Bus and Coach CV Sector Features & Interviews Logistics

A closer look at Torotrak’s Flybrid KERS

12 February 2015 #Bus and Coach #CV Sector #Features & Interviews #Logistics

Last year’s SMMT Award for Automotive Innovation was presented to Torotrak’s British-built Flybrid Kinetic Energy Recovery System (KERS) for buses and trucks. The award recognises the company’s commitment to innovation in improving efficiency, and reducing fuel consumption and CO2 emissions.

Previous winners of the prize include Ford, Optare and Gordon Murray Design and this year Torotrak beat off challenges from Jaguar Land Rover and Dearman, which both received Highly Commended accolades.

Torotrak was delighted to have won it. “Flybrid is a lovely piece of British engineering and clearly captured the imagination of the judges,” says Torotrak Product Development and Sales Director, Jon Hilton. With its roots in Formula 1 motor racing technology, it is a genuinely affordable mechanical alternative to going down the more-expensive diesel-electric hybrid route.

At the heart of Flybrid is a 60,000rpm flywheel that weighs a modest 8.5kg. “On a bus it is mounted at the rear next to the gearbox and linked to the rear diff by its own prop-shaft,” explains Hilton.

When the bus slows down the Flybrid system captures kinetic energy, which is transferred to the flywheel and released when the driver accelerates again. That reduces the load on the engine, cutting diesel usage and exhaust emissions.

“It saves enough fuel to pay for itself in less than five years,” says Hilton. “Operators can think in terms of average annual savings of around £4,000.”

Flybrid will be priced at around £15,000 once volume production is reached. The cost is about 25% of that of a diesel-electric hybrid system.

“Maintenance is minimal,” says Hilton. “All it requires is its gearbox oil changed every so often, and it has a projected life of one million kilometres.”

The system is on trial with Wrightbus, working closely with Arriva, and the indications so far are positive. Hilton is certain that Flybrid still makes sense even in a climate of declining oil prices. He points to the growing pressure on bus operators in urban areas from local authorities to cut CO2, NOx and particulate emissions, and to the incentives available.

Operating a Low Carbon Emission bus pays several pence per kilometre extra under the Bus Service Operator’s grant, and other subsidies are also available to offset the higher cost of low-emission technology.

Flybrid performs some of the functions of a retarder but cannot replace it entirely and Torotrak has yet to determine whether asking it to perform a dual role would reduce its lifespan.

“You still need a retarder to slow down if you are descending a steep hill for example, because under those circumstances the flywheel would not have the capacity to absorb the energy released,” he says.

“You also need one if you travel at speed along a motorway for some distance then leave it and descend a steep slip road, because the retarder will react more rapidly than the KERS will.”

Flybrid is unlikely to be used as a retarder on a heavy double-decker bus – Wrightbus has it on trial on the StreetLite single-decker.

Although Torotrak has concentrated its attention on the bus industry, there’s no reason why it shouldn’t be fitted to heavy trucks, especially those on urban distribution work, and could benefit refuse collection vehicles in particular.

Torotrak has also developed a CVT transmission licensed to Allison in the US for bus and truck applications and has come up with a variable-ratio supercharger.

“It can deliver high levels of boost at low engine speeds and low levels of boost at high engine speeds,” says Hilton.

Much of the engineering and research work is conducted at Silverstone, and Flybrid is made in Lancashire.

SMMT Chief Executive Mike Hawes, a member of the AAI judging panel, said, “The UK is one of the world’s leaders in automotive engineering, a fact epitomised by Torotrak’s Flybrid KERS.

“Not only is it a genuinely innovative concept, it is also in an advanced stage of development with huge potential to influence the wider automotive sector.”

Torotrak Chief Executive Officer Jeremy Deering said, “Winning such a prestigious award shows there is real faith in the commercial potential of our purely-mechanical hybrid system for heavy vehicle applications. By making hybridisation more accessible and affordable, we can make a real impact on fleet emissions and running costs. We hope this will raise awareness of our technology, and help us expand our reach more firmly into international markets.”

Filter News

Update Newsletter