Abstract:
The present invention relates to a medicament delivery device comprising a housing ( 10,12 ), capable of containing a medicament container ( 14 ), a plunger rod ( 18 ) and a drive member ( 34 ) arranged to said plunger rod and capable of acting on said plunger rod ( 18 ) for moving it in the proximal direction of the device for expelling a dose of medicament from said medicament container ( 14 ), a dose and drive setting mechanism ( 52 ) comprising a dose setting member ( 56 ) operably connected to a force member ( 82 ) such that setting of a dose causes said force member ( 82 ) to be energized. The intermediate member ( 68 ) is configured to interact with a dose setting sleeve ( 50 ) through a first unidirectional connection ( 64, 62 ), configured to interact with said drive member ( 34 ) through a second unidirectional connection ( 70, 72 ), and configured to interact with a dose drive sleeve ( 76 ) through a third connection ( 74,78 ).

Description:
TECHNICAL FIELD 
     The present invention relates to a medicament delivery device and in particular to a device with which a certain dose of medicament to be delivered may be set prior to dose delivery. 
     BACKGROUND OF THE INVENTION 
     There are a number of medicament delivery devices on the market that are capable of delivering a certain prescribed dose that has been set by the user before dose delivery. This feature of the medicament delivery devices is practical in many instances because the same type of medicament delivery device may be used for different types of drugs, for patients with different needs and thus for different dose sizes such as for children or for adults and/or for medicament administration schemes that vary over time. Instead of having specific designs delivering certain fixed dose amounts, a certain dose may be set by the patient directly before dose delivery. The feature of setting specific doses is also practical with multi-dose injection devices, which are capable of delivering a number of specified, set, doses until the compartment is empty. One example is disclosed in the European patent application publication EP1218042, where specific doses can be set before injection by turning a dose setting button on the distal end of the injector. 
     If however a dose is set too high, i.e. the user overshoots the desired dose, the device has to be reset so that a user may set the proper dose. According to EP1218042 this is done by continuing the rotation of the dose setting knob until it is moved past the maximum value, past which the dose setting knob is released. It is then possible to rotate back the dose setting knob to the initial, or zero, position, at which position the dose setting knob is re-connected to the dose setting mechanism. 
     A clear drawback with the solution according to EP1218042 is that if the dose is overshot, the dose knob has to be rotated the whole way to the end position and then rotated back to the zero position, and then again turned to the desired dose. Thus, if a dose setting is missed a lot of rotation is required in order reset the device and set the dose. Further, the design requires a substantial number of interacting components in order to achieve the desired function. 
     There is thus room for improvements regarding this type of medicament delivery device. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The aim of the present invention is to remedy the drawbacks of the state of the art medicament delivery devices. 
     The device according to the invention utilizes a dose and drive setting mechanism comprising an intermediate member or component, i. e. a member that may transfer movements and functions between different components that are arranged to set and re-set a dose of medicament as well as components that are arranged to deliver a set dose. 
     The dose and drive setting mechanism may further comprise a dose setting assembly operably connected to a force member. The components of the dose setting assembly that may be utilized to set and reset a dose may comprise among others a dose setting member comprised in a dose and drive setting mechanism accessible on the device by a user. Preferably the dose setting member may be rotated in a certain direction in relation to the device in order to set a dose and more preferably rotated in a particular direction around a longitudinal axis in order to set a dose. In one embodiment of the invention the dose setting member comprises a dose setting knob located at a distal end of the device. The dose setting assembly may further comprise a dose setting sleeve fixedly connected to said dose setting member, and a dose drive sleeve coaxially arranged on said dose setting sleeve and operably connected to said force member. 
     The function of the force member is to be energized, where the energy from the force member is utilized to expel a dose of medicament from a medicament container that is contained in the medicament delivery device. 
     The dose setting assembly may preferably be operably connected to said force member via the intermediate member such that when a dose is set by a user, the force in the force member is increased. The intermediate member may thus be positioned operatively to transform movement from the dose setting member to the force member such that when a dose is set by for example by rotating the dose setting knob in one direction, the force of the force member is increased. According to a preferred solution, the connection between the dose setting sleeve and the intermediate member may constitute a first unidirectional connection. 
