Called the Free Piston Engine Linear Generator (FPEG), the main purpose of this power plant – unlike conventional internal combustion engines - is to generate electricity.
Toyota says the new design is smaller and lighter, as it does not require connecting rods or a crankshaft (hence the ‘free piston’ reference).
In place of those parts, the combustion process acts like a ‘spring’, returning the piston to the top of the combustion chamber after each ignition stroke to begin the process again. The fuel-burning process itself shares some similarities with a two-stroke engine.
While conventional petrol and diesel engines can be used to drive a generator, the FPEG design generates electricity internally, as the piston itself contains a magnet and the chamber surrounding it acts as a coil.
Toyota says its initial design is only producing 10kW for now, but just two of these FPEG cylinders can produce enough electricity to keep a light or small-sized vehicle travelling at a steady 120km/h.
The Japanese carmaker believes that two cylinders could be the ideal set-up for its new design, ideally horizontally-opposed like a ‘boxer’ engine to minimise vibration and harshness.
Mitsubishi’s recent Outlander PHEV arrival uses a 2.0 litre petrol engine, acting as generator while also able to drive the front wheels.
Holden’s Volt is currently fitted with a 1.4 litre four-cylinder engine to generate electricity, but reports last year suggested GM would also be looking at smaller engines for the next-generation Volt.
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