An injection device with support ribs for supporting a glass cartridge

Abstract

The invention relates to a pre-filled injection device comprising an enclosed glass cartridge having a distal neck portion with a circumferential shoulder portion, and a proximal end portion with an opening surrounded by a proximal circumferential rim. A piston rod is adapted to move a plunger inside the cartridge. The two-part cartridge enclosure enclosing the glass cartridge comprises a distal section comprising a distal support structure engaging the circumferential shoulder portion of the cartridge and a proximal section comprising a proximal support structure engaging the proximal circumferential rim of the cartridge. The proximal support structure comprises support ribs pointing inwardly into the cartridge enclosure to engage the cartridge, and which support ribs are non-perpendicular and resilient.

Description

[0001] An Injection Device with Support Ribs for Supporting a Glass Cartridge

[0002] THE TECHNICAL FIELD OF THE INVENTION:

[0003] The invention relates to a pre-filled injection device with a two-part cartridge enclosure in which a glass cartridge is enclosed and axially secured.

[0004] The invention further relates to a two-part cartridge enclosure for enclosing a glass cartridge.

[0005] DESCRIPTION OF RELATED ART:

[0006] In so-called pre-filled injection devices, i.e. injection devices wherein the cartridge cannot be exchanged, the cartridge needs to be rather firmly secured in the housing structure in order to obtain a precise dosing.

[0007] EP 3,277,345 discloses an injection device with a glass cartridge in which the glass cartridge is located between a distal part engaging the distal portion of the cartridge and a proximal part which engages the proximal rim portion of the cartridge. In one prior art example depicted in figure 4 in EP 3,277,345, the proximal portion of the enclosure is provided with a number of holding ribs (“135” in figure 4) which engages the proximal rim on the glass cartridge. Such ribs are typical moulded as thin radial plastic ribs and are often referred to as crush ribs as they are crushed i.e. plastically deformed during assembly of the injection device. Due to the plastic deformation theses ribs are able to obtain tolerances both in the length and in the diameter of the glass cartridge. The glass cartridge is thus secured from axial movement by these two engagements. Since the proximal engagement is plastically deformed during assembly, a relatively large force is applied to the glass cartridge during assembly. However, since glass cartridges are fragile, especially on the proximal rim, such large force applied onto the rim can lead to fractures or even breakage of the fragile rim of the cartridge. WO 2022 / 268,771 discloses a prefilled single shot injection device with an enclosed glass cartridge. The glass cartridge is distally secured by the housing engaging the distal neck part of the cartridge. A nut element is threaded to the housing and has a number of inwardly pointing crush flanges (“67” depicted in figure 4D) which engages the proximal rim of the cartridge such that the glass cartridge is axially secured between the housing and the nut member. However, as these crush flanges are plastically deformed during assembly, the force applied to the rim of the glass cartridge is relatively high which can lead to fractures or even breakage in the fragile rim.

[0008] In an attempt to lower the force applied to the rim of the glass cartridge disclosed in US 2023 / 0191029 it has been suggested to angle the protruding crush ribs relative to the longitudinal axis such that the crush ribs both plastically deforms and folds. However, as the crush ribs needs to be plastically deformed a relatively high force is still applied onto the rim of the glass cartridge.

[0009] In order to protect the fragile rim of the cartridge it would be beneficial if the glass cartridge could be enclosed and axially locked without applying a high force directly onto the rim of the cartridge.

[0010] In a further example disclosed in EP 3,277,345, the two engagements points has been reversed such that the plastic deformation occurs at the distal neck portion of the glass cartridge by a number of crush flanges (“225” in figure 5) provided inside the housing. However, even this solution requires the proximal portion engaging the rim of the cartridge to apply a relatively large force to the rim portion in order to plastically deform the distal crush flanges.

[0011] US 5,372,590 discloses a safety syringe wherein a plastic housing is provided with a number of centring tabs supporting the outer surface of the barrel of the safety syringe and designed to centre the barrel of the safety syringe in the plastic housing. The housing is further closed by a lid at the proximal end. A couple of spring fingers prevents the barrel from being drawn to far in the proximal direction after injection. DESCRIPTION OF THE INVENTION:

[0012] It is henceforth an object of the present invention to provide an injection device in which the cartridge enclosure engages the proximal rim on the glass cartridge with a lower engagement force such that the fragile rim of the cartridge does not fracture upon assembly of the injection device.

