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Does the Prius have a transmission?

Discussion in 'Gen 3 Prius Main Forum' started by Jeff N, Apr 2, 2014.

  1. Bill Norton

    Bill Norton Senior Member

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    Sorry, I'm slow, like your ....

    So, you don't have full power available if you are entering a highway and the engine has not powered up yet that cold, cold morning?

    usb said, "If you exceed the battery support power limit, ICE will skip the warm up and make full power. Safety is more important."


    Which is it?
     
  2. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Prius transmission got away with a very simple single speed because it tightly integrated two propulsion systems. For eCVT to work, both propulsions has to be used for splitting and blending power because they work as one. That was the fundamental idea of HSD and the Plugin version upgraded the EV power from the "parking lot" / "golf cart" level to the NEV level capable of city and even highway (low end) driving.
     
  3. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Both. John's statement didn't address when you floor it.

    Such situations are rare and you can switch to HV mode prior to merging into the highway. This way, engine would already be warmed up.

    Using the engine you got is better than lugging around one with an oversized electric motor to support it. You'll pay for it whether you know or not.
     
  4. john1701a

    john1701a Prius Guru

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    FULL is the usual acceleration power, used for things like merging onto highways.

    REDLINE is when you drop the pedal all the way to the floor to override warm-up.

    Seriously, when was the last time you ever needed to do that? It's nice to have a maximum available, but that's overkill for ordinary driving.

    I accelerate on my morning commute, on a uphill ramp onto a 70 mph highway, while still in warm-up mode without any trouble merging. I suppose if Prius PHV weighed an extra 621 pounds like Volt, more power would be needed.

    Prius engine has special modifications for low resistance cold starting. The plug-in model takes advantage of having that, rather than sacrificing electricity by lugging around a gas-engine without using it.
     
  5. usbseawolf2000

    usbseawolf2000 HSD PhD

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    ICE may be ready to use after 10 seconds but PiP will run the ICE around 1,500 rpm (in special mode to generate max heat) until the Catalyst converter gets to 400 deg F. Only then, it'll use the ICE as normal.

    It was done for emission reasons (eAT-PZEV) and takes some efficiency hit due to the battery conversion loss during this time.

    Some of us do the pre-warm up in HV mode if we know we are going to use the ICE to merge into highway or a big climb where we want to save the battery for later.

    Those are the fun things we can do with PiP. There is no dull boring EV only drive. I know Bill's preference is the complete opposite but perhaps it started with not understanding PiP's design goals or how it worked.
     
  6. Bill Norton

    Bill Norton Senior Member

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    OK, got it. Thanks !

    And you're right it is a drag lugging around a gas engine and only using it on road trips.
    However the Volt electric motors are not 'oversized'. I wish they were bigger!!
    There is no penalty, other than weight, having a bigger than needed EV motor. Watts is watts.
    The Spark EV sounds like a hoot, Big Motors, but has limited availability, and I have no use for a BEV.

    I love having an EREV.
    I can smash the throttle in 0° weather after pulling out of the driveway and
    Nobody Gets Hurt !!!
    Wiki says: 160 HP - 236 ft/lb Torque, Bay Bee !!
    Driving a real EV can be habit forming. Fast at 3-4 cents a mile!!

    The "Lifetime MPG" displays on both these cars are silly. But to a gas burning Prius owner I guess it looks awesome in your signature.
    I go weeks without any gas consumption, but electricity is not free. Well, for me the commute home is free. I get to plugin at work!

    Is there any talk of the next gen PiP? Will it be an EREV?
    Wouldn't it be funny if the Volt and the NG PiP share the exact same transaxle!?!
    (back on topic)

    PS, I can turn on my ICE anytime I want to. It's called HOLD mode. But why on earth would I ever want to do that in normal driving? I'll do it on road trips to save some EV miles for use in the town I'm going to. That way I can slip into the driveway at my destination as silently as I left town !!
     
  7. 70AARCUDA

    70AARCUDA Active Member

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    I'd rather doubt that'd happen (referring back to the 2009 "divorce" of GM & Toyota NUMMI)...although GM *is* using more & more Aisin-Warner transmissions these days.
     
  8. Troy Heagy

    Troy Heagy Member

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    Still not convinced a Prius trans is simpler than an automatic or CVT or manual trans. Ranking from complex to least complex:

    Prius has a planetary gear set plus two motors plus engine plus battery to power motors.

    - automatic cars replace the two motors/battery with two or three clutches (a clutch is much simpler than a motor)

    - CVT is just two resizable pulleys and a belt plus one clutch (typical).

