A STATISTICAL ANALYSIS OF DIESEL PIEZO INJECTOR FUEL INJECTION TIMING AND DURATION MEASURED WITH A PHOTOSENSOR

When a piezo-type diesel injector was driven using various current patterns, the fuel injection start and stop timings were measured with a photosensor. The photosensor was positioned as close as possible to the piezo injector nozzle hole to accurately capture the start and stop timings. The charge currents for driving the piezo injector were controlled in nine different patterns. A peak-and-hold current waveform was generated using a microcontroller with pulse width modulation (PWM) control. The fuel injection duration was set to 1.0 ms. The common rail pressure was regulated in five cases: 30 MPa, 50 MPa, 70 MPa, 90 MPa, and 120 MPa. To analyze the uncertainty in fuel injection start timing and duration, measurements were repeated 33 times for each experimental condition. Among the nine current patterns used to drive the piezo injector, the pattern with the smallest variations in fuel injection start timing and duration was investigated. It was found that the peak current value had a significant impact on the variations in both injection start timing and duration.