Engineering news
Torotrak Group and Wrightbus have completed the in-service trial of a Wrightbus StreetLite midi bus fitted with Torotrak’s Flybrid mechanical kinetic energy recovery system (KERS).
The Flybrid system recovers kinetic energy from braking and stores it in a spinning carbon fibre and steel flywheel, before transferring it back into the driveshaft to reduce load on the engine. The flywheel weighs 8.5kg and spins at up to 30,000rpm.
The trial, which took place on a bus route in Gillingham, Kent from March 2015, 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 companies say the findings have already proven invaluable in selecting the operating strategy for the volume production system, which will be a second generation design.
The new KERS design, which is already undergoing detailed testing on rigs and in a new Euro VI StreetLite bus, has reduced parts count and system weight by 30% and 80kg respectively and incorporates a simpler 2x2x2 clutched flywheel transmission system reducing ‘coast down’ losses and improving efficiency during torque transfer.
Adam Robson, Torotrak Group chief executive, said: “This is a very exciting time for the Group with the bus KERS project that started in 2012 going into commercial production from the middle of this year. I am delighted with the progress we have made and we look forward to delivering our first systems to Wrightbus during Q3 2016.”
Brian Maybin, Wrightbus engineering director, added: “After the invaluable in-service trials with Arriva, Wrightbus and Torotrak have confirmed that the next generation of flywheel is now under extensive durability testing, and after successful fuel trials, will be put into service trials from May 2016. Production vehicles will be able to be delivered into service late in 2016.”