Patent ID: 8572964

Claim:
A method for recuperating energy from an exhaust gas flow of an internal combustion engine ( 10 ) of a motor vehicle, said method comprising the steps of: supplying the exhaust gas flow to en evaporator ( 16 ), in which a liquid working fluid under pressure is vaporized due to the transfer of heat from the exhaust gas flow to the working fluid, supplying the gaseous working fluid to en expansion machine ( 18 ) where the gaseous work fluid is expanded and where energy is obtained, and conducting the gaseous working fluid then to a condenser ( 22 ) for condensation therein to bring it back to the liquid state (Rankine cycle), and supplying the liquid working fluid to a pump ( 14 ) for pressurizing the liquid fluid before it is again supplied to the evaporator ( 16 ) by the pump ( 14 ), the pump ( 14 ) having a variable speed which is controlled based in dependence on a measured momentary exhaust as mass flow in combination with a variable representing the heat energy transferred by the momentary exhaust gas mass flow to the evaporator as determined with the aid of a performance graph established on the basis of exhaust gas temperature and exhaust gas mass flow values for the various engine operating conditions.