Linear Expansion Valve; Operation Summary Of The Linear Expansion Valve; Output Pulse Signal And The Valve Operation; Linear Expansion Valve Operation - Mitsubishi Electric MXZ-8A140VA Technical & Service Manual

Linear expansion valve

(1) Operation summary of the linear expansion valve

• Linear expansion valve open/close through stepping motor after receiving the pulse signal from the branch box controller
board.
• Valve position can be changed in proportion to the number of pulse signal.
<Connection between the branch box controller board and the linear expansion valve>
LEV
3
2
M
5
1
4
6
<Output pulse signal and the valve operation>
Output
(Phase)
1 2 3
[1
ON ON OFF
[2
OFF ON ON
[3
OFF OFF OFF
[4
OFF OFF OFF

(2) Linear expansion valve operation

Close
A
B
Extra tightening (about 32 pulse)
(LEV) in Branch box
Output
4 5 6 7 8
OFF OFF OFF OFF ON
ON OFF OFF OFF OFF
ON ON ON OFF OFF
OFF ON ON ON
OFF
C
Open
500 pulse
Opening a valve
all the way
Pulse number
Red
Brown
[4
Blue
[3
Orange
Yellow
[2
[1 White
Connector LEV-A
LEV-B
LEV-C
LEV-D
LEV-E
Opening a valve : 8 7
Closing a valve : 1 2
The output pulse shifts in above order.
• When linear expansion valve operation stops, all output phase
become OFF.
• When the switch is turned on, 700 pulse closing valve signal will be
sent till it goes to point in order to define the valve position.
A
(The pulse signal is being sent for about 20 seconds.)
• When the valve moves smoothly, there is no sound or vibration
occurring from the linear expansion valve : however, when the pulse
number moves from to
B
be heard.
No sound is heard when the pulse number moves from
case coil is burnt out or motor is locked by open-phase.
• Sound can be detected by placing the ear against the screw driver
handle while putting the screw driver to the linear expansion valve.
57
branch box controller board
DC12V
1
Drive circuit
2
[4
3
[3
4
[2
5
[1
6
6 5 4 3 2 1
3 4 5 6 7 8
or when the valve is locked, sound can
A
8
1
to in
B A