Automatic injection device for administering a fixed dose

Abstract

Injection device for administering a substance, wherein the injection device comprises the following: - a housing (1), - a syringe (7) permanently connected to the housing (1) with an injection needle (7b) for manual injection by pressing the injection device onto a surface while pushing back a cover sleeve (2) into the housing (1), - a piston rod (3) movable in the housing (1), on which at least one retaining element (3a) is provided that holds the piston rod (3) relative to the housing (1), - a sliding locking device which is slidable within the housing (1) and in a first position holds the at least one retaining element (3a) in a holding position relative to the housing (1) against displacement in a distal direction and in a second position releases the at least one retaining element (3a), and - Retaining elements on the cover sleeve (2) and housing (1) which generate an initial resistance when the cover sleeve (2) is pressed against the surface by a user holding the housing (1), whereby upon overcoming an initial force the retaining elements release from a holding position and release the cover sleeve (2), so that the injection needle (7b) is abruptly inserted into the surface.

Description

[0001] The present invention relates to a device for the self-administration of a fixed dose of a specific substance. Such a device is also referred to as a fixed-dose pen and enables a simple, single self-administration of a substance stored in an ampoule or syringe within the injection device.

[0002] An injection device for delivering a fixed dose, which can be preset once, for example, is known from DE 10 2006 038 103 A1 of the applicant.

[0003] DE 198 22 031 A1 describes an autoinjection device with a product container that can be slidably mounted in a housing.

[0004] DE 198 21 933 C1 describes a device for administering an injectable product, which includes means that generate a damping force which counteracts the driving force during a forward movement of the piston in addition to all unavoidable counterforces.

[0005] An injection device in which a spring element moves a needle guard into a position surrounding the needle after the injection needle has been removed from the skin is known from WO 2004 / 047 892 A1.

[0006] DE 102 03 597 A1 describes an injection device with a needle guard sleeve that is axially displaceable between a protective position and a functional position. The injection device has devices for locking the needle guard sleeve in the protective position and for releasing the lock.

[0007] It is an object of the present invention to propose an injection device for a single delivery of a fixed predetermined quantity of a substance, which can be easily constructed and operated.

[0008] This problem is solved by the injection device according to claim 1. Advantageous embodiments are defined in the dependent claims.

[0009] An injection device comprises a housing by which the user can hold the device. A piston rod is provided within the housing, which can press against a stopper of a syringe, preferably also located within the injection device. The pressure on the stopper displaces a substance contained within the syringe and preferably delivers it through an injection needle. The piston rod has at least one movable or deflectable retaining element, such as a spring arm with a radially projecting engagement area, which holds the piston rod in a fixed position relative to the housing and preferably against the housing itself, preventing displacement.Furthermore, a movable or displaceable locking element, for example a sleeve, preferably a cover sleeve, is provided on or in the injection device. This locking element is advantageously displaceable relative to the housing of the injection device and holds the at least one retaining element of the piston rod in a fixed position relative to the housing when the locking element or sleeve is in a first position. The at least one retaining element of the piston rod can be released when the locking element or sleeve is displaced from the first position, so that the coupling between the piston rod and the injection device or the housing of the injection device is released and, preferably, the piston rod can be moved or displaced within the injection device, for example, to trigger or carry out the injection.

[0010] Preferably, the locking element or sleeve is a cover sleeve located in the distal region of the injection device and projecting from it. This cover sleeve is displaceable relative to the housing of the injection device, i.e., it can be inserted axially into the housing of the injection device when the injection device is placed on a surface, such as skin, and is advantageously mounted in the housing of the injection device in a rotationally secured manner. When the housing of the injection device is pushed towards the skin, the cover sleeve can be inserted into the housing after overcoming a minimum counterforce caused, for example, by a releasable snap-fit ​​connection; that is, the housing of the injection device moves towards the surface.

[0011] Preferably, the housing has at least one rib or detent or retaining step on which the at least one retaining element can be held. The rib or retaining step can, for example, have a surface on which the longitudinal or axial axis of the injection device is perpendicular and is preferably chamfered so that the at least one retaining element of the piston rod can be released more easily when it is no longer held or fixed by the sliding cover sleeve. The at least one retaining element of the piston rod advantageously has a retaining area that corresponds to the contact surface of the retaining step, i.e., is also slightly chamfered, for example.

