Flybrid Automotive Ltd., a small, innovative and privately-owned company with a hand-picked team of engineers at Silverstone, UK, has been working on flywheel-based kinetic energy recovery systems (KERS) for a few years with leading vehicle- builders, including JaguarLandRover (JLR).
In the case of JLR, the KERS has been linked to a continuously variable transmission (CVT) activated at the rear axle. The work has proved particularly beneficial and is now being extended. Initially commissioned to demonstrate fuel economy gains, the technology, still using the same basic rear axle mounted flywheel and CVT, is being directed towards enhancing vehicle performance.
However, at this juncture, JLR does not appear to have a platform that is design-ready to accept a flywheel-based KERS. In any case, Jaguar has a number of other vehicle programmes it is anxious to bring to market more quickly.
In the case of Volvo however, it appears that Flybrid Automotive entered the scene at just the moment the Swedish company was designing a new platform. And its new platform is flywheel-ready and could be introduced with a couple of years.
‘It is suitable for our technology and could be launched around the end of 2016,’ notes Tobias Knichel, Flybrid Automotive’s commercial manager.
Although Knichel is unwilling to be drawn further, it is not unreasonable to surmise that Volvo could introduce KERS as a performance-enhancing feature in a vehicle (as this is one area where KERS has been demonstrated to offer impressive gains) before being offered to improve fuel economy. On the other hand, KERS could be used as part of Volvo’s downsizing programme.
‘All those we have worked with are open to the technology and keen to investigate and learn,’ added Knichel.
The road-car application is one of a number of areas where Flybrid Automotive is seeking to apply flywheel-based KERS. Others include motorsport, off-highway and urban bus and truck. But of these the first production application of a flywheel hybrid is likely to appear in the Wrightbus StreetLite product range by 2014.
This marks a breakthrough for Flybrid Automotive which has pioneered the application of mechanical flywheel KERS using either the clutched flywheel transmission (CFT) or the continuously variable transmission (CVT) of the type developed by Torotrak (Development) Ltd. of Leyland, Lancs, UK.
As well as Wrightbus, Flybrid Automotive is working with Productiv, transmission maker Voith Turbo and bus operator Arriva. It is a unique opportunity for Flybrid Automotive to demonstrate the technology as Wrightbus and Voith both have European customers.
The final choice has yet to be made as whether the Wrightbus application will adopt CFT or CVT. It is understood that Flybrid Automotive, as systems integrator, will be largely responsible for the choice.
‘That is why it is important to see that Wrightbus is fully up to speed and into production. That is our first target,’ confirmed Knichel.
A prototype vehicle fitted with KERS will undergo extensive testing at the Millbrook Proving Ground in Bedfordshire (currently up for sale), with in-service trials with leading operating partner Arriva also scheduled as part of the project.
The aim is to make Flybrid-powered StreetLites available from 2014 onwards, both for new vehicles and as well as an upgrade in buses already in service.
The Flybrid Automotive project is part-funded through the Low Carbon Innovation Platform (LCVIP) scheme managed by the Technology Strategy Board (TSB), itself sponsored by the UK Department for Business, Innovation and Skills. The TSB has provided funding of £700,000 for this project, match funded by the project partners in a total project investment of £1,400,000.
The small Silverstone-based company aims to manufacture its units in-house and is currently assessing the best route to take to achieve this. More than likely it will expand its manufacturing facilities and increase it staff complement.
Flybrid Automotive employs about 20 people and has a turnover of around £2 million. It is currently recruiting for more staff.
‘For the volumes we are looking at for the Wrightbus application, we think we can cope within Flybrid Automotive,’ said Knichel. ‘We are looking at expanding our facilities. It is on our wish list of how we want to grow. We think the volumes that will be required for the bus and truck market can be achieved within Flybrid.’
The point at which Flybrid Automotive expands its facilities, both in terms of testing, machining and assembly to accomplish the requirements is one that has to be finely judged. Timing is critical.
Should a road-car application come along as the Wrightbus programme gathers momentum, though extremely welcome, will nonetheless pose additional challenges.
Meanwhile, the urban bus application, with its stop-start duties, could provide valuable information for another possible area of application, namely commercial vehicles used for urban delivery duty cycles. In this respect, test results from the Millbrook experience will be invaluable.
However, according to Knichel, truck applications of flywheel hybrids are likely to appear after urban bus and off-highway applications.
Knichel claims that off-highway duty offers the same level of timing as the urban bus application. Dump truck and shovel loaders could each use a flywheel-based KERS as a power boost power with a smaller-sized engine, or to achieve fuel economy gains.
However, all three – off-highway, bus and truck – are quite similar in terms of flywheel hybrid requirements and how quickly they can enter production and appear in the market. Road-car applications are seen as being longer term; they can take longer to evolve as more people (in product planning and manufacture) are involved in decision-making.
Motorsport applications, as Flybrid Automotive has proved, can move fastest of all from design, through manufacturing to on-road experience.
The city car application, in theory can offer huge potential for the relatively simple CFT transmission. A three-clutch CFT linked to a two-ratio range extender would generate a ratio width of six. At the other end of the range, for example in a luxury car, a seven-speed gearbox linked to a three-clutch CFT could generate 21 ratios – while a four-clutch CFT would generate 28.
Flywheel hybrid engineers claim a CFT offers a more flexible design and manufacturing solution than a CVT; for example when scaling up it can use four clutch packs instead of three. Also a CFT uses widely known and understood technology and components, and it has no requirement for special and expensive lubricants. ∎