Development and Industrialization of the New Rear - ECS

Development and Industrialization of the
New Rear Axle for the VW Caddy 4motion
Integration of existing drivetrain technology from passenger cars
with independent suspensions into a newly to be developed rear
beam axle with controlled AWD clutch
Dipl.-Ing. Josef Leitner, ECS
Magna Powertrain, Engineering Center Steyr, Austria
www.ecs.steyr.com
Paper presentation at the conference
„8th International CTI Symposium
Innovative Automotive Transmissions“
Dec. 1st / 2nd, 2009 in Berlin
8th International CTI Symposium - Innovative
Automotive Transmissions, Dec. 1st / 2nd, 2009
Development and Industrialization of the New Rear Axle for the
VW Caddy 4motion
Integration of existing drivetrain technology from passenger cars with
independent suspensions into a newly to be developed rear beam axle with
controlled AWD clutch
Dipl.-Ing. Josef Leitner, ECS
Director Drivetrain Engineering
Magna Powertrain, Engineering Center Steyr, Austria
Abstract
This paper describes the development and industrialization of the driven rear axle for the
new VW Caddy 4motion. For this application, highest attention has been paid on integrating
verified components and technology from the high volume passenger car production, of
course considering the differences between the beam axle here and the independent
suspensions in passenger cars. The axle as a component has been developed by
Engineering Center Steyr (ECS), Volkswagen Commercial Vehicles (VW) uses it in the
Caddy 4motion as driven rear axle. By taking advantage of the carry over parts concept
mentioned above and by a very close cooperation between the two companies, it was
possible to develop and industrialize the axle, as well as the Caddy 4motion based on the
normal Caddy, within 15 months.
1
8th International CTI Symposium - Innovative
Automotive Transmissions, Dec. 1st / 2nd, 2009
1 The VW Caddy 4motion
Volkswagen Commercial Vehicles has offered the third generation Caddy since early 2004,
and now also with permanent four-wheel drive using the most competitive superior
technology from the all-wheel drive TIGUAN, slide 3.
2 Targets
Following targets for the vehicle had been defined, slide 4:
¾ Typical VW with non-problematic handling, performance and good comfort
¾ Same payload as the front-wheel-driven Caddy
¾ Same fuel capacity as the front-wheel-driven Caddy
¾ Maximum use of carry over parts (COP)
¾ A minimum of modifications in the vehicle environment
¾ Small investment
¾ Availability for market within a short time of 15 months
Out of these, the targets for the axle are derived.
3 The rear axles and the package
3.1
Comparison of non driven and driven axle
Slide 5 shows the representation of both the non driven and the driven rear axle. Both are
beam axles using leaf springs.
Both axle concepts are represented in the rear view on slide 6. The offset of the axle tube
and therefore the space for the spring travel had to be reduced by around 96 mm on the
Caddy 4motion because the driveshaft has to be within the tubes. To compensate in some
amount for that, the tubes of the 4motion rear axle have an offset to the driveshaft of 5 mm;
this gains some space for the leaf spring. Additionally the rear of the car is lifted compared to
the non driven one.
2
8th International CTI Symposium - Innovative
Automotive Transmissions, Dec. 1st / 2nd, 2009
3.2
Package of the drivetrain
The package view as illustrated in slide 7 shows the drivetrain and propshafts. The front
propshaft is COP from the TIGUAN. To adapt for the longer wheelbase, the central propshaft
support, the length of the rear propshaft and the Haldex flange profile have been adjusted.
4 Concept of the rear axle
The rear axle is basically a driven beam axle with integrated Haldex-Gen 4 controlled clutch,
cast center housing, an open bevel gear differential, a hypoid gear set with a ratio of i =
1.588, tubes, wheel carriers and 15“ disk brakes. There are separate oil supplies/circuits for
Haldex clutch and axle drive. See slide 8.
5 Carry over parts concept
The carry over parts concept is illustrated in slide 9.
