Author Topic: Honda Jazz Mk4 2020  (Read 1679 times)

jazzaro

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Re: Honda Jazz Mk4 2020
« Reply #15 on: January 15, 2020, 10:14:37 AM »
That's what I understand sparky. The CVT on a hybrid Yaris is like the CVT on the current or Mk2 Jazz - the ratios change. The new Jazz has nothing in common, in terms of transmission, with the Toyota set up as seen on all their hybrid cars. Honda claim it is a completely new concept in a small car and I think they are justified in doing so.
Definetly no.
The E-CVT in hybrid yaris is the same of all other toyota hybrids, only size and battery type change: the petrol engine is always linked to the wheels through an epicliclic gear called PSD, power split device, where each of the carriers has the ability to rotate in its own unique way, providing a wide range of power options. The “Ring” carrier is sometimes powered by the battery-pack to provide the ability to drive using only electricity (both forward & backward), allowing the engine to stop running to save gas. At other times, the “Ring” carrier creates power, regenerating electricity when you use the brakes. The “Planet” carrier is powered by the petrol engine, which causes rotation of both the car’s wheels (for driving forward) and the “Sun” carrier (for generating electricity). And while the
“Planet” & “Sun” carriers are spinning, the “Ring” carrier can join in to provide additional thrust to the wheels or to allow engine RPM to be reduced. Lastly, the “Sun” carrier is also used for starting the engine.  It's  a sort of
 asymmetrical differential, because about 70% of the petrol engine power goes to wheels, the other 30% is directed to a small electric machine working as a motor (in both directions) but also as a generator, depending from the ECU. The other bigger electric machine is directly connected tho wheels, but it's the small one, connected to the sun gear, that set the "ratio" between the petrol engine and the wheels. In some old pics you can see a sort of chain inside this device, but it's only a chain connecting the ring gear with the final drive.
So the whole system works as a belt CVT, even if there are no belts inside. The same for the Honda I-MMD, working as a belt CVT but without belts; so both belong to the CVT transmission family, using wires and no belts, and that's why we cannot say that the Honda system is the first ECVT in the small car segment: both toy and honda are E-CVT without belts and pulleys, and Toy already sells a small ecvt hybrid car.

EDIT This is a simulator of the Toyota PSD (open it in Firefox because Chrome will close flash), Mg1 is the small motogenerator, Mg2 is the main electric motor connected directly with the wheels, ICE is the petrol engine: you can see how the vehicle speed (MG2) changes not following ICE and MG1 and, keeping ICE fixed, how the speed changes by MG1.
http://eahart.com/prius/psd/
« Last Edit: January 15, 2020, 02:36:43 PM by jazzaro »

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