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Modern Atkinson Engine

Discussion in 'Gen 3 Prius Technical Discussion' started by bwilson4web, Jul 15, 2009.

  1. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Many of the Atkinson cycle engine web sites show the 1880s, linkage connected, crank shaft engine versus the modern Prius and Ford Atkinson engines. Also, I had to deal with a diesel advocate at another site and realized they don't understand how the Atkinson cycle is different than the Otto. So I put together a quick web page with a primitive animation of the modern Atkinson engine.

    Enjoy,
    Bob Wilson
     
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  2. ipopeye

    ipopeye Junior Member

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  3. Ogo

    Ogo Prius Owner since 2008

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    Prius's engine is in fact Otto engine using Atkison cycle. Atkinson engine is quite different in design as Atkison was trying to completely circumvent Otto's patents during the time of his invention. Atkison engine achieves all 4 cycles inside one crankshaft revolution, Prius's engine does not - as it is still Otto engine.

    So to be scientifically correct, we should talk about "Modern Atkinson cycle engine". Not "Modern Atkinson engine". :)
     
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  4. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Otto engine using Atkinson cycle is also known as Miller cycle.

    I am not able to see the animation. Bob, can you pick a different background color?
     
  5. qbee42

    qbee42 My other car is a boat

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    Only if it uses a supercharger. A Miller cycle engine is a modern Atkinson cycle with a supercharger.

    Tom
     
  6. tumbleweed

    tumbleweed Senior Member

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    Doesn't a Miller cycle engine need to have a supercharger?
     
  7. usbseawolf2000

    usbseawolf2000 HSD PhD

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    You guys are right. Miller cycle uses mechanical supercharger. Prius has electrical supercharger. :)
     
  8. Muhahahahaz

    Muhahahahaz Member

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    *so confused*
     
  9. yardman 49

    yardman 49 Active Member

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    +1 :sick:
     
  10. Flying White Dutchman

    Flying White Dutchman Senior Member

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  11. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Atkinson cycle boost the efficiency to Diesel level but lowers the torque. Miller cycle engine makes this up with a supercharger. Electric motor in Prius negates the need for high torque ICE; one of the synergy effect.
     
  12. ken1784

    ken1784 SuperMID designer

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  13. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I tested with:

    • Safari Mac - OK
    • Firefox Mac - OK
    • Camino Mac - OK
    • Internet Explorer Mac - hideous green, no animation
    • Firefox Windows - OK after Quicktime download
    • Internet Explorer Windows - OK
    What is your browser and operating system?

    Bob Wilson
     
  14. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Latest IE Windows and Google chrome both got green background and no animation.
     
  15. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I don't get too worried about whether the delayed intake valve closing is called an Atkinson or Miller cycle. The principle remains the same, a lower gas-ratio on the compression stroke and a higher gas-ratio on the expansion. The ability to tailor the expansion gives the engineers wide latitude to control the exhaust gas mixtures ... the amount of NO{x} and HCs.

    Better still, if the duration as well as timing of the intake valve closing is controlled, there is no need for a throttle plate.

    Bob Wilson
     
  16. PeterHaas

    PeterHaas Member

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    In 1882, when the Atkinson cycle engine was patented to circumvent the Otto cycle engine patent, there was no equivalent to today's variable valve timing with intelligence, better known as VVT-I, so Atkinson provided his cycle by employing a very complicated system of mechanical devices, said cycle which was necessarily fixed, and had no intelligence.

    Otto cycle engines are well-known, and have been widely employed for a century or more. High reliability and low cost are certainly several of its important advantages.

    However, Atkinson's original ideation of his cycle was neither high in reliability nor was it low in cost.

    Enter the VVT-I engine, which simulates an Atkinson or Atkinson-Miller cycle by employing simple, highly reliable additions to an Otto cycle engine.

    I agree that "modern Atkinson cycle engine" is more correct than "modern Atkinson engine".

    Just as correct would be "Otto cycle engine with additions for Atkinson or Atkinson-Miller cycle function and performance, hereinafter termed 'modern Atkinson cycle engine' for short".
     
  17. bisco

    bisco cookie crumbler

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    well i hope otto, miller and atkinson are getting the royalties.;)
     
  18. PeterHaas

    PeterHaas Member

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    Rudolph Diesel isn't getting any royalies for his inventive device.

    Besides, it took the likes of Kettering and his many associates to make Diesel engines a practical every-day reality.

    Think: Electro-Motive 567, 645 and 710 locomotive power plants, and Detroit Diesel 6-71 on-/off-road power plants, and its many derivatives.

    The practical "unit injector" was brought to market by General Motors in 1938 with both the 567 and the 6-71, a great many years after Diesel's "pulverized coal" Diesel-cycle engine, which was a failure.
     
    #18 PeterHaas, Jul 1, 2015
    Last edited: Jul 2, 2015
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  19. bisco

    bisco cookie crumbler

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    good point, i'm no expert in patents and licensing, that's for sure!
     
  20. PeterHaas

    PeterHaas Member

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    I DID enjoy that page, but I think the firing order may be incorrect.

    The Prius 4-bangers use a 1-3-4-2 firing order, which is functionally a 2-1-3-4 firing order.

    The intake ports are separated into two pairs: cyls 2 and 1, and cyls 3 and 4, this being "downwind" of the throttle plate.

    During cyl 2's compression stroke, the intake valve remains open for a significant time thereby forcing cyl 2's "excess charge air" into cyl 1.

    The same is true of cyl 3 into cyl 4.
     
    #20 PeterHaas, Jul 2, 2015
    Last edited: Jul 2, 2015