Sepp Hasslberger: No crankshaft, no problem: Toyota’s free piston engine is brilliant

05 Energy
Sepp Hasslberger
Sepp Hasslberger

Neat design for an engine that is also a generator of electricity. The idea has been around for some decades, but now Toyota has engineered one…

No crankshaft, no problem: Toyota’s free piston engine is brilliant

Jason Commisa

RoadTrack, 30 June 2014

Electrically driven cars are the future. But until we have cheap, 1000-mile batteries, we still need range-extending fossil-fuel engines.

Those devices don’t need to turn wheels, just generate juice. The simple solution is to strap a generator to a piston engine, as BMW did with the two-cylinder range extender in its i3 EV.

But if the engine never turns a wheel, there’s no need for it to rotate anything. Why not cut out the middleman and use the piston’s reciprocating motion to generate electricity? That obviates camshafts and most other rotating parts, too.

Toyota recently showed a prototype engine that does just that.It’s called the Free Piston Engine Linear Generator (FPEG). “Free” refers to the fact that the piston isn’t attached to a crankshaft; instead, as the piston is forced downward during its power stroke, it passes through windings in the cylinder to generate a burst of three-phase AC electricity.