JP2006119432A - Muffler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a muffler which occupies less space and has sufficient muffling performance. <P>SOLUTION: The muffler has a muffler main body 2 which allows gas to pass through, a perforated plate 4 which is arranged in the muffler main body 2 so as to form a min flow path 3a and a sub-flow path 3b, that are joined at the end section of the downstream side, at the inner side and the outer side, a pipe 5a which is used to guide the gas into the main flow path 3a so that the gas is allowed to flow in the main flow path 3a while being gyrated and through-holes 4a which pass a portion of the gas being gyrated in the main flow path 3a to the sub-flow path 3b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a silencer that silences noise superimposed on a fluid flow.

  So far, various structures have been proposed in order to mute noise superimposed on the flow of fluid (gas). For example, Patent Document 1 discloses a porous soundproof structure having a plurality of through holes through which gas flows. Such a porous soundproof structure is formed by opposingly arranging an exterior plate and an interior plate having a large number of through-holes, and the interior plate has a thickness, a hole diameter, and an opening ratio of a gas flowing through the through-holes. It is set so as to satisfy the design conditions for generating viscous action. And the energy of the sound wave is dissipated by the viscous action to absorb the sound. A structure using such a porous soundproof structure as a sound absorbing member is one of the structures that muffles noise superimposed on the gas flow.

Japanese Patent Laying-Open No. 2003-50586 (FIG. 1)

  However, although the sound absorbing structure described in Patent Document 1 can obtain a sound absorbing effect in a wide frequency range, its sound absorption rate is as small as about 0.3, and when this sound absorbing structure is used as a sound absorbing member of a silencer, it is sufficient. In order to obtain the silencing performance, it is necessary to enlarge the silencer body.

  Therefore, an object of the present invention is to propose a silencer that has a sufficient space-saving performance.

Means and effects for solving the problems

  The present invention relates to a silencer main body through which a fluid flows, a partition member provided in the silencer main body so as to form a main flow path and a sub flow path joined at an end on the downstream side inside and outside, a fluid Swirl starting means for allowing the fluid to flow into the main flow path so that the fluid flows while swirling the main flow path, and a through hole provided in the partition member for allowing a part of the fluid flowing through the main flow path to pass through the sub flow path. Have.

  According to this configuration, since the fluid flows in the main flow path while turning along the inner peripheral surface of the partition member, the fluid tends to spread outward by centrifugal force, and the fluid easily passes through the through hole provided in the partition member. can do. When sound waves pass through the through-hole, a viscous action on the hole wall surface can provide attenuation (silence) effect of the sound wave. When the flow of fluid superimposed with sound waves passes through the through-hole, in addition to the viscous action, the pressure loss of the flow By the action, the sound wave attenuation (silence) effect can be remarkably increased. Thereby, it is possible to realize a silencer having a sufficient silencing performance in a space-saving manner. Moreover, in order to flow a fluid to a through-hole, the centrifugal force by turning a fluid is utilized, and the resistance with respect to the flow of the fluid in the main flow path of the partition member which provided the through-hole can be made small.

  The partition member of the present invention is preferably cylindrical. According to this, the fluid flowing through the main flow path is likely to swirl along the inner peripheral surface of the partition member, and more easily passes through the through hole.

  It is preferable that the present invention includes an auxiliary partition member that is disposed so as to surround the partition member at an interval and provided with a passage hole through which a fluid passes. According to this, a larger silencing effect can be obtained in a wider frequency range.

  The present invention may include a blocking member provided to reflect a sound wave superimposed on the fluid flowing in the sub-flow channel so that the fluid flows downstream. According to this configuration, it is possible to prevent unnecessary acoustic resonance in the sub-flow channel and to mute up to a higher frequency.

  In this case, it is preferable that the relationship of b = <c / (2f) is satisfied, where f is the highest frequency of the sound wave, c is the sound velocity of the sound wave in the gas, and b is the interval between the blocking members. According to this, the sound can be reliably silenced by adjusting the interval between the blocking members.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, a first embodiment of the present invention will be described. The silencer 1 according to the present embodiment includes a moving device including a driving mechanism such as an engine, and a driving mechanism such as a motor and a gear inside, such as an automobile, a railway vehicle, a construction vehicle, a ship, and an automatic conveyance device. Suitable for exhaust pipes used when discharging airflow (fluid) with superimposed noise (sound waves) from equipment machinery, etc., or pipes where sound waves are propagated superimposed on the flow of compressed gas, such as compressors Is done. In addition, in this Embodiment, although the fluid which distribute | circulates the silencer 1 is demonstrated as gas, liquids, such as water and oil, may be sufficient.

  As shown in FIGS. 1 (a) and 1 (b), the silencer 1 includes a cylindrical silencer body 2 that forms a flow path 3 through which an air flow superimposed with sound waves flows, and a cylindrical porous plate. 4 (partition member) and piping 5a (turning start means) and 5b. The silencer body 2, the perforated plate 4, and the pipes 5a and 5b are made of a metal such as iron or aluminum, or a synthetic resin. The silencer body 2, the perforated plate 4, and the pipes 5a and 5b are preferably formed of the same material so that the separation process at the time of recycling is unnecessary.

  The perforated plate 4 extends in the axial direction of the silencer body 2 and divides the flow path 3 so as to form a main flow path 3a on the inner side and a sub-flow path 3b on the outer side. It arrange | positions so that the center axis | shaft of the main body 2 may correspond. That is, the sub-flow path 3b surrounds the outer periphery of the cylindrical main flow path 3a. Further, the perforated plate 4 is arranged so that the divided main flow path 3a and sub flow path 3b join at the downstream end. The porous plate 4 has a plurality of through holes 4a through which gas passes, and the gas can move between the main flow path 3a and the sub flow path 3b through the through holes 4a. It has become. The parameters such as the plate thickness of the perforated plate 4, the opening ratio of the through hole 4a, and the hole diameter are set so as to cause a damping effect due to viscous action and pressure loss on the gas passing through the through hole 4a. It is preferable.

  Further, when the gas is air at normal temperature and normal pressure, the hole diameter of the through hole 4a is not particularly limited, but is desirably 2 mm or less. And when the hole diameter of the through-hole 4a is set to 2 mm or less in this way, a viscous action can be reliably generated in the gas flowing through the through-hole 4a.

  Similarly, the lower limit of the diameter of the through hole 4a is preferably 0.2 mm. The reason for this is that when the diameter of the through hole 4a approaches 0, the peak of the sound absorption coefficient is theoretically 1.0, but in reality, it does not reach 1.0, and the diameter is 0.2 mm or less. This is because, if it is extremely small, the viscosity of the air in the through-hole 4a becomes too large, so that the resistance to the air flow in the through-hole 4a increases and the sound absorption rate is considered to decrease. In addition, if the diameter is extremely small, such as 0.2 mm or less, the manufacturing becomes significantly difficult, and depending on the usage environment, the through-hole 4a is likely to be blocked by dust, dust, or the like. In addition, the diameter of the through-hole 4a is not limited to the above-mentioned numerical value, and a suitable numerical value may be determined according to the gas state, characteristics, frequency of the sound wave to be silenced, and the like.

  Moreover, the through-hole 4a may be oval, rectangular, polygonal, or slit-shaped, may be set to the same size and shape, or may be mixed in various sizes and shapes. good. When various sizes and shapes are mixed, the frequency bandwidth that exhibits sufficient sound absorption performance can be expanded.

  The pipes 5a and 5b are disposed in the silencer body 2 and allow gas to flow into and out of the silencer body 2. The pipe 5a is disposed on the upper surface of the silencer body 2 at an angle of about 45 degrees, and the pipe 5b has a diameter substantially the same as the diameter of the perforated plate 4. It is arrange | positioned in the approximate center part of the lower surface. The pipe 5a is disposed at a position where gas flows into the main flow path 3a, that is, inside the perforated plate 4. By disposing the pipe 5a at an angle, the gas flows into the silencer body 2 at an angle, hits the perforated plate 4, and turns along the inner wall of the perforated plate 4 as indicated by the arrows in the figure. The main flow path 3a is circulated. Here, the upper surface of the silencer body 2 is the upstream surface of the flowing gas, and the lower surface is the downstream surface. The angle provided in the pipe 5a is not limited to 45 degrees as long as the gas described above is within a range in which the gas can flow while turning in the main flow path 3a.

  Next, the behavior of gas will be described. When the gas flows in from the pipe 5a, the gas swirls along the inner wall of the perforated plate 4. Then, centrifugal force is applied to the gas and it tries to spread outward. For this reason, the gas flow passes through the through holes 4 a provided in the porous plate 4. And when the gas flow passes through the through-hole 4a, the sound wave superimposed on the gas flow is greatly absorbed in each stage. The gas that has passed through the through-hole 4a flows through the auxiliary flow path 3b, merges with the gas flowing through the main flow path 3a on the downstream side, and flows out from the pipe 5b.

