Abstract:
The present invention provides an injection device and an actuator for an injection device, wherein the actuator comprises a generally rod-shaped driven member having a structured surface portion, a counter component having a structured surface portion engaging the structured surface portion of the driven member, whereby the driven member is movable by the counter component, and a spreader bushing for spreading open the counter component by a movement relative to the counter component, thereby allowing the driven member to shift freely, wherein the spreader bushing is selectively movable with and relative to the counter component.

Description:
BACKGROUND  
         [0001]    The present invention relates to an injection device for injecting fluid from a fluid container. It also relates to an actuator for such an injection device.  
           [0002]    Syringe-shaped injection devices for injecting fluids have been known for some time. They contain a bushing-shaped main body which can be screwed together at approximately the centre and can be divided into two main sections:  
           [0003]    a distal section (facing away from the patient) containing the discharge mechanism and comprising at least one rod-shaped driven member having a structured surface (e.g. a screw rod), a hollow cylindrical counter component corresponding to the driven member, provided with a structured internal sleeve (e.g. a screw nut); and  
           [0004]    a control button; and  
           [0005]    a proximal section (facing the patient) containing the fluid to be administered and a movable piston.  
           [0006]    At the proximal end of the main body, a needle and a needle holder are attached, allowing the fluid to be discharged from the device; known needles of this type are for instance needles as described in WO95/01812.  
           [0007]    The connecting member between the proximal and the distal section of the main body is the driven member, shifting the piston by the required dose in proximal direction and discharging the fluid through the needle.  
           [0008]    Often the fluid to be injected is not directly contained in the main body but in an ampoule or container, with the fluid being stored between a piercable membrane and a piston displaceable by sliding.  
           [0009]    Depending on the injection device, various features are expected from the discharge mechanism. There are devices allowing only a single discharge, devices allowing several discharges of the same dose and devices allowing freely selectable discharges.  
           [0010]    For patients using injection devices allowing a change of ampoules, it is—irrespective of the complexity of the discharge mechanism—extremely difficult to wind back the driven member to the initial position in order to make the device ready for operation after the ampoule has been changed. Devices requiring the driven member to be rewound by the control button are known from WO93/16740. Devices allowing the threaded rod to be pushed back, as in publications U.S. Pat. No. 4,592,745 and EP-A-0 554 995, are more easily operated by patients. According to these prior art devices the threaded nut is spread due to the release of the distal section from the proximal section of the main body, allowing the threaded rod to move freely without any conscious operation by the patient, with screwing together of both sections of the main body after replacement of the ampoule easily causing a premature unintentional discharge of fluid. Depending on the injection device, this could also result in an incorrect dosing which, in case of certain medication, could be extremely hazardous to the patient&#39;s health.  
           [0011]    An injection device to remedy this situation is known from applicants patent U.S. Pat. No. 6,090,080, the disclosure thereof is incorporated herein by reference. Such a known injection device is described with reference to FIGS.  14  to  19 .  
           [0012]    In the subsequent description, the terms proximal and distal are used in their usual medical sense, i.e. proximal=facing the patient and distal=facing away from the patient.  
           [0013]    As shown in FIG. 14, the injection device comprises a bushing-shaped main body  1  which can be divided into a rear (distal) section  3  containing the tubular actuating device or discharge mechanism  7  and a front (proximal) section  2  containing a replaceable ampoule  4  and a piston  5 . A needle  6  with its distal end connected to the fluid to be administered can be screwed to the proximal end of the main body  1 . The actuating device  7  comprises a control button  8 , a threaded rod  9  with a flange  19 , a guide member  24  and a driving member  11 .  
           [0014]    The tubular driving member  11  is rigidly connected to the control button  8  to prevent twisting. At the proximal end, the driving member  11  surrounds two threaded flanges  27 ,  27 ′ engaging in the thread of the threaded rod  9 .  
           [0015]    [0015]FIG. 18 shows that the threaded rod  9  comprises two level surfaces  12 ,  12 ′ and apart from that is of a circular cross section, with the circular surfaces  13 ,  13 ′ being threaded.  
           [0016]    The guide member  24  is rigidly connected to the distal section  3  of the main body  1 , thus preventing rotation or axial movement and is positioned in front of the driving member  11 . The aperture in the guide member  24 , through which the threaded rod  9  passes (FIG. 19) is of the same cross section as the threaded rod  9 —although enlarged by certain tolerances. As the guide member  24 , in contrast to the driving member  11 , is not threaded, the threaded rod  9  can be shifted through the opening of the guide member in axial direction. A rotational movement of the threaded rod  9  is therefore not possible as the guide member  24  does not allow this.  
           [0017]    The control button  8  may be moved in axial direction or may be rotated. Where the control button is activated by being pushed in proximal direction, it will simultaneously shift the driving member  11  until its front face  14  pushes against the rear face  14 ′ of the guide member.  
           [0018]    The threaded rod  9  is connected to the driving member  11  by threaded flanges  27 ,  27 ′ thus allowing any axial movement of the control button  8  to be transferred. See detailed description of threaded flanges  27 ,  27 ′ below.  
           [0019]    The axial movement is effected against the bias of a spring  16 , returning the actuating device  7  to its home position (FIG. 14).  
           [0020]    When turning the control button  8  to adjust an injection dose, the driving member  11  is also turned. This rotating movement can, however, not be transferred to the threaded rod  9  as the rod is rigidly seated in the guide member  24 . As a result of the rotating threaded flanges  27 ,  27 ′ in driving member  11 , the threaded rod  9  is rigidly driven forward via the threaded sections of the circular surfaces  13 ,  13 ′ (or backward, when reversing the rotation direction of the control button), thus bringing the flange  19  into the position required for the next injection dose to be discharged, i.e. the distance of the flange  19  from the piston  5  is respectively reduced.  
           [0021]    By pressing the control button  8 , the actuating device  7  is moved from its home position to the end position. The flange  19  pushes thereby against the piston  5  during this operation, carrying it along the set piston travel and thus discharging the pre-set volume of injection fluid through injection needle  6 . The travel of the flange  19  from the home position to the end position of the actuating device  7  always remains the same and corresponds to a constant distance by which the flange  19  is separated from the piston  5  before setting the injection dose. This process is described in detail in WO 93/16740.  
           [0022]    When the fluid container  4  is empty and the threaded rod  9  is therefore in the extreme proximal position, the threaded rod must be returned to the extreme distal position. The injection device according to the invention allows the threaded rod  9  to be returned by activation of an unlocking slide  32 .  
           [0023]    [0023]FIGS. 17 and 18 show that both threaded flanges  27 ,  27 ′ of the driving member  11  are designed as two half-shell threaded nut sections, each provided with two cams  28 ,  28 ′,  29 ,  29 ′.  
           [0024]    The unlocking slide  32  attached to the rear section  3  is connected to an internal spreader bushing  35  in the rear section  3 , with shifting of the unlocking slide  32  in distal direction causing the spreader bushing  35  to be shifted in distal direction.  
           [0025]    The spreader bushing  35  surrounds the driving member  11  and comprises four vertical tracks  30 ,  30 ′,  31 ,  31 ′ (FIG. 16), which extend towards the proximal end of the spreader bushing  35  outwardly at an angle. The tracks  30 ,  30 ′,  31 ,  31  ′ serve to accommodate the cams  28 ,  28 ′,  29 ,  29 ′ of the threaded flanges  27 ,  27 ′. When the spreader bushing  35  is in the proximal position (FIG. 14), the threaded flanges  27 ,  27 ′ surround the threaded rod  9 . When the spreader bushing  35  is moved to its distal position (FIG. 15) with the unlocking slide  32 , the threaded flanges  27 ,  27 ′ open as soon as their cams  28 ,  28 ′,  29 ,  29 ′ move over the angled section of the tracks  30 ,  30 ′,  31 ,  31 ′ and the threaded rod  9  can be freely shifted in axial direction.  
           [0026]    A notched surface  33  of the unlocking slide  32  arranged on the main body fits into a counter notched surface  34  on the proximal part of the spreader bushing  35 .  
