Dosing and dispensing mechanism for an injection device

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of medical injection devices for administering liquid substances, in particular medicaments or medicinal substances such as insulin and hormone preparations. The invention relates to an injection device with a dosing and dispensing mechanism. BACKGROUND OF THE INVENTION

[0002] Known injection devices typically comprise a drive sleeve for driving a piston rod to dispense the liquid substance from a carpule or product container, an actuating element or dosing element for setting a dose to be administered, and an element for displaying the set dose.

[0003] To set a dose, the user turns or pulls the actuating or dosing element, which then screws or moves out of the housing of the injection device. To dispense the set dose, the user presses directly on the actuating element or on a dispensing button at a proximal end of the injection device and generates a force in the distal direction, whereby the actuating element is screwed or pushed into the housing. In contrast to setting a dose, when dispensing the actuating element transfers the rotating or sliding movement to the drive sleeve, which then drives the piston rod and dispenses the substance from the carpule. Depending on the design, the piston rod is mounted so that it can rotate or only move relative to the housing.

[0004] To correct an inadvertently over-adjusted dose, the user can rotate or push the actuating element back into the housing. During this corrective movement, as well as when handling the injection device between administrations, it is important to ensure that the position of the plunger rod cannot be accidentally adjusted relative to the cartridge, especially that the plunger rod does not move away from the cartridge.

[0005] One way to prevent accidental adjustment is to use a so-called anti-reverse device. This either directly prevents the piston rod from rotating in the opposite direction to the direction of rotation required to discharge the substance, or the anti-reverse device engages the driving element, indirectly preventing the piston rod from moving backward.

[0006] Alternatively, unintentional adjustment of the piston rod can be prevented by means of a self-locking mechanism in the thread, especially if the piston rod has several threads with different pitches.

[0007] For example, the piston rod can have a left-hand thread that engages the drive sleeve and a right-hand thread that engages the housing. In this case, if the left-hand threaded drive sleeve is unscrewed when setting a dose, the piston rod will not move relative to the housing because it engages the right-hand thread. Securing the piston rod with different threads has the advantage that no special elements, such as a ratchet, are needed to prevent unwanted rotation of the piston rod. Furthermore, no additional force is required when dispensing to overcome the frictional resistance of a securing element, such as a ratchet.

[0008] WO 2014 / 033195 discloses a reusable injection pen with a piston rod comprising a first and a second, opposing thread. The piston rod is screwed into the housing using the first thread. A drive sleeve is in threaded engagement with the second thread. The injection pen also comprises a click mechanism with a distal and a proximal click ring, each having axial teeth. When setting a dose, the teeth are moved relative to one another, producing a clicking sound. Furthermore, during setting, a dispensing button, the drive sleeve, and a dose indicator sleeve are rotationally fixedly connected to one another by means of a coupling and are screwed out of the housing. The piston rod remains immobile relative to the housing, and the drive sleeve is screwed out of the piston rod. To dispense the dose, the dispensing button is pressed.The generated axial force causes the proximal click ring, which is rotationally fixed to the housing, to be rotationally coupled to the distal click ring. This allows the drive sleeve to be moved only axially, while the dose indicator sleeve can rotate freely and is screwed back into the housing. The axial displacement of the drive sleeve rotates the piston rod and dispenses the product.

[0009] This mechanism is complex and comprises many individual parts, making manufacturing more expensive and requiring complex assembly. Furthermore, the mechanism is designed for reusable injection pens, where the plunger rod must be retractable into the housing after administration.

[0010] US 9,005,171 B2 discloses an injection pen with a reset mechanism featuring a drive sleeve that can be rotationally coupled to a coupling sleeve using fingers. The fingers can be deflected radially inward. When setting the dose, the drive sleeve, coupling sleeve, and dose-setting sleeve rotate. During dispensing, an axial movement of the coupling sleeve couples the coupling sleeve and drive sleeve to the housing via the fingers, and they are thus only axially displaced without rotating.

[0011] US 2018 / 0008783 A1 discloses a dosing mechanism for an injection pen. During dispensing, a coupling sleeve is displaced axially distally relative to a drive sleeve, and elastically deflectable arms engage grooves in the pen housing, thereby coupling the coupling sleeve to the housing in a rotationally fixed manner.

[0012] US 2016 / 0045664 A1 discloses a reusable injection pen. When setting the dose, a drive sleeve rotates and is thus screwed along a piston rod. To dispense, a dispensing button is pressed, causing a coupling sleeve to rotate, moving the piston rod in the dispensing direction, while the drive sleeve is rotationally coupled to an inner housing part. PRESENTATION OF THE INVENTION

[0013] It is an object of the invention to enable dosing and dispensing with an injection device in a simple manner and with few components.

[0014] This object is achieved by an injection device and a dosing and dispensing mechanism according to the independent claims. Preferred embodiments are the subject of the dependent claims.

[0015] According to the invention, an injection device, in particular a disposable injection device, comprises a dosing and dispensing mechanism for dispensing a dose of a product by manually advancing a piston rod into a carpule held in the injection device. This dosing and dispensing mechanism comprises a housing with a longitudinal axis, a drive sleeve arranged longitudinally displaceably in the housing for driving a piston rod, and an actuating element for setting the dose. The actuating element is rotationally fixed to the drive sleeve and is displaceable relative to the drive sleeve in the direction of the longitudinal axis. The actuating element is rotatable relative to the housing for setting the dose.The actuating element comprises a first coupling element and the housing comprises a second coupling element, wherein the first and the second coupling element can be coupled to one another for dispensing the dose, so that in the coupled state the actuating element together with the drive sleeve is connected to the housing in a rotationally fixed manner and is or remains displaceable in the direction of the longitudinal axis relative to the housing.

[0016] Single-use injection devices have different requirements than reusable injection devices. For example, single-use injection devices do not require a resettable plunger rod when the maximum dose has been dispensed from the cartridge, as the injection device is discarded after the last dispensable dose. This opens up new possibilities regarding the design of the setting and dispensing mechanism.

[0017] Because the actuating element can be coupled directly to the housing via its first coupling element and without any additional intermediate element by means of the second coupling element arranged in the housing, a simple-to-construct dosing and dispensing mechanism can be created that requires few individual parts. This means that no additional components are required for the rotary coupling of the actuating element for dispensing, as is common in the prior art (see, for example, the above-mentioned WO 2014 / 033195).

[0018] In addition, the drive sleeve, which is rotationally fixed but movable during dispensing, enables effective and simple driving of the piston rod. The axial movement of the drive sleeve can, for example, be directly translated into an axial movement of the piston rod, moving it into the carpule and dispensing the product. Alternatively, the axial movement can be increased or reduced, for example, by having the drive sleeve threaded into the piston rod and causing it to rotate, thereby screwing the piston rod in the distal direction. Depending on the pitch of the thread used to mount the piston rod in the housing, more or less feed can be achieved.

[0019] The injection device comprises a carpule containing a medicinal substance. To dispense the product from the carpule, a plunger rod of the injection device can be used to displace, for example, a plug in the carpule distally in a dispensing direction. This dispensing direction is preferably parallel to the longitudinal axis of the housing.

[0020] The dosing and dispensing mechanism comprises a housing in which the drive sleeve, the piston rod, and preferably the actuating element are arranged. This housing can simultaneously form the outer housing of the injection device, or the injection device can alternatively comprise an additional housing structure. In this case, the housing of the dosing and dispensing mechanism is preferably arranged within the housing structure of the injection device.

[0021] Furthermore, the housing of the dosing and dispensing mechanism can comprise internal elements such as a housing insert or an inner housing sleeve. Such a housing insert can, for example, rotatably support a dose indicator element and / or the drive sleeve.

[0022] To dispense a set dose, the actuating element is moved in the direction of the longitudinal axis relative to the housing by a force manually applied by the user. The drive sleeve, which is non-rotatably connected to the actuating element, is also moved in the direction of the longitudinal axis during dispensing. The drive sleeve drives the piston rod so that it moves into the carpule and the product can be dispensed from the carpule. "Manual" means that no other energy, such as a force from a pre-tensioned spring, is used for dispensing. The advance of the piston rod to dispense the product is therefore applied solely by the user. The piston rod can be rotated by the drive sleeve so that it moves in a distal direction, for example, by a screwing movement.Alternatively, the piston rod can only be moved by the drive sleeve and guided in the housing in a rotationally fixed manner.

[0023] The actuating element is rotatable relative to the housing for setting and correcting a dose. Furthermore, the actuating element is rotationally fixed to the drive sleeve and can be displaced relative to the drive sleeve along its longitudinal axis. When setting a dose, the actuating element is preferably in a first axial position relative to the drive sleeve, in which the two coupling elements are not coupled to each other.

[0024] Preferably, the actuating element also serves to start the dispensing process. A dispensing button is therefore preferably integrated into the actuating element as one piece. In other words, the actuating element preferably serves both as a dosage adjustment element and as a dispensing button.

[0025] When dispensing the dose, the actuating element is preferably in a second axial position relative to the drive sleeve, in which the two coupling elements are coupled to each other, so that the actuating element and thus also the drive sleeve are rotationally fixedly connected to the housing and can be displaced relative to the housing in the direction of the longitudinal axis. This allows the piston rod to be easily driven by the drive sleeve to dispense the dose using a manual force acting in the distal direction, which displaces the actuating element and the drive sleeve distally.

[0026] The first and second coupling elements can be selectively and releasably coupled to one another in order to connect the actuating element to the housing in a rotationally fixed manner when coupled. The coupling elements can be designed in the form of a pin and opening, a wedge and groove, intermeshing gears, or elements that interact via frictional engagement. The first coupling element is formed directly in the actuating element, integrally connected to the actuating element, and the second coupling element is formed directly in the housing, integrally connected to the housing.

[0027] In this description, the term "distal" refers to a side or direction directed toward the front, piercing-side end of the injection device or the tip of the injection needle. In contrast, the term "proximal" refers to a side or direction directed toward the rear end of the injection device, opposite the piercing-side end.

[0028] The term "axial" refers to the longitudinal axis of the housing. Accordingly, an axial direction is parallel to the longitudinal axis of the housing or in the longitudinal direction of the housing. A radial direction refers to a direction perpendicular to the longitudinal axis of the housing.

[0029] The term "product," "medicine," or "medicinal substance" in this context encompasses any flowable medicinal formulation suitable for controlled administration via a cannula or hollow needle into subcutaneous or intramuscular tissue, for example, a liquid, a solution, a gel, or a fine suspension containing one or more medicinally active ingredients. A medicament can therefore be a composition containing a single active ingredient or a premixed or co-formulated composition containing multiple active ingredients from a single container. The term particularly includes medicinal products such as peptides (e.g., insulins, insulin-containing medications, GLP-1-containing preparations, and derivatives or analogues), proteins and hormones, biologically derived or active ingredients, hormone- or gene-based active ingredients, nutritional formulations, enzymes, and other substances in both solid (suspended) and liquid form.The term also includes polysaccharides, vaccines, DNA or RNA or oligonucleotides, antibodies or parts of antibodies as well as suitable base, auxiliary and carrier substances.

[0030] In this description, the terms "injection device" or "injector" refer to a device in which the injection needle is removed from the tissue after a controlled amount of the medicinal substance has been delivered. Thus, unlike an infusion system, the injection needle in an injection system or injector does not remain in the tissue for an extended period of several hours.

[0031] A "single-use injection device," also referred to as "disposable," is a device that is disposed of after one or more injections, but at the latest after the last deliverable dose. The cartridge in such a single-use injection device is not replaceable. In contrast, with reusable injection devices, the inserted cartridge can be replaced once the product has been completely dispensed from it. With such reusable injection devices, when the cartridge is replaced, the plunger rod is pushed proximally back into the housing so that it is ready to dispense the product from the new cartridge.

