| 摘要 |
PROBLEM TO BE SOLVED: To limit a maximum flow rate to a predetermined value irrespective of a combination of diameters of an orifice and a valve body. SOLUTION: A constriction section 22 is provided downstream an orifice 20 in succession to a valve seat 7, and a constriction of an expansion valve is adapted to be a two stage constriction composed of a variable first constriction comprising a valve seat 7 and a valve body 8 and a fixed second constriction comprising the constriction section 22. As a result, a maximum f low rate can be limited to a predetermined value irrespective of a diameter A of the valve seat 7 located more upstream than the second constriction and its configuration and of the valve body 8 and its configuration, so that a combination of the diameter of the valve seat 7 and the diameter of the valve body 8 can be altered without taking the maximum flow rate changing following the alteration of the combination into consideration.
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