Lee Hart wrote:
...have a long shaft on the motor... acts like a swing axle
...have a gear-, chain-, or belt-reduction between motor shaft and wheel...
Ben Goren via EV wrote:
Are any of those considered hub motor designs? I've never, for example,
heard of an aircooled VW as an hub motor vehicle.
Much of this is defined by marketing, not engineering. If calling it a
"hub motor" makes it sell, then it's called a "hub motor". You'll find
lots of examples of bicycle "hub motors" that have a high-speed motor
with a gear reduction between it and the wheel, for example. Of course
in bicycles, unsprung weight is much less of a problem due to the low
speeds and general lack of suspension anyway.
have an axial flux motor design, where the stator can be attached to
the car chassis, but the rotor can move up/down with the suspension.
Sounds like either a recipe for disaster or an impossible design.
True direct-drive hub motors pretty much *are* an impossible design. :-/
They only work if you're willing to sacrifice cost, performance,
reliability, etc. just to have a hub motor. That means they only get
used in specialized applications.
You've either got no room for travel between stator and rotor and
the two catastrophically collide the first time you run over a pebble,
or else you've got an huge gap between the two with some sort of
magnetic levitation keeping the wheels attached to the car and
also somehow spinning.
Indeed, the working examples do have these issues. They'll use McPherson
strut suspension, so the wheel does move straight up/down. Then some
kind of planar ball bearing, air cushion, or other means to keep the
rotor and stator apart, or minimize the consequences of them touching
(RPM is low, after all).
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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