JP2001280114A - Muffler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler free from the clogging and the deterioration in use with the lapse of time, having a simple structure, and being properly used for the silencing of an exhaust port. SOLUTION: An inner cylinder 14 having plural outflow holes 20 arranged along the longitudinal direction is inserted into an outer cylinder 2 comprising circular arc guide face parts 6, 6 and longitudinal flat face parts 4, 4, and having a number of fine ejection holes 7 on the flat face parts 4, 4 an array of the outflow holes 20 is opposite to the circular arc guide face parts 6, 6, and a swirl clearance 25 of the compressed air for communicating the outflow holes 20 and the fine ejection holes 7 is formed between the inner cylinder 14 and the outer cylinder 2. Whereby the inner cylinder 14 itself is provided with the action as a reactive muffler, and the compression air flowing out from the outflow holes 20 is expanded at a swirl clearance 25 side to be changed to the swirl current in the circumferential direction by the guiding action of the circular arc guide face parts 6, 6, and collided with the flat parts 4, 4, whereby the acoustic waves are interfered with each other to produce the action of a so-called interference-type muffler.

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 exhaust noise of compressed air discharged from various pneumatic devices.

[0002]

2. Description of the Related Art In various types of pneumatic equipment operated by using compressed air, a loud noise is generated at an outlet at the time of exhaustion and the like, which may lower the working environment. A muffler is attached to the outlet.

[0003] By the way, a silencer used for such an application generally has a structure in which a porous sound absorbing material or a fiber-based sound absorbing material is housed in a container, and the sound is absorbed by each sound absorbing material. General. For example, in the case of the former,
No. 61110, Japanese Utility Model Application Laid-Open No. 3-104116, and in the latter case, Japanese Utility Model Application Laid-Open No. 55-25624,
No. 2 and the like.

[0004]

The compressed air ejected from the exhaust port of such a pneumatic device contains moisture invading the piping, oil mist of cylinder lubricating oil, dust, etc., and is compressed air. When, penetrates the sound absorbing material, these components remain in the porous material of the sound absorbing material or in the fine flow holes of the fibers, and are likely to cause clogging. Therefore, if left for a long time,
Such clogging reduces the effective flow area, applies a large load, and causes malfunction of the pneumatic device. In addition, when a sound absorbing material made of a fiber material is used, deterioration due to moisture or oil also becomes a problem. For this reason, the service life is short,
It was necessary to replace the silencer in a relatively short time. Moreover, since the sound absorbing material is installed in the cylindrical holding container,
Not only is the unit price high, but also the structure is complicated, so most of the structures cannot be replaced with sound absorbing material, and the silencer must be disposed of with the oil contaminated, which is uneconomical and environmentally friendly. There were also problems. As described above, the conventional silencer using the sound absorbing material has a problem that the service life is short, the maintenance is complicated, and the management cost is high.

It is an object of the present invention to provide a silencer which is free from such clogging and deterioration due to use over time, has a simple structure, and is optimal for silencing an exhaust port.

[0006]

According to the present invention, there is provided a bottomed bottom in which an arc guide surface portion and a flat surface portion extending in a longitudinal direction are coupled in a circumferential direction, and a large number of minute ejection holes are formed in the flat surface portion. An outer cylinder, a bottomed inner cylinder that is inserted into the outer cylinder and has a plurality of outflow holes arranged in a longitudinal direction at a side edge facing the arc guide surface portion, the front end serving as an air inlet. And a swirl space of compressed air is formed between the inner cylinder and the outer cylinder to communicate with the outflow hole and the minute ejection hole. (Means of claim 1)

In such a configuration, the air inlet is connected to the outlet of the pneumatic device. As a result, compressed air flows into the inner cylinder from the air inlet, flows out of the outflow hole into the swirling space, is further guided by the arc guide surface portion, and flows out from the numerous minute ejection holes formed in the flat surface portion of the outer cylinder. Gushing. (Operation of Claim 1)

In this flow process, since the inside of the inner cylinder is hollow, a Helmholtz resonator is formed, vibrating air violently and absorbing sound energy. That is, the inner cylinder functions as a resonance type silencer. Also, the compressed air subjected to this silencing action expands from the outflow hole on the side of the swirling gap,
In addition, a swirling flow in the circumferential direction is generated by the guiding action of the arc guide surface portion. By the way, since the swirling gap has a flat surface portion instead of a uniform annular shape, the outer swirling flow collides with the inner surface of the flat surface portion and rebounds. As described above, since the compressed air causes various flows due to the flat surface portion, the sound waves interfere with each other, so that a so-called interference type silencer operates.
Then, the compressed air is ejected from the minute ejection holes while reducing the sound pressure while interfering with each other. Thus, the silencer having such a configuration can effectively reduce the sound generation by producing the actions of the resonance type silencer and the interference type silencer.

