Hybrid hydraulic electronic unit injector

摘要

A hybrid hydraulic electronic unit injector (HEUI) assembly, having some characteristics of an accumulator-type assembly and some characteristics of a non-accumulator type assembly, is produced by designing the volume (VACC) of the passageway downstream of an existing blowback prevention check valve of the assembly to be between 1.0 and 10.0 times the maximum quantity QMAX of fuel injected during an injection event. The resulting hybrid assembly 1) exhibits a rising injection rate during at least the initial stages of the injection event and therefore exhibits benefits generally associated with non-accumulator type HEUI assemblies, and 2) exhibits a falling rate injection during at least the final stages of the injection event and therefore exhibits benefits generally associated with accumulator-type HEUI assemblies. The percentage of the injection event taking place under a falling rate increases generally proportionally with the ratio VACC/QMAX.