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Opposed piston "twingle"

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At the risk of someone never having patented this idea, some unscrupulous person taking it and running off with my future fortune, I ask, has anyone ever heard of an opposed piston engine in a twingle format.

Basically, the opposed piston has no head and a single cylinder, so instead, have two cylinders in a U shape on a common crank with all the other OPE characteristics?

Two Saturdays ago I woke up with this idea and it just won't leave me alone. So it's either a really good idea that I don't have the money or ability to put to proof of concept or it's a really good idea somebody else thought of decades ago that no one ever used so it can't be that good of an idea.

Either way, I figure the group here are my best chance of having this idea poked and prodded.

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Yeah, I have seen something like what you describe. It was (if I recall properly) a port valve design, twin crank, two pistons facing each other.

fig1-07.jpg

Can I have my $2 now?

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At the risk of someone never having patented this idea, some unscrupulous person taking it and running off with my future fortune, I ask, has anyone ever heard of an opposed piston engine in a twingle format.

Basically, the opposed piston has no head and a single cylinder, so instead, have two cylinders in a U shape on a common crank with all the other OPE characteristics?

Two Saturdays ago I woke up with this idea and it just won't leave me alone. So it's either a really good idea that I don't have the money or ability to put to proof of concept or it's a really good idea somebody else thought of decades ago that no one ever used so it can't be that good of an idea.

Either way, I figure the group here are my best chance of having this idea poked and prodded.

I don't recall any in production. What do you think the advantages would be?

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Not a clue, it was something that popped up in my head right as I woke up. But if somebody already did it, then I don't even have to try.

I don't know the advantages of an opposed piston design. I do know one of it's biggest short comings is that it's wide. It also requires two cranks joined usually by external rods.

The twingle design resolves both of those issues. Instead of a really wide engine, it's now a parallel twin. Instead of having external connecting rods, it has a single pin on a single crank, like a Harley. Fewer parts usually means greater reliability. Yes, I used a Harley as an example of reliability. I must admit, they always run even if they're not running very well.

William, I told you I don't have the money to build one, what makes you think I have money to pay you to tell me I'm wrong?

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LOL, not a problem, I'll add it to your account. Your credit is good with me!

Here is another variation:

opoc-2-stroke-engine1.jpg

Eons ago, when I was about 12, I had a Bridgestone or Allstate twin. Looked like a real twin but he head combustion chamber was conjoined, making it in fact a weird single. Sadly, I saw a picture of the engine design earlier today but now I cannot find it.

Here are a few other wild designs:

Deltic17.jpg

PatOP1.gif

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That stop-motion one is really trippy. Very cool though. I take it that is one those variable crank case volume deals? No more cheap top-end rebuild with a piston that looks like that.

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IDK, I'd almost guess it was a combo 2S opposed, and a single 4S, based on piston shape.

The picture that will not show, you may have to look at the image properties, and copy/paste the URL into a new browser window.

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Conventional twingle:

http://en.wikipedia.org/wiki/Twingle_engine

The Bridgestone twins of the late '60's were real twins. Allstates were Puch products, and were twingles.

Smac,

Not visualizing your concept very well. Specifically, I can't picture an opposed twin with a common crank and no head.??

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Ok, an opposed piston is a single cylinder with two pistons which move towards each other for compression and away from each other during the power/intake stroke.

Instead of having a very long cylinder to do this, you "bend" it into a U shape. It would now have a head (well you could build it like a chainsaw with a single piece cylinder and head) with a common "duct" between the two cylinders where the spark plug would reside.

The pistons would both move in the same direction at the same time.

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Ok, an opposed piston is a single cylinder with two pistons which move towards each other for compression and away from each other during the power/intake stroke.

Instead of having a very long cylinder to do this, you "bend" it into a U shape. It would now have a head (well you could build it like a chainsaw with a single piece cylinder and head) with a common "duct" between the two cylinders where the spark plug would reside.

The pistons would both move in the same direction at the same time.

Isn't that pretty much what the "twingle" designs amount to?

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Sort of, but not quite. If I was any good with animation software, I could easily show you the difference. I'll see if I can pull something out of a hat. Either way, I'm convinced that there really isn't much point in discussing this further. In addition to already being tried - the main point of the question, there's no way I could pull it off.

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Yes #9+X.

(3+6) + some extra variations that were in my head.

That might be enough for me to pull some MS paint magic on though. Thanks. Now if I had only just started lunch instead of just finished it...

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Right, the blower eliminates the need for the crank case compression piston. This wacky little dream sure is going places for something I never intend to build. I've put much less effort into things that came about through conscious thought (and working them out on paper) before saying won't work/too expensive/etc.

ETA: Ok, how about throwing this in the discussion. Both pistons travel at the same rate, but on a short stroke, but since they travel twice the distance combined of a single, it is sort of a long stroke engine but the short connecting rod would allow for much higher RPM and the increased piston area gives it the characteristics of an oversquare engine, perhaps allowing for a much broader power band (where the undersquare motor would kill itself by throwining a rod, the oversquare motor is starting to make power - in my mind anyway).

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Short connecting rods allow power production at lower speeds. Longer rods are more beneficial for higher speeds. This has to do with the point in the crank's rotation at which a right angle is formed between the rod center line and the crank's throw radius, which happens later with a longer rod. Also, the effect of rod length on the asymmetric, non-sinusoidal acceleration of the piston bears on this matter.

As far as over/under square measurements, I'm not sure, but it seems to me as if the bore and stroke of each cylinder has to be considered individually. Individually, it would be, let's say, 2.5" x 2.0" or that times 2, but as a single "curved" bore, you'd have a 2.5" bore and a total of 4" of stroke. Certainly, the compression ratio would be calculated using the max volume of both cylinders as a pair, but how would that apply to the bore/stroke ratio?

Incidentally, aside from the abysmal port flow characteristics of the Puch/Allstate engine, it didn't have a great deal of compression, either, which was directly due to the open area in the combustion chamber where the two bores were linked.

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Ah crap. I said "connecting rod" but I really was thinking about stroke and didn't want to say "stroke" again.

After I wrote it I thought "somebody's gonna get confused", I was right, that somebody was me.

Yup, you're right, in order to get the compression high enough, the flow between the cylinders would be crap.

To answer your question, it's like having a very, very oversquare motor. If in theory, the bore/stroke of each cylinder was perfectly square, you'd have 2X bore to 1 stroke, which is like a single bore piston that moves twice as far, you're displacing twice the volume of a single stroke.

This thread was a lot like a lottery ticket, fun to think about, but never going to happen.

You just saved me a dollar.

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Two Saturdays ago I woke up with this idea and it just won't leave me alone.

I hope you wake up in the near future with the idea of a 2-stroke engine with the power delivery of a 4-stroke...

no, sometimes I also have such ideas, but I guess we're always too late...

nice thread :busted:

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