Inflatable elastomeric pump for an infusion device

An elastomeric pump for an infusion assembly, the pump comprising:

• a mandrel comprising a generally cylindrical body having first end and an opposed second end, a length, a generally uniform outer diameter that corresponds to a first radius (Rmandrel), a central bore extending through the length, a first port positioned between the first end and second end and extending from the outer diameter to the bore to provide a fluid passageway, a fill port at about the first end in fluid communication with the bore, and exit port at about the second end in fluid communication with the bore;
• and
• an inflatable elastomeric tube disposed concentrically about the mandrel, the tube positioned between the first end and second end of the mandrel and covering the first port, the tube being sealingly secured on the mandrel near the respective ends of the tube and having an original inner diameter that corresponds to a second radius (r) so that it approximately matches the outer diameter of the mandrel (Rmandrel), a length (L) less than the length of the mandrel, a wall thickness (t) such that:
• (0.4225×r)<t≦(0.660×r)
• the inflatable tube further comprising a volume (vtube) of an elastomeric material:
• vtube=πL(2rt+t2)
• such that introduction of a volume of liquid (vliquid) determined according to the following equation:
• (12.50×vtube)≦vliquid≦(22.16×vtube)
• through the fill port at a fill pressure of greater than 0 and less than 35 psig expands the inflatable elastomeric tube between the mandrel and the elastomeric tube such that the pump subsequently dispenses substantially all the volume of liquid through the first port upon contraction of the tube to substantially its original inner diameter.

An elastomeric pump for an infusion assembly, the pump comprising:

• a mandrel comprising a generally cylindrical body having first end and an opposed second end, a length, a generally uniform outer diameter that corresponds to a first radius (Rmandrel), a central bore extending through the length, a first port positioned between the first end and second end and extending from the outer diameter to the bore to provide a fluid passageway, a fill port at about the first end in fluid communication with the bore, and exit port at about the second end in fluid communication with the bore;
• and
• an inflatable elastomeric tube disposed concentrically about the mandrel, the tube positioned between the first end and second end of the mandrel and covering the first port, the tube being sealingly secured on the mandrel near the respective ends of the tube and having an original inner diameter that corresponds to a second radius (r) so that it approximately matches the outer diameter of the mandrel (Rmandrel), a length (L) less than the length of the mandrel, a wall thickness (t) such that:
• (0.4225×r)<t≦(0.660×r)
• and wherein the pump, upon inflation with a predetermined volume of liquid and during delivery of that liquid, exhibits a substantially linear pressure versus volume curve from a deflation yield point that is above a predetermined operating pressure to a volume the corresponds with the dispensing of substantially all the volume of liquid through the first port upon contraction of the tube to substantially its original inner diameter.