CN117627964A

CN117627964A - Noise reduction device and vehicle

Info

Publication number: CN117627964A
Application number: CN202210976246.7A
Authority: CN
Inventors: 刘瑞骏; 钱新; 危敏
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2022-08-15
Filing date: 2022-08-15
Publication date: 2024-03-01

Abstract

The application provides a noise reduction device and vehicle, wherein, noise reduction device includes: the flow guiding component is internally provided with a cavity, and is provided with a first through hole which is communicated with the cavity; the shell is fixed on the flow guiding component and at least partially positioned outside the flow guiding component; the device comprises a plurality of silencing structures, wherein the silencing structures are fixed on a flow guiding component and cover a first through hole, each silencing structure comprises a perforated plate and a back cavity positioned on a first plate surface of the perforated plate, the back cavity of at least one silencing structure is formed by a shell and the perforated plate, and the size parameters of the first silencing structure and the second silencing structure in the silencing structures are different. The effective noise reduction frequency band of the noise reduction device can be widened.

Description

Noise reduction device and vehicle

Technical Field

The application relates to the technical field of fan noise reduction, in particular to a noise reduction device and a vehicle.

Background

With the rapid development and application of intelligent cabins, the number of vehicle-mounted devices is gradually increased, and more vehicle-mounted devices have heat dissipation requirements, so that corresponding fans are arranged on the vehicle. As one of noise sources in a vehicle, a fan is easily caught by human ears and is uncomfortable, and thus noise, vibration and harshness (Noise Vibration Harshness, NVH) of the vehicle are increasingly problematic, and thus noise reduction treatment of the fan is required.

In the related art, a micro-perforated muffler is generally used to reduce noise of a fan, as shown in fig. 2, the micro-perforated muffler 11 includes an inner shroud 113 and an outer shroud 114, wherein the inner shroud 113 is fixed to an air outlet of the fan 20, the inner shroud 113 includes a perforated plate 115, and a back cavity 116 is formed between the perforated plate 115 and the outer shroud 114. The curve 4b in the graph of sound absorption coefficient shown in fig. 4 can be obtained by performing a simulation experiment on the microperforated muffler in the related art, and it can be seen from the curve 4b that the effective noise reduction frequency band of the microperforated muffler is about 1500Hz to 2400Hz.

Since fans typically have a plurality of different gear positions, each corresponding to a different rotational speed and blade passing frequency, the blade passing frequency range is wide, for example, a centrifugal fan having a blade passing frequency range of 1290Hz-3010Hz. It can be seen that the effective noise reduction frequency band of the microperforated muffler of the related art does not cover the blade passing frequency range, and thus, the noise reduction of the fan having a wide blade passing frequency range cannot be satisfied.

Disclosure of Invention

In order to solve the technical problem, the application provides a noise reduction device and a vehicle so as to widen the effective noise reduction frequency band of the noise reduction device.

The application provides a noise reduction device, including: the flow guiding component is internally provided with a cavity, and is provided with a first through hole which is communicated with the cavity; the shell is fixed on the flow guiding component and at least partially positioned outside the flow guiding component; the device comprises a plurality of silencing structures, wherein the silencing structures are fixed on a flow guiding component and cover a first through hole, each silencing structure comprises a perforated plate and a back cavity positioned on a first plate surface of the perforated plate, the back cavity of at least one silencing structure is formed by a shell and the perforated plate, and the size parameters of the first silencing structure and the second silencing structure in the silencing structures are different.

When the noise reduction device is applied to a vehicle, the flow guide part can be fixed on the fan and positioned at the air outlet, so that air flow flowing out of the air outlet of the fan can flow to the cavity inside the flow guide part. The sound-deadening structures are fixed on the flow-guiding component and cover the first through holes, so that air flows through the perforated plates of each sound-deadening structure when flowing in the cavity, and as the perforated plates are provided with a plurality of perforations, part of air flows through the perforated plates can pass through the perforations and enter the back cavity positioned on the first plate surface of the perforated plates, then flow out from the back cavity through the perforations of the perforated plates, and in the process, the sound energy is converted into heat energy to be dissipated through multiple friction between the sound energy and the perforations so as to weaken sound waves; in addition, in the flowing process of the air flow, air molecules in the air flow vibrate, the vibration is transmitted, pressure is generated by vibration, and the noise elimination structure can form obstruction to the pressure, so that the purpose of noise reduction is achieved.

Because in this application, the size parameters of first sound attenuation structure and second sound attenuation structure are different, consequently, first sound attenuation structure and second sound attenuation structure's sound absorption coefficient under the same blade pass frequency is different, and then first sound attenuation structure and second sound attenuation structure's the blade pass frequency that the biggest sound absorption coefficient corresponds is different. The sound absorption coefficient curve corresponding to the sound attenuation structure is generally parabolic, and in the application, the sound absorption coefficient curve of the noise reduction device includes a curve obtained by overlapping the parabolic sound absorption coefficient curve corresponding to the first sound attenuation structure and the parabolic sound absorption coefficient curve corresponding to the second sound attenuation structure, so that when the airflow in the flow guiding component passes through the first sound attenuation structure and the second sound attenuation structure respectively, the effective sound absorption frequency band of the sound absorption coefficient curve obtained finally is wider, that is, the noise reduction device can obtain a wider effective sound absorption frequency band.

In some possible implementations, the dimensional parameters include: at least one of the plate thickness, the hole penetration rate, the hole penetration diameter, the area of the first plate surface and the depth of the back cavity. Since the relative acoustic impedance of each sound damping structure can be calculated based on the blade passing frequency, the sound velocity in the air, the plate thickness of the microperforations, the perforation rate, the perforation diameter, and the depth of the back cavity, while the relative acoustic impedance of the sound damping device is calculated based on the relative acoustic impedance of each sound damping structure and the area of the first plate surface, when at least one of the plate thickness, the perforation rate, the perforation diameter, and the depth of the perforated plate in the first sound damping structure and the second sound damping structure is different, the relative acoustic impedances of the first sound damping structure and the second sound damping structure are different, and the blade passing frequency corresponding to the maximum sound absorption coefficient of the first sound damping structure and the second sound damping structure is different, whereby the effective sound absorption band of the sound damping device can be made wider.

In some possible implementations, the dimensional parameters of each sound attenuating structure are different. Thus, each sound attenuation structure corresponds to a parabolic sound absorption coefficient curve with different effective sound absorption frequency bands, and the sound absorption coefficient curve of the noise reduction device corresponds to superposition of the sound absorption coefficient curves of each sound attenuation structure, so that the effective sound absorption frequency bands can be further widened.

In some possible implementations, the first sound attenuating structure and the second sound attenuating structure are adjacent; the noise reduction device further comprises a baffle, and the baffle is fixed on the first plate surface of the first noise elimination structure and/or the second noise elimination structure. Like this, when the air current is through between first sound-damping structure and the second sound-damping structure, separate the shelves and can block the air current in the first sound-damping structure for the majority air current that gets into the back of the body chamber of first sound-damping structure flows out the perforated plate rethread second sound-damping structure's of first sound-damping structure perforated plate and gets into the second sound-damping structure, and not directly flows to the back of the body chamber of second sound-damping structure from the back of the body chamber of first sound-damping structure, thereby can reduce the influence to the air current in the water conservancy diversion part, and then reduce the influence to the fan performance.

