4 ms·

I would not call a CVT "not a gearbox". Were Audis equipped with their multitronic option (not in any way related to hybrid or BEV) "cars without a gearbox"?

by usrusr 2y ago

cyberax 2y ago
A traditional CVT is a different beast. Prius is more accurately described as having a power-split gearbox that can dynamically split the power between the gasoline engine and the electric motor.
jgilias 2y ago
Yeah, I’d say “not a gearbox”. A gearbox to me is something where there are actual gears engaging and disengaging leading to wear and tear. Doesn’t matter what kind of fancy electronics are then used to hide the mechanical operation from me. A mechanical CVT with belts and pulleys with changing diameters is even worse. What the hybrids (e-CVT ones) have though is basically a planetary gear set, where the gears are put together at the factory, and stay there for the life of the car. To me that’s not a gearbox. At least not in the traditional sense. Transmission sure.
- usrusr 2y ago
  To me the key element is that it can run different transmission ratios: wether that's in discrete steps or a continuous ramp, that's an implementation detail. BEV (most of them) don't have that, the Prius has. When I read GP post my (surprised) impression from the "no gearbox" claim was that the Prius started as a serial hybrid. (it did not)
  - numpad0 2y ago
    Is THS actually capable of varying transmission ratio? I thought it can modulate resistance but not actually change gear ratio.
    - jgilias 2y ago
      Transmission ratio yes, as in, what part of engine power gets transmitted to the wheels. Individual gear ratios of course not.
      - numpad0 2y ago
        So the relationship between engine RPM and wheel RPM is always fixed, only torque split is varied, right? I think that's around where some confusions are coming from.
        jgilias 2y ago
        No, the engine can spin without the wheels spinning. Then MG1 gets spun and charges the battery (or spins freely if the battery is full). This page has a neat PSD simulation to help grok what happens: http://eahart.com/prius/psd/ http://eahart.com/prius/psd/ I think it only works from a computer though!
numpad0 2y ago
Prius system is considered "CVT" for bureaucratic reasons only, it's slightly fancier EV style reduction gear.

I would not call a CVT "not a gearbox". Were Audis equipped with their multitronic option (not in any way related to hybrid or BEV) "cars without a gearbox"?

by usrusr 2y ago

I would not call a CVT "not a gearbox". Were Audis equipped with their multitronic option (not in any way related to hybrid or BEV) "cars without a gearbox"?

cyberax 2y ago

A traditional CVT is a different beast. Prius is more accurately described as having a power-split gearbox that can dynamically split the power between the gasoline engine and the electric motor.

jgilias 2y ago

Yeah, I’d say “not a gearbox”. A gearbox to me is something where there are actual gears engaging and disengaging leading to wear and tear. Doesn’t matter what kind of fancy electronics are then used to hide the mechanical operation from me. A mechanical CVT with belts and pulleys with changing diameters is even worse. What the hybrids (e-CVT ones) have though is basically a planetary gear set, where the gears are put together at the factory, and stay there for the life of the car. To me that’s not a gearbox. At least not in the traditional sense. Transmission sure.

usrusr 2y ago
To me the key element is that it can run different transmission ratios: wether that's in discrete steps or a continuous ramp, that's an implementation detail. BEV (most of them) don't have that, the Prius has. When I read GP post my (surprised) impression from the "no gearbox" claim was that the Prius started as a serial hybrid. (it did not)
- numpad0 2y ago
  Is THS actually capable of varying transmission ratio? I thought it can modulate resistance but not actually change gear ratio.
  - jgilias 2y ago
    Transmission ratio yes, as in, what part of engine power gets transmitted to the wheels. Individual gear ratios of course not.
    - numpad0 2y ago
      So the relationship between engine RPM and wheel RPM is always fixed, only torque split is varied, right? I think that's around where some confusions are coming from.
      - jgilias 2y ago
        No, the engine can spin without the wheels spinning. Then MG1 gets spun and charges the battery (or spins freely if the battery is full). This page has a neat PSD simulation to help grok what happens: http://eahart.com/prius/psd/ http://eahart.com/prius/psd/ I think it only works from a computer though!

numpad0 2y ago

Prius system is considered "CVT" for bureaucratic reasons only, it's slightly fancier EV style reduction gear.