Date of Award

8-2018

Degree Name

Master of Science in Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Dr. Richard T. Meyer

Second Advisor

Dr. Koorosh Naghshineh

Third Advisor

Dr. Jennifer Hudson

Keywords

Automatic transmission, powertrain, modeling, torque converter clutch, judder

Access Setting

Masters Thesis-Open Access

Abstract

This work presents automatic transmission-based powertrain modeling. The powertrain consists of an engine, torque converter with lock up clutch, transmission gearbox, propeller shaft, and vehicle body. Simplified powertrain component models are developed for vehicle powertrain dynamic response analysis and future control work. The powertrain components are modeled with algebraic and first order non-linear differential equations. A MATLAB-based powertrain simulation system is developed to investigate the transient characteristics during lock up of torque converter. Simulation results are used in the determination of effects of judder on torque and angular velocity. Clutch judder is a self-excited vibration that occurs during the clutch engagement process. It causes vibration in the drivetrain and poor driver feel. Effects on judder of throttle ramp time, final throttle opening, and clutch clamping force are investigated. A Honda CR-V is the basis for the powertrain analyzed. Results from simulation show that a negative friction gradient of clutch material causes self-excitation during engagement process and these torsional vibration causes fluctuation in torque in drivetrain. Fluctuation in torque results in bad shift quality. Final throttle opening more than 80% and clutch clamping force 1.25 times of original clutch clamping force caused judder and it affected angular speed and torque at turbine. In order to choose appropriate clutch clamping force with final throttle opening, control need to be developed. Also, coordination of engine torque control and clutch torque control is a viable strategy to improve shift quality.

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