Resettable drive mechanism for a medication delivery device and medication delivery device

A resettable drive mechanism comprising a housing, a drive member rotatable in a second direction for delivering a dose of a medication, a piston rod driven by the drive member when it rotates in the second direction. A stop member prevents rotation of the drive member in a first direction opposite to the second direction, when the stop member engages the drive member. A clutch member is movable between a delivery position and a reset position. When the clutch member is in the delivery position, the stop member and the drive member are engaged and the drive member is prevented from rotating in the first direction, and when the clutch member is in the reset position, the drive member and the stop member are disengaged, the drive member is rotatable in the first direction and the piston rod is movable in the proximal direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 of European application 08021629.4 filed Dec. 12, 2008, the contents of which are fully incorporated herein by reference.

The present invention relates to a resettable drive mechanism for a medication delivery device and a medication delivery device comprising such a drive mechanism.

In a medication delivery device, a piston within a cartridge that contains medication may be displaced with respect to the cartridge in the distal direction by a piston rod which moves in the distal direction with respect to the cartridge. Thereby, a dose of medication can be expelled from the cartridge. A medication delivery device is described in US 2007/0123829 A1, for example.

In order to provide for a reusable device, after the cartridge containing the medication has been emptied, the piston rod often has to be moved back from a distal end position to a proximal starting position.

It is an object to provide for an improved resettable drive mechanism. Also, an improved medication delivery device should be provided for.

This object may be achieved by a drive mechanism according to the independent claim. Further features, advantages and expediencies are subject matter of the dependent claims.

A resettable drive mechanism for a medication delivery device comprises a housing with a proximal end and a distal end, a drive member rotatable with respect to the housing in a second direction for delivering a dose of a medication, a piston rod adapted to be driven in a distal direction with respect to the housing by the drive member, when the drive member rotates in the second direction, a stop member adapted to prevent rotation of the drive member in a first direction opposite to the second direction with respect to the housing, when the stop member engages the drive member, and a clutch member movable with respect to the housing between a delivery position and a reset position.

When the clutch member is in the delivery position, the stop member and the drive member are engaged, and the drive member is prevented from rotating in the first direction with respect to the housing. When the clutch member is in the reset position, the drive member and the stop member are disengaged, the drive member is rotatable in the first direction with respect to the housing and the piston rod is movable in the proximal direction with respect to the housing.

Preferably, the clutch member is (linearly) displaced with respect to the housing when the clutch member is moved from the delivery position into the reset position or from the reset position into the delivery position. The clutch member may be displaced with respect to one of the drive member and the stop member when the clutch member is moved from the delivery position into the reset position or from the reset position into the delivery position. The other one of the drive member and the stop member may follow movement of the clutch member when the clutch member is moved from the delivery position into the reset position or from the reset position into the delivery position. Via this relative movement, drive member and stop member may be disengaged.

By providing for the clutch member which is movable with respect to the housing between a delivery position and the reset position, moving the piston rod in the proximal direction with respect to the housing is facilitated. In particular, since the drive member may be rotated in the first direction with respect to the housing, the drive member may rotate in that direction which is opposite to the one during delivery of the dose of medication without the rotational movement in the first direction being prevented by the stop member. Thus, proximal movement of the piston rod which may cause the drive member to be rotated in the first direction is no longer prevented and resetting of the drive mechanism is facilitated.

Stop member and drive member may be permanently engaged while the clutch member is in delivery position. The drive member may engage the piston rod. The drive member may be permanently engaged with the piston rod regardless whether the clutch member is in delivery position or in the reset position.

Rotational movement of the drive member may be converted into rotational movement of the piston rod in the same direction. Rotational movement of the piston rod may be converted into displacement of the piston rod with respect to the housing in the distal direction, for example by a threaded engagement of the piston rod with the housing. The piston rod may be displaced in the distal direction with respect to the housing and rotate in the second direction during the distal displacement. The piston rod may be displaced along its rotation axis.

Alternatively, rotational movement of the drive member may be converted into pure (linear) displacement of the piston rod with respect to the housing. Thus, the piston rod may move translationally with respect to the housing without rotating. A displacement axis of the piston rod may run transversely with respect to the rotation axis around which the drive member rotates.

In a preferred embodiment, the drive mechanism comprises a clutch resilient member, preferably a clutch spring member. The clutch resilient member may be biased when the clutch member is in the delivery position. The clutch resilient member may be fully or partly relaxed when the clutch member is in the reset position. The clutch resilient member may be arranged to exert a force on the clutch member which force tends to move the clutch member in the reset position when the clutch member is moved towards the delivery position or is in the delivery position.

In another preferred embodiment, the drive mechanism comprises a clutch stop member. The clutch stop member may be movable with respect to the clutch member. The clutch stop member may be removable, in particular from the drive mechanism. The clutch stop member may be arranged to keep, preferably to hold, the clutch member in the delivery position. The clutch stop member may be provided for preventing movement of the clutch member towards the reset position. The clutch stop member may be arranged to counteract the force exerted by the clutch resilient member that tends to move the clutch member in the reset position. The clutch stop member is preferably releasably secured with respect to the housing. If the clutch stop member is removed from the clutch member, e.g. detached from the housing, the clutch member is permitted to move into the reset position after the clutch stop member has been removed.

Thus, the clutch stop member may keep the drive mechanism in a delivery state by preventing movement of the clutch member towards the reset position. If the clutch stop member is removed from the clutch member, the clutch member may be moved into the reset position, which movement puts the drive mechanism in a reset state.

The clutch stop member and the clutch resilient member, in combination, facilitate provision of an automatically actuated reset mechanism for a drive mechanism. Due to the biased clutch resilient member the clutch member is moved automatically into reset position when the clutch stop member is removed.

In another preferred embodiment, the drive mechanism comprises a resilient member, preferably a spring member. The resilient member may be arranged to keep the stop member and the drive member in abutment and/or engagement. The resilient member may exert a force on one of or both of the drive member and the stop member which force tends to keep the drive member and the stop member in engagement. Preferably, this force has to be overcome for disengaging drive member and stop member.

In another preferred embodiment, the clutch resilient member is a clutch spring member and the resilient member is a spring member. The clutch spring member preferably has a spring strength which is greater than a spring strength of the spring member. Thus, the clutch resilient member may exert a force on the clutch member which overcomes the force exerted by the resilient member by which the stop member and the drive member are kept in abutment and/or engagement. Accordingly, disengaging stop member and drive member is facilitated.

