Meshing and disengagement of harmonic reducer teeth

update:2022-10-19

abstract:When the wave generator is the active element, the cam rotates in the flex wheel, causing the flex w...

When the wave generator is the active element, the cam rotates in the flex wheel, causing the flex wheel and the thin-walled bearing to undergo controllable elastic deformation. The teeth of the rigid wheel are completely meshed at the long axis of the wave generator, and the teeth in the short axis direction are completely disengaged.

When the motor drives the wave generator to rotate continuously in the flex wheel, it forces the flex wheel to produce continuous elastic deformation, so that the four states of the flex wheel teeth of meshing-meshing-meshing-out-disengagement cyclically change their respective original meshing state. This phenomenon is called staggered-tooth movement, and it is this staggered-tooth movement that, as a reducer, can change the input high-speed rotation into the output low-speed rotation.

For the harmonic gear transmission of the dual-wave generator, when the wave generator rotates 1/8 turn clockwise, the flexible gear teeth and the rigid gear teeth will be meshed from the original meshing state, and the original disengaged state will become engaged state. In the same way, the meshing becomes disengaged, and the meshing becomes meshing, so that the flexible wheel rotates (angular displacement) by 1/4 tooth relative to the rigid wheel; for the same reason, when the wave generator rotates another 1/8 turn, repeat the above process , then the flexible wheel is displaced by a pitch. By analogy, when the wave generator rotates relative to the rigid wheel for one cycle, the displacement of the flexible wheel relative to the rigid wheel is two pitches.

The meshing process of the flexible gear teeth and the rigid gear teeth at the pitch circle is like two pure rolling (no sliding) rings. At any instant, the arc lengths of the two rotating on the pitch circle must be equal. Since the flex wheel has two pitches less on the pitch circumference than the rigid wheel, during the meshing process of the flex wheel, it must rotate an angular displacement of two pitches relative to the rigid wheel, and this angular displacement is exactly the output shaft of the reducer. Rotation to achieve the purpose of deceleration.

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