"funkyoldcortina" wrote in message
...

Forget the Prius, although an amazing ground-breaking car, the Volt's setup
will be the norm in a few years time. Range extenders using Wankel and
free-piston engines will be around.

The free-piston engine with a linear generator is being investigated by a
number of research groups, driven by the increasing interest in the hybrid
electric vehicle concept in the automotive industry.

The first free piston generator was patented in 1959, and since then, a
number of variations have been proposed. Examples include the Stelzer engine
and the Free Piston Power Pack manufactured by Pempek Systems based on a
German patent. These engines are mainly of the dual piston type, giving a
compact unit with high power-to-weight ratio. A challenge with this design
is to find an electric machine with sufficiently low weight, and control
challenges in the form of high cycle-to-cycle variations have been reported
for dual piston engines.