In another preferred embodiment, the stop member and the drive member are arranged to be moved into engagement when the clutch member is moved from the reset position towards the delivery position. The force exerted by the resilient member may assist this movement. An additional external force may be applied for (re-)engaging stop member and drive member. It may be necessary to overcome the force exerted by the clutch resilient member for (re-)engaging stop member and drive member.

In another preferred embodiment, the drive member and the stop member are engaged to form a unidirectional friction clutch mechanism when the clutch member is in the delivery position. Accordingly, relative rotational movement of the drive member with respect to the stop member and, in particular, with respect to the housing in the first direction is prevented when the clutch member is in the delivery position.

In another preferred embodiment, the stop member is secured against rotational movement with respect to the housing and the stop member is displaceable with respect to the housing.

In another preferred embodiment, the stop member is arranged to follow movement of the clutch member towards the reset position, thereby disengaging from the drive member.

In another preferred embodiment, the clutch member is arranged to abut the stop member when the clutch member is moved towards the reset position. Preferably, the clutch member carries the stop member with it towards the reset position after having moved into abutment with the stop member.

Another aspect relates to a medication delivery device comprising a resettable drive mechanism as described above. The medication delivery device additionally comprises a cartridge for holding a medication, the cartridge being releasably attached to the housing.

Features which are described herein above and below in connection with the drive mechanism may also be applied for the corresponding medication delivery device and vice versa.

In a preferred embodiment of the medication delivery device, the cartridge or a cartridge retaining member, which is adapted to retain and/or attach the cartridge to the housing, is the clutch stop member. Thus, the cartridge or the cartridge retaining member may prevent the clutch member from moving into the reset position on account of the force exerted by the clutch resilient member. If the cartridge retaining member or the cartridge is detached from the housing, the clutch member will automatically move into reset position.

Further features, embodiments and expediencies for the drive mechanism or the medication delivery device become apparent from the following description of exemplary embodiments in conjunction with the figures.

Like elements, elements of the same kind and identically acting elements are provided with the same reference numerals in the figures.

Turning now toFIG. 1, a medication delivery device1comprises a cartridge unit2and a drive unit3. The cartridge unit2comprises a cartridge4. Medication5is retained in the cartridge4. The medication5is preferably liquid medication. The cartridge4preferably comprises a plurality of doses of the medication5. The medication5may comprise insulin, heparin, or growth hormones, for example. The cartridge4has an outlet6at its distal end. Medication5can be dispensed from the cartridge through outlet6. The device1may be a pen-type device, in particular a pen-type injector. The device1may be a disposable or a reusable device. The device1may be a device configured to dispense fixed doses of the medication or variable, preferably user-settable, doses. The device1may be a needle-based or a needle free device. The device1may be an injection device.

The term “distal end” of the medication delivery device1or a component thereof may refer to that end of the device or the component which is closest to the dispensing end of the device1. The term “proximal end” of the medication delivery device1or a component thereof may refer to that end of the device or the component which is furthest away from the dispensing end of the device. InFIG. 1, the distal end of the device1was assigned reference numeral7and the proximal end of the device was assigned reference numeral8.

The outlet6may be covered by a membrane9, which protects medication5against external influences during storage of the cartridge. For medication delivery, membrane9may be opened, e.g. pierced. For example, membrane9may be pierced by a needle unit (not explicitly shown). The needle unit may be (releasably) attached to the distal end of the cartridge unit2. The needle unit may provide for fluid communication from the inside of the cartridge4to the outside of the cartridge through outlet6.

A piston10is retained within the cartridge4. The piston10is movable with respect to the cartridge. The piston10may seal the medication5within the cartridge. The piston10expediently seals the interior of the cartridge4proximally. Movement of the piston10with respect to the cartridge4in the distal direction causes medication5to be dispensed from the cartridge through outlet6during operation of the device.

The cartridge unit2furthermore comprises a cartridge retaining member11. The cartridge4is retained within the cartridge retaining member11. The cartridge retaining member11may stabilize the cartridge4mechanically. Additionally or alternatively, the cartridge retaining member11may be provided with a fixing member (not explicitly shown) for attaching the cartridge unit2to the drive unit3.

The cartridge unit2and the drive unit3are secured to one another, preferably releasably secured. A cartridge unit2which is releasably secured to the drive unit may be detached from the drive unit3, for example in order to allow for providing for a new cartridge4, if all of the doses of medication which once were in the cartridge formerly attached to the drive unit3have already been dispensed. The cartridge retaining member11may be releasably secured to the drive unit3via a thread, for example.

Alternatively, the cartridge retaining member11may be dispensed with. It is particularly expedient, in this case, to apply a robust cartridge4and to attach the cartridge directly to the drive unit3.

The drive unit3is configured for transferring force, preferably user-exerted force, particularly preferably manually exerted force, to the piston10for displacing the piston10with respect to the cartridge4in the distal direction. A dose of medication may be dispensed from the cartridge in this way. The size of the delivered dose may be determined by the distance by which the piston10is displaced with respect to the cartridge4in the distal direction.

The drive unit3comprises a drive mechanism. The drive mechanism comprises a piston rod12. The piston rod12may be configured for transferring force to the piston10, thereby displacing the piston in the distal direction with respect to the cartridge4. A distal end face of the piston rod12may be arranged to abut a proximal end face of the piston10. A bearing member (not explicitly shown) may be arranged to advance the piston10, preferably to abut the proximal end face of the piston10. The bearing member may be arranged between piston10and piston rod12. The bearing member may be fixed to the piston rod12or a separate member. If the piston rod12is configured to be rotated during operation of the device, for example during dose delivery, it is particularly expedient to provide for a bearing member. The bearing member may be displaced together with the (rotating) piston rod with respect to the housing. The piston rod may be rotatable with respect to the bearing member. In this way, the risk that the rotating piston rod drills into the piston and thereby damages the piston is reduced. Accordingly, while the piston rotates and is displaced with respect to the housing, the bearing member is preferably only displaced, i.e. does not rotate. The piston rod may be bounded by the bearing member.

