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Plunger for a medication cartridge

  • US 9,981,088 B2
  • Filed: 03/18/2013
  • Issued: 05/29/2018
  • Est. Priority Date: 03/27/2012
  • Status: Active Grant
First Claim
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1. A medication cartridge plunger comprising:

  • a sealing member formed of a resilient material, said sealing member including a body with a forward end, a rearward end, and a length that extends in an axial direction between said forward end and said rearward end, wherein along said body length said sealing member includes at least one sealing surface extending around said body for a slideable, fluid- tight sealing engagement with an interior surface of a cartridge barrel in which the medication cartridge plunger is installed for use, wherein a central region of said rearward end of said body includes a recessed surface that defines a plate portion accommodating hollow and an attachment portion receiving cavity; and

    a force distributing member including a plate portion and an attachment portion projecting forward from said plate portion, said plate portion attached to said sealing member by said attachment portion fitting within said attachment portion receiving cavity, said force distributing member formed of a material more rigid than said resilient material, said plate portion shaped complementary with said sealing member to distribute to said recessed surface a medication expelling force that may be applied to said plate portion by an external drive element to drive the plunger forward, wherein a forward face of the plate portion contacts the recessed surface of the sealing member to distribute the medication expelling force to said recessed surface, said plate portion including an outer radial periphery arranged transverse to the axial direction and fit within said plate portion accommodating hollow, said outer radial periphery having a plurality of apex regions connected by spanning regions, said apex regions disposed along a common circle, said spanning regions disposed within said common circle, wherein each said apex region, relative to the common circle, is not in diametric alignment with any of the other apex regions.

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