharge port of the adsorption device, the air flows toward the slit provided in the middle cylinder while passing around the outer peripheral surface of the inner cylinder through the slit. Furthermore, it goes to the discharge port while wrapping around the outer peripheral surface of the middle cylinder through this slit. At this time, the air is absorbed by the first and second silencers covering the outer peripheral surfaces of the inner cylinder and the middle cylinder, and is discharged to the atmosphere from the outlet of the outer cylinder.

As described above, the air is detoured many times to increase the passage distance through the sound deadening material, and the air sneaking around the slit and the discharge port interferes to reduce the energy, thereby improving the sound deadening effect. .

According to the fourth aspect of the present invention, the outer peripheral surface of the inner cylinder is covered with a muffler, and the muffler is inserted into the outer cylinder to close the outer cylinder. An annular silencing chamber is formed inside the outer cylinder between the outer cylinder and the outer periphery of the inner cylinder, and at least one partition wall that partitions the silencing chamber is provided. In addition, the muffling room partitioned by the partition wall is further divided by a partition wall. Further, a slit is formed in the inner cylinder along the longitudinal direction, and the air flows into one of the muffling chambers divided by the partition. A notch is formed in this partition, and air flowing out of the slit and bypassing the outer peripheral portion of the inner cylinder is introduced into the other muffling chamber divided by the partition.
Further, a discharge port is formed in the outer cylinder, and discharges air flowing out of the notch and bypassing the outer peripheral portion of the inner cylinder.

Here, the flow of air from when air is introduced into the inner cylinder of the silencer to when it is discharged from the discharge port will be described.

When air is introduced into the inner cylinder from the discharge port of the adsorption device or the like, the air flowing out of the slit is introduced into one of the muffling chambers and goes around the outer peripheral surface of the inner cylinder toward the notch formed in the partition. . The air is introduced into the other muffling chamber through the notch, and goes around the outer peripheral surface of the inner cylinder toward the discharge port formed on the opposite side of the notch. At this time, the air
The sound is absorbed by the silencing material that covers the outer peripheral surface of the inner cylinder, and is discharged to the atmosphere from the outlet of the outer cylinder.

For this reason, a plurality of sound deadening chambers are provided and air is diverted in the radial direction and the axial direction of the inner cylinder, thereby increasing the passage distance of the sound deadening material. The noise reduction effect is improved by reducing the energy by causing interference. Furthermore, for convenience of explanation, when one muffling room is a first muffling room and the other muffling room is a second muffling room, the first muffling room and the second muffling room can be detached as one unit. By doing so, the muffling function can be adjusted according to the sound pressure level.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIGS. 1 to 3, a silencer 16 according to a first embodiment has a bottomed and tubular case 24 in which an existing silencer 100 can be stored.

The case 24 is provided on the outer peripheral surface of a cylindrical main cylinder 22 whose both ends are closed by a wall 22A, and a communication port 26 is formed between the case 24 and the main cylinder 22. I have. The hole 10 of the silencer 100 is
Air flowing out of the pipe 8 is introduced into the main cylinder 22.

The main cylinder 22 is filled with a first silencing material 20 formed into a cylindrical shape. This first silencer 20
Is made of a material having a sound deadening effect, such as a felt or a sponge. Further, a core 18 having the same length as the first silencer 20 is inserted into the core of the first silencer 20, and the core is in close contact with the core 18. A plurality of rectangular discharge ports 2 are provided on the outer peripheral surface of the main cylinder 22 at a position facing the communication port 26.
8 are formed at regular intervals in the longitudinal direction.

Note that the shape of the silencer 16 is not limited to a cylindrical body as long as the silencer 100 can be accommodated, and the shape of the discharge port 28 is not limited to a rectangle.

Here, the silencer 1 mounted on the case 24
00 will be described. As shown in FIGS.
The outer cylinder 112 of the silencer 100 is a cylindrical body whose both ends are closed by a wall 112A, and a hole 108 is formed on the outer peripheral surface. The hole 108 has a rectangular shape and a plurality of holes 108 are provided. The outer cylinder 112 is filled with a silencing material 106 formed into a cylindrical shape. This silencer 106
It is made of a material having a sound-deadening effect, such as felt and sponge. Furthermore, the inner cylinder 10
2 are closely inserted.

A slit 104 is formed in the inner cylinder 102 in the longitudinal direction, and a male screw portion 102A is provided at an end. As shown in FIG. 13, the male screw portion 102 </ b> A is formed with the female screw portion 1 formed in the discharge port 14 of the suction device 10.
4A can be screwed.

On the other hand, the suction device 11 is provided with a suction port 11 at a position facing the discharge port 14.
To connect with the air compressor to introduce compressed air into the adsorption device 10. A suction port 15 is formed on a side surface of the discharge port 14. The suction port 15 is open to the atmosphere. By introducing and discharging compressed air into the suction device 10, a vortex is generated, the air is sucked, and a suction force is generated.

Next, the operation of the silencer 16 according to the first embodiment in which the silencer 100 is mounted will be described.

As shown in FIGS. 3A and 3B, the air discharged from the suction device 10 is introduced into the inner cylinder 102, flows out of the slit 104, and separates around the outer peripheral surface of the slit 104 in two turns. It passes through the silencer 106.
Then, the air goes to the hole 108 formed on the opposite side of the slit 104. The air flowing out of the hole 108 is
It is guided to the main cylinder 22 through the communication port 26. The air guided to the main cylinder 22 passes through the first silencer 20 while being separated and wrapped around the outer peripheral surface of the core body 18, and is discharged to the atmosphere from an outlet 28 formed in the main cylinder 22.

As described above, the air is diverted to the outer peripheral surface of the core member 18 to increase the passage distance in the first noise reduction member 20, and the air flowing around the discharge port 28 interferes with each other to reduce energy. As a result, the silencing effect is improved. Further, the noise reduction effect can be improved only by attaching the existing silencer 100 to the case 24.

FIG. 3B does not show the first silencer 20 and the silencer 106 in order to clearly express the flow of air.

Next, a silencer 32 according to a second embodiment will be described. As shown in FIGS. 4 and 5, the silencer 32 according to the second embodiment is basically the same as the silencer 16 according to the first embodiment, and therefore only different parts will be described. The silencer 32 can be connected to a silencer 110 having a box-shaped outer shape. The silencer 110 has a bottom, and includes an outer cylinder 42 having a tenon 42A extending along the longitudinal direction at both outer ends of the side surface. The outer cylinder 42 has a silencer 3
The two main cylinders 36 are connected.

The main cylinder 36 is a rectangular cylinder whose both ends are closed by a wall 36B, and an opening 40 is provided on a side surface. Further, the main cylinder 36 is filled with a first silencing material 34 formed into a rectangular cylindrical shape. Further, a tenon 36A extends in the longitudinal direction inside the opening edge of the opening 40, and can be connected to a tenon 42A extending to the outer cylinder 42.

As described above, the silencing effect can be enhanced only by connecting the main cylinder 36 to the silencer 110, and the silencer 32 can be made compact because the outer cylinder 42 and the main cylinder 36 are directly connected. be able to.

The silencer 114, the hole 38, the core 3
3. The silencing function of the first silencing material 34 and the outlet 44
The description is omitted because it is almost the same as the form. Further, the shape of the silencer 32 is not limited to a prism, and the shape is not specified as long as the silencer 32 can be connected to the silencer 110.

Next, a silencer 46 according to a third embodiment will be described. As shown in FIGS. 6 and 7, the silencer 4
6 has a cylindrical outer cylinder 64 with a bottom. Outer cylinder 64
A plurality of rectangular discharge ports 66 are formed at regular intervals in the longitudinal direction on the outer peripheral surface of the. The outer cylinder 64 is filled with a second silencing material 62 formed in a cylindrical shape. The second silencing member 62 is composed of three layers, a felt and a sponge, and sandwiches the sponge between the felts. Also, inside the second silencer 62, a middle cylinder 58 of the same length as the second silencer 62 is inserted on the concentric circle of the outer cylinder 64,
It is in close contact with the silencer 62.

