Truck & Off-Highway Engineering - December 2021 - 20

DEVELOPING
EV-specific lubes
Many OEMs
have an increasing
interest in electrifying
the transmission, but
an integrated e-motor
presents significant
tribological challenges.
As electric-vehicle technology accelerates, dedicated e-fluids
are necessary to maintain proper levels of drivetrain performance.
by Dr. Michael Gahagan
E
lectric vehicle (EV) technology is transforming the world of
transportation at an increasingly fast pace, with a range of
options including full hybrids, plug-in hybrids or all-electric
vehicles. Most existing OEMs are pursuing electrification in
some form, and there have been a variety of new market entrants.
As the variety of EVs proliferates, lubricant manufacturers must
keep pace to ensure proper fluid management. It has become increasingly
clear that high-performance fluids and lubricants are even
more necessary than ever, and a wide variety of non-traditional performance
characteristics must be accounted for. Electrified drivetrains
have different demands; therefore, new fluid formulations are a
necessity for longevity and protection.
Many OEMs who are developing electrified drivetrains have an increasing
interest in electrifying the transmission, and for good reason:
Electrified dual clutch transmissions (e-DCTs) can fit with traditional
hardware platforms and can reduce the manufacturing complexity,
setting up a cost advantage for hybrids. It is also a good example
of some of the inherent challenges of electrification.
Compared to entirely electrical vehicles, a vehicle equipped with an
e-DCT can have a smaller battery and hybrid-electric powertrain. It
also eliminates the starter motor, which again lowers its complexity.
e-DCTs are highly efficient, save on energy use and can be made up of
helical gears, synchronizers, clutches, axles and integrated e-motors.
All these components are increasingly expected to be lubricated
by a common fluid. For traditional transmissions, this required certain
performance attributes. The addition of the integrated e-motor, however,
presents significant tribological challenges and a range of new
performance characteristics that an e-fluid must be able to provide,
including corrosion control, thermal properties, material compatibility,
friction performance, electrical properties, and prevention of
noise, vibration and harshness (NVH).
20 December 2021
Copper compatibility
Because e-fluids interact with charged components in
an electrified drivetrain, a properly formulated e-fluid
must maintain the right conductive characteristics.
Traditional lubricants are already very good electrical
insulators (most maintain electrical conductivity of
around 0.0000000001 Siemens/cm), but for the purposes
of allaying safety concerns, e-fluids generally
are expected to maintain even higher insulative properties
than traditional fluids.
Issues may arise, however, if an e-fluid's conductivity
is too low. A properly formulated e-fluid should maintain
a slight level of conductivity in order to prevent
the buildup of static electricity. Achieving this balance
of conductive properties is essential to prevent issues
in the transmission.
An e-fluid's interaction with electrical componentry
also brings with it concerns around material compatibility
and how it interacts with an increasing amount
of wiring and electronics. Modern EVs incorporate a
significant amount of copper and power electronics, as
well as a range of plastics used as insulation or in
place of traditional metal. In many cases, electrical
componentry may be entirely immersed in a fluid and
must remain operational.
Therefore, an e-fluid must be compatible with and
be able to protect a broader range of materials.
Copper, specifically, poses a critical challenge, as it is
highly susceptible to liquid and vapor phase corrosion.
To demonstrate this phenomenon, Lubrizol used a
TRUCK & OFF-HIGHWAY ENGINEERING
RICARDO

Truck & Off-Highway Engineering - December 2021

Table of Contents for the Digital Edition of Truck & Off-Highway Engineering - December 2021

Truck & Off-Highway Engineering - December 2021 - CVR4
Truck & Off-Highway Engineering - December 2021 - CVRA
Truck & Off-Highway Engineering - December 2021 - CVRB
Truck & Off-Highway Engineering - December 2021 - CVR1
Truck & Off-Highway Engineering - December 2021 - CVR2
Truck & Off-Highway Engineering - December 2021 - 1
Truck & Off-Highway Engineering - December 2021 - 2
Truck & Off-Highway Engineering - December 2021 - 3
Truck & Off-Highway Engineering - December 2021 - 4
Truck & Off-Highway Engineering - December 2021 - 5
Truck & Off-Highway Engineering - December 2021 - 6
Truck & Off-Highway Engineering - December 2021 - 7
Truck & Off-Highway Engineering - December 2021 - 8
Truck & Off-Highway Engineering - December 2021 - 9
Truck & Off-Highway Engineering - December 2021 - 10
Truck & Off-Highway Engineering - December 2021 - 11
Truck & Off-Highway Engineering - December 2021 - 12
Truck & Off-Highway Engineering - December 2021 - 13
Truck & Off-Highway Engineering - December 2021 - 14
Truck & Off-Highway Engineering - December 2021 - 15
Truck & Off-Highway Engineering - December 2021 - 16
Truck & Off-Highway Engineering - December 2021 - 17
Truck & Off-Highway Engineering - December 2021 - 18
Truck & Off-Highway Engineering - December 2021 - 19
Truck & Off-Highway Engineering - December 2021 - 20
Truck & Off-Highway Engineering - December 2021 - 21
Truck & Off-Highway Engineering - December 2021 - 22
Truck & Off-Highway Engineering - December 2021 - 23
Truck & Off-Highway Engineering - December 2021 - 24
Truck & Off-Highway Engineering - December 2021 - 25
Truck & Off-Highway Engineering - December 2021 - 26
Truck & Off-Highway Engineering - December 2021 - CVR3
Truck & Off-Highway Engineering - December 2021 - CVR4
https://www.nxtbook.com/smg/sae/22TOHE06
https://www.nxtbook.com/smg/sae/22TOHE04
https://www.nxtbook.com/smg/sae/22TOHE02
https://www.nxtbook.com/smg/sae/21TOHE12
https://www.nxtbook.com/smg/sae/21TOHE10
https://www.nxtbook.com/smg/sae/21TOHE08
https://www.nxtbook.com/smg/sae/21TOHE06
https://www.nxtbook.com/smg/sae/21TOHE04
https://www.nxtbook.com/smg/sae/21TOHE02
https://www.nxtbookmedia.com