In some possible implementations, the baffle is fixed to the first plate surface of the first sound-damping structure, and the dimension of the baffle along the depth direction of the back cavity is the same as the depth of the back cavity of the first sound-damping structure; or the baffle is fixed on the first plate surface of the second silencing structure, and the dimension of the baffle along the depth direction of the back cavity is the same as the depth of the back cavity of the second silencing structure; or the first part of the baffle is fixed on the first plate surface of the second silencing structure, and the dimension of the first part of the baffle along the depth direction of the back cavity is the same as the depth of the back cavity of the second silencing structure; the second part of the baffle is fixed on the first plate surface of the second silencing structure, and the dimension of the second part of the baffle along the depth direction of the back cavity is the same as the depth of the back cavity of the second silencing structure. Like this, separate the size of shelves along the degree of depth direction in back chamber, the degree of depth in back chamber rather than being located is the same, can block the air current that flows between the back chamber of first sound damping structure and the back chamber of second sound damping structure from this well to further reduce the influence to the air current in the water conservancy diversion part, and then reduce the influence to the fan performance.

In some possible implementations, the first sound attenuating structure and the second sound attenuating structure are located on the same layer, and the projection of the perforated plate of the first sound attenuating structure on the flow guiding member and the projection of the perforated plate of the second sound attenuating structure on the flow guiding member both cover a partial area of the first through hole. That is, the air flow flowing out from the air outlet of the fan is subjected to the silencing treatment of each silencing structure, so that the number of perforations rubbed with the air flow is increased, and the dissipated heat energy of the air flow is further increased, so that the sound wave is further weakened.

In some possible implementations, the flow directing member has first and second openings opposite and aligned in the first direction, each of the first and second openings communicating with the cavity; the first silencing structure and the second silencing structure are arranged side by side, and the arrangement direction is the first direction. In this way, the air flow flowing out from the air outlet of the fan enters the cavity of the flow guiding component from the first opening of the flow guiding component, flows out from the second outlet, and sequentially passes through the noise reduction treatment of the first noise elimination structure and the second noise elimination structure when the air flow goes forward in the cavity, so that the noise reduction effect can be improved.

In some possible implementations, the flow directing member has first and second openings opposite and aligned in the first direction, each of the first and second openings communicating with the cavity; the first silencing structure and the second silencing structure are arranged in a stacked mode, an included angle is formed between the stacking direction and the first direction, and an included angle is formed between the stacking direction and the first direction. In this way, the air flow flowing out from the air outlet of the fan enters the cavity of the flow guiding component from the first opening of the flow guiding component and flows out from the second outlet. When the air flow goes forward in the cavity, part of the air flow passes through the first silencing structure, enters the back cavity of the first silencing structure from the perforated plate of the first silencing structure, and flows out from the perforation of the perforated plate of the first silencing structure so as to weaken sound waves; in addition, the first silencing structure and the second silencing structure can form obstruction to pressure generated by airflow in the flowing process, and therefore noise reduction effect can be further improved.

In some possible implementations, the perforated plates of the first sound attenuating structure and the perforated plates of the second sound attenuating structure are stacked with a gap between each two adjacent perforated plates. When the air flow flowing out from the air outlet of the fan goes forward in the cavity, part of the air flow firstly passes through the first silencing structure, enters the back cavity of the first silencing structure from the perforated plate of the first silencing structure, and flows out through the perforation of the perforated plate of the first silencing structure so as to weaken sound waves; in addition, the first silencing structure and the second silencing structure can form obstruction to pressure generated by airflow in the flowing process, and therefore noise reduction effect can be further improved.

In some possible implementations, the perforated plates of the first sound attenuating structure and the perforated plates of the second sound attenuating structure are arranged side by side with an angle between the arrangement direction and the first direction. Like this, when the air current that flows from the air outlet of fan when the cavity is inside to go forward, a part of air current is through first sound damping structure, and a part of air current is through second sound damping structure, and first sound damping structure and second sound damping structure fall respectively these two parts of air currents to can further promote the noise reduction effect.

In some possible implementations, the plurality of sound attenuating structures are provided in multiple layers, and at least one of the sound attenuating structures includes at least one sound attenuating structure, and at least one of the sound attenuating structures includes at least two sound attenuating structures. In this way, when the air flow in the cavity moves forward in the cavity, part of the air flow enters the back cavity through the perforated plate of the silencing structure closest to the flow guiding component and then flows out of the perforated plate so as to weaken sound waves; the pressure generated by the air flow sequentially passes through the noise reduction treatment of each layer of noise elimination structure, so that the noise reduction effect can be further improved.

In some possible implementations, the first partial sound attenuating structures are arranged side by side and the second partial sound attenuating structures are arranged in a stack. Like this, when the air current that flows from the air outlet of fan when the cavity is inside to go forward, a part of air current is through first sound damping structure, and a part of air current is through second sound damping structure, and first sound damping structure and second sound damping structure fall respectively these two parts of air currents to can further promote the noise reduction effect.

In some possible implementations, the perforated plate of the first partial sound attenuating structure has an angle with the perforated plate of the second partial sound attenuating structure. Therefore, the air flow flowing in the cavity of the flow guide component is firstly subjected to noise reduction treatment of the first part of noise elimination structure and then is subjected to noise reduction treatment of the second part of noise elimination structure, and therefore the noise reduction effect can be further improved.

In some possible implementations, the thicknesses of the perforated plates arranged along the first direction are different, and the second plate surfaces of the perforated plates covering the first through holes are flush, and the second plate surfaces are opposite to the first plate surfaces. Because the back cavity of each sound-deadening structure is positioned on the first plate surface of the perforated plate, the back cavity depth of each sound-deadening structure can be realized through the difference of the plate thickness of each perforated plate, and the scheme is easy to realize. In addition, because the second face of each perforated plate is parallel and level, can reduce from this because of the second face of each perforated plate is not parallel and level leads to the condition that leads to the fact the air current in the cavity of water conservancy diversion part to influence fan performance.

In some possible implementations, the casing includes a bottom wall and a side wall fixed to a side surface of the bottom wall, the side wall is fixed to the flow guiding member, the bottom wall is stepped, and a distance between the bottom wall and each of the perforated plates arranged along the first direction is different. Therefore, the back cavity depth of each silencing structure can be different through the stepped bottom wall, the scheme is easy to realize, and the influence on the air flow in the cavity of the flow guide component is small.

In some possible implementations, the material of the perforated plate of the at least one sound attenuating structure comprises metal. The heat conductivity of the metal is better, and the heat dissipation performance is better, so that after the sound energy is converted into heat energy when the air flow in the flow guide component passes through the perforation of the perforated plate, the metal can well disperse the heat energy, thereby improving the relative acoustic impedance of the silencing structure and further improving the noise reduction effect.

In some possible implementations, the at least one sound attenuating structure further includes a sound absorbing portion, the sound absorbing portion being made of a sound absorbing material, the sound absorbing portion being positioned within the back cavity. Therefore, when the air flow in the cavity of the flow guide component enters the back cavity of the silencing structure, the sound absorption part in the back cavity can well block the pressure generated by the air flow, and accordingly the noise reduction effect is further improved.

The application also provides a vehicle, including fan and the device of making an uproar falls in any one of the aforesaid, the water conservancy diversion part of the device of making an uproar falls is fixed in the fan. The vehicle can achieve all effects of the noise reduction device.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments of the present application will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a related art noise reduction device;

FIG. 2 is a schematic diagram of another related art noise reduction device;

FIG. 3 is a simplified schematic diagram of the microperforated muffler of FIGS. 1 and 2;

FIG. 4 is a graph comparing sound absorption curves obtained by performing simulation experiments on the microperforated muffler shown in FIG. 3 and the noise reduction device shown in FIG. 7;

FIG. 5a is a graph showing a plurality of sound absorption coefficient curves corresponding to different perforation diameters obtained by performing a simulation experiment on the microperforated muffler shown in FIG. 3;

FIG. 5b is a graph showing a plurality of sound absorption coefficient curves corresponding to different perforation rates obtained by performing simulation experiments on the microperforated muffler shown in FIG. 3;

FIG. 5c is a graph showing a plurality of sound absorption coefficient curves corresponding to different back cavity depths obtained by performing a simulation experiment on the microperforated muffler shown in FIG. 3;

FIG. 6a is a schematic diagram illustrating an assembled structure of a noise reducer and a fan according to an embodiment of the present disclosure;

FIG. 6b is a schematic diagram illustrating an assembled structure of a noise reducer and another fan according to an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of the noise reducer shown in FIG. 6 a;

FIG. 8 is a schematic view of a flow directing member of the noise reducer of FIG. 7;

FIG. 9 is a schematic structural view of a noise reduction device according to another embodiment of the present disclosure;

FIG. 10 is a schematic structural view of a noise reduction device according to another embodiment of the present disclosure;

FIG. 11 is a schematic structural view of a noise reduction device according to another embodiment of the present disclosure;

FIG. 12 is a schematic view of a noise reducer according to another embodiment of the present disclosure;

FIG. 13 is a schematic view of a noise reducer according to another embodiment of the present disclosure;

fig. 14 is a schematic structural diagram of a noise reduction device according to another embodiment of the present application.