In such a configuration, a flat surface portion having a large number of minute ejection holes formed on the upper and lower sides of the outer cylinder is provided, and a plurality of outflow holes can be arranged along the longitudinal direction on both side edges of the inner cylinder. . (Means of Claim 2)

In this manner, by forming the flat portions on the upper and lower sides of the outer cylinder and forming the rows of outflow holes of the inner cylinder on the left and right, the compressed air flowing out of each of the outflow holes is guided by the arc guide surface of the outer cylinder. As a result, the flow is bisected toward the upper and lower flat portions, and the swirl flows in opposite directions. For this reason, the swirling flows collide with each other in the swirling gap and are repeatedly reflected by the flat surface portion, thereby interfering with each other, causing a large loss of sound energy, and improving the sound deadening effect. (Function of Claim 2)

Here, the outflow holes arranged along the longitudinal direction of the inner cylinder can be gradually reduced in diameter toward the far end.

That is, the compressed air flows out from the air inlet along the inner cylinder, hits the bottom of the inner end thereof, and flows out from each outlet hole into the annular peripheral gap. For this reason, when the inner cylinder has the same diameter in the longitudinal direction, the ejection amount from the outflow hole tends to increase as the inner cylinder approaches the bottom. Therefore, the outflow holes are made smaller as they are closer to the inner bottom, so that the flow rates from each outflow hole are made as equal as possible, and compressed air is jetted uniformly from the side edge of the inner cylinder along the longitudinal direction. This allows
A silencing effect can be evenly generated along the long direction. (Function of Claim 3)

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the accompanying drawings. As shown in FIGS. 1 to 4, the silencer 1 of the present invention is configured by inserting an inner cylinder 14 into an outer cylinder 2.

Here, as shown in FIGS. 5 and 6, the outer cylinder 2 has a bottomed shape, and flat surface portions 4 and 4 are formed on the upper and lower sides thereof, and the arc guide surface portion 6 is provided between the flat surface portions 4 and 4. , 6 are formed. A large number of fine minute ejection holes 7 having an inner diameter of about 1.2 mm are formed in the flat plane portions 4 and 4 in the vertical and horizontal directions. The outer cylinder 2 is shielded at the back end by a back bottom portion 9 and has a connection hole 10 formed at the center thereof. Further, the front end is open and serves as an insertion end of the inner cylinder 14.

A specific example of the outer cylinder 2 is a male screw projection 18.
Thread size R3 / 8 (taper thread for pipes), outer diameter 26 mm and inner diameter 22 mm of arc guide surfaces 6, 6, outer dimension 20 mm and inner dimensions between flat plane parts 4, 4 are 16 mm, and length is 69 mm. (This is only a design example.)

The inner cylinder 14 inserted into the outer cylinder 2 is shown in FIG.
As shown by, it has a tapered bottomed cylindrical shape having a deep bottom portion 16, and the inside is an inner space 15. The front end is opened to serve as an air inlet 21. A sealing flange 17 (see FIG. 3) for closing the opening of the front end of the outer cylinder 2 is formed on the peripheral edge of the front end, and a male screw projection 18 that is screwed into the exhaust hole of the pneumatic device is formed. ing. A screw hole 19 is formed in the inner bottom portion 16 of the inner cylinder 14.

Further, a plurality of outflow holes 20 are formed on both side surfaces of the inner cylinder 14 along the longitudinal direction at left and right edge positions facing the center of the arc guide surface portions 6, 6. The diameter of the outflow hole 20 is gradually reduced in the depth direction. The inner cylinder 14 is slightly tapered.

As an example of the dimensions of the inner cylinder 14, the length inserted into the outer cylinder 2 excluding the male screw projection 18 is 67 mm. After the outer surface of the outer cylinder 16 is brought into contact with the inner surface of the inner bottom portion 9 and the sealing flange 17 is inserted into a position where it fits into the front end opening of the outer cylinder 2, the connecting screw 30 is inserted through the connecting hole 10 shown in FIG. Screw hole 19 shown
And the outer cylinder 2 and the inner cylinder 14 are connected. And
In such a connected state, a turning gap 25 is formed between the inner surface of the outer cylinder 2 and the outer surface of the inner cylinder 14.

Next, the operation of the above configuration will be described. As shown in FIG. 2, the male screw projection 18 of the silencer 1 is screwed into the exhaust port of the pneumatic device, and the air inlet 21 is connected to the exhaust port. As a result, the compressed air discharged from the pneumatic device flows into the inner cylinder 14 from the air inlet 21, and from the plurality of outflow holes 20 along the longitudinal direction on both side edges of the inner cylinder 14 to the swirling gap 25. As shown in FIG. 4, the fluid flows out and is guided by the inner surfaces of the arc guide surfaces 6 and 6 of the outer cylinder 2.
Are ejected from a large number of minute ejection holes 7 formed in the flat surface portions 4 and 4.

In this flow process, the compressed air press-fitted into the inner cylinder 14 is ejected from the inner space 15 through the outflow hole 20 to the swirl gap 25 side. For this reason, the inner cylinder 1
4 is equivalent to a Helmholtz resonator having a hollow inside, and vibrates the air violently to produce an action as a resonance type silencer that absorbs sound energy. Further, the compressed air subjected to the noise reduction function further expands from the outflow hole 20 in the swirl space 25 and further has an arc guide surface portion 6.
As shown by the arrow in FIG. 4, the guide action 6 divides the upper and lower halves into swirling flows α and β in opposite directions in the circumferential direction.

Incidentally, since the swirling gap 25 is not a uniform annular shape but has upper and lower flat portions 4, 4, the outer swirling flow collides with the inner surfaces of the flat portions 4, bounces off, and is disturbed. It becomes a flow. Therefore, the compressed air generates various flows, and the sound waves interfere with each other. Moreover, since the swirling flows α and β in the opposite directions, which are divided into upper and lower parts, are generated, the swirling flows α and β
β collide with each other, resulting in a loss of sound energy, thus exhibiting the function of a so-called interference type silencer. Thus,
The silencer 1 can effectively reduce the sound generation by producing the respective functions of the resonance type silencer and the interference type silencer.

On the other hand, as shown in FIG. 2, the outflow holes 20 arranged along the longitudinal direction of the inner cylinder 14 are gradually reduced in diameter toward the bottom. That is, the compressed air flows in from the air inlet 21 along the inner cylinder, hits the inner bottom thereof, and flows out from each of the outflow holes 20 to the swirl gap 25, so that the inner cylinder 14 extends in the longitudinal direction. In the case of a diameter, as shown by an arrow group x in FIG. 2, the ejection amount from the outflow hole 20 tends to increase as it is closer to the bottom. Therefore, the diameter of the outflow hole 20 is made smaller as it is closer to the inner bottom,
As shown by the arrow group y in FIG. 2, the flow rate from each of the outlet holes 20 is made as equal as possible, and the compressed air is jetted uniformly from the side edge of the inner cylinder 14 along the longitudinal direction. . Thereby, it is possible to uniformly generate a noise-reducing effect along the long direction.

Table 1 shows the above-mentioned example of the design dimensions, and also shows the inner diameter and number (φ1.2 mm-88) of the minute ejection holes 7.
Muffler 1 constructed by assembling the outer cylinder 2 and the inner cylinder 14 by changing only the
And a conventional commercially available silencer (AN300) using a porous sound absorbing material made of a sintered material. Here, the noise is attached to the exhaust valve of the solenoid valve of the air cylinder, respectively, silencers attached, noise generated from the exhaust port,
The output was measured by an integrating recorder and the generated output was measured by an analyzing recorder, and the exhaust noise pressure was calculated from the output waveform.

[0024]

[Table 1]

Here, when the silencer was not used, the exhaust noise pressure (dB) from the valve exhaust port was about 100 dB. The effective sectional area is obtained by measuring the time required for the inside of the cylinder to decrease to a predetermined pressure and converting the measured time into the virtual opening area of the air outlet. If this value is large, the airflow resistance is small, and the air discharge processing amount is large.

As apparent from Table 1, the product of the present invention
The exhaust noise pressure is almost the same as that of the conventional silencer. It is also understood that the effective cross-sectional areas are almost the same, and that the desired characteristics can be adjusted by appropriately selecting the inner diameter and the number of the minute ejection holes 7.

