Patent Application
20210128836
The present invention relates to injection devices for injecting a medicament. In particular the present invention relates to a power unit for use in an autoinjection device having a releasable plunger, a click arm, and a radially protruding click protrusion on the plunger to generate a click during expelling. The present invention further relates to a method of obtaining a simplified process for assembling such device.
In relation to some diseases patients must inject a medicament on a regular basis such as once weekly, once daily or even a plurality of times each day. In order to help patients administering one or more doses of a medicament injection devices, such as autoinjectors, are widely used. Some injection devices generate feedback signals to signify certain operational states during operation of the device. For example, injection devices may generate one or more click sounds during the expelling procedure, signalling initialisation, finalization or progression of the expelling. References WO 2012/022810, WO 2016/089871 and WO 2017/191159 all provide disclosure of such devices wherein sound activating geometries associated with a plunger cooperate with additional elements for generating click sounds as the plunger is driven forward.
Typically, during manufacturing of injection devices, smaller or larger sub-assemblies of components are initially formed which are subsequently interconnected or coupled with additional components. Autoinjectors, such as disclosed in U.S. Pat. No. 6,099,503 and WO 2017/191159, may include a power unit comprising a drive spring which is brought in an energized state providing a force for driving forward a plunger, wherein the drive spring is arranged in a pre-strained state during an early assembly step. As click sounds typically are generated by having a click element rapidly snapping during forward movement of the plunger relative to the click element this condition typically makes the movement possible only in the expelling direction. Hence, inclusion of click sound generating elements in such devices typically lead to an increase in complexity both having regard to the number of components, and to the number of assembly steps when manufacturing the autoinjector.
Having regard to the above-identified prior art devices, it is an object of the present invention to provide a power unit for use in an autoinjector which is less complex and wherein the assembly procedure for forming the power unit, and ultimately the autonijector, is simplified.
In a first aspect the present invention relates to a power unit for use in an autoinjector, the power unit being configured for driving a plunger distally along an axis in an expelling movement so as to expel a drug from a held drug container, the power unit comprising:
By configuring the straining surface geometry of the click arm to be engaged with a tool during an assembly step, the click arm may be strained by being brought sufficiently out of reach relative to cooperating elements of the plunger to enable the plunger to be moved proximally relative to the power base during tensioning of the drive spring. In prior art devices, click elements, such as click arms that cooperate with protrusion elements to create click sounds typically dictates one-way movement between the click arm and the cooperating protrusions which implies a particular way of orienting and moving the implied components during assembly. For example, in prior art devices wherein additional components are used, the plunger will be initially arranged relative to the click arm so that the plunger approaches the click arm from the proximal side of the click arm, i.e. the plunger is moved distally relative to the click arm. This implies a pronounced simplification of the assembling procedure and enables the autoinjector to be more cost effectively provided.
In certain embodiments, each of the surfaces of the trailing surface pair comprises an abrupt sloping surface, whereas at least one of the surfaces of the leading surface pair comprises a gradually sloping surface. In some embodiments, one of the surfaces of the leading surface pair comprises abrupt sloping surface whereas in other embodiments, both the surfaces of the leading surface pair comprise a gradually sloping surface. In certain embodiments, each of the surfaces of the trailing surface pair comprises an abrupt sloping surface. Exemplary embodiments may include surfaces of the trailing surface pair being arranged substantially orthogonal to the axis, such as being arranged with in inclination angle larger than 70 degrees, preferably larger than 80 degrees, and more preferably larger than 85 degrees relative to the axis. The abruptly sloping surfaces of the trailing surface pair ensures that a particularly powerful click sound is generated each time the click arm passes a radially protruding click protrusion of the plunger.
In some embodiments, the click arm assumes a first relaxed radially inwards located position when not being acted upon by other components. In such embodiments, the click arm is movable into a tensed second radially outwards located position, such as when being acted upon by the one or more radially protruding click protrusions of the plunger, and when acted upon by the tool.
In some embodiments, the straining surface geometry of the click arm includes a distally oriented inclined surface having a surface normal inclined relative to the axis so that the surface normal intersects with the axis, and wherein said tool includes a reaction surface so oriented that, in the preparing step, the reaction surface engages the distally oriented inclined surface of the click arm thereby forcing the click arm to move radially outwards as the tool is moved proximally relative to the power base. A particularly simple construction is thereby obtained.
In other embodiments the straining surface geometry of the click arm includes a surface geometry, such as a stepped surface arranged at distal facing surface, wherein the stepped surface is engageable by a tool, and wherein the tool forces the click arm radially outwards as it cooperates with a non-circular outwards facing tool surface, in the course of the tool being rotated around the axis from a first rotational position wherein the click arm is in a radially inwards relaxed state and into a second rotational position wherein the click arm is in a radially tensed state.
In some embodiments the power unit further comprises a trigger element being movable relative to the power base between a first position and a second position, wherein, when the trigger element assumes the first position, the trigger element engages with the one or more retaining elements to maintain retaining engagement between respective ones of the one or more retaining elements and the one or more retaining geometries of the plunger. When the trigger element assumes the second position, the trigger element allows the one or more retaining elements to release said retaining engagement allowing the plunger to move distally.
In some embodiments the plunger comprises a spring seat, and wherein the drive spring is a compression spring having the second end of the drive spring grounded by the power base and the first end providing a distally directed force on the spring seat of the plunger.
In further embodiments the power base further comprises a distally facing spring seat arranged to receive the second end of the drive spring. In some embodiments, the spring seat and the click arm of the power base are formed as a unitary component, such as being molded in a molding process.
In still further embodiments, the power base is formed to define a closed proximal end cap configured for being coupled to the proximal end of a sleeve shaped housing of the autoinjector. The power base may in certain embodiments include a sleeve shaped power base housing that is formed to encircle at least a proximal end portion of the plunger and at least a proximal end portion of the drive spring, where the sleeve shaped power base housing is formed to protrude axially in the distal direction from the closed proximal end cap and extending further distally than the one or more retaining elements. In accordance with the first aspect, the power base housing is shaped with a passage so as to allow the said tool to be axially inserted radially within the power base housing but radially outside the plunger and the drive spring to enable engagement with the straining surface geometry of the click arm. In some embodiments, the power base housing includes guiding surfaces adapted for guiding the trigger element as it moves relative to the power base between the first position and the second position.
In further embodiments the click arm is formed in one piece with a transverse section forming a distally facing spring seat arranged to receive the second end of the drive spring. By forming the click arm and the spring seat as a unitary component, the power unit and the assembling procedure for preparing the power unit may be simplified and enables a more cost-effective and robust power unit to be provided.
In further embodiments, the power base of the power unit comprises a transverse section and a spring guide that is arranged to extend axially in distal direction relative to the transverse section, the spring guide and/or the transverse section defining a distally facing spring seat that receives the second end of the drive spring, and wherein the click arm is formed in one piece with the transverse section and/or the spring guide.
In other embodiments, the power base defines a distal facing spring seat that receives the second end of the drive spring, and wherein the power base defines a single unitary component having the spring seat formed in on piece with the click arm, and optionally, formed in one piece with the one or more retaining elements. In some embodiments, the spring seat of the power base is arranged distally to the one or more retaining elements. In other embodiments, the spring seat of the power base is arranged proximally relative to the one or more retaining elements.
In still further embodiments the power base comprises a transverse section and a spring guide that extends distally from the transverse section, the spring guide and the transverse section defining a distally facing spring seat arranged to receive the second end of the drive spring.
In some embodiments the spring guide is formed in one piece with the transverse section to form a distally facing cavity coaxially receiving the second end of the drive spring. In other embodiments, the spring guide is formed in one piece with the transverse section, and wherein the spring guide defines a rod-shaped element configured to be received coaxially within the drive spring.
In further embodiments, the said click arm provides a first click arm and wherein the power base comprises one or more additional click arms configured similarly to the first click arm to cooperate with click protrusions of the plunger, and wherein the plurality of click arms are arranged symmetrically around the plunger. The number of click arms may in different embodiments be one, two, three, four or more individual click arms. The click arms may in certain embodiments be provided as axially extending arms which generally runs parallel with the axis. In certain embodiments, each of the click arms extends distally from a proximally arranged transverse section. In other embodiments, each of the click arms extends proximally from a distally arranged tubular section of the power base.
