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Surprising Potentials in Planetary Transmissions
Frank Schoenstein
-2 %
-5 %
-3 %
-6 %
4-Speed 5-Speed 6-Speed
Gen II
8-Speed 6-Speed
Gen I
100 F
ue
l c
on
su
mp
tio
n in
%
Reduction of Fuel Consumption for AT
Schaeffler Symposium 2014 1 Frank Schoenstein
2
Trends in Automatic Transmission Development
Schaeffler Symposium 2014 Frank Schoenstein
1,000
2,000
3,000
4,000
5,000
6,000
7,000
4,000 6,000 8,000 10,000
Ma
x. a
cce
lera
tio
n v
alu
e in
g
Planet gear carrier speed in rpm
4 AT 5 AT 6 AT
7 AT 8 AT 9 AT
4AT
5AT
7AT
8AT
9AT
6AT
Ma
x. a
cc
ele
rati
on
va
lue
in
g
Planet carrier speed in RPM
7,000
6,000
5,000
4,000
3,000
2,000
1,000
4,000 6,000 8,000 10,000
Schaeffler Symposium 2014 Frank Schoenstein 3
Components of a Planetary Gearset
Sun gear Planetary pin with
needle roller bearing Ring gear
Planetary gear
Washers
Planetary carrier Oil distribution
plastic part
Optimization of the Cage Geometry
Schaeffler Symposium 2014 Frank Schoenstein 4
Cage bar
Rolling element /
Needle
Old cage design
Cage rim
Optimization of the Cage Geometry
Schaeffler Symposium 2014 Frank Schoenstein 5
Cage rim
New cage design
Cage bar
Rolling element /
Needle
Schaeffler Symposium 2014 Frank Schoenstein
Parameter: Rolling element mass
Cage friction is the predominant element for friction behavior
Friction Behavior under Pure Centrifugal Force
6
0
25
50
75
100
Design nr.1 (needle ø 2.5mm)
Design nr.2 (needle ø 2mm)
Fri
cti
on
in
%
Cage - sliding friction
Needles - sliding friction
Needles - rolling friction
Schaeffler Symposium 2014 Frank Schoenstein 7
Treatment by Shot Peening and Adapted Coatings
+
Increased cage strength and efficiency
Increased wear resistance
Up to 23% more efficiency
0
25
50
75
100
Durotect® Z Durotect® M Durotect® NP
Fri
cti
on
in
%
Schaeffler Symposium 2014 Frank Schoenstein 8
Optimization in Comparison
to State of the Art
Friction
Reduction
Bearing cage
design
Bearing cage
coating
Planetary gear
Durotect® NP
-11 %
-23 %
-50 %
Previous Successes in Development
Schaeffler Symposium 2014 Frank Schoenstein 9
Planetary Gears
Schaeffler Symposium 2014 Frank Schoenstein 10
db ,
Normal contact forces Fgm, Fcircum, Fcentr
Friction due to radial forces Ffr,rad
Fcentr
Fcircum
Fgm
Fgm
Pout
Pin
Planetary Gears
Angular acceleration forces Facc
Inner gear mesh friction Ffr,gm
Schaeffler Symposium 2014 Frank Schoenstein 11
Fgm
Fgm
Fcentr
Fcircum
Angular acceleration forces Facc
Inner gear mesh friction Ffr,gm
Planetary Gears
Normal contact forces Fgm, Fcircum, Fcentr
Friction due to radial forces Ffr,rad
12
Standard
plain bearing /
washer
Standard
thrust needle
roller bearing
Dimension
Inner diameter
Outer diameter
Width
Needle roller size
Washer thickness
Needle roller speed
17 mm
30 mm
1.0 mm
-
1.0 mm
-
18.2 mm
31.7 mm
2.81 mm
2 x 3.6 mm
0.81 mm
100,000 rpm
Previous Successes in Development
New
thrust needle
roller bearing
17 mm
30 mm
1,2 mm
1.0 x 2.25 mm
0.2 mm
300,000 rpm
Planetary gear set 2 Planetary gear set 3 Planetary gear set 4 Planetary gear set 1
Schaeffler Symposium 2014 Frank Schoenstein 13
0
50
100
150
200
250
300
350
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
Friction losses thrust washer Friction losses thrust needle bearing
Spec.
fuel con-
sumption
in engine
data map
Result
data
CO2
emission
Power
losses
AXK
Power
losses
AS µR from
thermal
balance
Axial
load
Bearing
load and
rpm
Input shaft
rpm and
Torque
BEARINX® transmission calculation due to CAFE
Input data
Gear
Frictio
n lo
sse
s in
Wa
tts
Simulation
Schaeffler Symposium 2014 Frank Schoenstein 14
Investigation
CO2
Reduction Reduction Achievement Initial
Simulation
(3. gear)
Component test
470 Watts
0.23 Nm
62 °C
50 Watts
0.02 Nm
57 °C
420 Watts
0.21 Nm
5 °C
For the entire
transmission
in the CAFE
- 1 %
1% CO2 reduction
at $15 additional costs for
the substitution in whole
transmission
Schaeffler´s Vision of Planetary Gear Set Challenge
We cannot solve our problems with the same thinking we used when we created them
”
“
Albert Einstein,
Physicist
1879-1955.
