Cylinder-Pressure Based Injector Calibration for Diesel Engines

One way of complying with future emission restrictions for diesel engines is to use pressure sensors for improved combustion control. Implementation of pressure sensors into production engines would lead to new possibilities for fuel injection monitoring where one potential use is injector calibration. The scope of this thesis is to investigate the possibility of using pressure sensors for finding the minimal energizing time necessary for fuel injection. This minimal energizing time varies over the injector's lifetime and therefore requires a re-calibration. The necessary energizing time can be found by estimating the injected fuel mass at dierent rail-pressures during a calibration state operating under specific engine conditions. Two dierent approaches based onin-cylinder pressure were used for fuel mass estimation. The result is based on a comparison to a non pressure based production line calibration function. Both fuel mass estimations show a correlation with convincingly accuracy for calibration use but with the possibility of further improvements. One approach is shown to be less sensitive to signal osets but more sensitive to noise. The oset sensitiveness can be reduces by changing measurement positions depending on user requirements. Compensations for energy losses depending on engine speed and cylinder dierences are shown to be necessary for calibration accuracy. Moreover are both injected fuel mass and rail-pressure shown to influence the combustion