Numerical Simulation of Pressure Fluctuation in High-pressure Common-rail Fuel Injection System

In the past several years, the global diesel engine technology has made significant breakthroughs. The diesel engine has a good economy and power. In 20 years or so, the number of diesel vehicles will exceed the trend of gasoline engines. Diesel engine technology is also developing towards low pollution, low fuel consumption, and high power. To improve the performance of diesel engines, the key is to improve the conversion rate of internal energy to mechanical energy and combustion degrees. In the fuel injection system of diesel engines, a high-pressure common-rail with a large volume is often added between the plunger high-pressure fuel pump and the injector. Its function is to save fuel from the plunger fuel pump, to suppress the fluctuation of oil pressure, and to output high-pressure fuel by adjusting the characteristic parameters of the injector. Firstly, the physical model and mathematical model have been established, including the plunger pump, the high-pressure common rail, and the injector. After that, we use the modified Euler method to solve ordinary differential equations by MATLAB programming. Finally, the Optimized working strategies of plunger pump to inject diesel oil into high-pressure common rail have been obtained. In this high-pressure common rail system, cam of the plunger pump spin 1225.67 times a minute, and pressure relief valve is opened automatically when the pressure in high-pressure common-rail is over 103 MPa, so that the pressure in high-pressure common-rail is approximately stable at 100 MPa, and the fluctuation is small.