How does the ICE restart when driving?

Discussion in 'Gen 3 Prius Technical Discussion' started by ES44AC, May 21, 2012.

  1. ES44AC

    ES44AC C.A.U.S

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    Still getting used to my 'new to me' 2011 Prius II. I am loving the car it's a joy to drive, very smooth and quiet.

    When I pull the car out of the garage it's obvious when the ICE starts. But after that I never am aware of the starter being used at all.

    Is it just road noise that prevents me from hearing it? Or is it like a manual transmission car that you restart by letting out the clutch once it's rolling?

    Sounds silly I know but I had to ask, since someone asked me and I didn't know!

    Cheers
     
  2. qbee42

    qbee42 My other car is a boat

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    There is no starter in the conventional sense. Each Prius has two electric motors-generators (MG1 & MG2) and one internal combustion engine (ICE). These three devices are always geared together through a fixed planetary gearbox.

    When the Prius is driving without the ICE, the smaller MG, MG1, turns backward to keep the ICE from turning. When the ICE needs to start, MG1 reverses direction, causing the ICE to spin. Once the ICE is up to around 1,000 RPM and oil pressure is detected, the engine controller adds spark and fuel and you have a running engine.

    Tom
     
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  3. spiderman

    spiderman wretched

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    Boy I wish mine was still that smooth... I can pretty much tell when the ICE kicks in now (32K miles). That and the instance fuel economy meter is a dead give away.
     
  4. jdcollins5

    jdcollins5 Senior Member

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    That is too bad, spiderman. It must be your climate! With 46k miles, I still have to look at my SGII sometime to verify that my ICE is on or off.
     
  5. GrumpyCabbie

    GrumpyCabbie Senior Member

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    A way that helped me understand how the Prius works is that the hybrid system is similar (though not mechanically similar) to a traditional differential but in reverse, in that you can run the car on just the electric and you can run it on the petrol engine or often it runs on both.

    Now the hybrid system itself doesn't work anything like a traditional differential but the idea above helped me understand it better.

    Does that make sense?
     
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  6. telmo744

    telmo744 HSD fanatic

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    Yes. MG1, MG2 and ICE are linked as a differential, I sometimes support on that when I want to explain a bit of the HSD "gearbox"...
     
  7. kithmo

    kithmo Couch Potato

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    The only time I feel the EV to ICE transition is when I've depleted the HV (2 bars left) in EV, before the ICE has started from cold. I.e. not initiated 1st warm up cycle no power left to drive MG and the ICE has just started running to charge HV, then after 5-10 seconds the ICE suddenly picks up the power.
    With a warmed up ICE, I have, on rare occasions, felt a very slight bump as the ice stars when using a low quality fuel (supermarket brands here in the UK).
     
  8. spiderman

    spiderman wretched

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    Hmm, perhaps there is something up with mine. It has steadily been getting more noticeable over time. Or perhaps I am a really sensitive kinda guy. :eek:
     
  9. rrg

    rrg Active Member

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    Yes, I am very curious as to why the ICE becomes more noticeable over time. Almost like it's trying harder to start.

    Ok, shoot me down if you like but all my traditional cars over time would loose a good, dare I say it, ground connection over time in the engine compartment. The idle would be noticeably more rough and the starter took a little more longer to start.

    At around 50K to 70K miles, I cleaned and added additional grounds wires called the big three and a few of my own. What a difference, Scanguage reported rock solid idle, no more fluctuating and the start was instant. It stayed that way until 211K miles. That car is now RIP (rust in peace).

    In Alaska I would guess the metal grounds could probably use a good cleaning and some No-Ox grease to help keep the metal clean and away from corrosion at a minimum.

    just my2cents.
     
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  10. David Beale

    David Beale Senior Member

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    Heavier oil will make the transition more noticeable. Driver experience also helps. ;) Funny though. When I was getting Pearl ready for her new owner I removed the Scangauge etc. and then I had a hard time telling if the engine was running. I was relying on the Scangauge to tell me. Took a few days to "recalibrate" my senses. If moving I got a slight "nudge" when it restarted.