Rotrex Develops Electrically-Driven Fully Variable Supercharger
2 July 2008
Rotrex has developed an electrically-driven fully variable supercharger for automotive and transportation markets. In addition to its first application on a fuel cell hybrid, the product is also targeted for mild- and full-hybrid systems.
Due to the design of the Rotrex traction drive which can achieve speeds up to 300,000 rpm, high-speed and efficient low-inertia impellers can be applied. The electric motor only needs to turn up to 20,000 rpm—response time to reach 90% boost is lower than 300 milliseconds.
The Rotrex traction drive uses an elastic annulus with a small pre-span to secure contact between the roller planets and the sun shaft with a reasonable force. The patented “ramp effect†increases efficiency and reliability in the transmission by regulating the torque transfer capability on demand through self-adjusting planet geometry.
To enhance performance, the Rotrex traction drive uses a new family of synthetic hydrocarbon oils and greases. Developed specially for use in Rotrex superchargers, the fluid momentarily increases viscosity under high surface pressure, enhancing the traction drive performance by securing the optimum friction between rolling elements while cooling and protecting the system.
The fuel cell hybrid system is being is developed together with a German customer for a 25kW system based on a PEM fuel cell in combination with a battery and a supercapacitor.