Interesting article on a split cycle engine, it makes me look at the 3 sided rotors and wonder if a split cycle rotary engine can be made?

 

I was thinking about this, and thought up a sort of "2 stroke" style rotary. My scanner isn't installed now, might have to update a picture later.

 

Seems like process a whole lot of moving parts.

 

I apologize in advance if this is too wordy or doesn't make sense. It's late and I'm only running on one rotor. Also, I am relatively new to rotaries so if something I say is wrong, please feel free to correct me. I'm just trying to get some discussion going with my understanding of what would be needed to make it work.

One of the main problems I'm seeing is the 20 degree lag between the pistons. To get a 20 degree lag in a rotary, you would have to rotate the lobes on the eccentric shaft such that they are not perfectly opposed. This would wreck havoc on the balance of the engine resulting in NVH issues or a heavy weighted flywheel to correct the balance. Either that or create a 4 rotor which is a whole nother can of worms.

The other option I'm seeing is, assuming you can get it to work with both rotors hitting TDC at the same time, is do a cross flow arrangement where the right side of the front rotor pairs with the left of the rear and vice versa. This would pair up the chambers without any change to the major moving parts of the engine. The problem with this is port/valve timing. The intake on the combustion chamber needs to open right as the rotor reaches TDC. Doing this on a rotary, from my understanding, would require peripheral ports. From here I see two options. One is ports right at the ends of the chambers which would be murder on apex seals and would not provide good flame spread because of the length of the chamber. The other is putting valves in the manifolds effectively like the valves in a piston engine. This could be made to work, but greatly increases the complexity of the engine reducing part of the rotary's allure and would be easier an more efficient with a piston engine since the infrastructure is already there.

If you have any ideas on how it could be done, I'm all ears. I think it's a cool idea, but right now I'm not seeing it. Who knows, maybe I'll think of something tomorrow.

Peace, Love, and Rotaries
-Tommy

 

Here's a thought, if each rotor only needs to preform two strokes, one idea is is to use two-sided rotors in single radius epitrochoid chamber. This would permeably reduce surface area to volume ratio and also increase the compression ratio. Each rotor would make one orbit and half-turn every full turn of the eccentric shaft.

 

So I don't know what is going on
But my Chrome browser blocked that phys.org link at the top
Indicating Malware

I've been to phys.org before ... guess they've been hacked

 

Yup:

Malicious software includes 273 trojan(s). Successful infection resulted in an average of 2 new process(es) on the target machine.

Malicious software is hosted on 3 domain(s), including novatag.org/, quickflange-training.com/, 4arabs.com/.

 

theoretical BS threads belong in General Discussion

 

i just skimmed the article, so my understanding of it is probably small. in the 80's Mazda took a patent out on a "low pumping loss" 3 rotor, and it works like they describe, there is an extra port in the iron, and it just goes to the other rotor.

so i think at the end of the compression stroke, instead of taking power to keep compression the mixture, it just goes into the other rotor.

since the patent is from the late 80's and they never did it, you could assume that it doesn't work well enough to justify the cost.

Mazda has been at the rotary for a long time and its very hard to find something that they have not tried. the recipe for sheer hp is pretty simple, and involves a rotor housing with two holes in it...

 

all rotor housings have at least two holes in them .... lol :D .... but im assuming you mean holes larger than spark plug holes

 

I disagree in part. There are lots of things that could have given the engine marginal gains which were either abandoned or never tried due to cost/complexity. These marginal gains which the piston engine has gotten every generation have continued to add up to major improvement while rotary engines tend to advance in spurts with painful growing pains. If you have an idea go ahead and try it, even if Mazda tried it and didn't implement it, that doesn't mean its a bad idea or doesn't work.

 

that is a good point, and some depend on the application too. the racing engines grew to be nearly completely different than the street engines by the end of the 80's.

i'm thinking the 16x, will actually finally get some of these upgrades, aluminum side housings, 3 spark plugs, etc.

i'm thinking the rotor faces will be pretty special in the new engine, look at the skyaktiv stuff.