Patent ID: 8527185

Claim:
A vehicle comprising: an internal combustion engine; an exhaust system having a set of fuel injectors adapted to inject fuel into a stream of exhaust gas from the engine, wherein the exhaust system is operable for selectively igniting the fuel after the fuel has been injected into the exhaust gas to thereby purify the exhaust gas; an air compressor operable for compressing intake air, and for delivering the compressed intake air to the engine; a turbine adapted for converting the exhaust gas from the engine into mechanical energy for powering the air compressor; a first sensor adapted for measuring an inlet temperature of the intake air entering the air compressor; a second sensor adapted for measuring an outlet temperature of the exhaust gas exiting the turbine; a third sensor which measures a mass flow rate of the compressed intake air entering the engine; and a controller operable for calculating an engine thermal efficiency value as a function of the inlet temperature, the outlet temperature, and the mass flow rate; wherein the controller uses the engine thermal efficiency value to maintain a temperature of the exhaust gas downstream of the turbine above a calibrated threshold temperature.