Creating Next Generation Lubricants For Electrified Mobility

As the world moves away from traditional internal combustion engines (ICEs) and towards complete electrification, the lubricant standards and test methods built up over a century of motoring become less valid.

Fluids for EVs have similar basic requirements to those for ICE vehicles: They must lubricate and cool moving components, reducing friction and wear and improving component durability. However, the operating conditions within an electric vehicle (EV) are radically different to those in an ICE: For example, the thousands of moving parts inside an ICE are replaced with a much simpler electric motor and most EVs do not have complex transmissions but instead a single fixed gear. Even though EVs have simpler drivetrains, EV fluids must contend with additional operating requirements compared to an ICE fluid and table 1 below details some of the main challenges.

Challenges in EV fluids vs. in ICE

Different operating environment
High torque from low RPM – high loads but poor film strength
Presence of electrical fields and high voltages
The potential for shared fluids between gearbox, motor, battery and power electronics (with immersion)
Faster rotational speeds: up to 30k rpm
Faster rotational speeds: up to 20-30k rpm
EV fluids have specific needs
Good (low) traction properties and low wear even at low viscosity
Must not degrade the electrical performance
High heat transfer ability
Corrosion resistant at high temperatures
Correct balance between dielectric strength and conductivity
Material compatibility requirements including copper and insulation materials
Table 1: Main challenges to take into consideration when formulating a fluids for an EV

We are currently at a turning point for electric mobility – where there are exciting and rapid changes to vehicle engineering, but their associated fluids have not kept pace with the new demands placed upon them. As the focus turns to efficiency for the next generation of electric vehicles, new fluids must be developed.

Croda is at the forefront of ester base oil development for the next generation of electric vehicles and we focus on the creation of novel, group V ester-based products. Our products reduce wear and traction, enabling energy efficient lubricant formulations with good material compatibility and long-term component durability.

Our product developments

  1. Novel low traction ester base fluids

In group III or group IV base oils, the addition of 20% of our development product DE 11846 reduces traction even under high loads and at slow speeds and reduces wear.

When compared to a neat group III or group IV base oil, DE 11846 has:

  • Significantly lower NOACK volatility
  • Significantly increased oxidation stability
  • Higher breakdown voltage
  • No adverse impacts on copper wire insulation or elastomer seals

2. Unique traction reducing co-base fluids for EV oils

In group III and group IV base oils, the addition of 5% Perfad 7726 or Perfad 7782:

  • Reduces traction coefficient by up to 32% vs. a PAO 100 thickened formulation
  • Offers an efficient thickening effect to maintain film strength and wear performance
  • Improves viscosity index by up to 11%
  • Does not impact viscosity in the KRL shear loss test (20 hours, 40°C)
  • Does not increase electrical conductivity or copper corrosion

Formulating with both 20% DE 11846 and 5% Perfad 7782 in a group IV base oil:

  • Reduces traction further compared to just the addition of DE 11846
  • In the FZG A10/16.6R/90 test, a formulation including Group IV + 20% DE 11846 + 5% Perfad 7782 outperformed a neat group IV by 2 load stages – offering significant wear benefits even at high loads.

Summary

  • Correct selection of fluids is crucial to the long-term performance of EV gearboxes and e-axles.
  • Traction within the gearbox reduces range and efficiency and current automatic transmission fluids do not have the required performance characteristics needed.
  • We are developing novel chemistry designed for the next generation of electric vehicles
  • Our knowledge of tuneable, ester-based chemistry allows us to tailor our products to your requirements.
  • We are developing novel group V base fluids and traction reducing co-base fluids suitable for the formulation of EV gearbox lubricants, offering up to 32% reduction in traction across a wide temperature range for very low traction within the gearbox or e-axle.

About Croda Energy Technologies

We create, make and sell speciality chemicals and additives for the global energy market. We overcome complex technical challenges through applied sustainability, collaboration and deep scientific expertise, so that our customers can efficiently power the world of tomorrow.

www.crodaenergytechnologies.com

Energy Technologies will be exhibiting at Lubricant Expo 2022. Visit them on stand 530