14 ms·
Hyundai Uni Wheel electric drive system could revolutionize EV design
- mulmen 3y agoHow 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?
- esaym 3y agoYea I don't see how this will work. Just a little bit of sand or water in there and it is a goner.
- manonthewall 3y ago[dead]
- deleted 3y ago[deleted]
- thedrbrian 3y agoSo we could have a slightly bigger inside to the usual EV SUV. woo
- LargeWu 3y agoA smaller battery would imply fewer resources required per vehicle, which will be important as demand for batteries increases.
- pornel 3y agoOptimistically, 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.
- estiaan 3y agoI 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 and maintain the same braking performance, which is totally possible. However the issue is that a larger car is only a safety advantage if your car is large compared to other cars on the road, so if everyone else also buys heavier cars no one wins and pedestrians, the environment and so on all lose.
- acdha 3y agoAlso 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.
- neuralRiot 3y agoBigger inside than modern SUVs? What does people transport? How many people ride regularly? What size are people?
- 4death4 3y agoTwo adults, two kids in car seats, and a dog. With that, even a mid-size SUV has no space for cargo. If you drive a sedan, you have to leave the dog at home.
- neuralRiot 3y agoMaybe if they don’t put a foot-wide console in the middle there would be more space for people and cargo.
- IlPeach 3y agoThat's why station wagons and vans exist. SUVs do not provide more space, they just occupy more (on top of being dangerous to others)
- nradov 3y agoLarge station wagons no longer exist in the US market. The biggest one remaining is probably the Volvo V90, which is a nice car but can barely fit 5 people, and if you put a dog in the back then there's no room for cargo. It's also too expensive for most families; several large SUVs are actually cheaper. Minivans are a good option for some families. But they suck for towing trailers, and the ground clearance is terrible if you ever have to drive on a dirt road.
- doubleg72 3y agoYeah really, like I’m gonna drive a minivan or station wagon out in the woods, or drive my four wheeler into the back when I need to take it somewhere.
- 3y ago
- partiallypro 3y agoI think more importantly is that you can add more battery capacity, making EVs much more competitive with gas vehicles.
- deleted 3y ago[deleted]
- igor47 3y agoAs a drivetrain nerd, this is awesome!
- mech987987 3y agoMore mass inside the wheel increases unsprung weight and worsens some ride/suspension characteristics of a vehicle- that being said the tradeoff might not be too bad in this case.
- pornel 3y agoIt’s just reduction gears, not the motor, so hopefully it can be made light enough. Shame that their promo didn’t say a word about the mass. Quad-motor all-wheel torque vectoring sounds awesome tho.
- SkyPuncher 3y agoMy semi-educated guess is the heavier weight of the vehicle means the wheels can bear a bit more weight.
- sam_goody 3y agoIs there some way that this or similar can be copied by all automakers, or is this all patented by Kia/Hyundai in such a way that most improvements are completely locked in?
- lovemenot 3y agoAssuming the technology has actual value, Kia/Hyundai would likely be more incentivised to license it to other vehicle-makers, than to keep an exclusive license for themselves.
- metamet 3y agoEspecially considering how their name and brand are in the dumpster, and likely won't recover. Their cars will be targeted for break ins for a long time to come due to how viral the vulnerability is, regardless of whether or not the model is actually susceptible to it.
- almostnormal 3y agoManufacturers often buy gearboxes from suppliers instead of producing them. Hyundai does have Hyundai Transys as separate company for transmissions, and they would likely be happy to sell complete devices, not just licenses. https://en.m.wikipedia.org/wiki/List_of_Hyundai_transmissions https://en.m.wikipedia.org/wiki/List_of_Hyundai_transmission...
- olyjohn 3y agoMaybe I can't tell from the video, or maybe they're not working on this yet... But what about the steering wheels? Surely the driveshaft will have to have a joint on it on the front wheels in order for the front wheels to turn? Also this doesn't look like it would deal with camber changes which are needed to keep your tires flat on the road when cornering...
- toss1 3y agoI also notice that unsprung weight was not mentioned. The "Uniwheel" clearly has advantages over CV joints, but it also looks like a significant increase in unsprung weight. They also gloss over "splitting the motor". It looks like 4 individual wheel motors, which would indeed be optimal for the torque vectoring that they mention. Still, looks like a very cool development. I hope it works out to be a real advance
- bluGill 3y agoIt is a compromise - maybe slightly more unsprung weight vs a CV joint, but less than a hub motor.
- lttlrck 3y agoRight, it seems like this will only work on non-steering solid axles, not with independent suspension.
- CodeWriter23 3y agoThe front wheels still have a CV joint to facilitate steering. See 4:17 in the video.
- ChumpGPT 3y agoThis will work and you will still be able to steer.
- seltzered_ 3y agoFWIW, 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-technology 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 alternative?
- grogenaut 3y agounsprung weight I believe is also a big issue with hub motors esp as you get up to car size at speed
- jacquesm 3y agoIt 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.
- throwaw33333434 3y agoThe other issue is that potholes my get quite expensive.
- jacquesm 3y agoYes, 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.
- benj111 3y agoHave 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.
- metadat 3y agoCc can you still do a burnout with these? It looks kind of fragile.
- prmoustache 3y agoHave you ever looked at a gearbox?
- kelseyfrog 3y agoDisappointed that they didn't explain how steering works. Seems like a major oversight.
- ChumpGPT 3y agoA 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. Steering doesn't really have anything to do with the CV Joints or power to your wheels, it is a separate system.
- bluGill 3y ago>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.
- ChumpGPT 3y agoMy understanding is they can't shorten the CV Shaft/Joint because it causes problems.If they can move it into the wheel hub, it allows them to make the motor smaller which is where they save the room. By taking one big motor to drive both front or rear wheels, they now have smaller ones much closure to each individual wheel. This reconfiguration leaves more room for interior space or extra batteries.
- chris_va 3y agoSeems like it's only in-plane motion, so the wheel can't tilt/turn? I assume that means they still need a CV joint for the front wheels regardless, and that it gains no camber when cornering.
- ChumpGPT 3y agoMost likely they will have a ball joint (like the current inner CV Joint shaft has) on the end of the shaft that connects to the device in the wheel hub.
- modeless 3y agoOne of their animations indeed showed a CV joint in between the motor and the device. But you only need one and it can be absolutely straight when the car is not turning so the efficiency should be good.
- estiaan 3y agoCorrect me if I’m wrong here but this is just sort of an alternative to a cv joint, sort of because it can’t handle rotation. It also has nothing to do with EVs specifically, a ICE could use this.
- ChumpGPT 3y agoAn 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.
- estiaan 3y agoYeah 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…
- nytesky 3y agoI honestly thought that Tesla made a version of their sedan which had 4 motors -- one for each wheel. When I looked into it, all I can find is that the CyberTruck should have 4 motors. Wasn't there a quad and duel version of the sedans -- what are they referring to?
- eightysixfour 3y agoThey have dual and triple, the triple (Plaid) has two motors on the rear if I remember correctly.
- hooby 3y agoThe 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 showing how the wheels steer. How is that supposed to work?
- deleted 3y ago[deleted]
- husam212 3y agoMaybe the motor is supposed to turn with the wheel, that doesn't sound like a good idea.
- justinclift 3y agoThat'd make the motor the pivot point. No idea if that's good or bad though. :)
- benj111 3y agoWhy 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?
- hooby 3y agoWell, 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.
- dist-epoch 3y agoI'm no mechanical expert, but I wonder how you prevent damage to the motor if the wheel encounters an obstacle when it tries to rotate (against a curb for example) or if it's forced to rotate by an exterior force.
- trabant00 3y agoUnsprung 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 city car would benefit from the space savings and does not need to go high speeds over less than perfect roads. Nor does it rack up that many miles in wear and tear. In general I think electric will bring more diversity in car designs depending on purpose.
- nixass 3y ago> 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. But uni-wheel changes paradigm!
- JoeAltmaier 3y agoAt least they are nine identical gears? So just keep a barrel of them handy!
- bluGill 3y agoI expect the bearings wear out before the gears. So just replace the whole thing. Then rebuild it with new gears and bearings later.
- nabilhat 3y agoWorth 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 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. It's a neat idea for highly space constrained applications that have to package a drivetrain very close to a wheel, which does end up being a rather niche use case. Mars rovers, perhaps. Trying to compete against CV joints in passenger vehicles with this would be quite difficult.
