This inside-out design solves most of the rotary engine’s problems

LiquidPiston's designs will show up first in UAVs and generators.

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[AusPeter]

I really need to see an animated cut-away operation of this motor. My head just can't get around the mechanical differences between this and a Wankel engine.

 

[thekevinmonster]

I really need to see an animated cut-away operation of this motor. My head just can't get around the mechanical differences between this and a Wankel engine.

Warped Perception on youtube did just that by doing a slo-mo see-through filming of one (something he has done for other engines):
View: https://www.youtube.com/watch?v=jLtyNtf9_ew&t=537s

 

[DeComposer]

LiquidPiston hass a video of how the engine works: https://www.liquidpiston.com/how-it-works

 

[davijoh723]

I really need to see an animated cut-away operation of this motor. My head just can't get around the mechanical differences between this and a Wankel engine.

Completely agree. My brain hurts from trying.

 

[dwrd]

LiquidPiston hass a video of how the engine works: https://www.liquidpiston.com/how-it-works

Wait, the 'X' engine? Noooooooo!

 

[Nowicki]

Between new engine designs, toroidal shape efficiency advancements, and new fuel types I cant wait to see how little fuel will be needed for various vehicles in the air, and sea.

 

[Arstotzka]

While cool, it really messes up one of my favorite explainers for how rotary engines work. (I still would like to drive an RX-7 or RX-8 in anger someday.)

 

[yurdle]

I've watched this develop for quite a while, and it seems to me like the difference in a standard electric motor vs a brushless motor, which should be such a no-brainer improvement that I've never understood their website directly soliciting investment.

It somehow has a as-seen-on-tv vibe, b/c it just seems too good to not be already developed and/or owned by Mazda or some other big manufacturer.

I truly hope it works out and makes it to market.

 

[solomonrex]

So the key is that the ignition is still in 3 places, and the inside still rotates, it's just oval and the outside is triangular, so it's inverted. I don't see why this is considered 'stationary' except perhaps with a Wankel, did it detonate anywhere along the inside of the oval, then? I don't think so, the spark plugs were still in fixed spots.

The video is brilliant, in fact, very clear. I'm just struggling with the explanation to see if I'm missing something. It looks like they changed the shapes, nothing more?

 

[yurdle]

Between new engine designs, toroidal shape efficiency advancements, and new fuel types I cant wait to see how little fuel will be needed for various vehicles in the air, and sea.

Toroidal props blow me away. How many item designs have been fully overlooked like props? And how large do they scale? It seems like they should be retrofitted to every ship out there if the gains work out on large industrial props.

 

[jhandojo]

This is the mechanical engineering nerd headache I didn't realize I needed today

 

[Nowicki]

Toroidal props blow me away. How many item designs have been fully overlooked like props? And how large do they scale? It seems like they should be retrofitted to every ship out there if the gains work out on large industrial props.

First thing that comes to mind are submarines. Their biggest thing is noise. They actually move slower than they are capable due to cavitation, and other similar things around noise.

 

[Tom Brokaw]

Surely every imaginable geometry has been tried in the last 150 years of internal combustion engine development. There has always been a demand for lighter, smaller, and more fuel-efficient engines. Is there more to this than just a novel chamber and rotor? If it's so good, why wasn't it done long ago?

The realities of commercial production mean that "good enough to make money" is a common plateau.

 

[jamesb2147]

So the key is that the ignition is still in 3 places, and the inside still rotates, it's just oval and the outside is triangular, so it's inverted. I don't see why this is considered 'stationary' except perhaps with a Wankel, did it detonate anywhere along the inside of the oval, then? I don't think so, the spark plugs were still in fixed spots.

The video is brilliant, in fact, very clear. I'm just struggling with the explanation to see if I'm missing something. It looks like they changed the shapes, nothing more?

Correct, but there's no more seal to maintain. Hence, increased efficiency and no more required rebuilds after some number of miles (in a car context). That's a meaningful improvement.

 

[Dr Gitlin]

The big problem with rotaries is their reliability. This comes down to the seals used, which don't really have any solution to oiling them properly. I don't see how this design solves that.... it doesn't.

You didn't read the entire article, did you?

 

[Tom Brokaw]

So the key is that the ignition is still in 3 places, and the inside still rotates, it's just oval and the outside is triangular, so it's inverted. I don't see why this is considered 'stationary' except perhaps with a Wankel, did it detonate anywhere along the inside of the oval, then? I don't think so, the spark plugs were still in fixed spots.

