Valve device

A valve device comprising:

• a housing in which a gas flow path through which a gas flows and an accommodation space that communicates with the gas flow path and accommodates a rotation shaft are formed;
• a valve body that is arranged in the gas flow path and adjusts an opening of the gas flow path;
• the rotation shaft that is arranged in the accommodation space and rotates around an axis to rotate the valve body;
• a seal member that is arranged in the accommodation space so as to be positioned around an outer peripheral surface of the rotation shaft and is slidably in close contact with the outer peripheral surface of the rotation shaft to prevent passage of the gas between the rotation shaft and the housing;
• and
• an annular attachment ring that is arranged in the accommodation space so as to be positioned around the outer peripheral surface of the rotation shaft and attaches the seal member to the housing, wherein
• the seal member has an outer peripheral end-side part, and the outer peripheral end-side part is in a shape of a plate extending radially outward from the rotation shaft side along a radial direction of the rotation shaft,
• the attachment ring has:
• a first-side plate part that is positioned on a first side of an axial direction of the rotation shaft with respect to the seal member and is in a shape of a plate extending along the radial direction;
• and
• a second-side plate part that is positioned on a second side of the axial direction with respect to the seal member and is in a shape of a plate extending along the radial direction,
• the first-side plate part and the second-side plate part sandwich and hold the outer peripheral end-side part of the seal member in the axial direction,
• the housing has, as inner wall surfaces forming the accommodation space, a tubular wall surface that surrounds the attachment ring and a facing surface that faces the second-side plate part in the axial direction,
• the attachment ring is fixed to the housing in a state where the attachment ring is in contact with the tubular wall surface and the second-side plate part is in contact with the facing surface,
• the second-side plate part has an inner surface in contact with the seal member, the inner surface of the second-side plate part has an end inside in the radial direction serving as an inner peripheral end of the second-side plate part, and the first-side plate part has an inner surface in contact with the seal member, the inner surface of the first-side plate part has an end inside in the radial direction serving as an inner peripheral end of the first-side plate part, the inner peripheral end of the second-side plate part being positioned outside in the radial direction beyond the inner peripheral end of the first-side plate part,
• the first-side plate part has an outer surface which is a surface of the first-side plate part on the first side of the axial direction, and the outer surface of the first-side plate part includes an outer peripheral-side region that is positioned outside in the radial direction beyond the inner peripheral end of the second-side plate part and an inner peripheral-side region that is positioned inside in the radial direction beyond the outer peripheral-side region, and
• the outer peripheral-side region is positioned on the first side of the axial direction with respect to the inner peripheral-side region.