JP2011058412A - Air flow passage radiation sound reducing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit radiation sounds generated in association with the air flow such as exhaust gas in an air passing pipe from leaking outside. <P>SOLUTION: In an air passage pipe 4, a rigidity reduced portion 12 comprising a pseudo cylindrical concave polyhedron is formed in a housing pipe 6. As a result, the pipe wall of the rigidity reduced portion 12 easily generates film vibrations by pressure vibrations acting from in the air passage pipe 4, and is able to thereby sufficiently transmit pressure vibrations via the pipe wall to a sound absorption material 8. In particular, if the relationship between the depth d of the unevenness of the surface of the pseudo cylindrical concave polyhedron and the thickness t of the member constituting the rigidity reduced portion 12 is d<√2t or d<2t, the member more flexibly deforms to easily generate significant film vibrations, whereby the pressure vibrations can be transmitted with higher efficiency to the sound absorption material 8 in solid-to-solid contact with the air passage pipe 4 to achieve the problem to be solved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention includes a vent pipe having an airflow passage inside and a storage pipe that accommodates the vent pipe in a non-contact state through a space, thereby reducing radiated sound caused by the airflow in the vent pipe. The present invention relates to an airflow passage radiated sound reduction structure.

  2. Description of the Related Art There is known an airflow passage radiated sound reduction structure that reduces radiated sound generated along with airflow in a vent pipe, for example, a silencer that reduces exhaust noise in an exhaust pipe of an internal combustion engine (see, for example, Patent Documents 1, 2, and 3). .

  In Patent Document 1, in a silencer comprising a metal tube having a small hole, a fibrous sound absorbing material disposed around the metal tube, and a shell covering the outside of the sound absorbing material, the metal tube and the fibrous material In which a woven fabric such as ceramic fiber is disposed between the sound absorbing materials.

  In Patent Document 2, a sound absorbing material is filled between an exhaust pipe having a large number of small holes and an outer cylinder surrounding the exhaust pipe, and one end of the outer cylinder and the exhaust pipe are slidable. A silencer is disclosed in which a plurality of band-like protrusions extending in the longitudinal direction are integrally provided on the exhaust pipe, and the end portions of the outer cylinder are supported by the protrusions.

  In Patent Document 3, a fitting end portion to be fitted to a silencer housing in at least one of the gas introduction pipes of the silencer is formed to have a larger diameter than a portion other than the fitting end portion, and a communication hole is formed in the gas introduction pipe. The cover pipe is disposed on the outer periphery of the cover pipe via a space, and one end of the cover pipe is fitted to the fitting end of the gas guiding pipe.

JP-A-8-260938 (page 2-3, FIG. 1) Japanese Utility Model Publication No. 5-916 (page 6-8, FIGS. 1, 2, 3 and 6) JP 2004-60523 A (page 3-5, FIGS. 1 and 2)

  However, in any of the patent documents, the noise component due to the pressure vibration of the exhaust gas is absorbed by the sound absorbing material through the through hole opened in the rigid tube wall of the exhaust passage, thereby reducing the exhaust noise. Therefore, the absorption efficiency by the sound absorbing material is low, and the entire length must be increased. For this reason, it is difficult to reduce the weight of the vehicle in an automobile or the like. Even if the distribution density of the through holes is increased, there is a limit to the direct transmission of the pressure vibration of the exhaust gas to the sound absorbing material. On the contrary, the pressure vibration may leak to the outside.

  An object of this invention is to suppress that the radiated sound which arises with the airflow in a vent pipe leaks outside.

In the following, means for achieving the above-mentioned purpose, and its operation and effect are described.
The airflow passage radiated sound reduction structure according to claim 1 includes a ventilation pipe having an airflow passage inside and a storage pipe that accommodates the ventilation pipe in a non-contact state through a space. An airflow passage radiated sound reduction structure for reducing radiated sound generated along with an airflow, wherein the vent pipe has one or both of a shape and a material other than a through hole in a tube wall in a region in the storage tube. Or it is characterized by low rigidity by both.

  As described above, in the ventilation pipe, the whole or a part of the pipe wall in the region in the storage pipe is reduced in rigidity by one or both of its shape and material. This low rigidity shape does not include the low rigidity due to the through hole, and even when the through hole exists, the rigidity is reduced in the portion other than the through hole.

  As described above, since the tube wall itself of the ventilation tube is made low in rigidity as described above, the tube wall easily generates membrane vibration due to pressure vibration acting on the tube wall from the airflow passage side. Therefore, regardless of the presence or absence of the through hole, the pressure vibration of the airflow acts on the tube wall of the vent pipe, so that the tube wall sufficiently absorbs the pressure vibration and vibrates itself.

  However, the storage pipe covering the ventilation pipe is not in contact with the ventilation pipe. For this reason, most of the pressure vibration energy of the airflow is used only to vibrate the tube wall of the vent pipe, and almost no vibration energy is transmitted from the tube wall to the storage tube side.

  For this reason, the pressure vibration energy of the airflow is consumed by changing to thermal energy only by the vent pipe, or if there is a sound absorbing material between the vent pipe and the storage pipe, the sound absorbing material also changes to thermal energy. Is done. As a result, the vibration of the storage tube is suppressed, and it is possible to suppress the radiated sound generated along with the air flow in the ventilation tube from leaking to the outside from the storage tube.

  The airflow passage radiated sound reduction structure according to claim 2 is provided with a ventilation pipe having an airflow passage inside and a storage pipe that accommodates the ventilation pipe in a non-contact state through a space. An airflow passage radiated sound reduction structure for reducing radiated sound generated along with an airflow, wherein the ventilation pipe has all or part of a tube wall in a region inside the storage pipe reduced in rigidity by a shape other than a through hole. It is characterized by.

In particular, since it is not necessary to depend on the material by reducing the rigidity according to the shape, the function and effect as described in the first aspect can be realized even by a conventionally used material.
The airflow passage radiated sound reducing structure according to claim 3 is characterized in that in the airflow passage radiated sound reducing structure according to claim 1 or 2, a sound absorbing material is arranged in a part or all of the space. .

