Air permeability evaluation device

Abstract

The utility model discloses a kind of air permeability evaluation devices, the device includes buoy cylinder, fabric fixing frame, buoy and blow assembly. Buoy cylinder is transparent cylinder, both ends are open and cross-sectional area increases from small end to big end, cylinder wall is equipped with axial scale, and radial sample slot is equipped near small end. Fabric fixing frame is used to fix and tension fabric sample, can be inserted sample slot to form sealed connection, and its coverage area completely shields airflow passage below buoy cylinder. Buoy is placed in cylinder, and its mark point is aligned small end reference scale when initial position. Blow assembly air outlet is communicated with small end of buoy cylinder, and provides axial adjustable airflow. When testing, first adjust air volume to make buoy rise to big end reference scale;After inserting fabric sample, airflow is blocked by sample, and buoy height drops, and by comparing buoy actual height with reference height, directly quantifying fabric air permeability-buoy height is higher, indicating that air permeability is more optimal. The device structure is simple, convenient to operate, and realizes the visualization of air permeability fast detection.

Description

Technical Field

[0001] This utility model relates to the field of materials science and technology, and in particular to an air permeability evaluation device. Background Technology

[0002] Sound-absorbing materials are widely used in noise control in buildings, transportation, and industrial equipment. However, when these materials are directly exposed to the environment, they are susceptible to factors such as humidity, dust, and mechanical impact, leading to structural aging, performance degradation, and even environmental pollution. To improve the durability of these materials, a protective coating is commonly used in engineering projects. Fiberglass cloth or other functional fabrics are typically chosen as the protective layer. This layer primarily provides physical protection and does not possess significant acoustic properties itself.

[0003] Engineering practice has shown that the air permeability of the facing fabric significantly affects the acoustic performance of the encased sound-absorbing material. When the fabric has good air permeability, sound waves can effectively penetrate the facing layer and enter the internal structure of the sound-absorbing material, resulting in minimal attenuation of the sound absorption coefficient. Conversely, if the air permeability is poor, sound wave penetration is hindered, leading to a significant decrease in overall sound absorption performance. This phenomenon stems from the energy dissipation mechanism of sound waves in porous materials. The facing layer essentially acts as an acoustic impedance matching interface, and its air permeability directly determines the transmission efficiency of sound waves. Therefore, in order to predict the severity of the impact of the facing layer on the performance of the sound-absorbing material, it is urgent to develop a device for evaluating the air permeability of the facing fabric. Utility Model Content

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides an air permeability evaluation device, aiming to solve the problem in the prior art that it is impossible to predict the degree of influence of the protective layer on the performance of the sound-absorbing material.

[0005] This utility model provides an air permeability evaluation device, comprising:

[0006] A buoy tube, the buoy tube being made of transparent material, the cross-sectional area of ​​the buoy tube gradually increasing along the axial direction, both ends of the buoy tube being open, the outer side of the buoy tube being provided with graduations along its axial direction, and a sample slot extending radially along the buoy tube being provided near the small end of the buoy tube.

[0007] A fabric holder is used to fix and tension a fabric sample, and the fabric holder is used to insert into and seal with the sample slot. The axial projection of the inner side of the buoy tube located below the fabric sample is located within the coverage area of ​​the fabric sample.

[0008] A buoy, wherein the buoy is disposed inside the buoy tube, and when the buoy is in its initial position, the marked point of the buoy is aligned with the scale near the small end of the buoy tube;

[0009] A blower assembly, wherein the air outlet of the blower assembly is connected to the small end of the buoy tube, and the blower assembly is used to provide an axially adjustable airflow into the buoy tube.

[0010] According to the air permeability evaluation device provided by this utility model, the blowing assembly includes an air supply device and an air volume adjustment device. The air outlet of the air supply device is connected to the small end of the buoy tube. The air volume adjustment device is used to adjust the ventilation cross-sectional area of ​​the small end of the buoy tube or to adjust the air volume of the air supply device.

