Patent ID: 8523091

Claim:
An ejector comprising: a nozzle configured to decompress and expand a fluid and to jet the fluid from a fluid jet port; a needle disposed inside of the fluid passage of the nozzle to extend a fluid flow direction; and a body provided with a fluid suction port from which a fluid is drawn by a high-speed jet fluid jetted from the fluid jet port, and a pressure increasing portion in which a velocity energy of a mixture fluid between the jet fluid and a suction fluid drawn from the fluid suction port is converted to a pressure energy thereof, wherein an inner peripheral surface of the nozzle defining the fluid passage includes a throat portion in which a fluid passage sectional area of the fluid passage is most reduced, a taper portion arranged downstream of the throat portion to gradually enlarge the fluid passage sectional area as toward a flow direction of the jet fluid, and an end taper portion arranged in a range from a downstream side of the taper portion to the fluid jet port to gradually enlarge the fluid passage sectional area as toward the flow direction of the jet fluid, the fluid passage, defined between an outer peripheral surface of the needle and the taper portion, includes a first expanding passage portion in which the fluid passage sectional area is gradually enlarged toward a flow direction of the jet fluid, and a second expanding passage portion arranged downstream of the first expanding passage portion to gradually enlarge the fluid passage sectional area toward the flow direction of the jet fluid, an increase degree of the fluid passage sectional area in the second expanding passage portion is larger than an increase degree of the fluid passage sectional area in the first expanding passage portion, and when an axial cross section including an axial line of the nozzle is defined as a standard cross section, an end expanding angle at an outlet side of the end taper portion on the standard cross section is smaller than an outlet expanding angle at an outlet side of the taper portion on the standard cross section.