User Manual

Actuation oil now flows past the open spool and to the top of the intensifier piston. The downward movement of
the piston and plunger (10) pressurizes the fuel in the plunger cavity to the nozzle tip (20) . Pilot injection
begins when the injection pressure increases in order to overcome the force of the nozzle spring (15) which lifts
the nozzle check (19) .
Pilot injection will continue if the following conditions exist:
• The solenoid is energized.
• The spool remains open.
• There is no actuation pressure on top of the check piston.
Injection Delay
Cross section of injection delay
(1) Solenoid
(2) Armature spring
(3) Armature
(4) Seated pin
(5) Spool spring
(6) Spool valve
(8) Intensifier piston
(10) Plunger
(16) Check piston
(19) Nozzle check
Injection delay begins when the control current to
the solenoid (1) stops and the solenoid is de-
energized. The armature (3) is held in the up
position by a magnetic field. When the magnetic
field is de-energized, the armature spring (2)
pushes the armature and the seated pin (4)
downward. The seated pin closes the lower seat
and the seated pin opens the upper seat. This
allows the actuation pressure to flow to the top of
the check piston (16) . The hydraulic force on the
check piston quickly overcomes the injection
pressure and the nozzle check (19) closes.
Injection stops at this point
.