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2016 Prius PDF Presentations - Chief Engineer & Hybrid Engineer

Discussion in 'Gen 4 Prius Main Forum' started by Danny, Oct 13, 2015.

  1. giora

    giora Senior Member

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    Toyota has added a new feature to enhance the driving experience when Power mode is selected. An adaptive system continuously monitors the acceleration pattern and lateral G-force readings to determine if the driver is adopting a more enthusiastic driving style. This system will then adapt and implement a sportier acceleration and deceleration.

    To improve brake feel and control while reducing noise reduction, the all-new Prius utilizes a newly-developed active hydraulic booster for its regenerative brakes.

    Under the Hood of the All-new Toyota Prius | TOYOTA Global Newsroom
     
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  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Higher engine stop speed.

    Does this mean that MG2 is capable of a higher rpm so the limit of engine-off is higher than 70km/h? (Gen 2 was 65km/h). That's great.
     
  3. royrose

    royrose Senior Member

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    That does make sense. I must admit that I didn't understand that there was a second planetary gear. So now I'd like to know what that planetary gear was doing and how it can be replaced by a parallel gear.
     
  4. giora

    giora Senior Member

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    See this post.
    The reduction gear he is talking about is a second planetary set, working inside the same gear ring, to this set MG2 is connected in Gen 3. Now replaced by helical set.
     
  5. Tideland Prius

    Tideland Prius Moderator of the North
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    Hopefully the video starts at 13:00 mins. Watch until 15:30 for the description of the reduction gear. If you want a bit more details as to what it does, continue watching until 17:06.
     
  6. DFGeneer

    DFGeneer Junior Member

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    I guess it works in the same way as the planetary gearset - the sun gear is the same, the planet gearset is now a single cog and the ring gear is another cog. The improved efficiency would come from the reduced surface of friction.
    Another advantage is the more compact packaging.
    A disadvantage would be the additional stress on the housing that the multi-axis design will put.
     
  7. royrose

    royrose Senior Member

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    Actually I watched the entire video. Very interesting. So, the second planetary gear set, which was seen as an advance over gen 1 & 2, is now being abandoned for a simpler and lighter reduction gear. The primary planetary set remains.
     
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  8. Tideland Prius

    Tideland Prius Moderator of the North
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    It's a good video and I hope they keep it up there (or archive it somewhere). It's simple enough to understand and of course having the actual pieces there for illustration helps.
     
  9. our1vue

    our1vue Member

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    In the Koji Toyoshima presentation, page 29, it looks like they are talking about a change to the Prius seat. Not sure what
    part of the seat (or the person) they are showing. I wonder if they changed the pitch of the seat to stop you from feeling
    like you are tilted back.
     
  10. bisco

    bisco cookie crumbler

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    someone mentioned that they are much more comfortable for long trips.
     
  11. royrose

    royrose Senior Member

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    From the Japanese press release:

    "In order to minimize discomfort during long drives, Toyota has totally redesigned the Prius' seats. In the front seats, improvements to frames and cushion bolstering have enhanced comfort while saving weight and space, providing a 'snug' fit and chiropractic control, while the seatback springs have been moved rearward for optimal occupant posture. As a result, pressure on the lower part of the pelvis is reduced and dissipated broadly, thereby alleviating stress on the lower back and muscles."
     
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  12. Lee Jay

    Lee Jay Senior Member

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    Translating the English version of the Japanese into American Yiddish, there's more cush for your tush.
     
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  13. giora

    giora Senior Member

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    Yes, up to 110 km/h. This was mentioned in a press conference in Japan.

    Also, it seems that they have improved cabin warm-up speed in a cold day.
    See this post
     
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  14. Tideland Prius

    Tideland Prius Moderator of the North
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    Wow. That's impressive. I wonder if that's a hint to the possible 110km/h engine off top speed of the PiP? Current one is 100km/h, so it's a 10% improvement in top speed.
     
  15. giora

    giora Senior Member

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    Comparing to EU PiP limit (85 km/h) is even more impressive.
    What do you think of the possible improvement in cabin warm-up in a cold day?
    Not a big issue here, but for you in the cold...should be:)
     
  16. awallin

    awallin New Member

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    So on page 9 of the Fushiki presentation:
    top left motor is MG1 with the power-split as usual, ICE is coupled to the shaft going right?
    bottom left is MG2 with the new gearing, and the blue gear goes to the wheels?
     
  17. giora

    giora Senior Member

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    On this schematic - yes and yes.
     
  18. Tideland Prius

    Tideland Prius Moderator of the North
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    It's important because it means the engine can shut off earlier and therefore close the gap between winter and summer fuel mileage. The Gen 2 takes a much bigger hit on mpg in the winter than the Gen 3 because it requires you to come to a complete stop before it'll do some checks and shut the engine off. If you never stop at a traffic light or if you have stop signs (so you don't stop long enough for the system to complete the checks), then your engine will keep running until the condition is met so it acts like a regular car. In the Gen 3, the ECU is able to do its checks on the fly so the engine can shut off even if the car is in motion and that's important. In addition, the Gen 3 ECO mode has a lower temperature threshold for the engine to shut off. I've had the engine shut off in -10°C after 5km with the heater running (albeit the auto A/C temp is set at 20.5°C or 21.0°C so it's running lightly). EHRS works better than the thermos coolant.

    Whatever improvements they do on the Gen 4 can only serve to faster warm the engine, faster heat the cabin and allow the engine to shut off earlier.
     
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  19. UsedToLoveCars

    UsedToLoveCars Active Member

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    so, from that first document, the salient improvements seem to be:
    • stiffer body
    • independent rear suspension
    • better sound deadening (why didn't they do this right in Gen III??)
    • more cargo room from moving the traction battery to under the rear passenger seat (probably the independent suspension helped here, too)
    What I learned from the 2nd document about the Gen III's front end during accerlation :
    • "Vehicle pitches unstably"
     
  20. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Weight. Weight saving from TNGA was spent on improving all those things plus the handling.

    Improvement in powertrain efficiency went to increase MPG.

    I think the Eco version would be tuned for highest MPG while cutting weight wherever possible.