Hybrid minivan is coming.. and no it is not HEV

Discussion in 'Prius, Hybrid, EV and Alt-Fuel News' started by cyclopathic, Apr 28, 2011.

  1. cyclopathic

    cyclopathic Senior Member

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    donee, I meant "fluid" not "fuel", my mistake.

    yes PV/T is constant for ideal gas, and is true for most of the gases at least in the temperature rage distant from triple point.

    Yes loosing 40% to cool down seems a big deal, however it is not as horrid if you look at larger picture. HEV only recovers ~30% energy in regenerative braking due to multiple energy conversions mechanical->electric->chemical->electric->mechanical, and low battery charge rate limit. Hydraulic system recovers 70%, which means that even if you loose 40% due to cool down you still end up with more - 42%.
     
  2. telmo744

    telmo744 HSD fanatic

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    This hydraulic solution also brings up more rotating parts than a HEV one, doesn't it?
    Ok, then another issue is reliability, which is also driven by those extra components.

    Let me put it this way. The HEV is much simpler. It pays in a long term, because it is a lean design approach.
     
  3. cyclopathic

    cyclopathic Senior Member

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    Not sure that HEV is simpler. After all it is a parallel design, and hydraulic hybrid is series. (look at the posted video). With respect to rotating parts there is no more parts, and probably less? as you do not have transmission. Hydraulic pumps have very few moving parts where transmissions have very many.

    No disagreement here reliability is an issue, given that it is a Chrysler product!
     
  4. telmo744

    telmo744 HSD fanatic

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    I have no acess where I am now, but I will! :)
     
  5. billnchristy

    billnchristy Active Member

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    I would say other than leak repairs from vibrations and the occassional motor failure hydraulic systems are probably the most reliable mechanical systems I have ever worked on. These systems wouldn't really have a lot of mechanical shock like a hydraulic shear or similar product would have so leaks from shock loosening probably wouldn't occur.
     
  6. donee

    donee New Member

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    Yes, of course. The issue is when you compress a gas ( the gas is in the accumulator, as mechanical springs would be too heavy, and require too heavy a contraption to retain) the gas gets hot. If it does not stay hot, then the pressure reduces.
     
  7. donee

    donee New Member

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    Hi cyclo,

    HEV's are commonly quaoted to have a 30 % energy regeneration efficiency. The Prius has a 80 % plus regeneration efficiency, however. Its been measured. This is thanks to the voltage doubler circuit in the Prius inverter.

    But, if yout try to use that electricity for a high load application, like re accelerating up to speed as fast as the EV switched Prius will let you, the Prius efficiency of reuse (efficiency of regeneration times the efficiency of accelleartion ) is in the mid 40's %. Now if you use the electricity for a low load application, there is allot less waste in the battery and interconnect resistances. How good it can be is not been measured to my knowledge.

    The Hydraulic Hybrid can easily have 300 HP hydraulic motors, hydraulic lines and switches. The Accumulator wont be 300 HP, but with those other things being so powerful, yet small and light weight for that power, the efficiency of acceleration at 100 hp is very good.
     
  8. cyclopathic

    cyclopathic Senior Member

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    Not sure how it works.. NiMH batteries are said to have 66% charge/discharge efficiency.

    yes! problem with Gen III Prius is the battery charge/discharge rate. The electric motor is rated at 80HP, but the battery only at 36HP short-term, then it drops to 28.. it is a bottleneck! To maximize electric you have to drive at lower speeds and lengthen braking, which is not always possible in rush hour traffic. As is some of the benefits are lost.

    It is easier get hydraulic accumulator to produce 300HP power-wise (you need thicker lines), but total capacity will not be 300Kw/h, for sure. Taking into consideration additional weight of bigger vehicle high charge/discharge rates are must.

    Given this Hydraulic could be more efficient, and given that the most expensive part of HEV is battery cheaper as well.
     
  9. wwest40

    wwest40 Member

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    Hydraulics are about torque, not, NEVER, speed.
     
  10. wwest40

    wwest40 Member

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    Passenger car hydraulic motor "circuit" design implementations, providing motion, braking, and braking/"regeneration" are not likely to be inexpensive.
     
  11. cyclopathic

    cyclopathic Senior Member

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    the high pressure tank is cheaper then battery per kW/h, the rest will be a wash with HEV.. probably more expensive in beginning.

    Toyota is quoted with 1200$ per kW/h costs if you include all required engineering..
     
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