The drive unit3comprises a housing13which may be part of the drive mechanism. The piston rod12may be retained in the housing. A proximal end side14of the cartridge unit2may be secured to the drive unit3at a distal end side15of the housing13, for example via a threaded connection. Housing13, cartridge4and/or cartridge retaining member11may have a tubular shape.

The term “housing” shall preferably mean any exterior housing (“main housing”, “body”, “shell”) or interior housing (“insert”, “inner body”) which may have a unidirectional axial coupling to prevent proximal movement of specific components. The housing may be designed to enable the safe, correct, and comfortable handling of the medication delivery device or any of its mechanism. Usually, it is designed to house, fix, protect, guide, and/or engage with any of the inner components of the medication delivery device (e.g., the drive mechanism, cartridge, piston, piston rod), preferably by limiting the exposure to contaminants, such as liquid, dust, dirt etc. In general, the housing may be unitary or a multipart component of tubular or non-tubular shape.

The term “piston rod” shall preferably mean a component adapted to operate through/within the housing, which may be designed to transfer axial movement through/within the medication delivery device, preferably from the drive member to the piston, for example for the purpose of discharging/dispensing an injectable product. Said piston rod may be flexible or not. It may be a simple rod, a lead-screw, a rack and pinion system, a worm gear system, or the like. “piston rod” shall further mean a component having a circular or non-circular cross-section. It may be made of any suitable material known by a person skilled in the art and may be of unitary or multipart construction.

The drive unit3comprises a dose part16. The dose part16is movable with respect to the housing13. The dose part16may be movable in the proximal direction with respect to the housing for setting of a dose of the medication5which is to be delivered and in the distal direction with respect to the housing for delivery of the set dose. The dose part16is preferably connected to the housing13. The dose part16may be secured against rotational movement with respect to the housing. The dose part16may be moved (displaced) between a proximal end position and a distal end position with respect to the housing13(not explicitly shown). The distance by which the dose part is displaced with respect to the housing during setting of the dose may determine a size of the dose. The proximal end position and the distal end position may be determined by a respective stop feature which may limit the proximal ordistal travel of the dose member with respect to the housing. The device1may be a variable dose device, i.e. a device configured for delivering doses of medication of different, preferably user-settable, sizes. Alternatively, the device may be a fixed dose device.

The device1may be a manually, in particular non-electrically, driven device. The (user-applied) force which causes the dose part16to be moved with respect to the housing13in the distal direction may be transferred to the piston rod12by the drive mechanism. For this purpose, other elements of the drive mechanism may be provided which are not explicitly shown inFIG. 1. The drive mechanism is preferably configured to not move the piston rod12with respect to the housing13when the dose part is moved in the proximal direction with respect to the housing for setting of the dose.

Embodiments of a drive mechanism which are suitable to be provided in the medication delivery device1as it was described above are described in more detail below.

A first embodiment of a drive mechanism which is suitable for being implemented in the medication delivery device1as described above is described in connection withFIGS. 2 to 9.

The drive mechanism comprises a housing part17. The housing part17has a proximal end18and a distal end19. The housing part17may be (outer) housing13ofFIG. 1, a part thereof or an insert within housing13, which insert is preferably secured against rotational and axial movement with respect to housing13. The housing part17may be an insert sleeve, for example. The insert sleeve may be snap-fitted or glued to housing13, for example. The housing part17may have a tubular shape. Housing part17may comprise outer fixing elements64, for example snap-fit elements, for fixing housing part17to housing13(cf.FIG. 8).

The piston rod12is retained in the housing13, preferably within housing part17. The piston rod12is driven in the distal direction with respect to the housing part17during dose delivery.

The drive mechanism furthermore comprises a drive member20. Drive member20is retained within the housing part17. Drive member20is configured to transfer force, preferably torque, to the piston rod12. The transferred force may cause the piston rod12to be displaced in the distal direction with respect to the housing part17for dose delivery.

Drive member20is rotatable with respect to housing part17. The drive member20may engage the piston rod12. Rotational movement of the drive member, for example rotational movement in a second direction may be converted into distal movement of the piston rod12with respect to the housing part17. This is explained in more detail below.

The drive mechanism furthermore comprises a rotation member21. The rotation member21is rotatable with respect to the housing part17in a first direction, in particular for setting of a dose of the medication, and in a second direction, in particular for delivering the set dose. The second direction is opposite to the first direction. The first direction may be counter-clockwise and the second direction may be clockwise as seen from the proximal end of the device, for example.

Drive member, rotation member and/or piston rod are preferably configured to be rotatable about a (common) rotation axis. The rotation axis may extend through drive member, rotation member and/or piston rod. The rotation axis may be the main longitudinal axis of the piston rod. The rotation axis may run between the proximal end and the distal end of the housing part17.

The rotation member21is coupled to the drive member20by an unidirectional clutch mechanism, in particular a friction clutch mechanism. This clutch mechanism permits rotational movement of the rotation member21with respect to the drive member20when the rotation member rotates in the first direction with respect to the housing part17. The clutch mechanism prevents rotational movement of the rotation member21with respect to the drive member20, when the rotation member rotates in the second direction with respect to the housing part17. The drive member20may thus follow rotational movement of the rotation member21in the second direction with respect to the housing part17.

The drive member20is arranged to abut and/or engage the rotation member and, in particular, engages rotation member21. The drive member20comprises a toothing22at one end, e.g. its proximal end. The rotation member comprises a toothing23at one end which end faces the drive member20, e.g. its distal end. Toothing22comprises a plurality of teeth24. Toothing23comprises a plurality of teeth25. Teeth24and/or25may extend along the rotation axis. Toothings22and23may be configured to mate with one another.

A respective tooth of teeth24and/or teeth25may be ramp-shaped, in particular along the azimuthal (angular) direction as seen from the rotation axis. The ramp of the respective tooth is limited (in the angular direction) by a steep end face of that tooth, i.e. a face of the tooth that runs parallel to the rotation axis or includes a smaller angle with the rotation axis when projected on this axis than the ramp when projected on this axis. The steep end face is followed by the ramp of the next tooth.

The teeth24may be disposed along the perimeter of that end of the drive member20which faces the rotation member21. The teeth25may be disposed along the perimeter of the rotation member21at that end which faces the drive member20.

