How to improve the reliability of the wind turbine gearbox by analyzing the application of the bearing, to reduce the downtime and improve the reliability of the wind turbine gearbox.
I. Analysis of lubrication of wind turbine gearbox bearings
The input shaft speed of the wind turbine gearbox is generally 10-20 rpm. Due to the relatively low speed, it is often difficult to form the oil film of the input shaft bearing, which is the carrier support bearing. The function of the oil film is to separate the two metal contact faces while the bearing is running, to avoid direct contact between the metal and the metal. We can introduce a parameter λ to characterize the lubrication effect of the bearing (λ is defined as the ratio of the thickness of the oil film to the sum of the roughness of the two contact surfaces). If λ is greater than 1, the thickness of the oil film is sufficient to separate the two metal surfaces, and the lubricating effect is good; and if λ is less than 1, the thickness of the oil film is insufficient to completely separate the two metal surfaces, and the lubricating effect is not satisfactory. In the case of poor lubrication, the bearing may be damaged as shown in Figure 1.
Since wind turbine gearboxes generally use ISOVG320 viscosity circulating lubricants, if λ is found to be less than 1, we can generally improve the lubrication by reducing the roughness of the bearing raceways and rollers. In addition, in the design of the gearbox, the carrier support bearing should try to avoid the size of the bearing at one end is too small. In the actual application analysis, we found that even if the life meets the condition, this design will lead to the very low linear speed of the small bearing, the oil film. More impossible to form.
Second, wind power gearbox bearing bearing area analysis
At present, in the design of wind turbine gearbox, the carrier support bearing generally adopts two single-row tapered bearings or two full-roller cylindrical bearings. We can increase the load-bearing area by properly pre-tightening the tapered roller bearing or reducing the clearance of the cylindrical roller bearing.
In the roller of the running bearing, only a part of the roller is generally subjected to the load at the same time, and the area where the roller is located is called the bearing zone of the bearing. The load bearing bearing capacity and the size of the running clearance will have an impact on the load bearing area. If the load zone range is too small, the roller is prone to slippage during actual operation. For wind turbine gearboxes, if the design of the main shaft uses a two-bearing support solution, then theoretically only torque is transmitted to the gearbox. In this case, after a simple force analysis, it is not difficult to find that the load on the planet carrier support bearing is relatively small, so the bearing area of the bearing is often small, and the roller is prone to slip.