Sterling(beta) refuses to work at all after 7 builds.. Help!

Discussion on Stirling or "hot air" engines (all types)
Insainhouserecords
Posts: 47
Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Wed Feb 20, 2013 8:30 am

Because the balloon is the energy transferer right? The balloon helps "push" the crank along with the flywheel. It's the only two spots recieving energy. The displacer is in a wire that falls on its own therefor cannot transfer energy upwards. Right?

Hopper
Posts: 54
Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Wed Feb 20, 2013 8:12 pm

Insainhouserecords wrote:Because the balloon is the energy transferer right? The balloon helps "push" the crank along with the flywheel. It's the only two spots recieving energy. The displacer is in a wire that falls on its own therefor cannot transfer energy upwards. Right?
Yes. The displacer's only function in this type of engine is to move the bulk of the air in the cylinder from the hot end of the cylinder to the cool end of the cylinder. The displacer does not provide power to the crankshaft. In fact it absorbs power from the crankshaft, that is the power needed to move it up an down. So if the displacer and its connecting rod are too heavy, the engine will not have enough power to move it up and down. That is why many engines use a counterbalance on the the crankshaft to minimize this effect.

All the power to your crankshaft in this engine comes from the rubber glove diaphragm.
You say your rubber glove diaphragm rises when the rod is disconnected but without enough power to turn the crank when the rod is connected.

Most likely reasons for this are:
Air leakage -- possibly around the displacer connecting rod or the other structural components where sealing is not complete. It take only a tiny bit of leakage to lose power on these very weak engines.

Friction: Most likely on crank bearings and rod bearins or again where the displacer rod passes through the end of the displacer cylinder. Engine should spin over for a few good revolutions when the flywheel is turned by hand.

Balance: If the connecting rods and pistons/displacers are too heavy, they will always fall to the bottom and hold the crank in that position. Try adding or removing weight from your flywheel until good balance is found. do this with the diaphragm disconnected from the rod.

Pics of your set up sure would help diagnosis.

Another thing to check is timing. The crankshaft must be made so the displacer crank is 90 degrees out from the power crank.

Insainhouserecords
Posts: 47
Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Wed Feb 20, 2013 8:24 pm

Thank all of you for all of your help! I'm sure and confident that I can make it work with your helps. I will be posting pictures to this engine in about 15-20min. Thank you!

Insainhouserecords
Posts: 47
Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Wed Feb 20, 2013 9:27 pm

The displacer is now made of light weight floral block foam with cardboard cutout for a bottom. I have a few more pictures of the crank and the PVC fixture if it will help you guys figure what the problem might be. Should the displacer touch bottom of the can when the crank is at its lowest point and the top at its highest?
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Displacer vs can...
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Crank top view
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This is the tin beta stirling attempt 8(even if it don't work it looks good.
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Insainhouserecords
Posts: 47
Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Wed Feb 20, 2013 9:31 pm

These are a few more if the make up
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Insainhouserecords
Posts: 47
Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Wed Feb 20, 2013 9:33 pm

Sorry if this is too many pictures. These are if the crank.
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Hopper
Posts: 54
Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Wed Feb 20, 2013 9:45 pm

No, you don't want the displacer to touch the can at top or bottom. There should be a small airspace space there.
Likewise the displacer should not touch the sides of the can, there needs to be a small airspace all around so the air can flow past as the displacer goes up and down.

I would question the use of two cans here. It seems the lower can is just deadspace, which greatly reduces engine efficiency.
The the other can and rubber glove engines I have seen had the plastic elbow coming out the middle of the upper can and no lower can. Flame was applied to the upper can.

See the comments and link I put on your other thread.

Hopper
Posts: 54
Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Wed Feb 20, 2013 9:51 pm

Here is the single-can engine I was talking about in the last post


As you can see, the elbow goes on the top can, flame straight under it. Second can is used only as a stand, not connected to the piston or displacer.

Heres some vidoes on how to build them

Insainhouserecords
Posts: 47
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Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Wed Feb 20, 2013 9:58 pm

No your not looking at the pictures correctly. The only real difference is your sides of the top can are cut out. My stand isn't pictured. The top can just holds the crank. The top cans bottom is the bottom cans top.

