Patent ID: 8329354

Claim:
An ejector, comprising: a body; a nozzle to which a first fluid is supplied and having a trunk portion and a front end portion; a needle which is coaxially arranged with the nozzle and having a base portion and a tip portion; a diffuser which sucks a second fluid by a negative pressure generated by the first fluid ejected from the nozzle and discharges the second fluid and the first fluid by mixing the second fluid with the first fluid; a first diaphragm and a second diaphragm whose periphery portions are fixed to the body, while being fixed to the nozzle on one side and the other side apart from the one side, respectively, and enabling the nozzle to move in an axial direction against the needle; a third diaphragm whose periphery portion is fixed to the body on the one side which is further end side of the first diaphragm, while being fixed to the nozzle on the one side and enabling the nozzle to move in the axial direction against the needle; a first fluid chamber which is surrounded at least by the first diaphragm, the second diaphragm and the body and to be supplied with the first fluid; a second fluid chamber which is surrounded at least by the second diaphragm and the body and to be supplied with the second fluid; a third fluid chamber which is surrounded at least by the third diaphragm and the body and to be supplied with a third fluid; a fourth fluid chamber which is surrounded at least by the first diaphragm, the third diaphragm and the body and communicated with the atmosphere; a valve which is formed in the first fluid chamber by disposing a valving element on one of the nozzle and the needle and a valve seat on the other one of the nozzle and the needle, wherein the valving element seats on or leaves from the valve seat by a movement of the nozzle; and a back pressure chamber which is disposed between the trunk portion of the nozzle and the base portion of the needle and is communicated with the first fluid chamber through the valve, wherein the first diaphragm and the second diaphragm have the same effective area; and wherein an effective area of the third diaphragm is different from the effective areas of the first diaphragm and the second diaphragm.