[0013] The invention is further defined in claim 1. Advantageous embodiments are defined in the dependent claims. Accordingly in one aspect of the invention the fixed dose injection device comprises:

[0014] An enclosed glass cartridge preferably having a circular cross section around a longitudinal axis. The glass cartridge has a distal outlet portion with a distal neck portion with a circumferential shoulder portion, and a cylindrical main portion having a proximal end portion with an opening surrounded by a proximal circumferential rim.

[0015] A piston rod which adapted to move a plunger, preferably forward, inside the cartridge.

[0016] A two-part cartridge enclosure enclosing the glass cartridge, which two-part cartridge enclosure comprises: a distal section comprising a distal support structure engaging the circumferential shoulder portion of the cartridge and being adapted to support the cartridge against movement in the distal direction,

[0017] A proximal section comprising a proximal support structure engaging preferably around the proximal circumferential rim of the cartridge and being adapted to secure the cartridge against movement in the proximal direction.

[0018] The cartridge is thereby axially secured in the cartridge enclosure between the distal support structure and the proximal support structure. The proximal support structure comprises support ribs pointing inwardly into the two-part cartridge enclosure to engage the proximal circumferential rim on the cylindrical main portion of the cartridge to thereby secure the cartridge axially.

[0019] According to the present invention the support ribs are non-perpendicular and resilient. Since the support ribs are non-perpendicular and resilient, the force transferred from the ribs and onto the proximal circumferential rim on the cartridge is relatively low thereby protecting the fragile cartridge from breakage. The support ribs are hence simultaneously plastically deformed and resiliently operated when engaging the glass cartridge which lowers the force exposed onto the circumferential rim of the fragile glass cartridge.

[0020] By non-perpendicular is meant that the support ribs are not perpendicular to the longitudinal axis (X). As both the surface of the cartridge and the nut element follows this longitudinal axis (X) both these surfaces could be taken as the reference surface, hence the ribs are nonperpendicular to the longitudinal surface of the cartridge as well as to the longitudinal surfaces of the nut element. Hence, the ribs which are preferably located on an inner surface of the nut element are preferable non-perpendicular to the inner surface of the nut element on which they are provided.

[0021] By pre-filled is meant that the cartridge of the injection device is filled with a specific volume by the manufacturer of the injection device. Hence, the injection device cannot be re-filled by the user but is preferably discarded after the filled volume has been used. In one preferred example, the major part of the volume pre-filled into the cartridge is expelled as one fixed dose meaning that only one shoot is available in the cartridge. The user can thus only perform one injection with the injection device. Hence, the injection device is discarded after one single injection. Such injection devices are often referred to as fixed dose single shot devices. However, the principle claimed herein can be used for a large variety of different injection devices and are not restricted to neither pre-filled devices nor to single shot devices.

[0022] The principle herein described and claimed could also be implemented in cartridge units for reusable injection devices.

[0023] At the same time the resiliency of the support ribs is able to absorb the forces occurring should the injection device fall onto a hard surface such as the ground or a table. The resiliency of the support ribs hence operates as shock absorbers. Further, as the support ribs preferably are moulded straight in the axial direction, the moulding tools and the moulding process is uncomplicated.

[0024] The glass cartridge is hence axially secured in the two-part cartridge enclosure which means that the cartridge is irreversible secured in the cartridge enclosure such that the cartridge cannot be removed. To facilitate this the two parts making up the cartridge enclosure is provided with a mechanism which prevents the two parts from being disengaged once engaged. Such mechanism can in one example be a one-way ratchet mechanism working together with a threaded connection between the two parts. Following such solution, the two parts can only be rotated relatively to each other in one rotational direction. The allowed rotational direction being the one that moves the two parts together to thereby encapsulate the cartridge.

[0025] The radial support ribs are preferably tangentially shaped to engage the glass cartridge tangential to engage the glass cartridge tangential to the circular cross section of the cylindrical main portion of the glass cartridge. The tangential shape thus makes the support ribs resilient.

[0026] In a further embodiment, the tangential support ribs are simultaneously bended and plastically deformed by engagement with the glass cartridge. Upon engagement with the glass cartridge e.g. during assembly of the injection device the circumferential rim on the cartridge plastically deforms the tangential support ribs which are at the same time bended further in the tangential direction thereby lowering the force exposed onto the rim while the tangential resiliency operating on the sidewall of the glass cartridge operates as shock absorbers should the user drop the device onto a hard surface.

