Diffusion member and clean booth

Abstract

To provide a diffusion member which can uniform air flow within a clean booth and can suppress upflow.SOLUTION: A diffusion member disposed in an air outlet of a fan filter unit has truncated quadrangular pyramid shape. An upper bottom surface and a lower bottom surface of the truncated quadrangular pyramid are rectangle. The upper bottom surface is opened and is made of a fabric or a resin sheet having a through hole.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a diffusion member attached to a fan filter unit and a clean booth. [Background technology]

[0002] A clean booth is a facility that provides a cleaner space more easily and at a lower cost than a clean room. Clean booths are used to achieve localized cleanliness in factories and research facilities, as well as to achieve high levels of cleanliness within clean rooms. A known clean booth configuration, for example, is one in which a fan filter unit is installed on the ceiling, clean air is supplied from the fan filter unit, and the air, along with dust, is exhausted through a gap below the clean booth. Dust inside the clean booth is diluted by the clean air and then exhausted.

[0003] BACKGROUND ART Conventionally, in fan filter units used in clean rooms and clean booths, a metal punching plate is provided at the bottom of the fan filter unit in order to rectify the flow (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-167722 [Patent Document 2] Japanese Utility Model Application Publication No. 6-3427 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, the cleaning mechanism of clean booths is dilution, so there are not many reports on the verification and process of rectification in clean booths.

[0006] The present disclosure has been made in consideration of the above-described situation, and aims to provide a diffusion member that is attached to a fan filter unit and can equalize the airflow within a clean booth, suppress upflow, and rectify the airflow. [Means for solving the problem]

[0007] As a result of intensive research to solve the above-mentioned problems, the inventors of the present disclosure focused on the shape of the diffusion member and discovered that the generation of turbulence can be suppressed when the diffusion member has the shape of a truncated quadrangular pyramid.

[0008] One embodiment of the present disclosure provides a diffusion member that is placed at the air outlet of a fan filter unit, the diffusion member having the shape of a quadrangular pyramid, the upper and lower base surfaces of the quadrangular pyramid being rectangular, the upper base surface being open, and the diffusion member being a cloth or a resin sheet having through holes.

[0009] Another embodiment of the present disclosure provides a clean booth having a ceiling portion, a wall portion, a fan filter unit arranged on the ceiling portion, and the above-mentioned diffusion member arranged at the air outlet of the fan filter unit. [Effects of the Invention]

[0010] The present disclosure has an advantage of being able to provide a diffusion member that can create a rectified airflow in a diffusion member that is attached to a fan filter unit. [Brief explanation of the drawings]

[0011] [Figure 1] 1A and 1B are schematic plan and cross-sectional views illustrating a diffusion member according to the present disclosure. [Figure 2] FIG. 1 is a schematic diagram illustrating a conventional clean booth. [Figure 3] FIG. 1 is a schematic diagram illustrating a clean booth according to the present disclosure. [Figure 4] 1A and 1B are a schematic perspective view and a cross-sectional view illustrating a conventional diffusion member. [Figure 5]FIG. 1 is a schematic diagram illustrating a conventional clean booth. [Figure 6] 1 is a schematic cross-sectional view illustrating a diffusion member according to the present disclosure. [Figure 7] FIG. 1 is a schematic diagram illustrating a clean booth according to the present disclosure. [Figure 8] 1A and 1B are schematic diagrams illustrating model shapes of clean booths in Examples and Comparative Examples. [Figure 9] 1 is a graph showing the simulation results of vorticity for Example 1 and Comparative Examples 1 to 5. [Figure 10] 10 is a graph showing the simulation results of vorticity in Example 2. [Figure 11] 10 is a graph showing the simulation results of vorticity in Example 3. [Figure 12] 10 shows simulation results and actual measurement results of airflow in Comparative Example 4. [Figure 13] 1 shows simulation results and actual measurement results of airflow in Example 1. [Figure 14] 10 shows the results of airflow simulation in Example 4. [Figure 15] 10 shows the results of airflow simulation in Comparative Example 6. [Figure 16] 10 is a graph showing the relationship between the distance between the wall of the clean booth and the FFU and the position where an upflow occurs. [Figure 17] 10 shows the results of airflow simulation in Example 5. [Figure 18] 10 shows the results of airflow simulation in Comparative Example 7. [Figure 19] 10 is a graph showing the relationship between the interval between adjacent FFUs and the position where upflow occurs. DETAILED DESCRIPTION OF THE INVENTION

[0012] Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different forms and should not be limited to the description of the embodiments exemplified below. Furthermore, in order to clarify the description, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the actual form, but these are merely examples and should not be interpreted as being limiting. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings will be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0013] In this specification, when expressing an aspect in which another component is placed on top of another component, the term "above" or "below" is used, unless otherwise specified, and includes both a case in which another component is placed directly above or below a component so as to be in contact with the component, and a case in which another component is placed above or below a component with another component in between.

[0014] The diffusion member and clean booth according to the present disclosure will be described in detail below.

[0015] A. Diffusion material The diffusion member in the present disclosure is a diffusion member that is placed at the air outlet of the fan filter unit, has the shape of a quadrangular pyramid, the upper and lower base surfaces of the quadrangular pyramid are rectangular, the upper base surface is open, and is a cloth or a resin sheet with through holes.

[0016] 1(a) and 1(b) are a schematic plan view and a cross-sectional view showing an example of a diffusing member according to the present disclosure, and FIG. 1(b) is a cross-sectional view taken along line AA in FIG. 1(a). As shown in FIGS. 1(a) and 1(b), diffusing member 1 has the shape of a truncated quadrangular pyramid. The truncated quadrangular pyramid has an upper base surface 2, a lower base surface 4, and four side surfaces 3a to 3d. In diffusing member 1, upper base surface 2 and lower base surface 4 of the truncated quadrangular pyramid are rectangular, and upper base surface 2 of the truncated quadrangular pyramid is open. Diffusing member 1 is a fabric or a resin sheet with through holes, allowing air to pass through.

[0017] FIG. 2 is a schematic diagram showing an example of a conventional clean booth. As shown in FIG. 2, the clean booth 100A has a ceiling 11, walls 12, and a fan filter unit 13 disposed on the ceiling 11. Hereinafter, the "fan filter unit" may be abbreviated as "FFU." In the clean booth 100A, clean air 15 is supplied from the FFU 13 and exhausted through a gap between the wall 12 and the floor 14. Because the clean air 15 is blown out from the FFU 13 directly downward, the air 15 flows vertically from the ceiling 11 to the floor 14. However, in areas where the FFU 13 is not disposed, the air 15 does not flow vertically from the ceiling 11 to the floor 14. This makes the air flow more turbulent, resulting in an upflow from the floor 14 to the ceiling 11. This causes dust to fly up and foreign matter to adhere to products.

[0018] FIG. 3 is a schematic diagram showing an example of a clean booth having a diffusion member according to the present disclosure. As shown in FIG. 3, clean booth 10 has ceiling 11, wall 12, FFU 13 arranged on ceiling 11, and diffusion member 1 arranged at the air outlet of FFU 13. Diffusion member 1 is arranged so that the upper base surface 2 of the truncated quadrangular pyramid faces FFU 13. In clean booth 10, clean air 15 is supplied from FFU 13 and exhausted through the gap between wall 12 and floor 14. At this time, clean air 15 is blown out directly downward from FFU 13, passes through diffusion member 1, and is sent into clean booth 10. Diffusion member 1 has the shape of a truncated quadrangular pyramid. Lower base surface 4 of the truncated quadrangular pyramid is horizontal to the ceiling surface, while side surface 3 of the truncated quadrangular pyramid is inclined relative to the ceiling surface. Therefore, the air 15 flows not only vertically from the ceiling 11 to the floor 14 but also diagonally from the ceiling 11 to the floor 14, diffusing the air 15. This allows clean air 15 to be delivered into the clean booth 10 over a wide area, in a wide direction, and at a slow speed. Furthermore, as described in the examples below, it has been confirmed that vorticity is reduced when the diffusing member has a truncated pyramid shape. Generally, high vorticity tends to cause turbulence in the flow. Therefore, in the present disclosure, the diffusing member has a truncated pyramid shape, which suppresses the generation of turbulence and prevents upflow. Therefore, in a clean booth using the diffusing member of the present disclosure, a downflow can be ensured overall, preventing dust from flying up and improving cleanliness. This prevents foreign matter from reaching products, improving product quality and yield.

