METHOD AND DEVICE FOR DETERMINING THE ACTUAL START OF INJECTION OF A PIEZO FUEL INJECTION VALVE

摘要

A method for determining the actual start of injection is performed by an actuating device for a piezo fuel injection valve and includes the following steps. First, a test injection is carried out with such a short actuation duration that a start of shut-off takes place at a time so early that the nozzle needle does not reach the open end position. Said time is predefined by the actuation and is therefore precisely known. Next, the closing time of the nozzle needle is then determined by measurement and evaluation of an electrical variable of the piezo direct drive. Once the closing time and the time of the start of shut-off are known, the actual start of injection is calculated back from the closing time via the start of shut-off. This permits an adequately precise determination of the actual injection quantity in almost every operating state of the internal combustion engine.