[0032] The first coupling element is preferably a flexible arm which can be deflected in the radial direction. This can interact with the second coupling element in the housing, for example by engaging in a recess, groove, opening or projection in the housing. The arm is preferably elastically deflectable or deformable in the radial direction and in particular elastically bendable or flexible. This allows a rotational coupling between the actuating element and the housing to be established quickly and easily. Alternatively, the arm can be flexibly deflectable but not elastic. In this case, the arm must be moved from an initial position to a deflected position by a manually applied force or back from the deflected position to the initial position by the manual force. This deflection can be enabled via a gear surface.

[0033] The arm is preferably arranged on an outer surface of the actuating element. Furthermore, in a preferred embodiment, the actuating element comprises at least two flexible arms on its outer side, each of which can interact with a second coupling element in the housing. This can strengthen the coupling.

[0034] Alternatively, it is also possible for the first coupling element to be designed not as an arm but as a cam, rigid projection, recess or groove.

[0035] The dosing and dispensing mechanism preferably comprises a locking element with which the flexible arm can be blocked in the radial direction. After the arm has been engaged with the second coupling element, at least a portion of the arm can be blocked or fixed by means of the locking element, so that the arm can no longer move radially. This prevents the coupling between the actuating element and the housing from accidentally becoming loose. The locking element can be designed, for example, as an arm, slide, lock nut, snap element, or sleeve. The locking element is preferably arranged on the drive sleeve and, in particular, is connected to it in one piece. This enables a compact design.

[0036] In a preferred embodiment, the flexible arm can be blocked with the locking element by displacing the actuating element in the direction of the longitudinal axis relative to the drive sleeve. If the locking element is cam-shaped or ring-shaped, it can be displaced in the radial direction, for example, under the flexible arm when the latter is engaged with the second coupling element, in order to block a radial movement of the arm towards the center of the injection device. Preferably, when the user moves the actuating element in the distal direction to start the dispensing process, the actuating element is displaced relative to the drive sleeve. In this case, the arm engaged with the second coupling element is preferably blocked with the locking element so that the arm cannot disengage.This ensures a simple and secure rotational coupling of the actuating element (and thus also the drive sleeve) with the housing.

[0037] Alternatively, it is also possible to block the flexible arm with the locking element by rotating the actuating element relative to the housing, for example by screwing a lock nut over the arm.

[0038] Preferably, the second coupling element is a groove in which at least a portion of the first coupling element can be received. The groove is preferably formed in the housing along the longitudinal axis. The groove is easy to manufacture and enables rapid coupling with the first coupling element. Furthermore, the housing preferably has several grooves distributed around the circumference, so that the first coupling element can be engaged with one groove at each of the different rotational positions.

[0039] In a preferred embodiment, the groove serves both as a coupling element and as a click element for generating an acoustic and / or tactile signal when setting and correcting a dose. This is generated by moving the first coupling element over the groove. The first coupling element then engages the groove only briefly and then springs back, generating the acoustic and / or tactile signal.

[0040] Alternatively, it is also possible for the second coupling element to be designed not as a groove but, for example, as an opening, hook, rib or tooth element.

[0041] In a preferred embodiment, in which the first coupling element is designed as an arm and the second coupling element as a groove, a free end of the flexible arm can preferably interact with the groove during setting and correction of a dose in such a way that a tactile and / or acoustic signal can be generated. The signal in the form of a click and / or a vibration can be generated when the free end of the flexible arm is moved over the groove, in particular transversely to the groove, and in the process elastically deflects and springs back into it, in particular when the actuating element is rotated relative to the housing during setting and correction of a dose. The groove therefore serves on the one hand as a signal generating element and on the other hand as a coupling element.In order to secure the coupling, in this embodiment the drive sleeve preferably comprises a locking element which is movable towards the arm and can block the arm by holding at least a portion of the arm in the groove by the locking element and thereby blocking rotation of the actuating element relative to the housing.

[0042] Preferably, the housing comprises a plurality of grooves so that a movement of the arm over the grooves can generate a plurality of clicks and vibrations.

[0043] In a preferred embodiment, a non-self-locking threaded connection is provided between the drive sleeve and the piston rod, so that by displacing the drive sleeve relative to the housing, the piston rod can be rotated to dispense the dose, transmitting axial force. In this embodiment, the piston rod is also threadedly connected to the housing. Thus, the force applied by the user is transferred to the piston rod by axially displacing the drive sleeve in the distal direction, causing the piston rod to be screwed through the thread in the housing and moved distally into the cartridge.

[0044] The piston rod preferably has a first thread with which the piston rod is screwed into the housing, and a second thread which has a different pitch direction than the first thread. The drive sleeve is preferably threadedly connected to the second thread. When setting and correcting a dose, the drive sleeve can be moved up and down on the second thread of the non-rotating piston rod, while when dispensing the dose, the non-rotating drive sleeve sets the piston rod in rotation due to the axial displacement and the piston rod is screwed through the housing with the first thread. Preferably, the first and second threads not only have a different direction (sense of rotation), but also a different pitch. In this case, a step-up or step-down ratio can be achieved between the movement of the drive sleeve and the advance of the piston rod.The first and second threads are each applied to a first and a second axially extending threaded section on the piston rod, with the first and second threaded sections not overlapping, partially overlapping, or completely overlapping. The first, the second, both, or neither of the threads can be self-locking.

[0045] The housing of the dosing and dispensing mechanism preferably comprises a housing sleeve fixed to the housing, with the second coupling element being formed on the inside of the housing sleeve. The housing thus comprises an outer housing structure or outer housing sleeve and an inner housing sleeve arranged inside. "Fixed to the housing" means that the inner housing sleeve is non-rotatably and axially fixedly connected to the outer housing sleeve. The inner housing sleeve enables an advantageous arrangement of the components inside the outer housing sleeve, since components inside can be supported on the inner housing sleeve or connected to it fixedly, movably, or detachably. Furthermore, components can be mounted radially on the inner housing sleeve between an inner side of the outer housing sleeve and an outer side of the inner housing sleeve.This is particularly advantageous for rotatable elements, since lower frictional moments arise for rotation on the outside of the inner housing sleeve than for rotation on the inside of the outer housing sleeve, since the radius of the inner housing sleeve, which determines the torque, is smaller than the radius of the outer housing sleeve.

