Advantages and disadvantages of both RV reducers and harmonic reducers

update:2022-05-23

abstract:As a precision reducer as the core component of industrial robots, compared with general reducers, r...

As a precision reducer as the core component of industrial robots, compared with general reducers, reducers for robots are required to have the characteristics of short transmission chain, small size, high power, light weight and easy control. RV reducer has higher fatigue strength, rigidity and life. Unlike harmonic drive, the motion accuracy will be significantly reduced with the increase of use time. The disadvantage is that it is heavy in weight and large in size.

▲RV-E type reducer harmonic reducer: used for industrial robots with small loads or several axes at the end of large robots, harmonic reducer is a kind of harmonic drive device, harmonic drive device includes harmonic accelerator harmonic wave reducer. The harmonic reducer mainly includes: rigid wheel, flexible wheel, bearing and wave generator, all of which are indispensable. Among them, the number of teeth of the rigid wheel is slightly larger than that of the flexible wheel. The characteristics of harmonic reducer used in small robots are small size, light weight, large bearing capacity, high motion accuracy, and large single-stage transmission ratio.

▲Both of the harmonic reducers are meshed with small tooth difference. The difference is that a key gear in the harmonic is flexible. It needs repeated high-speed deformation, so it is relatively fragile, and its bearing capacity and life are limited. RV usually uses cycloidal pinwheels. Harmonics used to use involute tooth shape. Now some manufacturers use double arc tooth shape, which is much more advanced than involute tooth shape.

The elliptical shape of the wave generator determines that the contact points of the teeth of the flexible and rigid gears are distributed on two opposite sides between the center of the ellipse.

During the rotation of the wave generator, the contact parts of the flex wheel and the rigid wheel teeth begin to mesh. Every time the wave generator rotates 180° clockwise, the flexible wheel is equivalent to one tooth difference when the rigid wheel rotates counterclockwise. At two places with 180° symmetry, more than 30% of the total number of teeth mesh at the same time, which also creates its high torque transmission. Compared with the harmonic reducer, the RV transmission is a new type of transmission. It is developed on the basis of the traditional needle pendulum planetary transmission. It not only overcomes the shortcomings of the general needle pendulum transmission, but also has the advantages of small size, light weight, It has a series of advantages such as large transmission ratio range, long life, stable precision, high efficiency and stable transmission.

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