Noise reduction device and power equipment

Abstract

The embodiment of the invention relates to a noise reduction device and power equipment. The noise reduction device comprises an air duct structure and a first expansion chamber. The air duct structure includes an air duct wall defining an air duct including an inlet and an outlet. The air duct wall comprises a first wall, and a first hole is formed in a first area of the first wall. The first expansion chamber is adjacent to the first wall of the air duct structure and comprises a first expansion chamber wall, the first expansion chamber wall and the first wall define a first space, and the first space communicates with the air duct through the first hole. The first aperture is configured such that acoustic impedance within the duct increases at the first region by an amount exceeding a first threshold to prevent acoustic waves of a first frequency band entering the duct through the inlet from passing through the outlet. Through the technical scheme of the embodiment of the invention, the noise emitted by the noise source can be effectively reduced, and the noise pollution of the environment is reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of mufflers, and more particularly, to a noise reduction device and an electrical device. Background Art

[0002] DC charging piles are currently widely used to charge electric vehicles. At present, the mainstream DC charging piles on the market mainly adopt a direct ventilation structure to dissipate heat from the DC charging piles. In this heat dissipation method, the noise source (such as a cooling fan) directly faces the air inlet duct, and the noise can be directly transmitted to the outside of the device. To reduce noise, a shielding cover is usually set up. In this solution, a shielding cover provided with sound-absorbing material is coupled to the cabinet body in this way to absorb the noise emitted by the noise source. However, the effect of this noise reduction solution is not obvious, and there are potential safety hazards. Summary of the Invention

[0003] Embodiments of the present disclosure provide a noise reduction device and an electrical device to at least solve the above and other potential problems of the prior art.

[0004] According to one aspect of the present disclosure, a noise reduction device is provided. The noise reduction device includes: a duct structure and a first expansion chamber. The duct structure includes: a duct wall that defines a duct, and the duct includes an inlet and an outlet; wherein, the duct wall includes a first wall, and a first hole is provided in a first region of the first wall; the first expansion chamber is disposed adjacent to the first wall of the duct structure, the first expansion chamber includes a first expansion chamber wall, and the first expansion chamber wall and the first wall define a first space, and the first space communicates with the duct through the first hole; wherein, the first hole is configured to increase the acoustic impedance in the duct at the first region, and the increased amount exceeds a first threshold, so as to prevent the sound wave of the first frequency band entering the duct through the inlet from passing through the outlet.

[0005] In the above embodiment, by providing a hole in the first region of the side wall of the duct structure, the cross-sectional area of the duct at the hole in the first region becomes larger, resulting in a sudden change in acoustic impedance here, so that the sound wave of the first frequency band entering the duct through the inlet can be reflected back to the noise source, that is, to prevent the noise from passing through the duct and being transmitted out through the outlet. In this way, the noise of a predetermined frequency band of the noise source can be effectively prevented from spreading outwards, thereby reducing the noise pollution of the environment.

[0006] In some embodiments, the first wall is uniformly provided with a plurality of first holes in a first array form.

[0007] In the above embodiment, by uniformly providing a plurality of first holes in a first array form on the first wall, the acoustic impedance at the first region can be effectively increased, and the resistance to the air flow in the duct can be avoided from being unfavorably increased.

[0008] In some embodiments, the opening ratio of a plurality of first holes at a first region of the first wall is above 30%, where the opening ratio represents the ratio of the opening area of the plurality of first holes to the area of the first region.

[0009] In the above embodiments, by setting the opening ratio at the first region to be above 30%, it is possible to ensure that the acoustic impedance of the air duct increases at the first region to a level sufficient to reflect the noise entering the channel.

[0010] In some embodiments, the air duct wall further includes a second wall adjacent to the first wall. A second hole is provided in a second region of the second wall. The noise reduction device further includes: a second expansion chamber disposed adjacent to the second wall. The second expansion chamber includes a second expansion chamber wall, and the second expansion chamber wall and the second wall define a second space. The second space communicates with the air duct through the second hole. Wherein, the second hole is configured such that the acoustic impedance of the air duct increases at the second region, and the increased amount exceeds a second threshold, thereby preventing the sound waves in a second frequency band entering the air duct through the inlet from passing through the outlet.

[0011] In the above embodiments, by providing a second expansion chamber beside the channel, it is possible to further reduce the noise from the noise source. For example, the noise in the second frequency band from the noise source can be eliminated or attenuated.

[0012] In some embodiments, the second wall is uniformly provided with a plurality of second holes in a second array form.

[0013] In the above embodiments, by uniformly providing a plurality of second holes in a second array form on the second wall, it is possible to effectively increase the air resistance at the second region and avoid unfavorably increasing the resistance of the air flow in the air duct.

[0014] In some embodiments, the air duct wall further includes a third wall. The noise reduction device further includes: a resistive noise reduction part disposed adjacent to the third wall. The resistive noise reduction part includes a resistive noise reduction wall, and the resistive noise reduction wall and the third wall define a third space. An acoustic absorption material is provided in the third space so that the sound waves in a third frequency band entering the air duct through the inlet are attenuated.

[0015] In the above embodiments, by providing a resistive noise reduction part beside the air duct, it will be possible to effectively absorb the noise in a relatively wide frequency band range entering the air duct.

[0016] In some embodiments, the air duct wall further includes a fourth wall. The fourth wall is provided with a plurality of third holes. The noise reduction device further includes: a resonance cavity structure disposed adjacent to the fourth wall. The resonance cavity structure includes a resonance cavity wall, and the resonance cavity wall and the fourth wall define a resonance cavity. Wherein, each of the plurality of third holes is configured to form a sound vibration system with the resonance cavity respectively, so that the sound waves in a fourth frequency band entering the air duct through the inlet are attenuated by forming resonance with the sound vibration system.

[0017] In the above embodiments, by arranging a resonance cavity structure beside the air duct, the noise entering the air duct can be effectively attenuated or eliminated through the resonance system.

[0018] In some embodiments, the resonance cavity has one of the following shapes: a cuboid, a cylinder, or a sphere.

[0019] In the above embodiments, by setting the resonance cavity in the above shapes, it is convenient for manufacturing and helps to form a resonance system to attenuate or eliminate the noise in a predetermined frequency band.

[0020] In some embodiments, a plurality of third holes are uniformly arranged on the fourth wall in a third array form, and the distribution density of the plurality of third holes is respectively less than the distribution density of the plurality of first holes and the plurality of second holes.