[0027] In one example, the two parts making up the cartridge enclosure securing the glass cartridge comprises are connected together. The two parts can in one example be threaded together however a broad number of connecting methods can be utilized. The two parts making up the cartridge enclosure each support the glass cartridge from opposite ends such that one part of the cartridge enclosure comprises the distal support structure and the other part of the cartridge enclosure comprises the proximal support structure.

[0028] One of the parts are preferably the housing structure of the injection device which thus comprises the distal support structure. The other part is preferably the nut element of the injection device which thus comprises the proximal support structure. The housing structure and the nut element making up the cartridge enclosure are preferably connected together by way of a thread connection, however many other methods of connecting these two parts can easily be contemplated.

[0029] Due to the resiliency of the tangential support ribs, they are folded further tangential by engagement with the glass cartridge. Preferably the radial support ribs points in the same tangential direction as the thread connection.

[0030] In a second aspect of the invention, the two-part cartridge enclosure enclosing the glass cartridge, comprises:

[0031] - A first distal part comprising a distal support structure engaging the circumferential shoulder portion of the glass cartridge and being adapted to support the cartridge against movement in the distal direction, and

[0032] - A second proximal part comprising a proximal support structure engaging the proximal circumferential rim of the cartridge and being adapted to support the glass cartridge against movement in the proximal direction.

[0033] The glass cartridge is thereby axially secured in the two-part cartridge enclosure between the distal support structure and the proximal support structure, the proximal support structure comprising support ribs pointing inwardly into the cartridge enclosure to engage the proximal circumferential rim on the cylindrical main portion of the glass cartridge.

[0034] The support ribs where one of more ribs can be provided are non-perpendicular and resilient.

[0035] In this way, the support ribs are simultaneously plastically deformed and resiliently operated when engaging the glass cartridge which lowers the force exposed onto the circumferential rim of the fragile glass cartridge and especially onto the circumferential rim thereby preventing the fragile glass cartridge from fractures and cracks during assembly of the injection device.

[0036] Such two-part cartridge enclosure could in one example be implemented into an exchangeable cartridge unit which could be used for a reusable injection device expelling a fixed dose.

[0037] The one or more radial support ribs are preferably tangential shaped to thereby have a radial resilient engagement with the sidewall of the glass cartridge. Hence, during assembly of the injection device, the tangential support ribs are simultaneously plastically deformed and bended to thereby secure the glass cartridge both axially and radially.

[0038] The first distal part and the second proximal part making up the cartridge enclosure are connected together using any known way of connecting elements such as e.g. a threaded connection. In one example, the threaded connection can be locked in one rotational direction by a one-way interface such that the thread is only operational in the opposite rotational direction. The workable direction being the one that encloses the cartridge.

[0039] DEFINITIONS:

[0040] An “injection pen” or “pen for injection” is typically an injection apparatus having an oblong or elongated shape somewhat like a pen for writing. Although such pens usually have a tubular cross-section, they could easily have a different cross-section such as triangular, rectangular or square or any variation around these geometries.

[0041] The term “Needle Cannula” is used to describe the actual conduit performing the penetration of the skin during injection. A needle cannula is usually made from a metallic material such as e.g. stainless steel and connected to a hub to form a complete injection needle also often referred to as a “needle assembly”. A needle cannula could however also be made from a polymeric material or a glass material. The hub also carries the connecting means for connecting the needle assembly to an injection apparatus and is usually moulded from a suitable thermoplastic material. The “connection means” could as examples be a luer coupling, a bayonet coupling, a threaded connection or any combination thereof.

[0042] The term “Needle unit” is used to describe one single needle assembly carried in a container. Such container usually has a closed distal end and an open proximal end which is sealed by a removable seal. The interior of such container is usually sterile such that the needle assembly is ready to use. Needle units specially designed for pen injection systems are defined in ISO standard No. 11608, part 2, and are often referred to as “pen needles”. Pen needles are usually double pointed having a front-end for penetrating through the skin of a user and a back-end for penetrating into the cartridge containing the drug such that liquid communication is established during injection.

[0043] As used herein, the term “Liquid drug” is meant to encompass any drug-containing flowable medicine capable of being passed through a delivery means such as a hollow needle cannula in a controlled manner, such as a liquid, solution, gel or fine suspension. Representative drugs include pharmaceuticals such as peptides, proteins (e.g. insulin, insulin analogues and C-peptide), and hormones, biologically derived or active agents, hormonal and gene-based agents, nutritional formulas and other substances in both solid (dispensed) or liquid form.