  In particular, in a space, by arranging a sound absorbing material in part or all of it, if the sound absorbing material and the vent pipe are in contact, sufficient pressure vibration is applied to the sound absorbing material from the tube wall of the vent pipe that vibrates in the membrane. Can do. In other words, if the sound absorbing material and the ventilation pipe are in contact, the pressure vibration transmission between the pipe wall of the ventilation pipe and the sound absorbing material is between solids, so the pressure vibration is transmitted from the pipe wall to the sound absorbing material with high efficiency. The noise absorption efficiency of the sound absorbing material is increased. When the sound-absorbing material contains liquid, there is also the transmission of pressure vibration between the solid and the liquid in addition to the solid, but in this case, the pressure vibration is converted into thermal energy with high efficiency and the noise absorption efficiency Is further increased.

  When the sound absorbing material is not in contact with the vent pipe, the pressure vibration transmission from the vent pipe to the storage tube is not a problem, and the vibration is suppressed by the sound absorbing material. Can be sufficiently suppressed from leaking to the outside from the storage tube.

  In the airflow passage radiated sound reducing structure according to claim 4, in the airflow passage radiated sound reducing structure according to any one of claims 1 to 3, the vent pipe is provided on a tube wall in a region in the storage pipe. A through hole is formed.

  Even when the through hole is formed in the vent pipe as described above, the rigidity is reduced by one or both of the shape and material of the tube wall other than the through hole as described above, or the rigidity is reduced by the shape of the tube wall. Accordingly, the pressure vibration is converted into thermal energy by the ventilation pipe or by the ventilation pipe and the sound absorbing material before the vibration is transmitted to the storage pipe. As a result, the vibration of the storage tube is suppressed, and it is possible to suppress the radiated sound generated along with the air flow in the ventilation tube from leaking to the outside from the storage tube.

  The airflow passage radiated sound reducing structure according to claim 5, wherein the rigidity of the airflow passage radiated sound reducing structure according to any one of claims 1 to 4 is such that a tube wall of the vent pipe is in an axial direction. It is realized by having a stretchable structure.

  Thus, the reduction in rigidity can also be realized by making the tube wall of the ventilation tube easy to displace in the axial direction, and the tube wall can easily vibrate in the axial direction by pressure vibration. As a result, sufficient vibration of the vent pipe before vibration is transmitted to the storage pipe causes pressure vibration to be converted into thermal energy by the vent pipe or the vent pipe and the sound absorbing material, so that the vibration of the storage pipe is suppressed. It is possible to suppress the radiated sound generated along with the air flow in the vent pipe from leaking out of the storage pipe.

  In the airflow passage radiated sound reducing structure according to claim 6, in the airflow passage radiated sound reducing structure according to any one of claims 1 to 5, the low rigidity is achieved by the tube wall of the vent pipe being It is realized by being formed in a wavy shape in the axial direction of the vent pipe.

  Thus, the rigidity may be reduced by forming the tube wall in a wavy shape in the axial direction, and the tube wall of the ventilation tube is displaced in the axial direction or the shaft is shaken by pressure vibration. As described above, since the pressure vibration is converted into thermal energy before the vibration is transmitted to the storage tube, the vibration of the storage tube is suppressed, and the radiated sound generated by the air flow in the ventilation tube is generated from the storage tube. It is possible to suppress leakage into the water.

  In addition, since the pipe wall of the ventilation pipe is formed in a wavy shape in the axial direction, in the configuration in which the sound absorbing material is in contact with the pipe wall, the sound absorbing material is less likely to be displaced in the axial direction, and airflow path radiation noise is reduced. The durability of the structure is improved.

  In the airflow passage radiated sound reducing structure according to claim 7, in the airflow passage radiated sound reducing structure according to any one of claims 1 to 5, the low rigidity is achieved by changing the tube wall of the vent pipe to a polyhedron. It is realized by doing.

  Low rigidity can be realized by making the tube wall into a polyhedron. In the case of a polyhedron, there are cases where it is difficult to be crushed against external pressure depending on the type. However, in the polyhedron, the angle between the surfaces sandwiching the ridges changes, so that the polyhedron can be flexibly deformed against pressure vibration from the inside, and the entire polyhedron can expand or contract. Along with this, membrane vibration can be easily generated by the outer peripheral surface of the polyhedron, and pressure vibration is caused by sufficient vibration of the ventilation pipe before the vibration is transmitted to the storage pipe. Is converted into thermal energy. Thus, the vibration of the storage tube is suppressed, and it is possible to suppress the radiated sound generated along with the airflow in the ventilation tube from leaking to the outside from the storage tube.

  In addition, since the tube wall of the vent pipe is formed as a polyhedron, the sound absorbing material is less likely to be displaced by the corners of the polyhedron in the configuration in which the sound absorbing material is in contact with the tube wall, and the durability of the airflow passage radiation noise reduction structure is improved. Improves.

  An airflow path radiated sound reducing structure according to an eighth aspect is characterized in that in the airflow path radiated sound reducing structure according to the seventh aspect, the polyhedron is formed as a pseudo-cylindrical concave polyhedron.

  As a type that can be adopted as a polyhedron, a pseudo-cylindrical concave polyhedron can be given. Such a quasi-cylindrical concave polyhedron is more difficult to collapse than a mere cylinder when pressed from the outside, but it is not rigid against pressure fluctuations from the gas flowing inside the tube wall, and it deforms flexibly. Because it can respond by expanding and contracting, the rigidity can be reduced.

  The airflow path radiated sound reducing structure according to claim 9 is the airflow path radiated sound reducing structure according to claim 8, wherein the tube wall formed as the pseudo-cylindrical concave polyhedron has a depth d corresponding to the concave portion. The relationship with the wall thickness t is d <√2 · t.

  Such a relationship represents the range in which the pseudo-cylindrical concave polyhedron can be easily deformed by reducing the bending rigidity of the pseudo-cylindrical concave polyhedron from the viewpoint of the average value of the moment of inertia of the cross section at the pipe wall of the vent pipe. Thus, the pipe wall can be deformed more flexibly with respect to pressure fluctuations from the inside, and the rigidity can be reduced.

  In the airflow passage radiated sound reducing structure according to claim 10, in the airflow passage radiated sound reducing structure according to claim 8, the tube wall formed as the pseudo-cylindrical concave polyhedron has a depth d corresponding to the concave portion. The relationship with the wall thickness t is d <2.t.

