SAE paper review

Discussion in 'Gen 4 Prius Technical Discussion' started by bwilson4web, Apr 8, 2016.

  1. bwilson4web

    bwilson4web i3 and Prime

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    Thank you!
    Here are some papers from Toyota & Aisin realated to the Prius Gen IV (the list may be incomplete):
    The New Toyota Inline 4 Cylinder 1.8L ESTEC 2ZR-FXE Gasoline Engine for Hybrid Car
    Development of the Li-ion Battery Cell for Hybrid Vehicle
    The New Generation Front Wheel Drive Hybrid System
    Development of New Hybrid Transaxle for Compact-Class Vehicles
    Development of Power Control Unit for Compact-Class Vehicle
    Efficiency Improvement in Exhaust Heat Recirculation System
    Development of Compact Electric Rear-Drive Unit
    The full texts are not online yet, but most of them have 5-pages free preview already.
    The new MG2 is 53kW/163Nm/17000rpm MAX (Gen III: 60kW/207Nm/13500rpm MAX).
    But I haven't seen the numbers for MG1.

    The $25, papers are available as of April 5 and I've bought:

    The New Generation Front Wheel Drive Hybrid System (SAE 2016-01-1167)

    As a summary, this is a good introduction and overview of the changes. It touches on the technical changes without going down the rabbit hole:
    • Transaxle - higher MG2 speed, 13500 rpm to 170000 rpm, reduces weight and improves efficiency. New stator winding technique and rotor reduced mass and improved power.
    • Power Control Unit - improved cooling and a "Super Body Layer" IGBT reduces size and improves efficiency. The DC/DC converter for the 12V power supply is smaller with increased output voltage range.
    • Battery - better packaging but not a lot of technical details.
    • Fuel Economy improvements sources:
      • 4% - battery
      • 28% - engine
      • 13% - transaxle
      • 16% - motor
      • 13% - power control unit (power electronics)
      • 26% - HV control laws
    • Maximum vehicle speed for engine stop, 110 km/h (68 mph)
    • Hybrid driving perception - the "rubber band" feel, the high engine rpm for maximum acceleration is reduced by using more battery power. In effect, 'sounding more normal' to reviewers who castigate the CVT.
    The New Toyota InLIne 4 Cylinder 1.8L ESTEC 2ZR-FXE Gasoline Engine for Hybrid Car (SAE 2016-01-0684)

    This provides the details hinted at in the earlier Combustion Development to Achieve Engine Thermal Efficiency of 40% for Hybrid Vehicles (SAE 2015-01-1254). The take-aways:
    • Tumble flow - improves use of higher, cooled EGR mixture and rapid combustion.
    • Intake valve timing - larger opening and slight tweaks in timing.
    • Exhaust manifold - YEA!!! They are pulling the exhaust after the catalytic converter. This significantly reduces the risk of carbon/oil blocking of the EGR valve and tube. This will improve the life of these important parts!
    • Intake manifold - better paths to even the cooled EGR ratios to the cylinders.
    • Spark plugs - adjusted to optimize ground wire and tumble fuel-air mixture and ignition.
    • Dual passage cooling - shortens warm-up yet improves cooling. Includes some baffles around cylinders and exhaust port cooling to minimize knock risk.
    • Friction reduction - bearings, new oil pump rotors, lower mass valve roller arms and spring, lower friction piston skirt coating, and lower friction cam chain.
    Efficiency Improvement in Exhaust Heat Recirculation System (SAE 2016-01-0184)

    Oh boy! Mechanical engineering talk! I loved it. I have to quote this:

    "As vehicle fuel economy has improved, waste heat represented as cooling heat loss Qw has declined. As a result, engine warm-up delays and insufficient heat stupply for cabin heaters have become an issue. TOYOTA and SANGO believe that utilizing the exhaust heat loss Qex, which is also waste heat, would be effective in improving fuel economy further."

    At last, discussing a 'topping cycle' as the future direction. In effect, the efficiency of hybrids is reaching a point where future improvements are going to address getting useful work from the exhaust heat:
    • Conventional exhaust heat recirculation
    • High-efficiency exhaust heat recirculation
    • Latent heat storage (aka., the Gen-2 thermos?)
    • Chemical heat storage
    • Thermoelectric power generation
    • Rankine cycle
    • Air-conditioner using waste heat (YEA!!!!!)
    • Stirling engine
    The rest of the paper goes into an excellent thermodynamic review of heat flows and how the new heat recovery system was developed. For example, knowing the boiling point and worst case heat flow with the valve closed, they balanced the tubes (i.e., no spot boiling); thinned the tubes for better transfer; added fins to improve heat transfer, and; reduced the amount of coolant in the tubes for faster transfers. Fully meets my mechanical engineering interest that concludes with:

    " . . . exhaust heat recirculation system are expected to become even more important technologically in order to improve fuel economy and maintain heating performance."

    Development of New Hybrid Transaxle for Compact-Class Vehicles (SAE 2016-01-1163)

    Things not discussed already:
    • stator - rectangular wires; segmentation winding; new coating to handle high voltages; welding wire segments.
    • rotor - high-speed, low-loss rotor reduced 15% saving materials yet improving performance.
    • power cables - gone! It plugs in directly.
    • cooling - ATF fluid handles cooling and goes to radiator so surface cooling is not as important.
    • differential - press-fitting
    • mechanical losses - reduced by better gears and bearings
    • dynamic ATF cooling flow - two fluid catch tanks and a fluid dam so only as much fluid is in the gears when needed to reduce stirring losses.
    There are some other papers I may buy for future reading and reporting in this thread. But for $100, these four were well worth it.