The middle cylinder 58 is provided with a slit 60 along the longitudinal direction at a position opposite to the discharge port 66 formed in the outer cylinder 64. The middle cylinder 58 is filled with a first muffler 54 formed into a cylindrical shape. The first silencer 54 is formed of felt, and an inner cylinder 50 is inserted inside the first silencer 54 on a concentric circle of the middle cylinder 58 in close contact with the first silencer 54.

A slit 52 is formed in the inner cylinder 50 along the longitudinal direction, and is located at a position opposite to the slit 60 formed in the middle cylinder 58. A male screw portion 50A is formed at an end of the inner cylinder 50.

The first silencer 54 and the second silencer 62
May be any material having a silencing effect, and the following various combinations are conceivable.

For example, the second sound deadening material 62 is formed by winding a double felt around the outside of PVF (porous material), the first sound deadening material 54 is made of felt, and the first sound deadening material 54 is made of PVD.
F, the first silencing material 54 is made of PVF, and the second silencing material 62 is formed by winding a double felt around the sponge.

Next, the operation of the silencer 46 according to the third embodiment will be described. As shown in FIGS. 7 (A) and 7 (B), the male screw portion 50A provided on the inner cylinder 50 is screwed into the female screw portion 14A provided on the discharge port 14 of the suction device 10 (see FIG. 1), so that a silencer is provided. 46 is connected. The air introduced from the outlet 14 into the inner cylinder 50 flows out of the slit 52 of the inner cylinder 50, passes through the first silencer 54 while wrapping around the outer peripheral surface of the slit 52 in two hands, and 50
Out of the slit 52 of the middle cylinder 58 formed on the opposite side of the slit 52 of FIG. The air that has flowed out passes through the second silencer 62 while splitting around the outer peripheral surface of the slit 52 in two hands, and passes through the outlet 6 formed in the main cylinder 64.
6 to the atmosphere.

As described above, the air is diverted many times to increase the distance of passage through the silencers 54 and 62, and the air that has flowed around the slit 60 and the discharge port 66 interferes to reduce energy. The silencing effect is improved.

FIG. 7B does not show the first silencer 54 and the second silencer 62 in order to clearly express the flow of air.

Next, a silencer 68 according to a fourth embodiment will be described. As shown in FIG. 8 and FIG.
8 is provided with a bottomed and cylindrical outer cylinder 76. The outer cylinder 76 is filled with a silencing material 74 formed into a cylindrical shape.
The sound deadening material 74 is formed of a material having a sound deadening effect, such as a felt or a sponge. The inner cylinder 70 is inserted into the core of the silencer 74 in close contact with the core. Also,
An annular partition wall 80 is formed inside the outer cylinder 76, and partitions an annular muffling chamber 78 formed between the outer cylinder 76 and the outer peripheral portion of the inner cylinder 70. A partition 82 is formed in the noise reduction chamber 78, and the noise reduction chamber 78 is divided into a first noise reduction chamber 84 and a second noise reduction chamber 8.
Divide into six.

In the inner cylinder 70, a slit 72 for allowing air to flow into the first silencing chamber 84 is formed along the longitudinal direction. The partition 82 has a cutout 88 for introducing air from the first silencing chamber 84 to the second silencing chamber 86.
Further, on the outer peripheral surface of the outer cylinder 76, a discharge port 90 for discharging air from the second silencing chamber 86 is provided. In this outlet 90, a plurality of rectangles are formed at regular intervals in the longitudinal direction.

The shape of the silencer 46 is not limited to a cylindrical body and may satisfy the above-mentioned effects, and the shape of the discharge port 66 is not limited to a rectangle.

Next, the operation of the silencer 68 according to the fourth embodiment will be described. FIG. 9 (A) (B) (C) (D) (E)
As shown in FIG. 5, a male thread portion 70A provided in the inner cylinder 70 is screwed into a female thread portion 14A provided in the discharge port 14 of the suction device 10 (see FIG. 1), and the silencer 68 is connected to the suction device 10. . The air introduced into the inner cylinder 70 from the outlet 14 flows out of each of the slits 72 arranged at intervals in the longitudinal direction of the inner cylinder 70, and the first muffler 78 in which the muffling chamber 78 is separated by the partition wall 82. Introduced into the muffling room 84,
While going around the outer peripheral surface of the inner cylinder 70 in two hands, it goes to the notch 88 formed on the opposite side to the slit 72.

