Sliding contact-type wave generator, strain wave gearing, and wave-generating method

A wave generator of a strain wave gearing comprising:

• a rigid wave generator plug provided with a non-circular external peripheral surface;
• and
• a wave generator bearing fitted to the non-circular external peripheral surface and made to flex into a non-circular shape;
• wherein the wave generator bearing is provided with an inner race, an outer race, and an annular body fitted between the inner race and the outer race in a state of sliding contact;
• and
• the annular body is composed of an endless coil spring, the annular body having a rigidity capable of maintaining a fixed gap between the inner race and the outer race, and a flexibility in a radial direction of the annular body so as to be capable of flexing into a non-circular shape following the inner race;
• wherein an external peripheral surface of the inner race is provided with an inner race track surface having a recessed arcuate cross-section with which an external peripheral surface portion of the annular body comes into sliding contact, and
• an internal peripheral surface of the outer race is provided with an outer race track surface having a recessed arcuate cross-section with which an internal peripheral surface portion of the annular body comes into sliding contact.