JP6788382B2 - Air filter - Google Patents

Description

The present invention relates to an air filter capable of preventing insects from invading the filtered fluid.

Buildings such as buildings and factories may be equipped with an air filter that takes in outside air and removes fine particles such as dust contained in the outside air. Such an air filter generally includes a filter medium that collects fine particles in a gas, and a frame that surrounds the filter medium from the outer peripheral side and holds the filter medium. The air filter is installed, for example, at an installation location in the middle of a duct that takes in outside air into the building.

As an air filter, for example, a pre-filter used for removing relatively large-sized particles is generally installed near the outside air intake of a duct, and is therefore susceptible to insect invasion. Therefore, the pre-filter is also required to prevent insects from passing through to the downstream side. Such invasion of insects occurs more often in the gap between the outer peripheral portion of the filter medium and the frame than in the central portion in the plane direction of the filter medium (extending direction of the filter medium). This is because when the insect reaches the surface of the filter medium, it moves to the outer peripheral side on the surface of the filter medium and reaches the end on the outer peripheral side, rather than directly entering the filter medium having high resistance due to the fiber structure, and then resists more. It is considered that this is because it tries to invade the gap between the small filter medium and the frame or the inside of the outer peripheral portion of the filter medium.
As a conventional air filter, among the parts constituting the frame, the side wall on the inflow surface side of the filter frame and the side wall on the outflow surface side of the side wall on the outflow surface side are provided with protruding portions protruding toward the inflow surface side to flow out. It is known that a support for supporting the filter medium is arranged between the side wall on the surface side and the protruding portion (see Patent Document 1). In the air filter of Patent Document 1, even when the support is arranged on the surface of the side wall on the outflow surface side on the inflow surface side, the filter medium is arranged in contact with the side wall on the inflow surface side and the protruding portion. It is said that it is possible to prevent the formation of voids between the filter frame and the filter medium.
Further, as a conventional air filter, one in which an insect repellent net is arranged on the upstream side or the downstream side of a frame constituting the air filter is known (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2013-208525 Japanese Unexamined Patent Publication No. 2014-039922

However, the air filter of Patent Document 1 cannot reliably prevent the invasion of insects between the filter medium and the frame. Further, in the air filter of Patent Document 2, the end portion on the outer peripheral side of the insect repellent net may be peeled off from the frame, and a gap may be formed between the insect repellent net and the frame, and insects may invade from there.

An object of the present invention is to provide an air filter capable of reliably preventing insects from invading between the filter medium for an air filter and the frame body.

One aspect of the present invention is an air filter.
Filter media for filters that collect fine particles in gas,
An outer frame that surrounds the filter medium for the filter from the outer peripheral side and is open so that the gas passes through the filter medium for the filter.
It is provided with an inner frame which is arranged inside the outer peripheral end portion of the outer frame and is an integral member formed in a circumferential shape along the outer frame.
The outer frame has a first wall portion that supports an end portion on the outer peripheral side of the filter medium for the filter from a first side that is one side in the direction in which the gas passes through the filter medium for the filter.
The inner frame is compressed by pressing the outer peripheral end of the filter filter medium from the first side and the second side opposite to the gas passing direction against the first wall side. It has a pressing portion and a locking portion that locks the inner frame to the outer frame so that the gas does not move in the direction in which the gas passes with respect to the outer frame in the pressed state in which the filter medium for the filter is pressed. And
The inner frame is different from the first portion and the second portion, which are two portions located in the middle of the circumference of the member and extend in parallel with each other, and the first portion and the second portion. It has a third part located in the middle of the circumference of the member,
The third portion has a shape curved so as to bulge toward the second side with respect to a plane including a direction in which the first portion and the second portion extend along the circumferential shape.
The third portion is characterized in that, in the pressed state, it is elastically deformed so as to extend in the plane.
Another aspect of the present invention is an air filter.
Filter media for filters that collect fine particles in gas,
An outer frame that surrounds the filter medium for the filter from the outer peripheral side and is open so that the gas passes through the filter medium for the filter.
Before being placed on the inside of the outer edge portion of the Kigaiwaku, and a inner frame is a member integrally formed circumferentially along the outer frame,
The outer frame has a first wall portion that supports an end portion on the outer peripheral side of the filter medium for the filter from a first side that is one side in the direction in which the gas passes through the filter medium for the filter.
The inner frame is compressed by pressing the outer peripheral end of the filter filter medium from the first side and the second side opposite to the gas passing direction against the first wall side. It has a pressing portion and a locking portion that locks the inner frame to the outer frame so that the gas does not move in the direction in which the gas passes with respect to the outer frame in the pressed state in which the filter medium for the filter is pressed. And
The pressing portion has a wall portion extending toward the first wall portion in a direction in which the gas passes through the filter medium for the filter over the entire circumference of the inner frame.
The tip of the wall portion in the extending direction comes into contact with the filter medium for the filter in the pressed state on at least a part of the circumference of the inner frame.
The air filter is an insect repellent net that prevents insects from passing through, and further includes a sheet-shaped insect repellent net whose outer peripheral end is surrounded by the outer frame.
The insect net is arranged so as to be located along the extending direction of the filter medium for the filter and in the central region between both ends in the thickness direction of the filter medium for the filter.
Yet another aspect of the present invention is an air filter.
Filter media for filters that collect fine particles in gas,
An outer frame that surrounds the filter medium for the filter from the outer peripheral side and is open so that the gas passes through the filter medium for the filter.
Before being placed on the inside of the outer edge portion of the Kigaiwaku, and a inner frame is a member integrally formed circumferentially along the outer frame,
The outer frame has a first wall portion that supports an end portion on the outer peripheral side of the filter medium for the filter from a first side that is one side in the direction in which the gas passes through the filter medium for the filter.
The inner frame is compressed by pressing the outer peripheral end of the filter filter medium from the first side and the second side opposite to the gas passing direction against the first wall side. It has a pressing portion and a locking portion that locks the inner frame to the outer frame so that the gas does not move in the direction in which the gas passes with respect to the outer frame in the pressed state in which the filter medium for the filter is pressed. And
The pressing portion has a wall portion extending toward the first wall portion in a direction in which the gas passes through the filter medium for the filter over the entire circumference of the inner frame.
The tip of the wall portion in the extending direction comes into contact with the filter medium for the filter in the pressed state on at least a part of the circumference of the inner frame.
The air filter is further provided with a support member that supports the portion of the filter medium for the filter exposed to the first side inside the inner peripheral side end portion of the outer frame from the first side. To do.

The pressing portion of the inner frame is formed so as to extend toward the first wall portion of the outer frame so as to abut the filter medium for the filter in a circumferential shape.
The first wall portion faces the tip of the pressing portion that comes into contact with the filter medium for the filter in the direction in which the gas passes, and the distance between the first wall portion and the tip of the pressing portion is 0 mm. It is preferably over 18.0 mm or less.

The locking portion of the inner frame has a member to be operated having a protruding portion protruding toward the outer frame when operated in the pressed state.
It is preferable that the end of the outer frame forming the opening has a wall surface facing the inner frame side and having a hole in which the projecting portion enters.

The locking portion of the inner frame forms the second end of the inner frame.
It is preferable that the end of the outer frame on the second side is located at the same position as the locking portion in the direction in which the gas passes, or is located on the second side of the locking portion.

The outer frame further has a second wall portion facing the first wall portion, and the outer peripheral end portion of the filter medium for the filter includes the first wall portion and the second wall portion. Placed between
The inner frame is two portions located in the middle of the circumference of the member, and has a first portion and a second portion extending in parallel with each other, and the first portion and the second portion. Each of the claws extends to the side of the outer frame, and has a claw portion arranged between the second wall portion and the first wall portion in the pressed state.
It is preferable that the inner frame is locked to the outer frame by abutting the second side portion of the claw portion with the second wall portion from the first side.

The length of the claw portion of the first portion extending to the side of the outer frame is preferably longer than the length of the claw portion of the second portion extending to the side of the outer frame.

