Servo Planetary Gear Reducers - Serve You Just Right!

Posted on Dec 13, 2020

Servo Planetary Gear Reducer

The servo planetary gear reducer serves as a speed reducer and a torque booster. Multiplying torque makes it easier to run the machine with a much smaller engine, saving both resources and energy. The position of the servo planetary gear as a speed reducer is just as significant in some applications as its torque multiplier feature.

The servo planetary gear reducer is a type of gear system. To decrease the number of engine revolutions to the necessary one and achieve high torque, it uses a gearbox speed converter. How does it operate for a planetary gearbox? From the framework, we will understand more about this. Planetary gear, sun gear, and ring gear are the principal frameworks of the planetary servo gearbox. 

The ring gear is in direct contact with the gearbox's inner housing. The middle of the ring gear comprises an additional force-driven sun gear. There is a planetary gear set between the sun gear and the ring gear, composed of three gears equally placed on the planetary carrier, floating between them on the output shaft support, the crown rim, and the sun gear. The planet gears are made to rotate when the sun gear is actuated by the input power and then rotate with the orbit of the ring gear around the core. Let us take a closer look at why servo planetary gear reducers are an awesome tool.
 

Main Functions of a Servo Planetary Gear Reducer

The servo planetary gear reducer serves as a speed reducer and a torque booster. Multiplying torque makes it easier to run the machine with a much smaller engine, saving both resources and energy. The position of the servo planetary gear as a speed reducer is just as significant in some applications as its torque multiplier feature. Crystal growth, for example, involves the incremental raising of the ball from the drum that holds the molten material. The entire assembly should be turned quite steadily, at a pace of 15 ° per hour to keep the crystal as round, smooth, and uniform as possible. Tight angular velocity control is provided by the servo mechanism, but the servo motors typically do not perform well or produce high torque at low speeds. The inclusion of a gearbox helps the servo motor to work from a control point of view at the maximum speed while producing a limited amount of torque that is raised by the gear ratio to the appropriate degree.
 

Why the 'servo' in Servo Planetary Gear Reducer Matters?

In servo applications - one where a feedback device is used to control the torque, position, or speed of a linear or rotary system - the ratio of load inertia to motor inertia is a critical factor in system performance. The lower inertia ratio allows the motor to control the load more accurately and to avoid overshoot and oscillation, improving system response. If the actual inertia of the load cannot be changed, adding gear to the system can reduce the amount of inertia of the load reflected back to the motor, essentially making the motor appear as if there is less inertia to transfer.

The gearbox reduces reflected load inertia by the square of the gear ratio, so adding a gearbox can significantly improve the system inertia ratio. The gears also multiply the torque from the motor to the load by an amount proportional to the gear ratio, while lowering the required motor speed by the same amount. In some applications, this means that a smaller motor can be used and the motor can run at a higher, more efficient speed.
 

:: Read More: The Beauty of Planetary Gearbox For Servo Motor

Main Advantages of Servo Planetary Gear Reducers

Servo planetary gears use three kinds of gears to transmit torque: planetary gears, sun gear, and ring gear. The attached motor drives the sun gear which is located in the center of the gear assembly. Many planetary gears work with both the sun gear and the ring gear, which are stationary and fixed inside the gearbox housing. As the sun gear rotates, it drives the planet gears to rotate around their axes and rotate around the sun gear. The planetary gear positions are set by the yoke, which also includes the output shaft.

With this arrangement, the load is distributed over multiple gear teeth, giving planetary designs high rigidity and contributing to low backlash - only 1 to 2 minutes of arc on some designs. High stiffness is also important in applications that require frequent start-stop cycles or changes in direction of rotation.

Planetary designs are also compact, providing high reduction factors in a small overall package. This compact design also means they have low inertia, which is especially advantageous in servo applications as the inertia of the gearbox directly increases the inertia of the load that the motor has to balance. And although planetary gears, like other designs, can be lubricated with grease or oil, most of them are lubricated by the manufacturer with grease and require no re-lubrication or maintenance throughout the life of the gearbox. Other advantages of servo planetary gear reducer include:
 

Torque Multiplication

Servo planetary gears provide a mechanical advantage when mounted on the motor output shaft. The number of gears and the number of teeth on each provides the mechanical advantage defined by the gear ratio. If the engine produces 100 pounds per inch. torque, connecting a 5: 1 servo planetary gear reducer generates an output torque close to 500lb-in. depending on the efficiency of the servo planetary gearbox.
 

Speed ​​Reduction

Planetary servo gears are often called gear reducers as most of them increase the output torque while reducing the output speed. The motor working at a speed of 1000 rpm, equipped with a planetary servo gear with a gear ratio of 5: 1, reaches 200 rpm. This speed reduction improves system efficiency as many engines are not efficient at low RPM. For example, with a grinding mechanism that must run at fifteen, the meshing of the motor causes the rotation of the wheel to be inconsistent. The varying resistance of the polished stone also makes the rotation of the wheel unpredictable. In contrast, mounting a 100:1 servo planetary gear reducer on the motor allows it to run at 1,500 rpm. The combination of motor, gear, and headstock provides a more consistent output force and smooth wheel rotation despite friction and load variations.
 

Matching Inertia

Over the past 20 years, servo manufacturers have introduced lightweight materials, dense copper windings, and high-energy motor magnets that generate more torque for given frame sizes. While favorable, this trend increased the risk of inertia mismatch between the servo motors and the loads they control.

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