[0011] The air permeability evaluation device provided by this utility model also includes an anemometer, the detection end of which is located inside the small end of the buoy tube.

[0012] According to the air permeability evaluation device provided by this utility model, the air supply device includes at least a fan or blower driven by a motor.

[0013] According to the air permeability evaluation device provided by this utility model, the air volume adjustment device includes a speed adjustment device for adjusting the speed of the motor.

[0014] According to the air permeability evaluation device provided by this utility model, the air volume adjustment device includes a baffle plate disposed at the small end of the buoy cylinder, the baffle plate is provided with ventilation holes, and the opening degree of the ventilation holes is adjustable.

[0015] According to the air permeability evaluation device provided by this utility model, the sample slot is an annular groove, the annular groove includes a closed section and an open section, the central angle of the closed section is m degrees, and the inner diameter of the closed section is larger than the inner diameter of the buoy tube at the location, the central angle of the open section is 360-m degrees, and the open section connects the inner and outer sides of the buoy tube, wherein m≤180 degrees.

[0016] According to the air permeability evaluation device provided by this utility model, the fabric fixing frame includes an upper air permeable clip and a lower air permeable clip, which are detachably connected. The upper air permeable clip and the lower air permeable clip are used to clamp the two sides of the fabric sample. The thickness of the upper air permeable clip and the lower air permeable clip is equal to the thickness of the sample slot. The outer diameter of the upper air permeable clip and the lower air permeable clip is greater than the inner diameter of the buoy tube at the sample slot location, and less than or equal to the inner diameter of the sample slot.

[0017] The air permeability evaluation device provided by this utility model also includes a base, the interior of which is hollow, the air blowing assembly is disposed inside the base, and the base is provided with an air inlet and an air outlet, the air outlet being disposed at the top of the base, the small end of the buoy tube communicating with the air outlet at the top of the base, and the air outlet end of the air blowing assembly communicating with the air outlet of the base.

[0018] According to the air permeability evaluation device provided by this utility model, the buoy is at least a cone or a sphere, and when the buoy is a cone, the tip of the cone faces the small end of the buoy tube.

[0019] This utility model has the following advantages due to the adoption of the above technical solution:

[0020] The air permeability evaluation device provided by this utility model includes a buoy tube, a fabric holder, a buoy, and a blowing assembly. The buoy tube is made of transparent material, and its cross-sectional area gradually increases along its axial direction. Both ends of the buoy tube are open, and graduations are provided on its outer side along its axial direction. A sample slot extending radially from the smaller end of the buoy tube is also provided. The fabric holder is used to fix and tension the fabric sample, and it is used to insert into and seal with the sample slot. The axial projection of the inner side of the buoy tube below the fabric sample is located within the coverage area of ​​the fabric sample. The buoy is placed inside the buoy tube, and when the buoy is in its initial position, the marked point of the buoy is aligned with the graduations near the smaller end of the buoy tube. The air outlet of the blowing assembly is connected to the smaller end of the buoy tube, and the blowing assembly is used to provide an axially adjustable airflow into the buoy tube. Before testing, the airflow assembly is first adjusted to regulate the air volume entering the buoy tube. The airflow is adjusted so that the buoy rises to the position where the marked point aligns with the scale near the large end of the buoy tube. Then, the fabric sample is fixed to the fabric holder, and the holder with the fabric sample is inserted into the sample slot. The airflow passing through the fabric sample is affected by the fabric's permeability. Different fabric samples have different airflow resistance rates, therefore, the airflow after passing through the fabric sample will vary, ultimately reflected in the buoy's rising height. The higher the buoy rises, the better the permeability of the current fabric sample, and vice versa. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1This is a schematic diagram of the structure of an air permeability evaluation device provided in an embodiment of the present invention;

[0023] Figure 2 This is a top view of a sample slot provided in an embodiment of the present invention;

[0024] Figure 3 This is a top view of a fabric fixing frame provided in an embodiment of the present invention;

[0025] Figure 4 This is a top view of a windbreak provided in one embodiment of the present invention.