The inner frame further has a third portion located in the middle of the circumference of the member, which is different from the first portion and the second portion.
The third portion has a shape curved so as to bulge toward the second side with respect to a plane including a direction in which the first portion and the second portion extend along the circumferential shape.
It is preferable that the third portion is elastically deformed so as to extend in the plane in the pressed state.

Further, it is an insect repellent net that prevents insects from passing through, and is provided with a sheet-shaped insect repellent net whose outer peripheral end is surrounded by the outer frame.
The insect repellent net is preferably arranged so as to be located along the extending direction of the filter medium for the filter and in the central region between both ends in the thickness direction of the filter medium for the filter.

The filter medium for a filter has a first filter medium element arranged on the first side of the insect screen and a second filter medium element arranged on the second side of the insect screen.
It is preferable that the first filter medium element has a smaller thickness in the direction in which the gas passes than the second filter medium element.

It is preferable that the ends of the first filter medium element, the insect repellent net, and the second filter medium element are connected to each other on the outer peripheral side.

Further, a support member may be provided to support the portion of the filter medium for the filter exposed in the opening from the first side.

According to the present invention, it is possible to reliably prevent insects from invading between the filter medium for the air filter and the frame.

It is an exploded perspective view of the air filter of 1st Embodiment. It is a perspective view of the main part of the outer frame which also shows the cross section taken along line AA of FIG. It is the main part perspective view of the inner frame which also shows the cross section of BB line of FIG. It is a main part perspective view which shows the state which the inner frame is locked to the outer frame in the pressed state. It is sectional drawing of the main part explaining the invasion route of an insect in an air filter. It is an exploded perspective view of the air filter of the 2nd Embodiment. It is a perspective view explaining an example of how to assemble the air filter of FIG. As the cross section of the air filter, the C-C line cross section of the outer frame and the C'-C' line cross section of the inner frame shown in FIG. 6 are shown together. As the cross section of the air filter, the cross section of the DD line shown in FIG. 6 and the cross section of the inner frame along the D'-D'line are shown together. As a cross section of the air filter, it is a figure which shows the EE line cross section of the outer frame and the E'-E' line cross section of an inner frame together shown in FIG. It is a side view which shows the modification of the inner frame in the Z direction.

Hereinafter, the air filter of the present invention will be described in detail.
FIG. 1 shows an exploded perspective view of the air filter 1 of the first embodiment.
The air filter 1 includes a filter medium for a filter (hereinafter referred to as a filter medium) 3, an insect repellent net 4, an outer frame 5, and an inner frame 11. The filter medium 3 is for collecting fine particles in a gas. The insect net 4 is a sheet-like member that prevents insects from passing through. The outer frame 5 is a rectangular (including a square in the following description) shaped member that surrounds the filter medium 3 and the insect repellent net 4 from the outer peripheral side, and has an opening 10 that is opened so that the gas passes through the filter medium 3. There is. The inner frame 11 is a rectangular member arranged inside the opening 10 of the outer frame 5, and has a pressing portion and a locking portion described later. In FIG. 1, the holes in the outer frame 5 (described later) and the locking portions of the inner frame 11 (described later) are not shown.

(Filter material)
The filter medium 3 is, for example, a filter medium for a pre-filter used for removing dust having a particle size of 5 μm or more and a concentration of 0.4 to 7 mg / m ³ . As a filter medium for a pre-filter, the collection efficiency is either 70 to 90% by the mass method or 5 to 10% by the counting method, the pressure loss is 20 to 196 Pa, and the dust holding capacity is 300 to 2000 g / m. ^The one which is ³ is used. In measuring the collection efficiency, in the mass method, 15 kinds of powders specified in JIS Z8901 or dust specified by the American Society for Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) are used. In the counting method, particles of atmospheric dust, polyalphaolefin (PAO), or silica having a particle size of 0.3 μm are used. The dust holding capacity is the amount of dust collected by the filter medium before reaching a predetermined final pressure loss.

The performance of the filter medium 3 is not limited to those described above, and may be any of a medium performance filter, a quasi-HEPA filter, a HEPA filter, a ULPA filter, and the like. The ULPA (Ultra Low Penetration Air) filter is a filter having a collection efficiency of 99.9995% or more for particles having a particle size of 0.15 μm at a rated air volume and an initial pressure loss of 245 Pa or less. The HEPA (High Efficiency Particulate Air) filter is a filter having a collection efficiency of 99.97% or more for particles having a particle size of 0.3 μm at a rated air volume and an initial pressure loss of 245 Pa or less. The quasi-HEPA filter is, for example, a filter having a collection efficiency of about 90% or more and less than 99.97% with respect to particles having a particle size of 0.3 μm. The medium performance filter is a filter having a medium particle collection rate mainly for particles having a particle size smaller than 5 μm.

As the filter medium for the pre-filter, specifically, a mat-like or felt-like filter medium using glass fiber (wet non-woven fabric, long fiber, short fiber) or synthetic fiber as a fiber material is used. As the filter medium for the pre-filter, for example, those manufactured by spun bond, melt blow, thermal bond, or chemical bond can be used. Such a filter medium for a pre-filter can be compressed in the thickness direction. The filter medium for the pre-filter may be an electret-treated one in order to impart the collection performance by charging the fibers of the filter medium to the original collection performance of the filter medium. Further, the filter medium for the pre-filter may be one that has been subjected to an antibacterial treatment in which an antibacterial agent is attached to the filter medium in order to impart antibacterial performance. The electret treatment and the antibacterial treatment may be applied in combination.
The filter medium 3 may be composed of one layer in the thickness direction, or may be composed of a plurality of layers. Examples of the filter medium 3 composed of a plurality of layers include a filter medium having a plurality of filter medium sheets, which will be described later. The plurality of layers may be made of the same type of fiber material or may be made of different types of fiber material.

The thickness of the filter medium 3 can be determined in consideration of the length (height) of the outer frame 5 in the airflow direction, the required collection performance of the filter medium 3, and the filter life. When used as a filter medium for a pre-filter, for example, It is 5 to 20 mm. The thickness of the filter medium 3 is not limited to this range, and may be, for example, more than 0 mm and 5 mm or less, or more than 20 mm. The thickness of the filter medium 3 refers to the total thickness of the filter medium sheets when a plurality of filter medium sheets are arranged on both sides of the insect screen 4 in the airflow direction as described later. The basis weight of the filter medium 3 can be determined in consideration of the required collection performance of the filter medium 3 and the filter life, and when used as a filter medium for a pre-filter, it is, for example, 100 to 800 g / m ² . The fiber diameter of the filter medium 3 can be adjusted in consideration of the required collection performance of the filter medium 3, and when used as a filter medium for a pre-filter, it is, for example, 30 to 60 μm.

(Insect repellent net)
By providing the insect repellent net 4, the air filter 1 moves in the central region of the filter medium 3 in the plane direction and tries to pass through the filter medium 3 while receiving resistance due to the fiber structure of the filter medium 3. Can be captured. In the present specification, the plane direction means a direction in which a plane orthogonal to the airflow direction extends, and may be referred to as an extension direction of the filter medium 3. Further, the airflow direction means the direction of the gas passing through the filter medium 3, and corresponds to the vertical direction of FIG. 1 and the X direction of FIGS. 6 and 7. In addition, in the present specification, the term "insect" means the Western flower thrips, unless otherwise specified. The air filter 1 may be used to prevent the invasion of other types of thrips and insects other than thrips.

