DE102005054397B3 - Pipe sound absorber for use in ventilation duct, has segments with different intervals to each other for separating space between inner channel and outer wall into chambers in axial direction, where channel has radial intervals from wall - Google Patents

Abstract

The absorber (1) has an inner channel (10) with micro-openings (15) and an outer wall (30) partially surrounding the channel. Separating segments (20) are orthogonally arranged between the channel and the wall, and have different intervals to each other for separating a space between the channel and the wall into a set of chambers in an axial direction. The channel has two radial intervals from the wall, where the wall is made of metal or plastic. An independent claim is also included for a method for utilizing a pipe sound absorber.

Description

The The invention relates to a device and a method for damping of Sound waves. In particular, the invention relates to a pipe silencer with Micro-openings.

From the DE 197 30 355 C1 is a sound absorber in ventilation ducts is known in which a micro-perforated plate is part of the ventilation duct. The disadvantage here is that provided cassettes are arranged as part of a flow-through backdrop at uniform intervals. The distance of the intermediate walls is of great influence for the quality of the sound damping behavior for the particular sound frequency to be damped. Thus, in this sound absorber, the effect of the sound attenuation is good only in a certain frequency range. He is therefore less suitable as a damper for a damping of different frequencies.

In the DE 976 032 describes a silencer with branch filter and series filter with a continuous, made of one piece, partially perforated inner tube.

In DE 298 08 058 a combination pipe muffler is described with a gas-carrying line, wherein the conduit has a double-walled portion which forms a substantially closed chamber between the inner tube and the outer tube.

task The present invention is therefore a pipe muffler with Micro openings and to provide a method of operating such a pipe muffler, which can be used flexibly and for different frequency spectra can be produced and the disadvantages of the prior art avoids.

These The object is achieved by the device and the method according to the independent claims. Further advantageous embodiments are specified in the dependent claims.

Especially we solved the task through a pipe muffler for the targeted reduction of the intensity of sound waves, comprising an inner channel with micro-openings and an outer wall at least partially surrounding the inner channel, wherein additionally Separating segments between the inner channel and the outer wall are provided, the individual distances in the axial direction between the Define separation segments, wherein the axial distances, at least comprise a first axial distance and a second axial distance, the radial distance between the surface of the inner channel and the outer wall at least a first radial distance and a second radial distance includes.

The Sound waves enter the muffler through the inner channel. Of the inner channel is preferably a tube, but can also have a recess inside a surrounding material. In the latter case, the channel becomes preferably of soundproofing be surrounded porous material in which the channel is incorporated.

Prefers the inner channel has micro-openings on. The sound waves pass through the micro-openings, passing through lose the friction of energy occurring. As a result of Wall friction occurs broadband losses in the energy of sound waves on. The micro-openings are preferably cylindrical through-holes, but can also have other geometric shapes.

Of the inner channel is preferably at a distance from an outer wall surround. The sound waves emerging from the inner channel hit on the outside wall and become a big one Part reflected. The outer wall acts with the enclosed air mass as a cavity resonator. The first and second distance between the inner channel and the outer wall Defined in the radial direction, as the inner channel to the outer wall is arranged. Preferably, the first and second distances are not equal large, so that the inner channel has different distances to the outer wall. The from the inner channel emerging and impinging on the outer wall sound waves, have to so depending on the exit point different distances to the impact on the outside wall return. Thereby distances with different damping behavior regarding. given individual frequencies. The advantage of this is a total better sound-damping effect over one Frequency range. Particularly preferred is the space between the inner channel and the outer wall through a filler filled, particularly preferably by fibrous material, tissue, or by a steel lamella composite.

The Separating segments between the inner channel and the outer wall define individual distances in the axial direction between the separating segments, wherein the axial Distances, at least a first axial distance and a second axial Include distance. When hitting the tennis segments, the Sound waves also reflected. The separator segments separate the Volume between the inner channel and the outer tube in the axial direction in individual chambers with preferably different chamber size. As a result, individual cavity resonators with different damping behavior given with respect to individual frequencies. The advantage of this is one better sound-damping effect over one Frequency range.

Especially Preferably, the pipe silencer according to the invention still a curvature on. By choosing the radius of curvature For example, the sound absorption property can be predetermined.

at a further preferred embodiment of the pipe silencer according to the invention are the outer wall and the inner channel disposed axially parallel.

These axis-parallel alignment allows one simple construction of the pipe silencer. Especially is the assembly of the inner channel inside the outer wall simply possible by inserting.

at a further preferred embodiment of the pipe silencer according to the invention are the outer wall and the inner channel aligned coaxially.