[0019] Conventionally, a known diffusion member disposed at the air outlet of an FFU is a diffusion member 101 having a semi-elliptical cylindrical shape, as shown in FIGS. 4(a) and 4(b). FIG. 4(a) is a perspective view illustrating a diffusion member having a semi-elliptical cylindrical shape, and FIG. 4(b) is a cross-sectional view taken along line AA in FIG. 4(a). The diffusion member 101 has an upper bottom surface 102a, a lower bottom surface 102b, and a curved side surface 103. FIGS. 5(a) and 5(b) are schematic diagrams illustrating an example of a clean booth having a diffusion member having a semi-elliptical cylindrical shape. As shown in FIGS. 5(a) and 5(b), a clean booth 100B has a ceiling 11, a wall 12, an FFU 13 disposed on the ceiling 11, and a diffusion member 101 having a semi-elliptical cylindrical shape disposed at the air outlet of the FFU 13. The diffusion member 101 is disposed so that the side surface 103 of the semi-elliptical cylindrical shape faces away from the FFU 13. In the clean booth 100B, clean air 15 is supplied from the FFU 13 and exhausted through the gap between the wall 12 and the floor 14. The clean air 15 is blown directly downward from the FFU 13, passes through the diffusing member 101, and is then sent into the clean booth 10. The diffusing member 101 has a semi-elliptical cylindrical shape, and the side surface 103 of the semi-elliptical cylinder is curved. Therefore, as shown in FIG. 5(a), the air 15 passing through the side surface 103 of the semi-elliptical cylinder in the diffusing member 101 flows not only vertically from the ceiling 11 to the floor 14, but also obliquely from the ceiling 11 to the floor 14. Meanwhile, the upper and lower bottom surfaces 102a and 102b of the semi-elliptical cylinder are perpendicular to the ceiling surface. Therefore, as shown in FIG. 5(b), the air 15 passing through the upper and lower bottom surfaces 102a and 102b of the semi-elliptical cylinder in the diffusing member 101 flows horizontally relative to the ceiling surface. Therefore, although the air 15 is diffused, part of the air 15 flows horizontally relative to the ceiling surface and collides with the wall, easily causing the air flow to become turbulent. Furthermore, although not shown, if multiple FFUs are installed in the ceiling of the clean booth, the air that is blown out from the FFUs and passes through the upper or lower bottom surfaces of the semi-elliptical cylinders of the diffusing member will collide with each other, easily causing the air flow to become turbulent. Therefore, a turbulent flow is likely to occur from the floor surface 14 toward the ceiling 11.Furthermore, as will be described in a comparative example below, it was confirmed that when the diffusion member has a semi-elliptical cylindrical shape, the vorticity becomes relatively large.

[0020] Therefore, in the present disclosure, it is important that the diffusion member has a truncated square pyramid shape.

[0021] Hereinafter, the diffusion member according to the present disclosure will be described in detail for each of its components.

[0022] 1. Square pyramid shape The diffusion member according to the present disclosure has a shape of a truncated quadrangular pyramid, and the upper and lower base surfaces of the truncated quadrangular pyramid are rectangular, with the upper base surface being open.

[0023] In this specification, the upper base of a truncated square pyramid refers to the base with the larger area of ​​the two bases of the truncated square pyramid. The lower base of a truncated square pyramid refers to the base with the smaller area of ​​the two bases of the truncated square pyramid. In addition, in this specification, the term "rectangular shape" also includes a square shape.

[0024] In the truncated quadrangular pyramid, the angle between the upper base and the side surface is, for example, preferably 43° or more and 65° or less, and more preferably 43° or more and 47° or less. When the angle is within the above range, air can be uniformly diffused in a clean booth using the diffusion member of the present disclosure. On the other hand, if the angle is close to 90°, in a clean booth using the diffusion member of the present disclosure, air blown out from the FFU and passing through the side surface of the truncated quadrangular pyramid of the diffusion member tends to flow in a direction approximately horizontal to the ceiling surface. This may increase the risk of turbulence. Furthermore, if the angle is close to 0°, in a clean booth using the diffusion member of the present disclosure, air blown out from the FFU and passing through the side surface of the truncated quadrangular pyramid of the diffusion member tends to flow in a direction approximately vertical to the ceiling surface. This may increase the risk of turbulence.

[0025] In a truncated quadrangular pyramid, the angle between the upper base and the side surface refers to the angle θ between the upper base 2 and the inner surface of the side surface 3, as shown in FIG.

