Dispensing pump

A pump of the resiliently deformable diaphragm type comprising:

• upper and lower housing members interconnected in fluid tight manner to define a pump housing, said members respectively having relatively opposed upper and lower clamping surfaces;
• a resiliently deformable diaphragm having an encircling imperforate flange clamped between said clamping surfaces in normally fluid tight manner, said flange constituting a unitary portion of said diaphragm and defining the sole area of engagement between said diaphragm and said housing members;
• said diaphragm and said upper housing member jointly defining an enclosed pump chamber;
• said lower housing member having a central opening therethrough surrounded by its said clamping surface;
• actuating means carried by said housing for movement through said opening in operative engagement with said diaphragm for deforming the latter to vary the volume of said pump chamber;
• said lower housing member being formed with an inlet port adapted for communication with a source of fluid and opening upwardly through said lower clamping surface beneath said flange, said upper clamping surface being formed with a recess opposite said inlet port extending from the outer peripheral edge of said flange into communication with said pump chamber to permit local upward flexing of said flange and flow of fluid from said inlet port around the outer edge of said flange into said recess;
• said upper housing member being formed with an outlet port communicating with said pump chamber and opening downwardly through said upper clamping surface, said flange normally seating against said last mentioned clamping surface to close the outlet port;
• said lower housing member being formed with a further recess in said lower clamping surface opposite said outlet port extending to the outer peripheral edge of said flange for permitting local downward flexing of said outer peripheral edge and flow of fluid from said pump chamber around said outer peripheral edge into said further recess, said further recess communicating through a discharge passage with the atmosphere.