PROBLEM TO BE SOLVED: To reduce needle displacement from full-close to full-open.;SOLUTION: An ejector includes: a cylindrical nozzle 151 depressurizing and injecting fluid to be depressurized; housings 152, 153 formed with a fluid suction port 152b sucking fluid to be sucked by a flow of injection fluid injected from the nozzle 151 and pressurization sections 152e, 153a raising pressure by mixing the injection fluid and the fluid sucked from the fluid suction port 152b; and a needle 154 as a needle member extending coaxially with the nozzle 151 and displaced in the axial direction of the nozzle 151. The end of the needle 154 in the injection direction of the injection fluid is formed with a tapered end having a shape tapered toward the injection direction, and at least a part of the tapered end forms a gradually changing tapered portion 154b with a cone angle gradually changed to be increased toward the injection direction. The needle 154 changes the opening area of the nozzle 151 by at least the gradually changing tapered portion 154b.;COPYRIGHT: (C)2010,JPO&INPIT
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