Patent ID: 8323852

Claim:
An ejector for ejecting fluid, comprising: a body; a nozzle having a trunk portion and a front-end part and ejecting a first fluid supplied thereto; a needle having a base part and a tip portion and being placed coaxially with the nozzle; a diffuser drawing in a second fluid using negative pressure caused by ejection of the first fluid from the nozzle, mixing the second fluid with the first fluid ejected from the nozzle, and discharging the mixed fluid; first and second diaphragms each having an outer portion being fixed to the body at their peripheral part and an inner portion, the first and second diaphragms being fixed to the nozzle at positions separate from each other in an axial direction of the nozzle, and allowing the nozzle to shift in the axial direction with respect to the needle; and a first fluid chamber being surrounded at least by the first and second diaphragms, the body, the nozzle and the needle and being supplied with the first fluid to be supplied to the nozzle, wherein: a valve in which a valve body contacts and separates from a valve seat according to the shifting action of the nozzle is formed by providing either the nozzle or the needle with the valve body and providing the other with the valve seat in the first fluid chamber, and a back pressure chamber connecting to the first fluid chamber via the valve is provided between the trunk portion of the nozzle and the base part of the needle.