Study On Topological Synthesis Of Planetary-Type Electro-mechanical Transmission For HEV

As an important part of the vehicle system,transmission determines the power,fuel economy of vehicle performance,and good transmission configuration is the prerequisite for good vehicle performance.Due to compact structure and wide transmission range,planetary transmission is widely used in electro-mechanical transmission.With the freedom and the number of planetary gear trains(PGT)increasing,the traditional design method of enumerating all the configurations is difficult to meet designing preferable.In this paper,the graph model is established,topology synthesis approach is proposed to generate multi-planetary gear train mechanism,the method of varying the structure of mechanism is researched and the continuous conditions of switching modes is studied.Finally,the function topology synthesis method of designing multi-mode electro-mechanical transmission is formed.Based on the coupling characteristics of electro-mechanical transmission,the graph model with clear property member of PGT is established.Through analyzing kinematics and dynamics of transmission,the power loop of two degrees of freedom planetary transmission mechanism is researched which is used for selecting preferred configurations.By analyzing the relationship between inner fixed connection edges and the number of PGTs,topology synthesis approach based on recursive method is proposed which can generate multi-PGT with 2-DOF transmission rapidly.And the method is verified by way of example.Through evaluate the importance of inner fixed connection edges of electro-mechanical transmission,the characteristics of the inner connection edges is analyzed.Through the method of weighting to graph model proposed in Section 2,the new graph model which can present the properties of inner connection edges is established.This model provides a theoretical basis for varying the structure of PGT transmission,and the corresponding computer-aided design method is formed.On the basis of the graph theory,the influence between multi-DOF mechanism and multi-mode is analyzed and revealed.Considering the influence of ratio range,the mechanical point properties,split forms and electrical work status and other factors to the multi-mode continuous switch,the conditions of mode switching and power flow constraints is studied.Through analysis of different forms of power flow and the properties of mechanical points,the switching conditions of mode are defined which contains the ascending of mechanical points,the logical order of switching mode and the status of motors,the synthesis method in designing multi-mode is proposed.Through analyzing the dynamics of mechanism including power flow,transmission efficiency,motion parameters,etc.,the control of switching mode,the range of gear ratio,the relationships between parameters of structure with the characteristic of PGT and motors are researched,and the influence of various parameters on the system performance is analyzed.According to the compact of structure,the extent of the sleeve shaft circuitous layers,member of the operating member bound orderly,comprehensive evaluation method for configuration is established to evaluate the merits of various configurations.