[0012] Preferably, an injection spring element is provided, which is supported, for example, on the housing or on an element preferably firmly connected or locked to the housing, such as an end cap, and which presses on the piston rod in a distal direction. The injection spring element is preferably tensioned in the initial position of the injection device and has a force sufficient to move the at least one retaining element out of its holding or engagement position when the retaining element is no longer held or locked by the safety catch or cover sleeve, so that the force of the injection spring element pressing on the piston rod then makes the piston rod movable relative to the injection device or relative to the housing and pushes it towards the stopper of the ampoule or syringe to initiate the dispensing process.

[0013] Advantageously, the cover sleeve is secured against rotation in or within the housing of the injection device, for example by an axially extending groove and / or a rib of the cover sleeve which interacts with a corresponding rib and / or an axial groove of the injection device or the housing or forms an axial guide.

[0014] Preferably, a cover spring is provided in the injection device, which advantageously bears against the injection device or its housing and presses on the movable cover sleeve, so that the cover sleeve can be subjected to pressure in a distal direction by the cover sleeve spring. When the injection device is placed on a surface and moved towards it, the cover sleeve can be pushed into the injection device against the force of the cover sleeve spring, resulting in compression and thus tension of the cover sleeve spring.

[0015] The injection device includes a syringe that is either permanently attached to the housing or held firmly within the housing, for example, by one or more stops and / or by the plunger rod pressing against the ampoule or the ampoule stopper. The syringe has an injection needle at its distal end, which may be secured, for example, by a removable needle cap. The injection needle is preferably arranged in the injection device such that, when the cap is extended, it is surrounded by the cap, and when the cap is retracted, it is exposed. This allows the injection device to be pressed against a surface, thereby retracting the cap and enabling the exposed injection needle to penetrate the surface.Advantageously, the insertion is performed manually by pressing the injection device onto a surface, eliminating the need to press a button or trigger for the insertion process. The protective sleeve is positioned within the injection device in such a way that when the device is pressed onto the surface, an initial force must be overcome to insert the sleeve. This ensures a rapid insertion process, as the initial force is quickly overcome and the subsequent pressure pushes the protective sleeve back, thus enabling the needle to be inserted quickly.

[0016] Another aspect relates to an injection device that can be assembled from just a few individual parts, such as only three or four components, which can be made of plastic, for example, such as a housing, a cover sleeve, a piston rod, and optionally an end cover or cap. In this case, for example, only a single spring is required for the injection and optionally another spring for the cover sleeve.

[0017] An injection device can be designed that allows for single dosing, i.e., a single dispensing, with the injection device preferably locking automatically after dispensing. The dispensing volume is preferably predetermined by the contents of the syringe contained in the injection device. Dispensing preferably occurs automatically after insertion, meaning that no further actuation mechanism is required to initiate the dispensing process. This dispensing process is fully automatic after insertion. Preferably, the injection device has a safety needle guard and locks or protects the injection needle after use, i.e., after injection, by, for example, automatically extending the protective sleeve axially over the injection needle.

[0018] Another aspect relates to a method for assembling or mounting an injection device from two, and preferably exactly two, subassemblies, wherein an ampoule or syringe to be used is preferably not considered a subassembly. When assembling the injection device from the two subassemblies, an injection spring is only tensioned during the assembly of the subassemblies. The injection spring is preferably a component of one of the subassemblies and, in the unassembled state, is in a relaxed state, i.e., not compressed or tensioned. This ensures that deterioration or aging processes caused by the pressure exerted by a tensioned injection spring do not occur from the moment the subassemblies are assembled.

[0019] Preferably, one of the two subassemblies comprises the housing of the injection device and, optionally, a cover sleeve inserted into the housing and movable relative to it, which may, for example, protrude from the distal region of the housing. The second subassembly preferably comprises a piston rod, an injection spring, and an injection spring support element, wherein the injection spring can be tensioned and, for example, compressed between the injection spring support element and the piston rod. The piston rod or piston rod element can, for example, be displaced relative to the injection spring support element and, for example, guided by the injection spring support element, inserted into it, so that the injection spring can be tensioned or compressed between the piston rod and the injection spring support element.When assembling the injection device, a syringe or ampoule can be inserted between the first and second subassemblies before assembly. For example, the syringe or ampoule can be inserted into the first subassembly. The second subassembly can then be inserted or inserted into the first subassembly. Advantageously, the piston rod or its distal end is pressed against the syringe or ampoule, for example, against a stopper that is movable within the syringe or ampoule. Since no fluid or substance can escape from the ampoule or syringe in the initial state, for example, due to a needle guard, when the second subassembly is inserted into the first, the piston rod is moved relative to the injection spring support element, for example, by pressure from the stopper, so that the injection spring is tensioned.Optionally, a cover sleeve spring can also be provided between the first and the second sub-assembly or on the second sub-assembly, which, for example, lies between the injection spring support element on the one hand and the cover sleeve on the other hand in the assembled state, so that when the cover sleeve is inserted into the housing, it causes tension or compression of the cover sleeve spring.

