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Heres some photo's of a little experiment I did. It's a stirling engine where the displacer is moved
by some magnets, the idea was to eliminate the displacer rod so that there is less chance of any
air leaking out. The displacer has a magnet on it's end which alternately attracted and repelled
by the curved magnets. I tried lots of different angles of the magnets relative to the power piston.

It did not work - I think that it doesn't have enough power to overcome the attraction between the
magnets. The bearings and piston are very smooth (graphite dash pot freebie!). Sometimes it will go 3/4
of a rotation under it's own steam and then get stuck

I suppose it should have some kind of guide for the displacer as it just slides along the bottom of the
beer can and makes alot of noise when it bangs into the end of the can! The end beer can is filled with
cold water for cooling.

Junkie wrote:Heres some photo's of a little experiment I did. It's a stirling engine where the displacer is moved
by some magnets, the idea was to eliminate the displacer rod so that there is less chance of any
air leaking out....

Hi,

I had, (or have) a similar idea, for more or less the same reason, but instead of eliminating the displacer rod, the idea was to solder or weld a tube (non-magnetic or non-ferrous metal) that would go through the displacer chamber (air tight of course) and attach some magnets to the end of the displacer rod and inside the displacer itself, which would have to be doughnut shaped to fit around the hollow tube.

Probably some sort of ball-bearings to keep the displacer centered on the tube and prevent it from rubbing or binding would be needed.

Here is a rough cut-away sketch of the idea, but I haven't tried it yet, so I don't really know if it would work or not.

Tom

That is a better idea I will have to try some time. I think that it definitely needs some guidance for the displacer, it'll probably grind its way through the cans after a few hours .

Junkie wrote:That is a better idea I will have to try some time. I think that it definitely needs some guidance for the displacer, it'll probably grind its way through the cans after a few hours .

Maybe your magnet setup would work better with a pivoting vertical displacer something like the "MC Easy Stirling" you posted on the other thread. At least that would eliminate the problem of the displacer "dragging".