Development work on Ricardo’s Kinergy flywheel technology has achieved an efficiency level greater than that of a conventional geared drive, claims the company.
The latest progress involves advances in the operation of the system’s magnetic coupling and gearing, according to Nick Owen, Ricardo’s Project Director for Research and Collaboration.
“This next generation, cost-effective, high energy density flywheel system technology genuinely moves the state-of-the-art forward," he said. "It offers the prospect of effective mechanical hybridization of low-carbon powertrain applications in all types of vehicles—from passenger cars to high speed railway rolling stock.”
The Ricardo system uses a high-speed carbon-fiber flywheel, operating within a hermetically sealed vacuum chamber at speeds up to 60,000 rpm. The system differs from other flywheel approaches in which energy is imported and exported via a driveshaft operating at flywheel speed.
Instead, "Kinergy transfers torque directly through its containment wall using a magnetic gearing and coupling system," Owen said. "This offers the prospect of enabling the unit to be sealed for life, obviating the need for high speed seals and a vacuum pump."
The company claims the technology reduces costs and maintenance requirements and provides weight and space saving potential, and subsequently more efficient packaging. Additionally, the magnetic coupling can incorporate a high gear ratio. "This makes the input and export of torque significantly more manageable than would be the case in a more conventional direct-drive high speed flywheel design," Owen noted.
Initially the 960J Kinergy system will be installed in a passenger bus technology demonstrator. Called the Flybus project, it is drawing on technology refinements developed as part of the KinerStor project, which the company leads in collaboration with Land Rover, SKF, Torotrak, Williams Hybrid Power, JCB, and CTG.
Flybus involves the development of Kinergy, which incorporates a Torotrak continuously variable transmission (CVT) for installation in a demonstrator vehicle based on an Optare Solo commercial bus. Torotrak leads the Flybus project, which is also supported by Allison Transmission.
The Kinergy technology could be scaled for use in smaller vehicles including cars, SUVs, and pick-ups, explained Owen.
Ricardo has revealed that Kinergy has been subjected to a series of successful tests at increasing speeds, demonstrating the elimination of stray magnetic losses in the coupling system. Work is now underway to develop the integration of Kinergy with the CVT, and with electrical power take-off (PTO) devices for recharging vehicle batteries.
Owen said improvements to the design of the magnetic gearbox for improved ease of manufacture and greater efficiency are also being developed in parallel with the use of low-loss magnetic bearings and lighter containment systems.
The KinerStor project was formed to demonstrate the potential for using high-speed flywheel technologies (including both Kinergy and competitor systems) in delivering hybrid systems with the potential for fuel savings of up to 30% and a similar reduction in CO2 emissions.
KinerStor aims to achieve this at an on-cost of sub-$1600 per application to help facilitate the mass market uptake of hybrid vehicles in price-sensitive vehicle applications.
Both the Flybus and KinerStor projects are supported via investments by the U.K. government-backed Technology Strategy Board as well as the participating companies.