The basic components of the flat-type gear system are the Wave
Generator and three gearwheels - the Flexspline, Circular Spline
and Dynamic Spline.
The Wave Generator consists of a sun gear, typically connected
to the motor shaft, and two elastically deformable planet gears.
The teeth of the planet gears engage with the internal teeth of
the Flexspline, which also features external teeth that engage
with the Circular and Dynamic Spline.
The Flexspline is a thin-walled elastically deformable ring,
that adopts the elliptical shape of the Wave Generator. The external
teeth of the Flexspline engage with the internal teeth of both
the Circular Spline and the Dynamic Spline.
The Circular Spline is an internally toothed ring gear and engages
with the Flexspline at both ends of the major elliptical axis
of the Wave Generator. The Circular Spline possesses two teeth
more than the Flexspline.
The Dynamic Spline is an internally toothed ring gear with the
same number of teeth as the Flexspline. This component rotates
in the same direction and with the same speed as the Flexspline
and is used as output element when the gear is used as a speed
reducer.
Principle of Operation
The Micro Harmonic Drive gear is based on a unique principle
of operation. When used as a speed reducer, the Wave Generator
acts as the input element. By means of the planet gears the Wave
Generator deforms the Flexspline elliptically, such that it engages
with both internally toothed ring gears, the Circular Spline and
the Dynamic Spline. The rotation of the planet gears of the Wave
Generator causes the major elliptical axis and thereby the regions
of tooth contact to rotate relative to the fixed Circular Spline.
Because the Flexspline possesses two teeth less than the Circular
Spline, for each 180° clockwise movement of the Wave Generator,
the Flexspline moves counterclockwise by one tooth relative to
the Circular Spline. Each complete clockwise rotation of the Wave
Generator results in the Flexspline moving counterclockwise by
two teeth from its previous position relative to the Circular
Spline. The Dynamic Spline rotates in the same direction and with
the same speed as the Flexspline and is used as the output element.
