Drive Mechanism for a Drug Delivery Device and Drug Delivery Device

• US 20150165130A1
• Filed: 05/28/2013
• Published: 06/18/2015
• Est. Priority Date: 05/30/2012
• Status: Active Grant

• Current Assignee: Sanofi-Aventis Deutschland GmbH (Sanofi )
• Original Assignee: Sanofi-Aventis Deutschland GmbH (Sanofi )
• Inventors: Butler, Stephen David, Horlock, Mark Philip
• Granted Patent: US 9,675,760 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61M 2005/2407 from the rear
• CPC Class Codes: A61M 5/24 Ampoule syringes, i.e. syringes with needle for use in combination with replaceable ampoules or carpules, e.g. automatic ampoules or carpules A61J1/06
• CPC Class Codes: A61M 5/31543 piston rod reset means, i.e. means for causing or facilitating retraction of piston rod to its starting position during cartridge change
• 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 5/31555 by purely axial movement of dose setting member, e.g. during setting or filling of a syringe
• CPC Class Codes: A61M 5/31561 using freely adjustable volume steps
• CPC Class Codes: A61M 5/31585 performed by axially moving actuator, e.g. an injection button
• CPC Class Codes: A61M 5/31593 Multi-dose, i.e. individually set dose repeatedly administered from the same medicament reservoir

Abstract

The drive mechanism for a drug delivery device comprises a piston rod, which is displaced in a distal direction for a delivery of a dose and in a proximal direction for a reset, and a rotatable drive member, which is threadedly engaged with the piston rod and rotates during the delivery of the dose. A biasing member is provided, which is loaded by the rotation of the drive member during the delivery of the dose and tends to rotate the piston rod with respect to the drive member in such a way that the piston rod is screwed into the drive member and is thereby advanced in the proximal direction. The drug delivery device is provided with such a drive mechanism.

Claims

1. A drive mechanism for a drug delivery device (1), comprising:

a piston rod (11), which is displaced in a distal direction (25) for a delivery of a dose and in a proximal direction (26) for a reset, and

a rotatable drive member (16), which is threadedly engaged with the piston rod (11) and rotates during the delivery of the dose,

characterized in that

a biasing member (20) is provided, which is loaded by the rotation of the drive member (16) during the delivery of the dose and tends to rotate the piston rod (11) with respect to the drive member (16) in such a way that the piston rod (11) is screwed into the drive member (16) and thereby advanced in the proximal direction (26).

2. The drive mechanism of claim 1, wherein

the biasing member (20) is a helical spring.

3. The drive mechanism of claim 2, wherein

the helical spring is arranged coaxially with the piston rod (11).

4. The drive mechanism of one of claims 1 to 3, further comprising:

a housing (2) and

a lock nut (13) releasably rotationally locked to the housing (2) and threadedly engaged with the piston rod (11), wherein

the biasing member (20) is latched to the lock nut (13) and to the drive member (16) so that the biasing member (20) is loaded when the drive member (16) rotates relative to the housing (2) during the delivery of the dose, and

the biasing member (20) relaxes when the rotational locking of the lock nut (13) is removed, resulting in a rotation of the lock nut (13) and a corresponding rotation of the piston rod (11) with respect to the drive member (16).

5. The drive mechanism of claim 4, further comprising:

a cartridge holder (3), which can be attached or removed,

the lock nut (13) being rotationally locked with the housing (2) when the cartridge holder (3) is attached and not being rotationally locked with the housing (2) when the cartridge holder (3) is removed.

6. The drive mechanism of claim 5, wherein

the biasing member (20) is loaded when the cartridge holder (3) is being attached.

7. The drive mechanism of claim 6, wherein

the cartridge holder (3) is attached by a helical movement, which rotates the lock nut (13) until the lock nut (13) is rotationally locked with the housing (2).

8. The drive mechanism of claim 7, wherein

the cartridge holder (3) is provided with an activation pin (27), which rotates the lock nut (13) until the lock nut (13) is rotationally locked with the housing (2).

9. The drive mechanism of one of claims 4 to 8, wherein

the piston rod (11) is displaced during the delivery of the drug in the distal direction (25) in a helical movement with respect to the housing (2), the movement of the piston rod (11) being guided by the threaded engagement of the piston rod (11) with the rotationally locked lock nut (13).

10. The drive mechanism of claim 9, wherein

the threaded engagement of the lock nut (13) with the piston rod (11) is effected by a screw thread (12) and the threaded engagement of the drive member (16) with the piston rod (11) is effected by a further screw thread (22), and

the ratio of the distances which are traveled by the drive member (16) and the piston rod (11) during the delivery of the drug is determined by the pitches of the screw thread (12) and the further screw thread (22).

11. A drug delivery device (1) comprising a drive mechanism according to one of claims 1 to 10.

12. The drug delivery device (1) of claim 11, wherein

the device (1) comprises a removable cartridge holder (3) that is provided for a cartridge (8) to be inserted, and

the biasing member (20) generates an automatic reset of the piston rod (11) each time the cartridge holder (3) is removed.

13. The drug delivery device (1) of claim 12, further comprising:

a counter (18), which is automatically reset simultaneously with the piston rod (11).

14. The drug delivery device (1) of one of claims 11 to 13, wherein the device (1) is a pen-type device.

15. The drug delivery device (1) of one of claims 11 to 14, wherein the device (1) is provided to deliver fixed doses.