Man L23/30DF, Project Manual

Page: 127 / 392

Fuel injection pump
The fuel pump and the roller guide are one unit,
placed over the fuel cam. A pipe supplies lubricat-
ing oil from the camshaft bearing to the roller guide.
The barrel is installed with seals on the outer cir-
cumference at various levels to avoid leakages and
to give the possibility to drain fuel from the lower
part of the barrel bore.
At the same time it also gives the possibility to add
sealing oil to minimize fuel contamination of the
lubricating oil.
The injection amount of the pump is regulated by
transversal displacement of a toothed rack in the
side of the pump housing. By means of a gear ring,
the pump plunger with the two helical millings, the
cutting-off edges, is turned whereby the length of
the pump stroke is reckoned from when the plunger
closes the inlet holes until the cutting-off edges
again uncover the holes.
A delivery valve is installed on top of the barrel. In
the delivery valve housing a second valve is instal-
led. This valve will open for oscillating high pressure
waves between the needle in the fuel injection valve
and the delivery valve on the pump, causing the
needle in the fuel valve to stay closed after the injec-
tion is finished. This will reduce formation of carbon
around the nozzle tip and save fuel.
The amount of fuel injected into each cylinder unit is
adjusted by means of the governor, which main-
tains the engine speed at the preset value by a con-
tinuous positioning of the fuel pump racks, via a
common regulating shaft and spring-loaded link-
ages for each pump.
The rack for fuel control is shaped as a piston at
one end. The piston works inside a cylinder. When
the cylinder is pressurized, the fuel rack will go to
zero and the engine will stop.
Figure 1: Fuel injection pump.
MAN Diesel & Turbo
1683324-8.1
Page 1 (1)
Fuel injection pump
B 11 02 1
L27/38S, L21/31S, L16/24S, L16/24, L21/31, L27/38
2015.11.27