Icon: 10-a noise reduction device; 11-microperforated muffler; 111-a sound deadening hole; 113-an inner shield; 114-an outer shield; 115-a perforated plate; 1151-piercing; 116-back cavity; 12-a conical deflector; 121-a tapered surface; 20-a fan; 21-an axial fan; 22-centrifugal fans; 23-air flow; 30-a flow guiding component; 31-side plates; 311-a first side plate; 312-a second side plate; 33-a first surface; 331-a first opening; 34-a second surface; 341-a second opening; 35-cavity; 36-a first through hole; 40-a housing; 41-a bottom wall; 411-a first bottom plate; 412-a second floor; 42-side walls; 50-a sound attenuation structure; 51-a first sound attenuating structure; 511-a first perforated plate; 5112-a first panel; 5113-a second deck; 512-a first back cavity; 52-a second sound attenuating structure; 521-a second perforated plate; 522-a second back cavity; 53-sound absorbing part; 54-a third sound attenuation structure; 541-a third perforated plate; 55-fourth sound attenuation structure; 551-fourth perforated plate; 60-gear.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

The term "and/or" is herein merely an association relationship describing an associated object, meaning that there may be three relationships, e.g., a and/or B, may represent: a exists alone, A and B exist together, and B exists alone.

The terms "first" and "second" and the like in the description and in the claims, are used for distinguishing between different objects and not for describing a particular sequential order of objects. For example, the first target object and the second target object, etc., are used to distinguish between different target objects, and are not used to describe a particular order of target objects.

In the embodiments of the present application, words such as "exemplary" or "such as" are used to mean serving as examples, illustrations, or descriptions. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.

In the description of the embodiments of the present application, unless otherwise indicated, the meaning of "a plurality" means two or more. For example, the plurality of processing units refers to two or more processing units; the plurality of systems means two or more systems.

Noise, vibration and harshness (Noise Vibration Harshness, NVH) of a vehicle are one of important performance indexes in objective evaluation of an entire vehicle owner, and with rapid development and application of an intelligent cabin, the number of vehicle-mounted devices such as a vehicle machine, wireless quick charge and the like is gradually increased, wherein more vehicle-mounted devices have heat dissipation requirements, and therefore, the vehicle is provided with fans. The fan vibrates the blades when in operation, thereby generating noise that is easily caught by human ears and is uncomfortable. Moreover, due to the increasing abundance of in-vehicle infotainment functions, drivers and passengers use vehicle-mounted devices more and more frequently while parking, resulting in more and more NVH problems of the vehicle, and thus, noise reduction treatment of the fan is required.

Fans equipped on vehicles tend to be smaller in size and limited in installation space, with noise management often being more difficult. If the noise is reduced by reducing the rotation speed of the fan, the heat radiation performance is poor, and therefore, a noise reduction device for reducing the noise of the fan on the premise of not affecting the heat radiation performance needs to be provided. In view of the above, the noise reduction device needs to have the following features, in the first aspect, since the fan equipped on the vehicle may be an axial fan or a centrifugal fan, the noise reduction device needs to have better universality, and can be applied to both the axial fan and the centrifugal fan; in the second aspect, the noise reduction device needs to have a small overall size, and be suitable for being installed in a narrow space inside a vehicle; in the third aspect, since the fan generally has a plurality of different gear positions, each corresponding to a different rotational speed and blade passing frequency, so that the operating band of the fan is wide, the noise reduction device needs to have a wide effective noise reduction band.

The microperforated muffler is a noise reduction device which is widely used and can meet the requirements, and has the characteristics of simple structure, moisture resistance, high temperature resistance, no pollution and the like, so that the microperforated muffler is adopted in many related technologies. In one related art, such as shown in fig. 1, a noise reduction device 10 includes a microperforated muffler 11 and a conical deflector 12. The micro-perforated muffler 11 is provided at an inner surface thereof with a sound deadening hole 111, and the inside of the sound deadening hole 111 is filled with glass wool. The conical surface 121 of the conical deflector 12 protrudes into the microperforated muffler 11, the conical surface 121 also being provided with sound attenuation holes 111. The scheme utilizes the sound attenuation characteristic of the microperforated muffler 11 and the porous sound absorption characteristic of the glass wool to achieve the purpose of noise reduction.

In another related art, as shown in fig. 2, the noise reducing device 10 includes a micro-perforated muffler 11, the micro-perforated muffler 11 includes an inner shroud 113 and an outer shroud 114, wherein the inner shroud 113 is fixed to an air outlet of the fan 20, the inner shroud 113 includes a perforated plate 115, and a back cavity 116 is formed between the perforated plate 115 and the outer shroud 114. When the air flow flowing out from the air outlet of the fan 20 passes through the inner shroud 113, the air flow enters the back cavity 116 through the perforated plate 115 of the inner shroud 113 and then flows out from the back cavity 116 through the perforated plate 115, thereby noise reduction is performed on the fan 20.

The microperforation muffler 11 shown in fig. 1 and 2 may be simplified to the structure shown in fig. 3, and as shown in fig. 3, the microperforation muffler 11 includes a perforated plate 115 and a back chamber 116 located at one side of the perforated plate 115, and when a part of the air flow is blown vertically onto the perforated plate 115, it flows from the perforations 1151 of the perforated plate 115 into the back chamber 116 and then flows out from the back chamber 116 through the perforations 1151, and during this process, multiple friction with the perforations 1151 converts the acoustic energy into thermal energy to dissipate, thereby attenuating the acoustic wave; in addition, during the flowing process of the air flow 23, air molecules in the air flow 23 vibrate, and the vibration is transmitted to generate pressure, and the micro-perforated muffler 11 can form obstruction to the pressure, so that the purpose of noise reduction is achieved. The microperforated muffler 11 comprises four important dimensional parameters, namely the plate thickness t of the perforated plate 115, the perforation diameter D, the perforation rate sigma, and the depth D of the back cavity 116. Where the perforation ratio σ refers to the ratio between the sum of the projected areas of all perforations 1151 on the plate surface of the perforated plate 115 and the surface area of the plate surface.

Before determining the effective sound absorption band of the microperforated muffler, it is necessary to calculate the relative acoustic impedance of the microperforated muffler and then calculate the sound absorption coefficient from the relative acoustic impedance, thereby determining the effective sound absorption band from the sound absorption coefficient curve. The relative acoustic impedance refers to the ratio of the acoustic impedance of the microperforated muffler to the acoustic impedance of air at normal temperature and pressure, and the acoustic impedance of the microperforated muffler comprises acoustic impedance and acoustic impedance. The relative acoustic impedance of the microperforated muffler may be calculated according to a first expression:

Wherein Z is _i The relative acoustic impedance of the microperforated muffler is represented by r, the relative acoustic impedance of the microperforated muffler is represented by j, the imaginary unit is represented by f, the frequency is represented by m, the relative acoustic mass of the microperforated muffler is represented by D, the depth of the back cavity is represented by c, the sound velocity is represented by c, and r and m are the perforation diameter D and the plate thickness tAnd a function of the perforation rate sigma.

