CN212724716U - Silencing device and silence pipeline that has it - Google Patents

Abstract

The utility model relates to a noise eliminator, it attaches to the pipeline with the mode of acoustic coupling with the sound of decay propagating to pipeline low reaches from the pipeline upstream, it includes: a bottom wall attached to the duct; a top wall disposed in generally parallel spaced relation to the bottom wall; a side wall for connecting the bottom wall and the top wall, wherein the bottom wall, the top wall and the side wall together define an interior cavity within which is disposed a sound propagation path including at least one of the inlet and at least one of the outlet, wherein the sound propagation path within the interior cavity is configured for bypassing a primary sound component from within the duct. Further, the utility model discloses still include a silence pipeline.

Description

Silencing device and silence pipeline that has it

Technical Field

The present invention relates to a flow path muffler device attached to a flow path through which gas and liquid flow in order to reduce noise transmitted through the flow path.

Background

The noise is the sound produced when the sounding body does irregular vibration, which can seriously hinder people from normally resting, studying and living. On one hand, noise pollution mainly comes from transportation, building construction, industrial noise, social noise, family life noise and the like, so that noise reduction is particularly important in order that the comfort level of people's life is not influenced by noise. On the other hand, in the field of carrying tools, strong noise generated during takeoff of the spacecraft is reduced, and damage to sensitive components can be reduced; the testability of reducing the noise of the engine of the submarine or the special vehicle is one of key technologies for improving the viability of the submarine or the special vehicle.

Conventionally, it is known that a noise damper is mounted in a flow path through which a gas and a liquid flow, in order to reduce the transmission of noise, since noise is transmitted as well as the flow of the fluid.

As a typical example, there is a problem that, in plants and buildings where the noise sources are large, the noise is easily transmitted through a pipe. To reduce these noises, it is generally considered to reduce the unwanted sound by inserting a muffler somewhere along the pipe.

As a common way, a barrier type muffler including a barrier material such as a pressed glass or mineral fiber fabric, a foam, or a polyester fiber as an energy absorbing material can be considered. Since sound is present in the flow, disposing the absorbing material in the form of baffles or sidewall linings in the flowing stream is an effective way to reduce the sound. However, this will inevitably lead to such adverse effects as pressure drop, noise generated by turbulence, and reduced volume flow.

Another common approach is the helmholtz resonator, which operates by changing the acoustic damping coefficient to reduce the acoustic reflections that are transmitted to the ports. In particular, it may comprise a closed acoustically resonant structure which communicates with the environment, for example through small holes. When the wavelength of the sound wave emitted to the resonance sound absorption structure is far larger than the aperture, the air in the cavity has elasticity, and the air column in the hole neck has certain mass and does reciprocating motion similar to a piston. Under the action of the sound waves, a part of sound energy is consumed as heat energy due to the damping effect of the neck wall. When the frequency of the incident acoustic wave matches the natural resonant frequency of the resonator, resonance is excited. However, in use, it has been found that the sound absorption effect is poor when the resonance frequency is deviated due to the maximum damping near the resonance frequency and the greatest consumption of sound energy, and such a helmholtz resonator is difficult to assemble the sound absorption structure into a desired overall shape according to the user's field conditions. On the other hand, it also causes undesirable resistance and influence on the normal flow of the fluid.

Sonotrodes are a new way of absorbing noise that has emerged in recent years. Compared with the traditional noise elimination mode, the sonotrode mainly forms a complex material with multilayer characteristics by designing the material characteristics, such as a multilayer composite material. Because the propagation speed of sound waves varies with the material characteristics, such complex materials are such that the incoming sound waves are increasingly accelerated in the material. When the sound wave is reflected in the material, the speed of the reflected wave propagating outwards becomes slower. Under the combined action of the two mechanisms, the complex material is similar to an acoustic black hole. Ideally, sound will not be transmitted out after it has passed into the material, resulting in almost 100% sound absorption. However, although the proposed sonotrode has good sound absorption performance, the current production technology and manufacturing process cannot reach the level of mass production of sonotrodes due to its small size and complex material characteristics and structure, and the manufacturing cost of such sonotrodes is high. It should be further noted that the existing sonotrodes can only absorb noise in a single frequency or a narrow frequency range, and therefore they cannot be applied to application scenarios requiring reduction of multiple frequencies or wide frequencies (such as ventilation ducts of air conditioning systems or air intake and exhaust ducts of automobiles, which not only generate single-frequency noise, but also generate significant wide-frequency noise).

