SPRING FOR AN INJECTION DEVICE

Abstract

An injection device for administering a medical substance includes a helical spring having a coil that extends in an axial direction and has at least three windings, where two adjacent windings are non-detachably connected to one another at a point in the axial direction by means of a laser-welded connection. The helical spring and a method for producing the helical spring for use with the injection device are also provided.

Claims

1. An injection device for administering a medical substance, comprising a coiled spring which extends in an axial direction as a coil with at least three loops, of which two adjacent loops are fixedly joined in the axial direction to one another in at least one point by means of a welded connection.

2. The injection device of claim 1, further comprising a casing and a protective sleeve for needle protection, wherein the protective sleeve is movable by the coiled spring in a distal direction in relation to the casing.

3. The injection device of claim 1, further comprising a spring retaining volume with an annular cross section surrounding at least part of the coiled spring, wherein the annular cross section of the spring retaining volume has a cross-sectional width of more than 1.3 times an external diameter dimension of a wire in the coiled spring, at least in sections.

4. A coiled spring for an injection device for administering a medical substance, wherein the coiled spring extends as a coil in an axial direction with at least three loops, of which two adjacent loops are fixedly joined to one another in at least one point in the axial direction by means of a welded connection.

5. The coiled spring of claim 4, wherein an outermost loop and a second from outermost loop of the coil are joined to one another by the welded connection.

6. The coiled spring of claim 5, wherein, on each end of the coiled spring, the outermost loop and the second from outermost loops of the coil are joined to one another by means of a welded connection in at least one point.

7. The coiled spring of claim 4, wherein the welded connection is a laser-welded connection.

8. The coiled spring of claim 4, wherein the coil is formed by a wire with a circular cross section.

9. The coiled spring of claim 8, wherein a diameter of the wire is less than 2 mm.

10. The coiled spring of claim 8, wherein the diameter of the wire is between 0.3 mm and 1.2 mm.

11. The coiled spring of claim 4, wherein the fixedly joined loops are joined together by laser welding at two separate points.

12. The coiled spring of claim 4, wherein the coiled spring comprises a coil that contains at least 5 loops.

13. The coiled spring of claim 4, wherein the coiled spring comprises a coil that contains between 6 and 30 loops.

14. The coiled spring of claim 4, wherein an external dimension of the coiled spring measured perpendicular to an axis of the spring is between 4 mm and 26 mm or between 9 mm and 21 mm.

15. The coiled spring of claim 14, wherein an external dimension of the coiled spring is at least 9 mm measured perpendicular to an axis of the spring, and the welded connection is at least 20 mm from an end of a wire forming the coiled spring.

16. A method for connecting two loops of a coiled spring for an injection device comprising the following steps: provision of a coiled spring which extends as a coil in an axial direction with at least three loops of wire; and connection of two adjacent loops in at least one point by welding.

17. The method of claim 16, wherein the welding is laser welding.

18. The method of claim 16, wherein the two adjacent loops are connected by laser welding at two separate points.

19. The method of claim 16, wherein the coiled spring has a first end and a second end, and two adjacent loops are connected at each of the first end and the second end.

20. The method of claim 16, wherein the connecting by welding is in an axial direction between adjacent loops.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] One design or embodiment of the invention will now be laid out in association with the figures. These demonstrate fundamental possibilities of the design and are in no way meant to be restrictive.

[0036] FIG. 1 shows a perspective image of a coiled spring according to this disclosure.

[0037] FIG. 2a shows a cross section view taken along the longitudinal axis of an exemplary injection device with the coiled spring in a de-tensed or unloaded position.

[0038] FIG. 2b shows a cross section view of the injection device rotated 90° from FIG. 2a, around the longitudinal axis.

[0039] FIG. 3a shows a cross section view of the injection device with the coiled spring in a compressed position.

[0040] FIG. 3b shows a cross section view of the injection device rotated 90° from FIG. 3a, around the longitudinal axis.

DETAILED DESCRIPTION

[0041] FIG. 1 is a perspective, overview image of a coiled spring 10 embodying the disclosure. The coiled spring 10 is set up as a compression spring and consists of a coil (or windings) that extends in an axial direction or in a longitudinal direction of the coiled spring 10 with 15 loops in total. In this example, the coiled spring 10 has a length Ls of 114 mm in an un-tensed position. It also has an external diameter D.sub.S of 15 mm. The coiled spring 10 is made of a wire with a circular cross section with a diameter D.sub.W of 0.7 mm. The wire is made of spring steel with a chrome-nickel alloy and is also electro-conductive. As can be seen in FIG. 1, the two outermost loops or windings on each end are connected to one another in at least one point by means of laser spot welding.

[0042] The outermost or first loop and the second outermost or second loop of the coil 10 are joined to one another at two connection points 20a, 20b, at one end, 20c, 20d, at the other. A first point of connection 20a is around 2 mm away from one of the ends of the wire, but this can be greater if desired. A second point of connection 20b is 3 mm from the same end of the wire or 1 mm from the first point of connection.

[0043] This arrangement of the points of connection 20a, 20b at the first end of the coiled spring has a corresponding arrangement in a third and a fourth point of connection 20c, 20d on the other end of the coiled spring 10. The coiled spring 10 thus has a total of four connection points 20a, 20b, 20c, 20d or welded spots.

