Toyota eCVT vs. Ford HF35 transmission

Discussion in 'Ford/Lincoln Hybrids and EVs' started by srfndoc, Jun 12, 2013.

  1. srfndoc

    srfndoc Junior Member

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    While researching what hybrid car to purchase I did a lot of reading on the eCVT in
    the Prius. It's a remarkable piece of technology and was a big reason I purchased the Prius v
    over other vehicles. One of those vehicles I passed on was the Ford Cmax Hybrid but what
    is interesting is how similar Ford's new transmission is (HF35) to Toyota's eCVT. They are so
    similar in fact that it seems Ford may have just copied it. Did Toyota cross license this technology
    to Ford or is it just a case of Ford seeing something that works and copying it?

    Ford's HF35 explained:

    [​IMG]


    Toyota's eCVT:

    [​IMG]


    Prior to 2013, Ford had used an Aisin sourced transmission in their hybrids which was not
    nearly as good. Is there anything in the HF35 that Ford improved upon compared to the eCVT
    in the Prius?

    BTW, for anyone that wants to learn how these work, these site was a great resource:

    Toyota Prius - Power Split Device
     
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  2. jhinsc

    jhinsc Senior Member

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    Maybe I'm wrong, but I thought Ford licensed the hybrid technology from Toyota for their previous Fusion Hybrid and Escape Hybrid. I believe Ford's current hybrids are their own developed hardware.
     
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  3. srfndoc

    srfndoc Junior Member

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    The hybrid transmission in the previous generation Fusion was sourced from Aisin (not sure about the rest of the
    tech). Ford did develop the HF35 on their own but when you look at it, it looks like a complete copy of the Toyota eCVT.
     
  4. rjparker

    rjparker Senior Member

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    The way I understand it, Toyota has the patents on the system and sold Ford rights to develop within the scope of their patents. Ford always claimed they developed their own hardware and software and did not simply directly copy Toyota design. But Ford does acknowledge paying the rights.
     
  5. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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  6. bisco

    bisco cookie crumbler

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    toyota traded to ford for ford patents way back in the day. ford has made their own improvements since then. not enough to catch the prius. (unless part of the agreement was to never produce a vehicle that out priused the prius;) )
     
  7. Trollbait

    Trollbait It's a D&D thing

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    Ford developed their system independently, but Toyota was first to market/file patents. There was 20% to 25% of the patents Toyota had on their system that Ford might be infringing on. Rather than pay the cost of going to court, both sides reached an agreement. All we know about that agreement is that involved patent swapping.

    Both of them ended up paying Paice by some route.

    The latest generation systems are different enough not to require an agreement, or are covered by the first one.
     
  8. bisco

    bisco cookie crumbler

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    i don't think ford developed their system in a vacuum, if they didn't have an agreement with toyota up front, they must have copied it, hoping to change it enough not to infringe. unsuccessfully.
     
  9. usbseawolf2000

    usbseawolf2000 HSD PhD

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    The main difference is, Toyota eCVT is better for packaging and possibly lower weight. ICE, MG1, PSD, SRU and MG2 are on the same shaft. You can put a rod though all of them.

    Ford's HF35 has MG1, PSD and ICE on one shaft. MG2 is on separate shaft with the speed reduction gear (SRU) in the middle shaft.

    The diagram OP posted for eCVT is the older design for Gen2 with the chain. Gen3 removed the chain and reduced one shaft. This is how Gen2 (left) and Gen3 (right) compares.

    [​IMG]
     
  10. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Ford claimed their hybrid development started around at the same as Prius Gen1 (1997?). However, their first hybrid (Escape) came out in 2005. By then, Toyota has already released Gen2 Prius.

    From what I recall reading, Ford was having difficulty with the control logics and cross-licensed Toyota's Gen1 Prius control logic. Ford also used the same supplier for the hybrid transaxle. Similarities where there. Escape hybrid had belt driven A/C, like Gen1 Prius. The EV speed was low like Gen1 Prius. The generator didn't spin as fast as Gen2 Prius, etc. All traits were obviously Gen1 eCVT.

    HF35 is Ford's in-house design. The control logics are totally different which is why we are seeing the discrepancy with the real-world and EPA numbers.
     
