JPH0422008Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention uses a combination of a sealed tank, a pipe, a partition wall, etc. to reflect sound waves sent in with exhaust gas, etc. to the sound source side, and generates the reflected sound waves. By preventing the incoming sound waves from colliding with the sound waves and allowing them to pass through the ventilation path inside the equipment, the noise mainly associated with the intake and exhaust of civil engineering and construction machinery such as bulldozers and pile drivers, automobiles and other engines and compressors can be reduced. This invention relates to a noise reduction device that aims to attenuate noise.

[Conventional technology]

As such a conventional silencer, for example, a third
There is a picture. This is the inside of the sealed tank 1.
The sealed tank 1 is divided into four chambers through partition walls 5, 6, and 7, which have openings 2, 3, and 4, respectively, and arranged in the diametrical direction. A discharge tube is disposed to pass through an inlet tube 13 having a large number of thin notched grooves 12 on its surface, and has one end guided outside into the fourth compartment 11 and has a large number of small holes 14 on its circumferential surface. 15. The end of the feed tube 13 on the first compartment 8 side and the discharge tube 1
5 on the fourth compartment 11 side are closed by partition walls 5 and 7, respectively. The openings 2 and 4 provided in the partition walls 5 and 7 are composed of a large number of small holes, and the opening 3 of the partition wall 6 has a larger diameter than the openings 2 and 4 and is provided in smaller numbers. Further, the partition wall 7 may be covered with a wire mesh.

Therefore, in this device, the sound waves of noise that enter the inlet tube 13 due to exhaust gas, etc. are sent into the first compartment 8 through the plurality of notched grooves 12, and are sent into the first compartment 8 through the partition wall 5.
The second compartment 9 is opened through the opening 2 consisting of a large number of small holes.
Enter the third compartment 10 through the opening 3 of the partition wall 6.
The opening 4 consisting of a large number of small holes in the partition wall 7 passes through the
It escapes into the fourth compartment 11 and is discharged to the outside through the discharge tube 15 through the many small holes 14 of the discharge tube 15.

[Problem that the invention attempts to solve]

However, such conventional devices have the following problems due to the above structure.

a The partition walls 5, 7 are provided with openings 2, 4 consisting of a large number of small holes, and the partition wall 6 is provided with an appropriate number of openings 3, so that the partition walls 5,
The reflectivity of the sound waves passing through 6 and 7 is reduced as much as possible, and therefore the noise attenuation efficiency is not sufficient.

b Since the noise sound waves pass through the sealed tank 1 in one direction from the inlet pipe 13 to the discharge pipe 15 side, the distance the noise sound waves pass through the device is relatively short, and therefore the noise is attenuated. Not efficient enough.

c. Exhaust gas, etc. passes through each compartment via the narrow groove 12 provided in the inlet tube 13 and the extremely small diameter openings 2, 3, 4 provided in the partition walls 5, 6, 7.
The discharge tube 1 is inserted through the small hole 14 provided in the discharge tube 15.
Since it is discharged to the outside from 5, the ventilation resistance increases when passing through the device, creating a large back pressure.As a result, the passage path is clogged with carbon soot due to incomplete combustion of the engine, and the engine output is reduced. At the same time, the noise damping efficiency becomes insufficient.

d Since it is necessary to drill a large number of notches and small holes in the feed tube 13, discharge tube 15, and bulkheads 5, 6, and 7, the structure becomes as complicated as possible and a large amount of time is required for manufacturing and assembly. This also increases the risk of failure or damage, resulting in poor durability.

The object of the present invention is to solve the problems of the conventional devices and to provide a silencing device that has a simple structure and has extremely good noise attenuation efficiency.