When the sound field is perpendicularly incident to the perforated plate, the sound absorption coefficient of the microperforated muffler may be calculated according to a second expression:

where α represents the sound absorption coefficient of the microperforated muffler, re (Z) represents the real part of Z, and Im (Z) represents the imaginary part of Z. As can be seen from the first expression, the second expression, and the third expression, when the frequency f is unchanged, the sound absorption coefficient α of the microperforated muffler is related to the perforation diameter D, the plate thickness t, the perforation ratio σ, and the depth D of the back cavity 116, i.e., at least one of the perforation diameter D, the plate thickness t, the perforation ratio σ, and the depth D of the back cavity 116 is changed, and the sound absorption coefficient α of the microperforated muffler is also changed.

In the related art shown in fig. 1 and 2, only one micro-perforated muffler 11 is included, and the perforated diameter D, the plate thickness t, and the depth D of the back cavity 116 of the micro-perforated muffler 11 are all the same, and therefore, simulation experiments were performed on the micro-perforated muffler 11 to obtain a sound absorption coefficient graph shown in fig. 4, wherein the graph 4b is a sound absorption coefficient graph of the noise reduction device of the related art, the perforation ratio σ is 0.03, the perforated diameter D is 0.6mm, the depth D of the back cavity is 10mm, and the plate thickness t of the perforated plate 115 is 1.4mm. As shown in fig. 4, the abscissa represents the blade passing frequency of the fan, and the ordinate represents the sound absorption coefficient, which tends to decrease before and after rising with an increase in the blade passing frequency.

The effective sound absorption frequency band of the microperforated muffler can be obtained by plotting in a sound absorption coefficient graph, for example, determining the maximum sound absorption coefficient, then taking half of the maximum sound absorption coefficient, and making a line parallel to the abscissa from the half of the maximum sound absorption coefficient, wherein the frequency range between two points where the line intersects with the sound absorption coefficient graph is the effective noise reduction frequency band of the microperforated muffler. For example, in fig. 4, the maximum sound absorption coefficient is about 0.81 and half of the maximum sound absorption coefficient is 0.405, and thus, as can be seen from fig. 4, the effective sound absorption frequency band of the microperforated muffler ranges from 1500Hz to 2400Hz.

The noise of the fan is mainly generated by the rotation of the blades, the passing frequency f of the blades _p According to a third expression, the third expression is:

wherein f _p The blade passing frequency of the fan is represented by p, the number of blades of the fan is represented by n, and the rotational speed of the fan is represented by n.

When the fan actually works, the rotating speed can be adjusted according to the heat dissipation requirement, and the rotating speed span is generally larger, so that the passing frequency of the blades can also change in a larger range, and particularly, the centrifugal fan with more blades is provided. For example, a centrifugal fan comprising 43 blades, which pass through the frequency range 1290Hz-3010Hz when its rotational speed varies between 1800rpm and 4200 rpm. Therefore, the effective sound absorption frequency band of the microperforated muffler in the related art is narrower than the blade passing frequency band, and the working conditions of the rotating speeds of the fans cannot be considered well.

Next, the influence of each dimensional parameter of the microperforated muffler on the sound absorption coefficient and the effective sound absorption frequency band is determined through simulation experiments.

When the plate thickness t of the perforated plate is 1.4mm, the perforation ratio sigma is 0.05, and the depth D of the back cavity is 10mm, the effect of different perforation diameters D on the sound absorption coefficient is obtained as shown in fig. 5 a. As shown in fig. 5a, 6 curves are included, curve 1a is a sound absorption coefficient curve corresponding to a perforation diameter d of 0.3mm, curve 1b is a sound absorption coefficient curve corresponding to a perforation diameter d of 0.4mm, curve 1c is a sound absorption coefficient curve corresponding to a perforation diameter d of 0.5mm, curve 1d is a sound absorption coefficient curve corresponding to a perforation diameter d of 0.6mm, curve 1e is a sound absorption coefficient curve corresponding to a perforation diameter d of 0.7mm, and curve 1f is a sound absorption coefficient curve corresponding to a perforation diameter d of 0.8 mm. As can be seen from fig. 5a, in the case that the other dimensional parameters are the same, the perforation diameter d is different, the maximum sound absorption coefficient is also different, the corresponding effective sound absorption frequency band is also different, and when the perforation diameter d is smaller, the maximum sound absorption coefficient is larger, and the effective sound absorption frequency band is also wider.

When the plate thickness t of the perforated plate is 1.4mm, the perforation diameter D is 0.3mm, and the depth D of the back cavity is 10mm, the influence of different perforation rates sigma on the sound absorption coefficient is obtained, as shown in fig. 5b, wherein 5 curves are included, curve 2a is the sound absorption coefficient curve corresponding to the perforation rate sigma of 0.01mm, curve 2b is the sound absorption coefficient curve corresponding to the perforation rate sigma of 0.02mm, curve 2c is the sound absorption coefficient curve corresponding to the perforation rate sigma of 0.03mm, curve 2D is the sound absorption coefficient curve corresponding to the perforation rate sigma of 0.04mm, and curve 2e is the sound absorption coefficient curve corresponding to the perforation rate sigma of 0.05 mm. As can be seen from fig. 5b, in the case where the other dimensional parameters are the same, the perforation ratio σ is different, the maximum sound absorption coefficient is different, and the corresponding effective sound absorption frequency band is also different.

When the plate thickness t of the perforated plate is 1.4mm, the perforation rate sigma is 0.05, and the perforation diameter D is 0.3mm, the influence of the depth D of the back cavity on the sound absorption coefficient is obtained, as shown in fig. 5c, wherein 6 curves are included, the curve 3a is the sound absorption coefficient curve corresponding to the depth D of the back cavity being 10mm, the curve 3b is the sound absorption coefficient curve corresponding to the depth D of the back cavity being 12mm, the curve 3c is the sound absorption coefficient curve corresponding to the depth D of the back cavity being 14mm, the curve 3D is the sound absorption coefficient curve corresponding to the depth D of the back cavity being 16mm, the curve 3e is the sound absorption coefficient curve corresponding to the depth D of the back cavity 116 being 18mm, and the curve 3f is the sound absorption coefficient curve corresponding to the depth D of the back cavity being 20 mm. As can be seen from fig. 5c, in the case that the other dimensional parameters are the same, the depth D of the back cavity is different, the maximum sound absorption coefficient is also different, and the corresponding effective sound absorption frequency band is also different.

It can be seen that, when at least one of the perforation ratio σ, the perforation diameter D, the depth D of the back cavity, and the plate thickness t of the perforated plate of the microperforated muffler is changed, the sound absorption coefficient is changed, and the effective sound absorption band is also changed, both from the calculation formula of the sound absorption coefficient and from the results of the simulation experiment.

Based on this, as shown in fig. 6a, the embodiment of the present application provides a noise reduction device 10, which may include a flow guiding component 30, a housing 40, a plurality of noise abatement structures 50 and a baffle 60, where each noise abatement structure 50 includes a perforated plate 115 and a back cavity 116 located on a first plate surface of the perforated plate 115. The first and second sound-deadening structures 51 and 52 of the plurality of sound-deadening structures 50 are different in size parameter, wherein the size parameter includes at least one of a plate thickness, a hole penetration rate, a hole penetration diameter of the perforated plate 115, and a depth of the back cavity 116, and the blade passing frequencies corresponding to the maximum sound absorption coefficients of the first and second sound-deadening structures 51 and 52 are different. The sound absorption coefficient curve corresponding to the sound attenuation structure 50 is generally parabolic, and in this embodiment, the sound absorption coefficient curve of the noise reduction device 10 includes a curve obtained by overlapping a parabolic sound absorption coefficient curve corresponding to the first sound attenuation structure 51 and a parabolic sound absorption coefficient curve corresponding to the second sound attenuation structure 52, so that when the airflow 23 in the flow guiding component 30 passes through the first sound attenuation structure 51 and the second sound attenuation structure 52 respectively, the effective sound absorption frequency band of the sound absorption coefficient curve obtained finally is wider, that is, the noise reduction device 10 can obtain a wider effective sound absorption frequency band.

