1. Introduction

2. The Role of Gear Transmission in Electric Drive Systems

• Power Transmission: It transfers the power generated by electric motors to loads, such as vehicle wheels and robotic arms, serving as a bridge between the power source and the execution end.

• Torque Amplification: Through the design of appropriate reduction ratios, gear transmission amplifies the torque output by the motor to meet the high-torque requirements of loads under different working conditions (e.g., NEV startup and heavy-duty robot operation).

• Speed Regulation: By engaging gear pairs with different numbers of teeth, it adjusts the output speed, enabling the system to adapt to varying speed demands, such as high-speed cruising of NEVs and precise low-speed positioning of robots.

• Precision Control: It enhances the dynamic response and positioning accuracy of the system. For instance, in robotic joints, high-precision gear transmission ensures that the robot can achieve millimeter-level movement accuracy.

3. Key Factors in Gear Transmission Design for Electric Drive Systems

3.1 Gear Type Selection

• Involute Gears: The most widely used type, featuring stable transmission and high precision, making them suitable for high-precision transmission scenarios like industrial machine tool spindles.

• Planetary Gears: With a compact structure and high torque density, they are the preferred choice for NEV reducers, as they can save installation space while delivering strong torque output.

• Helical Gears/Spur Gears: Helical gears operate with low noise and high smoothness due to their inclined tooth surface design, which ensures a larger contact area during meshing. They are ideal for high-speed applications such as electric motor output shafts.

• Harmonic Gears: Characterized by zero backlash, they are widely used in precision robotic transmissions (e.g., robotic arm joints) to achieve ultra-high positioning accuracy.

3.2 Material Selection

• Steel Gears: Materials like 20CrMnTi and 40Cr are commonly used. They offer high strength and wear resistance, making them suitable for heavy-load transmission scenarios, such as NEV main reducers and industrial gearboxes.

• Powder Metallurgy Gears: These gears are lightweight and cost-effective, making them applicable to small electric motors in household appliances and light-duty industrial equipment.

• Plastic/Composite Gears: With low noise and low manufacturing costs, they are used in low-load transmission systems, such as auxiliary components of electric vehicles and small-scale automation equipment.

3.3 Gear Parameter Optimization

• Module (m): Determines the strength of the gear teeth. A larger module indicates thicker teeth and higher load-carrying capacity, so it must be matched with the motor power to avoid tooth breakage under overload.