JP4567372B2 - Silencer - Google Patents

Description

  The present invention relates to a silencer in an apparatus or a pipe line for intake or exhaust between the apparatuses.

  Conventionally, as a general silencer in a compressor or the like, an expansion silencer provided with an expansion chamber having a diameter larger than the diameter of the main pipe or a resonance silencer such as a side branch has been used.

  Patent Document 1 discloses a porous material having a porosity of 40 to 60% in which a part of a gas flowing into a housing having a diameter larger than that of the main pipe is installed at an angle of 15 to 45 ° with respect to the flow direction. By passing the gas through the partition wall and passing the main flow part of the gas through the hole formed in the center of the porous partition wall, the rapid expansion of the gas is suppressed and the temperature is lowered, thereby generating explosion sound. Disclosed is a silencer that suppresses sound and attenuates sound by the resonance principle using a silencer chamber formed between porous partition walls, and provides a wide range of sound attenuation by providing different sizes of silencer chambers. Has been.

JP-A-8-151918

  However, the silencing device of Patent Document 1 has a problem that a large silencing effect in a wide band cannot be obtained because the porosity (opening ratio) of the porous partition walls is as large as 40 to 60%. In addition, since the gas that has not passed through the porous partition walls easily flows into the silencing chamber formed between the porous partition walls, there is a problem that the silencing effect based on the resonance principle is reduced. Furthermore, although the silencing effect is conspicuous by providing a plurality of porous partition walls, there is a problem that the cost increases as the number of installed partitions increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a silencer capable of reducing broadband sound waves at low cost.

Means and effects for solving the problems

The silencer of the present invention includes a silencer body having a main space through which a main flow portion of fluid containing sound waves passes, and a sub space connected to the main space and through which the tributary portion of the fluid passes, and the sub space. A partition plate that is inscribed in the silencer main body and has a plurality of through-holes that allow the fluid tributary portion to pass from the upstream side to the downstream side; and an inner wall provided from the partition plate to the downstream side of the partition plate The hole diameter of each through hole is set to 0.2 mm or more and 1 mm or less, and the inner wall has a partition for an intermediate chamber that forms an intermediate chamber on the downstream side of the partition plate, said intermediate chamber, a tributary of the fluid passing through the through-holes are formed so as to join the main portion of the fluid, the intermediate chamber partition wall is that having a through-hole.

