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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

#161

Post by atomicUpdate »

mannykannot wrote: post #159

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…

It also (conveniently) ignores that a wheel's camber changes when it moves up and down, due to suspension geometry. It's certainly an interesting idea for sure, and any efficiency improvements here could help ICE vehicles as well. There's likely a reason these are just renders in a video though.

Hopefully they are able to work out these details, and eventually provide a real physical demonstration of these use-cases.

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

#162

Post by Descon »

atomicUpdate wrote: post #161
mannykannot wrote: post #159

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…

It also (conveniently) ignores that a wheel's camber changes when it moves up and down, due to suspension geometry. It's certainly an interesting idea for sure, and any efficiency improvements here could help ICE vehicles as well. There's likely a reason these are just renders in a video though. Hopefully they are able to work out these details, and eventually provide a real physical demonstration of these use-cases.

I just assumed that the drive shaft between the motor and their uni wheel system would have a universal joint in it that would solve both of these issues, would it not? https://en.m.wikipedia.org/wiki/Universal_joint

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

#163

Post by atomicUpdate »

hooby wrote: post #47

The thing I see not mentioned in the article/video, is how the wheels can tilt/turn/angle - without needing a CV joint again. The designs seems to cover all the motion of the wheel in the suspension - but I don't see how this could accommodate steering. Is this for back wheel drive only? Curiously the animations shown in the video, show the uni wheel used in the front of a front wheel drive car - but without ever sho…

> The designs seems to cover all the motion of the wheel in the suspension - but I don't see how this could accommodate steering.

It actually doesn't. A wheel's camber changes as it moves up and down, which is why race cars typically have negative camber when going straight, so the tire's entire contact patch is used when going around a turn, which compresses the suspension of the outside wheel.

This design doesn't appear to handle this case at all. I'm not sure how a traditional suspension setup could be modified only move a wheel up and down, without any change in the camber, considering the fixed attach points of the various control arms.

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

#164

Post by jacquesm »

bluGill wrote: post #146
jacquesm wrote: post #106

Earlier quoted context omitted.

Interesting, I wonder what the technical reasons were for the change. It has gone this way with pretty much every hub motor concept that I've seen so far, either they don't make it of the drawing board, or they end up abandoned at the prototyping stage. The GP had me wondering if someone had actually managed to conquer it but alas that doesn't seem to be the case. It's a neat little car though, reminds of the Daihats…

unsprung weight is what every engineer who looks at a hub motor will think. The less of that the better. Engineers would love to move the brakes off the wheel (there are safety reasons not to, but it would make the car handle notably better if you did)

Citroen DS/ID had that, SM as well. CX and XM did not.

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

#165

Post by acdha »

estiaan wrote: post #39
pornel wrote: post #9

Earlier quoted context omitted.

Optimistically, we could have smaller cars without compromising on cabin space or storage. …except when large SUVs are bought as a status symbol, or the race to drive the biggest tank on the road in defense from the other tanks or the road.

I actually suspect part of the reason people keep buying larger cars is because larger cars are safer and sometimes get better safety scores because in a two vehicle collision a heavier vehicle will experience less acceleration in the crash. Also more space to absorb the impact, increasing the time over which the acceleration happens. This genuinely makes heavier and larger cars safer if they are designed properly an…

Also they’re worse for everything else: the poor handling, especially with overpowering, means you’re more likely to get in a crash, etc. Manufacturers have spent billions making them less likely to lose control, roll over, etc. but the physics are unforgiving.

Drivers discount that because they like to think that those are things they control and just won’t do, but every year some fraction of people will hit ice, be distracted or angry, etc.

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

#168

Post by HeyLaughingBoy »

robocat wrote: post #61
seltzered_ wrote: post #18

FWIW, there was recently a now-defunct car company (Lordstown motors) that utilized an in-wheel motor from the company Elaphe ( https://in-wheel.com/en/technology/#in-wheel-motor-technolog... ) I think the tradeoff is between more flexibility & fewer parts (no cv joints) but possibly more rolling resistance. But watch the video, this uni-wheel thing is different. It isnt an in-wheel motor, more of a cv-joint alternat…

I'll be interested to see if the Elaphe in-wheel motors are designed into a high ground clearance 4WD. The site says added weight 25-65kg but maybe that is two motors for 2WD? A grunty 4WD tyre like a 33 inch (33/12.50R20) might weigh 33kg per tyre (not sure if rim weight), so the additional unsprung weight for the motor is comparatively reasonable per wheel? In-wheel would allow the suspension to be designed for muc…

Pretty sure I measured a 33" BF Goodrich MT (mud traction) tire on an aluminum 15x8 wheel at 93lbs. However, it was about 25 years ago so memory's probably a bit fuzzy.

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

#169

Post by riversflow »

bluGill wrote: post #146
jacquesm wrote: post #106

Earlier quoted context omitted.

Interesting, I wonder what the technical reasons were for the change. It has gone this way with pretty much every hub motor concept that I've seen so far, either they don't make it of the drawing board, or they end up abandoned at the prototyping stage. The GP had me wondering if someone had actually managed to conquer it but alas that doesn't seem to be the case. It's a neat little car though, reminds of the Daihats…

unsprung weight is what every engineer who looks at a hub motor will think. The less of that the better. Engineers would love to move the brakes off the wheel (there are safety reasons not to, but it would make the car handle notably better if you did)

Don't even need to be an engineer just go ride some nice bikes, it is an amazing and very tangible lesson in the cost of unsprung weight.

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

#170

Post by audunw »

hooby wrote: post #74
jillesvangurp wrote: post #71

Earlier quoted context omitted.

Probably a combination of having some way to rotate wheel + motor around some axis and the ability to simply vary the motor speeds on each wheel independently.

But then you need empty space around the motor, so that it can rotate there. That somehow seems a weird choice for a device that's all about improving space efficiency.

You can see the motors turning in some empty space in the video yes. But it’s mostly in the space that would be taken up by the CV joint.

Just look closer at the animations in the video if you want to see how the space is being used

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