The insect net 4 may be a net such as a woven fabric or a knit as long as it can prevent the passage of insects, and a non-woven fabric, an expander, a punching or the like other than the net may be used. You can also. The size of the average opening diameter of the woven fabric or knitted fabric is not particularly limited, but is a size that can prevent insects from passing through the woven fabric or knitted fabric, and is appropriately adjusted according to the required value of ventilation resistance. Is preferable. Specifically, it is preferably 0.1 mm or more and less than 1 mm. The average pore size is determined by measuring the area of the hole in the insect net 4 using, for example, a scanning electron microscope (SEM) and using the diameter of a circle having the same area as the hole diameter. It refers to the average value of n (n = 5 or more) opening diameters of the net 4. The pore opening ratio is preferably 30 to 70% from the viewpoint of insect repellent and ventilation. The aperture ratio is the ratio of the total area of the openings to the area of the insect net in the plane direction. As a preferable insect repellent net 4 when a net body using an organic material as a fiber material, which will be described later, is used, for example, a net having a diameter of 30 mesh, specifically, an average opening diameter of 0.77 mm, a wire diameter φ of 0.17 mm, and an opening. Examples thereof include those having a pore ratio of about 37% and a thickness of 0.3 mm.
The fiber component of the net body constituting the insect repellent net 4 is not particularly limited, and for example, polyolefin-based resin (polyethylene, polypropylene, polymethylpentene, etc.), styrene-based resin, polyvinyl alcohol-based resin, polyether-based resin (polyetherether). Ketones, polyacetals, modified polyphenylene ethers, aromatic polyetherketones, etc.), polyester resins (polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylates, total aromatic polyesters Resins), polyimide resins, polyamideimide resins, polyamide resins (eg, aromatic polyamide resin, aromatic polyetheramide resin, nylon resin, etc.), resins with nitrile groups (eg, polyacrylonitrile, etc.), urethane-based Known organic polymers such as resins, epoxy resins, polysulfone resins (polysulfone, polyethersulfone, etc.), fluorine resins (polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzoimidazole resins, metal alkoxides. Polymers formed by polymerizing known inorganic compounds such as methoxydos such as silicon, aluminum, titanium, zirconium, boron, tin and zinc, ethoxydo, propoxide, butoxide, etc., or metals and glass. Inorganic materials such as can be used.

The insect repellent net 4 is preferably arranged so as to be located along the extending direction of the filter medium 3 and in the central region between both ends in the thickness direction of the filter medium 3. The reason for this is that when the insect repellent net 4 is arranged so as to cover the opening 10 on the outside of the outer frame 5, and the outer peripheral end of the insect repellent net 4 is adhered to the outer frame 5, the insect repellent net 4 This is because the end portion on the outer peripheral side is easily peeled off from the outer frame 5, so that a gap is formed between the insect net 4 and the outer frame 5 and insects may invade. When the insect repellent net 4 is arranged in the central region of the filter medium 3, the filter medium 3 has, for example, a first filter medium sheet 3a (first filter medium element) and a second filter medium sheet 3b (second filter medium element). , The insect screen 4 is inserted between the first filter medium sheet 3a and the second filter medium sheet 3b. As the first filter medium sheet 3a and the second filter medium sheet 3b, those previously formed can be preferably used. As described above, since the first filter medium sheet 3a is arranged on the upstream side (first side) of the insect repellent net 4, the pressing portion of the inner frame 11 comes into direct contact with the insect repellent net 4 and the insect repellent net 4 Further, the second filter medium sheet 3b is arranged on the downstream side (second side) of the insect repellent net 4, so that the mesh of the insect repellent net 4 can be prevented from expanding. Dust in the gas can be collected, and in particular, the gas contaminated by the decomposition products of insect feces and carcasses captured by the insect net 4 can be suppressed from flowing out to the downstream side of the air filter 1. From such a viewpoint, it is preferable that the thickness of the first filter medium sheet 3a is smaller than the thickness of the second filter medium sheet 3b. The reason for this is that in the assembled air filter 1, the distance in the airflow direction between the tip of the inner frame 11 (pressing portion) described later and the wall portion 6 (first wall portion) of the outer frame 5 is limited. This is because it is desirable to sufficiently collect dust in the gas on the downstream side of the insect screen 4 while the thickness of the filter medium 3 is limited. Even if the thickness of the first filter medium sheet 3a is small, it is considered that the first filter medium sheet 3a can serve as a cushioning material for avoiding direct contact between the inner frame 11 and the insect net 4, and the material and thickness of the first filter medium sheet 3a and the like. Can also be adjusted from the viewpoint of ensuring the function as a cushioning material. The first filter medium sheet 3a and the second filter medium sheet 3b may be of the same type, but different types may be used.

It is preferable that the ends of the first filter medium sheet 3a, the insect repellent net 4, and the second filter medium sheet 3b are connected to each other on the outer peripheral side. As a result, it is possible to prevent these members 3a, 4 and 3b from shifting from each other in the plane direction, and by handling these members 3a, 4 and 3b as a unit, the filter medium 3 and the insect repellent net 4 can be attached at the time of replacement, etc. Can be easily performed. The connection positions of these members 3a, 4 and 3b are preferably positions between the portion of the filter medium 3 pressed by the pressing portion and the outer peripheral end of the filter medium 3. The ends of the first filter medium sheet 3a, the insect screen 4, and the second filter medium sheet 3b on the outer peripheral side can be connected to each other, for example, by sewing them together. The sewing method is not particularly limited, and for example, parallel stitching, reverse stitching, star stopper and the like are used, but reverse stitching is preferable from the viewpoint of cutting off the invasion path of insects. The connection positions of these members 3a, 4 and 3b are preferably on the outer peripheral side of the position where the pressing portion of the inner frame 11 abuts.
Further, among the first filter medium sheet 3a, the insect repellent net 4, and the second filter medium sheet 3b, the edges of the outer peripheral portions of the insect repellent net 4 and the second filter medium sheet 3b excluding the first filter medium sheet 3a Is also preferably connected. In this case, the insect repellent net 4 and the second filter medium sheet 3b can be prevented from being displaced from each other in the plane direction, and these members 4 and 3b can be handled as one, so that the filter medium 3 and the insect repellent net 4 can be attached at the time of replacement. Can be easily performed. Further, the first filter medium sheet 3a was taken out separately from the insect repellent net 4 and the second filter medium sheet 3b, and was captured on the upstream side of the insect repellent net 4 or the insect repellent net 4 for cleaning the first filter medium sheet 3a and the like. The work of removing insects can be easily performed.

(Outer frame)
The outer frame 5 is manufactured by, for example, combining four frame members constituting each side of a rectangular shape, and the ends of the frame members in the longitudinal direction are joined to each other. The frame material is made of, for example, a metal material such as a galvanized iron plate, a stainless steel plate, or an aluminum plate, or a resin material. The outer frame 5 made of an aluminum plate may be one in which four frame materials are integrally molded. The outer frame 5 can be produced, for example, by bending a single flat plate cut into a predetermined outer shape.
As shown in FIG. 2, the outer frame 5 has a wall portion 6, a wall portion 7, a wall portion 8, and a wall portion 9, and these wall portions 6 to 9 are in the width direction (short direction). It has a shape that is connected side by side in series. FIG. 2 is a perspective view of a main part of the outer frame 5 showing the cross section taken along the line AA of FIG. Each wall portion 6 to 9 is a plate-shaped portion extending in the long side direction on each side of the outer frame 5 having a rectangular shape. The connection points of the wall portions 6 to 9 with the adjacent wall portions are at right angles in the cross section of FIG.

The wall portion 6 is a portion (first wall portion) that supports an end portion (outer peripheral portion) on the outer peripheral side of the filter medium 3 from the downstream side (first side) in the airflow direction. The wall portion 6 is arranged in a region including a plane position facing the tip of the pressing portion (wall portion 12 described later) of the inner frame 11 in the airflow direction, and is located on the downstream side of the inner frame 5 via the filter medium 3 and the insect net 4. Receives pressure contact force to. Further, the wall portion 6 forms an end on the downstream side of the opening 10.
The wall portion 6 may have ribs (not shown) capable of further compressing the portion of the filter medium 3 pressed by the inner frame 11 and compressed in the thickness direction in the plane direction. Specifically, such ribs are provided along the long side direction of the wall portion 6 at two locations separated from each other in the plane direction at the position of the wall portion 6 of the outer frame 5 facing the pressing portion 12 of the inner frame 11. Is formed to extend. The height of the rib is determined in consideration of the material and thickness of the filter medium 3. The rib may be formed on another member attached to the wall portion 6, or may be formed on a frame member constituting the wall portion 6.
The wall portion 7 is a portion facing the outer peripheral end of the filter medium 3 and extends in the airflow direction.
The wall portion 8 is a portion facing the upstream side (second side) end of the outer peripheral portion of the filter medium 3.