The noise reduction device 10 of the embodiment of the application can be applied to vehicles, and can also be applied to other occasions where the fan 20 needs to be reduced in noise, the installation space is limited, and the noise frequency variation range is large, such as electronic equipment of notebook computers, tablet computers and the like. The vehicle further comprises a fan 20 in addition to the noise reduction device 10, and the noise reduction device 10 is fixed at an air outlet of the fan 20. As shown in fig. 6a, the fan 20 may be an axial fan 21, and as shown in fig. 6b, the fan 20 may be a centrifugal fan 22.

For convenience of description, as shown in fig. 6a, two directions may be defined, respectively, a first direction (X direction) indicating a flow direction of the air flow 23 flowing out of the fan 20 and a second direction (Y direction) perpendicular to the first direction.

Next, each component in the noise reduction device 10 of the embodiment of the present application will be described in detail.

As shown in fig. 6a, the flow guiding component 30 is fixed on the fan 20 and is located at the air outlet. The cross-sectional shape of the flow guiding member 30 taken along the plane perpendicular to the X-direction may be a quadrangle, and then the flow guiding member 30 includes four side plates 31, and the four side plates 31 are connected end to end in sequence and are surrounded into a closed shape. As shown in fig. 8, the flow guiding member 30 has a first surface 33 and a second surface 34 opposite to each other, wherein the first surface 33 faces the fan 20, the second surface 34 is far away from the fan 20, and the first surface 33 and the second surface 34 may be aligned in the X-direction and parallel to each other. The interior of the deflector 30 has a cavity 35. The first surface 33 has a first opening 331 and the second surface 34 has a second opening 341, both the first opening 331 and the second opening 341 being in communication with the cavity 35. In this way, the air flow 23 exiting the outlet of the fan 20 may enter the cavity 35 from the first opening 331 and then proceed and exit from the second opening 341. The cross-sectional area of the end of the air outlet of the fan 20 connected to the flow guiding member 30 is generally large, and thus, the cross-sectional area of the flow guiding member 30 taken along a plane perpendicular to the X-direction gradually decreases from the first surface 33 to the second surface 34. In one embodiment, a first side plate 311 of the four side plates 31 is perpendicular to the first surface 33, and an included angle between the second side plate 312 and the first surface 33 is an acute angle.

As shown in fig. 8, the flow guiding member 30 is provided with a first through hole 36, the first through hole 36 is provided on the first side plate 311, and the first through hole 36 communicates with the cavity 35, so that the air flow 23 entering the cavity 35 from the first opening 331 can flow through the first through hole 36 and enter the first through hole 36.

The material of the flow guide member 30 may be plastic, which may reduce the weight.

As shown in fig. 7, the housing 40 is secured to the flow directing member 30 and is at least partially external to the flow directing member 30, and in one embodiment, the housing 40 is entirely external to the flow directing member 30. The casing 40 includes a bottom wall 41 and a side wall 42 fixed on a side surface of the bottom wall 41 and enclosing a closed structure, the side wall 42 is fixed on the first side plate 311 of the flow guiding component 30, and the first through hole 36 is located in a projection range of the casing 40 on the first side plate 311, so when the air flow 23 in the cavity 35 flows out through the first through hole 36, the casing 40 can play a role of blocking the part of the air flow 23, thereby avoiding flow leakage and affecting performance of the fan 20.

As shown in fig. 7, the bottom wall 41 is stepped, and in one embodiment, the bottom wall 41 includes a plurality of bottom plates arranged along the X direction and sequentially connected, each of the bottom plates is parallel to each other and parallel to the first side plate 311, and the distance between each of the bottom plates and the first side plate 311 is different. For example, as shown in fig. 7, the bottom wall 41 includes a first bottom plate 411 and a second bottom plate 412, and a distance D1 between the first bottom plate 411 and the first side plate 311 is smaller than a distance D2 between the second bottom plate 412 and the first side plate 311.

As shown in fig. 7, in the present embodiment, the number of the sound deadening structures 50 may be two, and in other embodiments, the number of the sound deadening structures 50 may be three, four, or more. For convenience of description, the two sound attenuating structures 50 may be named as a first sound attenuating structure 51 and a second sound attenuating structure 52, respectively.

As shown in fig. 7, the first sound attenuating structure 51 includes a first perforated plate 511 and a first back cavity 512, and the first perforated plate 511 has a first plate 5112 and a second plate 5113 opposite to each other. The first perforated plate 511 is fixed to the first side plate 311 and covers a portion of the first through hole 36. The second plate 5113 faces the cavity 35 and the first plate 5112 faces away from the cavity 35. Thus, a first back cavity 512 may be formed between the first bottom plate 411, the side wall 42, and the first perforated plate 511 of the case 40. Since the first perforated plate 511 is fixed to the flow guiding member 30 and covers the first through hole 36, when the air flow 23 flows in the cavity 35, a part of the air flow 23 can enter the first back cavity 512 after passing through the plurality of perforations of the first perforated plate 511, and then flows out from the first back cavity 512 through the perforations of the first perforated plate 511, and in the process, the sound energy is converted into heat energy by multiple friction between the heat energy and the perforations to dissipate the heat energy so as to weaken the sound wave; in addition, during the flowing process of the air flow 23, air molecules in the air flow 23 vibrate, and the vibration is transmitted, so that pressure is generated by the vibration, and the first silencing structure 51 can form obstruction to the pressure, thereby achieving the purpose of noise reduction.

As shown in fig. 7, the second sound attenuating structure 52 includes a second perforated plate 521 and a second back cavity 522, and the second perforated plate 521 has a second plate surface 5113 and a second plate surface 5113 opposite to each other. The second perforated plate 521 is fixed to the second side plate 312 and covers another partial area of the first through hole 36. The second plate 5113 faces the cavity 35 and the second plate 5113 faces away from the cavity 35. In this way, a second back chamber 522 may be formed between the second bottom plate 412, the side wall 42, and the second perforated plate 521 of the housing 40. Since the second perforated plate 521 is fixed to the flow guiding member 30 and covers the first through hole 36, when the air flow 23 flows in the cavity 35, a part of the air flow 23 can enter the second back cavity 522 after passing through the plurality of perforations of the second perforated plate 521, and then flows out from the second back cavity 522 through the perforations of the second perforated plate 521, and in the process, the sound energy is converted into heat energy to be dissipated through multiple friction between the sound energy and the perforations, so as to weaken the sound wave; in addition, during the flowing process of the air flow 23, air molecules in the air flow 23 vibrate, and the vibration is transmitted to generate pressure, and the second silencing structure 52 can form obstruction to the pressure, so that the purpose of noise reduction is achieved.

In the present embodiment, since the noise reduction device 10 includes the first sound damping structure 51 and the second sound damping structure 52, the relative acoustic impedance of the noise reduction device 10 can be calculated according to the fourth expression:

Where Z represents the relative acoustic impedance of the noise reducer 10, S ₁ Represents the area of the first plate 5112 of the first perforated plate 511 of the first sound-deadening structure 51, S ₂ The area Z of the first plate 5112 of the second perforated plate 521 of the second muffler structure 52 ₁ Representing the relative acoustic impedance, Z, of the first sound attenuating structure 51 ₂ Representing the relative acoustic impedance, Z, of the second sound attenuating structure 52 ₁ And Z ₂ May be calculated according to the first expression.

