Toroidal Engine Ready for Production

FarceMajeur writes "Business 2.0 has a column on a recently prototyped "round engine," properly named a toroidal engine, by VGT Technologies, Inc. Nice Flash animations of the concept are here. I've always admired the Wankel engine, but it seemed more like a time bomb than a going concern. This engine is billed as the 'world's first practical Concentric Positive Displacement Engine,' meaning no eccentric rotation to generate vibration, meaning fewer catostophic failures, one would hope."

Comments

rotary engine?

[PD]

The Mazda RX-8. It's a wankel, not the same as the engine in the article.

Yet another revolutionary internal combustion eng

[HotNeedleOfInquiry]

My understanding is that there is something like 500 different designs for internal combustion engines. Needless to say, nearly all of them are useless for one reason or another.

Reciprocating pistons and poppet valves still live because they work well, can be manufactured with simple operations and have seals (piston rings and valve seats) that will last for years.

I thought about a design like this many years ago and concluded that there would be major difficulties sealing in the combustion gases. I guess time will tell whether the problem has been solved.

Ok, I'm confused...

[Randolpho]

How does the main flywheel maintain its rotation? If it's transferring energy to another wheel, it will slow down, friction notwithstanding. One would think that pistons would still be needed to keep the big wheel turning.

Re:Ok, I'm confused...

[Smidge204]

It's a flywheel after all. There's a good deal of energy stored in it's rotation. Inertia alone would be sufficient to complete the cycle.

Now here's an interesting thought. You have two (hopefully dynamicaly balanced) flywheels (aka "Gyroscopes") with their axes perpendicular to eachother... very similar to the gyroscope arrangement in a navigational gimbal - used to make a platform that is rotationally stable to provide a reference point for measuring the rotation of your craft.

What would happen if you mounted this engine in a car? Worse yet, and aeroplane?

If the mass/speed of the wheels is high, then the entire engine will not want to rotate in any direction. Forcing it would cause very high bearing forces and a torque that would try to rip the two disks apart.

Sounds like an interesting problem. Hopefully they can keep the mass of the components down to minimize the gyroscopic effects.
=Smidge=

Re:Ok, I'm confused...

[Randolpho]

Er... I wasn't trying to discount gyroscopic motion, but the problem is that the 2nd flywheel (at least in the animations) is clearly being "hit" by the main flywheel to transfer energy; it looked almost like a two-tooth gear. That looks to me like it would substantially reduce the energy in the main flywheel from the impact, even despite the little ramp built in.

And, as I said, this was also despite friction, which would also be a necessary thing to worry about given that the flywheel is mounted somewhere.

Timing

[lirkbald]

Well, I looked at the animations. Neat idea, I think. But what happens if that timing belt goes? It looks to me like the thing would smash itself to pieces.

What would happen if a timing belt gave out on a 'normal' cylinder-based engine? I'm not too knowledgable about engines, but it doesn't seem like it would be quite as catastrophic.

"Useless for one reason or another"

[nusuth]

No they are not useless from a technical POW. One of the alternative designs should be used if we had to redesign all of engines, factories, fuels, motor oil and car's form factors. The design we use now is not the best one, it just happens to be the one whole automobile industry is shaped around. So it can only be replaced if an alternative is significantly better, while -to my knowledge- no alternative design is.

I'm taking the don'ts

[Paradise Pete]

Mr. Pekau is an experienced mechanical engineer....In addition to Mr. Pekau's work, which is well documented

IANAE, but this is likely to be a crackpot/scam venture.

The phrasing I've quoted above, which come from the web site, are big red flags. They're trying to pitch Pekau instead of the engine. Along the lines of "he's really smart and knows what he's doing, so of course his engine works." This is how scam after scam after scam gets pitched. "Ignore all the nay-sayers, because they just don't understand what our guy has done."

The phrase "which is well-documented" is also a tip off. Nobody says that unless it's not quite true.

Yeah, but the physics isn't intuitive

[Spamalamadingdong]

You have two (hopefully dynamicaly balanced) flywheels (aka "Gyroscopes") with their axes perpendicular to eachother... very similar to the gyroscope arrangement in a navigational gimbal...

