On the stage of industrial manufacturing, precision reducers play a crucial role. Among the many types of reducers, harmonic gear reducers, cycloidal planetary reducers, RV reducers, precision planetary reducers, and filter gear reducers each have their own application fields. In the field of articulated robots, harmonic gear reducers and RV reducers receive much attention.
Harmonic Gear Reducer
Structure: The harmonic gear reducer is composed of a flexible spline, a wave generator, and an output wheel. The flexible spline generates harmonic motion through the wave generator, driving the output wheel to achieve speed reduction.
Working Principle: The wave generator continuously produces periodic radial deformations, causing the flexible spline to bend and deform, thereby driving the rotation of the output wheel.
Characteristics: Harmonic gear drives feature ultra-high precision transmission, compact structure, and backlash-free motion. They are often used in precision instruments, spacecraft, robots, and other high-precision applications.
RV Reducer
Structure: The RV reducer is composed of an input shaft, an eccentric wheel, several cycloidal pin gears, and an output shaft. The cycloidal pin gears connect with the input shaft and output shaft through the movement of the eccentric wheel.
Working Principle: When the input shaft rotates, the eccentric wheel drives the cycloidal pin gears to rotate, achieving speed reduction through the continuous meshing of the cycloidal pin gears.
Characteristics: RV reducers have a compact structure, high transmission efficiency, and large output torque. They are commonly used in applications requiring high torque and reverse functionality.
Typically, RV reducers are arranged at the base, large arm, shoulder, and other heavy-load positions, mainly acting on robot joints over 20 kilograms. In contrast, harmonic gear drives are more frequently found in the small arm, wrist, or hand, suitable for robot joints under 20 kilograms. Meanwhile, planetary reducers are widely used in Cartesian robots.
Harmonic gear drives are composed of four basic components: the "flexible wheel, wave generator, rigid wheel, and bearing". The outer diameter of the flexible wheel is slightly smaller than the inner diameter of the rigid wheel, generally with the flexible wheel having 2 fewer teeth. The wave generator is elliptical, causing the contact points of the flexible and rigid wheels' teeth to be distributed at two opposite positions in the center of the ellipse. During the rotation of the wave generator, the teeth contact parts of the flexible and rigid wheels begin to mesh.
For every 180° clockwise rotation of the wave generator, the flexible wheel equivalently rotates 1 tooth difference in the counterclockwise direction to the rigid wheel. In two symmetrically opposed places at 180°, more than 30% of all teeth mesh simultaneously, achieving high torque transmission by the harmonic gear drive.
In summary, understanding the differences between harmonic gear drives and RV reducers helps in selecting the most suitable reducer for industrial robots, thereby improving manufacturing efficiency and precision.