As can be seen from the fourth expression, when two sound damping structures 50 are included in the noise reduction device 10, the area of the first plate 5112 of the first sound damping structure 51 and the area of the first plate 5112 of the second sound damping structure 52 both affect the relative acoustic impedance of the noise reduction device 10, thereby affecting the sound absorption coefficient of the noise reduction device 10. Therefore, in the present embodiment, the first sound attenuating structure 51 and the second sound attenuating structure 52 differ in dimensional parameters, wherein the dimensional parameters include: at least one of the plate thickness of the perforated plate, the perforation rate, the perforation diameter, the area of the first plate surface 5112 of the perforated plate, and the depth of the back cavity. In one embodiment, one of the dimensional parameters of the first sound attenuating structure 51 and the second sound attenuating structure 52 is different; in another embodiment, two of the dimensional parameters of the first sound attenuating structure 51 and the second sound attenuating structure 52 are different; in another embodiment, three of the dimensional parameters of the first sound attenuating structure 51 and the second sound attenuating structure 52 are different; in another embodiment, four of the dimensional parameters of the first sound attenuating structure 51 and the second sound attenuating structure 52 are different; in another embodiment, five of the dimensional parameters of the first sound attenuating structure 51 and the second sound attenuating structure 52 are different.

As can be seen from the above-described first expression, the relative acoustic impedance of the sound damping structure 50 can be calculated based on the blade passing frequency, the sound velocity in the air, the plate thickness of the microperforations, the perforation rate, the perforation diameter, and the depth of the back cavities, and therefore, when at least one of the plate thickness, the perforation rate, the perforation diameter, and the depth of the perforated plates in the first sound damping structure 51 and the second sound damping structure 52 is different, the relative acoustic impedances of the first sound damping structure 51 and the second sound damping structure 52 are different. As can be seen from the above-described third expression, when the area of the first plate surface 5112 of the first sound attenuating structure 51 and the area of the first plate surface 5112 of the second sound attenuating structure 52 are different, the relative acoustic impedance of the noise reducing device 10 is affected, and thus the effective sound absorption band of the noise reducing device 10 can be widened.

The first sound attenuating structure 51 and the second sound attenuating structure 52 are located in the same layer, and the first sound attenuating structure 51 and the second sound attenuating structure 52 are arranged side by side. In this embodiment, as shown in fig. 7, the first perforated plate 511 and the second perforated plate 521 are located on the same layer, and the first perforated plate 511 and the second perforated plate 521 are arranged side by side along the X direction, and the first plate 5112 of the first perforated plate 511 and the first plate 5112 of the second perforated plate 521 are flush, so that the air flow 23 flowing out from the air outlet of the fan 20 is subjected to the silencing treatment of each silencing structure 50, thereby increasing the number of perforations rubbed with the air flow 23, and further increasing the heat energy of the dissipated air flow 23, and further weakening the sound wave. In other embodiments, the alignment direction of the first perforated plate 511 and the second perforated plate 521 is the Y direction; when the number of the sound deadening structures 50 is three, four or more, the plurality of sound deadening structures 50 may be arranged in an array such as a rectangular array or a circular array.

In this embodiment, as shown in fig. 7, the plate thickness of the first perforated plate 511 is the same as the plate thickness of the second perforated plate 521, and since the first plate surface 5112 of the first perforated plate 511 is flush with the first plate surface 5112 of the second perforated plate 521, and since the bottom wall 41 is stepped as a whole, and the distances between the plurality of bottom plates included in the bottom wall 41 and the first side plate 311 are different, the depth D1 of the first back cavity 512 between the first perforated plate 511 and the first bottom plate 411 is different from the depth D2 of the second back cavity 522 between the second perforated plate 521 and the second bottom plate 412.

In one embodiment, the material of the first perforated plate 511, the material of the second perforated plate 521, and the material of the housing 40 may be the same as the material of the flow guiding member 30, so that the flow guiding member 30, the first perforated plate 511, and the side wall 42 of the housing 40 may be injection molded at one time, and then the bottom wall 41 of the housing 40 is fixed on the side wall 42 of the housing 40 by welding or screwing, thereby completing the manufacturing of the noise reducer 10. In another embodiment, the material of the first perforated plate 511 and the material of the second perforated plate 521 both comprise metal, and when the noise reduction device 10 is manufactured, the flow guiding member 30, the housing 40, the first perforated plate 511 and the second perforated plate 521 may be manufactured separately, and then the first perforated plate 511 and the second perforated plate 521 are fixed to the first side plate 311 of the flow guiding member 30 by welding or screwing, and the housing 40 is fixed to the first side plate 311, thereby manufacturing the noise reduction device 10. Because the heat conductivity of the metal is better, and the heat dissipation performance is better, after the air flow 23 in the flow guiding component 30 is converted into heat energy in the process of penetrating the perforation of the first perforation plate 511 and the perforation of the second perforation plate 521, the metal can well disperse the heat energy, so that the relative acoustic impedance of the sound damping structure 50 is further improved, and the noise reduction effect is further improved.

As shown in fig. 7, each of the first sound attenuating structure 51 and the second sound attenuating structure 52 includes a sound absorbing portion 53, the sound absorbing portion 53 is made of a sound absorbing material, and the sound absorbing material may be, for example, glass fiber or polyester fiber, and the sound absorbing portion 53 of the first sound attenuating structure 51 is located in the first back cavity 512, and the sound absorbing portion 53 of the second sound attenuating structure 52 is located in the second back cavity 522. In this way, when the air flow 23 in the cavity 35 of the flow guiding member 30 enters the first back cavity 512 and the second back cavity 522, the sound absorbing portion 53 can well form an obstruction to the pressure generated by the air flow 23, thereby further improving the noise reduction effect.

As shown in fig. 7, the baffle 60 is fixed to the first plate 5112 of the first sound attenuating structure 51 and/or the second sound attenuating structure 52. In this way, when the air flow 23 passes between the first sound attenuating structure 51 and the second sound attenuating structure 52, the baffle 60 can block the air flow 23 in the first sound attenuating structure 51, so that most of the air flow 23 entering the first sound attenuating structure 51 flows out of the first perforated plate 511 of the first sound attenuating structure 51 and then flows into the second sound attenuating structure 52 through the second perforated plate 521 of the second sound attenuating structure 52, but not directly flows from the first back cavity 512 to the second back cavity 522, thereby reducing the influence on the air flow 23 in the flow guiding component 30 and further reducing the influence on the performance of the fan 20.

As shown in fig. 7, in one possible implementation, the baffle 60 is fixed to the first plate surface 5112 of the first sound attenuating structure 51, and a dimension of the baffle 60 along the depth direction of the first back cavity 512 is the same as the depth of the first back cavity 512 of the first sound attenuating structure 51. In another possible implementation, the baffle 60 is fixed to the first plate 5112 of the second sound attenuating structure 52, and the dimension of the baffle 60 along the depth direction of the second back cavity 522 is the same as the depth of the second back cavity 522 of the second sound attenuating structure 52. In one possible implementation, the first portion of the baffle 60 is fixed to the first plate 5112 of the second muffler structure 52, and the first portion of the baffle 60 has a dimension along the depth direction of the second back cavity 522 that is the same as the depth of the second back cavity 522 of the second muffler structure 52; the second portion of the baffle 60 is fixed to the first plate 5112 of the second muffler structure 52, and the dimension of the second portion of the baffle 60 along the depth direction of the second back chamber 522 is the same as the depth of the second back chamber 522 of the second muffler structure 52. In this way, the dimension of the baffle 60 in the depth direction of the back cavity is the same as the depth of the back cavity in which it is located, so that the air flow 23 flowing between the first back cavity 512 of the first sound attenuating structure 51 and the second back cavity 522 of the second sound attenuating structure 52 can be well blocked, thereby further reducing the influence on the air flow 23 in the flow guiding member 30 and further reducing the influence on the performance of the fan 20.

