Power Flow And Efficiency Research Of Two-stage 2K-H Closed Planetary Drive System

At present,people are increasingly demanding the use of existing equipment,such as comfort,working performance,etc.;at the same time,they have put forward higher requirements for service life.As an important part of equipment,the transmission system directly affects the reliability of the entire mechanical system.As an important transmission form,gear transmission also plays an important role in the fields of lifting machinery,engineering machinery,mining machinery,construction machinery and so on.In order to meet higher usage requirements,it is developing in the direction of high precision and high reliability.The research on the transmission efficiency of the gear system has always been a hot research topic at home and abroad.This article focuses on the research of the two-stage closed planetary transmission system.Due to the complexity and particularity of its transmission form,it has some special properties that ordinary planetary transmission does not have.For example,some of its structures have the characteristics of load shunting,and the input power is transmitted by two branches at the same time,which greatly mentions the carrying capacity of the structure;some of the structures have the characteristics of feedback motion,which can achieve error correction.Power flow analysis,as an important part of closed planetary transmission system research,is a complex and difficult problem.The main reason is the uncertainty and possible generation of power flow direction caused by the value or structure of planetary row.The power recirculation will eventually reduce the life and efficiency of the wheel train.This paper mainly studies the structure of closed planetary transmission from the aspects of power flow characteristics and efficiency.For the study of power flow characteristics,the main object is to analyze the two-stage closed planetary transmission mechanism,the formula for calculating the transmission ratio and judging the power flow direction and power split ratio under the condition of the conventional planetary row characteristic parameters(P?[3,8])is derived,then combined with the derived transmission ratio range,a graphical analysis model was proposed to study the possible structural forms and their power flow characteristics.Studies have shown that the existence of circulating power is determined by the structure itself and has nothing to do with the characteristic parameter P;Six structural types with a large transmission ratio range are proposed.Combined with the analysis model,the relationship between transmission ratio and efficiency is discussed,and it is concluded that there must be a transmission power interval of circulating power under the condition of characteristic parameter P E[3,8].In terms of efficiency analysis,the kinematics relationship and efficiency analysis of components were carried out on a closed planetary transmission structure with motion feedback applied to gear processing machine tools.Use the principle of transformation mechanism to deduce the relationship between the rotation speed and torque of each component and the input rotation speed and torque,and explore its relationship with the characteristic parameters of planet row;Combine the power distribution coefficient formula to analyze the relationship between the power flow distribution ratio of its two branches and the characteristic parameters of the planetary row;use the meshing power method to derive its efficiency formula and optimize its efficiency.After that,the efficiency of the two-stage closed planetary transmission mechanism under electric vehicle operating conditions was explored.First,the specific structural form of the two-stage closed planetary transmission was determined,and then the meshing parameters and bearing parameters of its two-stage gears were determined.The efficiency analysis model has carried out efficiency analysis on the determined structure.The results show that the increase in the normal modulus,the number of sun gear teeth,the helix angle and the tooth width can have a beneficial effect on the meshing efficiency of the system when other parameters remain unchanged.The analysis results provide a meaningful reference for the structural design and parameter formulation of the two-stage closed planetary transmission mechanism under electric vehicle operating conditions.