The inclusion of mechanical energy recovery systems in mass-market cars has taken a step forward with the completion of a government-funded project to demonstrate flywheel hybrid technology in a prototype based on the Jaguar XF.
The car was demonstrated for the first time at the Cenex Low-Carbon Vehicle event in Millbrook, Bedfordshire last week. It uses a system developed by a consortium of British companies including Flybrid Systems, Jaguar Land Rover, Prodrive, Ricardo and Ford. The £3.3m project was part-funded by the government’s Technology Strategy Board.
The system works by using a small continuously variable transmission (CVT) connected to the car’s rear differential to transfer energy directly into a flywheel.
The flywheel spins at up to 60,000rpm, enabling it to achieve a high energy density and making it smaller and easier to package. When required, the CVT smoothly transfers the energy back to the wheels.
The Flybrid flywheel system was designed for use as the Kinetic Energy Recovery System in F1’s 2009 season but was not taken up by any teams. The system in the prototype provides 60kW of recovered energy, which can be used to provide an acceleration boost or improve fuel economy by 20%.
Mark Willows, technical specialist for Prodrive, which integrated the flywheel system into the vehicle, including the development of the electronics and software, said: “There were a lot of significant decisions made around when to store energy and when to remove it. The software has to be responsive to the driving conditions.”
Dick Elsy, chief executive of Torotrak, which provides the technology in the CVT, said: “This is half the size and half the cost of an equivalent battery based hybrid system. It’s a great bit of conventional mechanical engineering, and best of all its been developed entirely by a British consortium of companies.”
The research vehicle will be tested over the next few months. Ford is “examining the potential for secondary applications for flywheel-CVT systems”.