[0021] In the above embodiments, by making the distribution mode of the third holes different from that of the first holes and the second holes, the resonance cavity can attenuate the noise in different frequency bands in a manner different from that of the first expansion chamber and the second expansion chamber.

[0022] In some embodiments, the air duct structure includes a plurality of bending parts, and the first wall, the second wall, the third wall, and the fourth wall are respectively located at different bending parts of the bending structure.

[0023] In the above embodiments, by setting the air duct structure to include a plurality of bending parts, and the first wall, the second wall, the third wall, and the fourth wall are respectively located at different bending parts of the bending structure, the length of the air duct can be extended, and the sound will gradually weaken as the propagation distance becomes farther. In this way, it helps to attenuate the noise and helps to implement a combination of multiple noise reduction methods to attenuate or eliminate most of the noise.

[0024] In some embodiments, the first expansion chamber, the second expansion chamber, the resistive noise reduction part, and the resonance cavity structure are arranged in series on one side of the air duct structure to form a first noise reduction structure.

[0025] In the above embodiments, by arranging the first expansion chamber, the second expansion chamber, the resistive noise reduction part, and the resonance cavity structure in series on one side of the air duct structure, a composite noise reduction treatment can be performed on the noise entering the air duct, so that the noise in multiple frequency bands can be effectively attenuated.

[0026] In some embodiments, the air duct structure and the first noise reduction structure arranged adjacent to one side or both sides of the air duct structure together form a noise reduction unit; and the noise reduction device includes a plurality of noise reduction units arranged side by side.

[0027] In the above embodiments, by including a plurality of noise reduction units arranged side by side in the noise reduction device, effective noise reduction treatment can be implemented while ensuring ventilation for the device to be noise-reduced.

[0028] In some embodiments, the first space of the first expansion chamber, the second space of the second expansion chamber, and the resonance cavity of the first noise reduction unit among the plurality of noise reduction units are respectively spaced apart from the first space of the first expansion chamber, the second space of the second expansion chamber, and the resonance cavity of the adjacent second noise reduction unit among the plurality of noise reduction units.

[0029] In the above embodiment, in the case where a plurality of noise reduction units are arranged side by side in the noise reduction device, by respectively spacing apart the first space of the first expansion chamber, the second space of the second expansion chamber, and the resonance cavity of the first noise reduction unit from the first space of the first expansion chamber, the second space of the second expansion chamber, and the resonance cavity of the adjacent second noise reduction unit among the plurality of noise reduction units instead of two noise reduction units sharing the above respective spaces, the noise reduction performance of each part of the structure can be improved.

[0030] In some embodiments, the resistive noise reduction part is arranged adjacent to the outlet of the air duct, the resonance cavity structure is arranged adjacent to the inlet of the air duct, and the first expansion chamber and the second expansion chamber are arranged between the resistive noise reduction part and the resonance cavity structure.

[0031] In the above embodiment, by arranging each noise reduction structure in a predetermined order, it is possible to fully utilize the noise reduction characteristics of each noise reduction structure according to the characteristics of the noise frequency bands contained in the noise and obtain the best noise reduction effect.

[0032] According to another aspect of the embodiments of the present disclosure, there is provided an electrical device, which includes: a main body, in which a noise source is provided in the housing of the main body; and the noise reduction device according to the first aspect, the noise reduction device is coupled to the housing to perform noise reduction processing on the noise from the noise source.

[0033] It will be understood through the following description that the solution implemented by the present disclosure can effectively reduce the noise emitted by the noise source and reduce the noise pollution of the environment.

[0034] The Summary of the Invention is provided to introduce a selection of concepts in a simplified form, which will be further described in the Detailed Description below. The Summary of the Invention is not intended to identify the key features or main features of the present disclosure, nor is it intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A three-dimensional schematic diagram of a noise reduction device according to some exemplary embodiments of the present disclosure is shown;

[0036] Figure 2 A three-dimensional cross-sectional view of a noise reduction device according to some exemplary embodiments of the present disclosure is shown;

[0037] Figure 3 A three-dimensional cross-sectional view of a noise reduction device according to some exemplary embodiments of the present disclosure is shown;

[0038] Figure 4 shows a cross-sectional schematic view of the noise reduction device as Figure 3 shown;

[0039] Figure 5 shows a cross-sectional schematic view of another perspective of the noise reduction device as Figure 3 shown;

[0040] Figure 6 shows a cross-sectional schematic view of the first expansion chamber and the second expansion chamber of the noise reduction device according to some exemplary embodiments of the present disclosure;

[0041] Figure 7 shows a partial cross-sectional view of the noise reduction device according to some exemplary embodiments of the present disclosure;

[0042] Figure 8 shows a partial three-dimensional cross-sectional view of the first and second expansion chambers of the noise reduction device according to some exemplary embodiments of the present disclosure;

[0043] Figure 9 shows a partial cross-sectional schematic view of the resistive noise reduction part of the noise reduction device according to some exemplary embodiments of the present disclosure;

[0044] Figure 10 shows a partial three-dimensional cross-sectional view of the resistive noise reduction part of the noise reduction device according to some exemplary embodiments of the present disclosure;

[0045] Figure 11 shows a partial cross-sectional view of the resonance cavity structure of the noise reduction device according to some exemplary embodiments of the present disclosure;

[0046] Figure 12 shows a partial cross-sectional view of the air duct structure and the resonance cavity structure of the noise reduction device according to some exemplary embodiments of the present disclosure;

[0047] Figure 13 shows a schematic view of the resonance system formed by the resonance cavity and the holes according to some exemplary embodiments of the present disclosure;

[0048] Figure 14 shows a schematic view of the muffler cover including the noise reduction device according to some exemplary embodiments of the present disclosure;

[0049] Figure 15 shows a three-dimensional schematic view of the power equipment provided with the noise reduction device according to some exemplary embodiments of the present disclosure;

[0050] Figure 16 shows as Figure 15 shown in the front view of the power equipment;

[0051] Figure 17 shows the right view of the power equipment as Figure 15 shown; and

[0052] Figure 18 shows the left view of the power equipment as Figure 15 shown.

