1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Toyota Unveils Fuel-saving Technologies for New Prius

Discussion in 'Gen 4 Prius Main Forum' started by usbseawolf2000, Oct 25, 2015.

  1. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    55,566
    38,726
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    I can relate to that. In particular going around a low speed, counterclockwise 180 deg off-ramp. It's two way, and it's a real challenge, judging lane position, oncoming traffic, etcetera: where you're heading is right in the middle of that column.
     
    MrBillTulsa likes this.
  2. giora

    giora Senior Member

    Joined:
    Aug 28, 2010
    1,966
    730
    0
    Location:
    Herzliya, Israel. Car: Euro version GLI
    Vehicle:
    2013 Prius Plug-in
    Model:
    N/A
    Could well be and easy to achieve by changing the 'gear ratio' of the planetary set.
     
  3. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    27,398
    15,524
    0
    Location:
    Huntsville AL
    Vehicle:
    2018 Tesla Model 3
    Model:
    Prime Plus
    I am looking forward to counting the gear teeth in a high resolution photo. If the 28% counter torque is something smaller, more mechanical path and less electrical path.

    Bob Wilson
     
  4. chinna

    chinna Member

    Joined:
    Apr 20, 2009
    162
    44
    15
    Location:
    Bellevue, WA USA
    Vehicle:
    2006 Prius
    As per the specs given, Gen 4 has weaker/less powerful Motors compared to Gen 3. There is no ambiguity there. But will those be weakest link? We do not know at this time.

    But as I explained above(my guess anyways), new setup may not need as much conversion from ICE -Generator- Motor as ICE has better torque spread across the RPM range and can transfer power via new mechanical transmission to wheels better. Now, motors are not doing as much work as before, but potentially can take advantage of more power from battery adding additional torque.
     
  5. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    44,933
    16,155
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    This makes sense actually. Perhaps the increased in charging rate means that Toyota can rely a bit more on battery assist for an mpg boost while tuning the 2ZR engine for more torque (it peaks at quite a lower rpm than the Gen 3) so that it can go directly to the wheels rather than through MG2.
     
  6. HGS

    HGS Member

    Joined:
    Aug 15, 2015
    307
    122
    0
    Location:
    Florida
    Vehicle:
    2013 Prius
    Model:
    Two
    Yes. Turning left at a busy intersection at night in the rain is challenging. I have to lean to the right and forward so I can see and not hit a center island curb or sign post.

    The Gen 3 "A" pillar does have a considerable blind spot.
     
  7. Jeff N

    Jeff N The answer is 0042

    Joined:
    Oct 23, 2010
    2,382
    1,304
    0
    Location:
    California, USA
    Vehicle:
    2011 Chevy Volt
    I know the gen 4 MG2 is 53 kW. Does anyone know what the gen 4 MG1 is rated at?
     
  8. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    2,997
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Yup, 2.4% to be exact -- under JC08 cycle.

    FE Gain Breakdown.png
     
  9. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    2,997
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Trying to make something out from this graph.

    Note that ICE rpm is 20-25% lower compared to Gen3 for the same vehicle speed.

    Is ICE torque much higher across the rpm spectrum? Has PSD gear ratio changed to split more ICE torque directly to wheel -- less loss in the transaxle? Probably a combination of both.

    Lower Engine Speed.png
     
    telmo744 and bwilson4web like this.
  10. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    27,398
    15,524
    0
    Location:
    Huntsville AL
    Vehicle:
    2018 Tesla Model 3
    Model:
    Prime Plus
    The new intake porting allows it to 'breath' better and accept a larger charge. I was wondering when folks would pickup on that.

    There is another chart showing the relative rpm range of the current engine and next engine and the bragging rights about how they tweaked the operating line. No, the true operating line is not shown but two of the charts give a clue about how they did it.

    Bob Wilson
     
    usbseawolf2000 likes this.
  11. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    2,997
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Lower engine noise is another side-benefit.

    Perhaps, they are drawing more from the battery and borrowing but then the ICE shuts down just as fast.

    Perhaps, the 28% improvement in regen power allowed it? But then the amount of energy gained is peanut compared to the ICE power difference.
     
  12. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    27,398
    15,524
    0
    Location:
    Huntsville AL
    Vehicle:
    2018 Tesla Model 3
    Model:
    Prime Plus
    Check Shunsuke Fushiki's presentation pages:
    • 28 - shows the reduced ICE rpm, which means a larger fuel-air charge. Also, a little longer delay in New Prius engine start.
    • 30 - shows the vehicle acceleration and those 'dotted-lines' look a lot like the engine power output at a fixed rpm but variable torque load.
    I think the charts discussing the improved intake valving were part of a presentation on the 1.0 L engine. But they are using the same words including 'straighten intake manifold.'

