Casing of air filter, mounting structure of air filter, and mounting method of air filter

Abstract

To provide a casing of an air filter which can prevent air from leaking without passing through the air filter while reducing a manufacturing cost.SOLUTION: A casing 1 includes an annular plate-like frame 20, and a mounting structure 30. The plate-like frame 20 functions as a partitioning plate for preventing air taken in the casing 1 from leaking to a downstream side without passing through an air filter 100, and has a through hole 20a formed to penetrate in an air flow direction Y. The mounting structure 30 includes a bolt 31 which is inserted in the through hole 20a, an upstream side nut 33, and a washer 35. The washer 35 includes an inner circumference added part 35b added to an end part of a washer main body 35a on an inner circumference side. The inner circumference added part 35b deforms so that the washer 35 enters a clearance between the through hole 20a and the bolt 31 by being caught between the upstream side nut 33 and the plate-like frame 20.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a casing that houses an air filter, an air filter mounting structure, and an air filter mounting method. [Background technology]

[0002] A casing containing an air filter is installed adjacent to the air outlet that blows the air that has flowed through the duct into the room from the ceiling, and the air that has flowed through the duct is passed through the air filter to be purified. The casing body has a peripheral inner wall surface that surrounds the flow path of the air that passes through the air filter.

[0003] In order to prevent the taken-in air from leaking downstream without passing through the air filter, an annular plate-shaped frame is provided inside the casing, which protrudes into the air flow path from a position on the inner wall surface midway through the air flow path and runs around the inner wall surface. The air filter is attached in contact with the plate-shaped frame from the downstream side in the airflow direction so as to block the area of ​​the flow path surrounded by the plate-shaped frame.

[0004] One mounting structure for mounting an air filter to a plate-shaped frame, for example, involves fixing a nut to the downstream surface of the plate-shaped frame (filter mounting frame) by welding, inserting a bolt (stud bolt) into the nut, and then passing a fixing member (fixing metal fitting) that sandwiches and fixes the air filter between the plate-shaped frame and the bolt through the nut, and then tightening a fixing nut arranged downstream of the fixing member to press the fixing member against the air filter (Patent Document 1). In this type of mounting structure, the surfaces of the plate-shaped frame and the welded nut are generally painted to prevent rust at the welded points.

[0005] Another known mounting structure is one in which one (second locking member) of two mutually locking members is fixed to the inner wall surface of the casing (housing) by welding, and the air filter is pressed in the airflow direction with the tip of a bolt attached to the other locking member (first locking member), thereby pressing the air filter against the opening of the casing (Patent Document 2).The surface of the second locking member and the inner wall surface of the casing are preferably painted to prevent rust at the welded points. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-83107 A [Patent Document 2] JP 2022-157616 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the above mounting structure, the nuts and the locking members are fixed to the surface of the plate frame or the inner wall of the casing without drilling holes in the inner wall of the plate frame or the casing. Therefore, there are usually no locations on the inner wall of the plate frame or the casing that could cause air leakage. However, in the above mounting structure, welding and painting are required to fix the nuts and the locking members, so the manufacturing of the mounting structure and the casing is costly. In addition, special skills are required for welding and painting, and if the worker's skills are insufficient, defects in welding and painting may occur, which may cause the nuts and the locking members to loosen from the inner wall of the plate frame or the casing, weakening the force that fixes the air filter, and causing air leakage.

[0008] Therefore, an object of the present invention is to provide an air filter casing, an air filter mounting structure, and an air filter mounting method that can prevent air from leaking without passing through the air filter while reducing manufacturing costs. [Means for solving the problem]

[0009] The present disclosure includes the following aspects. Aspect 1 A casing for housing an air filter and for passing air through the air filter, a casing body having a circumferential inner wall surface surrounding a flow path of air passing through the air filter; a ring-shaped plate-shaped frame that protrudes into the flow path from a position on the inner wall surface midway through the flow path and goes around the inner wall surface, the air filter abutting against the area of ​​the flow path surrounded by the plate-shaped frame from the downstream side in the air flow direction, thereby functioning as a partition plate that prevents air taken into the casing from leaking downstream without passing through the air filter, and the plate-shaped frame having a through hole formed therein that penetrates in the air flow direction; an attachment structure for attaching the air filter to the plate-shaped frame, the attachment structure including: a bolt inserted into the through hole; an upstream nut disposed upstream of the plate-shaped frame in the airflow direction and attached to the bolt; and a washer inserted into the bolt so as to be interposed between the upstream nut and the plate-shaped frame; Equipped with The washer has a washer body and an inner peripheral addition portion added to an end portion on an inner peripheral side of the washer body, The casing is characterized in that the inner peripheral additional portion deforms so as to enter into the gap between the through hole and the bolt when the washer is sandwiched between the upstream nut and the plate-shaped frame.

