The practice has proved that the bearing is one of the weakest parts in the wind power gearbox. Because the wind power gear is impacted by variable loads and strong gusts throughout the year, it must be different from the ordinary gearbox in terms of design, manufacturing, and maintenance.
With the continuous increase of the design power of wind turbines, the volume of wind power gearboxes must be as small as possible and the weight must be as light as possible under the condition that the wind power gearbox meets the requirements of transmitting load. How to improve the wind power gearbox through the application analysis of bearings Reliability, to achieve the purpose of reducing downtime and improving the feasibility of wind power gearboxes.
In general, the speed of the coarse auxiliary input shaft of the wind power gear 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 planetary beam support bearing. The role of the oil film is when the bearing is running. Separate the two metal contact surfaces to avoid direct metal-to-metal contact.
Introduce a parameter to indicate the lubrication effect of the bearing (defined as the ratio of the thickness of the oil touch to the sum of the roughness of the two contact surfaces). If the parameter is greater than 1, the thickness of the oil film is enough to separate the two metal surfaces and the lubrication effect is good; and if it is less than 1, It means that the thickness of the oil film is not enough to completely separate the two metal surfaces, and the lubrication effect is not ideal. Running with poor lubrication may damage the bearings.
The general section of wind power gearboxes uses circulating lubricating oil with ISOVG320 viscosity. If the parameter is found to be less than 1, the lubrication effect can only be improved by reducing the roughness of the bearing raceways and rollers. In addition, in the design of the gearbox, the planet carrier support bearing should try to avoid the size of one end bearing being too small. In the actual application analysis, we found that even if the service life meets the conditions, this design will cause the linear velocity of the small bearing to be very low. The oil desert is even more unable to form.
Generally, only a part of the rollers of a running bearing bear the load at the same time, and the area where this part of the roller is located is called the bearing area of the bearing. The size of the load borne by the bearing and the size of the running clearance will affect the load-bearing area. If the bearing area is too small, the roller is prone to slipping during actual operation.
For wind power gearboxes, if the main shaft is designed with dual bearing support, theoretically only torque is transmitted to the gearbox. At this time, after a simple force analysis, it is not difficult to find that the load borne by the planet carrier support bearing is relatively small, so the bearing area of the bearing is often relatively small, and the rollers are prone to slippage.
At present, the planet carrier support bearing in the design of wind power gearboxes generally adopts two single-row tapered bearings or two full-complement cylindrical roller bearings. The tapered roller bearings are properly preloaded or the clearance of the cylindrical roller bearings is reduced, in order to increase the carrying load area.
Related Product: Gearbox Bearing Of Wind Turbine Generator (WTG)
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