Next, simulation experiments were performed on the microperforated muffler 11 of the related art shown in fig. 1 and the noise reduction device 10 shown in fig. 7, to obtain a sound absorption coefficient graph shown in fig. 4. As shown in fig. 4, a curve 4a is a sound absorption coefficient curve of the noise reduction device 10 of the embodiment shown in fig. 7, and a curve 4b is a sound absorption coefficient curve of the microperforated muffler 11 of the related art shown in fig. 1. The size parameters of the microperforated muffler 11 of the related art shown in fig. 1 are: the perforation diameter d was 0.6mm and the perforation ratio sigma was 0.03. The dimensional parameters of the noise reduction device 10 in the embodiment shown in fig. 7 are: area S of first plate 5112 of first muffler structure 51 ₁ 15mm of ² Diameter d of perforation ₁ 0.6mm, penetration rate sigma ₁ 0.03; area S of first plate 5112 of second muffler structure 52 ₂ 25mm of ² Diameter d of perforation ₂ 0.8mm, penetration rate sigma ₂ 0.08. As can be seen from fig. 4, the effective sound absorption band of the noise reduction device 10 shown in fig. 7 is wider than that of the microperforated muffler 11 of the related art.

In other embodiments, as shown in fig. 9, the difference from the noise reduction device 10 shown in fig. 7 is the arrangement of the first and second sound attenuation structures 51 and 52, the structure of the first sound attenuation structure 51 and the bottom wall 41 of the housing 40 in the noise reduction device 10. In the embodiment shown in fig. 7, the first sound damping structure 51 and the second sound damping structure 52 are arranged side by side in the X direction, and in the present embodiment, as shown in fig. 9, the first sound damping structure 51 and the second sound damping structure 52 are stacked. An included angle is formed between the stacking direction of the first sound attenuating structure 51 and the second sound attenuating structure 52 and the X direction, for example, in fig. 9, the stacking direction of the first sound attenuating structure 51 and the second sound attenuating structure 52 is the Y direction, which is perpendicular to the X direction. In this way, the air flow 23 flowing out of the air outlet of the fan 20 enters the cavity 35 of the flow guiding member 30 from the first opening 331 of the flow guiding member 30 and can flow out from the second opening 341. When the air flow 23 moves forward in the cavity 35, part of the air flow 23 passes through the first silencing structure 51, enters the first back cavity 512 of the first silencing structure 51 from the first perforated plate 511 of the first silencing structure 51, and flows out from the first perforated plate 511 of the first silencing structure 51 to weaken sound waves; in addition, the first and second sound attenuating structures 51 and 52 may form an obstruction to the pressure generated by the airflow 23 during the flow, so that the noise reducing effect may be further improved.

As shown in fig. 9, the first perforated plate 511 of the first sound damping structure 51 and the second perforated plate 521 of the second sound damping structure 52 are stacked with each other, and a gap is provided between the first perforated plate 511 and the second perforated plate 521. The first sound attenuating structure 51 is closer to the flow guiding member 30 than the second sound attenuating structure 52, a first back chamber 512 is formed between the first perforated plate 511, the side wall 42 of the housing 40, and the second perforated plate 521, and a second back chamber 522 is formed between the second perforated plate 521, the side wall 42 of the housing 40, and the bottom wall 41. Thus, when the air flow 23 flowing out from the air outlet of the fan 20 moves forward inside the cavity 35, and when the air flow 23 moves forward inside the cavity 35, part of the air flow 23 passes through the first silencing structure 51, enters the first back cavity 512 of the first silencing structure 51 from the first perforated plate 511 of the first silencing structure 51, and flows out from the first perforated plate 511 of the first silencing structure 51; in addition, the first and second sound attenuating structures 51 and 52 may form an obstruction to the pressure generated by the airflow 23 during the flow, so that the noise reducing effect may be further improved.

In the embodiment shown in fig. 7, the first sound attenuating structure 51 includes a first perforated plate 511, a first back cavity 512, and a sound absorbing portion 53, and in the present embodiment, as shown in fig. 9, the first sound attenuating structure 51 includes the first perforated plate 511 and the first back cavity 512 without the sound absorbing portion 53.

In the embodiment shown in fig. 7, the bottom wall 41 is stepped, and in this embodiment, as shown in fig. 9, the surface of the bottom wall 41 facing the flow guiding member 30 and the surface facing away from the flow guiding member 30 are both planar.

In the present embodiment, the first sound attenuating structure 51 and the second sound attenuating structure 52 are stacked in the Y direction, the sound absorbing portion 53 is disposed in the second back cavity 522, and the sound absorbing portion 53 is not disposed in the first back cavity 512; in other embodiments, when the number of the sound attenuation structures 50 is at least three, and at least three sound attenuation structures 50 are each stacked in the Y direction, the sound absorption portion 53 may be disposed in the back cavity of the sound attenuation structure 50 farthest from the flow guiding member 30.

In other embodiments, as shown in fig. 10, the difference between the embodiment shown in fig. 9 is the number of sound attenuating structures 50 and the arrangement of a plurality of sound attenuating structures 50. In the embodiment shown in fig. 9, the number of the sound deadening structures 50 is two, and the first sound deadening structure 51 and the second sound deadening structure 52 are stacked in the Y direction. In the present embodiment, as shown in fig. 10, the number of the sound damping structures 50 is four, and the four sound damping structures 50 are provided in two layers, and each layer of sound damping structure 50 includes two sound damping structures 50 therein. In this way, when the air flow 23 in the cavity 35 moves forward in the cavity 35, the pressure generated by the air flow 23 will sequentially pass through the noise reduction treatment of each layer of the noise reduction structure 50, thereby further improving the noise reduction effect. In other embodiments, the number of layers of the sound attenuating structures 50 may be three, four, or more, and each layer of sound attenuating structures 50 may include one sound attenuating structure 50 or may include a plurality of sound attenuating structures 50.

In other embodiments, as shown in fig. 11, the difference between the embodiment shown in fig. 9 is the number of sound attenuating structures 50 and the arrangement of a plurality of sound attenuating structures 50. In the embodiment shown in fig. 9, the number of the sound deadening structures 50 is two, and the two sound deadening structures 50 are arranged in a stacked manner in the Y direction, in this embodiment, as shown in fig. 11, the first partial sound deadening structure 50 includes a first sound deadening structure 51 and a second sound deadening structure 52, in which the first sound deadening structure 51 and the second sound deadening structure 52 are arranged side by side in the X direction, and in one embodiment, a first perforated plate 511 of the first sound deadening structure 51 and a second perforated plate 521 of the second sound deadening structure 52 are arranged side by side in the X direction; the second partial muffler structure 50 includes a third muffler structure 54 and a fourth muffler structure 55, wherein the third muffler structure 54 and the fourth muffler structure 55 are stacked in the Y direction, and in one embodiment, the third perforated plate 541 of the third muffler structure 54 and the fourth perforated plate 551 of the fourth muffler structure 55 are arranged side by side in the Y direction, and an included angle is formed between the second perforated plate 521 and the third perforated plate 541, for example, the included angle may be 90 °. In this way, when the air flow 23 flowing out from the air outlet of the fan 20 moves forward in the cavity 35, a part of the air flow 23 passes through the first silencing structure 51, a part of the air flow 23 passes through the second silencing structure 52, and the first silencing structure 51 and the second silencing structure 52 respectively reduce noise of the two parts of the air flow 23, so that the noise reduction effect can be further improved.

