That said if we have to grant patents, this is a great example of the sort of idea that should be recognized (assuming of course that there isn't prior art).  Engineers from +General Motors and the University of Michigan including Paul Najt who I interviewed on several occasions during my years as a journalist at AutoblogGreen have come up with an interesting new way of powering an extended range electric vehicle like the +Chevrolet Volt.

Because of the very short four-year development cycle for the Volt, the engineering team opted to use a conventional and proven 1.4-liter four-cylinder reciprocating engine to drive the generator once the battery has been depleted of energy from the plug. While this setup works remarkably well, it's not necessarily the most efficient setup for running in charge-sustaining mode, hence the Volt's 37 mpg EPA rating in this mode.

During and beyond the development phase of the first-generation Volt, engineers at GM R&D and Powertrain have been working on a wide range of alternative powerplants for use with the ER-EV Voltec system. http://amzn.to/QiSPQF

These alternatives include conventional diesels, Wankel rotaries, hydrogen fuel cells, HCCI and other less well known types. Among those options are free-piston engines http://www.popularmechanics.com/cars/news/industry/5-alternative-engine-architectures#slide-4

There are a number of ways to implement the free-piston concept but all of them involve a piston that "bounces" back and forth between a pair of combustion chambers that alternate firing. While it's possible to use this architecture in a completely mechanical form by linking the pistons to drive a transmission, the patented concept here converts combustion energy to electricity. 

By incorporating magnets and coils into the oscillating piston and the stationary cylinder, the motion can be used generate electricity. A free-piston layout inherently has lower friction than a traditional design. The mechanical simplicity means that engineers can set up a modular configuration several independent engine/generators that can be turned on or  off as needed based on transient power needs.

Because each generator operates independently, there are no frictional losses from the modules that aren't running. The result is potentially significantly improved overall efficiency in charge sustaining mode as well as greater packaging flexibility. It will be interesting to see if this idea ever goes beyond the concept stage. 

Via GreenCar Congress http://www.greencarcongress.com/2012/11/fpla-20121125.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+greencarcongress%2FTrBK+%28Green+Car+Congress%29