Avoiding sticky point by making magnet dissapear.

[broli]

So I was quite simply thinking of the dreaded sticky point known in pm motors until I started to think along the lines of making the rotor magnet "disappear" for a slight moment to avoid the sticky point and then make it "reappear". And what a better than to use magnetic shielding.

Quite simply when you approach the sticky point some shielding mechanism shields the magnet so it enters effortless and a very short moment later unshields it to let it speed up. The idea seemed so simple that I wanted some opinions as to wether I overlooked something  .

[resonanceman]

So I was quite simply thinking of the dreaded sticky point known in pm motors until I started to think along the lines of making the rotor magnet "disappear" for a slight moment to avoid the sticky point and then make it "reappear". And what a better than to use magnetic shielding.

Quite simply when you approach the sticky point some shielding mechanism shields the magnet so it enters effortless and a very short moment later unshields it to let it speed up. The idea seemed so simple that I wanted some opinions as to wether I overlooked something  .

Do you mean like this ? 

http://www.rexresearch.com/gary/gary1.htm


gary

[Onevoice]

Yes, that could work. By nature, magnetic shielding using thick steel, mu metal etc. is only partially effective. It doesn't actually block a magnetic field so much as it absorbs it. the shield is attracted to the magnet instead of the ferric material on the other side from the shield. Because of this, you couldn't for instance shield two magnets from each other but you could shield a magnet from a block of steel. You also need to work out how to remove the shield, since it will then become stuck to the original source magnet. Steorn has a patent on a low-energy actuator construct whereby a shield can be moved in and out from a magnet with little energy loss because it is being moved from one magnetic field into another magnetic field of equal strength. So long as your motor design would allow for a secondary magnet to be used like a holder for the shield when its not being used to block the primary field and so long as your design uses magnet-to-metal rather than magnet-to-magnet interactions, then you might be able to get something to work.

You should develop the idea further a post it out here for others to critique

[broli]

The idea was fueled by this shield;

http://www.overunity.com/index.php/topic,4528.msg96303.html

So there shouldn't be a problem of the shield being attracted.

[Onevoice]

I played around with something similar to that a while back in my first failed pm motor design. Note that he is using shields on both magnets. You will still need to figure out some way to move both of the shields in\out with minimum force. If these are mounted on a rotor and stator then it will take extra mechanical effort to move them both at the appropriate times - IE two separate mechanical systems. Kewl idea though. I'd like to see what kind of overall design you're working towards.