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Fuel ManageMent SySteM
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Valve Piston
• The valve piston is utilized for one main purpose:
1) It transfers the up and down movement from
the Piezo Actuator to the Valve Mushroom.
Valve Mushroom, Return Spring,
and Control Piston
• The valve mushroom is a hydraulic check valve that allows
high pressure fuel to bleed off into the fuel return passage
directly above it whenever the Piezo Actuator is energized.
• The valve mushroom is held in a closed (sealed)
position whenever the Piezo Actuator is not energized
via high pressure fuel and spring pressure.
• The control piston utilizes its large surface area
for a downward force to overcome the pressure
exerted by the smaller surface area of the nozzle
needle in the high pressure chamber to keep
the nozzle needle in a closed position.
Nozzle Needle
• The nozzle needle is an inwardly opening type which
lifts off its seat every time the pressure in the high
pressure chamber exceeds the pressure in the control
piston chamber, i.e. when the piezo is actuated.
• The needle control spring is used to hold
the nozzle needle in a closed position.
• Fuel is atomized at high pressure through
the nozzle tips six spray holes.
Valve Piston
Valve Mushroom
Valve Mushroom
High Pressure
Fuel
Needle Control
Spring
Control Piston
Valve Mushroom
Return Spring
Fuel Return Passage
Control Piston
Nozzle Needle
High Pressure
Chamber
Spray Holes (6 holes)
Control Piston
Chamber
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