Behold The Hyundai Uni Wheel. Transportation May Never Be The Same

Air conditioning and touchscreens didn’t alter how cars drove but did revolutionize the driving experience.

Can we please make touchscreens for neccessary functionality illegal, like using phones while driving?

Can we have more mechanical posts like this?

There's 2 significant inaccuracies in the article and 1 large oversight in the official video.

1. Differentials are not one wheel drive. They can seem to drive only one wheel when spinning the wheels as one let's loose and the other stays still, but it's not driving one wheel. It's still driving both. The problem is the free wheel is spinning at twice the speed indicated on the speedometer and the other is at 0. The driveshaft puts in a certain number of turns, the wheels, together, must add up to an equal output (multiplied by the gear ratio). If the car is going straight with full traction, then they turn the same. If you floor it in snow, one is probably spinning 40% over it's share and the other 40% under. This is not unique to rwd either as fwd cars still very much have a functioning differential. To throw some numbers at it to help clarify the function, let's say the engine is asking the wheels to spin at 30rpm each in a straight line. In a left turn, the right wheel travels further and needs to spin at 35rpm while the inner spins at 25rpm. It still adds up to 60rpm, same as a straight line. Mash it in the snow and it might be 60rpm in the left and 0nin the right or 0 in the left and 60 in the left. It could be 5/55, 40/20, or any other combo as long as it totals 60.

PS: differentials are irrelevant when the wheels aren't connected to each other. Individual-motor wheels, as shown in the video, don't need a diff. The non-drive wheels in a 2-wheel drive vehicle do not have a differential on the non-drive axle.

2. Cv joints are not specific to fwd as nearly all modern rwd cars with independent rear suspensions have CV joints. I don't know of any trucks still using U-joints either since big trucks are solid axle. Cv joints function the same as U joints. The difference is C.V. joints output constant velocity whereas U-joints (what you'll see often under trucks on the driveshaft, two square C shaft ends with an X link between) have lopey output that gets worse with greater deflection angle. If you own a u-joint bit for your socket wrench, I invite you to play with it. Instead of a solid pinned X between the U ends, CVs have free-rolling balls that can roll inboard and outboard to maintain the link between the shaft's cup and the wheel's cone.

3. The article is inaccurate but the video ignores this part, so I don't fault The writer. The CV joints are said to be a poor design, yet, it ignores the part where the video reinstalls them at 4:20 and 5:10 for the front wheels. This mechanism does not allow angular deflection between the motor and hub, as it's shown, without a CV joint. Lateral displacement, yes, but not angular - as in it can't steer. This may be an overall improvement by reducing how often it needs to bend (only when steering), but it doesn't eliminate it. And even then, the rear suspension is still designed to change camber as it changes ride height. Camber is the angle of the wheel as measured top to bottom, as in what you see from looking at the wheels from the front of the car. It keeps the wheels flat on the ground as you lean the car in a corner. You may see an overloaded car's rear wheels look like /---\ as viewed from the rear or ---/ when hanging free on a lift.

Look, I'm not an engineer at Hyundai (or even a competitor) but this doesn't quite pass the sniff test. Cool idea for sure, but it smells a little like marketing is clamoring for something edgy to display. Even as displayed, the motors and original reduces were already very compact and in close proximity to the wheels compared to a normal engine. The slightly reduced footprint of this uni wheel and slightly increased friction of a bunch of additional gears makes me think this is a fractional improvement in practice rather than a revolutionary improvement.

Now thar Hyundai has patented it, it will never become popular enough to impact the market and be standardized in more vehicles or change anything, similar to the Wankel engine.

Did none of you watch the video? The article is crap, but the video explains it well.

Go back and watch the video, ya old codgers!

One thing I took from the article is they're trying to sale the idea of having MORE space in a car due to smaller transmission system. In 1 presentation, they show the idea of putting a FUCKING DOUBLE BED IN THE CAR!

I DON'T want MORE space in the SAME sized cars.

I want the SAME space but in SMALLER sized cars.

The space we have now is FINE, and the car sizes are TOO BIG.

STOP MAKING BIGGER CARS!

What a badly written article, wrongly explaining both the diff and the CV joint. That's not what they do or how they work.

https://youtu.be/Nd6C0y8xc20

Seems really cool. I will definitely not buy the first model vehicle to use this, though.

The explaination of how differentials work was painfully wrong. An I lost confidence in this author's ability to explain the topic.

The one thing they don't really talk about is how it turns. The animations show vertical movement almost exclusively. At one point in the video there is a far shot showing a car turning and it looks like they actually swivel the entire motor to keep it perpendicular to the wheel which if true is going to pretty heavily limit it's turning angle and radius.

For the lazy people out there: https://www.youtube.com/watch?v=Nd6C0y8xc20

If you're gonna go through all this trouble, why not put motors directly into the wheels? Then you can bypass the drivetrain all together and directly power the wheels.

Not a new idea, military trucks used reduction gear drives in the wheels before WWII. Edit: Portal Gears.

One downside to doing this is adding unsprung weight, which is not a good idea.

And it will still need a CV at the wheel to accommodate suspension travel.

I don't understand how they are going to keep dust and dirt out of it. The point where the drive input goes in has so much movement.

So in short, this adds suspension directly to the wheel, at the cost of higher maintenance? That's it?

I cannot think of a car company I'd trust less to do this than Hyundai/Kia.

