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

• Current Assignee: Novo Nordisk A/S
• Original Assignee: Novo Nordisk A/S
• Inventors: Hansen, Torben S., Hemmingsen, Hans, Nielsen, Christian H., Kiilerich, Ebbe, Avlund, Mikkel, Melander, Matias
• Primary Examiner(s): GILBERT, ANDREW M
• Application Number:
  US14/368,708
• Publication Number:
  US 20140350478A1
• Time in Patent Office: 1,475 Days
• US Class Current: 1/1
• CPC Class Codes: A61M 2005/3126 Specific display means related to dosing
• CPC Class Codes: A61M 2005/3143 Damping means for syringe components executing relative movements, e.g. retarders or attenuators slowing down or timing syringe mechanisms
• CPC Class Codes: A61M 2205/42 Reducing noise
• CPC Class Codes: A61M 5/20 Automatic syringes, e.g. with automatically actuated piston rod, with automatic needle injection, filling automatically A61M5/142 , A61M5/46 take precedence; hypodermic projectiles F42B12/54
• CPC Class Codes: A61M 5/2033 Spring-loaded one-shot injectors with or without automatic needle insertion multishot dosing syringes A61M5/31525, needle insertion only A61M5/3287
• CPC Class Codes: A61M 5/31535 Means improving security or handling thereof, e.g. blocking means, means preventing insufficient dosing, means allowing correction of overset dose
• CPC Class Codes: A61M 5/3155 by rotational movement of dose setting member, e.g. during setting or filling of a syringe
• CPC Class Codes: A61M 5/31553 without axial movement of dose setting member
• CPC Class Codes: A61M 5/3156 using volume steps only adjustable in discrete intervals, i.e. individually distinct intervals
• CPC Class Codes: A61M 5/31578 based on axial translation, i.e. components directly operatively associated and axially moved with plunger rod
• CPC Class Codes: A61M 5/31593 Multi-dose, i.e. individually set dose repeatedly administered from the same medicament reservoir

Abstract

The present invention relates to an automatic torsion spring based injection device having a dial-up/dial-down mechanism by which a dose can be set by rotating a dose setting member in a first direction and which dose size can be reduced by rotating the same dose setting member in a second and opposite direction. The dial-up/dial-down mechanism operates a torsion spring which is strained when setting a dose and unstained when rotating the dose setting element in the second direction. In order to secure the torsion spring when strained, a ratchet arm (21) following the rotation of the dose setting element in the first direction, engages a toothed element (10) such that engagement of the at least one ratchet arm (21) with teeth (12) of the toothed element (10) prevents unwinding of the torsion spring, and wherein the rotation of the dose setting member in the first direction moves the ratchet arm (21) from one tooth (12) to the subsequent tooth (12) of the toothed element (10), and rotation of the dose setting member in the second direction lowering the set dose activates the ratchet arm (21) to disengage the teeth (12) of the toothed element (10) and thereby allow the torsion spring to move the ratchet arm (21) in the second direction to the previous tooth (12) such that the force accumulated in the torsion spring reduces incrementally. In order to provide a smooth movement when dialing down the set dose, the at least one ratchet arm (21) is provided o a ratchet tube (20) which carries friction teeth (30) which engage with a cam curve (16) of the toothed element, dampening the movement of the ratchet arm (21) by the torsion spring.

Claims

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, and

a 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, and

rotation 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, and

wherein 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.

2. An automatic torsion spring based injection device according to claim 1, wherein the ratchet tube carries the plurality of friction teeth.

3. An automatic torsion spring based injection device according to claim 2, wherein a part of the toothed element engaging the plurality of friction teeth constitutes a cam curve.

4. An automatic torsion spring based injection device according to claim 1, further comprising a reset tube where the reset tube is coupled between the ratchet tube and the dose setting element.

5. An automatic torsion spring based injection device according to claim 1, wherein the ratchet tube is keyed to a dose indicator sleeve by a key and groove connection.