Ky Ko fan - Pakistan style

[Tom Booth]

I saw this Stirling engine fan being offered locally (a few hours away) on Facebook marketplace.

Nearly identical fans are still being sold on Ebay, but adapted to run on propane. I thought this was one of those, but when I got it, it appears to be rather old and has the old type two wick kerosene burner.

It looks as though someone tried to light the wick dry, with no kerosene, by the way it is burned on the ends.

The fan does not really appear to have ever been used much, if at all. Looks like original, very old dried up appearing grease on the bearings.

For example, it has a break to stop the fan by pressing down on a spring-loaded metal rod that rubs against the crank. There is no sign of any wear whatsoever at the point of contact.

I wondered why anyone would buy a $500 reproduction fan (+$200 shipping) from Pakistan, then sell it on Facebook, for just the shipping cost.

Anyway, I wasn't going to look a gift hose in the mouth and snatched it up.

The engine itself seems to be - well, not broken in at all. Very tight. So much so I thought it was seized or jammed. Seems as though it has just been sitting in storage, probably for several decades I would guess. It seems it was only the dried up grease that caused it to be difficult to turn over.

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I'll probably need to clean off the old grease, but otherwise it seems to be in near pristine condition, though apparently rather old.

[Tom Booth]

I let the seller know the fan arrived ok, and also asked if he knew anything about the history of the fan:

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[Tom Booth]

I'm taking the engine apart. Curious what the displacer was constructed of. Glad I did.

Part of the problem was that apparently the crankshaft and bearings got knocked out of alignment during shipping, unless it had always been like that, but I doubt it. So the connecting rods were not aligned properly, causing some binding

https://youtu.be/QQI0kYp2seU

In the earlier lower photo, it can be seen that the bearings have been pushed out, not centered in the mounting bracket and the piston and displacer connecting rods were no longer vertical but we're angled off to the left, same as the bearings.

Luckily the engine is quite solid and seems to have come through it. Just needed to loosen the bearing holders a bit and slide the entire crankshaft and bearings back into position

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[staska]

Heh. Remember a work style seen on youtube in Pakistan.. Ok - just fits a on loose side, some loctite would help.

[Tom Booth]

After some time, I found that I was not able to completely eliminate the misalignment of the bearing mountings, bearings and connecting rod.

I finally concluded that at least one of the mounting brackets had been installed backwards and the crankshaft assembly would have to be taken apart further to get it turned around.

In the process of doing that, I discovered that the pin/bolt holding the power piston connecting rod to the crankshaft could not be removed in any way that made sense and I would have to grind off the head and replace it, but also this bolt had no bearing sleeve and was loose (wrong threads) held on with extra nuts that also nterfered with the connecting rod alignment.

It became obvious that at some point in the life of this fan it had been subject to a "repair".

The original pin must have broken, come loose and got lost or wore out and someone took the crankshaft out and replaced the pin with a cheap bolt that did not have the right threads and no bushing or shoulder or anything so that the crankshaft bearing was ridding directly on the bare threads.

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At least I can't imagine that bolt is an original part (and the mount got turned around the wrong way somehow).

This probably would not have entirely prevented the fan from operating, but would likely have caused excessive wear, possibly some continued binding and just generally a lack of any smooth operation. The loose bolt in the bearing and general misalignment would also cause some knocking and scrapping noises, which actually can be heard in the previous video. While turning over the crank the threads on the bolt would be scratching across the inside of the bearing. I had been wondering what that scratching noise was.

Anyway, nothing too major, just have to repair the repair.

My first assessment that this fan had been hardly used was obviously incorrect.

[Tom Booth]

I haven't really done anything to this engine, other than take it apart clean it up a little and put it back together.

I did have to make one new gasket.

It still needs the bearing on the power piston connecting rod fixed, which is what is making the clank clank noise as it runs.

At some time someone must have replaced the crankshaft pin with a bolt which is thinner than the original pin so the bolt rattles around in the bearing a bit.

The bearings are also still pretty gummed up with old grease and will need a good soak in some parts cleaner.

But, I just wanted to put it back together to see if it would run


https://youtu.be/svYkBk1WvxU?si=dSE5D10aqNVDY1EY


I would have used the kerosene burner, but I used all the kerosene I had in the salamander heater while trying to get the 3k engine started.

I did not have the heat on, and it's winter, so the shop was only about 45° F and the engine was stone cold so it took a bit of coaxing but it did finally run.

[aloneagain55]

It seems odd, that no company or China, has decided to mass produce these , at much lower costs. They are not that complex...id guess the most complicated things would be the proper tolerances/ alignment...but as far as individual parts are concerned, nothing expensive involved.

Surely there would be a solid market for these, if they were made to be about 2x the size of a normal $25 peltier woodstove fan ? Twice the size and at least 2x more air movement on top of a woodstove , and I bet they would sell like hotcakes on ebay, for $100 or less.

