Trying to understand how the Transmission works

Discussion in 'Gen 3 Prius Technical Discussion' started by Easton Hunt, Jul 15, 2018.

  1. Easton Hunt

    Easton Hunt New Member

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    First thing I think I understand it I'm more just trying to verify that I understand it if anything here is wrong please correct me, I'm mid way through getting a degree in mechanical engineering, but for what ever reason with electrical things I have a really hard time trying to grasp their concepts.

    I went through the forums and and people kept saying look into the PSD for the transmission and then you'll understand. Which trying to figure out felt like I was hitting my head into a brick wall (it was like dark souls all over again). When I woke up this morning though it finally clicked with me, MG1 (the one that isn't connected directly to the wheels) essentially behaves as a torque converter(but with magnetism rather than fluid) which can also start the ICE which will also charge the car via resistance on the motor. So if all this is correct I could drive the car without MG2, it would be super inefficient at this point but you technically could do it.

    Also from the videos I watched on how this transmission works, from what I understand is that the Toyota Highlander uses the same Hybrid transmission as the Prius? is that correct or is it just similar?

    I also read that the 2010 model MG1 motor produces 600 VAC(which is 600 volts AC I think) would that be the motor itself that produces that much or is that after going through a voltage booster?

    End of questions but if you're interested this is the why I want to know. I just recently purchased a Prius 2 months ago and I now love this thing, I used to hate them because reasons, I honestly have no idea why I disliked them other than they were green and I thought they were wimpy, little did I know. I was looking into the engineering of how the hybrid system works and I must say I really like it, from a economy stand point they're great and from a performance stand point having your max torque from start is also great. I also found out I can get the transmissions for these from junkyards for super cheap, this got me thinking what if I grab a few of these and make a box for them and stuff it under my suburban? If the Prius weighs 3000 lbs and my suburban weighs 5000lbs (probably closer to 6000 with the battery packs) It would take maybe two MG1's and MG2's to move the suburban, maybe I could use 3 of each so it could still do some towing, or if its the same as the highlanders motor I'll just have to increase what the battery can do to power it which I believe the highlander has a higher voltage battery. I also have plenty of space for some massive battery packs and rather than rely on a DC-DC booster(which I understand is a weak link for good power in the Prius) I could wire the batteries up to push 600 volts or whatever is close to the electric motors max voltage and just convert it straight to AC electricity ( I do realize this could be dangerous if I don't shield and store them properly), which could possibly eliminate the need for more than one of each motor.

    I'm pretty sure I could control the motors with some basic sensors and if I could find an open source ECM like mega-squirt or a realtime computer that I can program easily. From what I've seen in the coding of GM OBD I computers it looks similar to the G-code in CNC machines so I may be able to modify one of those to work. It definitely won't be as efficient as a Prius or Hybrid highlander(I'm not going to hire a electrical engineer to do anything too complicated), but I am pretty sure it would do better than 10 MPG.

    Yes this may seem like a crazy project idea but it would be so cool. No I'm not doing this just for good gas mileage(I know it probably wouldn't be worth it if that was the only reason). I want to do this mostly because I can, I already converted it from automatic to manual, so its not the most insane thing I've done yet. It also would be kind of funny to slap some hybrid badges on it and make peoples heads spin, especially when I explain to them how its powered by a Prius.
     
  2. FuelMiser

    FuelMiser Senior Member

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  3. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    i am going to link two videos that I find help me think of the transaxle. Both are from the gen 2 Prius, so are right in principal, but wrong in detail. Gen 3 uses gears rather than a chain, and adds step down gearing on M/G2; I think there are different voltages in Gen 3 and the location of the A/C inverter moves to the compressor.





    if you have already seen them, great, but they clearly show me what I otherwise would not understand. There are detailed videos on later Prius, but they lose some of the simplicity.
     
    #4 JimboPalmer, Jul 16, 2018
    Last edited: Jul 16, 2018
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  5. VFerdman

    VFerdman Senior Member

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    These are the best videos I have seen to make sense of the pretty tricky design. I have seen them before and was going to post them myself, but you beat me to it.

    To the OP. Please watch these videos if you want to comprehend the principle of Prius transmission. This will also give you a clue as to whether or not your idea with the truck will work. Also please, please, please consider using some punctuation in your writing. I am not a grammar nazi, but punctuation, even less than correctly used helps tremendously in making sentences easy to understand.
     
  6. padroo

    padroo Senior Member

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    To simplify the Prius transaxle it is just a highly engineered planetary gearbox. All conventional automatic transmissions I know of have one in the tail end of them and you never hear anyone having any trouble with that part of the transmission because they are reliable.
     
  7. Tideland Prius

    Tideland Prius Moderator of the North
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    @Easton Hunt If you need inspiration, Dr. Andrew Frank has already done something similar - He made a plug-in hybrid Suburban back in 2006/2007. It swaps the V8 for a 1.9 litre 4-cyl engine from a Saturn Ion.

