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CVT control not truly continuous?

Discussion in 'Gen 2 Prius Technical Discussion' started by 2009Prius, Nov 11, 2009.

  1. 2009Prius

    2009Prius A Wimpy DIYer

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    For highway driving, say, speed > 45 MPH, the CVT control does not seem truly continuous. At some low pressure position on the accelerator pedal, the so called superhighway mode, the instantaneous MPG on the MFD shows, say, 75 MPG. With an ever so slight increase of pressure on the accelerator pedal, the instantaneous MPG would make a quantum jump down to, say, 63 MPG. Then with an ever so slight decrease of pressure on the pedal, it jumps back up to 75 MPG. I think the ICE RPM also jumps up and down correspondingly although ScanGauge is too slow to show the jump, just the change. This behavior is very similar to "changing gears" although we all know the PSD is continuous (as long as the ICE is outputting power).

    Why is there such quantum jumps? Which part of the control system introduces such large quantization?
     
    #1 2009Prius, Nov 11, 2009
  2. qbee42

    qbee42 My other car is a boat

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    It's in the firmware. Presumably the control is table driven, having a fixed number of optimized levels.

    Tom
     
    #2 qbee42, Nov 11, 2009
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  3. Philosophe

    Philosophe 2010 Prius owner

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    Seems like a switch back and forth between "heretical mode/energy recirculation mode" and "normal mode" of the HSD. As you are pushing the pedal further, it switches from the most efficient heretical mode to the least efficient normal mode, to accelerate the car. When you release the pedal a bit, it switches back in heretical mode.

    See the explaination of both modes here: http://priuschat.com/forums/gen-ii-...sion/29352-introduction-prius-power-flow.html
     
    #3 Philosophe, Dec 23, 2009
  4. 2009Prius

    2009Prius A Wimpy DIYer

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    Makes sense. Thank you! :)
     
    #4 2009Prius, Dec 23, 2009
  5. V8Cobrakid

    V8Cobrakid Green Handyman

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    i remember reading an article a while ago that mentioned toyota mapping the prius acceleration pattern to match a six speed gearbox...
     
    #5 V8Cobrakid, Dec 23, 2009
  6. Philosophe

    Philosophe 2010 Prius owner

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    You may be confusing the Prius with the new Honda Insight. It has a CVT but Honda also chose to offer a simulated gear shift with paddles mounted on the steering wheel (which has absolutely no use!).

    The Prius acceleration is continuous, without any kind of "gear shift" patterns.
     
    #6 Philosophe, Dec 23, 2009
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