When the steep end faces of two teeth abut and the rotation member is rotated further on in the second direction, the steep sides stay in abutment and drive member20follows the rotation of rotation member21. When the rotation member rotates in the first direction, the ramp of the teeth—which ramps, in particular, run obliquely with respect to the rotation axis—slide along each other and, in consequence, the rotation member21may rotate with respect to the drive member20.

The drive mechanism furthermore comprises a stop member26. The drive member may be arranged between the stop member26and the rotation member21. The stop member26is configured for preventing rotational movement of the drive member20in the first direction with respect to the housing part17during setting of a dose, i.e. when the rotation member rotates in the first direction. Thus, the rotation member21may rotate in the first direction with respect to the housing part17, whereas the drive member20and the stop member21don't rotate.

The stop member26is coupled to the drive member20by another unidirectional clutch mechanism, in particular a friction clutch mechanism. This clutch mechanism prevents rotational movement of the drive member20with respect to the stop member20when the rotation member rotates in the first direction with respect to the housing part17. The clutch mechanism permits rotational movement of the drive member20with respect to the stop member26, when the rotation member rotates in the second direction with respect to the housing part17.

Thus, the rotation member21may rotate with respect to the drive member20and the stop member26in the first direction during setting of the dose, with rotation of the drive member being prevented by its interaction with the stop member, and rotation member as well as drive member may rotate with respect to the stop member in the second direction during delivery of the dose.

The stop member may be arranged to abut and/or engage the drive member during setting of the dose and, preferably, during delivery of the dose. The stop member26has a toothing27at one end which faces the drive member, e.g. its proximal end. The teeth may be ramp-shaped with a steep side and a less steep ramp. The teeth may be disposed azimuthally along the perimeter of the stop member.

Drive member20has a toothing28at one end which faces the stop member, e.g. its distal end. Toothings22and28of the drive member20are oppositely disposed. Toothing28may be configured in accordance with toothing21of the rotation member. Toothing22may be configured in accordance with toothing27of the stop member. Toothings27and28, in particular the steep sides of the teeth, do cooperate, e.g. abut, for preventing rotation of the drive member20with respect to the housing part17and, in particular, with respect to the stop member26in the first direction.

Stop member26is preferably secured against rotational movement with respect to the housing part17. Stop member26may be fixed to the housing or integrated into the housing. Stop member26may be fixed against displacement with respect to the housing part17or displacement with respect to the housing part17may be allowed.

As it is illustrated in the present embodiment, stop member26is displaceable with respect to the housing but non-rotatable with respect to the housing part17. For that purpose, one or a plurality of, preferably oppositely disposed, guide features, for example guide lugs29, are provided in the stop member26. The respective guide feature29engages a corresponding guide slot30which may be provided in the housing, e.g. in housing part17. This can be seen inFIGS. 2 to 5. A guide feature29cooperates with a guide slot30to prevent rotational movement of the stop member with respect to the housing part17, with axial movement of the stop member26with respect to the housing being allowed. The axial movement of the stop member26may compensate for play between components of the drive mechanism during operation.

From the group comprising drive member20, stop member26and rotation member21one or more members, preferably two members or three members, may be axially displaceable with respect to the housing part17and, preferably, with respect to the piston rod12. Therein, the drive member and another one of the recited members may be axially displaceable with respect to the housing. The remaining member may be secured against axial displacement or may also be axially displaceable during operation of the drive mechanism for medication delivery. Accordingly, if the drive member and the stop member are axially displaceable, the rotation member may be axially secured or axially displaceable and so on. Play between the components caused by relative (axial) movement of components of the clutch mechanism with respect to the housing can be compensated for in this way. The distance by which the respective components may be axially displaced with respect to the housing may correspond to the (maximum) depth of a tooth of the respective toothing22or28of the drive member. Alternatively, the distance may be greater than the (maximum) depth of a tooth of the respective toothing.

Furthermore, the drive mechanism comprises a resilient member31, preferably a spring member. The resilient member31may be biased during medication delivery operation of the drive mechanism. The resilient member may provide for a force that tends to keep the drive member20in engagement with the stop member26and/or the rotation member21. The force may be exerted along the rotation axis. In the situation shown inFIGS. 2 to 5, this force may be exerted in the proximal direction. The resilient member31may be a helical (coil) spring. The resilient member31may be a compression spring.

The resilient member31may keep the drive member20and the stop member26in (permanent) mechanical contact, e.g. in abutment, with each other during setting and delivery of a dose of the medication. Alternatively or additionally, the resilient member31may keep the drive member20and the rotation member26in (permanent) mechanical contact, preferably abutment, with each other during setting and delivery of a dose of the medication.

The resilient member31may be integrated within stop member26or a separate component. The resilient member31may be arranged on the distal end side of the stop member26.

The drive mechanism furthermore comprises a support member32. Support member32is expediently fixed against axial and rotational movement with respect to the housing part17or integrated into housing part17. Support member32is arranged on that side of the drive member20which is remote from the stop member26. Support member32may be a protrusion, for example a ring-like protrusion. Rotation member21may extend through an opening in support member32. The support member32may provide for a counter force to the force which is exerted by the resilient member31. Permanent abutment of the rotation member with the drive member and of the drive member with the stop member during setting and delivery of medication is facilitated in this way.

The rotation member21has an (radially) outwardly protruding member33, for example a flange portion. The protruding member33is expediently provided for abutting support member32, in particular the distal end side of support member32.

Another support48(cf.FIG. 6) may be provided for providing a counterforce to the force exerted by the resilient member31. Support48is arranged on that side of the drive member20which is remote from the rotation member21. Support48is arranged on that side of the stop member26which is remote from the support member32. The support48may be arranged to abut the resilient member31. The support48may be secured against axial and rotational movement with respect to the housing part17, with respect to the housing13or integrated into the housing13, for example into (additional) housing part40(cf.FIG. 6).

The drive mechanism furthermore comprises a dose member34. Dose member34may be dose part16or may be a part of the dose part16ofFIG. 1. Dose member34is movable with respect to the housing in the proximal direction for setting of a dose and for delivery of the dose. For example, the dose member34may be moved in the proximal direction with respect to the housing part17during dose setting and in the distal direction with respect to the housing part17during dose delivery. The dose member34may engage the housing part17or, alternatively, another part of housing13(not explicitly shown). Dose member34is preferably secured against rotational movement with respect to the housing part17. The dose member34may comprise a guide feature35, for example a guide lug or a guide slot, that engages another guide feature, for example a guide slot or a guide lug, respectively, that is provided in the housing part17or the housing13.

