Customer Case Study Automotive
Facts
Challenge
Design and production of
a function-integrated cooling
water jacket, that dissipates
heat directly at the electric
motor creating it.
Solution
Additive Manufacturing of
different test components
from polyamide as well as of
the final component with
integrated cooling channels
using the EOS M 290.
Results
•Functional: Integration of
cooling and transmission/
wheel mounts in a single
component
•Lightweight: 16% weight
reduction improves performance
•Effective: Increase in cooling
performance by 37% compared
to the previous season‘s car
Victorious: The cooling jackets for the electric motors were produced with Additive Manufacturing and played
a key role in ensuring that the race car performed well enough in the long-distance tests to secure the GreenTeam
2nd place in the overall ranking for the Formula Student Germany (courtesy of GreenTeam, Stuttgart University).
Leading the Pack – Race Car with Water-Cooled
Electric Motors Brings Students a Place on the Podium
Improved Cooling Thanks to Aluminum Jacket with Internal
Helix-Structure Produced with Additive Manufacturing
“Rallying has confirmed my presumption that a car with just two-wheel drive is nothing more than
Short profile
an emergency solution.” These words of racing legend Walter Röhrl also reflect the belief of the
The GreenTeam is a registered
GreenTeam, one of two Formula Student teams at the University of Stuttgart. For their racing car for
association and one of two
the 2013/2014 season the young engineers chose a four-wheel drive design with electric motors
Formula Student teams at the
positioned close to each of the wheels. There are 52 students that make up the team, which applies
University of Stuttgart. It was
innovative technology not only to powering the vehicle, but also to its manufacture. Central
formed in 2009 and is made up
components of the cooling system were produced using Additive Manufacturing, supported by EOS.
of students from the universities
of Stuttgart and Hohenheim,
Stuttgart Media University and
The Challenge
performance of an electric motor.
build-up. “The water cooling
the FOM Hochschule.
While the aims of the student
This allows motors to be smaller,
didn‘t function perfectly,” says
racing series Formula Student
leading to important weight
Dominik Schäfer, a member of the
Further Information
Electric (FSE) are broadly
savings.
team working on the power train.
www.greenteam-stuttgart.de
educational, success is ultimately
“It became clear that we had to
measured in lap times and
Alongside the benefits of trans-
take a closer look at the engine
victories. Electric engines provide
ferable engine power, contem-
cooling concept.” What they found
extremely high torque and
porary vehicle electronics allow
was that the high temperatures
thereby offer a very interesting
each wheel to be configured
were predominantly caused by
drive option. An additional
individually, ensuring the best
heat transfer and convection. “The
advantage is that they are
respective traction. Such a design,
reason for this lay in the geometry
relatively small in size. Because of
however, also has its disadvan
of the water channels. Hotspots
the high power density of electric
tages. One of these is the limited
had formed in areas with low
motors, the selection and design
possibility of heat dissipation due
water flow velocity,” continues
of the cooling concept has a big
to relatively little available space.
Schäfer. The design options were
influence on the performance and
In addition, the motors release
nonetheless limited – on the one
efficiency of the engine. Optimal
heat in close proximity to the
hand because of the lack of
cooling can lead to a significant
braking system. In short, the
space, and on the other, as
improvement in the long-term
temperature build-up and the
a result of the limitations of the
limited solutions to the problem
manufacturing process itself.
represent a significant challenge
Thanks to this complex
aluminum component, cooling
performance was increased by
37% . This achievement was the
result of optimized coolant flow
and improved heat dissipation
(courtesy of EOS GmbH).
wherein the basic choice is still
Solution
between air and water cooling.
Once again it was Additive
During the 2012/2013 season the
Manufacturing that pointed the
GreenTeam opted for water cooling
way toward a solution. One
and the concept proved to be
reason for this is the high degree
highly promising.
of flexibility offered in the
construction of any geometric
Nonetheless, the previous year‘s
form. Another is the ability to
car had to battle with heat
produce small series of components
both quickly and economically.