[0044] “Cartridge” is the term used to describe the container actually containing the drug which are often referred to as the primary packing as it is in direct contact with the liquid drug.

[0045] Cartridges are usually made from glass but could also be moulded from a suitable polymer. A cartridge or ampoule is preferably sealed at one end by a pierceable membrane referred to as the “septum” which can be pierced e.g. by the non-patient end of a needle cannula.

[0046] Such septum is usually self-sealing which means that the opening created during penetration seals automatically by the inherent resiliency of the septum once the needle cannula is removed from the septum. The opposite end of the cartridge is typically closed by a movable “plunger” which is a piston-like element made from rubber or a suitable polymer. The plunger is during use slidable moved inside the cartridge preferably in a distal direction. The space between the pierceable membrane and the movable plunger holds the liquid drug which is pressed out as the plunger decreased the volume of the space holding the liquid drug. The cartridges used for both pre-filled injection devices and for durable injections devices are typically factory filled by the manufacturer with a predetermined volume of a liquid drug. A large number of the cartridges currently available contains either 1 ,5 ml or 3 ml of liquid drug. The “rim” of a cartridge is generally understood to be the slightly raised part at the proximal end of the cartridge making up the end portion of the cartridge. Since a cartridge usually has a narrower distal neck portion into which the plunger cannot be moved not all of the liquid drug contained inside the cartridge can actually be expelled. The term “initial quantum” or “substantially used” therefore refers to the injectable content contained in the cartridge and thus not necessarily to the entire content.

[0047] By the term “Pre-filled injection device” is meant an injection device in which the cartridge containing the liquid drug is permanently embedded in the injection device such that it cannot be removed without permanent destruction of the injection device. Once the pre-filled amount of liquid drug in the cartridge is used, the user normally discards the entire injection device. Usually, the cartridge which has been filled by the manufacturer with a specific amount of liquid drug is secured in a cartridge holder which is then permanently connected in a housing structure such that the cartridge cannot be exchanged.

[0048] This is in opposition to a “Durable injection device” (also often named as a “Reusable injection device”) in which the user can himself change the cartridge containing the liquid drug whenever it is empty. Pre-filled injection devices are usually sold in packages containing more than one injection device whereas durable or reusable injection devices are usually sold one at a time. When using pre-filled injection devices an average user might require as many as 50 to 100 injection devices per year whereas when using durable or reusable injection devices one single injection device could last for several years, however, the average user would require 50 to 100 new cartridges per year.

[0049] All references, including publications, patent applications, and patents, cited herein are incorporated by reference in their entirety and to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0050] All headings and sub-headings are used herein for convenience only and should not be constructed as limiting the invention in any way.

[0051] The use of any and all examples, or exemplary language (e.g. such as) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. The citation and incorporation of patent documents herein is done for convenience only and does not reflect any view of the validity, patentability, and / or enforceability of such patent documents.

[0052] This invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law.

[0053] BRIEF DESCRIPTION OF THE DRAWINGS:

[0054] The invention will be explained more fully below in connection with a preferred embodiment and with reference to the drawings in which:

[0055] Figure 1 A show an exploded view of an example of a prior art injection device.

[0056] Figure 1 B show a cross-sectional view of the injection device in figure 1 A.

[0057] Figure 2 show a cross-sectional view of a carved-out portion of figure 1 B.

[0058] Figure 3 show a perspective view through line A-A of figure 2.

[0059] Figure 4 show a cross-sectional view through the line A-A in figure 2.

[0060] Figure 5 show a cross-sectional view of the tangential ribs according to the invention.

[0061] Figure 6 show a perspective view of the tangential ribs according to the invention.

[0062] The figures are schematic and simplified for clarity, and they just show details, which are essential to the understanding of the invention, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts.

[0063] DETAILED DESCRIPTION OF EMBODIMENT:

[0064] When in the following terms as “upper” and “lower”, “right” and “left”, “horizontal” and “vertical” or similar relative expressions are used, these only refer to the appended figures and not necessarily to an actual situation of use. The shown figures are schematic representations for which reason the configuration of the different structures as well as their relative dimensions are intended to serve illustrative purposes only. In that context it may be convenient to define that the term “distal end” in the appended figures is meant to refer to the end of the injection device supporting the injection needle, whereas the term “proximal end” is meant to refer to the opposite end carrying the injection button as indicated in figure 1A-B. Distal and proximal is meant to be along an axial orientation extending along the longitudinal axis (X) of the injection device as also shown in figure 1A-B.

