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Issue No. :- TC-77040725Dated :- 8th July, 2004 TECHNICAL BULLETIN
Product : Multi-V, Multi, Inverter Frequency : 50/60 HzCategory : Information/Technology
Fig 1 : Construction of EEV
Construction :It consists of pulse motor which is controlled by microprocessor.•A needle for opening and closing the the orifice space.•A spring for backing force for needle.•Flow in and flow out connected pipes. (fig1)
Principle : The amount of refrigerant flow is varied on the basis of load on the evaporator. In other words it control the mass flow rate on the basis of temperature at different locations.
Title: Electronic Expansion Valve (Linear expansion valve)
Details : Also known as linear expansion valve. Definition : It is very dynamic expansion device used for bringing down the condensing pressure to evaporating pressure and also control the mass flow rate of the refrigerant flowing in the system. It is very precise and accurate device which can react instantaneously to any kind variation or abnormality occurs during air-conditioners working.
Motor
Needle
Orifice
Flow in
Flow out
Shaft
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Issue No. :- TC-77040725Dated :- 8th July, 2004 TECHNICAL BULLETIN
Pulsemotor
Working : Temperature sensors are provided at different locations in evaporators and condenser such as inlet, outlet & middle.All this data is gathered and is send to the microprocessor a feedback loop. It calculates the optimum mass flow of refrigerant, depending on that a signal is sent to regulate the valve’s opening and closing (Fig 2).
Benefits : Wide capacity range.•High cool down capacity.•Quick response.•Less energy consumption.•Bi-flow capabilities.•Accurate and precise control.•High resolution.
Fig 2 : Working of LEV
Fig 3 : Actual shape of LEV
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Issue No. :- TC-77040725Dated :- 8th July, 2004 TECHNICAL BULLETIN
Usage : Multi Split systems, Variable refrigerant flow air Conditioning systems,Multi-V, Multi-V plus, Multi-V sync, DC inverter and MPS variable and MPS inverter systems.
Wiring connections : There are 5 wires of different colors to control the excitation of the motor. Depending on the the phase active and the time of pulse it decides the angle of motor to rotate. Below is the graph showing the phase excitation.
Drivingcircuit
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Issue No. :- TC-77040725Dated :- 8th July, 2004 TECHNICAL BULLETIN
Flow characteristics : In the graph below shows the plot between flow and pulse in different settings and modes of working. The graph is nearly linear.
Output pulse sequence-In valve close state 1→2→3→4→5→6→7→8→1-In valve open state 8→7→6→5→4→3→2→1→8
1. If the LEV open angle is not change, all of the output phase will be OFF.2. If the output phase is different or continuously in the ON state, motor will not start smoothly and start
vibrating
Pulse signal output value and valve operation
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Issue No. :- TC-77040725Dated :- 8th July, 2004 TECHNICAL BULLETIN
-20
-15
-10
-5
0
5
10
15
20
0 100 200 300 400 500 600 700 800 900
Time(sec)
Supe
rhea
t(℃)
Starting Control
Regular Control
TargetSuperheat
Comparison : Below is the comparison between EEV and TXV.
Flow control : Super heat characteristic control
Control flow by microprocessor
Very high
Best
Best
Best
Best
EEV (LEV)
Control flow by DiaphragmWorking method
HighCost
NormalMultiple unit attachment
GoodSystem efficiency
BestDevice Reliability
GoodSystem Performance
TXV
☞ General working is show superheat values may be different for different refrigerants and models.