[negativity]

This is a version of a Wankel Engine, right?

https://en.wikipedia.org/wiki/Wankel_engine

Originally invented and patented way back in 1929.

[tim333]

Not a Wankel:

http://pop.h-cdn.co/assets/cm/15/05/54caf9230d439_-_liquidpi...

[jccooper]

Similar concept, different geometry. It's almost like an inverse Wankel. Perhaps this geometry is easier to handle wrt seals and lubrication. The points of the Wankel triangular rotor have always been difficult.