Nozzle holder combination position / task / design / function

P07.13-0265-76

Design

50/2 Nozzle needle

50/3 Nozzle body

51/1 Intermediate disk

51/2 Thrust pin

51/3 Nozzle tensioning nut

51/4a Compression spring stage 1

51/4b Compression spring stage 2

51/5 Retaining body

51/7 Shim

51/9 Stop sleeve

51/10 Guide bush

a Initial stroke

b Full stroke

C Leak fuel (return)

D High pressure (feed)

NW Cam angle in °

NH Needle lift in mm

Advantages

Use of two-spring nozzle hoders greatly reduces the combustion noises, particularly in the idle speed and part throttle range. The level of pollutant emissions is reduced as a result of the combustion chamber design.

Task

 Combining injection nozzle and nozzle holder

 Specific preinjection for reducing combustion noises

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Function

1st stage

Two compression springs (51/4) are positioned one after the other in the two-spring nozzle holder. At first, only the compression spring (51/4a) acts on the nozzle needle (50/2) through the thrust pin (51/2) and in this way determines the initial opening pressure. At a cam angle of about 6° the injection pressure raises the nozzle needle. The compression spring (51/4b) is supported on the stop sleeve (51/9) which limits the initial stroke (a) to about 0.04 mm. Only a small part of the fuel quantity injected reaches the combustion chamber.

2nd stage

Once the pressure in the nozzle holder rises further, the stop sleeve is lifted off at a cam angle of 8° and both compression springs are acting on the nozzle needle. The nozzle needle (50/2) is opened to the full stroke (b) of 0.26 mm and the main quantity is injected.

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