The video is brilliant, in fact, very clear. I'm just struggling with the explanation to see if I'm missing something. It looks like they changed the shapes, nothing more?

My takeaway is that the shape of the combustion "chamber" does matter, so changing that returns benefits.

 

[bsplosion]

The big problem with rotaries is their reliability. This comes down to the seals used, which don't really have any solution to oiling them properly. I don't see how this design solves that.... it doesn't.

RTFA. That's literally one of the biggest claimed innovations here - that the seals are no longer requiring oil like they previously did.

 

[alansh42]

"We can directly interface the apex seals with the face seals. Now that there are no gaps anymore, the blow-by is significantly reduced, and... we can directly lubricate the seals by metering tiny amounts of oil... right to the ceiling surface," Shkolnik said.

The quote literally says there are seals and they're oiled. Though "ceiling" is probably a typo for "sealing".

 

[Matthew J.]

Has anyone told Mazda about this?

 

[quamquam quid loquor]

Another is for a portable 10 kW generator, which is 75 percent lighter and far more compact than the US Army's current Advanced Medium Mobile Power Source generator, as well as being about 8 percent more efficient.

we've run on gasoline, kerosene, jet fuel, diesel, and even gaseous fuels like propane and most recently hydrogen,

75% lighter and can run on almost any fuel? Take my money! From the video, it should cost less to manufacture, since it uses far less material.

 

[solomonrex]

Ok so, super slow mo, in my words, I think the key is that the rotary part on the inside is part of the combustion chamber, that's what they mean by "it doesn't move" and the moving part that drives the rotor appears to have fins that capture the force of the explosion in motion. So the insides can be sealed up and etc, and the explosions still occur on the peripheral, but not entirely, the rotary part itself is taking the force of the explosion.

Here's the key wording from the quote above:
"we now have a stationary combustion chamber inside of the housing,"

It's moving like a Wankel, but the explosion is taking a different path through the center of the motor. It's still ignited on the periphery outside the moving piece, but the force is directed. So instead of hitting a wall at a slight angle, it's capturing more force along it's focused vector and hitting closer to 90 deg ideal like pistons have.

 

[eggie]

I still would like to drive an RX-7 or RX-8 in anger someday.

If it's a 2nd-gen 7, be ready for the rear-wheel "steering" under hard cornering. It is quite exciting the first time. In a brown shorts kind of way.

If it's a 3rd-gen 7 with basic power mods, be ready for the +25% torque gain when the 2nd turbo hits. Do NOT learn about this while turning.

 

[solomonrex]

Has anyone told Mazda about this?

Their regular SkyActive engines are actually brilliant and they need to focus on electric right now anyway.

But if this plays a part in automobiles, it would be hybrids no doubt, given that's it's already designed as a generator, which are very similar. Esp that four stroke space saving design.

 

[abie]

The apex seals are probably the biggest problem with a Wankel engine, but very high fuel consumption is also a major issue. A 2008 Mazda RX-8 with a 1.3 liter rotary engine only does 18 mpg combined according to the EPA, while only producing 212 hp/150 lb-ft torque. To put this into perspective, the contemporary 2008 Mustang GT with a 4.6 liter v8 also does 18 mpg combined and produces a much healthier 300 hp/320 lb-ft torque.

I glanced through the website looking for fuel consumption figures and didn't see any highlighted, so I assume that it's not great. The engine does however look much smaller physically and is lighter, so it is probably more suited for applications like aircraft and UAVs rather than automobiles.

 

[Emon]

The big problem with rotaries is their reliability. This comes down to the seals used, which don't really have any solution to oiling them properly. I don't see how this design solves that.... it doesn't.

lol what a classic armchair response.

1. Read headline and a few words from the intro
2. Recognize something you're vaguely familiar with
3. Remember something you heard the words you recognized in step 2
4. Drop a "well achksually" in a sad attempt to look smart.

Were you eating doritos while you wrote this drivel?

Don't answer that, I don't care.

 

[Emon]

The apex seals are probably the biggest problem with a Wankel engine, but very high fuel consumption is also a major issue. A 2008 Mazda RX-8 with a 1.3 liter rotary engine only does 18 mpg combined according to the EPA, while only producing 212 hp/150 lb-ft torque. To put this into perspective, the contemporary 2008 Mustang GT with a 4.6 liter v8 also does 18 mpg combined and produces a much healthier 300 hp/320 lb-ft torque.

