Automotive Engineering - April 2022 - 23

ELECTRIFICATION FEATURE
Engineering a
'MAVERICK' HYBRID
TRANSMISSION
Stator windings
undergoing inspection at
Ford's Ion Park laboratory.
Ford Powertrain engineers marry their new in-house electric machine with the
proven HF45 transmission - under aggressive vehicle program timing.
by Lindsay Brooke
F
ord's 2022 Maverick combines many practical
attributes that earned the new compact pickup
its North American Truck of the Year title,
among them a standard hybrid powertrain
which delivers a 42-mpg city (37 mpg combined) EPA
fuel economy rating. MCA (Maverick) program chief
Chris Mazur called the truck's aggressive $20,000
base price " a rallying cry " and a " wildly audacious
goal " for the development team. Their work included
integrating and validating a new Ford-designed electric
machine into the two-motor HF45 hybrid transmission,
on what engineers describe as " a dramatically
accelerated " timetable.
" The biggest challenge for us was time, " Manny
Barberena, the hybrid powertrain supervisor, told SAE
Media. " Go-fast programs make engineers nervous, but
we were able to overcome it by being efficient " - taking
the learnings, development and base calibration from
the Escape Hybrid powertrain that was basically carried
over and applying it to Maverick. " It really minimized
the amount of re-development, " he said. " We did have
to do some tuning to make things work properly with
this new transmission but it sure saved a lot of time in
going from Escape to this program on the common C2
architecture. It enabled us to hit the ground running. "
Working on the vehicle-development critical path,
the powertrain engineers set up two teams to optimize
AUTOMOTIVE ENGINEERING
efficiency. Barbarena's team focused on the vehicle level, encompassing
emissions, on-board diagnostics (OBD) and driveability, particularly
the NVH transitions from when the 2.5-L IC engine is running to
when it's off. " The transition should be invisible to the customer, " he
noted, " but NVH with electrified vehicles is a challenge because the
IC engine masks certain noises, some of them rather quiet. " A second
team, led by Abdul Hajiabdi, the E-drive system and applications supervisor,
focused on the Maverick's powertrain from a component
and systems level.
In addition to the new e-motor - the first of its kind developed in
house by Ford - Hajiabdi's team also juiced up the power electronics
for higher voltage and current, and upgraded the other e-machine
that serves as the HF45's generator, " pushing its boundaries "
he said.
" We were able to design the in-house motor [which Ford engineering
sources said is currently manufactured by Toshiba] in such a way
that it shares the footprint and all the transmission interfaces with
the machine that's used in Escape, " Hajiabdi said. " That was one of
the major enablers, the synergies, in keeping the cost down without
affecting other components. "
The team also revised both the rotor and stator, changing from
round distributed winding to flat-wire, hairpin-type windings on the
stator. The hairpin design resulted in an e-machine with higher current
density and higher torque density, paving the way for a slightly smaller
overall motor with about a 20% mass savings. On the rotor side, magnet
orientation and tension were re-engineered with innovation: The
magnets are molded into rotor core, rather than adhesively bonded.
April 2022 23
FORD
Automotive Engineering - April 2022

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