EXPANSION VALVE
EXPANSION VALVE
SM2565457
id071100002000
Purpose
• The expansion valve atomizes liquid refrigerant to facilitate cooling of the evaporator.
Function
• The expansion valve reduces the pressure of liquid refrigerant rapidly to facilitate vaporization of the atomized refrigerant at the evaporator, and adjusts the refrigerant amount sent into the evaporator.
Structure/Construction
• The expansion valve consists of the following parts:
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― Diaphragm― Temperature sensor― Shaft― Expansion valve body― Ball valve― Spring
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Operation
• Adjustment of the refrigerant amount supplied to the evaporator is performed by the ball valve opening angle in the 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 evaporator under diaphragm― Spring force (Fs) pushing up ball valve
• If the refrigerant gas temperature from the evaporator increases, the 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 refrigerant gas temperature from the evaporator decreases, the 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.