These Coaxial alignment allows a simple construction of the pipe silencer. In particular, the Assembly of the inner channel inside the outer wall by inserting and fastening easy on the same wave.

at a further preferred embodiment of the pipe silencer according to the invention are the radial distances between the inner channel and the outer wall and / or the axial distances changeable between the separating segments.

The Schalldämpfverhalten is dependent on it how long the distance is, the sound waves from the exit the inner channel to hit the outer wall and how big the distance between the individual separation segments. Is the distance changeable, can the muffler adapted to different requirements with respect to the damping behavior become. For example, those of an internal combustion engine with the Exhaust gases emitted sound waves often at startup other intensities as on the fly. An adjustability of the silencer allows here a flexible adaptation to the changing sound damping task. In addition to the adjustment of the silencer during operation is also a cost effective Production of silencers possible if these with a similar structure for different purposes in big quantity can be produced and only adjusted to the respective sound damping task Need to become.

at a further preferred embodiment of the pipe silencer according to the invention are the distances between the inner channel and the outer wall by twisting the outer wall and / or the inner channel changeable.

These easy to implement kinematics with only one axis of rotation makes it possible to change the position of the inner channel relative to the outer wall. A Twisting is technically about axes of rotation and actuators easily realizable and positions are by means of protractors easy to identify and reproduce.

at a further preferred embodiment of the pipe silencer according to the invention are the axial orientation of the outer wall and the inner channel mutually changeable.

These changeability the axial alignment of the outer wall and the inner channel to each other allows a very far reaching Change in the radial distances between the inner channel and the outer wall in the axial direction. With this adjustment is a far-reaching change the sound damping behavior of the pipe silencer according to the invention microopenings possible.

at a further preferred embodiment have the pipe silencer according to the invention the outer wall and / or the inner channel is a cross section of the group: circular, square, oval, diamond-shaped, symmetrical polygonal, polygonal with rounded corners on.

at a further preferred embodiment the pipe muffler according to the invention has the outer wall an outer contour with surfaces and these connecting rounded edges.

These Contour offers the advantage of saving space in other systems is integrable. Furthermore, this contour is simple z. B. of sheet steel realizable.

at a further preferred embodiment of the pipe silencer according to the invention the outer wall at one end with an inlet opening and at the other end with an outlet opening of the inner channel, tightly connected.

For an optimal Sound-absorbing effect provides this arrangement sure that the system is closed and that no sound waves through openings can escape.

In a further preferred embodiment of the pipe silencer according to the invention, the micropores on the inner channel have a diameter smaller than 1 mm, in particular less than 0.5 mm, in particular less than 0.1 mm.

Of the Hole diameter or the design of the micropores and the Proportion of the surface of Micropores to the remaining surface has an influence on the predetermined sound absorption level.

at a further preferred embodiment the pipe silencer according to the invention is the proportion the micropores on the inner channel less than 10% of the total surface of the internal channel, in particular less than 5% of the total surface of the internal channel, in particular less than 2% of the total surface of the inner Channel.

Of the Perforated portion The micropores also have an influence on the sound absorption coefficient.

at a further preferred embodiment have the pipe silencer according to the invention the micropores on the inner channel are a geometric form of the group consisting of: circular, square, oval, rhombic, symmetrical polygonal on.

By The choice of the shape of the micropores can be different manufacturing processes be used. This allows advantageously also the sound absorption properties predetermined become.

at a further preferred embodiment the pipe muffler according to the invention has the inner channel tissue on.

The Fabric preferably comprises metal, nylon or glass fibers or a Combination of these materials. With opening degree of the fabric becomes here either the volume ratio fabric fibers and the spaces between the fabric fibers or the area ratio of surface of the fabric to the openings the meshes of the tissue. The fabric particularly preferably has opening degrees up to 40%. It can but also preferably tissue with degrees of opening only 20% are used.

at a further preferred embodiment of the pipe silencer according to the invention are one or more of the separation segments substantially orthogonal to axial direction of the outer wall aligned.

By this orthogonal orientation is the separation segments parallel to each other and opposite each other aligned. This arrangement is particularly good acoustic resonance system.

at a further preferred embodiment have the pipe silencer according to the invention one or more of the separation segments is a form from the group of: Cone part, ball part, ellipsoid part, paraboloid part, pyramid part on.

The Uneven shape of the separating segments preferably requires a more diffuse Sound reflection as with simply flat separation surfaces. An even better damping behavior is so realizable.

at a further preferred embodiment of the pipe silencer according to the invention are a plurality of separating segments arranged at an angle greater than 5 ° to each other, in particular greater than 20 ° to each other arranged, in particular larger than 40 ° to each other arranged.

