Research On The Nature Frequency Of Spur Planetary Gear Train With Elastic Ring And Sun

With the increasing of speed and load, the vibration and noise problem ofplanetary gear train is becoming more and more important. At high speed or withheavy load, the sun gear and ring gear have large deformations due to their elasticityand the need for load sharing, therefore considerable errors existed using thetraditional dynamic model of planetary gear train. In order to solve this problem, thispaper, taking spur2K-H planetary gear train for example, has done some work in thefollowing area:First of all, this paper introduces the common method of analyzing vibrationmodal of the planetary gear train and the development situation at home and abroad.The advantages and disadvantages the traditional lumped parameter method and thefinite element method are stated respectively. The methods adopted in this paper arechosen.Secondly, the rigid finite element method is introduced by dividing the sun gearand ring gear into multitude segments and each section is a rigid body connected witha spring; planetary gears, planet carrier are rigid bodies, supported and connected bysprings. The dynamic model is established using lumped parameter method.Displacements, stresses and dynamics equations of the components are studied.Then, a simplified way is used to simplify nonlinear equations into linearequations. After selecting proper parameters, MATLAB is used to solve the systemnatural frequency. The influences of the numbers of ring segments and sun segmentson the natural frequency of the2K-H spur planetary gear train are researched, andthereby the proper values of segments numbers are confirmed.Finally，the virtual spring stiffness of ring and sun are researched respectively inthe following cases: only ring gear is fixed, only the sun gear is fixed and none ofgears are fixed(differential transmission). Some useful conclusions are obtained.This research will be of the guiding significance and the valuable reference forthe vibration reduction of planet gear train with a larger deformation of ring gear and the sun wheel in high speed and under overloaded situation.