[0010] Aspect 2 2. The casing of claim 1, wherein the upstream nut is a cap nut in which a screw hole into which the bolt is fitted is closed on the upstream side in the airflow direction.

[0011] Aspect 3 Aspect 3. The casing according to aspect 1 or 2, wherein the upstream nut is a flanged nut having a downstream end that abuts against the washer and extends radially outward.

[0012] Aspect 4 A casing described in any one of aspects 1 to 3, wherein the mounting structure further has a pair of downstream nuts arranged downstream of the plate frame in the airflow direction and attached to the bolts so as to press against each other in the airflow direction.

[0013] Aspect 5 An inner peripheral end portion of a first nut arranged on the upstream side among the downstream nuts, in which a screw hole to be attached to the bolt is formed, has a wedge-shaped protrusion extending in a tapered shape toward a second nut arranged on the downstream side among the downstream nuts, A casing as described in aspect 4, wherein the second nut has a protrusion receiving recess adjacent to the upstream side of an inner end portion in which a threaded hole for attachment to the bolt is formed, the protrusion receiving recess being recessed to receive the wedge-shaped protrusion.

[0014] Aspect 6 The mounting structure further includes: a fixing member that is inserted through the bolt and that fixes the air filter by sandwiching it between the air filter and the plate-shaped frame; a fixing nut that is disposed downstream of the fixing member in the airflow direction and is attached to the bolt; Aspects 6. The casing of any one of aspects 1 to 5, wherein the bolt is threaded over an entire axial extent of the bolt.

[0015] Aspect 7 The washer body is made of metal, 7. The casing of claim 6, wherein the plate frame has no coating on the surface facing the washer.

[0016] Aspect 8 The plate-like frame has a rectangular shape when viewed in the airflow direction, A casing described in any one of aspects 1 to 7, wherein when the through hole is referred to as a first through hole, the plate-shaped frame further has at least three second through holes, and at least one of the through holes is formed in each of four side portions extending in a straight line corresponding to the four sides of the plate-shaped frame.

[0017] Aspect 9 1. A mounting structure for mounting an air filter to a casing that houses an air filter and allows air to pass through the air filter, comprising: The casing comprises: a casing body having a circumferential inner wall surface surrounding a flow path of air passing through the air filter; a ring-shaped plate-shaped frame that protrudes into the flow path from a position on the inner wall surface midway through the flow path and goes around the inner wall surface, the air filter abutting against the area of ​​the flow path surrounded by the plate-shaped frame from the downstream side in the air flow direction, thereby functioning as a partition plate that prevents air taken into the casing from leaking downstream without passing through the air filter, and the plate-shaped frame having a through hole formed therein that penetrates in the air flow direction; an attachment structure for attaching the air filter to the plate-shaped frame, the attachment structure including: a bolt inserted into the through hole; an upstream nut disposed upstream of the plate-shaped frame in the airflow direction and attached to the bolt; and a washer inserted into the bolt so as to be interposed between the upstream nut and the plate-shaped frame; Equipped with The washer has a washer body and an inner peripheral addition portion added to an end portion on an inner peripheral side of the washer body, an air filter mounting structure, characterized in that the inner peripheral additional portion deforms so as to enter into the gap between the through hole and the bolt when the washer is sandwiched between the upstream nut and the plate-shaped frame.

[0018] Aspect 10 A method of mounting an air filter to a casing according to any one of aspects 1 to 8, comprising the steps of: a preparation step of inserting the bolt into the through hole, and attaching the upstream nut to the bolt on the upstream side of the plate-shaped frame in the airflow direction with the washer interposed between the bolt and the plate-shaped frame; and a tightening process for deforming the inner peripheral addition portion so that it enters into the gap between the through hole and the bolt by sandwiching the washer between the upstream nut and the plate-shaped frame. Effect of the Invention

[0019] According to the above aspect, it is possible to reduce manufacturing costs and prevent air from leaking without passing through the air filter. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a perspective view showing the inside of a casing according to the embodiment. [Diagram 2] FIG. 4 is a bottom view showing the casing as viewed from the downstream side. [Diagram 3] 3 is a cross-sectional view of the mounting structure taken along line III-III of FIG. 1. [Figure 4] FIG. 4 is an enlarged view showing a part of the mounting structure. [Diagram 5] 1A is a cross-sectional view showing the washer before the upstream nut is tightened, and FIG. 1B is a cross-sectional view showing the washer after the upstream nut has been tightened. [Figure 6] FIG. 13(a) is a diagram showing the steps of inserting a bolt into a through hole, (b) is a diagram showing the steps of attaching an upstream nut to the bolt, and (c) is a diagram showing the steps of tightening a second nut of the downstream nut. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an air filter casing, an air filter mounting structure, and an air filter mounting method according to an embodiment will be described.