The wall portion 9 is a portion forming the upstream end of the opening 10 and is in contact with the space inside the opening 10 (hereinafter referred to as the inside of the opening 10) along the plane direction of the air filter 1 with the wall surface 9a. The inner frame 11 has a hole 9b into which a protruding portion of a fastener described later can be inserted. For example, two holes 9b are provided on each side of the outer frame 5, but the number of holes 9b is not limited to two, and one or three or more holes 9b are provided depending on the number of locking portions on each side of the inner frame 11. It may be provided. When a plurality of holes 9b are provided on each side, it is preferable that the holes 9b are provided one by one in a region in which each wall portion 9 is divided into a plurality of the same length in the long side direction. When one hole 9b is provided on each side, it is preferable that the hole 9b is provided at an intermediate point in the long side direction of each wall portion 9.
It is preferable that the upstream end of the inner frame 11 is not located upstream of the upstream end of the outer frame 5 (the surface on the upstream side of the wall 8) in the hole 9b in the state where the protruding portion is inserted. .. By locating the upstream end of the inner frame 11 at the same airflow direction position or downstream side as the upstream end of the outer frame 5, the air filter 1 is attached to, for example, a casing in the middle of the duct. It is possible to prevent the inner frame 11 from hitting the portion (not shown) of the casing that receives the end in the airflow direction of 1 to form a gap that causes a leak between the casing and the outer frame 5.

(The inner frame)
The inner frame 11 is an integral member formed in a circumferential shape along the wall portion 9 of the outer frame 5. It is preferable that the inner frame 11 has an outer shape such that a slight gap (several mm) is formed in the plane direction between the inner frame 11 and the wall portion 9 in a state of being arranged inside the opening 10. As a result, the inner frame 11 can be easily arranged in the opening 10, and the inner frame 11 can be easily positioned in the plane direction with respect to the outer frame 5. The inner frame 11 can be manufactured, for example, by using a single flat plate that has been cut to form a predetermined outer shape. In the predetermined outer shape, the portions to be the four pressing portions 12 (described later) corresponding to the four sides of the rectangular shape are connected in series in the long side direction, and the four wall portions 13 (described later) are connected to each of these portions. One of the portions is connected in the lateral direction. A single flat plate having such an outer shape is bent at a connection point between the pressing portions 12 to form a rectangular shape, and both ends of the single flat plate in the long side direction are connected by rivets and the opening 10 is formed. By bending the portion to be the wall portion 13 with respect to the pressing portion 12 so as to form the end on the upstream side, an integral member having no gap in the circumferential direction can be manufactured. In one flat plate, the portion to be the wall portion 13 is cut so that both ends in the long side direction are chamfered (cornered) at an inclination of 45 ° with respect to the long side direction. Specifically, in one flat plate, the portion to be the wall portion 13 has a trapezoidal shape with the position connected to the pressing portion 12 as the base and the end farthest from the pressing portion 12 as the upper side. As a result, when the portion to be the wall portion 13 is bent with respect to the pressing portion 12, the adjacent wall portions 13 can come into contact with each other without overlapping in the thickness direction and without a gap. The frame material is made of, for example, a metal material such as a galvanized iron plate, a stainless steel plate, or an aluminum plate, or a resin material. The outer frame 5 made of an aluminum plate may be one in which four frame materials are integrally molded.
The inner frame 11 is not particularly limited as long as it is formed in a circumferential shape along the end of the outer frame 5 forming the opening 10. For example, the inner frame 11 is large enough to prevent insects from passing through the four frame materials. It may be arranged with a gap (for example, 0.1 to 1.0 mm). In this case, the ends of the frame members connected so as to be orthogonal to each other are connected to each other by using, for example, a metal fitting having a substantially L-shaped cross section.

As shown in FIG. 3, the inner frame 11 has a wall portion 12, a wall portion 13, and a locking portion 15. Of these, the wall portion 12 functions as a pressing portion and is also referred to as a pressing portion 12. Note that FIG. 3 is a perspective view of a main part of the inner frame 11 showing the cross section of the line BB of FIG. 1 together. The two wall portions 12 and 13 are plate-shaped portions extending in the long side direction on each side of the inner frame 11 having a rectangular shape. The wall portion 13 is a portion extending in the airflow direction. The wall portions 12 and 13 are connected so as to form a right angle in the cross section of FIG.

The pressing portion 12 has a function of pressing the outer peripheral side ends of the filter medium 3 and the insect net 4 from the upstream side against the wall portion 6 side of the outer frame 5 and compressing them in the thickness direction at the portion where the pressing portion 12 abuts. Have. Specifically, the pressing portion 12 is formed so as to extend toward the wall portion 6 side of the outer frame 5 so as to contact the filter medium 3 in a circumferential shape, and the lengths in the width direction (air flow direction) become equal over the entire circumference. ing. By the above-mentioned function of the pressing portion 12, in the illustrated example, the filter medium 3 is crushed to the extent that the collecting performance of the pressed portion is impaired, and the air filter 1 is in the pressed state. In the pressed state, there is no gap between the pressing portion 12 and the filter medium 3, and since the filter medium 3 is crushed, insects can pass from the inside to the outside of the inner frame 11 in the plane direction, for example. It is not possible, and as shown in FIG. 5, the invasion route of insects can be cut off.
FIG. 5 is a cross-sectional view of a main part for explaining the invasion route of insects in the air filter 1. In the air filter 1, it is conceivable that insects invade from the upstream side through the space between the wall portion 13 of the inner frame 11 and the filter medium 3 and move along the path shown by the thick solid line P in FIG. Here, in the conventional air filter not provided with the inner frame 11, the insect moves on the surface on the upstream side of the filter medium 3 to the outer peripheral side of the filter medium 3 and reaches the outer peripheral side end of the filter medium 3, and then the filter medium 3 And the gap between the wall portion 6 of the outer frame 5 or the inside of the filter medium 3, there is a possibility that the air filter may pass through to the downstream side of the air filter. In the air filter 1 of the first embodiment, the filter medium 3 is pressed against the outer frame 5 side by the inner frame 11 to be compressed, so that the passage of such insects from the outer peripheral end of the filter medium 3 can be suppressed. .. As a result, the number of insects that collect in the vicinity of the outer peripheral end of the filter medium 3 in the airflow direction region in the outer frame 5 is reduced, and the vicinity of the outer peripheral end of the filter medium 3 becomes the outer frame 5 and the inner frame 11. By being surrounded and difficult to see from the outside, it is possible to prevent the viewer from giving an unsanitary impression. Further, in the air filter 1 of the first embodiment, the filter medium 3 is pressed against the outer frame 5 side by the inner frame 11 and compressed, so that the inside of the inner frame 11 (inside in the plane direction) along the solid line P from the upstream side. It is possible to cut off the invasion route of the insects that have entered from the inside and prevent the insects from moving to the outside of the inner frame 11 as shown by the broken line P'. As a result, it is possible to reduce the number of insects that try to get into the gap between the filter medium 3 and the wall portion 6 of the outer frame 5 or the inside of the filter medium 3 from the outer peripheral end of the filter medium 3.
The distance between the tip 12a of the pressing portion 12 and the wall portion 6 of the outer frame 5 in the pressed state is determined in consideration of the material and thickness of the filter medium 3, and is preferably more than 0 mm and 7.0 mm or less. For example, it is adjusted to 4 to 7 mm. Further, the end surface of the tip 12a of the pressing portion 12 is preferably flat, but for example, it hits the filter medium 3 in the pressed state due to having minute irregularities due to the processing marks formed at the time of producing the frame material. A non-contact area may be partially formed.