    Bob Wilson
     
    #92 bwilson4web, Nov 2, 2015
    Last edited: Nov 2, 2015
  13. giora

    giora Senior Member

    Joined:
    Aug 28, 2010
    1,966
    730
    0
    Location:
    Herzliya, Israel. Car: Euro version GLI
    Vehicle:
    2013 Prius Plug-in
    Model:
    N/A
    I have added two values for y axis (vehicle speed).

    EDIT See post #101 with correct numbers: 70 and 110 and the source for these.

    96554_Lower_Engine_Speed.png
     
    #93 giora, Nov 2, 2015
    Last edited: Nov 3, 2015
  14. chinna

    chinna Member

    Joined:
    Apr 20, 2009
    162
    44
    15
    Location:
    Bellevue, WA USA
    Vehicle:
    2006 Prius
    Important point made in this graph is, ICE shutdown relative to Vehicle speed and acceleration. If you see the graph, the moment vehicle starts decelerating (even slow deceleration), engine is shutdown in Gen 4 Prius, where as in Gen 3, ICE rpm is lowered(may be idle RPM). Shutdown of ICE is occurring even at 72MPH in the Gen 4, where as on Gen 3, ICE is shutdown completely only when vehicle speed 45MPH or less(assuming km/h give are correct value on the above graph).

    One thing that is not very clear here in Gen 3 is when engine shown as running at low RPM during the deceleration above 45MPH, is this DFCO mode or not?(I am guessing it is DFCO, ScanGauge would tell).

    Gen 4 shows the Engine is not running at all during the deceleration. Does it mean that, is it completely disengaged from transmission? or its RPM is brought down to zero my managing the transmission ratios and motor speeds?

    Irrespective of mechanism how ICE RPM is brought down to zero, Gen 4 has potential for easier and longer coasting distances(Hypermilers rejoice) because there are no ICE pumping losses anymore. Even in DFCO mode in Gen 3 ICE has considerable pumping losses via what we call engine braking. That is not there in Gen 4. Thought of adding another point here, this also means, more energy recovery from deceleration even without braking.

    Of Course other observation already mentioned is, lower engine RPM relative to Vehicle speed which is a results of early peak torque in the RPM range. Frictional losses are proportional to Engine RPM and pumping losses proportional to Square root of engine RPM. So here more gain by reducing the pumping losses because engine is mostly operating at lower RPM.

    All in all, I think Gen 4 will have better highway mileage in real world because of this and better Cd.
     
    #94 chinna, Nov 2, 2015
    Last edited: Nov 2, 2015
  15. bwilson4web

    bwilson4web BMW i3 and Model 3

    Joined:
    Nov 25, 2005
    27,398
    15,524
    0
    Location:
    Huntsville AL
    Vehicle:
    2018 Tesla Model 3
    Model:
    Prime Plus
    What is this term?

    Bob Wilson
     
    Mendel Leisk likes this.
  16. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    2,997
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    Deceleration Fuel Cut-Off.

    A regular Prius shuts engine down at 70 mph? Wow!

    Those upgrading from Gen2 will be in for a big surprise.
     
    Mendel Leisk and Tideland Prius like this.
  17. GasperG

    GasperG Senior Member

    Joined:
    May 13, 2011
    1,168
    598
    1
    Location:
    Slovenia
    Vehicle:
    2018 Prius
    Model:
    N/A
    I added the rpm scale, because we know when old engine must run in deceleration it runs arround 1,000 rpm


    I think the graph is a little exchagerated to prove a point, but it's obvious that new engine will use more torque and have lover rpm under acceleration. Current engine uses only around 90-110 Nm under medium acceleration it looks like new engine will be run at 120-140 Nm very early in the rpm range. This will lower engine speed for the same acceleariton by 500 to 900 rpm.

    To put it simple, it will have more grunt :)
     
    telmo744, usbseawolf2000 and giora like this.
  18. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    44,933
    16,155
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Peak torque for the Gen 4 is at 3,600rpm so that may explain the lower torque curve during the acceleration to 115km/h.
     
    usbseawolf2000 likes this.
  19. GasperG

    GasperG Senior Member

    Joined:
    May 13, 2011
    1,168
    598
    1
    Location:
    Slovenia
    Vehicle:
    2018 Prius
    Model:
    N/A
    That is true, but even Gen3 could be driven at higher torque, but it was not. It would be possible to run Gen3 engine at 120 Nm @2,000 rpm, but it was not because apparently that was not the sweet spot efficiency or maybe because of HSD restrictions/efficiency

    [​IMG]
    If transition from 2nd gen to 3rd gen was -300 rpm, then transition from 3rd gen to 4th gen will be at least -600 rpm at same load.
     
  20. usbseawolf2000

    usbseawolf2000 HSD PhD

    Joined:
    Sep 22, 2004
    14,487
    2,997
    0
    Location:
    Fort Lee, NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    A huge improvement despite staying at the same 1.8L. For Gen2 to Gen3, it was increased from 1.5L to 1.8L.