Cvt

[OldTrout]

Having just acquired a Lexus with a CVT I was interested to read about CVTs in a book by L.J.K. Straight published in 2003.

"DAF did it delightfully in small cars from 1958. Evolved versions have been given scant attention: in the mid-1990s a steplessly variable transmission was installed experimentally in a Williams F1 racing car, and in the hands of David Coulthard it lapped the Grand Prix circuit at Silverstone two seconds faster than the same care fitted with the standard gearbox, open of the most modern of its kind. By prevailing standards this was an enormous improvement - but when word of it got out, the regulatory authorities had it and all other fully automatic transmissions banned. In the advancement of technology, racing can be remarkably counter-productive."

I wonder how similar that experimental transmission was to the Toyota product then and the Lexus product now.

Can anyone provide more details?

J

[Zotto]

Toyota eCVT is totally different: no belts, 2 electric motors/generators and no sliding parts, a brilliant solution with epicycloidal gears.

Just a link:

http://eahart.com/prius/psd/

In small Lexus is so, in larger ones, GS 450h and LS is added a different final gear to let higher max speed keeping motors in project specs.

[OldTrout]

Zotto,

Informative as ever. Thank you. With your link and Wikipedia entry I think I now understand a little better than before.

I wonder what the CVT arrangement in that Williams F1 car was.

The present F1 cars have energy recovery and extra drive from electric motor when required but I assume that both of these are not integral with the engine. Or are they?

J

[ColinBarber]

It is more integrated than a Toyota hybrid system on a road vehicle. The output motor is directly connected to the engine/turbo before the conventional gearbox. They also use a heat recovery system to help charge the Battery store.