[0026] The height of the truncated square pyramid is preferably, for example, 70 mm or more. On the other hand, the height of the truncated square pyramid is preferably, for example, 200 mm or less, more preferably 160 mm or less, even more preferably 100 mm or less, and particularly preferably 90 mm or less. That is, the height of the truncated square pyramid is preferably, for example, 70 mm or more and 200 mm or less, preferably 70 mm or more and 160 mm or less, more preferably 70 mm or more and 100 mm or less, and even more preferably 70 mm or more and 90 mm or less. If the height is within the above range, air can be uniformly diffused in a clean booth using the diffusion member of the present disclosure. Furthermore, as described in the examples below, it has been confirmed that there is a correlation between the height of the truncated square pyramid and vorticity, and that there is a suitable value. If the height is within the above range, vorticity can be reduced, and the generation of turbulence can be suppressed. On the other hand, if the height is too high, the side surface area of ​​the truncated quadrangular pyramid tends to increase. Therefore, in a clean booth using a diffusion member according to the present disclosure, a large amount of air flows obliquely from the ceiling to the floor among the air blown out from the FFU and passing through the diffusion member. Therefore, there is a risk that the air blown out from the FFU and passing through the side surface of the truncated quadrangular pyramid of the diffusion member may be more likely to collide with the wall. Furthermore, if multiple FFUs are installed on the ceiling of a clean booth, there is a risk that the air blown out from the FFUs and passing through the side surface of the truncated quadrangular pyramid of the diffusion member may be more likely to collide with each other. Therefore, there is a concern that turbulence may be more likely to occur. Furthermore, if the height is too low, there is a risk that the vorticity will increase, making turbulence more likely to occur.

[0027] The height of the truncated quadrangular pyramid refers to the height H from the inner surface of the lower base surface 4 to the upper base surface 2, as shown in FIG.

[0028] The truncated quadrangular pyramid has an upper base that is rectangular. Because the diffusion member is disposed at the air outlet of the FFU, the size of the upper base of the truncated quadrangular pyramid is preferably equal to or larger than the size of the air outlet of the FFU, and is preferably larger than the size of the air outlet of the FFU. For example, the size of the upper base of the truncated quadrangular pyramid may be approximately the same as the size of the FFU in a planar view.

[0029] Furthermore, the truncated quadrangular pyramid has a rectangular bottom surface. The size of the bottom surface is preferably set so that the angle between the top surface and the side surface falls within a predetermined range. The size of the bottom surface is appropriately set depending on the size of the top surface, the height of the truncated quadrangular pyramid, the angle between the top surface and the side surface, the air volume of the FFU, etc. For example, if the air volume of the FFU is 10 m 3 / min, and when the size of the upper base is 610 mm x 610 mm, the size of the lower base is preferably 350 mm x 350 mm or more and 530 mm x 530 mm or less. If the size of the lower base is within the above range, air can be uniformly diffused in a clean booth using the diffusion member of the present disclosure. Furthermore, as described in the examples below, it has been confirmed that there is a correlation between the size of the lower base and vorticity, and that there is a suitable value. If the size of the lower base is within the above range, vorticity can be reduced and the generation of turbulence can be suppressed.

[0030] As will be described later, if the diffusion member is made of cloth, the shape of the truncated quadrangular pyramid may bend due to its own weight. However, even in such a case, if the diffusion member is designed to have a truncated quadrangular pyramid shape, it is considered to have the shape of a truncated quadrangular pyramid.

[0031] 2. Physical Properties The diffusion member in the present disclosure preferably has a small pressure loss. 3 / hr, the pressure loss is preferably 5mmAq or less, and the air volume is 600m 3 At this rate, it is more preferable that the pressure loss is 1 mmAq or less.

[0032] The pressure loss of the diffusion material is determined by the following method. First, the diffusion material is placed in a duct, and a blower blows air at a volume of 1600 m 3 / hr or 600m 3 / hr and supply clean air. A differential pressure gauge is used to measure the difference between the pressure (static pressure) on the upstream side and the pressure (static pressure) on the downstream side of the diffusion member, and this differential pressure is taken as the pressure loss.

[0033] 3.Material The diffusion member in the present disclosure is a cloth or a resin sheet having through holes.

[0034] The fabric is preferably a dust-free fabric, which is used in clean rooms and clean booths and is less likely to generate dust. The fabric is preferably chemical-resistant and flame-retardant. Examples of the fabric include woven fabrics and knitted fabrics.