Another significant disadvantage of using sonotrodes for acoustic damping is that the movement of the acoustic wave propagation medium, such as the air stream formed by air, is not taken into account. The existing sound metamaterial does not fully consider a ventilation design or even does not have a ventilation design, so that airflow in a pipeline can be subjected to wind resistance. Wind resistance can greatly reduce the ventilation efficiency of the duct, which also makes it difficult for sonotrodes to function properly in certain application scenarios.

Therefore, the industry still needs to provide a muffler device which is simple in manufacturing process, can meet the requirements of different application scenes, can effectively perform noise elimination in multiple frequency bands, and is compact in structure.

SUMMERY OF THE UTILITY MODEL

The present invention aims to provide a muffler device which can at least partially solve the above-mentioned deficiencies of the prior art.

According to an aspect of the present invention, there is provided a muffler device attached to a pipe in an acoustic coupling manner to attenuate sound propagating from an upstream of the pipe to a downstream of the pipe, the muffler device comprising: a bottom wall attached to the duct, wherein the bottom wall is provided with at least one inlet for receiving sound from upstream of the duct on an upstream side of the duct and at least one outlet for emitting sound downstream of the duct on a downstream side of the duct; a top wall disposed in generally parallel spaced relation to the bottom wall; a side wall for connecting the bottom wall and the top wall, wherein the bottom wall, the top wall and the side wall together define an interior cavity within which is disposed a sound propagation path including at least one said inlet and at least one said outlet, wherein the sound propagation path within the interior cavity is configured for bypassing a primary sound component from within the duct and the length of the sound propagation path is designed such that a phase difference between a bypassed sound component emanating through at least one said outlet and a primary sound component propagating within the duct from upstream to downstream of the duct is M times a half-wave period of the sound being attenuated or a sum of wavelengths of the bypassed sound component emanating and the primary sound component is N times the sound being attenuated, wherein M is an odd number and N is a positive integer number.

Compare with current super material of sound and traditional helmholtz resonant cavity, according to the utility model discloses a noise eliminator has following apparent advantage at least: the utility model discloses a noise eliminator simple structure, to the requirement of form tolerance and geometric design low, need not costly precision finishing or high manufacturing compactness. And simultaneously, the utility model discloses a noise eliminator compact structure, it is low to installation space's requirement.

As a preferred aspect of the present invention, the muffler device further comprises at least one guide wall provided in the internal cavity in a parallel spaced manner, wherein the guide wall is configured to define a meandering sound propagation path within the internal cavity between at least one of the inlets and at least one of the outlets, wherein the length of the sound propagation path and the length of the main sound component passing through at least one of the inlets and at least one of the outlets within the pipe differ from each other by a positive integer multiple of half the wavelength of the attenuated sound.

As a preferred aspect of the present invention, the muffler device includes a plurality of inlets provided at an interval from each other on the upstream side of the pipe and one outlet provided on the downstream side of the pipe, wherein the lengths of sound propagation paths each formed by the plurality of inlets with respect to the one outlet respectively differ from the lengths of the attenuated sounds different in frequency by a positive integer multiple of half the wavelength of the attenuated sounds different in frequency in the pipe, thereby allowing the muffler device to attenuate the sounds different in frequency propagating in the pipe.

As a preferred aspect of the present invention, the muffler device is designed to be in a substantially square shape that is attached to a rectangular pipe in a form-fitting manner or in a substantially fan shape that is attached to a circular pipe in a form-fitting manner, thereby allowing the muffler device to be used as a reinforcement for reinforcing the pipe. From this, set up the utility model discloses a noise eliminator can strengthen original silence pipeline's intensity, reduced the silence pipeline for example because of the vibrations that the air current changes and arouse.

As a preferred aspect of the present invention, the inlet and/or the outlet of the muffler device are designed as a plurality of holes arranged on the bottom wall, wherein the apertures of the plurality of holes are designed such that the muffler device only receives sound from the inside of the pipe without affecting the flow in the pipe.

As a preferred aspect of the present invention, the muffler device is designed to be substantially spiral-shaped attached to a circular pipe in a spiral winding manner.

The utility model discloses still relate to a silence pipeline, wherein the silence pipeline is including setting up the pipeline import that is used for receiving sound at the upper reaches and the pipeline export that is located the outside sound that spreads of low reaches, its characterized in that silence pipeline has a plurality of in its pipe wall post with the utility model discloses a noise eliminator, wherein as first group a plurality of noise eliminator are in the first position of pipe wall and are arranged with the mode of connecting in parallel each other, with the permission the silence pipeline can attenuate a plurality of sounds of propagating in the pipeline with different frequencies. Thereby, the requirements of different application scenes (reducing the noise of a certain frequency, a certain narrow frequency band or a wide frequency band) can be met.

