A Magneto-Elastic Sensor for Measuring Pressure Oscillations in Common Rail Systems

The trend in developing common rail injection systems goes to higher injection pressures and smaller minimum injected fuel masses. Multiple injection patterns generate pressure oscillations on the connection pipe between common rail and injector. These oscillations influence the amount and progression of the injected fuel mass and therefore the combustion process. As the oscillations depend on many different parameters, it is impossible to calculate their exact progression analytically. In this paper a new, non-invasive pressure sensor for measuring the pressure at the injector is introduced. It is based on the magneto-elastic effect and does not involve any mechanical elements. The physics on which the sensor is based are explained and the sensor design as well as a signal processing algorithm to reconstruct the pressure are illustrated. Measurement results are presented.