Of the Angle of the separation segments causes an oblique reflection the sound waves. Standing waves between two opposite surfaces become so avoided. Furthermore is thus preferred in gradual formation of the separation segments a spectrum of waves with different wavelengths inside the separating segments damped.

at a further preferred embodiment of the pipe silencer according to the invention are one or more of the separating segments formed as a helix band, the formed around the inner channel, trained.

hereby results in an angle of attack between the helix and a plane perpendicular to the axial direction and at the same time a separating segment with predefined many chambers based on the individual sections within the space between inner channel and outer wall.

at a further preferred embodiment of the pipe silencer according to the invention are one or more of the separating segments formed as a helix band, the with changing pitch screwed around the inner channel, trained.

The changing pitch of the helix allows a varying distance in the axial direction between the individual turns of the helix. Since the helix is sound-hard and has a function corresponding to the separating segments, the same advantages apply here as for the different spacing of the separating segments. By selecting the pitch or the course of the pitch predetermined frequency ranges can be represented by the wavelength or a quarter of the wavelength. In this way it is possible, a special To attenuate the frequency band especially by these wavelengths or a quarter of these wavelengths are selected as a spacing between the individual helix bands after a period. The helix can be designed as an elastic steel band, which allows an adjustment of the helix by deformation.

at a further preferred embodiment of the pipe silencer according to the invention are one or more of the separating segments adjustable.

To the one can preferably adjusted the distance of Trennsegemente each other and on the other hand, the angle of the separating segments to each other adjusted become. This allows the frequency range to be absorbed is predetermined.

at a further preferred embodiment of the pipe silencer according to the invention he from several individual successively arranged segments constructed, which are connected to each other.

This modular design allows it, depending on the purpose of several different silencer segments a silencer build. With the number and type of segments, the damping behavior be set.

at a further preferred embodiment of the pipe silencer according to the invention the outer wall is hardy.

Thereby, that the outer wall is sound-hard, the sound waves emerging from the inner channel become reflected and it is particularly easy to create a cavity resonator.

at a further preferred embodiment of the pipe silencer according to the invention contains the material the outer wall an element from the group of: Fe, Pt, Cr, Cu, Ni, C, in particular Metal or plastic.

In the choice of the material of the outer wall can be different Environmental requirements and sound conduction characteristics for given frequency ranges especially taken into account and be predetermined.

at a further preferred embodiment the pipe muffler according to the invention has the outer wall Outside an insulation on.

These Insulation provides additional sound insulation as well as a damping the reverberant outer wall. For this Insulation are particularly suitable materials that the Schallharte Exterior wall in restrict the vibration excitation and themselves a good sound-damping behavior exhibit. As a material can therefor preferably rubber and more preferably foam or other insulating materials be used.

at a further preferred embodiment the pipe muffler according to the invention has the pipe silencer several inner channels on.

It can also several inner channels be provided. An advantage here is that the individual Canal exterior walls, one damping cause the sound waves between the channels. For example have to Sound waves from an inner, surrounded by other channels channel only through the Walls of the other channels pass through until they enter the space between the channels and the outer wall reach. This will still change the sound attenuation behavior achieved.

at a further preferred embodiment of the pipe silencer according to the invention are one or more of the separation segments substantially orthogonal to aligned in the axial direction of the inner channel.

Prefers the separation segments are substantially orthogonal to the axial direction aligned with the inner channel.

It is also a method of using a pipe silencer in Sense of the present invention, wherein sound pressure waves through the inlet opening into the inner channel, the sound pressure waves through Friction at the micro-openings and reflection on the outside wall and are reduced in amplitude at the separating segments and the muted ones Sound pressure waves leave through the outlet opening of the pipe silencer.

Further The present invention comprises the use of a pipe silencer according to the invention for execution a method for use of a pipe silencer according to the invention in particular for targeted reduction of the intensity of sound waves.

in the Below is to further advantageous embodiments of the invention explained with reference to the figures become. This shows

1 A schematic sectional view of a pipe muffler according to the invention.

2 A schematic sectional drawing of a pipe silencer according to the invention ent long section line AB off 1 ,

3 A schematic sectional view of a pipe muffler according to the invention along the section line AB 1 ,

4 A schematic sectional view of a pipe muffler according to the invention with varying pitch.

5 A schematic representation of a pipe silencer according to the invention with adjustable radial distance s along the section line AB 1 ,

6 A diagram with a representation of the radial distance s over the circumference in an adjustable pipe silencer according to the invention.

