First let me say this is the best design so far that I have seen on youtube so far (except for the commercial ones). So many people over look the importance of heat exchange when they build their stirlings, both in and out. For all intents and purposes, you got your displacer right. About pressurization. The back end of the piston also has to be pressurized. Its pressure should be between the pressures when the gas is hot and when the gas is cold. Good luck.
Wow, this is really frustrating! But do not be discouraged, so many years you is in this fight and I'm sure that will solve this problem. Congratulations on such persistence. Leandro Wagner.
Thanks, Leandro! As I'm sure you know, failures are an inevitable part of the process of building these engines. It's frustrating, yes, but seeing the engine run, even briefly, is always motivating.
Wow that looks amazing!!! Looks like it's got some real potential for a lot of power out put. And it looks pretty efficient too, considering that you don't even have the whole displacer insulated or glowing red hot. All in all just an awesome build and I can't wait for the results on power measurements and future runs! Thanks for sharing and keep up the great work!
Excellent work there! Unfortunately getting the bugs out of something is a real pain.You will improve it I am sure,and I like the brake chamber diaphragm,very good idea!!
Very nice engine Approtechie! Just waiting for the 'more to come' I really like to know what power you will gett when you get it running properly. I'd also like to make a bigger engine, but that's for the future, first i'm going to completely rebuild my last engine.
its a damn nice engine........... why didnt i think of that with the diaphragm.... a truck airbrake, brilliant. I wonder if it would be powerfull enough to run a small generator off of, like them 4 stroke gasoline 2500 watt generators. (or perhaps 1500 watt would also be nice already)
Looks great. For my solar thermal powered car I need a 4hp/3kw stirling engine. It would be great if you could attach a generator to the motor and get a power value. Efficiency is also important. Thermal to electrical efficiency you can measure the heat used and the electricity producted.
A 3KW Stirling engine would either be huge or high-tech running at high pressures and high temps. If you look at the videos of the ST-5 you'll see what I mean. [www.stirling-tech.com/stirling/stirling.htm]
This is awsome! Congratulations. As I told you on your other vídeo, I realy like the bell crank to drive the displacer, and the main reason is because it reduces size and rod angle problems. Nice improvemnts you've done lately on your engines by increasing internal pressure, and that advantage can be seen at the vídeo (specialy at the broken linkage part... lol). Hope you fixe it soon. Not sure if this could be a good idea, but you can increase torque of the bell crank, just by increasing one of the sides of the lever/L (the one that links to the connecting rod). This way, you may be able to reduce some stress from the main crank, and also reduce the effects of friction losses on the crosshead... Just an idea. I'm working on a beta engine now, and it also uses bell crank mechanism, but I may need some time to get progress on it. Congratulations, merry crhistmas and happy new year! :-)
I did try just a sheet of rubber, then two sheets, then two sheets with fabric between, and all of them blew out. This air-brake diaphragm is the answer, and works really well.
***** well thats what i mean, a piece of rubber, but i didnt know it was from an air-brake, thats a nice idea. i've been wanting to try a pneumatic tire. i remember the Artattacks used tires instead of piston/cylinder for an air pump in an episode of Junkyard Wars.
Rinoa Super-Genius My very first engine used two half-tires (didn't run unfortunately), and I've often thought of using small tires since, but I keep ending up with a lot of dead volume unless the tire can be partially filled with something to take up the extra unused volume.
Michael Crumpton I've tried those, too. In this case, the air brake diaphragm has turned out to be the best solution. The accordion boots flex and warp in and out too much. You have to put braces in each fold, both in and out, to prevent that, then you end up with wearing at those points. Heat also causes them to get pretty soft.
Excellent idea using the Air Brake actuator diaphragm. One of the best sources of parts for any project is looking at automotive sources as the parts are made to with stand long usage and a wide range of temperature differentials. Hats off to you. Will you be posting any plans for this engine?
Thanks for posting. I hope to make a mid-sized engine one of these days. imo, the reciprocating components are too massive for sustained high-speed operation. Otherwise, its great work. cheers
Hi thats really nice , may I ask do you have plans for this lovely machine, If so can you put them up please, I would love to build one of these. Thanks for showing it on here.
