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Discussion Starter · #3 ·
I copied the images from a thread at Wayne Gerdes' CleanMPG.com. I searched a few times in vain for Wayne's source. Maybe someone else can do better. Lot's of good info in these images and they won't last forever. A link would be great.
 

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I was poking around trying to figure out what the belt on the engine is for. Appears it is for the HSG ( Hybrid Starter Generator )..which replaces the starter/alternator and can potentially be part of the regenerative braking process.

Seems like an obvious weak point in the design. Note that the Sonata Hybrid also has a belt-driven HSG.

The Prius does not have this...similar function is all handled inside the transmission ( the PSD - power split device - is key ). A much more simple/elegant solution if you ask me.

Does anyone have more information on this? Owners, is the HSG belt maintenance interval listed in the manual?
 

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Discussion Starter · #5 · (Edited)
The power-split transmission (Toyota and Ford) has the advantage that no belt is needed to start the ICE. It is also slightly more efficient at lower speeds than Hyundai's P2 system. However, the P2 has an efficiency advantage at higher speeds because it doesn't require electrical power to hold a gear ratio as the power-split does. The power-split's main disadvantage is cost. It needs two large, expensive motors to counteract the torque of the ICE. If you want to learn more about the engineering pros and cons of each system, I suggest John German's book mentioned here. BTW, German is fairly strongly in favor of the P2 design because cost is a major impediment to public acceptance of HEVs.

The normal service and severe service maintenance schedules for the belt are outlined in the manual which is avail for download.
 

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according to the manual I have in Europe the HSG belt under normal conditions seems to be 70,000 miles, harsh conditions 40,000miles


non Europe seems to be under normal conditions seems to be as low as 40,000 miles, harsh conditions 20,000miles


very wide variation of belt life, the worst was middle east of 20,000 miles, I assume due to heat and sand
 

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The power-split transmission (Toyota and Ford) has the advantage that no belt is needed to start the ICE. It is also slightly more efficient at lower speeds than Hyundai's P2 system. However, the P2 has an efficiency advantage at higher speeds because it doesn't require electrical power to hold a gear ratio as the power-split does. The power-split's main disadvantage is cost. It needs two large, expensive motors to counteract the torque of the ICE. If you want to learn more about the engineering pros and cons of each system, I suggest John German's book mentioned here. BTW, German is fairly strongly in favor of the P2 design because cost is a major impediment to public acceptance of HEVs.

The normal service and severe service maintenance schedules for the belt are outlined in the manual which is avail for download.
Thanks for the update. Yes, I understand all of the pros/cons of Toyota's transaxle.

As for myself, I'm not really concerned about the slight cost differences..which are extremely debatable. Frankly, the costs are not too far off when you take the entire system into account.

At any rate, some good discussion here regarding P2 (Niro/Ioniq) vs Power-split (Toyota/Ford) :

2017 Kia Niro Hybrid Prototype First Drive Review

A couple quotes from the article :

"A P2 can get close to a power-split’s efficiency—about 90 percent—during city driving, and you can match them on the highway,” German continued, “but at significantly lower cost, especially with a small, high-power lithium-ion battery (way tinier than its nickel-metal hydride alternative yet powerful enough to satisfy a hybrid’s needs). The Achilles’ heel of the P2, or parallel hybrids, is bump-starting the engine. Early systems that eliminated the torque converter didn’t work well. But more sophisticated algorithms are changing things.” (For lots more, check out John’s book, “Hybrid-Powered Vehicles, 2nd Edition,” published by the SAE).

Our pal Mike Duoba, senior engineer at Argonne National Laboratory’s Advanced Powertrain Research Facility, offered a second perspective. “Hybrids are really just everyday cars with very fancy transmissions,” he said. “Transmissions convert engine shaft power to wheel axle power, but ‘fancy’ hybrid transmissions can provide additional propulsion or regen using battery energy storage. As you know, the frequently heard statement ‘The engineers picked the best design’ is really only partially true, as final decisions are also influenced by cost, past experience, and capital investment in doing lay-shaft (used in P2 hybrids) versus planetary gear (power-split hybrids) transmissions. Europe does lay-shaft transmissions, while the U.S. and Japan prefer planetary gear automatics. Analyzing what was revealed about the new Prius, Toyota is showing that if your engineers keep at it, limitations of the power-split can be engineered out and thus you get a pretty optimum system. I would be interested in driving the Niro because the advantage of using a smaller motor with a P2 design becomes a drivability disadvantage because this smaller motor has to provide all the torque needed to launch from a stop. Compared to a conventional vehicle that has a torque converter, this torque limitation was evident in the (original) Sonata HEV.”