A navigational gyro table uses three gyroscopes as sensors; the actual rotation of the table to keep it fixed in space is done with motors, not torque from the gyros. If you applied any torque to the gyros, they would precess and wouldn't be pointing in the same direction any longer.

The total gyroscopic moment of the wheels in the toroidal engine can be computed as the vector sum of the angular momenta of the two pieces. This isn't quite intuitive, but it's not rocket science either.

What would happen if you mounted this engine in a car? Worse yet, and [sic] aeroplane?

It's easy to answer this question, because it's been done. ;-) The WWI aircraft rotary engines were radials with the crankshaft mounted to the firewall and the propeller bolted to the block. The effect of the rotating mass was to make the aircraft yaw when pitched up or down, and pitch when yawed left or right. This coupling effect made some maneuvers easier than others, and thus more predictable for enemy pilots - I'm sure lots of Allied airmen died because the Germans knew what to expect, and thus where to shoot.

If the mass/speed of the wheels is high, then the entire engine will not want to rotate in any direction. Forcing it would cause very high bearing forces and a torque that would try to rip the two disks apart.

Not a big issue. The real problem is torque on the vehicle, particularly on slippery surfaces when going over a sharp hump. This can be remedied by lightening the rotating parts.

The real issue is that this engine probably can't be manufactured to the required tolerances (especially over temperature), and its large surface areas will probably keep its thermal efficiency lower than piston engines. This puts its claims well toward the "scam" category

nice theory, and real world snake oil

[Anonymous Coward]

the problem is always pressure seals, and take a look at what would be needed for the 'flywheel' on this one. wake me after they've dealt with that, and i expect it'll be some years, if ever.

the wankel worked, btw. it just didn't turn out to be much more efficient because the piston-crank method is so refined. it was more of a marketing disaster because mazda made them a little too cheaply after a big PR campaign. they had to remove it from their sedan line but could keep in their sports car because those customers read a little more.

and it's very hard to think of a simpler or more efficient seal than the piston ring & cylinder combination.

the compression rings [there's a few others doing things like oil] are very like split ring washers, and expand to meet the cylinder wall. in the piston they're still sitting in the ledge of their groove for support, and the pressure holds them tight against it. but they're free to rotate around the piston, so you get even wear between them, the cylinder walls, and their grooves. and because they expand to contact, they can take an amount of wear over time before they're not reaching the cylinder walls effeciently.

you'll have to at least match that before you can begin to test if this 'new' design is any more efficent.

and quotes for 'new' because they are indeed hundreds of really interesting concepts from the last century. many were successful in fields other than automotive. worth geeking out and digging into the history. [turbines are well known. whittle was looking at turbo assited piston engines and realized with a bit of work you could throw away the 'engine'. brilliant rotarty solution.]

oh, and a note for /. editors: guys, there's 'brilliant new combustion engine' designs all the time, and they never go anywhere. don't touch these articles unless they get real backing. you're outside your expertise and sliding us towards the worst of Popular Science. no offense; i know you don't know.

The main problem...

[Muerte23]

Is the precise timing required by the whole system. You see the vertical wheel with the notch? That notch has to pass the little wings on the rotor exactly on two sliding surfaces.

Those tight fit parts that absolutely fly by each other have to meet, slide, and keep a pretty good seal. Each time the timing chain is a little off, say to increase or decrease in power, they will miss a little, bonk, and get worn. Hot exhaust gasses slipping through will probably cause preignition in the little transfer tube. Nasty.

Also notice how much physical distance the compression arms of the rotor have to move each cycle. Can you imagine the heat from friction and the lubrication required? And the kinds of seals that you would need? I guess you could get decent lubrication by using the rotor as some sort of centrifugal oil pump, but still the wear would be nasty.

Consider as well that it's basically a 2 cylinder 4-stroke engine. It's gotta be a pretty good size and run at a pretty high RPM to get enough power to be really useful.

Don't count on this one.