[0020] The invention is described below with reference to a preferred embodiment. The figures show... Fig. 1 an injection device in its initial state in cross-sectional view; Fig. 2 the in Fig. 1. Injection device shown in exploded view before assembly, Fig. 3 the in Fig. 2 Injection device shown in partially assembled state; and Fig. 4A to 4C describe the procedure of an injection using the injection device.

[0021] Fig. Figure 1 shows an injection device with a housing 1, which has axially extending ribs 1a or webs on its inner side. A retaining element 3a in the form of a spring arm with radially outward engagement rests against a proximal side of each rib 1a, the retaining elements 3a being attached to a piston rod 3 and holding it in the axial position shown. An injection spring 5 is provided in the rear or proximal region of the injection device, which bears against an end cap 4 snapped into the housing 1 and which presses on the piston rod 3 and preferably the retaining elements 3a of the piston rod 3 in a distal direction. The retaining elements 3a of the piston rod 3 are preferably positively engaged or with a small amount of play in the engagement or holding position at the edges of the ribs 1a by arms 2a of the cover sleeve 2, so that the injection spring 5 cannot push the piston rod 3 distally.

[0022] On the distal side of the piston rod 3, an ampoule or syringe 7 is provided with a sliding stopper 7a, against which the piston rod 3 can press. An injection needle 7b is provided on the distal or front side of the syringe 7, on which a needle guard 7c is attached, which is removed before use of the injection device. The cover sleeve 2 preferably has radially outwardly projecting lugs 2b in the region of its front or distal half, which engage in a corresponding groove or recess 1c of the housing to generate initial resistance when the cover sleeve 2 is pressed against a surface by a user holding the housing 1.If the force with which the user presses on the housing 1 in a distal direction increases, these retaining elements release from their holding position and suddenly or jerkily release the cover sleeve, which is axially displaceable in the injection device, so that it can slide into the injection device, thereby bringing the injection device 1 jerkily onto the surface and inserting the injection needle 7b.

[0023] In the rear or proximal part of the injection device, a cover sleeve spring 6 is provided, which is supported against the housing 1 of the injection device or, in the illustrated embodiment, against the end cap 4 which is connected to or latched to the housing 1 and which presses in a distal direction onto the cover sleeve 2.

[0024] Fig. 2 shows the in Fig. Figure 1 shows an exploded view of the injection device, revealing the seven individual components of the injection device described above. The cover sleeve 2 has two axially extending arms 2a with proximal end or retaining regions 2d and a release recess 2c offset axially between the arms 2a and the retaining regions 2d. The piston rod 3 has two retaining elements 3a and 3a', which can be, for example, pushed apart and / or secured against being compressed by the retaining regions 2d.

[0025] Fig. Figure 3 shows the partially assembled individual components, with the cover sleeve 2 being inserted into the housing 1 and the piston rod 3, the injection spring 5 and the end cap 4 being assembled into a unit.

[0026] The Fig. 1, Fig. 4A, Fig. 4B and Fig. 4C shows the process of an injection using the injection device, starting from the point in Fig. 1. Delivery condition shown.

[0027] The injection device is loaded by the injection spring 5, which is compressed or tensioned between the piston rod 3 and the end cap 4. The cover sleeve 2 is mounted or suspended in the housing 1 to prevent rotation and is pressed into the forward or distal position by the cover sleeve spring 6. The syringe 7 is supported in the housing 1, for example, by stops or retaining elements 1b, and is additionally guided by arms 2a or ribs in the cover sleeve 2 and secured by webs 4a of the end cap 4. Retaining elements 3a, designed as radially outwardly projecting spring elements, are attached to the piston rod 3. These retaining elements bear against ribs 1a in the housing 1 and are prevented from deflecting radially inward outside the retaining position by the proximal side of the arms 2a of the cover sleeve 2.

[0028] The end cap 4 is snapped or locked into the housing 1. This snap or locking connection is designed to withstand the forces of the injection spring 5 and the cover sleeve spring 6.

