48
Extraction
For extraction the motor operates in an extraction pattern which is always
the same with regard to motor speed. The pattern is as follows:
1. A brief, fast extraction, which removes most of the water from the wash
load.
2. A brief reversed drum action, to allow optimum distribution of the load.
3. A distribution period with imbalance sensing – 20 seconds.
4. Extraction at 550 rpm – 30 seconds.
5. Extraction at 700 rpm – 2 minutes.
6. Extraction at 1020 rpm – remaining time out of the program's total
extraction time.
The different extraction cycles in the different programs are achieved by
varying the time that the motor will follow this extraction pattern.
Imbalance sensing
At the start of every extraction sequence, the system monitors variations in
the motor torque while the drum is operating at distribution speed. If these
variations are too great, it indicates that the load is unevenly distributed in
the drum. At this point extraction is halted, the motor speed is reduced to
wash speed and a fresh attempt to begin extraction starts. This procedure
will be repeated up to three times per extraction. After the third time the
system will decide whether the imbalance is "great" or "small".
•
If the imbalance is "great", the extraction stage of the program will end
without extraciton having taken place.
•
If the imbalance is "small", extraction will take place, but at a reduced
speed.
Fig.
71
Mechanical and electrical design
100
300
500
400
200
1000
800
600
400
200
0
0
1
2
3
4
5
6
rpm
71
3355
seconds
Imbalance check