JP2011052791A - Ventilation structure and ventilation member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ventilation structure and a ventilation member having excellent water proofing property. <P>SOLUTION: The ventilation structure 50 is provided with a housing 20 having an opening 21 for ventilation and the ventilation member 10 attached to the opening 21. The opening 21 is formed with a taper 23 so that an opening diameter enlarges from an internal space 22 side toward an external space side 24 of the housing 20. The ventilation member 10 is provided with a ventilation membrane 2, a support 4 which supports the ventilation membrane 2 and a sealing ring 8 which is provided on a root of a leg 26 of the support 4. The sealing ring 8 deforms along the taper 23 by being interposed between the support 4 and the housing 20. Between the lower surface 11q of the support 4 and the surface 20p of the housing 20, a clearance 30 is formed to face a part of the sealing ring 8 protruding from the opening 21. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a ventilation structure and a ventilation member.

  A ventilation member is attached to a housing that houses automobile electrical components such as a lamp, a motor, a sensor, a switch, and an ECU. The ventilation member secures ventilation between the inside and the outside of the housing to prevent a problem based on a pressure change, and also prevents foreign matter from entering the inside of the housing. Examples of such a ventilation member are disclosed in Patent Documents 1 and 2. The ventilation member disclosed in Patent Document 1 is shown in FIG.

  The ventilation member 101 includes a support body 103, a ventilation film 102 disposed on the support body 103, and a protection unit 104 covering the ventilation film 102. The ventilation member 101 is fixed to the opening 107 of the housing 106 via the O-ring 105. The leg portion 108 of the support 103 is engaged with the opening 107 so that the ventilation member 101 does not come out of the housing 106.

JP 2004-47425 A JP 2007-141629 A

  The ventilation member is required to have high durability depending on its use. For example, many parts and materials of automobiles are required to undergo environmental tests according to industrial standards such as JIS (Japanese Industrial Standards). An example of an environmental test is a high pressure car wash test. In order to prevent water from entering the housing in the high-pressure car wash test, the ventilation member is also required to have high waterproofness.

  An object of this invention is to provide the ventilation structure and ventilation member provided with the outstanding waterproofness.

That is, the present invention
A ventilation structure comprising a housing having an opening for ventilation and a ventilation member attached to the opening,
The ventilation member includes: (i) a base portion in which a ventilation path is formed between an internal space and an external space of the housing; and a leg portion that extends from the base portion and is fitted in the opening. And (ii) a ventilation film disposed on the base portion so as to close the ventilation path on the external space side, and (iii) a seal ring provided at the base of the leg portion. ,
The opening is tapered so that the opening diameter increases as it goes from the inner space side to the outer space side,
The seal ring is made of a material having rubber elasticity, and is deformed along the taper by being sandwiched between the support and the housing in the opening.
A ventilation structure is provided in which a gap facing a part of the seal ring protruding from the opening is formed between the lower surface of the base portion of the support and the surface of the housing. .

In another aspect, the present invention provides:
A ventilation member attachable to a housing having an opening for ventilation,
A support having a ventilation path between the internal space and the external space of the housing;
A ventilation membrane disposed on the support so as to close the ventilation path on the external space side;
A cover covering the support from the side where the gas permeable membrane is disposed,
The cover includes: (a) a ceiling part that covers the whole of the gas permeable membrane in plan view; (b) an outer flange part that extends downward from the periphery of the ceiling part toward the support; ) Located between the gas permeable membrane and the outer flange with respect to the radial direction of the cover, extends downward from the lower surface of the ceiling toward the support body, and has an outer periphery of the gas permeable membrane in plan view And (d) formed on the ceiling portion so as to communicate the inside and outside of the cover between the inner flange portion and the outer flange portion with respect to the radial direction. And a ventilation member.

  According to the ventilation structure of the present invention, the opening of the housing is tapered. The seal ring is made of a material having rubber elasticity, and is deformed along the taper in the opening. In this case, the seal surface formed by the seal ring is hidden in the opening, and a seal surface having a direction inclined with respect to the surface of the housing can be formed. Such a sealing surface exhibits high sealing performance against water sprayed from a direction parallel to the surface of the housing.

