Patent ID: 6705291
Filing Date: 2004-03-16
Classification: F02D,H01L,H02N

Abstract:
Fuel injection system comprising a piezoelectric element (10, 20, 30, 40, 50 or 60) for controlling the amount of injected fuel, characterized in that the fuel injection system comprises a control unit (D) for determination of a possible fault of the piezoelectric element (10, 20, 30, 40, 50 or 60) or of an electric circuitry driving the piezoelectric element (10, 20, 30, 40, 50 or 60) based upon a value related to the capacitance of the piezoelectric element (10, 20, 30, 40, 50 or 60) and in that the control unit determines the value related to the capacitance of the piezoelectric element (10, 20, 30, 40, 50 or 60) based upon the quotient of the second voltage and the charge the piezoelectric element (10, 20, 30, 40, 50 or 60) is carrying, based upon the quotient of the charge the piezoelectric element (10, 20, 30, 40, 50 or 60) is carrying and the second voltage, based upon the quotient of the difference between the second voltage and the first voltage and the product of the charging time and the current charging the piezoelectric element (10, 20, 30, 40, 50 or 60), or based upon the quotient of the product of the charging time and the current charging the piezoelectric element (10, 20, 30, 40, 50 or 60) and the difference between the second voltage and the first voltage.