According to the present invention, the branch portion of the fluid passing through the through hole passes through the through hole as a fluid containing sound waves. The branch portion of the fluid is separated from the main flow portion of the fluid passing through the main space by the inner wall. The fluid tributary portion flows into a space portion formed between the partition plate and the inner wall and not affected by the fluid main flow portion. As a result, the sound wave can be reduced by the dynamic pressure loss and the viscous resistance when the fluid containing the sound wave passes through the through hole.
In addition, the intermediate chamber can be a space that is not affected by the main flow portion of the fluid, and the fluid pressure loss and viscosity resistance due to the passage of the fluid tributary portion as a fluid containing sound waves through the through hole, Sound waves contained in the tributaries can be reduced. Further, by forming the intermediate chamber, it is possible to obtain a silencing effect based on the Helmholtz resonance principle.
In addition, since the branch portion of the fluid that has passed through the through hole of the partition plate flows into the intermediate chamber and is discharged from the intermediate chamber to the main flow portion of the fluid, the branch portion of the fluid passes through the through hole as a fluid containing sound waves. The state to perform is performed continuously. Thereby, the reduction of the sound wave by the dynamic pressure loss and the viscous resistance when the fluid containing the sound wave passes through the through hole can be continuously realized.
In addition, since the tributary part of the fluid that has passed through the through hole of the partition plate flows into the intermediate chamber and is discharged from the through hole of the partition for the intermediate chamber to the main fluid part of the fluid, the tributary part of the fluid is a fluid containing sound waves. The state of passing through the through hole is continuously performed. This reduces the sound pressure due to the dynamic pressure loss and viscous resistance when the fluid containing sound waves passes through the through hole of the partition plate, and the dynamic pressure loss and viscous resistance when passing through the through hole of the partition for the intermediate chamber. Reduction of sound waves can be continuously realized.
The silencer of the present invention includes a silencer body having a main space through which a main flow portion of a fluid containing sound waves passes, and a sub space connected to the main space and through which the branch portion of the fluid passes, A partition plate provided in the space and having a plurality of through holes inscribed in the silencer main body and passing the fluid tributary portion from the upstream side to the downstream side; and provided from the partition plate to the downstream side of the partition plate. The inner wall has a partition wall for an intermediate chamber that forms an intermediate chamber downstream of the partition plate. The intermediate chamber is formed so that the branch portion of the fluid that has passed through each through hole merges with the main flow portion of the fluid, and the intermediate chamber has an opening that opens to the main space side. Have.
According to the present invention, the branch portion of the fluid passing through the through hole passes through the through hole as a fluid containing sound waves. The branch portion of the fluid is separated from the main flow portion of the fluid passing through the main space by the inner wall. The fluid tributary portion flows into a space portion formed between the partition plate and the inner wall and not affected by the fluid main flow portion. As a result, the sound wave can be reduced by the dynamic pressure loss and the viscous resistance when the fluid containing the sound wave passes through the through hole.
In addition, the intermediate chamber can be a space that is not affected by the main flow portion of the fluid, and the fluid pressure loss and viscosity resistance due to the passage of the fluid tributary portion as a fluid containing sound waves through the through hole, Sound waves contained in the tributaries can be reduced. Further, by forming the intermediate chamber, it is possible to obtain a silencing effect based on the Helmholtz resonance principle.
In addition, since the branch portion of the fluid that has passed through the through hole of the partition plate flows into the intermediate chamber and is discharged from the intermediate chamber to the main flow portion of the fluid, the branch portion of the fluid passes through the through hole as a fluid containing sound waves. The state to perform is performed continuously. Thereby, the reduction of the sound wave by the dynamic pressure loss and the viscous resistance when the fluid containing the sound wave passes through the through hole can be continuously realized.
In addition, since the branch portion of the fluid that has passed through the through hole of the partition plate flows into the intermediate chamber and is discharged from the opening of the intermediate chamber to the main flow portion of the fluid, the branch portion of the fluid penetrates as a fluid containing sound waves. The state of passing through the hole is continuously performed. Thereby, the reduction of the sound wave by the dynamic pressure loss and the viscous resistance when the fluid containing the sound wave passes through the through hole can be continuously realized.

  In the present invention, it is preferable that the cross-sectional area of the main space is equal to or larger than the cross-sectional area of the main pipe through which the fluid flowing into the silencer body passes. According to this, since the fluid passing through the main pipe flows into the silencer body without changing the flow area, it is possible to prevent an increase in fluid resistance of the fluid passing through the silencer body.

  In this invention, it is preferable that the said partition plate is set to the range whose aperture ratio is about 1% or more and 10% or less. According to this, the silencing effect due to the viscous resistance when the fluid passes through the through hole can be made remarkable.

  Hereinafter, embodiments of a silencer according to the present invention will be described with reference to the drawings.

[First Embodiment]
The configuration of the silencer according to the first embodiment of the present invention will be described with reference to FIG. In addition, it demonstrates as what uses gas as a fluid.

  As shown in FIG. 1, the silencer 10 includes a housing (silencer body) 1 provided in connection with a main pipe 14 through which a gas containing sound waves passes, and partitions provided in subspaces 12 and 12 described later. It has the board | plates 4 and 4 and the inner walls 6 and 6 similarly provided in the subspaces 12 and 12. FIG.

  The housing 1 is cylindrical and has a main space 11 having the same cross-sectional area as the main pipe 14 and subspaces 12 and 12 connected to the main space 11 so as to surround the outer periphery of the main space 11. The main flow part of the gas flowing into the housing 1 from the inlet 2 passes through the main space and flows out of the housing 1 as it is from the outlet 3. The tributary part of the gas that has flowed into the housing 1 passes through the subspaces 12, 12, merges with the main gas flow part, and flows out of the housing 1 from the outlet 3. Thus, since the gas that has passed through the main pipe 14 is configured to flow into the housing 1 without changing the flow area, the gas that has passed through the main pipe 14 does not increase its fluid resistance. Flow into. In the subspaces 12, 12, partition plates 4, 4 and inner walls 6, 6 are provided. The shape of the housing 1 is not limited to a cylindrical shape, and the cross-sectional shape may be a square, a triangle, or the like.

