An automatic injection device

Abstract

This utility model discloses an automatic injection device, relating to the field of medical device technology, including a torsion spring assembly, a housing component, and a sleeve. The torsion spring assembly includes at least two spring coils, a first spring coil and a second spring coil. The two ends of each spring coil are respectively connected to the housing component and the sleeve. The housing component and the sleeve are coaxially arranged and can rotate relative to each other around the axis. When the housing component and the sleeve rotate relative to each other, each spring coil can generate an elastic torsional force between the housing component and the sleeve relatively independently. The torsional force between the housing component and the sleeve is provided by two or more spring coils. When the required torque of the housing component and the sleeve is specific, the number of rotations during torsion spring assembly can be reduced. When a larger injection force is required, it is not necessary to tighten the spring too many times to store preload. A smaller number of rotations or angles during assembly can provide a larger torque.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, and more specifically to an automatic injection device. Background Technology

[0002] Adjustable dosing injection pens are precise and convenient drug delivery tools with a wide range of applications. The pen incorporates a torsion spring, which, once assembled, has a preload torque. This torsional torque of the spring serves as the driving force for drug delivery. During administration, one end of the torsion spring remains fixed, while the other end rotates due to the torsional torque, releasing it.

[0003] If a larger injection force is required, the spring needs to be pre-tightened by several turns to store preload, and sometimes even a large number of turns is not enough to provide greater torque.

[0004] When the number of coils increases, more axial space is needed to accommodate the preload coils. Sometimes, due to the limited internal space of the product, it is necessary to compromise by using thinner and weaker spring wires to achieve the rated number of coils, in order to avoid increasing the axial space.

[0005] Therefore, how to reduce the number of rotations during torsion spring assembly without increasing the product's spatial dimensions is a technical problem that needs to be solved by those skilled in the art. Utility Model Content

[0006] The core of this utility model is to provide an automatic injection device. The torsion spring assembly has two or more spring coils, each of which is connected to the housing member and the sleeve respectively. When the housing member and the sleeve rotate relative to each other, the torsion spring can generate a larger torque, which helps to reduce the number of rotations during torsion spring assembly. The specific solution is as follows:

[0007] An automatic injection device includes: a torsion spring assembly, a housing component, and a sleeve;

[0008] The torsion spring assembly includes at least a first spring coil and a second spring coil along the axial direction from the distal end to the proximal end;

[0009] The two ends of the first spring coil are respectively connected to the shell cover component and the sleeve;

[0010] The two ends of the second spring coil are respectively connected to the shell cover component and the sleeve;

[0011] The shell cover component and the sleeve are coaxially arranged and can rotate relative to each other around the axis.

[0012] Optionally, the first and second spring coils have opposite helical directions, or the torsion spring assembly includes the plurality of spring coils, with the helical directions of the spring coils alternately opposite along the axial direction.

[0013] Optionally, the first spring coil and the second spring coil may have the same or different number of effective turns, or the torsion spring assembly may include multiple spring coils, all of which may have the same or different number of effective turns. Optionally, the cover member is connected to the proximal end of the first spring coil and the distal end of the second spring coil.

[0014] The sleeve is connected to the distal end of the first spring coil and the proximal end of the second spring coil.

[0015] Optionally, the proximal end of the first spring coil and the distal end of the second spring coil are integrally connected to form a middle connecting portion;

[0016] The middle section connecting part is hooked onto the shell cover component.

[0017] Optionally, the middle connecting part includes a first arc-shaped rod, an axial rod, and a second arc-shaped rod. One end of the first arc-shaped rod is connected to the proximal end of the first spring coil, one end of the second arc-shaped rod is connected to the distal end of the second spring coil, and the two ends of the axial rod are respectively connected to the other ends of the first arc-shaped rod and the second arc-shaped rod.

[0018] The radial distance between the axial rod and the axis of the torsion spring assembly is less than the coil radius of the first spring coil and the coil radius of the second spring coil.

[0019] Optionally, the cover component includes a cover and an extension tube, the extension tube being axially inserted into the coil of the torsion spring assembly;

[0020] The extension tube is used to connect the first spring coil and the second spring coil.

