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Torsion-spring based wind-up auto injector pen with dial-up/dial-down mechanism

  • US 9,533,106 B2
  • Filed: 12/20/2012
  • Issued: 01/03/2017
  • Est. Priority Date: 12/29/2011
  • Status: Expired due to Fees
First Claim
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1. An automatic torsion spring based injection device for multiple injections of a settable and adjustable dose size of a liquid drug comprising:

  • a housing holding the liquid drug,a rotatable dose setting element comprising a ratchet tube for setting a size of a dose thereby straining a torsion spring, anda dial-up/dial-down mechanism;

    wherein the torsion spring is strained when setting the dose by rotating a dose setting element relative to a housing in a first direction and unstrained when rotating the dose setting element in a second direction opposite the first direction,the dial-up/dial-down mechanism comprises;

    at least one ratchet arm arranged to follow the rotation of the dose setting element in the first direction when setting a dose,a toothed element securing the at least one ratchet arm against a bias of the torsion spring such that engagement of the at least one ratchet arm with a tooth of the toothed element prevents unwinding of the torsion spring, and wherein rotation of the dose setting element in the first direction moves the at least one ratchet arm from one tooth to the subsequent tooth of the toothed element, androtation of the dose setting element in the second direction lowering the set dose activates the at least one ratchet arm to disengage the teeth of the toothed element and thereby allow the torsion spring to move the at least one ratchet arm in the second direction to the previous tooth such that the force accumulated in the torsion spring reduces incrementally,wherein,the at least one ratchet arm is provided on the ratchet tube which ratchet tube further engages with the toothed element through a plurality of friction teeth thereby dampening a movement of the at least one ratchet arm executed by the torsion spring when the at least one ratchet arm is disengaged from the teeth of the toothed element, andwherein the ratchet tube is provided with structure preventing a dose indicator sleeve from rattling comprising a number of flexible legs provided between the ratchet tube and the dose indicator sleeve.

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