[0053] In each of the drawings, the same or corresponding reference numerals denote the same or corresponding parts. Detailed Embodiments

[0054] The principles of the present disclosure will be described below with reference to various exemplary embodiments shown in the accompanying drawings. It should be understood that the description of these embodiments is only for enabling those skilled in the art to better understand and further implement the present disclosure, and is not intended to limit the scope of the present disclosure in any way. It should be noted that where feasible, similar or identical reference numerals may be used in the figures, and similar or identical reference numerals may represent similar or identical functions. Those skilled in the art will readily recognize that alternative embodiments of the structures and methods described herein may be employed without departing from the principles of the invention described herein.

[0055] As used herein, the term "comprising" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise specified, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "an exemplary embodiment" and "an embodiment" mean "at least one exemplary embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects.

[0056] Currently, the main source of noise generated by DC charging piles is the fan used for air cooling inside the DC charging pile. For example, the airflow during the heat dissipation of the charging module to be cooled by the fan will generate noise.

[0057] As mentioned above, in order to reduce noise, a shielding cover provided with sound-absorbing materials such as sound-absorbing cotton is usually used in the market to reduce noise. By coupling the shielding cover to the cabinet body, the sound-absorbing cotton is attached to the side of the cabinet door panel, thereby preventing the noise from spreading to the environment through the shielding cover. This solution has the advantages of being simple and easy to manufacture, cheap and practical, and having relatively low requirements for designers and production units. However, the noise reduction effect of this noise reduction solution is not obvious, and there are potential safety hazards. For example, the sound-absorbing cotton is exposed to the outside, having disadvantages such as short lifespan and short replacement cycle; in terms of the material of the sound-absorbing cotton, rock wool and low-density polyurethane are mostly used, and their flame retardancy and noise reduction effects are poor, which affects the use safety of the charging pile. In addition to the above problems, some solutions also have problems such as unreasonable design structures of the shielding cover.

[0058] Embodiments of the present disclosure provide an improved noise reduction device. The noise reduction device includes a duct structure and a first expansion chamber. The duct structure includes a duct wall that defines a duct having an inlet and an outlet. The duct wall includes a first wall, and a first hole is provided in a first region of the first wall. The first expansion chamber is disposed adjacent to the first wall of the duct structure. The first expansion chamber includes a first expansion chamber wall, and the first expansion chamber wall and the first wall define a first space that communicates with the duct through the first hole. The first space may be an approximately closed space with only a small hole as an opening, or a space that also has an opening in other walls in addition to the small hole. The first hole is appropriately provided such that the acoustic impedance in the duct increases at the first region by an amount exceeding a first threshold to prevent sound waves in a first frequency band entering the duct through the inlet from passing through the outlet.

[0059] The noise reduction device according to the embodiments of the present disclosure is provided with a hole at a first region of the first wall of the duct structure, so that the cross-sectional area of the duct becomes larger at the first region, thereby causing a sudden change in the acoustic impedance of the duct at the first region, and thus being able to reflect sound waves in a first frequency band entering the duct through the inlet back to the noise source, that is, preventing noise from passing through the duct and exiting through the outlet. In this way, it is possible to effectively prevent the noise of a predetermined frequency band of the noise source from spreading outward, thereby reducing the noise pollution of the environment.

[0060] Embodiments of the present disclosure will be specifically described below with reference to the accompanying drawings. Figure 1 A perspective schematic view of a noise reduction device 100 according to some exemplary embodiments of the present disclosure is shown. As Figure 1 shown, the noise reduction device 100 is generally in the shape of a cuboid. A duct and a noise reduction structure are provided inside the housing 101 of the noise reduction device 100, which will be specifically described later. A plurality of rows of air inlets 107 are provided on one side surface of the housing 101, and the air inlets 107 correspond to the inlet of the duct provided inside the housing 101. This side surface is adapted to face the noise source to receive noise from the noise source. An air outlet ( Figure 1 not visible in the figure) is provided on another side surface of the housing 101. The noise reduction device 100 is particularly suitable for being applied to a device that dissipates heat from a heat-generating device by air cooling.

[0061] Figure 2 A perspective cross-sectional view of a noise reduction device 100 according to some exemplary embodiments of the present disclosure is shown. As Figure 2 shown, the noise reduction device 100 includes a resonance cavity structure 110, a first expansion chamber 120, a second expansion chamber 130, and a resistive noise reduction part 140. Figure 2 Only the structure inside the noise reduction device 100 as seen from an obliquely upper view is schematically shown, and will be further described below in conjunction with the accompanying Figure 3 drawings.

[0062] Figure 3A perspective cross-sectional view of a noise reduction device 100 according to some exemplary embodiments of the present disclosure is shown. A plurality of air ducts 103 may be provided in the noise reduction device 100 (as Figure 3 indicated by the thick black arrows in). Figure 3 Two air ducts 103 are shown. The air ducts 103 are generally in a bent structure. It should be understood that the embodiments of the present disclosure are not limited thereto, and the air ducts 103 may also adopt various other structures, such as an S-shaped structure, a straight-line structure, and so on.

[0063] In some embodiments, as Figure 3 shown, a resonance cavity structure 110 is provided on the inlet 106 side of the noise reduction device 100. The resonance cavity structure 110 is adjacent to one wall of the air duct 103. A first expansion chamber 120 and a second expansion chamber 130 are sequentially provided on the left side of the resonance cavity structure 110. On the left side of the second expansion chamber 130, that is, near the outlet 108 side of the air duct 103, a resistive noise reduction part 140 is provided. A sound-absorbing material 146, such as sound-absorbing cotton, etc., is provided in the resistive noise reduction part 140. Figure 3 A plurality of air outlets 109 are provided on the left side of the noise reduction device 100 shown in.

[0064] Next, in conjunction with Figure 4 and Figure 5 the internal structure of the noise reduction device 100 of the embodiments of the present disclosure will be further described.

[0065] Figure 4 A cross-sectional schematic view of the noise reduction device 100 as Figure 3 shown is shown, in which a schematic diagram of the internal structure of the noise reduction device 100 is shown; Figure 5 A cross-sectional schematic view of another perspective of the noise reduction device 100 as Figure 3 shown is shown. As Figure 4 and Figure 5 shown, the noise reduction device 100 includes an air duct structure 102, and a first expansion chamber 120, a second expansion chamber 130, and a resonance cavity structure 110 located on both sides of the air duct structure 102.