[0046] The inner housing sleeve is preferably arranged coaxially to the longitudinal axis and is permanently connected to the outer housing sleeve at a distal end. The outer housing sleeve can be constructed as a single piece with the inner housing sleeve, or the outer housing sleeve and the inner housing sleeve can be manufactured as individual parts and then permanently connected to each other in an axially and rotationally fixed manner, for example, by welding or gluing.

[0047] The dosing and dispensing mechanism preferably comprises a dose indicator sleeve arranged in the housing for displaying a set dose, wherein the dose indicator sleeve is rotationally coupled to the actuating element by means of a coupling mechanism when a dose is set. For this purpose, for example, the actuating element and the dosing sleeve can each comprise teeth that can engage with one another to rotationally couple the actuating element to the dosing sleeve. Alternatively, the coupling mechanism can comprise a wedge and a corresponding groove, or the coupling mechanism can comprise elements that can be coupled to one another in a force-fitting manner. In all embodiments, the coupling mechanism allows the actuating element to be optionally rotationally coupled to the dose indicator sleeve or to be released from one another.

[0048] The dose indicator sleeve is not operated by the user and therefore does not require a handle or other actuating elements, allowing for a compact design. When setting or correcting a dose, the dose indicator sleeve is rotated, shifted, or moved in a screw-like manner relative to the housing using the actuating element. To display the dose, the dose indicator sleeve can, for example, have numbers on its exterior.

[0049] Preferably, in the dosing and dispensing mechanism, the dose indicator sleeve is decoupled by means of the coupling mechanism during dispensing, so that the dose indicator sleeve can rotate relative to the actuating element. If the coupling mechanism comprises teeth or ribs, these are preferably aligned along the longitudinal axis. As a result, for dispensing, by means of a relative displacement of the actuating element to the dose indicator sleeve, the teeth of the actuating element can be pushed out of teeth or grooves in the dose indicator sleeve, thereby canceling the coupling and allowing the dose indicator sleeve to rotate relative to the actuating element. By decoupling the dose indicator sleeve and actuating element, the dose indicator sleeve can, for example, be pushed or screwed into the housing, while the actuating element can be displaced purely axially relative to the housing to drive the piston rod.The dose indicator sleeve can be displaceable, rotatable or mounted by means of a thread on the housing or an internal housing insert or internal housing sleeve, if present, or in an annular gap formed by coaxially arranged components.

[0050] The dose indicator sleeve preferably comprises a radial click element that can interact with the actuating element to generate a tactile and / or acoustic signal. The signal is preferably generated during dispensing when the actuating element rotates relative to the dose indicator sleeve. The actuating element preferably has counter-elements in the form of webs, grooves, or projections, so that when the click element, preferably in the form of a flexible radial arm or a flexible tab, is moved over the counter-elements during dispensing, the tactile and / or acoustic signal is generated in the form of a click or a vibration. This signal provides the user with feedback when the dose is dispensed. The counter-elements can be part of the coupling mechanism on the actuating element described above.

[0051] In a preferred embodiment, the dose indicator sleeve has an internal thread that is threadedly connected to an external thread of the inner housing sleeve. This allows a numerical scale for indicating the dose to be arranged on an outer side of the dose indicator sleeve without the need for a thread on the outside of the dose indicator sleeve, which would restrict the placement of the scale. The dose indicator sleeve is preferably screwed proximally out of or into the housing together with the actuating element when setting or correcting a dose. When dispensing the dose, the dose indicator sleeve is preferably decoupled from the actuating element and screwed distally back into the housing, while the actuating element can be displaced distally in a purely axial manner.

[0052] Preferably, the inner housing sleeve has a distal and a proximal rib on its outer side, wherein the distal rib abuts against a stop element on the inner side of the dose indicator sleeve to limit a minimum adjustable dose or to define the end of a dispensing cycle, and the proximal rib abuts against a stop element to limit a maximum adjustable dose. The stop can be configured in a radial or axial direction.

[0053] In a preferred embodiment, the drive sleeve comprises an elastic element at a proximal end that is firmly and permanently connected to the drive sleeve. The actuating element can be subjected to a preload force generated by the elastic element in the proximal direction. The elastic element is, for example, a spring made of metal or plastic, or an elastically deformable material such as an elastomer. The elastic element is permanently connected to the drive sleeve and / or held between the drive sleeve and the actuating element.

[0054] The preload force allows the actuating element to be held in a proximal position relative to the drive sleeve. This is advantageous if, for example, the actuating element is to remain rotationally decoupled from the housing or rotationally coupled in a proximal position relative to the drive sleeve. In this case, the preload force can be used to prevent unwanted coupling or unintentional coupling of the actuating element with the housing. Only by applying a manual distal force applied by the user that exceeds the preload force can the actuating element be moved distally relative to the drive sleeve in order to couple or uncouple the first and second coupling elements.

[0055] Preferably, the elastic element and the drive sleeve are formed as a single piece. For example, the elastic element can be designed as a spiral spring or wave spring, which is connected to a cylindrical body of the drive sleeve at the proximal end, for example, by injection molding. Furthermore, the elastic element can be formed from an elastomer material and manufactured as a single piece with the drive sleeve, which, for example, is made of a thermoplastic, using multi-component injection molding. Such a single-piece drive sleeve reduces the number of components of the injection device and simplifies assembly.

[0056] Alternatively, it is also possible for the elastic element to be designed separately from the drive sleeve as a single part, for example as a metal or plastic spring in the form of a spiral or wave spring.

