Dial-Down Mechanism for Wind-Up Pen

• US 20120095410A1
• Filed: 10/21/2009
• Published: 04/19/2012
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Novo Nordisk A/S
• Original Assignee: Novo Nordisk A/S
• Inventors: Møller, Claus Schmidt, Markussen, Tom Hede, Radmer, Bo, Enggaard, Christian Peter
• Granted Patent: US 9,132,239 B2
• Time in Patent Office: Days
• US Class Current: 604/207
• 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 5/31525 Dosing burettes, pipettes B01L3/02
• 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

Abstract

The present invention relates to a dial-down mechanism for an injection device comprising a torsion spring for assisting injection of a dose of medicament from the injection device, the dial-down mechanism comprising a ratchet arm (21) engaging a ring element (10) and a reset element (30) which acts on a knob located on the periphery of the ratchet arm (21) to move the ratchet arm (21) out of engagement with the ring element (10) in order to allow the set dose to be reduced.

Claims

1. A dial-down mechanism for an injection device comprising a torsion spring which is strained when setting a dose by rotating a dose setting element (20) relatively to a housing in a first direction and unstrained when rotating the dose setting element (20) in a second direction opposite the first direction, the dial-down mechanism comprising:

a fixation element (10) coupled to the housing and having a plurality of inwardly pointing teeth (12),

at least one ratchet arm (21) coupled to the dose setting element (20),

wherein the at least one ratchet arm (21) engages the teeth (12) of the fixation element (10) and is shaped such that the dose setting element (20) is prevented from rotating in the second direction when the ratchet arm (21) engages the teeth (12) of the fixation element (10),

and which dial-down mechanism further comprises a reset member (30) which when rotated in the second direction activates the ratchet arm (21) to disengage the fixation element (10) and thereby allow the dose setting element (20) to rotate in the second direction, wherein

the reset tube (30) is at least partially provided inside the dose setting tube (20) and axially retained by the dose setting tube (20),

the ratchet arm (21) carries at least a part (25) extending radially from the at least one ratchet arm (21) and having an outer radius from the centre axis of the injection device larger than the outer radius of the remaining part of the ratchet arm (21), and

the reset tube (30) carries at least one forward extending reset element (32) located distally to the reset tube (30) and which acts on the at least one part (25) of the ratchet arm to move the ratchet arm (21) out of engagement with the teeth 12 of the fixation element (10).

2. A dial-down mechanism according to claim 1, characterized in that, the reset element (32) travels along a constant radius from the centre axis of the injection device when rotated.

3. A dial-down mechanism according to claim 1, characterized in that, the ratchet arm (21) is provided with a steep surface (24) engaging a steep surface (13) of the teeth (12) of the fixation element (10).