Environmental Engineering Reference
In-Depth Information
Solution:
An Excel programme is written to solve for the gear ratio steps for direct
comparison with the stated transmission steps published for the 2010 Camaro SS.
The Excel Workbook results are shown here.
Hydramatic 6L80
Aisen AY6 MT
z
x
z
x
x
6L80
x
AY6
1
4.044
4.03
1
4.075
4.08
2
2.823
2.36
2
2.905
2.58
3
1.970
1.53
3
2.071
1.63
4
1.375
1.15
4
1.476
1.19
5
0.960
0.85
5
1.052
1
6
0.670
0.67
6
0.750
0.75
rev*
3.06
3.06
rev
3.67
3.67
FD
3.27
3.27
FD
3.27
3.27
*rev = reverse gear.
For the 6L80 we have
z
0
= 0.67,
r
= 1.234 and
a
= 1.71
For the AY6 we have
z
0
= 0.75,
r
= 1.235 and
a
=1.61
Note that these sets of parameters fit the transmission gear step end points but
that considerable discrepancy exists for the third and fourth gear steps. Other fac-
tors such as driveability during shift, driveline oscillation etc. contribute to the
difference noted.
4.1.3 Automatic transmission architectures
Prior to power split architectures, the most popular choice of transmission has been
the automatic. The step ratio automatic transmission with torque converter remains
the preferred transmission choice for crankshaft mounted and belt driven starter-
alternator systems. During 2002 and 2003, the major transmission manufacturers in
the world announced new products offering higher efficiency, plus quieter and
smoother shifting performance. In addition, these new automatic transmissions
have larger gear shift ratio coverage and some have entirely new architectures. The
following subsections will explain the uniqueness of these products and why they
are so important for hybrid propulsion. To illustrate the various stepped automatic
transmission architectures, this work will consider the three transmission types
given in Table 4.4 [1-3].
The Simpson 3-speed stepped automatic is used as the base underdrive trans-
mission in both the front wheel drive (FWD) and rear wheel drive (RWD) appli-
cations noted. To realize a 5-speed transmission the base Simpson 3-speed is
augmented with a double pinion (planet gears) at the main input shaft. Both of these
transmissions are capable of realizing a 1:1 ratio and have a gear shift ratio cov-
erage of 4.865:1. The 1:1 ratio is important for gears that have high frequency of
usage and where highest efficiency is necessary. In the 55-50SN the 1:1 ratio is
realized without bypassing the epicyclic gear set.
