Super-compact internally rotating combustion engine packs a solid punch
Michael Arsenaeu designed the Avadi engine 20 years ago in the hopes of creating an entirely new engine design to be efficient as well as reduce emissions. In 2015, Avadi began the build and development.
Rotary might be a good name for this sort of engine, if the name wasn't already taken. Everything inside the crankcase rotates, but unlike a Wankel-style rotary engine, this design uses a piston with two connecting rods that have a scissor-like movement attached to pinion gears at the back of the engine.
All of this rotates on a fixed ring gear connected directly to the output shaft. It uses a valve disk that also rotates to complete a four-stroke cycle of intake, compression, combustion, and exhaust as everything rotates internally.
According to Avadi's website, "two connecting rods and their corresponding pinion gears reside in what we call a 'halfshaft.'... the halfshaft can be likened to the heart of the Avadi design, it is essentially the housing where up-and-down piston motion is translated to rotational motion."
Unlike a Wankel rotary engine, the Avadi eliminates the traditional crankshaft entirely, as the cylinder and piston rotate within the case during its stroke. Everything very much looks and functions like what you'd see in a rear differential – if differentials had pistons connected to planetary gears.