           [0027]    In principle, the spreader bushing  35  is retained in its proximal position by the spring  16 . In order to release the threaded flange  27 ,  27 ′ the user must actively shift the unlocking slide  32  into its distal position by simultaneous pushing it down. During this process, the notched surface  33  of the unlocking slide  32  engages in the counter notched surface  34  of the spreader bushing  35 , moving it backwards. Because of this movement, the cams  28 ,  28 ′,  29 ,  29 ′ must run over corresponding outwardly extending tracks  30 ,  30 ′,  31 ,  31  ′ of the spreader bushing  35  (FIGS.  16 - 18 ). This forced movement causes the threaded flanges  27 ,  27 ′ to open (FIG. 18) and releases the threaded rod  9 . When at the same time the injection device is held with the dosing button  8  down, gravity causes the threaded rod  9  to automatically fall back into its distal position. Upon releasing the unlocking slide  32 , the spreader bushing  35  slides forward again. At the same time the cams  28 ,  28 ′,  29 ,  29 ′ slide back in the tracks  30 ,  30 ′,  31 ,  31  to their stop position in which the threaded flange  27 ,  27 ′ is closed. The unlocking slide  32  is moved into the proximal position by means that are not shown.  
           [0028]    For safety reasons, the threaded flanges  27 ,  27 ′ can only be released from the threaded rod  9  with the actuating device  7  in its proximal position (FIG. 15). For this reason the tracks  30 ,  30 ′,  31 ,  31  ′ are of such a dimension that activation of the unlocking slide  32  in the operating position of the actuating device  7  (FIGS. 14 and 16) only causes the cams  28 ,  28 ′,  29 ,  29 ′ to slide in the vertical tracks  30 ,  30 ′,  31 ,  31 ′ without reaching their angled section at the proximal end of the spreader bushing  35 . In order for the cams  28 ,  28 ′,  29 ,  29 ′ to reach the angled section of the tracks  30 ,  30 ′,  31 ,  31  ′ and to release themselves from the threaded rod  9 , the actuating device must also be in its proximal position (FIG. 15).  
           [0029]    To release the threaded rod  9  the control button  8  has to be pressed, as shown in FIG. 15, so that the flanges  27 ,  27 ′ are moved from the distal position shown in FIG. 16 to the proximal position along the vertical tracks  30 ′,  31 ′ to the point where the tracks  30 ′,  31 ′ spread outwards. Then, after actuating the unlocking slide  32 , the spreader bushing  35  which is during normal operation in a fixed and stationary relationship, is moved in the distal direction, thereby spreading the flanges  27 ,  27 ′ open to release the rod  9 . Thus, two elements have to be actuated by the user at the same time to slide back the rod  9 , namely the control button  8  and the unlocking slide  32 .  
         SUMMARY  
         [0030]    In one embodiment, the present invention provides an injection device and an actuator wherein the actuator comprises a first actuator component which is adapted to permit a second actuator component to be selectively moved when the first actuator component is manipulated by a third actuator component.  
           [0031]    In one embodiment, the present invention provides an injection device and an actuator for the injection device wherein the actuator comprises a first actuator component comprising a counter component which is adapted to permit a second actuator component comprising a driven member to be selectively moved when the counter component is manipulated by a third actuator component.  
           [0032]    In one embodiment, the present invention provides an injection device and an actuator for an injection device wherein the actuator comprises a first actuator component comprising a counter component which is adapted to permit a second actuator component comprising a driven member to be selectively moved when the counter component is manipulated by a third actuator component comprising a bushing which is selectively movable with and relative to the counter component.  
           [0033]    In one embodiment, the present invention provides an actuator for an injection device, wherein the actuator comprises a generally rod-shaped driven member having a structured surface portion, a counter component having a structured surface portion engaging with the structured surface portion of the driven member, whereby the driven member is movable by the counter component, and a spreader bushing for spreading open the counter component by a movement relative to the counter component, thereby allowing the driven member to shift freely, wherein the spreader bushing is selectively movable with and relative to the counter component.  
