On 12/7/2007 9:57 AM, Horace Heffner wrote:
>
> 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
>
> Well, you can attempt to balance out the forces. See Figs 1-3.
>
> | | | |
> | M1 | | M2 |
> -------- --------
> ============= ============= ============= Shield
> motion --->
> -------- --------
> o| C1 |o o| C2 |o
> o| |o o| |o
>
> Fig.1 - Partial cross section of shield concept
>
>
> | | | |
> | M1 | | M2 |
> -------- --------
> ============= ============= =============
> -------- --------
> o| C1 |o o| C2 |o
> o| |o o| |o
>
> Fig.2 - Intermediate state of shield in motion
>
>
> | | | |
> | M1 | | M2 |
> -------- --------
> ============= ============= =============
> -------- --------
> o| C1 |o o| C2 |o
> o| |o o| |o
>
> Fig.3 - Shield open to M2-C2 flux
>
>
> The shield here is a rotor with gaps that rotate between magnets Mi,
> and cores with coils Ci, which are arranged in a staggered fashion as
> shown, such that the force of closing off one flux path is balanced
> by the energy obtained opening 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 shield is retarded because the
> energy from opening the flux hole is less.
>
>
> Horace Heffner
> http://www.mtaonline.net/~hheffner/
I see.
However, I just realised the shield in my drawing
http://web.ncf.ca/eo200/generator.html
is also subject to its own weight -- without the magnets it will tend to
orient itself so the gaps are aligned horizontally. So with gravity and the
right combination of magnet strength and shield weight distribution you
can minimise the energy required to keep the shield rotating.
Harry
