Ventilation component and ventilation structure

A ventilation component comprising:

• an internal member including an elastic material and having an open tubular structure;
• a gas-permeable membrane covering one opening of the internal member;
• and
• an external member having a closed tubular structure, wherein
• the internal member is fixed to the external member such that the internal member is inserted inside the external member and that a portion of an outer circumferential surface of the internal member is elastically deformed to form a first contact portion with a portion of an inner circumferential surface of the external member,
• the ventilation component is capable of being fixed to a projection of a housing such that the projection is inserted inside the internal member through the other opening of the internal member and that an inner circumferential surface of the internal member is elastically deformed to form a second contact portion with an outer circumferential surface of the projection, the projection tubularly protruding from an outer surface of the housing toward an edge of a ventilation opening allowing communication between an inner space of the housing and an outer space of the housing,
• the first contact portion is placed between a center of a portion of the internal member and the one opening, the center being defined in an axial direction of the internal member, the portion overlapping the external member in the axial direction,
• an inner diameter of the external member is larger than an outer diameter of the internal member between the first contact portion and the other opening in the axial direction of the internal member,
• a combination of the internal member and the external member includes a protruding portion arranged on the inner circumferential surface of the external member or the outer circumferential surface of the internal member, the protruding portion forming the first contact portion, and
• around an axis of the internal member, a gap is present by the protruding portion and between the inner circumferential surface of the external member and the outer circumferential surface of the internal member.