[0026] Figure label:

[0027] 100: Buoy tube; 110: Scale; 120: Sample slot; 200: Buoy; 300: Fan; 400: Wind deflector; 410: Ventilation hole; 500: Anemometer; 600: Fabric holder; 700: Base; 710: Air inlet. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0029] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0032] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0033] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0034] The air permeability evaluation device provided by this utility model includes a buoy tube, a fabric holder, a buoy, and a blowing assembly. The buoy tube is made of transparent material, and its cross-sectional area gradually increases along its axial direction. Both ends of the buoy tube are open, and graduations are provided on its outer side along its axial direction. A sample slot extending radially from the smaller end of the buoy tube is also provided. The fabric holder is used to fix and tension the fabric sample, and it is used to insert into and seal with the sample slot. The axial projection of the inner side of the buoy tube below the fabric sample is located within the coverage area of ​​the fabric sample. The buoy is placed inside the buoy tube, and when the buoy is in its initial position, the marked point of the buoy is aligned with the graduations near the smaller end of the buoy tube. The air outlet of the blowing assembly is connected to the smaller end of the buoy tube, and the blowing assembly is used to provide an axially adjustable airflow into the buoy tube. Before testing, the airflow assembly is first adjusted to regulate the air volume entering the buoy tube. The airflow is adjusted so that the buoy rises to the position where the marked point aligns with the scale near the large end of the buoy tube. Then, the fabric sample is fixed to the fabric holder, and the holder with the fabric sample is inserted into the sample slot. The airflow passing through the fabric sample is affected by the fabric's permeability. Different fabric samples have different airflow resistance rates, therefore, the airflow after passing through the fabric sample will vary, ultimately reflected in the buoy's rising height. The higher the buoy rises, the better the permeability of the current fabric sample, and vice versa.

[0035] The following is combined Figures 1 to 4 This invention describes the air permeability evaluation device.

[0036] This invention provides an air permeability evaluation device, mainly used to evaluate the air permeability of fabric samples. The air permeability evaluation device includes a buoy cylinder 100, a fabric fixing frame 600, a buoy 200, and a blowing assembly.

[0037] The buoy tube 100 can be made of transparent materials such as transparent glass or transparent plastic. Along the axial direction of the buoy tube 100, the cross-sectional area of ​​the buoy tube 100 gradually increases. For example, it can be a conical tube structure with open ends. When in use, the small end of the buoy tube 100 faces down and the large end faces up.

[0038] The outer side of the buoy tube 100 is provided with a scale 110. The scale 110 can be set along the axial direction of the buoy tube 100, and the value corresponding to the scale 110 gradually increases from the small end to the large end. For example, the scale value of the scale 110 near the small end of the buoy tube 100, or near the bottom of the buoy tube 100, is 0, and the scale value of the scale 110 near the large end of the buoy tube 100, or near the top of the buoy tube 100, can be 100%. The intermediate scales 110 can include 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90%.

[0039] A sample slot 120 is provided near the small end of the buoy tube 100, or in other words, a sample slot 120 is provided near the bottom of the buoy tube 100. A fabric sample can be installed in the sample slot 120 to separate the bottom and top spaces of the sample slot 120.

[0040] The fabric holder 600 is used to fix and tension the fabric sample. The fabric holder 600 is inserted into the sample slot 120. After connection, the fabric holder 600 and the sample slot 120 are sealed together to prevent gaps from forming between them, which could lead to air leakage and affect the permeability evaluation results. The axial projection of the inner side of the buoy cylinder 100 located below the fabric sample lies within the coverage area of ​​the fabric sample.

[0041] Specifically, the fabric sample is tensioned on the fabric holder 600 and then inserted into the sample slot 120 along with the fabric holder 600. Since the axial projection of the inner side of the float tube 100 located below the fabric sample is within the coverage area of ​​the fabric sample, after insertion, the fabric sample blocks the two spaces above and below the fabric sample. When the airflow enters the space above the fabric sample from below, it must pass entirely through the fabric sample.