[0057] Preferably, the dosing and dispensing mechanism comprises a stop nut for limiting a final dose. The stop nut is threadedly connected to an external thread of the drive sleeve and interacts with the second coupling element. The second coupling element guides the stop nut toward the longitudinal axis and prevents rotation of the stop nut relative to the housing. The stop nut strikes a stop on the drive sleeve when the last dispensable dose has been set, thus preventing a final dose from being set that would exceed the capacity of the cartridge. FIGURES

[0058] Preferred embodiments of the invention are described below in conjunction with the attached figures. These are intended to illustrate basic possibilities of the invention and are in no way to be interpreted as limiting. Fig. 1 shows a perspective view of an exploded view of the individual parts of the injector according to the invention with the dosing and dispensing mechanism; Fig. 2 shows a sectional view of the injector in a starting position, wherein the section runs through the longitudinal axis of the injector; Fig. 3a shows a perspective view of an actuating element; Fig. 3b shows a perspective view of the proximal region of the injector during the setting and correction of a dose, wherein the distal region is cut away and the section runs perpendicular to the longitudinal axis of the injector; Fig. 4a shows a central region of the injector in a sectional view during the setting and correction of a dose; Fig. 4b shows the central region Figure 4a when dispensing a dose and Fig. 5 shows a perspective sectional view of the proximal region of the injector when dispensing a dose, the section running through the longitudinal axis. FIGURE DESCRIPTION

[0059] Figure 1 shows a perspective view of the individual parts of an injector 1 according to the invention with a dosing and dispensing mechanism in an exploded view. The distal, piercing-side end of the injector 1 is located in the lower left area of ​​the Figure 1 and the proximal end of the injector 1 in the right upper area of ​​the Figure 1 .

[0060] In the illustrated embodiment, the injector 1 is designed as a disposable injector. As shown in Figure 1As can be seen, the injector 1 comprises a removable protective cap 11, an elongated, cylindrical housing 10, which simultaneously forms the housing of a dosing and dispensing mechanism, and a carpule holder 12 in which a carpule 13 filled with a medicinal substance is held. Furthermore, the injector 1 comprises the dosing and dispensing mechanism. This includes the housing 10, which comprises an outer housing sleeve and an inner housing sleeve 20 arranged inside the outer housing sleeve, a dose indicator sleeve 30, a drive sleeve 50, a lock nut 40, which is threadedly connected to the drive sleeve 50, an actuating element 60 for setting and correcting a dose and for triggering the dispensing process, and a piston rod 70 arranged within the drive sleeve 50, which can be driven by the drive sleeve 50 to dispense the medicinal substance from the carpule 13.

[0061] The structural features of the individual components of injector 1 are discussed in detail below. The function, particularly the setting, correction, and dispensing of a dose, is described subsequently.

[0062] The cartridge holder 12 is snapped or can be snapped to the housing 10 at a distal end of the housing 10 by means of a snap connection in a rotationally fixed and axially fixed manner. Alternatively, the cartridge holder 12 can also be designed to be snapped to the inner housing sleeve 20. The cartridge holder 12 supports the cartridge 13 and has a connecting element at its distal end to which an injection needle or cannula (not shown) can be attached.

[0063] The cylindrical and sleeve-shaped outer housing sleeve of the housing 10 has an opening 14 on the cylinder surface through which the dose indicator sleeve 30 is visible. The inner housing sleeve 20 also has a cylindrical shape and is arranged coaxially to the outer housing sleeve. At a distal region, the inner housing sleeve 20 can be connected or is connected to the outer housing sleeve both in the axial direction and rotationally immovable relative to the latter. In the distal region, the inner housing sleeve 20 has an internal thread in its interior, into which the piston rod 70 can be screwed or is screwed, as shown in Figure 2 . The Figure 2shows a sectional view of the injector, with the section running through the longitudinal axis. On the outside, the inner housing sleeve 20 has an external thread 21, which extends on a distal section approximately over half the axial length of the inner housing sleeve 20. The dose indicator sleeve 30 is threadedly connected to the external thread. On the inside, the inner housing sleeve 20 has several longitudinal grooves 22 distributed over the circumference and oriented in the direction of the longitudinal axis, which serve as a coupling element and extend over the entire length of the inner housing sleeve 20, as can be seen in Figure 2 .

[0064] As in Figure 1 As can be seen, the inner housing sleeve 20 has a radial web 23, 24 at the beginning and end of the external thread 21. These serve as stops and interact with a radial projection 31 inside the dose indicator sleeve 30, thus limiting a minimum or maximum adjustable dose.

[0065] In the distal end region, the inner housing sleeve 20 has a cylindrical section with a larger diameter, which is firmly connected to the outer housing sleeve. Inside this distal end region, the inner housing sleeve 20 comprises ribs (not shown) that are distributed around the circumference and project radially towards the center. The ribs have a gradient in the axial direction, with the gradient increasing in the proximal direction. In other words, the ribs are wedge-shaped axially and have a smaller radial height distally than proximally, with the radial height steadily increasing in the proximal direction (gradient). However, in an alternative embodiment, the ribs can also be designed without a gradient. In every embodiment, the ribs are dimensioned and made of material such that they are plastically deformable. During assembly, the carpule 13 is first inserted into the carpule holder 12.The carpule holder 12 is then snapped onto the distal end of the inner housing sleeve 20. When the carpule holder 12 is brought together with the inner housing sleeve 20, the carpule 13 located in the carpule holder 12, or its flame rim, first touches the ribs of the housing sleeve 20 at an edge facing the center. If the carpule holder 12 is pushed further in the proximal direction into the inner housing sleeve 20, the ribs undergo plastic deformation. This means that the ribs are permanently deformed by the carpule 13. In the process, the ribs are either pushed sideways as a whole from their original position or the ribs at least partially assume the shape of the outer contour of the carpule 13.When the carpule holder 12 is now snapped onto the inner housing sleeve 20, the carpule 13 is held axially and radially free of play and immovably in the carpule holder 12, since the carpule holder 12 exerts a clamping force in the proximal direction on the carpule 13 and thereby presses it onto the deformed ribs.

