August 13,2026
In recent years, the greenhouse effect has become increasingly severe, and public environmental awareness has grown continuously. Vehicle exhaust is a major contributor to the urban greenhouse effect, and the development of new energy vehicles (NEVs) is of great significance in addressing exhaust pollution. Bearings are critical components of NEVs, and their performance directly determines the comfort and safety of the vehicles.
It is estimated that by 2025, the NEV bearing market will reach RMB 14.2 billion, mainly comprising drive motor bearings, hub bearing units, transmission bearings, steering system bearings, etc. Among these, drive motor bearings are important components that supply power to NEVs. Facing the demanding operating requirements of NEV bearings, their performance requirements are becoming increasingly stringent. Developing high-performance NEV drive motor bearings has become a key focus for major automotive and bearing manufacturers.
NEVs have demanding requirements for bearings, including long life, creep resistance, high speed, low friction, low vibration, etc. Specific requirements are as follows:
(1) High speed: Drive motor speeds can reach up to 20,000 r/min, with bearing Dmn values (product of mean diameter and inner ring speed) exceeding 800,000, much higher than those of ordinary industrial motors.
(2) High temperature: Bearings must operate stably at -40 to 150 °C without squealing; long-term operating temperature is 110–120 °C; starting temperatures in cold regions are -30 to -20 °C, with low starting torque and low noise.
(3) Lubrication: The grease must exhibit excellent low-temperature performance, high-temperature resistance, vibration resistance, energy efficiency, and long life.
(4) Vibration and noise: To ensure passenger comfort, the motor's vibration and noise levels must be low to maintain a quiet cabin environment.
(5) Electrical corrosion: Imbalances in the windings can create potential differences between rotors, generating currents; current leakage caused by high-frequency voltage from inverters can also lead to electrical corrosion and bearing failure.
(6) Life: Bearings must match the vehicle warranty period (5–8 years or 100,000–160,000 km).
2.1 Overseas Research Status
NTN Corporation has developed electrically corrosion‑resistant insulated coated bearings for the three‑electric systems (e‑Axle) of pure electric (EV) and hybrid (HEV) vehicles. An insulating film layer is applied to the outer diameter and end faces of the bearing outer ring, capable of withstanding voltages above 100 V and exhibiting excellent insulating properties.
NTN has also developed an anti‑electrical‑erosion bearing, i.e., an insulated coated bearing for electric vehicle axles, which suppresses current passing through the bearing by applying an insulating coating on the bearing surface. The insulation performance of this bearing reaches above 100 V, supporting high‑voltage batteries. The insulating coating has a low friction coefficient and excellent wear resistance, and compared with standard products without the coating, the total wear amount of the outer ring outer diameter and housing inner diameter is reduced by 88%. Thus, even if the outer ring creeps, the coating maintains the required insulation.
SKF has released a revolutionary high‑speed deep groove ball bearing for e‑drive systems, the HSBB1.8, with a maximum Dmn value of 1.8 million. Taking a 40 mm shaft diameter as an example, it can meet motor speeds up to 30,000 r/min.
SKF has developed the Drive ball bearing series, which optimises raceway design, adopts new‑structure polymer cages, and uses greases with a wide temperature range, as well as hybrid ceramic bearings, to meet the high‑speed performance requirements of motor bearings, helping to extend transmission system service life and increase battery range.
NSK has developed a new generation of creep‑resistant bearings for drive systems such as hybrid/electric vehicle transmissions, improving passenger comfort by suppressing creep. The product features include:
① Optimised bearing ring rigidity prevents ring deformation, thereby minimising the increase in wall thickness while effectively improving resistance to creep caused by static gear loads.
② Use of O‑ring material with superior durability in high‑temperature oil environments, and optimisation of its compression deformation, reduces creep caused by rotational loads from motor imbalance by 80% when the bearing is exposed to high‑temperature oil.
③ Improved creep resistance without mechanical fixation makes assembly easier, thereby enhancing productivity and reducing costs.
NSK has also developed the NSK LCube Ⅱ™ tapered roller bearing for electric vehicle transmissions. Product features include:
① In harsh lubrication conditions with thin oil films, microscopic concave portions are formed on the rolling surfaces and heads of tapered rollers to retain oil, improving oil film retention on contact surfaces and preventing wear and surface damage. Durability and seizure resistance are eight times or more than current products.
② Oil retention performance in the low‑speed range (where oil films are more easily formed) is improved, reducing friction by 10% compared with current products.
Schaeffler's TriFinity is a three‑row hub bearing that is smaller than standard double‑row ball bearings but offers higher load capacity, longer service life, and greater stiffness. In addition, its innovative design can replace preloaded tapered roller hub unit solutions. Compared with tapered roller bearings, TriFinity significantly reduces friction torque and increases stiffness, and under the FTP75 test cycle, it can reduce power consumption by 0.7% per vehicle. Moreover, combined with Schaeffler's face spline technology, the hub unit size is reduced. The miniaturisation not only reduces bearing and seal friction but also lowers bearing mass, thereby reducing the carbon footprint. For the same dimensions, bearings with zero‑clearance face spline technology are lighter and can transmit 50% more torque. In addition, installation is more convenient, and noise is reduced in electric vehicles. The high‑efficiency ball bearing with centrifugal disc is a new product developed specifically by Schaeffler for electric vehicles, offering high performance, low friction and energy savings. Combining the design advantages of open and sealed bearings, a single bearing can reduce friction by 0.3 N·m and reduce CO₂ emissions by about 0.1 g/km. The service life of this high‑efficiency ball bearing is ten times that of open bearings, significantly reducing operating costs.