[0022] Fig. 1 shows a see-through view of the inside of a casing 1 according to an embodiment. Fig. 2 shows the casing 1 as viewed from the downstream side. Fig. 3 shows a cross section of a mounting structure 30 at the position of a through hole 20a. Fig. 3 is a view taken along the line III-III in Fig. 1.

[0023] The casing 1 is a member that houses the air filter 100 and allows air to pass through the air filter 100. The casing 1 is installed in the ceiling space adjacent to an air outlet provided in the ceiling of a building such as a factory or a building.

[0024] The casing 1 includes a casing body 10, a plate-shaped frame 20, and a mounting structure 30. The mounting structure 30 is omitted from illustration in Figs. 1 and 2.

[0025] The casing body 10 of the example shown in FIG. 1 is a member having a rectangular parallelepiped outer shape and a hollow inside. The casing body 10 has an upper surface portion 11 and four side surfaces 12, which form the upper surface and side surfaces of the six surfaces of the rectangular parallelepiped. One of the side surfaces 12 is formed with an intake port 10a connected to a duct (not shown) in a building. The intake port 10a is an opening for taking in air whose temperature and humidity are adjusted by an air conditioning system (not shown) in the building and which flows through the duct. The air taken into the casing 1 is purified by passing through an air filter 100. The part of the casing body 10 that forms the bottom surface of the rectangular parallelepiped is formed with an exhaust port 10b for discharging the air taken into the casing 1 and passed through the air filter 100. The casing 1 is arranged so that the exhaust port 10b faces, for example, a plate material (not shown) with a plurality of holes that forms an air outlet on the ceiling.

[0026] 1 diagrammatically shows the flow of air inside the casing 1. The casing body 10 has a circumferential inner wall surface that surrounds the flow path of air in the Y direction passing through the air filter 100. The circumferential inner wall surface is composed of inner surfaces 12a of four side surface portions 12 that face inward of the casing 1.

[0027] The casing body 10 is produced, for example, by combining plate materials forming the top surface portion 11 and the side surface portion 12. As the plate materials, metal plate materials such as aluminum-zinc alloy plated steel plate, zinc plated steel plate, stainless steel plate, etc. are preferably used, but aluminum-zinc alloy plated steel plate (for example, Galvalume steel plate (registered trademark)) is preferably used in terms of obtaining a cost reduction effect. Since attaching the air filter 100 to the casing 1 requires work at a high altitude, the plate thickness of the top surface portion 11 and the side surface portion 12 is preferably 0.8 to 1.2 mm, for example 1.0 mm, in order to reduce the weight of the casing 1 and the burden on the worker.

[0028] The plate-shaped frame 20 is an annular member that protrudes into the flow path from a position on the inner wall surface midway through the flow path and goes around along the inner wall surface. The air filter 100 abuts against the plate-shaped frame 20 so as to block the area of ​​the flow path surrounded by the plate-shaped frame 20 from the downstream side in the airflow direction (Y direction) (the lower side in the Y direction). This configuration makes it easy to insert and remove the air filter 100 from below into the casing 1, and facilitates the replacement (removal and installation) of the air filter 100 at high altitudes.

[0029] The plate-like frame 20 is produced, for example, by bending the edges on the outer and inner sides of an annular plate material, and the cross section of the ring midway has a U-shape as shown in Fig. 3. When the air filter 100 abuts against the plate-like frame 20 as described above, the plate-like frame 20 functions as a partition plate that prevents air taken into the casing 1 from leaking downstream without passing through the air filter 100.

[0030] On the other hand, the plate-shaped frame 20 is formed with a through hole 20a penetrating in the air flow direction. This allows the bolt 31 to be inserted into the through hole 20a, and as will be described later, the bolt 31 can be fixed by tightening nuts 33, 37 from both sides of the plate-shaped frame 20. For this reason, when the casing 1 is manufactured, unlike the conventional mounting structure in which a bolt is inserted into a nut fixed to one side of the plate-shaped frame and fixed, it is not necessary to fix the nut by welding and further paint the surface of the plate-shaped frame and the nut including the welded part. Conventionally, welding is performed by spot welding using a high nut, for example. Painting is performed by melamine baking paint, for example. By eliminating welding and painting when manufacturing the casing 1, the manufacturing cost of the casing 1 can be significantly reduced. In addition, since welding is not required when manufacturing the casing 1, for example, a plate material such as Galvalume steel plate (registered trademark), which is difficult to weld but inexpensive, can be used for the plate-shaped frame 20, and the degree of freedom in selecting the material for the plate-shaped frame 20 is increased. Furthermore, since no welding is required in the manufacture of the casing 1, a thin plate material that is easily distorted by welding can be used for the plate frame 20. This makes it easy to reduce the weight and cost of the casing 1. The thickness of the plate frame 20 in the airflow direction is preferably 1.0 to 3.0 mm, for example 2.3 mm.

[0031] The mounting structure 30 is a structure for mounting the air filter 100 to the plate-shaped frame 20. The mounting structure 30 has a bolt 31, an upstream nut 33, and a washer .

[0032] The bolt 31 is a member inserted into the through hole 20a. The bolt 31 may have a head (usually a hexagonal portion) at one end in the longitudinal direction, but is preferably a stud bolt that does not have a head at both ends in the longitudinal direction. If the bolt 31 does not have a head at both ends, a fixing nut 43 (described later) can be attached to the downstream end of the bolt 31, so that the moving distance of the fixing nut 43 along the shaft of the bolt 31 is short, and the air filter 100 can be replaced quickly. Note that in the cross-sectional view of the bolt 31, the threads are shown instead of the cross section.

[0033] The upstream nut 33 is a member that is disposed on the upstream side of the plate frame 20 in the airflow direction (upper side in the Y direction) and is attached to the bolt 31.

[0034] The washer 35 is inserted onto the bolt 31 so as to be interposed between the upstream nut 33 and the plate-shaped frame 20. As shown in Fig. 5, the washer 35 has a washer body 35a and an inner peripheral additional portion 35b added to the end portion on the inner peripheral side of the washer body 35a. Fig. 5(a) shows a cross section of the washer 35 before the upstream nut 33 is tightened, and Fig. 5(b) shows a cross section of the washer 35 after the upstream nut 33 is tightened. Note that in Fig. 3, in order to clearly show the entire mounting structure 30 after the upstream nut 33 is tightened, the inner peripheral additional portion 35b and the gap between the through hole 20a and the bolt 31 are omitted.

[0035] The washer body 35a is sandwiched between the upstream nut 33 and the plate-shaped frame 20 to restrict the movement of the upstream nut 33 downstream and prevent air leakage caused by excessive deformation of the inner peripheral additional portion 35b. For this reason, the washer body 35a is made of a material harder than the inner peripheral additional portion 35b, and is preferably made of metal or resin. The washer body 35a is preferably an annular body that is continuous in the circumferential direction.

[0036] As shown in FIG. 5(b), the inner peripheral additional portion 35b is deformed so as to enter the gap between the through hole 20a and the bolt 31 when the washer 35 is sandwiched between the upstream nut 33 and the plate-shaped frame 20. This blocks the gap between the through hole 20a and the bolt 31, and the air on the upstream side cannot pass through the through hole 20a. In this way, the risk of air leakage caused by the through hole 20a being provided in the plate-shaped frame 20 functioning as a partition plate can be prevented. In order to deform when the washer 35 is sandwiched between the upstream nut 33 and the plate-shaped frame 20, the inner peripheral additional portion 35b preferably has a shape that protrudes upstream in the airflow direction from the washer main body 35a, as in the example shown in FIG. 5(a). Even though it has this type of shape, when it is sandwiched between the upstream nut 33 and the plate-shaped frame 20 and deformed, no part of the inner circumference additional portion 35b remains on the upstream side of the washer body 35a, so it is possible to prevent a gap from forming between the upstream nut 33 and the washer body 35a.

[0037] According to an experiment conducted by the inventor, it has been confirmed that air leakage cannot be completely prevented when a general washer without the inner peripheral additional portion 35b is used instead of the washer 35, the air filter 100 is attached to the plate-shaped frame 20, and a liquid sealant is applied to seal the places where air leakage is expected (between the upstream bolt and the washer, and between the plate-shaped frame and the washer) and then hardened. One of the reasons for this is that a certain level of skill is required to apply the liquid sealant so as to prevent air leakage, and it is difficult to know the appropriate range of the amount to be applied, so that the degree to which air leakage can be prevented is thought to be largely dependent on the skill of the worker. According to this embodiment, by using the washer 35 having the inner peripheral additional portion 35b, the effect of preventing air leakage can be obtained regardless of the skill of the worker, regardless of who performs the installation.

