Let me preface this by saying I'm pretty new to the rotary engine. I have a basic idea of how they work but not much beyond that. Anyway, here goes.

Use this picture for reference if you're not sure what I'm talking about: http://home.att.net/~mazdarx8/901-0186_IMG.JPG

1] Seems like the rotor tip seals are awful short. I thought they would stick out more beyond the rotor. They must be engineered to not wear down the slightest little bit because it looks like if they did the rotor would contact the housing (and I'm guessing this would score the housing).

2] Why is the recessed portion of each rotor face done with a relatively sharp edge? I know that in piston engines, sharp edges and points in the combustion chamber are a bad thing (they encourage detonation for one). I would have thunk the same would apply to a rotary's combustion chambers. I wonder if any performance benefits would be realized with some machine work done to a rotor to smooth out those edges.

Thoughts?

 

Hi BryanH,

Quick thoughts, before I go to bed for a few hours.

1) I assume you mean that the apex seals don't look like they extend very far from the "triangle". The tips are hardened so that wear is minimal but they have nothing to do with keeping the rotor from contacting the housing. The rotor path follows the circular gear thing and it will not touch the housing (even without any apex seals). The apex seals also have a spring behind them so that as the tip wears a little, they can extend a bit more.

2) NA rotaries are extremely resistant to detonation since the intake, compression, ignition and exhaust "strokes" all take place in different areas of the engine. I believe the recesses in the rotors are machined now so they are all the same spec. You will have less performance if you try to machine the edges of the bathtub smoother because you will decrease the compression ratio.

Brian

 

1) Like Buger said, the seals don't locate the rotor, the cycloidal gearing does, seals or no. The seals in the engine have springs that keep them in constant contact with the housing as they wear.

2) The depressions in the rotor have always been the same on each rotor face, as each side of the rotor goes through the same four cycles, just at different times.

I don't know about the edge thing, I'm not that well versed in combustion dynamics but perhaps with the shape of the combustion chamber in a rotary it's not that much of an issue?