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Hyundai Uni Wheel electric drive system could revolutionize EV design

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Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#151

Post by bluGill »

Justsignedup wrote: post #109

A question to someone who understands the physics involved here... Does this benefit ICE cars as well? Is this a generally good tech that reduces weight / space / cost for cars in general?

Not really. You can use this on an ICE, but this really is useful (compared to a CV joint) when you have very short axles. On a ICE the axle needs to cross the entire width of the car anyway in some form, so you may as well use a CV joint. With an EV they want to use 4 small motors as close to each wheel as possible and thus free up space in the middle of the car where the axle used to go. A CV joint has a longer minimum length axle compared to this, so the motor has to go that much closer to the middle. When they use this they get useful space in the middle of the car (between the motors) that can be used for something else.

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#152

Post by esaym »

mulmen wrote: post #48

How do they keep this clean? A CV boot is compact, flexible, and fixed to the shaft. What kind of dust shield can cover the big vertical gap and handle a spinning shaft?

Yea I don't see how this will work. Just a little bit of sand or water in there and it is a goner.

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#153

Post by bluGill »

Justsignedup wrote: post #115
ChoGGi wrote: post #112

Earlier quoted context omitted.

Probably not, this is using four motors that are close to each wheel. ICE cars route energy from a central motor.

can this not use a single center motor with a shaft, just replacing the current structures? It won't be that big savings as it is in electric vehicles, but it could reduce some complexity and unify architecture of electric and ICE?

If you have a single central motor and shaft, then existing CV joints work just fine. This is useful when you want to have a separate motor for each wheel, because it lets you put those motors closer to the wheel. There is then space in the middle (where the shafts went with the single central engine/motor) that can be used for something else not related to the drive train.

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#154

Post by bluGill »

redandblack wrote: post #108

Will competitive racing adopt this? Assuming they seek out every advantage. Maybe their adoption will move this further to consumer space

(Assuming the max speed issues the other post mention are resolved!).

For a regular car this is useful because the space all the shafts taking power from the ICE to the wheels can be used for something else. For a race car there is plenty of space for those shafts and you don't have anything else to put into that space if you could. This the reason this was developed doesn't apply to race cars.

Of course for race cars they are concerned about weight and performance. Not having those shafts may be better for weight and thus worth it (assuming a EV race care), or it might not make a difference. This might have some other advantage in racing applications that the designers haven't even realized yet.

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#155

Post by bluGill »

ChumpGPT wrote: post #36
kelseyfrog wrote: post #32

Disappointed that they didn't explain how steering works. Seems like a major oversight.

A very simple and incomplete explanation. You have an electrical or hydraulic steering rack that spans your vehicle just behind the wheels behind your engine and close to the bottom. It connects to each wheel with a tie rod that has a ball joint on the end (not to be confused with your actual ball joints that are part of your control arms). When you turn your steering wheel it moves the tie rods to steer the car. Ste…

>Steering doesn't really have anything to do with the CV Joints or power to your wheels

When you turn the wheels the axles need to flex somehow around that rotation. This is one of the things CV joints do well: they can handle not just moving up and down, but also the wheel turning left/right. This thing is a bunch of gears and seems to handle only wheels moving up and down and not turning.

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#156

Post by bluGill »

estiaan wrote: post #45
ChumpGPT wrote: post #37

Earlier quoted context omitted.

An ice could use this but there is no real purpose. The whole goal was to make the electric motor smaller and closure to each wheel so there is more room for other things.

Yeah fair, though ICE cars also benefit from more space. Maybe I’m just salty because I had to watch 10 minutes of their video just for a clip that was about 1s long that actually shows what it is instantly, they should have lead with that…

An ICE still needs all the shafts connecting the wheel to the engine.

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#157

Post by bluGill »

JoeAltmaier wrote: post #85
trabant00 wrote: post #49

Unsprung weight is a clear disadvantage to the solution. It will significantly affect ride quality, no way around that. Those planetary wheels look more fragile than the traditional solution. You also need to keep that entire thing closed and lubed as well and even so it looks like added friction, wear and a more expensive repair job when it goes bad. All that being said it could be a good niche solution. A small cit…

At least they are nine identical gears? So just keep a barrel of them handy!

I expect the bearings wear out before the gears. So just replace the whole thing. Then rebuild it with new gears and bearings later.

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#158

Post by aidenn0 »

nabilhat wrote: post #51

Worth noting, placement at the wheel is somewhat arbitrary. There's nothing to prevent this contraption from working the other way around and being mounted at the chassis instead, aside from squeezing out every bit of space optimization. Axle support would be a concern either way. Controlling deflection of the drive axle adds a structural requirement, certainly a well supported bearing close to this device. The gears…

> Worth noting, placement at the wheel is somewhat arbitrary

You're suggesting placing the ring-gear in the chassis and running the axle to the wheel? That would involve two reduction gearsets in the chassis instead of the current "one plus a CV gear," which kind of defeats the purpose of reducing chassis space usage.

> The gears will be turning at a large multiple of wheel speed, so will require roller bearings except for low power and speed use: a radial and thrust bearing for each end of each gear, or 22 of each per wheel. Increasing torque also increases the level of thrust support required for the moving gear carriers handling all of those helical gears.

I imagine the final product would use herringbone gears, since the large number of thrust bearings would all add to unsprung weight.

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#159

Post by mannykannot »

My first question, on seeing a picture of the drive, was how this allowed the wheel to be turned for steering - this is, after all, the difficult part of driving the front wheels (if you are not using an in-hub motor) and is why a CV joint, and not just any universal joint, is needed (when turning sharply, the wheel axis is nowhere near parallel to the motor axis.) Neither the article nor the video mentioned steering, however, and neither did the video demonstrate it, despite showing an all-wheel drive installation. It even has an animation of vehicles going around a curve with all the wheels resolutely pointing straight ahead!

Re: Hyundai Uni Wheel electric drive system could revolutionize EV design

#160

Post by lstodd »

benj111 wrote: post #133
consp wrote: post #92

Earlier quoted context omitted.

> The standard response to that is a hand wavey "unsprung mass". But has it actually been tried and shown to be an issue? Afaik with high performance motors, if you want optimal performance and space efficiency you take the unsprung mass for granted and move everything in wheel and try to reduce the mass as much as possible. As a bonus you do not need joints, just a planetary gear system.

Why only high performance though. A motor per wheel simplifies everything. No diff, no CV joints, you don't need this, just a simple planetary gearbox. You gain space, lower manufacturing costs (theoretically, assuming multiple motors doesn't offset the other cost reductions, although as you could base a 2wd and 4wd high performance version on the same motor, that's an even harder case to make).

Everyone says "unsprung mass" but you also have to provide cooling without ingesting all the dirt and water off the road. It's not that simple.
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