Environmental legislation is becoming more and more stringent and requires a significant reduction in the fuel consumption and pollutant emissions caused by future vehicles. Apart from exhaust treatment or optimised combustion procedures, supercharging internal combustion engines is a major contribution towards achieving this end. It allows for the so-called downsizing which means that a comparable performance can be generated by using engines that have a smaller piston displacement and/or fewer cylinders. This increases engine efficiency as it considerably reduces losses by internal friction.
Supercharging an internal combustion engine always requires a compressor to deliver the fresh air flow under high pressure. Supercharging systems differ by the method used for driving the compressor. This can be done by a separate electric motor (e-compressor), by direct coupling to the crankshaft (supercharging) or by using a turbine to withdraw energy from the exhaust gas which would otherwise escape to the atmosphere without being used (turbocharging).
