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Forgive my ignorance, but what exactly is a
magnetically coupled thruster? I get a mental picture of a 'standard' motor,
whose shaft has a largish diameter disk, with magnets on it,
all encased, coupling through a thin non-magnetic wall to a simular
disk / shaft / prop.
If that's what it is, it sounds like a bit of a
kludge. If the coupling wall is conductive, then you get eddy current
problems unless the RPMs are low. There need to be two sets of bearings, etc. A
motor is inherently a magnetically coupled structure, so adding a second set of
magnets for torque coupling seems redundant.
It seems to me that a BLDC motor could be made to
operate in sea water directly... no pressure comp, etc. Put the magnets on
the shaft, use an open cage for the shaft bearings. The stator & windings
could be potted in epoxy. The shaft & magnets similarly would have to be
coated. The bearings could be a weak point, as they would operate in the
water, but I think that would be solvable. Instead of using a shaft,
increase the stator diameter and you could make a ring-thruster.
What am I missing?
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