  Furthermore, according to the ventilation structure of the present invention, a gap is formed between the lower surface of the support (specifically, the lower surface of the base portion) and the surface of the housing. When the seal ring is disposed in the sealed space, it is difficult to discharge the liquid that has entered the periphery of the seal ring for some reason. Depending on the type of liquid, the seal ring may swell or melt. That is, the deterioration of the seal ring is promoted, and the sealing performance is lowered early. For example, when salt water that has entered the periphery of the seal ring is allowed to stand, salt precipitates between the surface of the seal ring or the ventilation member and the housing. The deposited salt may roughen the surface of the seal ring or other parts, leading to a decrease in sealing performance.

  On the other hand, when a gap having an appropriate width is provided as in the present invention, it is possible to promote the discharge of liquid from the periphery of the seal ring. Therefore, the occurrence of the above problems can be prevented in advance. Therefore, according to the present invention, although the ability to prevent the intrusion of liquid into the housing is higher than that of the conventional product, the ventilation structure that is unlikely to cause deterioration of the seal ring, that is, excellent waterproofness is exhibited over a long period of time. A ventilation structure can be provided.

  In addition, according to the ventilation member of the present invention, the cover that covers the support from the side where the ventilation film is disposed is provided. The cover includes a ceiling portion that covers the entire gas permeable membrane in plan view, and an outer flange that extends downward from the periphery of the ceiling portion toward the support. Therefore, the gas permeable membrane can be appropriately protected from foreign substances such as liquids and pebbles from the upward and lateral directions. In addition, a ventilation hole that communicates the inside and the outside of the cover is formed in the ceiling. When such a vent is formed, water that has entered the cover is likely to be discharged to the outside. However, such a vent allows entry of foreign matter into the cover, and it cannot be denied that the ventilation film may be directly damaged by the foreign matter.

  In the present invention, the inner flange is provided between the gas permeable membrane and the outer flange in the radial direction. The inner flange extends downward from the lower surface of the ceiling toward the support and has an arc shape along the outer periphery of the gas permeable membrane in plan view. Since the inner flange acts as a defense wall, the foreign matter cannot go straight from the vent toward the vent membrane, and the vent membrane can be prevented from being directly damaged by the foreign matter. Therefore, according to this invention, the ventilation member which exhibits the outstanding waterproofness and durability over a long term can be provided.

1 is an exploded perspective view of a ventilation structure according to an embodiment of the present invention. Longitudinal sectional view of the ventilation structure Cross section of the ventilation membrane Exploded sectional view showing outer diameter of seal ring and opening Partial enlarged sectional view of the ventilation structure Schematic showing the collapse width of the seal ring Schematic showing the relationship between the taper of the opening and the support Schematic enlarged view of FIG. Bottom view of cover Longitudinal sectional view of the ventilation structure according to the second embodiment Side view of conventional ventilation member Schematic showing the problems of conventional ventilation members

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, the ventilation structure 50 according to the present embodiment includes a housing 20 having an opening 21 for ventilation and a ventilation member 10 attached to the opening 21. The housing 20 has an internal space 22 that requires ventilation. The ventilation member 10 includes a gas permeable membrane 2, a support 4, a cover 6, and a seal ring 8. Gas can flow between the internal space 22 and the external space 24 through the gas permeable membrane 2.

  Examples of the housing 20 include an ECU (Electric Control Unit) box and a lamp box of an automobile. However, only a part of the housing 20 is shown in FIGS. 1 and 2. A taper 23 is formed in the opening 21 of the housing 20 so that the opening diameter increases from the inner space 22 side toward the outer space 24 side. In this specification, a direction orthogonal to the radial direction of the opening 21 is defined as an axial direction, and a straight line parallel to the axial direction and passing through the center of the opening 21 is defined as an axis O.