[Means for solving problems]

The present invention attempts to solve the problems of the above-mentioned conventional apparatus by making rational improvements to the structures of the inlet and outlet tubes and partition walls, and their arrangement within the closed tank. That is, specifically, ``the inside of a closed tank with an appropriate length and an appropriate diameter is divided into four compartments through partition walls arranged in the diametrical direction, and the first and fourth compartments are divided into second and third compartments. The volume is relatively small, and one end is led out to the outside and the other end is opened to the third compartment in the center of the first and second compartments, and each end is connected to the side wall of the sealed tank as much as possible. The second and third
Inside the compartment, there is a first tube with a diameter slightly smaller than that of the feeding tube, and one end of which is a first tube.
A plurality of elongated connecting tubes each having the other end opened in the fourth compartment are arranged in a concentric circular position centered on the feeding tube, and the feeding tube is inserted into the second compartment. A plurality of short connecting tubes each having a diameter slightly smaller than that of the feeding tube and opening at one end into the first compartment and at the other end into the third compartment are arranged in concentric circles around the feeding tube. In addition, a discharge pipe with one end extending outside is provided in the center of the fourth compartment.

[Effect]

Noise sound waves sent along with exhaust gas etc. from a considerable length of inlet pipe collide with the bulkhead of the third compartment when they exit the inlet pipe, are reflected back to the sound source side, and the reflected sound waves are sent back. A plurality of rods collide with the incoming sound waves, diffuse uniformly throughout the third compartment, penetrate into the second compartment, open into the third compartment, and are arranged in concentric circles around the feeding tube. The sound travels inside the short connecting cylinder toward the source side and enters the first compartment, is reflected by the side wall 20 ₁ of the sealed tank, and the first
Opening into the compartment, passing through the second and third compartments, and advancing toward the discharge cylinder through a plurality of long connecting cylinders arranged concentrically around the feed cylinder; When the sound passes through each of the long connecting tubes into the fourth compartment, it comes into contact with the side wall of the sealed tank, is reflected again toward the sound source, and is discharged to the outside through the discharge tube led out from the fourth compartment.

Therefore, the noise sound waves sent through the inlet pipe of considerable length exit the inlet pipe and are reflected in the sound source direction by the partition wall of the third compartment and collided with each other, and are also reflected in the closed tank 20 ₁ , 20 ₂ , the low-frequency components are first efficiently attenuated, and then the high-frequency components are attenuated as they pass into the long U-shaped ventilation path from the short connecting tube to the long connecting tube to the discharge tube. components are efficiently attenuated. In addition, exhaust gas, etc. is released from an outlet having the same diameter as the inlet diameter of the inlet tube into a third compartment which is larger than the inside of the inlet tube, and is arranged in a concentric circle around the inlet tube. Since the exhaust gas is distributed within a plurality of short connecting cylinders with a relatively large diameter and directed toward the first compartment, the pressure associated with the exhaust gas, etc. is greatly reduced in the third compartment, and
Since it is discharged from the fourth compartment to the outside through the exhaust pipe with the same diameter as the inlet pipe, ventilation resistance increases as exhaust gas, etc. passes into the ventilation path of the device, creating a large amount of back pressure. This is not the case, and exhaust gas and the like are smoothly discharged.

〔Example〕

An example of the embodiment of the present invention will be described with reference to the attached drawings FIGS. 1 and 2. 20 has both ends attached to the side wall 2
0 ₁ , 20 ₂ is closed, and has an appropriate length and diameter. 25, 3rd compartment 26, 4th
It is divided into four compartments 27. 1st, 4th
The compartment has a smaller volume than the second and third compartments. A feeding cylinder 28 is disposed through the center of the first compartment 24 and the second compartment 25 through support of the side wall 20 ₁ and the partition walls 21 and 22.
One end of the feeding cylinder 28 is guided outside, and the other end opens into the third compartment 26 through a fitting hole provided in the partition wall 22. In the second compartment 25 and the third compartment 26, four long connecting tubes 29 are disposed to penetrate through the partition walls 21, 22, and 23, and each long connecting tube 29 The ends of the side walls 20 of the closed tank are located in the first compartment 24 and the fourth compartment 27, respectively.
₁ and 20 ₂ as close as possible. The four long connecting tubes 29 have a diameter slightly smaller than that of the feeding tube 28, and are arranged around the feeding tube 28 in a concentric circle with an interval of 90 degrees from each other. ing. Moreover, eight short connecting tubes 30 are installed in the second compartment 25 through the support of the partition walls 21 and 22.
is disposed through the tube, and the ends of each short connecting tube 30 open into the first compartment 24 and the third compartment 26, respectively. And these eight short connecting tubes 3
0 has a slightly smaller diameter than the feeding tube 28, and like the long connecting tube 29, they are arranged in a concentric circle around the feeding tube 28, and each two tubes are connected to four long connecting tubes. It is arranged between the connecting tubes 29. A discharge tube 31 having the same diameter as the feed tube 28 and having one end led out to the outside through the support of the side wall 20 ₂ is disposed in the center of the fourth compartment 27 .

Therefore, the noise sound waves sent from the feed tube 28 along with the exhaust gas, etc. enter the third compartment 26 in the large space from the outlet of the feed tube 28, collide with the partition wall 23, and go to the sound source side. While being reflected, the reflected sound waves collide with the incoming sound waves that are successively sent in, and are uniformly diffused throughout the third compartment 26, and as a first step, low frequency components are attenuated. Next, the sound waves of the noise that have been diffused into the third compartment 26 and have had their low frequency components attenuated are transmitted to the 8 which opens into the third compartment 26.
It enters each short connecting tube 30 of the book in a distributed manner, advances inside the short connecting tube 30 toward the sound source side, and then enters the first connecting tube 30.
It enters the compartment 24, is reflected by the side wall ₂₀₁ of the sealed tank, receives further attenuation of low frequency components, and enters each of the four long connecting tubes 29 opening into the first compartment 24. The noise sound waves that have entered each long connecting tube 29 advance inside the long connecting tube 29 toward the discharge tube 31 side, enter the fourth compartment 27, are reflected by the side wall 20 ₂ of the sealed tank, and are further The discharge tube 31 receives attenuation of low frequency components and opens into the fourth compartment 27.
more is discharged to the outside. This short connecting tube 30, the first compartment 24, the long connecting tube 29, the fourth compartment 27,
The high frequency components are attenuated as the air passes through the exhaust tube 31, which is a relatively long ventilation path.

Furthermore, the exhaust gas etc. sent into the feed tube 28 is released from the outlet having the same diameter as the inlet into the third compartment 26, which is a larger space than the feed tube 28, and diffuses. Since the gas enters the eight short connecting tubes 30 of relatively large diameter arranged in a concentric circle around the tube 28 in a distributed manner, the pressure associated with the exhaust gas etc. is greatly reduced at this stage. be done. Then, the exhaust gas, etc. whose pressure has been reduced, smoothly travels through the short connecting tube 30, the first compartment 24, the long connecting tube 29, and the fourth compartment 27, and passes through the discharge tube having the same diameter as the inlet tube 28. 31 to the outside. Therefore, the exhaust gas and the like are smoothly discharged without increasing the ventilation resistance and applying a large amount of back pressure as the exhaust gas passes through the ventilation path of the device.

Incidentally, an example of the dimensions of the above embodiment device is as follows.

Inlet tube 28, discharge tube 31, φ50mm (40mm or less) Long connection tube 29, short connection tube 30, φ30mm (20
mm) Sealed tank 20, 200mm (150mm) Total length of sealed tank 20, 350mm (300mm) Length of short connecting tube 30 150mm (150mm) Length of first compartment 24, fourth compartment 27
50mm (50mm) Length of third compartment 100mm (50mm) Distance between long connecting tube 29 and side walls 20 ₁ , 20 ₂
20mm (20mm) Distance between the discharge pipe 31 and the partition wall 23 20mm (20mm) However, as a result of an experiment using the above specific device, 30
It was possible to muffle approximately 40 horns, and a damping effect 3 to 4 times greater than that of conventional devices was obtained.

[Effect of idea]

Since the present invention is constructed as described above, it solves the problems of the above-mentioned prior art and has the following effects.

1. The feed cylinder passes through the first and second compartments, and its opening face faces the discharge cylinder side partition wall of the third compartment. Therefore, the feeding tube has a considerable length, and is disposed so as to penetrate through the central portions of the first and second compartments. Moreover, since the short connecting tube connected to the third compartment extends toward the first compartment, no opening surface is formed in the discharge cylinder side partition wall of the third compartment. The first and fourth compartments are set to have a smaller volume than the second and third compartments, and both ends of each long connecting tube open to the first and fourth compartments. is located as close as possible to the side wall of the closed tank.

