Have you seen the dual-power stroke mod Stirling made to 1816 engine?

[GaryEng]

I have been searching for days trying to find more info on how Robert Stirling managed to push the power piston in both directions.

If you know where I might see a drawing or read some text, please advise.

[Tom Booth]

I have been searching for days trying to find more info on how Robert Stirling managed to push the power piston in both directions.

If you know where I might see a drawing or read some text, please advise.

First I've heard of it.

There were many steam engines that had double acting power pistons, but I don't know of any such thing in any Stirling engine.

Do you have a reference source for this "dual-power stroke" Stirling engine?

[GaryEng]

http://hotairengines.org/closed-cycle-e ... rling-1827

"They took a leaf out of James Watt’s book and made the engine "double acting", meaning that it produced power on both the upstroke and downstroke.

Watt did this by valves; the Stirling’s by arranging two displacers, one to feed the foot of the power cylinder and one the top of it."

[Tom Booth]

Interesting.

That was, apparently, the 1827 patent.

It looks like there is some information here: though, for some reason my browser gave a warning for this website, which I ignored.

http://hotairengines.org/closed-cycle-e ... k-galloway

It includes this illustration from the patent showing what I assume to be the two large displacers on either side of the central power piston.

20b9ec93a5802b852c9ad9a58e05ca3ea1b25243-galloway-hebert-01.jpeg (128.98 KiB) Viewed 4534 times

If for some reason that page doesn't work, there is a cache on the Wayback Machine archive:

https://web.archive.org/web/20200606153 ... k-galloway

There is also details of the displacers and operating principles, presumably quoted from the patent also

Additionally there is a PDF:

http://hotairengines.org/patents/stirli ... 201827.pdf

These resources are on the same website you posted apparently, though I found the information in a round about way by searching for the 1827 Stirling patent mentioned on the Wikipedia page.

Thank you for bringing this to my attention. I never knew Stirling had patented such a duel displacer, double acting type engine.

[GaryEng]

You're welcome.

The sealing of the hot side must've been done much like a beta engine.

Routing of gasses and distribution of heat to both sides had to present new issues.

I'm confused as to how this is better than just making a dual system with one crankshaft.

[Tom Booth]

There is a top view and some additional descriptive information on another page:

http://hotairengines.org/closed-cycle-e ... ng-engines

f22d36e23d3971326432263712af906928d732ed-stirling-air-engine---dundee---top-view.jpeg (44.37 KiB) Viewed 4516 times

Apparently this engine was also pressurized and could use purified gases rather than air

These are developments I had formerly associated with modern high tech Stirling engines. I was not aware that the Stirling brothers themselves ever conceived of any pressurized hot air engine.

[GaryEng]

I read somewhere that Stirling used a pressure of 10 bar in this machine. This one achieved 45 HP.

I'd like to build something to achieve 20 HP.

I'm thinking of borrowing from some steam designs and adding crankshaft-contolled valves to cut off the dead volume, and perhaps steal some power to run antifreeze through jacketed cold sides.

I think it would be easier for me to use multiple betas rather than something like the 1827 design. I don't really grasp what he's done there.

I think the Ford-Philips design showed just how viable the 4-cylinder beta could be by putting out 200KW at 4500 RPM.

[Bumpkin]

Hello Gary. Actually Stirlings are naturally double acting anyway, but yes the pressurized variant using two displacers for one power cylinder has some advantages if you don’t want to seal and pressurize the crankcase. If you type “starspin” in the search bar above you’ll get some of the forum’s past thoughts - (for better or worse.)
Bumpkin

[GaryEng]

Thanks for the reply.

My issue is I cannot picture how he sealed the other side of the hot piston.

The connecting rod moves in an arc fashion, so I can only imagine he lengthened the hot cylinder, added a straight connecting rod with a seal which then pushed the original connecting rod.

Also, I'm wondering how he managed to heat both ends evenly.

[MikeB]

Gary,
sealing is actually one of the advantages of using a double-acting power piston - any leakage past the piston itself goes into the other half of the engine, rather than being vented, and then presumably leaks straight back the other way after 180 degrees.

Sealing the various con-rods is an inherent problem in most engines - a few designs (if they drive a generator) encase the entire engine for this reason.

[Tom Booth]

Thanks for the reply.

My issue is I cannot picture how he sealed the other side of the hot piston.

The connecting rod moves in an arc fashion, so I can only imagine he lengthened the hot cylinder, added a straight connecting rod with a seal which then pushed the original connecting rod.

Also, I'm wondering how he managed to heat both ends evenly.

I believe the connecting rod(s) have a kind of elbow hinge. You are basically right: "a (lower) straight connecting rod with a seal which then pushed the (upper) connecting rod."

Screenshot_20210927-135602.jpg (69.49 KiB) Viewed 4397 times

Similar to this connecting rods on this double acting steam engine, though vertical rather than horizontal.


https://youtu.be/jKR-EdmKlYE

In the patent drawing, the connecting rod appears to be straight, but presumably has a hinge or elbow like joint, as well as a pivot at the top.

As far as heating both ends evenly, from what I can gather, this heat engine was built and installed as a replacement for a steam engine on a ship but was problematic in that regard.

I have a suspicion the cause of the failure (overheating, burning up the cylinders and firebox) may have been due as much to the operator, unfamiliar with Stirling engines, stoking the fire too much.

If the Stirling engine was very efficient, feeding the fires, as if it were a steam engine could probably have easily resulted in overheating and damage to the engine.

[MikeB]

If you want to know more about how that works, look up "Parallel Motion" which was used on steam engines long before Stirling came along.