Automotive bearings have developed rapidly in recent years. In order to meet the development trend of high performance, high power, more comfortable and more durable in the automotive market, VBF has invested more energy in automotive bearings, and gradually developed many high temperature resistant, long life, Products with high reliability are widely used in automobile engines, belt tensioners, steering wheels, air-conditioning fans, seat window adjustment motors, etc.
New energy electric vehicles are green and zero-emission new energy vehicles advocated and developed by the state in recent years. The driving motor, battery and controller are the core components of new energy vehicles, as well as the heart of new energy vehicles.
Rolling bearings are rotating parts of driving motor. High speed, high temperature and frequent start-stop accompanied by impact are the main working conditions of electric vehicle driving motor. The development of serialized sealed deep groove ball bearings that can adapt to the working conditions can meet the requirements of a series of new energy vehicle driving motors, such as hybrid buses, pure electric buses, pure electric passenger cars and pure electric minicars. And has been widely used in the market. The bearing design of new energy drive motor takes into account good sealing performance, high temperature performance, low temperature performance, repeated start-stop performance, certain axial impact load and other conditions, optimizes the internal structure of the product, fully considers the bearing material, heat treatment, machining accuracy, grease, installation and match influence on the product, so that the product performance has been greatly improved. The limit speed can reach 1.5 times more than the limit speed of conventional bearings.
Running speed affects the life of bearing and grease simultaneously. Therefore, bearing size, cage type, lubrication mode, clearance and seal type must be considered when selecting bearings. At present, the speed of the motor used for driving new energy vehicles can reach up to 18,000 RPM, and the dmn value can reach more than 800,000.
Due to the expansion and contraction of the material, the expansion coefficient should be considered when selecting the material of shaft and shell. Heat expansion and cold contraction will directly affect the fit of shaft and housing, thus affecting the bearing internal clearance. The shaft of the drive motor field is usually made of medium carbon steel and tempered, and the shell is usually made of cast aluminum or aluminum alloy, which can reduce the overall weight of the motor and greatly improve the speed of heat dissipation.
In wet, low temperature, high temperature and a lot of mud, dust environment, sealing and sealing materials are particularly important. Need to consider the impact of seals on the product; To prevent oil leakage to environmental pollution of products, at the same time, the leakage of grease will cause bearing oil shortage, affect the service life of bearings.
Bearing temperature is one of the main reasons 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, the internal clearance of the bearing should be checked to avoid unnecessary bearing damage.
High temperature resistant (≥180℃) engineering plastic cage is used for high speed bearings of new energy vehicle drive motor, and SPCC cage is used for medium and low speed bearings. The cage has good high speed performance and low noise performance.
The precision grade of driving motor bearings of new energy vehicles can reach P6 level, and the internal parameters can reach P5, with extremely high rotation stability and low noise performance (noise level can reach Z3 group).
2023-01-06