[0066] The air duct structure 102 includes an air duct wall that defines the air duct 103. The air duct 103 includes an inlet 106 and an outlet 108 for air flow to pass through. The air duct wall includes a side wall, a top wall, and a bottom wall that define the air duct 103. The air duct wall may include a first wall 122. A first hole 124 is provided in a first region ( Figure 4 a region approximately in the middle of the first wall 122 in, Figure 7 labeled 125 in) of the first wall 122. The number of the first holes 124 may be one or more. Specifically, for example, the first hole 124 may be a larger hole or multiple smaller holes. The shape of the hole is not limited herein.

[0067] Reference Figure 7 , in which it is shown that the first region 125 is approximately located at the middle position of the first wall 122. Embodiments of the present disclosure are not limited thereto. For example, if the length of the first expansion chamber 120 in the air duct direction is L, the first region 125 may be located within the range of L / 2 to 3L / 4 from the inlet of the first expansion chamber 120 to the first wall 122. In this way, the frequency range of noise elimination can be expanded, and generally, the noise corresponding to odd and even multiples of λ / 2 (λ is the predetermined noise elimination wavelength) can be eliminated. In addition, preferably, the first region 125 extends in the vertical direction and substantially covers the vertical height of the first wall 122.

[0068] Refer again to Figure 4 , the first expansion chamber 120 is adjacent to the first wall 122 of the air duct structure 102, and the first expansion chamber 120 includes a first expansion chamber wall. The first expansion chamber wall may include side walls, a chamber top, and a chamber bottom. The first expansion chamber wall and the first wall 122 together define a first space, and the first space communicates with the air duct 103 through a first hole 124. In other words, the first expansion chamber 120 may have a common first wall 122 with the air duct structure 102, and the first wall 122 separates the air duct 103 from the first space (cavity) inside the first expansion chamber 120. The first space may be an approximately enclosed space, and this space communicates with the air duct 103 only through a small hole. The first hole 124 is configured such that the acoustic impedance in the air duct 103 increases at the first region 125, and the increased amount exceeds a first threshold to prevent the sound waves in the first frequency band entering the air duct 103 through the inlet 106 from passing through the outlet 108. For example, when there are multiple first holes 124 provided on the first wall 122, the size of each hole and the distance between each hole are set such that the acoustic impedance of the air duct 103 changes abruptly at the position where each hole is located. Specifically, the size of the hole and the hole spacing can be determined according to the frequency band of the preset noise reduction sound wave and the set size of the first expansion chamber 120.

[0069] Sound often contains sound waves of different frequencies. In a pipeline structure, only sound waves of certain frequencies can pass through, and the rest will be reflected, attenuated, or dissipated in the chamber structure, thus achieving the "filtering" function of sound waves. When sound waves pass through small tubes and small chambers one by one, they are gradually weakened.

[0070] In some embodiments of the present disclosure, the main principle of using the first expansion chamber 120 for noise elimination is: using the cross-section mutation of the air duct 103 to cause a change in acoustic impedance, so that a part of the sound waves propagating along the air duct 103 are reflected back to the sound source. In addition, the sound waves propagating in the air duct 103 can also be attenuated by reflection and interference. In this way, the purpose of noise elimination can be achieved.

[0071] In some embodiments, the first wall 122 is uniformly provided with a plurality of first holes 124 in a first array form. AsFigure 4 , Figure 6 and Figure 7 As shown in Figure 4 , Figure 6 and Figure 7 , multiple rows and columns of first holes 124 are provided on the first wall 122. The porosity of these first holes 124 at the first region 125 of the first wall 122 can be 30% or more, where the porosity represents the ratio of the opening area of the multiple first holes 124 to the area of the first region 125. Specifically, at the first region 125, each of the first holes 124 is dense and uniform. In this way, it can be approximately regarded that the first region 125 is a region where the first wall 122 (for example, a metal plate) does not exist, but directly communicates with the cavity (the first space) beside the air duct 103. The cross-sectional area of the air duct 103 in this section can be approximately equivalent to the sum of the cross-sectional area of the air duct 103 and the cross-sectional area of the first space communicated by the first holes 124. Thus, when noise passes through the cross-sectional mutation region, due to the sudden change in acoustic impedance, it cannot pass through the region with a large acoustic impedance, and thus is reflected back in the direction of the sound source. Therefore, the noise cannot pass through the air duct 103 and spread out. At this time, the dense first holes 124 can improve the loss of aerodynamic performance caused by the cross-sectional mutation. That is to say, compared with the scheme in which the first holes 124 are sparsely distributed on the first wall 122, the resistance to the airflow can be reduced, which is helpful for ventilation.

[0072] In some embodiments, the air duct wall further includes a second wall 132. As Figure 4 shown, the second wall 132 is adjacent to the first wall 122. Second holes 134 are provided in the second region ( Figure 7 marked as 127 in Figure 7 ) of the second wall 132. The noise reduction device 100 may further include a second expansion chamber 130, and the second expansion chamber 130 is disposed adjacent to the second wall 132. In addition, the second expansion chamber 130 is also adjacent to the first expansion chamber 120, and a plate 131 is located between the two. The second expansion chamber 130 includes a second expansion chamber wall. Similar to the first expansion chamber 120, the second expansion chamber wall may include the side walls of the second expansion chamber 130, as well as the chamber top and chamber bottom. The second expansion chamber wall and the second wall 132 may define a second space, and the second space communicates with the air duct 103 through the second holes 134. The second space may also be an approximately enclosed space, and this space communicates with the air duct 103 only through small holes as openings. The second holes 134 are configured such that the acoustic impedance of the air duct 103 increases at the second region 127, and the increased amount exceeds the second threshold, so as to prevent the second-frequency sound waves entering the air duct 103 through the inlet 106 from passing through the second expansion chamber 130 and spreading out from the outlet 108.

[0073] In some embodiments, the second wall 132 is uniformly provided with a plurality of second holes 134 in a second array form. Similar to the first holes 124, the porosity of the second holes 134 at the second region 127 of the second wall 132 can also be 30% or more.

[0074] The following further refers toFigures 6 to 8 Describe the first expansion chamber 120 and the second expansion chamber 130. Figure 6 FIG. 2 shows a cross-sectional schematic view of the first expansion chamber 120 and the second expansion chamber 130 of the noise reduction device 100 according to some exemplary embodiments of the present disclosure; Figure 7 FIG. 3 shows a partial cross-sectional view of a noise reduction device according to some exemplary embodiments of the present disclosure; Figure 8 FIG. 4 shows a partial perspective cross-sectional view of the first expansion chamber 120 and the second expansion chamber 130 of the noise reduction device 100 according to some exemplary embodiments of the present disclosure.

