EXPANSION VALVE

id071100002000

Front

Purpose/Function

•  The front expansion valve rapidly depressurizes the liquid refrigerant to form it into a mist.

•  The front expansion valve adjusts the liquid refrigerant flow volume sent to the front evaporator.

Structure/Construction

•  The front expansion valve consists of the following parts.

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Operation

•  The front expansion valve adjusts the liquid refrigerant flow volume using the opening angle of the ball valve in the front expansion valve.

•  The opening angle adjustment is performed according to the balance of the following forces:

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―  Refrigerant pressure (Pd) in diaphragm

―  Refrigerant gas pressure (PI) of front evaporator under diaphragm

―  Spring force (Fs) pushing up ball valve

•  If the gaseous refrigerant temperature from the front evaporator increases, the front expansion valve increases the amount of refrigerant according to the following operations:

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1.  The temperature of the temperature sensor tightly sealed against the diaphragm increases.

2.  The refrigerant in the diaphragm warms and the Pd increases.

3.  If this Pd increases more than PI + Fs, the diaphragm is pressed down.

4.  The shaft installed to the temperature sensor end presses down the ball valve.

5.  The amount of refrigerant is increased.

•  If the gaseous refrigerant temperature from the front evaporator decreases, the front expansion valve decreases the amount of refrigerant flow according to the following operation:

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1.  The temperature of the temperature sensor tightly sealed against the diaphragm decreases.

2.  The refrigerant temperature in the diaphragm decreases and the Pd decreases.

3.  The Pd decreases less than PI + Fs.

4.  The ball valve installed to the temperature sensor end is pressed up.

5.  The amount of refrigerant is decreased.

Fail-safe

•  Not applicable

Rear

Purpose/Function

•  The rear expansion valve rapidly depressurizes the liquid refrigerant to form it into a mist.

•  The rear expansion valve adjusts the liquid refrigerant flow volume sent to the rear evaporator.

Structure/Construction

•  The rear expansion valve consists of the following parts.

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Operation

•  The rear expansion valve adjusts the liquid refrigerant flow volume using the opening angle of the ball valve in the rear expansion valve.

•  The opening angle adjustment is performed according to the balance of the following forces:

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―  Refrigerant pressure (Pd) in diaphragm

―  Refrigerant gas pressure (PI) of rear evaporator under diaphragm

―  Spring force (Fs) pushing up ball valve

•  If the gaseous refrigerant temperature from the rear evaporator increases, the rear expansion valve increases the amount of refrigerant according to the following operations:

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1.  The temperature of the temperature sensor tightly sealed against the diaphragm increases.

2.  The refrigerant in the diaphragm warms and the Pd increases.

3.  If this Pd increases more than PI + Fs, the diaphragm is pressed down.

4.  The shaft installed to the temperature sensor end presses down the ball valve.

5.  The amount of refrigerant is increased.

•  If the gaseous refrigerant temperature from the rear evaporator decreases, the rear expansion valve decreases the amount of refrigerant flow according to the following operation:

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1.  The temperature of the temperature sensor tightly sealed against the diaphragm decreases.

2.  The refrigerant temperature in the diaphragm decreases and the Pd decreases.

3.  The Pd decreases less than PI + Fs.

4.  The ball valve installed to the temperature sensor end is pressed up.

5.  The amount of refrigerant is decreased.

Fail-safe

•  Not applicable