New Injector Nozzle Dlla140p1790 0433172092 for Fuel Injector 0445120141

1. Fuel temperature field in the gap between the needle valve coupling parts:

When the needle valve reciprocates, the kinetic energy lost by the shear flow friction between the needle valve couple and the gap fuel is converted into heat energy, the temperature of the gap oil film gradually rises, and the fuel will expand when the temperature rises, so that there is an additional pressure on the gap oil film Field, the load capacity of the oil film increases, this phenomenon is the thermal wedge effect. When the shear flow is not considered, the fuel flow rate is reduced due to the wall viscous resistance. When the needle valve is stationary or moving at a low speed, the pressure loss of the fuel is all converted into heat energy. In a short time, heat is difficult to transfer to the solid wall, so it is simplified as an adiabatic process. Due to the friction of the fuel shear flow, the temperature of the fuel increases and expands to form an additional pressure field, which makes the fuel flow, which is called hot wedge flow. The thickness of the oil film affects the carrying capacity of the oil film temperature rise. As the thickness of the oil film becomes thinner, the temperature rises and the carrying capacity gradually increases.

2. Influence of structural parameters of needle valve coupling on sealing characteristics

For the injector, due to the small volume of the oil tank, the sealing performance of the needle valve coupling is reduced, which will greatly reduce the pressure in the nozzle pressure chamber. Therefore, a reasonable gap is very important for the sealing characteristics of the needle valve coupling. Considering the processing technology and leakage loss at this stage, generally take 2~4μm.