What are the factors that affect the efficiency of micro reduction motors

What is the function of a deceleration motor? The deceleration motor has two main functions. Firstly, they obtain the torque generated by the power source (input) and multiply it. Secondly, as the name suggests, a deceleration motor reduces the input speed to achieve the correct output speed.

How can a deceleration motor increase torque while reducing speed? The output gear of the reduction motor has more teeth than the input gear. Therefore, although the output gear may rotate slower, thereby reducing the input speed, the torque increases.
 

Therefore, they use input power to increase torque while reducing speed.

There are various shapes and sizes of reduction motors, but some common reducers are gearboxes, which is the reason for the decrease in efficiency of micro reduction motors. The main reason for the decrease in efficiency of micro reduction motors is the increase in various losses, such as copper loss, iron loss, mechanical loss, etc. The large copper loss of micro reduction motors.

There are many factors that affect the efficiency of micro reduction motors, which can be roughly divided into the following main categories:

1. Efficiency of motor body:

Copper loss: Joule heat loss (I ² R) caused by current flowing through the resistance of the stator winding. The higher the current and winding resistance, the greater the loss. Micro motors have thin wire diameters, relatively high resistance, and significant copper loss.

Iron loss (core loss):

Hysteresis loss: The loss caused by the flipping and friction of magnetic domains in an alternating magnetic field when the core material is repeatedly magnetized. Related to material properties (coercivity), frequency, and magnetic flux density.

Eddy current loss: Joule heat loss caused by eddy currents induced in the iron core by an alternating magnetic field. It is related to material resistivity, laminate thickness, frequency, and magnetic flux density. Solid iron cores or thicker laminations are commonly used in micro motors, which may result in significant eddy current losses.

Mechanical wear and tear:

Friction loss of bearings: Friction loss of rotor bearings (ball bearings or oil containing bearings). Poor lubrication, excessive preload, and pollution can all increase losses.

Wind friction loss: The loss caused by the friction between the rotor and air during rotation. The speed of micro motors is usually not high, and the wind and friction losses are relatively small, but they cannot be ignored at high speeds.

Stray losses: Additional losses that are difficult to accurately calculate, such as those caused by harmonic magnetic fields in conductors and iron cores.

Reversing loss (brushed motor): The loss caused by the voltage drop (I * V_drop) between the brush and the commutator, as well as the loss caused by commutation sparks. This is one of the main sources of loss unique to brushed DC motors, and its efficiency is usually lower than that of brushless motors.

2. Efficiency of reduction gearbox:

Gear meshing friction loss: This is the main source of loss for gearboxes. include:

Sliding friction: Friction generated by relative sliding between tooth surfaces.

Rolling friction: Friction generated at the rolling contact points between tooth surfaces.

Influencing factors:

Gear design: Whether the design of tooth profile (involute, arc), modulus, pressure angle, helix angle, tooth surface modification, etc. is reasonable directly affects the contact stress and sliding rate.

Gear accuracy: Processing accuracy (tooth profile error, tooth orientation error, tooth pitch error) and assembly accuracy directly affect meshing smoothness and contact area. Low accuracy results in high friction loss and noise. The precision challenge in micro gear machining is significant.

Gear series: Each gear transmission has an efficiency loss (usually between 90% -98%, with micro gears possibly lower), and the more series, the lower the overall efficiency.

Gear type: Planetary gears have a compact structure and usually have high efficiency (up to 90-95%+); Worm gear has a large single-stage reduction ratio but low efficiency (usually 40-70%, or even lower), and is usually irreversible.

Materials and Heat Treatment: Strength, Hardness, Wear Resistance, and Friction Coefficient of Gear Materials. Surface treatments such as carburizing and quenching, nitriding, and coating can improve wear resistance and reduce friction.

Lubrication:

Lubricating grease performance: viscosity, base oil type, viscosity, extreme pressure anti-wear additive performance. Excessive viscosity increases agitation resistance, while low viscosity leads to insufficient oil film strength and increased boundary lubrication friction.

Lubricating grease filling amount: Too much leads to significant oil loss during agitation, while too little results in insufficient lubrication.

Lubrication method: grease lubrication is the mainstream for micro gearboxes, while oil lubrication may have higher efficiency but poses greater sealing challenges.

Bearing loss: Friction loss generated by the bearings supporting the gear shaft inside the gearbox (similar to the principle of motor bearing loss).

Oil stirring loss: The resistance loss caused by stirring the grease when the gear rotates in the lubricating grease. Significant in high-speed or high viscosity lubricating grease.

3. System matching and working conditions: