autogyro wrote:CVT transmissions are only of real use in instrumentation and low power applications.
In high energy applications the control systems used to control cones, discs or other variable energy delivery components require too much energy to operate and the trade off is a reduction in efficiency.
haven't they made about 50000000 of the modern (steel 'belt') car CVTs ?
don't CVT-equipped cars give better economy than any equivalents with other types of transmission ?
unfortunately the modern car CVT generally has to fit in a space designed for other transmissions
so the belt is externally loaded (compressed), transmitting power by pushing on the 'slack' side (plus the usual pulling action)
this friction between the compressing band and the drive belt is extra friction, compared with a free design
the USP of the CVT is enabling the engine to work at higher ratios than any transmission that has non-continuous ratio variability
this is most useful eg with a gasoline ICE eg Japanese manufacturers
the earlier elastomer belt CVTs needed no mechanical differential and had none
as each wheel had its own CVT drive, this gave an inherent (non-friction) LSD characteristic
(wheel slip causes the slipping wheel's drive ratio to increase and its torque to decrease)
but yes, it's hard to see why a CVT would be much benefit in EV racing
racing flatters the efficiency of gear-type transmissions (gears designed around and run at one torque level can be 99.5% efficient)
I'd like to see EV/CVT fans in discussion with the 'EVs don't need gearboxes' people