Oz Invention Eliminates Piston Rings

Submitted: Thursday, Dec 26, 2013 at 08:04
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Interesting concept...what do the mechanical gurus think?

Victorian company’s ringless air-seal system could revolutionise combustion engine design

A Victorian company is working on a technology with potentially major implications for future petrol and diesel engine design.

Warrnambool-based engineering consultancy Dynex has come up with a piston design that eliminates the spring-metal ring traditionally used to form a seal between the piston and the wall of the combustion chamber.

“That’s long been seen as essential in maximising compression and combustion efficiency,” Dynex CEO Brian Trigg told motoring.com.au.

“But our work so far suggests otherwise – that an absolute seal isn’t that important, and eliminating the friction generated by the rings on the cylinder wall can have far-reaching effects on engine design on the whole.”

The key to the technology lies in the replacement of metal rings with “virtual rings” of air pressure, created by the movement of air through grooves in the side of the piston.

“We’ve found a kind of compromise where our design produces a good-enough seal while virtually eradicating the friction created by normal rings.”

With patents in place, Dynex is currently in talks with a number of big-name car-makers worldwide, pitching its technology as a breakthrough in boosting mechanical, volumetric and thermal efficiency levels.

It stands to cut fuel consumption, exhaust emissions and wear-and-tear by eliminating internal friction. It’s also working on a version for rotary engines.

While Dynex is developing the new piston design for incorporation into existing engine designs, it also opens the way for a complete conceptual overhaul, giving potential rise to lighter and more compact engines.

While conventional piston rings form an effective seal, the friction they generate absorbs some of the kinetic energy the engine is trying to create and turns it into unwanted heat energy.

This is a large part of the reason cars need cooling systems. Eliminating friction allows engines to run cooler. That makes for smaller, smarter cooling systems, cutting associate pumping losses and reducing engine mass.

How the ringless piston works:
In place of the rings, each piston has numerous small, angled grooves, semi-circular at their apex. With the small clearances between them, the movement of the piston creates high-speed eddies -- air pressure working like metal rings to cut leakage and loss during the compression and combustion strokes.

“That means there’s no metal-to metal contact between the pistons or rotors and their mating cylinders or housings. Virtually no friction means the mechanism needs no lubrication and there’s no wear and tear on major components,” said Trigg.

There’s an important by-product here, too. Putting an “air cushion” around the periphery of the combustion chamber creates a stratified air-fuel charge – an injection profile that enriches the mixture in the centre of the chamber and leans it up towards the periphery.

It’s the ideal set-up to make the most of each spark, already used in advanced engines by the likes of Benz and BMW for the win-win it produces in boosting performance while cutting consumption and emissions.

Dynex has brought the technology to the proof-of-concept phase, in which virtual modelling of the “air-sealing” principle looks promising enough to get to work on the real thing.

The company is working up a horizontally-opposed (boxer) prototype engine with conventional ringed pistons, with a view to replacing them with the grooved ones.

“We’ve reached the point where we need to secure corporate backing to push the project through the development stage towards international commercialisation,” Trigg said.

“While it’s not possible to predict time to market until we achieve that, we’re confident it won’t take long.”

The Dynex piston design also has major implications beyond the consumer car market, he added.

“We are optimistic there’ll also be good demand for the technology for aircraft and military applications.”


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Reply By: Member - bbuzz (NSW) - Thursday, Dec 26, 2013 at 08:29

Thursday, Dec 26, 2013 at 08:29
Not an engineer but a thought occurred.

How is the pressure inside the bore (above the piston) matched or exceeded by the air pressure on the sides of the piston? There would some serious pressure figures involved in the combustion phase.

Then the next question, how do you get the air into the piston while its going up and down?

Its an interesting concept that more detail would make clearer.

Bill B

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AnswerID: 523521

Follow Up By: Member - Wamuranman - Thursday, Dec 26, 2013 at 08:52

Thursday, Dec 26, 2013 at 08:52
Yes Bill good points.
Did you also have a look at the link right at the bottom of my thread...if you click on that for the full story with pictures/diagrams?
FollowupID: 804977

Follow Up By: Herbal - Thursday, Dec 26, 2013 at 12:14

Thursday, Dec 26, 2013 at 12:14
Good questions...