[0065] When referring to clock-wise and anti or counter clock-wise in the following examples it is understood that the injection device is viewed from a position distal to the injection device. Clock-wise is thus a rotation following the arms on an ordinary clock to the right when e.g. moving from 12 O'clock to 3 O'clock, and wherein counter clock-wise is a rotation in the opposite direction.

[0066] To explain the various movements which take place in the injection device described in the example, the following terminology are used throughout the following detailed description.

[0067] “Translational movement” is meant to be a strictly linear movement without any rotation.

[0068] “Rotational movement” is any movement of rotation around a centre which centre can be a centre point i.e. in one planar or a centre axis i.e. having a longitudinal extension.

[0069] “Axial movement” means any movement in an axial direction. Such movement can be a strictly translational movement or include a rotational movement which thus makes it a “Helical movement” as this is meant to be an axial movement combined with a rotational movement. By “axial” is meant in a lengthwise direction but not necessarily along a straight line. “Radial” is meant to be at an angle to the axial direction. The angle is not necessarily 90 degrees hence the radial direction is not necessarily be perpendicular to the axial direction.

[0070] “Telescopic” is meant to cover the situation in which a movable element moves out from, and / or into, a base element. The telescopic movement can be either translational or include a rotation thus making the telescopic movement helical. Figure 1A and figure 1B discloses the prior art single dose injection device described in WO 2022 / 268771. The housing structure 10 is distally provided with a removable protective cap

[0071] 20 and proximally provided with an injection button 30 which can be pushed in the distal direction. The housing structure 10 distally supports a glass cartridge 40 which contains the liquid drug to be expelled. The glass cartridge 40 preferably contains one single dose which is injected in one single shot. The injection button 30 is fixedly connected to a piston rod 50 which is thus moved in the distal direction when the user presses the injection button 30. The piston rod 50 is slidable supported by a nut element 60 which is threaded to the housing structure 10 such that a piston rod foot 70 connected to, or supported by, the piston rod 50 during assembly can be brought into physical contact with a rubber plunger 41 positioned inside the glass cartridge 40 to thereby remove any air gap between the piston rod foot 70 and the rubber plunger 41 during assembly as explained in WO 2022 / 268771. The axial movement of the injection button 30 and the piston rod 50 are thus transferred directly to an equal movement of the rubber plunger 41 during injection.

[0072] The glass cartridge 40 containing the liquid drug to be ejected preferably has a circular cross section around the longitudinal axis X with a distal outlet portion having a distal neck portion with a circumferential shoulder portion 42. Proximally, a cylindrical main portion of the glass cartridge 40 terminates in a proximal circumferential rim 43. A rim of a glass cartridge typically has a slightly raised diameter, either on the inside or on the outside or both. As the cartridge 40 is made from glass it is vulnerable and the circumferential rim 43 is especially vulnerable.

[0073] As best seen in figure 1A, the housing structure 10 can be provided with at least one anti-roll protrusion 13 to hinder the single dose injection device in rolling on a surface such as a table or the like. This anti-roll protrusion 13 can be provided in any random position on the housing structure 10 and is e.g. in figure 3 disclosed in a more distal position whereas figure 1A discloses the anti-roll protrusion 13 in a proximal position on the housing structure 10. Further, the protective cap 20 can be provided with a pair of gripping flanges 21 enabling a user to more easily remove the protective cap 20. As seen in figure 1A these gripping flanges

[0074] 21 can be replaced by a textured surface.

[0075] Figure 2 is an enlargement of the encircled part of figure 1 B. The circumferential shoulder part 42 of the cartridge 40 is distally supported by a distal support structure 11 in the housing structure 10 (best seen in figure 1B) and the proximal circumferential rim 43 of the cartridge 40 is proximally secured by a proximal support structure 61 provided in the nut element 60 and which comprises a number of radial support ribs 62 provided on an inner surface of the nut element 60. The cartridge enclosure, in this example, comprises the housing structure 10 and the nut element 60.

