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Why not in-wheel hub engines?

I have read about the Brabus All Electric 4wd , and now it seems it is in production.
Brabus uses wheel hub engines. 4 of them for a whopping 4 x 110 hp. 440 HP. Grip on all wheels. Must be fun. Even in wintertime.

As we know there is no plan for a 4wd Tesla S any time soon.
But wouldn't it be possible for Tesla also to use those Protean Electric motors?
Sure bolting 2 of them in front corners must be cost friendly way to give Tesla S 4wd?

I do see the obvious, that those 2 electric motors will increase the unsprung weight. Are there others?

Maybe possible to do an personal upgrade to the front wheels, slightly modification maybe but should be doable?

Here you can see those In-wheel motors

I doubt they'd ever allow for all electronic braking. I think mechanical brakes would still be required by the NTSB. Mechanical brakes are designed so that there's no single point of failure, i.e. dual master cylinders, etc. You might be able to get away with smaller brakes, like the Prius does. Inductive motors require excitation power to generate electricity so if your main power supply (i.e. battery) dies or have an electrical fault you'd have no brakes.

@Protean; But,each of our motors is 800 N.m peak torque and more torque feels better

Tesla Model S standard 85kWh version gives peak motor torque of "only" 440Nm, but that then gets multiplied by reduction gear so that output torque is 9.73*440Nm = 4281.2Nm. 800*4 = 3200Nm, or 4281.2/4 = 1070.3Nm. That's with single motor. Doubled to AWD you get over 2000Nm measured from the wheels.

Performance version gets even more impressive numbers.

The fact is that hub-motors just are not powerful enough, not for passenger cars anyway. Hub-motors could be useful as brake replacements though, especially for very heavy vehicles with multiple wheels. Regen would be much better I imagine.

@ Iph .

100% regen braking under current NHTSA regulations would not be allowed. There MUST be a redundant mechanical system, Air or Hydraulic in place.

@Superliner, I imagine that is one regulation that could be removed if the regen as brake could be proven to be equally powerful and more reliable (magnetic brake essentially, with no moving parts it could be more reliable than ordinary brakes).

Complete stop at low speeds must still be managed mechanically. Unless you run the motor in reverse to apply decel.

To address some of the follow up comments....we can regen as much as we "gen" or about 80kW per motor. Our motors were used on both the Brabus EV and the Brabus Hybrid cars, based on a Mercedes E Class. Just from regen, we can develop about 0.3G of decell, which is enough for most normal stopping maneuvers. However, we also have conventional disc brakes (not breaks) because of regulation requirements. (belt and suspenders)

Finally,we use a conventional wheel and tire, not a special design, as long as it is at least 18". Thanks for listening.

Protean,

On this forum, it's "breaks", not "brakes". You will learn...

Protean, don't listen to him. Group-think misspellings are still boners. >:p

@Protean

Do you think it might be possible in the future to add aftermarket in-wheel motors to the front wheels of Tesla S to get 4wd?

I realize there are not all positive effects from using such motors regarding unsprung weight but for many users the benefits would far outweigh! the downside. And after all, Tesla S is first and foremost an every day car - not a track day car or a trailer queen. For me living in snow and ice 6-8 months a year I do prefer 4wd. Yet I would not like to wait for the Tesla X.

Will it be possible at all to mount your motors in the front wheels?

The Toyota i-Road has been revealed at the Geneva Motor Show. The two front wheels have in-wheel electric motors. I think Toyota should really start thinking about producing and selling these i-Road vehicles. They are ideal for the city, where there is lots of traffic. This could be a real success. It's better than the Renault Twizzy anyhow.

@torst1 - I don't think it is a good idea to retrofit hub motors, as I think you need to design the suspension around the extra unsprung weight and torques that will be created.

Retro fitting Hub motors wouldn't require a re-design of the Suspension geometry, a recalculation of the damping and rebound maybe and change the springs and shocks. If you were planning on converting your ICE car you would have to do that anyway.

If hub motors are so useless, can someone explain these 2 youtub videos?

https://www.youtube.com/watch?v=0avfYsLW28k

https://www.youtube.com/watch?v=AM6DAnoa8pE

Why would you want to build and control four motors when you can do it with just one?

A bit off topic. When clicking on the OP's Brabus link, why is the title of the webpage page "Brabus - Tesla Roadster"? (hint: look at your browser's title bar)

@eccocentral: "If hub motors are so useless, can someone explain these 2 youtub videos?"

Easy! Tesla builds CARS not bikes!

Even the fantastic 4-motor Rimac Concept_One doesn't use hub motors.
They're simply not there yet. Protean may be leader in the field and in case this is definitely something to watch.

But in the future, we may see hub motors in EVs. Nice, neat, and simple.

Hub motors will not work due to fact that dynamic loading of every component will lead to premature failure. Also corrosion is a big issue. There is no seal that can handle the dynamic loads and water pressure in a wheel that will not leak in short order... With these loads you need a really big set of bearings and this means you need a really big seal. Big seals are more likely to fail and leak...

Right now if your seal fails you have to replace the cheap wheel bearings and maybe a spindle. In a hub motor you replace the motor...

Inwheel motor projects are sucker traps for unknowing investors, who don't know much about motor design or manufacturing. Much like Webcrawler described, they simply do not make sense for anything that needs handling and reliability of sealing is nowhere near where it should be to be a reliable option. Maybe for military and applications where money is thrown away on rebuilding and maintenance but not in applications that need to handle and make economic sense in the mid or long run. It only looks good as an idea in the simplest
of terms.

I love how random people keep saying how in-hub will never work, for this and that reason, in their humble opinion, blah blah blah. Did anybody bother to read the nice research from Lotus? Doesn't seem so. If Lotus tells me unsprung mass can be dealt with, and Mercedes makes prototypes with in-hub from Protean, then it must be something worth their time. Maybe some of these posts are payed for by the automotive and oil industries who would like to maintain the status quo?

Because you don't need it with our traction control.

The question remains why? Nothing it mentioned can not be done with the much less complex conventional design other than "using unoccupied space in the wheel" which is not 100% true anyway. But it's not like designs like Model S, either RWD or future AWD, really eat up that much usable space either.

@darkhut,
What is random about Car t man, Webcrawler, chrisdl, ir, etc.?

@PBEndo Well, they all know hoe to spell "paid."

But not how.


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