     The first unidirectional connection may be capable of transferring movement from said dose setting member to said force member via said intermediate member in one direction for setting a dose and energizing said force member. The first unidirectional connection may comprise a first ratchet connection. Preferably the first ratchet connection comprises wedge-shaped teeth having a certain inclination α and a certain tooth height h 1 . 
     The force member may be a tensioning member such as a spring force member. The spring force member may comprise a constant force spring or a compression affected spring force member which may comprise a spiral compression spring, a plate compression spring for example. More preferably the spring force member may comprise a torsion affected spring means which may comprise a spiral spring means that may be twisted along its longitudinal axis, a wound flat band clock spring as a constant force spring or a variable force spring for example. 
     The components that may be utilized to deliver a dose may comprise a plunger rod that preferably is arranged to be movable in the longitudinal direction of the device. The plunger rod is preferably positioned such that it may act, when moving, on a stopper arranged movable inside a medicament container, whereby the movement of the stopper may cause a dose of medicament to be delivered from the medicament container. In this context, a suitable dose delivery member may be arranged to the medicament container, through which medicament delivery member the dose of medicament may be expelled. 
     According to one feasible solution, the plunger rod may be arranged with threads on its outer surface, which threads are designed to cooperate with a drive member. According to one feasible solution, the plunger rod cooperates with stationary fixed threads so that the plunger rod is forced to rotate by the drive member in order to move the plunger rod in the longitudinal direction for acting on the stopper of the medicament container. 
     According to a preferred solution the plunger rod is arranged to be locked against rotation, but being movable linearly, and that a drive member comprises a drive nut that is forced to rotate by said force member, thereby acting as the plunger rod driver, in order to move the plunger rod in the longitudinal direction for acting on the stopper of the medicament container. 
     According to the invention, the intermediate member is arranged to cooperate with said force member in order to transfer a torque force to said drive member in order to move said plunger rod for delivering a dose of medicament. According to one preferred embodiment, the drive member is a drive nut where a connection is established between the intermediate member and the drive member. According to one preferred solution, the connection constitutes a second unidirectional connection, which is arranged such that it transforms movement from the force member to the drive member via the intermediate member. 
     The second unidirectional connection may comprise a second ratchet connection. Preferably the second ratchet connection comprises wedge-shaped teeth having a certain inclination β and a certain tooth height h 2 . 
     According to one aspect, the second unidirectional connection is arranged to allow relative movement between the intermediate member and the drive member when said intermediate member is moved by said dose setting member for setting a dose and for energizing said force member. Said second unidirectional connection is also arranged to prevent movement of the intermediate member in an opposite direction, thereby holding said force member in the energized state. 
     According to a particular aspect of the invention, the intermediate member may be positioned operatively to transform movement from the dose setting member to the force member such that when a dose is set by rotating the dose setting member in a second direction the force of the force member is decreased, such as for decreasing the size of a set dose or to reset the whole device. The second direction may be the opposite direction, as to when the force of the force member is increased. The dose setting member may then be used both for increasing the force and setting a dose as well as decreasing the force and resetting a dose. 
     For this purpose, the first and second unidirectional connections may cooperate such that when the dose setting member is operated in the opposite direction, the first unidirectional connection may be designed and arranged to be able to disconnect said second unidirectional connection. Thereby the intermediate member is free to move, and thereby the force member, whereby the force will be reduced. 
     According to a preferred solution of the invention, the inclination α of the first ratchet connection may be chosen larger than the inclination β of the second ratchet connection. Also the tooth height h 1  of the first ratchet connection may be chosen larger than the tooth height h 2  of the second ratchet connection. 
     Thereby, when the dose setting member is rotated in the opposite direction and relative the intermediate member, the teeth of the first ratchet connection will slide on each other, whereby the teeth of the second ratchet connection will be moved out of engagement with each other, because of the lesser height. 
     According to a preferred solution, the connection between the dose drive sleeve and the intermediate member may constitute a third connection. According to one solution, this third connection enables a relative movement in a longitudinal direction between the intermediate member and the force member. This in turn facilitates the disconnection of the second unidirectional connection by said first unidirectional connection, and in particular when ratchet connections are utilized. 