           [0034]    According to the present invention, a driven member can be shifted freely in an axial direction by forcibly opening the counter component upon actuation of a single element. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]    The invention is described with reference to the enclosed drawings showing embodiments of the invention, where:  
         [0036]    [0036]FIG. 1 shows a first embodiment of an injection device according to the invention with the threaded rod in a distal position and a blocked unlocking slide;  
         [0037]    [0037]FIG. 2 shows a first embodiment of an injection device according to the invention with a pushed control button and a blocked unlocking slide;  
         [0038]    [0038]FIG. 3 shows a first embodiment of an injection device according to the invention with a released threaded rod and a pushed unlocking slide, the control button not being pushed;  
         [0039]    [0039]FIG. 4 shows a cross sectional view along line A-A of FIG. 1;  
         [0040]    [0040]FIG. 5 shows a perspective view of a spreader bushing surrounding a threaded flange according to the invention;  
         [0041]    [0041]FIG. 6 shows a second embodiment of an injection device according to the invention with the container not being inserted;  
         [0042]    [0042]FIG. 7 shows the injection device of FIG. 6 with the inserted container;  
         [0043]    [0043]FIG. 8 shows the injection device of FIG. 7 with the control button being pushed;  
         [0044]    [0044]FIG. 9 shows the injection device of FIG. 7 with the threaded rod being released;  
         [0045]    [0045]FIG. 10 shows the injection device of FIG. 7 in a cross-sectional view perpendicular to the view of FIG. 7;  
         [0046]    [0046]FIG. 11 shows a cross sectional view along line B-B of FIG. 9;  
         [0047]    [0047]FIG. 12 shows a cross sectional view along line A-A of FIG. 8;  
         [0048]    [0048]FIG. 13 shows a cross sectional view along line C-C of FIG. 9;  
         [0049]    [0049]FIG. 14 shows an injection device of the prior art with a retained threaded rod;  
         [0050]    [0050]FIG. 15 shows an injection device of the prior art with a free threaded rod;  
         [0051]    [0051]FIG. 16 shows an injection device of the prior art in which the actuating device has been removed;  
         [0052]    [0052]FIG. 17 shows a cross section along line A-A of FIG. 14;  
         [0053]    [0053]FIG. 18 shows a cross section along line B-B of FIG. 15; and  
         [0054]    [0054]FIG. 19 shows a cross section along line C-C of FIG. 15. 
     
    
     DESCRIPTION  
       [0055]    Reference is made to the above description of FIGS.  14  to  19  for the general function of the inventive injection device, except the function of the unlocking slide  32 , spreader bushing  37  and flanges  27  and  27 ′.  
         [0056]    Referring to FIG. 1, the actuating device  7  comprises a control button  8 , a threaded rod  9  with a flange  19 , a guide member  24  and a driving member  11 .  
         [0057]    The tubular driving member  11  is rigidly connected to the control button  8 . When the control button  8  is actuated, for example rotated or pushed, the corresponding movement is transferred to the driving member  11 , the spreader bushing  37  and the threaded flanges  27 ,  27 ′. The threaded flanges  27 ,  27  ′ engage with the threaded rod  9  during normal operation. The spreader bushing  37  surrounds both the driving member  11  and the threaded flanges  27 ,  27 ′ and moves with them during normal operation.  
         [0058]    When turning the control button  8  to adjust an injection dose, the driving member  11  is also turned. This rotating movement can, however, not directly be transferred to the threaded rod  9  as the rod  9  is rigidly seated in the guide member  24 . Referring to FIG. 5, projections of the driving member  11  (not shown) or of any other suitable element to transfer a movement of the driving member engage with recesses  37   a ,  37   b  of the spreader bushing  37  to rotate the spreader bushing  37  when the driving member  11  is turned. Projections  37   c ,  37   d  of the spreader bushing  37  engage with projections  27   a  or  27   b  of a first flange  27  shown in FIG. 5 and a second flange  27 ′ (not shown) to transfer the rotational movement of spreader bushing  37  to the flanges  27  and  27 ′. By this rotational movement of the threaded flanges  27 ,  27 ′ the threaded rod  9  seated in the guide member  24  preventing rotational movement of the rod  9 , as described above, is driven forward via the threaded sections on rod  9  (or backward, when reversing the rotation direction of the control button  8 ), thus bringing the flange  19  into the position required for the next injection dose to be discharged, i.e. the distance of the flange  19  from the piston  5  is respectively increased or reduced.  
