Purging Mechanism - Brother MFC4820C Service Manual

4.2.3.3

Purging mechanism

[ 1 ] Overview of the purge drive
The purge mechanism is driven by the purge motor (stepping motor) in the purge unit, and restores
the machine's ability to jet out ink by sucking up ink deteriorated in quality from the head nozzles.
The purge motor also pushes up the vent rods in the purge unit and, as described in Section 4.2.3.1,
[ 2 ], (3), expels the air trapped in the print head unit manifold.
The main components of the purge mechanism include the purge motor, drive gears, planet gears,
pump switching unit, purge cam (cam gear 90), head wiper, head cap unit (see Section 4.2.3.2),
vent rod unit, purge cam HP switch and the tube pump.
When the purge motor rotates counterclockwise (as seen from the motor output shaft), the
rotational torque is transmitted to the purge cam (cam gear 90) via the planet gear, as shown in the
figure below. The rotation of the purge cam in turn drives the head wiper, head cap unit and vent
rod unit.
Purge unit
Purge motor
Planet gear
Purge cam
HP switch
Purge cam
(Cam gear 90)
Pump switching unit
Head cap unit
Head wiper
Head wiper
Head cap unit
Purge cam (Cam gear 90)
Purge cam HP switch
4 - 2 2
Vent rod unit
Vent rod unit