  In the ventilation member 10, the gas permeable membrane 2, the support body 4, and the cover 6 each have a circular shape in plan view. An axis O passes through the centers of the gas permeable membrane 2, the support 4 and the cover 6. With respect to the axial direction, the side where the gas permeable membrane 2 is located is the upper surface side of the support body 4, and the side facing the housing 20 is the lower surface side of the support body 4. Further, the thickness direction of the gas permeable membrane 2 is parallel to the axis O, and the radial directions of the gas permeable membrane 2 and the support 4 are parallel to the radial direction of the opening 21.

  As shown in FIG. 2, the support 4 of the ventilation member 10 includes a base portion 11 and a leg portion 26. The base portion 11 is a portion that supports the gas permeable membrane 2 and has a substantially disk shape. A through hole 3 is formed in the base portion 11 as a ventilation path between the internal space 22 and the external space 24. The leg part 26 is a part for fixing the ventilation member 10 to the housing 20, and is formed integrally with the base part 11 and extends downward from the base part 11. The leg portion 26 is divided into a plurality of portions (three portions in the present embodiment) along the circumferential direction of the through hole 3. In the ventilation structure 50, the leg portion 26 is fitted in the opening 21.

  The gas permeable membrane 2 is disposed on the base portion 11 so as to close the through hole 3 on the external space 24 side. The gas permeable membrane 2 is not particularly limited as long as it has a property of allowing gas permeation and preventing liquid permeation. As shown in FIG. 3, the gas permeable membrane 2 may have a membrane body 2a and a reinforcing material 2b superimposed on the membrane body 2a. By providing the reinforcing material 2b, the strength of the gas permeable membrane 2 is improved. Of course, the gas permeable membrane 2 may be composed only of the membrane body 2a.

  The film body 2a may be subjected to liquid repellent treatment such as oil repellent treatment and water repellent treatment. These liquid repellent treatments can be performed by applying a substance having a small surface tension to the film body 2a, and curing after drying. The liquid repellent used for the liquid repellent treatment is not particularly limited as long as it can form a film having a surface tension lower than that of the film body 2a. For example, a liquid repellent containing a polymer having a perfluoroalkyl group is suitable. The liquid repellent is applied to the film body 2a by a known method such as impregnation or spraying.

  A typical example of the membrane body 2a is a porous membrane made of fluororesin or polyolefin. From the viewpoint of ensuring sufficient waterproofness, a resin porous membrane having an average pore diameter of 0.01 to 10 μm can be used for the membrane body 2a.

  Examples of the fluororesin suitable for the membrane body 2a include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-ethylene copolymer. Examples of suitable polyolefin for the membrane body 2a include polymers of monomers such as ethylene, propylene, 4-methylpentene-1,1butene, and copolymers thereof. A nanofiber film porous body using polyacrylonitrile, nylon, or polylactic acid may be used. Among them, PTFE is preferable because it has a small area and can ensure high air permeability and is excellent in ability to prevent foreign matter from entering the inside of the housing. The PTFE porous membrane can be produced by a known molding method such as a stretching method and an extraction method.

  The reinforcing material 2b can be a member made of a resin such as polyester, polyethylene, or aramid. The form of the reinforcing material 2b is not particularly limited as long as the air permeability of the gas permeable membrane 2 can be maintained, and is, for example, a woven fabric, a nonwoven fabric, a net, a mesh, a sponge, a foam, or a porous body. The membrane body 2a and the reinforcing material 2b are preferably bonded together by thermal lamination, thermal welding, ultrasonic welding, or an adhesive.

The thickness of the gas permeable membrane 2 is preferably in the range of 1 μm to 5 mm in consideration of strength and ease of handling. The air permeability of the gas permeable membrane 2 is preferably in the range of 0.1 to 300 sec / 100 cm ³ in terms of the Gurley value obtained by the Gurley tester method specified in JIS (Japanese Industrial Standards) P 8117. The water pressure resistance of the gas permeable membrane 2 is preferably 1.0 kPa or more.

  The seal ring 8 is provided at the base of the leg portion 26. In the present embodiment, the seal ring 8 is made of rubber elastic material, for example, an elastomer such as nitrile rubber, ethylene-propylene rubber, silicone rubber, fluorine rubber, acrylic rubber, hydrogenated nitrile rubber or the like. Instead of the elastomer, the seal ring 8 may be made of another rubber elastic material such as a foam.

