Diaphragm foam pump for foam dispensers and refill units

Abstract

A refill unit for a foam dispenser including a liquid container and a diaphragm foam pump connected to the liquid container and diaphragm foam pumps. The diaphragm foam pump includes an elastomeric diaphragm having an air piston bore and a bellows. The air piston bore forms at least a portion of an air chamber. A reservoir is located at least partially within the bellows that includes a liquid inlet. The diaphragm foam pump includes a piston that forms a portion of the air chamber wherein the piston bore may be moved relative to the piston. Movement in a first direction causes air in an air chamber to be compressed and draws liquid into the reservoir and further movement in the same direction causes compressed air to flow into the reservoir where it mixes with the liquid and is expelled as a foam.

I/We claim: 
     
         1 . A refill unit for a foam dispenser comprising:
 a liquid container and   a diaphragm foam pump connected to the liquid container;   the diaphragm foam pump including;
 an elastomeric diaphragm having an air piston bore portion and a compressible reservoir portion formed as a unitary piece; 
 the air piston bore portion forming at least a portion of an air chamber; 
 a liquid inlet into the compressible reservoir; 
 a piston forming at least a portion of the air chamber, wherein the piston bore moves relative to the piston to compress air; 
   wherein movement of the air piston bore portion relative to the piston in a first direction causes air in the air chamber to be compressed and draws liquid into the reservoir and wherein further movement of the air piston bore causes compressed air to be released from the air chamber and to flow into the reservoir.   
     
     
         2 . The refill unit of  claim 1  wherein the piston is stationary and the compressible reservoir is a bellows. 
     
     
         3 . The refill unit of  claim 2  wherein the air piston bore has a slit valve located in a wall. 
     
     
         4 . The refill unit of  claim 2  wherein the air piston bore is located at least partially within the reservoir. 
     
     
         5 . The refill unit of  claim 2  wherein the piston is secured to a cap which connects to the liquid container. 
     
     
         6 . The refill unit of  claim 2  further comprising an outlet passage from the reservoir that has a first cross-sectional area that is different than a second cross-sectional area. 
     
     
         7 . The refill unit of  claim 2  further comprising one or more recesses in the piston bore for allowing air to enter the air chamber. 
     
     
         8 . 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. 
   
     
     
         9 . The diaphragm foam pump of  claim 8  comprising an air outlet in a wall of the air piston bore wherein the air is sized to restrict air flow therethrough. 
     
     
         10 . The diaphragm foam pump of  claim 9  wherein the air outlet is a slit valve. 
     
     
         11 . The diaphragm foam pump of  claim 8  further comprising an outlet passage that has a first portion with a first cross-sectional area and a second portion with a second cross-sectional area that is greater than the first. 
     
     
         12 . The diaphragm foam pump of  claim 8  wherein the piston post is secured to a cap that is securable to a liquid container. 
     
     
         13 . The diaphragm foam pump of  claim 8  further comprising a container filled with a foamable liquid. 
     
     
         14 . The diaphragm foam pump of  claim 8  wherein the liquid inlet passage is formed between a portion of a shell and the diaphragm. 
     
     
         15 . 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. 
   
     
     
         16 . The diaphragm foam pump of  claim 15  further comprising an outlet duck-bill valve. 
     
     
         17 . The diaphragm foam pump of  claim 15  wherein the piston bore has a slit valve through one of its walls for the compressed air to pass therethrough. 
     
     
         18 . The diaphragm foam pump of  claim 15  wherein the outlet valve is integrally formed with the elastomeric diaphragm. 
     
     
         19 . The diaphragm foam pump of  claim 15  wherein the piston bore comprises one or more elongated recesses for allowing air to enter the air chamber. 
     
     
         20 . The diaphragm foam pump of  claim 15  wherein the elastomeric diaphragm further comprises an actuator member for engaging with a dispenser actuator.