The locking portion 15 has a function of locking the inner frame 11 to the outer frame 5 so that the inner frame 11 does not move in the airflow direction with respect to the outer frame 5 in the pressed state. Specifically, the locking portion 15 has a fastener 16 (operated member) and a pin 17. The fastener 16 is attached to the upper surface (upstream side surface) of the wall portion 13 by a pin 17, and can be rotated by, for example, manually operating as shown by the bidirectional arrow in FIG. The fastener 16 has a protruding portion 16a in which a part of the outer peripheral portion projects outward. In the pressed state, the fastener 16 is rotated so that the protruding portion 16a protrudes toward the outer frame 5, so that the protruding portion 16a enters the hole 9b of the wall portion 9 of the outer frame 5. The inner frame 11 is locked to the outer frame 5. In the pressed state, the repulsive force that the pressed filter medium 3 tries to restore to the upstream side along the thickness direction acts on the inner frame 11, but the inner frame 11 is locked to the outer frame 5 so that the filter medium 3 is locked. It is possible to prevent the outer frame 5 from moving so as to float upstream with respect to the outer frame 5 due to the repulsive force of. The locking portion 15 is provided at a position corresponding to the position of the hole 9b of the outer frame 5 on each side of the inner frame 11. The locking portion 15 forms an upstream end of the inner frame 11, and the upstream end thereof is located at the same position in the airflow direction as the upstream surface of the wall portion 8 of the outer frame 5, or a wall. It is preferably located on the downstream side of the surface on the upstream side of the portion 8.

An urging member (not shown) such as a spring washer or a coil spring may be arranged between the fastener 16 and the wall portion 13 so as to be inserted through the pin 17, for example. By urging the fastener 16 and the wall portion 13 so as to be separated from each other by the urging member, the urging member can be removed even when the repulsive force of the pressed filter medium 3 becomes smaller with time, for example. Sufficient force is secured to press the wall portion 13 together with the pressing portion 12 toward the filter medium 3, and it is more reliable to prevent a gap from being formed between the pressing portion 12 and the filter medium 3 or between the filter medium 3 and the wall portion 6. Can be done.
Although two locking portions 15 are provided on each side of the inner frame 11, the number of locking portions 15 is not limited to two, and can be adjusted in consideration of the dimensions of the air filter 1, and one or three. The above may be provided.

The air filter 1 may further include a support member (not shown) that supports the portion of the filter medium 3 exposed to the downstream side in the opening 10 from the downstream side. Examples of the support member include a sheet-like member such as a wire mesh, a stay provided so as to connect opposite ends on the downstream side of the opening 10. The sheet-like member is arranged between the wall portion 6 of the outer frame 5 and the filter medium 3. As the sheet-shaped member, for example, a member having an average opening diameter larger than that of the above-mentioned insect repellent net 4 can be used. As the stay, for example, a plurality of rod-shaped members arranged in a plane direction at substantially equal intervals can be used. The stay is connected to the wall portion 6 of the outer frame 5 and is provided so as to cross the space forming the downstream end of the opening 10. By providing such a support member, it is possible to apply a pressure contact force from the downstream side to the filter medium 3 which is pressed against the pressing portion 12 and tends to project from the inside of the inner frame 11 to the downstream side. Further, by providing the support member, it is possible to prevent the filter medium 3 from coming off the outer frame 5 and coming out to the downstream side due to the high velocity of the air flow or the like.

The air filter 1 of the first embodiment can be attached to a predetermined installation location of a duct provided in a building such as a building or a factory. A gasket may be provided on the wall portion forming the upstream or downstream end of the air filter 1 to prevent leakage between the mounting location of the casing and the air filter 1. The gasket is made of, for example, polyurethane foam, rubber, or the like. Further, other air filters different from the air filter 1 may be arranged in the casing on the upstream side or the downstream side of the air filter 1 at intervals in the air flow direction or adjacent to each other. Further, the air filter 1 may be installed directly with respect to the mounting location of the casing, or may be indirectly installed in a state of being housed in another box-shaped casing capable of accommodating the air filter 1 inside. ..

As the air filter 1, an air filter of the DS-600 model having the following specifications and performance provided with an insect screen having the following specifications can be exemplified.
External dimensions: length (page depth direction in FIG. 5) 610 mm x width (horizontal direction in FIG. 5) 610 mm x height (vertical direction in FIG. 5) 20 mm
Distance between the tip 12a of the pressing portion 12 and the wall portion 6 of the outer frame 5 in the pressed state: 5.5 mm
Planar length of the gap between the outer frame 5 and the inner frame 11 in the pressed state: 1 mm
Filter material: Thickness 20 mm (thickness on the upstream side of the insect net, thickness 13 mm on the downstream side), grain size 360 g / m ² , polyester resin spunbonded non-woven fabric with an average fiber diameter of about 45 μm Collection efficiency (mass method): 82% (JIS B9908 format 3)
Initial pressure loss (processing air volume 3360 m ³ / hour): 88 Pa
Dust retention: Approximately 860 g / m ²
Insect repellent net: Polypropylene resin woven fabric with an average hole diameter of 0.77 mm, a wire diameter of φ0.17 mm, an average aperture ratio of 37%, and a thickness of 0.3 mm.

The above specifications and performance are measured by, for example, the following measurement methods.
(thickness)
The thickness of the test sample when a load of 2.5 N is applied at 10 mmφ is measured using a dial thickness gauge.
(Metsuke)
The weight of a 100 mm × 100 mm test piece collected from a test sample is measured and converted into a weight per 1 m ² .
(Average fiber diameter)
Two orthogonal lines were drawn on the surface of the test sample taken with a scanning electron microscope (SEM), and 500 lines were measured using the thickness of the image of the fiber intersecting these lines as the fiber diameter. Let the arithmetic mean of be the average fiber diameter.

(Collection efficiency)
In accordance with JIS B9908 format 3, a vertical test device is used to measure the collection efficiency of JIS 11 types of dust specified in JIS Z8901 at a test wind speed of 2.5 m / sec.

(Initial pressure loss)
According to JIS B9908 format 3, the pressure loss at a wind speed of 2.5 m / sec is measured using a duct having a size of 610 mm × 610 mm.
(Dust retention amount)
In accordance with JIS B9908 format 3, the final pressure loss (250 Pa) is reached at a dust concentration of 70 ± 30 mg / m ³ and a test wind speed of 2.5 m / sec by JIS 11 types of powder specified in JIS Z8901. Measure the amount of dust supplied up to.
(Insect repellent performance)
While ventilating the test sample of the air filter 1 at a wind speed of 2.5 m / sec, 100 adults of Western flower thrips were released from the upstream side, and one day later, the number of insects existing on the downstream side of the test sample was counted and released. The ratio of the number of insects captured by the test sample to the number of insects was calculated to be the collection rate (%), and the average value of the collection rates obtained by performing the same test three times was calculated to determine the insect control performance. evaluated. Western flower thrips is considered to be one of the important pests, and is the shortest of the important pests. In addition, it was used in this test because it is easy to breed. By this test, it was confirmed that the insect repellent performance of the air filter of the present invention was good.