Further, the air is introduced into the other second sound deadening chamber 86 through the notch 88, and heads toward the discharge port 90 formed on the opposite side to the notch 88 while going around the outer peripheral surface of the inner cylinder 70 in two steps. At this time, the air is absorbed by the sound deadening material 74 covering the outer peripheral surface of the inner cylinder 70, and the air is discharged from the outlet 9 of the outer cylinder 76.
Emitted from 0 to the atmosphere.

As described above, by dividing the air flowing in the axial direction in the inner cylinder 70 into two, energy can be dispersed. In addition, the air is diverted in the radial direction and the axial direction of the inner cylinder 70, so that the passage distance through the sound deadening material 74 is increased, and further, the air that has flowed around the notch 88 and the discharge port 90 interferes to reduce energy. By doing so, the silencing effect is improved.

Further, in this embodiment, the outer cylinder 76 is partitioned by the partition wall 80 and two muffling chambers 78 are formed.
One unit may be connected in the axial direction by providing a joint that allows the ends of the inner cylinder 70 to communicate with each other, and by providing a screw portion on the outer peripheral surface of the unit. Thus, the number of muffling chambers can be easily increased or decreased, and the muffling function can be adjusted according to the sound pressure level.

In FIG. 9A, the sound deadening member 74 is not shown in order to clearly express the flow of air.

On the other hand, each of the silencers 16, 32, 46,
In order to confirm the effect of No. 68, the suction device 10 was surrounded by a soundproof wall, and the sound pressure level was measured with a sound level meter at a distance of 50 cm from the suction device 10 shown in FIG. As shown in FIG.
The measurement results show that the first to fourth forms of the silencer 1
6, 32, 46, and 68 have a lower rate of increase in sound pressure level due to an increase in the inlet compressed air pressure flowing into the adsorption device 10 than the conventional silencer 100, and the first to third forms of the silencer 16, At 32 and 46, even if the inlet compressed air pressure is increased to 0.4 MPa, the sound pressure level is targeted at 65.
dB or less.

Further, it was confirmed that the suction force (suction flow rate) was reduced due to the increase in the silencing effect. In the measurement results shown in FIG.
Silencers 16, 32, 46 of the first to fourth embodiments,
68 can generate almost the same suction force as the conventional silencer 100 when the inlet compressed air pressure is 0.4 MPa or more.

Further, the results of spectrum analysis of the sound pressure level in each frequency band using the silencer 16 of the first embodiment are shown. As shown in FIG. 12, it can be seen that the sound pressure level of a specific frequency is not reduced but the sound pressure level of the conventional silencer 100 is reduced substantially uniformly over a wide range.

[0055]

According to the present invention, the above configuration is provided.
According to the invention described in (1), the muffling effect can be improved only by attaching the existing muffler to the case. According to the second aspect of the present invention, the silencing effect can be improved only by connecting the conventional silencer to the conventional silencer via the connecting means, and the silencer can be made more compact. According to the third aspect of the present invention, the air can be detoured many times to increase the passage distance in the sound deadening material, and the air that has flowed in the vicinity of the slit and the discharge port interferes to reduce energy, thereby reducing the sound deadening effect. Can be improved. According to the fourth aspect of the present invention, a plurality of sound deadening chambers are provided, and air is diverted in the radial direction and the axial direction of the inner cylinder, so that the passage distance of the sound deadening material is increased. The noise reduction effect can be improved by reducing the energy by causing the air to interfere.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a silencer and a suction device according to a first embodiment.

FIG. 2 is an exploded perspective view of the silencer according to the first embodiment.

FIG. 3 is a cross-sectional view of a silencer according to a first embodiment and a diagram showing a flow of air.

FIG. 4 is an exploded perspective view of a silencer according to a second embodiment.

FIG. 5 is a cross-sectional view of a silencer according to a second embodiment and a diagram showing a flow of air.

FIG. 6 is an exploded perspective view of a silencer according to a third embodiment.

FIG. 7 is a cross-sectional view of a silencer according to a third embodiment and a diagram showing a flow of air.