[0042] The buoy 200 is set inside the buoy tube 100. When the buoy 200 is in the initial position, that is, when there is no airflow through the buoy tube 100, the mark point of the buoy 200 is aligned with the scale 110 near the small end of the buoy tube 100, that is, aligned with the scale 110 with the scale value of 0.

[0043] The air outlet of the blowing assembly is connected to the small end of the buoy tube 100. The blowing assembly is used to blow air along the axial direction of the buoy tube 100, that is, to blow air upward from the bottom of the buoy tube 100. The air volume of the blowing assembly is adjustable.

[0044] The working principle of the air permeability evaluation device provided in this embodiment is as follows:

[0045] The cross-sectional area of ​​the buoy tube 100 gradually increases from bottom to top. When the airflow flows from bottom to top, the annular flow area between the top of the buoy 200 and the buoy tube 100 is greater than the annular flow area between the bottom of the buoy 200 and the buoy tube 100, resulting in a pressure difference between the upper and lower ends of the buoy 200. This pressure difference forms the upward thrust of the buoy 200. When the upward thrust on the buoy 200 is greater than the weight of the buoy 200 immersed in the airflow, the buoy 200 rises. As the buoy 200 continues to rise, the annular flow area also increases. The larger the annular flow area, the lower the gas velocity through the annular flow surface, and the smaller the pressure difference between the upper and lower ends of the buoy 200. The thrust acting on the buoy 200 also decreases until the upward thrust equals the weight of the buoy 200 immersed in the air, at which point the buoy 200 stabilizes at a certain height.

[0046] The operation process of the air permeability evaluation device provided in this embodiment is as follows:

[0047] First, turn on the blower assembly and adjust it to change the airflow into the buoy tube 100 until the airflow is adjusted so that the buoy 200 floats stably at the position where the marked point on the buoy 200 is aligned with the 100% scale 110 in the horizontal direction.

[0048] Then, the fabric sample to be evaluated is fixed onto the fabric holder 600, the fabric sample is tensioned on the fabric holder 600, and then the fabric holder 600 is inserted into the sample slot 120. At this time, the airflow must pass through the fabric sample when it flows from bottom to top.

[0049] When the airflow located below the fabric sample passes through the fabric sample, it is affected by the air permeability of the fabric sample. Part of the airflow is blocked, while part of the airflow passes through the fabric sample and provides an upward thrust for the float 200. When the position of the float 200 is stable, the scale value corresponding to the scale 110 of the float 200 can be read to know the current air permeability of the fabric sample.

[0050] It should be noted that fabric samples with different air permeability have different effects on airflow obstruction. The less breathable the fabric sample, the stronger the obstruction effect on airflow. Consequently, less airflow passes through the fabric sample and continues to move upward, resulting in a smaller rise height of buoy 200 and a smaller scale value of 110. Conversely, the more breathable the fabric sample, the larger the obstruction effect.

[0051] In some embodiments, the blowing assembly includes an air supply device and an air volume regulating device. The air outlet of the air supply device is connected to the small end of the buoy cylinder 100, and the air volume regulating device is used to adjust the ventilation cross-sectional area of ​​the small end of the buoy cylinder 100 or to adjust the air volume of the air supply device.

[0052] Specifically, the blowing assembly includes an air supply device and an air volume regulating device. The air supply device is used to supply air to the buoy cylinder 100 from bottom to top. The air volume regulating device can directly control the air volume of the air supply device, changing the air volume delivered from the source. It can also adjust the flow cross-sectional area at the connection between the bottom end of the buoy cylinder 100 and the air supply device, thereby changing the air volume entering the buoy cylinder 100 by changing the flow cross-sectional area.

[0053] In some embodiments, the air supply device may be a fan 300 driven by an electric motor, or it may be a blower driven by an electric motor.

