Membran type engine

[Henrik]

Hi

Ive been playing with a little idea by using membrans to guide the air from hot to cold and back..

http://bylaug.stolbro.dk/HenrikPrivat/M ... gV1_00.JPG

When the displacer(sealed) move upward it push the air to go through the small blue pipes(coldside). When the displacer goes down it push the air through the red pipes(hotside). The powerpiston is connected to the displacer champer through the the topparts! I hope you can understand my print.

What do you think.. will my little stirling work? or have I made something wrong? Nevermind the flywheel stuff it has been done in haste, its timed 90 degress

Henrik

[Cartech]

Interesting design, if I get what I see, the displacer only moves air back and forth through flap or reed type valves? Hot and cold is only at the "pipes"? I'm still trying to wrap my brain around it but it might work. I'm still trying to figure out how the piston gets it's ported air considering there is a top and bottom valve assembly, could this cause too much "dead air". -my thoughts

[Henrik]

I've seen the pipe idea used on a few power producing engine where the hot end had to be put into the fire.. like this engine
http://www.elec.canterbury.ac.nz/docume ... irling.htm

But I wished to do that with the cool side too. so I had to guide the air around, so i came up with the idea of using the flaps, because they don't use any mechanical action to work.
By letting the air go through pipes gives the biggest surface.

I've thought about the 'dead air' thing too. But I don't think its gonna be a problem because it's such a small % of the total volume.

I've made a better picture of the portsystem. It should explain better.
http://bylaug.stolbro.dk/HenrikPrivat/M ... 1_00_a.JPG

[Cartech]

I'm wondering how your displacer will fit? Very close to move the best amount of air? If so, won't it cover the power piston port at that end of the stroke? One idea I have would be to install a small spring loaded valve in the displacer that opens when it reaches that end stroke, then it would allow the air pressure change to reach the piston. Something like a mushroom valve and give it a long stem to keep the duration a little long. I think contact of such a valve with the cylinder end would be minimal friction. You could then have a nearly contacting displacer piston or maybe even a low friction graphite one? I also like your software your drawing with, what is it? If you can use it with a CNC mill, your all set. I have thought of a couple designs that keep the hot and cold side apart but remember, it's not just hot and cold, the pressure will change up and down within the whole displacer chamber. Your flap valves will have to deal with this yet not cause too much restriction. I think maybe you should loop your tubes to keep them long (like the letter "C") and shorten your chamber and stroke on the displacer. Make it wider if you want to keep that same volume.

[Henrik]

I think Im gonna rebuild my engine and use a big displacer and shorter stroke as you say. The "C" pipes has been my idea all the time, but it was easier to "paint" the pipes as I did. My next project will be a two cylinder stirling using the same heatpipes and power piston but timing will be 180°.
The program im using is solidwork.

Cartech.. thanks alot for all your feedback.

[Cartech]

Glad to be some help. I have limited experience but some possibly useful insight :) I'll have to look into Solidwork, I do all my drawing by hand still.

[Henrik]

I did my drawings on my friends computer, who use it trough his job. It should be pretty expensive.

Henrik