As a preferred aspect of the present invention, there is further included a plurality of the muffling devices as a second group arranged at intervals downstream of the pipe with respect to the first portion, wherein the plurality of muffling devices of the first group and the plurality of muffling devices of the second group are arranged in series with each other to allow the silent pipe to attenuate a plurality of sounds propagating in the pipe at different frequencies.

As a preferable aspect of the present invention, the plurality of muffling devices of the first group and/or the second group are attached to the pipe wall of the silent pipe in a manner of surrounding at least the silent pipe.

As a preferred aspect of the present invention, the first group and/or the second group of the plurality of muffling devices are disposed in close proximity to each other so as to be attached to the pipe wall of the silent pipe.

Additional features and advantages of the invention will be set forth in part in the description which follows, and in part will be apparent to those having ordinary skill in the art upon examination of the following, or may be learned from the practice of the invention.

Drawings

Embodiments of the present invention are described in detail below with reference to the attached drawing figures, wherein:

fig. 1 shows a front view of a first embodiment of a silencing device according to the invention, with parts transparentized to better show the internal structure of the device;

fig. 2 shows a front view of a silencer duct with the silencer device of fig. 1;

FIG. 3 shows a front view of a plurality of first embodiments of the muffling apparatus of the present invention in a series arrangement, with portions of the components being transparentized to better illustrate the internal structure of the apparatus;

FIG. 4 shows a front view of the silent pipe with the muffling apparatus of FIG. 3 with portions of the components being transparentized to better illustrate the internal structure of the apparatus;

fig. 5 shows a front view of a silencer duct with a second embodiment of the silencer device according to the invention;

FIG. 6 shows a front view of a silencer duct with multiple silencers of FIG. 5 arranged in parallel;

FIG. 7 shows a front view of a silent pipe with a plurality of muffling devices of FIG. 5 in a series-parallel arrangement;

fig. 8 shows a front view of a third embodiment of a silencing device according to the invention, with parts transparentized to better show the internal structure of the device;

fig. 9 shows a front view of a silencer duct with a plurality of the silencer devices of fig. 8:

fig. 10 shows a front view of a fourth embodiment of a silencing device according to the invention, with parts transparentized to better show the internal structure of the device;

fig. 11 shows a front view of a silencer duct with the silencer device of fig. 10.

Description of the reference numerals

10. 10A, 10B, 10C, 10D, 10E, 10F, 10G

11. Bottom wall 12, top wall 13, side walls 14, 14A, 14B, inlet

141. Hole 15, outlet 20, 20a, pipe 21, 21a, pipe inlet

22. 22a. pipe outlet s. upstream x. downstream d. length of propagation path within pipe

B. Bypass sound component M main sound component

Detailed Description

Referring now to the drawings, illustrative aspects of the disclosed muffler assembly will be described in detail. Although the drawings are provided to present some embodiments of the invention, the drawings are not necessarily to scale of particular embodiments, and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the disclosure of the present invention. The position of some components in the drawings can be adjusted according to actual requirements on the premise of not influencing the technical effect. The appearances of the phrase "in the drawings" or similar language in the specification are not necessarily referring to all drawings or examples.

It will be understood that when an element is referred to as being "attached" to another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "attached" to another element, it can be directly attached to the other element or intervening elements may also be present. Certain directional terms used hereinafter to describe the accompanying drawings, such as "upstream," "downstream," "front," "rear," "inner," "outer," "above," "below," and other directional terms, will be understood to have their normal meaning and refer to those directions as normally referred to in the drawings. Unless otherwise indicated, the directional terms described herein are generally in accordance with conventional directions as understood by those skilled in the art. The terms "first," "second," and the like, as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another.

Some embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

In fig. 1, a first embodiment of a muffler device 10 according to the present invention is shown, the muffler device 10 being generally rectangular in shape, as shown in fig. 1, having a bottom wall 11 below, a top wall 12 disposed in parallel spaced relation to the bottom wall 11, and side walls 13 for connecting the bottom wall 11 and the top wall 12 together along four sides of the bottom wall 11 to define an internal cavity. As shown in fig. 1, an inlet 14 for introducing external sound is provided on the bottom wall 11 at the upper left of fig. 1, wherein the inlet 14 is designed as a plurality of holes 141 arranged on the bottom wall 11, and an outlet 15 for discharging sound passing through a sound propagation path (described in detail below) in the internal cavity is provided on the bottom wall 11 at the lower right of fig. 1, wherein the outlet may also be designed as a plurality of holes 141 arranged on the bottom wall 11. It should be noted that the relative positional relationship between the inlet 14 and the outlet 15 in fig. 1 is merely exemplary, and those skilled in the art will readily recognize that the arrangement positions of the inlet 14 and the outlet 15 may be exchanged or modified.

