Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Donut Lab's next-generation in-wheel motors

donutlab.com

Post reply on HN
Print view View original

11–20 of 41 posts

Re: Donut Lab's next-generation in-wheel motors

#11

Post by vlachen »

notjulianjaynes wrote: post #9
lelanthran wrote: post #8

Maybe they thought of this, but I didn't see any mitigation for the unsprung mass problem that these motors bring.

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 s…

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.

Re: Donut Lab's next-generation in-wheel motors

#12

Post by humptybumpty »

vlachen wrote: post #11
notjulianjaynes wrote: post #9

Earlier quoted context omitted.

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 s…

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.

Well, you can already buy one: https://www.vergemotorcycles.com/

Re: Donut Lab's next-generation in-wheel motors

#13

Post by archontes »

lelanthran wrote: post #8

Maybe they thought of this, but I didn't see any mitigation for the unsprung mass problem that these motors bring.

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.

Re: Donut Lab's next-generation in-wheel motors

#14

Post by vlachen »

humptybumpty wrote: post #12
vlachen wrote: post #11

Earlier quoted context omitted.

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.

Well, you can already buy one: https://www.vergemotorcycles.com/

Well that is interesting.

I still have my doubts, but I wish them luck. I've always wanted to get Kenada's bike.

Re: Donut Lab's next-generation in-wheel motors

#15

Post by pbronez »

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).

Re: Donut Lab's next-generation in-wheel motors

#16

Post by pbronez »

pbronez wrote: post #15

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…

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/

Re: Donut Lab's next-generation in-wheel motors

#17

Post by lelanthran »

notjulianjaynes wrote: post #9
lelanthran wrote: post #8

Maybe they thought of this, but I didn't see any mitigation for the unsprung mass problem that these motors bring.

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 s…

> 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?

Re: Donut Lab's next-generation in-wheel motors

#18

Post by exabrial »

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

Re: Donut Lab's next-generation in-wheel motors

#19

Post by westmeal »

exabrial wrote: post #18

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…

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!

Re: Donut Lab's next-generation in-wheel motors

#20

Post by JumpCrisscross »

exabrial wrote: post #18

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…

“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

Post reply on HN