     
  8. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Everyone has things that are simply beyond their comprehension. For me, the inner workings of the Prius transaxle falls into that category. I've tried watching the videos: they start talking about sun and planet gears, motor generator one, motor generator two, and that's when I fall asleep. I think it's a defense mechanism... :oops:

    Knowing the limits of your intelligence is smart. (y)
     
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  9. VFerdman

    VFerdman Senior Member

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    The OP is a mechanical engineering student, so hopefully it'll be easier on their system than on yours :)
     
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  10. Easton Hunt

    Easton Hunt New Member

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    The site won't let me quote for some reason, I think its because I just signed up(I should of done it two months ago when I started browsing the forum), so I am just going to stick your username in front.

    Jimbo, I actually already saw these videos which is why I was able to come to the conclusion that MG1 behaves as a torque converter. They were super helpful though, other than I was kind of distracted while the second one was playing so I missed some of it.

    FuelMiser, thats actually what I was looking for, everything I kept coming across was this flash file that kind of explained what was going on, but it seemed more focused on explaining how the ICE, MG1 and MG2 effect each other speed wise. Very few sources explain that MG1 can transfer power, in fact that source is the only source that I've seen that does so far. which confirms what I was thinking when I watched the videos.

    ETC(SS), I didn't realized that some places allowed hybrids to park in special places that is kind of interesting though. I'm in Idaho they don't care about hybrids, plus I don't think I could even get away with it, the suburban is a 1988 even if I showed them what I had done I don't think they'd believe me.

    Tideland, that is exactly what I was thinking when I was picturing how I could pull this off, Chances are though I'll swap the engine to a 2.5L 1jz-gte it still produces 280lb's of torque at 2400rpm so its close enough to the 5.7L v8 that is already in it and with electric assist from the electric motor it should have enough to get things moving like normal and I should be able to still tow with it. It would also be more efficient and lighter, which is probably why he used a 4cyl Saturn motor. Of course 30MPG is impressive, I was thinking I'd get closer to 20MPG I get 10MPG currently.

    Vferdman, Sorry about the grammar I wrote it yesterday while I was semi-awake I should have waited on posting it when I was more alert and had a chance to read through it. (granted, grammar still isn't my strong suit)

    And Thank you all, This information has been very helpful. I might be able to actually pull this off.
     
  11. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Hey....
    There's a thread on the forum where somebody......ah.....'modified' a vintage Pontiac Firebird by doing a cut-copy-paste of the drive-train with a Prius, so anything is possible.....


    I'm thinking that 135BHP would be enough to actually get an 80's suburban to move under its own power, but the thrust-to-weight ratio would make it a little unwieldy on the highway......in town...through neighborhoods....etc. ;)

    OTOH....who knows?
    You may gain a little automotive history.
    Slowest Cars 0-60 Times | 0 to 60 & Quarter Mile Specs for the Slowest Cars in the World
     
  12. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    This is my (feeble) understanding.

    29% of the engine torque twists on M/G1
    71% twists on M/G2

    This is not the power, just the twisting force. M/G1 is mostly (95% of the time?) used as a Motor, so the torque going this way produces electricity. This electricity can charge the HV Battery or power M/G2. (your torque converter)

    The 71% going towards M/G2 mostly goes on to push on the wheels mechanically. (I am ignoring heretical mode)
     
  13. tpenny67

    tpenny67 Active Member

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    It's not the 135 HP that's the problem, it's the 450 lb-ft of torque vs 6000 lbs of weight that's the problem. Compare that to a V8 with 300 lb ft of torque, which then gets doubled in the torque converter (=600 lb ft) before going through a ~3:1 ratio in the transmission, resulting in 1800 lb ft of torque going into the rear end at a dead stop, or about 4x what the Prius can generate.
     
  14. Easton Hunt

    Easton Hunt New Member

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    135BHP would be great if I wanted to good gas mileage the main downfalls of it though would be that it wouldn't be able go uphill, tow, or get out of its own way. I still want to be able to use this like a truck, I mostly got this idea because I was listening to something and they said ford was making a F-150 hybrid, which got me thinking why not do that with the suburban, I want to keep it till I die so improving it this way would save money in the long run and if I make it efficient enough my wife won't care that I own it. If i'm gonna do it though that plug in hybrid suburban from the video posted by tideland seems like the best way to go. plus 60 miles of range with no gas chances are I'd rarely need gas, which would ironically make it better than my Prius for fuel efficiency, well in town anyways, can't do much for brick aerodynamics on the highway.

    I also found that Firebird, pretty sweet idea but hacking up a Prius uni-body(bad idea for stability) and the mounting the Firebird body on it would be easier but I don't think I could pull that off with the suburban I'd need to dice up two Prius's for that.
     
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  15. VFerdman

    VFerdman Senior Member

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    60 miles of range is a great number for something as big as a Suburban. I would want to see more proof of those numbers in real life situations. But assuming it's true, it's an amazing achievement and for a second vehicle that's a special duty kind of hauler that would be a brilliant achievement.

    Good luck on your efforts and keep us informed.
     
  16. tpenny67

    tpenny67 Active Member

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    If you're going to hack up two Prii, use one drivetrain for the front axle and the other for the back axle. Now you have 4wd and double the hp and torque. :)

    It wouldn't be the first time it's been tried: BangShift.com Random Car Review: The 1980 Chevrolet "Push Me, Pull Me" Citation X-11 - BangShift.com
     
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