[0076] The cartridge 40 is thus locked against any axial movement as the nut element 60 is connected to the housing structure 10 in a thread connection 12, 63. This thread connection 12, 63 comprises an outer thread 63 provided on an outer surface of the nut element 60 and an inner thread 12 provided on an inner surface of the housing structure 10.

[0077] A one-way ratchet is made between a one-way arm 64 on an inner surface of the nut element 60 working together with longitudinal teeth provided on an inner surface of the housing structure 10. The threaded connection 12, 63 between the housing structure 10 and the nut element 60 is hence irreversible as the threaded connection 12, 63 only works in one rotational direction. The direction being the one that encloses the cartridge 40.

[0078] The radial support ribs 62 are formed as inwardly pointing crush ribs which are plastically deformed by the proximal circumferential rim 43 on the cartridge 40 during assembly. This plastic deformation imposes a relatively high force onto the rim 43 of the cartridge 40.

[0079] When the single dose injection device is assembled, the proximal circumferential rim 43 on the glass cartridge 40 is forced into the polymer material making up the radial support ribs 62 which is thereby plastically deformed. The radial support ribs 62 are pointed inwardly and are moulded perpendicular to the inner surface of the nut element 60 as seen in figure 3.

[0080] Figure 3 and figure 4 further discloses views through line A-A of figure 2. The radial support ribs 62 are crushed i.e. plastically deformed in the longitudinal area “b” by the proximal circumferential rim 43 of the cartridge 40 as best seen in figure 3. The longitudinal length (along the axis “X”) of the area “b” varies depending on how far into the housing structure 10, the nut element 60 needs to be positioned and due to the tolerances on the length of the cartridge 40. The radial width of the crushed area “b” also varies from cartridge 40 to cartridge 40 due to the tolerances of the outer diameter of the cartridge 40.

[0081] As seen on figure 4 four such radial support ribs 62 are used, however, any number can be used all though three or more is preferred. The figures 5 and figure 6 discloses the present invention and the same elements as in the prior art example has been dedicated the same numerical numbers. However, in these figures the support ribs 62 has been designated the reference numerical “62a” to separate the tangential support ribs 62a from the perpendicular radial support ribs 62. The views disclosed in figure 5 and in figure 6 also follows the line A-A in figure 2 with the respect to the present invention.

[0082] As seen in figure 5 and figure 6, the inwardly pointing support ribs 62a are here moulded in a tangential direction and not perpendicular as in the prior art. Hence, the tangential support ribs 62a are folded inwardly by the proximal circumferential rim 43 of the cartridge 40 during assembly as best seen in figure 6. This lowers the force on the proximal circumferential rim 43 of the cartridge 40 as compared to the prior solution and thus secures that the cartridge 40 does not fracture or crack so easily during assembly.

[0083] The tangential support ribs 62a are thus crushed less than the radial and perpendicular ribs 62. Further, in addition to the tangential ribs 62a being crushed less, the resiliency and the tangential extension of the tangential support ribs 62a provides a better support for the cartridge 40 which is thereby able to absorb forces in the glass cartridge 40 arising should the device fall onto a hard surface. The tangential ribs 62a thus also helps protect the glass cartridge 40 from breakage when dropped e.g. onto the ground or a floor.

[0084] The resiliency of the tangential support ribs 62 operating on the sidewall of the cartridge 40 and on the rim 43 thus helps protect the glass cartridge 40 and the plastic deformation of the tangential ribs 62a by the rim 43 of cartridge secures the cartridge 40 from movement in the proximal direction. Prior to assembling the injection device, the fictive diameter formed by the inner surface of the tangential support ribs 62a are smaller than the outer diameter of the glass cartridge 40 as best seen in figure 5 such that the tangential support ribs 62 are simultaneously crushed and pushed further outwardly in the tangential direction during assembly to thereby apply a force onto the outside surface of glass cartridge 40 and support the circumferential rim 43 of the cartridge 40.

[0085] The tangential extension of the tangential support ribs 62a are preferably shaped such that the tangential support ribs 62a folds towards the smallest angle during assembly. The smallest angle of the tangential support ribs 62a are preferable less than 90 degrees as disclosed in figure 5 and 6. The tangential support ribs 62a are preferably moulded straight in the longitudinal direction following the longitudinal axis “X”. This makes the moulding tools relatively simple as a standard two-part tool can be used.

[0086] Some preferred embodiments have been shown in the foregoing, but it should be stressed that the invention is not limited to these but may be embodied in other ways within the subject matter defined in the following claims.