  This relationship represents the range in which the pseudo-cylindrical concave polyhedron can be easily deformed by reducing the bending rigidity of the pseudo-cylindrical concave polyhedron from the viewpoint of the minimum value of the moment of inertia of the cross section at the pipe wall of the vent pipe. Thus, the rigidity of the tube wall can be reduced more flexibly with respect to pressure fluctuations from the inside.

  In the airflow passage radiated sound reducing structure according to claim 11, in the airflow passage radiated sound reducing structure according to claim 6, the corrugated shape is such that a tube wall of the vent pipe is formed in an accordion shape in the axial direction. It is characterized by being realized.

The axial wavy shape may be reduced in rigidity by forming a bellows-like tube wall, and the tube wall of the vent tube can be sufficiently expanded and contracted particularly in the axial direction by pressure vibration.
The airflow path radiated sound reducing structure according to claim 12, wherein the storage tube is disposed in an outer cylinder of the silencer according to any one of claims 1 to 11. The resonance cover is characterized in that all or a part of the region forming the space is reduced in rigidity.

  Further, in the case where the storage tube is a resonance cover, there is a further outer cylinder covering the space around the resonance cover. For this reason, the resonance cover itself may be a structure in which all or a part of the region forming the space is made low in rigidity.

By configuring in this way, the resonance cover itself is more likely to vibrate, the vibration can be easily converted into thermal energy, and the leakage of radiated sound to the outside of the outer cylinder can be suppressed.
The airflow passage radiated sound reduction structure according to claim 13 is a sound deadening in which a ventilation pipe having an airflow passage inside and a resonance cover for housing a part or all of the ventilation pipe through a space are accommodated in an outer cylinder. An airflow passage radiated sound reduction structure that reduces the radiated sound generated with the airflow in the ventilation pipe in the vessel, wherein the resonance cover is entirely or partially reduced by one or both of the shape and material other than the through hole. It is characterized by being rigid.

Regardless of whether or not the ventilation pipe is reduced in rigidity as described above, all or part of the resonance cover may be reduced in rigidity.
By comprising in this way, the membrane vibration of a resonance cover can be easily converted into a thermal energy, the noise absorption efficiency can be improved, and it can suppress that it becomes a radiation sound to the exterior.

  The airflow path radiated sound reducing structure according to claim 14 is characterized in that in the airflow path radiated sound reducing structure according to claim 13, a sound absorbing material is arranged in a part or all of the space.

  In particular, if the sound absorbing material is disposed in part or all of the space between the resonance cover and the ventilation pipe so that the sound absorbing material and the resonance cover are in contact with each other, pressure is applied to the sound absorbing material from the tube wall of the resonance cover that vibrates. Vibration can be sufficiently applied. In other words, if the sound absorbing material and the resonance cover are in contact, the pressure vibration transmission between the tube wall of the resonance cover and the sound absorbing material is between solids, so the pressure vibration is transmitted from the tube wall to the sound absorbing material with high efficiency. Increases the noise absorption efficiency of the material. When the sound-absorbing material contains liquid, there is also the transmission of pressure vibration between the solid and the liquid in addition to the solid, but in this case, the pressure vibration is converted into thermal energy with high efficiency and the noise absorption efficiency Is further increased.

  Even if the sound-absorbing material is not in contact with the resonance cover, if the internal vent pipe is in contact with the sound-absorbing material, pressure vibration transmission from the vent pipe to the resonance cover side has almost no problem even if the vent pipe is rigid. Even if transmitted, the resonance cover can sufficiently convert the vibration into thermal energy, so that the noise absorption efficiency can be improved.

  In the airflow path radiated sound reducing structure according to claim 15, in the airflow path radiated sound reducing structure according to any one of claims 12 to 14, the rigidity reduction in the resonance cover is any of claims 5 to 11. The structure of the low rigidity in the pipe wall of the said ventilation pipe as described in any one of the above is employ | adopted.

As for the low rigidity of the resonance cover, the low rigidity structure of the pipe wall of the ventilation pipe according to any one of claims 5 to 11 can be employed.
As a result, the resonance cover itself or together with the sound absorbing material can sufficiently convert vibration into heat energy, so that the noise absorption efficiency can be increased.

  In the airflow passage radiated sound reducing structure according to claim 16, in the airflow passage radiated sound reducing structure according to any one of claims 1 to 15, the air pipe has an internal airflow passage as an exhaust passage of the internal combustion engine. It is characterized by being.

  When the airflow passage radiated sound reduction structure is applied to the exhaust passage of the internal combustion engine as described above, the exhaust noise of the internal combustion engine can be effectively suppressed even with the small airflow passage radiated sound reduction structure due to the above-described actions and effects. For this reason, it can contribute to the weight reduction of a vehicle in an automobile or the like.

FIG. 3 is a perspective view showing the silencer of the first embodiment. FIG. 3 is a partially broken perspective view of the silencer of the first embodiment. (A), (b) The elements on larger scale of the low rigidity part of Embodiment 1 are expanded explanatory drawing. (A), (b) Explanatory drawing of expansion-contraction deformation | transformation of the low rigidity part of Embodiment 1. FIG. Structure explanatory drawing which shows an example of the silencer of Embodiment 2. FIG. Structure explanatory drawing which shows an example of the silencer of Embodiment 2. FIG. Structure explanatory drawing which shows an example of the silencer of Embodiment 2. FIG. FIG. 6 is a partially broken perspective view showing an example of a silencer according to a third embodiment. FIG. 6 is a partially broken perspective view showing an example of a silencer according to a third embodiment. Sectional drawing of the resonance cover type silencer of Embodiment 4. FIG. FIG. 10 is a perspective view of a resonance cover arrangement portion according to the fourth embodiment. FIG. 10 is a partial vertical cross-sectional view of a resonance cover arrangement portion according to the fourth embodiment. FIG. 10 is a partially broken perspective view of a resonance cover arrangement portion according to the fourth embodiment. The fragmentary broken perspective view which shows the resonance cover arrangement | positioning part of Embodiment 4 except a sound-absorbing material. FIG. 10 is a perspective view showing an airflow passage radiated sound reducing device according to a sixth embodiment. FIG. 10 is a partially broken perspective view of the airflow path radiated sound reducing device of the sixth embodiment. FIG. 9 is a partially broken enlarged configuration explanatory view of an airflow passage radiated sound reducing device of a sixth embodiment. FIG. 6 is a partially broken enlarged configuration explanatory view showing an example of a silencer according to another embodiment. FIG. 6 is a partially broken enlarged configuration explanatory view showing an example of a silencer according to another embodiment. FIG. 6 is a partially broken enlarged configuration explanatory view showing an example of a silencer according to another embodiment.