     A preferable solution of the third connection may be to utilize wedge-shaped teeth that cooperate with surfaces inclined in relation to the longitudinal direction. By this design, any force from the force member will cause the intermediate member to be forced in a longitudinal direction as well as a rotational direction. The movement in the longitudinal direction may then force the second ratchet connection in re-engagement when the teeth of the first ratchet connection have come to a subsequent meshing position when resetting the dose. Further, the design of the third connection will ascertain a force from the force member on all components, including both first and second unidirectional connections, such that a good and stable contact is obtained in any event. 
     The device according to the invention may further comprise an activation mechanism that may be operably connected to said drive member for releasing said force member. The activation mechanism may comprise a manually operated activation member accessible on the device. The manually operated activation member may be movable in relation to the housing of the device. The activation member may be a component that is moved when the device is moved in contact with a dose delivery site. This may for example comprise a needle guard or needle shield, when a dose delivery member is an injection needle, which may be positioned at a proximal end of the device. Preferably the activation member may comprise a button that is moved generally linearly in relation to the housing of the device such as a sliding button. 
     These and other aspects of and advantages with the present invention will become apparent from the following detailed description of the invention and from the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following detailed description of the invention, reference will be made to the accompanying drawings, of which 
         FIG. 1  is a perspective view of a medicament delivery device that may comprise the present invention, 
         FIG. 2  is a cross-sectional side view of the embodiment of  FIG. 1 , 
         FIG. 3  is an exploded view of the device of  FIG. 1 , 
         FIG. 4  is a detailed view of the dose and drive setting mechanism, 
         FIG. 5  is an exploded view of a dose and drive setting mechanism comprised in the device of  FIG. 1 , 
         FIG. 6  is an exploded view corresponding to  FIG. 5  but turned 180°, 
         FIG. 7  is a detailed cross-sectional view of the dose and drive setting mechanism of  FIG. 5 , 
         FIG. 8  is a detailed view of first and second ratchet connections comprised in the present invention, 
         FIG. 9  is a detailed exploded view of components comprised in the present invention 
         FIG. 10  is a detailed view of the dose and drive setting mechanism, 
         FIGS. 11 to 13  show detailed views of different functional states of the present invention, and 
         FIGS. 14   a  and  b  show detailed views of interaction between two components comprised in the dose setting mechanism of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the present application, when the term “distal part/end” is used, this refers to the part/end of the injection device, or the parts/ends of the members thereof, which under use of the injection device is located the furthest away from the medicament injection site of the patient. Correspondingly, when the term “proximal part/end” is used, this refers to the part/end of the injection device, or the parts/ends of the members thereof, which under use of the injection device is located closest to the medicament injection site of the patient. 
     The device shown in the drawings comprises a proximal housing part  10  and a distal housing part  12 ,  FIG. 1 . The proximal housing part  10  is arranged and designed to accommodate a medicament container  14 ,  FIG. 2 . The proximal end of the medicament container  14  is arranged to fit into a neck  16 ,  FIG. 2 , at the proximal end of the proximal housing part  10 . A medicament delivery member  17 , such as an injection needle, a nasal or mouth piece, a nozzle or the like, may be adapted to be connected to the neck  16  for delivering a dose of medicament. The connection may comprise a number of attachment members such as threads, bayonet connections, luer-locks, just to mention a few. 
     An elongated plunger rod  18 ,  FIG. 3 , is provided with threads  20 ,  FIG. 5 , on its outer surface and having a proximal end in contact with a stopper  22 ,  FIG. 2 , movably arranged inside the medicament container  14 . The plunger rod  18  is further provided with longitudinally extending grooves  24 ,  FIG. 5 , which are arranged to cooperate with radially inwardly extending ledges  26  on a guide member  28  arranged fixed to the housing. The guide member could either be an integral part of the housing or a component that is locked or held stationary in relation to the housing. 
     The threaded plunger rod  18  is cooperating with corresponding threads  30  arranged in a central passage  32  of a generally cylindrically shaped drive nut  34 ,  FIG. 5 . The drive nut  34  is arranged with a number of longitudinally directed ledges  36 , which ledges  36  are comprised in an activation mechanism  38 ,  FIG. 4 . 