In other embodiments, as shown in FIG. 12, the difference from the embodiment shown in FIG. 7 is that the barrier 60 is eliminated on the basis of FIG. 7. That is, in the present embodiment, as shown in fig. 12, the noise reducing device 10 may include the flow guide member 30, the housing 40, the first sound attenuating structure 51, and the second sound attenuating structure 52.

In other embodiments, as shown in fig. 13, the difference from the embodiment shown in fig. 7 is the relationship between the plate thickness of the first perforated plate 511 and the plate thickness of the second perforated plate 521 and the structure of the bottom wall 41 of the housing 40. In the embodiment shown in fig. 7, the plate thickness of the first perforated plate 511 is the same as the plate thickness of the second perforated plate 521, and in the present embodiment, as shown in fig. 13, the plate thickness of the first perforated plate 511 is different from the plate thickness of the second perforated plate 521, and since the second plate 5113 of the first perforated plate 511 is flush with the second plate 5113 of the second perforated plate 521, the first plate 5112 of the first perforated plate 511 is not flush with the first plate 5112 of the second perforated plate 521. Since the back cavity of each muffler structure 50 is located on the first plate surface 5112 of the perforated plate, the difference in depth between the first back cavity 512 and the second back cavity 522 can be achieved by the difference in plate thickness of the first perforated plate 511 and the second perforated plate 521, which is easy to achieve. In addition, since the second plate 5113 of the first perforated plate 511 and the second plate 5113 of the second perforated plate 521 are flush, the influence on the air flow 23 in the cavity 35 caused by the non-flush second plate 5113 of each perforated plate can be reduced, thereby affecting the performance of the fan 20.

In the embodiment shown in fig. 7, the bottom wall 41 of the housing 40 is stepped, and in this embodiment, as shown in fig. 13, the surface of the bottom wall 41 facing the flow guiding member 30 and the surface facing away from the flow guiding member 30 are both planar.

In other embodiments, as shown in fig. 14, the difference from the embodiment shown in fig. 7 is the relationship between the plate thickness of the first perforated plate 511 and the plate thickness of the second perforated plate 521. In the embodiment shown in fig. 7, the plate thickness of the first perforated plate 511 is the same as the plate thickness of the second perforated plate 521, and in the present embodiment, as shown in fig. 14, the plate thickness of the first perforated plate 511 is different from the plate thickness of the second perforated plate 521, and since the second plate 5113 of the first perforated plate 511 is flush with the second plate 5113 of the second perforated plate 521, the first plate 5112 of the first perforated plate 511 is not flush with the first plate 5112 of the second perforated plate 521. Since the distance between the first bottom plate 411 and the first side plate 311 is smaller than the distance between the second bottom plate 412 and the second side plate 312, the depth of the first back cavity 512 is smaller than the depth of the second back cavity 522.

The embodiments of the present application have been described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those of ordinary skill in the art without departing from the spirit of the present application and the scope of the claims, which are also within the protection of the present application.

Claims

1. A noise reduction device, comprising:

the flow guiding component is internally provided with a cavity, and is provided with a first through hole which is communicated with the cavity;

the shell is fixed on the flow guiding component and at least partially positioned outside the flow guiding component;

the device comprises a plurality of silencing structures, wherein the silencing structures are fixed on the flow guide part and cover the first through holes, each silencing structure comprises a perforated plate and a back cavity positioned on a first plate surface of the perforated plate, at least one of the back cavities of the silencing structures is formed by the shell and the perforated plate, and the size parameters of the first silencing structure and the second silencing structure in the silencing structures are different.

2. The noise reducer of claim 1, wherein the dimensional parameters comprise: at least one of a plate thickness of the perforated plate, a perforation rate, a perforation diameter, an area of the first plate surface, and a depth of the back cavity.

3. A noise reducer according to claim 1 or 2, wherein the dimensional parameters of each of the sound attenuating structures are different.

4. A noise reducer according to any one of claims 1-3, wherein the first sound attenuating structure and the second sound attenuating structure are adjacent;

The noise reduction device further comprises a baffle, and the baffle is fixed on the first plate surface of the first noise elimination structure and/or the second noise elimination structure.

5. The noise reduction device according to claim 4, wherein the baffle is fixed to the first plate surface of the first sound attenuation structure, and a dimension of the baffle in a depth direction of the back cavity is the same as a depth of the back cavity of the first sound attenuation structure;

or, the baffle is fixed on the first plate surface of the second silencing structure, and the dimension of the baffle along the depth direction of the back cavity is the same as the depth of the back cavity of the second silencing structure;

or, the first part of the baffle is fixed on the first plate surface of the second silencing structure, and the dimension of the first part of the baffle along the depth direction of the back cavity is the same as the depth of the back cavity of the second silencing structure; the second part of the baffle is fixed on the first plate surface of the second silencing structure, and the dimension of the second part of the baffle along the depth direction of the back cavity is the same as the depth of the back cavity of the second silencing structure.

6. The noise reduction device of any one of claims 1-5, wherein the first noise abatement structure and the second noise abatement structure are located in a same layer, and wherein a projection of the perforated plate of the first noise abatement structure onto the flow guiding member and a projection of the perforated plate of the second noise abatement structure onto the flow guiding member each cover a partial region of the first through hole.

7. The noise reducer of any of claims 1-6, wherein the flow directing member has first and second openings opposite and aligned in a first direction, each of the first and second openings being in communication with the cavity;

the first silencing structure and the second silencing structure are arranged side by side, and the arrangement direction is the first direction.

8. The noise reducer of any of claims 1-5, wherein the flow directing member has first and second openings opposite and aligned in a first direction, each of the first and second openings being in communication with the cavity;

the first silencing structure and the second silencing structure are arranged in a stacked mode, and an included angle is formed between the stacking direction and the first direction.

9. The noise reducing device according to claim 8, wherein the perforated plates of the first noise reducing structure and the perforated plates of the second noise reducing structure are stacked with a gap between each two adjacent perforated plates.

10. The noise reducer of claim 8, wherein the perforated plates of the first noise abatement structure and the perforated plates of the second noise abatement structure are arranged side by side with an included angle between an arrangement direction and the first direction.

11. The noise reducer of any of claims 1-5 or 8-10, wherein the plurality of sound attenuating structures are provided in multiple layers, and at least one of the sound attenuating structures comprises at least one of the sound attenuating structures, and at least one of the sound attenuating structures comprises at least two of the sound attenuating structures.

12. A noise reduction device as defined in any one of claims 1-11, wherein a first part of said sound attenuating structures are arranged side by side and a second part of said sound attenuating structures are arranged in a stack.

13. The noise reducer of claim 12, wherein said perforated plate of said first portion of said sound attenuating structure is angled with respect to said perforated plate of said second portion of said sound attenuating structure.

14. The noise reduction device according to any one of claims 7, 8, or 10, wherein a plate thickness of each of the perforated plates arranged in the first direction is different, and a second plate surface of each of the perforated plates covering the first through holes is flush, the second plate surface being opposite to the first plate surface.

15. The noise reducer of any one of claims 7, 8, 10, or 14, wherein the housing includes a bottom wall and a side wall fixed to one side of the bottom wall, the side wall is fixed to the flow guiding member, the bottom wall is stepped, and a distance between the bottom wall and each of the perforated plates arranged in the first direction is different.

16. The noise reducer of any of claims 1-15, wherein the material of the perforated plate of at least one of the sound attenuating structures comprises metal.

17. The noise reduction device of any one of claims 1-16, wherein at least one of the sound attenuating structures further comprises a sound absorbing portion, the sound absorbing portion being of a sound absorbing material, the sound absorbing portion being located within the back cavity.

18. A vehicle comprising a fan and a noise reduction device according to any one of claims 1 to 17, wherein a flow directing element of the noise reduction device is secured to the fan.