[0075] As Figure 6 shown, the first expansion chamber 120 and the second expansion chamber 130 are arranged adjacent to each other end to end along the direction of the air duct 103. One first expansion chamber 120 and one second expansion chamber 130 are respectively arranged on both sides of the air duct 103. Thus, noise entering the air duct can be reduced on both sides of the air duct 103. The first holes 124 on the first wall 122 and the second holes 134 on the second wall 132 are arranged in a rectangular array of multiple rows and multiple columns.

[0076] As Figure 7 shown, which shows the first holes 124 in the first region 125 and the second holes 124 in the second region 127. The first holes 124 and the second holes 124 shown in the figure are circular. Embodiments of the present disclosure are not limited thereto, but may be other shapes, such as ellipses, rectangles, and the like. In addition, the arrangement manner of the first holes 124 and the second holes 124 is not limited to the form shown in the figure, but may vary according to actual situations.

[0077] As Figure 8 shown, two first expansion chambers 120 are arranged adjacent to each other and are separated by a partition 121. Each of the two first expansion chambers 120 has one side adjacent to the corresponding side wall of the air duct 103 (the air duct 103 is located on the upper side and the lower side of the V-shaped structure in the figure, which is not shown in the figure). By separating the two first expansion chambers 120 with the partition 121, a better noise reduction effect can be obtained compared with the scheme of combining the two first expansion chambers 120 together.

[0078] As can be seen from the above description, in the embodiments of the present disclosure, the expansion chamber mainly utilizes the sudden change of the duct cross-section to cause a sudden change in the acoustic impedance in the channel 103, so that some frequency bands of sound waves propagating along the air duct 103 cannot pass through the expansion chamber and are reflected back to the sound source direction, so that the noise sound waves cannot pass through the expansion chamber part and thus cannot be transmitted outside the noise reduction device 100, thereby achieving the purpose of noise elimination. The noise elimination performance of the expansion chamber is related to its structure and is generally applicable to the control of narrowband noise and low and medium frequency noise. The noise reduction device 100 of the present disclosure is provided with a first expansion chamber 120 and a second expansion chamber 130, which have a good noise elimination effect on two specific frequency bands of noise. The noise elimination range of some expansion chambers in the embodiments of the present disclosure is usually in the medium and low frequency range. For example, it is in the range of 250 - 1000 hz.

[0079] In some embodiments, the air duct wall further includes a third wall 142 (see Figure 10 ). The third wall 142 can be adjacent to the second wall 132. The noise reduction device 100 can further include a resistive noise reduction part 140. The resistive noise reduction part 140 is arranged adjacent to the third wall 142. The resistive noise reduction part 140 will be further described below in conjunction with Figure 9 and Figure 10 .

[0080] Figure 9 FIG. shows a partial cross-sectional view of the resistive noise reduction part 140 of the noise reduction device 100 according to some exemplary embodiments of the present disclosure; Figure 10 FIG. shows a partial perspective cross-sectional view of the resistive noise reduction part 140 of the noise reduction device 100 according to some exemplary embodiments of the present disclosure.

[0081] As Figure 9 shown, the resistive noise reduction part 140 is located on both sides of the air duct 103. The resistive noise reduction part 140 includes a resistive noise reduction wall, and the resistive noise reduction wall can include side walls as well as a top and a bottom. The resistive noise reduction wall and the third wall 142 define a third space. The third space is preferably a closed space. As Figure 9 and 10 shown, a sound-absorbing material 146 with a certain thickness, such as sound-absorbing cotton, is arranged in the third space to attenuate the sound waves of the third frequency band entering the air duct 103 through the inlet 106. The sound-absorbing cotton can fill the space as Figure 9 and Figure 10 shown, or it can not fill the space when only covering the surface of the third wall 142. In some embodiments, the material of the sound-absorbing cotton can be high-density polyurethane, which has the advantages of a wide sound absorption frequency range and good flame retardant properties and is a preferred material for sound insulation materials.

[0082] The resistive noise reduction part 140 can utilize the sound absorption effect of the sound-absorbing material to continuously absorb and gradually attenuate the noise propagating along the air duct 103. When the sound wave passes through the micropores on the sound-absorbing cotton, the air inside the micropores vibrates and thus frictions with the pore walls, causing a considerable part of the sound energy to be converted into heat energy and consumed, playing a sound-absorbing role. The principle of resistive noise reduction is mainly to utilize the sound wave propagating in the porous sound-absorbing material or sound-absorbing structure, and convert the sound energy into heat energy and dissipate it due to friction, so that the noise propagating along the pipeline attenuates with the distance, thereby achieving the purpose of noise elimination. Install the sound-absorbing material or sound-absorbing structure on the inner wall or the channel space to absorb the sound wave energy. This solution has a small pressure drop on the air flow and has a good noise elimination effect on medium-frequency and high-frequency sound waves. The sound-absorbing material can adopt a soft, porous and breathable fabric, such as sound-absorbing cotton, fiberglass cloth, or perforated plate, etc. The resistive noise reduction method can effectively reduce the medium-high frequency noise to achieve the purpose of reducing the noise of the air duct 103. Generally speaking, the resistive noise reduction part 140 is especially effective for medium-frequency noise, for example, noise above 1000 Hz to 2500 Hz.

[0083] In some embodiments, the diameter of the second hole 134 can be, for example, an aperture of 3 - 10 mm. The embodiments of the present disclosure are not limited thereto, but other sizes of holes can be adopted according to actual needs.

[0084] Refer again to Figure 4 , in some embodiments, the air duct wall may further include a fourth wall 112. The fourth wall 112 can be adjacent to any one of the first wall 122, the second wall 132, and the third wall 142. In Figure 4 the illustrated embodiment, the fourth wall 112 is adjacent to the first wall 122. The fourth wall 112 may be provided with a plurality of third holes 114. The third holes 114 can be uniformly arranged on the fourth wall 112 in a third array form. The distribution density of the plurality of third holes 114 can be respectively less than the distribution densities of the plurality of first holes 124 and the plurality of second holes 134. As Figure 4 shown, two columns of third holes 114 are provided on the fourth wall 112. The embodiments of the present disclosure are not limited thereto, but other forms of third holes 114 can be set according to needs. In some embodiments, the center-to-center distance between each of the third holes 114 is more than 5 times the diameter of the third hole 114, thereby ensuring that the sound radiation of each hole does not interfere with each other. The noise reduction device 100 may further include a resonance cavity structure 110, and the resonance cavity structure 110 is arranged adjacent to the fourth wall 112. In addition, the position of the third hole 114 is preferably set near the middle position of the resonance cavity structure 110 along the air duct direction. The following refers to Figures 11 to 13 to further describe the embodiments of the present disclosure.