         [0059]    When pressing the control button  8  against the force of spring  16 , as shown in FIG. 2, the actuating device is moved in the proximal direction. Flange  19  pushes thereby against piston  5  during this operation, carrying it along the set piston travel and thus discharging the pre-set volume of injection fluid through injection needle  6 .  
         [0060]    According to the invention the spreader bushing  37  is also moved in the proximal direction when pressing control button  8  to remain basically in the same relative position to the flanges  27 ,  27 ′.  
         [0061]    The axial movement is effected against the bias of a spring  16 , returning the actuating device  7  to its home position after injection, as shown in FIG. 1.  
         [0062]    When the fluid container  4  is empty and the threaded rod  9  is therefore in an extreme proximal position, the threaded rod must be returned to an extreme distal position. The injection device according to the invention allows the threaded rod  9  to be returned only by activation of the unlocking slide  32 , as shown in FIG. 3.  
         [0063]    When the fluid container  4  is removed from the injection device, as shown in FIG. 3, the blocking element  36   a  is moved to a proximal position, thereby allowing the unlocking slide  32  to be moved in a direction to engage with a recess  37   e  of the spreader bushing  37 , which either directly causes a movement of the spreader bushing in the distal direction, relative to the flanges  27 ,  27 ′, thus spreading flanges  27 ,  27 ′ open. This movement can be effected by the provision of tilted surfaces effecting an axial movement of spreader bushing  37  when moving unlocking slide  32  in radial direction. It is also possible to effect this movement by simply engaging unlocking slide  32  with spreader bushing  37  and subsequent axial movement of slide  32 . Since the spreader bushing  37  is moved together with the flanges  27 ,  27 ′ during normal operation, spreader bushing  37  can always be in a position close to the flanges  27 ,  27 ′ so that only a short relative movement of the spreader bushing  37  is required to spread flanges  27 ,  27 ′ open. Thus, control button  8  does not have to be pressed to unlock rod  9 .  
         [0064]    [0064]FIGS. 4 and 5 show that both threaded flanges  27 ,  27 ′ are designed as two half-shelf threaded nut sections which surround the rod  9  having circular surfaces  13 ,  13 ′ being threaded which engage with the threaded surface  27   c  on the inner side of flanges  27 ,  27 ′. The outer diameter of the threaded flanges  27 , 27 ′ becomes smaller in distal direction.  
         [0065]    Projections  27   a ,  27   b ,  27 ′ a ,  27 ′ b  of the flanges  27 ,  27 ′ are positioned to form grooves G between the respective projections  27   a  and  27 ′ a  or  27   b  and  27 ′ b  which become smaller in the distal direction. Projections  37   c ,  37   d  of the spreader bushing  37  form a wedge-shaped part  37   g  having a width gradually decreasing in the distal direction, so that if the spreader bushing  37  is moved relative to the flanges  27 ,  27 ′, the flanges  27 ,  27 ′ are guided by grooves  37   h ,  37   i  adjacent the wedge-shaped part  37   g  to thereby open or close the flanges  27 ,  27 ′.  
         [0066]    Recesses can be provided at a variety of positions along bushing  37 , so that more than the shown recesses  37   e  and  37   f  can be provided. The recesses can either be formed around bushing  37  or only at district portions, as shown in FIG. 5. Notches can be provided to allow rotations of bushing  37  only with a predefined angle in the end position.  
         [0067]    A second embodiment of the invention is described with reference to FIGS.  6  to  13 .  
         [0068]    [0068]FIG. 6 shows an injection device according to a second embodiment of the invention. The container  4  is not inserted. According to the second embodiment spreader bushing  37  has two recesses  37   e ,  37   f  surrounding the spreader bushing  37 . Unlocking slide  32  can engage with spreader bushing  37  using either of the recesses  37   e ,  37   f  so that spreader bushing  37  can be moved relative to the flanges  27 ,  27 ′ in two positions of the injection device, namely with control button  8  being in the normal position, as shown in FIG. 6, so that unlocking slide  32  engages with the proximal recess  37   e  of spreader bushing  37 , or with control button  8  being pressed, so that unlocking slide  32  engages with the distal recess  37   f  of spreader bushing  37 , as shown in FIGS. 8 and 9. Thus, according to the second embodiment, the flanges  27 ,  27 ′ can be spread open starting from two positions of the injection device, namely with control button  8  being in the normal position, or control button  8  being pressed. According to the invention only one element, namely unlocking slide  32 , has to be actuated by the user to unlock rod  9  to allow it to be moved to the distal position, when the injection device is held with the distal end facing downwards.  
