U
NIVERSITÀ DI
P
ISA
S
CUOLA DI
I
NGEGNERIA
Master Thesis
Vehicle engineering
Systematic analysis of
torque-vectoring systems for
automotive applications
Department of Civil
and Industrial Engineering
A
UTHORAndrea Congestrì
S
UPERVISORSFrancesco Frendo
Francesco Bucchi
Aldo Sorniotti
A
CADEMICY
EAR2016/2017
I
Abstract
Nowadays, vehicle dynamics enhancement plays a key role for most of the
automotive companies. Technical developments of the last twenty years made
torque-vectoring an effective way to improve the stability and the performances
of a vehicle. Since first studies on wheel torque distribution optimisation have
been made, many different systems have been analysed and produced. Through
a standard analysis procedure, this thesis clarifies the definition of a
Torque-Vectoring System (TVS) and shows the mechanical and performance differences
between the major torque-vectoring systems, discussing the different
characteristics of the most used actuation typologies. Eventually, a categorization
and a final comparison in terms of yaw moment capability and efficiency are
carried out.
Keywords: Epicyclic Gear, Differential, Yaw Moment Control, Torque-vectoring.
Copyright information: All the non-referenced figures were created by the
author.
II
Index
1.
Introduction ... 1
1.1 Torque-vectoring ... 1 1.2 Torque-vectoring systems ... 3 1.3 Control algorithms ... 52.
System analysis ... 6
2.1 Basic models ... 6 2.1.1 Single shaft ... 7 2.1.2 Motor ... 72.1.3 Clutch and brake ... 8
2.1.4 Ordinary gear train ... 9
2.1.5 Planetary gear set ... 10
2.1.6 Composed planetary gear set ... 13
2.1.7 Chassis ... 14 2.1.8 Block diagrams ... 14 2.2 TVS analysis ... 17 2.2.1 Example one ... 17 2.2.2 Example two ... 18 2.2.3 Example three ... 22
3.
Categorization ... 29
4.
Comparison ... 39
4.1 Normalization process ... 404.2 Torque difference as a function of the torque demand ... 41
4.2.1 Category I – TMA ... 42
4.2.2 Category II – WD ... 43
4.2.3 Category III – WOD ... 48
4.2.4 Torque comparison between the three categories ... 50
4.3 Actuation torque for a given value of the torque difference ... 51
4.4 Power loss comparison ... 54