[Embodiment 1]
FIG. 1 is a perspective view showing a silencer 2 attached to an exhaust system of an internal combustion engine for a vehicle, to which the above-described airflow path radiation noise reducing structure is applied. The silencer 2 includes a metal ventilation tube 4 and a storage tube 6, and the storage tube 6 stores a part of the ventilation tube 4 therein. End walls 6a and 6b are formed at both ends of the storage tube 6, and the end walls 6a and 6b form a part of the ventilation tube 4 in the storage tube 6 as shown in FIG. Is sealed.

  The internal space of the storage tube 6 is filled with a fibrous sound absorbing material 8 (in the form of a lump of fibers, a woven fabric, a non-woven fabric, etc.) such as glass wool, ceramic fiber, alumina fiber, and silica fiber. The sound absorbing material 8 is in contact with the inner peripheral surface of the storage tube 6 and the outer peripheral surface of the vent tube 4. The sound-absorbing material 8 may be in the form of a homogeneous fiber lump, woven fabric, non-woven fabric, or the like, but may be one in which a plurality of these are filled in layers. Further, these fibrous materials may be impregnated with a liquid.

  The portion of the vent pipe 4 housed in the housing pipe 6 has a low rigidity portion 12 formed in a part of the pipe wall 10. The low rigidity portion 12 of the present embodiment is formed of a polyhedron, and the overall shape is formed in a pseudo-cylindrical shape. Specifically, the polyhedron is a pseudo-cylindrical concave polyhedron (PCCP). This PCCP corresponds to a shape combining triangles or trapezoids with the ridges of uneven polygonal lines as boundaries. FIG. 2 illustrates a combination of triangles.

  Such a PCCP has its outer shape expanded or contracted by changing the angle between the faces across the ridge, so that flexibility is generated even with the same material and thickness as compared to a simple cylinder. Accordingly, the rigidity of the low rigidity portion 12 is lower than that of other portions of the vent pipe 4. That is, the low rigidity portion 12 has a low rigidity by a shape other than the through hole.

  Here, as shown in the enlarged view of FIG. 3A, the low-rigidity portion 12 has the above-described fold line-shaped ridges with respect to the ridges 12a arranged annularly in the circumferential direction and the axial direction of the vent pipe 4. There are two types of ridges 12b and 12c that are arranged obliquely and have a helical arrangement with different twist directions as a whole. A large number of triangular portions 12d surrounded by these three types of straight edges 12a, 12b, and 12c exist to form a pseudo-cylindrical shape as a whole.

  Among the three types of ridges 12a, 12b, and 12c, the ridges 12a that are annularly arranged in the circumferential direction form a concave portion by being bent portions having an inter-surface angle of less than 180 °, and the ridges 12b that are arranged in a spiral shape 12c forms a convex portion by being a bent portion having an inter-surface angle exceeding 180 °. Accordingly, it can be considered that the low rigidity portion 12 has unevenness in the axial direction, and the low rigidity portion 12 is formed in a wave shape in the axial direction of the vent pipe 4.

  As shown in FIG. 3B, which is a cross-sectional view taken along the line AA in FIG. 3A, a state of being recessed at a position of depth d between each vertex P of the triangular portion 12d on both sides of the ridge 12a. Thus, the center point B of the ridge 12a exists.

  If the relationship between the depth d and the thickness t of the member constituting the low rigidity portion 12 is expressed by the following equation 1, the PCCP of the present embodiment is from the inside of the low rigidity portion 12. Deformation is relatively likely to occur with respect to pressure fluctuations. That is, the reduction in rigidity can be promoted.

[Formula 1] d <√2 · t
Here, “√2” indicates the square root of 2. This expression 1 represents a range in which deformation easily occurs from the viewpoint of the average value of the cross-sectional secondary moment in bending the tube wall of the low rigidity portion 12 based on the structural analysis of PCCP.

  Therefore, as shown by the arrow in FIG. 4A, the reduced rigidity portion 12 expands and contracts in the axial direction like a spring, and the expansion / contraction wave is generated in the axial direction. Since the shape is easily deformed, a wave that vibrates in the radial direction as shown by the arrow in FIG.

In addition, the rigidity of the low rigidity portion 12 may be reduced by making the relationship as expressed by the following expression 2 so that the rigidity of the low rigidity portion 12 is easily deformed with respect to pressure fluctuation from the inside.
[Formula 2] d <2.t
This expression 2 represents a range in which deformation is easy from the viewpoint of the minimum value of the moment of inertia of the cross section in bending the tube wall of the low rigidity portion 12 based on the structural analysis of PCCP.

According to the first embodiment described above, the following effects can be obtained.
(1) The ventilation pipe 4 has a low-rigidity portion whose rigidity has been reduced by forming a polyhedron, particularly a pseudo-cylindrical concave polyhedron, on a part of the pipe wall portion housed in the storage pipe 6. There are 12. That is, there is a portion whose rigidity is reduced by a shape other than the through hole.

  As described above, the pipe wall itself of the ventilation pipe 4 has a low rigidity as described above. Therefore, the pipe wall can be easily formed by pressure vibration acting on the pipe wall of the low rigidity portion 12 from the air flow path side in the ventilation pipe 4. Causes membrane vibration. Here, the inter-plane angle at the ridges 12a, 12b, and 12c fluctuates, and as shown in (a) and (b) of FIG. Pressure vibration can be sufficiently transmitted to the sound absorbing material 8 through the wall.

  If the rigidity-reducing portion 12 of the vent pipe 4 is a pseudo-cylindrical concave polyhedron set so as to satisfy the formula 1 or the formula 2, it is designed to be easily deformed particularly in the radial direction, so that the vibration can be more flexible. Thus, the transmission of pressure vibrations to the sound absorbing material 8 that is in contact with each other on the tube wall can be executed with higher efficiency.