  The partition plates 4 and 4 are provided in the subspaces 12 and 12 so as to be inscribed in the housing 1 and orthogonal to the gas flow direction. A plurality of through holes 5 and 5 are formed in the partition plates 4 and 4. Therefore, the tributary part of the gas passing through the subspaces 12 and 12 flows through the through holes 5 and 5 in the downstream direction. The hole diameter of the through holes 5 and 5 is not particularly limited, but is set to 1 mm or less in order to obtain the effects described below. Moreover, the shape of the through holes 5 and 5 may be an elliptical shape, a rectangular shape, a polygonal shape, or a slit shape, and various shapes may be mixed between or inside the through holes 5 and 5. Furthermore, the through holes 5 and 5 may be set to the same size and diameter, and various sizes and diameters may be mixed between and inside the through holes 5 and 5. When various sizes and diameters are mixed, the frequency bandwidth that exhibits the sound absorption effect described later can be expanded.

  The inner walls 6, 6 are connected to the partition plates 4, 4 and are on the downstream side separated from the partition walls 4, 4 by a distance d from the main walls 7, 7 provided on the downstream side of the partition plates 4, 4. The intermediate chamber partition walls 8 and 8 are provided so as to be inscribed in the housing 1 and perpendicular to the gas flow direction. Between the main walls 7 and 7 and the intermediate chamber partition walls 8 and 8, openings 13 and 13 are opened toward the main space 11. Intermediate chambers 9 and 9 are formed in the subspaces 12 and 12 by the inner walls 6 and 6 and the partition plates 4 and 4. Therefore, the tributary part of the gas that has flowed downstream through the through holes 5 and 5 of the partition plates 4 and 4 flows into the intermediate chambers 9 and 9 that are not affected by the main stream part of the gas passing through the main space 11. Then, it flows to the downstream side by the distance d, flows out from the openings 13 and 13 to the outside of the intermediate chambers 9 and 9, and joins the main flow portion of the gas passing through the main space 11. When the tributary part of the gas flowing at a constant flow velocity passes through the through holes 5 and 5 and flows into the intermediate chambers 9 and 9, the pressure loss resistance (dynamic pressure loss) due to the through holes 5 and 5 ) This dynamic pressure loss is generally known as a dynamic pressure loss according to Bernoulli's law, and when the fluid passes through a hole such as a through hole, the pressure of the fluid is lost, and the sound wave of the fluid is generated. A resistance is received, and the vibration energy of the sound wave is converted into heat energy by this resistance, and the sound wave is reduced. This dynamic pressure loss causes a silencing action, and the tributary part of the gas passing through the through holes 5 and 5 is silenced in a wide band. In addition, viscous resistance due to the through holes 5 and 5 is generated in the tributary part of the gas passing through the through holes 5 and 5. A silencing action is generated by this viscous resistance, and the tributary part of the gas passing through the through holes 5 and 5 is silenced. Here, by setting the opening ratio of the partition plates 4 and 4 in the range of about 1% or more and 10% or less, the silencing effect due to the viscous resistance when the gas tributary part passes through the through holes 5 and 5 becomes remarkable. can do. The silencing effect due to the dynamic pressure loss and the silencing effect due to the viscous resistance are continuously realized while the gas tributary portion passes through the through holes 5 and 5 continuously.

  In addition, it is preferable that the lower limit of the diameter of the through-holes 5 and 5 is 0.2 mm. This is because when the diameter of the through-holes 5 and 5 approaches 0, the peak of the sound absorption coefficient tends to increase due to the viscous effect, but in reality, the peak of the sound absorption coefficient does not reach 1.0. When the diameter is extremely small, such as 0.2 mm or less, the viscosity of the tributary part of the gas passing through the through holes 5 and 5 becomes too large, so that the resistance to the flow of the tributary part of the gas passing through the through holes 5 and 5 This is because it is considered that the sound absorption rate is lowered. In addition, if the diameter is extremely small, such as 0.2 mm or less, the manufacture becomes significantly difficult, and the through holes 5 and 5 are likely to be blocked by dust or dust depending on the use environment.

  Further, the distance d from the partition plates 4 and 4 to the intermediate chamber partition walls 8 and 8, which is the space layer thickness of the intermediate chambers 9 and 9, the aperture ratio of the partition plates 4 and 4, and the plate thickness of the partition plates 4 and 4 And the hole diameters of the through holes 5 and 5 are set so as to satisfy the Helmholtz resonance principle for sound waves having a frequency to be muffled.

