Dynamic Analysis Of Coaxial Counter-rotating Epicyclic Transmission

Power system of Unmanned Underwater Vehicle (UUV) mainly consists of twoparts of the power sources and propulsion systems. The propulsion systems drived bythe single-rotor motor not only meet the requirements of coaxial counter-rotating anddual output under high speed, but also have a small noise and vibration, light weight andeasy maintenance, etc. Nowadays, the UUV drived by single-rotor permanent magnetsynchronous motor and equipped by coaxial counter-rotating reducer propulsionsystems is the best choice.The thesis subject is supported by National Natural Science Foundation. RegardingCoaxial Counter-rotating Epicyclic Transmission (CCET) with the ordinary gear trainand the differential gear train as research object, and considering a variety of internalexcitation and external excitation, the coupled dynamic model of CCET is built. Theinherent characteristics and dynamic response of the transmission system are obtainedby using numerical methods, and the vibration characteristics of the gearbox areobtained by using finite element methods. All of these provide a theoretical basis fordynamic design, noise and vibration evaluation for CCET. This dissertation’s main workis as follow:①Based on the method of gear system dynamics and Lagrange equation, acoupling dynamic model of the CCET is built by lumped-parameter method, and thedynamic differential equations are derived with consideration given to the time-varyingmesh stiffness, transmission error, support stiffness, elastic coupling and power flow ofthe gear train.②The system natural frequency and vibration vector can be obtained by solvingthe eigenvalue according to the relevant parameters of the CCET, the vibration modes ofthe system are obtained, and the relationship between the stiffness parameters withsensitivity of the inherent frequency is discussed.③Time-domain dynamic characteristics of the CCET are achieved by numericalanalysis method, the displacement response and speed response curve are obtained, andthe change law of the curves are analyzed. According to the dynamic meshing force ofthe system, the load sharing and error parameters impact on the load sharing of thesystem are discussed.④The finite element model of the coaxial counter-rotating gearbox system is established. The modal and vibration response of the gear box system is analyzed, andthe inherent characteristics and the nodes time-domain vibration response of the systemare calculated. Finally, whether the vibration of the system meets the designrequirements is evaluated according to the analysis result.