  Since such highly efficient pressure vibration transmission is possible by membrane vibration through the tube wall, even if there is no through hole in the ventilation pipe 4 inside the storage pipe 6, airflow (in this case, exhaust from the internal combustion engine) ) Pressure vibration can be sufficiently transmitted to the sound absorbing material 8 side through the tube wall of the ventilation tube 4.

  In addition, since the pressure vibration transmission between the tube wall and the sound absorbing material 8 is between solids, it is highly efficient as described above. However, when the sound absorbing material 8 contains a liquid, the solids are added in addition to the solids. There is also pressure vibration transmission between the liquid and the liquid, and conversion into heat energy is efficiently performed, resulting in higher noise absorption efficiency.

  In this way, according to the airflow passage radiated sound reduction structure adopted by the silencer 2 of the present embodiment, the efficiency of absorbing noise generated by the exhaust flow in the sound absorbing material 8 around the ventilation pipe 4 having the inside as the exhaust passage is sufficiently high. Enhanced. As a result, the vibration of the storage tube 6 is suppressed, and it is possible to suppress the radiated sound generated along with the exhaust flow in the ventilation tube 4 from leaking from the storage tube 6 to the outside.

As a result, even the downsized silencer 2 can sufficiently exhibit a silencing effect, and can contribute to weight reduction of the vehicle in an automobile or the like.
[Embodiment 2]
5-7 show a partially broken perspective view and a partially enlarged view of the silencer of the present embodiment.

  The silencer 52 shown in FIG. 5 is different from the configuration of the first embodiment in that the ventilation pipe 54 is formed with a through hole 54a in a portion other than the low rigidity portion 62 in a portion in the storage tube 56. Different. Other configurations such as the storage tube 56, the sound absorbing material 58, and the low rigidity portion 62 are the same as those in the first embodiment.

  The silencer 102 shown in FIG. 6 is characterized in that the vent pipe 104 is formed with through holes 104a and 112a entirely including the low rigidity portion 112 in a portion in the storage pipe 106. The configuration is different. Other configurations such as the storage tube 106 and the sound absorbing material 108 are the same as those in the first embodiment.

  The silencer 152 shown in FIG. 7 is different from the configuration of the first embodiment in that the ventilation pipe 154 has a through-hole 162a formed in the reduced rigidity portion 162 in a portion inside the storage pipe 156. Other configurations such as the storage tube 156 and the sound absorbing material 158 are the same as those in the first embodiment.

According to the second embodiment described above, the following effects can be obtained.
(1) Even when the through holes 54a, 104a, 112a, 162a are formed in the vent pipes 54, 104, 154 as described above, the shape of the pipe wall is a pseudo-cylindrical concave as described in the first embodiment. There are low-rigidity portions 62, 112, and 162 that are low-rigidity due to the polyhedron.

  As a result, in addition to the transmission of pressure vibration through the through holes 54a, 104a, 112a, 162a, sufficient pressure vibration is transmitted from the tube wall that easily undergoes membrane vibration to the sound absorbing materials 58, 108, 158 due to further reduced rigidity. Can be communicated to. As a result, the efficiency of absorbing noise generated by the airflow in the sound absorbing materials 58, 108, 158 around the vent pipes 54, 104, 154 can be increased.

  In this way, the vibration of the storage pipes 56, 106, 156 is suppressed, and it is possible to suppress the radiated sound generated along with the exhaust flow in the vent pipes 54, 104, 154 from leaking to the outside from the storage pipes 56, 106, 156. . Therefore, the silencers 52, 102, and 152 can be reduced in size, and can contribute to reducing the weight of the vehicle in an automobile or the like.

[Embodiment 3]
As shown in FIG. 8, the silencer 202 of the present embodiment includes a sound absorbing material 208 around the ventilation pipe 204 in the storage pipe 206, but a mat-like sound absorption having a large specific gravity especially around the low rigidity portion 212. A material 208a is wound around. As a result, the sound absorbing material 208 is multilayered.

Further, as shown in FIG. 9, the sound absorbing material in the inner space 256 a of the storage tube 256 may be only the mat-like sound absorbing material 258 wound around the low rigidity portion 262.
In addition, although the through-hole 254a is provided in parts other than the low rigidity part 262 in the ventilation pipe 254 in the storage pipe 256 of FIG. 9, this through-hole 254a does not need to be provided. Further, a through hole may be provided in the low rigidity portion 262. The vent pipe 204 shown in FIG. 8 may also be provided with a through hole in the storage pipe 206.

According to the third embodiment described above, the following effects can be obtained.
(1) The effects of the first embodiment and the following effects are produced. That is, a mat-like sound absorbing material 208a having a specific gravity different from that of the sound absorbing material 208 is arranged as shown in FIG. 8, or a mat-like sound absorbing material 258 is wound around the position of the low rigidity portion 262 as shown in FIG. In such a case, there is a possibility that a displacement in the axial direction with respect to the low rigidity portions 212 and 262 may occur in the mat-like sound absorbing materials 208a and 258 due to vibration.

  However, since the low-rigidity portions 212 and 262 around which the mat-like sound absorbing materials 208a and 258 are wound are pseudo-cylindrical concave polyhedrons, the frictional force between the mat-like sound absorbing materials 208a and 258 due to the unevenness of the surfaces thereof. Is higher than when it is a mere cylindrical surface.

For this reason, the resistance against the above-described displacement increases, so that the displacement of the mat-like sound absorbing materials 208a and 258 due to vibration can be prevented, and the durability of the silencers 202 and 252 can be increased.
[Embodiment 4]
As shown in FIG. 10, the present embodiment shows an example in which the airflow passage radiated sound reducing structure is applied to a resonance cover type silencer 302 attached to an exhaust system of a vehicle internal combustion engine.

  The silencer 302 has an outer wall formed by an outer cylinder 304 and both end plates 306 and 308. The internal space of the outer cylinder 304 is partitioned by partition plates 310 and 312, and thereby, expansion chambers 314, 316 and 318 are formed in the outer cylinder 304.

  An exhaust introduction pipe 320 is disposed in a state of passing through the end plate 306 and the partition plates 310 and 312, and the distal end of the exhaust introduction pipe 320 is open to the expansion chamber 318 on the left side in the drawing. The partition plates 310 and 312 are penetrated by the inner pipes 322 and 324, respectively, so that the expansion chambers 314, 316, and 318 are in communication with each other. Further, an outlet pipe 326 is disposed in a state of penetrating the partition plates 310 and 312 and the end plate 308, and exhaust is discharged from the expansion chamber 314 on the right side of the drawing to the outside of the silencer 302.