In some embodiments respective ones of the one or more retaining elements, such as being provided as retaining arms, is defined by one of said click arms. In other embodiments the one or more click arms are formed individually from the one or more retaining elements.
In some embodiments the plunger is hollow, wherein the drive spring is a compression spring, and wherein the compression spring extends at least partly into the hollow plunger. In other embodiments, the drive spring is provided as a helical compression spring arranged to encircle at least a portion of the plunger. When the drive spring of the power unit is arranged in the tensed state, the compression spring is arranged in a compressed state and thus urges the ends of the drive spring away from each other.
In further embodiment, the power unit is coupled with a housing, and with a drug container to provide an autoinjector. In still further embodiments, the power base defines a proximal end cap to be received within a sleeve formed housing at the proximal end thereof.
In a second aspect, the invention relates to a method of preparing, such as assembling, a power unit as defined in any of the embodiments described in connection with the first aspect mentioned above. The method comprises the steps of:
In some embodiments, the method of preparing a power unit is characterized in that, in step d), the second tool part includes a reaction surface configured to engage said straining surface geometry of the click arm with the distally oriented inclined surface, and wherein, in step e), due to the engagement between the distally oriented inclined surface with the reaction surface, the click arm moves radially into a tensed state to enable the plunger to be moved proximally while allowing the surfaces of said trailing surface pair to pass each other.
The second tool part may in some embodiments the first and second tool parts are arranged distally relative to the click arm of the power base. The tools may be so formed that the second tool part includes an opening through which the plunger may protrude.
In some further embodiments, the method further comprises the steps of:
In further embodiments, the power unit according to the first aspect and the power unit prepared by the method according to the second aspect may include any of the features and combination of features disclosed in the following.
In some embodiments, the autoinjector is configured for expelling a dose of drug from a held drug container, the injection device comprising:
As the energy source acts to force the memory element to move into the fired position the autoinjection device becomes less dependent on tolerance variations so that the correct functions of a secondary function controlled by the position of the memory element becomes more reliable. In addition, the movement of the memory element into the fired position means that the movement of the memory element becomes less dependent on how the user operates the device.
In some embodiments, the memory element, when assuming the fired position, controls a secondary function of the autoinjection device, wherein said secondary function is distinct from the function associated with the release of the plunger, i.e. the release being provided by the retaining element being moved in the radial direction to release the engagement with the retaining geometry of the plunger. A non-exhaustive list of secondary functions may include one or more of controlling initialisation or generation of a feedback signal, i.e. conditional to the release of the plunger, such as a visible, audible or tactile signal, or generation of an electronic signal to be recorded or stored in electronic circuitry, wherein the electronic signal is responsive to the release of the plunger. Still other secondary functions may include a latch function, such as for locking a needle shroud in a particular position, i.e. conditional to the release of the plunger.
In some embodiments the memory element is axially movable, and wherein said at least one surface is inclined relative to said radial direction and so oriented as to induce axial movement of the memory element from the firing position to the fired position upon radial movement of the retaining element.
In other embodiments the memory element is rotationally movable, and wherein said at least one surface is inclined relative to said radial direction and so oriented as to induce rotation of the memory element from the firing position to the fired position upon radial movement of the retaining element.
In some embodiments the retaining element includes a retaining surface that engages a cooperating surface of the retaining geometry to retain the plunger in the pre-firing position, and wherein one or both of the retaining surface and the cooperating surface include(s) a surface being inclined relative to said radial direction so that distal movement of the plunger, upon initial release of the retaining engagement, induces radial movement of the retaining element to disengage the retaining surface from the cooperating surface of the retaining geometry.
In some embodiments the trigger element assumes a pre-firing position when the trigger element assumes the pre-firing condition, and assumes a firing position when the trigger element assumes the firing condition, and wherein the trigger element cooperates with the retaining element to initiate release of the retaining engagement when the trigger element assumes the firing position.
In some embodiments the trigger element defines said memory element, and wherein the trigger element is movable from the pre-firing position to the firing position, and further to the fired position.
In some embodiments, the trigger element is movable axially from the pre-firing position to the fired position, such as movable proximally from the pre-firing position to the fired position. In some embodiments, the firing position is positioned at an intermediary position between the pre-firing position and the fired position.
