Bob O'Neil Air Engine

[Tom Booth]

Here is one more version that allows for some additional pre-cooling of the air before being "expanded" by utilizing some of the cold from the air that has already been cooled.

[Joe1]

What puzzles me is the inlet valves (on top of the compression cylinders). If the purpose was simply to provide an inlet for air to be compressed, why not just use ordinary check valves as elsewhere? Using strong springs would tend to severely restrict air flow into the compression cylinder which would just put an unnecessary strain on the engine to open such valves. Of course, just how strong the springs may have been is guesswork. The patent lacks detailed specifications.

I certainly agree with your comments about the odd inlet valves at top of compressor cylinders.  Some other possible explanations might be that there is not enough vertical space in the head piece to fit a ball valve as used elsewhere.  Another could be that he could remove the upper inlet valve and run the engine with half the inlet air, using single acting pistons instead of double acting.

Your posts regarding the cooling and stirling references are interesting and worth some study time.  One thought I have is that Neal does mention that the compressor is working against only 15 psi, which to me implies there would be little heat generated in the compressor cylinder.  Over time with the engine running, it seems there could be a trend toward cooling so that the tank air would begin to cool down.  Not necessarily as the main working principle, but as a side effect.

From what little I know of Stirling engines, the temperature differential is directly related to the amount of work that can be produced by the engine.  The LTD stirlings will just barely turn a light crankshaft.  Neal would need a high temp differential to turn his crankshaft.  It does not seem like that requirement would result in an overunity effect, since much energy would be needed to develop the high temp diff in the first place.  But as you have mentioned, possibly he left that part out of his patent.

Thanks so much for the posts and diagrams, which will keep me busy with study.

[Tom Booth]

... Stirling engines, the temperature differential is directly related to the amount of work that can be produced by the engine.  The LTD stirlings will just barely turn a light crankshaft.

I think the advantage of the LTD Stirling is that it CAN or is able to run on a very low temperature difference, as little as 5 or 6 degrees Fahrenheit due to the very large surface area, but I don't think it is limited to running on a Low Temperature difference. I suspect with a higher TD it could put out power comparable to other Stirling Engines.

As it is, we don't yet know what the effect of "pulling a vacuum" to create a TD would be. If it were possible for the Neal engine to realize what I guess would be the ideal... actual liquefaction of the air, the amount of liquid air produced from each cylinder would no doubt be miniscule. Perhaps just a tiny droplet or a mist, but there are so many cylinders working together and continuously...

When air actually liquifies, so I've read, it takes on a "spheroidal state" and even in a high temperature environment tends to persist. Surrounding itself with a protective, insulating vapor. This is similar to splashing a drop of water on a very hot skillet. Rather than evaporating from the heat, the drop of water will dance around on the skillet on a layer of water vapor. I can imagine such droplets of liquid air traveling down the common pipe to the "equalizer" then into the tank.

If this were possible, Air, when it expands from a liquid increases in volume 800 times. In other words, a very small amount of liquid air could easily fill an air tank.

The same principle for COOLING air, when taken to extremes will also liquify air.

Most of the early difficulties involved in liquifying gases were due to ignorance regarding critical temperature. It was found that compression, no mater how extreme just didn't work. The "permanent gases" that were considered "impossible" to liquify were found to be relatively easy to liquify when cooled. In other words, cooling is a more effective way to "compress" air than actual compression.

As you point out, the Neal engine was only supposed to use 15 PSI which is practically no compression at all. Logically, it seems to me, extreme cooling would be the only viable substitute for actual compression.

Historically, I think it is also interesting that Neal completed work on his engine and filed the patent not too long AFTER the period of time when Trippler was liquifying air in great quantities and very inexpensively, primarily using cooling rather than high compression, and created quite a stir about the possibility of running engines on liquid air. 

Neal would need a high temp differential to turn his crankshaft.  It does not seem like that requirement would result in an overunity effect, since much energy would be needed to develop the high temp diff in the first place.  But as you have mentioned, possibly he left that part out of his patent.

A high temperature difference can be arrived at in two different ways. Heating something above ambient, OR cooling it far below ambient. You don't necessarily need to have an availability of an extremely cold sink to get extremely cold temperatures since this can be arrived at by mechanical means. Trippler liquified air in enormous quantities with nothing more than the availability of cold river water for cooling, the rest of the cooling was mechanical, compression and expansion.

Of course, I'm just speculating. If the Neal engine actually worked, including the small model he took to the patent office, I can't help but wonder what happened to these engines.

Recently I've been wondering what happened to Trippler. He seemed poised at one point to bring about a revolution. He seems to have proved that an engine could very well run on liquid air and that the liquid air itself could be produced in quantity at very little cost, then what ?

Thanks so much for the posts and diagrams, which will keep me busy with study.

One thing about the diagrams. It is a minor point and I was going to fix it but I didn't realize it until after I could no longer edit my posts. But the "vacuum pump" is wrong. That is, the placement of the check valves makes the pump non-functional. I don't see any need to re-upload all of them I'll attach one image with the valve relocated.

Anyway, using the LTD engine would, I think be an advantage as it is not so demanding, as far as temperature difference requirements. But it could be made to operate on the same principle which if taken to extreme might be used to run a larger engine, like the Neal engine.

In other words, the same principle used to run the LTD engine on slightly cooled air could theoretically also run the Neal engine if the cooling were taken to the point of liquefaction.  I very much doubt it would work otherwise. That is, without an actual change of state the air would just be expanded in the cylinder and then compressed back down before it left the chamber. As far as I can figure out, that would serve no purpose. But if even a very small quantity of the air actually liquified and condensed into the "spheroidal state" then it could accumulate and be moved into the tank. The change of state, I think, would be very important in the Neal engine for it to function, but a change of state would not be required with the LTD engine, though the same principle is involved.

In other words, if the LTD engine could function as illustrated then I think that this would lend some credence to the idea that this is how the Neal engine may have functioned in principle as the method used for cooling is the same as that used in gas liquefaction. It would just be a mater or taking it a step further. A greater degree of cooling using the same or similar method.

[Joe1]

This is a very interesting discussion.  Do you have any links where I could learn about Trippler?  Tried the Google patent inventor search, but nothing there.  Many Thanks.  Are there any patents associated with Trippler?  Do you have a first name, or did he publish any papers or descriptions?

When you refer to the spheroidal shape, sounds like that would be similar to supersaturated water.

[Joe1]

Here we go,
http://archive.org/details/liquidairandthel033169mbp
See Chapter XII.