  The exhaust introduction pipe 320 is formed into a low rigidity portion by forming the pseudo-cylindrical concave polyhedron 320a described in the first embodiment in the central expansion chamber 316, and this pseudo-cylindrical concave The polyhedron 320a is formed according to the relationship between the thickness and the depth as shown in the formula 1 or the formula 2. Further, a large number of through holes 320b are formed in the pseudo-cylindrical concave polyhedron 320a.

  A resonance cover (high frequency resonance tube) 328 is attached to the outside of the exhaust introduction pipe 320 around the pseudo-cylindrical concave polyhedron 320a so as to be fitted to the exhaust introduction pipe 320 at both tapered ends. As a result, a high frequency resonance chamber 330 is formed between the resonance cover 328 and the exhaust introduction pipe 320.

  The high frequency resonance chamber 330 is filled with a sound absorbing material 332 made of the material as described in the first embodiment. The high-frequency resonance chamber 330 may not be filled with the sound absorbing material 332, or, as shown in FIG. 8 or 9, the mat-like sound absorbing material is wound around the peripheral portion of the pseudo-cylindrical concave polyhedron 320a. Also good.

  FIG. 11 shows an arrangement portion of the resonance cover 328 in the exhaust introduction pipe 320. FIG. 12 is a partial longitudinal sectional view of the resonance cover 328 and the sound absorbing material 332 cut longitudinally, FIG. 13 is a perspective view thereof, and FIG. 14 is a partially broken perspective view of the resonance cover 328 except for the sound absorbing material 332.

  The resonance cover 328 covering the high frequency resonance chamber 330 is formed as a pseudo-cylindrical concave polyhedron 328c except for the fitting portions 328a and 328b at both ends. Therefore, the resonance cover 328 is also provided with a low rigidity portion.

  The pseudo-cylindrical concave polyhedron 328c is also formed in the relationship between the thickness and the depth as shown in the formula 1 or the formula 2 similarly to the pseudo-cylindrical concave polyhedron 320a on the exhaust introduction pipe 320 side. .

  With such a configuration, the exhaust gas of the internal combustion engine introduced into the exhaust introduction pipe 320 from the right side in FIG. 10 is introduced into the silencer 302 from the exhaust introduction pipe 320 as indicated by the arrow, and is passed through the inner pipes 324 and 322. The exhaust pipe 326 is discharged through the expansion chambers 318, 316, and 314. During this time, the high frequency component in the exhaust sound is silenced in the high frequency resonance chamber 330 and the low frequency component is silenced in the expansion chambers 314, 316, and 318, respectively.

According to the fourth embodiment described above, the following effects can be obtained.
(1) Since the reduced rigidity portion is formed by the pseudo-cylindrical concave polyhedron 320a in the exhaust introduction pipe 320 corresponding to the ventilation pipe, the effect of the first embodiment is produced. Along with this, the following effects are produced.

  In the silencer 302, the storage tube is a resonance cover 328, and an outer cylinder 304 further exists on the outside thereof. For this reason, the resonance cover 328 itself, which is a storage tube, also has a low rigidity in a part of the region forming the space (the high frequency resonance chamber 330) in which the sound absorbing material 332 is disposed. By configuring in this way, the vibration of the resonance cover 328 is further transmitted to the internal sound absorbing material 332 with high efficiency and absorbed, so that it is possible to suppress the sound emitted to the outside of the outer cylinder 304.

[Embodiment 5]
The present embodiment is a modification of the fourth embodiment.
That is, in the present embodiment, in contrast to the configurations shown in FIGS. 10 to 14, the resonance cover similarly has a configuration in which a low rigidity portion is formed by a pseudo-cylindrical concave polyhedron, but the exhaust introduction pipe is formed in a cylindrical body. It is only the structure which provided many through-holes, and the pseudo-cylindrical concave polyhedron is not formed. That is, it is assumed that the exhaust introduction pipe is not made low in rigidity.

  Even in this configuration, as described in the fourth embodiment, the vibration of the resonance cover is transmitted to and absorbed by the internal sound absorbing material with high efficiency, so that it is possible to suppress the radiation sound to the outside of the outer cylinder. .

[Embodiment 6]
15 to 17 show an airflow path radiated sound reducing device 352 of the present embodiment. This airflow path radiated sound reducing device 352 is one to which the airflow path radiated sound reducing structure of the present invention is applied. FIG. 15 is a perspective view of an airflow path radiation sound reducing device 352 formed in a part of the vent pipe 354, and FIG. 16 is a partially cutaway perspective view showing the storage pipe 356 in a cutaway state. FIG. 17 is a front view of FIG. 16 and a partially enlarged view thereof.

  This airflow passage radiated sound reducing device 352 is not limited to the silencer of the internal combustion engine, but is a device that suppresses radiated sound generated by pressure vibration of the airflow flowing through the inside of the vent pipe 354 in various airflow passages.

  As shown in the figure, the airflow passage radiated sound reducing device 352 includes a vent pipe 354 and a storage pipe 356, and the storage pipe 356 stores a part of the vent pipe 354 therein. End walls 356a and 356b are formed at both ends of the storage pipe 356, and a part of the ventilation pipe 354 in the storage pipe 356 is sealed by the end walls 356a and 356b.

Unlike the above embodiments, the sound absorbing material is not disposed in the internal space 356c of the storage tube 356, and is completely hollow.
A portion of the ventilation pipe 354 housed in the storage pipe 356 is formed with a low rigidity portion 362 on a part of the pipe wall. The low rigidity portion 362 is a pseudo-cylindrical concave polyhedron (PCCP) as described in the first embodiment. Therefore, the rigidity reduction portion 362 is reduced in rigidity by a shape other than the through hole.

  Thus, although the outer peripheral surface of the low rigidity part 362 is uneven | corrugated by being a pseudo-cylindrical concave polyhedron, none is contacting the inner peripheral surface of the storage pipe 356. The height of the internal space 356c is set so that the rigidity reducing portion 362 does not come into contact with the inner peripheral surface of the storage tube 356 even if the low rigidity portion 362 causes membrane vibration due to the airflow inside the ventilation tube 254.