[0021] Optionally, a middle section protrusion is provided on the outer surface of the extension cylinder, and the middle section protrusion is located between the two axial ends of the sleeve in the axial direction.

[0022] Optionally, the proximal end of the first spring coil and the distal end of the second spring coil are connected to the middle protrusion.

[0023] Optionally, the middle section protrusion is used to hook the middle section connecting part formed by the integral connection of the proximal end of the first spring coil and the distal end of the second spring coil.

[0024] Optionally, the axial length of the middle section protrusion is less than the axial length of the axial rod of the middle section connecting part.

[0025] Optionally, the outer surface of the extension tube has one or two centrally symmetrical middle section protrusions;

[0026] Along the circumferential direction, one end of the middle section protrusion forms an acute angle with the outer surface of the extension cylinder, and the other end forms an obtuse angle with the outer surface of the extension cylinder.

[0027] Optionally, a distal hook is provided at the distal end of the first spring coil, and the distal hook hooks onto a first inner protrusion that protrudes from the inner surface of the sleeve;

[0028] The second spring coil has a proximal hook at its proximal end, and the distal hook is hooked into the slot of the second inner protrusion that protrudes from the inner surface of the sleeve.

[0029] Optionally, the inner surface of the sleeve is provided with one or two first inner protrusions that are centrally symmetrical, and one or two second inner protrusions that are centrally symmetrical.

[0030] Optionally, the cover has a flange that protrudes radially, and the flange is used to engage with a notch at the distal end of the pen casing of the automatic injection device to limit the cover circumferentially and axially.

[0031] Optionally, the cover has ribs that protrude axially to limit the maximum axial distance that the dose indicator of the automatic injection device can move in the injection pen.

[0032] The automatic injection device of this utility model includes a torsion spring assembly, a housing component, and a sleeve. The torsion spring assembly includes at least two spring coils, including a first spring coil and a second spring coil. The two ends of each spring coil are respectively connected to the housing component and the sleeve. Since the housing component and the sleeve are coaxially arranged, they can rotate relative to each other around the axis. When the housing component and the sleeve rotate relative to each other, each spring coil can generate an elastic torsional force between the housing component and the sleeve relatively independently. The torsional force between the housing component and the sleeve is provided by two or more spring coils. When the required torque of the housing component and the sleeve is specific, the number of rotations during the assembly of the torsion spring can be reduced. When a larger injection force is required, it is not necessary to tighten the spring too many times to store preload. A smaller number of rotations or angles during assembly can provide a larger torque. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is an axonometric sectional view of the torsion spring assembly, the housing component, and the sleeve in mutual cooperation.

[0035] Figure 2 This is an isometric sectional view of the torsion spring assembly and the sleeve in mutual engagement.

[0036] Figure 3 An axonometric sectional view showing the interaction between the torsion spring assembly and the housing component;

[0037] Figure 4A This is an isometric view of the torsion spring assembly.

[0038] Figure 4B This is a top view of the torsion spring assembly;

[0039] Figure 5A This is an axonometric drawing of the shell cover component;

[0040] Figure 5B This is a bottom view of the shell cover component;

[0041] Figure 6A This is a first-view axonometric cross-section of the sleeve.

[0042] Figure 6B This is a second-view isometric cross-sectional view of the sleeve.

[0043] Figure 7 This is an isometric sectional view of a specific embodiment of the automatic injection device of this utility model;

[0044] Figure 8 This is a partial structural isometric view of the automatic injection device of this utility model.

[0045] The image includes:

[0046] Torsion spring assembly 10; first spring coil 110; distal hook 111; middle connecting part 120; first arc-shaped rod 121; axial rod 122; second arc-shaped rod 123; second spring coil 130; proximal hook 131;

[0047] Shell cover component 20; shell cover 210; flange 211; rib 213; extension tube 220; middle section protrusion 221;

[0048] Sleeve 30; First inner protrusion 310; Second inner protrusion 320; Groove 321;

[0049] Pen casing 40; notch 410;

[0050] Dosage indicator 50. Detailed Implementation

[0051] To enable those skilled in the art to better understand the technical solution of this utility model, the automatic injection device of this utility model will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] The automatic injection device provided by this utility model can realize the quantitative injection of medicine. The torsion spring assembly 10 generates torque between the shell cover component 20 and the sleeve 30. The structural design of the torsion spring assembly 10 helps to reduce the rotation angle during assembly.