[0038] The inner peripheral additional portion 35b, which is deformed by being sandwiched between the upstream nut 33 and the plate-shaped frame 20, is preferably made of an elastic material that restores its original shape when the upstream nut 33 is loosened. The elastic material is preferably an elastomer such as synthetic rubber or natural rubber. As the synthetic rubber, for example, nitrile rubber can be used. A part of the inner peripheral additional portion 35b is embedded in the end portion on the inner peripheral side of the washer body 35a. The washer 35 is preferably a washer called a seal washer.

[0039] According to the casing 1 described above, the manufacturing cost of the casing 1 can be reduced, and air can be prevented from leaking without passing through the air filter 100.

[0040] 3, the upstream nut 33 is preferably a cap nut in which the screw hole 33a to be attached to the bolt 31 is closed on the upstream side in the airflow direction. This makes it possible to prevent air from entering between the upstream nut 33 and the bolt 31 and flowing toward the gap between the through hole 20a and the bolt 31. In this way, by taking multiple measures to block the air flow, the reliability of preventing air leakage can be increased.

[0041] The upstream nut 33 is preferably a flanged nut whose downstream end (seat portion) that abuts against the washer 35 has a flange shape and extends to the outer periphery. The flanged nut has a large contact area with the washer 35, so that it can prevent air from entering between the upstream nut 33 and the washer 35 and flowing toward the through hole 20a and the bolt 31. In this case, the reliability of preventing air leakage can be improved. In addition, even if a washer 35 with a large diameter of the inner peripheral addition portion 35b and a large deformation amount is used, the upstream nut 33 abuts reliably against the washer body 35a, so that excessive deformation of the inner peripheral addition portion 35b can be suppressed. The upstream nut 33 in the example shown in FIG. 3 is a flanged cap nut.

[0042] The mounting structure 30 preferably further includes a pair of downstream nuts 37, 39 that are disposed downstream of the plate-shaped frame 20 in the airflow direction and are attached to the bolt 31 so as to press against each other in the airflow direction. Of the downstream nuts 37, 39, the first nut 37 disposed upstream tightens the bolt 31 by sandwiching the plate-shaped frame 20 between the first nut 37 and the upstream nut 33. Furthermore, the first nut 37 and the second nut 39 disposed downstream of the first nut 37 use a tightening method called the double nut method to press against each other so as to generate a tensile force on the shaft of the bolt 31. With this configuration, even if a force acts on the bolt 31 to rotate around the shaft when replacing the air filter 100, the bolt 31 rotates relative to the upstream nut 33 and the downstream nuts 37, 39, and the upstream nut 33 and the downstream nuts 37, 39 are prevented from loosening. If the upstream nut 33 and the downstream nuts 37, 39 become loose, a gap will be created between the through hole 20a and the bolt 31 that can serve as an entrance for air flowing toward the space between the through hole 20a and the bolt 31, and the effect of preventing air leakage may be compromised.

[0043] FIG. 4 shows an enlarged view of a portion of the mounting structure 30. 4, the inner peripheral end of the first nut 37, in which a screw hole for fitting to the bolt 31 is formed, preferably has a wedge-shaped protrusion 37a that extends in a tapered shape toward the second nut 39, and the second nut 39 preferably has a protrusion receiving recess 39a that is recessed to receive the wedge-shaped protrusion 37a adjacent to the upstream side of the inner peripheral end in which a screw hole for fitting to the bolt 31 is formed. According to this embodiment, the inner peripheral parts of the first nut 37 and the second nut 39 are strongly pressed against the bolt 31 in a direction perpendicular to the axial direction of the bolt 31, thereby achieving a high anti-loosening effect. The downstream nuts 37, 39 in this embodiment are called hard lock nuts. According to an experiment conducted by the inventor, it has been confirmed that the anti-loosening effect of this embodiment when the air filter 100 was replaced 10 times is equivalent to that of a casing using the above-mentioned downstream nuts 37, 39, which are fixed by inserting a bolt into a nut (high nut) fixed to one side of a plate-like frame not having a through hole 20a and pressed against each other using the double nut method. Since the air filter 100 is generally replaced every 2 to 3 years, this embodiment can maintain the anti-loosening effect for a long period of time.