[0085] Figure 11 shows a partial cross-sectional view of the resonance cavity structure of the noise reduction device according to some exemplary embodiments of the present disclosure; Figure 12Shows a partial cross-sectional view of the air duct structure 102 and the resonance cavity structure 110 of the noise reduction device 100 according to some exemplary embodiments of the present disclosure;

[0086] Figure 13 Shows a schematic diagram of a resonance system formed by a resonance cavity and holes according to some exemplary embodiments of the present disclosure.

[0087] In some embodiments, small holes with a specific diameter are provided at specific positions on the side walls on one or both sides of the air duct 103 so as to form a resonance cavity structure 110 with the cavity beside the air duct. As Figure 11 and 12 shown, the resonance cavity structure 110 is disposed adjacent to the fourth wall 112. The resonance cavity structure 110 may include a resonance cavity wall, and the resonance cavity wall may include side walls, a cavity top, and a cavity bottom. The resonance cavity wall and the fourth wall 112 define a resonance cavity 116. The resonance cavity 116 is preferably a closed space with only the small holes as openings. Each of the plurality of third holes 114 is configured to form a sound vibration system with the resonance cavity 116 respectively, so that the sound waves in the fourth frequency band entering the air duct 103 through the air duct inlet 106 are attenuated by forming resonance with the sound vibration system.

[0088] The resonance cavity structure 110 may be disposed on the side of the air duct inlet 106. In some embodiments, the resonance cavities 116 between two adjacent air ducts 103 may be isolated by a metal material. In this way, each air duct 103 has a separate resonance cavity, so that noise can be more effectively attenuated or eliminated.

[0089] As Figure 13 shown, the noise entering the air duct 103 enters the resonance cavity 116 through the third holes 114. When the noise passes through the resonance cavity 116, the neck of the third hole 114 and the air in the resonance cavity 116 beside the air duct 103 form a sound vibration system. For the equipment to which the noise reduction device 100 is applied, for example, the noise generated in the cabinet, when passing through the third holes 114, the noise in a certain frequency band generated in the cabinet enters the air duct 103 and resonates with the sound vibration system at the resonance cavity. The acoustic impedance here changes suddenly, causing most of the acoustic energy to be reflected back to the sound source, and a part of the acoustic energy is dissipated as heat through the friction damping of the vibration system. Only a small part of the acoustic energy can continue to propagate forward, so as to achieve the effect of attenuating or eliminating noise. The noise elimination range of the resonance cavity is usually in the low-frequency range. For example, in the range of 0 - 250 hz.

[0090] The principle of attenuating or eliminating noise by the resonance cavity structure 110 and the first expansion chamber 120 and the second expansion chamber 130 in some embodiments of the present disclosure is different, and the noise elimination frequency bands targeted are different. The first expansion chamber 120 and the second expansion chamber 130 usually target medium-frequency noise, while the resonance cavity structure 110 usually targets low-frequency noise.

[0091] As shown in Figure 11 and Figure 12 shown, two rows of third holes 114 are provided on the fourth wall 112 of the resonance cavity structure 110, which can perform two-stage noise cancellation for specific frequency band noises respectively. Obviously, it should be understood that the embodiments of the present disclosure are not limited thereto, but one row or multiple rows of third holes 114 can be provided as needed.

[0092] Figure 11 and 12 shown, the resonance cavity shown in has a cuboid shape. The embodiments of the present disclosure are not limited thereto, but can be set to other shapes as needed, such as a cylinder, or a sphere, etc. The shape of the third hole 114 can also be in various forms, such as a rectangle, a circle, an ellipse, etc.

[0093] As shown in Figure 12 shown, third holes 114 are provided on both sides of the air duct 103. Correspondingly, resonance cavity structures 110 are provided on both sides of the air duct 103.

[0094] Referring again to Figure 4 and Figure 5 shown, the air duct structure 102 may include multiple bending parts, and the first wall 122, the second wall 132, the third wall 142, and the fourth wall 112 are respectively located at different bending parts of the bending structure.

[0095] In some embodiments, the first expansion chamber 120, the second expansion chamber 130, the resistive noise reduction part 140, and the resonance cavity structure 110 are arranged in series on one side of the air duct structure 102 to form a first noise reduction structure.

[0096] In some embodiments, the air duct structure 102 and the first noise reduction structure arranged adjacent to one side or both sides of the air duct structure 102 together form a noise reduction unit; and the noise reduction device 100 may include multiple noise reduction units arranged side by side.

[0097] In some embodiments, the first space of the first expansion chamber 120, the second space of the second expansion chamber 130, and the resonance cavity of the first noise reduction unit among the multiple noise reduction units are respectively spaced apart from the first space of the first expansion chamber 120, the second space of the second expansion chamber 130, and the resonance cavity of the adjacent second noise reduction unit among the multiple noise reduction units. For example, they can be spaced apart by a metal plate or a plate made of other materials. Thus, multiple independent structures suitable for noise reduction are maintained in the noise reduction device 100.

[0098] In some embodiments, the resistive noise reduction part 140 is arranged adjacent to the outlet 108 of the air duct 103, the resonance cavity structure 110 is arranged adjacent to the inlet 106 of the air duct 103, and the first expansion chamber 120 and the second expansion chamber 130 are arranged between the resistive noise reduction part 140 and the resonance cavity structure 110.

[0099] From Figure 4 and Figure 5 It can be seen that in the illustrated embodiment, a labyrinth air duct structure 102 is adopted. This structure is particularly suitable for situations with a large flow rate, a low flow velocity, and a high required noise reduction volume. In addition, it is also suitable for occasions where the requirement for resistance loss is not strict. The noise reduction device 100 of this solution has a waterproof function. In addition, a good dustproof effect can be achieved by setting filter materials such as filter cotton at the inlet of the air duct 103.