In other embodiments, the trigger element is rotationally movable from the pre-firing position to the firing position. In some embodiments wherein the trigger element defines said memory element the trigger element is rotationally movable from the pre-firing position to the firing position, and further rotationally movable into the fired position. In these embodiments, the at one or both of the engagement surface and the activation surface include(s) a surface being inclined relative to said radial direction and being so oriented that radial movement of the retaining element induces rotation of the trigger element. The sequence of the rotation is initiated by the user which initially drives the trigger element to rotate from the pre-firing position to the firing position. Thereafter, the trigger element is in the first place urged to move by distal movement of the plunger, as forced by the energy source, which in turn induces radial movement of the retaining element, and which in turn induces rotation of the trigger element from the firing position to the fired position.
Some embodiments of the autoinjection device comprises a needle shroud being axially movable relative to the housing, and a needle shroud spring which is arranged biasing the needle shroud in the distal direction, wherein the needle shroud is movable from a first distal extended position into a proximal collapsed position when a proximally directed force is applied to the needle shroud, and from the proximal collapsed position into a distal extended locked position, and wherein the trigger element couples to the needle shroud so that the trigger element moves from the pre-firing position to the fired position in response to the needle shroud being moved from the first distal extended position into the proximal collapsed position.
In some embodiments, the first distal extended position is the same as the distal extended locked position. In other embodiments, the first distal extended position may be located distally or proximally relative to the distal extended locked position. The distal extended locked position defines a state wherein the needle shroud protects the needle from being touched by the user. The proximal collapsed position defines a state wherein the needle extends distally beyond the needle shroud, or where the needle is positionable to extend distally beyond the needle shroud, to allow for insertion of the needle into an injection site.
The needle shroud may be configured so that when it moves from the first distal extended position towards the proximal collapsed position the needle shroud causes the trigger element to move from the pre-firing position into the fired position, the needle shroud slaving the trigger element into the firing position, and optionally into the fired position.
In some embodiments a latch is associated with the trigger element, the latch engaging when the trigger element assumes the fired position to arrest the trigger element in the fired position.
The latch may in some embodiments be provided by cooperating latch geometries of the trigger element and the housing to prevent the trigger element from being moved distally away from the fired position. In other embodiments the latch is configured to rely on a frictional coupling, such as a frictional engagement, between the trigger element and the housing to prevent the trigger element from being moved distally away from the fired position. In some embodiments the latch is configured to provide a permanent axial locking of the trigger element relative to the housing when the trigger element assumes the fired position.
In some embodiments, when the needle shroud moves from the proximal collapsed position into the distal extended locked position, the needle shroud moves relative to the arrested trigger element, and wherein the needle shroud cooperates with the trigger element to lock the needle shroud as the needle shroud is moved distally into the distal extended locked position.
In some embodiments at least one of the needle shroud and the trigger element comprises a lock element which is resiliently urged towards the other of the needle shroud and the trigger element to move along relative to a surface of said other of the needle shroud and the trigger element when the needle shroud moves relative to the arrested trigger element until the lock element reaches a locking geometry formed in or on said other of the needle shroud and the trigger element upon the needle shroud being moved distally into the distal extended locked position so as to lock the needle shroud in the distal extended locked position.
In some embodiments the trigger element includes a distally directed lock surface configured to engage a proximally directed locking geometry of the needle shroud to prevent the needle shroud to be moved proximally when the needle shroud assumes the distal extended locked position.
In some embodiments the distally directed lock surface is formed on a resiliently movable lock element being movable from a non-locking position into a locking position, and wherein a biasing means urge the resiliently movable lock element towards moving to the locking position, and wherein the resiliently movable lock element is moved from the non-locking position into the locking position upon the needle shroud being moved from the proximal collapsed position into the distal extended locked position.
In some embodiments the resiliently movable lock element is configured to slide along a sliding surface of the needle shroud as the needle shroud is moved from the proximal collapsed position into the distal extended locked position for the distally directed lock surface of the trigger element to axially align with the proximally directed locking geometry of the needle shroud to enable the distally directed lock surface to engage with the proximally directed locking geometry.
In some embodiments the resiliently movable lock element is structured as a lock sleeve.
