Research On Kinematics And Dynamics Of Two-stage Power Split Planetary Transmission

Planetary gear transmission has been widely used in various types of fields such as aerospace machinery,lifting machinery,wind power machinery,automotive transmission,and national defense weapons,on account of thier small size,light weight,extensive transmission ratio and strong bearing capacity.Compared with the commonly used planetary transmissions,the power-split planetary transmission mechanism has a larger transmission ratio,and at the same time,because of its power splitting characteristics,it has stronger structural load carrying capacity and impact resistance,and the mechanism transmission is more stable.Therefore,it is necessary to study the two-stage power splitting planetary transmission mechanism.This paper carried out some related research and experiments on the two-stage power splitting planetary gear transmission mechanism from the aspects of kinematics and dynamics,including:By analyzing the structure of the two-stage power split planetary transmission mechanism,the mechanism was converted into a differential gear train with two degrees of freedom and a quasi-planetary gear train with one-degree-of-freedom.After that,analyzed the design process,and designed the two-stage power split planetary gear mechanism according to the given design requirements,tooth calculation,the allowed transmission ratio error,modulus calculation,meshing parameter calculation,displacement judgment and corresponding solution,geometry calculation,assembly condition checking,transmission efficiency calculation,and strength check conditions.And use computer language to transfer the design process to computer software,the software can simplify the design and calculation,improve the design speed and calculation accuracy.A kinematics analysis was performed for the two-stage power splitter planetary gear train,the transmission ratio,rotational speeds of various components of the system,calculation model of the transmission efficiency of the system,and the calculation formula of the two-stage power split ratio coefficient were deduced.At the same time,the effect of planetary row characteristic parameters on transmission ratio,rotational speed of each component,and the power split ratio of the two stages of the system were analyzed.The results show that the absolute value of the system transmission ratio is positively correlated with the planetary row characteristic parameters.The absolute value of the rotational speed of each member of the first stage and that the sun wheel in second stage is only related to the input rotational speed and the characteristics of the first stage planetary gear,they are proportional to the input rotational speed,and inversely proportional to the first stage planetary gear characteristic parameter.The absolute value of the rotational speed of the second-stage movable components are proportional to the input rotational speed and inversely proportional to the characteristics of the two planetary row characteristic parameters.The translation-torsion coupling model of the two-stage power splitting planetary transmission mechanism that studied in this paper was established.The nonlinear factors such as time-varying meshing stiffness and ulnar clearance were included in the nonlinear dynamics equations,and use the equations solve the natural frequency.And analyzed the change of system frequnency,when the number of first-stage planetary gears was fixed at three,the number of second-stage planetary gears takes different values.The two-stage power splitting planetary transmission mechanism test bench was built to perform dynamic experiments and kinematics experiments respectively.The solid-state characteristics experiment was chosen as the kinetic experiments.The hammer was tapped several times on the gear box.The acceleration sensors on radial,axial,and circumferential on the gearbox housing,collect the response of the gearbox system after being struck by a force hammer.The transfer function was analyzed by the vibration analysis system to obtain the sixth-order natural frequency.The obtained natural frequency values were compared with the theoretical natural frequency values obtained by the previous theoretical analysis.The correctness of the nonlinear dynamic model established in this paper was verified within the error range.The kinematics experiment selected the transmission efficiency test of the planetary transmission system.Under the experimental conditions that the constant input speed with changed system load and the constant system load with changed input rotation speed,the transmission efficiency wrer obtained through the real-time measurement and control platform and software.The results show that the system transmission efficiency had rare relationship with the input speed.However,under the condition of fixed input speed,the system transmission efficiency increased when the load on the system was increased.