Another new engine that seems to be fading away...

[RodRico]

I never understood how the Nautilus HCCI Engine was going to work, even after I spoke with the inventor at length on the phone some time back. The engine has cylindrical bumps on the pistons that fit into their own cavity in the head. According to the inventor, the intake charge would be compressed to ignition in the small cavity then, as the piston descended, the combustion gases would flow into the larger cylinder where they would be expanded by a ratio far greater than compression (aka over-expansion).

I pointed out to the inventor that repeatedly retracting the bump from its chamber then pushing it back in would be a nightmare due to tolerances, and I questioned whether a seal sufficient for HCCI would be formed except at very high RPM. The inventor tried to answer my concerns, but I never fully understood what he was saying or how it addressed my concerns.

My first conversation with the inventor was shortly after their presentation at an SAE convention a few years back. At that time, the engine used electro-hydraulic valves as illustrated in the figure to the left. Shortly after obtaining investor funds and hiring an engineering team, the inventor announced the benefits of their new gas transport and valve system shown in the center image. About a year later, the inventor told me they were seeing great test results. I asked when they would be available for public review, and he said "soon." About the time I expected to see the test results, I instead saw him post an image of the newly refined engine which now features a spark plug.

I still don't understand what the bump on the pistons accomplishes other than increasing surface area and heat loss, and the addition of a spark plug is a pretty big step back from their original objective of pure HCCI.

Alas, the inventor is a nice guy, and he was well funded.

 

[PJGD]

He is not the inventor, he is the re-inventor; it is an old concept that is explained very well in patent GB1156821, and even that is not the earliest example of the idea.

PJGD

 

[RodRico]

PJGD,

You're right! It looks very similar. I wonder if Nautilus' investors know.

The full patent is available at:

http://pattakon.com/tempman/GB1156821.pdf

I would have precisely the same questions. At least the guy at

http://pattakon.com/pattakonPatBam.htm

recognized the need to seal the auxiliary chamber!

Rod

 

[GregLocock]

Maniolis at pattakon is an extremely clever chap and his ideas are well worth tracking.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[dgallup]

Side valves? Really, side valves??? I wouldn't give someone proposing side valves the time of day.

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[Pud]

Side valves? Really, side valves???

It's for a lawnmower? Small cement mixer?

www.tynevalleyplastics.co.uk

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[RodRico]

dgallup and Pud,

I know, right?

I can't find a definition of their target market anywhere on their web site (

http://nautilusengineering.com/dynamic-multiphasic-combustion-engine).

They do, however, claim multi-fuel operation in their white paper, so I would guess their market is "everything."

Rod

 

[BrianPetersen]

What problem are they trying to solve that isn't better solved some other way?

 

[dgallup]

Here's the market for side valves, it's long gone.

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[enginesrus]

Yeah funny stuff. What's old is new again.

 

[RodRico]

Brian, Holding my cynicism at bay, I think they were just trying to make HCCI work.

dgallup, LOL!

enginesrus, yup.

 

[BrianPetersen]

I recall reading about some interesting attempts at diesel engines early on (back when extremely tight machining tolerances were hard to do and CNC didn't exist) which used a low pressure injection system to put fuel into a little chamber like that and use a projection on the piston to squash it out into the main chamber and mix it with air.

 

[RodRico]

Brian,

It's also pretty easy to imagine an HCCI system in which a cam drives a small piston in a small chamber then either A) exposes the larger volume of the main cylinder to the resulting temperature/pressure to cause autoignition (similar to SkyActiv X use of a spark plug) or B) full combustion in the small chamber with over-expansion in the large chamber (the value of using a cam driving a small piston is simply that it can be driven so fast that it completes compression well within the fuel's ignition delay at the lowest RPM and can then be held there to satisfy the fuel's ignition delay at maximum RPM, thus solving the HCCI combustion problem). Whether or not either of these approaches would work or be worth doing, I can't say. Both, however, seem more likely to be successful than the Nautilus approach IMHO.

Rod

 

[moon161]

Those corners seem like they'd erode pretty quickly from the combustion gas as it's driven into the larger cylinder. The cylindrical port also seems like it would be a zone of briefly choked flow.