[0100] In addition, from Figures 3 to 5 it can be seen that adjacent air ducts 103 share a resistive noise reduction part 140. In other words, the resistive noise reduction part 140 is not independent of each air duct 103 like other noise reduction structures. In this way, compared with setting an independent resistive noise reduction part 140, the same noise reduction effect can be obtained while omitting the partition.

[0101] As mentioned before, the first expansion chamber 120, the second expansion chamber 130, and the resonance cavity structure are mainly effective for noise in the low-frequency to mid-frequency range.

[0102] In the embodiments of the present disclosure, the resonance cavity structure 110, the first expansion chamber 120, the second expansion chamber 130, and the resistive noise reduction part 140 are combined to form a composite noise reduction device. It can be qualitatively considered that the noise reduction values of the resistive and reactive noise reduction structures in the same frequency band can be effectively superimposed to achieve a better noise reduction effect.

[0103] Some embodiments of the present disclosure use the combination of air duct turning + resistive noise reduction + reactive noise reduction to absorb noise in multiple directions and reduce the propagation of noise. In this sound insulation structure, during the process of the noise passing through the air duct 103, after being absorbed by multiple reactive noise reduction sections and resistive noise reduction sections, the noise energy is released to a certain extent, thereby achieving the purpose of reducing noise.

[0104] According to the noise reduction device 100 of the embodiments of the present disclosure, generally speaking, in addition to what has been mentioned before, it has the following advantages:

[0105] 1. The noise reduction frequency range for noise is relatively wide. When the noise passes through the resonance cavity and the expansion chamber part, the medium and low-frequency noise is effectively reduced. When passing through the resistive noise reduction part 140, the medium and high-frequency noise is effectively reduced.

[0106] 2. Using an impedance composite muffler for noise reduction, by combining the resonance cavity, the expansion chamber, and the resistive noise reduction part, not only is the length of the air duct through which the noise passes long and the number of noise reflections relatively large, but also multiple noise reductions can be achieved, thus having a significant noise reduction effect.

[0107] 3. Using multiple noise reduction methods can effectively absorb the noise in the low - medium frequency band and the medium - high frequency band.

[0108] Briefly, some solutions of the embodiments of the present disclosure can effectively eliminate noise in a relatively wide frequency range by combining the structures and performances of various mufflers through reasonable collocation, so as to adjust the sound absorption effect to the optimal.

[0109] In addition, it should be noted that in the above embodiments, the solutions of the present invention are shown in combination with specific structures shown in the accompanying drawings. It should be understood that the embodiments of the present disclosure are not limited thereto, but can be variously deformed. For example, in the embodiments shown in the accompanying drawings, the noise reduction device 100 includes a plurality of noise reduction structures, that is, a combined noise reduction structure is shown. It should be understood that the embodiments of the present disclosure are not limited thereto, and can include at least one of them as needed, that is, can include one or any combination of the first expansion chamber 120, the second expansion chamber 130, the resonance cavity structure 110, and the resistive noise reduction part 140. Moreover, the shapes and structures of each noise reduction structure can be changed.

[0110] Figure 14 A schematic diagram of a sound insulation cover including a noise reduction device 100 according to some exemplary embodiments of the present disclosure is shown.

[0111] Embodiments of the present disclosure provide a sound insulation cover structure 200 capable of noise reduction. As Figure 14 shown in the figure, the sound insulation cover structure 200 includes: a protective cover 202; a door panel 204; a noise reduction device (which can be called a sound insulation louver) 100; a wire mesh and filter cotton 206; and further may include a fan mounting plate 208. The noise reduction device 100 can be fixed to the door panel 204. The protective cover 202 can be installed outside the noise reduction device 100 to protect it and prevent dust or other sundries from entering.

[0112] The sound insulation cover structure 200 has a wide range of applications, such as in indoor and outdoor electrical, communication, control and other structures. It has greater advantages in outdoor structures and can effectively weaken various noises generated when the equipment is running.

[0113] In addition, according to the embodiments of the present disclosure, a power device 400 is further provided, which will be further described below in conjunction with the attached Figures 15 to 18 drawings.

[0114] Figure 15 A three-dimensional schematic diagram of a power device 400 provided with a noise reduction device 100 according to some exemplary embodiments of the present disclosure is shown. As Figure 15 shown, the power device 400 includes a main unit 300, and the main unit 300 can be any device capable of generating noise. For example, a common power device 400 with a fan for air-cooling the heat-generating components therein. The main unit 300 has a housing, and the inner housing is provided with, for example, various modules and a fan for air-cooling the corresponding modules. As Figure 15As shown, a noise reduction device 100 is provided on each side of the host 300 to reduce the noise generated inside the host.

[0115] In the embodiments of the present disclosure, the application mode of the noise reduction device 100 is usually an embedded type. For example, it can be installed at the air inlet and outlet 109 on the left and right sides of the cabinet. In some embodiments, the noise reduction device 100 uses an embedded air duct and is applied to a 180KW DC charging pile. The design range of the length of the embedded air duct is relatively large, which can meet the design requirements of the composite sound insulation cover, and the length of the resistive noise reduction part 140 can also be guaranteed, increasing the effective absorption times of the sound insulation cotton and having a good noise reduction effect. For example, it can handle noise in the range of 500HZ - 5000HZ.

[0116] Figure 16 As shown Figure 15 a front view of the power equipment 400 as shown. Figure 17 As shown Figure 15 a right view of the power equipment 400 as shown. Figure 18 As shown Figure 15 a left view of the power equipment 400 as shown. As Figure 17 and 17 shown, an air outlet 109 is provided on the protective cover 202, which communicates with the outlet 108 of the air duct 103 of the noise reduction device 100.

[0117] It should be noted that the noise reduction device provided by the present disclosure can not only ensure the effective cooling of the equipment, but also weaken the noise to meet the target requirements. In addition, the solution of the embodiments of the present disclosure maximizes the reduction of the noise generated during the heat dissipation of the cabinet after meeting the basic requirements of the heat dissipation of the cabinet of the host, and is convenient to be applied to old models without affecting the internal structure of the cabinet. Using the structure of the impedance composite muffler greatly reduces the propagation of noise. It can be adjusted according to the needs of outdoor equipment and is also compatible with various types of usage environments, with strong practicability, thus having good social and economic benefits.

