The traditional methods of dynamic modeling for the simulation of hydro-mechanical continuously variable transmission (HMCVT) are cumbersome and complex. The physical simulation models of engine, hydraulic speed regulating mechanism, mechanical speed regulating mechanism and the load were established based on Simscape, and the dynamic characteristics of the components were analyzed in the paper. The simulation results show that with the change of displacement ratio e, the output speed of the system is continuous and stepless, and the output torque of the system is constant when the torque of load is constant. From the analysis results, it is concluded that the physical models are feasible. The research provides a theoretical foundation and a verification platform for further development and improvement of HMCVT shifting strategy.
The quasi-static load sharing characteristics of a planetary gear set with planet journal bearings are numerically investigated. The application of journal bearings instead of rolling bearings in planetary gear sets is an alternative to increase the rotation speed. Therefore, an effective analysis method is needed to estimate the dynamic performance of a planetary gear set with planet journal bearings. Here, an available load sharing factor computation method is developed considering the effect of the variable journal bearing stiffness. Results of an experiment are used to validate the effectiveness of the computation method. Furthermore, the load sharing characteristics of a planetary gear set with planet journal bearings are influenced by bearing parameters and operating conditions significantly due to the changing bearing stiffness of journal bearings. The effects on the load sharing factor and the bearing stiffness are studied in detail simultaneously based on the proposed analysis method. The load sharing factor of a planetary gear set with planet journal bearings has a similar variation with the bearing support stiffness under the same load. These researches provide a theoretical basis for the application of journal bearings in planetary gear sets.
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