Automotive industry

As the important bearing application field, the automotive industry can be divided into engine bearings, transmission system bearings, steering system bearings, and air conditioner bearings according to the installation location. It can then be further subdivided into various components of the above systems, such as engines, clutches, transmissions, etc. Boxes, gearboxes, etc., are widely used. Therefore, changes in the automotive industry's market sentiment, overall production and sales, and supply and demand conditions can have a greater impact on the bearing industry.

Auto parts manufacturers are characterized by professionalism, independence, and globalized operations. After long-term development, the auto parts industry in developed countries has emerged several world-renowned companies with strong technology, sufficient capital, and large scale, mainly in Japan. , the United States, and Germany, occupying the main market share of mid-to-high-end products, achieving better revenue, and the development direction of the industry. These companies have adopted differentiated competitive strategies to form positions in segmented fields, such as Bosch and Continental in the automotive braking system field, and ZF and Aisin in the transmission field.

With the expansion of the automobile market and the rapid growth of global procurement, my country's auto parts industry supply system has gradually improved. my country has been deeply integrated into the global supply chain system and has become an important production and supply base. According to the "2022 Top 100 Global Auto Parts Suppliers List" released by "Automotive News", Japan, the United States, and Germany have 22, 21, and 18 companies on the list respectively, and my country has 10 companies on the list.

①Power device (components)

Case: alternator, turbocharger, etc.

②Steering device (component)

Case: steering gear, pump, etc.

③Power transmission device (component)

Case: transmission, differential gear, etc.

④Travel device (parts)

Case: wheels, suspension, etc.

The number of bearings used in high-end automobiles can reach about 150.

These bearings all play an important role.

If there are no bearings in the car, the components will not rotate smoothly, consume more energy, and the parts that support rotation will soon fail, resulting in the car being unable to operate safely and comfortably.

Due to the wide range of uses, the diversity and complexity of bearing varieties are determined. The bearing manufacturing industry is a precision basic parts manufacturing industry. Its accuracy is measured in 0.001 mm, while the manufacturing tolerance of ordinary mechanical parts is generally only 0.01 mm. ​

The component assemblies that use bearings on cars include engines, generators, water pumps, clutches, transmissions, differentials, steering gears, air conditioners, etc. The main bearing types are small deep groove ball bearings, tapered roller bearings, cylindrical roller bearings, angular contact ball bearings, and needle roller bearings. The matching proportions of various types of bearings are 27% deep groove ball bearings, 23% tapered bearings, 15% needle roller bearings, 6% water pump bearings, 5% cylindrical roller bearings, and 24% other bearings. ​

The component assemblies using bearings on commercial vehicles include water pumps, transmissions, drive shafts, generators, differentials, front and rear wheel hubs, steering systems, etc. The main bearing types include tapered roller bearings, deep groove ball bearings, needle roller bearings, and cylindrical roller bearings.

New energy electric vehicles are green, environmentally friendly, zero-emission energy vehicles that the country has advocated and developed in recent years. Drive motors, batteries, and controllers are the core components of new energy vehicles and the heart of new energy vehicles.
Rolling bearings are rotating parts of drive motors. High speed, high temperature, frequent starts and stops, and impact are the main working conditions of electric vehicle drive motors. We have developed a series of sealed deep groove ball bearings that can adapt to these working conditions to meet the requirements of hybrid buses, pure electric buses, pure electric passenger cars, pure electric mini cars, and other series of new energy vehicle drive motors. and are widely used in the market. The design and application characteristics of motor bearings are as follows:

Rolling bearings are rotating parts of drive motors. High speed, high temperature, frequent starts and stops, and impact are the main working conditions of electric vehicle drive motors. The design of new energy drive motor bearings takes into account conditions such as good sealing performance, high-temperature performance, low-temperature performance, repeated start and stop performance, certain axial impact load, etc., optimizes the internal structure of the product and fully considers bearing materials, heat treatment, and machining accuracy. , grease, and installation coordination on the product, greatly improving product performance, and the limit speed can reach more than 1.5 times the speed of conventional bearings.

(1) Speed

Operating speed affects both bearing and grease life. Therefore, bearing size, cage type, lubrication method, clearance, and seal type must be considered when selecting a bearing. The speed currently used in new energy vehicle drive motors can reach up to 18,000 rpm, and the dmn value can reach more than 800,000.

(2) Environment

In environments with humidity, low temperature, high temperature, and a lot of mud, water, and dust, sealing and sealing material are particularly important. It is necessary to consider the impact of sealing on the product; it is necessary to prevent lubricant leakage from causing pollution to the environment and products. At the same time, grease leakage will cause the bearing to be short of oil and affect the service life of the bearing.

