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F U E L M A N A G E M E N T S Y S T E M
Main Injection Step 1
• Pulse width controlled current energizes the
open coil, magnetic force moves the spool
valve to the open position.
• High pressure oil flows past the spool valve
into the intensifier piston chamber.
• Oil pressure overcomes the intensifier piston
spring force and the intensifier starts to
move.
• Fuel inlet check ball seats due to an
increase of fuel pressure under the plunger.
• Fuel pressure starts to build once the
plunger passes the fuel spill port of the
barrel.
• Force on the nozzle needle begins to build.
Main Injection Step 2
• The pulse width controlled current is shut off
after 800 µsec (micro second or millionth of
a second), but the spool remains in the open
position.
• High pressure oil from the rail continues to
flow past the spool valve.
• The intensifier piston and plunger continue
to move and pressure increases in the
barrel.
• When fuel pressure rises above the VOP
(Valve Opening Pressure) of about 3100 psi,
the nozzle needle lifts off of it's seat and
injection begins.
46
PINTLE CLOSED
PINTLE OPEN
SPOOL VALVE OPEN
INTENSIFIER PISTON
MOVING DOWN
98
SPOOL VALVE OPEN
INTENSIFIER PISTON
MOVING DOWN
99
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