Linking the Physical Manifestation and Performance Effects of Injector Nozzle Deposits in Modern Diesel Engines
Abstract:
The formation of deposits within injector nozzle holes of common-rail injection
fuel systems fitted to modern diesel cars can reduce and disrupt the flow of
fuel into the combustion chamber. This disruption in fuel flow results in
reduced or less efficient combustion and lower power output. Hence there is
sustained interest across the automotive industry in studying these deposits,
with the ultimate aim of controlling them.
In this study, we describe the use of Scanning Electron Microscopy (SEM) imaging
to characterise fuel injector hole deposits at intervals throughout an
adaptation of the CEC Direct Injection Common Rail Diesel Engine Nozzle Coking
Test, CEC F-98-08 (DW10B test)[1].
In addition, a similar adaptation of a previously published Shell vehicle test
method [2] was employed to analyse fuel
injector hole deposits from a fleet of Euro 5 vehicles. During both studies,
deposits were compared after fouling and after subsequent cleaning using a novel
fuel borne detergent.
In all cases, the use of fuel borne detergents quickly recovered >75% of power
lost during the fouling stage of the tests. SEM images showed that the removal
of deposits within the injector nozzle holes was key to the recovery of power
and that deposits on the injector nozzle exterior could be misleading in
predicting the performance of fuel injectors.