Investigation of Rail Pressure Drop During Diesel Fuel Injection

Injection flow of high pressure common rail diesel injectors can be affected by carbon deposition or nozzle wear, leading to cylinder-to-cylinder variation of injection quantity and then causing poor engine performance. In this paper, rail pressure variation during the fuel injection was investigated in a high-pressure common-rail diesel fuel system. The rail pressure was collected at a frequency of 10 kHz on a fuel pump test rig and its variation characteristics were obtained by a wavelet transform processing method. The relationship between the fuel injection flow and the rail pressure variation was determined. The results show that the rail pressure drop occurs during the fuel injection, and the rail pressure drop rate is monotonically positively correlated with the injection flow rate. In addition, the total amount of rail pressure drop caused by the fuel injection is also positively correlated with the total amount of fuel injection. Multiple injection is found to be little effect on rail pressure drop. In order to ensure the same rail pressure drop for multi-cylinder fuel injections, a control method based on modifying the injection pulse width was proposed and the consistency of injection flow rate was verified by experiments. © 2022, Editorial Office of the Transaction of CSICE. All right reserved.