Diesel Injector Deposits Potential in Future Fueling Systems 2006-01-3359
Diesel engines will require new hardware to meet future emissions levels required by upcoming legislation. One of the key enablers towards meeting such legislation is the use of better fuel injection equipment (FIE). However, these systems can produce temperatures at the injector tips that are considerably higher than those seen today. This environment can exacerbate the rate of deposit formation or generate new types of deposits at and around the injector tip.
Previous and ongoing investigations continue to further our understanding of this phenomenon using a modern passenger car diesel engine, various commercial 10 ppm S diesel fuels, a severe test cycle and injector nozzles representative of those likely to be in use in EURO V engines. The engine tests show good repeatability with clear and treated fuels. This supports the validity of the data generated. The test protocol used has recently been released to the industry.
Most testing has been carried out with metal contaminated fuel. The data show that the level of deposit is fuel dependent for both base and additive treated fuel.
Use of higher metal contamination produces increased levels of the same kind of deposits seen with lower metal levels. The type and composition of the deposit appears to be independent from the level of metal added to fuel, which offers potential for reduced testing times without changing the phenomenon.
The majority of the testing has been carried out with a soluble metal salt specifically developed to mimic the typical metal contamination seen in the field. To confirm the use of this salt as a valid test material, parallel testing has been conducted using fuel naturally contaminated with metal.
Commercial detergents, at a variety of treat rates, have been assessed to understand their impact. Detergent levels that have historically been used in the field are now proving less effective, suggesting that the deposits are more challenging than those seen in current and previous FIE technologies. Some results with novel detergent chemistries are also presented.