  11. srfndoc

    srfndoc Junior Member

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    That's great info, thanks for posting it. So it looks like with the Gen3, Toyota distanced themselves again from Ford by making it lighter and simplifying the design (no chain). The whole idea of the PSD is pretty amazing and really makes this thing seem pretty elegant.
     
  12. drinnovation

    drinnovation EREV for EVER!

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    Actually the core of the current designs dates back to the early 1970s and the work og George Gelb and others at TRW automative.

    C-Max Energi: George Gelb, Planetary Gear, Hybrid Drive and Ford

    A nice discussion of the differences in designs can be found at
    http://groups.engin.umd.umich.edu/vi/w4_workshops/Miller_W04.pdf


    Toyota did make some nice advances, but the similarities on what ford had developed and what toyota had are because both started with the EMT design from TRW, after the patents on that system had expired.
     
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  13. srfndoc

    srfndoc Junior Member

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    Great information, who knew we had this tech all along and squandered it.
     
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  14. Jeff N

    Jeff N The answer is 0042

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    GM has the first U.S. patent, 5888588, (filed in February 1995) which closely describes the design used in the Toyota and Ford hybrid transmissions. As far as I know, GM has never been sued or paid Paice Inc. for hybrid patent infringement unlike Toyota and Ford.

    See: Does GM REALLY want to phase out the Volt? | Page 9 | PriusChat
     
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  15. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Bolded the important part. Both the eCVT and HF35 have the inverted input and output shaft drive from the original TRW design.

    I don't think Toyota claimed they invented hybrids. They did claim of the first mass-produced commercial hybrid, which was the Prius.
     
  16. Drdiesel

    Drdiesel Active Member

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    The FORD trans is a better design. The FORD trans allows the Energi to run 85 mph
    without the need to run the ICE. Ford and Toyota have shared and cross patented design
    for their respective transmissions. Toyota is not the designer of the CVT. While Toyota
    simplified it's design for lighter weight and smaller packaging (as in the C) it's not
    capable of the higher EV speed. My Energi MG2 is rated @ 118 horsepower. It's a very
    robust unit and works like a charm. Running EV off freeway hills at 65 to 70 mph is
    something all Hybrids should be able to do, IMO. Take a test drive and you'll be enlightened.
     
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  17. acdii

    acdii Active Member

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    It is probably the coolest thing cruising at 80 MPH on electric alone in such a big car as the Fusion. The latest update allows my HyTi to run 85 on EV like the Energi.
     
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  18. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Do you know how fast MG1 spins at 85 mph with ICE off?
     
  19. Drdiesel

    Drdiesel Active Member

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    No. The C-Max Energi has an external trans pump and doesn't require the ICE to run to lubricate
    the trans. I don't think MG1 runs at all in EV mode. MG2 is on a separate shaft and it's driving
    the wheels. Why would they run MG1 during EV operation ? It would be counter productive.
    MG1 is connected though a planetary gear with the ICE. If the ICE is off, so to should be MG1,
    unless it's during regen. That should be the job of the planetary gear. No ICE on regen either.

    The HF-35 is electronically controlled, unlike the Prius version. It's all mechanical with MG1, MG2
    and the ICE on one common assembly.

    I never plan on pushing EV to 85 mph. I do like rolling of the hills on the freeway at 65 to 75
    in EV without spinning the ICE :cool: The 118 bhp/177 lbf, HF-35 is a beastly CVTe. The added
    ATF pump just makes it that much nicer too!

    We even have an AUX coolant pump/heater for the HVAC system.
    No need to run the ICE to deliver heat to the cabin.

    The Downhill Assist is pretty amazing too.
    I was able to regen my EV battery back to 28 miles using it on a decent sized
    hill near Carmel Valley. I think I was able to capture a total of 6 or 7 miles in a short distance.

    [​IMG]
     
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  20. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Because that's how planetary gearset works. MG2 may be on different shaft but it is still connected to the ring gear of PSD (through reduction gears).

    The only difference in Gen3 Prius is, the reduction gears and MG2 are on the same shaft as ICE and MG1. They are elegantly packaged. The genius part is using a 2nd set of PSD as "reduction gear" to eliminate 2nd shaft.

    If MG2 is turning and ICE is stationary, MG1 must be turning as well. The question is how fast at 85 mph.

    The reason I asked was because the 2014 model supposed to be geared differently. Knowing the current MG1 speed would allow us to compare with the next year model.
     
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