According to the sixth embodiment described above, the following effects can be obtained.
(1) Since the reduced rigidity portion 362 is formed by the pseudo-cylindrical concave polyhedron on the ventilation pipe 354, the rigidity reduction section 362 easily generates membrane vibration due to pressure vibration of the airflow flowing inside the ventilation pipe 354. However, since the reduced rigidity portion 362 is not in contact with the storage tube 356, vibration is not transmitted to the storage tube 356, and most of the vibration energy is finally converted into thermal energy by the reduced rigidity portion 362.

In this way, it is possible to suppress the radiated sound generated by the pressure vibration of the airflow flowing inside the ventilation pipe 354 from leaking to the outside of the storage pipe 356.
Further, if the low rigidity portion 362 is set so as to satisfy the formula 1 or the formula 2 described in the first embodiment, the design is particularly easy to deform. Vibration can be efficiently converted into thermal vibration.

As a result, the airflow passage radiated sound reducing device 352 can be reduced in size, which can contribute to weight reduction of the device in various applications.
(2) Although there is a case where it is desired to insulate the inside of the ventilation pipe 354 from the outside depending on the application, since the storage pipe 356 is always in non-contact with the low rigidity portion 362 through the internal space 356c, there is a heat insulation effect. large.

  Furthermore, even if the temperature difference between the ventilation pipe 354 and the storage pipe 356 increases, the low rigidity portion 362 is flexible, so that the thermal expansion difference is absorbed and the airflow passage radiation noise reduction device 352 is absorbed. Can increase the durability.

[Other embodiments]
In each of the above embodiments, an example of a pseudo-cylindrical concave polyhedron (PCCP) composed of triangular faces divided by creases has been shown as the polyhedron. As another pseudo-cylindrical concave polyhedron, a pseudo-cylindrical concave polyhedron 412 having a trapezoidal shape divided by creases as shown in the partially broken perspective view of FIG. It can also be adopted for 404. Alternatively, it can also be adopted in the resonance cover shown in the fourth embodiment. In FIG. 18, the sound absorbing material around the pseudo-cylindrical concave polyhedron 412 is omitted. When applied to the sixth embodiment, no sound absorbing material is required. As a result, the effects of the respective embodiments can be produced. Also in this case, by adopting the relationship of the formula 1 or the formula 2, the reduction in rigidity can be further strengthened.

  The perspective view of FIG. 19 and its enlarged view show an example in which a pseudo-cylindrical concave polyhedron 462 having a trapezoidal shape and a size different from each other is formed in a part of the vent pipe 454. In FIG. 19, the sound absorbing material around the pseudo-cylindrical concave polyhedron 462 is omitted. When applied to the sixth embodiment, no sound absorbing material is required. Such a pseudo-cylindrical concave polyhedron 462 can also be used in the resonance cover shown in the fourth embodiment. Even if the rigidity is reduced by such a shape and size, the effects of the respective embodiments can be produced. In particular, if the trapezoidal shape is large, the unevenness of the pseudo-cylindrical concave polyhedron 462 can be increased, so that the effect of preventing the mat-like sound absorbing materials 208a and 258 from shifting as shown in FIGS. In the resonance cover shown in the fourth embodiment, the effect of preventing the inner sound absorbing material 332 from shifting is increased.

  As shown in the perspective view of FIG. 20 and its enlarged view, the low rigidity portion may be a low rigidity portion 512 in which the tube wall of the vent pipe 504 is formed in a wavy shape (for example, bellows shape) in the axial direction. In FIG. 20, the sound absorbing material around the bellows-like low rigidity portion 512 is omitted. When applied to the sixth embodiment, no sound absorbing material is required. Such a bellows-like low rigidity portion 512 can also be employed in the resonance cover shown in the fourth embodiment. As a result, the pipe wall of the ventilation pipe 504 or the resonance cover can be displaced in the axial direction, and the pipe wall of the low rigidity portion 512 expands and contracts in the axial direction due to the pressure vibration of the internal exhaust, causing a large deformation in the sound absorbing material. Can do. Furthermore, since the shaft of the low rigidity portion 512 is likely to shake in the direction orthogonal to the axis due to the pressure vibration of the internal exhaust, the sound absorbing material is more easily deformed, and the pressure vibration is transmitted to the sound absorbing material with high efficiency. The silencing effect can be improved.

  In the first to fifth embodiments, the pressure fluctuation of the internal exhaust gas is applied to the outer side (in the case of the resonance cover) as a low rigidity portion by adopting the shape of a polyhedron, particularly a pseudo-cylindrical concave polyhedron, on the pipe wall of the ventilation pipe or the resonance cover. It was transmitted to the sound absorbing material on the inner side with high efficiency. The shape may be a polyhedron other than this, for example, a prismatic shape, and the angle between each surface changes as the pressure vibration of the internal exhaust fluctuates, thereby serving as a low rigidity part. Can be transmitted to the outer or inner sound-absorbing material with high efficiency to improve the silencing effect. Such a configuration can also be applied to the sixth embodiment.

  The shape satisfying the expressions 1 and 2 represents an embodiment of low rigidity. If a polyhedron such as a pseudo-cylindrical concave polyhedron is reduced in rigidity as shown in each claim, the expression It is realizable as one embodiment of the present invention, without being limited to the shape which satisfies 1 and 2.

  In each of the above embodiments, a part of the ventilation pipe in the storage pipe or the exhaust introduction pipe in the resonance cover is a low rigidity part, but the ventilation pipe in the storage pipe or the exhaust introduction pipe in the resonance cover has The whole may be formed as a low rigidity portion.

In the fourth embodiment, the resonance cover is not provided with the low-rigidity parts at both ends, but the entire resonance cover including the fitting parts at both ends may be the low-rigidity part.
Furthermore, although the through hole is not formed in the resonance cover, a through hole communicating with the expansion chamber and the internal high frequency resonance chamber may be formed.

  In each of the above embodiments, the low rigidity portion is reduced in rigidity by the shape, but may be reduced in rigidity by the material. For example, the rigidity may be reduced by forming the resin-based material. As a silencer for an internal combustion engine, the rigidity can be reduced by employing a heat-resistant resin material.

