Patent ID: 6858340

Claim:
A variable flow-rate ejector comprising: a body; a nozzle having a head and a base, each of which has an opening, wherein the nozzle ejects a first fluid from the opening at the head; a diffuser whose central axis coincides with that of the nozzle, wherein a second fluid is drawn into the diffuser due to a negative pressure produced around the first fluid ejected by the nozzle, and the second fluid is entrained with the first fluid and the mixed fluid is output; a needle inserted into the nozzle, wherein the central axis of the needle coincides with that of the nozzle and the needle is movable along the central axis; a first diaphragm whose peripheral portion is supported by the body and which is provided for closing the opening at the base of the nozzle, wherein the first diaphragm is attached to the needle and is movable along the central axis of the needle; a second diaphragm whose peripheral portion is supported by the body and which is arranged at a distance from the first diaphragm, wherein the second diaphragm is attached to the needle and is movable along the central axis of the needle; a third-fluid chamber formed by the first diaphragm, the second diaphragm, and the body and arranged adjacent to the inside of the nozzle via the first diaphragm, wherein the first fluid is supplied to the nozzle and a third fluid is supplied to the third-fluid chamber; and a fourth-fluid chamber formed by the second diaphragm and the body and arranged adjacent to the third-fluid chamber via the second diaphragm, wherein a fourth fluid is supplied to the fourth-fluid chamber, wherein: an area of an opening around the needle in the opening at the head of the nozzle is changed by displacement of the needle along the central axis according to movement of the first and second diaphragms which move in accordance with the pressure produced by the first fluid, the third fluid, and the fourth fluid.