Drive assembly for a medication delivery device and medication delivery device comprising a drive assembly

Abstract

A drive assembly for a medication delivery device is provided, comprising a piston rod which is movable from a start position to an end position for medication delivery and resettable from the end position to the start position. The drive assembly further comprises an impeding element for impeding a movement of the piston rod from the end position to the start position during a reset of the piston rod, wherein the impeding element comprises at least one resilient element. Furthermore, a medication delivery device comprising the drive assembly is disclosed.

Claims

1. A drive assembly for a medication delivery device, comprising a piston rod movable from a start position to an end position for medication delivery and resettable from the end position to the start position, wherein the piston rod is configured as a lead screw, wherein the piston rod is configured to carry out a combined axial and rotational movement during movement from the start position to the end position, and an impeding element for impeding a movement of the piston rod from the end position to the start position during a reset of the piston rod, wherein the impeding element comprises at least one resilient element; a dose limiting member being configured to prevent the setting of a dose of medication which is larger than the maximal available amount of medication; wherein the impeding element is permanently fixed to an outer housing of the medication delivery device and is formed as an integral part of the dose limiting member.

2. The drive assembly of claim 1, comprising a plurality of resilient elements being located rotationally symmetric around the piston rod.

3. The drive assembly of claim 1, wherein the impeding element exerts a radial force on the piston rod.

4. The drive assembly of claim 1 comprising a member forming an opening, wherein the impeding element is located at the opening.

5. The drive assembly of claim 4, wherein the impeding element extends into the opening.

6. The drive assembly of claim 1 comprising at least one support bearing being configured to support the piston rod.

7. A medication delivery device comprising a drive assembly according to claim 1.

8. The medication delivery device of claim 7, comprising a medication receptacle which is configured to receive a cartridge containing a medicament.

9. The medication delivery device of claim 8, comprising a main body, wherein the receptacle is detachable from the main body to enable an exchange of the cartridge.

10. The medication delivery device of claim 9, comprising a locking device being configured to inhibit a movement of the piston rod towards a start position when the receptacle is attached to the main body.

11. The medication delivery device of claim 1, wherein the receptacle has to be detached from the main body to enable a reset of the piston rod.

12. The medication delivery device of claim 9, wherein the impeding element is configured to inhibit an unhindered resetting of the piston rod when the receptacle is detached from the main body.

13. A drive assembly for a medication delivery device, comprising: a piston rod movable from a start position to an end position for medication delivery and resettable from the end position to the start position, wherein the piston rod is configured as a lead screw, wherein the piston rod is configured to carry out a combined axial and rotational movement during movement from the start position to the end position, a member forming an opening through which the piston rod is disposed, and an impeding element for impeding a movement of the piston rod from the end position to the start position during a reset of the piston rod, wherein the impeding element, is located at the opening, comprises at least one resilient element, wherein the resilient member comprises a spring arm having a first end connected to the member and a second end protruding into the opening towards the piston rod; and is formed as an integral part of the member.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows a cross-sectional view of a medication delivery device comprising a drive assembly.

(2) FIG. 2A shows a perspective view of an exemplary embodiment of a drive assembly for a medication delivery device.

(3) FIG. 2B shows the embodiment of FIG. 2A without showing the piston rod.

(4) FIG. 3 shows a perspective view of a second embodiment of a drive assembly for a medication delivery device.

(5) FIG. 4 shows a perspective view of a third embodiment of a drive assembly for a medication delivery device.

(6) FIG. 5 shows a front view of a fourth embodiment of a drive assembly for a medication delivery device.

(7) FIG. 6 shows a front view of a fifth embodiment of a drive assembly for a medication delivery device.

(8) FIG. 7 shows a perspective view of a sixth embodiment of a drive assembly for a medication delivery device.

(9) Like elements, elements of the same kind and identically acting elements may be provided with the same reference numerals in the figures.

DETAILED DESCRIPTION

(10) FIG. 1 shows a medication delivery device 9, in particular an injection device. For the detailed description of the medication delivery device 9 it is referred to WO 2009/132778 A1. The medication delivery device 9 comprises a drive assembly 1 comprising a piston rod 3.

(11) The piston rod 3 acts on a piston 10 in a cartridge 11 containing a medication. The cartridge 11 is located in a receptacle 12. The receptacle 12 is attached to a main body 13 of the medication delivery device 9.

(12) The piston rod 3 is configured as a lead screw. The lead screw comprises two threaded sections 23, 24. A first threaded section 23 is located at a distal part of the piston rod 3 and a threaded section 24 is located at a proximal part of the piston rod 3. The piston rod 3 is in threaded engagement with a nut member 14 with the first threaded section 23. Furthermore, the piston rod 3 is in threaded engagement with a drive member 28 with the second threaded section 24. The drive member 28 exerts a force on the piston rod 3 to cause a movement of the piston rod 3 for a dose delivery operation. The threaded sections 23, 24 have opposite senses of rotation.