  The Helmholtz resonance principle has a general formula of “f = (c / 2π) × √ {β / (t + 1.6b) d}”, and the sound velocity c, the aperture ratio β of the partition plates 4 and 4, and the partition plates 4 and 4 are used. The resonance frequency f is shown using the plate thickness t, the hole diameter b of the through holes 5 and 5, and the space layer thickness d of the intermediate chambers 9 and 9 as parameters. These parameters cause a silencing effect due to the viscous resistance described above. Due to this Helmholtz resonance principle, the sound waves of the resonance frequency f contained in the sub-spaces 12 and 12 and in the gas branch located upstream of the partition plates 4 and 4 are muted. Due to the synergistic effect of the silencing action by viscous resistance and the silencing action by the Helmholtz resonance principle, the silencing effect is exhibited in a wide frequency band where the frequency bandwidth where the sound absorption coefficient is 0.3 or more is 10% or more with respect to the resonance frequency f. Can be made. The silencing effect based on the Helmholtz resonance principle is continuously realized while the gas tributary part continuously passes through the subspaces 12 and 12.

  The parameters of the silencer are the aperture ratio β in the partition plates 4 and 4 when the space layer thickness d is 10 mm to 50 mm so as to have a synergistic effect of the silencing action by the viscous resistance and the silencing action by the Helmholtz resonance principle. Is 3% or less, the plate thickness t of the partition plates 4 and 4 is 0.3 mm or more, and the hole diameter b of the through holes 5 and 5 is preferably set to 1 mm or less.

  The housing 1, the partition plates 4 and 4, and the inner walls 6 and 6 are formed of a metal such as iron or aluminum or a synthetic resin. Moreover, it is desirable that these are formed of the same material so that the separation process at the time of recycling is unnecessary.

  Next, the operation of the silencer in the above configuration will be described.

  The gas flowing into the housing 1 from the inflow port 2 flows into the housing 1 as a flow including sound waves generated by a noise generation source before the inflow. The main flow portion of the gas passes through the main space 11 of the housing 1 and flows out of the housing 1 through the outlet 3 as it is. On the other hand, the gas tributary part passes through the subspaces 12 and 12.

  First, the sound velocity c, the aperture ratio β of the partition plates 4 and 4, the plate thickness t of the partition plates 4 and 4, the hole diameter b of the through holes 5 and 5, and the space layer thickness d of the intermediate chambers 9 and 9 are used as parameters. According to the Helmholtz resonance principle, the sound waves having the resonance frequency f of the sub-spaces 12 and 12 and the gas branch located upstream of the partition plates 4 and 4 are muted. Thereafter, the gas tributary part flows toward the partition plates 4 and 4.

  Next, the gas tributary part is subjected to viscous action by the through holes 5 and 5 when the through holes 5 and 5 of the partition plates 4 and 4 are penetrated. Thereby, the sound wave which the tributary part of the gas which passes the through-holes 5 and 5 has is reduced.

  Further, since the gas tributary part flows with a constant flow, the gas tributary part is subjected to a dynamic pressure loss when passing through the through holes 5 and 5. Also by this, the sound wave which the tributary part of the gas which passes through the through-holes 5 and 5 has is reduced.

  Then, the tributary part of the gas that has passed through the through holes 5, 5 flows into the intermediate chambers 9, 9, and is downstream of the intermediate chambers 9, 9 without being affected by the main stream part of the gas that passes through the main space 11. And flow. The gas tributary part flows out of the intermediate chambers 9 and 9 from the openings 13 and 13, merges with the gas main flow part passing through the main space 11, and flows out of the housing 1 from the outlet 3.

  Next, in order to confirm the silencing effect due to the dynamic pressure loss of the silencer in the present embodiment, the following test was performed. That is, an acoustic tube 51 for measuring the normal incident sound absorption coefficient as shown in FIG. 2 is prepared, and the opening ratio β is 5%, the plate thickness t is 0.8 mm, and the hole diameter b is A perforated plate 54 having a through hole 55 of φ2 mm is installed, the working wall 56 is adjusted so that the air layer thickness d of the intermediate chamber 59 is 350 mm, a gas not containing sound waves is introduced from the inlet 52, and the outlet 53 is Gas was allowed to flow out. At the same time, white noise is generated from the speaker 57 arranged on the end face of the acoustic tube 51 on the inlet 52 side, and the normal incident sound absorption coefficient (reflection sound from the wall) is measured by two microphones 58 provided adjacent to the acoustic tube. did.

