The permanent magnet gearmotor

In today’s field of industrial automation and precision control, the permanent magnet gearmotor, as an efficient and reliable reduction motor, has become an essential part of various devices. This article will introduce in detail the principle, structure, application, and advantages of the permanent magnet gearmotor, to help readers better understand this important industrial transmission device.

Why do motors need gearmotor?

Torque: The torque of a motor is a key indicator of its output power, describing the torque that can be applied when the motor rotates. It is one of the basic parameters of a motor, with a unit of N/m.

The torque of a motor directly affects its performance and range of application. The greater the torque, the greater the static friction and inertia forces that the motor can overcome during startup, resulting in a stronger starting capability. At the same speed, a motor with a higher torque can drive a larger load.

Some motor used in electric vehicles and industrial machine tools require the use of gearmotors because they require higher torque and more precise speed control. The motor will reach its optimal load state under a certain load, at which point the motor efficiency is highest. If the torque is too large or too small, it will cause the motor to move away from its optimal working state and reduce efficiency.

Certain equipment or machinery requires a specific operating speed, which is usually lower than the rated speed of the motor. The gearmotor can adjust the output speed of the motor to meet these requirements.

During the start or stop process, the gearmotor can help reduce the impact and vibration caused by sudden acceleration or deceleration.

The gearbox provides an economical, effective and flexible way to increase torque. It allows the use of smaller, lighter and lower-cost motors to achieve the required torque and speed combination, while also providing more precise control. Therefore, in many practical applications, using a gearbox is the most practical solution.

Working principle of permanent magnet gearmotor

The reason why permanent magnet gearmotors can increase output torque is due to their working principle and design. The gearmotors usually contains one or more gear pairs inside, which mesh with each other at a fixed transmission ratio. When the speed of the motor is transmitted to the gearmotors, due to the different sizes of the gears, the larger gear will rotate at a lower speed, while due to the principle of energy conservation, the lower speed will be converted into a higher torque.

The relationship between torque (T) and power (P) can be expressed by the following formula:

T = P / ω​

Where T is torque, P is power, and ω is angular velocity (speed). 

From this formula, it can be seen that when the power remains constant, reducing the speed (ω) will lead to an increase in torque (T). This is the basic principle of how permanent magnet gearmotors work.

Type of permanent magnet gearmotor

1. Gear gearmotor

Gear gearmotors reduce speed through a series of meshing gears of different sizes. The small gear on the input shaft meshes with the large gear on the output shaft. Because the number of teeth on the gears is inversely proportional to the speed, when the small gear rotates at high speed, the large gear rotates at a lower speed. Due to energy conservation, the reduced speed is converted into increased torque.

2. Worm gear gearmotor

The main components of a worm gear gearmotor include a worm, a worm wheel, a box, and bearings. The worm is usually a spiral shaft, and its spiral shape matches the teeth of the worm wheel. When the worm rotates, the worm wheel rotates with it. Since the helical angle of the worm is smaller than the tooth angle of the worm wheel, the speed of the worm wheel is lower than that of the worm, thus achieving a reduction effect.

The spiral shape of the worm allows the worm wheel to move at a small angle when the worm rotates, thus achieving a significant reduction in speed. However, due to the high friction loss and relatively low efficiency of worm gear gearmotors.

3. Planetary gearmotor

The working principle of the planetary gear gearmotor is based on the interaction of the sun gear, planetary gears, and internal gears (or ring gears). The sun gear is located at the center, and the planetary gears rotate around the sun gear while also meshing with their outer internal gears. When the input shaft rotates, the planetary gears not only rotate but also revolve around the sun gear, while the internal gears remain stationary or rotate at a slower speed, achieving the effect of speed reduction. This structure can achieve high torque and compact design.

4. Belt gearmotor

permanent magnet gearmotor

The main components of a belt gearmotor include a drive wheel, a driven wheel, and a drive belt. Depending on the diameter of the wheel and the width of the belt, different reduction ratios can be achieved. Belt gearmotors are widely used in various mechanical and electrical equipment, especially in situations where smooth, low-noise transmission is required.

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