In order to control the length over which sound entering the silencing device 10 from the inlet 14 travels to the outlet 15, from which sound can emerge to the outside, at least one guide wall 16 is arranged in parallel spaced apart fashion in the interior of the silencing device 10. In the muffler device 10 shown in fig. 1, four guide walls 16 are provided in parallel at equal intervals, wherein each of the four guide walls 16 is connected to the side wall 13 of the muffler device 10 and has a length smaller than the width of the muffler device 10, i.e., the four guide walls 16 are arranged in the width direction of the muffler device at a distance from the side wall 13. Since the thickness of the guide walls 16 is designed to be substantially acoustically opaque, the plurality of guide walls 16 arranged in parallel at intervals can define a meandering sound propagation path within the internal cavity (see reference character B in fig. 1). It will be appreciated by those skilled in the art that the length of the sound propagation path within the interior cavity or the time required for sound transmitted into the muffler assembly 10 through the inlet 14 to exit the outlet 15 through the muffler assembly 10 can be adjusted by adjusting the number of guide walls 16 disposed within the interior cavity, changing the distance between the guide walls 16, the distance of the guide walls 16 from the side walls 13, etc. Here, the guide walls 16 may be fixed within the internal cavity of the muffler device 10 by milling several grooves in the bottom wall 11 or the top wall 12 for the insertion of the guide walls 16 into these milled grooves. Alternatively, the guide wall 16 may be fastened to the top wall 12 or the bottom wall 11 of the muffler device 10 by means of gluing, welding or fusion.

In fig. 2, a sound-deadening duct 20 with the muffler device 10 of fig. 1 is shown, wherein both fluid (e.g., air) and/or sound can travel through the sound-deadening duct 20 from an upstream S in fig. 2 to a downstream X of the sound-deadening duct 20. As an example of the silencing duct 20, the duct 20 may be a ventilation duct of various air conditioning ventilation systems, an intake duct or an exhaust duct of a vehicle such as an automobile, a warm air duct or a ventilation duct in a house building, and the like. In various application scenarios, it is desirable to attenuate the sound propagating within the sound-deadening duct 20 by means of the sound attenuating device 10, as will be described in detail below.

As shown in fig. 2, in order to achieve attenuation of sound propagating through the silencing duct 20 from its upstream S to the downstream X of the silencing duct 20, the muffler device 10 in fig. 1 is attached to the silencing duct 20 in an acoustically coupled manner. As shown in fig. 2, the silencing duct 20 shown here as an example is a duct having a substantially rectangular cross section, in which case the bottom wall 11 of the silencing device 10 is attached to the wall of the silencing duct 20 in a form-fitting manner. Specifically, the bottom wall 11 of the muffler device 10 may be attached to the pipe wall of the silencing pipe 20 by means of bonding or fastening members in such a manner that the inlet 14 of the muffler device 10 is immediately upstream S of the silencing pipe 20 and the outlet 15 is immediately downstream X of the silencing pipe 20 (as shown in fig. 2). Here, it is preferable that the inlet 14 and the outlet 15 are communicated. Due to the inlet 14 and the outlet 15 being a plurality of holes 141 arranged on the bottom wall 11, the aperture of the holes 141 can be designed so that the muffler device receives only sound from the inside of the pipe without affecting the flow in the pipe by properly designing the aperture. It should be noted that the specific size of the hole 141 can be adaptively and optimally designed according to the cross-sectional area of the muffler device and the moving speed of the fluid in the silencing pipe 20. As an example, the suitable pore diameter range of the pores 141 can be obtained by computer aided flow calculation or finite element analysis, and the above design is within the capability of those skilled in the art, and therefore will not be described herein.

After the muffler device 10 is placed in position on the pipe wall of the silencing pipe 20, as shown in fig. 2, the sound desired to be attenuated may propagate from upstream S to downstream X through the silencing pipe 20 via the pipe inlet 21 of the silencing pipe 20 and finally out through the pipe outlet 22. As shown in fig. 2, when the sound coming in through the pipe inlet 21 reaches the position of the inlet 14 of the muffler device 10, since the muffler device 10 is acoustically coupled with the silencing pipe 20 (i.e., the muffler device 10 can be acoustically regarded as a bypass branch of the silencing pipe 20), the sound desired to be attenuated can propagate downstream in two acoustic propagation paths at the position of the inlet 14 of the muffler device 10, i.e., can be divided into a main sound component (denoted by M in fig. 2) continuing to propagate in the silencing pipe 20 and a bypass sound component (denoted by B) propagating in the muffler device 10.

