RE: Detroit '09: Fisker Karma S
Discussion
zcacogp said:
theluckyman said:
A question - I'm an energy analyst/engineer not an automotive engineer. I suspect quite a few of you are though. What would the implications be of putting an electric motor on each wheel? Would it necessarily affect unsprung mass?
Interesting Q. Little known fact - this is where a car-making company called Porsche started, around 100 years ago ... (not what you think tho'.) It would be possible. The unsprung mass issue would depend upon whether you put the motor outside of the suspension (in which case it would be part of the unsprung mass), or inside driving through a CV joint or similar (in which case it wouldn't be part of the unsprung mass.)
What's behind the question?
Oli.
I was thinking about the Audi A8 - heavy because of the quattro system they use, which got me thinking about how you'd package 4WD with a plug-in. Advantages of having the elec motor connected to all wheels is a big increase in the amount of energy you recover when you slow down or break. If you could have a motor on each wheel it would reduce complexity - you don't need diffs or the weight of the mechanical system - and you could set it up to alter the car's handling pretty much at will with the right software.
So what's this Porsche story? I like little-known facts
Cheers, George
zcacogp said:
theluckyman said:
A question - I'm an energy analyst/engineer not an automotive engineer. I suspect quite a few of you are though. What would the implications be of putting an electric motor on each wheel? Would it necessarily affect unsprung mass?
Interesting Q. Little known fact - this is where a car-making company called Porsche started, around 100 years ago ... (not what you think tho'.)It would be possible. The unsprung mass issue would depend upon whether you put the motor outside of the suspension (in which case it would be part of the unsprung mass), or inside driving through a CV joint or similar (in which case it wouldn't be part of the unsprung mass.)
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