The key role of heat treatment in electric transmissions

The key role of heat treatment in electric transmissions

At a time when new energy vehicles are booming, electric transmissions are one of the core components, and their performance directly affects the operating efficiency and service life of the vehicle. The heat treatment process plays an indispensable role in the manufacturing process of electric transmissions. It is like a finishing touch, injecting excellent performance and reliability into the key components of electric transmissions.

1. Improvement of the performance of electric transmission gears by heat treatment

(I) Enhance the bearing capacity of gears
During the operation of electric transmissions, gears are subjected to huge loads and stresses. Through heat treatment processes such as carburizing and quenching, the hardness and wear resistance of the gear surface can be significantly improved while maintaining the toughness of the core. This surface hardening and good core toughness structure enable the gear to effectively resist deformation and wear when subjected to high loads, thereby greatly improving the bearing capacity of the gear. Studies have shown that the tensile strength and yield strength of the 20CrMnMo automotive transmission gear shaft after optimized heat treatment process have been significantly improved, by 8% and 7.76% respectively.

(II) Improve the fatigue resistance of gears
Fatigue is one of the main forms of gear failure. Heat treatment can improve the residual stress distribution of gears and form a layer of beneficial residual compressive stress on their surface. This layer of residual compressive stress can offset part of the working stress, delay the initiation and expansion of fatigue cracks, and thus significantly improve the fatigue resistance of gears. Using a strong honing process to treat heat-treated gears can not only reduce the surface wear caused by grinding, avoid the resonance and noise generated during the meshing of transmission gears, but also make the tooth surface have a large residual compressive stress, significantly increasing the fatigue resistance of gears.
(III) Improve the meshing performance of gears
Heat treatment has an important influence on the microstructure of gears, which can make the tooth surface of gears smoother and flatter, and reduce the roughness and micro defects of the tooth surface. This helps to improve the meshing accuracy of gears, reduce the noise and vibration of gears during operation, and improve the running smoothness and comfort of the entire transmission. In addition, heat treatment can also improve the dimensional stability of gears, reduce gear deformation caused by temperature changes, and ensure the meshing performance of gears under different working conditions.

2. Optimization of the overall performance of electric transmission by heat treatment
(I) Improving the transmission efficiency of the transmission
The transmission efficiency of the electric transmission directly affects the power output and energy utilization efficiency of the vehicle. Gears and other key components that have been heat treated can reduce friction and energy loss between gears due to their high surface hardness and good wear resistance, thereby improving the transmission efficiency of the transmission. This means that under the same power input, the electric transmission that has been optimized by heat treatment can transfer more energy to the wheels, improving the vehicle’s cruising range and power performance.
(II) Enhancing the reliability and life of the transmission
As a core component of the vehicle, the reliability and life of the electric transmission are crucial. The heat treatment process can comprehensively improve the comprehensive mechanical properties of the transmission components, enabling them to work stably during long-term operation and reduce the probability of failure. For example, pre-heat treatment of the gear blank using an isothermal normalizing process can effectively reduce heat treatment deformation, improve the processing performance and use performance of the gear, and thus enhance the overall reliability and life of the transmission.
(III) Adapting to the special working environment of the electric transmission
Compared with traditional mechanical transmissions, the working environment of the electric transmission is more special. It needs to operate under high speed, high torque, and frequent start-stop and shifting conditions. After heat treatment, the parts can better adapt to this special working environment and maintain stable performance and good working condition. At the same time, heat treatment can also improve the corrosion resistance and oxidation resistance of the parts, making them less prone to damage and failure under harsh working conditions.

III. Enhancement of reliability and life of electric transmission by heat treatment
(I) Ensure the stable performance of key parts
The stability of the performance of key parts in electric transmission, such as gear shafts and bearings, is directly related to the reliability and life of the entire transmission. Through precise heat treatment process control, it can be ensured that these key parts maintain good mechanical properties and dimensional stability during long-term operation. For example, the special heat treatment technology “HA-C” developed by NTN Co., Ltd. of Japan has achieved high load-bearing capacity, high-temperature dimensional stability, pollution-resistant lubricity and high wear resistance of bearings, and has contributed to the miniaturization, lightweight and energy saving of automobile drive devices.
(II) Reduce the failure rate and maintenance cost of the transmission
The electric transmission optimized by heat treatment has a significantly improved performance of its parts, and the probability of failure is greatly reduced. This means that the number of repairs and maintenance costs caused by transmission failures can be reduced during the use of the vehicle. At the same time, reliable transmission performance can also improve the overall safety of the vehicle and the user experience.
(III) Extending the service life of the transmission
The comprehensive improvement of the performance of electric transmission components by heat treatment technology enables the transmission to maintain a good working condition during long-term operation and reduce the wear and damage of components. This not only extends the service life of the transmission, but also reduces the full life cycle cost of the vehicle, and improves the economy and environmental protection of the vehicle.

IV. Innovative application and future prospects of heat treatment in electric transmissions
(I) Development and application of special heat treatment technology
With the continuous development of new energy vehicle technology, the requirements for the performance of electric transmissions are getting higher and higher. Some special heat treatment technologies have emerged, such as NTN Corporation’s “HA-C” technology, which provides new solutions for improving the performance of key components of electric transmissions. These special heat treatment technologies can significantly improve their load-bearing capacity, wear resistance and fatigue resistance without increasing the size and weight of the components, providing strong support for the miniaturization, lightweight and high-performance development of electric transmissions.
(II) Deep integration of heat treatment technology and electric transmission design
In the future, heat treatment technology will be more closely integrated with the design of electric transmissions. By fully considering the impact of heat treatment on the performance of components in the design stage and optimizing the structure and material selection of components, the heat treatment process can better play its advantages and further improve the overall performance and reliability of electric transmissions. At the same time, with the help of advanced computer simulation technology and data analysis methods, the heat treatment process parameters can be controlled more accurately to realize the intelligence and automation of the heat treatment process.
(III) Development of environmental protection and energy-saving heat treatment technology
Under the general trend of environmental protection and energy conservation, the heat treatment industry is also constantly exploring and innovating. Developing more environmentally friendly and energy-saving heat treatment technology and equipment, and reducing energy consumption and pollutant emissions during heat treatment are important directions for the development of heat treatment technology in the future. For electric transmission manufacturers, this can not only reduce production costs, but also improve the market competitiveness of products, which meets the requirements of sustainable development.

In short, heat treatment plays a vital role in electric transmissions. It improves the overall performance, reliability and life of electric transmissions by optimizing the performance of key components, and provides strong support for the development of new energy vehicles. With the continuous advancement and innovation of technology, heat treatment processes will play a more important role in the field of electric transmissions and promote the new energy vehicle industry to a new height.