Study On Pitch Bearing Friction Torque In Mw Level Wind Turbine

With the increasing depletion of fossil energy, developing Clean Energy hasbecome the focus of national, wind power as a clean energy more and more getnational attention, and wind turbines can convert wind energy into electricity for useby people, the wind power industry prospects will be very bright. Wind turbines workenvironment is very harsh, requiring extremely high reliability, pitch bearing is one ofthe core components of the wind turbine, pitch bearing is directly impact on thereliability of wind turbines, so the study of the pitch bearing to improve the level ofChina’s wind power bearing manufacturer has a very important significance.This paper focuses on pitch bearing friction torque do the following researchwork. First, the force conditions of pitch bearing were analyzed. Secondly, the pitchbearing inner balance numerical model at combined external force was established,pitch bearing load distributions were calculated by finite element software, then thestructural parameters of the pitch bearing groove, bolt preload and simulated operatingconditions influence on the load distribution were analyzed. Once again, the pitchbearing friction torque was calculated, the external loads and the structural parametersof the pitch bearing groove influence on friction torque were analyzed. Finally pitchbearing friction torque were tested, friction torque was tested with load and with outload, and do a comparison with theoretical calculations.The results show that: Pitch bearing external loads is cyclical and random,making its axial force, radial force and overturning moment on the pitch bearing alsoshowing periodic and random, and overturning moment is largest. Appropriateincreases initial contact angle and decreases pitch bearing groove radius of curvaturecoefficient are conducive to improve the carrying capacity of the pitch bearing; impactof clearance on load distribution is more complex, the maximum load of bearing pitchbetween the ball and the groove with increase clearance first decreases and thenincreases, so take the appropriate negative clearance will help improve the carrying capacity of the pitch bearing; effect of bolt preload is similar to clearance impact onload distribution, appropriate bolt preload can increase the carrying capacity of thepitch bearing; under simulated operating conditions, bearing pitch torsionaldeformation occurs, load distribution showed some irregularities. Increase the initialcontact angle, decreases pitch bearing groove radius of curvature coefficient andincreases clearance can reduce the pitch bearing friction torque between the ball andthe groove, variation of the friction torque cause by differential slip and spin isconsistent of friction torque between the ball and the groove, the variation of frictioncause by pitch bearing groove radius of curvature coefficient is opposite. Friction testsshow that, if pitch bearings is uninstalled sealing and not filling of lubricants, thefriction of pitch bearings installed double row ball is about1.5times installed singlerow of balls; friction caused by seals and grease is the important source of the pitchbearing frictional torque, the friction torque and the friction torque between the balland the groove and caused by cage is relatively small; friction torque theoreticalcalculations and experimental results are similar, the theoretical model can meet theengineering application.