VERY old plans for large, high torque engine

[onecycleDan1990]

Surprised nobody mentioned this before (either that or a bad search engine)
From the book Amateur Work Three (3) from 1904! Published by Draper Publishing Company
The plans detail a large gamma engine with 3 inch stroke and 2.5 inch bore power piston and 3 inch bore displacer piston.
The displacer cylinder is a steel pipe, and uses external threads instead of fins or a water jacket for heat exchange.
The engine produces very low speed but impressive torque; approximately 1/8 horsepower (about 90 watts) at only 100 to 150 rpm. To put this into perspective the same torque from the same displacement at, say 1000 rpm (not achievable from this engine, sorry) would equate to (1000 rpm/150rpm)*90W at 150 rpm= 600 watts or otherwise 600/241=2.49 watts per cc per 1000 rpm. This would imply very good heat transfer especially at the cold end, surprising for an engine that only has a screw thread as a heat sink.

This image is from the link below


Much of the techniques originally used are severely obsolete or cause severe health/ environmental harm. The two worst are sealing the hot cap plugs with red lead , and perhaps even worse, using Asbestos to insulate the firebox. Not harmful but no longer practical is to hire a tinsmith to make the displacer.

I believe someone with proper tools and the ability to adapt this design to modern times could build this engine without extreme difficulty.

For anyone who is interested the plans, as published in 1904 are available free from this link:

http://chestofbooks.com/crafts/popular- ... ngine.html

[vile_fly]

Now, THAT is very cool. The book-magazines they are from are neat, too. I found "Amateur Work 3" at www.archive.org and the other ones in the series, too. They are free public domain books. It is an old hobby of mine, collecting old books that are no longer in print. Everything you could ever want to make in those books and more. Even has a wimhurst machine set of plans in there.
A good use for this engine probably would be as a very large fan or running a lathe or sewing machine. The threading is a nice quick and dirty method for fins, by the way. It appears I still have a lot to learn from these old timers who wrote the articles.
Many thanks for posting it.

[Ian S C]

With modern materials, Ball bearings, Aluminium in places where it is required for lightness, or to get rid of heat, stainless steelfor displacer cylinder and the displacer You could get the modern equivalent of a tinsmih to make these up with his TIG welder. Using this stuff should give a bit more power, and if you wanted more, water cooling would help, or even a small engine driven fan next to the cold end, possibly with a duct to direct the air.
One change I would make is the displacer cylinder, I would make it in two pieces, hot end stainless, cold end aluminium. Gland teflon bushing. The air take offshould come from the cold end rether than the old method of half way. Ian S C

[onecycleDan1990]

My ideas for improvement on this engine are as follows.
1. replace the steel pipe displacer cylinder with spun or deep drawn stainless less than one millimeter thickness. spun for small numbers, deep drawn in the event someone wants to sell many for a profit
2. reduce displacer to cylinder gap to about one thirtieth of an inch thick.
3. install a water jacket such that water is in direct contact with the displacer cylinder walls.

The purpose of changes one through three is to reduce thermal bottlenecks. While thick walls with threads do a wonderful job of maintaining a large internal temperature difference at 150 rpm they will not do nearly as well at 1000+ rpm. The goal here is not to increase torque, which is already nearing its achievable limit, but to allow for unusually high torque to be continue to provided at far higher rotational speeds.

4. perhaps not necessary, increase power cylinder bore. This will do two things; A: increase displacement, and B: increase compression by increasing displacement more than increasing dead space.

5. most important if it is to be sold to the layperson: use an enclosed crankcase. This is a safety measure. With these modifications an engine this size might produce several hundred watts. One could easily imagine the fallout if a senseless child stuck there hand in between the crank and the bed. And so could the parents lawyers. It might even give stirling engines a bad image in the public eye, and that would be bad for everyone.

I would keep a cast iron frame, in have had bad experiences with cheap aluminum castings, namely a transmission cover on my motorcycle, cast in aluminum, more than 3/ 16 inch thick, broke when kick starting. The break went all the way around the starter shaft, preventing it from ever being used without expensive repair. I have also seen wonderful aluminum castings, in the case of the old Evinrude/Johnson outboards (not strirling unfortunately) I want a good first impression on the public's mind.

In case anyone is wondering, I personally have no intent at all to commercially manufacture this or any other engine.

Anyone else have any ideas.

