Evaluation of the repeatability of fuel dosing by the Common Rail fuel supply system.
This study aimed to investigate and evaluate the repeatability of fuel dosage in a Common Rail fuel injection system under various engine operating conditions. The research focused on fuel injection processes for five distinct operating states: idling conditions, full engine load, mi-cro-dosing, full injector load, and high-frequency injector operation (to examine the injector\'s dividing capacity). The tests were conducted using an injection waveform indicator, enabling precise analysis of the dynamic characteristics of the fuel dosage process. The operation of the solenoid valve and the waveform of its supply signal were also analyzed. The waveforms of the supply signal were compared to the waveforms of injection pressure build-up. Additionally, in-tegral and differential injection characteristics were generated for each operating condition. The results revealed that the highest dosing non-repeatability occurred during small injection doses, i.e., at low injection pressures and short injector opening times. The coefficient of variation for micro-doses was 6.24% for injection volume and 7.81% for injection pressure. By contrast, under full engine load, these values were significantly lower at 0.43% and 1.45%, respectively. For other operating conditions, the repeatability of fuel dosage was high and consistent across conditions. The study concluded that the high inertia of the injector\'s moving components significantly affects dosing variability. The influence of inertia forces on these components becomes more pronounced during short injector opening times or low injection pressures.
Topic: Engine combustion
Author: Karol Dębowski
Co-authors: Mirosław Karczewski
