There isn’t really a clear diagram in either the article (which shows a conventional 4t engine) or video but this still works on a 4 stroke concept – an independent valve system with states ...

This means it is a reciprocating rotary engine. Yeah, weird stuff. The camshaft is also centrally located in the crankcase and still runs at 50-percent crankshaft speed but only actuates one valve ...

Term Reliability Bethlehem, PA – Warren Controls, a manufacturer of control valves and specialty fluid handling products, ...