On Jun 29, 2009, at 8:36 AM, Harry Veeder wrote:
Yes the loop is closed, but I am working from the hypothesis that
the bearings are accelerated by the magnetic field produced by the
current flowing through the shaft. Therefore the bearings
do not need to make electrical contact with the shaft,
although they might need some start-up rotation. Note,
my hypothesis is just a guess so I can't justify it on theoretical
grounds using conventional physics. All I can say is that a
"torque" is
not required. This is becoming clearer to me as we talk about it.
It there is no torque there will be no rotation. There is friction
that stops any rotation unless torque is maintained. If there is no
current there will be no torque.
It there is a current through the shaft there is a circular B field
around the shaft, except in the vicinity of the brushes. A circular
B field, even if it magnetizes the balls, will produce no torque upon
the balls other than a torque that retards their rotation, unless
there is also a radial current through the balls.
It is easy to see, by symmetry, that a radial current through the
balls can not produce a net torque, because the circular B field is
in the same direction at the bearings at both ends, but the current
direction is into the shaft at one end and out at the other, thus any
such torque must net to zero. The torque at one end of the shaft
exactly cancels the torque at the other end, provided both ends are
symmetrical to each other.
Besides the symmetry argument, if you actually draw the configuration
you can see that a circular B field will act on any radial current
through the balls to produce an axial force on the bearings, not a
torque on the bearings.
If you look more carefully at what happens to the magnetic material
in the ordinary Marino motor as it rotates, however, you can see that
hysteresis (a delay in the de-magnetizing of the material) permits
magnetized material to rotate into place where the radial current
through it produces a torque that reinforces the direction of
rotation, which ever direction of rotation that might be. This is all
laid out in diagrammatic form in Figs 3 and 4 of:
http://www.mtaonline.net/~hheffner/HullMotor.pdf
Further, the symmetry argument for the ordinary Marinov motor now
shows a reinforcing, not canceling, effect at both ends of the
shaft. This is because, when the current i is directed radially into
the shaft, the magnetization direction of the material that rotates
into place in the current stream is the opposite of the material at
the other end of the shaft where the current is directed radially out
of the shaft. The torque at both ends of the shaft is thus
reinforcing, and in the direction of the rotation, whichever
direction that might be.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
