Screw motion mechanism and damping apparatus using same

A damping apparatus, comprising:

• a threaded shaft having an outer peripheral surface provided with a helical thread groove, the threaded shaft having at least one axial end coupled to a first structural body;
• a nut member held in a rotatable manner with respect to a second structural body and threadedly engaged with the threaded shaft, the nut member being configured to perform a reciprocating rotation along with vibration of the second structural body with respect to the first structural body;
• damping means coupled to the nut member, for damping the reciprocating rotation of the nut member;
• and
• a spherical joint for coupling the at least one axial end of the threaded shaft to the first structural body, the spherical joint comprising:
• a spherical portion;
• and
• a sphere receiving portion for housing the spherical portion,
• wherein the spherical portion and the sphere receiving portion are spaced from the nut member in the axial direction of the threaded shaft,
• wherein a rotational torque transmitted between the nut member and the threaded shaft varies in accordance with an axial force applied to the threaded shaft,
• wherein a sliding torque transmitted between the spherical portion of the spherical joint and the sphere receiving portion of the spherical joint also varies in accordance with the axial force applied to the threaded shaft, and
• wherein, on a graph of torque and axial force of the threaded shaft, a line of the rotational torque intersects with a line of the sliding torque, and the sliding torque exceeds the rotational torque under an initial state in which the axial force is not applied to the threaded shaft.