Some embodiments of the autoinjector forms a device wherein the energy source comprises a helical compression spring arranged in a pre-tensed state exerting a distally directed force on the plunger.
In further embodiments a latch is associated with the memory element, the latch engaging when the memory element assumes the fired position to arrest the memory element in the fired position.
The latch may in some embodiments be provided by cooperating latch geometries of the memory element and the housing to prevent the memory element from being moved distally away from the fired position. In other embodiments the latch is configured to rely on a frictional coupling, such as a frictional engagement, between the memory element and the housing to prevent the memory element from being moved distally away from the fired position. In some embodiments the latch is configured to provide a permanent axial locking of the memory element relative to the housing when the memory element assumes the fired position.
In some embodiments of the autoinjector, the device irreplaceably accommodates a container within the housing so that the container cannot be removed from the device without the use of tools. In such embodiments, the autoinjector forms a disposable device.
In some embodiments the container is provided as a syringe having a barrel and with an injection needle fixedly attached to the barrel.
In embodiments incorporating a cartridge and a separate needle unit, the cartridge and the needle unit may be initially held in a configuration where the cartridge and the needle unit are separated by a distance. The energy source may be capable, upon release of the plunger retaining arrangement, to cause the cartridge and the rear needle to enter into the state where the cartridge septum is pierced by the rear needle and subsequently to cause the plunger to move to dispense the drug through the needle.
In some embodiments the needle or needle unit substantially follows movement of the housing as the housing moves relative to the needle shroud. In particular embodiments, the needle or needle unit is attached to the housing in a way preventing relative axial movement between the housing and the needle.
As used herein, the term “drug” is meant to encompass any drug-containing flowable medicine or combinations of separately held plurality of drug-containing flowable medicines capable of being passed through a delivery means such as a cannula or hollow needle in a controlled manner, such as a liquid, solution, gel or fine suspension.
The invention will now be described in further detail with reference to the drawings in which:
In the context of the present disclosure 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 which carries the injection needle whereas the term “proximal end” is meant to refer to the opposite end of the injection device pointing away from the injection needle. The shown figures are schematical representations for which reason the configuration of the different structures as well as the relative dimensions are intended to serve illustrative purposes only.
The following is a description of an exemplary embodiment of a medical injection device 10 for administering a pre-determined amount of a liquid medicament. The device 10 is a disposable autoinjector configured for expelling a dose of a drug in a single administration whereafter the device 10 is ready for disposal.
Referring to
At the distal end of the housing 300 a protective cap (not shown) will normally be arranged to cover a needle arrangement located at the distal end of the housing.
In the shown embodiment, the housing 300 accommodates a standard prefilled syringe (PFS) as widely used in industry. The syringe 100 comprises a tubular barrel 110 having a neck portion 115 located distally wherein the neck portion 115 has a reduced diameter compared to the diameter of the barrel 100. An injection needle 130 is mounted to the neck portion 115 and a removable cap (not shown) provided in the form of a rigid needle shield (RNS) will prior to use be attached to the neck 115 so that the needle shield sealingly and sterilely seals off the needle 130 Internally in the barrel 110 a slideably arranged piston 120 is arranged. A drug may be accommodated within the barrel between the piston 120 and the needle 130. Although the shown syringe only incorporates a single piston 120, other configurations may incorporate multiple pistons for accommodation and expelling of one or more drugs, including drugs to be reconstituted before administration. In other not shown embodiments, instead of a PFS type syringe, the housing may alternatively include other types of medicament containers, such as cartridges configured to receive a separate injection needle.
Injection device 10 will typically be available in a form which further includes a removable protective cap (not shown) that attaches to a distal end of the device 10 to protect a needle end of the device 10. As commonly known for auto-injectors that incorporate a PFS syringe having an RNS shield attached, the protective cap may couple to the RNS so that the RNS is removed together with the protective cap. This situation is depicted in the state shown in
In the shown embodiment, a syringe holder 200 is arranged to hold syringe 100 inside housing 300 in a manner so that syringe 100 is fixedly withheld within the housing 300 by means of the syringe holder 200. Syringe holder 200 includes a body extending along a central longitudinal axis and being adapted to receive the barrel 110 of syringe 100. The body of the syringe holder 200 includes two longitudinal body sections disposed around the central longitudinal axis, where each of the body sections has a distal end with a radial inwards flange section 250 adapted for being received in a circumferential gap between the shoulder section 150 of barrel and the not shown RNS covering the needle. In this way the syringe holder 200 retains the syringe 100 so as to prevent the syringe from moving distally relative to the syringe holder 200. The two longitudinal body sections of syringe holder 200 are connected to each other by means of flexible portions allowing the two body sections to be radially moved away from each other in order to insert the syringe with the RNS attached into syringe holder 200. During manufacture, the assembly formed by the syringe holder and the syringe with the RNS attached is insertable into housing 300 through a proximal opening in the housing shell.
