New F1 tech for road cars – the mechanical kinetic energy recovery system

In 2009, Formula One (F1) motor racing is introducing new rules that will lower the environmental impact of the sport. Part of this is to recover deceleration energy that can be stored for acceleration. The first commercial product resultant from this mandated new direction in technology will come from vehicle transmission design and manufacturing company Xtrac. A licence arrangement will enable Xtrac to exploit Torotrak’s full-toroidal traction drive technology to develop highly efficient and compact continuously variable transmissions (CVTs) for use in the new kinetic energy recovery systems (KERS) proposed for F1. Whatsmore, the system holds much promise for use in road cars. Very cool technology indeed! Detailed images.

The fact that Formula One had so directly contributed to a technology destined for road use, was not lost at the announcement when Peter Digby, managing director of Xtrac, commented: “The transfer of world-class transmission technology from Torotrak, combined with the added value of Xtrac’s expertise in the design and manufacture of transmissions for motorsport – and with clear potential to feed the resulting technical solution back into mainstream automotive use – is a good example of what I believe FIA president Max Mosley had in mind when he announced that Formula One should embrace an energy efficient future and open up the world of motorsport to new manufacturers.”

Dick Elsy, chief executive at Torotrak, added: “We are delighted to be working with Xtrac on this exciting new application of our transmission technology, to provide a highly efficient KERS solution for initial application in motorsport, but with a clear opportunity to apply the system in mainstream road cars to provide performance, economy and greenhouse gas emission benefits.”

How Torotrak’s full-toroidal traction drive technology works

The components within each variator include an input disc and an opposing output disc. Each disc is formed so that the gap created between the discs is ‘doughnut’ shaped; that is, the toroidal surfaces on each disc form the toroidal cavity.

Two or three rollers are located inside each toroidal cavity and are positioned so that the outer edge of each roller is in contact with the toroidal surfaces of the input disc and output disc.

As the input disc rotates, power is transferred via the rollers to the output disc, which rotates in the opposite direction to the input disc.

The angle of the roller determines the ratio of the Variator and therefore a change in the angle of the roller results in a change in the ratio. So, with the roller at a small radius (near the centre) on the input disc and at a large radius (near the edge) on the output disc the Variator produces a “low” ratio. Moving the roller across the discs to a large radius at the input disc and corresponding low radius at the output produces the “high” ratio and provides the full ratio sweep in a smooth, continuous manner.

The transfer of power through the contacting surfaces of the discs and rollers takes place via a microscopic film of specially developed long-molecule traction fluid. This fluid separates the rolling surfaces of the discs and rollers at their contact points.

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