Abstract:
A device for administering an injectable product in doses including a casing, a reservoir for the product, a piston which displaces product towards a reservoir outlet and out of the reservoir when it slides in an advancing direction, a drive member which may be slid along a sliding axis, thereby pushing the piston in the advancing direction, and a dosing member which is mounted in the casing and may be slid, preferably rotatably, about the sliding axis of the drive member for setting a product dose, wherein a bearing surface between the dosing member and the casing is lubricated and at least one lubricating agent reservoir is provided on the bearing surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application is a continuation of International Patent Application PCT/CH01/00469, filed on Jul. 31, 2001, which claims priority to German Patent Application No. 100 47 637.6, filed on Sep. 26, 2000, the contents of which are incorporated herein by reference.  
         SUMMARY  
         [0002]    The invention relates to a devices for administering an injectable product. An injection device or apparatus in accordance with the present invention also relates to what is known from WO 97/36625 and DE 199 00 792 C1. The injection apparatus of the present invention comprises a casing, a product reservoir including a piston accommodated in it such that it can slide and displace product from the reservoir when it slides in an advancing direction, a drive means, and a dosing means.  
           [0003]    The drive means comprises a drive member which can slide in the advancing direction and a driven member which is prevented from sliding counter to the advancing direction, but which is slaved by the drive member when the drive member slides in the advancing direction thereby pushing the piston in the advancing direction, such that product is displaced from the reservoir. The product is deliverable in selected dosages set or chosen by means of the dosing means.  
           [0004]    The dosing means comprises the drive member and a dosing member for setting the distal end position of the drive member. The dosing member is mounted in the casing, rotatable about the axis along which the drive member moves or slides axially. In one embodiment, it preferably comprises a dosing stopper revolving spirally about the sliding axis, preferably with a continuous course and a constant gradient relative to the sliding axis of the drive member, said drive member abutting said dosing stopper when it slides into the distal position, i.e., the rotational angular position of the dosing member determines the distal position of the drive member.  
           [0005]    The deliverable product dosage is selected by rotating the dosing member, in one embodiment preferably in discrete steps. To this end, the dosing member locks in rotational angular locking positions formed at regular intervals between the casing and the dosing member. Rotating the dosing member between two adjacent locking positions corresponds to the smallest settable product dosage.  
         SUMMARY  
         [0006]    An object of the present invention is to provide a device for administering an injectable product, in particular of the aforementioned type, which enables a user to easily dose a product, wherein the dosing precision and accuracy of previously known devices is at least maintained. In particular, easy rotation of the dosing member is ensured.  
           [0007]    This object is addressed by the injection device of the present invention, which comprises a bearing surface between the dosing member and the casing, wherein the bearing surface is lubricated. In one embodiments, at least one lubricating agent reservoir is provided on or near the bearing surface. The present invention also encompasses a method of providing a lubricated bearing surface.  
           [0008]    In one embodiment, the present invention comprises a device for administering an injectable product in doses, said device comprising a casing, a drive member moveable along a sliding axis, a dosing member operably moveable about the sliding axis of the drive member for setting a product dose, and a bearing surface between said dosing member and the casing, the bearing surface being lubricated. At least one lubricating agent reservoir is operably adjacent to the bearing surface. The dosing member is operably coupled to the casing by an annular bulge, such that it can slide axially, and the bearing surface is formed by at least one surface of the annular bulge. In one embodiment, the annular bulge is provided on the dosing member and is axially held in an annular groove in the casing. In one embodiment, the at least one lubricating agent reservoir is formed by a flattened portion of the annular bulge.  
           [0009]    By lubricating the bearing surface, friction between the dosing member and the casing is reduced. The movement, preferably rotation, of the dosing member which has to be performed for dosing is made easier for the user. By providing at least one lubricating agent reservoir, sufficient lubricating agent can be provided to avoid the need for a secondary supply of lubricating agent during the entire usable life of the device. Thus, lifetime lubrication is ensured. This simplifies using the device.  
           [0010]    In one embodiment, the lubricating agent reservoir is preferably provided in the immediate vicinity of the bearing surface. In one embodiment, it is preferably formed by a hollow space or relieved area in the dosing member or in the casing.  
           [0011]    In one embodiment, the dosing member is preferably mounted in the casing, rotatable about the sliding axis of the drive member and secured against sliding axially. Particularly preferably, there is no longitudinal play between the dosing member and the casing. This ensures exact dosing in the device. A high surface pressure therefore prevails in the bearing surface between the dosing member and the casing. This high surface pressure results in a high torque which, however, is effectively reduced by lubricating.  
           [0012]    In one preferred embodiment, the dosing member is mounted on the casing, secured against sliding axially via an annular bulge. The annular bulge is preferably arranged on the surface area of the dosing member which is in contact with the casing, and protrudes into a recess in the surface area of the casing. In this way, an undercut is produced between the dosing member and the casing. In principle, however, the annular bulge could also be provided on the casing. A surface of the annular bulge at an angle to the sliding axis forms a bearing surface for the axial mount of the dosing member. Preferably, this surface is lubricated and at least one lubricating agent reservoir is provided on it. The lubricating agent reservoir is arranged such that the lubricating agent situated in it comes into contact with the bearing surface when the dosing member is rotated.  
           [0013]    In some embodiments, a second bearing surface for the axial mount of the dosing member is also lubricated and at least one lubricating agent reservoir is provided on it. This second bearing surface can be formed by another surface of the annular bulge or by another surface of the dosing member or the casing.  
           [0014]    In one embodiment, the annular bulge is preferably provided on the dosing member and axially held in a recess in the casing. The dosing member is arranged within the casing such that the annular bulge radially projects from the outer surface area of the dosing member into an annular groove provided on the inner surface area of the casing.  
           [0015]    In some embodiments, the lubricating agent reservoir is preferably formed by a flattening of the annular bulge. In one preferred embodiment, the annular bulge is interrupted at the point at which the lubricating agent reservoir is provided. The interruption in the annular bulge creates a hollow space between the dosing member and the annular groove in the casing. Any suitable lubricating agent can be stored in this hollow space. One advantage of the lubricating agent reservoir is that, while the lubricating agent is pressed away from the bearing surface as the dosing member is assembled in the casing, the bearing surface is adjacent to, travels near or contacts a lubricating agent reservoir during rotation such that constant re-lubricating is ensured. The lubricating agent also remains at the desired point after assembly.  
           [0016]    In some preferred embodiments, a number of lubricating agent reservoirs may be arranged or distributed, including uniformly distributed, over the circumference of the dosing member or the casing. This ensures that the bearing surface is better lubricated. In one preferred embodiment, four lubricating agent reservoirs are provided.  
           [0017]    In one embodiment, grease is used as the lubricating agent, particularly preferably Molykote grease. The lubricating agent reservoirs are thus provided as pockets of grease. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    An exemplary preferred embodiment of the present invention is explained below with reference to the accompanying figures.  
         [0019]    [0019]FIG. 1 depicts an injection device comprising a dosing means, in longitudinal section; and  
         [0020]    [0020]FIG. 2 depicts a dosing member comprising a lubricating agent reservoir in accordance with the present invention, corresponding to Detail area A of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0021]    [0021]FIG. 1 shows an injection apparatus, in the exemplary embodiment an injection pen, in longitudinal section. FIG. 2 shows Detail area A of FIG. 1.  
         [0022]    The injection apparatus comprises a casing including a front casing sleeve  1  and a rear casing sleeve  10  fixedly connected to the front casing sleeve  1 . The front casing sleeve serves as a receptacle for an ampoule  2 . A liquid product in the form of an active agent solution, for example insulin, is contained in the ampoule  2 . Furthermore, a piston  3  is accommodated in the ampoule  2 . By sliding the piston  3  in the advancing direction, i.e., towards an ampoule outlet  4 , the product is displaced from the ampoule  2  through its outlet  4  and delivered through an injection needle N, which can be any size, including  31 G or a higher or lower Gauge number. The front casing sleeve  1  is protected by a cap K, as is the needle N.  