[0066] As mentioned, the dose indicator sleeve 30 is threadedly connected to the external thread 21 of the inner housing sleeve 20. The dose indicator sleeve 30 is thus arranged in an annular gap above the inner housing sleeve 20 and within the outer housing sleeve. Furthermore, the dose indicator sleeve 30 has the shape of a hollow cylinder. It has a circumferential numerical scale in a distal region on its outer side, which can be read from the outside through the opening 14 in the outer housing sleeve and indicates the set dose to the user.

[0067] At the distal end, the dose indicator sleeve 30 comprises two radial projections 31 on the inside, visible in Figure 1 . These are attached to a tab or a snap fastener or alternatively directly on the inside so that the dose indicator sleeve 30 can be snapped into the external thread 21 of the housing sleeve 20 via the web 24 with the projections 31 during assembly. In the assembled state, the projections 31 thus run in the external thread 21, whereby the dose indicator sleeve 30 is in threaded connection with the housing sleeve 20. When the dose indicator sleeve 30 is fully screwed in, a projection 31 strikes the web 23 of the housing sleeve 20 so that the minimum dose or the screwing movement of the dose indicator sleeve 30 into the housing is limited by the web 23. The maximum dose or the screwing movement of the dose indicator sleeve 30 out of the housing 10 is limited by the web 24.

[0068] As in Figure 2As can be seen, the dose indicator sleeve has a taper or a section with a smaller inner diameter at the proximal end 30. On the inside of this section, teeth 33 are formed, pointing radially inward toward the center, which can be releasably engaged with teeth 65 of the actuating element 60. This releasable interlocking between the dose indicator sleeve 30 and the actuating element 60 forms a coupling mechanism. In addition, the dose indicator sleeve 30 has a flexible, radial click arm 32 in this section. When moved over teeth or grooves of the actuating element 60, this can generate an acoustic clicking sound.

[0069] Located inside the inner housing sleeve 20 is the drive sleeve 50. This is essentially cylindrical and has a rigid and a flexible section. The rigid section is in turn divided into a distal section 51 with an external thread and a proximal section 52 with a locking element 58. The lock nut 40 is screwed onto the external thread.

[0070] Furthermore, the drive sleeve 50 comprises a circumferential wall 56 in the central region, which divides the rigid section into the distal region 51 and the proximal region 52. The proximal region 52 comprises two guides 53 in the form of axial webs, which are arranged opposite one another around the circumference and engage in axial grooves 64 in the actuating element. The proximal region 52 also forms a locking element 58 with a cylindrical region to block radial deflection of arms 62 of the actuating element 60. This is described in detail below in connection with the dispensing process. At the proximal end of the rigid proximal region 52, it has a stepped region 54 which has a smaller outer diameter than the remaining region. The elastic section of the drive sleeve 50 is designed as a plastic spiral spring 55.This means that the plastic coil spring 55 is molded onto the proximal end of the rigid section and firmly or integrally connected to it. When installed, the coil spring 55 is thus located between the proximal end of the proximal region 52 of the drive sleeve 50 and an inner wall of the actuating element 60. The coil spring 55 is slightly compressed in the axial direction, so that the actuating element 60 is subjected to a force in the proximal direction generated by the preload.

[0071] In an alternative not according to the invention, the spring made of metal or plastic can also be formed separately from the drive sleeve 50. In this case, it is supported distally on the proximal region 52 and proximally on the inner wall of the actuating element 60.

[0072] The piston rod 70 is arranged coaxially inside the drive sleeve 50. The drive sleeve 50 has radial engagement webs 57 inside, which engage with a left-hand thread of the piston rod 70. The drive sleeve 50 is thus rotatably mounted relative to the piston rod 70 and to the housing 10.

[0073] The actuating element 30 is connected to the drive sleeve 50 in a rotationally fixed and axially displaceable manner. This is individually Figure 3a It comprises a cylindrical body, to which a button element 61 is connected in the proximal area. The cylindrical body has an axial opening or bore in which the axial grooves 64 are located on the inside. The axial webs of the guide 53 of the drive sleeve 50 engage in these and thus couple the actuating element 60 in a rotationally fixed but axially displaceable manner to the drive sleeve 50. As best shown in Figure 3aAs can be seen, coupling elements in the form of flexible arms 62 are formed in the wall of the cylindrical body, offset from one another by 180° in the circumferential direction. These arms 62 can be elastically deflected in the radial direction. Furthermore, the arms 62 each have a cam 63 on their outer side at their free end.

[0074] In Figure 3b The proximal area of ​​the injector is shown in perspective view, with the distal area cut away and the cut perpendicular to the longitudinal axis. In this figure, as well as in Figure 4a It can be seen that the cams 63 of the arms 62 extend into the longitudinal grooves 22 of the inner housing sleeve 20. In a proximal region of the cylindrical body of the actuating element 60, the latter has circumferentially arranged teeth 65, which can be engaged with the teeth 33 of the dose indicator sleeve 30 in order to rotatably couple the actuating element 60 to the dose indicator sleeve 30.

[0075] The button element 61 comprises a shell that protrudes beyond the proximal region of the cylindrical body. In other words, the button element 61 is mushroom-shaped.

[0076] In addition, the button element 61 is formed in one piece with the cylindrical body of the actuating element 60 and is thus axially and rotationally fixedly connected to the cylindrical body.

[0077] As mentioned and in Figure 2 As can be seen, the lock nut 40 is screwed onto the external thread 21 of the inner housing sleeve 20. This nut has axially aligned webs on its outer side, which engage in the longitudinal grooves 22 on the inner side of the housing sleeve 20. The lock nut 40 is thus rotatable relative to the drive sleeve 50 and axially displaceable but rotationally fixed relative to the housing sleeve 20.

[0078] The piston rod 70 comprises a left-hand thread (left-hand thread) and a right-hand thread (right-hand thread). The right-hand thread is used to screw the piston rod 70 into the inner housing sleeve 20. The left-hand thread engages the drive sleeve 50. The thread pitches are preferably different. For example, the right-hand thread can have twice the pitch of the left-hand thread. At the distal end of the piston rod 70, there is a button-shaped end piece ( Figure 2 ), which enables a snap connection with a flange 71, whereby the flange 71 is rotatable and preferably tiltable relative to the piston rod 70, but is held axially on the piston rod 70. The flange 71 can act on a plug 15 in the carpule 13 to discharge the medicinal substance from the carpule 13.