[0118] In some embodiments of the present disclosure, the noise reduction device applicable to DC charging piles is described. It should be understood that the noise reduction device of the embodiments of the present disclosure is not limited to being applied to DC charging piles, but can be applied to any equipment that generates noise, especially suitable for power equipment that requires air cooling.

[0119] The embodiments of the present disclosure have been described above. The above description is exemplary and only an alternative embodiment of the present disclosure. It is not exhaustive and does not limit the present disclosure. Although the claims in this application have been formulated for specific combinations of features, it should be understood that the scope of the present disclosure also includes any novel feature or any novel combination of features that are explicitly or implicitly disclosed herein or any generalization thereof, regardless of whether it relates to the same solution in any of the currently claimed claims. The applicant hereby informs that new claims may be formulated for these features and / or combinations of these features during the examination process of this application or in any further application derived therefrom.

[0120] The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other ordinary technicians in the technical field to understand the embodiments disclosed herein. For those skilled in the art, various changes and modifications can be made to the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A noise reduction device (100), comprising: Air duct structure (102), the air duct structure (102) comprising: An air duct wall that defines an air duct (103), the air duct (103) including an inlet (106) and an outlet (108); Wherein, the air duct wall includes a first wall (122), and a first hole (124) is provided in a first region (125) of the first wall (122); and A first expansion chamber (120) is disposed adjacent to the first wall (122) of the air duct structure (102), the first expansion chamber (120) including a first expansion chamber wall, the first expansion chamber wall and the first wall (122) defining a first space, the first space communicating with the air duct (103) through the first hole (124); Wherein, the first hole (124) is configured such that the acoustic impedance in the air duct (103) increases at the first region (125), the increased amount exceeding a first threshold to prevent sound waves in a first frequency band entering the air duct (103) through the inlet (106) from passing through the outlet (108).

2. The noise reduction device (100) according to claim 1, wherein: The first wall (122) is uniformly provided with a plurality of the first holes (124) in a first array form.

3. The noise reduction device (100) according to claim 2, wherein: The porosity of the plurality of the first holes (124) at the first region (125) of the first wall (122) is above 30%, where the porosity represents the ratio of the opening area of the plurality of the first holes (124) to the area of the first region (125).

4. The noise reduction device (100) according to any one of claims 1 to 3, wherein the air duct wall further comprises a second wall (132), the second wall (132) is adjacent to the first wall (122), a second hole (134) is provided in a second area (127) of the second wall (132), and the noise reduction device (100) further comprises: A second expansion chamber (130) is disposed adjacent to the second wall (132), the second expansion chamber (130) including a second expansion chamber wall, the second expansion chamber wall and the second wall (132) defining a second space, the second space communicating with the air duct (103) through the second hole (134); Wherein, the second hole (134) is configured such that the acoustic impedance of the air duct (103) increases at the second region (127), the increased amount exceeding a second threshold, thereby preventing sound waves in a second frequency band entering the air duct (103) through the inlet (106) from passing through the outlet.

5. The noise reduction device (100) according to claim 4, wherein: The second wall (132) is uniformly provided with a plurality of the second holes (134) in a second array form.

6. The noise reduction device (100) according to claim 4, wherein the air duct wall further comprises a third wall (142), and the noise reduction device (100) further comprises: A resistive noise reduction part (140) is disposed adjacent to the third wall (142), the resistive noise reduction part (140) including a resistive noise reduction wall, the resistive noise reduction wall and the third wall (142) defining a third space; Absorbent material is provided in the third space so that sound waves in a third frequency band entering the air duct (103) through the inlet (106) are attenuated.

7. The noise reduction device (100) according to claim 6, wherein, The air duct wall further includes a fourth wall (112), the fourth wall (112) being provided with a plurality of third holes (114), and the noise reduction device (100) further includes: A resonance cavity structure (110) is disposed adjacent to the fourth wall (112), the resonance cavity structure (110) including a resonance cavity wall, the resonance cavity wall and the fourth wall (112) defining a resonance cavity; Each of the plurality of third holes (114) is configured to form a sound vibration system with the resonance cavity respectively, so that the sound waves in the fourth frequency band entering the air duct (103) through the inlet (106) are attenuated by forming resonance with the sound vibration system.

8. The noise reduction device (100) according to claim 7, wherein: The resonance cavity has one of the following shapes: a cuboid, a cylinder or a sphere.

9. The noise reduction device (100) according to claim 7, wherein: The plurality of third holes (114) are uniformly arranged on the fourth wall (112) in a third array form, and the distribution density of the plurality of third holes (114) is respectively less than the distribution density of the plurality of first holes (124) and the plurality of second holes (134).

10. The noise reduction device (100) according to claim 7, wherein: The air duct structure (102) includes a plurality of bending parts, and the first wall (122), the second wall (132), the third wall (142) and the fourth wall (112) are respectively located at different bending parts.

11. The noise reduction device (100) according to claim 7, wherein: The first expansion chamber (120), the second expansion chamber (130), the resistive noise reduction part (140) and the resonance cavity structure (110) are arranged in series on one side of the air duct structure (102) to form a first noise reduction structure.

12. The noise reduction device (100) according to claim 11, wherein: The air duct structure (102) and the first noise reduction structure arranged adjacent to one side or both sides of the air duct structure (102) together form a noise reduction unit; and The noise reduction device (100) includes a plurality of the noise reduction units arranged side by side.

13. The noise reduction device (100) according to claim 12, wherein: The first space of the first expansion chamber (120), the second space of the second expansion chamber (130) and the resonance cavity of the first noise reduction unit among the plurality of noise reduction units are respectively spaced apart from the first space of the first expansion chamber (120), the second space of the second expansion chamber (130) and the resonance cavity of the adjacent second noise reduction unit among the plurality of noise reduction units.

14. The noise reduction device (100) according to claim 12, wherein: The resistive noise reduction part (140) is arranged adjacent to the outlet (108) of the air duct (103), the resonance cavity structure (110) is arranged adjacent to the inlet (106) of the air duct (103), and the first expansion chamber (120) and the second expansion chamber (130) are arranged between the resistive noise reduction part (140) and the resonance cavity structure (110).

15. A power device (400), comprising: A main machine (300), a noise source is arranged in the housing of the main machine (300); and The noise reduction device (100) according to any one of claims 1 to 14, which is configured to be coupled to the housing to perform noise reduction processing on the noise from the noise source.

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