– Freudenberg Sealing Technologies introduces a new sealing solution for electric vehicles.
Freudenberg Sealing Technologies has unveiled a new product for the automotive industry, a rectangular busbar overmold. This product is designed to protect an electric vehicle’s power electronics from damage. It combines busbars, seal, and guide into one package, simplifying assembly.
Electric vehicles often use oil-cooled motors. To ensure reliable operations, it’s essential to shield power electronics within the inverter from motor oil. This is achieved by sealing the busbar motor/inverter interface. Other electrical busbars with rectangular shapes, like those in immersion cooled batteries and oil pumps, also need sealing along their cables.
Traditional busbars, made from copper or aluminum sheets and bent to shape, present sealing challenges. The rectangular form isn’t ideal for standard sealing as corners hinder effective compression of the sealing material. Attempts to improve the contact surface with partially embossed edges or press-on structures don’t provide satisfactory sealing results. Post-processing methods like potting can be used but are time-consuming and impractical for large-scale applications. They also require additional space, limiting busbar design flexibility.
Freudenberg Sealing Technologies has developed a solution that seals rectangular busbars effectively, preventing damage to power electronics in electric vehicles. The patented, sealed, rectangular busbar overmold includes an elastomeric layer, which bonds firmly with the metallic conductor and the surrounding plastic later in the manufacturing process.
“Sealing rectangular shapes is considered the pinnacle in sealing technology, as leakage points often occur in the corners. Thanks to an elastomer layer between the metal and plastic we can now produce sealed busbars – and in a way that saves valuable space, as component and seal virtually become one. This new solution from Freudenberg Sealing Technologies enables our customers to seal their busbars even more reliably, while at the same time offering a high degree of design latitude,” says Parisa Burger, Business Development Manager and Project Manager at Freudenberg Sealing Technologies.
The new busbar seal configuration creates an impermeable bond by chemically pretreating the conductor surface with a primer and applying a special elastomeric coating. This forms a firmly bonded intermediate layer, followed by thermoplastic injection molding. The elastic material should preferably be based on vulcanizable elastomers such as FKM, AEM, ACM, HNBR, NBR, EPDM, but thermoplastic elastomers (TPE) can also be used.
The flexible coating reduces stress on the threshold between the copper and the thermoplastic matrix. The elastic coating reduces the notch effect at the conductor edges, minimizing the susceptibility of the electronic component to stress cracking.
“We are proud to offer our customers a solution that is not only technically advanced, but also saves time and space, and is cost efficient. This solution provides a wide range of benefits and application options. In particular, the inverter’s sensitive power electronics can now be reliably protected from liquids originating from the electric motor,” said Burger.
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