Injection Device

Abstract

The present disclosure refers to an injection device comprising a housing, a cartridge holder having a first attachment member, a threaded sleeve insert axially and rotationally constrained to the housing, the threaded sleeve insert having a second attachment member for releasable attachment with the first attachment member, and a metering mechanism. The metering mechanism comprises an actuating element, a piston rod, a piston rod sleeve in which the piston rod can be non-rotatably connected in the piston rod sleeve, and a coupling element coupling the actuating element and the piston rod sleeve. The piston rod can be non-rotatably connected to the piston rod sleeve by a coupling sleeve. The cartridge holder is attached to the threaded sleeve insert by axially moving cartridge holder with respect to the threaded sleeve insert and the housing to engage the coupling sleeve with the piston rod sleeve.

Claims

1-15. (canceled)

16. An injection device, comprising a housing having a central axis, a cartridge holder for receiving a cartridge containing a medicament, the cartridge holder having a first attachment member, a threaded sleeve insert axially and rotationally constrained to the housing, the threaded sleeve insert having a second attachment member, and a metering mechanism, the metering mechanism comprising an actuating element for setting or discharging a dose of the medicament from the injection device, a piston rod for producing an advance movement for dispensing a dose, a piston rod sleeve for accommodating the piston rod, wherein the piston rod is non-rotatably connected to the piston rod sleeve, and a coupling element for coupling the actuating element and the piston rod sleeve to discharge the dose with the actuating element in a manner such that a dispensing movement of the actuating element is transmitted to the piston rod by the piston rod sleeve, wherein the metering mechanism further comprises a reverse rotation prevention element for the piston rod sleeve, to permit rotation of the piston rod sleeve in one direction and to prevent rotation of the piston rod sleeve in an opposite direction, wherein the piston rod is non-rotatably connected to the piston rod sleeve by a coupling sleeve, wherein the coupling sleeve engages the piston rod sleeve to form a non-rotatable connection between the piston rod and the coupling sleeve, and wherein the piston rod is rotatable relative to the piston rod sleeve when the coupling sleeve is out of engagement with the piston rod sleeve, wherein the cartridge holder is configured to move axially with respect to the threaded sleeve insert and the housing to attach the cartridge holder to the threaded sleeve insert by an interaction of the first attachment member and the second attachment member and to bring the coupling sleeve into engagement with the piston rod sleeve.

17. The injection device according to claim 16, wherein the cartridge holder comprises at least one axially extending protrusion directly abutting the coupling sleeve while the cartridge holder moves axially to attach to the threaded sleeve insert, such that a common axial movement of the cartridge holder and the coupling sleeve brings the coupling sleeve into engagement with the piston rod sleeve.

18. The injection device according to claim 16, further comprising a coupling ring axially constrained to the coupling sleeve, wherein the cartridge holder comprises a contact face directly abutting the coupling ring while the cartridge holder moves axially to attach to the threaded sleeve insert, such that a common axial movement of the cartridge holder, the coupling ring and the coupling sleeve brings the coupling sleeve into engagement with the piston rod sleeve.

19. The injection device according to claim 18, wherein the coupling ring is axially guided in the threaded sleeve insert and rotatable with respect to the threaded sleeve insert.

20. The injection device according to claim 16, further comprising a clutch spring, wherein the clutch spring exerts a force on the coupling sleeve to bring the coupling sleeve out of engagement with the piston rod sleeve when the cartridge holder is detached from the threaded sleeve insert.

21. The injection device according to claim 20, wherein the clutch spring is interposed between the coupling sleeve and the piston rod sleeve.

22. The injection device according to claim 16, wherein the first attachment member comprises a cam and the second attachment member comprises a guide track, wherein the guide track comprises at least one portion guiding the cartridge holder with the cam axially with respect to the threaded sleeve insert.

23. The injection device according to claim 16, wherein the first attachment member comprises a cam and the second attachment member comprises a guide track, wherein the guide track comprises at least one portion guiding the cartridge holder with the cam on a helical path with respect to the threaded sleeve insert.

24. The injection device according to claim 16, wherein the actuating element is coupled to the coupling element such that an axial movement of the actuating element for setting a dose is transmitted to the coupling element.

25. The injection device according to claim 16, wherein the coupling element comprises a coupling member and the actuating element comprises a counterpart coupling member.

26. The injection device according to claim 25, wherein the coupling member and the counterpart coupling member can be coupled or decoupled relative to each other by an axial displacement of the coupling element relative to the actuating element.

27. The injection device according to claim 25, wherein the coupling member and the counterpart coupling member can be coupled or decoupled relative to each other by a radial displacement of the coupling element relative to the actuating element.

28. The injection device according to claim 25, wherein the actuating element comprises a shoulder as the counterpart coupling member and the coupling element comprises a flange with at least one tooth as the coupling member arranged such that an axial movement of the actuating element for setting a dose is transmitted to the coupling element.