The seal ring 8 is deformed along the taper 23 by being sandwiched between the support 4 and the housing 20 in the opening 21. In this case, the seal surface formed by the seal ring 8 is hidden in the opening 21 and a seal surface having a direction inclined with respect to the surface of the housing 20 can be formed. Such a sealing surface exhibits high sealing performance against water sprayed from a direction parallel to the surface of the housing 20. As shown in FIG. 4, in the present embodiment, the seal ring 8 has an outer diameter D ₂ that is smaller than the opening diameter D ₁ of the opening 21 on the outer space 24 side in a state where the seal ring 8 is restored to its original shape. Therefore, when the ventilation member 10 is attached to the housing 20, the seal ring 8 can enter the opening 21.

  As shown in FIGS. 2 and 5, a part of the seal ring 8 protruding from the opening 21 faces between the lower surface 11 p of the base body 11 of the support 4 and the surface 20 p of the housing 20. A gap 30 is formed. If there is such a gap 30, it is possible to avoid the seal ring 8 being disposed in a sealed space. For this reason, even when liquid such as water and oil adheres to the seal ring 8, the discharge of the liquid from the periphery of the seal ring 8 can be promoted. In particular, a liquid having a low surface tension (for example, lubricating oil for automobiles) may invade into a small gap due to capillary action, so that a structure that promotes discharge is significant.

  As shown in FIG. 12, in the conventional ventilation structure, the seal ring 80 is compressed into a flat shape by the support 82 and the housing 84. One seal surface is formed between the seal ring 80 and the support 82, and the other seal surface is formed between the seal ring 80 and the housing 84. When water injection is performed from the side, the direction of water injection may coincide with the direction of each seal surface. In this case, the possibility of allowing water to enter the housing 84 is increased.

  On the other hand, in this embodiment, the sealing surface between the seal ring 8 and the housing 20 is formed on the taper 23 of the opening 21. That is, the seal surface is hidden in the opening 21. Therefore, high sealing performance can be exhibited with respect to water injection from the side. However, if the gap 30 is too wide, the possibility of allowing the water sprayed from the side to enter the housing 20 increases. Therefore, in the present embodiment, the height h of the gap 30 in the axial direction is adjusted to be less than the collapse width d of the seal ring 8. If the height h of the gap 30 is adjusted to a predetermined range, it is possible to achieve high sealing performance against water injection from the side, and to obtain the effect of promoting the liquid discharge described above. The lower limit of the height h of the gap 30 is not particularly limited, but is 0.2 mm, for example.

  In the present specification, the “collapse width d of the seal ring 8” is defined as follows. In this embodiment, the seal ring 8 has a circular cross section in a state where the seal ring 8 is restored to its original shape. As shown in FIG. 6, in a cross section including the axis O, a virtual circle 8 i having the same wire diameter r as that of the seal ring 8 in a region surrounded by the support 4 (base portion 11 and leg portion 26) and the taper 23. Is placed in contact with the base portion 11 and the leg portion 26. Then, the difference {(r / 2) -L} between the radius r / 2 of the virtual circle 8i and the distance L from the center C of the virtual circle 8i to the taper 23 is defined as the actual collapse width d of the seal ring 8. To do.

  The compression ratio of the seal ring 8 in the ventilation structure 50 is appropriately in the range of 8 to 40%. The compression rate of the seal ring 8 is expressed by 100 × (collapse width d) / (wire diameter r of the seal ring 8).

  In the present embodiment, in the cross section including the axis O, the surface profile of the taper 23 exhibits a convex curve toward the external space 24 side. According to such a configuration, since the seal surface formed between the seal ring 8 and the taper 23 is a curved surface, an improvement in sealing performance can be expected. Of course, in the cross section including the axis O, the surface profile of the taper 23 may be a straight line.

