Diaphragm foam pump for foam dispensers and refill units

A diaphragm foam pump comprising:

• an elastomeric diaphragm having an air piston bore portion and a bellows portion, wherein the air piston bore portion is located at least partially within the bellows portion;
• a reservoir at least partially formed by the bellows and the outside of the piston bore portion;
• a liquid inlet into the reservoir;
• a piston post, wherein the piston bore moves relative to the piston post to compress air;
• an air inlet into the reservoir;
• wherein movement of a portion of the elastomeric diaphragm causes liquid to be drawn into the reservoir and causes air to be forced into the reservoir to mix with the liquid.

A diaphragm foam pump comprising:

• a housing for connecting the diaphragm foam pump to a liquid container;
• a piston post secured to the housing;
• a shell configured to at least partially fit within a neck of the liquid container and held in place by the housing;
• the shell having a cylinder and a liquid inlet located therein;
• an elastomeric diaphragm located at least partially between the shell and the housing;
• the elastomeric diaphragm having a bellows and a piston bore;
• the piston bore having an opening in one end sized to fit over the piston post to form an air chamber;
• the piston bore configured to fit at least partially within the cylinder of the shell;
• wherein movement of the piston bore over the piston post compresses the air chamber and compresses air located therein;
• and compressed air travels between the outside of the piston bore and the cylinder into the bellows.