Anti-rotation feature for infusion pump cartridge
Apparatus is described for administering a substance to a subject. A vial contains the substance and a stopper is disposed within the vial and is slidably coupled to the vial. A first threaded element is (a) rotatable with respect to the vial and (b) substantially immobile proximally with respect to the vial during rotation of the first threaded element. A second threaded element is threadedly coupled to the first threaded element. At least a distal end of the second threaded element is substantially non-rotatable with respect to the vial, and the distal end of the second threaded element defines a coupling portion that couples the second threaded element to the stopper. The first threaded element, by rotating, linearly advances the stopper and at least the distal end of the second threaded element toward a distal end of the vial. Other embodiments are also described.
1. A system for rotating a rotary drive element in a cylindrical vial, the system comprising:
the cylindrical vial comprising a proximal end, a distal end, and an opening in said proximal end; and
the rotary drive element;
the rotary drive element comprising:
a cylindrical cog with a plurality of circumferential protrusions, said cylindrical cog being disposed at least partially outside of said opening in said proximal end of the cylindrical vial;
a first threaded element joined to said cylindrical cog and extending toward said distal end of the cylindrical vial, said first threaded element at least partially extending into said opening in said proximal end of the cylindrical vial, said first threaded element having a threaded portion;
said first threaded element and said cylindrical cog being rotatable with respect to the cylindrical vial but substantially linearly immobile with respect to the cylindrical vial; and
a second threaded element threadably coupled to said threaded portion of said first threaded element, said second threaded element positioned entirely within the cylindrical vial;
wherein rotating said cylindrical cog causes said first threaded element to rotate with respect to said second threaded element, linearly advancing said second threaded element with respect to the cylindrical vial; and
wherein said first threaded element fits into said opening such that a surface of said first threaded element is in contact with a surface of the cylindrical vial.
2. The system of claim 1 , wherein a diameter of said first threaded element is substantially equal to at least one of an inner diameter of the cylindrical vial and an inner diameter of said opening.
3. The system of claim 1 , wherein said surface of said first threaded element is an outer surface; and said surface of the cylindrical vial is an inner surface.
4. The system of claim 1 , wherein said first threaded element aligns said cylindrical cog and the cylindrical vial.
5. The system of claim 1 , wherein said first threaded element is coaxial to said cylindrical cog.
6. The system of claim 1 , wherein said cylindrical cog and said first threaded element are integrally formed.
7. The system of claim 1 , wherein an outer diameter of said cylindrical cog is greater than an inner diameter of said opening.
8. The system of claim 1 , wherein the plurality of circumferential protrusions protrude a distance from the proximal end of the vial.