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How does reverse work?

Discussion in 'Gen 3 Prius Technical Discussion' started by kgall, Jul 26, 2011.

  1. kgall

    kgall Active Member

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    Just curious:
    Since HSD doesn't reall have gearing like a manual or auto trans, how does reverse work?
     
    #1 kgall, Jul 26, 2011
  2. mad-dog-one

    mad-dog-one Prius Enthusiast

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    It's all electric; no ICE or gears.
     
    #2 mad-dog-one, Jul 26, 2011
  3. spiderman

    spiderman wretched

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    Lets find out here. MG2 rotates in a counter-clockwise rotation (electricity coming from the HV battery) up to 25mph.
     
    #3 spiderman, Jul 26, 2011
  4. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    There are 2 electric motors which can spin in forwards or reverse and an engine that can only spin in one direction connected by a series of gears in a static arrangement called the "planetary gear set".

    Use this magic tool to figure it out: Toyota Prius - Power Split Device

    EDIT: Beaten to it by spidy
     
    #4 2k1Toaster, Jul 26, 2011
  5. kgall

    kgall Active Member

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    Thanks, mad, spi and 2k1.

    OK, I get that MG2 spins backward to drive the wheels.
    I also get that the engine can only operate in one direction. Thus, I think I get that the Planet Carrier can only go in one direction, right?

    But there are a few things I don't get, even after staring at the animations that folks sent me to, and some links from those:

    1. What happens when the traction battery is too low to drive MG2? I don't find myself stuck being unable to back up, so I'm guessing there must be some way to send energy indirectly from the ICE to spin MG2 backward. But, how, given that 72 percent of the power is going to push the ring gear forward? I'm clearly missing something, but what?????

    2. And it brings up a separate question: what happens in Park, when I turn my car on on a cold morning and the ICE starts? Is it the computer giving a net flow of zero energy to the wheels, but the planet carrier and the sun gear are moving?
     
    #5 kgall, Jul 28, 2011
  6. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    Did you play with the flash animation, or just stare at it?

    1. You stop moving until it charges back up via the ICE. You aren't normally stuck because "empty" is 40%. But unless you are pulling a lot of current, you can have the ICE spin high RPM to spin MG as a generator and the other MG to use that generated electricity to drive the wheels.

    The ICE is spinning and MG is spinning equally to charge up the battery.
     
    #6 2k1Toaster, Jul 28, 2011
  7. jdcollins5

    jdcollins5 Senior Member

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    Another way to look at this is:

    1. In order for the ICE to push the ring gear forward it has to have enough counter-torque from MG1 to "push" against to drive the ring gear.

    2. The ICE and MG1 can spin to charge the HV battery without producing counter-torque to push the ring gear.
     
    #7 jdcollins5, Jul 28, 2011
  8. Prius-it

    Prius-it Junior Member

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    My battery meter never goes below 2 bars. ICE turns on to charge when it's only 2 bars.
     
    #8 Prius-it, Jul 28, 2011
  9. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    That's good. It is supposed to. However there are times it will let you get down to 1 pink (I think) bar and even then, that is only 40% not fully empty.
     
    #9 2k1Toaster, Jul 28, 2011
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