As the force bearing condition of bearings for wind power generation (yaw bearings and pitch bearings) is complex and the bearings withstand larger shocks and vibration, the bearings are required to be capable of supporting both shocks and bigger loads. The life requirement for wind turbine host is 20 years, and the bearing installation costs are huge, so the life requirement for yaw and pitch bearings is also 20 years.
Wind turbines may work in extremely cold areas, and the environmental temperature may be as low as -400C and the bearing working temperature is around -200C, so the requirement is that the bearings must be capable of withstand big shock loads at low temperature.
There are special requirements for yaw and pitch bearings in terms of the clearance. Compared with yaw bearings, pitch bearings can withstand bigger shock loads. The vibration caused by wind blowing to the blade is big, so the clearance of pitch bearings is required to be zero or a slightly negative clearance value. In this case, the vibration could reduce fretting wears of bearings. The requirement for the clearance of yaw bearings is small clearance value.
Wind turbine equipment work in the field and part of the yaw bearings and pitch bearings is left bare, so they may be polluted by air and high temperature may also corrode the bearing substrate, so the part of yaw bearings and pitch bearings being left bare needs to be processed for anti-corrosion on the surface. |
