The belt-driven starter/generator (BSG) is the preferred architecture for mild hybrid electric vehicle powertrain designs. It provides a low-cost solution to reduce fuel consumptions and CO2 emissions. The unit enables fast stop/start, regenerative braking and boosting functions.
The BSG electronic control unit (ECU) requires instantaneous detection of rotor position and/or speed in order to work efficiently. The most reliable and economical way to achieve this is to mount a rotor positioning bearing (RPB) combined with a sensor directly integrated in the ECU.
In recent years, SKF has developed a benchmark RPB design in conjunction with one of the world’s leading BSG manufacturers. As the hybrid electric vehicle market is set to grow rapidly, newcomers are beginning to address the corresponding growth in demand for BSGs. SKF is currently gearing up to supply this market with a new universal RPB design that is both axially compact and robustly constructed, and which is also easily integrated into current and future BSG designs.
SKF’s RPB has an envelope (encompassing both bearing and magnetic ring) that is similar to that of a standalone bearing. As such, it is easy to press-fit onto the BSG shaft’s existing bearing location, adjacent to the ECU. Since the magnetic ring is mounted on top of the bearing outer ring, the axial length of the BSG is not badly impacted by sensor integration compared to a standard alternator. The new RPB will be suitable for both current 12V and upcoming 48V systems.
SKF Rotor positioning bearings are customized units that integrate a sealed bearing and magnetic impulse ring for measuring rotor angular position and/or speed in a variety of power transmission shaft applications and electrical machines, such as belt-driven starter/generators and traction motors.
SKF rotor positioning bearing units are robustly constructed and are designed to deliver high-level magnetic pulses that are easily detected in challenging under-hood applications affected by strong external magnetic fields.