The lower distal half of the housing 300 includes two opposing window openings 310 allowing visual inspection of the drug contained within the syringe of the device 10. In addition, window openings 310 allow a user of the device to determine whether or not the device 10 has been used for an injection by inspecting the presence or the location of a piston of syringe 100. In the course of an injection, window openings 310 also allow for a rod-shaped plunger 500 of the device to become increasingly visible by the plunger gradually blocking more and more of the space between window openings 310.
The injection device 10 is configured for being triggered to expel a dose when the needle shroud 600 is moved from the distal extended position towards the proximal collapsed position. As the syringe 100 is substantially fixedly mounted within housing 300 of the device 10, the injection needle 130 follows axial movement of the housing when the housing is moved relative to the needle shroud 600.
The protective cap, when attached to injection device 10, prevents the needle shroud 600 from being manipulated and thereby prevents premature unintentional triggering of the injection device 10. In the shown embodiment, this function may be provided by a mechanism incorporating radially flexible arms 330 formed in the housing, the flexible arms having heads 335 formed at an internal location in the housing 300 arranged to cooperate with an internal skirt 635 provided inside the needle shroud 600. The heads 335 and skirt 635 are located at the same radial position. Thus, for the needle shroud 600 to become pushed proximally relative to housing 300, the flexible arms 330 with heads 335 are required to become deflected radially inwards by cooperating with skirt 635 before the skirt and thus the entire needle shroud is movable away from the distal extended position. As long as the RNS and/or the protective cap is still attached to the syringe the flexible arms 330 with heads 335 are initially blocked against moving radially inwards by the presence of the RNS. The skirt 635 is thus not able to axially pass the heads 335. Only after removal of the protective cap with the RNS and forcing the needle shroud 600 towards the proximal collapsed position the heads will cooperate with skirt 635 to move the heads radially inwards and allow the skirt 635 to pass the heads of the flexible arms (cf.
Piston 120 is driveable towards the needle outlet in order to dispense medicament from the syringe 100. The dispensing is carried out by an expelling assembly incorporating the plunger 500 and a pre-stressed drive spring 550.
In the shown embodiment, the needle shroud 600 forms a distal portion and a proximal portion. The distal portion is provided as a generally hollow tubular member having a distal end rim arranged to form an abutment surface, the tubular member initially covering the injection needle 130. The proximal portion of the needle shroud 600 forms two opposed axial running legs extending from the distal portion and in the proximal direction for a substantive part of the length of the housing. Each of the two opposed axial running legs ends in a proximally facing abutment surface 611. The needle shroud 600 with its two legs is shaped to be accommodated within the housing 300 with the radial outer surface of the needle shroud being in intimate but slideable contact with a radially inwards facing cylindrical surface of the housing shell.
The needle shroud 600 cooperates with a trigger element 700 which is located at the proximal end of the needle shroud 600. Trigger element 700 serves as a memory element which assumes a first distal position prior to use of the device 10, and which assumes a second proximal pre-defined parked position after the device 10 has been fully triggered, and wherein the memory element stays in the parked position subsequent to triggering. In the shown embodiment the trigger element both serves as a trigger sleeve, and also serves as a lock sleeve for the needle shroud. For accommodating both functions, the trigger element 700 is movable axially in the proximal direction relative to the housing 300 from a pre-firing position (
In the shown embodiment, both the needle shroud 600 and the trigger element 700 are mounted in a way that prevents rotational movement but allows axial movement relative to the housing 300. The needle shroud 600 is urged in the distal direction by means of the needle shroud spring 650 so that when no externally applied force is exerted on the needle shroud, the needle shroud assumes its distal extended position which is shown in
As the device 10 is removed from the injection site, the needle shroud 600 will move distally due to the force from the needle shroud spring 650. After an injection has been performed, as the needle shroud 600 reaches its distal extended position again, as shown in
The needle 130 of syringe 100 is arranged at the distal end of the housing 300, such that the needle shroud 600 completely covers the needle when the needle shroud is in its distal extended position. When the needle shroud 600 is in its proximal collapsed position, the needle 130 protrudes through a central opening in the needle shroud 600.
