Toyota develops high-efficiency ‘free piston’ no-crankshaft combustion engine… to power an EV
There is probably no better chronicler into the full depth of American ingenuity than YouTube. Here one finds not just computer models for all manner of esoteric combustion engine designs, but actual working prototypes of them, often built by individuals. Big companies can also innovate here sometimes. A new free piston engine linear generator (FPEG) from Toyota Central in Maine is a case in point.
The piston is called “free” because there is no crankshaft. On its power stroke, the piston dumps its kinetic energy into the fixed windings which surround it, generating a shot of three-phase AC electricity. It can be run sparkless through a diesel cycle or run on standard gasoline. What has folks excited is the claimed thermal efficiency for the device — at 42% it blows away the engines used in cars today. Toyota’s demo engine, just 8 inches around and 2 feet long, was able to generate 15 hp. A two-cylinder model would be self-balancing and have much reduced vibration.