[0079] The following describes how to set and correct a dose. Figure 2the injector 1 is shown in an initial position. To set a dose, the actuating element 60 is rotated relative to the housing 10 by means of its knob element 61. Since the actuating element 60 is rotationally coupled to the dose indicator sleeve 30 by means of its teeth 65, the dose indicator sleeve 30 is also rotated. Since the actuating element 60 is also rotationally fixedly connected to the drive sleeve 50 and this is threadedly connected to the piston rod 70, the actuating element is screwed out of the housing 10 by the rotation in the proximal direction. The rotationally coupled dose indicator sleeve 30 is also screwed out of the housing 10, since its internal thread is threadedly connected to the inner housing sleeve 20.The external thread 21 of the housing sleeve must have the same pitch and the same thread direction as the left-hand thread of the piston rod 70, since the actuating element 60 and the dose indicator sleeve 30 should not be displaced relative to each other when setting and correcting a dose.

[0080] The actuating element 60 and the drive sleeve 50 are rotationally coupled by means of the guides 53, which engage in the axial grooves 64. An axial stop on the drive sleeve 50 prevents the actuating element 60 from being pulled off in the proximal direction via the drive sleeve 50.

[0081] Figure 4a shows a sectional view of a central region of the injector, in which region the drive sleeve 50 and the actuating element 60 are connected. In the position shown, the actuating element 60 is in a proximal position relative to the drive sleeve 50 during the setting and correction of a dose.

[0082] When the actuating element 60 is screwed out of the housing 10 relative to the inner housing sleeve 20, the cams 63 of the flexible arms 62 are each guided transversely over the longitudinal grooves 22. This means that during the relative movement, the arms 62 briefly deflect radially inward. This is possible because, during adjustment and correction, the arms 62 are located longitudinally at the offset area 54 of the drive sleeve 50, thus providing space for the radial deflection of the arms 62. When the actuating element 60 rotates relative to the inner housing sleeve 20, the flexible, elastic arm 62 is moved from one longitudinal groove 22 to the next. In doing so, the arm 62 springs back into the longitudinal grooves 22. As a result, a clicking noise and vibration are generated each time the cam 63 is moved from one longitudinal groove 22 to the next.

[0083] If a dose is accidentally set too high, the dose can be corrected by screwing the actuating element 60 back into the housing 10. The cams 63 of the flexible arms 62 are thereby moved in the opposite direction over the longitudinal grooves 22 and, in turn, generate a clicking sound and vibration when they are moved from one longitudinal groove 22 to the next.

[0084] The stop nut 40 is guided axially and rotationally fixedly in the longitudinal grooves 22 of the housing sleeve 20 by means of its axial webs. When setting a dose or rotating the drive sleeve 50, it is screwed onto its thread in the proximal direction. When correcting a dose or reversing the actuating element 60, the stop nut 40 is screwed back in the distal direction. When the last dose is reached, the stop nut 40 strikes the wall 56 of the drive sleeve 50 proximally, thus preventing further rotation of the actuating element 60 and thus further dosing.

[0085] The distribution process is described below. Figure 4b shows a sectional view of the central region of the injector, with the actuating element 60 in a distal position relative to the drive sleeve 50, as is the case when dispensing a dose.

[0086] To dispense the set dose, the user presses the button element 61 in the distal direction. This displaces the actuating element 60 in the distal direction relative to the dose indicator sleeve 30 and relative to the drive sleeve 50. In doing so, the teeth 65 of the actuating element 60 are displaced from engagement with the teeth 33 of the dose indicator sleeve 30, thereby rotationally decoupled from the actuating element 60. The distal displacement relative to the drive sleeve 50 is stopped when a distal end of the actuating element 60 abuts the wall 56. During this displacement, the cylindrical region of the drive sleeve 50 serving as the locking element 58 is pushed under the arms 62. The arms 62 thus rest entirely or almost entirely on the cylindrical region and are thus radially blocked. The arms 62 can no longer be deflected radially inward.This means that the cams 63 of the arms 62 are each held in a longitudinal groove 22 and can no longer be moved to the next longitudinal groove 22. The actuating element 60 and thus also the drive sleeve 50 are thus rotationally fixedly coupled to the housing 10.

[0087] However, since the longitudinal grooves 22 in the inner housing sleeve 20 run in the direction of the longitudinal axis, the actuating element 60 can still be displaced axially relative to the housing 10. The force applied by the user in the distal direction displaces the actuating element 60 and the drive sleeve 50 further distally. The drive sleeve 50 transfers the axial force to the left-hand thread of the piston rod 70 and forces the piston rod 70 to rotate. This then screws into the non-rotating drive sleeve 50. Since the piston rod 70, with its right-hand thread, is threadedly connected to the housing sleeve 20, the piston rod 70 simultaneously screws in the distal direction. If the right-hand thread has a smaller pitch than the left-hand thread, a reduction in the distal displacement of the actuating element 60 and thus a force transmission can be achieved.The flange 71 moves the plug 15 in the carpule 13 distally and the product is dispensed from the carpule 13.

[0088] The Figure 5 shows a perspective sectional view of the proximal region of the injector 1. The figure shows the position after the user has pressed the button element 61 with a force acting in the distal direction to dispense the dose and thus, as described above, the teeth 65 of the actuating element 60 are pushed out of engagement with the teeth of the dose indicator sleeve 30 and thus the actuating element and dose indicator sleeve are rotationally decoupled from one another.

[0089] Due to the distal displacement of the actuating element 60 relative to the housing 10, the dose indicator sleeve 20 is screwed back into the housing 10 by the axial force. The click arm 32 of the dose indicator sleeve 30 moves over the teeth 65, generating a clicking sound during dispensing. Since the drive sleeve 50 is held rotationally fixed to the housing sleeve 20 during dispensing, the lock nut 40 arranged between them is not moved.

