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submitted 11 months ago by floofloof@lemmy.ca to c/technology@lemmy.world
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[-] MonkderZweite@feddit.ch 249 points 11 months ago

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?

[-] Pulptastic@midwest.social 57 points 11 months ago

Yeah, buttons can be found without looking.

[-] HiddenLayer5@lemmy.ml 48 points 11 months ago

They also provide tactile feedback allowing you to be sure they have been pressed without even looking.

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[-] nexusband@lemmy.world 25 points 11 months ago* (last edited 11 months ago)

THE reason i got a Mazda, after many years of Mercedes and BMW...

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[-] Haywire@lemm.ee 14 points 11 months ago

Also make them illegal in aircraft! And spacecraft! Seriously stupid.

[-] CeeBee@lemmy.world 17 points 11 months ago

I vote for cheap PlayStation controllers.

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[-] Pika@sh.itjust.works 13 points 11 months ago

So much this, it makes no sense for using a portable phone to be illegal while driving but yet my car stereo can be a full on entertainment system and require me to have zero feedback to change the channel or answer a call.

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[-] luthis@lemmy.nz 169 points 11 months ago

Can we have more mechanical posts like this?

[-] Maalus@lemmy.world 87 points 11 months ago

No, you need 555 posts about the shit that a billionaire said about stuff he knows nothing about

[-] StereoTrespasser@lemmy.world 18 points 11 months ago

And then someone saying something about Linux

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[-] machinin@lemmy.world 20 points 11 months ago

Be the change you want to see!!

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[-] XeroxCool@lemmy.world 145 points 11 months ago

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.

  1. 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.

  2. 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.

[-] OhmsLawn@lemmy.world 41 points 11 months ago

I'd be concerned with the amount of unsprung weight this adds, too. You're basically taking the transmission and adding that mass to the hub. Seems like it would be pretty crashy on rough surfaces.

[-] XeroxCool@lemmy.world 15 points 11 months ago* (last edited 11 months ago)

I considered that but couldn't make any conclusions. The driveshaft and sun gear are not added to the unsprung. I'd guess only half the weight of planets and carriers is added. It definitely adds the weight of the ring gear to the unsprung mass.

I'm also curious how this affects rotational mass. So while every component spinning with the wheel from tire to motor shaft has rotational inertia, small-diameter components such as drive shafts have relatively little rotational inertia. Wheels and even brake discs have a lot more. I don't have numbers obviously but I'm curious if the rotational mass of the ring gear ends up being detrimental compared to a heavier-weight lower-inertia cv setup.

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[-] agent_flounder@lemmy.world 23 points 11 months ago

I noticed they conveniently didn't talk a lot about steering..

The claim of "one wheel drive" I think is meant to highlight what happens if traction is lost. It sounds like something I have heard on 4wd off-road forums. I agree the phrase "one wheel drive" is perhaps not a great way to explain the disadvantages of differentials vs limited slip differentials vs locking differentials vs individually driven wheels.

The idea of "one wheel drive" as I have seen it used, is that in a vehicle with one powered axle assembly (what we normally call 2wd-- either front or rear wheel drive) is that if you lose traction with either drive wheel, the vehicle no longer moves because all power is diverted to the slipping wheel.

If you have a limited slip differential, there is a limit to how much power is diverted to the slipping wheel. With a locking differential, you only stop moving if you lose traction to both drive wheels.

Anyway...

The design is really interesting.

You also bring up a good point about how camber changes with suspension position. Also the effective track width changes, such as with my 4Runner which has upper and lower control arms, a Double wishbone suspension. If the motor remains in a fixed position, the wheel will move onboard and outboard relative to the motor depending on suspension location.

I don't quite get how these two effects are addressed with this new design. Or are the suggesting a different suspension technology that they didn't discuss?

As for steering, I wonder if the design rotates the motor along with the wheel. In that case no CV is needed but I would guess there are some downsides to such a design.

I agree the video seems kind of... premature. The mechanism is cool but I don't get the sense that its applications haven't exactly been nailed down yet.

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[-] BaroqueInMind@kbin.social 94 points 11 months ago

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.

[-] psycho_driver@lemmy.world 39 points 11 months ago

similar to the Wankel engine

Was the Wankel engine really a step forward though? I'm a gearhead who does all his own car maintenance, up to and including engine swaps in the past and retro-modding bigger turbos and aftermarket fuel injection systems into my cars (Datsuns in the latter case). That being said, I only know the very basics about rotary engines. I've always admired the Mazda RX's from afar.

Mazda, who by no means makes a bad gasoline engine, could never get a rotary motor to last well or to have anywhere near decent fuel economy. Also, the rotary design was tried for a while in at least refrigeration compressor applications, where it blew up there a lot more than the other types of compressors as well.

[-] gens@programming.dev 21 points 11 months ago

Yea. They have worse efficiency. To get better efficiency from them you would need to run them hotter (afaik), and if you do that they would last even shorter.

It's great if you want a smaller but still strong engine, but it's not efficient and those seals are a big problem.

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[-] Cethin@lemmy.zip 13 points 11 months ago

But capitalism creates innovation!!!

[-] aidan@lemmy.world 15 points 11 months ago

Some people argue that intellectual property law is not free market capitalism, and is instead a regulation that benefits big business. I'm one of those people

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[-] trackindakraken@lemmy.whynotdrs.org 88 points 11 months ago

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!

[-] PlutoniumAcid@lemmy.world 71 points 11 months ago

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

[-] Snapz@lemmy.world 64 points 11 months ago

Yeah, skimmed and saw one of his other articles praising the cybertruck and realized this likely wasn't a source worth absorbing.

[-] cordlesslamp@lemmy.today 71 points 11 months ago* (last edited 11 months ago)

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!

[-] AlijahTheMediocre@lemmy.world 20 points 11 months ago

If we could get standardized and interoperable electric car parts, that'd be great.

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[-] danc4498@lemmy.world 64 points 11 months ago

https://youtu.be/Nd6C0y8xc20

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

[-] billwashere@lemmy.world 21 points 11 months ago

Surprisingly easy to understand video for a complex concept.

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[-] ilovesatan@lemmy.world 40 points 11 months ago

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

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[-] orclev@lemmy.world 33 points 11 months ago

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.

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[-] x2XS2L0U@feddit.de 22 points 11 months ago
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[-] Magiccupcake@startrek.website 21 points 11 months ago

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.

[-] storcholus@feddit.de 46 points 11 months ago

If you put the motor in the wheel you increase the unsuspended mass. Bad for handling and ride quality

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[-] BearOfaTime@lemm.ee 15 points 11 months ago* (last edited 11 months ago)

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.

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[-] epyon22@sh.itjust.works 14 points 11 months ago

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.

[-] Trollception@lemmy.world 24 points 11 months ago

It will have a boot or case on it and will be filled with grease. Just like a cv joint or ball joint.

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this post was submitted on 02 Dec 2023
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