Validated series parts at Volkswagen and Magna Powertrain (MPT) are used for this new
application. The hypoid gear set with ratio 1,588, as well as the complete differential
including its bearings, and also the Haldex 4 controlled clutch are COP from the passenger
car rear axle module HAA450 (independent wheel suspension). The brake caliper and disk
are COP from Tiguan, and the wheel bearings are COP from Caddy front-axle. The complete
load carrying structure including the center housing, the tubes and the brackets had to be
developed newly.
6 New features in this axle and application
The new features in this axle and application respectively are (see slide 10):
¾ Haldex 4 applied on beam axle – dynamically moved with axle, not fixed on chassis
like in passenger car application
¾ De-centered axle tube relative to axle shaft -> minimizing of the necessary chassis
lifting
¾ Guidance ring to ease assembly and maintenance
3
8th International CTI Symposium - Innovative
Automotive Transmissions, Dec. 1st / 2nd, 2009
7 Development
7.1
Development / Timing
Slide 11 gives an overview about the timing.
There was one prototype generation and then the series was set up.
Based on the carry over parts concept described above, the intensive and trustful
cooperation from both sides, short decision processes in both companies, an extraordinarily
short development and industrialization timing could be realized. SOP of the axle was 15
months after program start at ECS.
7.2
Development / Diff assembly
Whereas the differential HAA4550, that the complete differential is taken from, has
longitudinal parting in an aluminum die cast housing, the axle for the Caddy uses a grey cast
iron housing, where the differential has to be inserted from the back. To achieve a bearing
pretension in the assembled condition, it is necessary to open the housing at the bearing
shoulders to enable the assembly without force. The housing is pressed vertically, the
differential inserted, and when the vertical pressing is released the pretension is applied,
slide 12. This process has been established based on simulations and later on verified on the
hardware.
7.3
Development / FEA, fatigue analysis
Slide 13 shows some aspects of the strength and fatigue calculation carried out. For strength
calculations NASTRAN is used; for fatigue calculations the ECS software FEMFAT is used.
On the one hand, extreme and static load cases are considered, on the other hand the
endurance for measured road load data has been analyzed. The rear cover shows an
especially flat cover design for participating highly in load transfer.
7.4
Development / NVH
Some items of the NVH investigations performed are shown in slide 14:
¾ Modal analyses in simulation
¾ Modal analyses on hardware
4
8th International CTI Symposium - Innovative
Automotive Transmissions, Dec. 1st / 2nd, 2009
¾ Vibrations analyses on test bench in loaded condition
¾ Limit sample analyses
¾ Measurements in the vehicle
Finally the correlation between rig test and vehicle has been established.
7.5
Development / Structure testing
The axle structure has been tested in an 8-cylinder set-up for endurance, slide 15. The axle
was mounted elastically with original springs and dampers. The iteration channels (left and
right) for correlation measurement to test rig have been:
¾ Wheel force transducers:
vertical force, lateral force, longitudinal force, braking moment
¾ Damper forces
¾ Various strain gauges on leaf spring
¾ Various strain gauges on the axle structure
The test program has been derived out of measurements in the vehicle in a way to achieve
the same damage within a reasonable time on the test rig, keeping the most damage
relevant sections same as in the vehicle measurement.
7.6
Development / Functional testing
Functional testing (slide 16) of the axle covered items such as:
¾ Lubrication
¾ Oil foaming
¾ Temperature behavior (in loaded and unloaded condition)
¾ Drag torque measurements
¾ Seal ring test
As soon as the functional tests show positive results, the endurance tests are started.
5
8th International CTI Symposium - Innovative
Automotive Transmissions, Dec. 1st / 2nd, 2009
7.7
Development / Dyno testing
Rotational strength and endurance testing of the axle has been performed on dyno test rigs,
slide 17. A 3-machine set-up has therefore been used. The ultimate strength test, where
torque at the input shaft is applied and increased up to rupture while recording the torque
and the angle showed that the design targets have been met or even exceeded.
For the endurance testing, a block cycle program derived from road load data has been
applied. In some of the blocks there is a controlled application of difference speed left / right,
to test differential right along in this set up, and in this test run, without having to carry out an
additional test with additional (prototype) axles.
To check the behavior at high dynamic loads, an own dynamic peak torque test has been
carried out.
