| Multi-stage planetary transmission system has n-planet to share the load and power split, and the system has the many advantages, such as compact, high torque to weight ratio, high transmission efficiency, strong load capacity and steady transmission. These advantages make the multi-stage planetary transmission system widely used in industry fields. However, manufacturing and assembly errors, time-varying mesh stiffness and other vibration excitations would cause unequal load sharing among planet gears; and the unequal load sharing would lead to the vibration and noise which will affect the reliability and stability of the transmission system. In this paper, the author presented a torsional-transverse-axis coupling dynamic model to study the dynamic characteristics of multi-stage planetary transmission system. The main research contents are as follows:First, a dynamic model for multi-stage helical planetary transmission system is built based on lumped-parameter method. The model considers three translations and one torsional of each component, also the manufacturing and assembly error, time-varying mesh stiffness and elastic deformation are included. Gear elastic compatibility equations are proposed to describe compatibility relationship between displacements, errors and elastic deformations, also the equation of motion of system are built according to the Newton's second law.Secondly, dynamic load-sharing coefficient is proposed to evaluate the load sharing characteristics. One type of 2.0MW wind turbine gear transmission system is presented as example; the parameters in the dynamic model are calculated, such as moment of inertia, mesh stiffness and damping, torsional stiffness of carrier and so on. Substitute these parameters into the dynamic model, the equation of motion of system are solved with Runge-Kutta numerical integral method, which yields the displacements and deformations of each component, also the dynamic load-sharing coefficient is determined.Thirdly, a load-sharing experimental study of 2.0MW wind turbine gear transmission system is presented. The strain gauges are mounted in root fillet of the fixed ring gear; sampling frequency is 2000Hz, the gauges record strain distribution of tooth roots.1/n circle rotation of the carrier is a circle of strain data, select the maximum value during the period, and save it into the matrix. Load-sharing coefficients of experiment calculation are compared to the numerical calculation under different load condition, and numerical calculations agree well with the experiment calculations.Finally,3.0MW wind turbine gear transmission system is considered as the research object, the load-sharing coefficients of multi-stage helical planetary transmission system are determined. The analysis indicate the eccentric error affect the load-sharing characteristic significantly, the sensitivity of load-sharing coefficients to the errors in descending order is planet gear, sun gear, carrier and ring gear. Also find the floating would improve the load-sharing characteristic obviously, the flexible planet pin is useful to the system. |
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