Engineering Lubricants for an EV-Driven World

Engineering Lubricants for an EV-Driven World

As more EVs enter the market, how manufacturers develop the fluids that will protect them will become ever more critical

By Amanda Eastwood and Suzanne Patterson

Vehicle manufacturers are slowly shifting their focus away from internal combustion engines (ICEs) and turning their attention to building more electric vehicles (EVs). Part of this shift is the result of increasing consumer demand, but the influences on the burgeoning EV market go beyond consumers making private choices.

Global governments are establishing more regulations in response to climate change, which is expected to expand the EV market significantly. In combination with stricter carbon dioxide (CO2) targets, original equipment manufacturers (OEMs) are moving toward widespread electrification of their vehicle fleets—and lubricant manufacturers must change to meet these new vehicles’ specific demands.

In addition to their conventional lubricants, forward-thinking lubricant manufacturers have already added fluids that specifically target EVs. These lubricants must focus on the particular needs of e-axle hardware, performance and efficiency. In addition to their traditional role of protection, they will need to appropriately minimize electrical conductivity, prevent copper corrosion and improve energy efficiency. Lubricant manufacturers and oil marketers must learn quickly how to adapt.

Where the Market Stands Now
Experts agree that ICE vehicles will be actively in use for the foreseeable future, but the eventual transition to EVs appears inevitable, especially in the passenger car market. Analysts are predicting that by 2030, around two thirds of global new car sales will be made up of hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs).

How quickly this transition will occur depends on the region and country, but it is true that legislators around the world are beginning to push hard to remove ICE vehicles from their streets. Some, like Norway, are even looking to set specific deadlines by which ICE vehicles will no longer be able to operate.

OEMs have reacted with appropriate urgency, and many have pledged to stop producing ICE vehicles on similar time frames. While it can be a daunting task, it also makes the passenger vehicle market more dynamic than it has been in decades. New e-driveline architectures are being developed every day. Therefore, it follows suit that lubricant manufacturers develop fluids to maximize their operation.

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How e-Fluids Must Differ from Conventional Oils
Many modern EV architectures combine the electric motor in the gearbox with the inverter and control unit. Traditional fluids can corrode the copper found in these components, which increases the risk of damaging the EV’s power source. e-Fluids are carefully formulated to prevent corrosion so the e-device can operate safely and efficiently.

Moreover, the thermal stability of the lubricants is important because EVs often operate at higher temperatures than traditional ICE vehicles. At their core, however, the essential performance imperatives of e-fluids are unchanged from traditional ones—they must protect components like gears and bearings as well as the vehicle’s motor components. Since EVs demand lower viscosity fluids to maximize efficiency and heat transfer, lubricant manufacturers are working to strike the appropriate balance between form and function.

E-Fluid Operating Conditions
e-Fluids must have appropriate electrical conductivity which isn’t too high or too low. Too high, and the components may fall victim to pitting. Too low, and current can leak, creating shock hazards and diminishing the vehicle’s efficiency. The primary elements affecting the fluid’s electrical properties are its viscosity and additive packages.

In addition, lubricants must be compatible with the polymeric materials being used in EVs. The list includes, but is not limited to, polyamides, polyimides, polyester-amides, polyphenylene sulfides and polyether ether ketones (PEEK). EV OEMs are using these materials to build magnet wire insulation, coatings, slot liners and structural parts of the vehicle, including bearing cages.

Frequently EVs contain almost six kilometers of copper wiring in their batteries, windings and e-motor rotors, so e-fluids must be compatible with copper and the plastics that cover them. If these components get damaged in an EV, either through corrosion or creating deposits, it could destroy the e-motor’s circuitry and sensors and render the vehicle unusable.

EVs sometimes operate at higher temperatures than traditional ICE vehicles, which poses a particular danger of oxidation and sludge formation. That’s why e-fluids must be designed to manage such buildup, particularly when they encounter the motor. Balancing the need to protect gears and bearings with e-fluids’ material compatibility is one of the great challenges facing lubricant manufacturers today.

EV lubricants are being used in many ways, including to cool the motor. Therefore, e-fluids must have the thermal properties necessary to perform this task, but lowering viscosities to improve heat transfer can lead to an entirely new set of potential issues, including foaming, aeration, load-carrying capability and, as discussed earlier, electrical conductivity.

One final note: e-fluids must also be energy efficient, which is often done by lowering the viscosity to reduce churn losses. In some EVs, or under certain operating conditions, however, other considerations must take precedence over its efficiency, including traction and friction. For lubricant manufacturers, it will be critical to find the appropriate balance between efficiency and the other more traditional lubricant functions as they develop new fluids for these innovative vehicles.

Looking Ahead
As more EVs enter the market, how manufacturers develop the fluids that will protect them will become ever more critical. Determining how to maintain traditional performance demands like protecting components from undue wear and tear will still be important—but e-fluids will also have to protect the vehicle’s copper wiring, optimize electrical conductivity and improve efficiency.

Fortunately, current lubricant manufacturers are already hard at work to meet today’s EV requirements while still preparing for the next evolution of the technology. It will be crucial to continue these efforts as more countries and OEMs around the world wean themselves off ICE vehicles and e-fluids become more prevalent.

Amanda Eastwood, Product Manager, Driveline, The Lubrizol Corporation

Amanda Eastwood is a Product Manager for Driveline Additives, based in Hazelwood UK, with global responsibility for electrified driveline product lines. Prior to joining Lubrizol, Amanda worked in the European chemical industry in a variety of commercial and technical roles, both in Germany and the UK. In the last 15 years, Amanda’s focus has been in the lubricant and metalworking industry. Amanda has a Bachelor of Science in Chemistry with French and a PhD in Organic Chemistry, both obtained from the University of Hull.

Suzanne Patterson, Technology Manager, Driveline, The Lubrizol Corporation 

Suzanne Patterson is a Technology Manager for Driveline Additives, located in the United States, with global responsibility for axle and electrified vehicle fluid platform development and product support. Suzanne has been with The Lubrizol Corporation for 17 years working in the chemical synthesis of viscosity modifiers and small molecules before moving to Driveline. Suzanne received her PhD in organic chemistry from The Ohio State University.

30.06.2022 10:12:00

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