8
Production and assembly of the axle
8.1
Production of the axle
The assembly concept and the assembly line are tailor-made for the requested volume of the
axle, slide 18. The structure part comes pre-assembled with tubes pressed in and all
brackets welded on and already painted. There is a semi-automated assembly that involves
optical checks by laser and Poka Yoke solutions. Relevant items are documented: there is a
recording of all tightening torques / angles drag torque and backlashes measured.
A coordinate measurement machine is included in the assembly line for hypoid gear,
differential and housing measurement for proper gear setting calculation.
The axle is finished with wheel bearings and brakes. At the end there is a functional check of
Haldex, tightness and ABS sensor signals. The axle is then shipped to the vehicle
manufacturing plant.
8.2
Assembly of the axle into vehicle
For the assembly of the axle into the vehicle, existing tooling with a minimum of modifications
is used, slide 19. There is a mixed assembly of driven and non driven rear axles into the
vehicle on the same line. The end-of-line-test of the vehicle includes of course a functional
test of the 4motion.
6
8th International CTI Symposium - Innovative
Automotive Transmissions, Dec. 1st / 2nd, 2009
9 Summary
The setpoints of the project Caddy 4motion, being fuel capacity, payload, comfort and
drivability were fulfilled with a tight budget for development and investment.
The rear beam axle with controlled 4WD is the optimum drivetrain solution for the VW Caddy
4motion; it has been realized in close cooperation between the OEM VW and Magna
Powertrain ECS as developer and supplier of the rear axle as a component.
Optimal use of synergies is made by utilizing main carry over parts, developed and verified
from VW‘s and Magna Powertrain‘s volume production of passenger car components.
Beam axle specific parts are tailor-made and developed acc. to the axle specifications for the
Caddy.
The development and industrialization until SOP has been realized in an extraordinarily short
time of only 15 months
The vehicle is very positively accepted by the market.
7
8th International CTI Symposium - Innovative
Automotive Transmissions, Dec. 1st / 2nd, 2009
References
/1/
Zips, T., Leitner, J.:
The new Caddy 4motion from Volkswagen Commercial Vehicles. Integration of existing
drivetrain technology from Volkswagen passenger cars into a rear beam axle to be
newly developed. 9. European All-Wheel Drive Congress Graz“, 16. / 17. April 2009 in
Graz.
/2/
Leitner, J.:
Antriebsstrangentwicklung - Einsatz modernster Simulations- und Testtools. Seminar
„Neue Technologien und Innovationen in der Fahrzeugtechnik“, 6.- 8. März 2006, HTL
Steyr.
/3/
Leitner, J.:
Engineering and new simulation methods applied on the 4WD driveline for an offroad
vehicle. CTI conference „Innovations pour transmissions automobiles“, 28 et 29
septembre 2004, Chateau Hôtel Mont Royal, Paris
/4/
Leitner, J.:
Neuentwickelter Allradantrieb für ein Geländefahrzeug. Konzept, Entwicklung,
Erprobung. VDI-Tagung Antriebssysteme für Off-Road-Einsätze, 18. / 19. September
2003 in Garching bei München. VDI Berichte 1793.
8
Development and Industrialization of the New
Driven Rear Axle for the VW Caddy 4motion
Integration of existing drivetrain technology from passenger cars
with independent suspensions into a newly to be developed rear
beam axle with controlled AWD clutch
Dipl.-Ing. Josef Leitner, ECS
Director Drivetrain Engineering
Magna Powertrain, Engineering Center Steyr, Austria
www.ecs.steyr.com
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
1
Contents
1. The vehicle
2. Targets for the VW Caddy 4motion
3. The rear axles and the package
4. Concept of the rear axle
5. Carry over parts concept
6. New features in this axle and application
7. Development process
8. Production
9. Summary
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
2
1 The VW Caddy 4motion
• Caddy proven to be light
commercial vehicle with high
customer acceptance
• Volkswagen Commercial
Vehicles has offered the third
generation Caddy since early
2004
• Now also with permanent fourwheel drive using the most
competitive superior
technology from the
all-wheel drive TIGUAN
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
3
2 Targets
• Typical VW with non-problematic handling,
performance and good comfort
• Same payload as the front-wheel-driven Caddy
• Same fuel capacity as the front-wheel-driven Caddy
• Maximum use of carry over parts (COP)
• A minimum of modifications in the vehicle environment
• Small investment
• Availability for market within short time
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
4
3.1 The rear axles of the Caddy 4motion
Rear axle of
4x2 Caddy
Comparison of rear axles:
• Non driven axle for the
front driven Caddy
Rear axle of
4x4 Caddy
MPT ECS Leitner J.
