Electric vehicle seals

Electric vehicle seals

February 19, 2019

Trelleborg Sealing Solutions

Adhesives/Sealants Assembly Design Components Materials

Trelleborg Sealing Solutions launches the HiSpin PDR RT and HiSpin HS40 seals developed for e-Mobility applications. Engineered to operate at high velocity, they make a significant step in overcoming issues related to sealing at high rotary speeds that limit electric vehicle (EV) range.

EV e-axles, a combined electric motor and gearbox that fits within the traditional engine space require efficient lubrication. However, the motor must remain dry, so a highly reliable seal is required between these two components.

Paul Taylor, Product Line Director at Trelleborg Sealing Solutions, says, “As electric motors run most efficiently at high speeds, the seal requirements are very different from those for a transmission input on a combustion-engine vehicle. Gasoline engines normally run at 2,000rpm to 4,000rpm, but the electrically driven transmission runs up to 8x faster, typically at 16,000rpm, and in the future this is likely to increase significantly.”

In the gearbox side of the electric drive system, lubrication can be limited to just a mist of lubricant. In these conditions rotating seals will be subject to high frictional forces and stick-slip after periods of rest, potentially causing wear and shortening the life of a seal, as well as power loss, lowering the travelling range of the vehicle.

Diversity of lubricants in the electric drive system is also a difficulty, and not all sealing materials are compatible with or operate effectively in the media involved. In addition, the trends in lubricants used could bring up unknown challenges when water-based, dielectric, and lower-viscosity media come into play.

To ensure that the needs of electric car manufacturers could be met quickly, Trelleborg Sealing Solutions put together a rapid response team to develop the new e-Mobility seals.

HiSpin PDR RT is constructed from two parts: a precision manufactured metal body and a mechanically retained Turcon polytetrafluoroethylene (PTFE) sealing element. It has a custom designed lip with additional features that improve performance and behavior of lip laydown profile on shaft, crimped into a precision-machined body.

Capable of 60m/sec and higher speeds, it has high and low temperature capability. Able to handle pressure, it is universally compatible with chemicals, and its low friction coefficient means it is capable of dry running. Prototypes are offered through a recently launched Rapid Prototype Service introduced to support customers. A conductive PTFE based grade is available.

HiSpin HS40 is of a familiar product type to automotive customers. With a unique bi-directional hydrodynamic lip feature, it has negligible frictional torque at high speeds. As a result of extensive FEA studies, its rubber lip geometry and flexible design give optimum lip contact on the shaft, ensuring optimum static and dynamic sealing performance.

The seal is manufactured using proven proprietary XLT fluoroelastomer (FKM) compounds to meet higher speeds and a wider operating temperature range. Compatible with increasingly aggressive synthetic automatic transmission fluids (ATF), it is produced using proven conventional high-volume manufacturing processes. Capable of speeds up to 40m/sec, the HiSpin HS40 has the ability to handle run out and is easy to install.