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Rotary Valves Make Normal Valves Look Silly - Why Aren't We Using Them? - YouTube (youtu.be)

submitted 2 months ago by BallShapedMan to c/cars

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I had no idea this type of valve was a thing. Interesting to learn a little about. Maybe something like this would make electrically controlled variable timing more viable and thus improve the efficiency of ICEs?

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[–] [email protected] 4 points 2 months ago* (last edited 2 months ago) (1 children)

I'd say a rotary engine exposes the difficulty/challenge of rotary valves, as it's essentially one big rotary valve.

Sealing has always been a bitch, especially as the seals wipe across the intake/exhaust openings. With a rotary valve on a piston engine, I wonder how the compression forces would impact valve sealing and rotation, where conventional valves are forced closed by compression.

I imagine the bigger issue would be airflow dynamics because of how such valves open.

I'm sure these have been considered, and not used for specific reasons.

[–] [email protected] 1 points 2 months ago (1 children)

I had the same thought, these seals aren't containing oil like a camshaft seal, they're actually dealing with compression forces. Maybe not directly, but still there's a pressure differential.

I didn't think of airflow dynamics, but yeah this thing is basically the lever valve thing in your garden hose adapter spinning at a few thousand rpm regulating combustion gasses. I could see it doing weird stuff when the valve is only partially open, especially when it starts to close.

[–] [email protected] 1 points 2 months ago

Exactly.

I hadn't really visualized it at speed either - I can only imagine the turbulence then.