Pressure Oscillations as a Factor Affecting the Management of the Fuel Injection Process in the Combustion Chamber of a Diesel Engine

Abstract

Fuel injection causes considerable oscillations of fuel pressure at the injector inlet. One of the reasons is hydraulic impact originating when closing the injector nozzle needle. Evidently, these oscillations influence the fuel supply process in case of multiple injections: the previous injections would influence on the following ones. The influence of the interval between the impulses of a double injection on the injection rate value of the second portion was investigated. The superposition of waves in case of multiple injection may result both in amplification and damping of oscillations process. It is shown that with multiple injection, the controllability of fuel supply deteriorates, therefore, either a special design study of the fuel system for multiple injection or the introduction of additional electronic correction of control pulses by the diesel control system is required. On the other hand, it is shown how multiple injection can produce a stepwise injection characteristic, which can serve as a means of reducing nitrogen oxides and noise.