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Print 24 comment(s) - last by snhoj.. on Feb 12 at 4:38 PM

Patent also shows aerodynamic wheels

Although there are numerous patents that get filed and never applied to real-life products, a couple of a few patents from automaker Audi have turned up that are reportedly going to be used in a production vehicle within the next two years.
 
The patents are for “active” aerodynamic wheels and an electric all-wheel drive system. The patent for the wheels shows a hinged flap between the spokes that move over the spokes of the wheels as speed increases. Once fully deployed, the hinged flaps create a flat wheel surface, reducing drag.
 
Active Wheel Shutters on the Ford Atlas Concept

Audi says that the fully enclosed wheels smooth the airflow and help improve the aerodynamics of the vehicle. When the car starts to slow down, the flaps reopen. The flaps are also temperature sensitive and if the brakes become too hot, the flaps open to allow cooling air inside.
 
It's hard to imagine the extra complexity of this sort of wheel justifying any fuel efficiency improvements gained by better aerodynamics, but the Germans are known for using overly complex electrical/mechanical systems.
 
Ford showed a similar active flap system with its Atlas concept truck at the 2013 Detroit Auto Show, but that feature didn’t make it into the all-new 2015 F-150.
 
Audi Quattro LaserLight Concept

The other Audi patent is for electric all-wheel drive technology, outlining a system with an electrically driven rear axle. The patent is for software systems that use sensors in the wheels to detect when the wheels break traction on slippery surfaces.
 
The patent outlines a system that would use regenerative braking that varies according to road conditions. The sensors would detect speed differences between the front wheels and rear wheels to determine how much braking force is appropriate.

Source: Autocar



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Electric wheel drives
By Cluebat on 2/10/2014 1:04:59 PM , Rating: 2
I am still waiting for someone to come out with direct- drive EV wheels.




RE: Electric wheel drives
By snhoj on 2/10/2014 8:45:44 PM , Rating: 3
I'm not. Wheel motors substantially increase the unsprung weight which will have a significant negative effect on vehicle dynamics. In order to generate the required torque without the aid of any gearing direct drive motors will need a lot of poles. The gradability of such a vehicle is likely to be compromised. At the end of the day a better solution is to put the motors inboard where they won’t contribute to unsprung weight and behind reduction boxes were their torque can be amplified by gearing so they can be small and light and the vehicle gradability won’t be a compromise.


RE: Electric wheel drives
By Cluebat on 2/11/2014 7:50:28 AM , Rating: 2
http://car.pege.org/2006-ever-monaco-2-wheels/20-k...

Leaf is 80 kW and the wheels are much larger than the one on this scooter.

I think it's very doable with present technology. You can pick it apart all you like, but I don't think that there is any point you have made which cannot be easily overcome. Of course if everyone wanted one then we would have material supply issues, but we already have that with lithium and rare earth metal supplies on current EVs.


RE: Electric wheel drives
By snhoj on 2/11/2014 10:00:14 PM , Rating: 2
A leaf will also weigh many times what that scooter will weigh. Power and torque are two different things. Power is a fairly meaningless parameter when determining gradability. Torque at the wheel divided by the rolling radius of the wheel will determine the motive force. Weight of the vehicle times gravity times the gradient will determine the force that must be overcome for the vehicle to move up the grade.

It is true that these are just technical issues to be overcome and I'm sure will be one day but for me the compromises that must currently be struck are just not worth it for some debatable vehicle packaging advantage. I’m not convinced the compromises will ever be worth it.


RE: Electric wheel drives
By PaFromFL on 2/11/2014 8:49:28 AM , Rating: 2
Active suspensions can compensate for the increase in unsprung weight. Inboard motors take up space and increase mechanical complexity. Hopefully hub motors will reduce the overall weight and size of the vehicle, reducing torque requirements.


RE: Electric wheel drives
By snhoj on 2/11/2014 9:39:35 PM , Rating: 2
The best way to compensate to unsprung weight is to reduce unsprung weight. Deal with the problem directly rather than adding extra layers of technology and complexity to try and fix the symptoms. To me the benefits in terms of vehicle packaging are outweighed by the deficits. Mechanical complexity is a mute point when you consider that you will have to work around some mechanical brakes and increase the number of poles in the motor by a factor of at least 5. Then because the wheel is now full of motor and brakes steering geometry is compromised.


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