Very nice work, looks so smooth when running. I wonder if adding pressure to a diaphragm is a good idea though as there is no pressure on the other side for rebound/balance and if that would simply exert onto the displacer rod? Can't wait to see more experiments and where they take you, thanks for shearing and Merry Christmas.
the pressurization doesn't really stress the displacer rod much, more the power piston linkage. I think I had a minor misalignment of the rod and perhaps not enough support for it, esp. at speed. Also the guides for the diaphragm were starting to bend a bit and that likely messed up the rod guide.
Hello first of all well done mate second im not all that knowledgable on sterlings but if you put a fan or blower type assembly on the crank aimed at the or channeled at the cool part of it would that increase efficiency ?
+dennis buckner Thanks, Dennis! The water cooling seems to work well and pulls very little power compared to a fan. If no water cooling was available then, yes, fins and a fan would be best.
BOOM, lol, sorry to see of you dismay my friend,, we in the shop see a lot of broken efforts that the non do ers never feel, wishing you luck, and i wish i had yer fly wheel,, doesnt fit my lathe,, ;) a friend
Odd that the displacer linkage would break, since the rpms were fairly low and the load on a displacer linkage should be fairly low too. Perhaps there was some friction that caused expansion and binding at the point of entry to the cylinder.
Hi, Michael! Good to hear from you! Yes, the diaphragm had two guides and the displacer rod guide was in the diaphragm itself. When I pressurized the engine the two guides flexed down and caused the displacer rod to flex down and bind up, actually bending it. That's when the linkage broke and it all came crashing to a stop.
No, it just increases the air density, the number of molecules that can exchange energy levels (heat) inside the closed cylinder. More air equals more power, so long as you can get enough heat in and out of the engine.
can these diaphragm engines work at higher pressure? i think you'd need two solid pistons if you wanted to pressurize the system, otherwise the bladder will just bow out
The diaphragm I'm using now is from truck air brakes and good for over 200 psi. The fasteners would likely be the first to give out. Pistons are certainly better for higher pressures.
How can i calculate easily a good efficiency? i mean.. there is any basic rule to follow like the right volume difference betwen the 2 cilinders without making too much calculations.. i cant messure the temperature of the hot cilinder.. that limits my ability to calculate the right volume and the right torque!
Zsolt Márkus I've not been able to keep this engine running long enough to do many measurements, and not enough time to work on it for the past few months.
Tem um lança-chamas aquecendo!!! Pra mim motor stirling foi criado pra ser usado em caso de extrema dependência de energia... e sim, em outras coisas.,.. Mas, se ele depender de velas pra ligar isso? NÃO VAI PEGAR NUNCAAA!
Looking so promising - this time it was not the diaphragm any more... Some speculation: -Did displacer rod broke because of rod jerk in linear guide or was it displacer itself that was hitting the wall? Additional pressure might bend diaphragm out of center line -> displacer linear guide is also out of the center line. Maybe linear guide might have its own small attachment plate on rubber that is not connected to power piston plate? In that way the linear guide line could be more flexible... Diaphragm seems to be other way round than in original use? I believe that these are designed other way round and it might hold better the center line with internal pressure... Lots of info about diaphragms here: www.simritna.com/news/brochures/Diaphragm_Engineering_and_Design_Manual.pdf Nice work!
Eki, the piston under pressure started flexing down, bent the guides and thus the displacer guide, causing the displacer rod to bend and the whole thing to seize up, break the linkage. Yes, I may have to design separate guides, or a whole different linkage, I'll see. Diaphragm is in correctly for internal pressure and works really well. Thanks for the comments!
This is amazing.. By the way plz check my new video of 4 cylinder stirling..I have tested 2 of them..Still 2 more to go until final crankshaft is used..Counterweights are used in my test wooden crankshaft which have reduced vibrations and increased smoothness. I would replicate the crank with brass bars once testing is completed..Plz share your thoughts...
