| 摘要 |
A self-regulated Joule-Thomson expansion valve and cryostat useful in miniaturized cryogenic gas liquefaction systems include a substantially frustroconical valve member having a base portion supported at the end of first means such as an elongate shaft and a tapered valve seat generally complementary to the valve member and supported circumferentially adjacent a lengthwise portion of the valve member by second means such as a sheath slidably received upon the shaft. The valve member and valve seat taper down toward a free extremity of the valve member, whereby opposing peripheral surfaces of the valve member and valve seat define a converging annular passageway terminating at an annular expansion opening. The first means is constructed with an effective coefficient of thermal expansion lower than that of the second means so that the valve seat moves axially toward and away from the valve member by differential contraction and expansion between the first and second means in response respectively to decreases and increases in the temperature of expanded coolant gas, thus regulating the effective flow area of the converging annular passageway. The valve member may advantageously include labyrinth flow spoilers in the form of circumferential grooves which serve additionally as catchment reservoirs for capturing contaminants contained in the coolant gas, thus rendering the expansion valve highly resistant to blockage by such contaminants. Means may also be provided for adjusting the relative axial positions of the valve member and valve seat in order to calibrate the effective flow area of the converging passageway.
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