[0035] Examples of the material for the cloth include natural fibers and chemical fibers. Examples of natural fibers include silk, cotton, and animal hair. Examples of chemical fibers include polyester, nylon, and polypropylene. The material for the cloth is preferably a material used for dust-free cloth, and for example, polyester, nylon, and polypropylene are preferably used.

[0036] The thickness of the fabric is not particularly limited as long as it satisfies the above physical properties, and may be, for example, 0.4 mm or more and 0.7 mm or less, or 0.4 mm or more and 0.5 mm or less.

[0037] Methods for forming a piece of fabric into a truncated pyramid shape include, for example, folding the fabric or stitching the fabric. In the stitching method, stitches may be added to a single piece of fabric or to multiple pieces of fabric sewn together.

[0038] The resin sheet having through holes is preferably chemical resistant and flame retardant, and may be made of, for example, polypropylene.

[0039] The size of the through holes in the resin sheet is not particularly limited as long as the above physical properties are satisfied. The thickness of the resin sheet is also not particularly limited as long as the above physical properties are satisfied, and may be, for example, 0.4 mm to 0.7 mm, or 0.4 mm to 0.5 mm.

[0040] In particular, the diffusion member in the present disclosure is preferably a cloth, since cloth has a higher degree of freedom in shape than a resin sheet, and cloth is easy to handle when attaching the diffusion member to the air outlet of the fan filter unit.

[0041] 4. Other configurations The diffusion member according to the present disclosure may have a fixing portion for attaching it to the air outlet of the fan filter unit. The fixing portion is not particularly limited, and examples thereof include double-sided tape and hook-and-loop fasteners.

[0042] B. Clean Booth The clean booth according to the present disclosure includes a ceiling, a wall, a fan filter unit disposed on the ceiling, and the above-described diffusion member disposed at an air outlet of the fan filter unit.

[0043] Fig. 3 is a schematic diagram showing an example of a clean booth in the present disclosure. Fig. 3 has been described above in the section "A. Diffusion member," so a description thereof will be omitted here.

[0044] In the present disclosure, the above-described diffusion member is disposed at the air outlet of the fan filter unit, thereby achieving the effects described in the above section "A. Diffusion member."

[0045] Below, the clean booth according to the present disclosure will be described in detail for each component.

[0046] 1. Diffusion material The diffusing member in this disclosure is similar to the diffusing member described above, and therefore will not be described here.

[0047] 2.FFU The FFU in the present disclosure is placed on the ceiling of the clean booth, and a general FFU used in clean booths can be used as the FFU.

[0048] The number of FFUs may be one or more. When multiple FFUs are provided, the cleanliness can be improved.

[0049] In a clean booth, the distance between the wall and the FFU is adjusted appropriately depending on the air volume of the FFU. For example, if the air volume of the FFU is 10 m 3 / min, the distance between the wall and the FFU is preferably 10 mm or more. If the distance between the wall and the FFU is within the above range, the occurrence of upflow can be suppressed. On the other hand, the lower limit of the distance between the wall and the FFU is not particularly limited. For example, if the air volume of the FFU is 10 m 3 / min, the distance between the wall and the FFU is 600 mm or less. 3 / min, the distance between the wall and the FFU is preferably 10 mm or more and 600 mm or less. When the FFU is arranged over the entire surface of the ceiling, the vorticity becomes extremely small. In other words, when the FFU is arranged away from the wall, the vorticity becomes larger than when the FFU is arranged over the entire surface of the ceiling. Therefore, the present disclosure is useful when the FFU is arranged away from the wall.

[0050] The distance between the wall and the FFU refers to the distance D1 from the inner surface of the wall 12 to the end of the FFU 13 on the wall 12 side, as shown in FIG.

[0051] When multiple FFUs are installed in a clean booth, the distance between adjacent FFUs is adjusted appropriately according to the air volume of the FFU. 3 / min, the interval between adjacent FFUs is preferably 610 mm or less. If the interval between adjacent FFUs is within the above range, the occurrence of upflow can be suppressed. On the other hand, the lower limit of the interval between adjacent FFUs is not particularly limited, and for example, if the air volume of the FFU is 10 m 3 / min, the distance between adjacent FFUs is 100 mm or more. 3 / min, the interval between adjacent FFUs is preferably 100 mm or more and 610 mm or less. As described above, when FFUs are arranged over the entire surface of the ceiling, the vorticity becomes extremely small. In other words, when FFUs are arranged at a distance from each other, the vorticity becomes greater than when the FFUs are arranged over the entire surface of the ceiling. Therefore, the present disclosure is useful when FFUs are arranged at a distance from each other.