  In the present embodiment, the housing 20 is made of metal, and the taper 23 of the opening 21 is formed by pressing. After forming the through hole by a metal processing method such as punching and cutting, the case 20 having the opening 21 formed with the taper 23 is obtained by pressing. In particular, in order to form the taper 23 having a convex curved surface toward the external space 24 as in the present embodiment, a technique by press working is suitable. Of course, the taper 23 may be formed by other processing methods such as cutting. In addition, when the housing | casing 20 is resin, the housing | casing 20 used for the ventilation structure 50 can be manufactured easily by well-known resin molding methods, such as an injection molding method.

  As shown in FIG. 7, in this embodiment, the edge 21e of the opening 21 on the external space 24 side is accommodated inside the support body 4 in a plan view. According to such a configuration, the water jet can be prevented from directly reaching the seal surface formed between the seal ring 8 and the taper 23, and the effect of enhancing the waterproof property of the ventilation structure 50 can be obtained.

  As shown in FIG. 8, in the cross section including the axis O, the lower end of the seal surface (contact surface) formed between the seal ring 8 and the taper 23 is set as the reference inclined position 25, and the taper 23 at the reference inclined position 25 is set. Is defined as an opening reference line TL. In the cross section, two opening reference lines TL are defined. As shown in FIG. 7, the angle θ formed by these opening reference lines TL is, for example, in the range of 40 ° to 120 °. That is, it is desirable that the taper 23 of the opening 21 is not too steep and not too loose and has an appropriate angle. When the angle θ is set in such a range, it is possible to secure a wide seal surface between the seal ring 8 and the taper 23 while avoiding the enlargement of the size of the ventilation structure 50, which leads to enhancement of waterproofness of the ventilation structure 50. .

Further, the two opening reference lines TL intersect the support 4 on the lower surface of the base portion 11. The distance W ₂ from the intersection of the opening reference line TL and the support 4 to the axis O is smaller than the radius W _{1 in} plan view of the support 4. Such a configuration is advantageous in preventing direct water injection to the seal surface between the seal ring 8 and the taper 23.

  As shown in FIG. 2, in this embodiment, the ventilation member 10 is pushed in the direction of dropping from the housing 20 by the elastic restoring force of the seal ring 8. The leg portion 26 includes a claw 28 that is engaged with the peripheral portion of the opening 21 from the inner space 22 side of the housing 20 so that the ventilation member 10 is prevented from falling off from the housing 20. The nail | claw 28 is a part which has a shape convex to radial direction outward. According to such a configuration, it is possible to reliably prevent the ventilation member 10 from falling off the housing 20. The force (seal ring repulsive force) by which the seal ring 8 pushes the support body 4 upward is 20 to 350 N, for example. By appropriately adjusting the seal ring repulsive force, rotation and backlash of the ventilation member 10 can be prevented.

As shown in FIG. 2, the cover 6 is attached to the support 4 so as to cover the gas permeable membrane 2. A space AR ₁ is formed between the gas permeable membrane 2 and the cover 6. A space AR ₂ is also formed between the outer periphery of the cover 6 and the outer periphery of the support 4. These spaces AR ₁ and AR ₂ also function as a ventilation path between the internal space 22 and the external space 24.

  Specifically, the cover 6 includes a ceiling portion 31, an outer flange portion 32, and an inner flange portion 34. The ceiling part 31 has a size that covers the entire gas permeable membrane 2 in plan view. The outer flange portion 32 is a portion that extends downward from the periphery of the ceiling portion 31 toward the support body 4. The inner flange portion 34 is located between the gas permeable membrane 2 and the outer flange portion 32 in the radial direction, and extends downward from the lower surface of the ceiling portion 31 toward the support body 4. As shown in FIG. 9, the inner flange 34 also has an arc shape along the outer periphery of the gas permeable membrane 2 in plan view. A ventilation hole 7 is formed in the ceiling portion 31 so as to communicate the inside and the outside of the cover 6 between the inner flange portion 34 and the outer flange portion 31 in the radial direction.