  As described above, the silencer 1 according to the first embodiment of the present invention includes the silencer main body 2 that circulates gas (fluid), the main flow path 3a and the sub flow channel that are joined at the downstream end. The porous plate 4 (partition member) provided in the silencer body so as to form the flow path 3b on the inner side and the outer side, and the gas flows into the main flow path 3a so that the gas flows while swirling the main flow path 3a And a through hole 4a that is provided in the perforated plate 4 and allows a part of the gas flowing through the main flow path 3a to pass through the sub flow path 3b.

  According to this configuration, the gas flows along the main flow path 3a while swirling along the inner peripheral surface of the partition member. Therefore, the gas tends to spread outward due to centrifugal force, and the gas passes through the hole 4a provided in the porous plate 4. Can be easily passed. When the sound wave passes through the through-hole 4a, the viscous action on the hole wall surface can obtain the attenuation (silence) effect of the sound wave superimposed on the gas flow. When the gas flow on which the sound wave is superimposed passes through the through-hole, the viscous action occurs. In addition, the sound attenuation (silence) effect superimposed on the flow can be significantly increased by the pressure loss action of the flow. Thereby, the silencer 1 having sufficient silencing performance can be realized in a space-saving manner. Moreover, in order to flow gas to the through-hole 4a, the centrifugal force by turning an airflow is utilized, and resistance with respect to the flow of the gas in the main flow path 3a of the perforated plate 4 provided with the through-hole 4a is reduced. Can do.

  Moreover, since the silencer main body 2 and the perforated plate 4 (partition member) are cylindrical, the flowing gas (fluid) is easy to swirl. Thereby, it becomes easier to pass through the through-hole 4a, and the sound wave can be silenced more reliably. The silencer 1 is easy to recycle because it does not use difficult-to-recycle materials such as glass wool that had to be disposed of as industrial waste.

  Moreover, although this invention was demonstrated based on suitable embodiment, this invention can be changed in the range which does not exceed the meaning. That is, in this Embodiment, although the silencer main body 2 and the perforated plate 4 are made into the cylindrical shape, it is not limited to this. Any shape that allows gas to flow while swirling may be used. Moreover, although the piping 5a is arrange | positioned diagonally so that gas may rotate and distribute | circulate the main flow path 3a, it is not limited to this. For example, as shown in FIG. 2, the pipes 5 a and 5 b may be arranged perpendicular to the silencer body 2. In this case, the gas flowing horizontally into the silencer body 2 hits the perforated plate 4 and swirls along the inner wall of the perforated plate 4.

  Further, as shown in FIG. 3, the pipe 5a is arranged without providing an angle, the pipes 5a and 5b and the main flow path 3a are formed in a straight line, and the swirl plate 7 is placed at the inlet of the main flow path 3a. It may be arranged obliquely with respect to the traveling direction, and the gas may be swirled to flow into the main flow path 3a. In this case, since the piping can be formed in a straight line, it can be easily created and the durability is improved. The swivel plate 7 may have any shape that can swirl the gas.

  Further, as shown in FIG. 4, an auxiliary porous plate 4 b (auxiliary partition member) provided with a through hole 4 c (passing hole) through which gas passes is disposed so as to surround the porous plate 4 with a space therebetween. A double structure using a perforated plate may be used. Thereby, it is possible to greatly mute the sound in a wider frequency range by the synergistic effect of the two perforated plates.

(Second Embodiment)
Next, a silencer according to the second embodiment of the present invention will be described. As shown in FIG. 5, the silencer 10 according to the present embodiment reflects sound waves superimposed on the gas flowing through the sub-flow channel 3 b to the sub-flow channel 3 b of the silencer 1 of the first embodiment. Thus, a plurality of plate-like blocking plates 8 (blocking members) are arranged in the axial direction. The blocking plate 8 is arranged so that gas can flow downstream. By disposing the blocking plate 8, the frequency at which the sound waves resonate in the sub-flow path 3 b that hinders the silencing effect by the perforated plate can be increased, and the sound can be silenced to a higher frequency. The blocking plate 8 may not be plate-shaped as long as it can block a part of the gas.