[0087] List of Parts

Claims

CLAIMS:

1. A pre-filled injection device, comprising:A glass cartridge (40) having a circular cross section around a longitudinal axis (X) with a distal outlet portion having a distal neck portion with a circumferential shoulder portion (42), and a cylindrical main portion having a proximal end portion with an opening surrounded by a proximal circumferential rim (43), andA piston rod (50) adapted to move a plunger (41) inside the glass cartridge (40), andA two-part cartridge enclosure (10, 60) enclosing the glass cartridge (40) comprising: a distal section comprising a distal support structure (11) engaging the circumferential shoulder portion (42) of the cartridge (40) and being adapted to support the cartridge (40) the distal direction,A proximal section comprising a proximal support structure (61) engaging the proximal circumferential rim (43) of the cartridge (40) and being adapted to support the cartridge (40) in the proximal direction,The glass cartridge (40) thereby being axially secured in the two-part cartridge enclosure between the distal support structure (11) and the proximal support structure (61),The proximal support structure (61) comprising support ribs (62) pointing inwardly into the two-part cartridge enclosure to engage the proximal circumferential rim (43) on the cylindrical main portion of the cartridge (40) to thereby secure the cartridge (40) axially,Characterized in that, the support ribs (62) are nonperpendicular and resilient.

2. An injection device according to claim 1 , wherein the support ribs (62) are tangentially shaped to engage the glass cartridge (40) tangential to the circular cross section of the cylindrical main portion of the glass cartridge (40).

3. An injection device according to claim 2, wherein the tangential shaped support ribs (62a) are simultaneously bended and plastically deformed by engagement with the glass cartridge4. An injection device according to any of the claims 1 to 3, wherein the two parts of the cartridge enclosure are connected together preferably by a threaded connection (12, 63).

5. An injection device according to claim 4, wherein one part of the cartridge enclosure comprises the distal support structure (11) and the other part of the cartridge enclosure comprises the proximal support structure (61).

6. An injection device according to claim 4 or 5, wherein a housing structure (10) of the injection device comprises the one part comprising the distal support structure (11).

7. An injection device according to any of the claims 4, 5 or 6, wherein a nut element (60) of the injection device comprises the other part comprising the proximal support structure (61).

8. An injection device according to any of the claims 4 to 7, wherein the two parts are connected by a threaded connection (12, 63).

9. An injection device according to any of the claims 3 to 8, wherein the tangential shaped support ribs (62a) engaging the glass cartridge (40) tangential are folded further tangential by engagement with the glass cartridge (40).

10. An injection device according to any of the previous claims, wherein the tangential shaped support ribs (62a) points in the same tangential direction as the thread connection (12, 63).

11. A two-part cartridge enclosure for enclosing a glass cartridge,Wherein the glass cartridge (40) has a circular cross section around a longitudinal axis (X) with a distal outlet portion having a distal neck portion with a circumferential shoulder portion (42), and a cylindrical main portion having a proximal end portion with an opening surrounded by a proximal circumferential rim (43),The two-part cartridge enclosure further comprises:A first distal part comprising a distal support structure (11) engaging the circumferential shoulder portion (42) of the glass cartridge and being adapted to support the cartridge (40) in the distal direction, andA second proximal part comprising a proximal support structure (61) engaging the proximal circumferential rim (43) of the cartridge (40) and being adapted to support the glass cartridge (40) in the proximal direction,The glass cartridge (40) thereby being axially secured in the two-part cartridge enclosure between the distal support structure (11) and the proximal support structure (61),The proximal support structure (61) comprising support ribs (62) pointing inwardly into the cartridge enclosure to engage the proximal circumferential rim (43) on the cylindrical main portion of the glass cartridge (40),Characterized in that, the support ribs (62) are nonperpendicular and resilient.

12. A two-part cartridge enclosure according to claim 11 , wherein the support ribs (62) are tangential shaped to engage the cartridge tangential to the circular cross section of the cylindrical main portion of the glass cartridge (40).

13. A two-part cartridge enclosure according to claim 12, wherein the tangential shaped support ribs (62a) are simultaneously bended and plastically deformed by engagement with the glass cartridge (40).

14. A two-part cartridge enclosure injection device according to any of the claims 11 to 13, wherein the first distal part and the second proximal part are connected together preferably by a threaded connection (12, 63).

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