In the case of the construction shown in fig. 2, the main sound component M continuing to travel in the sound-damping duct 20 will meet again at the location of the outlet 15 of the sound-damping device 10 with the bypass sound component B traveling in the sound-damping device 10, the length of the acoustic path traveled by the main sound component M being denoted D, and the length of the acoustic path traveled by the bypass sound component B being appropriately selected as described above. In order to achieve the attenuation of the desired sound, a phase difference is generated by the different propagation distances of the main sound component M and the bypass sound component B, wherein the phase difference between the main noise component M through the silencer duct 20 and the bypass sound component B through the silencer device 10 is adjusted to be M times the half-wave period of the attenuated sound, wherein M is an odd number, for example, including 1 or 3. Alternatively, it is also possible, by appropriate design of the length of the acoustic propagation path within the silencing device 10 (for example by appropriate design of the guide wall 16), to have the sum of the wavelengths of the bypass sound component B that passes out of the outlet 15 of the silencing device 10 and the main sound component M that continues to propagate within the silencing duct 20 be a multiple N of the sound to be attenuated, where N is a positive integer. In both of the above two ways, the sound may be attenuated or disappeared due to the phenomenon of the opposite phase interference occurring when both the main sound component M and the bypass sound component B meet at the intersection. As a result, the sound coming out through the duct outlet 22 of the silencing duct 20 is significantly attenuated or even extinguished. As a practical matter, the length D of the acoustic propagation path within the mute tube 20 and the length of the acoustic propagation path through which the bypass sound component B passes in fig. 2 differ from each other by a positive integer multiple of half the wavelength of the attenuated sound.

As a non-limiting design, a cascade-coupled acoustic grid (two ports) with two ports may be estimated according to the frequency range of the sound to be attenuated by the inlet 14 and the outlet 15 of the sound eliminator 10 according to the sound transmission loss (e.g., decibels of the sound to be attenuated) required by the actual application scenario. Each node in the network represents the topology (n-product-like topology) of a muffler assembly 10 whose acoustic transfer function can be estimated from the low frequency model. The back transfer-matrix can then be used to calculate the acoustic losses of the entire network. This acoustic transmission loss will be subtracted from the acoustic transmission loss required by the actual application scenario and averaged over the frequency range, denoted as r. In order to optimize the network, the system may be optimized using the length and cross-sectional area of the muffler device 10 at each node as parameters and r as a target value to be minimized. It is possible to use a differential evolution algorithm for global optimization to obtain the values of the structural design parameters required for the silencing device 10. As an example, when the cross section of the silencing duct 20 shown in fig. 2 is a square with a side length of, for example, 8.9 centimeters, the silencing device 10 is also designed to be a square, with the side length of each side being, for example, 3.5 centimeters. When the noise desired to be attenuated is at 1060Hz and 1400 Hz. The sound attenuation device 10 with the above structural design parameters can reduce the sound transmitted in the silencing pipe 20 at 1060Hz by 62 decibels (dB) and reduce the sound at 1400Hz by 55 dB.

According to the utility model discloses a noise eliminator 10 compares with current sound metamaterial and traditional Helmholtz resonant cavity, all has following apparent advantage in the application of making an uproar falls in the pipeline of multiple difference: first, compared to existing acoustic superstructures of multilayer composite materials, since the muffler device 10 of the present invention is a large-sized simple structure with low requirements for shape tolerances and geometric design, no costly precision machining or high manufacturing compactness is required, which is certainly extremely advantageous for reducing the manufacturing costs of the muffler device 10. For example, the muffler device 10 according to the present invention may be manufactured from a common plastic process.

Meanwhile, the muffler device 10 of the present invention has a compact structure and requires a small installation space, which is very advantageous to simplify the installation of the muffler device 10 and to expand the application range of the muffler device 10. In particular, since the muffler device 10 itself is attached to the silencing pipe 20, the muffler device 10 itself is equivalent to the silencing pipe 20 being subjected to ribbing (ribbing), so as to strengthen the strength of the original silencing pipe 20 and reduce the vibration of the silencing pipe 20 caused by the change of the air flow.

Further, the utility model discloses a noise eliminator 10 has fine commonality and satisfies scene design. Specifically, according to the requirements of different application scenarios (reducing noise of a certain frequency, a certain narrow frequency band, or a wide frequency band), the above-described design method can be used to obtain an optimized geometric structure, and the noise reduction scheme meeting the requirements can be realized by adjusting the size of the geometric structure.

