

Michelin reinvents the wheel, electric motors help to retire the combustion engine - mielles
http://www.theenergyroadmap.com/futureblogger/show/1365-michelin-reinvents-the-wheel-electric-motors-help-to-retire-the-combustion-engine

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krschultz
A better write up without the hype

[http://www.motorauthority.com/michelins-active-wheel-
technol...](http://www.motorauthority.com/michelins-active-wheel-technology-
in-detail.html)

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paddy_m
Look at heavy equipment LeTourneau loved electric wheel motors. He built huge
scrapers, tractors, and offroad trucks with them.
<http://en.wikipedia.org/wiki/R.G._LeTourneau>

One big disadvantage of wheel motors is greater unsprung weight. This will
make for poorer ride quality, or more expensive/complicated suspension
systems. Because the wheel needs to move over bumps, if it has less mass, it
can accelerate with less energy input.

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noonespecial
LeTourneau (a personal hero of mine) powered his giant square-wire-wound
electric motors with even more powerful diesel engine/generator sets. His
machines were diesel powered with electric transmissions.

The article misses the "elephant in the room" point that _the electric motors
are the easy part_. They always have been. It doesn't much matter if you cram
the electric motor into the wheel or under the hood. Getting a power supply
with enough power density and a short enough charge cycle that its actually
feasible for daily use is the silver pearl.

~~~
jwilliams
> _His machines were diesel powered with electric transmissions._

Large mining machinery (Haulpaks) are the same - electric with a diesel power
plant.

I don't believe the wheel weight is a big issue in these cases - particularly
for the AC systems, which are somewhat simpler and more robust (in terms of
the wheel motor, the actual control system is much more complex).

The reason they use an electric system for Haulpaks is varied - but basically
it's due to the fact that a mechanical drive system is almost infeasible at
that size/load/torque. An electric transmission system is easier to control
and more robust.

Also, electric lets you control the torque much better, particularly in the AC
case where they can adjust phase/freq/etc to keep it controlled.

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mixmax
This technology is also common in cruiseships.

~~~
ms01
Diesel-electric locomotives work like this too. You can run your diesel engine
at its most optimal rpm which makes it more efficient.

This is how I hope they'll build gas-electric or diesel-electric hybrids in
the future.

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frankus
The problem with wheel motors has historically been unsprung mass (the mass of
the portion of the car that moves with the wheel, rather than with the chassis
-- typically the tire, wheel, brakes, suspension upright, and half of the
driveshafts, springs, dampers and suspension arms).

The problem with unsprung mass is that it lowers the amount of available
friction (for cornering, acceleration or braking) on bumpy roads. What happens
is that the inertia of the unsprung mass as it's cresting a bump partially or
completely offsets the downward force of the weight of the car, and the tire
no longer has any normal force with which to create friction.

A good active suspension can help by measuring the force of the tire on the
road and attempting to keep it roughly constant (by actively shoving around
the suspension). But historically active suspensions have been energy hogs,
soaking up something like a liter of fuel per hundred kilometers. It's
possible that newer power electronics and an attempt to actually focus on
energy efficiency could reduce that, but it's likely to be expensive and
complicated in any case.

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ms01
Two concept cars with this technology:

Eco-commuter Heuliez Will [http://www.treehugger.com/files/2008/11/active-
wheel-afforda...](http://www.treehugger.com/files/2008/11/active-wheel-
affordable-electric-car.php)

Performance roadster Venturi Volage
[http://www.autobloggreen.com/2008/10/02/paris-2008-venturi-v...](http://www.autobloggreen.com/2008/10/02/paris-2008-venturi-
volage-revealed/)

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ible
I've been excited by the possibility of in wheel motors ever since I first
heard of them because of the combination of simplicity of the motor, and the
massive simplification of mechanical systems of a car. You no longer need all
the bits which connect your inefficient internal combustion engine to the
wheels, and those bits lose a lot of energy, somewhere around 50% according to
what I've read. There is one company that makes buses with wheel motors which
quadruple the fuel efficiency of the current best diesel bus, and of course
there is the electric mini prototype which got a lot of hype a few years ago.

My biggest problem assessing the technology is my complete ignorance of the
mechanical/electrical engineering issues involved. One engineering grad
student argued that wheel motors were no good because they destroyed the
control of the car by putting all the weight at the very bottom, and that the
motors were going to be subject to a lot of shocks in real world use. I don't
know enough to evaluate if that is true or not, but I'm hopeful. Anyone here
know more?

~~~
streety
"There is one company that makes buses with wheel motors which quadruple the
fuel efficiency of the current best diesel bus"

Given that buses are surpassed only by garbage trucks in the number of stop
and starts they make in a given distance I suspect this has much more to do
with scavenging energy during braking than it does with the fact the motors
are in the wheels.

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mikkom
If wheels contain the motors and th motors can operate independently, it makes
some really interesting things possible like rotating the car in the position
(wheels on other side of the car roll to different directions).

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bprater
Great concept, but the article lacks any teeth. And the links don't work.
Anyone have better links -- is Michelin really developing this seriously?

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jmackinn
Here is the Michelin page for the Active Wheel:
[http://www.michelin.co.uk/michelinuk/AfficheServlet?Rubrique...](http://www.michelin.co.uk/michelinuk/AfficheServlet?Rubrique=20061224112323&Langue=EN&news_Id=23759)

But for much more detail check out the press release (pdf):
[http://servicesv2.webmichelin.com/frontnews/servlet/GetEleme...](http://servicesv2.webmichelin.com/frontnews/servlet/GetElement?elementCode=54609)

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bjoernw
So what happens when you have a flat tire? You're extremely screwed?

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kingkongrevenge
As long as the lithium ion battery is the best we got, there will be no mass
replacement of combustion engines with electric. There simply isn't the energy
density. Also, lithium supplies aren't sufficient.

~~~
DaniFong
Energy density isn't nearly the as big a problem as lifespan and cost. You
have to move some things around, but if you stick the suspension and the
engines in the wheels, there's room for > 500 liters of battery in most cars.
Th!nk gets about 150 L in a _microcar._