Dose member34may be moved in the proximal direction and in the distal direction with respect to rotation member21. Dose member34is arranged to be couplable and is preferably (permanently) coupled to rotation member21such that movement of the dose member, e.g. in the proximal direction with respect to the housing part17, for setting a dose of the medication is converted into rotational movement of the rotation member in the first direction and movement of the dose member, e.g. in the proximal direction with respect to the housing part17, for delivering the dose is converted into rotational movement of the rotation member21in the second direction opposite to the first direction.

The rotation member21may be provided with an (outer) thread36. Thread36may be engaged with one or a plurality of engagement members42of dose member34. The respective engagement member may be arranged on the inside of the dose member. The respective engagement member may be a thread or a part of a thread, for example. Thus, dose member34and rotation member21may be threadedly coupled, in particularly threadedly engaged. The rotation member21may be arranged inside the dose member34.

The rotation member21, the drive member20, the stop member26and/or the dose member34may be or may comprise a respective sleeve. The piston rod12may be arranged to be driven and, in particular, may be driven through one of, more of or all of those sleeves. The piston rod12may run through one of, more of or all of those sleeves.

The drive member20and the piston rod12are configured for rotational movement of the drive member20with respect to the housing being converted into rotational movement of the piston rod with respect to the housing. The drive member20may engage the piston rod12. The piston rod12is displaceable with respect to the drive member20along a displacement axis. Presently, the displacement axis runs along the rotation axis. The drive member20may be splined to the piston rod12, for example.

The piston rod12is threadedly coupled to the housing13. The piston rod12may be provided with an outer thread49, for example. The piston rod12may extend through and be engaged with a (part) thread in opening39which is provided in housing part40, for example in support48(cf.FIG. 6). Housing part40may be formed integrally with housing part17, may be a housing part fixed thereto or may be a housing part secured separately from housing part17to housing13.

The piston rod12comprises an engagement track37, preferably two oppositely disposed engagement tracks, on the outside. The (respective) engagement track37may interrupt thread49. The (respective) engagement track37preferably extends along the axia along which the piston rod is displaceable with respect to the housing and, in particular, with respect to the drive member.

Rotational movement of the drive member20with respect to the housing may thus be converted into rotational movement of the piston rod12with respect to the housing and the rotational movement of the piston rod12is, on account of the threaded engagement of the piston rod and the housing (part), converted into movement of the piston rod with respect to the housing in the distal direction.

The dose part16(cf.FIG. 1) may comprise a dose knob41(cf.FIG. 8). Dose knob41may be configured to be gripped by a user. Dose knob41may be arranged and connected to the dose member34at the proximal end. Dose knob and dose member may be unitary.

In the following, operation of the present drive mechanism for delivering medication from the cartridge4ofFIG. 1is described.

To set a dose, a user may manually move dose member34in the proximal direction (arrow43) with respect to the housing part17(cf.FIGS. 2,3,8and9). To do so, the user may grip dose knob41and pull it in the proximal direction. Dose member34moves proximally also with respect to the rotation member21. Proximal movement of the rotation member is prevented by support member32which abuts protruding member33of rotation member21. Consequently, the proximal movement of dose member34with respect to the housing part17is converted into rotational movement of the rotation member21in the first direction (arrow44) with respect to the housing part17, in particular on account of the threaded engagement of dose member34and rotation member21. Thus, the rotation member21rotates in the first direction—counter-clockwise as seen from the proximal end of the rotation member—with respect to the housing. Rotation member21also rotates with respect to the drive member20and to the stop member26. The drive member20is prevented from rotating in the first direction by interaction with the stop member26, e.g. by interlocking of toothings27and28. As the piston rod12is coupled to the drive member20and rotation in the first direction of the drive member would cause the piston rod to travel in the proximal direction, the piston rod12is prevented from being driven in the proximal direction by interaction of stop member26and drive member20. Dose accuracy can be increased in this way.

When the rotation member21rotates in the first direction, the ramps of the teeth of toothing23of rotation member21slide along the ramps of the teeth of toothing22. Thus, a tooth of the rotation member may index around the rotation axis until the tooth engages one of the next teeth of toothing22of drive member20. The teeth of rotation member21slide along the ramps of the teeth of drive member20. During this movement, drive member20and, in particular, stop member26are displaced along the rotation axis with respect to piston rod12and housing by a distance determined by, preferably equal to, the depth of a tooth of toothing22, before a tooth of toothing23(totally) disengages that tooth of toothing22. Afterwards, the tooth of the rotation member21engages the next tooth of toothing22and the force provided by resilient member31moves drive member20and, in particular, stop member26back along the rotation axis into the axial start position. An according movement of stop member and drive member in the distal direction and back into the proximal direction is indicated by double arrow45inFIGS. 2 and 3.

A tooth of the rotation member which engages the next tooth of the drive member may cause an audible and/or tactile feedback to the user.

The drive mechanism is suitable for a fixed dose device or a user settable dose device. The size of the fixed dose of medication which is to delivered or the increments in which a user-settable dose may be varied by a user are preferably determined by the distribution of the teeth of the respective toothings in the drive member, rotation member and stop member. The rotation member may be rotated over more than one teeth (dose increment) of the drive member for a user-settable dose device and over one teeth (only) for a fixed dose device. The number of teeth in the drive member20over which the rotation member21rotates during dose setting determines the size of the dose which is actually delivered. The dose member and the rotation member may be adapted to one another such that the rotation member may rotate only by one tooth for a fixed dose device and by more than one tooth for a variable dose device.

After the dose has been set, the dose part16and with it the dose member34is moved (pushed) by the user in the distal direction with respect to housing part17(arrow46; cf.FIGS. 4,5,8and9). Thus, the dose member34is moved in the distal direction with respect to the housing part17. The rotation member21accordingly rotates in the second direction, which is opposite to the first direction, with respect to the housing (arrow47, cf.FIGS. 4 to 9). Drive member20follows rotational movement of the rotation member in the second direction. Rotational movement of the drive member20in the second direction is converted into rotational movement of the piston rod12in the second direction, which movement, in turn, is converted into movement of the piston rod12in the distal direction. Accordingly, the piston10ofFIG. 1may be displaced in the distal direction with respect to the cartridge4and a dose of medication5is dispensed from the cartridge the amount of which corresponds to the previously set dose.

