HARMONIC DRIVE THAT IMPROVES TRANSMISSION ACCURACY

摘要

A harmonic drive includes a rigid internal gear, a flexible external gear meshed with the rigid internal gear, and a wave generator abutted against the flexible external gear. Through a special parameter setting to design the outer peripheral edge of the wave generator in a surface of variable curvature, the contact area between the wave generator and the flexible external gear is increased to improve fretting wear, thereby enhancing transmission accuracy and reducing hysteresis error.

主权项

1. A harmonic drive, comprising:
a rigid internal gear; a flexible external gear rotatably mounted within said rigid internal gear; and a wave generator rotatably mounted within said flexible external gear, said wave generator comprising an axle bearing and an elliptic wheel mounted in said axle bearing, said axle bearing comprising an outer peripheral edge abutted against an inner perimeter of said flexible external gear, the radius of curvature of said outer peripheral edge in the YZ plane being defined as RGX, RGX=√{square root over (yx2+zx2)}, the relationship between yx and zx satisfying the ellipse parametric equation of:
yx+{ax+cax×(sin(4θ−(π/2))+1)}×sin θ·0≦θ≦2πzx+{bx+cbx×(sin(4θ−(π/2))+1)}×sin θ·0≦θ≦2π wherein ax is the semi-major axis of said outer peripheral edge of said axle bearing of said wave generator in the YZ plane before insertion of said elliptic wheel; cax is the semi-major axis correction factor; bx is the semi-minor axis of said outer peripheral edge of said axle bearing of said wave generator in the YZ plane before insertion of said elliptic wheel; cbx is the semi-minor axis correction factor; θ is the centrifugal angle of said outer peripheral edge of said wave generator in the YZ plane.