Fuel cell system

An ejector comprising:

• a first fluid chamber into which a first gas is introduced;
• a rod-shaped needle;
• a nozzle accommodating the needle inside thereof and circulating the first gas introduced into a first fluid chamber in a space with the needle and then exhausting the first gas from an exhaust port,
• a second fluid chamber provided at the top end side of the nozzle, into which second gas is introduced,
• a diffuser increasing the flow rate of the first gas exhausted from the nozzle to deliver the exhausted first gas and then aspirating the second gas introduced into the second fluid chamber according to the negative pressure of the delivered first gas to merge the second gas with the delivered first gas;
• and,
• a third fluid chamber provided at the bottom end side of the nozzle, into which third gas is introduced, wherein
• the top end of the needle and the exhaust port of the nozzle move relatively by using the pressure of the third gas introduced into the third fluid chamber to change the opening area of the exhaust port thereby to adjust the flow of the first gas to be exhausted from the nozzle,
• the first fluid chamber is provided between the second fluid chamber and the third fluid chamber,
• the first fluid chamber and the second fluid chamber are separated by a first diaphragm,
• the first fluid chamber and the third fluid chamber are separated by a second diaphragm,
• the needle and the nozzle moves to approach each other by the pressure of the third gas introduced into the third fluid chamber, and
• the needle and the nozzle moves to isolate each other by the pressure of the second gas introduced into the second fluid chamber.