During dose delivery, toothings22and23interlock and ramps of the teeth of toothing28of the drive member20slide along ramps of the teeth of toothing27of stop member26. This movement is similarly as describe above for the relative rotational movement of rotation member and drive member with opposite rotation direction. The stop member26is thereby displaced in the distal direction with respect to the drive member20by a distance corresponding to the depth of a tooth of toothing27in stop member26. Resilient member31forces the stop member26back into the axial starting position, when the next tooth of toothing28is engaged by the respective tooth of toothing27(double arrow65).

A tooth of the drive member which engages the next tooth of the stop member may cause an audible and/or tactile feedback to the user.

FIG. 10schematically shows an oblique sectional view of a second embodiment of a drive mechanism. This drive mechanism essentially corresponds to the one described in conjunction withFIGS. 2 to 9. In contrast thereto, the stop member26is secured against rotational movement and displacement with respect to the housing (13,17,40). Stop member26may be integrated in housing part40or17or an insert thereof. Housing part40may be housing13, for example. Housing part17may be inserted and fixed within housing13. Fixing elements64may engage corresponding elements in the housing for fixing the housing part17to housing part40.

In order to compensate for the relative axial displacement between rotation member21, drive member20and stop member26, when the respective parts rotate with respect to one another, the rotation member21is movable with respect to the housing. In order to keep stop member26and rotation member21in, preferably permanent, abutment with drive member20during medication delivery operation of the drive mechanism, resilient member31exerts a force on the rotation member21, preferably on protruding member33thereof which presses rotation member and drive member20towards stop member26. Resilient member31may be arranged at that side of the drive member which faces away from the stop member, e.g. its proximal side. Resilient member may abut the proximal face of protruding member33. Support member32can thus be dispensed with. The distal end face of housing part17may act as an abutment surface for the resilient member31.

However, when the elements are arranged as shown inFIG. 10, axial movement of the rotation member, which may occur correspondingly to the axial movement of the stop member in the previous embodiment, may be transferred to the dose part16and thereby to the user. This movement of an external part might be irritating for a user.

FIGS. 11 to 15schematically show a third embodiment of a drive mechanism which is suitable for being provided in the medication delivery device1as described in conjunction withFIG. 1.

The drive mechanism essentially corresponds to the one described in connection with the previous embodiments. In contrast thereto, the drive member20and, in particular, the rotation member21are rotatable around a rotation axis which runs obliquely with respect to the axis along which the piston rod12is displaced (displacement axis). The rotation axis (cf. axis A inFIG. 14) may run transversally, in particular perpendicularly, with respect to the displacement axis and, in particular, with respect to a main direction of extent of the piston rod12.

Drive member20and rotation member21may be retained by an axis member50, which may extend through rotation member21and drive member20. Axis A may run along axis member50. Axis member may secure drive member and rotation member against displacement with respect to the housing. Stop member26may be integrated into housing13. Of course, stop member26may also be embodied as a separate element. Axis member50may extend through stop member26.

Drive member20comprises an outer toothing51. Teeth of the outer toothing51may extend radially away from rotation axis A. Drive member may be a toothed gear sleeve. The piston rod12is expediently provided with an outer toothing52. The outer toothing52of piston rod12and the outer toothing51of the drive member20are arranged to engage one another. The outer toothing52of piston rod12and the outer toothing51of the drive member20may be permanently engaged. When the drive member20and the rotation member21rotate together in the second direction with respect to the housing13, the piston rod12is also displaced in the distal direction with respect to the housing. The piston rod does not rotate while it is displaced in the distal direction with respect to the housing.

The piston rod12may be supported against deviation in the radial direction with respect to the displacement axis, for example by means of housing part17through an opening53in which the piston rod may extend.

In contrast to the previously described embodiments, the dose member34and the rotation member21are not threadedly engaged. Rather, rotation member21and dose member34are connected/coupled to one another via a lever mechanism. The lever mechanism is adapted to convert movement of the dose member34with respect to the housing in the proximal direction into rotational movement of the rotation member in the first direction with respect to the housing and movement of the dose member34with respect to the housing in the distal direction into rotational movement of the rotation member in the second direction with respect to the housing.

Drive member20is prevented to rotate during setting of the dose on account of the stop member26preventing rotational movement of the drive member in the first direction.

The lever mechanism may comprise a lever55. Lever55is preferably secured against rotational movement with respect to rotation member21and preferably against (simultaneous) translational movement with respect to rotation member21. Preferably, lever55is formed unitary with rotation member21. Lever55is pivotally around the rotation axis in the first direction during dose setting and in the second direction during dose delivery.

Dose member34may, preferably at its distal end, comprise an engagement member54, e.g. a pin, for engagement with the lever55. Engagement member54may engage the lever55, in particular an opening56, preferably an elongate opening56within lever55.

Stop member26prevents rotational movement of the drive member in the first direction during dose setting as described previously.

FIG. 16shows a schematic sectional view of a part of a resettable drive mechanism according to an embodiment in a delivery state.FIG. 17shows the resettable drive mechanism ofFIG. 16in a reset state.

The drive mechanism may correspond to the one described in conjunction withFIGS. 2 to 9. However, a reset mechanism for a drive mechanism as it is described in more detail below may also be provided for in the remaining drive mechanisms as described above.

The drive mechanism described in conjunction withFIGS. 15 and 16is a resettable drive mechanism. For this purpose, the drive mechanism comprises a reset mechanism. The reset mechanism may be switched between a reset position and a delivery position.

In contrast to the drive mechanism described in conjunction with the previous figures, the rotation member21is not shown inFIGS. 16 and 17. However, a rotation member may nevertheless be provided.FIGS. 16 and 17only show a half of a section through the drive mechanism. The additional cut was made along piston rod12.

As shown inFIG. 16, in the delivery state, drive member20and stop member26are engaged with one another such that rotational movement of the drive member20with respect to housing13in the first direction is prevented and rotation of the drive member20in the second direction, opposite to the first direction, is allowed. Toothings27and28may be provided for this purpose as described further above.