[0052] The interval between adjacent FFUs refers to the distance D2 between the opposing ends of adjacent FFUs 13, as exemplified in FIG.

[0053] 3. Ceiling The FFU is disposed on the ceiling section in the present disclosure. The ceiling section includes, for example, a ceiling material and a frame that supports the ceiling material.

[0054] The ceiling material may be a general ceiling material used in clean booths. Examples of the ceiling material include a resin sheet, a resin plate, a metal composite plate, and a metal plate. The ceiling material may or may not be flexible. The frame may be a general frame used in clean booths.

[0055] 4.Wall part The wall portion in the present disclosure includes, for example, a wall material and a frame that supports the wall material.

[0056] The wall material can be a typical wall material used in clean booths. Examples of wall materials include resin sheets, resin plates, metal composite plates, and metal plates. The wall material may or may not be flexible. The frame can be a typical frame used in clean booths.

[0057] The clean booth in the present disclosure has a gap between the wall and floor for exhaust ventilation. The gap between the wall and floor is not particularly limited as long as it is a gap generally set in a clean booth, and is, for example, more than 0 cm and not more than 10 cm.

[0058] 5. Other configurations The clean booth in the present disclosure may have a sensor to control the airflow rate of the FFU. An example of such a sensor is a human presence sensor. When a person enters or leaves the clean booth, the pressure inside the booth tends to drop significantly. Therefore, for example, a system using a human presence sensor to increase the airflow rate when a person enters the booth is available.

[0059] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included within the technical scope of the present disclosure. [Example]

[0060] [Example 1] A diffusion member was prepared, which had a shape of a quadrangular pyramid, with the top and bottom surfaces of the pyramid being square, the top surface being open, and which was made of a woven polypropylene fabric. The size of the top surface of the quadrangular pyramid was 450 mm x 450 mm, the size of the bottom surface was 610 mm x 610 mm, the height was 80 mm, and the angle between the top surface and the side surface was 45°. The diffusion member was used to radiate an air volume of 1600 m3. 3 / hr, the pressure loss is 4mmAq and the air volume is 600m 3 The pressure loss at 1000kJ / hr was 1 mmAq.

[0061] The clean booth had one FFU, and the FFU used was the "MAC-IIA-101DCCON" manufactured by Airtech. The clean booth had a height of 2300 mm, a width of 2210 mm, and a depth of 2800 mm. A gap was provided between the wall and floor of the clean booth for exhaust ventilation. The size of the FFU was 610 mm x 610 mm. The distance between the wall of the clean booth and the FFU was 600 mm. The above-mentioned diffusion member was placed at the outlet of the FFU in the clean booth.

[0062] In the following simulations, the models of the clean booth, FFU, and diffusion member were the same as those described above.

[0063] [Comparative Example 1] The following simulation was performed in the same manner as in Example 1, except that the following diffusion member model was used. The diffusion member had a rectangular parallelepiped shape, with the upper and lower base surfaces of the rectangular parallelepiped being square, and the upper base surface was open. The dimensions of the upper and lower base surfaces of the rectangular parallelepiped were 610 mm × 610 mm, and the height was 80 mm.

[0064] Comparative Example 2 The following simulation was performed in the same manner as in Example 1, except that the following diffusion member model was used. The diffusion member had a quadrangular pyramid shape, and the base of the quadrangular pyramid was a square with an open bottom. The size of the base of the quadrangular pyramid was 610 mm × 610 mm, and the height was 80 mm.

[0065] Comparative Example 3 The following simulation was performed in the same manner as in Example 1, except that the following diffusion member model was used. The diffusion member was a model having the shape of a semi-elliptical cylinder as shown in Figures 4(a) and 4(b). In the semi-elliptical cylinder, the size of the open surface 104 was 610 mm x 610 mm, and the height H1 was 80 mm.

[0066] Comparative Example 4 The following simulation was carried out in the same manner as in Example 1, except that a model was used in which no diffusion member was placed in the clean booth.

[0067] Comparative Example 5 The following simulation was carried out in the same manner as in Example 1, except that the FFU was placed over the entire surface of the ceiling of the clean booth and no diffusion member was placed in the model.