Hopper
Posts: 54
Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Wed Feb 20, 2013 10:21 pm

Insainhouserecords wrote:No your not looking at the pictures correctly. The only real difference is your sides of the top can are cut out. My stand isn't pictured. The top can just holds the crank. The top cans bottom is the bottom cans top.
OK, I get it now.
IN that case it must be a matter of reducing friction and increasing sealing.
Crankshaft looks a little wobbly, does it rotate freely?

Insainhouserecords
Posts: 47
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Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Wed Feb 20, 2013 10:38 pm

With a swift spin on the flywheel with your fingers it rotates nearly 5-6 spins. I'm going to redo the displacer with a tighter fitting one and seal the top can to the bottom can other than that.. It makes no sense to me why physics aren't working.

Hopper
Posts: 54
Joined: Fri Feb 08, 2013 6:54 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Hopper » Thu Feb 21, 2013 6:59 pm

Insainhouserecords wrote:With a swift spin on the flywheel with your fingers it rotates nearly 5-6 spins. I'm going to redo the displacer with a tighter fitting one and seal the top can to the bottom can other than that.. It makes no sense to me why physics aren't working.
Displacer needs to be a loose fit, not tight. Air needs to move past it as it is displaced from one end of the can.

Yes, the top of the displacer can MUST be sealed, or your air will all leak out there instead of pushing the balloon upwards.
Again I cant tell from your pics the current overall desgin, but it looks like yes you need to seal the top tin to the bottom tin with silicon sealer or duct tape etc. I would say this is your problem.

Also the small hole in the top of the displacer can must be a a good seal on the fishing line or wire that the displacer hangs from. Some designs use a piece of tape with a pinhole in it for this seal.

Insainhouserecords
Posts: 47
Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Thu Feb 21, 2013 7:16 pm

It really is just a pain. I added 2inches of more displacer to fill the chamber all but an inch. I did this thinking that the less air the more pressure. I shortened the displacer crank slot to almost 1/2in so that the throw of the crank is almost 1in, giving the displacer 1/8-1/4 inch top and bottom to "float" on with all sides 1/8-1/4in gap for easy movment up and down. The diaphragm crank slot is 1/2 size of displacer crank slot. It is sealed around the can and with the fishing wire. Still nothing!!! No work-a! Their has to be a magic ratio for these things to work. That's what nobody will divulge. Truth is the size of the displacer vs size of can= crank arm length. Problem being is that these seem to be well kept secret facts and with out the proper ratio it will be impossible. If anyone has a tin can engine please give the thickness of your displacer and the length of your crank throw on both sides.

Junkie
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Location: England
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Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Junkie » Fri Feb 22, 2013 2:38 am

Have seen your photos, I would say it's probably that rubber seal that's letting you down. Is that blue piece of rubber made from balloon or something similar ?

Try using a piece of inner tube, or even better making a tiny hole using a sewing needle (those cans are probably too thick for that though) or 0.6 mm drill.

Also, a foam displacer won't work with a fishing line connection, it needs to be porous wire wool to allow the air to flow through, otherwise there's too much resistance to it falling through the displacer chamber.

What are you using to seal the two cans together ? I can't see any silicone in the pictures.

Hope that helps,
http://www.scraptopower.co.uk My web site, Stirling engines and AE stuff.

Insainhouserecords
Posts: 47
Joined: Fri Feb 15, 2013 3:18 pm

Re: Sterling(beta) refuses to work at all after 7 builds.. H

Post by Insainhouserecords » Fri Feb 22, 2013 6:41 am

I will replace the balloon cutout with inner tube. I'm just not sure that's the problem. Put it this way when I take off the balloon and blow with force into the PVC pipe, its air tight. It think it has to do with crank throw length or maybe the displacer size. I didn't know air had to travel thru the displacer, only around it. I will go back to the wire wool. I been thinking of also going to a solid piston like a coke can inside my tin can but now you say air needs to flow thru, that's idea is also in question.

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