Valve device and assembly method of valve device

1. A valve device comprising:

a housing having a cylindrical internal peripheral wall in which a columnar space is formed;

a fluid introduction path being formed in the housing and communicating with the space in the internal peripheral wall;

a fluid discharge path being formed in the housing and communicating with the space in the internal peripheral wall;

a valve element having a communication path inside that brings the fluid introduction path and the fluid discharge path into communication with each other, and having, when seen along an axis center of the space in a state of being stored in the space, a major radial portion formed with a predetermined first internal radius associated with an internal radius of the internal peripheral wall of the housing, a minor radial portion formed with a second internal radius smaller than the first internal radius, and an intermediate portion that has an internal radius equal to or less than the first internal radius and equal to or more than the second internal radius and that is formed in such a way as to join the major radial portion and the minor radial portion together;

a valve element rotation mechanism having the axis center as a rotation axis center and rotating the valve element inside the space;

a seal member being provided on the internal peripheral wall and being able to contact the valve element rotating inside the space; and

a shaft inserted in the space through a through-hole formed in the housing in such a way that the axis center of the valve element stored in the space in a state of being out of alignment with the rotation axis center is aligned with the rotation axis center in accordance with the seal member and an internal radius of the valve element.

2. The valve device according to claim 1 , wherein

the valve element is provided with a valve-element-side through-hole coaxially with the axis center of the valve element on a side where the through-hole in a state where the valve element is stored in the space is formed, the valve-element-side through-hole including a guide portion gradually decreasing in internal diameter as the guide portion becomes apart from the through-hole and guiding entry of the shaft, a first internal diameter portion communicating with the guide portion and being formed with a predetermined first internal diameter, and a second internal diameter portion communicating with the first internal diameter portion and being formed with a second internal diameter smaller than the first internal diameter,

the shaft includes a first external diameter portion formed with a first external diameter associated with the first internal diameter, and a second external diameter portion coupled to the first external diameter portion and formed with a second external diameter associated with the second internal diameter, and

an axial length of the second external diameter portion is configured to be greater than a sum of an axial length of the first internal diameter portion and an axial length of the second internal diameter portion.

3. The valve device according to claim 1 , wherein

a range which an external edge portion of the minor radial portion and an external edge portion of the intermediate portion account for relative to an external edge portion of the valve element when the valve element is seen along the axis center of the valve element is 180 degrees.

4. The valve device according to claim 1 , wherein

a diameter reduction amount of the minor radial portion relative to the major radial portion is, in a state where the axis center of the valve element is aligned with the rotation axis center by the shaft, equal to or more than a collapse amount of the seal member in a state where the major radial portion is in contact with the seal member.

5. The valve device according to claim 1 , wherein

the seal member is provided in a state of being tilted relative to the axis center of the space when the seal member is seen along a direction parallel to both a diametrical direction of the space and a diametrical direction of the seal member.

6. An assembly method of a valve device, comprising:

a valve element mounting step of mounting a valve element in a columnar space formed inside a base housing, the valve element including, in a plan view, a major radial portion formed with a predetermined first internal radius associated with an internal radius of an internal peripheral wall of the base housing, a minor radial portion formed with a second internal radius smaller than the first internal radius, and an intermediate portion that has an internal radius equal to or less than the first internal radius and equal to or more than the second internal radius and that is formed in such a way as to join the major radial portion and the minor radial portion together;

a seal member fitting step of fitting a seal member between an internal peripheral wall of the space and the valve element in a state where an axis center of the space and an axis center of the valve element are not aligned with each other;

a fastening and fixing step of fastening and fixing a lid housing that closes an opening part of the base housing, to the base housing, by use of a fastening member; and

an insertion step of inserting a shaft into a valve-element-side through-hole provided along the axis center of the valve element in such a way that the axis center of the valve element and the axis center of the space are aligned with each other, while being guided by a guide portion that passes through a through-hole formed in the lid housing and that gradually decreases in internal diameter as the guide portion becomes apart from the through-hole provided on the through-hole side of the valve element.