[0053] Combination Figure 1As shown, the diagram illustrates the assembly relationship of the torsion spring assembly 10, the housing member 20, and the sleeve 30 in a specific embodiment, with the dashed line C representing the axis. The automatic injection device of this utility model includes the torsion spring assembly 10, the housing member 20, and the sleeve 30, combined with... Figure 4A As shown, the torsion spring assembly 10 includes at least a first coil 110 and a second coil 130 along the axial direction from the distal end to the proximal end. That is, the entire torsion spring assembly 10 has two or more coils (including the first coil 110 and the second coil 130), each coil being a helical torsion spring, and each coil can generate torque relatively independently. Each torsion spring can be a completely independent structure or a structure fixed as a single unit. In this document, the proximal end refers to the injection end, and the distal end refers to the end furthest from the injection end.

[0054] For the entire torsion spring assembly 10, different spring coils are distributed along the axial direction. Since each spring coil independently generates torque and plays a role, the various spring coils of the entire torsion spring assembly 10 can be regarded as having an "interconnected" relationship. The torque generated by each spring coil is superimposed to form the total torque.

[0055] The torsion spring assembly 10 shown in the accompanying drawings of this utility model has two spring coils, namely a first spring coil 110 and a second spring coil 130. If there are more spring coils, they can be arranged along the axial direction. The number of coils of each spring coil is set independently, and it is not required that the number of coils of each spring coil be equal.

[0056] In one specific embodiment, the effective number of coils of each spring coil is equal or approximately equal. That is, the effective number of coils of the first spring coil 110 and the second spring coil 130 shown in the attached figures is equal; if the torsion spring assembly 10 includes a larger number of spring coil structures, then the effective number of coils of all spring coils is equal. The equal effective number of coils of each spring coil ensures that the deformation amplitude of each spring coil is consistent under stress.

[0057] Combination Figure 2 , Figure 3 As shown, the first spring coil 110 has its two axial ends connected to the cover member 20 and the sleeve 30, respectively. One end of the first spring coil 110 is connected to the cover member 20, and the other end is connected to the sleeve 30. One end of the first spring coil 110 is fixed, while the other end rotates. When the cover member 20 and the sleeve 30 rotate relative to each other, the first spring coil 110 generates a torque between the cover member 20 and the sleeve 30.

[0058] The two ends of the second spring coil 130 are connected to the cover member 20 and the sleeve 30, respectively. One end of the second spring coil 130 is connected to the cover member 20 and the other end is connected to the sleeve 30. One end of the axial ends of the second spring coil 130 is fixed and the other end rotates. When the cover member 20 and the sleeve 30 rotate relative to each other, the second spring coil 130 generates a torque between the cover member 20 and the sleeve 30.

[0059] The cover component 20 and the sleeve 30 are coaxially arranged, with the axis of the cover component 20 coinciding with the axis of the sleeve 30, and also coinciding with the axis of the torsion spring assembly 10. The axes of the torsion spring assembly 10, the cover component 20, and the sleeve 30 are as follows: Figure 1 As shown by the dashed line C.

[0060] The cover component 20 and the sleeve 30 can rotate relative to each other around the axis. When the cover component 20 and the sleeve 30 are subjected to an external torque and rotate relative to each other, the first spring coil 110 and the second spring coil 130 will generate torque respectively.

[0061] For an automatic injection device, after the torsion spring assembly 10 is installed, a certain preload torque is required. This preload torque is the initial torque, which provides a minimum torque guarantee and is the minimum force to facilitate the injection requirements. Before using the automatic injection device, the injection dose needs to be adjusted. When adjusting the injection dose, the shell cover component 20 and the sleeve 30 will rotate relative to each other, which will further increase the torque of the torsion spring assembly 10 on the basis of the preload torque (initial torque). The magnitude of the preload torque will affect the magnitude of the output force of the dose adjustment.

[0062] During the injection process, the shell cover component 20 and the sleeve 30 rotate in opposite directions, and the torque of the torsion spring assembly 10 gradually decreases. When the automatic injection device finishes injecting the preset dose of medicine, the torque of the torsion spring assembly 10 reaches the pre-tightening torque (initial torque).