[0090] In a further embodiment of the dosing and dispensing mechanism according to the invention, a different limiting mechanism can be provided instead of the stop nut 40, which ensures that no dose can be set that exceeds the capacity of the carpule. Thus, instead of the stop nut, the external thread of the coupling sleeve, and the longitudinal grooves 22 in the housing sleeve 20, the dosing and dispensing mechanism according to the invention can comprise a limiting mechanism between the housing sleeve 20 and the drive sleeve 50 with eccentric elements, as described in patent application EP 2 918 298 A1 in paragraphs [0059 - 0138] and shown in Figures 1 to 25b.

[0091] In a further embodiment, instead of the lock nut, a ball with corresponding guideways in the housing sleeve and in the drive sleeve can be provided, as described in patent application WO 2010 / 149209 A1 on pages 25-27 and shown in Figures 3-8. Alternatively, instead of the ball, a segment guided in longitudinal guides can be used, as disclosed in WO 2010 / 149209 A1 on pages 27-29 and Figures 9-14. LIST OF REFERENCE SYMBOLS

[0092] 1 Injector 10 Housing 11 Protective cap 12 Cartridge holder 13 Cartridge 14 Opening 15 Plug 20 Housing sleeve 21 External thread 22 Longitudinal grooves 23, 24 Webs 30 Dose indicator sleeve 31 Radial projection 32 Click arm 33 Teeth 40 Lock nut 50 Drive sleeve 51 Distal area 52 Proximal area 53 Guides 54 Stepped area 55 Coil spring 56 Wall 57 Engagement webs 58 Locking element 60 Actuating element 61 Button element 62 Arm 63 Cam 64 Grooves 65 Teeth 70 Piston rod 71 Flange

Claims

1. A dosing and dispensing mechanism for an injection device (1) for setting and dispensing a dose of a product by means of manual advancement of a plunger (70) into a carpule (13) held in the injection device (1), the dosing and dispensing mechanism comprising the plunger (70); a housing (10) having a longitudinal axis; a drive sleeve (50) longitudinally displaceably arranged in the housing (10) for driving the plunger (70); an actuating element (60) for setting the dose, the actuating element (60) being connected to the drive sleeve (50) against rotation and being displaceable in the direction of the longitudinal axis relative to the drive sleeve (50), the actuating element (60) being rotatable relative to the housing (10) in order to set the dose, the actuating element (60) comprising a first coupling element formed in one piece with the actuating element (60) and the housing (10) comprising a second coupling element formed in one piece with the housing (10), the first and the second coupling element being able to be coupled to one another in order to dispense the dose, so that in the coupled state the actuating element (60) is connected to the housing (10) against rotation and is displaceable in the direction of the longitudinal axis relative to the housing (10) characterized in that the drive sleeve (50) comprises a resilient element (55) at a proximal end and the actuating element (60) can be acted upon in the proximal direction by a pretensioning force generated by the resilient element (55), the resilient element (55) and the drive sleeve (50) being formed in one piece.

2. Dosing and dispensing mechanism according to claim 1, characterized in that the first coupling element is a flexible arm (62) which can be deflected in the radial direction.

3. Dosing and dispensing mechanism according to claim 2, characterized by a locking element (52) with which the flexible arm (62) can be blocked in the radial direction.

4. Dosing and dispensing mechanism according to claim 3, characterized in that by displacement of the actuating element (60) in the direction of the longitudinal axis relative to the drive sleeve (50), the flexible arm (62) can be blocked with the locking element (52).

5. Dosing and dispensing mechanism according to any of claims 1 to 4, characterized in that the second coupling element is a groove (22) in which at least a portion of the first coupling element can be received.

6. Dosing and dispensing mechanism according to claims 2 and 5, characterized in that when a dose is set and corrected, a free end of the flexible arm (62) can interact with the groove (22) in such a way that a tactile and / or acoustic signal can be generated.

7. Dosing and dispensing mechanism according to any of claims 1 to 6, characterized in that a threaded connection is provided between the drive sleeve (50) and the plunger (70), so that by displacement of the drive sleeve (50) relative to the housing (10), the plunger (70) can be set in rotation in order to dispense the dose.

8. Dosing and dispensing mechanism according to any of claims 1 to 7, characterized in that the housing (10) of the dosing and dispensing mechanism comprises, in its interior, an inner housing sleeve (20) fixed to the housing, the second coupling element being formed on the inside of the inner housing sleeve (20).

9. Dosing and dispensing mechanism according to any of claims 1 to 8, characterized in that the dosing and dispensing mechanism comprises a dose indicator sleeve (30) arranged in the housing (10) for displaying a set dose, the dose indicator sleeve (30) being coupled for conjoint rotation to the actuating element (60) by means of a coupling mechanism when a dose is set.

10. Dosing and dispensing mechanism according to claim 9, characterized in that during dispensing, the dose indicator sleeve (30) is decoupled by means of the coupling mechanism, so that the dose indicator sleeve (30) is rotatable relative to the actuating element (60).

11. Dosing and dispensing mechanism according to claims 9 and 10, characterized in that the housing sleeve (20) has a distal rib (23) and a proximal rib (24) and in that the dose indicator sleeve (30) has on its inside a stop element (31) which abuts the distal rib (23) in order to limit a minimum settable dose and abuts the proximal rib (24) in order to limit a maximum settable dose.

12. Dosing and dispensing mechanism according to any of claims 9 to 11, characterized in that the dose indicator sleeve (30) comprises a radial click element (32) which can interact with the actuating element (60) to generate a tactile and / or acoustic signal.

13. Dosing and dispensing mechanism according to claims 8 and 9, characterized in that the dose indicator sleeve (30) is connected in a threaded manner to the inner housing sleeve (20) by means of an internal thread.

14. An injection device (1) comprising a dosing and dispensing mechanism according to any of claims 1 to 13.