(3)Temperature

Bearing temperature is one of the main factors affecting machine life. When the operating temperature difference between the ambient temperature and the bearing temperature is large, the bearing will produce a temperature gradient. If the temperature gradient is large, check the internal clearance of the bearing to avoid unnecessary bearing damage.

(4) Bearing accuracy

The precision level of new energy vehicle drive motor bearings all reaches the P6 level, the internal parameters can reach P5, and they have extremely high rotational stability and low noise performance (the noise level can reach Z3).

Electric vehicle bearings achieve breakthroughs

Switching from an internal combustion engine to an electric motor, and from a fuel tank to a battery, is not something that happens overnight - the emergence of electric vehicles requires us to rethink the design of all car parts.

For example, high-performance bearings are needed for a motor that rotates at 30,000 rpm to keep up with the high speed. Bearing technology is changing to accommodate the demands of electric vehicles, with suppliers looking to provide OEMs with stronger, more durable components.

What are the major developments in optimizing bearings? How do they improve motor performance?

OEMs are demanding significant improvements in quality and performance to be able to offer reliable electric vehicles to their customers. As a result, suppliers are redesigning bearings and polymer cages so that the entire unit can withstand the higher speeds, accelerations, and temperatures that characterize motor operation.

Additionally, higher speeds require a more efficient lubricant and one that can maintain its viscosity and be of high quality.

In this regard, Dr. Farrukh Qureshi, a technical researcher at Lubrizol, said that “depending on the vehicle configuration and design, there will be several drivetrain configurations”.

“If the motor is embedded in the transmission or axle and submerged in lubricating oil, the electrical and thermal conductivity of the fluid will be very important. However, there is a lack of consensus among OEMs on electrical and thermal conductivity goals”.

He added: “Friction and wear protection of gears, bearings and seals is also important. Motor output speeds may exceed 25,000 rpm, which requires proper lubrication of relevant bearings, seals, and other components.”

Hybrid ceramic bearings

Steel bearings are currently the industry standard for electric motors. However, despite the high efficiency of the motor and inverter, one feature that affects traditional steel bearings is the high-frequency voltage switching of the inverter, which can create current leakage, especially at high motor speeds. This current sometimes flows through the actual bearing, causing surface pitting and soon after, catastrophic failure of the component.

Anders Thormann of CeramicSpeed said: “Current flow through bearings can also create micro-welds in the passage from the rolling elements to the races, weakening the steel and damaging the raceways – a phenomenon known as galvanic corrosion. A large number of frequency converters are running at higher Operating at frequencies greatly accelerates this problem and thus creates common-mode voltages that are difficult to isolate accurately due to the high frequency.

This is where the advantages of hybrid or ceramic bearings come into play because they do not conduct electricity.

Due to their galvanically insulating properties, hybrid bearings are 40% less dense than steel bearings. This allows them to operate at lower temperatures, require less lubrication, and last up to ten times longer than steel bearings.

According to a study by the Danish Institute of Technology (DTI), due to the reduced friction of ceramic hybrid bearings, operating temperatures can be 10 to 40 Kelvin lower than equivalent standard bearings in the same motor. This results in longer service life for grease, bearings, and motors.

Thormann said: "Ceramic hybrid bearings are not affected by any current flow because the resistivity of the ceramic material is higher than that of air, resulting in an effective insulation distance equal to the entire ball diameter. Unlike coatings that are insulated The 0.1mm of insulation in the bearings makes a world of difference. It’s that simple – problem solved”

Challenges posed by drive motors to motor bearings

For motor bearings used in general industrial motors, the domestic bearing industry has continued to develop. With the improvement of the theoretical level of bearing design, the advancement of bearing steel material technology, the improvement of ferrule processing equipment, and the technology level, the level of steel ball manufacturing has risen. , has replaced imports and occupied the main domestic market, but the characteristics of the automobile drive motor's wide speed range, large starting torque, high power density, and high efficiency make it suitable for high speed, high and low temperature, durability, stability, and reliability of the bearings. At present, domestic new energy vehicle motor bearings still mainly rely on imports.

1. Speed: The driving motor speed is as high as 20,000r/min, and the bearing dm. n value reaches more than 800,000, which is much higher than the speed of ordinary industrial motors.

2. Temperature: -40~150 ℃, the bearing operates stably without whistling; the long-term operating temperature is 110~120 ℃; the starting temperature in cold areas is -30~-20°C, the starting torque is small, and the noise is low. ​

3. Lubrication: The grease is required to have low-temperature performance, high-temperature resistance, vibration resistance, energy saving and high efficiency, and long life.

4. Vibration and noise: To ensure the comfort of the car, the vibration and noise level of the motor should be low to ensure quietness in the car.