Structure for mounting dynamic damper on rotary shaft and rotary shaft equipped with dynamic damper

A method for mounting a dynamic damper on a rotary shaft, comprising the step of:

• preparing the rotary shaft where bending vibration is occurred and the dynamic damper including (i) a mass member with a cylindrical shape and (ii) a first and second elastic support members respectively formed on axially opposite end portions of the mass member with a predetermined axial distance therebetween to elastically support the mass member and allow the mass member to be relatively displaced while the mass member is mounted on the rotation shaft;
• mounting the dynamic damper on the rotary shaft, such that an axial center of the mass member is spaced axially apart from a position of a loop of the bending vibration on the rotary shaft, the mass member having a center of gravity at a position deviated from the axial center thereof toward a first end of axially opposite ends;
• and
• fixing the first and second elastic support members to the rotary shaft, upon the mass member being mounted on the rotary shaft such that the axial first section having the center of gravity of the mass member is located closer to the position of the loop of the bending vibration on the rotary shaft than an axial second section, whereby the dynamic damper is mounted on the rotary shaft.