[0054] In some embodiments, the airflow regulating device may include a speed regulating device for adjusting the motor speed, such as a motor speed controller. By changing the motor speed, the speed of the fan 300 or blower is changed, thereby changing the airflow.

[0055] Alternatively, a wind deflector 400 can be provided at the small end of the buoy cylinder 100. The wind deflector 400 may include two stacked wind deflectors 400 rotatably connected, with the rotation axis extending along the axial direction of the wind deflector 400. Multiple pairs of ventilation holes 410 are provided opposite to each other on the two wind deflectors 400. By rotating the relative angle of the two wind deflectors 400, the opening of the ventilation holes 410 on the wind deflector 400 can be adjusted, thereby adjusting the airflow after passing through the wind deflector 400.

[0056] The bottom wind deflector 400 can be fixed inside the buoy tube 100. The outer circumference of the top wind deflector 400 can be provided with a handle that extends radially outward. The handle extends to the outside of the buoy tube 100. An arc-shaped groove can be provided at the position corresponding to the buoy tube 100. The handle can slide in the arc-shaped groove to adjust the angle of the wind deflector 400, thereby changing the opening of the ventilation hole 410.

[0057] In some embodiments, the air permeability evaluation device further includes an anemometer 500, the detection end of which is located inside the small end of the float tube 100, specifically in the space below the sample slot 120.

[0058] During use, the airflow of the blower assembly can be adjusted. When the float 200 floats stably and the marked point on the float 200 is aligned horizontally with the 100% scale 110, record the wind speed value displayed on the anemometer 500 at this time. When installing the fabric sample, the blower assembly can be turned off. After the fabric sample is installed, turn on the blower assembly and adjust the airflow of the blower assembly to the recorded wind speed value.

[0059] In some embodiments, the sample slot 120 may include an annular groove, which includes a closed section and an open section. The central angle of the closed section is m degrees, and the inner diameter of the closed section is larger than the inner diameter of the buoy tube 100 at the location. The central angle of the open section is 360-m degrees, and the open section connects the inner and outer sides of the buoy tube 100, wherein m ≤ 180 degrees.

[0060] For example, the open section of the sample slot 120 opens to the right, and the central angle of the closed section is less than or equal to 180 degrees. This embodiment is illustrated with the example of the central angle of the closed section being 180 degrees. The corresponding central angle of the open section is also 180 degrees.

[0061] The sample slot 120 can be understood as an annular groove set on the inner side wall of the buoy tube 100. The right half of the annular groove extends radially outward through the buoy tube 100 to allow the fabric holder 600 to enter the sample slot 120.

[0062] It should be noted that if the central angle of the open section is less than 180 degrees, it will limit the maximum width of the fabric holder 600, or rather, limit the outer diameter of the fabric holder 600. The maximum width or outer diameter of the fabric holder 600 can only be set to the maximum width of the open section. In this case, after the fabric holder 600 is inserted, a gap will appear between the fabric holder 600 and the maximum width of the annular groove, resulting in air leakage.

[0063] In some embodiments, the fabric holder 600 includes an upper breathable clip and a lower breathable clip, which are detachably connected so that the fabric sample can be clamped between the upper and lower breathable clips, and the fabric sample can also be replaced.

[0064] The total thickness of the upper and lower venting clips can be equal to the thickness of the annular groove, allowing them to be clamped together within the groove for a seal. The upper and lower venting clips can be annular or circular with vent holes. Whether annular or circular, their outer diameter is greater than the inner diameter of the buoy cylinder 100 at the location of the annular groove, and less than or equal to the inner diameter of the annular groove.

[0065] It should be noted that the shapes of the upper and lower breathable clips only need to be circular at the position corresponding to the closed section, while the part corresponding to the open section can be of any shape, as long as it ensures a sealed connection with the open section. For example, the part corresponding to the open section can be rectangular.

