On Jul 12, 2007, at 5:54 AM, Stiffler Scientific wrote:
Would it possible to arrange things such that the _net_ displacement
of the field is zero?
Harry
You can eliminate the shields altogether, and just move the magnets
(or coils). See Figs 1-3.
| | | |
| M1 | | M2 | Magnet motion --->
-------- --------
-------- --------
o| C1 |o o| C2 |o
o| |o o| |o
Fig.1 - Partial cross section of staggered magnet motion concept
| | | |
| M1 | | M2 | Magnet motion --->
-------- --------
-------- --------
o| C1 |o o| C2 |o
o| |o o| |o
Fig.2 - Intermediate state of magnets in motion
| | | |
| M1 | | M2 | Magnet motion --->
-------- --------
-------- --------
o| C1 |o o| C2 |o
o| |o o| |o
Fig.3 - M2-C2 flux maximized
The rotor contains magnets Mi, and cores with coils Ci, which are
arranged in a staggered fashion as shown, such that the force of
breaking off one flux path is balanced by the energy obtained closing
a flux path. Having N magnet-core stators and N+1 holes achieves
this. The bigger N is, the more balance that can be achieved.
However, there will still be losses due to core and magnet heating,
even if no power is drawn from the coils. Further, as soon as the
coils draw power, the motion of the magnets is retarded because the
energy from closing the flux path is less due to back emf and thus
reduced force.
Horace Heffner
http://www.mtaonline.net/~hheffner/
