Meta muffler

Abstract

The present invention relates to a meta muffler capable of effectively reducing, over a wide band, low frequency noise that leaks through piping and is generated in various engines, machines and instruments in vehicles, ships, aircraft, factories and the like.

Description

Meta Silencer

[0001] The present invention relates to a meta silencer that can effectively reduce noise generated through pipes from various engines, machines, and devices in automobiles, ships, aircraft, factories, etc.

[0002] In general, silencers are appropriately used to effectively reduce low-frequency and high-frequency noise generated from various engines, machines, and devices in automobiles, ships, aircraft, and factories.

[0003] These silencers can be broadly classified into three types: reflective silencers that reduce noise by utilizing impedance mismatch, absorptive silencers that reduce noise by converting acoustic energy, and hybrid silencers that combine reflective and absorptive silencers.

[0004] Here, reflective silencers have the advantage of being easy to design, manufacture and maintain, but they have the disadvantage of having poor sound absorption performance in the high-frequency range and requiring a relatively large size.

[0005] And although absorptive silencers have the advantage of excellent sound absorption performance in various frequency ranges, they have the disadvantage of being difficult to design due to their complex structure and requiring relatively high costs for manufacturing and maintenance.

[0006] In addition, although hybrid silencers have the advantage of complementing the shortcomings of reflective and absorbing silencers, they have the disadvantage of requiring complex designs to optimize the combination of reflective and absorbing silencers.

[0007] That is, conventional hybrid silencers have a structure that applies micro-perforated panels or membranes to existing silencers to improve sound absorption performance, but they have limitations in terms of durability and inability to properly control broadband low-frequency noise.

[0008] Therefore, research and development of a silencer structure that can effectively remove broadband low-frequency noise and exhibit excellent durability is necessary for application to various engines, machines, and devices in automobiles, ships, aircraft, and factories.

[0009] The present invention was invented to solve the above-mentioned problems, and its purpose is to provide a meta silencer having a structure that can effectively remove even broadband low-frequency noise and exhibit excellent durability so as to reduce noise generated from various engines, machines, and devices in automobiles, ships, aircraft, and factories.

[0010] The purpose of the present invention is not limited to the purpose mentioned above, and other purposes not mentioned can be sufficiently included in the purpose of the present invention while being clearly understood from the description below.

[0011] In order to achieve the above object, the meta silencer according to the present invention is installed on a pipe through which noise passes, and may be configured as a unit resonator in which a communication hole is perforated on the lower surface of the front end to communicate with the inside of the pipe, a cavity is provided at the rear end, and a first slit unit and a second slit unit are installed facing each other with a space therebetween on the inner left and right surfaces between the communication hole and the cavity.

[0012] The first slit unit may be configured with a plurality of first slits that are spaced apart from each other so that a first individual sound-absorbing space is provided therebetween and that gradually increase in length from the communication hole to the cavity, and the second slit unit may be configured with a plurality of second slits that are spaced apart from each other so that a second individual sound-absorbing space is provided therebetween and that gradually increase in length from the communication hole to the cavity.

[0013] The first slit and the second slit may have different lengths, and the first slit unit and the second slit unit may be formed asymmetrically according to the different lengths of the first slit and the second slit.

[0014] The first slit may have at least one first bend formed at an end thereof to extend the length of the first individual sound-absorbing space, and the second slit may have at least one second bend formed at an end thereof to extend the length of the second individual sound-absorbing space.

[0015] The above unit resonators are responsible for a certain length of the pipe and are composed of a plurality of units, and can be installed connected to each other while forming a shape corresponding to the cross-sectional shape of the pipe along the circumference of the pipe.

[0016] The above unit resonators are configured in multiple units and are responsible for a certain length of the pipe, and are installed so as to be connected to each other while forming a shape corresponding to the cross-sectional shape of the pipe around the pipe, and can be installed in multiple stages along the length of the pipe.

[0017] The meta silencer according to the present invention with the above-described configuration can be expected to have the following effects.

[0018] First, the first individual sound-absorbing space and the second individual sound-absorbing space according to the plurality of first slits and second slits provided in an asymmetrical shape inside the unit resonator can effectively block not only high-frequency noise passing through the pipe but also low-frequency noise and ultra-low-frequency noise through the joint action.

[0019] And, as at least one first bend and one second bend are formed in each of the plurality of first slits and second slits, the length of the first individual sound-absorbing space and the second individual sound-absorbing space is extended, so that low-frequency noise can be blocked in a wide band.

[0020] FIG. 1 is a perspective view illustrating a unit resonator forming a meta silencer according to a preferred embodiment of the present invention.

[0021] FIG. 2 is a plan view showing a unit resonator forming a meta silencer according to a preferred embodiment of the present invention.

[0022] Figure 3 is an exemplary diagram showing a state in which a meta silencer is applied in parallel according to a preferred embodiment of the present invention.

[0023] Fig. 4 is an exemplary diagram showing a state in which a meta silencer according to a preferred embodiment of the present invention is applied in a series-parallel configuration.

[0024] FIG. 5 is a cross-sectional view of a first form of a meta silencer according to a preferred embodiment of the present invention, and a diagram showing the acoustic transmission loss and acoustic pressure field mode thereof, respectively.

[0025] FIG. 6 is a diagram showing the reflectivity and group velocity according to the first form of the meta silencer according to a preferred embodiment of the present invention.

[0026] FIG. 7 is a cross-sectional view of a second form of a meta silencer according to a preferred embodiment of the present invention, and a diagram showing the acoustic transmission loss and acoustic pressure field mode thereof, respectively.

[0027] Fig. 8 is a diagram showing the reflectivity and group velocity according to the second form of the meta silencer according to a preferred embodiment of the present invention.

[0028] In order to achieve the above object, the meta silencer according to the present invention is installed on a pipe through which noise passes, and may be configured as a unit resonator in which a communication hole is perforated on the lower surface of the front end to communicate with the inside of the pipe, a cavity is provided at the rear end, and a first slit unit and a second slit unit are installed facing each other with a space therebetween on the inner left and right surfaces between the communication hole and the cavity.

[0029] The first slit unit may be configured with a plurality of first slits that are spaced apart from each other so that a first individual sound-absorbing space is provided therebetween and that gradually increase in length from the communication hole to the cavity, and the second slit unit may be configured with a plurality of second slits that are spaced apart from each other so that a second individual sound-absorbing space is provided therebetween and that gradually increase in length from the communication hole to the cavity.

[0030] The first slit and the second slit may have different lengths, and the first slit unit and the second slit unit may be formed asymmetrically according to the different lengths of the first slit and the second slit.

[0031] The first slit may have at least one first bend formed at an end thereof to extend the length of the first individual sound-absorbing space, and the second slit may have at least one second bend formed at an end thereof to extend the length of the second individual sound-absorbing space.

[0032] The above unit resonators are responsible for a certain length of the pipe and are composed of a plurality of units, and can be installed connected to each other while forming a shape corresponding to the cross-sectional shape of the pipe along the circumference of the pipe.

[0033] The above unit resonators are configured in multiple units and are responsible for a certain length of the pipe, and are installed so as to be connected to each other while forming a shape corresponding to the cross-sectional shape of the pipe around the pipe, and can be installed in multiple stages along the length of the pipe.

[0034] The present invention relates to a meta silencer that can effectively reduce noise generated through pipes from various engines, machines, and devices in automobiles, ships, aircraft, factories, etc.

[0035] In particular, the meta silencer according to the present invention is characterized by being able to effectively reduce even broadband low-frequency noise and exhibiting excellent durability.

[0036]

[0037] Hereinafter, a meta silencer according to a preferred embodiment of the present invention will be described in detail with reference to the attached drawings.

[0038] A meta silencer (100) according to a preferred embodiment of the present invention may be composed of at least one unit resonator (200) installed in communication with one side of a pipe (P) through which noise passes or installed to form a certain section of the pipe (P).

[0039] That is, the meta silencer (100) according to a preferred embodiment of the present invention may have a form in which one unit resonator (200) is installed alone on one side of the pipe (P), as shown in FIG. 3, a plurality of unit resonators (200) may form a certain section of the pipe (P) and may be arranged in a shape corresponding to the shape of the pipe (P) along the outer periphery of the pipe (P) and may have a parallel form connected to each other, as shown in FIG. 4, may form a part of the pipe (P) and may have a series-parallel composite form in which the parallel forms form multiple stages along the length of the pipe (P).

[0040]

[0041] Meanwhile, the unit resonator (200) may be composed of a body (210) having a cylindrical shape as illustrated in FIGS. 1 and 2, a communication hole (220) perforated on the lower end of the front end of the body (210) to communicate with the inside of the pipe (P), a cavity (230) provided at the rear end of the body (210), and a first slit unit (240) and a second slit unit (250) which are installed facing each other with a gap between them on the left and right inner surfaces of the body (210) in the section between the communication hole (220) and the cavity (230).

