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Steam Wankel II

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The Crower 6-Stroke is a reciprocating gasoline engine that adds a steam expansion and steam exhaust cycle to make it effectively: Intake, Compression, Combustion, Exhaust, Steam-Expansion, Steam-Exhaust. Well it seems to me the Wankel engine is a good candidate for this treatment.

This idea is based on the concept of having camshaft-controlled valves to close off and open different ports. No Wankels that I've ever heard of have ever used this before. The valves I propose to use I refer to as "garage-door" valves. The camshaft pushes these "doors" down with the lobe, then the springs push it up when the lobe is not pushing down. These "doors" are set in tracks to slide in and out of to provide a good seal and absorb any excess pressure. So now how my idea would work.

Normal Wankels have ports only for intake and exhaust. In my idea, there is a port for intake, a port in the compression area, and two ports in the exhaust area. Each port has its own "garage-door" valve and camshaft (except for the two exhaust ports side by side, of which both "garage-door" valves are controlled by the same cam. There are steam injectors for the Exhaust area and the Compression area. The cycle for the fuel combustion goes like this: Intake (the valve is open; the cam lobe is not pushing down), Compression (valve is down; cam lobe is pushing down), Combustion, Exhaust (one of the valves is up while the other is down). Immediately after this cycle is the steam cycle and it goes: Water Injection (immediately after the exhaust port from previous combustion cycle closes), Steam Expansion (where the Intake area for combustion cycle is; the Intake valve is closed by cam), Steam Exhaust (where the compression area for combustion cycle is; the valve is opened by cam), Water Injection II (right after the valve from Steam Exhaust closes), Steam Expansion II (where combustion occurs for fuel cycle), Steam Exhaust II (where the fuel exhaust is, remember how there are two valves in this area? The second one is now open). Then comes the combustion cycle again, then steam, etc.

The benefit to having all these valves is that you'll note no valves from the fuel combustion process are shared with the steam process, leaving dedicated paths for steam recovery. If you have a 2-rotor engine like the average, there are 3-cams and 8 garage door valves: not overly excessive. If you used a system like BMW's Valvetronic to vary valve lift, you could vary the port area to increase low RPM torque and high RPM power.

The gains? More power, more effeciency, a quieter engine (at any given RPM there are half as many fuel combustions compared to a normal Wankel), and no more carbon buildup (the steam would surely clean it out), no cooling system needed, and more low RPM torque (which Wankels desperately need).

[Edit: This would probably work even better with some sort of rotary valve]

acurafan07, Oct 28 2007

(?) Steam powered Wankel http://ghlin2.green...apatter/wankel.html
Looks just about identical to any other Wankel [acurafan07, Oct 29 2007]


       Hmmm, sounds very steampunk-ish. This is a worthy idea, if not a proficiently modern one. Strangely, I see many uses for this. (+) for an idea worthy of Felix himself.   

       BTW, although this is probably from my lack of sleep, the phrase "Steam Wankel" sounds funny in so many ways. Yeah, I need sleep.
Shadow Phoenix, Oct 29 2007

       Crower-Wankel? Recovering waste heat is good. [+] For the concept.
the dog's breakfast, Oct 29 2007

       Before I scrolled down, I looked at the title and knew it was [acura].   

       I think to get the extra expansion cycle, you have to have a different shape for the rotor and chambers. If I understand how it works, the Wankel is undergoing combustion, expansion, exhaust etc. all simultaneously; each side of the rotor is experiencing its own portion of the combustion cycle independently of the others as it progresses through the rotation. If you want each space to do a couple more things on its way round the chamber, then you'll have to add a lobe and another space to the "cylinder."   

       Now, that introduces extreme lean angles to the apex seals - really extreme.   

       There's also the possibility I simply don't fully realize what you're describing - a Wankel that is a gas engine part of the time, and a steam engine part of the time.   

       Whichever, I'm bunning it.
elhigh, Oct 29 2007

       This is more like an 8-stroke Crower Wankel. Since this has 2 steam expansion cycles per fuel cycle, do you think that each steam cycle would have to use less water than if there was only one steam cycle?
BJS, Oct 29 2007

       Thanks for the kind words, [Shadow Phoenix].   

       [BJS], yeah probably. Maybe something like a full-on first steam cycle and then a lower pressure second. In thinking about it, it might be easier to just compress the first steam cycle and then inject a little bit more water and have it all exhaust from the one valve. But then again maybe not.   

       [elhigh], I found a steam wankel engine online that doesn't look all that different from a fuel powered one. I'll try to find the link.
acurafan07, Oct 29 2007

       I reckon that in the first steam cycle the face of the rotor will be hotter than the walls because it just went through the combustion and exhaust. And I also reckon that in the second steam cycle the walls will be much hotter than the rotor because the walls where just exposed to the fuel combustion, and the rotor was just cooled by the first steam expansion.   

       So... I think that it would be best if the first water injector sprays right onto the rotor, and if there is some way for the second injector to spray onto the walls, that should be better, methinks.
BJS, Oct 29 2007


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