[0029] Fig. Figure 4A shows the injection device in a triggered state after the needle guard 7c has been removed from the injection needle 7b. Upon insertion, the cover sleeve 2 is pushed into the rear position until the retaining elements 3a of the piston rod 3 are released for deflection through a recess 2e in the cover sleeve 2. Due to the chamfer on the ribs 1a in the housing 1 and on the retaining elements 3a of the piston rod 3, the retaining elements 3a of the piston rod 3 are deflected by the force of the injection spring 5, thus automatically triggering the dispensing. The injection spring 5 provides the force required to deflect the retaining elements 3a and thus release the piston rod 3, which is then pressed by the injection spring 5 against the stopper 7a of the syringe 7, inserting it into the syringe 7 and thus automatically triggering the dispensing.

[0030] The cover sleeve spring 6 rests against the proximal sides of the cover sleeve 2 and has been compressed or compressed by the inserted cover sleeve 2.

[0031] Fig. Figure 4B shows the injection device after the dispensing process. The release of the injection spring 5 pushes the piston rod 3 forward in a distal direction. The piston rod 3 presses against the stopper 7a of the syringe 7 and empties the syringe 7 completely until the stopper 7a rests against the end of the glass body of the syringe 7. The two retaining elements 3a on the piston rod 3 slide over the ribs 1a of the housing 1. At the end of the dispensing process, one of the two retaining elements 3a snaps over the end of one or more ribs 1a in the housing 1, causing a sound after dispensing, the so-called "end click," and simultaneously locking the piston rod 3 against being pushed back.

[0032] The other retaining element 3a' on the piston rod 3 is held in the deflected state by an arm 2a acting as a locking bar on the cover sleeve 2.

[0033] Fig. Figure 4C shows the injection device in the locked state after removal from the injection site.

[0034] After the injection is complete, the injection device is removed from the injection site. During this process, the cover sleeve 2 is pushed into the forward or distal position by the cover sleeve spring 6. The arm 2a of the cover sleeve 2 shifts under the deflected retaining element 3a' on the piston rod 3 until the retaining element 3a' snaps over the end of the arm 2a, producing a sound, a so-called "click". In this state, the injection device is locked. The cover sleeve 2 can no longer be pushed in because it is blocked by the piston rod 3, which rests against, for example, the three ribs 1a in the housing 1.

Claims

[1] Injection device for administering a substance, the injection device comprising: - a housing (1), - a syringe (7) permanently connected to the housing (1) with an injection needle (7b) for manual injection by pressing the injection device onto a surface while pushing back a cover sleeve (2) into the housing (1), - a piston rod (3) movable in the housing (1), on which at least one retaining element (3a) is provided that holds the piston rod (3) relative to the housing (1), - a sliding locking device which is slidable within the housing (1) and in a first position holds the at least one retaining element (3a) in a holding position relative to the housing (1) against displacement in a distal direction and in a second position releases the at least one retaining element (3a), and - Retaining elements on the cover sleeve (2) and housing (1) which generate an initial resistance when the cover sleeve (2) is pressed against the surface by a user holding the housing (1), whereby upon overcoming an initial force the retaining elements release from a holding position and release the cover sleeve (2), so that the injection needle (7b) is abruptly inserted into the surface. [2] Injection device according to claim 1, wherein the retaining elements comprise radially formed noses (2b) and corresponding recesses (1c). [3] Injection device according to claim 2, wherein the retaining elements comprise radially outwardly projecting noses (2b) which engage in corresponding grooves. [4] Injection device according to claim 3, wherein the lugs (2b) are arranged on the cover sleeve (2) and the grooves are arranged on the housing (1). [5] Injection device according to one of the preceding claims, wherein the cover sleeve (2) is mounted in the injection device or in the housing (1) in a rotationally secured manner. [6] Injection device according to one of the preceding claims with an injection spring (5) which is supported against the housing (1) or against an element connected to the housing and which presses in a distal direction on the piston rod (3), wherein the injection spring (5) is tensioned in a starting position of the injection device and has a force to move the at least one retaining element (3a) out of the retaining position when the at least one retaining element (3a) is no longer held by the locking device. [7] Injection device according to one of the preceding claims with a cover sleeve spring (6) which is supported against the housing (1) of the injection device or an element connected thereto and which generates or presses a spring force on the cover sleeve (2) in a distal direction, wherein after injection the injection needle (7b) is protected by the cover sleeve (2) being pressed into a forward or distal position by the cover sleeve spring (6). [8] Injection device according to any of the preceding claims, characterized by , that the sliding locking device in the first position holds the at least one retaining element (3a) in the holding position relative to the housing (1) against displacement in the distal direction.

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