Theory And Experimental Research Of Single-loop Coupled Epicyclic Gear Transmission

Single-loop coupled epicyclic gear transmission(S-EGT)is widely used into the vehicle,aviation and wind power generation because of its excellent performance that are compact structure,high power density,power split capability,and so on.The power characteristics of S-EGT are very complex.In power transmission,poor power flow characteristics can cause low transmission efficiency and even mechanism failure.In particular,the research on differential single-loop coupled epicyclic gear transmission(DS-EGT)at home and abroad is still in its infancy and lacks a complete theoretical system.Especially in the application of multiple power sources,there is a lack of a measure of the quasi-dynamic response of the gear train when the operating conditions change.Based on the existing research,this paper further perfected the theoretical system of the differential epicyclic gear train(D-EGT),proposed new parameters that affect the critical point of the S-EGT power flow patterns,summarized the design criteria of the S-EGT.Finally,the research was proved by the test system developed by the research team.The study includes:Aiming at the complex and ever-changing application environment,a new concept of dynamic tracking performance of differential epicyclic gear transmission(D-EGT)is presented for the first time,and the sensitivity and contribution of D-EGT are analyzed.Dynamic tracking performance reflects adjustment speed and effect of D-EGT’s speed,torque and power.The influence of system parameters on dynamic tracking performance is obtained by analyzing the expression of sensitivity and contribution of speed,torque and power.The speed sensitivity is verified through experiments.The results show that the speed sensitivities and the torque contributions of D-EGT’s three basic components are only associated with the characteristic parameter.The speed contribution and the power contribution are determined by the characteristic parameter and the speed matching situations of D-EGT.Aiming at the single-degree-freedom single-loop coupled epicyclic gear transmission(SS-EGT)coupled by a continuously variable transmission(CVT),the influences of the CVT’s slip ratio on the system power distribution coefficient,the system slip ratio,the power ratio of each branch of the system,and the power flow pattern are analyzed.SS-EGT’s dynamic tracking performance is studied based on the theory of SS-EGT.The system parameters chosen principle of SS-EGT is proposed based on the combination of the influences of the characteristic parameter of D-EGT,the ratio of the coupling mechanism and the slip ratio of the coupling mechanism on the system transmission efficiency,system dynamic tracking performance,power distribution coefficient and power flow pattern.The system parameters chosen principle of SS-EGT is a supplement to the existing design criteria.Considering the absence of the theory and design criterion of differential single-loop coupled epicyclic gear transmission(DS-EGT),a comprehensive analysis of DS-EGT is carried out.The analysis of DS-EGT’s speed,torque and power characteristics shows that the external characteristics of DS-EGT are similar to the external characteristics of D-EGT,which is in line with the similarity principle of epicyclic gear transmission.In addition,DS-EGT’s power analysis shows there are 19 different power flow patterns exist in the system,and the efficiency calculation formulas are given according to the node power method.These power flow patterns include 7 patterns at parameters’ critical points,6 power split and confluence patterns and 6 patterns with power circulate.The later 6 patterns including 3 patterns with clockwise circulate and 3 patterns with counter clockwise circulate.The composite lever mechanical models of DS-EGT are proposed.The essential attribute of DS-EGT’s circulating power flow is explained with the comprehensive analysis of mechanical models and power flow.The structural conditions and kinematic conditions for the existence of coupled torque are proposed.The parameters selection principle of DS-EGT is proposed on the combination of the above research and DS-EGT’s dynamic tracking performance analysis.An computer-controlled open structure SS-EGT test platform with variable coupling mechanism was developed,and a test scheme for torque and power flow research was designed.The different power flow forms of the SS-EGT and the self-locking regions in the system are studied through experiments.The test also studies the system transmission ratio,the proportional relationship between the torque of the basic components of D-EGT,and the dynamic following performance theory of SS-EGT.The experimental conclusions further verified the correctness of the theoretical research.