  According to the cover 6, the inner flange 34 exists on the path from the vent hole 7 to the vent film 2. Since the inner flange portion 34 functions as a defense wall, the foreign matter cannot move straight from the vent hole 7 toward the vent film 2, and the vent membrane 2 can be prevented from being directly damaged by the foreign matter. In other words, a maze structure is formed in the cover 6. The vent hole 7 faces an inclined surface 37 formed on the outer peripheral portion of the support 4 (base portion 11). Therefore, the liquid splashed back to the inner flange 34 can be smoothly discharged out of the cover 6 through the slope 37. The inclined surface 37 is a surface inclined with respect to both the axial direction and the radial direction.

  In the present embodiment, the outer flange portion 32 and the inner flange portion 34 each extend to a position that coincides with the upper surface of the support body 4 (the upper surface of the base body portion 11). The outer flange 32 may extend to a position that covers the side surface of the support 4.

  As shown in FIG. 9, the ceiling part 31 has a circular shape in plan view. The ventilation holes 7 are formed at a plurality of locations along the circumferential direction of the ceiling portion 31 at equal intervals, and each of them has a shape of a long hole along the outer periphery of the ceiling portion 31. According to such a configuration, the liquid that has entered the inside of the cover 6 can be smoothly discharged to the outside of the cover 6 through the vent hole 7 regardless of the mounting posture of the ventilation member 10 to the housing 20.

  Further, the inner flange 34 is also divided into a plurality of arc-shaped portions so that the inner flange 34 is provided at a position corresponding to each of the plurality of vent holes 7. According to such a configuration, it is possible to sufficiently exert the role of the inner flange 34 as a defensive wall, and the liquid that has entered the cover 6 through the space between the two inner flanges 34 adjacent to each other. Can be smoothly discharged out of the cover 6.

  As shown in FIG. 2, in the present embodiment, the base portion 11 of the support 4 includes a first engagement portion 4 k for fixing the cover 6 to the support 4. The cover 6 also includes a second engagement portion 6k that engages with the first engagement portion 4k. The second engaging portion 6k is provided so as to protrude downward from the outer flange portion 32. With such a configuration, the cover 6 can be positioned with respect to the support 4.

  The support 4 and the cover 6 can be manufactured by a general molding method such as injection molding, compression molding, or cutting. A thermoplastic resin such as PBT (polybutylene terephthalate), PA (polyamide), or PET (polyethylene terephthalate) can be suitably used as the material for the support 4 and the cover 6. The material of the support 4 and the cover 6 may include a pigment, a filler, a water repellent material, and the like. Further, the surfaces of the support 4 and the cover 6 may be subjected to a water repellent treatment for urging the liquid to be removed.

(Second Embodiment)
As shown in FIG. 10, the ventilation structure 60 according to the second embodiment includes a housing 20 and a ventilation member 51 attached to the opening 21 of the housing 20. The ventilation member 51 includes a seal ring 18 having a V-shaped cross section. Constituent elements that are the same as or correspond to those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

  One seal surface is formed between the seal ring 18 and the taper 23, and another seal surface is formed between the seal ring 18 and the leg portion 26 of the support 4. Further, the upper end of the seal ring 18 is in contact with the base portion 11 of the support 4. The seal ring 18 also has an outer diameter smaller than the opening diameter of the opening 21 on the outer space 24 side in a state where the seal ring 18 is restored to its original shape. According to this seal ring 18, when a water pressure is applied from the outside, the seal ring 18 swells in the direction in which the V shape expands due to the water pressure, thereby improving the sealing performance.

  The ventilation members 10 and 51 described in each embodiment include not only the housing 20 having the opening 21 with the taper 23 but also the opening with no taper (that is, the opening having a constant opening diameter). It is applicable also to the housing | casing which has.

  The structure of the present invention can be used for a housing of automobile parts such as a lamp, a motor, a sensor, a switch, an ECU, and a gear box. Further, the present invention can be applied not only to automobile parts but also to electric products such as mobile communication devices, cameras, electric razors, and electric toothbrushes.