[0066] In some embodiments, the air permeability evaluation device further includes a base 700, which is hollow inside. An air outlet can be provided at the top center of the base 700, and air inlets 710 can be provided on other sides of the base 700. A blowing assembly is disposed inside the base 700, and its air outlet end communicates with the air outlet. The small end of the buoy tube 100 is connected to the top end of the base 700 and communicates with the air outlet.

[0067] In some embodiments, the buoy 200 described above can be a cone or a sphere. When the buoy 200 is a cone, the tip of the cone is positioned downwards.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An air permeability evaluation device, characterized in that, include: A buoy tube (100) is made of transparent material. The cross-sectional area of ​​the buoy tube (100) gradually increases along the axial direction of the buoy tube (100). Both ends of the buoy tube (100) are open. A scale (110) is provided on the outer side of the buoy tube (100) along its axial direction. A sample slot (120) extending radially along the buoy tube (100) is also provided near the small end of the buoy tube (100). A fabric holder (600) is used to fix and tension a fabric sample, and the fabric holder (600) is used to insert into the sample slot (120) and be sealed to the sample slot (120). The axial projection of the inner side of the float tube (100) located below the fabric sample is located within the coverage area of ​​the fabric sample. A buoy is disposed inside the buoy tube (100), and when the buoy is in its initial position, the mark point of the buoy is aligned with the scale (110) near the small end of the buoy tube (100); A blower assembly, the air outlet of which is connected to the small end of the buoy tube (100), is used to provide an axially adjustable airflow into the buoy tube (100).

2. The air permeability evaluation device according to claim 1, characterized in that, The blowing assembly includes an air supply device and an air volume regulating device. The air outlet of the air supply device is connected to the small end of the buoy tube (100). The air volume regulating device is used to adjust the ventilation cross-sectional area of ​​the small end of the buoy tube (100) or to adjust the air volume of the air supply device.

3. The air permeability evaluation device according to claim 2, characterized in that, It also includes an anemometer (500), the detection end of which is located inside the small end of the buoy tube (100).

4. The air permeability evaluation device according to claim 3, characterized in that, The air supply device includes at least a fan (300) or blower driven by an electric motor.

5. The air permeability evaluation device according to claim 4, characterized in that, The air volume regulating device includes a speed regulating device for adjusting the speed of the motor.

6. The air permeability evaluation device according to claim 4, characterized in that, The air volume regulating device includes a baffle plate (400) disposed at the small end of the buoy cylinder (100), the baffle plate (400) being provided with a ventilation hole (410), and the opening degree of the ventilation hole (410) being adjustable.

7. The air permeability evaluation device according to claim 1, characterized in that, The sample slot (120) is an annular groove, which includes a closed section and an open section. The central angle of the closed section is m degrees, and the inner diameter of the closed section is larger than the inner diameter of the buoy tube (100) at the location. The central angle of the open section is 360-m degrees, and the open section connects the inner and outer sides of the buoy tube (100), wherein m ≤ 180 degrees.

8. The air permeability evaluation device according to claim 1, characterized in that, The fabric holder (600) includes an upper breathable clip and a lower breathable clip, which are detachably connected. The upper and lower breathable clips are used to clamp the two sides of the fabric sample. The thickness of the upper and lower breathable clips is equal to the thickness of the sample slot (120). The outer diameter of the upper and lower breathable clips is greater than the inner diameter of the buoy tube (100) at the location of the sample slot (120), and less than or equal to the inner diameter of the sample slot (120).

9. The air permeability evaluation device according to claim 1, characterized in that, It also includes a base (700), the interior of which is hollow, the blower assembly is disposed inside the base (700), and the base (700) is provided with an air inlet (710) and an air outlet. The air outlet is disposed at the top of the base (700), the small end of the buoy tube (100) is connected to the air outlet at the top of the base (700), and the air outlet end of the blower assembly is connected to the air outlet of the base (700).

10. The air permeability evaluation device according to claim 1, characterized in that, The buoy is at least a cone or a sphere, and when the buoy is a cone, the tip of the cone faces the small end of the buoy tube (100).

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