         [0069]    In general it is possible according to the invention that more than only two recesses  37   e ,  37   f  are provided in the spreader bushing  37 . Any other element or structure can be used for the invention which allows an engagement of unlocking slide  32  with spreader bushing  37 , as for example a structured or notched surface of the unlocking slide  32 , which can engage with the respective counter element on spreader bushing  37 .  
         [0070]    The engaging portion of unlocking slide  32  can be tilted with respect to the axial direction of the injection device to cause an immediate movement of spreader bushing  37 , when unlocking slide  32  is pressed down, as shown schematically in FIG. 3 of the first embodiment. However, it is also possible to provide the possibility for engagement of unlocking slide  32  with spreader bushing  37 , so that the user first has to perform an engaging operation, for example by pressing down unlocking slide  32  of FIG. 6, and then has to perform a shifting operation by moving unlocking slide  32  coupled with spreader bushing  37  in the distal direction, thus effecting a movement of spreader bushing  37  in the distal direction relative to flanges  27 ,  27 ′, thus spreading flanges  27 ,  27 ′ open. In general it is also possible to provide a mechanism which will open the flanges  27 ,  27 ′ by any other movement of unlocking slide  32 , e.g. in the proximal direction.  
         [0071]    After inserting the container  4 , as shown in FIG. 7, control button  8  is turned to adjust a dose to be injected, as described above, and is then pressed to move rod  9  in a proximal direction, thereby injecting the preset dose. Spreader bushing  37  is moved together with driving member  11  during normal operation and remains thus in a basical fixed relative relationship.  
         [0072]    When the rod  9  is in a proximal position after performing one or more injection operations, container  4  is removed as shown in FIG. 8 and unlocking slide  32  is pressed to engage with the distal recess  37   f  of spreader bushing  37  as shown in FIG. 9. After this engagement unlocking slide  32  is moved in the distal direction of the injection device, thus moving spreader bushing  37  in the distal direction, which biases spring  38  located between driving member  11  and spreader bushing  37 . This movement of spreader bushing  37  in axial direction causes a movement of the flanges  27 ,  27 ′ in a radial direction of the injection device, thus spreading flanges  27 ,  27 ′ open, as shown in FIG. 9. Rod  9  is now movable inside the injection device and can be brought to the distal position by simply holding the injection device with the distal side facing downwards, causing rod  9  to fall into an extreme distal position.  
         [0073]    After rod  9  is brought into its distal position unlocking slide  32  can be released, thus effecting that spring  38  pushes spreader bushing  37  back to its normal position, thereby again engaging the threaded flanges  27 ,  27 ′ with the threaded surfaces  13 ,  13 ′ of rod  9 .  
         [0074]    [0074]FIG. 10 again shows the basic concept of the inventive injection device with a cross-sectional view in a plane turned by 90° with respect to the cross-sectional views described above.  
         [0075]    [0075]FIG. 11 shows a cross-sectional view along line B-B of FIG. 9. Flanges  27 ,  27 ′ are spread open by the wedge-shaped elements  37   g  of spreader bushing  37 , which engage with the projection  27   a ,  27   b  of flange  27  which are shown and described with reference to FIG. 5, and the corresponding projections of flange  27 ′.  
         [0076]    [0076]FIG. 12 shows the flanges  27 ,  27 ′ in a closed condition being engaged with rod  9 , seen in the cross-sectional view along line A-A in FIG. 8. In this state spreader bushing  37  is in a more proximal position relative to the flanges  27 ,  27 ′, as compared to the state shown in FIG. 11.  
         [0077]    [0077]FIG. 13 is a cross-sectional view along line C-C in FIG. 9 and shows the coaxial arrangement of the inventive injection device.  
         [0078]    In general, it is not intended that the invention described herein be restricted to the described embodiments. Reference should be made to the appended claims to ascertain the spirit and scope of the invention.