december2021 - 34

POWER CONTROLS
& ACCESSORIES
* Charger
* Vehicle software
* Air compressor
ENERGY STORAGE
* Active thermal management
* 150 miles estimated range
DRIVE INVERTERS 14XE
very efficient across the majority of that speed
range. In our 17Xe, for example, the electric motor
can run up to 5,500 rpm, and it's efficient; and by
efficient, I'd say over 92% efficient for about 80%
of that range. So, it's highly efficient, as opposed
to a diesel engine... That's a big difference with
an electric powertrain-you can get away with,
in some cases, a single speed, but in most cases
of the heavy-duty vehicle, two or three speeds,
and that's it. "
REGENERATIVE
BRAKING
Meritor
" The bigger the number, the bigger the vehicle
that it's intended to cover, " explained John
Bennett, VP and CTO at Meritor. " A 12Xe has an
integrated electric motor and two-speed transmission,
focused on Class 4 and 5 vehicles.
Our 14Xe-Class 6, 7, and then can be used as
a tandem for Class 8-also has an integrated
electric motor and a two or three speed transmission.
The 17Xe is targeting heavy Class 8 as
a single axle, so European applications which are
predominantly 4x2 or 6x2, using a single driving
axle. The 17Xe has a much larger motor and a
larger integrated transmission available as both
a two speed or a three speed. "
The 17xe is being used as the e-axle for Hyliion's
ERX truck.
Bennett noted that the transmission
can also be configured
as a single speed.
" Right off the bat you'll
notice, compared to a diesel
engine mounted to an automated
manual transmission,
that the number of speeds is
significantly reduced, " Bennett
noted. " The reason for that is
an electric motor has a very
wide speed range in comparison
to diesel engine, and it's
Diagnostics
Utilizing diagnostic software will remain standard
practice when servicing electric powertrains
and e-axles. Bennett explained that a
familiar process will still exist with diagnostics,
as plugging in a diagnostic tool " will flash fault
codes and indicate which areas are problematic
or need to be serviced. That'll give a technician
a pretty easy indication, very similar to today, of
where to look and where to go, and what things
to service, potentially. "
Understanding how the system functions
lends to being able to accurately diagnose performance
issues.
" The controls themselves are a bit more
complex, " Bennett heeded. " The mechanical parts
are simplified. The parts that are there are very
conventional. There's no clutch in these systems.
It's essentially gears, shafts, and bearings. "
Bennet said while the shift rail, shift collar,
and actuator will be familiar to technicians, the
controls, which are clutch-less, are more complex,
similar to an AMT.
" You're doing synchronization of the motor
speed; you're essentially taking the motor and
Toning down the torque
While electric axles provide hybrid and electric vehicles with instant power, one of
the potential drawbacks is also that they provide instant power. From a standstill,
diesel drivers are used to their trucks taking some time to pick up speed; electric
trucks can call on instant torque. When initially accelerating, say at a traffic light just
turned green, this could create some accidental rear-end events if drivers forget this.
" That stoplight scenario is a very real thing, " said Jeremy Freznick, senior
director of Dana Inc.'s commercial vehicle engineering. " If a driver has a
lapse in judgment and takes off from a light anticipating that it reacts like a
diesel truck, and it has that instantaneous torque, they're going to move a
little more swiftly than they would have with a diesel engine in there. "
This could be trained out of a driver fairly quickly, but some drivers may be
flipping back and forth between electric and diesel, Freznick pointed out.
Because the software within the powertrain control module is tunable, acceleration
can be calibrated to throttle some of that immediate torque.
" [For] customers that have been focused on system efficiency, we'll actually
implement acceleration limit logic into the software to make the vehicle
react and mimic more of the diesel application, " he explained.
Conversely, some fleets will want every newton available. Either way, Freznick
said Dana will work directly with fleets to make adjustments. Technicians,
however, will not be able to calibrate the e-axle acceleration themselves.
" There are a lot of moving pieces in there, and opening that up to customers
is like opening a can of worms, " he said. " All those software
controls and calibration is something that we keep in house. "
FleetMaintenance.com/inquire
34 Fleet Maintenance | December 2021

http://www.eberspaecher-na.com http://www.FleetMaintenance.com/inquire

december2021

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