[0042]

[0043] Here, the body (210) can have a shape corresponding to the outer circumference of the pipe (P) so that it can be installed on the pipe (P) or can form a part of the pipe (P).

[0044] And the first slit unit (240) may be composed of a plurality of first slits (241) that are spaced apart so that each first individual sound-absorbing space (242) with an open entrance is provided, and whose length gradually increases from the front end to the rear end of the body (210).

[0045] In addition, the second slit unit (250) may be configured with a plurality of second slits (251) that are spaced apart so that each second individual sound-absorbing space (252) with an open entrance is provided, and whose length gradually increases from the front end to the rear end of the body (210).

[0046] That is, the gap between the first slit unit (240) and the second slit unit (250) can be formed into a horn shape due to the difference in length according to the installation positions of the first slit (241) and the second slit (251).

[0047]

[0048] Accordingly, high-frequency noise and low-frequency noise passing through the inside of the pipe (P) can be reduced by being absorbed by the first individual sound-absorbing space (242) and the second individual sound-absorbing space (252) according to the first slit (241) and the second slit (251) after being introduced into the inside of the front end of the body (210) through the communication hole (220) before being discharged to the outside.

[0049] And the ultra-low frequency noise that is not absorbed by the first slit (241) and the second slit (251) can be reduced by being absorbed by the cavity (230) inside the rear end of the body (210) after passing through the first slit (241) and the second slit (251).

[0050] In addition, as the lengths of the first slit (241) and the second slit (251) gradually increase in length by position, the lengths of the first individual sound-absorbing space (242) and the second individual sound-absorbing space (252) separated therebetween also gradually increase in length by position, thereby causing a gradual change in acoustic impedance and reducing the reflection component of wave energy moving inward, thereby effectively absorbing and reducing low-frequency noise.

[0051]

[0052] Meanwhile, the meta silencer (100) according to a preferred embodiment of the present invention has a first form (as shown in (a) of Fig. 5) in which the first slit unit (240) and the second slit unit (250) are formed in an asymmetrical shape so as to absorb low-frequency noise in a wide band. ) can have.

[0053] That is, the plurality of first slits (241) forming the first slit unit (240) and the plurality of second slits (251) forming the second slit unit (250) can be configured to have different lengths.

[0054] Then, the plurality of first slits (241) all have different lengths at different locations, the plurality of second slits (251) also have different lengths at different locations, and the plurality of first slits (241) and the plurality of second slits (251) can also have different lengths.

[0055] Accordingly, since the lengths of the first individual sound-absorbing space (242) and the second individual sound-absorbing space (252) are all divided differently according to location, a rainbow trapping effect occurs, thereby absorbing and reducing broadband low-frequency noise.

[0056] This can be confirmed through the acoustic transmission loss evaluation results (calculation results through theory (solid line) in Fig. 5 (b), simulation results through finite element analysis (dotted line) and experimental results (circular line) in Fig. 5 (c), acoustic pressure field results through finite element analysis in Fig. 5 (c), reflection rate calculation results according to frequency in Fig. 6 (a), and group velocity calculation results at the end of the slit in Fig. 6 (b).

[0057] That is, according to (b) and (c) of Fig. 5, the first form ( ) in the case of plane mode, ~ The multi-slit localized mode of It can be divided into three modes including the single-slit localized mode.

[0058] And according to (a) of Fig. 6 You can see that the reflectance dip appears in ~ You can see that the reflectance decreases as the reflectance dip appears in . It can be seen that multiple reflectance peaks and dips appear in .

[0059] In addition, according to a comparison of (b) of Fig. 5 and (a) of Fig. 6, it can be confirmed that the frequency at which the reflectivity dip appears and the peak point of the acoustic transmission loss coincide.

[0060] And, a broadband blocking effect on low-frequency noise can be confirmed by the occurrence of multiple reflectivity peaks and dips in the frequency band corresponding to the single-slit localized mode due to the rainbow capture effect.

[0061] In addition, according to (b) of Fig. 6, it can be confirmed that the group velocity becomes 0 in the frequency band where the single-slit localized mode begins to occur.

[0062]

[0063] Here, the meta silencer (100) according to a preferred embodiment of the present invention has a second form as shown in (a) of Fig. 7, in which at least one first bend (243) and a second bend (253) are formed at the ends of the first slit (241) and the second slit (251) so that the lengths of the first individual sound-absorbing space (242) and the second individual sound-absorbing space (252) can be further extended. ) can have.

