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Auto-injector

  • US 10,258,740 B2
  • Filed: 06/04/2012
  • Issued: 04/16/2019
  • Est. Priority Date: 06/02/2011
  • Status: Active Grant
First Claim
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1. An auto-injector comprising:

  • a cassette unit for use with an auto-injector having an electrically powered drive unit, said cassette unit comprising;

    a cassette unit housing defining a cassette unit housing cavity and a needle projection aperture, said cassette unit housing cavity in receipt of a syringe comprising;

    a barrel for containing a volume of a liquid drug formulation, said barrel defining a flange at the rear end thereof and a forward shoulder at the forward end thereof;

    a hollow needle at a front end of said barrel, said hollow needle defining a needle tip for dispensing of said liquid drug formulation; and

    a plunger that is axially movable within the barrel; and

    in contact with said plunger and axially movable within the barrel, a plunger slaving part defining a rear drive-receiving face and a forward drive-transferring face, and arranged such that when a drive load is applied to a rear drive-receiving face thereof the drive load is evenly transmitted to a rear end of the plunger by contact with said forward drive-transferring face thereof,wherein a drive end of a drive transfer element for transferring axial drive to the plunger slaving part and subsequently to the plunger is arranged for receipt in a central recess of the plunger slaving part and configured to apply a point load to the rear-drive receiving face of the plunger slaving part,wherein the plunger defines a hollow well therein and has a rear end wall that defines both the perimeter of said hollow well and the rear end of the plunger, andwherein said hollow well has a well floor that tapers to a central point; and

    a drive unit comprising;

    a drive unit housing defining a docking cavity and a needle delivery aperture, wherein said docking cavity is arranged for docking receipt of the cassette unit at a docking position, whereupon said cassette unit and/or said syringe is movable from a rest position, in which the needle tip of the syringe is within the drive unit housing to a use position, in which the needle tip protrudes from said needle delivery aperture; and

    a drive arrangement, said drive arrangement comprising;

    one or more electrically powered sources of axial drive;

    a first drive transfer element for transferring said axial drive to the cassette unit and /or to the syringe for advancing the syringe to said use position; and

    a second drive transfer element for subsequently transferring the axial drive to the plunder slaving part and hence, to the plunger of the syringe for moving the plunger into the barrel of the syringe to eject at least part of said volume of liquid drug formulation,wherein the second drive transfer element defines said drive end for transferring axial drive to the plunger slaving part and subsequently to the plunger and arranged for receipt in the central recess of the plunger slaving part and configured to apply a point load to the rear-drive receiving face of the plunger slaving part, andwherein the second drive transfer element is in the form of a rotating screw or worm drive.

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