[Ian S C]

For a one off engine, its proberbly best to fabricate the frame etc., rather than use castings. Some steel, and a welder is a heck of a lot easier than making patterns, and getting castings. I,v got a stainless handelless cup that cost $NZ4 that would be the right size for the displacer cylinder, its waiting to go on one of my motors as a replacement of the mild steel one thats on the motor now(its got a big bulge from running at red heat for a number of hours). Ian S C

[Ferraccio]

The cover closed, first of all, may be is good for the pressurization of the body, with drastic increase of the working fluid mass, and therefore of power. If the closed casing contains the generator, it is necessary that it functions also as engine to start.
It should also be an accumulation / distribution of electricity to boot.

It seems to me unjustified and penalizing the gas plug that goes from the hot chamber to the motor piston in the middle of the displacer.
While the clearance for the passage from upstream to downstream of the displacer is probabily excessive, the rolling of the gas in the pipe 1/4" is a true bottleneck, that can not be solved, and worse drastically if you reduce the clearance. (do some accounts of the ring section in a 1/4 " x clearance ....!!!!). Perhaps is for this that clearance may be was increased ...

If now all take the gamma architecture with duct from the cold side of the displacer must be a reason .....!

If you make an engine "archaeological copy" must be perfectly equal (many dimensions are due to the use of commercial pipes); if you start thinking about what is best (now) may be that become, slowly, an engine that is completely different.

[Ian S C]

I'v got an interesting artical from model Engineer 16 Feb 1977 by W. D. Urwick. He did some experiments, and found that the tube from the displacer cylinder to the power cylinder did'nt really matter how long it was, he tryed a rubber tube six foot long, and he thought that any reduction in power could be put down to the pulsing in the rubber tube ie., the rubber stretches, and it could be improved using metal tube.
If you close the crankcase of a non pressurised engine, it must have enough ventilation so there is no back pressure, I now, I'v tried on a couple of engines, and if I seal them, it puts a load on the motor, these motors are designed to be pressurised, but this hasn't happened yet. Ian S C

[Ferraccio]

I follow your think
In general, the volume between the two sides work (hot or cold) where there is no transformation of energy (such as a plastic tube) is called dead space, and in general its presence in a relevant way is always considered negative.
Of course if the pipe (certainly better metal) only transmits the pulse to the motor piston, when the piston engine is not cooled and therefore not involved in the heat change, the air in the tube only the function of gas piston

Where, however, increased technology in machines, the motor piston is cooled and it plays a significant additional workload, in decompression, in this case by making comparisons with the piston "only mechanical" there is lot of difference, because in case of long pipe the thermal function of piston is not yet possible .

Yust like you can not do snorkeling with a pipe six feet long, where pushing the same air back and forth over the last feet of pipe you die of anoxia.

The engine pressurized to 16 times the atmospheric pressure has a proportional mass of working gas.
In these terms, the pressure in the crankcase is not many important.
With two phased unit by 180°, with a common crankcase, pumping pressure in crankcase become irrelevant.

When you then say that "the same" I have my doubts, because it depends on which measurement comparation you have.
If you think it need ventilation in the carter is not an engine with elevated performance. The refrigeration cooling system may provide this.

[onecycleDan1990]

A good example of what a modern version of the engine I described in the first post of this thread might look like is the Sunflower solar engine designed by Bill Gross for Energy Innovations, a subsidiary of Idealabs (founded by Bill Gross).
It is also a large high temperature difference gamma with (as far as I can tell from the illustrations of the video) plain surface heat exchangers. It appears to be roughly similar in size to the 1904 engine.

Here is a link to the video where the creator describes this engine http://www.youtube.com/watch?v=TSMzKg6fwJ8
as a warning if anyone is short on time: fast forward, the engine is not shown until around 12:30 minutes.

In case anyone wants one as seen in the video: too bad, there not for sale and probably never will be. Energy Innovations gave up on stirling engines several years ago and now is exclusively using concentrated photovoltaic for the sunflower product range.

The idealabs engine was slated to power a generator of 250 watts or 275 watts continuous output. this would imply a 350 to 450 watt or so mechanical output, assuming a 60% to 70% efficient generator proper and assuming the engine is operating at less than 100% load. The rotating speed in rpm is unknown but is probably moderate. My guess would be between 500 and 1000 rpm (if anyone is aware of the true value please post). The displacement is not given but I would guess the power piston swept volume to be between 250 and 500 cubic centimeters. This indicates a specific power of between seven tenths (.7)of one watt and one point eight (1.8) watts per cubic centimeter per atmosphere (W/cc/atm.) this puts it between the upper normal range and the unusual but achievable (with difficulty) output ranges for an unpressurized air engine, implying that it is unpressurized or perhaps lightly pressurized.

perhaps a useful, cheap engine could be made by further simplifying the sunflower engine. A conventional crank or scotch yoke would replace the existing linkage. This would allow for a smaller, therefore lighter crankcase, and reduce the number of bearings (read: precision mating surfaces, in turn read: more machine time, I.E. more cost) A rotating pto shaft, identical to that on a small IC engine, would allow for multipurpose use. My opinion on the pto vs sealed generator debate is below.

regarding the placement of the connecting pipe on the middle of the displacer cylinder: The placement of the pipe originally decided on enabled the head of the power cylinder to be forward of the base of the displacer cylinder, thus enabling a shorter overall length to the engine. where the pipe connects with the displacer cylinder does not matter with cylinder walls that thick; the cylinder wall can be threaded to accept the pipe. The reason this is no longer done is probably simply because it is very difficult to attach a tube to a cylinder whose walls can be as little as only a hundredth of an inch thick, as is the case with spun or deep drawn stainless hot caps.

The idea to hermetically seal the crankcase and keep an electric generator and all moving shafts within same crankcase is a good idea for some situations. The situations in question are when a highly pressurized engine is running a dedicated generator. The most obvious drawback is that the machine can be used for no purpose other than the generation of electricity, when there are so many other uses for the now absent rotating shaft. Also, the problem solved by sealing the crankcase is far more benign with air at a few tens of psi than the herculean task of confining hydrogen or helium at over one thousand psi. For a lightly pressurized air filled engine the shaft seals used on an IC engine are adequate and available. Some leakage will be present but there is air everywhere, and only a tiny compressor is needed to maintain the desired pressure.

[Ferraccio]

Very interesting your considerations Dan,
Only two considerations
1) For pressurizzed engine is not necessary use Helium (rare) or Hydrogen (dangerous), it is sufficient Nitrogen, more common.
When the Crancase is filled (and sealed) no other gas needs. For a "small compressor" (with good seals), may be you lose easily 10-15% of energy, or more. The energy output is proportional to the gas mass in work.
2) An output in electrical energy is good for all uses, (in different location and position). The loose in energy electrical-electrical is minimum. Of course, to have mechanical work, you need an electr. motor; but how many energy do you lose with bearings, gear and rubber belts?

[Ferraccio]

Nitrogen is really common (78% of the air is Nitrogen), is neutral, not oxidant, frequently used in industry to fill food packages-storage.
Recent use is to fill tires, to encrease the durations and performances, no oxidation or degradation (metal-rubber).
http://www.innovativebalancing.com/Nitrogen.htm

[vile_fly]

It is interesting to note, Ferraccio, that the automotive industry does not advertise its mistakes. After working in that field for 20 years, I have seen a few interesting things. The trouble with nitrogen in tires is that it does indeed lack moisture. The tire actually dry rots from the inside out. The nature of tire compounds is that they ultimately NEED moisture to stay flexible. So many shops have complained of tires wearing out sooner than the warranty expires. I've been to the conventions. They all say the same thing.....internal dry rot. Figured you might want to know.
I just wish nitrogen was a smaller molecule.

[Ferraccio]

In fact, the industry uses the items as raw materials, but the ideal would be to define the waste as raw materials again, and not as waste.
I worked for the petrochemical industry (U.S.), the nitrogen is really important as a overhead for lubricant processing (avoiding contact with oxygen and water), and then throws away the oxygen, since nitrogen is obtained by air distillation.
Oxygen instead is used a lot for steel industry, and thus the nitrogen in this case is thrown away in enormous quantity.
The industry would be ideal for use everywhere, is that of one of the other.

In fact if there was an excess of sodium carbonate should be found that prevents tooth decay.

[Ferraccio]

Tires are made by organic material;
Organic materials are short life, will constantly change over time, are more sensible to environment , and being done by a complex procedure every step of production may be is well, ... or less well done.
A steel beam is enough predictable for life, enduration, and strengh.
A wooden beam is beautiful, but can stay rotting, termites, or invisible knots, advising at last more monitoring and also over-sizing.

[waleeed]

The engine produces very low speed but impressive torque; approximately 1/8 horsepower (about 90 watts) at only 100 to 150 rpm. To put this into perspective the same torque from the same displacement at, say 1000 rpm (not achievable from this engine, sorry) would equate to (1000 rpm/150rpm)*90W at 150 rpm= 600 watts or otherwise 600/241=2.49 watts per cc per 1000 rpm. This would imply very good heat transfer especially at the cold end, surprising for an engine that only has a screw thread as a heat sink.