The expelling assembly of injection device 10 is based on a plunger that is driven in the distal direction along the central longitudinal axis of the device for advancing the piston 120 to thereby expel the dose of drug accommodated within the syringe 100. The plunger 500 in the shown embodiment forms a solid rod having a circular flange arranged at the distal end of the plunger. In device 10 with the rod-shaped plunger 500 arranged along the central axis, a stored energy source in the form of a pre-stressed helical compression drive spring 550 is arranged to encircle the plunger rod 500 along a portion of its length. Drive spring 550 is energized by straining the compression spring during manufacture of the device. The distal end of drive spring 550 is supported onto plunger 500 by a circular flange arranged at the distal end of the plunger. The proximal end of drive spring 550 is supported by a spring seat (non-referenced) formed at a distal end of power base 400 and thus grounds the proximal end of drive spring relative to the housing 300.
As mentioned, in the shown embodiment, the drive spring 550 urges the plunger 500 in the distal direction. In the non-triggered state of the injection device 10, a plunger retaining arrangement associated with the housing engages with a retaining geometry of the plunger to retain the plunger 500 in a pre-firing position. In the shown embodiment, and referring to 1a,
The plunger retaining arrangement further comprises two retaining elements in the form of two retaining arms 410 extending axially in the distal direction from the proximal portion of the power base 400. Each of the two retaining arms 410 forms a radially resilient arm that ends in an enlarged blocking head 415 having its radially inwards facing portion situated in the recessed portion of the plunger rod 500. Generally referring to
Referring to
As shown in
Alternatively to using a pre-stressed spring which is compressed during manufacture of the device, other embodiments of autoinjectors may include a mechanism for compressing the spring as an initial procedure when putting the device into use. Also, the energy source may in other embodiments be provided as a torsion spring which is pre-stressed to exert a torsion force for driving forward a rotational drive of the expelling assembly. Alternatively, the energy source may be in the form of a compressed medium such as a gas. Still alternatively, the energy source may include a gas generator such as an electro-chemical cell.
Referring again to
In the following, the components that relate to the needle shroud lock function will be further described. Referring back to
The needle shroud lock function further incorporates the power base 400. Power base 400 additionally includes two independent flexible arms 430 each extending in the distal direction from the power base. Each flexible arm is biased radially outwards so that a latch head 435 provided at the free distal end of the flexible arm assumes the position shown in
As shown in
When the device 10 is removed from the injection site S the needle shroud spring 650 forces the needle shroud 600 from the proximal collapsed position into the distal extended locked position. During this movement, the proximally facing abutment surfaces 611 of the legs of the needle shroud initially moves out of engagement with the distal abutment surfaces 721 of the trigger element 700. Continued distal movement makes the legs of the needle shroud slide along the trigger element 700 until the proximally facing abutment surfaces 611 axially align with the distally directed lock surfaces 731 of the deflectable arms 730. Due to the radially outwards biased force from the flexible arms 430 onto the cooperating deflectable arms 730, the deflectable arms 730 are forced to move radially outwards into their locking position. As a consequence, the distally directed lock surfaces 731 of the deflectable arms 730 enter into blocking position relative to the proximally facing abutment surfaces 611 of the legs of the needle shroud 600 and the needle shroud 600 is prevented from moving towards the proximally collapsed position after the device 10 has been triggered.
Returning now briefly to details which relate to the triggering procedure of injection device 10 wherein the needle shroud 600 and the trigger element is moved in the proximal direction relative to the housing 300. Due to the profiled nature of axial tracks 736 the latch heads 435 initially climb a steep portion of the profiled axial tracks 736 (climb meaning move in the radial direction). This creates an initially high force which has to be overcome by the user when pushing device 10 against an injection site S to make the needle shroud 600 move towards the proximal collapsed position.
