Design Of High Pressure Common Rail Pipe Assembly With Distributor And Research On Hydraulic Process

The high pressure common rail system is famous for precisely controlling the injection pressure and timing.Its application has greatly improved the energy efficiency and fuel economy of diesel engines.However,the expansion wave and pressure wave caused by intermittent fuel supply of high-pressure fuel pump,lifting and seating of injector needle valve seriously affect the stability of fuel pressure and the accuracy of fuel injection,thus affecting the combustion process of fuel in the cylinder.Therefore,it is of great significance to study the generation and propagation of pressure waves in the high-pressure common rail system.For medium and large diesel engines,due to the limitation of diesel engine installation and layout,the processing difficulty of long rail pipe is far more than that of two short common rail pipes.To solve the fuel distribution problem,according to the structural layout characteristics and technical requirements of V-type 12 cylinder diesel engine,a high-pressure common rail assembly with distributor is designed in this paper.The main contents of this topic are as follows:1.Briefly describe the main structure and working principle of the high pressure components of the system,carry out the general layout and conceptual design of the high pressure common rail pipe assembly with distributor,establish physical and mathematical models,and briefly describe the mathematical models of key components.Through the establishment of three fuel supply simulation models,combined with rail pressure fluctuations and fuel injection consistency results,the advantages of high-pressure common rail system with distributor are obtained.2.The influence of the system with distributor on the pressure fluctuation characteristics under different working conditions(changing the structure parameters of distributor,target rail pressure and injection pulse width)is deeply studied.The results show that the smaller the inner diameter of the distributor,the greater the rail pressure fluctuation;The longer the distributor is,the smaller the rail pressure fluctuation is.Due to the limited installation space,it is necessary to reasonably design its structural dimensions.The inner diameter of the distributor designed in this paper is 10.6mm,and the length is 234 mm.Then,starting from the target rail pressure and injection pulse width,the change rule and influence mechanism of hydraulic characteristics are discussed,and the technical feasibility of adding a distributor is verified.3.In order to further analyze the influence of the distributor on the flow field characteristics of the high-pressure oil circuit of the common rail system,a three-dimensional model of the high-pressure pipeline with the distributor is established.The injection process of No.1 injector and the fuel pressure distribution and velocity distribution at the center section of each pipeline during fuel supply are mainly analyzed.The generation and interaction of pressure wave and expansion wave in high-pressure pipeline are also described.The research shows that the distributor can effectively restrain the pressure fluctuation in the high-pressure pipeline,which verifies the rationality of the design of the common rail pipe assembly with the distributor.