US Patent 11680652 Valve device

A valve device is configured to adjust an opening degree of a flow path for fluid, and includes an axial member, a valve body, and a biasing member. The axial member is configured to be fixed to the flow path. The valve body is rotatable about the axial member, and is configured to be rotated in a closing direction in which the opening degree is reduced, and to be rotated, by the use of a fluid flowing down through the flow path, in an opening direction in which the opening degree is increased. The biasing member is provided to the axial member inside the flow path, and is configured to bias the valve body to rotate in the closing direction.