The electric vehicle industry is growing; global manufacturing and registrations of electric vehicles is increasing exponentially each year. Our engineers have extensive experience in designing seals for automotive applications, but we still find new challenges involved in sealing components within hybrid, hydrogen fuel and full battery powered electric vehicles.
The Application
Our customer has 30 years’ experience of providing pioneering technologies globally to the mobility industry. This established organisation is a supplier of powertrain solutions for electric and hybrid vehicles and traditional internal combustion power engines. The team of powertrain development experts approached our engineers for a high speed rotary seal. This is for the gearbox within an electric vehicle. The position of the rotary seal is needed between the wet transmission and dry e-motor, and pressed into a bulkhead housing.
The sealing lip runs on the surface of the transmission rotor shaft. It is pressed radially by a tension spring onto the shaft, and requires a dust lip to provide protection against dirt and debris from the environment on the dry motor side.
The shaft and housing dimensions, are all fixed and provided by the customer. These include full dimensional, surface finish, pressure, temperature and media specification for our engineers to review and propose a bespoke seal design.
Our sealing solution
The application media was a synthetic oil. This is relatively standard for an automotive application. However, because of the maximum working temperature, FKM (Viton) was the elastomer material to meet the required range.
As with many applications within electric vehicle gearboxes, the shaft speed is particularly high at 8500 RPM. Typically with these high speeds, seal design needs to ensure minimal friction to ensure the service life required.
Our application engineers designed a bespoke, double lipped spring energised seal.
On the dry e-motor side, the rubber lip has been designed to act as a dirt and dust excluder. There is a slight clearance from the shaft to avoid friction which prevents damage to the seal, additionally any unnecessary wear to the rotary system as a whole.
In the wet transmission side it is imperative that the oil is kept away from the e-motor with the same minimal friction requirements. Consequently, our engineers designed the seal with an inlaid PTFE lip with 15% graphite fill. It is energised with spring to ensure force to achieve ultimate shaft sealing performance.
Read more about our rotary seals HERE