Resilient member31exerts a force acting in axial direction on stop member26, said force tending to keep the stop member and the drive member engaged. Resilient member31may be arranged to keep stop member in engagement and, in particular, in abutment with drive member20in the delivery state. The (biased) resilient member31may be supported by and, preferably, bear against bearing member57. Bearing member may be support48ofFIG. 6, for example. Bearing member57is expediently secured against rotational movement and displacement with respect to housing13.

Rotation of the drive member20in the second direction may cause the piston rod12to be displaced in the distal direction with respect to housing13. The piston rod13may rotate and translate in the distal direction with respect to the housing for dose delivery as described in conjunction withFIGS. 2 to 10. Alternatively, the piston rod may be moved in the distal direction with pure translatory movement (not explicitly shown, cf. a drive mechanism according toFIGS. 11 to 15). The drive member20may engage the piston rod12. The drive member20may be splined to the piston rod12. Preferably, there is no relative rotational movement possible between piston rod12and drive member20. Also, the drive member20preferably cannot be rotated in the first direction on account of the (permanent) interlocking of the drive member20and the stop member26when the reset mechanism is in the delivery state.

Thus, when the drive mechanism is in the delivery state, movement of the piston rod12in the proximal direction with respect to housing13to a starting position is prevented, because the stop member26prevents rotation of the drive member20in the first direction and the drive member has to be rotated in the first direction, if the piston rod12was to be moved in the proximal direction with respect to the housing13into the starting position.

However, after a cartridge4has been emptied, i.e. after a distal end position of the piston10and, in particular, of the piston rod12has been reached, the piston rod has to be moved in the proximal direction back into a proximal starting position in order to allow the drive mechanism to be reused. Expediently, the drive mechanism is configured to be switchable from the delivery state to a reset state. In the reset state, the piston rod12may be moved in the proximal direction with respect to the housing, for example by a user screwing and/or pushing the piston rod12in the proximal direction.

The drive mechanism comprises a clutch member58. Clutch member58is movable with respect to housing13, preferably displaceable with respect to the housing, between a delivery position D and a reset position R. The clutch member58may be moved back and forth between the delivery position and the reset position. The reset position may be arranged in the distal direction as seen from the delivery position. The clutch member58may be a sleeve. Piston rod12may extend through clutch member.

In the delivery position, drive member20and stop member26are engaged. In the reset position, drive member20and stop member26are disengaged (cf. the encircled region59inFIG. 17). Thus, when the clutch member58is in the reset position, the drive member may be rotated in the first direction with respect to the housing13without the stop member26preventing the rotation. Consequently, the piston rod12may be moved in the proximal direction, e.g. by rotation with respect to the housing and on account of a threaded engagement to the housing, due to the drive member20and the stop member26being disengaged.

The clutch member58may comprise a protrusion61. Protrusion61may protrude radially and preferably inwardly from a base portion66of the clutch member58. The base portion may extend in the axial direction. Protrusion61may be arranged to move the drive member20and the stop member26out of engagement when the clutch member is moved towards reset position R. Protrusion61may be provided at or near the proximal end of the clutch member58. A distal end face of protrusion61of clutch member58may be arranged to couple to and preferably to abut a proximal face of stop member26.

The reset mechanism furthermore comprises a clutch resilient member60, for example a clutch spring member, like a coil spring and/or a compression spring, for example.

The clutch member58may extend along drive member20, stop member26, resilient member31, bearing member57and/or clutch resilient member60. The clutch member58may be rigid. The clutch member58may have a constant length.

Clutch resilient member60may be biased when the clutch member58is in the delivery position. Biased clutch resilient member may exert a force on the clutch member that tends to move the clutch member in the reset position. Clutch resilient member60may bear on bearing member57, in particular on a distal face thereof.

Clutch member58may comprise a (additional) protrusion62. Protrusion62may protrude radially and preferably inwardly from the base portion66of the clutch member58. Protrusion62may be arranged in the region of the distal end of the clutch member58. Protrusion62may be arranged to be abuttable by and is preferably abutted by clutch resilient member60. Clutch resilient member60may be supported by and, in particular, bear on a proximal face of protrusion62.

The clutch resilient member60is arranged to exert a force on the clutch member58which force tends to move the clutch member58in the reset position R. When the drive mechanism is in the delivery state, this force is counteracted by a clutch stop member63. Accordingly, in the delivery state, clutch member58may be held in the delivery position by the clutch stop member63.

In the delivery state, clutch stop member63is preferably secured against displacement with respect to the housing13. Clutch stop member63may be arranged to abut clutch member58. A proximal end face of the clutch stop member63may abut a distal end face of the clutch member58in the delivery state.

For resetting the device, the clutch stop member63may be moved, for example removed, so as to allow the clutch member to move into the reset position. Thereupon, biased clutch resilient member60which exerts the force, which is no longer compensated by clutch stop member, on clutch member58. The force automatically tends to move clutch member58in the reset position R. The clutch member58may abut stop member26. Stop member26may tend to follow movement of the clutch member towards the reset position R.

In order to get into reset position the force exerted by the resilient member31on the stop member26, which force tends to hold drive member20and stop member26in engagement, has to be overcome. Thus, the force moving the clutch member58towards the reset position R has to be greater than the force exerted by the resilient member31. The force for moving and, in particular, holding the clutch member58in reset position R may be provided for by clutch resilient member60. It is expedient for the resilient member31and the clutch resilient member60to be embodied as a spring member, respectively. Clutch resilient member60, in this case, preferably has a spring strength greater than the one of resilient member31in order to overcome the force exerted by resilient member31.

The clutch stop member63is expediently formed in the cartridge unit, for example, by the cartridge4or the cartridge retaining member11. Thus, if the cartridge unit is detached from the housing13for replacing an empty cartridge, the clutch member58is moved, preferably automatically, towards and into the reset position and preferably held in the reset position.

The distance by which the clutch member58moves with respect to the housing13when moving from delivery position into reset position is preferably chosen to be great enough to disengage toothings27and28.

The clutch member58is expediently secured to the drive mechanism in order to avoid the clutch member falling out of the housing. For this purpose, the clutch member may abut a proximal face of the stop member26.

