Dynamic modeling and simulation of a powertrain system with a six-speed automatic transmission 2019-36-0100
The constant growth of the automotive market demands for comfort to the user and energy efficiency have caused the intensification of the industry researches and development of the automatic transmissions (AT). However, vehicles equipped with these gearboxes entails in higher fuel consumption levels than the one required by vehicles equipped with manual transmission. In the automotive industry due to the advantages offered using computer simulations, such as fast evaluation an optimization, many researchers are using virtual models for optimization of dynamic behavior of systems and fuel consumption. Aiming to study the dynamic behavior of an AT and the influence of its components on that behavior, this paper presents an AT dynamic model developed in MATLAB® / Simulink®. The AT model has three main subsystems: a torque converter model, which includes the dynamic of both the forward flow mode and the reverse flow mode; a Lepelletier gearbox model, composed by a set of three planetary gearsets in parallel, resulting in a six forward speeds gearbox; and a gear-shift schedule, which has the vehicle speed and accelerator pedal position as inputs of the model and the gear that should be selected in that condition as output of the model. The torque converter subsystem considers the transient and steady-state dynamic and their mainly operation dynamic characteristic: the conversion range, in which occurs a torque amplification and the stator is held; the coupling range, in which the stator freely rotates; and the transition periods from the forward to the reverse flow mode and vice-versa. The axial volume flow of the fluid, the speed and the torque of the three wheels (impeller, stator and turbine) were verified for the dynamic analysis of the system. In addition, the AT model was integrated into a MATLAB® / Simulink® vehicular dynamics and fuel consumption model in order to be analyzed under the ABNT 7024 standard speed profile.