German sealing technology specialist Freudenberg has developed two in-wheel motors (IWM) sealing solutions: Cassette seal and V-seal, working in a closed and open system, respectively. The company’s patented sealing geometry supports original equipment manufacturers (OEMs) and manufacturers of electric motors ranging from electric cars to commercial vehicles right at the development stage.
The company says that in-wheel motors for EVs offer numerous benefits: components such as transmissions, brakes, and suspensions can either move much closer to the point of power transmission or be completely eliminated. The decisive advantages of vehicles equipped with IWM include wheel-specific torque control, enhanced comfort and more design space within the vehicle. This results in a better driving experience, greater range and more flexibility for developers.
At any speed, the seal provides optimal protection against dirt and water. A key feature of the Freudenberg seal is its dynamic adjustment of sealing effectiveness and friction – which adapts according to the rotational speed of the wheel. This prevents major friction losses.
The company has developed two significant seal designs: The cassette seal offers a double sealing lip and mating contact surface installed in a closed system, featuring precisely matched materials made of stainless steel and special rubber compounds. The required speed ranges and contamination protection can be scaled. The cassette seal stands out for its long service life and high functional reliability. It is capable of achieving up to 500,000 km and protection class IP67. This makes it a maintenance-free, self-lubricating solution throughout its entire service life.
The second design, a V-seal, works in an open system. Its particularly wear-resistant elastomers with excellent sliding properties, combined with attractive manufacturing costs, create a plug-and-play solution designed for flexible applications.
“As a solution, Freudenberg has positioned the sealing lip in such a way that high contact pressure maximizes sealing performance at low rotational speeds. At higher speeds, both the contact pressure and the friction are significantly reduced by the generated centrifugal forces. Depending on the customer’s requirements, the seal can even be fully lifted off the stator, which also eliminates friction, thus significantly increasing the lifetime of the seal.”
Luca Breusa, Product Developer at Freudenberg
