Jaguar is testing a British-engineered flywheel hybrid that promises an 80bhp power boost and up to a 20 per cent fuel economy improvement.
Packaged into the rear axle of an XF test prototype revealed at this week’s Low Carbon Vehicle event at Millbrook, the hybrid features components from British engineering specialists Flybrid Systems, Torotrak, Xtrac and Prodrive, plus input from Ricardo, and is being evaluated as an alternative to battery hybrids for storing waste energy during braking.
The £3m project is dubbed the FHSPV — Flywheel Hybrid System for Premium Vehicles — and is funded to the tune of around £2.2m by the government’s Technology Strategy Board.
“The FHSPV is really an engineering due diligence exercise,” says the project’s engineer Daniel Loftus. “We need to look at mechanical flywheels and see how they compare with electric hybrids. And then see if they have a production future.”
The composite flywheel is driven through a Torotrak/Xtrac CVT gearbox and spins at up to 60,000rpm to store a peak of 60kW, equivalent to 80bhp. A computer controls the flow of power from and to the flywheel, which can spin-up and deliver a boost in any part of the driving cycle, including performance on the move, although there’s only enough energy to deliver the peak 80bhp for around seven seconds.
Jaguar is currently testing it in stop-start city mode, which means the flywheel gathers energy lost in braking and then delivers ‘free’ power at start-up to save fuel.