(13) The medication delivery device comprises a dose setting member 22 and a dispense button 26. For setting a dose, the dose setting member 22 is rotated until the desired dose has been reached. The dose setting member 22 comprises a dial grip 27. By rotating the dial grip 27, the dose setting member 22 is rotated. For dispensing the set dose, the dispense button 26 is depressed.

(14) Furthermore, the medication delivery device 9 comprises a dose limiting member 7. The dose limiting member 7 is configured to inhibit the setting of a dose which is larger than a maximal available amount of medication.

(15) For delivering a dose of a medication, the piston rod 3 is moved in a distal direction 17, towards a distal end 15 of the medication delivery device 9. The distal end 15 is the dispensing end of the medication delivery device 9.

(16) In the depicted embodiment the piston rod 3 is shown in a start position. During the delivery of a dose of a medication, the piston rod 3 is moved towards an end position. The start position may be the most proximal position of the piston rod 3. The end position may be the most distal position of the piston rod 3. In particular, the piston rod 3 may have reached the end position when the medication of a cartridge 11 has been fully or partially delivered.

(17) In particular, during dose delivery, the piston rod 3 is rotated towards a distal end 15 through a nut member 14 for delivering a dose of medication.

(18) The piston rod 3 may be moved in a proximal direction 18, towards a proximal end 16 of the medication delivery device 9 during a reset of the piston rod 3.

(19) The medication delivery device 9 comprises a locking device for preventing a movement of the piston rod 3 in a proximal direction when the receptacle 12 is attached to the main body 13. In particular, the nut member 14 is rotationally fixed with respect to the main body 13 when the receptacle 12 is attached. Thereby, a movement of the piston rod 3 in a proximal direction may be inhibited due to a blocking by the two threaded sections 23, 24 being in engagement with the locking device comprising the nut member 14 and the drive member 28. When the receptacle 12 is detached from the main body 13 the nut member 14 may be disengaged from the main body 13, such that a rotation of the nut member 14 is enabled. Thereby, a reset of the piston rod 3 back to the start position is enabled. During a reset of the piston rod 3, the piston rod 3 rotates towards the proximal end 15. In particular, the piston rod 3 rotates through the dose setting member 22.

(20) The drive assembly 1 comprises an impeding element 2 for impeding an unintended movement of the piston rod 3 during a detachment of the receptacle 12. The impeding element 2 is located at a member forming an opening through which the piston rod 3 extends. In the shown embodiment, the impeding element is located at the dose limiting member 7. In further embodiments, the impeding element 2 may be located at a different member of the drive assembly 1.

(21) In particular, the impeding element 2 is configured to impede the movement of the piston rod 3 towards the start position. In particular, the impeding element is configured to exert a friction force on the piston rod 3. Thereby, an unhindered movement of the piston rod 3 towards the start position is inhibited.

(22) FIGS. 2A to 7 show different embodiments of impeding elements.

(23) FIG. 2A shows an exemplary embodiment of a drive assembly 1 for a medication delivery device. The drive assembly 1 may be used in the medication delivery device as shown in FIG. 1.

(24) The drive assembly 1 comprises a member 8 forming an opening 4 and a piston rod 3 extending through the opening 4. The member 8 may correspond to the dose limiting member 7 shown in FIG. 1.

(25) An impeding element 2 is located at the member 8. The impeding element 2 is configured to be in contact with the piston rod 3. In particular, the impeding element 2 impedes a movement of the piston rod 3 such that a force required for resetting the piston rod 3 to a start position is increased. In particular, the impeding element 2 is configured such that it exerts a radial force on the piston rod 3. Thereby, the piston rod 3 has to be moved against a resistance when resetting the piston rod 3. In particular, the impeding element 2 exerts a friction force on the piston rod 3.

(26) The impeding element 2 may be an integral part of the member 8 of the drive assembly 1.

(27) The impeding element 2 comprises at least one resilient element 6. In the depicted embodiment, the impeding element 2 comprises three resilient elements 6. Each resilient element 6 comprises a shape of an arch. The resilient elements 6 are in contact with the piston rod 3 such that the friction force acting on the piston rod 3 occurring during a reset of the piston rod 3 is increased. The resilient elements 6 are arranged rotationally symmetric around the piston rod 3. The resilient elements 6 are arranged at the same axial position relative to a longitudinal axis 29 of the medication delivery device.