As for me, as a buyer, I'm more concerned about reliability. It seems like Toyota wins there. The power-split device really is a proven marvel of engineering. The mechanical simplicity the Toyota transaxle is pretty amazing. I'm also quite skeptical of the long term reliability of Hyundai's system. However, I like Hyundai a lot ( we have two of them )...so I don't know what to do! :)
 

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reliability of the drive train ,due to planetary gear design of the prius system has to have it as no friction material to wear, but the way it drives is not to everyone's liking,


the big question is what is the life of the clutch plates and the cost to replace them ?


but balance that against the known failure of the Toyota NiMh battery pack at around 130-150k miles, if the LiPo pack of the Hyundai has a longer life (again the life is unknown) but with 125,000 mile warranty in the EU and unlimited mileage in the US but I suspect Hyundai have a fair margin in there with those warranties


problem is we won't know the answer to either the clutch wear or battery life until we get a number of cars over 100k miles, but an indicator may be if vehicles start having any early failures of either the DSG clutch or batteries or not
 

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the big question is what is the life of the clutch plates and the cost to replace them ?
I hope I don't find out. :)

But I am confident mainly because there is no clutch action involved when starting from a stop. That's done by the electrical motor keeping the clutch fully engaged. I would consider this as the main source of wear and the main source of annoyance with DCT transmission (the infamous shuddering feeling at low speeds)

Any gear changes later on should not put too much strain on the clutches because the engine isn't that powerful and I would assume that most people do not rev their car up to the rpm limiter.

Out of curiosity I did a quick google search and there don't seem to be widespread complaints about worn DCT clutches of any manufacturer. So let's keep the fingers crossed.
 

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the ECU and gearbox controls do try and match the speed of the engine to the speed of the input shaft of the gearbox to minimise wear, this is part of the reason for some of the changes appearing a little slow


sport mode does seem not to worry as much about matching so excessive use of sport mode could I think cause slightly more wear
 

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Discussion Starter · #11 ·
^this exactly.^ The DCT clutches are under very little stress because the electric motor is effectively a torque converter and always gets the car underway. The batteries are more of a question mark as to their longevity, but Hyundai is taking the risk of the expensive battery pack with their lifetime warranty.
 

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Good discussion here.

What about wear on other parts of the system? Primarily the HSG ( Hybrid Starter Generator ). I wonder how reliable that will be? I did a quick search on the Sonata Hybrid regarding the HSG and it does seem like it is a point of failure..broken belts and such.

So two possible points of potential wear that Toyota's Hybird Synergy Drive doesn't have :

- The Dual Clutch transmission (DSG)
- The Hybrid Starter Generator (HSG) - also frequent HSG belt replacement is required.

Anything else?

I'm also a bit concerned about Hyundai's exhaust gas recirculation (EGR) implementation. Toyota has had time to tweak their implementation. In fact, it looks to me like Toyota changed the EGR to be post-catalytic converter vs pre-converter for the Gen4 Prius. In theory this can reduce carbon deposits, etc...which can be a problem in the Gen3 Prius. I'm certainly no expert on this though.

- Source : https://priuschat.com/threads/what-causes-egr-clogs.174268/#post-2458981

It would also be nice if Hyundai would get some SAE technical papers out. It's actually quite odd that they haven't.
 

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Discussion Starter · #15 ·
Thanks for the video. I think this is one of the better ones that have been released since the Santa Barbara press conference last week. I love cutaways and naked chassis displays. This video settles the conjecture DaveAZ and I were having over the location of the US 12V battery. DaveAZ was correct that it's packaged inside the traction battery enclosure. The naked chassis display is missing the gas tank and I was hoping to get a better look at the mystery box alongside the gas tank.
 

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Good discussion here.

What about wear on other parts of the system? Primarily the HSG ( Hybrid Starter Generator ). I wonder how reliable that will be? I did a quick search on the Sonata Hybrid regarding the HSG and it does seem like it is a point of failure..broken belts and such.


snip....
we try to give honest info, not just the plus side as the car is so new it is not for everyone, there is so much new tech which is potentially unknown


BUT Hyundai have put there money where their mouth is with a good warranty which gives a level of comfort so long as we don't need to keep going back for niggles or major issues


I think everyone accepts they might get the odd niggle on such a new model, so long as it is fixed first time and you don't end up with the car off the road for long periods


the car itself is good, now we are into how good are the dealers and Hyundai with any after care issues, so far my dealer has been fantastic, but I have been providing them a lot of feedback
 

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we try to give honest info, not just the plus side as the car is so new it is not for everyone, there is so much new tech which is potentially unknown


BUT Hyundai have put there money where their mouth is with a good warranty which gives a level of comfort so long as we don't need to keep going back for niggles or major issues


I think everyone accepts they might get the odd niggle on such a new model, so long as it is fixed first time and you don't end up with the car off the road for long periods


the car itself is good, now we are into how good are the dealers and Hyundai with any after care issues, so far my dealer has been fantastic, but I have been providing them a lot of feedback

I really value the news I get from you guys about how the car is holding up.

I think we all believe in the Hyundai warranty here. I sure do as we own two Hyundai non-hybrid models ( a Sonata and Elantra GT ).

I'm also glad we can have a good civilized discussion here. When I try to discuss the Ioniq over on PriusChat..even in their 'other cars' sub-forum..I sometimes feel like the hounds have been released on me! :) I kind of expected that though...
 
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