INJECTION DEVICE

• US 20090163867A1
• Filed: 05/10/2007
• Published: 06/25/2009
• Est. Priority Date: 05/11/2006
• Status: Active Grant

• Current Assignee: Owen Mumford
• Original Assignee: Owen Mumford
• Inventors: Rolfe, Steven Mark Guy, Marshall, Jeremy
• Granted Patent: US 8,167,834 B2
• Time in Patent Office: Days
• US Class Current: 604/136
• 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 5/2448 comprising means for injection of two or more media, e.g. by mixing
• CPC Class Codes: A61M 5/31553 without axial movement of dose setting member
• CPC Class Codes: A61M 5/31586 performed by rotationally moving or pivoted actuator, e.g. an injection lever or handle

Abstract

A pen injection device designed for use with dual or multi-chamber cartridges (14), is provided with an extended length plunger (24) having a non-drive portion (24′) on its forward end and the usual screw-threaded drive portion (24′) on its rearward end. This arrangement allows the plunger to be pushed forwardly whilst the dosing drive mechanism is disengaged to effect a reconstitution movement of the rearward bung (18′) in the cartridge. Thereafter the threaded portion on the plunger (24′) engages the drive mechanism to allow metered dosing.

Claims

1. An injection device for dispensing in use a substance from a dual or multi-chamber cartridge, said cartridge having a bung moveable in a first reconstitution phase of movement and a second, dosing phase of movement, said device comprising:

a body portion;

a plunger mounted in said body portion for longitudinal movement with respect thereto in a forward dispensing direction to co-operate in use with said bung;

a plunger drive element disposed adjacent said plunger for driving said plunger;

said plunger having a drive portion adapted to mate with a complementary drive portion on said drive element and adapted to impart dosing movement to said plunger;

said drive portion extending only partly along said plunger to leave a forward non-drive portion;

whereby, during a reconstitution phase, said plunger may be moved longitudinally forward from a position with the non-drive portion adjacent said drive element, to bring its drive portion into driving engagement with the drive portion on said drive element.

2. An injection device according to claim 1, wherein said drive portions on said plunger drive element and said plunger are complementary threaded drive portions.

3. An injection device according to claim 2, wherein said plunger carries a male thread and said plunger drive element includes a bore having a female thread.

4. An injection device according to claim 3, wherein said non-drive portion of said plunger comprises a non-threaded portion sized to be moveable freely through said plunger drive element.

5. An injection device according to claim 1, including a mover element slideably moveable in said body portion and having an externally accessible push region for being pushed to engage said plunger and to move it to bring said complementary drive portions into driving engagement.

6. An injection device according to claim 5, including means for releasably preventing longitudinal movement of said mover element.

7. An injection device according to claim 5, wherein said mover element includes a cap element defining said push region, said cap element being adapted to engage in snap engagement an end region of said injection device on completion of said constitution movement.

8. An injection device according to claim 1, including bias means for urging said plunger element towards complementary driving engagement with said plunger drive element.

9. An injection device according to claim 8, wherein said bias means and said plunger is arranged such that said plunger is isolated from the influence of said bias means following driving engagement between said complementary drive portions.

10. An injection device according to claim 1, including a drive mechanism to apply a pre-selectable amount of angular movement to said plunger drive element on activation thereof.

11. An injection device according to claim 10, wherein said drive mechanism comprises:

a user suitable dose setting member rotatably mounted on said body portion to set a dose;

a spring acting between said dose setting means and said body portion, said spring being strained to a variable extent depending on movement of said dose setting member;

a ratchet arrangement disposed between said dose setting member and said plunger drive element for allowing one way relative movement therebetween as said dose setting member is rotated to set a dose, and

a trigger member operable to prevent rotary movement of said drive element and releasable to allow said spring to rotate said dose setting member and said plunger drive element by an amount corresponding to the set dose.

12. An injection device according to claim 11, wherein said dose setting element includes a generally cylindrical portion surrounding at least part of said plunger.

14. An injection device according to claim 2, including a mover element slideably moveable in said body portion and having an externally accessible push region for being pushed to engage said plunger and to move it to bring said complementary drive portions into driving engagement.

15. An injection device according to claim 3, including a mover element slideably moveable in said body portion and having an externally accessible push region for being pushed to engage said plunger and to move it to bring said complementary drive portions into driving engagement.

16. An injection device according to claim 4, including a mover element slideably moveable in said body portion and having an externally accessible push region for being pushed to engage said plunger and to move it to bring said complementary drive portions into driving engagement.

17. An injection device according to claim 6, wherein said mover element includes a cap element defining said push region, said cap element being adapted to engage in snap engagement an end region of said injection device on completion of said constitution movement.

18. An injection device according to claim 2, including bias means for urging said plunger element towards complementary driving engagement with said plunger drive element.

19. An injection device according to claim 3, including bias means for urging said plunger element towards complementary driving engagement with said plunger drive element.

20. An injection device according to claim 4, including bias means for urging said plunger element towards complementary driving engagement with said plunger drive element.

13. (canceled)