| 摘要 |
PROBLEM TO BE SOLVED: To provide an expansion device capable of assuring an appropriate evaporation amount at an evaporator, in a system in which an external heat exchanger is used as the evaporator. SOLUTION: The expansion device 10 includes a small-aperture control valve 12 that functions as a normal temperature type expansion valve, a power element 21 which controls the small-aperture control valve 12 by detecting the degree of the overheating of a coolant at the outlet of an evaporator, a large-aperture control valve 13 which is controlled by the power element 21 and has a flow-rate characteristic which is opposite to the small-aperture control calve 12, and an electromagnetic valve 22 which has performed switching between control state and non-control state of the large-aperture control valve 13. Upon electrification to the electromagnetic valve 22, control by the large-aperture control valve 13 having a large aperture is prioritized. When the degree of overheating grows, the large-aperture control valve 13 is stopped down to increase the amount of evaporation at the evaporator for autonomous control pursuing a constant degree of overheating, and thus an appropriate amount of evaporation at the evaporator is secured. COPYRIGHT: (C)2012,JPO&INPIT |
