Following intensive research and engineering development, Ricardo has announced a breakthrough in its revolutionary Kinergy hermetically sealed high-speed flywheel energy storage device. A significant improvement in the magnetic coupling and gearing system has now taken its efficiency to better than that of a conventional geared drive, consolidating Kinergy’s position as perhaps the most promising high-speed flywheel concept currently available.

The subject of nine Ricardo patent families in application, Kinergy represents a step-change advance in mechanical energy storage technology. It is based on a high-speed carbon fibre flywheel operating within a hermetically sealed vacuum chamber at speeds of up to 60,000 rev/min. But unlike current devices in which energy is imported and exported via a drive shaft operating at flywheel speed, Kinergy transfers torque directly through its containment wall using a magnetic gearing and coupling system.

This new breed of high-speed flywheel technology offers the prospect of enabling the unit to be sealed for life, thus avoiding the need for high-speed seals and a vacuum pump, and hence reducing costs and maintenance requirements. The consequent weight and space saving potential provides for a competitive packaging envelope, while the ability of the efficient magnetic coupling to incorporate a high gear ratio makes the input and export of torque significantly more manageable than would be the case in a more conventional direct-driven high-speed flywheel design.

Kinergy high-speed flywheel prototype testing

This first Kinergy prototype has resulted from a fast-track engineering development process intended to deliver the unit that will be at the core of the Flybus high-speed flywheel mechanical hybrid powertrain demonstrator vehicle. Following precise balancing of the flywheel rotor during construction and assembly, the unit was installed on a specially constructed dynamometer for development testing.

Major development thrust
Successive tests have been carried out at increasing speeds and compared with the results of engineering simulations of performance and efficiency. A major thrust of that development has been the elimination of stray magnetic losses in the coupling, and breakthroughs have been made that are critical to the success of the technology.

The 960 kJ rated Kinergy system provided for use on Flybus has been developed by Ricardo as part of its involvement in the KinerStor project, which also includes a longer term development process planned for completion towards the end of 2011. This work will focus on the further optimisation of the Kinergy system, primarily integration with an improved continuously variable transmission, and with electrical power take-off devices for recharging vehicle batteries. Also being explored are improvements to the design of the magnetic gearbox for better manufacturability and efficiency, and designs for improved component concepts including low-loss magnetic bearings and lighter containment systems. The prototype Kinergy system – as delivered to the Flybus project – was recently on display at the Ricardo and Torotrak booths at the Cenex LCV2011 event at Rockingham, UK.

Commenting on the latest announcement, Nick Owen, project director for research and collaboration at Ricardo UK, said the efficiency improvements just announced represented a significant milestone in the development of the highly promising Ricardo patented energy storage technology. “This next-generation, cost-effective, high-energy-density flywheel system technology genuinely moves the state-of-the art forward, offering the prospect of effective mechanical hybridisation of low-carbon powertrain applications in all types of vehicles from passenger cars to high-speed railway rolling stock,” Owen remarked.

Flybus and KinerStor
Ricardo is currently engaged in two research collaborations through which it is developing and refining its Kinergy high-speed flywheel technology. They relate to Flybus and KinerStor. Each of these projects is supported by an investment from the UK Government-backed Technology Strategy Board with balancing resources provided by the respective research partners. The first of these research collaborations – Flybus – involves the development of a Ricardo Kinergy flywheel energy storage device incorporating a Torotrak patented Continuously Variable Transmission (CVT) for installation in a demonstrator vehicle based on an Optare Solo commercial bus. The Flybus project is being led by Torotrak and includes partners Optare and Ricardo along with support from Allison Transmission.

The KinerStor project led by Ricardo comprises a consortium of industrial partners including CTG, JCB, Land Rover, SKF, Torotrak and Williams Hybrid Power. The project aims to demonstrate the potential of using high-speed flywheel technologies – including both Kinergy and competitor systems – in delivering hybrid systems with the potential for 30 per cent fuel savings (and equivalent reductions in CO2 emissions) at an on-cost of below £1000 ($1,575), thus enabling the mass-market uptake of hybrid vehicles in price-sensitive vehicle applications.

Ricardo is a global, world-class, multi-industry consultancy for engineering, technology, project innovation and strategy. With almost a century of delivering value, the company employs over 1,600 professional engineers, consultants and other staff. Its client list includes the world’s major transportation original equipment manufacturers, supply chain organisations, energy companies, financial institutions and governments.

The Technology Strategy Board is a business-led government body which works to create economic growth by ensuring that the UK is a global leader in innovation. Sponsored by the UK Government’s Department for Business, Innovation and Skills (BIS), the Technology Strategy Board brings together business, research and the public sector, supporting and accelerating the development of innovative products and services to meet market needs, tackle major societal challenges and help build the future economy.