Dial-Down Mechanism for Wind-Up Pen

• US 20150148750A1
• Filed: 03/15/2013
• Published: 05/28/2015
• Est. Priority Date: 05/31/2012
• Status: Active Grant

• Current Assignee: Novo Nordisk A/S
• Original Assignee: Novo Nordisk A/S
• Inventors: Pedersen, Simon Munch, Roervig, Simon
• Granted Patent: US 10,195,359 B2
• Time in Patent Office: Days
• US Class Current: 604/207
• CPC Class Codes: A61M 2005/2026 Semi-automatic, e.g. user activated piston is assisted by additional source of energy
• 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 5/31535 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

Abstract

The invention relates to a torsion spring driven injection device having a dial-down mechanism for dialling down a selected dose size. The torsion spring (2) is strained when setting a dose by rotating a proximally located dose setting button(30) relatively to the housing in a first direction and unstained when rotating the same dose setting button (30) in a second direction opposite the first direction. In order to secure the torsion spring (2) in its strained position a one-way ratchet mechanism is provided. This one-way ratchet mechanism comprises a fixation element (1) coupled to the housing and having a toothing (6) and a ratchet element (20) having at least one ratchet arm (22) engaging the fixation element (1) and which ratchet element (20) is operational coupled to the dose setting button (30). The dose setting button (30) directly engages the at least one ratchet arm (22) when the dose setting button (30) is rotated in the second direction which releases the at least one ratchet arm (22) from the toothing (6) of the fixation element (1) and allows the ratchet element (20) to rotate relatively to the fixation element (1) in the second direction under influence of the torsion spring (2).

Claims

1. A torsion spring driven injection device having a dial-down mechanism for dialling down a selected dose size, comprising a torsion spring which is strained when setting a dose by rotating a proximally located dose setting button relatively to a housing in a first direction and unstrained when rotating the same dose setting button in a second direction opposite the first direction, the dial-down mechanism further comprising:

a fixation element coupled to the housing and having a toothing,

a ratchet element having at least one ratchet arm engaging the fixation element and which ratchet element is operational coupled to the dose setting button, and

wherein the at least one ratchet arm engages the toothing of the fixation element and is shaped such that the ratchet element is prevented from rotating relatively to fixation element in the second direction when the ratchet arm engages the toothing of the fixation element,

and wherein the dose setting button directly engages the at least one ratchet arm when the dose setting button is rotated in the second direction to thereby release the at least one ratchet arm from the toothing of the fixation element and allow the ratchet element to rotate relatively to the fixation element in the second direction under influence of the torsion spring.

2. An injection device according to claim 1, wherein the fixation element is permanently attached to the housing.

3. An injection device according to claim 1, wherein the fixation element is releasable coupled to the housing.

4. An injection device according to the claim 1, wherein the teeth of the fixation element are V-shaped.

5. An injection device according to claim 1, wherein the at least one ratchet arm has an abrupt end engaging one of the V-shaped teeth of the fixation element.

6. An injection device according to claim 1, wherein the ratchet element protrudes above and beyond the fixation element in the axial direction.

7. An injection device according to claim 1, wherein the ratchet element is provided in the proximal end of the injection device.

8. An injection device according to claim 1, wherein the dose setting button has a first protrusion engaging the ratchet element when the dose setting button is rotated in the first direction to set a dose.

9. An injection device according to claim 1, wherein the dose setting button has a second (or release) protrusion engaging the ratchet arm when the dose setting button is rotated in the second direction.

10. An injection device according to claim 9, wherein the second protrusion moves the ratchet arm in an approximate radial direction to release the ratchet arm from the fixation element thereby allowing the torsion spring to rotate the ratchet element in the second direction.

11. An injection device according to claim 9, wherein at least a part of the second protrusion is positioned such that the ratchet arm abuts the second protrusion when released.

12. An injection device according to claim 11, wherein the at least part of the second protrusion is positioned in front of the abrupt end of the ratchet arm when the ratchet arm is released as the dose setting button is rotated in the second direction.

13. An injection device according to claim 9, wherein the second protrusion has an upper surface designed to catch the ratchet arm when the dose setting button is rotated in the second direction.