Free piston engine already invented

A free-piston engine is a linear, 'crankless' internal combustion engine, in which the piston motion is not controlled by a crankshaft but determined by the interaction of forces from the combustion chamber gases, a rebound device (e.g., a piston in a closed cylinder) and a load device (e.g. a gas compressor or a linear alternator).
The purpose of all such piston engines is to generate power. In the free-piston engine, this power is not delivered to a crankshaft but is instead extracted through either exhaust gas pressure driving a turbine, through driving a linear load such as an air compressor for pneumatic power, or by incorporating a linear alternator directly into the pistons to produce electrical power.

FPLG patent from 1943 - Pontus Ostenberg, USA by P. Ostenberg

 Here is the patent from 1943. The inventor obviously time traveled to 2016 and stole my idea.

We get direct electro, magnetic flows from windings on the piston rod. That yields a mostly one moving pat electric generator, great for hybrids.