Patent ID: 7006913

Claim:
Method for finding the angular acceleration of a drive shaft ( 4 ) of an internal combustion engine ( 1 ) using a gear wheel ( 5 ) integral with said drive shaft ( 4 ); the method comprising the steps of: identifying, in each complete revolution of the drive shaft ( 4 ), a number of angular measurement lines having the same amplitude, determining, in the course of an engine fuel cut-off phase ( 1 ), values of correction coefficients (K i ) that take account of asymmetries in the gear wheel ( 5 ) relative to the angular measurement lines, measuring the time (T i ) used by the drive shaft ( 4 ) to pass over each angular measurement line using the signal supplied by the gear wheel ( 5 ), adding algebraically, to the time used by the drive shaft ( 4 ) to pass over each angular measurement line, a corresponding correction coefficient (K i ), and determining the value (acc) of angular acceleration of the drive shaft ( 4 ) as a function of the time (T i ) used by the drive shaft ( 4 ) to pass over each angular measurement line; wherein the determining of the values of the correction coefficients (K i ) comprise the further steps of: recording in the course of a fuel cut-off phase a succession of times (T i ) used by the drive shaft ( 4 ) to pass over the angular measurement lines is during half a combustion phase if the number (ncyl) of cylinders ( 2 ) is even and during a whole combustion phase if the number (ncyl) of cylinders ( 2 ) is odd; determining, using the succession of times (T i ) used by the drive shaft ( 4 ) to pass over the angular measurement lines, a straight line (r) that interpolates the ideal course of the evolution of the times (T i ) used by the drive shaft ( 4 ) to pass over the angular measurement lines in a plane angle (θ) of the drive shaft ( 4 )/time (T); and determining, for the i-th angular measurement line, the absolute value of the correction coefficient (K i ) as the difference between the measured value of time (T i ) used by the drive shaft ( 4 ) to pass over the i-th angular measurement line and the corresponding value of time (T pi ) used by the drive shaft ( 4 ) to pass over the i-th angular measurement line obtained on a straight line (r) as a projection at a constant angle of the measured value.