(28) The impeding element 2 is located at the opening 4 of the member 8 through which the piston rod 3 extends. The impeding element 2 extends into the opening 4. In particular, the resilient elements 6 extend into the opening. The resilient elements 6 comprise two ends 19, 20. The resilient elements 6 are connected to the opening 4 at both of their ends 19, 20. Thereby, a high stability of the resilient element 6 may be achieved.

(29) FIG. 2B shows the embodiment of FIG. 2A without showing the piston rod.

(30) FIG. 3 shows a second embodiment of a drive assembly 1 for a medication delivery device. For clarity reasons, the piston rod is not depicted. This embodiment is similar to the embodiment shown in FIGS. 2A and 2B. The drive assembly 1 comprises an impeding element 2, which comprises three resilient elements 6. However, here, the resilient elements 6 are connected to the member 8 only at one of their ends 19. The other end 20 freely protrudes towards the piston rod 3. Thereby, the elasticity of the resilient element 6 may be increased, compared to the embodiment of FIGS. 2A and 2B. The resilient elements 6 may be elastically deformed by the piston rod 3 more easily because of the one-ended connection. Thereby, a radial force, which is exerted on the piston rod 3 by the resilient element 6, may be reduced. Particularly, the friction force which occurs during the reset of the piston rod 3 may be decreased. Thereby, the required force for resetting the piston rod 3 exerted by a user may be reduced.

(31) FIG. 4 shows a third embodiment of a drive assembly 1 for a medication delivery device. For clarity reasons, the piston rod is not depicted. The drive assembly 1 comprises an impeding element 2 which comprises a resilient element 6 comprising a spring arm 21. The spring arm 21 is pre-tensioned towards the piston rod 3. Accordingly, the spring arm 21 is configured as a biasing element. Thereby, the spring arm 21 exerts a radial force on the piston rod 3. The spring arm 21 comprises the shape of a hook. Thereby, the contact area between the piston rod 3 and the resilient element 6 is increased. The spring arm 21 is connected to the member 8 at one end 19. Thereby, a high elasticity of the resilient element 6 may be achieved.

(32) Furthermore, the impeding element 2 comprises two support bearings 5. The support bearings 5 are configured such that they may support the piston rod 3 when the spring arm 21 exerts a force on the piston rod 3. The support bearings 5 are located at the opening 4 of the member 8. Particularly, the support bearings 5 support the piston rod 3 in a direction such that a radial position of the piston rod 3 is maintained. In particular, the position of the piston rod 3 is maintained concentric in the opening 4 of the member 8.

(33) FIG. 5 shows a fourth embodiment of a drive assembly 1 for a medication delivery device. For clarity reasons, the piston rod is not depicted. The drive assembly 1 comprises an impeding element 2 comprising three resilient elements 6. The resilient elements 6 of the impeding element 2 comprise a meander shape. Particularly, the resilient elements 6 are waved. Thereby, a high stability as well as a high elasticity of the resilient elements 6 may be achieved. Each of the resilient elements 6 comprises two ends 19, 20. The resilient elements 6 are connected to the member 8 at both of their ends 19, 20.

(34) In particular, the resilient elements 6 form a clamp 25. The clamp 25 acts on the piston rod 3 from different sides of the piston rod 3 and, thereby, clamps the piston rod 3.

(35) FIG. 6 shows a fifth embodiment of a drive assembly 1 for a medication delivery device. For clarity reasons, the piston rod is not depicted. The impeding element 2 comprises three resilient elements 6 comprising a meander shape. The resilient elements 6 are connected to the member 8 at both of their ends 19, 20. Furthermore, the resilient elements 6 are connected to each other. In particular, the resilient elements 6 form a clamp 25. The clamp 25 acts on the piston rod 3 from different sides of the piston rod 3 and, thereby, clamps the piston rod 3.

(36) FIG. 7 shows a sixth embodiment of a drive assembly 1 comprising an impeding element 2. For clarity reasons, the piston rod is not depicted. The impeding element 2 is located at an opening 4 through which the piston rod 3 may extend. The opening 4 is formed by a member 8 which is permanently fixed to an outer housing of the medication delivery device. However, the shape of the shown impeding element 2 is not specific for the shown member 8. In particular, the shown impeding element 2 may alternatively be part of a dose limiting member 7 as shown in FIGS. 2A to 6 or of another member of the drive assembly 1.

(37) The impeding element 2 comprises two resilient elements 6. In this embodiment, the resilient elements 6 are straight. The resilient elements 6 are arranged at opposite sides of the piston rod 3. In particular, the resilient elements 6 form a clamp 25. The clamp 25 acts on the piston rod 3 from different sides of the piston rod 3 and, and thereby clamps the piston rod 3.