Truck & Off-Highway Engineering - October 2022 - 8

TECHNICAL INNOVATIONS
" But batteries are coming in all shapes
and sizes, and OEMs want to put them
in different parts of the vehicle. This is
also true of hydrogen fuel-cell vehicles.
So a lot of standardization needs to
happen in order for us to effectively
move to the next step of design for a
cost-effective modular frame. "
Shifting priorities
While many OEMs are updating legacy
chassis to more quickly and cost-effectively
retrofit EV and fuel cell powertrains,
that route is not without its own set of
challenges. " Previously, our frames were
all designed around an ICE powertrain, "
Bloomer said. " But there's definitely some
challenges and opportunities for optimizing
them around an EV powertrain. "
Bloomer went on to describe some of
the challenges he and his team at Ricardo
have seen for updating an ICE frame design
for an electrified driveline. " For one
thing, the frame now becomes a protecting
element for portions of the powertrain
such as sensitive electrical components
like fuel cells and batteries. Some batteries
have a high integrity structure while others
are very lightweight. So the frame is
not just a mounting point, but also protecting
the power source from impacts,
partial deflection inputs and vibration. "
eAxles also can present challenges in
chassis development. " eAxles lead to a
significant increase in unsprung mass, " he
said. " This not only affects the ride quality,
but you're also putting a lot of sensitive
electronics on the unsprung mass,
which can present a durability challenge. "
Bloomer further described some of the
integration challenges of eAxles: " You
OEM engineers must reconsider every aspect of vehicle design to successfully
integrate electrified powertrains. The Freightliner eM2 medium-duty electric truck is shown.
also have to consider the interaction between
the driveline and the park brake.
Do you want those to work together? Do
you need just one or the other or both?
So you have to find the solution there
with very different axle architecture. "
High-voltage systems also offer some
challenges and opportunities for brake
and steering integration. " Going to
high-voltage components enables electromechanical
steering and brakes,
which can be much more package-efficient
and integrated into the frame. This
can translate to both heavy- and lightduty
commercial vehicles. Steer-by-wire
is also a potential solution for modularity
between designs thanks to these
higher-voltage systems. "
Modern problems, modern
solutions
Despite the challenges and disruption
electrification is causing in the commercial
truck sector, it is also opening opportunities
for new ideas and designs that before
may not have been possible. " For certain
lighter vehicle classes, you have the opportunity
to go for automotive-style suspension
architectures such as independent
suspension, " Bloomer said. " This provides
clear advantages in ride and handling.
An electric driveline also becomes
part of the sprung mass in this instance,
which provides durability advantages. "
The upcoming shift in traditional powRicardo
has partnered with Lightning eMotors to provide commercial electric vehicles to
customers in the U.K.
8 October 2022
ertrains is reportedly creating some supply
chain challenges, particularly for hydraulic
brakes. " These vehicles come in
roughly between what is currently available
for lighter-duty hydraulic brakes
and heavy-truck air brakes, " Bloomer
said. " There's not many suppliers for
hydraulic brakes components on the
scale these trucks will require, so we can
see this as a particular challenge. "
Turney of Daimler Truck North
America also described the shift in
mentality that OEMs have undergone to
meet the challenges of EV powertrain
integration. " We have to reconsider every
aspect of vehicle design, " he said.
" We [now] have to cool a battery and a
lot of other things plus we have an
HVAC system that doesn't have an engine.
It's a totally new approach. We
have to keep an open mind throughout
the design process and ask if what
we're doing is actually the best way to
integrate an alternative powertrain "
Matt Wolfe
TRUCK & OFF-HIGHWAY ENGINEERING
FROM TOP: DTNA; RICARDO

Truck & Off-Highway Engineering - October 2022

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