Accueil         Home



Nous Contacter



EPM Engine Performance Map
WOT Wide Open Throttle
OEC Optimum Efficiency Curve
DRC Driving Resistance Curve
OD Overdrive ratios
UD Underdrive ratios
CPC Constant Power Curves
Iv Variator ratios (wsun-shaft/wcounter-shaft)


Technical points:

Note the total coverage of the Engine Performance Map by the DRCs of two-stages CVPST.  The conversion range of the transmission (lowest ratio/highest ratio) can attain value of 7.0...  That provides a good dynamic coefficient to the vehicle on the "first gear" [ratio] as well as a good overdrive ratio for quite cruising with low engine rpm. 

It is also worth noting that the DRC of max. power is obtained with high Iv ratio (close to 2.0), where the power split is the biggest (only about half of power is passing through the variator (and belt), the remaining portion passes directly through the gears which exhibit much higher efficiency).  That allows to drive with "pedal-to-metal" for long periods of time without worrying too much about the CVPST's belt life.  We can see the similar effect at the first stage [low "gear ratio"] at Iv=2.0 where the power split is protecting the belt, and enhancing the efficiency of the CVPST.  This is just the opposite of what is happening when using torque converters [so-called "power sapping devices"], where their efficiency is very poor at the launch of the vehicle.  That is, along with big mass of the today's vehicles, the main factor for elevated fuel consumption in the city traffic conditions.