Stirling Cycle engines

Not sure if this will help, but hackaday had an article on building your own Stirling engine out of soda cans. Probably won't give you any info as to how to fix your specific engine, but should provide some nice primer info on how the contraption works:

http://www.hackaday.com/entry/1234000750073459/

About all I remember about Stirling engines is that they are based on the heating of air to operate, and can require very small temperature differentials to operate. It's one of those things that I'll love to get some time to tinker with (I do some machinist work at home). Anyway, that's not the helpful part- take a gander at Lindsay Publications (lindsaybks.com) They've got several books on stirling engines- from design on up. At the very least you might see a discussion of a similar design and get some ideas. Failing that, I work at an engineering university and might be able to find some references, should you like.

mike

Someone from another forum I post on once used the exact same model engine I have and he suggested the timing might be off. I'm going to rotate it 180° and see if that helps.

I would like to know more history about this enginge in particular. The box has a return address for a place called "Solar Engines" that no longer exists.

Dr. Bob,
I just did a quick google.. which I'm sure you've done, and turned up that Solar Engines is now a division of a company called PM Research Inc. They have a webpage and catalog and list something called their "original" solar engine. Perhaps this is it, it looks a lot like your pictures. Here's the link:

http://www.pmresearchinc.com/store/customer/home.php?cat=5

Hope this is it! Looks really cool...

Mike

That's it exactly! Saweet! Thanks.

PS: Dr. Bob sucks at Google

I'm glad that turned out to be the right one! Lemme know if you need any engineering literature.

Mike

I did some more work on it, but I still can't get it to run. It's trying real hard now, but jsut won't get there. I need to find a way to take it apart.

I think I will write to the manufacturer and see if they have any advice.

That's a neat little toy you have there. Wish I had one. ;^)

I'm guessing looking at the engine that it's a "gamma Stirling":

http://en.wikipedia.org/wiki/Sterling_engine#Configurations

Which would make the large cylinder over the burner the displacer and the smaller one the power piston:

http://travel.howstuffworks.com/stirling-engine2.htm

Googling seems to indicate *the* big problem with toy Stirlings is air leaks. Given it's an "old" engine I'd wonder if there might be some plastic seals or rubber on the inside of the the cylinders that have deteriorated? It'd be really handy to have an exploded diagram of it.

You could always try packing the top end of the displacer with ice while firing up the burner. Greater temperature difference means more power, after all. ;^)

--Peace

Last night I was able to take it apart further. The metal piece above the burner unscrews. The displacer piston was very clean. One it was open I noticed that it's very hard to turn the engine at certain points in the stroke. I think the power piston has galled the aluminum cylinder walls. I will take it all the way apart tonight and see what I can find.

I also found out that the hole above the power piston is supposed to be a valve. I always thought it was a relief hole for when they drilled the air channel, but someone told me last night that it needs a rubber o-ring and that it's normal for a little bit of air to escape. On mine, the rubber was shot so I replaced it with a nylon washer and screwed it down very tightly.

So at lunch I'm off to the auto parts store for the lightest machine oil I can find, the finest lapping compond they've got, and an O-ring that fits a 6/32 screw.

I got it running. WooHoo!

here's a little movie.

http://vader.inow.com/~drbob/temp/engine/engine.mp4

Hi Dr Bob - co-incidentally my students call me Dr Bob too, so there's a thing!
I see you got your engine working. The conventional wisdom is that any oil will usually be too viscous for application to the power piston. The recommended lubricant is powdered graphite. Just thought you might be interested to know.
Good luck
Dr Bob Howlett

I did use powdered graphite during the runs posted above. It only ran once though and I haven't been able to start it since. I suspect there is still more oil in it and I need to soak it in solvent to clean it out.

I am the Happy Guy having The user manual. I can send scan.
You must use a fine, light lubricant such as Marvel Mystery
oil, not a graphit grease.
To receive a scan send a mail to

Actually, believe it or not, I tracked down the company that made it. They still make them, and they sent me a new manual. Thanks for the offer though.

They said to use graphite BTW. I got it working by following their directions to the letter.