2 Ventilation membrane 3 Through-hole 4 Support body 4k First engagement portion 6 Cover 6k Second engagement portion 7 Vent holes 8, 18 Seal ring 10 Vent member 11 Base portion 20 Housing 21 Opening portion 22 Internal space 23 Taper 24 External Space 26 Leg portion 28 Claw 31 Ceiling portion 32 Outer flange portion 34 Inner flange portion 50 Ventilation structure O Axis line

Claims (12)

A ventilation structure comprising a housing having an opening for ventilation and a ventilation member attached to the opening,
The ventilation member includes: (i) a base portion in which a ventilation path is formed between an internal space and an external space of the housing; and a leg portion that extends from the base portion and is fitted in the opening. And (ii) a ventilation film disposed on the base portion so as to close the ventilation path on the external space side, and (iii) a seal ring provided at the base of the leg portion. ,
The opening is tapered so that the opening diameter increases as it goes from the inner space side to the outer space side,
The seal ring is made of a material having rubber elasticity, and is deformed along the taper by being sandwiched between the support and the housing in the opening.
A ventilation structure in which a gap facing a part of the seal ring protruding from the opening is formed between the lower surface of the base portion of the support and the surface of the housing.   2. The ventilation structure according to claim 1, wherein the seal ring has an outer diameter smaller than an opening diameter of the opening on the outer space side in a state where the seal ring is restored to its original shape. The seal ring has a circular cross-section with its original shape restored,
The ventilation structure according to claim 1 or 2, wherein a height h of the gap in the axial direction orthogonal to the radial direction of the opening is adjusted to be less than a collapsed width d of the seal ring.   The ventilation structure according to claim 1 or 2, wherein the seal ring has a V-shaped cross section. When a straight line parallel to the axial direction perpendicular to the radial direction of the opening and passing through the center of the opening is defined as an axis,
The ventilation structure according to any one of claims 1 to 4, wherein a surface profile of the taper exhibits a convex curve toward the external space in a cross section including the axis.   The ventilation structure according to any one of claims 1 to 5, wherein an edge of the opening on the external space side is accommodated inside the support in a plan view. The ventilation member is pushed in the direction of dropping from the housing by the elastic return force of the seal ring,
The leg includes a claw engaged with a peripheral portion of the opening from the inner space side of the casing so that the ventilation member is prevented from falling off from the casing. The ventilation structure according to any one of 6.   The ventilation structure according to any one of claims 1 to 7, wherein the casing is made of metal, and the taper of the opening is formed by pressing. The ventilation member further includes a cover covering the support from the side of the ventilation membrane;
The cover includes: (a) a ceiling portion that covers the entire breathable membrane in plan view; (b) an outer flange portion that extends downward from the periphery of the ceiling portion toward the support; It is located between the gas permeable membrane and the outer flange with respect to the radial direction of the opening, extends downward from the lower surface of the ceiling portion toward the support, and on the outer periphery of the gas permeable membrane in a plan view. An inner flange having an arcuate shape, and (d) formed on the ceiling so as to communicate the inner side and the outer side of the cover between the inner flange and the outer flange with respect to the radial direction. The ventilation structure according to claim 1, further comprising a ventilation hole. The ceiling has a circular shape in plan view;
The ventilation structure according to claim 9, wherein the ventilation holes are formed at a plurality of positions along the circumferential direction of the ceiling portion at equal intervals, and each of them has a long hole shape.   The ventilation structure according to claim 10, wherein the inner flange portion is also divided into a plurality of arc-shaped portions so that the inner flange portion is provided at a position corresponding to each of the plurality of ventilation holes. A ventilation member attachable to a housing having an opening for ventilation,
A support having a ventilation path between the internal space and the external space of the housing;
A ventilation membrane disposed on the support so as to close the ventilation path on the external space side;
A cover covering the support from the side where the gas permeable membrane is disposed,
The cover includes: (a) a ceiling part that covers the whole of the gas permeable membrane in plan view; (b) an outer flange part that extends downward from the periphery of the ceiling part toward the support; ) Located between the gas permeable membrane and the outer flange with respect to the radial direction of the cover, extends downward from the lower surface of the ceiling toward the support body, and has an outer periphery of the gas permeable membrane in plan view And (d) formed on the ceiling portion so as to communicate the inside and outside of the cover between the inner flange portion and the outer flange portion with respect to the radial direction. And a ventilation member.

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