[0044] The mounting structure 30 having the above-described downstream nuts 37, 39 is preferable when it further has a fixing member 41 and a fixing nut 43, as shown in FIG. The fixing member 41 is a member having a generally L-shaped cross section, which is inserted through the bolt 31 and used to sandwich and fix the air filter 100 between the bolt 31 and the plate-shaped frame 20. The fixing member 41 of the example shown in Fig. 3 has a hole 41a through which the bolt 31 is inserted, and also has a recess 41b formed therein for guiding the fixing member 41 so that the upstream end of the fixing member 41 does not shift position relative to the bolt 31 when the fixing member 41 moves along the bolt 31. Fixing nut 43 is disposed downstream of fixing member 41 in the airflow direction, and is attached to bolt 31 . In such a casing 1, when the fixing nut 43 is loosened or tightened during replacement of the air filter 100, a force that rotates the bolt 31 about its axis is likely to act as described above. However, according to the mounting structure 30 having the downstream nuts 37, 39, as described above, the upstream nut 33 and the downstream nuts 37, 39 can be prevented from loosening.

[0045] In this case, it is preferable that the bolt 31 is a stud bolt having both axial ends threaded. The upstream nut 33 is disposed upstream of the air filter 100, whereas the fixing nut 43 is disposed near the downstream end of the air filter 100. Therefore, by using a stud bolt 31 having both axial ends threaded and attaching the fixing nut 43 to the downstream end of the stud bolt 31 and moving (screwing) it upstream, the moving distance of the fixing nut 43 along the shaft of the stud bolt 31 in the airflow direction can be shortened, the air filter 100 can be replaced efficiently, and the burden of working at high altitudes can be reduced.

[0046] Furthermore, it is preferable that the bolt 31 is threaded (threaded) over the entire axial direction of the bolt 31. This allows air filters 100 of various heights in the airflow direction to be sandwiched between the plate-shaped frame 20 and the fixing member 41.

[0047] The washer body 35a is preferably made of metal, and the plate-shaped frame 20 preferably has no coating on the surface facing the washer 35. As described above, painting can be omitted in the casing 1 of this embodiment, and therefore a hard washer body 35a can be used without worrying about damage to the coating, so that the movement of the upstream nut 33 in contact with the washer body 35a toward the downstream side can be reliably stopped.

[0048] The plate frame 20 is rectangular when viewed in the airflow direction, and has at least four through holes 20a. It is preferable that the through holes 20a are formed at least one on each of the four side portions that extend linearly in correspondence with the four sides of the plate frame 20. This allows welding and painting to be omitted in all parts of the plate frame 20 when manufacturing the casing 1, and the effect of reducing the manufacturing cost of the casing 1 is improved. Depending on the size and weight of the air filter 100, the through holes 20a may be formed one on each of the four side portions, or one on each of a pair of opposing side portions among the four side portions, and two on each of the other pair of opposing side portions. When there is one through hole 20a provided in a side portion, it is preferable that it is provided at the center in the length direction of the side portion, and when there are two through holes 20a, it is preferable that they are provided at two positions that divide the side portion into three equal parts in the length direction.

[0049] The hole wall of the plate-like frame 20 in contact with the through hole 20a is preferably a flat cylindrical surface in the airflow direction. This allows the inner peripheral additional portion 35b of the washer 35 to easily enter the gap between the through hole 20a and the bolt 31. If a screw hole for screwing in the bolt 31 is formed in the hole wall, the inner peripheral additional portion 35b will have difficulty entering. The ratio d / D of the hole diameter d of the through hole 20a to the outer diameter D of the shaft of the bolt 31 is preferably 1.02 to 1.20 from the viewpoint of ensuring the ease of entry of the inner peripheral additional portion 35b while avoiding the gap not being filled even when the inner peripheral additional portion 35b enters.

[0050] As shown in Fig. 3, the mounting structure 30 preferably further includes a solidified liquid sealant 45. For example, an acrylate-based, silicone-based, or olefin-based resin sealant can be used as the liquid sealant 45. As shown in Fig. 3, the liquid sealant 45 is applied so as to cover an area including the end faces on the outer circumferential side of the upstream nut 33 and the washer 35, and extending from a part of the surface of the upstream nut 33 to a part of the surface of the plate-shaped frame 20. By sealing the area into which air may enter, the reliability of preventing air leakage can be improved.

[0051] (Air filter) As shown in FIG. 3, the air filter 100 includes an outer frame 110, a filter medium 120 surrounded by the outer frame 110, and a gasket .

[0052] The outer frame 110 has a rectangular shape when viewed in the airflow direction, and is a member that circumferentially surrounds the filter medium 120. The outer frame 110 is made by combining a plurality of plate materials corresponding to each of the four sides. The material of the plate materials is, for example, aluminum or aluminum alloy, stainless steel, or ceramic.

[0053] The gasket 130 is provided on the surface of the outer frame 110 facing the upstream side so as to go all the way around the outer frame 110. The gasket 130 is made of a material that is elastically deformed when sandwiched between the outer frame 110 and the plate-like frame 20. The gasket 130 is made of, for example, a hard foamed polyurethane resin.

