High Quality Diesel Fuel Injector Nozzle Dlla334n419

Research on the Influence of Needle Valve Movement of Diesel Engine Injector on the Injection Characteristics of Each Hole (part1 )

As emissions and fuel consumption regulations become increasingly stringent, internal combustion engines continue to move toward clean, efficient, and energy-saving directions. The strict emission regulations put forward higher requirements for the fuel supply system, and the fuel injection pressure can reach about 250MPa or even higher. High-pressure common rail has become the mainstream in the field of diesel engines due to its unique technical advantages, and the fuel injector, as the terminal actuator connecting the upstream high-pressure common rail system and downstream fuel injection, is self-evident. The needle valve couple not only carries the role of fuel lubrication, sealing and circulation, but also acts as a direct execution part of fuel injection, which determines the characteristics of fuel injection and spray, and then affects the subsequent fuel-gas mixing quality and emission characteristics.

The needle valve assembly is composed of a needle valve and a needle valve body. With the continuous increase of the high-pressure common rail injection pressure, the flow of high-pressure fuel in the nozzle (composed of needle valve assembly, pressure chamber, etc.) not only has a high Reynolds number The instantaneous turbulence of the jet is accompanied by cavitation caused by pulse contraction and fluid vortex motion, forming a complex gas-liquid two-phase flow, which in turn affects the fuel atomization quality at the outlet of the nozzle hole. Based on this, from the perspective of the transient motion of the needle valve, this paper analyzes the influence of the regular motion (without considering eccentricity) and irregular motion (considering eccentricity) of the needle valve on the internal flow and injection characteristics of each hole, and develops a method that considers the compressibility of fuel oil. Based on the gas-liquid two-phase transonic flow model in the nozzle, the influencing factors of the elastic deformation and eccentric motion of the needle valve are explored, which provides a theoretical basis for optimizing the design and manufacture of the injector.