Wind turbines are installed in areas with windy sand or relatively high humidity in the wild. The working conditions of wind turbine bearings are very harsh, and the temperature, humidity, and load that need to be subjected to a wide range of changes. In particular, the yaw and pitch bearings need to withstand large axial forces and overturning moments, and the gearbox bearings need to withstand huge shock loads during starting and braking. At the same time, the wind turbine gearbox bearings are required to have low friction when starting at low speeds. Features of torque and high operating flexibility. There are as many as 32 sets of bearings for a wind turbine. Therefore, the selection of bearings is very important to ensure the safe and stable operation of wind turbines. So, which bearings are used in wind turbines?
Wind turbine bearings are generally divided into the following types: yaw bearings, pitch bearings, main shaft bearings, gearbox bearings and generator bearings. According to different bearing types, technical requirements are also different.
1, yaw, pitch bearing
This type of bearing is generally designed as an assembly. Single-row four-point contact ball slewing bearings or double-row four-point contact ball slewing bearings should meet the following technical requirements:
According to the force characteristics of the wind turbine bearing, the yaw bearing adopts a small clearance, and the pitch bearing adopts a four-point contact ball bearing with zero clearance or “negative clearance” design. The channel needs to be specially designed and processed to withstand large The axial load and moment load. The yaw gear in the assembly should choose the appropriate material, modulus, tooth profile and hardness to ensure the life matching with the driving gear. At the same time, targeted heat treatment measures must be taken to improve the strength of the tooth surface, so that the bearing has good wear resistance and impact resistance.
Because the fan is exposed to the field, there are strict requirements on the sealing performance of the bearing, and the sealing form of the bearing must be optimized to ensure that the life of the bearing is the same as that of the fan. Fans are installed at an altitude of more than 50m or even hundreds of meters. The assembly and disassembly costs are expensive. Therefore, they must have very high reliability. Generally, the life span of 20 years is required. In addition, the bearing structure is complicated, so the design and manufacturing requirements are extremely high.
2, spindle bearing
Spindle bearings are generally spherical roller bearings, and some have double-row tapered roller bearings with large taper angles. Most of the impeller spindles are supported by two spherical roller bearings. Because the load of the main shaft of the impeller is very large, and the shaft is very long and easy to deform, the bearing must have good centering performance.
3, gearbox bearing
There are many types of gearbox bearings, including deep groove ball bearings, cylindrical roller bearings, full complement cylindrical roller bearings, double row tapered roller bearings, spherical roller bearings, thrust spherical roller bearings and four Point contact ball bearings.
The bearings in the gearbox are mainly lubricated by the gear oil in the gearbox. There are more metal particles in the lubricating oil, which will obviously affect the life of the bearing. Therefore, a special heat treatment process is required to make the surface of the raceway have compressive stress and reduce the raceway. Sensitivity to particle impurities improves bearing life. At the same time, it is also necessary to optimize the bearing structure according to the working conditions of the bearing, improve the processing technology of the bearing, and further improve the performance index of the bearing.
4, generator bearing
The generator bearing adopts cylindrical roller bearing and deep groove ball bearing. It is necessary to reduce the noise of bearing vibration through the structural design of these two kinds of bearings, the improvement of processing methods, the cleanliness control of the production process and the optimization of related components, so that the bearing has a good low-noise performance.
The above is the answer to which bearings are used in wind turbines. The bearings used from the main shaft to the generator are collectively referred to as transmission system bearings. Most of these bearings are standard bearings in terms of structure. The difference is that in order to ensure high reliability, In addition to some special requirements in terms of materials and heat treatment, other key technologies need to be adopted.