Needle-free injector dose setting apparatus and methods
A needle-free injector including dose setting apparatus. The needle-free injector includes a hammer housing, a mainspring positioned within the hammer housing, and a hammer assembly engaged with the mainspring. The hammer assembly may include a hammer sleeve and a hammer engaged with the hammer sleeve, where the engagement between the hammer sleeve and the hammer provides for a forward or rearward position of the hammer with respect to the hammer sleeve be changed to select an injection dose from two or more available injection doses. Additional embodiments include methods of varying or setting the dose delivered by a needle-free injector.
1 . A needle-free housing comprising:
a hammer housing;
a mainspring positioned within the hammer housing;
a hammer assembly engaged with the mainspring, wherein the hammer assembly comprises:
a hammer sleeve; and
a hammer engaged with the hammer sleeve, wherein the engagement between the hammer sleeve and the hammer provides for a forward or rearward position of the hammer with respect to the hammer sleeve to be changed to select an injection dose from two or more available injection doses;
a dose selector knob engaged with the hammer, wherein articulation of the dose selector knob causes the forward or rearward position of the hammer with respect to the hammer sleeve to change;
a threaded engagement between the hammer sleeve and the hammer, wherein rotation of the dose selector knob causes the hammer to rotate at the threaded engagement with respect to the hammer sleeve;
an indexing structure that becomes engaged to limit rotation of the dose selector knob when the dose selector knob is rotated through a defined angle of rotation; and
a bias spring biasing the indexing structure into engagement until the dose selector knob is displaced against the bias of the bias spring, causing the indexing structure to become disengaged.
2 . The needle-free injector of claim 1 wherein the hammer sleeve comprises a spring interface shoulder.
3 . The needle-free injector of claim 2 wherein the hammer comprises a hammer stopping block.
4 . The needle-free injector of claim 3 wherein the hammer housing comprises a forward wall contacting the hammer stopping block when the needle-free injector is discharged.
5 . The needle-free injector of claim 3 wherein the hammer comprises a forward extension extending forward of the hammer stopping block, wherein the forward extension has a fixed length.
6 . The needle-free injector of claim 1 further comprising:
a status indicator defined by or attached to the hammer; and
a viewing window, through which the status indicator may be viewed.
7 . The needle-free injector of claim 1 wherein the status indicator includes indicia of at least one of an arming status of the needle-free injector, and the selected dose to be delivered by the needle-free injector.
8 . The needle-free injector of claim 1 further comprising a control housing element at least partially surrounding the hammer, the control housing element configured to at least partially define the indexing structure.
9 . The needle-free injector of claim 8 wherein the indexing structure includes a plurality of extensions positioned on the dose selector knob, the extensions configured to mate with a plurality of gaps defined by the control housing element.
10 . The needle-free injector of claim 8 wherein the control housing element includes a viewing window through which a status indicator may be viewed.
11 . The needle-free injector of claim 1 wherein the indexing structure includes mating radial splines.
12 . The needle-free injector of claim 1 wherein the dose selector knob includes a central socket configured to rotationally lock the dose selector knob with the hammer.
13 . The needle-free injector of claim 1 wherein the dose selector knob is biased in a forward direction by the bias spring.
14 . The needle-free injector of claim 1 wherein the defined angle of rotation is about 120 degrees.
15 . The needle-free injector of claim 1 wherein the hammer sleeve includes female threads and the hammer includes male threads.