In the air filter 1 described above, the outer peripheral portion of the filter medium 3 is compressed and crushed by being sandwiched between the wall portion 6 of the outer frame 5 and the pressing portion 12 of the inner frame 11. Therefore, it is possible to prevent the insects from passing through to the outer peripheral side of the inner frame 11 by cutting off the invasion route of the insects that have entered the inside of the inner frame 11 to the outer peripheral side on the upstream side of the air filter 1. Further, even if an insect enters the air filter 1 through the gap between the outer frame 5 and the inner frame 11 on the upstream side of the air filter 1 and invades the filter medium 3 from the outer peripheral end of the filter medium 3. It cannot pass through the part pressed by the inner frame 11 inside.
Here, as another air filter different from the air filter 1, the filter medium is provided with a wall portion on the upstream side and a wall portion on the downstream side of the frame so as to bite into the filter medium in the thickness direction in the cross section in the direction in which the gas passes. On the other hand, it is assumed that the shape is processed so that the pressure contact force acts in the thickness direction. In this air filter, it is considered that the filter medium is strongly pressed against the wall portion because the repulsive force is strong in the portion of the filter medium on which the pressure contact force acts. However, even when an air filter equipped with such a frame is used, insects get inside the filter medium while struggling at the boundary between the wall on the upstream side of the frame and the filter medium. Further, it may move toward the outer peripheral side of the filter medium. The reason why insects try to move toward the gap between the filter medium and the wall of the frame facing the outer peripheral edge of the filter medium is that in other air filters of the above-described form, the filter medium has a wall on the downstream side of the frame. Due to the high density of the filter medium near the part where the part bites, the insects have a lower density of the filter medium (less resistance) than moving in the filter medium toward the downstream side in the direction of the air flow. It is considered that this is because it tries to move to the portion, and further, rather than moving inside the filter medium, it tries to go out of the filter medium (the gap between the filter medium and the outer frame). Therefore, after the insects reach the outer peripheral end of the filter medium 3, the insects dig into the gap between the filter medium 3 and the wall portion 6 of the outer frame 5 or the inside of the filter medium 3, and are on the downstream side of the air filter. There is a possibility of passing through. On the other hand, in the air filter 1, the outer peripheral portion of the filter medium 3 is crushed so that the density of the filter medium 3 becomes maximum in the thickness direction at the position pressed by the inner frame 11, and the invasion path of insects is established. The structure is completely cut off and insects cannot invade.

Further, since the inner frame 11 is an integral member, the filter medium 3 can be pressed with an equal force on each side of the outer frame 5, and the strength of the force for pressing the filter medium 3 varies between the sides. It is possible to easily perform the work of attaching and detaching the filter medium 3 at the time of replacement. Further, when the inner frame 11 presses the filter medium 3 in a circumferential shape, the pressing portion 12 of the inner frame 11 and the filter medium 3 come into contact with each other over the entire circumference, and from the inside of the inner frame 11 on the upstream side of the air filter 1. It is possible to surely cut off the invasion route of insects to the outside.
Further, in the other air filters described above, the filter medium is held by the frame by using the repulsive force of the filter medium, but as the filter medium, a material that does not generate a sufficient repulsive force even if it receives a pressure contact force from the frame. , Shape, etc., insects can easily invade through the gap between the filter medium and the wall. Since the air filter 1 of the first embodiment cuts off the invasion route of insects by compressing and crushing the filter medium 3, the invasion of insects is ensured even when a filter medium that does not generate a sufficient repulsive force is used. Can be prevented. In this respect, the degree of freedom in selecting the filter medium is high.

(Modification example)
As for the filter medium 3, the first filter medium sheet 3a and the second filter medium sheet 3b may have the same thickness, and the thickness of the first filter medium sheet 3a may be larger than the thickness of the second filter medium sheet 3b. Good.
The air filter 1 may be adapted to press the filter medium 3 against the wall portion on the upstream side from the downstream side. In this case, in the outer frame 5, the downstream wall portion is configured in the same manner as the wall portion 8, the upstream wall portion is configured in the same manner as the wall portion 6, and the downstream wall portion is configured in the same manner as the wall portion 6. The unit 9 is connected. Further, in the inner frame 11, the wall portion 13 is arranged as a wall portion on the downstream side, and the locking portion 15 is provided on the downstream side of the wall portion on the downstream side. In this case, the support member is preferably arranged on the downstream side.

Next, the air filter of the second embodiment will be described with reference to FIGS. 6 to 11.
Here, the air filter 21 will be described by paying attention to the difference from the air filter 1 of the first embodiment.
FIG. 6 is an exploded perspective view of the air filter 21 of the second embodiment. FIG. 7 is a perspective view illustrating an example of how to assemble the air filter 21. In FIGS. 6 and 7, the filter medium and the insect screen of the air filter 21 are not shown. The X direction shown in FIGS. 6 and 7 is the direction in which the gas passes.
FIG. 8 is a diagram showing a cross section of the air filter 21 including the CC line cross section of the outer frame 25 and the C'-C' line cross section of the inner frame 31 shown in FIG. FIG. 9 is a diagram showing a cross section of the air filter 21 including the D-D line cross section of the outer frame 25 and the D'-D' line cross section of the inner frame 31 shown in FIG. FIG. 10 is a diagram showing a cross section of the air filter 21 including the EE line cross section of the outer frame 25 and the E'-E' line cross section of the inner frame 31 shown in FIG. In FIGS. 8 to 10, the direction from the upper side to the lower side coincides with the X direction shown in FIGS. 6 and 7.
FIG. 11 is a side view showing a modified example of the inner frame when viewed in the Z direction.

The air filter 21 includes a filter medium 3 (see FIGS. 8 to 10), an insect screen 4 (see FIGS. 8 to 10), an outer frame 25, and an inner frame 31. Of these, the filter medium 3 and the insect screen 4 are the same as the filter media 3 and the insect screen 4 described in the first embodiment.

The outer frame 25 has a wall portion 26 (first wall portion), a wall portion 27, and a wall portion 28 (second wall portion). Of these, the wall portion 28 is a portion extending inward in the plane direction from the upstream end of the wall portion 27. As shown in FIGS. 8 to 10, the wall portion 28 guides the inner frame 31 so that the upstream end portion (guide portion 37 described later) is arranged flush with the upstream end portion of the outer frame 25. It has a step in the airflow direction for receiving the portion 37. In FIGS. 6 and 7, the step is not shown. Further, the wall portion 28 has a plate-shaped wall portion 29 extending downstream at the inner end in the plane direction. The wall portion 29 is not provided with the hole 9b described in the first embodiment.

As shown in FIG. 6, the inner frame 31 is two portions located in the middle of the circumference of the members constituting the inner frame 31, and the first portion 31a and the second portion 31c extending in parallel with each other. have. In the example shown in FIG. 6, the first portion 31a and the second portion 31c are portions corresponding to a set of opposite sides among the four portions corresponding to the four sides of the rectangular shape of the inner frame 31. Each of the first portion 31a and the second portion 31c extends to the side of the outer frame 25 and has a claw portion 33 arranged between the wall portion 28 and the wall portion 26 of the outer frame 25 in the pressed state. doing. Further, each of the first portion 31a and the second portion 31c has a guide portion 37 that is arranged on the upstream side of the claw portion 33 and extends to the side of the outer frame 25 facing the claw portion 33. ing. In the example shown in FIG. 6, the claw portion 33 and the guide portion 37 extend in the direction in which the first portion 31a and the second portion 31c extend, and extend in a plate shape in the plane direction. As a result, a groove-shaped space extending in the Z direction is formed between the claw portion 33 and the guide portion 37 in the X direction. In FIG. 6, the distance between the claw portion 33 and the guide portion 37 in the X direction is exaggerated. Further, the inner frame 31 is provided with a step in the X direction at the upstream end portion inside the guide portion 37 in the plane direction as shown in FIGS. 8 to 10. In FIGS. 6 and 7, the step is not shown.