In order to reduce the different frequencies of sound propagating in the sound-damping duct 20, as a preferred embodiment, a plurality of muffling devices 10A-D are shown in series in fig. 3. Wherein the multiple muffling devices 10A-D have substantially the same configuration, differing only in that each has different dimensions to denoise different sound frequencies. As shown in fig. 3 to 4, 4 muffling devices 10A-D having different sizes are abutted closely adjacent to each other, wherein the opening arranged to the left in fig. 3 among the 4 muffling devices 10A-D is an inlet and the opening arranged to the right is an outlet, and wherein the length, width, and number and spacing distance of guide walls provided therein of the 4 muffling devices 10A-D are different, so that the 4 muffling devices 10A-D can attenuate sounds of different frequencies in the silencing duct 20 as one combination. Since the principle of the sound damping device 10A-D is the same as the sound damping device 10 in fig. 1, it will not be described in detail here.

The use of such combined muffling devices 10A-D in a silencing duct 20 is shown in fig. 4, in which 4 muffling devices 10A-D are arranged on the wall of a silencing duct 20, for example, of rectangular cross-section. Wherein sound incoming from the duct inlet of the silencing duct 20 passes downstream X from the upstream S of the silencing duct 20 and finally out of the duct outlet 20. As in the embodiment shown in fig. 1-2, since the sound desired to be attenuated is divided within the silent pipe 20 into a main sound component (denoted by M in fig. 4) continuing to propagate within the silent pipe 20 and bypass sound components (not shown) respectively propagating within the muffling apparatuses 10A-D, a phase difference is generated by different propagation distances of the main sound component M and the bypass sound component B, and finally the sound is attenuated or extinguished due to the phenomenon of reverse phase interference occurring when the main sound component M and the bypass sound components meet at the intersection. As a result, the sound coming out through the duct outlet 22 of the silencing duct 20 is significantly attenuated or even extinguished. As a practical matter, in fig. 4 the length of the acoustic propagation path within the mute conduit 20 and the length of the acoustic propagation path through which the bypass sound component passes differ from each other by a positive integer multiple of half the wavelength of the attenuated sound.

Fig. 5 shows a front view of a muffler device 10E of another structure, in which the muffler device 10E is provided with inlets 14A and 14B and a single outlet 15 which are provided on both sides in the width direction, unlike the embodiment of fig. 1. Thereby, it is allowed to simultaneously attenuate sounds of two different frequencies with a single muffler device 10E. Since the principle of the muffler device 10E attenuating sound is the same as that of the muffler device 10 in fig. 1, it will not be described again.

The application of such a muffler device 10E in the silencing pipe 20 is shown in fig. 5, in which the muffler device 10E is laid on the pipe wall of the silencing pipe 20, which is rectangular in cross section, for example. Wherein sound incoming from the duct inlet of the silencing duct 20 passes downstream X from the upstream S of the silencing duct 20 and finally out of the duct outlet 20. As in the embodiment shown in fig. 1-2, since the sounds of different frequencies desired to be attenuated are respectively transmitted into the muffler device 10E through the inlets 14A and 14B in the silencing duct 20, and are divided into a main sound component (denoted by M in fig. 5) continuously propagating in the silencing duct 20 and a bypass sound component (not shown) respectively propagating in the muffler device 10E, a phase difference is generated by different propagation distances of the main sound component M and the bypass sound component, and finally, the sound is attenuated or extinguished because of the phenomenon of phase-reversal interference when the main sound component M and the bypass sound component meet at the intersection. As a result, the sound coming out through the duct outlet 22 of the silencing duct 20 is significantly attenuated or even extinguished. As a practical matter, in fig. 5 the length of the acoustic propagation path within the mute conduit 20 and the length of the acoustic propagation path through which the bypass sound component passes differ from each other by a positive integer multiple of half the wavelength of the attenuated sound.

In fig. 6, a front view of a silent pipe 20 with a plurality of the muffling devices of fig. 5 arranged in parallel is shown, in which a plurality of muffling devices 10E are respectively arranged on the respective pipe walls of the silent pipe 20, which allows sound to be attenuated over a larger frequency range.

More preferably, in fig. 7, a front view of a silencing duct 20 with a plurality of silencing devices of fig. 5 arranged in series-parallel is shown. Here, a plurality of muffling devices 10E may be arranged in series upstream S and downstream X of the silencing duct 20 for different frequency sections, and each muffling device 10E absorbs a specific frequency. In order to reduce the sound absorption effect without causing interference between the upper and lower two adjacent muffling devices 10E, the distance between the muffling devices 10E may be optimized by means of mathematical simulation or the like. The method of optimization is within the ability of the person skilled in the art to determine the above design, for example, from the actual noise frequency and the pipe flow, and is therefore no longer redundant here.

