Dispensing speed control mechanism and injection device

#This application is a 371 U.S. National Phase Application of International Application Serial No. PCT/EP2014/057000, filed on Apr. 8, 2014, entitled “DISPENSING SPEED CONTROL MECHANISM AND INJECTION DEVICE” which claims priority to European Application Serial No. 13163108.7, filed on Apr. 10, 2013 the entire contents of which are hereby incorporated by reference.

#The present invention is generally directed to a handheld injection device, i.e. a drug delivery device for selecting and dispensing a number of user variable doses of a medicament. In more detail, the invention refers to a dispensing speed control mechanism and an injection device with such a speed control mechanism.

#Pen type drug delivery devices have application where regular injection by persons without formal medical training occurs. This may be increasingly common among patients having diabetes where self-treatment enables such patients to conduct effective management of their disease. In practice, such a drug delivery device allows a user to individually select and dispense a number of user variable doses of a medicament. The present invention is not directed to so called fixed dose devices which only allow dispensing of a predefined dose without the possibility to increase or decrease the set dose.

#Non-limiting, exemplary embodiments of the invention will now be described with reference to the accompanying drawings, in which:

#FIG. 1 shows an exploded view of an injection device comprising a limiter mechanism according to a first embodiment of the invention,

#FIG. 2 shows a section view of the limiter mechanism of FIG. 1 during dose setting,

#An injection device 1 according to the present invention is shown in FIG. 1 in an exploded view, wherein the dispensing speed control mechanism, which is shown in more detail in FIGS. 16 to 17c is not visible in FIGS. 1 to 12. The injection device comprises a cartridge holder 10, a cartridge 20 and a limiter mechanism. The limiter mechanism comprises a housing with an outer housing 30 and an inner housing 40, a dial sleeve as a dose setting member 50 with a dial grip 51, a limiting element 60, a tubular drive member 70, a lead screw 80, a bearing 81, a nut 90, a drive spring 100 with a storage spool 101 and an output spool 102, a return spring 110, a dose button 120, a display wheel 130 and a gear wheel 140. With the exception of the gear wheel 140, the storage spool 101 and the spring 100, all components are located concentrically about a common principle axis of the mechanism. In more detail, the drive member 70 surrounds the lead screw 80, the output spool 102 and the dose setting member 50 surround the drive member 70, and the limiting element 60 and the display wheel 130 surround the dose setting member 50. Further, the nut 90 is located between the drive member 70 and the dose setting member 50.

#FIGS. 1 and 2 show cross-sectional views of the limiter mechanism concept incorporated into a pen injector. A medicament cartridge 20 is housed within the cartridge holder 10. The cartridge holder 10 is rigidly constrained in a body defined by the proximal housing part 30 and the distal housing part 40. The cartridge holder 10 provides location and containment of the medicament cartridge 20 and partial protection of the spring 100 and the storage spool 101.

#The distal end of the lead screw 80 connects to the bearing 81 to permit relative rotation but prevent axial separation. The distal face of the bearing 81 abuts a bung of the medicament cartridge 20. It is the lead screw 80 and bearing 81 assembly that drives the bung axially in order to deliver medicament. The lead screw 80 has a thread running along its length, which may be a twin-start thread, in addition to splines 82, which may be a plurality of splines.