| 摘要 |
In a thermostatic expansion valve having a thermo bulb, a valve opening degree is defined by the force difference between a first force at one side surface of a diaphragm and a second force at the other side surface thereof. The former force is the sum of the pressure of a refrigerant, sensed at the downstream side of a valve seat and applied on one side surface by an auxiliary pressure applying capillary tube, and the biasing force, applied on one side surface by a valve body spring. The latter force is the sum of the pressure of an actuator vapor, contained in a thermal bulb and applied on the other side surface of the diaphragm, and the pressure of the refrigerant, sensed at the upstream side of the valve seat in a refrigerant pathway of a valve housing and applied on the other side surface by way of a force transmitting member. Parameters for the former and latter forces are so selected that the latter becomes bigger than the former so that a refrigerant can be supplied at a flow rate over a predetermined value to an evaporator, even when the value of a superheat degree is lower than the value of a predetermined set static superheat degree in a case where the difference in the pressure of the refrigerant exerted on the valve body between a first pressure sensed at the upstream side of the valve seat and a second pressure sensed at the downstream side thereof is larger than a pressure difference which is used as a base for setting the static superheat of the thermostatic expansion valve.
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