Main And Sub Unit's Eev Control - LG ARUV Series Service Manual

Function
(2) (2) The sequence of compressor operation for 2 unit system
INV C1
Main
1) Stage increasing situation
Inv C2 C1
Inv C3 C1
2) Stage decreasing situation
Full C2 C1
Full C3 C1

1.3 Main and sub unit's EEV control

(1) Main EEV control
Main EEV operates with fuzzy control rules to keep the degree of super Heat(Superheat) (about 3°C)at
the evaporator outlet stable during heating mode
The degree of Superheat = Tsuction - Tevaporation
Tsuction : temperature at suction pipe sensor(°C)
Tevaporation : evaporation temperature equivalent to low pressure(°C)
(2) Sub EEV control
Sub EEV operates according to the opening of main EEV, otherwise the opening range is limited by the
open degree of the main EEV
- Limited conditions : liquid back control, discharge temperature control etc.
(3) Subcooling EEV control(about 15°C)
Subcooling EEV works with fuzzy rules to keep the degree of Subcool at the outlet of subcooler during
cooling mode
The degree of Subcool = Tcondensation - Tliquid
Tliquid : temperature at outlet of subcooler(°C)
Tcondensation : condensation temperature equivalent to high pressure(°C)
(4) Avoiding excessive high discharge temperature : when main EEV opens some given opening (R22 :
1000pls, R410A : 800 pls) and discharge temperature is above 85°C in heating operation, subcooling
EEV may control the "subcooling out temperature-evaporating temperature" to be some given difference.
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Only for training and service purposes
C2 C3
SUB1
C3(full)
C2(full)
C3
C2
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