29. The injection device according to claim 25, wherein the coupling member and the counterpart coupling member are each provided with teeth.

30. The injection device according to claim 16, wherein the coupling element comprises grooves and the piston rod sleeve comprises ribs for preventing relative rotation of the coupling element and the piston rod sleeve and permitting relative axial displacement of the coupling element and the piston rod sleeve.

31. The injection device according to claim 16, wherein the reverse rotation prevention element is configured to engage the piston rod sleeve by a tooth or a latch.

32. The injection device according to claim 31, wherein the reverse rotation prevention element comprises a spring arm or is in the form of a spring arm.

33. The injection device according to claim 16, wherein the reverse rotation prevention element and the piston rod sleeve are coupled to each other.

34. The injection device according to claim 16, wherein the reverse rotation prevention element is non-rotatably and axially-fixedly connected to the housing.

35. The injection device according to claim 16, wherein the piston rod is axially displaceable relative to the piston rod sleeve when the coupling sleeve is out of engagement with the piston rod.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] FIG. 1 schematically shows an injection device according to the prior art;

[0041] FIG. 2 schematically shows a cartridge holder according to an embodiment of the present disclosure; and

[0042] FIG. 3 schematically shows a sectional view of the metering mechanism of an injection device according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0043] Referring to FIG. 1, there is shown an injection device as disclosed in EP 2 643 036 B1 with a metering mechanism. The metering mechanism comprises an actuating element 1 for setting and delivering a dose. The actuating element 1 has an external thread 1b, which is guided into an internal thread of an internal housing 6 of the metering mechanism. To set a dose, the actuating element 1 is screwed out of the housing 6 while the actuating element 1 is screwed back into the housing 6 to deliver (discharge) a dose. A number sleeve 9 (display sleeve) is arranged axially and rotationally fixed on the actuating element 1, to display the actually set dose in a display window 21a of an outer housing sleeve 21 which coaxially surrounds the housing 6. At a distal end of the external thread 1b, there is a stop cam 1a cooperating with a corresponding counter cam (not shown) of the housing 6 to limit the setting of a maximum dose. In stop contact, the actuating element 1 cannot be unscrewed further out of the housing 6. A further stop cam 6b is provided as a minimum dose stop, typically preventing setting a dose below the dose value zero.

[0044] In the metering mechanism, a piston rod 2 is movably mounted with an external thread 2a for generating a movement for dispensing a dose. At the distal end of the piston rod 2, a pressure foot or flange 11 is rotatably arranged. During the advancing movement of the piston rod 2, the flange 11 abuts a rubber bung, which is movably received in a cartridge 19 in order to deliver a medicament from the injection device. The cartridge 19 is received in a cartridge holder 18. A detachable protective cap 20 is provided for receiving the cartridge holder 18.

[0045] The external thread 2a of the piston rod 2 is in a threaded engagement with an internal thread of a threaded sleeve insert 12 (also referred to as threaded sleeve in the following description). The threaded sleeve 12 is axially and rotatably constrained to the housing 6 via the outer housing sleeve 21. The threaded sleeve 12 serves to transform a rotational movement of the piston rod 2 in a combined rotational and axial movement of the piston rod 2. A stop cam 2b of the piston rod 2 can come into abutment contact with the threaded sleeve 12 when the cartridge 19 is empty. The distal end of the cartridge holder 18 has a thread 18b to connect a needle unit to the cartridge 19. At the proximal end of the cartridge holder 18 there is an outwardly projecting locking cam 18a which can be brought into engagement with a guide 12a in the threaded sleeve 12 to form a bayonet locking.

[0046] A piston rod sleeve 3 surrounds the piston rod 2 coaxially. A coupling sleeve 7 is provided for coupling the piston rod 2 detachably with the piston rod sleeve 3. For this purpose, the coupling sleeve 7 is rotationally constrained to the piston rod 2, for example by means of a rib 7a provided on an inner surface of the coupling sleeve 7 engaging a longitudinally extending groove of the piston rod 2. Further, longitudinally extending ribs 7b are arranged on an outer surface of the coupling sleeve 7 which engage grooves 3a on an inner surface of the piston rod sleeve 3.

[0047] A coupling element 4 is provided for coupling the actuating element 1 and the piston rod sleeve 3 such that a dose discharging movement of the actuating element 1 can be transmitted to the piston rod 2 via the piston rod sleeve 3 and the coupling sleeve 7. Longitudinally extending ribs 4b are arranged on an inner surface of the coupling element 4 which engage corresponding ribs 3c extending on an outer surface of the piston rod sleeve 3 to provide a rotationally fixed connection between the coupling element 4 and the piston rod sleeve 3. However, due to the rib connection, the coupling element 4 can move axially relative to the piston rod sleeve 3. The coupling element 4 is provided with a 4a with a tooth 4c which can engage with a corresponding coupling element, e.g. a ring of teeth (not shown), arranged on an internal shoulder of the actuating element 1.

