Hybrid buses are here, and the technology is being improved. The Wrightbus is powered by just a standard 2.4 litre diesel engine – as used in the Ford Transit – mated with a hybrid system. And the performance is currently being optimised by leading engine development and engineering services provider, Roush Technologies (now rebranded as Revolve).
The Wrightbus programme involves optimising Series Hybrid Drive systems through a detailed analysis of generator load patterns. Roush engineers have been able to recalibrate the engine to operate at its peak performance throughout the drive cycle, by using smart charging and load control technology. Overall engine performance is significantly improved when compared with normal applications.
Drawing on its knowledge of the engine EMS system, Roush engineers have also been able to utilise some of the existing vehicle based strategies to carry out functions which otherwise would have required significant software changes. This, coupled with a unique CAN interface module, has allowed the full integration of the engine and its controller into the overall hybrid control system – and at a relatively low cost.
Paul Turner, Roush’s Technical Director of Product Development, says, “Having the engine control as a fully integrated part of the hybrid system – and coupled with a unique calibration, has enabled us to achieve exceptional improvements in fuel consumption. During back-to-back route trials in London, these fuel savings have been in excess of 30%. The application works extremely well and demonstrates the real potential for hybrid systems… but we do get a few raised eyebrows when people realise that we are running a full size double-decker bus with a 2.4 litre engine from a light van.”
Roush Technologies’ Executive Chairman, Andrew Williams says, “Roush is best known for its work in the car sector – but its significant knowledge and experience in other automotive areas is equally important. Programmes such as the Wrightbus hybrid system, alternative fuel projects for the defence industry, diesel and LPG applications – in addition to our high performance rally and racecar business – give an insight into the depth, scope and capability which we offer this important and growing area of the market.”