Diesel fuel injection system is a core part in diesel engine. It has a significant effect on the economic performance, motivity and reliability to diesel engine, and it also has a strong impact on decontaminating exhaust gas, vibration and noise. Simulation is an effective way to analyze and study the diesel fuel injection system, which can analyze the influence of structure factors and running parameters to injection performance, so that optimize the fuel injection system, improve the economic performance and reduce the deleterious exhaust gas. Recently, along with the development of high pressure injection technology, many corporations, such as Bosch, Denso, Zexel etc., have developed new fuel injection system with different delivery valves for avoiding secondary injection and cavitation, and to guarantee the intensity and credibility of the system structure and the running stabilization of the engine in low speed situation [1][2][3][4]. In this paper, based on traditional structure of Pump-Pipe-Nozzle, the mathematical models of the fuel injection system are analyzed, and their simulation models are also built. And then, the fuel injection system models with damping valve, constant pressure delivery valve and constant volume delivery valve are calculated and simulated respectively. In the end, the influences to the fuel spraying performance of different delivery valves are compared and analyzed.
Math Models of Fuel Injection SystemThe common components in the injection system are flow valve, closed chamber, moving part, high-pressure pipe, etc. The math models of all these components are as follow Abstract: In this paper, the simulation of diesel fuel injection system using different kinds of delivery valves is studied. And the performance differences of the fuel injection system under different spraying pressure are compared. The influence of three basic delivery valves, which are damping valve, constant pressure delivery valve and constant volume delivery valve, to pump pressure, nozzle pressure, injection rate and secondary injection under the different spraying pressures are researched according to analyzing the performance parameters of injection pump with them. The simulation results show that the constant pressure delivery valve has obvious advantages in the injection time stability and avoiding secondary injection compared with the other two when the spraying pressure is low. On the other hand, when the pressure is high, the damping valve and constant pressure delivery valve have advantages in above mentioned, they can keep spraying pressure higher during the whole injection process, and the fuel droplet can reach a long distance, form a better spraying cone angle.