Renben Group has developed the high‑speed BS series bearing specifically for NEV drive motors. Adopting new designs, new processes and new materials, optimising internal bearing structures, and using simulation and lubrication technologies, it solves the problems of bearing heating and lubrication under high speed and high temperature. The company has established a design theory and methodology for NEV drive motor bearings, ensuring high precision, low centrifugal force, low friction, and the ability to meet NEV requirements for low starting torque, high speed and rapid gear changes, durability and high reliability.
Zhejiang Wuzhou Xinchun Group Co., Ltd. has developed the drive motor bearing 6008-2RZG. Through optimised ring parameters, cage design, non‑contact sealing structure, and the use of long‑life, low‑noise, high‑ and low‑temperature‑resistant grease, the bearing meets the requirements for high‑speed, high‑temperature, and long‑life ring operation, ensuring stable high‑speed performance, low noise, and extended life under high‑speed and high‑temperature operation, as well as during rapid or variable speed operation.
Chongqing Changjiang Bearing Co., Ltd. (hereinafter referred to as "Changjiang Bearing") has made new breakthroughs in high‑temperature and high‑speed NEV reducer bearings, high‑temperature and high‑speed NEV drive motor bearings, and key technologies for NEV hub bearing units. In particular, for NEV hub bearing units, Changjiang Bearing successfully solved challenges such as simultaneously meeting stiffness and strength requirements in lightweight designs, dynamic balancing after weight reduction, and process difficulties caused by product deformation after lightweighting, achieving a 30% weight reduction.
ZWZ has supplied reducer series bearings to a well‑known European international automotive manufacturer for its pure electric and plug‑in hybrid vehicles. By using special materials and specialised heat treatment processes, the bearing life has been increased to meet NEV supporting requirements, and mass production has been achieved. ZWZ NEV bearings feature high precision, high speed, high load capacity, long life, low friction and low noise.
High‑speed performance is a difficult challenge in developing NEV drive motor bearings, and China enterprises have no directly applicable experience to draw upon. Products must not only achieve high‑speed performance indicators in design and theoretical calculations, but also pass high‑speed performance tests, simulated bench tests and road tests to ensure reliability and durability under high‑speed conditions. Therefore, product development involves a wide range of fields, long lead times, and requires consideration of cost‑effectiveness and overcoming competition from international brands in order to achieve industrialisation.
Bearing design needs to be optimised to reduce friction and wear while maintaining stability at high speeds. Specific countermeasures include:
① Grease optimisation: develop grease‑lubricated high‑speed bearings for drive motors used in hybrid and pure electric vehicles.
② Cage shape optimisation: for deep groove ball bearings used in hybrid and pure electric vehicles, steel cages and crown‑type resin cages are employed. The crown‑type resin cage is lighter than the steel cage, has relatively lower centrifugal force at high rotational speeds, and has a smaller friction coefficient between the steel balls and the cage pockets, reducing heat generation between the balls and the cage.
③ Use of high‑rigidity resin materials: resin cage materials used at high speeds must have high rigidity to limit deformation caused by centrifugal force.
Yu Qingfeng systematically analysed the force sources and corresponding stress and strain states of cages in high‑speed deep groove ball bearings, finding that the cage's own centrifugal force is the most significant factor. He proposed a high‑speed cage design scheme, verified by simulation using Abaqus and CABA3D software, and passed bench tests and customer installation tests.
Due to the thermal effects of motors and power electronics, the operating temperature environment of NEV bearings is higher than that of conventional vehicles. This requires bearing materials to withstand higher operating temperatures without degrading performance. Special alloy materials, ceramic materials, and surface coating technologies offer possibilities for manufacturing bearings that meet NEV requirements. These materials can provide better wear resistance, corrosion resistance and temperature stability.
With the development of the NEV industry, the corrosion problem of electric vehicle drive motor bearings has also drawn increasing attention. Bearings are important components in the drivetrain; once corroded, they can cause vehicle instability and ultimately lead to safety issues.
Specific countermeasures include:
① Optimise bearing structure, such as enhancing sealing and using anti‑corrosion lubricants.
② Use high‑performance materials with corrosion resistance, such as special materials and specialised treatment processes to improve corrosion resistance.
③ Improve bearing lubrication capability, such as enhancing lubrication between parts and using highly corrosion‑resistant lubricants.
④ Carry out regular maintenance and inspection of bearings.
Traditional automotive bearings face a reshuffle. In the future, electric vehicles will adopt electric drive, eliminating the engine, transmission, driveshaft, etc. of conventional fuel vehicles. Some products in the automotive bearing industry, such as generator bearings, water pump bearings, rocker arm bearings, and tensioner bearings, will face a reshuffle. NEV bearings bring both new business opportunities and challenges to bearing manufacturers.
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