In the above-described configuration, the flat portions 4 and 4 are formed on the upper and lower sides of the outer cylinder 2 and the rows of the outflow holes 20 are formed on the left and right of the inner cylinder 14 so as to face the arc guide surface section 6. However, the flat portion 4 may be single, and the separation angle between the 20 rows of outflow holes and the arc guide surface portion 6 can be appropriately selected.

[0028]

The silencer of the present invention has a circular arc guide surface and a flat surface along the longitudinal direction, and a plurality of outflow holes are formed in an outer cylinder having a large number of minute ejection holes formed in the flat surface. The inner cylinders arranged along the longitudinal direction are inserted, the outflow hole row is opposed to the arc guide surface portion, and the swirling of the compressed air communicating between the outflow holes and the minute ejection holes is provided between the inner cylinder and the outer cylinder. Because the gap is formed, the inner cylinder itself has the function of a resonance type silencer, and the compressed air that has flowed out of the outlet hole expands on the side of the swirling gap to guide the arc guide surface. As a result, a swirling flow in the circumferential direction collides with the flat surface portion, thereby causing sound waves to interfere with each other, thereby producing a so-called interference type silencer.

As a result, the sound absorbing effect is high, and since there is no sound absorbing material, it is not necessary to replace the sound absorbing material due to clogging, thereby improving the durability. Further, even if the minute ejection holes or the outflow holes are clogged, it can be reused by washing. Furthermore, the structure is simple, and it can be easily formed by injection molding of a synthetic resin material or the like, so that it is easy and inexpensive to manufacture. (Effect of Claim 1)

Further, in such a configuration, a flat surface portion having a large number of minute ejection holes formed on the upper and lower sides of the outer cylinder is provided, and a plurality of outflow holes are arranged along the longitudinal direction on both side edges of the inner cylinder. In this case, the compressed air flowing out of each outlet hole is bisected toward the upper and lower flat portions by the guiding action of the arc guide surface portion of the outer cylinder, and becomes a swirling flow in the opposite direction, and swirls in the swirling space. When the streams collide with each other and are repeatedly reflected on the flat surface portion, the streams mutually interfere with each other, resulting in a loss of sound energy, thereby improving the sound deadening effect. (Effect of Claim 2)

Further, in such a configuration, when the outflow holes arranged along the longitudinal direction of the inner cylinder are gradually reduced in diameter toward the depth bottom, the outflow holes from each of the outflow holes are formed. The flow rate can be made as equal as possible, and the compressed air can be jetted out uniformly from the side edge of the inner cylinder along the elongate direction, thereby producing a silencing effect evenly along the elongate direction.
(Effect of Claim 3)

[Brief description of the drawings]

FIG. 1 is a side view of a muffler 1 according to the present invention.

FIG. 2 is a longitudinal sectional front view of the muffler 1 of the present invention.

FIG. 3 is a cross-sectional plan view of the muffler 1 of the present invention.

FIG. 4 is a longitudinal sectional side view of the muffler 1 of the present invention.

5 is a vertical sectional front view of the outer cylinder 2. FIG.

6 is a vertical side view of the outer cylinder 2. FIG.

7 is a vertical sectional front view of the inner cylinder 14. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silencer 2 Outer cylinder 4,4 Flat surface part 6,6 Circular guide surface part 7 Micro ejection hole 14 Inner cylinder 20 Outflow hole 21 Air inlet 25 Swirling gap

Claims (3)

[Claims] 1. A bottomed outer cylinder in which a circular arc guide surface portion and a flat surface portion extending in the longitudinal direction are coupled in a circumferential direction, and a plurality of minute ejection holes are formed in the flat surface portion; A plurality of outflow holes are arranged along the longitudinal direction at a side edge facing the arc guide surface portion, and a bottomed inner cylinder having a front end serving as an air inlet is provided, and an inner cylinder and an outer cylinder are provided. Wherein a swirling circumferential space of the compressed air communicating with the outflow hole and the fine ejection hole is formed between the muffler and the air outlet. 2. A method according to claim 1, further comprising a flat surface portion having a plurality of minute ejection holes formed on the upper and lower sides of the outer cylinder, and a plurality of outflow holes arranged on both side edges of the inner cylinder along a longitudinal direction. 1. The muffler according to 1. 3. The silencer according to claim 1, wherein the outflow holes arranged along the longitudinal direction of the inner cylinder are gradually reduced in diameter toward the back end. vessel.