A consortium of UK automotive companies has showcased a prototype flywheel hybrid system for premium vehicles at the Low Carbon Vehicle event at Millbrook, Bedfordshire. The system is claimed to add up to 82PS (60kW) of recovered energy and is predicted to demonstrate fuel economy gains of 20% relative to the current production model. Testing work is currently underway.
The consortium includes some of the UK's most respected names in automotive engineering - Jaguar Land Rover, Flybrid Systems, Ford, engineering consultancies Prodrive and Ricardo, and transmission experts Torotrak and Xtrac. Together, they will determine the viability of flywheel hybrids for production and cost-effective modular application. Part-funding is being provided by the UK's Technology Strategy Board.
Compared to conventional hybrid systems, flywheel hybrids reduce the number of energy conversions onboard the vehicle, improving the efficiency of the regenerative braking system. Instead of converting kinetic energy into electricity for storage in a battery, a small continuously variable transmission (CVT) connected to the car’s rear differential transfers the energy directly into a compact, high-speed flywheel. When the driver reapplies the accelerator, the CVT smoothly transfers the energy back to the wheels.
Commented Pete Richings, chief engineer at lead partner Jaguar Land Rover: "This research project explores the potential for more efficient and cost-competitive hybrid drivetrains that improve fuel economy while enhancing standards of vehicle refinement and performance. We have investigated the base technology, built the prototype and will be testing it in the next few months to see if it lives up to its potential."
The flywheel-CVT system uses a flywheel developed by Flybrid Systems. Spinning at speeds of up to 60,000rpm enables the flywheel to achieve a high energy density, making it smaller and easier to package. The CVT, which manages the flywheel's speed and the flow of kinetic energy, has been built by motorsport firm Xtrac using Torotrak's traction drive technology.
Automotive consultancy Prodrive is responsible for the system's configuration and integration into the vehicle. The company is also developing the system's sophisticated control software and electronics.
Ricardo is providing independent analysis on the potential for alternative technologies within the system.
Ford is examining the potential for secondary applications for flywheel-CVT systems.
Torotrak is also involved in two other industrial projects that use a compact, lightweight version of its CVT platform, scaled to deliver a rated power of 60kW. The projects are also part-funded by the UK's Technology Strategy Board. The first - 'Flybus' - involves Allison Transmission and bus manufacturer Optare, and uses a flywheel developed by engineering consultancy Ricardo. The second, the Ricardo-led 'KinerStor' project looks at low-cost kinetic energy recovery systems for mass-market applications, using Torotrak's CVT technology. Industrial partners include composites firm CTG, JCB, Land Rover, SKF and Williams Hybrid Power.