It's the movement and speed. It is like a computer hard drive. The disk spins so fast that it causes a vacuum effect without causing an actual vacuum. This in turn makes the head (the part that reads the data) float on a thin layer of air. So while the hard drive is working no contact is made with the disk at all.

Once the engine was running, even at idle, it would be moving fast enough for the theory to be sound. But there are 3 questions I would be interested in.

1. How do they get oil to the little end bearings without it going up the skirt of the piston?

2. How do they stop carbon build up in the air pockets?

3. How do they keep the piston off the cylinder wall at start up, when the engine simply is not moving fast enough to cause a vacuum effect?
FollowupID: 804989

Follow Up By: Ross M - Thursday, Dec 26, 2013 at 15:54

Thursday, Dec 26, 2013 at 15:54
My Dentist uses a drill which has air suspended bearing for the rotor unit. Not sure how the side force of a piston pushing high torque conversion into a crank will be able to hold the piston OFF the wall of the cylinder. Sounds good.

SHOOOSSSS Carbon and oil aren't in the speak so far. Friction isn't a high generator of heat in an engine as the oil minimizes it. So it is a small factor, not a big one requiring a cooling system. Mostly the cooling system is there to handle the heat when burning fuel.
Run a diesel down hill for 10km on a cool day and you will see the temp guage go to NOT HOT, and only rises when fuel is burnt. How much friction is there???

All sounds impressive and I also think someone will sell the rights and run.


The computer disk doesn't create a vacuum AFAIK otherwise it would have the heads crashing into the surface, IF anything the speed causes a localized plane, pressure effect which transports the heads on a cushion of air. IE, grader blade technology. or B Double and caravan passing effect.
FollowupID: 805002

Follow Up By: Herbal - Thursday, Dec 26, 2013 at 16:37

Thursday, Dec 26, 2013 at 16:37
Seems to me that you might be having some good old Christmas Cheer there mate ;)

I did not say the hard drive created a vacuum...did I ?

I said the hard drive causes a vacuum effect but does not actually cause a vacuum. I used that analogy because in order for this piston to work, it would need to use the same theory. The hard drive is completely sealed and some are even positively pressurised and some filled with a pure gas (as apposed to air).

Carbon and oil, in fact was mentioned some hours prior to your followup, by Ron below. I found Ron's comments quite useful and I read his post several times...Maybe your "cheer" prevented you from reading that far before your followup :)

Short of putting these pistons in a completely sterile and air tight container, free of any chance of oil, dust, fuel or carbon etc, etc, (just like a hard drive) then I do not see how they could work and hence my above 3 questions.

Merry Christmas Ross M, to you and your loved ones, and all the best for the new year mate...Enjoy that cheer - I am enjoying some myself :)
FollowupID: 805006

Reply By: HarryH - Thursday, Dec 26, 2013 at 10:06

Thursday, Dec 26, 2013 at 10:06
My first thought was that this is another too good to be true story where everyone will go broke and the inventor then disappears with a heap of cash, but hopefully its all legit. I suppose if a major car company becomes involved in the future then that would be a good sign, its pretty hard to see anyone conning them (with the exception of Brockies magic crystal black box polarisation thingy from the 80s).
AnswerID: 523523

Follow Up By: Shaker - Thursday, Dec 26, 2013 at 12:49

Thursday, Dec 26, 2013 at 12:49
I don't think that even conned them, wasn't their refusal to fit it to the vehicles the main reason for the split between Brock & GMH?

FollowupID: 804993

Follow Up By: HarryH - Thursday, Dec 26, 2013 at 13:11

Thursday, Dec 26, 2013 at 13:11
You are probably right, I can't remember the details its too long ago:)
FollowupID: 804996

Follow Up By: Member - gmax - Thursday, Dec 26, 2013 at 15:36

Thursday, Dec 26, 2013 at 15:36
agreed , Harry
it all rings of "too good to be true", no real mention of the rings' other principal function, that is to prevent oil working upwards also towards the combustion chamber....
will be interesting to look this up again in a few years and see if it took off anywhere, or a bit of a smokescreen to bump up the value of the company in question...