[0048] A knob 8 is rotatably mounted in the actuating element 1 by means of a snap connection 8a (also referred to as locking cam in the following description). A spring 13 is disposed within the knob 8 and is supported at the distal end on a flange 4a of the coupling element 4 and at the proximal end on a spring holder 14 which is held in the knob 8.

[0049] The metering mechanism further comprises a reverse rotation prevention element 5 with a spring arm 5a. The reverse rotation prevention element 5 is rotationally and axially fixed to the housing 6. The spring arm 5a engages a toothing 3b on a radially protruding flange of the piston rod sleeve. The spring arm 5a and the toothing 3b are designed such that the piston rod sleeve 3 can only be rotated in one direction relative to the spring arm 5a, namely during dose discharging.

[0050] The coupling sleeve 7, a coupling ring 15, a coupling holder 16 and a clutch spring 17 are mounted in the threaded sleeve 12. At its distal end, the coupling sleeve 7 has an outwardly projecting ring 7c. The coupling ring 15 comprises webs extending in the longitudinal direction which are provided with an annular groove 15a. The ring 7c of the coupling sleeve 7 is axially fixed in the annular groove 15a but free to rotate with respect to the coupling ring 15. A guide cam 15b is arranged at the distal end of the coupling ring 15 for engaging a guide track 16a of the coupling holder 16. The guide track 16a is designed such that the guide cam 15b can be guided with respect to the threaded sleeve 12 during rotation of the coupling ring 15.

[0051] The clutch spring 17 is supported at its proximal end on the threaded sleeve 12 and with its distal end on the coupling holder 16. The coupling holder 16 is axially displaceable and rotatable relative to the threaded sleeve 12, whereas the coupling ring 15 is axially movable but rotationally fixed with respect to the threaded sleeve 12. The cartridge holder 18 has a recess 18c which can engage with a cam 16c of the coupling holder 16. The coupling holder 16 has a projection 16b to be guided in the threaded sleeve for attaching the coupling holder 16 with a cartridge holder 18 in a locking position. An inwardly projecting web 15c is mounted on an inner surface of the coupling ring 15 which is received in a longitudinal groove 12c of the threaded sleeve 12. Due to the guide slot between the coupling holder 16 and the coupling ring 15, a rotation of the coupling holder 16 relative to the threaded sleeve 12 results in an axial movement of the coupling ring 15 (with coupling sleeve 7) relative to the threaded sleeve 12, thereby bringing coupling sleeve 7 in an out of engagement with the piston rod sleeve 3 depending on the direction of rotation of the coupling holder, i.e. depending of attachment or detachment of the cartridge holder 18.

[0052] In order to set the dose with the injection device of FIG. 1, a user rotates actuating element 1 in a first direction such that the actuating element 1 winds out of housing 6 and housing sleeve 21 guided by external thread 1b. Coupling element 4 is axially entrained by actuating element 1 with flange 4a abutting a respective shoulder in actuating element 1. Tooth 4c rides over the teeth in actuating element 1 compressing spring 13. Due to the splined engagement of the coupling element 4 with the piston rod sleeve 3 the coupling element 4 is prevented from rotation by means of reverse rotation prevention element 5 acting on piston rod sleeve 3. With the cartridge holder 18 attached to the threaded sleeve 12, coupling sleeve 7 and engages piston rod sleeve 3 such that the piston rod 2 is prevented from rotating, too. During dose setting a respective dose value printed on the number sleeve 9 is displayed in the window 21a as of the number sleeve 9 rotates together with actuating element 1.

[0053] After a dose has been set, the user may discharge the dose by pushing on knob 8. This compresses spring 13 such that tooth 4c is kept in engagement with the respective teeth of actuating element 1. Further, actuating element 1 is wound back into the housing 6 and housing sleeve 21, wherein rotation of the actuating element 1 is transmitted via the coupling element 4 to the piston rod sleeve 3 and, thus, via coupling sleeve 7 to piston rod 2. Due to the threaded engagement of the piston rod 2 with the threaded sleeve 12, the piston rod 2 translates axially in the distal direction with the flange 11 acting on a bung (not shown) in the cartridge 19.

[0054] With the injection device of FIG. 1 an empty cartridge 19 may be replaced with a new cartridge which requires resetting of the piston rod 2 from its distal position back to a retracted proximal position. Replacing the cartridge 19 involves detachment of the cartridge holder 18 from the injection device, in more detail from threaded sleeve insert 12, by rotating the cartridge holder 18 guided with respect to the threaded sleeve insert 12 with locking cam 18a moving within guide 12a. This pure rotational movement is followed by an axial movement of the cartridge holder 18 in the distal direction with respect to the threaded sleeve 12. The rotational movement of the cartridge holder 18 .