I glanced through the website looking for fuel consumption figures and didn't see any highlighted, so I assume that it's not great. The engine does however look much smaller physically and is lighter, so it is probably more suited for applications like aircraft and UAVs rather than automobiles.

Articles can be read fyi

 

[lithven]

So the key is that the ignition is still in 3 places, and the inside still rotates, it's just oval and the outside is triangular, so it's inverted. I don't see why this is considered 'stationary' except perhaps with a Wankel, did it detonate anywhere along the inside of the oval, then? I don't think so, the spark plugs were still in fixed spots.

The video is brilliant, in fact, very clear. I'm just struggling with the explanation to see if I'm missing something. It looks like they changed the shapes, nothing more?

Based on the animations it looks like the change is whether the air/fuel mixture moves or doesn't around the chamber. In a Wankel the air/fuel mixture is input at one point in the chamber and then is moved to be compressed and combusted at a different point, and finally exhausted at a third fixed location on the cycle. In this engine it looks like you have three independent chambers that each intake, compress, combust, and then exhaust without the air/fuel mixture moving around the entire chamber. So the stationary part is the air/fuel mixture not any mechanical part of the engine.

But maybe I'm completely misunderstanding.

 

[Anton Longshot]

Has anyone told Mazda about this?

RX-X sounds great. WANT!

 

[thekaj]

Toroidal props blow me away. How many item designs have been fully overlooked like props? And how large do they scale? It seems like they should be retrofitted to every ship out there if the gains work out on large industrial props.

Now I'm salivating over the idea of replacing the engines in our boat with something substantially smaller yet equal in power. Pleasure craft engine compartments are seemingly designed to be about 80% the size of the engines they cram in there. Things like replacing spark plugs or even adding oil require being a contortionist and doing things by feel alone. Looking at the size differential in the story photo, doing any work on that engine would be a breeze.

Of course, boat manufacturers will immediately reduce the engine compartment size to compensate and be right back to forcing people to be double-jointed. But existing boat owners will definitely rejoice.

 

[85mm]

Ultra light and very powerful. I would have liked to have seen an old Lotus designed around one.

 

[Sarty]

I glanced through the website looking for fuel consumption figures and didn't see any highlighted, so I assume that it's not great. The engine does however look much smaller physically and is lighter, so it is probably more suited for applications like aircraft and UAVs rather than automobiles.

Other articles quote about an 8% reduction in fuel burn relative to the diesel generator they're trying to replace. Difficult to be sure how much that's projected and how much it's proven in testing, but it would be a surprise for fuel burn to be substantially worse than reciprocating.

 

[Emon]

RX-X sounds great. WANT!

I always really wanted an RX-8 in college and thought I'd buy one when I graduated and got a real job.

Instead I kept my 2002 Saturn until 2015 and then bought a Subaru because it was more practical.

Younger me: omg I want a cool car

Real world me: how accessible is the oil filter? Is changing my oil going to be annoying?

(Answer, on a Subaru, the filter is right there when you open the hood. Fuck removing quarter panels to change your oil)

 

[Boskone]

Gotta admit, this screams "PHEV auxiliary power" to me.

Unless the downside we're not seeing is all that catastrophic (and I just assume everything I read/hear has an unstated downside), it seems like a near-perfect use.

 

[kkeane]

Not sure how relevant this is for cars, but improving generators may be HUGE. I'm not quite clear about what the actual improvements will be. Hopefully, it will at least be lighter and cleaner.

We just had our fourth 8-hour power outage of the year, and it's just the beginning of outage season. Dealing with a traditional generator is a PITA, even though they have improved.

 

[eggie]

The big problem with rotaries is their reliability. This comes down to the seals used, which don't really have any solution to oiling them properly.

Mazda Wankels have 2 main reliability issues. Neither is about apex-seal oiling or wear under normal conditions.

Issue 1 is that the apex seals are incredibly intolerant to detonation. Real world, this is mostly an issue with modified turbo engines.

Issue 2 is that the rotor housings are aluminum, the plates are iron, and everything seals with o-rings under low clamping pressure. IOW, the engine is incredibly intolerant to overheating.