[0044] FIGS. 2a, 2b, 3a and 3b each show a cross section of an autoinjector 1 with the coiled spring 10 according to the present disclosure. In each case, the cross section view is taken along the longitudinal axis L of the autoinjector 1. The cross section in FIGS. 2b and 3h reflects the views of FIGS. 2a and 3a, respectively, rotated 90° around the longitudinal axis L. In the following, the arrangement and function of the coiled spring 10 within the autoinjector 1 will be laid out with reference to these figures.

[0045] The autoinjector 1 comprises a sleeve-like elongated casing or housing 2 with a longitudinal axis L. In the casing 2, there may be a product container 13 with the medicine. On the distal end, the product container 13 is joined to a hollow injection needle 13a. The autoinjector 1 also has a protective sleeve 3 that is movable in a proximal direction relative to the casing 2 and along the longitudinal axis L during the actuator stroke (H.sub.B) to the activated position in order to trigger the release of the product.

[0046] In the casing 2, there is also a trigger sleeve 15 and a locking sleeve 8. The trigger sleeve 15 is positioned at a proximal end 3a of the protective sleeve 3. The coiled spring 10 is oriented in a longitudinal direction within the autoinjector and partly surrounds both the trigger sleeve 15 and the locking sleeve 8. The coiled spring 10 partially supports itself with a circumferential portion of its distal end, seen from a circumferential direction resting on the trigger sleeve 15. Part of the trigger sleeve 15 is thus positioned between the protective sleeve 3 and the distal end of the coiled spring 10. In this way, the coiled spring 10 can be seen in FIG. 2a with its distal portion in an annular volume 9a which is formed by the exterior surface of the trigger sleeve 15 and an inner wall of the casing 2. In addition, the coiled spring 10 is supported at its proximal end on a projection 6e of a retainer element 6, as is shown in FIG. 2b. The retainer element 6 protrudes into the casing 2 and can slide axially without rotating. In its proximal portion, the coiled spring 10 is also arranged in an annular volume 9b, which is formed by the exterior surface of the retainer element 6 and the inner wall of the casing 2. The coiled spring 10 is thus only supported at its distal and proximal ends. The annular volumes 9a, 9b are significantly wider than the diameter of the wire D.sub.W of the coiled spring 10. In sections, the width WA of the annular volume 9a, 9b is approximately, twice as wide as the diameter D.sub.W of the wire. As such, the loops of the coiled spring 10 hardly, touch the walls of the annular volume 9a, 9b between the two ends of the coiled spring 10.

[0047] In the starting position of the protective sleeve 3, as shown in FIGS. 2a and 2b, the distal end of the protective sleeve 3 protrudes distally beyond the needle point of the injection needle 13a, initially preventing the needle point from being contacted, and therefor may be referred to as a needle protective sleeve.

[0048] In order to administer the medicine out of the product container 13, the distal end of the protective sleeve 3 is positioned on a patient's intended point of injection, the casing 2 is pushed toward the point of injection and the protective sleeve 3 is displaced from its starting position in the proximal direction relative to the casing 2, via the actuator stroke (HO. As a result of this, the coiled spring 10 is compressed and thus tensed, whereby the trigger sleeve 15 and the locking sleeve 8 are displaced together with the protective sleeve 3 via the actuator stroke (He). This state (with stroke He) is depicted in FIGS. 3a and 3b.

[0049] As a result of the displacement of the locking sleeve 8, e.g., in the proximal direction, a piston driving member 7 is released via a protrusion 6a, causing a movement in the distal direction along the release stroke (HA), by which the release of the medicine out of the product container 13 begins.

[0050] At the end of the release stroke (HA), the protrusions fib of the retainer element 6 are moved out of a recess 8b of the locking sleeve 8. Thus, the tensed coiled spring 10 can relax in part and then the retainer element 6 can accelerate in the proximal direction, as a result of which an acoustic and/or tactile signal is produced when the retainer element 6 meets an end signal stop 5e.

[0051] When the autoinjector 1 is removed from the injection point, the protective sleeve 3 is free to move back into a distal position; the coiled spring 10 relaxes and thus moves the trigger sleeve 15 and the protective sleeve 3 out of the actuation position into the protective position via the protective sleeve return stroke (distally along H.sub.B shown in the figures).

KEY FOR REFERENCE NUMBERS

[0052] 1 Autoinjector [0053] 2 Casing [0054] 3 Needle protective sleeve [0055] 3a Proximal end of sleeve 3 [0056] 5e Final signal stop [0057] 6 Retainer element [0058] 6a Protrusion [0059] 6b Protrusion [0060] 6e Retainer Projection [0061] 7 Driving member [0062] 8 Locking sleeve [0063] 8b Recess [0064] 9a Annular volume (proximal) [0065] 9b Annular volume (distal) [0066] 10 Coiled spring [0067] 13 Product container [0068] 13a Hypodermic needle [0069] 15 Trigger sleeve [0070] 20a First connection point [0071] 20b Second connection point [0072] 20c Third connection point [0073] 20d Fourth connection point