[chinathrow]

Click "More" and scroll down:

"In contrast to conventional radial flux motors, the electromagnetic flux in an axial flux motor runs parallel to the axis of rotation. The key components are arranged in a disc‑shaped layout: two rotors sandwich the stator from the left and right. This design enables an especially compact motor architecture, high power and torque density, and new freedoms in drivetrain packaging. In the new Mercedes‑AMG GT 4‑Door Coupe, the motor at the front axle is just under nine centimetres wide; the two motors at the rear axle each measure around eight centimetres in width. The three axial flux motors are integrated per axle into so‑called High Performance Electric Drive Units (HP.EDU), where they are combined with a compact input planetary gearbox in a single housing."

[giancarlostoro]

Really the kind of thing that should be earlier in an article about… that very thing the reader is wondering about, but maybe we arent the target audience?

[woodpanel]

> that very thing the reader is wondering about

Don’t mistake your curiosity for everyone else’s

[zymhan]

It's a press release.

[swiftcoder]

This is the same design that enables the PCB Stator Motors, right?

[klaff]

Yes. If you have a laser printer, that windup sound you hear at the start of a job is the polygon mirror motor spinning up thousands of RPMs - those are PCB stator motors. As were VCR head motors.

[utopiah]

"Advantages : A motor can be built upon any flat structure, such as a PCB, by adding coils and a bearing." https://en.wikipedia.org/wiki/Axial_flux_motor with image of "A miniature DC brushless axial motor used in a Digital Data Storage drive, showing the integration with PCB construction techniques."

[moffkalast]

Floppy disk drive motors, but for cars.

[phyzix5761]

For some reason that reminds me of https://www.youtube.com/watch?v=aW2LvQUcwqc

[engineer_22]

> This design enables an especially compact motor architecture, high power and torque density, and new freedoms in drivetrain packaging.

Hand waving.

[0-_-0]

No, it means the motor is smaller and it can be put into the wheel

[klaff]

It doesn't make that a good idea. Armature losses are proportional to torque squared - doesn't matter if it is radial or axial design. That's why all the EVs today have gear boxes with ratios like 13:1. Get rid of that gearbox and the steady-state losses go up with the square of that ratio. Then there are the issues of sprung mass, and where to put the mechanical brakes.

[ed_balls]

>gear boxes with ratios like 13:1.

you add planetary gears

>sprung mass

you can integrate all into one hub (breaks, bearings, gears etc) and it weights pretty much the same.

what you gain is more space for a bigger battery, torque vectoring, no loss on diff and CVs

[klaff]

> you can integrate all into one hub (breaks, bearings, gears etc) and it weights pretty much the same.

You would get to delete about half the mass of the half-shaft but otherwise you are cramming a lot of stuff into the wheel volume and it all has to survive living out there. Now your HV wiring and any cooling connections to the motor have to flex with the movements of the suspension and probably need guarding against rocks and other road debris. I think all EVs now have the drive electronics tightly coupled to the motors - now that either has to be separated or made compact enough to fit and rugged enough to survive a much higher vibration regime. We do have small amounts of electronics on hub assemblies today (I'm thinking of electronic parking brakes) so there is some precedent but that circuitry is much less challenging than an inverter handling 100s of kW.

>no loss on diff

I doubt there's much loss from differentials in EVs. They don't have the bevel gear of diffs used in longitudinal layout ICE vehicles and mostly the gears in a diff don't move relative to one another (unless you are doing donuts!), so the whole cage mostly acts like a solid gear giving whatever final ratio.

[zardo]

YASA claims their integrated brake/wheel motor is lighter than comparable (supercar) disc brake systems.

[klaff]

Do they claim enough reliability and peak power capability to delete the mechanical brakes? I know Brembo is working on electric brakes that would eliminate the hydraulic circuits and pistons. I don't know what they plan to do to make sure the electrical side is as robust as the split-diagonal brake system we've been using for 60 years or so.

[zardo]

Having four wheel motors solves any issues that compromise a single unit, but I don't think they've answered how they would mitigate potential system issues that might bring them all down at once.

[engineer_22]

Yeah that's exactly what the words say, thanks for parsing it for me.

No, it's hand waving because it doesn't explain how or why. That's what "hand waving" means.

[MostlyStable]

aren't there other issues with having the motor in the wheels? Unsprung mass, plus the wheels can get pretty banged around?

[parineum]

You could add a short drive shaft behind the springs to put the motor on the car body. That'd give you some additional advantage of moving much of the brake weight off of the wheel as well.