[0068] [Example 2] The following simulations were performed in the same manner as in Example 1, except that the size of the lower base of the truncated quadrangular pyramid was changed to 150 mm x 150 mm, 250 mm x 250 mm, 350 mm x 350 mm, 450 mm x 450 mm, or 550 mm x 550 mm, and the height was changed to 80 mm or 160 mm.

[0069] [Example 3] The following simulation was carried out in the same manner as in Example 1, except that the height of the truncated quadrangular pyramid was changed to 40 mm, 80 mm, 160 mm, 240 mm, and 320 mm.

[0070] [Rating 1] (1) Simulation of vorticity As described above, simulation of vorticity was carried out for Examples 1 to 3 and Comparative Examples 1 to 5. <Simulation conditions> ·Inflow speed: 0.65m / s ·Opening: Exit conditions Diffusion material: Porous condition Uses turbulence model Clean booth model: The above clean booth, Fig. 8(a)

[0071] The simulation results of vorticity for Example 1 and Comparative Examples 1 to 5 are shown in Figure 9. It was confirmed that Example 1 had a smaller vorticity than Comparative Example 4, in which no diffusing member was provided. It was also confirmed that Example 1 had a smaller vorticity than Comparative Example 3, in which a conventional diffusing member having a semi-elliptical cylindrical shape was used. On the other hand, Comparative Example 1, in which a diffusing member having a rectangular parallelepiped shape was used, and Comparative Example 2, in which a diffusing member having a square pyramid shape was used, had a larger vorticity than Comparative Example 4, in which no diffusing member was provided.

[0072] The simulation results of the vorticity for Example 2 are shown in Fig. 10. Fig. 10 confirms that there is a correlation between the size of the lower base surface and the vorticity, and that a suitable value exists.

[0073] The simulation results of vorticity for Example 3 are shown in Fig. 11. Fig. 11 confirms that there is a correlation between the height of the truncated square pyramid and the vorticity, and that a suitable value exists.

[0074] (2) Airflow simulation and measurement For Example 1 and Comparative Example 4, a simulation of the airflow was carried out between the wall of the clean booth and the FFU. <Simulation conditions> ·Inflow speed: 0.65m / s ·Opening: Exit conditions Diffusion material: Porous condition Uses turbulence model Clean booth model: The above clean booth, Fig. 8(a)

[0075] In addition, for Example 1 and Comparative Example 4, the air volume of the FFU was 10 m 3 / min, and the wind speed inside the clean booth was measured using a three-dimensional anemometer manufactured by Sonic Corporation.

[0076] The simulation results and actual measurement results for Comparative Example 4 are shown in Figures 12(a) and 12(b), respectively. The simulation results and actual measurement results for Example 1 are shown in Figures 13(a) and 13(b), respectively. In Comparative Example 4, the simulation showed an upflow at a height of 370 mm or more from the floor, whereas the actual measurement showed an upflow from the floor to the ceiling, with a maximum wind speed of 0.05 m / s. Meanwhile, in Example 1, the simulation showed an upflow at a height of 663 mm or more from the floor, whereas the actual measurement showed an upflow at a height of 1600 mm or more from the floor, with a maximum wind speed of 0.04 m / s. The simulation results and actual measurement results for Example 1 generally showed a consistent trend. Furthermore, in Example 1, the actual measurement showed no upflow at a height of 1600 mm or less from the floor, but a downflow with a maximum wind speed of 0.02 m / s occurred. It was found that the actual measurement showed a tendency for the airflow to be more rectified in Example 1.

[0077] [Example 4] In the model of Example 1, models were used in which the distance between the wall of the clean booth and the FFU was changed to 20 mm, 100 mm, 200 mm, 400 mm, 500 mm, 600 mm, and 1000 mm.

[0078] Comparative Example 6 In the model of Comparative Example 4, models were used in which the distance between the wall of the clean booth and the FFU was changed to 20 mm, 100 mm, 200 mm, 400 mm, 500 mm, 600 mm, and 1000 mm.

