Philips HD 8753, Service Manual

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INTELIA 04 OPERATING LOGIC
Saeco International Group Rev. 01 / September 2011 Page / 08
4.5. Coffee grinder
2
3
4
5
6
1
4.6. Low bean level detection, dose quantity adjustment, coffee grinder
blocked
t1
V
t2
t3
t4
t
Without beans n=100%
With beans n=100%
Without beans n=50%
With beans n=50%
The coffee grinder is driven by a direct current motor (1) using a worm screw helicoidal wheel
transmission (2).
The worm screw (2) drives a plastic gear wheel (3), which turns the lower grinder (4) and the
increment pin (5)
There are two magnets (6) in the gear wheel; at every rotation these induce two pulses to a Hall
sensor, which in turn transmits them to the electronic system.
No coffee
A low coffee bean level is detected by the Hall sensor,
after variations in the pulse frequency (with or without
coffee).
If there are no coffee beans (operation while empty),
the number of rotations – and therefore the number of
pulses – will be greater.
t1 = no coffee indication
If, however, there are coffee beans, the number of
rotations will be lower due to the force created by the
grinding.
t2 = no indication
t3 and t4 = this measurement is performed at the end
of each grinding process
Dose quantity adjustment
The dose quantity is adjusted in accordance with the
pulses detected (number of rotations proportional to the
selected fl avor – mild, medium or strong).
Coffee grinder blockage
If the coffee grinder becomes blocked for any reason,
pulses will no longer be transmitted to the electronic
system and the grinder will come to a stop.
05