[0055] Reattachment of the cartridge holder 18 after replacement of the cartridge 19 involves first a proximal movement of the cartridge holder 18 with respect to the threaded sleeve 12 followed by a pure rotational movement. During this rotational movement, entrained by the cartridge holder 18, thus resulting in proximal displacement of the coupling ring 15 with the coupling sleeve 7 to engage the coupling sleeve 7 with the piston rod sleeve 3.

[0056] Turning now to an embodiment of the present disclosure as depicted in FIGS. 2 and 3, the main working principle of dose setting and dose discharging is identical as described above and in EP 2 643 036 B1. The bayonet locking of the cartridge holder 18 with the threaded sleeve insert 12 is substantially the same as described above and in EP 2 643 036 B1, too. The injection device according to the present disclosure may be either a manually driven device as in EP 2 643 036 B1 or a spring driven or spring assisted device.

[0057] FIG. 2 shows that the cartridge holder 18 is provided with a protrusion 18d on its proximal side facing towards the threaded sleeve insert 12. FIG. 3 shows that compared to FIG. 1 the omitted such that the protrusion 18d of the cartridge holder 18 may directly abut the distal face of coupling ring 15 when inserted into the threaded sleeve insert 12 during attachment of the cartridge holder 18. Omitting the coupling holder reduces the number of component parts and simplifies assembly.

[0058] In this embodiment, during its axial movement, the cartridge holder 18 pushes with its protrusion 18d on the coupling ring 15, thereby compressing spring 17 and shifting coupling sleeve 7 proximally to engage piston rod sleeve 3. When detaching the cartridge holder 18 from the injection device and the threaded sleeve insert 12 spring 17 pushes the coupling ring 15 together with the coupling sleeve 7 in the distal direction, thereby decoupling of the coupling sleeve 7 from the piston rod sleeve 3.

[0059] In the embodiment depicted in FIG. 3, the coupling ring 15 is guided in the threaded sleeve insert 12 such that the coupling ring 15 can be displaced axially with respect to the threaded sleeve insert 12 but is prevented from rotation with respect to threaded sleeve insert 12. The coupling sleeve 7 is axially retained in the coupling ring 15 but free to rotate with respect to coupling ring 15.

[0060] As an alternative to the embodiments depicted in FIG. 3, the coupling ring 15 may be omitted in a not shown embodiment, thereby further reducing the number of component parts and further simplifying assembly. In this embodiment, the spring 17 is located interposed between the coupling sleeve 7 and the piston rod sleeve 3, for example between ring 7c and the flange carrying the toothing 3b. In this embodiment the coupling sleeve 7 is guided within the threaded sleeve insert 12 such that the coupling sleeve is free to rotate with respect to threaded sleeve insert 12 and that the limited axial displacement of the coupling sleeve 7 is permitted. The protrusion 18d of the cartridge holder 18 directly abuts the ring 7c of the coupling sleeve 7 when the cartridge holder 18 is inserted into the threaded sleeve insert 12 for attachment. Thus, attachment of the cartridge holder 18 engages of the coupling sleeve 7 with the piston rod sleeve 3, while at detachment of the cartridge holder 18 allows the spring 17 to disengage the coupling sleeve 7 from the piston rod sleeve 3.

[0061] In an embodiment of the present disclosure the interface between the cartridge holder 18 and the threaded sleeve insert 12 is the same as in EP 2 643 036 B1, i.e. with the guide 12a having an axially extending portion and a circumferentially extending portion for guiding the locking cam 18a to move axially and to rotate.

[0062] As an alternative, the circumferentially extending portion of the guide 12a may be replaced by a helical portion such that the locking cam 18a is guided on a helical path. Preferably, the axial movement of the cartridge holder 18 caused by this helical path results in engaging of the coupling sleeve 7 and with the piston rod sleeve 3 when attaching the cartridge holder 18.

REFERENCE NUMERALS

[0063]

TABLE-US-00001 1 actuating element 11 flange 1a cam 12 threaded sleeve insert 1b outer thread 12a guide 2 piston rod 12c groove 2a outer thread 13 spring 2b cam 14 spring holder 3 piston rod sleeve 15 coupling ring 3a grooves 15a groove 3b toothing 15b cam 3c ribs 15c web 4 coupling element 16 coupling holder 4a flange 16a guide track 4b ribs 16b projection 4c tooth 16c cam 5 reverse rotation 17 spring prevention element 5a arm 18 cartridge holder 6 housing 18a cam 6b cam 18b thread 7 coupling sleeve 18c recess 7a rib 18d protrusion 7b ribs 19 catridge 7c ring 20 cap 8 knob 21 housing sleeve 8a snap feature 21a window 9 number sleeve