     The activation mechanism  38  further comprises a generally tubularly shaped lock and release member  40 ,  FIG. 4 , through which the drive nut  34  extends and provided with corresponding ledges  42  on an inwardly facing surface, which ledges are arranged to cooperate with the ledges  36  of the drive nut  34  to rotationally lock the drive nut  34  in relation to the lock and release member  40 . Further the activation mechanism  38  comprises an activation member  44  in the form of a plate arranged slidable on the outer surface of the distal housing part  12 . A support  46 ,  FIG. 4 , is attached to the activation member  44 , extending through an opening in the housing and being attached to the lock and release member  40 . 
     A distal part of the drive nut  34  is arranged with a central tubular recess  48 ,  FIG. 7 , into which a dose setting sleeve  50  of a dose and drive setting mechanism  52  is arranged, shown in  FIGS. 5 and 6 . The dose setting sleeve  50  comprises a generally tubular body having a proximal end part fitting into the recess  48  of the drive nut  34 , whereby the plunger rod  18  is positioned inside, and extending through, the dose setting sleeve  50 . A distal end of the dose setting sleeve  50  is arranged with an attachment post  54 . 
     The dose and drive setting mechanism  52  is further arranged with a dose setting member  56 ,  FIGS. 5 and 6 , in the form of a knob rotatably arranged at the distal end of the distal housing part  12  and accessible by a user. The dose setting member  56  is provided with an elongated shaft  58 ,  FIGS. 5 and 6 , extending in the proximal direction, where the proximal end of the shaft  58  is arranged with an attachment member of corresponding configuration of the attachment post  54  of the dose setting sleeve  50  so as to connect the two, whereby, when a user rotates the dose setting member  56 , so does the dose setting sleeve  50 , as will be described below. 
     Further the dose setting sleeve  50  is arranged with a generally cup-shaped member  60 ,  FIGS. 5 and 6 , attached to or made integral with, the dose setting sleeve  50 , and where the edge of the cup-shaped member  60  is facing a distal direction. The edge of the cup-shaped member  60  is further arranged with a number of wedge-shaped teeth  62 ,  FIG. 8 , of a first unidirectional connection comprising a first ratchet connection, where the distal surfaces of the teeth  62  have an inclination α,  FIG. 8 , in relation to a plane normal to the longitudinal direction of the device. The teeth also have a certain height h 1 ,  FIG. 8 . 
     The first ratchet connection further comprises a set of circumferentially extending wedge-shaped teeth  64  arranged on a proximally directed ledge surface of a circumferential ledge  66  of an intermediate member  68 ,  FIG. 8 , comprised in the dose and drive setting mechanism  52 ,  FIGS. 5 and 6 . The set of wedge-shaped teeth  64  have the same number of teeth, the same inclination α and the same height h 1  as the teeth  62  of the cup-shaped member  60  of the dose setting sleeve  50 , whereby they cooperate with each other as will be described. 
     The intermediate member  68  is arranged with a central passage with a diameter somewhat larger than the outer diameter of the dose setting sleeve  50 , whereby the latter passes through the intermediate member  68 . On the ledge  66  of the intermediate member  68  and outside of the set of teeth  64  of the first ratchet connection as seen in the radial direction is a second set of wedge-shaped teeth  70  of a second ratchet connection,  FIG. 8 , which second set of wedge-shaped teeth  70  have a certain number of teeth, a certain inclination β in relation to a plane normal to the longitudinal direction of the device and a certain tooth height h 2 ,  FIG. 8 . 
     The second set of teeth  70  cooperate with a set of teeth  72  on a distally directed surface of the drive nut  34 ,  FIG. 8 , having the same inclination β and tooth height h 2 , whereby they cooperate with each other as will be described. 
     A distally directed ledge surface of the intermediate member  68  is further arranged with a distally directed circumferential set of wedge-shaped teeth  74  comprised in a third connection,  FIG. 9 , having an inclination γ in relation to a plane normal to the longitudinal direction of the device. Further, the dose and drive setting mechanism  52  comprises a dose drive sleeve  76 ,  FIGS. 5 ,  6 ,  9 , having a generally tubular shape and being positioned coaxially outside and surrounding the dose setting sleeve  50  as seen in the radial direction, where the dose drive sleeve  76  is rotatable in relation to the dose setting sleeve  50 . The dose drive sleeve  76  is provided with a proximally directed end surface, which surface is provided with circumferential set of wedge-shaped teeth  78 ,  FIG. 9 , which set of wedge-shaped teeth  78  have the same number of teeth and the same inclination γ as the distally directed teeth  74  of the intermediate member  68 , whereby they cooperate with each other as will be described. 