- benj111 3y agoIt's trying to compete against a CV joint and gear box. That seems like an easier sell. I'm not sure if we're talking past each other but you wouldn't need an axle to deflect. The motor drive could attach directly to the 'uni wheel' which is in turn connected directly to the wheel. If you're talking about the motor drive shaft, then surely you'd just be moving thrust bearings from the gearbox to the motor (if motors don't already have them)
- nabilhat 3y agoIf the drive source is attached directly to the uniwheel, then handling radial drive inputs isn't required and the uniwheel isn't necessary. It's effectively a hub motor with reduction gears at that point. Once the motor is mounted remotely from the uniwheel and the uniwheel is handling radial offsets, then we need to prevent the axle from getting pushed around radially. Rotating shafts that deflect introduce off-balance vibration and destructive mechanical loads. If the motor is located very near the uniwheel, keeping the shaft's free length very short, the motor's output bearing does effectively provide that support. Then we're only constrained by relocating the suspension elements. Thrust bearings are for the gears. The depictions show helical gears, which would surely be necessary when operating at transportation speeds for noise reasons. Helical gears experience axial forces, which would need to be handled for each gear. Mainly on one side for ICE drivetrains, since coasting loads are small, so one side could get away with a ground and hardened rub surface. EV's using regenerative braking would need robust thrust handling on both sides. Herringbone gears would eliminate the axial thrust issue, at substantially more expense. The easiest method is to separate the gear areas with a central runout groove so you'd have a hope of grinding in a decent surface on the faces, then it's only a little more than double the work; effectively cutting two gear shapes per gear plus the runout. https://en.wikipedia.org/wiki/Herringbone_gear https://en.wikipedia.org/wiki/Herringbone_gear
- wildekek 3y agoAn axial flux wheel motor is a much simpler and less fragile design for ev’s. I’d like to see more experiments with that.
- BHSPitMonkey 3y agoRegardless of the merit or practicality of the idea, I really loved the video and the animations. I'd happily watch a series of cars and other complex machines explained in the same style.
- kibwen 3y agoThe video is good, but I couldn't help but draw a parallel to the famous Rockwell Retro Encabulator: https://youtube.com/watch?v=RXJKdh1KZ0w https://youtube.com/watch?v=RXJKdh1KZ0w
- konart 3y agoI wonder how long will it take this to break if use on real (not-so-perfect) roads.
- JoeAltmaier 3y agoMy first thought, too. All those unsealed tiny gears. One fragment of metal filing in there? Perhaps a cascade failure of teeth chipping and flinging fragments until total breakdown. Reminds me of the head of a waterpic toothbrush - a packet of tiny gears, the weakest point in the device, constantly wearing out.
- tlb 3y agoThis 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.
- teamonkey 3y agoI wasn't clear why this couldn't be used on all vehicles but that makes sense, thanks.
- bluGill 3y agoIn and ICE you have the transmission - just put different gear ratios in the transmission if you need to get a different output speed. I think this could have worked with an ICE, but there is no real point: the CV joint is simple and the advantages to this don't apply when you have a single large power source.
- audunw 3y agoThis mostly makes sense if you have four individual motors right next to the wheels, that turns with the wheel. That’s obviously also not viable with ICE cars.
- KaiserPro 3y agoI love innovation. There still needs to be a CV joint to allow steering, but short of hub motors[1] There isn't much you can do about that. What I would be interested to see is how lubrication works. Do you think they just have a bunch of oil in the bottom and rely on centrifugal force to fling it to the ring gear? Then let surface tension transmit it to the sun gear? [1] They are heavy and heavy wheels affect ride quality, as suspension works essentially by allowing a light wheel to move up and down dampening against the mass of the heavy body. If the body is light, then you need to have less dampening, which means more shock/impulse is transferred into the main body of the car/
- tlb 3y agoThe hard thing with lubrication is sealing it so it doesn’t leak. Considering the pinion gear and shaft moves in 2 axes relative to the housing, that could be tough.
- audunw 3y ago> There still needs to be a CV joint to allow steering Naw, because if you look closely in the video you can see that the motors turns with the wheel. With small EV motors that’s not unreasonable. Presumably the motor is free to tilt up and down a bit as well to deal with changing camber. > but short of hub motors[1] There isn't much you can do about that. I mean, it is pretty much a hub motor that has been decouple in the vertical motion so it doesn’t contribute to unsprung mass, and with a good reduction gear as a bonus.
- spacecadet 3y agoMore or less a portal. But neat.
- nottorp 3y agoHmm steering and ride quality questions aside - i'm no mechanical engineer... How much would damaging a wheel cost?
- drsopp 3y agoLooks similar to https://507movements.com/mm_222.html https://507movements.com/mm_222.html
- iampivot 3y agoI guess they will still need a cv joint, just because wheels get out of alignment all the time. That aside, it would interesting if someone made a 3d model one could print to try this out at home for small robots.
- mtrovo 3y agoLooking at the video on their website it seems the EV motors are supposed to be mounted directly into each wheel, then you only need to account for oscillations on the X and Y axis.
- bluGill 3y agoI got that impression at first, but looking closer, the motor isn't in each wheel. It is on the frame of the car - just much closer to the wheel than a CV joint allows.
- redandblack 3y agoWill competitive racing adopt this? Assuming they seek out every advantage. Maybe their adoption will move this further to consumer space
- deleted 3y ago[deleted]
- 55555 3y agoI don’t know anything about cars but the video said the max speed was 120km/hr
- bluGill 3y ago(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.