1 shows a schematic sectional view of a pipe muffler according to the invention. microopenings 15 are at the periphery of an inner channel 10 arranged. The channel 10 has an inlet opening 12 and an outlet opening 14 on. An outer wall 30 surrounds the inner channel 10 coaxial. separating segments 20 are orthogonal between the inner channel 10 and the outer wall 30 arranged. The individual separation segments have different distances d, d ', d' to each other and separate the space between the inner channel 10 and the outer wall 30 in the axial direction into individual chambers. The inner channel 10 points from the outside wall 30 a first radial distance s1 and a second radial distance s2.

In use, the sound waves pass through the inlet opening 12 into the pipe silencer. The sound waves pass through the micro-openings 15 through, where they lose energy due to the friction occurring. The sound waves then hit the outside wall 30 and reflected to a large extent. When hitting the tennis segments 20 the sound waves are also reflected. Finally, the sound waves reduced in their amplitude pass through the outlet opening 14 from the pipe silencer.

The respective opposite reverberant walls of the outer wall 30 and the separator segments 20 cause intervening λ / 4 waves to form. Because the distances between the separation segments 20 and also between the inner channel 10 and the outer wall 30 are different, forming individual cavity resonators with different λ / 4 wavelengths. The sound-absorbing effect is thus given for different sound frequencies. In addition, as the sound passes through the microapertures 15 of the inner channel 10 in the space between the inner channel 10 and the outer wall 30 Viscous wall friction, which leads to broadband losses in the sound waves. By the combination of resonator with different axial wall spacings d and radial wall distances s in each case based on a wavelength range with the spacing of λ / 4 waves and absorber by means of the micro-openings 15 the sound damping effect is given in the pipe silencer according to the invention over a wide frequency range.

In 2 is the pipe silencer of the invention 1 in a schematic sectional view along the section line AB 1 shown. 1. The cylindrical inner channel 10 is inside the cylindrical outer wall 30 arranged. The axes of inner channel 10 and outer wall 30 are arranged offset. There are different radial distances s between the inner channel 10 and the outer wall 30 entered. The distance varies between s1 as the smallest distance and s2 as the largest distance.

This results in a different radial distance s for the out of the micro-openings 15 to the outer wall 30 emerging sound waves, depending on where the sound waves on the circumference of the inner channel 10 escape.

By the distance spectrum is a broadband acoustic damping behavior given.

In 3 is the pipe silencer of the invention 1 in a schematic sectional view along the section line AB 1 shown. 3 differs from 2 in that the outer wall 30 has a rectangular cross-section.

Due to the rectangular cross-sectional shape is the distance distribution between the inner channel 10 and the outer wall 30 trained differently. Here, the difference between the shortest distance and the longest distance is larger than in the arrangement 2 ,

By the distance spectrum is a broadband acoustic damping behavior for another Frequency spectrum given.

4 shows a schematic sectional view of a pipe muffler according to the invention. In principle corresponds 4 of the 1 , the separating segments 20 are here but as a helix shaped band 20 formed with changing pitch around the inner channel around trained.

Shown is how the now changing big ßen distances between the individual turns of the separation segment band 20 allow different λ / 4 standing waves.

Through this spectrum of axial distances between the individual turns of the Trennsegmentbandes 20 a wider range of attenuation is possible than with simple straight separation segments 20 ,

In 5 is the pipe silencer of the invention 1 in a schematic sectional view along the section line AB 1 shown as well as in 2 the case is. Here, however, is a non-circular inner channel 10 in a non-round outer wall 30 arranged. Furthermore, here is the inner channel 10 against the outer wall 30 rotatable about the longitudinal axis. Shown is the angle of rotation ω around the inner channel 10 against over the outer wall 30 is twisted. The angle α indicates an angle, below which along a straight line through the center of the inner channel 10 and then at this angle α to the outer wall 30 runs, the distance between the inner channel 10 and outer wall 30 is measured.

In 6 are for the pipe silencer according to the invention as in 5 show the distance values between the inner channel 10 and the outer wall 30 shown for two different angles of rotation ω.

It can be seen that the distance spectrum, ie the difference between the largest distance value and the smallest distance value, from the angular position of the rotation of the inner channel 10 to the outer wall 30 depends. Thus, with an angular position of ω = 0 °, the distance spectrum is smaller here than at an angle of ω = 90 °.

Therefore but also the resonance and the damping behavior are different for both Angular positions. This makes it possible via the angular position of the damping behavior of the pipe silencer to change.

