Dynamic Modeling and Simulation of Double-Planetary Gearbox Based on Bond Graph

New generations of powertrains are using gearboxes with multiple speed-shift designs to improve fuel efficiency. However, transmission controls and calibration are substantially time consuming, specifically during shift processes. To study the dynamic characteristics of a gearbox with a double-planetary gear train and analyze the influence of external excitation and internal parameters on the dynamic response of a system, dynamic modeling and simulation of the transmission system are conducted. Some physical processes are complex and difficult to express via lumped mass modeling. The dynamic model of a double-planetary gearbox is obtained by adopting the bond graph method based on the working principle analysis of the transmission, as well as the kinematic characteristics of the double-planetary gear train. Subsequently, state equations are deduced from the dynamic model of the power transmission system for simplified calculations, which can effectively facilitate the shift process simulation. The basic case of different shift plans and times is originally analyzed, followed by an analysis of the influence of damping, stiffness, and moment of inertia on transmission systems. The analysis results provide references for the structural design, control strategy optimization, and failure diagnostics of this gearbox type.

Modelling and Simulation of Frequency Response on Input shaft/carrier of a Planetary Gear Train under the Influence of Vibration

The transmission of motion from one gear to the other in a planetary gear train usually result in unwanted conditions such as vibration due to poor gear assembly, high contact forces, high rotation speeds etc. The vibrating effect of the gear can result in higher or lower frequency response which may damage the gear or offer safe working condition. Using SOLIDWORKS 2018 version for the modelling, SimulationXpress was used to conduct frequency analysis on input shaft/carrier of a planetary gear train to understand its behaviour at different mode shapes during vibration. Results obtain from the input shaft/carrier frequency analysis showed natural frequency values of 1922.4Hz, 1922.8Hz, 2101Hz, 2183.1Hz and 2185.3Hz for mode shape 1-5. Geometry of the input shaft/carrier appeared differently at each mode number, resulting in frequency responses characterised by different modal shapes. This also led to gradual increase in the natural frequency of the input shaft/carrier at increasing mode no, consequently causing deflection on the mode shapes of the input shaft/carrier model. Hence, vibration should be reduced to the lowest limit of tolerance for minimum deflections and longevity of the input shaft/carrier and planetary gear components.