     The dose drive sleeve  76  is further arranged with an attachment member  80  at a distal end thereof,  FIG. 9 . A spring force member  82 ,  FIGS. 5 and 6 , shown in the form of a clock spring, is attached with an inner end to the attachment member  80  of the dose drive sleeve  76 . An outer end of the spring force member  82  is attached to a point fixed in relation to the distal housing part  12  of the device. 
     The dose drive sleeve  76  is further arranged with thread segments  84 ,  FIG. 10 , on its outer surface, which thread segments  84  cooperate with internal threads on a dose indication nut  86 , such that rotation of the dose drive sleeve  76  causes the dose indication nut  86  to move linearly in the longitudinal direction of the device. The dose indication nut  86  is further provided with attachment means  88 ,  FIG. 10 , for attaching suitably position sensor (not shown), which position sensors are arranged to cooperate with corresponding indicators positioned on e.g. a printed circuit board (not shown). 
     The device is intended to function as follows. 
     Dose Setting 
     When the user is to take a dose of medicament from the device a preferred and prescribed dose size is to be set. The user then activates the dose and drive setting mechanism  52 , whereby he/she turns the dose setting member  56 , whereby its shaft  58  also is turned, and due to the connection with the dose setting sleeve  50 , the latter is also turned. Because the cup-shaped member  60  is attached or integral to the dose setting sleeve  50 , it is also turned. The configuration of the wedge-shaped teeth  62  of the cup-shaped member  60  and the wedge-shaped teeth  64  of the intermediate member  68  of the first ratchet connection causes the intermediate member  68  to be brought along and rotated together with the dose setting sleeve  50 . 
     Further, the distally directed teeth  74  of the intermediate member  68  are configured such with the teeth  78  of the dose drive sleeve  76  that the dose drive sleeve  76  is brought along and rotated when the intermediate member  68  is rotated. Because the inner end of the spring force member  82  is attached to the dose drive sleeve  76 , the spring force member  82  will now be tensioned when the dose drive sleeve  76  is rotated. Also, during the turning of the intermediate member  68 , the second set of proximal teeth  70  of the second ratchet connection are configured such in relation to the cooperating teeth  72  of the drive nut  34  such that the inclined surfaces of the teeth slide in relation to each other in this direction,  FIG. 11 , because the drive nut  34  is locked due to the interconnection between its ledges  36  and the ledges  42  of the lock and release member  40  of the activation mechanism  38 ,  FIG. 11 . However, the intermediate member  68  is prevented from being rotated back due to the configuration of the wedge-shaped teeth of the second ratchet connection. Thus the spring force member  82  is held tensioned by the dose and drive setting mechanism  52  after operation of the dose setting member  56 . Further, the intermediate member  68  is forced in the proximal direction as indicated by arrow A 68  of  FIG. 14   b , ensuring a safe connection between the intermediate member  68  and the drive nut  34  due to the force from the spring member acting to turn the dose drive sleeve  76  as indicated by arrow A 76 ,  FIG. 14   b , providing a force F 76  on the third connection between the proximally directed teeth  78  of the dose drive sleeve  76  acting with its inclined surfaces on the inclined surfaces of the distally directed teeth  74  of the intermediate member  68 . 
     Further the turning of the dose drive sleeve  76  causes the dose indication nut  86  to move linearly in the longitudinal direction of the device due to the threaded connection between the dose drive sleeve  76  and the dose indication nut  86 . The sensors will then move along the indicators, whereby information may be obtained as how far the dose indication nut has moved, which distance corresponds to a certain dose of medicament to be delivered. This certain dose may be displayed to the user in any appropriate way known to the person skilled in the art. 
