Patent ID: 7942647

Claim:
A pump for supplying chemical liquids using operating gas, the pump comprising: a pump housing having a concave chamber; and a diaphragm having a flexible film that divides the concave chamber into a pumping chamber and an operating gas chamber; the pump housing further including: a gas passage; a suction passage; and a discharge passage; the gas passage being connected to the operating gas chamber and configured to drive the flexible film with the operating gas; the suction passage being connected to the pumping chamber and configured to suction the chemical liquids with the driven flexible film; the discharge passage being connected to the pumping chamber and configured to discharge the chemical liquids with the driven flexible film; and the pump housing further including a stationary protruding portion positioned on a first internal concave wall surface of the operating gas chamber so that the stationary protruding portion is offset from a center of the first internal concave wall surface of the operating chamber; the pump being configured so that: during suctioning of the chemical liquid, operating gas inside the operating chamber is evacuated from the chamber and the flexible film deforms against the first internal concave wall surface of the operating gas chamber, and a part of the flexible film corresponding to the protruding portion rides on the protruding portion wherein the part of the flexible film riding on the protruding portion deforms in a convex shape toward the pumping chamber; and during discharging of the chemical liquid, operating gas is introduced into the operating chamber and the flexible film deforms towards the pumping chamber beginning from the part of the flexible film that is riding on the protruding portion, so that pulsations due to the drive of the flexible film are reduced; and a height of the stationary protruding portion from the first internal concave wall surface decreases continuously toward a periphery of the stationary protruding portion.