2.2 planetary gear bearings
2.2.1 Common failure modes A common planetary gear bearing consists of a pair of double row cylindrical roller bearings (as shown in Figure 4). In the case where the interference fit between the outer ring of the bearing and the inner bore of the planetary gear is insufficient or the contact area of the gear is reduced due to the deformation of the gear, the outer ring running and wear may occur.
For the design of the helical gear wheel, since the planetary gear is engaged with the inner ring gear and the sun gear at the same time, the axial force of the same magnitude and opposite direction is generated, and the overturning moment generated causes the outer two rows of rollers to bear larger. The middle two rows of rollers carry less. The uneven distribution of load between the four rows of rollers makes the actual service life have a certain difference. Under the premise of the same design life, the outer two columns will have fatigue spalling in advance.
2.2.2 Solution The Timken integrated flexible pin planetary gear assembly (shown in Figure 5) is one of the best solutions to improve the reliability of the line. The gear and bearing outer ring are integrated into one, eliminating the possibility of running the outer ring, and there are more internal spaces to design more and larger rollers to improve the carrying capacity. By pre-tightening the two rows of tapered rollers, the bearing area is optimized, reducing the stress and the probability of roller slip, so that the load is more evenly distributed in two columns. The flexible pin design allows the planetary gear assembly to produce a flexible offset during operation, ensuring a high meshing ratio of the tooth flanks, especially for the design of multiple planetary gears, resulting in a more uniform load distribution between the planet wheels, and It can reduce the precision requirements of machining and assembly.
2.3 high speed shaft bearing
2.3.1 Common failure modes Cylindrical roller bearings and four-point contact ball bearing combinations are more common in high-speed applications. In the case of high speed and low load, cylindrical roller bearings are prone to roller slip and raceway slip, and ball bearings may suffer from slip and micro-flaking.
2.3.2 Solution Timken introduced cylindrical roller bearings with anti-wear coatings and single row tapered roller locating bearings (see Figure 6). Cylindrical roller bearings with anti-wear coatings continuously prevent slippage during the entire life cycle, as well as prevent raceway damage and poor lubrication due to impurities in the lubricant. Single row tapered roller locating bearings can withstand radial and bidirectional axial loads, and their pure rolling characteristics minimize the possibility of slippage.
3. Summary
With the rapid development of the wind power equipment industry, especially the mainstream of high-power wind turbines, the reliability of wind turbines and components will be the focus of research and development. The common failure modes and solutions for gearbox bearings described in this paper are intended to help equipment manufacturers select bearing solutions that are more suitable for wind turbine gearbox applications, and strive to continuously optimize the design of the gearbox to make the gearbox and even the machine reliable. Sex has been greatly improved.