  As a result, as shown in the sound absorption coefficient measurement result of FIG. 3, when the gas flow velocity at the inlet 52 is changed to 0 m / s, 2 m / s, 4 m / s, and 8 m / s, the Helmholtz is at 0 m / s. Compared to the normal incident sound absorption coefficient obtained by the resonance principle and the viscous action of the through-hole 55, the normal incident sound absorption coefficient is clearly improved by adding the dynamic pressure loss effect to the gas, and the normal incident sound absorption coefficient increases as the flow velocity increases. It turns out that it improves.

[Second Embodiment]
The structure of the silencer 20 which concerns on 2nd Embodiment of this invention is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment, and the description is abbreviate | omitted. The configuration of the second embodiment is different from that of the first embodiment in that a plurality of through holes 31 and 31 similar to the partition plates 4 and 4 are also perforated in the intermediate chamber partition walls 28 and 28, and an opening is provided. The main walls 27, 27 and the intermediate chamber partition walls 28, 28 are joined together. The through holes 31, 31 are the same as the through holes 5, 5.

  The operation of the silencer 20 in the above configuration will be described. Of the gas containing sound waves flowing into the housing 1 from the inflow port 2, the tributaries of the gas passing through the subspaces 12, 12 are the subspaces 12, 12 and are located upstream of the partition plates 4, 4. Sometimes the sound is muted by the silencing effect of the Helmholtz resonance principle. Further, the gas tributary part is silenced by the viscous action and the dynamic pressure loss when passing through the through holes 5 and 5 of the partition plates 4 and 4, and then flows through the intermediate chambers 29 and 29 to flow through the intermediate chamber partition walls 28 and 29. 28 is reached. And when penetrating the through holes 31, 31 of the intermediate chamber partition walls 28, 28, the sound is further silenced by the viscous action and the dynamic pressure loss by the through holes 31, 31. The tributary part of the gas passing through the through holes 31, 31 joins the main part of the gas passing through the main space 11 and flows out of the housing 1 from the outlet 3. Since other points are the same as those of the first embodiment, description thereof is omitted.

[Third Embodiment]
A configuration of a silencer according to a third embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment, and the description is abbreviate | omitted. The configuration of the third embodiment is different from the first embodiment in that there is no opening, the main walls 37 and 37 and the intermediate chamber partition walls 38 and 38 are joined, and the downstream side of the intermediate chambers 39 and 39 is closed. It is a point.

  The operation of the silencer 30 in the above configuration will be described. When the gas flowing into the housing 1 from the inlet 2 is accompanied by a transient flow or pressure fluctuation, a pressure difference is generated between the intermediate chambers 39 and 39 and the subspaces 12 and 12. If the pressure of 39,39 is smaller than the pressure of subspace 12,12, the tributary part of gas will flow from subspace 12,12 to the intermediate chambers 39,39, and will pass through-hole 5,5 of partition plates 4,4. When passing, a silencing effect due to dynamic pressure loss and viscous resistance can be obtained. On the other hand, if the pressure in the subspaces 12 and 12 is smaller than the pressure in the intermediate chambers 39 and 39, the gas tributary part flows from the intermediate chambers 39 and 39 to the subspaces 12 and 12 and the through holes of the partition plates 4 and 4. When passing 5 and 5, a silencing effect due to dynamic pressure loss and viscous resistance can be obtained. Since the gas tributary part receives a dynamic pressure loss at the through holes 5 and 5 of the partition plates 4 and 4, a sound pressure difference is generated before and after the partition plates 4 and 4. During the period in which the sound pressure difference occurs, the gas tributary portion flows from the higher pressure to the lower pressure, and the silencing effect due to the viscous action by the through holes 5 and 5 and the dynamic pressure loss is exhibited. Further, due to the intermediate chambers 39, 39 closed on the downstream side, a silencing effect based on the Helmholtz resonance principle is exhibited in the sub-spaces 12, 12 and in the gas tributary portion located upstream of the partition plates 4, 4. However, if the pressure in the intermediate chambers 39 and 39 is the same as the pressure in the subspaces 12 and 12, the gas tributary part no longer flows into the intermediate chambers 39 and 39 and also into the subspaces 12 and 12. Thus, the silencing effect due to the dynamic pressure loss and the viscous resistance and the silencing effect due to the Helmholtz resonance principle are not exhibited.