  The blocking plate 8 satisfies the relationship b = <c / (2f), where f is the highest frequency of the sound wave to be silenced, c is the velocity of the sound wave in the gas, and b is the arrangement interval b of the blocking plate 8. It is preferable that they are arranged. This can surely prevent resonance from occurring at a frequency f or lower by setting the interval between the blocking plates 8 to be equal to or shorter than a half wavelength of a sound wave having the highest frequency f. The arrangement interval b of the blocking plates 8 preferably satisfies the above equation, but the interval b may be non-uniform, and even if the sound wave includes various frequencies, the sound can be silenced in a wide band.

  Although not shown, a plurality of blocking plates 8 may be arranged in the circumferential direction in the sub flow path 3b. Thereby, the subchannel 3b is formed with a plurality of small chambers in the circumferential direction. In this case, resonance in the circumferential direction can be prevented.

  As described above, the silencer 10 according to the present embodiment can silence sound waves up to a higher frequency in addition to the effects of the first embodiment.

  Next, in order to confirm the increase in the sound absorbing effect of the perforated plate by passing the gas flow superimposed with sound waves through the through hole in the first embodiment, the following test was performed using an apparatus as shown in FIG. Went. That is, a porous plate 100 having a through hole 100a similar to the porous plate 4 of the silencer 1 shown in FIG. 1 is disposed in a cross section in the cylinder 101 having a hole 101a for flowing in gas and a hole 101b for flowing out. . Then, at the same time as the gas is circulated from the hole 101a, a sound wave is emitted from the speaker 104, and the sound wave enters the perforated plate 100 together with the gas. The gas is discharged from the hole 101b. And the sound pressure was measured by the microphone 102 at two locations in the cylinder 101, and the sound absorption coefficient by the perforated plate was calculated. FIG. 7 shows that, based on the above test results, the horizontal axis represents the sound wave frequency (unit: Hz), the vertical axis represents the sound absorption coefficient, and the velocity of the flow through the through hole 100a is 0, 2, 4, 8 m / s. It is a graph of the case. A velocity of 0 m / s means that there is no gas flow.

  Further, the piston 103 is movable in the axial direction, the distance from the perforated plate 100 can be changed, and corresponds to the width of the sub-flow channel 3b of the first embodiment. By changing this distance, a frequency at which a particularly large sound absorption effect can be obtained can be set. The porous plate 100 used in this test had a plate thickness of 0.8 mm, a through hole 100a diameter of 2.0 mm, an aperture ratio of 5%, and the distance between the piston 103 and the porous plate 100 was 350 mm.

  As can be seen from FIG. 7, the sound absorption coefficient of the perforated plate increases as the gas passes through the through hole 100a and the speed thereof increases. That is, it was confirmed that when the gas was passed through the perforated plate 4, the silencer performance of the silencer could be remarkably improved.

  The present invention can be applied not only to the above-described apparatus but also to a construction machine or a press machine using hydraulic pressure, a pipe portion where a liquid such as a pump circulates, or the like.

(A) Side perspective view of the silencer according to the first embodiment of the present invention. (B) Top view of the silencer according to the first embodiment of the present invention. The figure which shows the modification of the 1st Embodiment of this invention. The figure which shows another modification of the 1st Embodiment of this invention. The figure which shows another modification of the 1st Embodiment of this invention. The side see-through | perspective view of the silencer which concerns on the 2nd Embodiment of this invention. The test equipment figure for confirming the effect at the time of flowing gas into a perforated board. The graph which shows the test result of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silencer 2 Silencer body 3 Flow path 3a Main flow path 3b Sub flow path 4 Perforated plate 4a Through hole 5a, 5b Piping

Claims (5)

A silencer body that circulates fluid,
A partition member provided in the silencer body so as to form the main flow path and the sub flow path merged at the downstream end on the inside and the outside;
Swirl starting means for causing the fluid to flow into the main flow path so that the fluid flows while swirling the main flow path;
A muffler provided in the partition member and having a through hole through which a part of the fluid flowing in the main channel passes through the sub channel.   The silencer according to claim 1, wherein the partition member has a cylindrical shape.   3. The silencer according to claim 1, further comprising an auxiliary partition member that is disposed so as to surround the partition member at an interval and is provided with a passage hole through which the fluid passes. .   4. The apparatus according to claim 1, further comprising: a blocking member provided to reflect a sound wave superimposed on the fluid flowing through the sub-flow channel, and to allow the fluid to flow downstream. The silencer described in the section. 5. The relationship of b = <c / (2f) is satisfied, where f is a maximum frequency of noise to be silenced, c is a sound velocity of the sound wave, and b is an interval between the blocking members. Silencer.

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