When the trigger element 700 is moved from the distal extended position towards the proximal collapsed position the two flexible arms 430 and the corresponding profiled axial tracks 736 of the trigger element 700 provide resistance to movement of the trigger element 700 and thus also resistance to movement of the needle shroud 600. Upon applying the autoinjector 10 at an injection site, a high axial reaction force is initially created when the flexible arms 430 engage the proximal end portion of the profiled axial tracks 736. Thus, a high force exerted on the needle shroud 600 is required in order for the flexible arms 430 to climb the profiled axial tracks 736. As soon as the flexible arms 430 have climbed the profiled axial tracks 736, resulting in the flexible arms 430 have been deformed radially inwards, the flexible arms 430 travel and slide along an almost constant height track profile as the needle shroud 600 is pushed further proximally relative to housing 300. This action requires considerable less force to be applied on the needle shroud 600 than the initial high force. Hence the needle shroud displacement will occur in two stages, i.e. a first high force stage and a second low force stage.
It will be appreciated, that the force needed for proximally displacing the needle shroud will be largely independent from the force provided by the drive spring but will rather be decided by the force of the needle shroud spring 650 and the force profile for the interaction between the flexible arms 430 and the profiled axial tracks 736. A further minor force which has to be overcome when pushing in the needle shroud 600 emanates from the flexible arms 330 of the housing cooperating with the inner tubular proximal rim 635 of the needle shroud 600, cf. the discussion mentioned above with respect to the removal of the protective cap/RNS.
As will be discussed further below, the above-mentioned firing position of trigger element 700, and the corresponding position of needle shroud 600, will be situated at the final part of the proximal needle shroud movement where the flexible arms 430 travel along the almost constant height profile of axial tracks 736. The high initial needle shroud force over a short distance assures that the needle shroud is fully displaced and the autoinjector is effectively triggered due to the inertia of the human motion.
Referring now to
The power unit 15 is provided as an assembly of components which in the shown embodiment is made up by the following components: plunger 500, drive spring 550, power base 400 and trigger element 700. Once assembled to form a power unit the power unit 15 serves as a pre-assembled and pre-energized drive assembly to be inserted into housing 300 as part of assembling the pre-filled syringe 100 with the remaining components of injection device 10. The power unit 15, even though it holds the drive spring 550 in a compressed state, forms a stable assembly where the trigger element maintains the retaining elements of the power base securely engaged with the corresponding retaining surfaces of the plunger during storage and handling of the energized power unit.
Referring to
The second tool part 20 further includes a generally cylindrical outer surface defined by the radially outer surface of the pair of arms 25 and an outer cylindrical tool portion (non-referenced). The latter parts are so shaped that a trigger element 700 can be held in a way that the radially outer surface of the pair of arms 25 is received within a held trigger element 700.
During assembly, in
As shown in
In the shown embodiment, in a sixth step shown in
As shown in
As a ninth step, the trigger element 700 is moved proximally relative to the power base 400 into a position where the trigger element surrounds the enlarged blocking heads 415 of the resilient arms 41. In this position the radially outwards bias of resilient arms 410 emanating from the compressed drive spring 550 creates friction for retaining the trigger element in the pre-firing position referred to above in connection with
Finally, as shown in
It is to be noted that the above described embodiment where the principle of moving the resilient arms 410 outwards during assembly provides only one suitable mechanism for obtaining this process step. In alternative embodiments, as examples in accordance with the present invention, the distal facing surfaces 415d of enlarged blocking heads 415 may be provided with differently shaped surface geometries than the shape shown in
It is also to be noted that, although the shown embodiment shows an embodiment wherein the resilient arms 410 form click arms, thus serving both the function of retaining the plunger prior to firing as well as providing clicks during expelling, other embodiments may be provided wherein click arms are formed separately from retaining elements, such as separately from retaining arms. The instant invention may be utilized both for ensuring that click arms and/or retaining arms are tensioned radially outwards during an assembly step by using a suitable tool in a manner as disclosed above.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18176176.8 | Jun 2018 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/064737 | 6/5/2019 | WO | 00 |