In fig. 8, a front view of a third embodiment of a sound-damping device 10F according to the invention is shown, wherein the sound-damping device 10F, unlike the sound-damping device of fig. 1-7, is adapted to a sound-damping duct 20A having a circular cross-section. As shown in fig. 8, wherein the muffler assembly 10F is generally fan-shaped, it has a bottom wall that includes a lower portion, a top wall that is disposed in a parallel spaced relationship relative to the bottom wall, and side walls that connect the bottom wall and the top wall together along four sides of the bottom wall to define an interior cavity. As shown in fig. 8, an inlet 14 for the introduction of external sound is provided on the bottom wall at the lower left of fig. 8, wherein the inlet 14 is designed as a plurality of holes arranged on the bottom wall 11, and an outlet 15 for the outward sound passing through the sound propagation path in the internal cavity is provided on the bottom wall at the upper right of fig. 8, wherein the outlet may also be designed as a plurality of holes arranged on the bottom wall. It should be noted that the relative positional relationship of the inlet 14 and the outlet 15 in fig. 8 is merely an example, and those skilled in the art will readily recognize that the arrangement positions of the inlet 14 and the outlet 15 may be exchanged or modified.

In principle, as in the case of the sound-damping device 10 shown in fig. 1-2, in the case of the construction shown in fig. 8, the main sound component M which continues to travel in the sound-damping duct 20A will meet again at the location of the outlet 15 of the sound-damping device 10F with the bypass sound component B which travels in the sound-damping device 10F, the length of the acoustic path traveled by the main sound component M being denoted D and the length of the acoustic path traveled by the bypass sound component B being appropriately selected as described above. In order to achieve the attenuation of the desired sound, a phase difference is produced by the different propagation distances of the main sound component M and the bypass sound component B, wherein the phase difference between the main noise component M passing through the silencer duct 20A and the bypass sound component B passing through the silencer device 10F is adjusted to be M times the half-wave period of the attenuated sound or the length of the acoustic propagation path within the silencer device 10F (for example by appropriate design of the guide wall 16), such that the sum of the wavelengths of the bypass sound component B passing out of the outlet 15 of the silencer device 10 and the main sound component M continuing to propagate within the silencer duct 20A is N times the attenuated sound, where N is a positive integer. In both of the above two ways, the sound may be attenuated or disappeared due to the phenomenon of the opposite phase interference occurring when both the main sound component M and the bypass sound component B meet at the intersection. As a result, the sound coming out through the duct outlet 22 of the silencing duct 20A is significantly attenuated or even extinguished. As a practical matter, the length D of the acoustic propagation path within the mute tube 20A and the length of the acoustic propagation path through which the bypass sound component B passes in fig. 8 differ from each other by a positive integer multiple of half the wavelength of the attenuated sound.

As an example, when the cross section of the silencing duct 20A shown in fig. 8 is a circle having a diameter of, for example, 59 cm, the muffler device 10F is also designed as a fan shape having an opening angle of 60 degrees and a radial thickness of 2 cm. When the noise desired to be attenuated is at 550 Hz. The sound transmitted in the silent pipe 20A can be reduced by 50 decibels (dB) by the muffler device 10F having the above structural design parameters. It should also be noted that the muffler device 10F can also be used as a reinforcement for reinforcing the silent pipe 20A.

Fig. 9 shows a front view of a silencer duct 20A with several silencer devices according to fig. 8, in which, for example, 6 fan-shaped silencer devices 10F with an opening angle of 60 degrees are provided. This allows attenuation of sound over a larger frequency range. And simultaneously, the silent pipe 20A can be better reinforced.

In fig. 10 is shown a front view of a fourth embodiment of a sound-damping device 10G according to the invention, in which, unlike the sound-damping device in fig. 1-7, the sound-damping device 10(3 is adapted to a sound-damping duct 20A having a circular cross-section, as shown in fig. 10, in which the sound-damping device 10F is substantially spiral-shaped so as to spiral around the circular sound-damping duct 20A, having a bottom wall including a lower portion, a top wall arranged in parallel spaced relation to the bottom wall, and side walls for connecting the bottom wall and the top wall together along four sides of the bottom wall to define an inner cavity, as shown in fig. 10, on the left side of fig. 10 is provided an inlet 14 for the introduction of external sound, wherein here the inlet 14 is designed as a plurality of holes arranged in the bottom wall, and on the right side of fig. 10 is provided an outlet 15 for the outward passage of sound through a sound propagation path within the inner cavity, the outlet opening can also be designed as a plurality of holes arranged in the bottom wall.

The working principle of the muffler device 10G in fig. 10 is the same as that of the muffler device in fig. 1 to 9, and will not be described again.