  Such a silencer 30 is suitably used as a silencer for an engine or apparatus in which the gas flow rate changes. That is, as the pressure of the gas flowing into the housing 1 rises, the pressure in the intermediate chambers 39 and 39 rises as the gas tributary flows into the intermediate chambers 39 and 39 and moves accordingly. The silencing effect due to the pressure loss and viscous resistance and the silencing effect due to the Helmholtz resonance principle are also exhibited, and the tributary part of the gas is silenced, and when the pressure of the gas flowing into the housing 1 is reduced, the intermediate chambers 39 and 39 are accumulated. When the gas tributary part flows out of the intermediate chambers 39, 39, the pressure in the intermediate chambers 39, 39 also decreases, and accordingly, the silencing effect due to dynamic pressure loss and viscous resistance and the silencing effect due to the Helmholtz resonance principle. Is also exerted to mute the tributary part of the gas. Then, as the pressure of the gas flowing into the housing 1 rises again, the gas tributary part flows into the intermediate chambers 39, 39, so that the pressure in the intermediate chambers 39, 39 also rises. Transient gas generated by an engine or device that changes the flow rate of the gas, such as the silencing effect due to loss and viscous resistance, and the silencing effect due to the Helmholtz resonance principle are also demonstrated, and the tributary part of the gas is muted. It is possible to exert a silencing effect repeatedly with flow and pressure fluctuations. Since other points are the same as those of the first embodiment, description thereof is omitted.

  As described above, the silencer of the present embodiment is provided with a partition plate in which a through hole is drilled in a subspace of a housing that is thicker than the main pipe, and an inner wall is provided from the partition plate to the downstream side of the partition plate. By forming an intermediate chamber that is not affected by the main flow part of the gas that passes through the main space, the sound is silenced by the dynamic pressure loss and viscous resistance caused by the through hole when the gas tributary part passes through the through hole. It is configured. In addition, the space layer thickness of the intermediate chamber, the aperture ratio of the partition plate, the plate thickness of the partition plate, and the hole diameter of the through hole satisfy the Helmholtz resonance principle for sound waves of the frequency to be silenced. Since they are respectively set, they are sub-spaces, and are configured such that a silencing effect based on the Helmholtz resonance principle is exhibited in a gas tributary part located upstream of the partition plate. Thereby, the silencer which can reduce a broadband sound wave is realizable at low cost.

  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, as shown in FIG. 6, another sound absorbing structure 40 may be connected downstream of the silencer 10 having the configuration of the first embodiment. The sound absorbing structure 40 has a cylindrical pipe line 41 having a diameter larger than that of the main flow pipe 14 and extends in the axial direction of the pipe path 41 inside the pipe path 41 so as to divide the pipe path cross section of the pipe path 41. The perforated plate 44 is formed. The perforated plate 44 is cylindrical and has a large number of holes 45, and the aperture ratio of the holes 45 is preferably about 1% or more and 10% or less. The sound absorbing structure 40 has a double structure as described above, and the gas passing through the perforated plate 44 is silenced by the silencing effect of viscous action and dynamic pressure loss and the silencing effect by the Helmholtz resonance principle. Can be improved. A sound absorbing structure 40 may be provided downstream of the silencers 20 and 30 having the configuration of the second and third embodiments.

  Moreover, the structure by which the intermediate chamber of 1st-3rd embodiment was continuously provided in the circumferential direction in the housing may be sufficient. The intermediate chambers arranged in the circumferential direction may be the same type of intermediate chambers or different types of intermediate chambers. In particular, when different types of intermediate chambers are provided in the circumferential direction, the space layer thickness of the intermediate chamber, the aperture ratio of the partition plate, the plate thickness of the partition plate, and the hole diameter of the through hole are different for each intermediate chamber. Since the frequency corresponding to each intermediate chamber can be made different, it is possible to mute sound waves in a wider frequency range. Moreover, the structure by which the intermediate | middle chamber of 1st-3rd embodiment was continuously provided in the axial direction in the housing may be sufficient, and you may combine with the structure which provided the different intermediate | middle chamber in the circumferential direction.

