Diesel distributor fuel-injection pumps VE - K-Jet.org

Axial-pistondistributorpumpsFig. 10Two-spring nozzle holder for direct-injection(DI) engines1 Nozzle-holder body, 2 Shim,3 Spring 1, 4 Pressure pin,5 Guide element, 6 Spring 2,7 Pressure pin, 8 Spring seat,9 Shim, 10 Intermediate element,11 Stop sleeve,12 Nozzle needle,13 Nozzle-retaining nut,14 Nozzle body.h 1 Initial stroke,h 2 Main stroke.123When strokes take place in excess of theinitial stroke, the stop sleeve lifts and bothsprings have an effect upon the nozzleneedle (Fig. 10).Method of operationDuring the actual injection process, thenozzle needle first of all opens an initialamount so that only a small volume offuel is injected into the combustionchamber.Along with increasing injection pressurein the nozzle holder though, the nozzleneedle opens completely and the mainquantity is injected (Fig. 11). This 2-stagerate-of-discharge curve leads to “softer”combustion and to a reduction in noise.Nozzle holders with needlemotionsensor4567891011121314ApplicationThe start-of-injection point is an importantparameter for optimum diesel-engineoperation. For instance, its evaluationpermits load and speed-dependent injectiontiming, and/or control of the exhaustgasrecirculation (EGR) rate.Fig. 11Comparison of needle-lift curvesa Standard nozzle holder (single-spring nozzleholder),b Two-spring nozzle holder.h 1 Initial stroke, h 2 Main stroke.amm0.40.20bmm0.4h 2h 1Nozzle-needle lift0.2h 252UMK1423-1Y00 1Timeh 12 msUMK1422E