Automotive Engineering - January/February 2021 - 16

Gearing EVs
for greater
efficiency

COVER STORY

Inmotive's 2-speed
Ingear transmission with
front case removed,
as currently used in
demonstrator vehicles.

Ingear, an innovative 2-speed transmission born in Canada, aims to unlock
electric-vehicle performance and efficiency.

by Lindsay Brooke

16 January/February 2021

CEO. His company's product, known as Ingear, currently is under evaluation by passenger- and commercial-vehicle makers. Conceptually influenced by the classic derailleur-type bicycle drivetrain, Ingear uses offthe-shelf automotive technology and standard materials and processes
to keep per-unit costs less than $150. Features include a BorgWarner
Morse inverted-tooth Hy-Vo silent chain, powder-metal components and
splash lubrication rather than a pressurized pump.
CAE analyses and prototype testing have shown the Ingear 2-speed
gearbox, in combination with some electric-motor optimization, is capable of system-efficiency gains of 7% to 12% compared to singlespeed types. Acceleration, gradeability and towing are improved by up
to 15%, according to Inmotive CTO Tony Wong. Inmotive has retrofitted
a Kia Soul EV with Ingear for industry demonstrations.

Right-sizing the e-machine
The idea for Ingear came to Wong, an avid cyclist, during a commute ten
years ago. " I was thinking about the torque-transfer inefficiencies of a
bike transmission - the derailleur shoving the chain side to side, often
with a slight misalignment of the chain, " he explained. " So, I thought,
what if instead of moving the chain, we instead moved the sprocket underneath it? There is empty space between the sprockets; what if we cut
the sprockets into 'pie slices' and devised a method of maintaining chain
engagement with the sprocket teeth throughout the shift? "
Wong presented his invention to Bottero, a tech-industry veteran,
and the two began a patent search. Among Ingear's " special sauces " are what they call the " key segments " - the sprocket component (now patented) that controls chain-to-sprocket alignment. An
animation of the Ingear's shifting dynamics can be found here:
https://www.youtube.com/watch?v=sTAhgMeub-g&feature=youtu.be
AUTOMOTIVE ENGINEERING

INMOTIVE

long-touted benefit of electric vehicles (EVs)
has been the utter simplicity of their drivetrains. With just a pair of reduction gears
between the traction motor and final drive,
single-speed gearing helps to minimize the bill of material (BoM) and driveline-system cost while delivering
acceptable performance.
But the more demanding duty cycles of commercial
EVs, off-road equipment and high-performance passenger EVs are prompting development of multi-speed solutions. Tesla got there first, albeit unsuccessfully, in 2007.
While still a start-up staffed mainly by electronics engineers, Tesla developed its own 2-speed gearset for use in
its Roadster sports car. Perhaps not surprisingly, catastrophic failures of early production units led Elon Musk to
reluctantly commission a clean-sheet single-speed unit
engineered by BorgWarner.
Since then, 2-speed EVs have trickled into low-volume
production at Porsche and exoticar maker Rimac. BMW
used a 2-speed transmission on its hybrid I8, and ZF has
prototyped a compact 2-speed unit (https://www.sae.
org/news/2019/07/zf-2-speed-ev-transmission-prototype). Enter Inmotive, a Toronto, Canada-based supplier
founded in 2010, with a novel twist to the 2-speed (and
potentially 3-speed) solution.
" We've been hearing from OEMs around the globe,
with growing demand for a 2-speed EV solution that provides enhanced range, improved performance characteristics and the opportunity to reduce cost by downsizing
the batteries and motors, " said Paul Bottero, Inmotive's

https://www.sae.org/news/2019/07/zf-2-speed-ev-transmission-prototype https://www.sae.org/news/2019/07/zf-2-speed-ev-transmission-prototype https://www.sae.org/news/2019/07/zf-2-speed-ev-transmission-prototype https://www.sae.org/news/2019/07/zf-2-speed-ev-transmission-prototype https://www.youtube.com/watch?v=sTAhgMeub-g&feature=youtu.be

Automotive Engineering - January/February 2021

Table of Contents for the Digital Edition of Automotive Engineering - January/February 2021