How planetary gear motors can increase motor torque without increasing motor volume

"Gear progression" refers to the number of layers or stages of gear transmission in a planetary gear reducer, which is a key factor in determining the size of the reduction ratio and the complexity of the structure.

Layman's Explanation:

You can think of the "gear progression" as a "deceleration step":

• First-stage gears: There is only one set of sun gears → planetary gears → internal ring gears, which is the most basic layer of deceleration.

• Second-stage gear: On the basis of the first-stage gear, a group of gears of the same structure is connected to continue to decelerate.

• Three-stage gears: add one more set for a total of three-stage transmissions.

The reduction ratio of the planetary gear is obtained by multiplying the reduction ratio of each stage, that is, the total reduction ratio = the first reduction ratio x the second reduction ratio x the third reduction ratio

The superposition of three-stage gears can reach a reduction ratio of hundreds to one, which is improved from the application of power tools and smart locks to ultra-high torque, industrial robotic arms and lifting platforms under heavy loads.

Added: Reduction ratio size judgment

Example is a comparison of 30:1 and 300:1 reduction ratios

1. 30:1 means that the motor rotates 30 times, and the output shaft outputs one turn, the motor output speed is faster, but the output torque is smaller.

2. 300:1 means that the motor rotates 300 times, and the output shaft outputs one turn, the motor output speed is slower, but the output torque is relatively larger.

So in terms of reduction ratio output torque, 300:1>30:1

How to Increase Motor Torque

In many cases, due to limited equipment space and planning costs, the planetary gear motor cannot meet the output torque requirements, in this case, you may wish to consider the following measures;

1. Increase the Gear Ratio

• Principle: By increasing the reduction ratio, the torque of the output shaft can be increased without increasing the motor volume.

• Manner:

  Increase the number of gear stages (e.g. from one stage to two stages, three stages). 

  Each gear set remains in the same housing, keeping it compact.

• Note: When the reduction ratio increases, the output speed decreases, and the relationship between speed and torque needs to be weighed.

2. Improve the transmission efficiency of the planetary gear system

• High-precision machining of gears and high-hardness materials such as alloy steel is used to reduce friction between gears.

• Needle roller bearings are used instead of plain bearings to reduce energy loss.

• Improved lubrication systems, such as the use of synthetic grease or oil film lubrication structures, reduce energy consumption and heat generation, and improve transmission efficiency.

3. Optimize the output characteristics of the motor body (within the same volume)

• Switch to a brushless DC motor (BLDC) or rare earth permanent magnet motor to increase the output torque per unit volume.

• Improve the filling rate of copper wire and the heat dissipation efficiency of the winding, and improve the power density of the motor.

• Improve the stator groove structure or air gap magnetic density, and improve the electromagnetic torque output capacity.

4.The "coaxial multi-planetary" design is adopted

• For example, using multiple planetary wheels in the same planetary carrier (from 3 to 4 or 5):

• It can effectively distribute the load and improve the ability to transmit torque per unit time.

• The overall bearing capacity is increased without changing the diameter of the shell.

5. Use high-strength and lightweight materials

• Replace the internal structural parts with titanium alloys, high-strength steels or engineering plastics to reduce weight and increase torque bearing.

• Precision forging and heat treatment techniques allow for higher gear strength without the need for oversizing.

You have to know:

The fundamental purpose of the planetary gear motor to increase torque is to drive heavier, harder to start, and more inertial loads.

The increase in torque is likely to achieve the desired results, such as increased start-up power, smoother work, and a more reliable system. But it's important to be aware of the problems that can arise: slower output speeds, greater impact of inertial loads, increased power consumption, increased heat generation, and slower responses.

Don't panic when these problems occur, since the problem arises, it is bound to force a solution, if you have related troubles, please actively contact us, we are always online.