[Tom Booth]

It seems odd, that no company or China, has decided to mass produce these , at much lower costs. They are not that complex...id guess the most complicated things would be the proper tolerances/ alignment...but as far as individual parts are concerned, nothing expensive involved.

Surely there would be a solid market for these, if they were made to be about 2x the size of a normal $25 peltier woodstove fan ? Twice the size and at least 2x more air movement on top of a woodstove , and I bet they would sell like hotcakes on ebay, for $100 or less.

One annoying aspect of a Stirling engine fan is it needs to be manually started, but there are safety/liability issues. A cage around it, like most fans makes the blade inaccessible for easy starting.

I've been thinking lately about a bladeless, "air amplifier" type stove fan. Dyson might have something to say about that though.

That would help with the safety issue, but start up could still be a problem.

[VincentG]

Pretty cool, I've been keeping and eye out lately for a good deal on something like this.

What is the bore and stroke of the pistons?

[Tom Booth]

...
What is the bore and stroke of the pistons?

I'm glad you asked as it gave me an excuse to take the engine apart again and look deeper into its construction.

I must say, although the bearings are probably still a little gummed up I wasn't especially impressed by the power of this engine.

Looking at the power cylinder, while taking measurements:

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There is quite a, IMO, unnecessary "combustion chamber" or hollowed out space in the cylinder head. The piston also does not even reach the shoulder, so altogether there is about a 3/8" plus "dead space", about 2" diameter. Add that to the transfer tube and the displacer chamber "dead space", and, well, there is some room for increasing the compression ratio just by filling that "combustion chamber" with some high temperature epoxy or something. Of course, a Stirling engine does not have any combustion so I see no real purpose in it being there, unless you just want lower compression for some reason.

The displacer I found also comes up about 1/4" short of the bottom of the displacer chamber.

The power piston and cylinder are machined to incredibly close tolerances. I could not see and difference between the power piston OD and the power cylinder ID

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They both read 2 1/10" as far as I could tell with my caliper. Sorry if you prefer metric, but it's the only set of calipers I have.

The displacer cylinder measured 2" diameter and the displacer itself 1 7/10" which seems like an excessive amount of clearance for this type engine as well.

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[Tom Booth]

The stroke of the power piston is 1-2/10"

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And the displacer 1-7/10"

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If you think of anything else let me know.

[Tom Booth]

The displacer BTW, is one heavy duty steel cylinder. Hollow, but otherwise not what I would call light weight.

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Also, seems a bit rusty. I'd have to check with a magnet to be sure, but I'm guessing NOT stainless, so very likely conducts heat quite rapidly.

Also, the length of the displacer, being highly conductive, (I'm assuming at this point, maybe I'll do some tests), probably contributes to the engine being able to run at all by effecting SOME temperature gradient. Opinions differ I suppose, but in my experience and testing, I don't think that the annular space contributes much to heat exchange, It could serve as a kind of regenerator to some extent, but basically just WARM air coursing up and down the sides of the displacer not doing much of anything.

A non-heat conducting, shorter, lighter, closer fitting displacer that actually goes all the way to the end of the displacer chamber, displacing ALL the hot air on the down strike would likely produce a vast improvement in performance.

Of course, the entire engine, as well as the power piston is cast iron and steel. Certainly very durable and built to last, but thermodynamically, it just soaks up and conducts away enormous quantities of heat. In that "first run" video above, the fan would slow down to a stop almost immediately if the propane torch was not held close supplying the maximum possible amount of heat input. That can't all be attributed to the cold workshop. Theoretically the cold should increase the temperature difference making the engine run better.

Being of a Gamma type design, not much can be done about the large dead air volume in the displacer chamber, which IMO leaves no excuse for allowing additional avoidable dead volume elsewhere.

Overall, a very nice, well built engine, but could likely see tremendous improvement in power to weight and size ratio with a few changes.

[Goofy]

This one looks a just like the Ky Ko inside, though "electrified" :

https://www.ebay.com/itm/204296343706?h ... R_a3i_OtYw

But only 15 watt for such a large engine ? ? ?

[Tom Booth]

This one looks a just like the Ky Ko inside, though "electrified" :

But only 15 watt for such a large engine ? ? ?

Yes, that is actually, exactly the same engine, by the same builder/s in Pakistan (I believe anyway).

I think the original original Ky Ko fans were produced in Europe ? Not really sure, but then some castings were taken and it was reproduced for a. Long time in Pakistan, and still is actually. So yes, that is basically the same fan engine turned into a generator.

See this old thread:

viewtopic.php?t=1178

From first post:

From what I know about the design of the “Big Stirling engine”, they started building these type of engines 40 years ago by their grandfather who imported a “KyKo fan” from Europe. Now they have started rebuilding them with their own modifications.

[Tom Booth]

Well, the displacer is definitely not stainless.


https://youtu.be/L-DitxOkMFo?si=8-I8TMdRp-xxBZ3i