Abstract
KEYWORDS
bond graph, modeling, simulation, automatic transmission, planetary gear train, variable dynamics systems
ABSTRACT
The paper presents the dynamic model of a five-speed automatic transmission. The basic approach followed by authors is „bond graph modeling => mathematical model => simulation model in Simulink”. The relative complexity degree of the transmission’s mechanicals relies from the presence of two planetary gear trains, triggering a complex mathematical model of gears and shifts. The authors have chosen to present shift processes that occur in different planetary units, thus a larger problematic was considered. Nevertheless, the bond graph method applied by authors allows the process of finding the governing equations of motion within few lines, dramatically faster than more traditional methods like Newton’s second law or Lagrange’s formalism. Moreover, the methodology is applicable to all kind of epicyclical automatic transmissions. Two drivetrain hypotheses are taken into account for simulation. The simulation model (Simulink block diagram) is also presented. Finally, a standstill acceleration simulation process is performed, in order to (qualitatively) test the dynamic model for the analyzed transmission. Due to the simulation results’ allure, the proposed bond graph and mathematical model are appreciated to be correct.