System for diagnosing error conditions of a gas flow control system for turbocharged engines

摘要

A combustion engine evaluation unit is disclosed which com­prises a microprocessor for receiving measurement signals from a gas flow control system of a combustion engine and for outputting a state signal indicating a state of the gas flow control system. The microprocessor provides input ports for receiving a first set of measure­ment signals which comprise at least a signal of a pressure upstream of a turbocharger and a signal of a pressure down­stream of a turbocharger. Moreover, the microprocessor provides input ports for receiving a second set of measurement signal which comprises at least a motor revolution speed. The microprocessor is adapted to calculate a first set of pre­dicted values by using a turbocharger model, based on the first set of measurement signals and the microprocessor is adapted to calculate a second set of predicted values by us­ing a nominal model, based on the second set of measurement signals. The microprocessor is furthermore adapted to gener­ate the abovementioned state signal based on a comparison of the first set of predicted values with the second set of predicted values. Optionally the second set of measurement signals can comprise an actuator signal for adjusting a variable geometry turbine and an actuator signal for an exhaust gas recycling, EGR, valve.