A fake Wankel engine

[mklotz]

I call this engine WANKELIKE because it looks something like a Wankel but really isn't. The familiar Reuleaux triangle-shaped rotor of the Wankel has been replaced with a simple cylinder and the epitrochoid-shaped chamber has been replaced with a cartouche-like opening.

This makes it easier to machine but introduces a weird geometric constraint. The "cylinder" has to move up and down when the engine is running! What can I say; it's a silly design, totally impractical but makes for excellent eye-candy at model engineering shows.

At the beginning of the video I turn it over slowly by hand so you can see the piston inside the chamber. Plexiglass chamber walls make it visible but guarantee the engine will never be run on steam. Note that the piston is offset on the crankshaft and it's this motion that forces the chamber to move up and down as the crankshaft rotates.

All the valving, intake and exhaust, is done via a central channel in the crankshaft that admits air to channels in the piston that communicate with the vacancies in the chamber. The engine is completely symmetrical so it can be reversed by simply interchanging the intake and exhaust.

Building the engine takes some care. The two biggest items are getting the chamber moving smoothly on the uprights and sealing the chamber.

[Toolguy]

That is an interesting design. Similar to a Scotch yoke in some respects. Very nice!

[mklotz]

This query from "metric_taper" was asked in another post...

"I looked through all your engine models. I like the "Wanklelike", with eccentric piston and oscillating cylinder. I can see the exhaust port, on the eccentric, I'm guessing the input port on the backside uses some other porting on the eccentric as well acting as an flow control valve for the compressed air inlet."

but the response to it really belongs here...

Surprisingly, the hole in the "piston" visible in the video serves no purpose at all in the operation of the engine. All inlet and exhaust is done via central channels in the crankshaft. Connectors in the bearing standards connect with these central channels which in turn connect with radial channels in the piston that open into the cavities in the moving engine block.

This arrangement is completely symmetric which means that the engine can be run in reverse by simply interchanging the inlet and exhaust connections.

[metric_taper]

Surprisingly, the hole in the "piston" visible in the video serves no purpose at all in the operation of the engine. All inlet and exhaust is done via central channels in the crankshaft. Connectors in the bearing standards connect with these central channels which in turn connect with radial channels in the piston that open into the cavities in the moving engine block.

This arrangement is completely symmetric which means that the engine can be run in reverse by simply interchanging the inlet and exhaust connections.

That makes sense, with the shaft ports and bearing plate providing the timing of the pressure and exhaust ports.

I recall a 1961 Popular Mechanics article on the Wankle (new at that time). I think it touted 90MPG and 300Kmile engine life. I don't know how anyone could think a sliding seal could have any longevity especially with combustion artifacts fouling on a continuum.