FollowupID: 804999

Follow Up By: Ross M - Thursday, Dec 26, 2013 at 15:40

Thursday, Dec 26, 2013 at 15:40
Brocky hit a tree, if that isn't pole arisation I don't know what is.
FollowupID: 805001

Reply By: Ron N - Thursday, Dec 26, 2013 at 13:38

Thursday, Dec 26, 2013 at 13:38
An interesting concept, but not new - and possibly less of a major advance than currently being bleated by the media.
The principle has many potential problem areas, and not the least of which is oil control in current-design engines.
Oil control is a crucial factor that engineers spend hundreds of thousands of man-hours on, trying to get the right balance.
There's no way you could gain effective control over oil going past the piston with air-pressure sealing - it has to be mechanical sealing, or oil-ring scraping, to keep control of the oil.

Failure to tightly control oil going past the piston results in excessive and fast buildup of carbon in the combustion chamber, and the potential to block the air-pressure holes, as Herbal has mentioned.

The idea probably has merit in a new engine design where the conrod is kept moving in purely a straight-line fashion, so oil can be sealed on the con-rod shaft and prevent its entry to the upper part of the cylinder.

Oil would then, theoretically not be needed, in the upper part of the cylinder if this was done - however one has to question if the piston and cylinder would produce the necessary lifespan without any oil at all, in the upper part of the cylinder.

Then there's the question of the need for a new engine that features a crankless design.
Many people have tried crankless engine designs and none have yet proved commercially successful.

I'd put this idea on a par with Sarichs Orbital engine. Promised a lot, but delivered little in the final washup, due to too many complex, initially-unseen problems, that eventually all posed insurmountable.
Vane sealing problems were the bane of Sarichs engine - perhaps this air-sealing idea applied to the Sarich engine design, might be the breakthrough that's needed?


Cheers, Ron.
AnswerID: 523529

Follow Up By: carnaby - Thursday, Dec 26, 2013 at 16:01

Thursday, Dec 26, 2013 at 16:01
Hi as Rod said not a new idea
Sulza have used this principal for over 50 years in there c02 compressors crosshead design so conrd is in a seperate case to the piston rod and piston they use a bronze piston in a cast iron bore no contact but they still wear out and fill with carbon
one must remember that the engines we use today have had over 100 years development so we will see in 100 years how this goes
FollowupID: 805003

Reply By: Eric Experience - Friday, Dec 27, 2013 at 21:43

Friday, Dec 27, 2013 at 21:43
Its a pity that Mr Trigg does not subscribe to the Society of Automotive Engineers journals. He would have read about this idea a long time ago. The early one failed because the piston melted, an important function of the oil is to transfer heat to the block from the piston. Eric.
AnswerID: 523578

Reply By: V8 Troopie - Friday, Dec 27, 2013 at 23:48

Friday, Dec 27, 2013 at 23:48
Yes but...
"How the ringless piston works:
In place of the rings, each piston has numerous small, angled grooves, semi-circular at their apex. With the small clearances between them, the movement of the piston creates high-speed eddies -- air pressure working like metal rings to cut leakage and loss during the compression and combustion strokes. "

Are we talking about a reciprocating piston engine? Then one has to consider that the piston comes to a complete stop at TDC before accelerating in the reverse direction.
So, no movement created high speed air eddies at TDC & BDC to keep the piston from scraping the cylinder wall and causing, presumably, excessive localized wear.
AnswerID: 523582

Reply By: The Bantam - Sunday, Dec 29, 2013 at 00:09

Sunday, Dec 29, 2013 at 00:09
Um yeh note that they are talking about "proof of cconcept" in ordinary english that means they don't yet have a full sized working one.

The problems in real life are many.....yess oil control.

now think of this piston if it does actually work when it is new.....it will rely on these funky groves....what happens when the engine wears or gets carboned up.

I can see gross and catastrophic failure due to a small amount of dirt or wear that would be of little or no concen in a conventional engine.

It might work in something like an oilless compressor and maybee in some sort of alternative material like ceramic or plastic....


yeh..too good to be true.

Have a look thru the patent sites and you will find all sorts of ideas, ranging from the plausable to the down right idiotic, that never made it to reality.

seems to me at the moment tis is an idea and nothing more.

AnswerID: 523607

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