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Anti-rotation mechanism for telescopic screw assembly

  • US 10,376,647 B2
  • Filed: 03/18/2016
  • Issued: 08/13/2019
  • Est. Priority Date: 03/18/2016
  • Status: Active Grant
First Claim
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1. A injection assembly comprising:

  • a housing;

    a barrel positioned in the housing, the barrel including a proximal end, a distal end, an axis extending between the proximal and distal ends, and a chamber for storing medicine;

    an elongate anti-rotation shaft rotationally fixed to the housing, the shaft having a non circular cross section;

    an inner screw having an inner screw opening configured to complementarily receive the anti-rotation shaft to prevent rotation of the inner screw with respect to the anti-rotation shaft but allow respective linear translation along the axis;

    a outer screw rotatable with respect to the housing and having an outer screw opening to threadably receive the inner screw, wherein rotation of the outer screw translates the inner screw along the axis and along the anti-rotation shaft; and

    a plunger coupled to a distal end of the inner screw and moveable with respect to the chamber to push the medicine out of the chamber when the outer screw is rotated.

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