Dose reset mechanism

• US 8,870,831 B2
• Filed: 08/24/2010
• Issued: 10/28/2014
• Est. Priority Date: 08/24/2009
• Status: Active Grant

• Current Assignee: Shl Medical AG
• Original Assignee: SHL Group AB
• Inventors: Holmqvist, Anders, Wieselblad, Anders
• Primary Examiner(s): Mehta, Bhisma
• Assistant Examiner(s): Meghri, Nicholas
• Application Number:
  US13/392,143
• Publication Number:
  US 20120165752A1
• Time in Patent Office: 1,526 Days
• Field of Search: 604/131, 604/134, 604/135, 604/207, 604/208, 604/209, 604/211
• US Class Current: 604/211
• CPC Class Codes: A61M 2005/202 cocking means, e.g. to bias the main drive spring of an injector
• 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 5/31553 without axial movement of dose setting member
• CPC Class Codes: A61M 5/31556 Accuracy improving means
• CPC Class Codes: A61M 5/3156 using volume steps only adjustable in discrete intervals, i.e. individually distinct intervals
• CPC Class Codes: A61M 5/31575 using scaling up or down transmissions, e.g. gearbox
• CPC Class Codes: A61M 5/31586 performed by rotationally moving or pivoted actuator, e.g. an injection lever or handle
• CPC Class Codes: A61M 5/31593 Multi-dose, i.e. individually set dose repeatedly administered from the same medicament reservoir

Abstract

A dose reset mechanism for a medicament delivery device with a housing and a medicament container includes a dose setting member in the housing for setting a dose when it is rotated and for resetting the dose when it is rotated in the opposite direction. The dose setting member has a drive member connected to a plunger rod such that when the drive member rotates, the rod moves axially; and a connection member between the dose setting member and the drive member. A ratchet mechanism enables the connection member to rotate when the dose setting member rotates for setting a dose but not to move in the opposite direction. At least one dose reset member and at least one blocking member are connected to the ratchet mechanism such that the connection member and drive member are released when a dose knob is turned in the opposite direction.

Claims

1. A dose reset mechanism for a medicament delivery device having a housing having opposite distal and proximal ends and a medicament container, comprising:

a dose setting member coaxially and rotationally arranged in the housing for setting a dose when it is rotated and for resetting the dose when it is rotated in an opposite direction, the dose setting member having a dose setting knob accessible outside the distal end of the housing;

a drive member connected to a plunger rod to act on the container for expelling the medicament;

a connection member arranged between the dose setting member and the drive member, wherein the connection member and the dose setting member are connected by an engagement mechanism, and the connection member and the drive member are connected by a ratchet mechanism such that the connection member rotates when the dose setting knob rotates for setting a dose and is prevented by the ratchet mechanism from moving in the opposite direction; and

a drive spring having a first end connected to the connection member and a second end connected to a fixed point of the housing such that the drive spring is tensioned when the dose setting member and the connection member are rotated for setting a dose;

wherein the dose setting member further has at least one dose reset member and at least one supporting element interactively connected to the ratchet mechanism such that the ratchet connection between the connection member and the drive member is released when the dose knob is turned in the opposite direction; and

the at least one dose reset member comprises a first arm portion protruding generally transverse to an outer circumferential surface of the dose setting member, a second arm portion axially extending in a proximal direction, and the second arm portion includes a curved surface.

2. The dose reset mechanism of claim 1, wherein the drive member is threadedly connected to the plunger rod such that when the drive member is rotated, the plunger rod is axially moved to expel the medicament.

3. The dose reset mechanism of claim 1, wherein the ratchet mechanism comprises a number of generally radial inwardly extending ledges on a distal inner circumferential surface of the drive member, and generally radial outwardly protruding ledges on free ends of flexible arms extending in a circumferential direction of the connection member.

4. The dose reset mechanism of claim 3, wherein the connection member comprises at least one cut-out forming a slot that extends in a circumferential direction of the connection member and is limited in the circumferential direction by transversal walls of the at least one cut-out and in the radial direction by the circumferential wall of the cut-out and by the flexible arm.

5. The dose reset mechanism of claim 4, wherein the at least one cut-out comprises a closed end from which the flexible arm extends and an open end forming a gap between the ledge and one of the transversal walls of the slot.

6. The dose reset mechanism of claim 1, wherein each ledge on the flexible arms of the connection member is arranged with one side surface having a curved shape and to cooperate with the curved surface of the second arm portion of the reset member.

7. The dose reset mechanism of claim 1, wherein the engagement mechanism comprises at least one dose setting drive member having a first part protruding generally transverse to the outer circumferential surface of the dose setting member and a second part axially extending in a proximal direction, and at least one cut-out provided on the outer circumferential surface of the connection member such that a position of the at least one cut-out corresponds to a position of the at least one drive member, whereby the drive member fits in the cut-outs.

8. The dose reset mechanism of claim 7, wherein a width of the at least one cut-out is larger than a width of the at least one drive member.

9. The dose reset mechanism of claim 8, wherein flexible return elements are circumferentially arranged in the cut-outs, between at least one transversal wall of the cut-outs and the dose setting drive members, and are configured for returning the dose setting member to a neutral position.

10. The dose reset mechanism of claim 1, wherein the dose reset mechanism is included in a medicament delivery device.

11. A dose reset mechanism for a medicament delivery device having a housing having opposite distal and proximal ends and a medicament container, comprising:

a dose setting member coaxially and rotationally arranged in the housing for setting a dose when it is rotated and for resetting the dose when it is rotated in an opposite direction, the dose setting member having a dose setting knob accessible outside the distal end of the housing;

a drive member connected to a plunger rod to act on the container for expelling the medicament;

a connection member arranged between the dose setting member and the drive member, wherein the connection member and the dose setting member are connected by an engagement mechanism, and the connection member and the drive member are connected by a ratchet mechanism such that the connection member rotates when the dose setting knob rotates for setting a dose and is prevented by the ratchet mechanism from moving in the opposite direction; and

a drive spring having a first end connected to the connection member and a second end connected to a fixed point of the housing such that the drive spring is tensioned when the dose setting member and the connection member are rotated for setting a dose;

wherein the dose setting member further has at least one dose reset member and at least one supporting element interactively connected to the ratchet mechanism such that the ratchet connection between the connection member and the drive member is released when the dose knob is turned in the opposite direction;

the ratchet mechanism comprises a number of generally radial inwardly extending ledges on a distal inner circumferential surface of the drive member, and generally radial outwardly protruding ledges on free ends of flexible arms extending in a circumferential direction of the connection member;

the connection member comprises at least one cut-out forming a slot that extends in a circumferential direction of the connection member and is limited in the circumferential direction by transversal walls of the at least one cut-out and in the radial direction by the circumferential wall of the cut-out and by the flexible arm; and

at least one supporting element having a first portion protruding generally transversal to the outer circumferential surface of the dose setting member and a second portion axially extending toward the proximal direction into the slot is configured for locking outwardly protruding ledges in engagement with inwardly extending ledges when the supporting element is positioned adjacent the outwardly protruding ledges.

12. The dose reset mechanism of claim 11, wherein the dose setting member is movable between a neutral position, in which the supporting element is positioned in the slot adjacent the outwardly protruding ledges, and a reset position, in which the supporting element is positioned in the gap at the open end of the slot.

13. The dose reset mechanism of claim 12, wherein the dose setting member is movable between the neutral position and a dose setting position, in which the supporting element is positioned in the closed end of the slot.