[0054] The filter medium 120 is a member that collects fine particles such as dust particles in the gas. The filter medium 120 is, for example, a fibrous body made of glass fiber, silica fiber, or a mixture of these fibers, and has the form of, for example, nonwoven fabric, paper, cotton, or a mat. Specific examples of the filter medium 120 include glass nonwoven fabric, glass filter paper, glass wool, etc., which are made of glass fiber. The filter medium 120 may further contain a binder that bonds the fibers together. In order to ensure a filtering area, the filter medium 120 is preferably pleated and has a zigzag shape in which mountain folds and valley folds are alternately repeated. This increases the amount of air that can be processed, and the filter medium 120 can have a long life.

[0055] The air filter 100 has, for example, the performance of a HEPA (High Efficiency Particulate Air) filter. A HEPA filter is a filter that has a collection efficiency of 99.97% or more for particles with a particle diameter of 0.3 μm at a rated air volume and an initial pressure loss of 245 Pa or less.

[0056] The casing 1 can be used in facilities such as medical facilities, food factories, pharmaceutical factories, and electronic factories.

[0057] (How to install the air filter) The method of mounting the air filter is to mount the air filter to the casing. The casing and the air filter are configured similarly to the casing 1 and the air filter 100 described above.

[0058] Figure 6(a) shows the procedure for inserting bolt 31 into through hole 20a, Figure 6(b) shows the procedure for attaching upstream nut 33 to bolt 31, and Figure 6(c) shows the procedure for tightening second nut 39 of the downstream nut. In FIG. 6, in order to easily explain the procedure, the inner peripheral additional portion 35b of the washer 35, the gap between the through hole 20a and the bolt 31, and the sealant 45 are omitted. In addition, the upstream nut 33 and the washer 35 are shown in Fig. 6(a) in their outer shapes, and in Fig. 6(b) and Fig. 6(c) in their cross sections. The second nut 39 is shown in Fig. 6(a) and Fig. 6(b) in their outer shapes, and in Fig. 6(c) in their cross section.

[0059] The method for attaching an air filter includes a preparation step and a fastening step.

[0060] The preparation step is a step of inserting the bolt 31 into the through hole 20a, and attaching the upstream nut 33 to the bolt 31 on the upstream side of the plate frame 20 in the airflow direction with a washer 35 interposed between the bolt 31 and the plate frame 20. By using the casing 1 having the through hole 20a in the plate frame 20, as described above, welding and painting can be omitted when manufacturing the casing 1, and the manufacturing cost of the casing 1 can be significantly reduced. The upstream nut 33 can be efficiently tightened by applying the first nut 37 to the plate frame 20 as shown in Figures 6(a) and 6(b).

[0061] In the preparation step, it is preferable to attach downstream nuts 37, 39 to bolt 31 before inserting bolt 31 into through hole 20a. In this case, downstream nuts 37, 39 can be attached to the upstream end of bolt 31 and moved (screwed) downstream, so the amount of axial movement (amount screwed) is smaller than when they are attached to the downstream end of bolt 31 and moved (screwed), allowing for efficient work.

[0062] The tightening process is a process in which the washer 35 is sandwiched between the upstream nut 33 and the plate-shaped frame 20, thereby deforming the inner peripheral addition portion 35b so as to enter the gap between the through hole 20a and the bolt 31. When the air filter 100 is attached using a general washer that does not have the inner peripheral addition portion 35b, as described above, a certain level of skill is required to apply the liquid sealant 45, and it is difficult to know the appropriate range of the amount to be applied. In this embodiment, by using the washer 35 that has the inner peripheral addition portion 35b, the effect of preventing air leakage can be obtained regardless of the skill of the worker who attaches the filter.

[0063] According to this method of mounting the air filter, the manufacturing cost of the casing 1 can be reduced, and air can be prevented from leaking without passing through the air filter 100.

[0064] Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various improvements and modifications may be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0065] 1 Casing 10 Casing body 10a Intake port 10b Outlet 11 Top part 12 Side part 20 Plate Frame 20a through hole 30 Mounting structure 31 Volts 33 Upstream nut 33a screw hole 35 Washer 35a Washer body 35b Inner circumference addition 37 First nut (downstream nut) 37a Cuneiform projection 39 Second nut (downstream nut) 39a Protrusion receiving recess 41 Fixing parts 41a hole 41b Recess 43 Fixing nut 45 Sealant 100 Air Filter 110 Outer Frame 120 Filter media 130 Gasket

