In-service trial Flybrid mechanical kinetic energy recovery system

Torotrak, a leading UK low-carbon vehicle innovation company, has completed an in-service trial of a midi bus fitted with a Flybrid mechanical kinetic energy recovery system.

The trial was conducted on a standard bus route in Gillingham, Kent from March 2015. It successfully demonstrated the performance of the Flybrid KERS under real-world operating conditions including the capture, storage and release of energy from the brakes and the drivability of the system. The learnings from the trial have already proven invaluable in selecting the operating strategy for the volume production system, which will be a second generation design, says the company.

The new design is intended to further improve bus fuel efficiency and reduces the KERS weight and cost with a reduced parts count and system weight by 30 percent and 80kg respectively and incorporates a simpler 2x2x2 clutched flywheel transmission system reducing ‘coast down’ losses and improving efficiency during torque transfer.

Using common materials and manufacturing methods, and removing the requirement for replacement batteries during service life the flywheel-based technology can offer ‘exceptional value and an opportunity’ for widespread hybridisation. The KERS captures the kinetic energy that is normally wasted when the bus is braking and stores it in a steel and carbon fibre flywheel weighing 8.5kg and spinning at up to 30,000 rpm. The energy stored in the flywheel is then delivered back to the wheels reducing the energy that is required from the engine to accelerate the bus and so reducing the fuel consumption of the vehicle. The process of capturing, storing and releasing energy back to the wheels is fully automated, giving a high quality driving experience. The Flybrid KERS technology was developed in Formula 1 and has been applied in a variety of vehicle applications including motorsport, passenger road cars and excavators.