Patent ID: 7720594

Claim:
A control method for a fuel injector having a piezoelectric stack that is charged by means of a charge current and that is discharged by means of a discharge current, the fuel injector, in operation, defining an injector closing time, the method comprising: determining a required separation time between: (i) a termination of an electrical on signal associated with a first injection event; and (ii) an initiation of an electrical on signal associated with a second injection event; calculating an overlap time between the required separation time and the time required to charge the piezoelectric stack to a first reference level using the charge current; dividing the overlap time into first and second time periods as a function of the charge and discharge currents; applying the charge current to the piezoelectric stack for a charge time calculated on the basis of the first time period of the overlap time; and applying the discharge current to the piezoelectric stack for a discharge time so as to discharge the stack to a second reference level; wherein the discharge time is calculated on the basis of the second time period of the overlap time, such that the first and second injection events are merged in a merging pulse mode of operation.