CABIN
B2050, B2350, B2650, B3150, WSM
10-M8
[4] AIR CONDITIONER UNIT
The air conditioner unit consists of evaporator (2),
expansion valve (3), heater core (4), blower (1). etc..
9Y1210982CAM0010US0
Expansion Valve
The expansion valve regulates the amount of liquid
refrigerant that passes through the valve. Also, this
atomizes the refrigerant for delivery to the evaporator to
enable the refrigerant to vaporize readily in the
evaporator.
The expansion valve is made up of a diaphragm,
temperature sensing rod, and needle valve (ball) etc.
and refrigerant gas is enclosed in the diaphragm.The
evaporator outlet pressure is applied to the outside of the
diaphragm.
In the diagram to the left, the temperature sensing
rod senses refrigerant temperature after passing through
the evaporator. The temperature here is communicated
to the refrigerant gas inside the diaphragm chamber via
the temperature sensing rod.
Therefore, the gas pressure is changed by the
temperature which moves the temperature sensing rod
that is in direct contact with the diaphragm regulating the
opening of the needle valve.
When the temperature of the evaporator outlet is low
(when cooling load is small)
The gas pressure in the diaphragm chamber drops
and volume decreases causing the temperature sensing
rod to move to the right in the diagram and constricting
the needle valve.
When the temperature of the evaporator outlet is
high (when cooling load is large)
The gas pressure in the diaphragm chamber
increases, increasing volume causing the temperature
sensing rod to move to the left in the diagram, opening
up the needle valve and supplying increased amount of
refrigerant to the evaporator.
9Y1210982CAM0013US0
(1) Blower
(2) Evaporator
(3) Expansion Valve
(4) Heater Core
(1) Evaporator
(2) Temperature Sensing Rod
(3) Diaphragm
(4) Body
(5) Spring
(6) Needle Valve
(7) Expansion Valve
(8) AC Unit
(A) To compressor
(low pressure)
(B) From receiver
(high pressure)
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