Claims

1. A casing for housing an air filter and for passing air through the air filter, a casing body having a circumferential inner wall surface surrounding a flow path of air passing through the air filter; a ring-shaped plate-shaped frame that protrudes into the flow path from a position on the inner wall surface midway through the flow path and goes around the inner wall surface, the air filter abutting against the area of ​​the flow path surrounded by the plate-shaped frame from the downstream side in the air flow direction, thereby functioning as a partition plate that prevents air taken into the casing from leaking downstream without passing through the air filter, and the plate-shaped frame having a through hole formed therein that penetrates in the air flow direction; an attachment structure for attaching the air filter to the plate-shaped frame, the attachment structure including: a bolt inserted into the through hole; an upstream nut disposed upstream of the plate-shaped frame in the airflow direction and attached to the bolt; and a washer inserted into the bolt so as to be interposed between the upstream nut and the plate-shaped frame; Equipped with The washer has a washer body and an inner peripheral addition portion added to an end portion on an inner peripheral side of the washer body, The casing is characterized in that the inner peripheral additional portion deforms so as to enter into the gap between the through hole and the bolt when the washer is sandwiched between the upstream nut and the plate-shaped frame.

2. The casing according to claim 1 , wherein the upstream nut is a cap nut having a screw hole into which the bolt is fitted that is closed on the upstream side in the airflow direction.

3. 3. The casing according to claim 1, wherein the upstream nut is a flanged nut having a downstream end that abuts against the washer and that extends radially outward.

4. 3. A casing as described in claim 1 or 2, wherein the mounting structure further includes a pair of downstream nuts arranged downstream of the plate frame in the airflow direction and attached to the bolts so as to press against each other in the airflow direction.

5. An inner peripheral end portion of a first nut disposed on the upstream side among the downstream nuts, in which a screw hole to be attached to the bolt is formed, has a wedge-shaped protrusion extending in a tapered shape toward a second nut disposed on the downstream side among the downstream nuts, 5. The casing according to claim 4, wherein the second nut has a protrusion receiving recess that is recessed to receive the wedge-shaped protrusion, adjacent to the upstream side of an inner circumferential end portion in which a threaded hole for attachment to the bolt is formed.

6. The mounting structure further includes: a fixing member that is inserted through the bolt and that fixes the air filter by sandwiching it between the air filter and the plate-shaped frame; a fixing nut that is disposed downstream of the fixing member in the airflow direction and is attached to the bolt; The casing according to claim 1 or 2, wherein the bolt is threaded over an entire axial length of the bolt.

7. The washer body is made of metal, The casing according to claim 6 , wherein the plate-shaped frame has no coating on a surface facing the washer.

8. The plate-like frame has a rectangular shape when viewed in the airflow direction, A casing as described in claim 1 or 2, wherein when the through hole is referred to as a first through hole, the plate-shaped frame further has at least three second through holes, and at least one through hole is formed in each of four edge portions extending in a straight line corresponding to the four sides of the plate-shaped frame.

9. 1. A mounting structure for mounting an air filter to a casing that houses an air filter and allows air to pass through the air filter, comprising: The casing comprises: a casing body having a circumferential inner wall surface surrounding a flow path of air passing through the air filter; a ring-shaped plate-shaped frame that protrudes into the flow path from a position on the inner wall surface midway through the flow path and goes around the inner wall surface, the air filter abutting against the area of ​​the flow path surrounded by the plate-shaped frame from the downstream side in the air flow direction, thereby functioning as a partition plate that prevents air taken into the casing from leaking downstream without passing through the air filter, and the plate-shaped frame having a through hole formed therein that penetrates in the air flow direction; an attachment structure for attaching the air filter to the plate-shaped frame, the attachment structure including: a bolt inserted into the through hole; an upstream nut disposed upstream of the plate-shaped frame in the airflow direction and attached to the bolt; and a washer inserted into the bolt so as to be interposed between the upstream nut and the plate-shaped frame; Equipped with The washer has a washer body and an inner peripheral addition portion added to an end portion on an inner peripheral side of the washer body, an air filter mounting structure, characterized in that the inner peripheral additional portion deforms so as to enter into the gap between the through hole and the bolt when the washer is sandwiched between the upstream nut and the plate-shaped frame.

10. A method for mounting an air filter to a casing according to claim 1 or 2, comprising the steps of: a preparation step of inserting the bolt into the through hole, and attaching the upstream nut to the bolt with the washer interposed between the bolt and the plate-shaped frame on the upstream side of the plate-shaped frame in the airflow direction; and a tightening process for deforming the inner peripheral addition portion so that it enters into the gap between the through hole and the bolt by sandwiching the washer between the upstream nut and the plate-shaped frame.

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