  In the first embodiment, the inner walls 6 and 6 may be the main walls 7 and 7 alone, and the intermediate chamber partition walls 8 and 8 may not be provided. In this case, the silencing effect of the Helmholtz resonance principle by the intermediate chambers 9 and 9 is not exhibited, but the silencing effect of the dynamic pressure loss and the viscous resistance by the through holes 5 and 5 of the partition plates 4 and 4 is exhibited and the through hole 5 5 is silenced. Even if it is the structure where both of the two intermediate chamber partition walls 8 and 8 are not installed, the structure where either one is not installed may be used.

  In the first to third embodiments, the cross-sectional area of the main space 11 of the housing 1 may be smaller than the cross-sectional area of the main pipe 14. Further, the sectional area of the housing 1 may be smaller than the sectional area of the main pipe 14. In this case, the gas that has passed through the main pipe 14 increases its fluid resistance when flowing into the housing 1, but the dynamic pressure loss is well controlled by increasing the diameter of the through holes 5, 5. It functions as a silencer.

  The silencer according to the present invention has a moving device, a motor and a gear provided with a driving mechanism such as an engine, such as an automobile, a railway vehicle, a construction vehicle, a ship, and an automatic transfer device, if the fluid passing therethrough is a gas. It can be suitably used as a soundproof cover for equipment machines equipped with a drive mechanism such as the above. Further, if the fluid passing through the silencer is a liquid, it can be suitably used for a machine using hydraulic pressure such as a construction machine or a press machine.

It is sectional drawing which showed the silencer which concerns on 1st Embodiment of this invention. It is sectional drawing of the acoustic tube used in order to test the effect of the silencer of this invention. It is a graph showing the test result of the effect of the silencer of the present invention. It is sectional drawing which showed the silencer which concerns on 2nd Embodiment of this invention. It is sectional drawing which showed the silencer which concerns on 3rd Embodiment of this invention. It is sectional drawing which showed the modification of the silencer which concerns on 1st Embodiment of this invention.

Explanation of symbols

1 Housing (muffler body)
2 inflow port 3 outflow port 4 partition plate 5 through-hole 6 inner wall 7 main wall 8 partition wall for intermediate chamber 9 intermediate chamber 10 silencer 11 main space 12 subspace 13 opening 14 main pipe 40 sound absorption structure 41 piping path 44 perforated plate 45 hole 51 acoustic tube 52 inlet 53 outlet 54 perforated plate 55 through hole 56 working wall 57 speaker 58 microphone 59 intermediate chamber

Claims (4)

A silencer body having a main space through which a main flow portion of a fluid containing sound waves passes, and a sub space connected to the main space and through which a tributary portion of the fluid passes;
A partition plate provided in the sub-space, and having a plurality of through holes that are inscribed in the silencer main body and pass the branch portion of the fluid from the upstream side to the downstream side;
An inner wall provided from the partition plate to the downstream side of the partition plate;
Have
The hole diameter of each through hole is set to 0.2 mm or more and 1 mm or less ,
The inner wall has an intermediate chamber partition wall that forms an intermediate chamber downstream of the partition plate;
The intermediate chamber is formed so as to merge the branch portion of the fluid that has passed through each through hole with the main flow portion of the fluid,
Muffler said intermediate chamber partition wall is characterized Rukoto to having a through-hole.   A silencer body having a main space through which a main flow portion of a fluid containing sound waves passes, and a sub space connected to the main space and through which a tributary portion of the fluid passes;
  A partition plate provided in the sub-space, and having a plurality of through holes that are inscribed in the silencer main body and pass the branch portion of the fluid from the upstream side to the downstream side;
  An inner wall provided from the partition plate to the downstream side of the partition plate;
Have
  The hole diameter of each through hole is set to 0.2 mm or more and 1 mm or less,
  The inner wall has an intermediate chamber partition wall that forms an intermediate chamber downstream of the partition plate;
  The intermediate chamber is formed so as to merge the branch portion of the fluid that has passed through each through hole with the main flow portion of the fluid,
  The muffler, wherein the intermediate chamber has an opening that opens to the main space side. The silencer according to claim 1 or 2 , wherein a cross-sectional area of the main space is equal to or larger than a cross-sectional area of the main pipe through which a fluid flowing into the silencer body passes. The silencer according to any one of claims 1 to 3 , wherein the partition plate has an opening ratio set in a range of about 1% to 10%.

Images