The VGT is a rotary piston engine. It combines the advantages of Wankel and piston engines – compact size and high torque output.

All major moving parts rotate in a perfectly circular motion, just like an electric motor or a gas turbine - which makes it the world’s first practical “Concentric Positive Displacement Engine”. All other positive displacement engines (including the Wankel rotary) utilize an eccentric motion to develop their compression and power. A concentric engine inherently has the lowest vibration, which contributes to efficiency and reliability.

Many of the engine parameters are variable while the engine is running. For example the displacement volume, compression ratio, inlet stroke, and exhaust stoke are a few of the possibilities. The parameters are varied by computer-operated solenoids activated by sensors and are part of the Engine Management System (EMS). The EMS makes it possible to change the displacement of the engine on demand and can yield superior fuel consumption and exhaust emissions compared to conventional engines.

Due to the absence of a crankshaft and the fact that all pistons are mounted at a constant distance from the center of rotation, the VGT engine has a constant torque arm that yields high torque values at low RPM. As a result, less gear shifting is required; which means the VGT operates with smaller gearboxes or a direct drive requiring no gearbox at all. This contributes to weight and cost savings.

Compression, combustion and expansion take place in isolated regions in the VGT engine. This configuration is ideal for running alternative fuels such as hydrogen.

The number of parts of the VGT engine is significantly lower than for conventional piston engines and most parts are easily manufactured using today’s technology.

http://www.roundengine.com