Torque generating device

A torque generating device comprising:

• a magnetic disk configured to have rotational motion around a rotation axis;
• a first yoke located on one side and a second yoke located on an other side across the magnetic disk, the first yoke having an annular portion and a cylindrical portion that extends concentrically from the annular portion, the annular portion having an outer periphery on an annular portion outside diameter, the cylindrical portion having an outer periphery on a cylindrical portion outside diameter, the cylindrical portion outside diameter being less than annular portion outside diameter to define a step portion on the outer periphery of the cylindrical portion,
• an annular coil having an inner periphery and an outer periphery on an annular coil outside diameter, the annular coil outer diameter being greater than the annular portion outer diameter, the annular coil disposed in the step portion such that the inner periphery of the annular coil is disposed along the outer periphery of the cylindrical portion and such that the annular coil overlaps the magnetic disk when viewed in a direction along a direction in which the rotation axis extends;
• a third yoke of which at least a region proximity to the magnetic disk is located on an outer side of the magnetic disk and the coil and that makes up a magnetic path of a magnetic field that is generated by the coil in cooperation with the first yoke and the second yoke;
• and
• a magnetic viscous fluid filled between the magnetic disk and each of the first yoke and the second yoke, wherein:
• the third yoke has a magnetic gap between the third yoke and the first yoke, and
• the magnetic gap is at a position on an outer side of an outer peripheral edge of the magnetic disk or a position that overlaps the outer peripheral edge of the magnetic disk when viewed in the direction along the direction in which the rotation axis extends.