Towards the Environmentally-Friendly Motorcycle
David Limebeer
Department of Engineering Science, University of Oxford
Abstract. The feasibility of constructing a high-performance zero-emissions motorcycle will be considered. The broad purpose is to re-invent the two-wheeled road vehicle making it quieter, more fuel efficient and zero-carbon, but without a sacrifice in performance. This will be achieved by making the machine significantly lighter, twice as aerodynamically efficient as compared with conventional machines and battery powered. The new machine will be based on a combination of a new reduced-mass frame, the novel use of carbon fibre materials, a yokeless and segmented armature (YASA) traction motor and state-of-the-art lithium ion batteries and IGBT-based power electronics. The YASA motor has a 2-3 times higher specific torque (20Nm/kg) as compared with alternative motors. This high-torque traction motor will also facilitate the removal of the gearbox thereby reducing further the machine’s weight. The software-based motor control system makes adjustable throttle maps and adjustable regenerative breaking straight-forward embellishments. The primary aims of the project are to: (1) demonstrate experimentally the aerodynamic efficiency of a new frame and chassis layout, (2) demonstrate a significant reduction in the vehicle mass, (3) demonstrate the performance and range capabilities of an new all-electric drive train, and (4) show that the vehicle can be manufactured at costs and standards acceptable to the emerging electric and hybrid automotive industry. The key technical challenges to be overcome include the development of (1) the new aerodynamically efficient frame and fairing in carbon fibre materials, (2) a new multi-loop chain drive and steering assembly, (3) a special purpose YASA motor, power electronics and motor control system, (4) safe battery storage and battery management systems and (5) battery and motor cooling systems.