Therefore, the low frequency component of the noise is caused by the collision between the reflected sound wave and the transmitted sound wave due to reflection from the partition wall 23 of the third compartment and the side walls 20 ₁ and 20 ₂ of the sealed tank of the first and fourth compartments. Therefore, the sound is surely attenuated and muffled.

2. Even if the overall length and other dimensions of the device are the same as those of conventional devices, the combination of the short connecting tube and the long connecting tube installed in the compartment will reduce the distance that the noise waves travel through the device. It can be made much longer than the previous one, and therefore the noise can be sufficiently attenuated compared to the conventional one.

3 Even if the distance of the ventilation path for the noise sound waves in the equipment is made longer than before, there are still small parts on the peripheral surfaces of the inlet tube, each connection tube, and the discharge tube in the device, as well as on the partition walls of the compartments. There are no small holes, notched grooves, or openings in the area, and the exhaust gas, etc. is released from the inlet tube into the third compartment in the large space, diffused, and dispersed into multiple long connecting tubes. Since the exhaust gas is discharged to the outside through the first compartment, the plurality of long connecting pipes, and the fourth compartment from the discharge pipe having the same diameter as the inlet pipe, unlike conventional methods, there is no ventilation resistance due to the passage of exhaust gas, etc. This increases the amount of backpressure that occurs, causing carbon soot due to incomplete combustion in the engine to clog in the ventilation path, causing a reduction in engine output and the possibility that sufficient noise attenuation may not be achieved. do not have.

4 Unlike conventional equipment, there is no need to drill numerous small holes or small-diameter openings in the inlet and discharge tubes and partition walls of the compartments, and the system simply consists of a straight cylinder and a flat plate. Since the device can be formed by combining the devices, the overall structure is extremely simple compared to conventional devices, making manufacturing and assembly easier, as well as having excellent durability with less risk of failure or damage.

5. There are no restrictions on the material of the device, but as mentioned above, the overall structure is simple and does not require drilling, so stainless steel or composite steel coated with stainless steel may be used in the same way. In this case, durability and corrosion resistance can be further increased.

6. As mentioned above, the attenuation efficiency of low frequency components and high frequency components of noise is extremely good compared to conventional systems, so by appropriately selecting the diameter and length of each cylindrical body, it is possible to create a suitable device according to the noise source. can be obtained.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the silencing device according to the present invention, FIG. 1 is a vertical side view,
Figure 2 is a cross-sectional front view (A-A sectional view in Figure 1);
FIG. 3 is a longitudinal sectional side view of the conventional device. 20... sealed tank, 20 ₁ , 20 ₂ ... side wall of sealed tank, 21, 22, 23... bulkhead, 24...
...First compartment, 25...Second compartment, 26...Third compartment, 27...Fourth compartment, 28...Infeed tube, 29...Long connection tube, 30...Short connection tube,
31...Ejection tube.

Claims (1)

[Scope of utility model registration request] The inside of a sealed tank with an appropriate length and an appropriate diameter is divided into four chambers through partition walls arranged in the diametrical direction.
The volume of the compartment is smaller than that of the second and third compartments,
A feeding cylinder having one end led out to the outside and the other end opening into the third compartment is disposed in the center of the first and second compartments, and inside the second and third compartments, It has a slightly smaller diameter than the feeding tube, and has one end in the first compartment and the other end in the fourth compartment.
A plurality of long connecting tubes each having an opening in the compartment and each end placed as close as possible to the side wall of the sealed tank are arranged in concentric circles around the feeding tube. In the second compartment, a plurality of short connecting tubes each having a diameter slightly smaller than that of the feeding tube and opening at one end into the first compartment and at the other end into the third compartment are placed in a concentric circle around the feeding tube. What is claimed is: 1. A sound muffling device characterized in that a discharge tube is disposed in a central portion of the fourth compartment and has one end led out to the outside.