    Bob Wilson
     
    #1 bwilson4web, Apr 8, 2016
    Last edited: Apr 8, 2016
  2. pakitt

    pakitt Senior Member

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    I am really going to be curious to see how fast the Gen4 gets warmed up.
    In my experience with the Gen3, it takes about 3 mins to heat up the ICE in winter, and about 1 in summer at nice 20C-30C.
    If in winter the engine heats up in half the time :) and also it doesn't need to be so warm to heat up a cabin, that at least during my test drive, felt less cold and better insulated, not only from noise, but also therefore from external air, then my commute will see an even better fuel consumption reduction as what one could expect simply looking at MPG/EU cycle ratings.
    Not considering also all the possible savings due to a MG2 that is more capable of pushing and sail the car than what happens now in the Gen3...
    I am getting every day more excited about getting my Gen4. And I hope my Gen3, which I will miss, will go to somebody currently using a diesel or a gasoline car doing 7-9L/100km in city traffic and move to 4-5L/100km in a way cleaner Prius....!
     
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  3. RRxing

    RRxing Senior Member

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    Bob,
    I think you added a zero here. If not, then this is f**king AMAZING!!! ;)
     
  4. I'mJp

    I'mJp Active Member

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    On a cold morning I can actually hear a slight boiling noise from under the console. It must be the heat exchanger for the exhaust.
     
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  5. aurelio

    aurelio Member

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    I doubt it. It happens in many cars. Could be the climate system.

    Nexus 10 ?
     
  6. I'mJp

    I'mJp Active Member

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    Never heard it once in 5 years with the gen 3.

    Hear it never every time when I back out of the garage and it's cold enough to cause the ICE to turn on.
    I never run the climate system, for the first 10 miles, it encourages ICE, which I do not want.

    I'ts gonna drop close to freezing tonight, I'll see if I can record it tomorrow morning, although my phone microphone is monaural, and probably won't indicate direction.
     
  7. aurelio

    aurelio Member

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  8. mcdavidbranson

    mcdavidbranson New Member

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  9. E46Prius

    E46Prius Active Member

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    Thank you for that. I can't wait to see what Lexus does with this powertrain for the next CT! Probably software tweaks and further software tweaks as they did with the CT and subsequent CT facelift!
     
  10. Former Member 68813

    Former Member 68813 Senior Member

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    this is not cool. increased battery cycling just to please stupid people?

    looks like they learned from gen 3.

    this is way cool. they should also consider heat pump for heating instead of electric resistance heating.

    thanks for paying and posting, Bob.
     
  11. JamesBurke

    JamesBurke Senior Member

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    Just noticed this paper is available as a free preview this morning. Development of New Hybrid Transaxle for Compact-Class Vehicles
     
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  12. MauroneRelax

    MauroneRelax Junior Member

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    Hi bwilson4web,
    Did you find anything about the inverter's maximum boost voltage to drive MG2?
    I know p510 has 500 Volts, p410 has 650 Volts, How many Volts p610 inverter can drive?
    Thank you.
     
  13. Jeff N

    Jeff N The answer is 0042

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    I believe the answer you are seeking was stated yesterday during a technical session presentation I attended in Detroit at the SAE World Congress regarding the new IGBT in the p610's inverter. As I recall, the stated maximum voltage was 600V.

    This was shown on a presentation slide that contrasted specifications between the older inverters and the new p610 IGBT but I'm not sure if those numbers are in the actual technical paper. I recall seeing it contrasted with the 650 volt maximum of the p410. You may just have to trust my memory or try contacting the Toyota engineers who authored the paper. Or, it seems like it should be available in Toyota's service manuals. I don't recall which of the authors gave the presentation. I don't see the 600V number on the 5-page free preview of the 6 page paper:

    Development of New IGBT to Reduce Electrical Power Losses and Size of Power Control Unit for Hybrid Vehicles
     
    #13 Jeff N, Apr 6, 2017
    Last edited: Apr 6, 2017
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  14. Elektroingenieur

    Elektroingenieur Senior Member

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    In Course TIN516A Handbook: 2016 Toyota New Technology Update, Toyota writes in Section 3 – P610 Transaxle, “The maximum operating voltage has been changed from 650 volts to 600 volts allowing a more efficient and compact inverter/converter assembly.”

    In the New Car Features book (NM3200U), under Hybrid / Battery Control: Hybrid Control System: Boost Converter, Toyota writes, “The boost converter boosts the nominal voltage of DC 201.6 V*1 / DC 207.2 V*2 that is output by the HV battery to a maximum voltage of DC 600 V.” (*1 and *2 refer to models with Ni-MH and Li-ion batteries, respectively.)

    May I ask why you are interested in this voltage?
     
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  15. MauroneRelax

    MauroneRelax Junior Member

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    Thanks a lot!
    I was trying to understand some differences among p410 p510 and p610. At a given car speed p510 spins slower and MG2 has less power than p410. I though it was because of the voltage. When I realized that p610 spins faster, I expected a higher voltage of the inverter and a higher output power.. Now I see why p610 MG2 has a lower nominal power.
    Looking at the Oakridge evaluation of gen3 MY2010, I saw the motor and inverter has higher efficiency driven at 650v than lower voltages. Maybe the new inverter has other improvements to reach 17000 rpm..
     
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