[HN Gopher] Donut Lab's next-generation in-wheel motors
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Donut Lab's next-generation in-wheel motors
Author : klemola
Score : 29 points
Date : 2025-01-08 07:19 UTC (15 hours ago)
(HTM) web link (www.donutlab.com)
(TXT) w3m dump (www.donutlab.com)
| dscottboggs wrote:
| At first I was like "this is crazy, those are going to be crazy
| expensive, they'll never make it" and then I realized we're not
| the customers, at least not willingly
|
| https://www.donutdefence.com/
| unwind wrote:
| The Oruga Unitrack [1] is listed as one of their case-studies,
| it looks awesome and I would really like to see it move.
|
| I found [2] on YouTube, but it doesn't seem to contain any
| actual video of the vehicle (and the voice-over says "unit-
| rack" rather than "uni-track" which I didn't love).
|
| 1: https://oruga.eu/#unitrack
|
| 2: https://www.youtube.com/watch?v=clL4sDXxvWQ
| rco8786 wrote:
| Looks like they're targeting "civilian" products as well
| https://www.vergemotorcycles.com/
| numpad0 wrote:
| Looks like one of many "shovels for gold diggers" unitized motors
| for robotic dogs and humanoids. There's been a lot of such
| compact all-in-one motor units from China lately.
| vlachen wrote:
| I spent a number of years designing outer-runner direct drive
| permanent magnet motors for industrial equipment and I've got
| some questions.
|
| Cheifly, bearings. They're not shown in any of the oh-wow images,
| but these will likely be the most expensive component of each
| motor. Big bearings are expensive, and to accept the loading of
| normal wheel operation, these will have to be pretty beefy.
| That's not even discussing operational life and maintenance.
|
| After you've stuffed a pair of angular contact roller bearings
| into this "wheel", you're going to want to keep salt water and
| road grime from entering those bearings, so what do you use as a
| seal? Whatever you use is going to be big, expensive, and suck up
| huge amounts of power due to the large contact surface.
|
| Finally, once you've got big ass bearings and big ass seals, how
| do you have enough room to put a decent amount of copper in
| there? Power in these things always amounts to maximizing the
| amount of copper in the space, and I just don't see room for it.
| tetris11 wrote:
| I guess I'm not really following. The engine's in the wheel?
| klemola wrote:
| Yeah. In fact, the article linked below[1] is more informative
| than the page I linked. TL;DR: there's a big reduction to the
| overall weight of an EV using these, but they do add to the
| unsprung mass of the vehicle (the weight below suspension, as
| mentioned in another comment).
|
| [1]: https://www.cnet.com/home/electric-vehicles/this-donut-
| shape...
| lelanthran wrote:
| Maybe they thought of this, but I didn't see any mitigation for
| the unsprung mass problem that these motors bring.
| notjulianjaynes wrote:
| If the weights are listed on the are to be believed, this
| shouldn't be an issue. It says 40 kg for a 21" wheel. A quick
| Google is telling me that a regular old steel wheel from a
| truck of the same size is around 50 to 80 lbs (23-36 kg).
|
| That said, I was already thinking 630 kw per wheel was a pretty
| incredible claim before I realized these are apparently not
| much heavier than a non-mptorized wheel. These have to be some
| marketing department numbers or something. 630 kw is roughly
| 850 horsepower.
| vlachen wrote:
| There's a whole lot of marketing speak, finger waggling, and
| wishful thinking in what I am seeing here.
|
| Copper is heavy. So is silicon steel. So are high strength
| magnets.
|
| I love the idea, but this one's going to have a real world
| bite in the ass once they get it out of the lab.
| humptybumpty wrote:
| Well, you can already buy one:
| https://www.vergemotorcycles.com/
| vlachen wrote:
| Well _that_ is interesting.
|
| I still have my doubts, but I wish them luck. I've always
| wanted to get Kenada's bike.
| lelanthran wrote:
| > If the weights are listed on the are to be believed, this
| shouldn't be an issue. It says 40 kg for a 21" wheel. A quick
| Google is telling me that a regular old steel wheel from a
| truck of the same size is around 50 to 80 lbs (23-36 kg).
