In wind power generation system, variable pitch bearing is one of the key components, and its performance is directly related to the efficiency and reliability of the whole system. However, in the actual operation process, wind power bearings often have the problem of oil leakage, which not only increases the maintenance cost, but also may cause pollution to the environment. This paper will deeply discuss the main factors leading to this problem, and put forward the corresponding solutions.
1. Improper selection of grease
The selection of greases needs to take into account the working conditions of variable pitch bearings, temperature changes and the needs of specific additives. If the selected grease consistency is not appropriate or the pressure resistance is insufficient, especially at low temperatures, the fluidity of the grease is poor, it is easy to cure and block the lubrication channel, and eventually overflow from the seal. Therefore, it is necessary to select a grease with appropriate consistency and good fluidity according to the specific working conditions to ensure that it can work effectively under various conditions.
2. The amount of grease injection and the setting of lubrication system are unreasonable
Excessive fat injection
Variable pitch bearings should be filled with an appropriate amount of grease during initial installation, usually accounting for about 60%-80% of the internal space. Overfilling (e.g. up to 80%), while ensuring initial lubrication, may lead to a build-up of grease in the long run, especially during unit downtime when the automatic grease injection system continues to operate according to the preset procedure, further exacerbating this build-up.
Limitations of automatic and manual grease injection systems
Centralized automatic grease injection systems provide even and continuous lubrication, but during static or extended downtime, it may inject too much grease and increase internal pressure. In contrast, although manual regular fat injection is flexible, if the operation is not standardized, it is also difficult to avoid the problem of excessive fat injection. When the grease injection pressure exceeds the maximum that the seal can withstand (about 2.8×10^5 Pa), it will cause serious grease leakage.
In addition, if there is air in the pressure pump or the grease pipeline of the automatic grease injection system, the gas will be brought into the grease injection process, causing the internal pressure to rise abnormally, thus destroying the seal structure, resulting in a large amount of oil leakage.
3. Design defects of waste fat discharge
At present, most wind turbines collect the used oil by arranging multiple waste fat discharge holes on the bearing circumference and connecting fat collecting bottles. This method relies on the newly injected grease to push the old grease out into the grease collection container. However, with the increase of service life, the waste fat discharge efficiency gradually decreases, increasing the risk of oil leakage. To this end, it is recommended to optimize the design of waste fat discharge paths, such as introducing more efficient sewage discharge devices or cleaning waste fat outlets regularly to maintain good discharge results.
In order to prevent oil leakage of wind power bearings, in addition to the correct selection of grease, it is necessary to set the grease injection amount reasonably and improve the lubrication system, while ensuring the effective management of waste grease. By taking these measures, the frequency of oil leakage can be significantly reduced, the service life of bearings can be extended, and the overall reliability and economic benefits of wind power generation equipment can be improved.