[0064] That is, the first individual sound-absorbing space (242) can be divided into a first a individual sound-absorbing space (242a) and a first b individual sound-absorbing space (242b) that are sequentially connected by the first bend (243) with the end of the first slit (241) as the boundary, and the second individual sound-absorbing space (252) can be divided into a second a individual sound-absorbing space (252a) and a second b individual sound-absorbing space (252b) that are sequentially connected by the second bend (253) with the end of the second slit (251) as the boundary.

[0065] Then, as the first individual sound-absorbing space (242) is divided into the first individual sound-absorbing space (242a) and the first individual sound-absorbing space (242b) that are sequentially connected, its length is further extended, and as the second individual sound-absorbing space (252) is also divided into the second individual sound-absorbing space (252a) and the second individual sound-absorbing space (252b) that are sequentially connected, its length is further extended, thereby expanding the rainbow trapping effect and enabling the broadband low-frequency noise to be absorbed and reduced more effectively.

[0066] This is the acoustic transmission loss evaluation result of Fig. 7 (b) (the result calculated through theory (solid line), the simulation result through finite element analysis (dotted line), the result through experiment (circle line), the acoustic pressure field result through finite element analysis of Fig. 7 (c), and the results of (a) and (b) of Fig. 8). ~ This can be confirmed through the results of group velocity calculation at the first slit unit ((240, Top) and the second slit unit (250, Bottom).

[0067] That is, according to (b) and (c) of Fig. 7, in the case of the second form plane mode, The multi-slit localized mode of ~ It can be classified into three modes including the single-slit localized mode.

[0068] and In , the first cutoff band occurs at 264 Hz, In , the cutoff band occurs at 600 Hz, ~ It can be seen that a wide cutoff band occurs from 728 Hz to the cutoff frequency.

[0069] Also, according to Fig. 9, the first slit unit (240, Top) has 728 Hz ( ), 1280㎐ in the second slit unit (250, Bottom) ) can be confirmed that the group velocity becomes 0.

[0070] That is, it can be confirmed that the rainbow capture effect occurs in the first slit unit (240, Top) from 728 Hz and in both the first slit unit (240, Top) and the second slit unit (250, Bottom) from 1280 Hz.

[0071]

[0072] The above-described embodiments are merely exemplary, and those skilled in the art may devise other embodiments with various modifications therefrom.

[0073] Therefore, the true technical protection scope of the present invention should include not only the above-described embodiments but also other embodiments modified in various ways by the technical idea of ​​the invention described in the following patent claims.

[0074] The present invention relates to a meta silencer that can effectively reduce noise generated through pipes from various engines, machines, and devices in automobiles, ships, aircraft, factories, etc.

Claims

1. It is installed on the pipe through which noise passes. A meta silencer characterized in that it is composed of a unit resonator in which a communication hole is perforated on the lower surface of the front end to communicate with the inside of the pipe, a cavity is provided on the rear end, and a first slit unit and a second slit unit are installed facing each other with a space therebetween on the inner left and right surfaces between the communication hole and the cavity.

2. In paragraph 1, The above first slit unit It is composed of a plurality of first slits spaced apart from each other so that a first individual sound-absorbing space is provided between them and the length thereof gradually increases from the above-mentioned communication hole to the above-mentioned cavity, The above second slit unit A meta silencer characterized by comprising a plurality of second slits spaced apart from each other so as to provide a second individual sound-absorbing space and having a length that gradually increases from the communication hole to the cavity.

3. In paragraph 2, The above first slit and the above first slit have different lengths The above first slit unit and the above second slit unit A meta silencer characterized in that it is formed asymmetrically according to the different lengths of the first slit and the second slit.

4. In paragraph 2, The above first slit At least one first bend is formed at an end to extend the length of the first individual sound-absorbing space, The above second slit A meta silencer characterized in that at least one second bend is formed at an end to extend the length of the second individual sound-absorbing space.

5. In paragraph 1, The above unit resonator A meta silencer characterized in that it is composed of a plurality of pieces and is responsible for a certain length of the above pipe, and is installed so as to be connected to each other while forming a shape corresponding to the cross-sectional shape of the above pipe along the circumference of the above pipe.

6. In paragraph 1, The above unit resonator A meta silencer characterized in that it is composed of a plurality of pieces and is responsible for a certain length of the pipe, is installed in a shape corresponding to the cross-sectional shape of the pipe around the pipe, and is installed in multiple stages along the length of the pipe.

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