Specifically, the claw portion 33 has a lower surface 35 forming a downstream end in the X direction and an upper surface 34 forming an upstream end in the X direction. The lower surface 35 functions as a pressing portion, and the upper surface 34 functions as a locking portion. In the air filter 21, the filter medium 3 is compressed by being pressed downstream by the lower surface 35 of the claw portion 33, and is brought into a pressed state. Then, in the pressed state, the upper surface 34 of the claw portion 33 comes into contact with the wall portion 28 of the outer frame 25 from the downstream side, so that the inner frame 31 is locked to the outer frame 25. Specifically, the upper surface 34 abuts on the tip (downstream end) of the wall portion 29 of the wall portion 28 in the example shown in FIGS. 8 to 10.
In the pressed state of the air filter 21, the height position of the lower surface 35 of the claw portion 33 with respect to the wall portion 26 of the outer frame 25 (distance between the claw portion 33 and the wall portion 26) is the thickness of the filter medium 3 (X). Shorter than (length along the direction). As a result, the filter medium 3 can be pressed against the wall portion 26 side of the outer frame 25 by the claw portion 33 in the pressed state and compressed. Further, the upper surface 34 of the claw portion 33 is pressed against the wall portion 28 of the outer frame 25 by the repulsive force along the thickness direction of the pressed filter medium 3, so that the inner frame 31 can be locked to the outer frame 25. it can. The distance is, for example, more than 7 mm and 18 mm or less when the thickness of the filter medium 3 is 20 mm.

In the air filter 21, the length L1 (see FIG. 8) in which the claw portion 33 of the first portion 31a extends toward the outer frame 25 is such that the claw portion 33 of the second portion 31c is on the side of the outer frame 25. It is preferably longer than the extending length L2 (see FIG. 9). The fact that L1 is longer than L2 contributes to the fact that the inner frame 31 locked to the outer frame 25 is hard to come off from the outer frame 25. Here, how to assemble the air filter 21 will be described. After arranging the filter medium 3 and the insect net 4 between the wall portion 26 and the wall portion 28 of the outer frame 25, as shown in FIG. 7, the inner frame 31 is slightly tilted with respect to the outer frame 25. The wall portion 28 of the outer frame 25 is arranged in the groove between the claw portion 33 and the guide portion 37 of the inner frame 31. In FIG. 7, the inclination of the inner frame 31 with respect to the outer frame 25 is exaggerated. Then, the wall portion 28 of the outer frame 25 is brought into contact with the groove bottom 38 between the claw portion 33 and the guide portion 37, and the inner frame 31 is arranged in the same plane as the outer frame 25. Is rotated around the first portion 31a as a fulcrum, and the second portion 31c is arranged in the opening 10. At this time, in the first portion 31a and the second portion 31c, the lower surface 35 of the claw portion 33 presses the filter medium 3 toward the downstream side to compress it (pressed state), and in the first portion 31a, the claw portion 31a. The upper surface 34 of the portion 33 receives the repulsive force of the pressed filter medium 3 and comes into contact with the wall portion 28 of the outer frame 25 from the downstream side. Next, the inner frame 31 is slid in the Y direction with respect to the outer frame 25 from the state shown in FIG. 8, and the wall portion 28 of the outer frame 25 is arranged in the groove of the second portion 31c. At this time, the wall portion 28 of the outer frame 25 may be brought into contact with the groove bottom 38 of the second portion 31c as shown in FIG. At this time, the upper surface 34 of the claw portion 33 of the second portion 31c receives the repulsive force of the filter medium 3 and comes into contact with the wall portion 28 of the outer frame 25 from the downstream side. In this way, the inner frame 31 is locked to the outer frame 25, and the air filter 21 is assembled.

Regarding the dimensions of the inner frame 31, the length L38 (see FIG. 6) of the inner frame 31 from the groove bottom 38 of the first portion 31a to the tip of the claw portion 33 of the second portion 31c in the Y direction is in the Y direction. It is shorter than the length of the space inside the opening 10 along. As a result, the second portion 31c of the inner frame 31 can be arranged in the opening 10 in a state where the wall portion 28 of the outer frame 25 is in contact with the groove bottom 38 of the first portion 31a. Further, the length L33 (see FIG. 6) of the inner frame 31 from the tip of the claw portion 33 of the first portion 31a to the tip of the claw portion 33 of the second portion 31c in the Y direction is an opening along the Y direction. It is longer than the length of the space inside the portion 10. As a result, the inner frame 31 locked to the outer frame 25 is prevented from coming off from the outer frame 25. The claw portion 33 is longer than the guide portion 37 in the plane direction in the first portion 31a, and has the same length as the guide portion 37 in the plane direction in the second portion 31c. The length of the guide portion 37 in the plane direction is equal in the first portion 31a and the second portion 31c.

The following examples can be given with respect to the dimensions of the inner frame 31.
With respect to the claw portion 33, L1 is preferably 1 to 3 mm longer than the length of L2. For example, when L2 is 3.0 to 6.0 mm, L1 is 4.0 to 9.0 mm.

The inner frame 31 further has third portions 31b and 31d at positions in the middle of the circumference different from the first portion 31a and the second portion 31c. In the example shown in FIG. 6, the third portions 31b and 31d are portions corresponding to the other pair of opposite sides among the four portions corresponding to the four sides of the rectangular shape of the inner frame 31, and each has a circumferential shape. It is connected to the first portion 31a and the second portion 31c on both sides in the direction along. The third portions 31b and 31d are provided with guide portions 37, but are not provided with claw portions 33. Further, the third portions 31b and 31d have a plate-shaped wall portion 36 extending downstream at the inner end in the plane direction. The wall portion 36 functions as a pressing portion. The height position of the tip (end in the X direction) of the wall portion 36 with respect to the wall portion 26 of the outer frame 25 is the first in the example shown in FIG. 10 in a state where the inner frame 31 is locked to the outer frame 25. It is preferable that it is equal to the height position of the lower surface 35 of the claw portion 33 in the portion 31a and the second portion 31c. As a result, the lower surface 35 of the claw portion 33 of the first portion 31a and the second portion 31c and the wall portion 36 of the third portions 31b and 31d are circumferentially formed as an integral pressing portion against the filter medium 3. The end of the outer peripheral portion of the filter medium 3 can be pressed uniformly over the entire circumference.

The inner frame 31 may have other pressing portions in addition to the claw portion 33 and the wall portion 36. The inner frame 31 is a wall portion 32 forming an inner end in the plane direction as another pressing portion, and has a plate-shaped wall portion 32 extending downstream along the X direction. In the example shown in FIGS. 8 to 10, the height position of the tip of the wall portion 32 is located at the same height as the lower surface 35 of the claw portion 33 and the tip of the wall portion 36. Since the inner frame 31 has the wall portion 32, the wider planar region of the end portion of the outer peripheral portion of the filter medium 3 can be pressed and compressed together with the claw portion 33 and the wall portion 36. In the air filter 21 of the second embodiment, in order to alleviate the load on the filter medium 3 due to the pressing portion pressing the filter medium 3, the tip of the pressing portion (the end in the X direction) with respect to the wall portion 26 of the outer frame 25 The height position is set high. In the air filter 21, the claw portion 33 has a lower surface 35 extending along the Y direction, so that the area where the filter medium 3 is pressed is widened. Further, since the inner frame 31 has another pressing portion, it is possible to press and compress the wider planar region of the filter medium 3 together with the pressing force by the claw portion 33 and the wall portion 36. As a result, the invasion of insects can be prevented more reliably. Further, in the air filter 21, the number of parts of the inner frame 31 can be reduced, and the work man-hours for locking the inner frame 31 to the outer frame 25 can be reduced. Further, since the air filter 21 does not have a hole in the inner frame 31, it is possible to cut off the invasion route of insects that pass through the inner frame 31.