1

silencer

10

inner channel

12

inlet port

14

outlet

15

microopenings

20

separating segments

30

outer wall

35

insulation

d

axial distances between the separation segments

d1

first axial distance

d2

second axial distance

S

radial Distance between the inner channel and the outer wall

S1

first radial distance

S2

second radial distance

S _i

radial Distance i

λ

wavelength

Claims (27)

Pipe silencer ( 1 ) for the targeted reduction of the intensity of sound waves, comprising an inner channel ( 10 ) with micro-openings ( 15 ) and one the inner channel ( 10 ) at least partially surrounding outer wall ( 30 ), characterized in that additionally separating segments ( 20 ) between the inner channel ( 10 ) and the outer wall ( 30 ) are provided, which define individual distances (d) in the axial direction between the separating segments, wherein the axial distances (d), at least a first axial distance (d1) and a second axial distance (d2) include, wherein the radial distance (s ) between the surface of the inner channel ( 10 ) and the outer wall ( 30 ) comprises at least a first radial distance (s1) and a second radial distance (s2). Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the outer wall ( 30 ) and the inner channel ( 10 ) are arranged axially parallel. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the outer wall ( 30 ) and the inner channel ( 10 ) are aligned coaxially. Pipe silencer ( 1 ) according to one of the preceding, characterized in that the radial distances (s) and / or the axial distances (d) are variable. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the distances (s) by the rotation of the outer wall ( 30 ) and / or the inner channel ( 10 ) are changeable. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the axial alignment of the outer wall ( 30 ) and the inner channel ( 10 ) is mutually variable. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the outer wall ( 30 ) and / or the inner channel ( 10 ) a cross section from the group: circular, square, oval, rhombic, symmetrical polygonal, polygonal with rounded corners. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the outer wall ( 30 ) has an outer contour with surfaces and these connecting rounded edges. Pipe silencer ( 1 ) characterized according to the preceding, that the outer wall ( 30 ) at one end with an inlet opening ( 12 ) and at the other end with an outlet opening ( 14 ) of the inner channel, is tightly connected. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the micropores ( 15 ) on the inner channel ( 10 ) have a diameter smaller than 1 mm, in particular less than 0.5 mm, in particular less than 0.1 mm. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the proportion of micropores ( 15 ) on the inner channel ( 10 ) less than 10% of the total surface of the inner channel ( 10 ), in particular less than 5% of the total surface of the inner channel ( 10 ), in particular less than 2% of the total surface of the inner channel ( 10 ) is. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the micropores ( 15 ) on the inner channel ( 10 ) have a geometric shape from the group consisting of: circular, square, oval, diamond-shaped, symmetrically polygonal. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the inner channel ( 10 ) Has tissue. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that one or more of the separating segments ( 20 ) substantially orthogonal to the axial direction of the outer wall ( 30 ) are aligned. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that one or more of the separating segments ( 20 ) have no planar shape, in particular a shape from the group of: cone part, ball part, ellipsoid part, paraboloid part, pyramid part. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that one or more of the separating segments ( 20 ) are arranged at an angle greater than 5 ° to each other, in particular greater than 20 ° are arranged, in particular greater than 40 ° are arranged. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that one or more of the separating segments ( 20 ) formed as a helix-shaped band which screws around the inner channel are formed. Pipe silencer ( 1 ) according to the preceding one, characterized in that one or more of the separating segments ( 20 ) formed as a helix-shaped band which screws with changing pitch around the inner channel around. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that one or more of the separating segments ( 20 ) are adjustable. Pipe silencer ( 1 ) according to one of the preceding, characterized in that it is composed of a plurality of individual successively arranged segments, which are connectable to each other. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the outer wall ( 30 ) is hard-hitting. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the material of the outer wall ( 30 ) contains an element from the group of: Fe, Pt, Cr, Cu, Ni, C, in particular metal or plastic. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the outer wall ( 30 ) has insulation on the outside. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that the pipe silencer ( 1 ) several inner channels ( 10 ) having. Pipe silencer ( 1 ) according to one of the preceding claims, characterized in that one or more of the separating segments ( 20 ) substantially orthogonal to the axial direction of the inner channel ( 10 ) are aligned. Method for using a pipe silencer ( 1 ) according to one of the preceding claims, characterized in that sound pressure waves through the inlet opening ( 12 ) into the inner channel, the sound pressure waves by friction at the micro-openings ( 15 ) and reflection on the outer wall ( 30 ) and at the separating segments ( 20 ) are reduced in amplitude and the attenuated sound pressure waves through the outlet opening ( 14 ) the pipe silencer ( 1 ) leave. Use of a pipe silencer ( 1 ) after one of the foregoing to a pipe muffler ( 1 ) directed claims for performing a method according to one of the preceding, directed to a method claims, in particular for the targeted reduction of the intensity of sound waves from a pipe.