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How can they improve the fuel economy of the next generation Pruis?

Discussion in 'Gen 3 Prius Technical Discussion' started by techman41973, Aug 28, 2012.

  1. Mendel Leisk

    Mendel Leisk Senior Member

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    Very simple one: include the block heater as a standard item.
     
  2. john1701a

    john1701a Prius Guru

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    Oh! You beat me responding with the same by just a few minutes. It should be obvious that thermal efficiency of the engine leaves room for improvement, especially when integrated with a large traction motor and battery-pack along with a power-split device. But apparently, that's an easy benefit of the design to overlook.
     
  3. austingreen

    austingreen Senior Member

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    Absolutely correct, the prius is about being low emission, and diesel works against that. I am not convinced that a diesel hybrid is any more efficient than a di turbo hybrid, but toyota has not gone DI turbo to save cost and have fewer parts to go wrong. Toyota says they have a direct injection turbocharged engine in the lab with 45% efficiency, and this would be lower poluting and cost less than a diesel in a hybrid configuration. Diesels strength is higher efficiency at low loads. The hsd can keep the ice at higher load levels. I find it likely that Toyota stays with an efficient normally aspirated gasoline engine for the gen IV.

    I'm guessing that Toyota is buying BMWs diesels because they have a better engine at a better price point right now. Toyota can't be best at everything.:) I don't think the anouncement means toyota is going to sell fewer diesels, it just is going to use bmw as a supplier.

    Not to mention cost of car and the lack of refueling choices. I am sure the next prius phv will be able to use more renewable electricity. I have no idea why anyone would want to kill the prius line by converting it to hydrogen.
     
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  4. John H

    John H Senior Member

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    A common way to evaluate where the priority for improvement should be is to ask "If I had one more dollar to put in, where would I get the most benefit?" Variations would be the next $100, $1000, or $10,000.

    For me, the next place would be upgrading the onboard charger to get faster fill-ups on electricity, eventually overtaken by additional battery capacity to increase the range between charges. For a PiP I would think the battery capacity would be a higher priority for most.
     
  5. john1701a

    john1701a Prius Guru

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    You wouldn't want to invest everything on a single priority. Remember, Toyota strives for balance.

    Squeezing out a few more miles from a pack would be nice, but it's not really as important as rapid engine warm-up and even more efficient engine operation.
     
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  6. John H

    John H Senior Member

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    So maybe a little regen current to pre-heat the ICE systems?
     
  7. austingreen

    austingreen Senior Member

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    The rumor is a larger pack though for the phv. Its only a rumor, but a 20 mile pack might be more ballanced than an 11 mile pack;)

    A higher capacity pack won't really effect engine warm up, unless they do something like bmw's electric heating for pollution control. Direct injection with valve timing can lead to faster, more efficient warm-up routines, while using less fuel than port injected warm-up. There is additional cost, but it can lead to more hp in the same sized engine, or similer hp in a down sized engine. I'm guessing that toyota will be doing this in their next generation prius. Maybe they can use some of the inverter coolant to preheat the ice in the phv.
     
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  8. tedjohnson

    tedjohnson Member

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    I would suggest holding off the ICE starting until it is needed. Let it run on Battery until the discharge gets too great and then start up the ICE. Many times on short runs the ICE is not needed at all. Automatic grill shutters would be a plus as well.
     
  9. john1701a

    john1701a Prius Guru

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    That's the way it works already for the plug-in model. My trips through the burbs rarely ever needs the engine.

    For the regular model, a more efficient engine would provide a bigger bang-for-the-buck... for both consumer & automaker.
     
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  10. cwerdna

    cwerdna Senior Member

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    One of my friends (who has a Volt) mentioned that (IIRC) there were some Federal emissions regulation that dictated how quickly (by a certain point in time) cold startup emissions should fall after powering up. He said that GM got that regulation changed (for the Volt).

    This might be the reason why the Prius always fires up the ICE a few seconds after powering up and perhaps it can go away due to the regulation change? Unclear if this can only be done for PHEVs or if it can be carried over to regular HEVs.

    Unfortunately, he didn't know off the top of my head where the discussion of this was. Perhaps a Volt enthusiast can chime in and correct me on my assertions?
     
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  11. austingreen

    austingreen Senior Member

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    That sounds like the opposite that has happened. GM tried to get phevs to get a relaxation of the rules, since the engine is only used part of the time. CARB treats phevs like regular ice vehicles. New rules are still being proposed. If an engine is only run on 1/3 the miles, meaning the carb rules force a car like the volt to be 3 times lower emissions.
     
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  12. cwerdna

    cwerdna Senior Member

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    Hmm... sorry if my post was ambiguous.

    Basically, what I'm saying is that that supposedly GM got the Feds to alter the rules so that the Volt (and presumably other PHEVs?) DON'T need to fire up their ICE within x of # seconds after power up since the rule doesn't make sense for the Volt when its battery isn't depleted.
     
  13. ProximalSuns

    ProximalSuns Senior Member

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    You see a roughly 25% jump in mpg going from gas to Diesel models

    Hydrogen is very efficient if the product of solar powered electrolysis. The most efficient use would be direct burn though the fuel cell efficiencies may be approaching the direct burn. The problem long term with fuel cells is the same as with EV vehicles, do the resources exist to convert the current fleet of cars and trucks.
     
  14. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    If you had said Otto cycle to Diesel, I would agree with you. For Atkinson cycle to Diesel, more like 8%
     
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  15. John H

    John H Senior Member

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    I would think you would direct any solar capacity into a more direct load as a priority, and only use excess electric generation, night time wind perhaps, for electrolysis of hydrogen. The advantage of solar electric is that it matches peak loads on the grid, you can get peak prices when you sell it during peak loads.
     
  16. ProximalSuns

    ProximalSuns Senior Member

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    Short term it's OK but long term, do the resources exist for 1 billion cars with hybrid batteries or fuel cells? Solar derived hydrogen seems to be the perfect future fuel for transportation.
     
  17. John H

    John H Senior Member

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    I really don't think we should encourage a future with 1 billion cars. Maybe a billion electric scooters. Time spent in a personally piloted car (or scooter) is a huge waste of human resource.
     
  18. ProximalSuns

    ProximalSuns Senior Member

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    Too late for that it will be 2 billion soon. Have to deal with it.
     
  19. John H

    John H Senior Member

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    Enslaved by the very thing that granted us the freedom of mobility :(
     
  20. GasperG

    GasperG Senior Member

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    Use diesel tech to improve gasoline engine and efficiency is the same, price and complexity of that engine will be a big problem (just like current diesel engine). There will always be 10% difference of MPG at same efficiency, but the CO2 emissions will be the same and energy usage from oil will be the same. This is psychological effect, because we measure fuel by volume if we would measure fuel by weight it would be the other way around.

    Maybe we will see someday a hydrogen plug-in, the battery tech will always bee more efficient it will always be a cheaper choice of using electricity, hydrogen may be used only to extend range, but the problem is hydrogen won't wait in cars tank, it evaporates.
    We may see a different solution for quick fill up of the battery like EOS flow battery.