As shown inFIG. 17, when the clutch member58is in reset position R, the drive mechanism is in the reset state and the piston rod12may be moved in the proximal direction with respect to the housing from a distal end position back into a proximal starting position. When a new cartridge4is attached to the housing13, after the piston rod12was moved back into starting position, clutch member58may be moved into the distal direction back into delivery position together with the cartridge4and, if present, the cartridge retaining member11, thereby moving drive member20and stop member26again into engagement.

Accordingly, the medication delivery device may be reused. As an element of the cartridge unit like cartridge4or cartridge retaining member11may serve as the clutch stop member63, the reset mechanism may automatically and, in particular (purely) mechanically, decouple stop member26and drive member20, when the cartridge unit2is detached from the drive unit3(cf.FIG. 1). Thus, the only action required by a user is to move, e.g. screw and/or push, the piston rod12back into the starting position before a new cartridge unit2may be attached to the drive unit3. The drive mechanism is thus easily reusable.

The reset mechanism described herein above may be implemented easily and requires only a small amount of additional parts such as compared to the corresponding non-resettable drive mechanism. In particular, such as compared to the first embodiment, only two additional parts—clutch member and clutch resilient member—are required for the automatic reset mechanism.

As the reset mechanism may be an automatic one, no external action is required for disengaging stop member and drive member. Thus, the clutch member may be retained in the housing and, in particular, inaccessible from the outside.

Of course, the reset mechanism may be implemented as a manual, non-automatic mechanism. It is expedient, in this case, to configure the movement of the clutch member to be externally actuable.

In contrast to the situation depicted inFIGS. 16 and 17, the clutch member58may be (partly) arranged outside of the housing. The housing may be provided with one or more openings through which the clutch member may extend from the outside to the inside of the housing. This is particularly expedient for a non-automatic reset mechanism.

With the (resettable) drive mechanisms described herein above a good dose accuracy may be achieved. The drive mechanisms are particularly suitable for dispensing doses of the medication from and including 1 IU up to and including 30 IU, preferably from and including 3 IU up to and including 20 IU. Also, doses of 30 IU or more or 1 IU or less may be dispensed by means of the described drive mechanisms. However, doses of from and including 1 IU up to and including 30 IU are particularly suitable. For example, if a device described in conjunction withFIGS. 1 to 10, in which the piston rod rotates during displacement, was to be designed for doses less than 1 IU, the thread of the piston rod should have a low pitch and/or the number of teeth of the respective toothing of drive member and rotation member should be increased. Of course, the production costs may increase on account of the finer segmentation of the toothings and the lower pitch thread. In order to provide for a device configured to deliver doses greater than 30 IU, e.g. 50 IU or greater, the thread in the piston rod should have a higher pitch. Consequently, small deviations from a predetermined course of the thread result in major absolute deviations from the desired dose. Thus, the risk of a reduction in dose accuracy may be increased. In addition, the risk of self-locking of a threaded engagement may be increased.

A diameter of the (outer) housing of the medication delivery device may be less than or equal to 20 mm, preferably less than or equal to 16 mm, particularly preferably less than or equal to 14 mm.

A first aspect of the invention provides a resettable drive mechanism for a medication delivery device (1), comprising:

a housing (13,17,40) with a proximal end and a distal end,

a drive member (20) rotatable with respect to the housing in a second direction for delivering a dose of a medication,

a piston rod (12) adapted to be driven in a distal direction with respect to the housing by the drive member, when the drive member rotates in the second direction,

a stop member (26) adapted to prevent rotation of the drive member in a first direction opposite to the second direction with respect to the housing, when the stop member engages the drive member, and

a clutch member (58) movable with respect to the housing between a delivery position (D) and a reset position (R), wherein,

when the clutch member is in the delivery position, the stop member and the drive member are engaged and the drive member is prevented from rotating in the first direction with respect to the housing, and

when the clutch member is in the reset position, the drive member and the stop member are disengaged, the drive member is rotatable in the first direction with respect to the housing and the piston rod is movable in the proximal direction with respect to the housing.

A second aspect provides a drive mechanism according to the first aspect, wherein the drive member (20) engages the piston rod (12).

A third aspect provides a drive mechanism according to the first or second aspect, wherein the drive mechanism comprises a clutch resilient member (60) which is arranged to exert a force on the clutch member (58) which force tends to move the clutch member in the reset position (R) when the clutch member is moved towards the delivery position (D) or is in the delivery position.

A fourth aspect provides a drive mechanism according to the third aspect, wherein the drive mechanism comprises a removable clutch stop member (63) that is arranged to counteract the force, thereby preventing the clutch member (58) from moving in the reset position (R).

A fifth aspect provides a drive mechanism according to any one of the first through fourth aspects, wherein the drive mechanism comprises a resilient member (31) which exerts a force on one of or both of the drive member (20) and the stop member (26) which force tends to keep the drive member and the stop member in engagement.

A sixth aspect provides a drive mechanism according to the third and fourth aspects, wherein the clutch resilient member (60) is a clutch spring member and the resilient member (31) is a spring member, the clutch spring member having a spring strength which is greater than a spring strength of the spring member.

A seventh aspect provides a drive mechanism according to any one of the first through sixth aspects, wherein the drive member (20) and the stop member (26) are engaged to form a unidirectional friction clutch mechanism when the clutch member is in the delivery position (D).

An eighth aspect provides a drive mechanism according to any one of the first through seventh aspects, wherein the stop member (26) is secured against rotational movement with respect to the housing (13,17,40) and the stop member is displaceable with respect to the housing.

A ninth aspect provides a drive mechanism according to any one of the first through eighth aspects, wherein the stop member (26) is arranged to follow movement of the clutch member (58) towards the reset position (R), thereby disengaging from the drive member (20).

A tenth aspect provides a drive mechanism according to any one of the first through ninth aspects, wherein the clutch member (58) is arranged to abut the stop member (26) when the clutch member is moved towards the reset position (R).

An eleventh aspect provides a medication delivery device (1) comprising a resettable drive mechanism according to any one of the first through tenth aspects, and a cartridge (4) for holding a medication (5), the cartridge being releasably attached to the housing (13,17,40).

A twelfth aspect provides a medical delivery device according to the eleventh aspect, with a drive mechanism according to the fourth aspect, wherein the cartridge (4) or a cartridge retaining member (11) is the clutch stop member (63).

Of course, the invention is not restricted by the embodiments described above.

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