(only one is required for each
draining of water were also built
crashing into the back of you at
The process made it possible for
wheel). Thankfully EOS were on
in to the design. The result was
thirty when you‘re at a red light.“
the GreenTeam to produce three
hand to help.
that the young engineers were able
Perhaps the young engineers
to reduce the weight by 16%
shared the racing legend‘s thoughts
different forms for the cooling
unit and to not only test them in
“Production turned out to be
compared to the previous year –
as they set a new world record
simulation, but actually manu-
both fast and simple,” explains
a decisive factor in achieving
on the track.
facture them from the polyamide
Schäfer. “The transfer of the
greater speed and in the endurance
PA2200. The aim was to achieve
design data also took place
tests that are such a key part of
sufficient cooling at a minimum
without any problems.” The EOS
the FSE. The final weight was just
water pump throughput rate.
M 290 was used to build the
370 g. Even more important was
A larger pump could, of course,
component, layer by layer, from
the improvement in the cooling:
increase the pressure and flow
a fine metal powder by means of
performance rose by 37% over
velocity of the water, thereby
a high precision laser. The metal
the 2012/2013 season.
improving cooling. However, this
used, the EOS Aluminum AlSi10Mg,
would in turn require more energy
is particularly well suited to the
Nikolai Zaepernick is responsible
results, including 2nd place in
and a corresponding increase in
task at hand because it unites
for Strategy and Business
the overall standings for the
the weight of the battery or of
high mechanical and thermal
Development at EOS. Alongside
Formula Student Germany and
the pump itself. The best way to
durability with light weight,
the direct advantages brought by
1st place at the Formula
overcome this trade-off was
making it ideal for applications
the technology he also has an eye
Student China. Our car simply
through perfecting the geometry
on the race track. In very little
on its future potential. “Experts
performed extremely well. The
of the cooling channels.
time the racing team was able to
predict a big future for electro-
four-wheel drive with wheel-
benefit from the advantages of
mobility. Wheel-hub electric motors
hub motors proved the right
Schäfer tested different varia-
the helix geometry, conceived by
in road vehicles bring similar
choice in terms of performance,
tions in the form of the cooling
Schäfer, which had proved its
challenges to those faced in this
and the cooling water jacket
jacket using software for what
worth over other honeycomb and
racing series. It is good to know
produced through Additive
is known as Computational
meander structures.
that intelligent minds have already
Manufacturing was shown to
been successfully working around
be the ideal way of attaining
the issues that arise in this area.”
the required heat dissipation.
Fluid Dynamics (CFD). The final
“In the 2013/2014 season our
team achieved outstanding
component looked like a cup.
Results
The integrated cooling coils are
In addition to built-in cooling
channels on the interior wall,
channels, the finished component
Back on the track, the advantages
the build-up of heat compared
comparable to a coarse thread.
had the further advantage that
are there for all to see. The
to last year and EOS technology
This becomes a watertight
the cooling jacket was integrated
GreenTeam broke the world record
made a great contribution to
cooling pipe when the electrical
with both the transmission flange
in a drag racing competition for
this achievement.“
motor is slid into the cup in the
and the wheel mounts. Besides the
the Formula Student Germany
form of a cylinder. It is not a
advantages of part consolidation,
(FSG)! The race car covered the
Dominik Schäfer, Member of
simple task to construct such a
the total weight was reduced and
75 m distance in just 3.36 sec.
the power train working group
complex component with the
the final assembly was less com-
Walter Röhrl once summed up the
with GreenTeam, Stuttgart
necessary precision and such
plicated due to fewer individual
acceleration of his Audi Quattro
University
limited production quantities
parts. Brackets for the intake and
S1 as follows: “It‘s like someone
We were successful in reducing
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Status 03/2015. Technical data subject to change without notice. EOS is certified according to ISO 9001.