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Dazza

The mechanical construction side of my Stirling engine project.

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I am posting the mechanical side of my project here, as there was interest in this part of my project, and the electronic side of this project is posted here(http://www.electronics-lab.com/forum/index.php?topic=3343.0)

I'll have a go at trying to explain how this engine works for those who are interested, first of all it's important to have a perfect seal, when heat is applied to the bottom chamber (the loosely fitting balsa wood piston is at the top") the air inside expands forcing the diaphram upwards, as a result forcing the push-rods upwards creating a half turne of the crank, the piston which is connected via a piece of fishing line to the crank, at the point of which is to a 90 degree phase angle in relation to the push rods, descends downwards displacing the hot air from the bottom of the chamber to the top, and as a result cooling the displaced air which has the effect of drawing the diaphram inwards creating a complete revolution of the crank shaft.

This Stirling engine design is relatively simple to construct, and I think it is a very good place to start for experimenting, however I have found one major problem with this design, which is the whole in the diaphram connecting the piston to the crank, it wears out far too quickly.  I do have some ideas to remedy the problem, but to do so I think it will be best to scale up this Stirling engine a bit, because it is just two small and fiddly to try to implement a reliable ceiling solution. Another problem is, the crank shaft needs to be of a much heavier gauge, I found that I need to bend the crank shaft back into shape, each time I needed to replace the diaphram, so basically the crank is getting more and more out of whack each time I have to straighten it, resulting in increased friction and reduced efficiency.

I have attached a short video clip of my Stirling engine ;D.

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post-2744-14279142250945_thumb.jpg

Sterling_Engine_video.zip

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Hi Dazza,

Wow! Nice video, I like this gizmo! ;D  I have seen a couple on the net and I have been thinking about trying to build one. The sealing of the piston and the membrane, what are they made of? Is the membrane exposed to high temperatures or could it possibly be made of leather? If you are building a bigger one, wouldn’t it be nice with two “cylinders” for a smother run or maybe it’s not possible to make a two cyl crank? 8)

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Hi Ante :),

Yes it's cool isn't it ;D, when I first fired it up I just watched it takeover in amazement :o, I was quite pleased with myself 8) ;D.

This is where I got the plans from (www.bekkoame.ne.jp/~khirata/english/make.htm) the membrane is a balloon and the piston is made of layers of balsa wood, there needs to be a space between the piston and the cylinder, to displace the air.  I'm pretty certain leather will not work for many reasons :(, but I'm thinking silicon rubber may work well, I have a lot of improvements/modifications in mind that I am going to try, I will post my progress with this project here.

Go for it Ante make one, it's well worth it, this project is definitely a good place to start 8).

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Hi audioguru,

It sounds much noisier on the video ;D. you should make one Audioguru, you could mount it under your porch and when your skunk sleeps under it, it will start-up and scare it off :o ;D ;D.

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Hi Dazza,

Yes I might try it out if I can make time for it! I have seen this site and it’s interesting for sure. I am going to read it through in detail to get the work cycle right, seems the angle of the crank is very important. Maybe you could try a latex glove instead of the balloon, they are made from a much better quality rubber. What do you think; will it run with two cylinders?

BTW. In a moment I have the first part finished in my hand.....  an empty beercan will do as the cylinder won’t it? ;D

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Hi Ante :),

No, I very much doubt an empty beer can will work :(, although may be you should prepare a couple more, just in case they come in handy for some think ;D.

Yes it will run with two cylinders ;), but I suggest making two identical Stirling engines, and then joining their cranks together at the right phase angle.  Yes I did try using a latex glove, but it didn't work because it was not flexible enough :(, a solution for this could be to use a wider diameter cylinder whilst maintaining the same height.
I'm thinking silicon might be a good choice, because it has high flexibility even when using a thick layer for strength, as well as it can handle very high temperatures, not that it really needs to.
At the moment, I'm testing a new ceiling solution for the connection from the crank through the diaphram to the piston, and it is working :D, but the problem is with testing it for reliability, I had to keep replacing the diaphram/balloon far too often,and it's getting very annoying >:(.

If this ceiling solution proves to be reliable, I will move on to making a new Stirling engine with many more improvements, and I will post my progress here with some picks of course ;D.

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Hi Dazza,

I have seen a picture of one made from a Cola can and I don’t drink much of that stuff. How about a six-pack ehmm..  I mean a six cylinder engine? ;D ;D
The silicone, is it something you will make yourself or is it from some other product you are cutting to size? If you are lucky you might find better quality balloons from another supplier. What are you using for connecting rod bearing and main bearings?
I would like some close-ups as the work proceeds!  8)

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Hi Ante :),

The way it's looking, I may have to make my own silicon matting from a tube of silicon, I'm not sure how that'll turn out, it could get very messy :o.

I think you're right Ante, there are probably better quality balloons that are stronger and thicker, I know of a couple of places around town that could have them, I'll have to go and have a look see.

The connecting rods are just timber, and there are no Barings just some Greece ;D.

Ante, my ceiling solution idea works and I'm confident that it is reliable, I will provide a close-up pic of it tonight ;).

I have many other improvements for this design that I know will work 8), but I'm not sure when I'm going to get the time to put it together :(, if you're interested Ante I will concentrate my efforts on drawing up my improved design, with as much detail as I can for making the parts and putting it together, the only equipment that is really necessary for making it is a drill press?

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Oops, I didn't get the chance to take some picks today :(, I did try just now but it was too dark and they didn't turn out, :'( Sorry, I will take some better pic's tomorrow in better light, and upload them tomorrow night.

Oh,and I should mention that, Yes it is Friday night and I'm on the turps :P :P :P :P :P :P, and even though that last bit rhymes ;D it was not intentional but still I think it is amusing ;D ;D ;D.

[move] :P ;D :P ;D :P ::) :P ;D[/move]

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dazza thats a nice construction job there i bet you could do it on a larger scale useing your hydrogen gass generator and a cylender block from a car and the pistons and crankshaft my partner said your clever as i showed her your hollywood video clip

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Hi Alun, steven :),

Good idea Alun ;), I would never of thought of using a swimming hat ;D.

steven, yes that's the plan for later on down the track, having a Stirling engine fuelled by hydrogen ;D, but I first must succeed in getting a standard car engine/combustion engine, to produce its own fuel "hydrogen from water" to run on 8).

I'm finally posting some picks, Sorry for the delay :(.

post-2744-14279142262613_thumb.jpg

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:)hey daza that looks good i allso have the plans from the internet to biuld these nu yours is larger by the looks of it, im impressed at how neat your construction work is , i once thought it would be a good idea to biuld something similiar but useing magnets  in an oposeing way against each other  like a perpetual motion machine  but i think its a long way off till i test this idea i have. , i take it youve herd of the liuqiud piston pump  it runs off the heat of sunlight like your stirling angine runs off the heat from a candle

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Hi Dazza,

I found this, I don’t know if you’ve seen it. How to generate electricity with a Stirling engine!
http://www.windstuffnow.com/main/stirling_generator.htm
Looks very nice I think! :D

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