Ventilation housing
A ventilation housing of the present disclosure includes: a housing; and a ventilation assembly. The housing includes a tubular projection extending to project from an outer surface and internally having a first space communicating the inside and the outside of the housing. The ventilation assembly includes: an internal member being a tubular body having an opening at a first end portion and an opening at a second end portion; a gas-permeable membrane covering the opening at the first end portion of the internal member; and an external member being a tubular body having a bottom, the external member being joined to the internal member with the internal member inserted in the interior of the external member from the first end portion side. The ventilation assembly is fixed to the projection with the projection inserted in the opening at the second end portion of the internal member to make an inner peripheral surface of the internal member and an outer peripheral surface of the projection abut each other. The ventilation assembly has a second space serving as a ventilation path connecting the gas-permeable membrane and the outside of the ventilation assembly in the inside of the internal member, the inside of the external member, and/or an interspace between the two members. A ratio between an area S 1 of a cross-section of the first space and a smallest total area S 2 min determined by comparison of values of different total areas determined at different distances from the gas-permeable membrane, the total areas each being determined for a cross-section(s) of the second space, is 1.0 or more. A ratio between the area S 1 and a total area S 2 out of a plane consisting of a cross-section(s) of the second space taken at a position(s) where the second space is the narrowest is more than 1.0. This ventilation housing exhibits excellent performance in terms of moisture permeation between the inside and the outside of the housing.
1. A ventilation housing comprising:
a housing; and
a ventilation assembly, wherein
the housing comprises a tubular projection extending to project from an outer surface of the housing and internally having a first space communicating an inside and an outside of the housing,
the ventilation assembly comprises:
an internal member being a tubular body having an opening at a first end portion and an opening at a second end portion;
a gas-permeable membrane covering the opening at the first end portion of the internal member; and
an external member being a tubular body having a bottom, the external member being joined to the internal member with the internal member inserted in an interior of the external member from a side of the first end portion,
the ventilation assembly is fixed to the tubular projection with the tubular projection inserted in the opening at the second end portion of the internal member to make an inner peripheral surface of the internal member and an outer peripheral surface of the tubular projection abut each other,
the ventilation assembly has a second space serving as a ventilation path connecting the gas-permeable membrane and an outside of the ventilation assembly in at least one selected from an inside of the external member and an interspace between the internal member and the external member joined together,
a ratio S 2 min /S 1 between an area S 1 of a cross-section of the first space taken along a plane perpendicular to a central axis of the tubular projection and a smallest total area S 2 min determined by comparison of values of different total areas determined at different distances from the gas-permeable membrane is 1.0 or more, the total areas each being determined for a cross-section of the second space taken along a plane perpendicular to a ventilation direction in the ventilation path, the cross-section being located at a certain distance from the gas-permeable membrane, a ratio S 2 out /S 1 between the area S 1 of a cross-section of the first space taken along a plane perpendicular to a central axis of the tubular projection and a total area S 2 out of a plane consisting of a cross-section of the second space taken at a position where the second space is the narrowest when the second space is observed from the second end portion side along a central axis of the ventilation assembly is more than 1.0,
a distance H is a greater height selected from a height H 1 of the internal member and a height H 2 of the tubular projection,
a sum of the distance H and an insertion depth of the external member is 17 mm or less, and
the ventilation assembly has a moisture permeation rate of at least 55.6 gm −2 h −1 .
2. The ventilation housing according to claim 1 , wherein the height H 1 of the internal member is 6.0 mm or more and 10 mm or less.
3. The ventilation housing according to claim 1 , wherein the ratio S 2 out /S 1 is 1.5 or more.
4. The ventilation housing according to claim 1 , wherein a length of a portion of the internal member in a direction along a central axis of the ventilation assembly is 6.0 mm or more and 8.0 mm or less, the portion being covered by the external member.
5. The ventilation housing according to claim 1 , wherein the external member and/or the internal member has a locking mechanism detachably joining the external member and the internal member together.