Blade resistance adjustment structure and exercise machine having the same

A blade resistance adjustment structure, comprising:

• a rotating shaft, extending in an axial direction;
• a blade seat, connected to the rotating shaft, the blade seat being rotated along with the rotating shaft;
• a plurality of blades, surrounding the rotating shaft, the blades each including a free end and a pivot end opposite to the free end, the pivot end being pivotally connected to the blade seat, the blades each extending along a reference line between the pivot end and the free end, the blades each having a pivot portion between the pivot end and the free end;
• a sliding seat, slidably fitted onto the rotating shaft in the axial direction, wherein a distance from an axis of the rotating shaft to an outermost edge of the free end on the reference line and perpendicular to the axial direction is defined as a radius of rotation;
• a plurality of connecting members, each having one end pivotally connected to the sliding seat and another end pivotally connected to the pivot portion of a corresponding one of the blades;
• wherein when the rotating shaft is driven to rotate by an external force, the blades are rotated synchronously around the rotating shaft in a fluid to obtain a rotational resistance;
• wherein when the sliding seat is driven to move in the axial direction by an adjustment force, each blade is rotated with the pivot end as a fulcrum to change an opening and closing angle between the reference line and the axis, so that the radius of rotation changes along with the opening and closing angle, thereby changing the magnitude of the rotational resistance.