|
| I'm skeptical; They say 40kg, but I think that's just for the
| motor, not the entire wheel. I working off the (maybe
| incorrect)[1] assumption that the 40kg doesn't include the
| steel/mag rim and the tyre.
|
| As far as a 21" standard mag wheel, the tyre alone is around
| 12kg, so quite believable that a standard wheel with tyre
| would weigh maybe 30kg. However this still means that putting
| a tyre on a 40kg wheel is going to take it to +52kg.
|
| [1] Just the minimum metal and rubber needed for a 21" wheel
| to maintain its shape and structure should be around 30kg.
| Maybe this motor is structurally round already, so doesn't
| need any rim to reinforce it?
| archontes wrote:
| I'm thinking about the motorcycle motor. If they're really
| lighter than competing motors, I don't see the downside of
| using them like a traditional motor, taking the weight savings,
| putting it inside a sealed cavity, and coupling it to a
| driveshaft. Simplifies some of the other problems with sealing
| and bearings mentioned elsewhere, avoids unsprung mass.
| pbronez wrote:
| Pretty powerful stuff. The Model Y Long Range AWD has a pair of
| motors that deliver Peak Power of 286 kW and Peak Torque of 510
| N[?]m. Donut's claims their Automotive (21") motor can 2.2x the
| Power (630kW) and 8.4x the Torque (4300 Nm)
|
| That's high enough that I have to assume it's for all four
| wheels... if it's for a single wheel, then an all wheel drive
| vehicle would have 2520Kw Power + 17,200 Nm Torque, which is 1.6x
| more than the most powerful production car in the world: the
| Lotus Evija (1,500 kW).
| pbronez wrote:
| This page [0] says "Donut Platform empowers hypercars [...]
| Delivering 1,500kW and 9,000Nm of total wheel torque, with
| acceleration from 0-100km/h in under 2 seconds"
|
| I don't see how you go from a single 286kW/510Nm hub motor x4
| gets you 1500kW/9000Nm instead of 2520Kw/17200Nm. Wonder what
| the limitations are + what nonsense they are trying to pull in
| their single motor stats.
|
| [0] https://www.donutlab.com/industries/
| exabrial wrote:
| There's a concept called "unsprung mass", which basically
| destroys handling of all vehicles from race cars to trucks.
| Basically the greater the unsprung mass, the harder it is to damp
| the input into the suspension because of the inertia of the
| moving suspension components themselves. An ideal suspension has
| zero undamped mass, and all input to the suspension is a direct
| result of contact with the surface the vehicle is traveling on.
|
| There is zero chance this tech will make it into sports cars
| unless it can beat the weight of a magnesium or AL alloy rim.
| Even casual vehicles like minivans have rim weight minimized for
| comfort.
|
| Not an expert :) just watched enough Donut media on youtubes :P
| westmeal wrote:
| One thing to add, while your wheels and tires are a big chunk
| of the weight here - you also have the uprights/knuckle and the
| wheel hub, bearing, brakes, rotor etc etc. All of that adds up
| quick. Most times if you are looking to reduce this on a car
| you will have the most gains (or losses haha) switching to an
| aftermarket wheel. No wonder the manufacturers slapped alloys
| on their cars too!
| JumpCrisscross wrote:
| "The unsprung mass (colloquially unsprung weight) of a vehicle
| is the mass of the suspension, wheels or tracks (as
| applicable), and other components directly connected to them.
| This contrasts with the sprung mass (or weight) supported by
| the suspension, which includes the body and other components
| within or attached to it. Components of the unsprung mass
| include the wheel axles, wheel bearings, wheel hubs, tires, and
| a portion of the weight of driveshafts, springs, shock
| absorbers, and suspension links.
|
| ...
|
| The unsprung mass of a typical wheel/tire combination
| represents a trade-off between the pair's bump-absorbing/road-
| tracking ability and vibration isolation."
|
| https://en.m.wikipedia.org/wiki/Unsprung_mass
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(page generated 2025-01-08 23:02 UTC)