[0063] Before each injection, the shell cover component 20 and the sleeve 30 need to be rotated relative to each other. The larger the injection dose, the greater the torque added to the shell cover component 20 and the sleeve 30 on the basis of the pre-tightening torque. After each injection is completed, the torsion spring assembly 10 returns to the pre-tightening torque.

[0064] Because the automatic injection device of this utility model adopts a brand-new torsion spring assembly 10, which has two or more spring coils, compared with the traditional torsion spring structure, under the conditions of equal wire diameter, equal total axial length, and equal outer diameter, and under the condition of equal rotation angle, the torsion spring assembly 10 of this utility model can generate greater torque. The torsion spring assembly 10 of this application has a smaller deformation range when the required torque is equal. Under the condition of a fixed internal space size of the automatic injection device, the required torque can be obtained by rotating a small torsion angle, reducing the space occupied inside the automatic injection device and helping to avoid a large operating space.

[0065] After the entire automatic injection device is assembled, the torsion spring assembly 10 generates a preload torque (initial torque). Generating this preload torque requires applying an external torque to rotate the cover component 20 and the sleeve 30 relative to each other, causing the torque of the torsion spring assembly 10 to reach the preload torque from zero. For a given automatic injection device, the required preload torque is a constant preset value. Using the torsion spring assembly 10 provided by this invention, compared to traditional torsion spring structures, when generating the same preload torque, the relative rotation angle between the cover component 20 and the sleeve 30 is less. Using the same wire diameter, this helps to reduce product size, thereby reducing costs and product weight.

[0066] Based on the above solution, this utility model provides a helical structure for the first spring coil 110 and the second spring coil 130, wherein the helical directions of the first spring coil 110 and the second spring coil 130 are opposite, combined with Figure 4A As shown, the first spring coil 110 is a counterclockwise spiral when viewed from above (from far end to near end), and the second spring coil 130 is a clockwise spiral when viewed from above.

[0067] When the torsion spring assembly 10 includes the plurality of spring coils (more than two spring coils), the helical direction of each spring coil alternately reverses in the axial direction. For example, in the order from the distal end to the proximal end, each spring coil is arranged in a helical direction of clockwise → counterclockwise → clockwise → counterclockwise... or in a helical direction of counterclockwise → clockwise → counterclockwise → clockwise...

[0068] Based on the opposite helical directions of the first spring coil 110 and the second spring coil 130, combined Figure 3 As shown, the first spring coil 110 is positioned closer to the distal end on the torsion spring assembly 10, while the second spring coil 130 is positioned closer to the proximal end on the torsion spring assembly 10.

[0069] In one specific embodiment, the cover member 20 is connected to the proximal end of the first spring coil 110 and the distal end of the second spring coil 130. The proximal end of the first spring coil 110 and the distal end of the second spring coil 130 are close to each other, and the proximal end of the first spring coil 110 and the distal end of the second spring coil 130 can be connected as one piece or be independent of each other; the proximal end of the first spring coil 110 and the distal end of the second spring coil 130 are connected to the same structure of the cover member 20, which simplifies the structural design of the cover member 20 and facilitates assembly.

[0070] The sleeve 30 is connected to the distal end of the first spring coil 110 and the proximal end of the second spring coil 130. The distal end of the first spring coil 110 and the proximal end of the second spring coil 130 are located at the two ends of the entire torsion spring assembly 10 and are far apart from each other. Therefore, at least two connecting structures need to be provided on the sleeve 30, which are respectively connected to the distal end of the first spring coil 110 and the proximal end of the second spring coil 130.

[0071] In some embodiments, combined with Figure 4A As shown, the proximal end of the first spring coil 110 and the distal end of the second spring coil 130 are integrally connected to form the middle connecting part 120. The entire torsion spring assembly 10 is formed by bending and spiraling a single steel wire or other material wire.

[0072] In this embodiment, the first spring coil 110, the middle connecting portion 120, and the second spring coil 130 are fixed as a single unit. Besides this structure, the first spring coil 110 and the second spring coil 130 can also be two completely independent torsion spring structures. It should be noted that when the first spring coil 110 and the second spring coil 130 are independent of each other, the helical direction of the first spring coil 110 and the helical direction of the second spring coil 130 can be the same or different.

