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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

#71

Post by jillesvangurp »

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…

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.

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

#72

Post by hooby »

benj111 wrote: post #65
husam212 wrote: post #56

Earlier quoted context omitted.

Maybe the motor is supposed to turn with the wheel, that doesn't sound like a good idea.

Why not? You'd have an added complication of making the shock absorber the pivot point, and attaching the motor to the top point. Or having a separate pivot point where the motor or wheel can slide up and down. This does raise the question of why not just attach the motor straight to the wheel. The standard response to that is a hand wavey "unsprung mass". But has it actually been tried and shown to be an issue?

Well, if the motor is unsprung mass, you no longer need this contraption at all, and you can just directly connect the motor to the wheel...

So, that's probably not it.

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

#73

Post by jacquesm »

benj111 wrote: post #68
jacquesm wrote: post #38

Earlier quoted context omitted.

It is the issue for in-hub motors. Solve that one and the world will beat a path to your door and shower you with money.

Have you got a source. Everyone mentions this, but I've never come across anyone trying and failing. Motor scooters have unsprung motors, the motor is a significant proportion of the mass.

Motor scooter motors weigh a fraction of what the equivalent motor for a car would weigh, and it's exactly the problem:

The issue is that it scales poorly, unsprung weight is bad enough that on some cars the disc brakes live 'inboard' on the front wheels (older hydraulic suspension cars).

Essentially the larger the unsprung mass the bigger the hit every time the road surface irregularities cause the wheels to move relative to the vehicle body. The larger the mass the more energy gets imparted, and the more energy that gets imparted the bigger the impact and all that energy then needs to be absorbed so you'll need a stronger (and heavier) suspension system, roughly half of which is unsprung mass!, and a larger battery to compensate for the losses in the suspension which also adds weight (harder suspension -> bigger range but less comfortable ride). So it feeds back on itself and that's why it scales so poorly.

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

#74

Post by hooby »

jillesvangurp wrote: post #71
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…

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.

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

#75

Post by jacquesm »

Beijinger wrote: post #70
jacquesm wrote: post #38

Earlier quoted context omitted.

It is the issue for in-hub motors. Solve that one and the world will beat a path to your door and shower you with money.

You can buy a car powered with in-wheel motors here: We have developed the first production car to use in-wheel hub motors. https://mwmotors.cz/luka-ev/ This car maybe too, as far as I understand it. A Russian UAZ on steroids: https://www.youtube.com/watch?v=RCOf_33C1qc

815 Kg curb weight, aluminum chassis. It makes sense for a vehicle with that form factor (2 seater little sports car) but you can't really compare it with a full sized sedan, and note too that it has a tiny battery pack (22 KWh), range is 'unofficial' 300 Km and likely will be adjusted down based on weight/pack size. The four motors together are less than half the rated power of what you'd find in a more conventional (is there such a thing already?) EV. But with that light total weight it will be a zippy little car anyway (most EVs are over-powered for their weight).

Still, very impressive achievement and a nice testbed for this kind of tech, it may also make sense for motorcycles and for vehicles that are not meant for highway use.

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

#76

Post by jacquesm »

throwaw33333434 wrote: post #64
jacquesm wrote: post #38

Earlier quoted context omitted.

It is the issue for in-hub motors. Solve that one and the world will beat a path to your door and shower you with money.

The other issue is that potholes my get quite expensive.

Yes, the impact from a pothole can be substantial. Having an upset alignment is one thing, damaging the guts of an in-wheel motor is a totally different picture. But: when properly packaged and lightweight enough I think that is a secondary concern, you can design with that in mind given that it is more or less predictable from which direction and with which magnitude such an impact would happen. But every pound counts and the shocks+spring will have to be matched to the increased weight.

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

#77

Post by teamonkey »

tlb wrote: post #60

This wouldn't have worked for ICE cars, because in order to have a reasonable range of up-and-down movement the gear ratio needs to be quite high (ie, the pinion gear has to be much smaller than the ring gear). It's 6.2:1 in the article, about 2x what's appropriate for the top gear on an ICE car.

I wasn't clear why this couldn't be used on all vehicles but that makes sense, thanks.

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

#78

Post by Beijinger »

jacquesm wrote: post #75
Beijinger wrote: post #70

Earlier quoted context omitted.

You can buy a car powered with in-wheel motors here: We have developed the first production car to use in-wheel hub motors. https://mwmotors.cz/luka-ev/ This car maybe too, as far as I understand it. A Russian UAZ on steroids: https://www.youtube.com/watch?v=RCOf_33C1qc

815 Kg curb weight, aluminum chassis. It makes sense for a vehicle with that form factor (2 seater little sports car) but you can't really compare it with a full sized sedan, and note too that it has a tiny battery pack (22 KWh), range is 'unofficial' 300 Km and likely will be adjusted down based on weight/pack size. The four motors together are less than half the rated power of what you'd find in a more conventional…

What is the advantage of in-wheel motors?

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

#79

Post by jacquesm »

Beijinger wrote: post #78
jacquesm wrote: post #75

Earlier quoted context omitted.

815 Kg curb weight, aluminum chassis. It makes sense for a vehicle with that form factor (2 seater little sports car) but you can't really compare it with a full sized sedan, and note too that it has a tiny battery pack (22 KWh), range is 'unofficial' 300 Km and likely will be adjusted down based on weight/pack size. The four motors together are less than half the rated power of what you'd find in a more conventional…

What is the advantage of in-wheel motors?

That you save on a whole bunch of linkage and drive train components, four wheel drive without the associated complexity, that you can integrate the wheels, motors and brakes, cleaner airflow under the car and that the system as a whole can be lighter weight than the same package with motors near the centerline of the car, so you get somewhat better range. It also gives more space for batteries and/or more storage space. That's why manufacturers will keep trying to get this done, if they can get it to work cost effectively and without impacting that unsprung weight too much it will give them an advantage.

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

#80

Post by Beijinger »

jacquesm wrote: post #79
Beijinger wrote: post #78

Earlier quoted context omitted.

What is the advantage of in-wheel motors?

That you save on a whole bunch of linkage and drive train components, four wheel drive without the associated complexity, that you can integrate the wheels, motors and brakes, cleaner airflow under the car and that the system as a whole can be lighter weight than the same package with motors near the centerline of the car, so you get somewhat better range. It also gives more space for batteries and/or more storage sp…

"cleaner airflow under the car"?

Why should the airflow be cleaner?

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