Fig. 11 shows a front view of a silencer duct with a plurality of the silencer devices of fig. 10. In which for example 6 spiral muffling devices 10 (3) are provided, which allows sound to be attenuated over a larger frequency range, while at the same time better ribbing of the silent pipe 20A is possible.

It is to be understood that while the specification has been described in terms of various embodiments, it is not intended that each embodiment comprises a separate embodiment, and such descriptions are provided for clarity only and should be taken as a whole by those skilled in the art, and that the embodiments may be combined to form other embodiments as will be apparent to those skilled in the art.

The above description is only exemplary of the present invention, and is not intended to limit the scope of the present invention. Without departing from the concept and principles of the present invention, equivalent changes, modifications and combinations that may be made by those skilled in the art should be considered within the scope of the present invention.

Claims (10)

1. A muffling device attached to a pipe in an acoustically coupled manner to attenuate sound propagating from upstream of the pipe to downstream of the pipe, the muffling device comprising:

a bottom wall attached to the duct, wherein the bottom wall is provided with at least one inlet for receiving sound from upstream of the duct on an upstream side of the duct and at least one outlet for emitting sound downstream of the duct on a downstream side of the duct;

a top wall disposed in generally parallel spaced relation to the bottom wall;

a side wall for connecting the bottom wall and the top wall, wherein the bottom wall, the top wall and the side wall together define an interior cavity within which is disposed a sound propagation path including at least one said inlet and at least one said outlet, wherein the sound propagation path within the interior cavity is configured for bypassing a primary sound component from within the duct and the length of the sound propagation path is designed such that a phase difference between a bypassed sound component emanating through at least one said outlet and a primary sound component propagating within the duct from upstream to downstream of the duct is M times a half-wave period of the sound being attenuated or a sum of wavelengths of the bypassed sound component emanating and the primary sound component is N times the sound being attenuated, wherein M is an odd number and N is a positive integer number.

2. The muffling device of claim 1, further comprising at least one guide wall disposed in parallel spaced relation within the internal cavity, wherein the guide wall is configured to define a tortuous sound propagation path within the internal cavity between at least one of the inlets and at least one of the outlets, wherein the length of the sound propagation path and the length of the primary sound component through at least one of the inlets and at least one of the outlets within the conduit differ from each other by a positive integer multiple of half the wavelength of the sound being attenuated.

3. The muffling device of claim 2, wherein the muffling device comprises a plurality of inlets disposed at an upstream side of the pipe at a distance from each other and one outlet disposed at a downstream side of the pipe, wherein a length of a sound propagation path formed by each of the plurality of inlets with respect to the one outlet differs from a length of a sound propagation path formed by a different frequency of the attenuated sound passing through the plurality of inlets and the one outlet within the pipe by a positive integer multiple of half a wavelength of the different frequency of the attenuated sound, respectively, thereby allowing the muffling device to attenuate the different frequency of sound propagating within the pipe.

4. The muffling device of claim 2, wherein the muffling device is designed to be substantially square in shape to conform to a rectangular pipe or substantially fan-shaped in shape to conform to a circular pipe, thereby allowing the muffling device to be used as a reinforcement to stiffen the pipe.

5. The muffling device of claim 1, wherein the inlet and/or the outlet of the muffling device are designed as a plurality of holes arranged on the bottom wall, wherein the apertures of the plurality of holes are designed such that the muffling device receives only sound from within the pipe without affecting flow within the pipe.

6. The muffling device of claim 1, wherein the muffling device is designed to be in a substantially helical shape affixed to a circular pipe in a helical coil.

7. A silent pipe, wherein said silent pipe comprises a pipe inlet for receiving sound arranged upstream and a pipe outlet for outgoing sound arranged downstream, characterized in that said silent pipe has affixed to its pipe wall a plurality of sound-attenuating devices according to any one of claims 1 to 6, wherein said plurality of sound-attenuating devices as a first group are arranged in parallel with each other at a first location of the pipe wall, so as to allow said silent pipe to attenuate a plurality of sounds propagating in the pipe at different frequencies.

8. A silent pipe as claimed in claim 7, further comprising a plurality of said muffling devices as a second group arranged downstream of said pipe in spaced relation to said first location, wherein said first group of said plurality of muffling devices and said second group of said plurality of muffling devices are arranged in series with each other to allow said silent pipe to attenuate a plurality of sounds propagating within the pipe at different frequencies.

9. A silencer duct according to claim 8, wherein the first and/or second plurality of muffling devices are attached to a wall of the silencer duct so as to surround at least the silencer duct.

10. A silencer duct according to claim 8, wherein the first and/or second plurality of silencing devices are arranged in close proximity to each other and affixed to the wall of the silencer duct.

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