         [0023]    The piston  3  is slid in the advancing direction by a drive means accommodated in the rear casing sleeve  10 . The drive means comprises a toothed rack  5  as a driven member which acts directly on the piston  3 , and a drive member  6 . The drive member  6  mounted in the rear casing sleeve  10  such that it can be linearly slid along the sliding axis V in and counter to the advancing direction of the piston  3 . A cover  9 , which is connected to the drive member  6  such that it can slide and freely rotate, protrudes backwards out of the casing.  
         [0024]    A dosing member  15  provided as a sleeve body is connected to the rear casing sleeve  10 , secured against sliding but rotatable about a common longitudinal axis which corresponds to the sliding axis V. The dosing member  15  protrudes into the rear casing sleeve  10  via a front sleeve portion  17 . Its rear sleeve portion protrudes out of the rear casing sleeve  10 . The rear sleeve portion of the dosing member  15  is provided with a contour  16  so that it can be rotated with a secure manual grip.  
         [0025]    As is seen by referring to FIG. 2, an annular bulge  20  provided on the front sleeve portion  17  of the dosing member  15  and latched into a circumferential recess  19  on the inner surface of the rear casing sleeve  10  serves to fix the dosing member  15  such that it is secured against sliding. A bearing surface L 1  of the annular bulge  20  comes into contact with an undercut surface of the recess  19  of the rear casing sleeve  10 . Any suitable complementary fixing structure may be used to fix the dosing member, and any suitable shape or arrangement may be used to provide for the bulge  20  and recess  19 . A second bearing surface L 2  is formed between the rear end of the rear casing sleeve  10  and a circumferential, radially protruding projection of the dosing member  15 . The dosing member  15  is mounted in the casing, secured against axially sliding, between the bearing surfaces L 1  and L 2 .  
         [0026]    In front of the contour  16  (see FIG. 1), the dosing member  15  may have a suitable, clearly visible dosage scale (not shown, but well known in the art) around its outer surface area, the scale being adjusted to established rotational angular positions in which the dosing member  15  locks against the rear casing sleeve  10 . The locking mechanism between the dosing member  15  and the rear casing sleeve  10  is formed by elevations on the outer surface of the front sleeve portion  17  of the dosing member  15 , and cavities  23  are formed in the inner surface of the rear casing sleeve  10 . The cavities  23  are circumferentially arranged on a level, alongside each other, at equal angular intervals on the inner surface of the rear casing sleeve  10 . In the fixed rotational angular locking positions of the dosing member  15 , the number of elevations are accommodated precisely in the respectively opposing cavities in the inner surface of the rear casing sleeve  10 .  
         [0027]    When the injection apparatus is completely assembled, as shown in FIG. 1, the drive member  6  protrudes through the dosing member  15 . The dosing member  15  concentrically surrounds a distal portion of the drive member  6  and also of the driven member  5 . The cover  9  protrudes via a sleeve portion into an annular gap formed between the drive member  6  and the dosing member  15 . As is known to those skilled in the art, the cover  9  may also bear a marking in its surface region protruding out of the dosing member  15 , which in cooperation with the marking on the dosing member  15  enables the total amount of product administered from the ampoule  2  to be determined exactly, even after a number of complete rotations of the dosing member  15 .  
         [0028]    The maximum dosage path length which the drive member  6  and the toothed rack  5  can travel in the advancing direction, and therefore also the maximum product dosage which may be delivered in an injection, also if the size of the needle is  31 G or a higher Gauge number, is set by rotating the dosing member  15 .  
         [0029]    The smaller the axial play of the dosing member  15  in the rear casing sleeve  10 , the more exact the dosage of the device. The dosing member  15  is preferably accommodated in the rear casing sleeve  10  with no play. This, however, increases the surface pressure on or between the bearing surfaces L 1 , L 2 , such that a higher torque would be required from the user to set the dosage. By lubricating at least the one of the bearing surfaces L 1 , L 2  this torque can be reduced. Since at a high surface pressure the lubricating agent would be displaced from the bearing surfaces L 1 , L 2  during assembly or operation, lubricating agent reservoirs F are provided to help establish and maintain a contact between the bearing surfaces L 1 , L 2  and the lubricating agent.  
         [0030]    A lubricating agent reservoir F is formed by an interruption in sections of the annular bulge  20 . This results, in sections, in an intermediate space between the dosing member  15  and the casing sleeve  10 . This intermediate space can be filled with lubricating agent, such as grease, and serves to provide lifetime lubrication for the bearing surface L 1 . In some preferred embodiments, a number of lubricating agent reservoirs F are arranged in uniform distribution over the circumference. The more lubricating agent reservoirs F are provided, the more often the bearing surface L 1  brushes over a lubricating agent reservoir F when rotated. The section of FIG. 2 runs through the annular bulge  20  in the upper region of the drawing and through a lubricating agent reservoir F in the lower region of the drawing.  
         [0031]    [0031]FIG. 2 depicts a further development of a lubricating agent reservoir F in which its volume is increased by additionally providing a suitably shaped cavity C (shown in phantom; any suitable shape may be used) in the dosing member  15  in the region of the interruption in the annular bulge  20 . It should be appreciated that the annular bulge  20  could be arranged on the rear casing sleeve  10 , with the lubricating agent reservoir F provided therein as well. It should also be appreciated that lubricating agent reservoirs can also be provided in the bearing surface L 2 , analogously to the lubricating agent reservoirs F in the annular bulge  20 . Preferably, in some embodiments, the reservoirs F are formed by recesses in the radial facing surface of the dosing member  15  or of the rear end surface of the rear casing sleeve  10 . In some embodiments, lubricating agent reservoirs F are only provided in the bearing surface L 1 . They can, however, also be provided in the bearing surface L 2 . In some preferred embodiments, lubricating agent reservoirs F may be situated in both bearing surfaces L 1  and L 2 .  
         [0032]    Before the dosing member  15  is assembled, the region  22  of the rear casing sleeve  10  indicated in FIG. 2 by a broken line is provided with lubricating agent. When, to assemble it, the dosing member  15  is pushed into the rear casing sleeve  10 , the lubricating agent remains behind in the region of the lubricating agent reservoirs F and ensures that the bearing surfaces L are lubricated when the dosing member  15  is rotated.  
         [0033]    Dosing is performed in a proximal end position of the drive member  6 , foremost with respect to the advancing direction, in which position a stopper cam or collar  13  protruding radially from the outer surface area of the drive member  6  abuts a stopper formed by the rear casing sleeve  10 . In this proximal end position of the drive member  6 , the dosing member  15  is rotated about the sliding axis V relative to the rear casing sleeve  10  until it has reached the desired dosing or rotational angular locking position. In this dosing position, a slight dosing interval remains between another collar or cam (which may be known as the dosing cam) which likewise projects from the outer surface area of the drive member  6  and forms the dosing stopper and the proximal facing side  18  of the dosing member  15  opposite said dosing cam  14 . The drive member  6  can be retracted counter to the advancing direction, relative to the rear casing sleeve  10  and therefore also relative to the piston  3 , by the dosing interval. It is retracted manually by pulling on the cover  9 . The dosing interval is equal to the dosage path length when the product is subsequently administered.  
         [0034]    When the drive member  6  is slid back or retracted, the toothed rack  5  remains in its sliding position relative to the casing, assumed during the dosing process. The toothed rack  5  is secured against sliding counter to the advancing direction by blocking means  11  and  12  provided on the rear casing sleeve  10 . In one embodiment, the blocking means  11  and  12  are locking cams provided on each of the front ends of an elastically flexible tongue, and protrude from their tongue radially inwards towards the toothed rack  5 . The blocking means  11  and  12  each cooperate with a row of teeth of the toothed rack  5  facing them, such that they allow the toothed rack  5  to slide in the advancing direction and prevent it from sliding counter to the advancing direction using a positive-lock blocking mesh or connection. Once the drive member  6  has been retracted, it can be slid in the advancing direction by the dosage path length, thereby slaving the toothed rack  5  and the piston  3 , such that a dosed amount of the injectable product is displaced from the reservoir  2 .  
         [0035]    In the foregoing description, embodiments of the invention, including preferred embodiments, have been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments were chosen and described to provide the best illustration of the principals of the invention and its practical application, and to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth they are fairly, legally, and equitably entitled.