• Driven beam axle of
Caddy 4motion
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
5
3.1 The rear axles of the Caddy 4motion
Schematic presentation of the two axles
in rear view
Front wheel driven
96 mm
4motion
Comparison of rear axles:
• 4motion rear axle to fit into
existing package
• Removing offset of axle tube Ö
space reduction for leaf spring
5 mm deby 96 mm
centered
• Tubes of 4motion axle with
offset to driveshaft of 5 mm to
gain some space for the leaf
spring
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
6
3.2 Package / Drive train
Adaptations for longer
wheelbase compared to front
wheel driven and TIGUAN
respectively:
• central propshaft support
• length of rear propshaft
• Haldex-flange
Drivetrain and front propshaft
are COP from TIGUAN
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
7
4 Concept of the rear axle
• Beam axle with integrated
Haldex-Gen 4 controlled clutch
• Cast center housing, tubes, wheel
carriers
• Ratio of i = 1.588
• Open bevel gear differential
• 15“ disk brakes
• Separated oil supplies/circuits for
Haldex clutch and axle drive
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
8
5 Carry over parts concept
HAA450
Validated series parts at VW and MPT
are carry over for this new application
• Hypoid gear set with ratio 1,588
(COP HAA450)
• Differential complete (COP HAA450)
Caddy axle
• Haldex 4 controlled clutch
(COP HAA450)
• Brake caliper and disk (COP Tiguan)
• Wheel bearings (COP Caddy)
MPT ECS Leitner J.
VW COP
MPT LANNACH COP HAA450
HALDEX 4 controlled clutch
Ö blue
Ö brown
Ö red
MPT ECS developed newly
Ö gray
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
9
6 New features in this axle and application
• Haldex 4 applied on beam axle –
dynamically moved with axle, not
fixed on chassis
• De-centered axle tube relative to
axle shaft Ö minimizing of the
necessary chassis lifting
• Guidance ring to ease assembly
and maintenance
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
10
7.1 Development / Timing
• Timing
Phase/AP/Aufgabe
Start
07
Mar
VW Caddy 4motion Rear Axle
1 Project start, order VW
2 Development generation PT1
2.1 Concept, design
2.2 Concept freeze
2.3 Prototype procurement
2.4 Functional testing PT1
2.5 1st PT1 prototype delivery to VW
2.6 Vecle testing at VW
2.7 First test results from VW
2.8 Testing on rigs
3 Development (pre-) series
Mon 15.03.04
Thu 26.07.07
26.07
09.08
Qtr 1, 2008
Jan
Mar
21.12 01.02
May
Qtr 3, 2008
Jul
Sep
26.06
Nov
20.10
07.11
21.12 01.02
Thu 09.08.07
Concept freeze
09.08
Mon 24.09.07
Tue 04.12.07
Fri 21.12.07
1st PT1 prototype delivery to VW
21.12
Fri 21.12.07
First test results from VW
Fri 01.02.08
01.02
Tue 04.12.07
26.06
Mon 26.11.07
3.3 Procurment serial tools / assembly line
3.4 Testing on rigs
3.5 Start of pre series delivery to VW
3.6 Vehicle testing at VW
Thu 13.12.07
MPT ECS Leitner J.