FIG. 11 shows a side view showing a modified example of the inner frame 31 when viewed in the Z direction.
As shown in FIG. 11, the third portions 31b and 31d of the inner frame 31 bulge downstream with respect to the plane S including the direction (Z direction) in which the first portion 31a and the second portion 31c extend. It is preferable that it has a curved shape. In FIG. 11, the deflection of the inner frame 31 is exaggerated. Further, it is preferable that the third portions 31b and 31d are elastically deformed so as to extend in the plane S in the pressed state.
In the air filter 21, claws are provided in the third portions 31b and 31d in order to lock the inner frame 31 to the outer frame 25 by using the claws 33 of the first portion 31a and the second portion 31c. Not. Therefore, when the third portions 31b and 31d are in the form of extending linearly along the Y direction as shown in FIGS. 6 and 7, if the repulsive force of the pressed filter medium 3 is large, the inner frame 31 Is locked to the outer frame 25, the third portions 31b, 31d may be separated from the wall portion 26 of the outer frame 25 so that the central region in the Y direction rises above the regions at both ends in the Y direction. There is. In particular, when the length (width) of the inner frame 31 along the plane direction is shortened in order to reduce the weight of the air filter 21, such floating becomes remarkable. In the modified example shown in FIG. 11, the third portions 31b and 31d have the above-mentioned curved shape, so that the inner frame 31 is the outer frame 25 even if the repulsive force of the pressed filter medium 3 is large. In the state of being locked to, it is possible to prevent the central region from rising along the Y direction. The third portions 31b and 31d are elastically deformed so as to extend in the plane S in the pressed state, and return to the form shown in FIG. 11 when removed from the outer frame 25.
Specifically, the maximum amount of deflection D at the portion where the third portions 31b and 31d bulge most downstream with respect to the plane S is, for example, 10 to 20 mm. The maximum amount of deflection D in this range is suitable when the vertical length of the air filter 21 is, for example, 610 mm. The maximum amount of deflection D is located at the most downstream side of the upstream ends of the first portion 31a and the second portion 31c and the upstream ends of the third portions 31b and 31d in the example shown in FIG. Although it is indicated by the distance to the portion to be formed, the airflow between the intermediate position in the airflow direction of the first portion 31a and the second portion 31c and the airflow of the third portions 31b and 31d bent to the most downstream side. It may be a distance from a position in the middle of the direction.

According to the air filter 21 of the second embodiment, the filter medium 3 can be pressed and compressed by the pressing portion. Therefore, on the upstream side of the air filter 21, the invasion route of the insects that have entered the inside of the inner frame 31 to the outer peripheral side can be cut off, and the insects can be prevented from passing through to the outer peripheral side of the inner frame 31. Further, even if an insect enters the air filter 21 through the gap between the outer frame 25 and the inner frame 31 on the upstream side of the air filter 21, and invades the filter medium 3 from the outer peripheral end of the filter medium 3. It cannot pass through the inside of the portion pressed by the inner frame 31.
The height position of the tip of the wall portion 32 may be lower than the height position of the lower surface 35 of the claw portion 33. In this case, instead of the lower surface 35 of the claw portion 33, the wall portion 32 mainly functions as a pressing portion.

Although the air filter has been described in detail above, the present invention is not limited to the above embodiment, and it goes without saying that various improvements and changes may be made without departing from the gist of the present invention.

1 Air filter 3 Filter material 3a First filter medium sheet 3b Second filter medium sheet 4 Insect repellent nets 5, 25 Outer frame 6, 26 Outer frame wall part (first wall part)
7,8,9,27,28 Outer frame wall part 9a Wall surface 9b Hole 11, 31 Inner frame 12 Inner frame wall part (pressing part)
13 Inner frame wall 15 Locking 16 Fastener (operated member)
17 Pin 33 Claw 34 Upper surface of the claw 35 Lower surface of the claw

Claims (6)

Filter media for filters that collect fine particles in gas,
An outer frame that surrounds the filter medium for the filter from the outer peripheral side and is open so that the gas passes through the filter medium for the filter.
Before being placed on the inside of the outer edge portion of the Kigaiwaku, and a inner frame is a member integrally formed circumferentially along the outer frame,
The outer frame has a first wall portion that supports an end portion on the outer peripheral side of the filter medium for the filter from a first side that is one side in the direction in which the gas passes through the filter medium for the filter.
The inner frame is compressed by pressing the outer peripheral end of the filter filter medium from the first side and the second side opposite to the gas passing direction against the first wall side. It has a pressing portion and a locking portion that locks the inner frame to the outer frame so that the gas does not move in the direction in which the gas passes with respect to the outer frame in the pressed state in which the filter medium for the filter is pressed. And
The inner frame is different from the first portion and the second portion, which are two portions located in the middle of the circumference of the member and extend in parallel with each other, and the first portion and the second portion. It has a third part located in the middle of the circumference of the member,
The third portion has a shape curved so as to bulge toward the second side with respect to a plane including a direction in which the first portion and the second portion extend along the circumferential shape.
The third portion is an air filter characterized in that, in the pressed state, the air filter is elastically deformed so as to extend in the plane. It ’s an air filter.
Filter media for filters that collect fine particles in gas,
An outer frame that surrounds the filter medium for the filter from the outer peripheral side and is open so that the gas passes through the filter medium for the filter.
Before being placed on the inside of the outer edge portion of the Kigaiwaku, and a inner frame is a member integrally formed circumferentially along the outer frame,
The outer frame has a first wall portion that supports an end portion on the outer peripheral side of the filter medium for the filter from a first side that is one side in the direction in which the gas passes through the filter medium for the filter.
The inner frame is compressed by pressing the outer peripheral end of the filter filter medium from the first side and the second side opposite to the gas passing direction against the first wall side. It has a pressing portion and a locking portion that locks the inner frame to the outer frame so that the gas does not move in the direction in which the gas passes with respect to the outer frame in the pressed state in which the filter medium for the filter is pressed. And
The pressing portion has a wall portion extending toward the first wall portion in a direction in which the gas passes through the filter medium for the filter over the entire circumference of the inner frame.
The tip of the wall portion in the extending direction comes into contact with the filter medium for the filter in the pressed state on at least a part of the circumference of the inner frame.
The air filter is an insect repellent net that prevents insects from passing through, and further includes a sheet-shaped insect repellent net whose outer peripheral end is surrounded by the outer frame.
The air filter is characterized in that the insect repellent net is arranged so as to be located along the extending direction of the filter medium for the filter and in the central region between both ends in the thickness direction of the filter medium for the filter. The first or second aspect of the invention, further comprising a support member for supporting the portion of the filter medium for the filter exposed to the first side inside the inner peripheral end of the outer frame from the first side. Air filter. It ’s an air filter.
Filter media for filters that collect fine particles in gas,
An outer frame that surrounds the filter medium for the filter from the outer peripheral side and is open so that the gas passes through the filter medium for the filter.
Before being placed on the inside of the outer edge portion of the Kigaiwaku, and a inner frame is a member integrally formed circumferentially along the outer frame,
The outer frame has a first wall portion that supports an end portion on the outer peripheral side of the filter medium for the filter from a first side that is one side in the direction in which the gas passes through the filter medium for the filter.
The inner frame is compressed by pressing the outer peripheral end of the filter filter medium from the first side and the second side opposite to the gas passing direction against the first wall side. It has a pressing portion and a locking portion that locks the inner frame to the outer frame so that the gas does not move in the direction in which the gas passes with respect to the outer frame in the pressed state in which the filter medium for the filter is pressed. And
The pressing portion has a wall portion extending toward the first wall portion in a direction in which the gas passes through the filter medium for the filter over the entire circumference of the inner frame.
The tip of the wall portion in the extending direction comes into contact with the filter medium for the filter in the pressed state on at least a part of the circumference of the inner frame.
The air filter is further provided with a support member that supports a portion of the filter medium for the filter exposed to the first side inside the inner peripheral side end portion of the outer frame from the first side. Air filter to do. Further, it is an insect repellent net that prevents insects from passing through, and is provided with a sheet-shaped insect repellent net whose outer peripheral end is surrounded by the outer frame.
The air filter according to claim 1 or 4, wherein the insect repellent net is arranged along the extending direction of the filter medium for the filter and in the central region between both ends in the thickness direction of the filter medium for the filter. .. The filter medium for a filter has a first filter medium element arranged on the first side of the insect screen and a second filter medium element arranged on the second side of the insect screen.
The air filter according to claim 5, wherein the first filter medium element has a smaller thickness in the direction in which the gas passes than the second filter medium element.

Images