No More Side Effects

With a new generation of conductive seals, marketed under the name “eCON^evo”, Freudenberg Sealing Technologies aims to eliminate both of these effects. The company already launched the basic principle in series production in 2015 and it is used, for example, in the best-selling electric car in Europe. With eCON^evo, a very thin, conductive nonwoven material is attached to the radial shaft seal ring and provides direct electrical contact between the rotor shaft and motor housing. The development of a new material blend now makes it possible to use a nonwoven with the very low AC resistance of about one ohm. As a result, the electrical conductivity of the nonwoven material is high enough not only to prevent electro corrosion but also the emission of electromagnetic waves.

Quickly Operational

The solution used by Freudenberg Sealing Technologies has multiple advantages. The nonwoven material is only about a millimeter thick, which usually eliminates the need to make design changes on the motor. In addition, the nonwoven material is firmly attached to the radial shaft seal so that no additional steps are required when the engine is assembled. And since the component prevents electromagnetic interference directly at the motor, it can replace costly shielding in other areas, such as at the drive shafts. The supplier demonstrated the effectiveness on a test rig developed in-house, on which components for electric motors can be tested at speeds of up to 36,000 RPM. Development of this nonwoven technology is so advanced, series production may begin within a few months.“ The electrically conductive seal is a small, inconspicuous component,” said Stefan Morgenstern, Advance Developer at Freudenberg. “But its impact is enormous. We can eliminate unwanted side effects from electric drives with power semiconductors made of silicon carbide. As a result, the seal contributes to the ultra-fast charging of electric cars, and ultimately, to faster acceptance of electric mobility as a whole.”