Nov
Thu 26.07.07
Mon 26.11.07
3.7 2-day production
Qtr 3, 2007
Jul
Sep
26.07
26.07
09.08
Thu 26.07.07 ject start, order VW
3.1 Series documentation
3.2 Release for procurement
4 SOP axle
5 SOP vehicle
May
Thu 13.12.07
Fri 27.06.08
Start of pre series delivery to VW
Thu 26.06.08
26.06
Mon 30.06.08
Mon 29.09.08
SOP axle
SOP vehicle
Mon 20.10.08
Fri 07.11.08
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
20.10
07.11
11
7.2 Development / Diff assembly
Differential assembly investigation
• Application of vertical press force
• Housing opens in lateral direction
• Differential including adjustment
shims is inserted from rear
without force
• Release of press force Ö
pretension of differential bearings
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
12
7.3 Development / FEA, fatigue analysis
All bolts tightened properly
Strength and fatigue calculation
• Application of NASTRAN for
strength calculations
Effect of reduced support in case some cover bolts loosened
• Application of FEMFAT for
fatigue calculations
• Analyses of extreme and
static load cases
• Analyses of endurance for
measured road load data
Factor in stress ~2.5
MPT ECS Leitner J.
• Especially flat cover design
for participating highly in load
transfer
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
13
7.4 Development / NVH
NVH investigations
• Modal analyses in simulation
• Modal analyses on hardware
• Vibrations analyses on test
bench in loaded condition
• Limit sample analyses
• Measurements in the vehicle
• Correlation established
between test rig and vehicle
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
14
7.5 Development / Structure testing
Testing of axle structure
• Endurance testing in a 8-cylinder
set-up
• Axle mounted elastically with
original springs and dampers
• Iteration channels (le/ri) for correlation measurement – test rig:
ƒ Wheel force transducers:
vertical force, lateral force,
longitudinal force, braking moment
ƒ Damper forces
ƒ Various strain gauges on leaf spring
ƒ Various strain gauges on the axle
structure
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
15
7.6 Development / Functional testing
Functional testing of the axle
• Lubrication
• Oil foaming
• Temperature behavior (in
loaded and unloaded
condition)
• Drag torque measurements
• Seal ring test
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
16
7.7 Development / Dyno testing
Rotational strength and
endurance testing of the axle
• 3-machine set-up
• Ultimate strength test (torque
increase up to rupture;
recording of torque and angle)
• Endurance testing by
application of a block cycle
program derived from road load
data
• Dynamic peak torque test
• Controlled application of
difference speed left / right to
test differential
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
17
8.1 Production of the axle
Assembly concept and assembly Line
• Tailor-made for the requested volume
• Structure part comes in with tubes pressed in
and all brackets welded on, painted
• Semi-automated assembly, optical checks by
laser, Poka Yoke solutions, recording of all
tightening torques / angles, drag torque,
backlash
• Coordinate measurement machine at the
assembly line for hypoid gear, differential and
housing measurement for proper gear setting
calculation
• Axle finished with wheel bearings and brakes
• Functional check of Haldex, tightness and
ABS sensor signals
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
18
8.2 Assembly of axle into vehicle
Axle installation in vehicle plant
• Mixed assembly of driven and
non driven rear axles into the
vehicle on the same line
• Use of existing tooling with a
minimum of modifications
• End-of-line test of vehicle
including 4motion functional
test
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
19
9 Summary
• Setpoints of the project Caddy 4motion, being fuel capacity, payload, comfort
and drivability were fulfilled with a tight budget for development and investment
• Rear beam axle for VW Caddy 4motion with controlled 4WD as optimum
drivetrain solution, realized in close cooperation between the OEM VW and
Magna Powertrain ECS as developer and supplier of the rear axle as a
component
• Optimal use of synergies by utilizing main carry over parts, developed and
verified, from VW’s and Magna Powertrain’s volume production of passenger
car components
• Beam axle specific parts tailor-made and developed acc. to the axle
specifications for the Caddy
• Development and industrialization until SOP in an extraordinarily short time
of only 15 months
• Vehicle very positively accepted by the market
MPT ECS Leitner J.
8. International CTI Symposium - Innovative Automotive Transmissions
Berlin, Dec. 2009
20
Thank you for your attention!
Dipl.-Ing. J. Leitner
josef.leitner@ecs.steyr.com
www.ecs.steyr.com