    - manual is second simplest with 4 or 5 selectable gears

    - and EV is simplest of all with one gear (or no gears in a direct drive system)
     
  9. acceleraptor

    acceleraptor Member

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    ... pretty sure "redline" refers to hitting the top of the safe RPM range on the tachometer in a specific gear ratio, before the engine would be overheating (typically marked on the tachometer by a line between the "white" and "red" regions), before one nominally shifts to the next higher gear on a car with a multi-gear transmission, for maximum torque and acceleration.

    Flooring the accelerator is simply that, not the same thing as redlining an engine.

    And the continuously variable transmission, via planetary gear mechanisms, is a transmission. Such terms are so named by the function they perform (in this case, transmission (of power from the power plant source(s) to the intended destination of the wheels and tires)), not for the methods by which they were historically implemented (e.g. discrete gear ratios that must be shifted between).
     
  10. 70AARCUDA

    70AARCUDA Active Member

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    Uh, just what KIND of "simple" are you defining?

    1) Numerically SIMPLE, as in fewest number of components?
    2) Mechanically SIMPLE, as in shortest input-to-output path?
    3a) Efficiency SIMPLE, as in highest mechanical efficiency?
    3b) Efficiency SIMPLE, as in highest electrical efficiency?
    3c) Efficiency SIMPLE, as in highest TOTAL (mech+elect) efficiency?
    4) Physically SIMPLE, as in smallest size envelope?
    5) Physically SIMPLE, as in least weight?
    6a) Functionally SIMPLE, as in least number of MOVING parts?
    6b) Functionally SIMPLE, as in least number of ENGAGING parts?
    6c) Functionally SIMPLE, as in least number of MESHED parts?
    7) Operationally SIMPLE, as in least driver input required?
     
  11. john1701a

    john1701a Prius Guru

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    That's just a marketing term now, since there is no clear definition anymore.

    Did you have any specifics goals in mind?
     
  12. KennyGS

    KennyGS Senior Member

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    The engine in my 2007 Civic Si redlined at 8600 rpm, and there were times I would exceed 9000 on downshifts. I was told that as long as I stayed away from 10K, the valves would not contact the piston.

    It's my understanding that mechanical failure can occur well before any heat issues, which is the primary reason for a redline.
     
  13. john1701a

    john1701a Prius Guru

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    Since you don't have throttle control as with a traditional vehicle anyway, you can label them anything you want. The point remains, they're not the same as "full".
     
  14. acceleraptor

    acceleraptor Member

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    I suppose, but labeling terms with "anything one wants" leads to flawed conceptual models about how the concepts and events described by those terms relate to each other. Not that I was intent on joining the discussion, but looking back to what "full" seems to have been referring to, yes... the maximum power|torque|acceleration the car can ever achieve at its peak would not generally be available on a cold morning. (Perhaps it is with the Plug-In on EV mode..)
     
  15. john1701a

    john1701a Prius Guru

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    We'd need to specify event conditions too. "Cold" is quite vague. For that matter, so is "warmed up".
     
  16. acceleraptor

    acceleraptor Member

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    Yes. The assumptions I made were that the car had been undriven all night, and the night was lows for the local temperature range (which itself is pretty variable--you, for instance, list as in Minnesota, after all), but presumably far enough below operating temperature for peak performance of the car|engine, yet without conditions such as the coolant having frozen or such (which I might consider "exceptional" in that I would probably be required to take more steps than "start the car" for it to be drivable).
     
  17. Jeff N

    Jeff N The answer is 0042

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    There was a clear definition (the one proposed by GM engineers in an SAE technical paper) but through some undefined process it isn't clear anymore?

    True, GM's proposal has not been adopted in an SAE standard but the proposal was clear if you bother to read it.

    It says a vehicle is an EREV if
    • the EV aspect of the car is fully capable of highway driving (as opposed to only neighborhood streets), as defined by a California Air Resources Board (CARB) definition in a published document
    • the range extender does not start due to vehicle speed
    • the range extender does not start due to torque demand (accelerator pedal position)

    http://www.media.gm.com/content/dam/Media/microsites/product/volt/docs/paper.pdf

    That's a clear and useful description for the phrase "Extended Range Electric Vehicle" or EREV. It is a shorthand for a useful qualitative aspect of a plugin hybrid design.

    But apparently someone on an Internet forum misunderstood or guessed incorrectly at GM's definition and EREV is therefore now a vaguely defined marketing term?
     
  18. john1701a

    john1701a Prius Guru

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    What's clear is the definition has changed since rollout.

    What's also clear is being EREV requires tradeoffs.
     
  19. Jeff N

    Jeff N The answer is 0042

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    What was the process for how it changed?

    How is the definition now different?
     
  20. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Well, the range extender starts due to low temp, scheduled engine or fuel maintenance, open the hood, driver pushing the Hold button.

    The way it was described prior to rolling out, RE does not turn the wheels and operate like a series hybrid. The final product came out quite differently with PSD and 3 clutches.