Electronic Expansion Valve Pi Control - Daikin RQYQ140-180PY1 Service Manual

SiBE341001

2.5.4 Electronic Expansion Valve PI Control

Main electronic expansion valve EVM control
When the outdoor unit heat exchanging is performed via the evaporator (20SA is set to ON),
this function is used to exert PI control on the electronic expansion valve (Y1E) so that the
evaporator outlet superheated degree (SH) will become constant.
SH = Tg - Te
Subcooling electronic expansion valve EVT control
In order to make the maximum use of the subcooling heat exchanger, this function is used to
exert PI control on the electronic expansion valve (Y3E) so that the evaporator-side gas pipe
superheated degree (SH) will become constant.
SH = Tsh - Te
Refrigerant charge electronic expansion valve EVJ control
While in automatic refrigerant charge mode or additional refrigerant charge mode, this function
is used to exert PI control on the opening degree of the electronic expansion valve (Y2E) in
response to outdoor temperature and close the valve after the completion of refrigerant charge.
For normal operation, this electronic expansion valve is set to "41 pls".
2.5.5 Step Control of Outdoor Unit Fans
[Step control of fans]
Used to control the revolutions of outdoor unit fans in the steps listed in table below, according to condition changes.
STEP No.
1
2
3
4
5
6
7
8
* Figures listed above are all those controlled while in standard mode, which vary when the system is set to high static
pressure or capacity precedence mode.
[Control at a low outdoor temperature during cooling]
Secure the liquid pressure and circulating rate in the indoor unit through high pressure control with the outdoor fan when
the outdoor temperature is low during cooling. Control the fan with the target Tc (high pressure equivalent saturation
temperature) = 34°C
Function
RQYQ140PY1
RQEQ140PY1
285
315
360
450
570
710
830
Cooling: 951
Heating: 941
SH: Evaporator outlet superheated degree
(°C)
Tg : Suction pipe temperature (°C) detected
by the heat exchanger gas pipe
thermistor R4T.
Te : Low pressure equivalent saturation
temperature (°C)
SH: Outlet superheated degree of evaporator
(°C)
Tsh: Suction pipe temperature (°C) detected
by the subcooling heat exchanger outlet
thermistor R7T
Te: Low pressure equivalent saturation
temperature (°C)
Fan revolutions (rpm)
RQYQ180PY1
RQEQ180PY1
285
315
360
450
570
710
855
1100
Detailed Control Functions
RQEQ212PY1
285
315
360
450
570
710
855
1100
44