FIG. 8 is an exploded perspective view of a silencer according to a fourth embodiment.

FIG. 9 is a cross-sectional view of a silencer according to a fourth embodiment and a diagram illustrating a flow of air.

FIG. 10 is experimental data showing the relationship between each inlet compressed air pressure and sound pressure level using the silencers according to the first to fourth embodiments and a conventional product.

FIG. 11 is experimental data showing the relationship between each inlet compressed air pressure and the suction flow rate using the silencers according to the first to fourth embodiments and a conventional product.

FIG. 12 is experimental data showing a relationship between a frequency band and a sound pressure level of the silencer according to the first embodiment and a conventional product.

FIG. 13 is an exploded perspective view showing a silencer and a suction device according to a conventional product.

FIG. 14 is an exploded perspective view of a silencer according to a conventional product.

FIG. 15 is a cross-sectional view of a silencer according to a conventional product and a diagram showing a flow of air.

[Explanation of symbols]

 18 core body 20 first silencer 22 main cylinder 24 case 26 communication port 28 discharge port 33 core 34 first silencer 36 main cylinder (connection means) 40 opening 42 outer cylinder (connection means) 44 discharge port 50 inner cylinder 54 first silencer 58 middle cylinder 62 second silencer 64 outer cylinder 70 inner cylinder 72 slit 74 silencer 76 outer cylinder 80 partition wall 82 partition wall 88 notch 90 outlet

Claims (4)

[Claims] An inner cylinder into which a slit is formed along a longitudinal direction and into which air is introduced, a silencing material covering an outer peripheral surface of the inner cylinder; For use in a silencer having an outer cylinder having a hole formed on the opposite side of the core, wherein a cylindrical core, a first silencer covering an outer peripheral surface of the core, and the first silencer are housed. A main cylinder that is closed due to
A case provided on an outer peripheral surface of the main cylinder and accommodating the muffler; and air formed between the case and the main cylinder and discharged from a hole of the outer cylinder flows into the first muffler. A silencer comprising: a communication port to be closed; and a discharge port formed at a position facing the communication port of the main cylinder and configured to discharge air that has passed through the first silencing material. 2. An inner cylinder in which a slit is formed along a longitudinal direction and air is introduced into the inner cylinder, a silencing material covering an outer peripheral surface of the inner cylinder, and the silencing material is housed in a closed state, and the slit is closed. For use in a silencer having an outer cylinder having a small hole formed on the opposite side of the cylindrical body, accommodating a cylindrical core, a first silencer covering an outer peripheral surface of the core, and a first silencer. A main cylinder that is closed due to
A connection means for connecting the main cylinder and the hole side of the outer cylinder, an opening formed in the main cylinder and allowing air discharged from the hole to flow into the first silencing material, A silencer, wherein the silencer has a discharge port formed at a position facing the opening and configured to discharge air that has passed through the first silencing material. 3. An inner cylinder in which a slit is formed along the longitudinal direction and air is introduced into the inner cylinder, a first silencer covering the outer peripheral surface of the inner cylinder, and a closed state in which the first silencer is housed. And a middle cylinder having a slit formed on the side opposite to the slit of the inner cylinder, a second silencer covering the outer peripheral surface of the middle cylinder, and a closed state in which the second silencer is housed and closed. And an outer cylinder having a discharge port formed on a side opposite to the slit of the silencer. 4. An inner cylinder into which air is introduced, a muffler covering the outer peripheral surface of the inner cylinder, an outer cylinder in which the muffler is inserted and in a closed state, and an inner cylinder provided inside the outer cylinder. , At least one partition wall that partitions an annular noise reduction chamber formed between the outer circumference of the inner cylinder, a partition wall that further divides the noise reduction chamber partitioned by the partition wall, and a longitudinal direction of the inner cylinder. A slit formed along the wall and allowing air to flow into one of the muffling chambers divided by the partition, and air formed in the partition and flowing out of the slit and bypassing the outer peripheral portion of the inner cylinder was divided by the partition. A silencer comprising: a notch introduced into the other muffling chamber; and an outlet formed in the outer cylinder and discharging air flowing out of the notch and bypassing the outer peripheral portion of the inner cylinder.