Article made it sound like only front wheel drive exists now and that only front wheel drive cars use CV joints lol.

so the pretty much only upside compared to hub motors is less weight in the wheels, and comared to conventional drivetrain layouts there's added complexity and slight extra interior space? i mean innovation is key, but i don't quite see the upsides as much as the hyundai engineers.

Honestly I don't care at this point, I won't buy anything from Hyundai.

Permanently Deleted

This is pretty cool!

But, in the video there is a quick flash of text that went away after 1s, 120km/h max speed?

From a mechanical standpoint, the new bearing saves a nearly negligible amount of space. Splitting the motor up and moving it to the notoriously wasted wheel well space is what clears up the center of the frame. Still very cool. It's basically a single output differential, which is already quite compact. No need to split the rotation for turning since the wheels rotation will no longer be mechanically linked.

I don't get what this does or what's the benefit. There's still a cv-joint there. Otherwise the wheels can't turn

Anyone remember the Hyundai debacle where the transmission gears stripped mid-drive? Yeah..... I'm not trusting their gear-making ability (or lack thereof) with precision gears inside all of my wheels. Pass.

I was just learning about CVJ gearing the other day and was thinking cars should use it instead of fixed gear ratios. Very cool.

Setting aside all of the already observed questions in the comments already about mechanical viability, i.e. how this assemblage is supposed to steer. The elephant in the room is whether or not this is equivalently economical to produce compared to an axle with a CV joint in it, and/or if it will acceptably reliable for roadgoing vehicle use, what with having a shitload more moving parts in there.

The animation shows the geartrain assembly in an open faced housing, which if that's how it's ultimately designed is going to mean that there is now no way to keep the gears in a bath of oil or transmission fluid like is presently done in traditional transmissions and differentials. And yes, even in CV joints which are packed with grease inside their rubber sealing boots. I'll let you in on a big automotive industry secret: There's a reason current transmissions and other geartrain devices are kept suspended in oil all the time. A big one. One that has to do with your transmission not glowing red hot by the time you make it to your destination, or converting itself into glitter within the first mile.

Even setting aside lubrication concerns -- Maybe the thing is chock-a-block full of sealed ballraces or something, for all I know -- the big open slot they depict for the axle to move up and down in is just begging for a stone, a stick, a stray bolt, or any other show-stopping piece of debris from getting in there and causing you to have a very expensive day. Ditto with the gap around the edge of the sun gear, which is going to need a bitchin' huge mechanical seal on it at the minimum. If the solution is perhaps to put some kind of rubber boot over the opening that moves with the axle, it's going to have to be ridiculously flexible and remain so even throughout all kinds of temperatures and operating environments. Cars, you know, being devices quite infamous for being operated outdoors in the weather and all.

I mean, I can't imagine Hyundai's engineers haven't thought of this. But I wonder if this is one of those works-in-the-lab-and-test-track things, and they're expecting someone else to figure out the viability challenges.

There needs to be more music in the background, and the narrator needs to speak with more enthusiasm about more needless details of how smaller makes it possible to use the space for something else. /s

The concept is cool though.

I know Hyundai is Korean and all, but this presentation style where the host pretends to be demonstrating a product "uh, wait a second . . . what if we" and is speaking almost like it's a personal conversation between the two of you is giving me huge Nintendo Direct vibes when they demonstrate unreleased games and play them for you.

Is this a common sort of business/sales presentation method in SEA?

Another advantage of putting drivetrain components in the wheel is you can just swap them out easily rather than having to tear the engine bay apart. Really outstanding work!

So how does it handle potholes?

Seems like this adds more than a bit to the unsprung weight of the wheel.

BEHOLD

its pretty cool tech. replacing the CV joints is a bonus. but each tire as its own motor? eeehhh, skeptical

Does the market want tires that are this 'complex'?

also, tires take a lot of direct damage over terrain, while the rubber and shok absorbers certainly mitigate this, how many hits can this uniwheel take?

automotive standards is an interesting beast to work with. customers are going to be a bit upset every tire change when the cost trickles down.

This is cool, but wouldn’t it make any tire issue an engine issue and this way more expensive and difficult to deal with?

Mine just stopped working with brscan5. It was a fast and quiet mobile scanner with high quality output. The new one is bigger, slower and louder and runs 90% of time in some photo mode. 🙁

Neat!

Fascinating, but in the video they very quickly swipe off-screen that the top speed their new system was able to achieve was 120 kph / ~75 mph.

I imagine something like this would have to be limited to vehicles that never need to approach speeds above that on a highway, so maybe busses or indoor shipping & receiving vehicles.

That's neat, I'm looking forward to electric vehicles with the sort of modularity and space they are envisioning due to the extra space.

EV already have much smaller gearboxes, because they don't need to shift.

Now they need 4 of them, not just 1.

Such a gain in weight :-)

I don't need video(s) to understand the subject here : I just use an image search :
https://duckduckgo.com/?q=%2B"Hyundai+Uni+Wheel"&t=ofa&iar=images&iax=images&ia=images

This is a mechanical device that allows coupling of any wheels of any vehicles to any electric motor.

it is designed in such a way to permit vertical movement of the wheel without the need of such movement of the motor. So basically it is a new type of suspension.

Since it needs many gears in a row for the transit of mechanical energy it will incure an inefficiency factor.

Expected a monowheel got something about cars. Blegh.