- Justsignedup 3y agoA 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?
- ChoGGi 3y agoProbably not, this is using four motors that are close to each wheel. ICE cars route energy from a central motor.
- Justsignedup 3y agocan 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?
- ElectricalUnion 3y agoThis proposed power transfer mechanic linkage can't handle angular differences between the power plant and wheel, so you would end up with broken mechanic linkages and torn shafts. Non-spinning-shaft power transmission (doesn't really need to be electric, could as well be something like fluid power transmission like hydraulic or pneumatic power) dodge this by putting the power plant in a way the angle between power plant and wheel can't change.
- bluGill 3y agoIf 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.
- ElectricalUnion 3y agoAs ICE cars are right now, no, because unlike electric engines, combustion engines and the clutch can't be made efficient, cheap and compact all at once. If you have to end up with 4 "normal sized engines" or "normal sized clutches" to implement this, you now are in net gain of wasted weight/space.
- Tor3 3y agoIt looks interesting. But how do you change wheels? From the video there's no obvious way, and I'll assume the wheels must be very expensive - if all we see in the video is built in. Where I live I change wheels twice a year, for winter and summer (vastly different tires, and there's no way around that). So, to start with, I have to buy 8 wheels (9 actually, as my car has a spare wheel too, and that's also necessary here). That will cost a lot, it seems, and then - can I even change wheels?
- zdragnar 3y agoYou could probably get away with changing the tires, rather than replacing the entire wheel. The more interesting question to me is what happens if you get a flat tire? Does everyone need to carry a spare uniwheel, or wait to get towed?
- kwhitefoot 3y agoMost people wait to get towed these days on those rare occasions that they get a flat tyre. In over forty years of driving I've only had three flats. One I changed the wheel, the second I just drove slowly for twenty miles because the tyre was at the end of its useful life anyway, the third was on a narrow rural road on a slope so in the winter in the dark so I just waited for the car to be taken away on the back of a lorry. A lot of cars don't have a spare wheel now, why would they start carrying one in the future?
- zdragnar 3y agoI have yet to buy a car without one, but I suppose that'll be changing soon enough.
- bluGill 3y agoBack in the 1950s tires went flat often, so a spare that you knew how to put on was a must. These days tire technology is much better and so getting a flat is rare kit does happen of course, but it is not very common. Many cars will go through their entire life without using the spare even once. Since a spare takes up a lot of space and weight, it makes sense to get rid of it if it isn't needed much. Tow trucks have always existed, just call one to fix the tire when you have issues.
- simne 3y agoExcellent for sales/mechanic! Now wheel will cost more than chasis $)
- simne 3y agoWell, in reality, Forward wheel drive become typical, when it become cheap. And gears close to wheel used in off-road vehicles looong time, to create more clearance but they was headache, because need much additional mechanic time, and there was huge losses.
- metabagel 3y agoHow much additional noise will this produce compared to CV joints?
- mannykannot 3y agoMy 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!
- atomicUpdate 3y agoIt 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.
- Descon 3y agoI 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 https://en.m.wikipedia.org/wiki/Universal_joint
- audunw 3y agoIn the video you can see the motors turning with the wheels. So there’s no problem there at all. I think this would make most sense with an axial flux motor. That’d keep the package quite compact. I’m guessing the camper changes mentioned could also be handled by the motor pivoting up and down as well. But I can’t say for sure if that makes sense.
- mannykannot 3y agoI just replayed it on a big screen, and I see what you are saying - it is visible between about 5:15 and 5:20.
- crankybaldguy 3y ago[flagged]
- einpoklum 3y agoThe video says the motivation is clearance for the vehicle's cabin. Does this have benefits in term of energy efficiency? Longevity/reduced wear? Overall weight?
- Too 3y agoI’m sure there are 100 good reasons, just to play with the thought, why not a chain? Like on a motorbike. With all those extra gears, the efficiency should be comparable? Would only work for real wheels of course.
- nuancebydefault 3y agoI would assume all these gears have friction and need oil or greese. Will that alone not drain quite some energy? I was always under the impression that since EV's have a motor per active wheel, the motor would be directly on the center of the wheel and the electrical wiring would move instead, but apparently not. Would that not be the ultimate solution?
- julienfr112 3y agothe problem is you want the weight to be after the suspension, not before, so that the unsuspended weight is minimal. Putting the motor inside the wheel make that not possible, and motors are quite heavy, even electrical ones.
- nuancebydefault 3y agoI believe that makes sense since there is a lot of alternating upward and downward acceleration on the wheels while following irregularities of the road. I guess the resulting constant change of momentum would be bad for stability of the suspended part, and would wear out the suspension faster.