121–130 of 192 posts
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?
It 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…
You 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?
A lot of cars don't have a spare wheel now, why would they start carrying one in the future?
It 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…
You 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?
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?
The HUB takes up all of the space where you disk or drum brakes would be. ICE cars don't benefit from regenerative braking so you'd have to come up with another solution of how to stop the car.
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…
It'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…
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.
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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?
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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 re…
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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?
I've been under the impression that putting the motor on the wheels increases gyroscopic forces which can cause handling problems.
Earlier quoted context omitted.
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?
The wheel can move up and down relative to the motor, so you can still attach a shock absorber to the wheel, without the motor being involved. The video shows this at 2:36.
Earlier quoted context omitted.
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?
I'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.