The inverted rotor/stator design is such an obvious and elegant
solution to an electric drive for vehicles that one does wonder
why it hadn't been thought of before.
It has been thought of before. To my personal knowledge, it was
thought of at least 40 years ago.
There are several reasons the design was not used in cars:
* Motors like this make for heavier wheels; the `unsprung weight'
increases. I have yet to read a discussion of how important this
factor is now; all I know is that engineers have always told me
that an increase in `unsprung weight' is a problem.
As far as I know, this is, or was, the key problem.
In the 1960s, Wyle Labs developed a hydraulic resevoir and motor
that would have been fine for cars except for this problem. (I am
told it ended up being used by NASA; devices may have gone to the
moon.) I don't know whether modern designs for either electricty
or hydraulics weigh less.
* In the 1950s, it was less expensive to build cars with an internal
combustion engine driving a clutch, a differential, and wheels
than to build cars with an internal combustion engine driving a
generator and then motors on wheels.
Remember, car manufacturers enjoyed a great deal of sunk
investment in machinery to make clutches and differentials. A
different technology could not simply be a little better; it had
to be sufficiently better that the oligopolists of the time had an
incentive to shift. Moreover, California smog regulations did not
exist, so companies were not encouraged to design hybrids with
less smoggy engines.
* In the past, and perhaps in the present, I do not know, engineers
have been worried about keeping connections in a wheel from
shorting when the car drives through puddles of water.
Would the inverted rotor/stator design be for direct current,
which was the least expensive before modern controls and which has
the best low power torque? If so, the problem of shorts becomes
very serious.
* In the past, speed control mechanisms were more expensive than
now; the price of modern electronics has dropped markedly over the
past half century.
Incidentally, I do not know how a car was supposed to respond to a
foot on the pedal in the past-- would it increase the fuel flow to the
engine, which would generate more electricity, which would provide
more power to the wheels, thereby obviating the need for expensive and
unreliable batteries, or would pressing the accelerator increase
electricity from a battery, the draw on which would cause a govenor to
increase fuel flow to an engine? Remember, batteries are temperature
sensitive, and their use through the winter is difficult, though not
impossible.
I personally have always wanted to see an inverted rotor/stator design
for cars. It is a beautiful design.
--
Robert J. Chassell Rattlesnake Enterprises
http://www.rattlesnake.com GnuPG Key ID: 004B4AC8
http://www.teak.cc [EMAIL PROTECTED]
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