  -Although the said Embodiments 1-5 gave the example of the silencer of the internal combustion engine as an example, it is applicable not only to the silencer of the internal combustion engine as in the above-mentioned Embodiment 6, but in various airflow passages, and the inside of the vent pipe It is possible to realize a device that can effectively suppress leakage of radiated sound generated by pressure vibration of the airflow flowing through the outside.

  2 ... silencer, 4 ... vent pipe, 6 ... storage pipe, 6a, 6b ... end wall, 8 ... sound absorbing material, 10 ... pipe wall, 12 ... low rigidity part, 12a, 12b, 12c ... ridge, 12d ... triangle Part 52. Silencer 54 54 vent pipe 54 a through hole 56 storage tube 58 sound absorbing material 62 low rigidity part 102 silencer 104 104 vent pipe 104 a through hole 106 DESCRIPTION OF SYMBOLS ... Storage pipe, 108 ... Sound absorbing material, 112 ... Low rigidity part, 112a ... Through hole, 152 ... Silencer, 154 ... Ventilation pipe, 156 ... Storage pipe, 158 ... Sound absorbing material, 162 ... Low rigidity part, 162a ... Through hole, 202 ... silencer, 204 ... vent tube, 206 ... storage tube, 208 ... sound absorbing material, 208a ... mat-like sound absorbing material, 212 ... low rigidity part, 252 ... silencer, 254 ... vent tube, 254a ... through Hole, 256 ... storage tube, 256a ... internal space, 258 ... mat Sound-absorbing material, 262 ... Low rigidity part, 302 ... Silencer, 304 ... Outer cylinder, 306, 308 ... End plate, 310, 312 ... Partition plate, 314, 316, 318 ... Expansion chamber, 320 ... Exhaust pipe, 320a ... Pseudo cylindrical concave polyhedron, 320b ... through hole, 322,324 ... inner pipe, 326 ... outlet pipe, 328 ... resonance cover, 328a, 328b ... fitting part, 328c ... pseudo cylindrical concave polyhedron, 330 ... high frequency resonance chamber, 332... Sound absorbing material, 352... Airflow passage radiation sound reducing device, 354... Ventilation pipe, 356. Vent pipe, 412 ... pseudo-cylindrical concave polyhedron, 454 ... vent pipe, 462 ... pseudo-cylindrical concave polyhedron, 504 ... vent pipe, 512 ... low rigidity part, B ... center point P ... vertex.

Claims (16)

Airflow passage radiated sound that reduces the radiated sound caused by the airflow in the vent pipe by including a vent pipe having an air flow passage inside and a storage pipe that accommodates the vent pipe in a non-contact state through the space. A reduction structure,
In the air pipe, the air flow passage radiated sound reduction structure is characterized in that all or part of the pipe wall in the region within the storage pipe is made low in rigidity by one or both of the shape and material other than the through hole. . Airflow passage radiated sound that reduces the radiated sound caused by the airflow in the vent pipe by including a vent pipe having an air flow passage inside and a storage pipe that accommodates the vent pipe in a non-contact state through the space. A reduction structure,
The air passage radiated sound reduction structure, wherein the vent pipe is reduced in rigidity by a shape other than the through hole in the whole or a part of the pipe wall in the region in the storage pipe. The airflow passage radiated sound reduction structure according to claim 1 or 2, wherein a sound absorbing material is disposed in a part or all of the space. The airflow passage radiated sound reduction structure according to any one of claims 1 to 3, wherein the vent pipe has a through hole formed in a tube wall in a region in the storage pipe. Radiation sound reduction structure. 5. The airflow passage radiated sound reduction structure according to claim 1, wherein the reduction in rigidity is realized by a configuration in which a tube wall of the vent pipe is elastic in an axial direction. An airflow passage radiated sound reduction structure characterized by that. 6. The airflow passage radiated sound reduction structure according to claim 1, wherein the low rigidity is such that a pipe wall of the vent pipe is formed in a wavy shape in an axial direction of the vent pipe. An airflow passage radiated sound reduction structure characterized by being realized by the following. The airflow passage radiated sound reduction structure according to any one of claims 1 to 5, wherein the low rigidity is realized by making a tube wall of the vent pipe into a polyhedron. Radiation sound reduction structure. 8. The airflow path radiated sound reduction structure according to claim 7, wherein the polyhedron is formed as a pseudo-cylindrical concave polyhedron. 9. The airflow passage radiated sound reduction structure according to claim 8, wherein the pipe wall formed as the pseudo-cylindrical concave polyhedron has a relationship between a depth d of the concave portion and a wall thickness t of d <√2 · t. An airflow passage radiated sound reduction structure characterized by being made. 9. The airflow passage radiated sound reduction structure according to claim 8, wherein the pipe wall formed as the pseudo-cylindrical concave polyhedron has a relation between the depth d of the concave portion and the wall thickness t as d <2.t. An airflow passage radiated sound reduction structure characterized by that. The airflow passage radiation sound reducing structure according to claim 6, wherein the corrugated shape is realized by forming a tube wall of the vent pipe in a bellows shape in an axial direction. Sound reduction structure. The airflow path radiated sound reduction structure according to any one of claims 1 to 11, wherein the storage tube is a resonance cover arranged in an outer cylinder of a silencer, and the resonance cover is a region that forms the space. An airflow passage radiated sound reduction structure characterized in that all or part of the structure has low rigidity. Radiation sound generated due to the air flow in the vent pipe by a silencer that houses a vent pipe with the inside as an air flow passage and a resonance cover that houses part or all of the vent pipe inside through a space. An airflow passage radiated sound reduction structure that reduces,
The structure of the airflow passage radiated sound is characterized in that all or a part of the resonance cover is reduced in rigidity by one or both of a shape and a material other than the through hole. The airflow path radiated sound reduction structure according to claim 13, wherein a sound absorbing material is disposed in a part or all of the space. The airflow passage radiated sound reduction structure according to any one of claims 12 to 14, wherein the low rigidity of the resonance cover is low in the pipe wall of the vent pipe according to any one of claims 5 to 11. An airflow passage radiation noise reduction structure characterized by adopting a rigid structure. The airflow path radiant sound reduction structure according to any one of claims 1 to 15, wherein the air pipe has an internal airflow path as an exhaust path of an internal combustion engine.

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