Professional Manufacture 0 445 110 788 Diesel Injector Common Rail Injector Engine Parts Vehicle Parts 0445110788

Abstract
The structural design of a diesel fuel injector plays a decisive role in determining its injection accuracy, spray quality, atomization efficiency, and overall combustion performance. This study investigates the relationship between key structural parameters of injector components—including the needle valve assembly, nozzle orifice configuration, control chamber geometry, and electromagnetic/ piezoelectric actuation system—and their impact on injection characteristics under high-pressure common-rail conditions.

A comprehensive multi-physics approach is adopted, integrating CFD simulation, structural dynamics modeling, and high-speed spray visualization. Simulation results indicate that micro-scale variations in needle seat geometry, needle lift profile, and control chamber pressure propagation significantly influence injection rate shaping and stability. Optimization of the radial clearance between the needle and guide, along with tapered seat contour refinement, demonstrates a notable reduction in internal leakage and improved consistency of the start of injection (SOI).

Nozzle structural factors such as orifice diameter, inlet rounding radius, length-to-diameter ratio (L/D), and orifice arrangement patterns are analyzed for their influence on cavitation intensity and spray breakup behavior. Enhanced orifice inlet rounding and optimized sac volume effectively mitigate undesired cavitation collapse, resulting in more uniform spray dispersion and reduced droplet SMD (Sauter Mean Diameter). Multi-hole and asymmetric orifice layouts are further shown to improve air–fuel mixing in modern combustion chambers.

Experimental injection tests under varied rail pressures (80–200 MPa) validate the simulation outcomes, revealing that structural optimization yields faster needle response, improved injection rate reproducibility, and enhanced atomization at both low and high loads. Piezo-driven injectors demonstrate superior controllability compared to electromagnetic types, enabling more precise multi-stage injection strategies such as pilot, main, and post injections.

This study concludes that injector structural design must follow a holistic optimization principle, balancing hydraulic dynamics, mechanical reliability, thermal stability, and manufacturability. The results provide theoretical and practical guidance for developing next-generation high-efficiency, low-emission fuel injection systems.