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Australian Team Working On Engines Without Piston Rings
JabrTheHut writes "An Australian team is seeking funding for bringing an interesting idea to market: cylinder engines without piston rings. The idea is to use small grooves that create a pressure wave that acts as a seal for the piston, eliminating the piston ring and the associated friction. Engines would then run cooler, could be more energy efficient, and might even burn fuel more efficiently, at least according to the article. Mind you, they haven't even built a working prototype yet. If it works I'd love to fit this into an older car."
I'm sorry but the energy density of hopes and dreams is nowhere close to that of gasoline.
fnord.
But hopes and dreams are of endless supply. Gasoline not so much.
Extra fuel efficiency would be nice, but I am most excited about the prospect of the engine itself lasting longer. Less friction = less heat, less wear & tear, etc. A cool, frictionless engine could potentially last for half-million miles before needing replacement. At my paltry 10-20k miles per year, I could potentially never have to buy another car again.
Trust me, I have a PhD in engineering.
Would you care to expand upon that? Or is this the scenario we are looking at below?
If an elderly but distinguished scientist says that something is possible, he is almost certainly right; but if he says that it is impossible, he is very probably wrong. -- Arthur C. Clarke
Or perhaps we simply have a loose troll?
much of left-wing thought is a kind of playing with fire by people who don't even know that fire is hot - George Orwell
Wankel apex seals are the equivalent of piston rings - ie a chunk of metal/ceramic that fills the gap between the piston/rotor and the chamber wall.
From TFA:
A 'virtual model' equates to 'proof-of-concept'? Since when?
I'm really annoyed at the US car market.
Take any car that is available in Europe, and the only engine you can get here is the biggest one that's available there. I drove on European highways with a 1.1l Fiesta. It won't win any races, but it goes fast enough, and sips fuel. Same car, US side? 1.6l engine. Still pretty good mileage by US standards, but few people would buy it across the pond with the "big" wasteful engine.
Diesel? over 60% of the market in multiple Euro countries. Small HDI engines that give you more oomph than a 2.0l gas one, and torque like a small V6, for two drops of fuel per mile. States-side? Gotta buy a VW/Audi at a premium, or trust GM to have finally made a reliable econobox. For starter, the GM solution with a urea tank is probably not really happy today in the northwest (freezes at 12F according to the web).
So yeah, I'd love a diesel, or a European car, so I can say bye-bye to the fuel pump without lugging batteries and paying a repair premium (and no 10yr resale value). But you can't get them here, because someone decided that Americans NEED MORE POWAAAAR, or something. To drive 65MPH.
Trust me, I have a PhD in engineering.
Would you care to expand upon that? Or is this the scenario we are looking at below?
I'm an engineer too, but without PhD. I don't know what he was thinking of (or even if he is an engineer at all), but I can say one major flaw that I noticed. The piston rings serves two functions and they only consider one.
The article deals with combustion, which is on top of the piston. It never mentions what is below, which is the piston rod and the crankshaft. The connection between those two needs to be well lubed, but the construction makes it really tricky to lube a "run away" bearing. The solution is to make an "oil fog", which sticks to everything, including the cylinder below the piston. When the piston moves downwards, the piston rings scrape off the oil from the cylinder and provides a clean surface for the combustion.
When running an engine with cracked piston rings, lube oil will start to enter the combustion. This will produce toxic black and foul smelling exhaust and the engine "will be burning oil". Even worse the oil burns badly and leaves behind soot, which will damage/block the valves. Some of it will stick to the cylinder wall and not be removed by the piston rings, which mean it ends up in the lube oil. The higher the amount of soot in the oil, the worse lubing ability it has. Eventually you have an engine with enough oil, but no lubing.
In short: no piston rings will destroy every valve and bearing in the entire engine and replacing it could be cheaper than repairing it.
I consider this to be a far more serious problem than anything the article mentions and I find it rather shady that they completely avoid this rather serious issue. It isn't like it is an unknown problem. If you run big engines like trains or ships, then you will periodically test the oil for soot (and other stuff related to other defects) to detect faulty piston rings before the engine is wrecked. Anybody working in the engine industry should know this.
Turbulent obturation rings of this kind (well, technically I guess these are obturation cannelures) have been used in a lot of applications because they have some interesting properties. For instance they are used in mortar shells. When you drop the shell down the mortar barrel, you essentially want it to fall without retardation so the primer gets a good hard strike and the propellant ignites 100% of the time. However you want as much as possible of the propellant gas to do the job of propelling the projectile, without blowing past it in the barrel. You ALSO want it to be as consistent as possible so the CEP of where the projectile lands relative to the target is as small as possible. So this isn't impossible, but it's not easy either.
From the TFA:
"... that an absolute seal isnâ(TM)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 "
" ... that the whole thing is blowing a bunch of hot air?"
If they _ CAN _ use that bunch of hot air to form a seal, and achieve a drastic reduce of friction in between the piston ring and the bore itself, I feel that it's time for the return of the ceramic engine.
The chief reason why ceramic engine doesn't make it into the mainstream despite having had under research since the 1970's is that the friction in between the piston ring and the wall of the bore itself result in the wearoff of the ceramic material in the form of a pile up of fine ceramic dust inside the chamber.
If what the vendor said is proven to be true, then we should bring the ceramic engine back to the fore-front.
Muchas Gracias, Señor Edward Snowden !
I'm not switching from gasoline until someone makes an engine that will run on distilled suffering of hippies.
Violence is like duct tape. If it doesn't solve the problem, you didn't use enough.
I believe this is not true. When I lived in New Zealand I noticed that the octane ratings were higher than in the USA, but after researching this, discovered that the difference is mostly accounted for in a difference in the way that octane is measured. In New Zealand (and probably Australia, and probably Europe), the rating uses just the "research octane", i.e. that measured in a lab somewhere; but in the USA, the rating is an average of the "research octane" and the "measured octane", the measured octane producing a lower number, that when averaged with the research octane, means that the same fuel is rated at a lower octane rating than it would be in New Zealand.
To add on to what user Firethorn has said, try imagine an engine that needs no cooling.
The very reason we need to COOL our engine because the metal that we use in our engine can withstand heat up to a certain limit, and beyond that, the engine starts to melt.
Ceramics don't have that problem. Some ceramic compounds can withstand thousands of degrees of heat (and for that they have been used as shields for the Space Shuttles) and they are excellent insulators !
Serious research has been carried out on ceramic engines since before 1970's, by almost all the developed countries (America, Europe, Japan) and prototype engines had been developed.
The main problem so far is that, unlike metal, ceramics are not as durable against friction. Very fine ceramic dusts will fall out as a result of the friction, and combined with the fuel, it become "sludge"-like, jamming up the chamber.
There are a lot of places inside an engine where there are frictions, but the MAIN place which friction takes place is in between the piston ring and the bore wall.
If what the TFA says is true - that they can manipulate the air to become a "force" and takes the place of the piston ring, which means, the friction in between the piston ring and the wall of the bore is gone, then, the number one problem facing the ceramic engine is solved !
Muchas Gracias, Señor Edward Snowden !