LocostUSA.com

An Australian company has come up with a way to get rid of piston rings and all the resultant friction & drag. Too early yet to see if it will work well enough to be adapted, but at least someone is looking outside the box.

http://www.motoring.com.au/news/2013/aussie-invention-eliminates-piston-rings-40773?WT.z_csource=Outbrain&WT.seg_4=Outbrain

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mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

That appears to be the same types of seal they use between cylinders on the crankshaft of a 2-stroke…

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
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Supposedly it's a variation and improvement upon several systems out there.

I'm not sure how efficacious it would be for higher performance engines, but if it frees up horsepower by lack of the engine losing less then in one way that's a performance mod.

I foresee several improvements to the infernal combustion engine over the next few years that will give us some much more efficient engines.

What I liked about this article was the fact they are working on an application for the rotary. That would eliminate the weak link in the rotary engine. I've seen numerous articles about using small package rotaries to power the "generator" on hybrid cars as rotaries seem to do well in steady state applications.

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

One major drawback to implementing this with a major automotive manufacturer, is the engine redesign requirements appear to go far beyond the pistons themselves. In conventional engines, the pistons see significant off-axis loading from the angle created by the crankshaft and connecting rod. I doubt if their 'air seal' alone can withstand this. In the picture they appear to be illustrating a purely axial functioning connecting rod, which would alleviate this problem, but I don't see how they're planning to convert that into rotational motion at the center portion of the engine. I suppose it might just be the infamous magic-box mechanism...Although the center portion could possibly be used as a linear electric generator. But their confidence that the time to market "won't take long" seems to be mostly optimistic marketing speak.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

It's called a Labirynth seal.

Tried to make one once for a Honda NSR250 as I couldn't buy one (comes with crankshaft as an assembled unit only) and it didn't work darn it.

Honda have tried running race engines without compression rings before but need to be turning around 10,000 rpm before the piston speed is faster than the escape velocity of the compression charge.

Not quite the same thing. It's not that it doesn't have piston rings, it's just the piston rings are an air curtain.

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

That was the first thing that came to my mind Marcus (I'm assuming by crankshaft you meant piston).

2 stroke glow engines for RC models are ringless and rely on grooves in the piston and the very slight taper of the sleeve for compression. I dabbled with them for several years when I was younger - the simplicity was pretty amazing.




Apparently BMC did that for the crank on the A-Series engine. It must be an easy design to get right since they've never been known to leak oil.

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-Andrew
Build Log
Youtube

That disc with the pin on the circumference, in the center of the assembly, will accomplish the transition.

Walt

Thanks for the clarification Walt! It seems I couldn't see the forest for the trees...Still, it's lacking a lot of detail (possibly on purpose) and in general makes me question how well that configuration would actually be able to reliably replace the current evolution of engine design. But I'm all for investigating any possible novel improvements, so best of luck to them if they genuinely have found a new way to make it all work.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

its becoming more common in race engines to leave out the second ring, it reduces drag.

if the top ring allows gas to pass, then it is lost to the crank case and out the breather system as opposed to lingering between the top and second ring which causes ring flutter, having a smaller second ring gap compared to the top ring is now frowned upon for this very reason.

there is a lot more to it than just leaving it out though, as you only have one compression ring, you must make every effort to promote top ring sealing by various methods like gapless rings or gas porting the top of the ring groove and moving the top ring up towards the crown to limit crevis volumes caused by the porting.

there have even been attempts to use top land rings, Visard has written extensively on this very subject.

the largest drag on a piston is the oil control ring, tention in this ring can be reduced by using a multi layer type ring, the problem is keeping the piston cool by transfering heat from the piston to the cylinder wall and away to the cooling system.

some piston manufacturers like to put the little grooves in a conventional piston, usually to stop unburnt fuel from creeping down the side of the piston crown by trapping combustion gasses in the crevice above the top ring between the cylinder wall and the piston.

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this story shall the good man teach his son,
and chrispin chrispian shall ne'er go by,
from this day to the end of the world.
but we in it shall be remembered.

Justin, look up scotch yoke.

Also http://www.autospeed.com/cms/A_0948/article.html

Like a conventional engine and a steam engine with a rotary center section

_________________
mobilito ergo sum
I drive therefore I am

I can explain it to you,
but I can't understand it for you.

They use a labyrinth seal on 2 stroke engines between the cylinders. In a 2 stroke the crankcase is pressurized on the piston downstroke and then the charge goes up into the cylinder thru the transfer ports. Not all 2 strokes work this way, but it is the common method to supply lube to the crankcase and connecting rods...

The amount of sealing required in this application would be relatively minor compared to pistong rings, but I saw that part years ago and was surprised it worked...

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

Sorry I thought you were talking about the piston/sleeve seal.

This one only has one groove but I seem to recall some of the other engines I've owned having 2 or 3.



Just replace the ports in the sleeve with some overhead valves and you'd be in business.

Interestingly enough though the model 4 strokes use a single ring instead of the groove. I've never had one apart so I don't know if those sleeves are also tapered as well or straight.

_________________
-Andrew
Build Log
Youtube

Thanks for the background information on the use of that type of mechanism in engines. This reinforces the likelihood that they're expecting whoever they partner with to design, develop, and prove out a completely new engine architecture dedicated to this technology, which will be far more costly and time consuming to introduce than if this was just a 'novel' piston idea that could be used with any existing style mass production engine architectures as well.

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie