You've heard of radial engines and rotary engines, you probably also know a piston radial has a fixed cylinder block and a rotating crankshaft. A pistonless rotary like the Wankel has the same fixed engine block and a rotating rotor, while a piston rotary, looks like a radial, but the cylinder block rotates around a fixed crankshaft. So far, so good. So, what's a radial bi-rotary engine? As you've probably guessed by now, it rotates both the crankshaft and the cylinder block, but in opposite directions, and that is what we have here, the Radial Bi Rotary Balanced Piston Combustion Engine by Devaere Engineering. After the Circle Cycle engine we wrote about a few days ago, Franky Devare thought we might like to see what he has been working on.
In this engine, the rotating cylinders are open topped and move past intake and exhaust ports, the engine works in normal four stroke fashion and modifying the position and size of the ports, can serve to create the effects of an EGR valve with a small overlap of the ports, or even make this an Atkinson cycle engine where the power stroke is longer than the compression stroke by elongating the intake port which shortens the compression stroke.
The engine is smooth and generates no rocking couple between cylinders. The counter rotating block and crankshaft decreases gyroscopic forces and the speed of the relative counter rotation, which can be changed depending on planetary gearing selected in the design gives the engine a higher effective rpm in relation to the actual rpm in either direction. The fixed ring inlet ports also eliminate the valve train, simplifying construction. The size of the ring and number of cylinders affects the number of ignitions per revolution.
The engine's natural element would be in aviation, but as you can see by the concept motorcycle at the beginning of this article, it could be used in many other applications. In fact, it could even be inside the wheel instead of mounted in the frame as shown above.
The Devaere Engineering website shows the long history of the design and engine families that have led to the development of this particular engine. I would very be interested in seeing a running example.
Thanks to Franky Devaere for sending us the pointer.
Have we exhausted the possible variations of internal combustion engines yet? My guess is absolutely not. Amazing.
Link: Devaere Engineering
Video animation below: