The principle of harmonic gear transmission was first proposed by engineer А.И.Москвитин in 1947 and invented by American engineer C.W.Musser in 1955.
A new transmission method that uses the elastic deformation of flexible working components to transmit motion or power has overturned the mode of mechanical transmission using rigid components, thereby obtaining a series of special functions that are difficult to achieve with other transmissions. The deformation process of the intermediate flexible component is basically a symmetrical harmonic of a cosine, hence the name.
Rigid wheel: a rigid circular component with gears engraved on the inner circumference, which have 2 more teeth than the flexible wheel and are usually fixed on the casing.
Flexible wheel: a thin-walled cup shaped metal elastic component with gears engraved on the outer circumference of the opening. The bottom of the flexible wheel is called the diaphragm and is usually installed on the output shaft.
Wave generator: it is a component that assembles a thin-walled ball bearing on the outer circumference of an elliptical cam. The inner wheel of the bearing is fixed on the cam, and the outer wheel can undergo elastic deformation through the ball, usually installed on the input shaft.
The reduction principle of harmonic gear transmission utilizes the relative motion of the flexible wheel, rigid wheel and wave generator (mainly the controllable elastic deformation of the flexible wheel) to achieve motion and power transmission. The elliptical cam inside the wave generator rotates inside the flexible wheel, causing deformation of the flexible wheel. When the flexible gear teeth and rigid gear teeth at both ends of the elliptical long shaft of the wave generator enter meshing, the flexible gear teeth at both ends of the short shaft detach from the rigid gear teeth. When the teeth between the long and short axes of the wave generator gradually enter a semi-meshing state along different sections of the circumference of the flexible and rigid wheels, it is called mesh in. When it is in a gradual withdrawal state, it is called mesh out. When the wave generator rotates continuously, the flexible wheel continuously undergoes deformation, causing the teeth of the two wheels to continuously change their original working states during mesh in, meshing, mesh out, and detachment, resulting in staggered tooth motion, achieving the transmission of motion from the active wave generator to the flexible wheel.
0 °: after the wave generator is installed in the flexible wheel, it forces the profile of the flexible wheel to change from the original circular shape to an elliptical shape. The teeth near the two ends of the long axis are fully engaged with the teeth of the rigid wheel, while the teeth near the two ends of the short axis are completely detached from the rigid wheel;
90 °: the rigid wheel is fixed, and the wave generator rotates in a clockwise direction. The flexible wheel generates elastic deformation, and the gear positions that mesh with the rigid wheel move in a counterclockwise direction
180 °: after the wave generator rotates 180 degrees clockwise, the flexible wheel only rotates one tooth counterclockwise
360 °: after the wave generator rotates 360 degrees (one revolution), the flexible wheel rotates counterclockwise by 2 teeth