[0079] [Rating 2] For Example 4 and Comparative Example 6, an airflow simulation was carried out. <Simulation conditions> ·Inflow speed: 0.65m / s ·Opening: Exit conditions Diffusion material part: Porous condition (input resistance coefficient) Uses turbulence model Clean booth model: The above clean booth, Fig. 8(a)

[0080] For Example 4, simulation results for when the distance between the wall and the FFU is 1000 mm or 600 mm are shown in Figures 14(a) and 14(b), respectively. For Comparative Example 6, simulation results for when the distance between the wall and the FFU is 1000 mm, 400 mm, or 100 mm are shown in Figures 15(a), 15(b), and 15(c), respectively. The circles in Figures 14 and 15 indicate the location of upflow generation. The location of upflow generation was also determined from the simulation results. Figure 16 shows the relationship between the distance between the wall of the clean booth and the FFU and the location of upflow generation. In Figure 16, the location of upflow generation is indicated by the height from the floor. Figure 16 reveals that there is a suitable range for the distance between the wall of the clean booth and the FFU.

[0081] [Example 5] In the model of Example 1, a model was used in which the clean booth had two FFUs, and the interval between adjacent FFUs was changed to 100 mm, 305 mm, 610 mm, 800 mm, and 1220 mm.

[0082] Comparative Example 7 In the model of Example 5, a model in which a diffusion member was not placed in the clean booth was used.

[0083] [Rating 2] For Example 5 and Comparative Example 7, an airflow simulation was carried out. <Simulation conditions> ·Inflow speed: 0.65m / s ·Opening: Exit conditions Diffusion material: Porous condition Uses turbulence model Clean booth model: The above clean booth, Fig. 8(b)

[0084] For Example 5, simulation results when the interval between adjacent FFUs is 800 mm or 610 mm are shown in Figures 17(a) and 17(b), respectively. For Comparative Example 7, simulation results when the interval between adjacent FFUs is 800 mm, 610 mm, or 100 mm are shown in Figures 18(a), 18(b), and 18(c), respectively. The circles in Figures 17 and 18 indicate the locations where upflows occur. The locations where upflows occur were also determined from the simulation results. Figure 19 shows the relationship between the interval between adjacent FFUs and the locations where upflows occur. In Figure 19, the locations where upflows occur are indicated by the height from the floor. Figure 19 reveals that there is a suitable range for the interval between adjacent FFUs.

[0085] The present disclosure provides the following inventions. [1] A diffusion member disposed at an air outlet of a fan filter unit, The pyramid has a shape of a truncated quadrangular pyramid, and the truncated quadrangular pyramid has an upper and lower base surfaces each having a rectangular shape, and the upper base surface is open, The diffusion member is a cloth or a resin sheet having through holes. [2] The diffusion member according to [1], wherein the angle between the upper base and the side surface of the truncated quadrangular pyramid is 43° or more and 65° or less. [3] The diffusion member according to [1] or [2], wherein the height of the truncated quadrangular pyramid is 70 mm or more and 200 mm or less. [4] A clean booth having a ceiling portion, a wall portion, a fan filter unit arranged on the ceiling portion, and a diffusion member according to any one of [1] to [3] arranged at the air outlet of the fan filter unit. [5] The clean booth according to [4], wherein the distance between the wall and the fine filter unit is 10 mm or more and 600 mm or less. [6] The clean booth according to [4] or [5], which has a plurality of the fan filter units, and the interval between adjacent fan filter units is 100 mm or more and 610 mm or less. [Explanation of symbols]

[0086] 1... Diffusion element 2 … Upper base 3a, 3b, 3c, 3d…side 4 … Bottom surface 5... Release material 10... Clean booth 11 ... Ceiling 12 … Wall part 13 … FFU 14...Floor

Claims

1. A diffusion member disposed at an air outlet of a fan filter unit, The pyramid has a shape of a truncated quadrangular pyramid, and the upper and lower base surfaces of the truncated quadrangular pyramid are rectangular in shape; The upper and bottom surfaces are open, The diffusion member is a cloth or a resin sheet having through holes.

2. The diffusing member according to claim 1 , wherein the angle formed between the upper base and the side surface of the truncated quadrangular pyramid is equal to or greater than 43° and equal to or less than 65°.

3. The diffusion member according to claim 1 , wherein the height of the truncated quadrangular pyramid is 70 mm or more and 200 mm or less.

4. A clean booth comprising: a ceiling portion; a wall portion; a fan filter unit disposed on the ceiling portion; and a diffusion member according to any one of claims 1 to 3 disposed at an air outlet of the fan filter unit.

5. 5. The clean booth according to claim 4, wherein the distance between the wall portion and the fine filter unit is 10 mm or more and 600 mm or less.

6. 5. The clean booth according to claim 4, wherein a plurality of the fan filter units are provided, and the interval between adjacent fan filter units is 100 mm or more and 610 mm or less.

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