     Dose Delivery 
     The device is now ready to deliver a dose of medicament. The user then operates the dose activation mechanism  38 . This is done by sliding the activation button  44  in the longitudinal direction in relation to the housing,  FIG. 12 . This causes the ledges  42  of the lock and release member  40  to be moved out of contact with the ledges  36  of the drive nut  34 ,  FIG. 8 , whereby the latter is free. The connection of the second ratchet connection with the wedge-shaped teeth  72  of the drive nut  34  and the teeth  70  of the intermediate member  68  are arranged such that the intermediate member  68  will rotate the drive nut  34 ,  FIG. 12 , this in turn due to the connection between the distally directed wedge-shaped teeth  74  of the intermediate member  68  cooperating with the teeth  78  of the dose drive sleeve  76  and since the spring force member  82  is tensioned and acting on the dose drive sleeve  76 , the spring will force the dose drive sleeve  76  to rotate. Thus, the drive nut  34  will rotate by the force of the spring force member  82  and due to the threaded connection between the drive nut  34  and the plunger rod  18 , the latter will be moved in the proximal direction linearly due to the ledges  26  of the guide member  28  fitting into the longitudinal grooves  24  of the plunger rod  18 , thereby preventing rotation of the plunger rod  18 . The movement of the plunger rod  18  in the longitudinal direction will cause the stopper of the medicament container  14  to be moved in the proximal direction, whereby a dose of medicament will be delivered. 
     Resetting of a Set Dose 
     If the user for some reason wishes to reduce the set dose, either if set too high or the device should be reset to zero, the user activates the dose and drive setting mechanism  34  by turning the dose setting member  56  in the opposite direction as to the setting direction. This will then cause the dose setting sleeve  50  to rotate and thus also the cup-shaped member  60  indicated by arrow I in  FIG. 13 . 
     The drive nut  34  has been moved to the left in the figure for clarity. The actual position of the drive nut is indicated by broken lines with reference numeral  34 ′. 
     The teeth  62  of the first ratchet connection on the cup-shaped member  60  will now slide with their inclined surfaces on the inclined surfaces of the teeth  64  of the intermediate member  68 ,  FIG. 13 . This action will cause the intermediate member  68  to be moved in the distal direction indicated by arrow II in  FIG. 13 . The movement of the intermediate member  68 , as also indicated by arrow A 68  in  FIG. 14   a , is facilitated by the third connection, where the inclined surfaces of the distally directed teeth  74  slide on the inclined surfaces of the teeth  78  of the dose drive sleeve  76 . The movement of the intermediate member is done against the force F,  FIG. 14   a , from the spring force member  82 , also turning the intermediate member  68  somewhat. 
     The movement of the intermediate member  68  in the distal direction will cause it to be moved also in relation to the drive nut  34 , which is held fixed by the activation mechanism  38 . Due to the difference in inclination and also in height of the teeth on the intermediate member  68 , the teeth  72  of the drive nut  34  and the cooperating teeth  70  of the intermediate member  68  of the second ratchet connection, having a lesser inclination β and lesser height h 2 , will be moved out of contact with each other during the movement of the intermediate member  68  due to the interaction between the teeth  62  of the cup-shaped member  60  of the dose setting sleeve  50  and the teeth  64  of the intermediate member  68  of the first ratchet connection, having a larger inclination α and larger height h 1 . 
     When the teeth of the second ratchet connection are moved out of contact with each other, the intermediate member  68  and the dose drive sleeve  76  are free to rotate due to the force from the spring force member  82  on the dose drive sleeve  76  indicated by arrow III in  FIG. 13 , so as to reduce the tension of the spring force member  82 . However, due to the interaction between the distally directed teeth  74  of the intermediate member  68  and the teeth  78  of the dose drive sleeve  76  of the third connection, the intermediate member  68  is forced in the proximal direction again, as indicated by arrow IV and also by arrow A 68  in  FIG. 14   b , whereby the teeth of the second ratchet connection are again moved in contact with each other, locking the intermediate member  68  from rotation. In order to reduce the dose size further and thereby reduce the tension of the spring force member  82 , the user again has to perform the above mentioned turning of the dose setting member  56 . Thus for each operation by a user, the dose is reduced one increment. 
     It is to be understood that the embodiments described above and shown in the drawings are to be regarded only as non-limiting examples of the invention and that it may be modified in a number of ways within the scope of the patent claims.