Abstract
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.
Highlights
A gearbox is a mechanical system with multiple degrees of freedom that is generally equipped with a gear train, bearings, transmission shaft, clutch, and brake
As its most significant advantage, a planetary gear can split power when transmitting power, while its input and output shafts lie on the same horizontal line. erefore, planetary gear transmission systems have been widely used in different types of speed reducer, speed increaser, and speed changer systems
Owing to the enhancement of transmission-shifting continuity and smoothness requirements, as well as the utilization of composite-planetary gear train and its integrated parts, its structure has become more compact and complex, and the analysis of its dynamic characteristics has become more difficult. e availability of a reliable power train model provides a basis for different simulation studies of power trains and facilitates the development of various power train estimation and control strategies. erefore, an efficient and accurate dynamic analysis method is required to address the problem triggered by the complex dynamic analysis process of transmission
Summary
A gearbox is a mechanical system with multiple degrees of freedom that is generally equipped with a gear train, bearings, transmission shaft, clutch, and brake. A conventional control-oriented power train model comprises dominant transmission dynamics that are characterized by gear inertias, speed ratios, and clutch friction. Ranogajec and Deur [4] presented an automated model-order reduction method in which the corresponding bond graph model was constructed based on a general example of a ten-speed advanced transmission system, which comprised four planetary gears and six clutches. The dynamic modeling of a dual-planetary gear train was included in a study conducted by Zhongshuang and Weike [6], which adopted augmentation to effectively eliminate the differential causality in the vector bond graph model of this system type. The fundamental structure and working principle of the dual-planetary gearbox are analyzed, and the bond graph method is adopted to establish the corresponding full-gear set model. The fundamental structure and working principle of the dual-planetary gearbox are analyzed, and the bond graph method is adopted to establish the corresponding full-gear set model. e state equations of the transmission system are derived, and the time-domain curves of key variables, such as speed and torque, are obtained under different load conditions via numerical solutions. e impact of different working states of the motor and engagement modes of the clutch on the system response are discussed. e influence of the main factors, such as system damping, comprehensive stiffness, and moment of inertia, on the system dynamic response are analyzed
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