[0073] The middle connecting part 120 is hooked onto the cover member 20. Through this structure, the proximal end of the first spring coil 110 and the distal end of the second spring coil 130 are hooked onto the cover member 20, simplifying the assembly between the torsion spring assembly 10 and the cover member 20.

[0074] Combination Figure 2 , Figure 3 As shown, in this embodiment, the middle connecting portion 120 includes a first arc-shaped rod 121, an axial rod 122, and a second arc-shaped rod 123. One end of the first arc-shaped rod 121 is connected to the proximal end of the first spring coil 110, and the first arc-shaped rod 121 is tangent to the proximal helical end of the first spring coil 110. One end of the second arc-shaped rod 123 is connected to the distal end of the second spring coil 130, and the second arc-shaped rod 123 is tangent to the distal helical end of the second spring coil 130. The two ends of the axial rod 122 are respectively connected to the other ends of the first arc-shaped rod 121 and the second arc-shaped rod 123. In a specific structure, the tangent of the first arc-shaped rod 121 is perpendicular to the axial rod 122, and the tangent of the second arc-shaped rod 123 is perpendicular to the axial rod 122. The first arc-shaped rod 121, the axial rod 122, and the second arc-shaped rod 123 form a "U"-shaped structure. It should be noted that the tangent of the first arc-shaped rod 121 is not necessarily perpendicular to the axial rod 122, and the tangent of the second arc-shaped rod 123 is not necessarily perpendicular to the axial rod 122. For example, the first arc-shaped rod 121, the axial rod 122, and the second arc-shaped rod 123 can approximately form the top side and two hypotenuses of an isosceles trapezoid.

[0075] The helical lines constituting the first spring coil 110 are located on the same cylindrical surface, and the helical lines constituting the second spring coil 130 are also located on the same cylindrical surface. The diameters of the two cylindrical surfaces are equal, and their axes coincide; this axis is also the axis of the entire torsion spring assembly 10. The radial distance between the axial rod 122 and the axis C of the entire torsion spring assembly 10 is less than the coil radius of the first spring coil 110 and the coil radius of the second spring coil 130. Figure 4BAs shown, D represents the radius of the first spring coil 110 and the radius of the second spring coil 130, and d represents the distance between the axial rod 122 and the axis C (center), satisfying: d < D.

[0076] Axial rod 122 is parallel to the axis and is the closest radial distance from axis C to the entire 120. The first arc-shaped rod 121 extends from the first spring coil 110 towards axial rod 122, with the distance from axis C gradually decreasing. Similarly, the second arc-shaped rod 123 extends from the second spring coil 130 towards axial rod 122, with the distance from axis C gradually decreasing. (Viewed from top view...) Figure 4B The first arc-shaped rod 121 and the second arc-shaped rod 123 coincide, and the first arc-shaped rod 121 and the second arc-shaped rod 123 are at the same radial distance from the axis C, and are subjected to the same force during use.

[0077] Combination Figure 3 , Figure 5A As shown, in one embodiment, the cover component 20 includes a cover 210 and an extension cylinder 220. The cover 210 is a plate-like structure perpendicular to the axis, and the extension cylinder 220 is a hollow cylindrical structure parallel to the axis. The cover 210 and the extension cylinder 220 are fixed as one piece and can be integrally formed.

[0078] The outer diameter of the extension tube 220 is smaller than the inner diameter of the first spring coil 110 and the second spring coil 130 of the torsion spring assembly 10. The extension tube 220 is axially inserted into the torsion spring assembly 10. The outer diameter of the cover 210 is larger than the outer diameter of the first spring coil 110 and the second spring coil 130, and the cover 210 cannot pass through the first spring coil 110 and the second spring coil 130. The length of the extension tube 220 should be greater than the axial length of the first spring coil 110. The extension tube 220 extends into the first spring coil 110 from its distal end, and the proximal end of the extension tube 220 extends axially beyond the first spring coil 110 to mate with the intermediate connecting portion 120.

[0079] The extension tube 220 is used to connect the first spring coil 110 and the second spring coil 130. The extension tube 220 can be provided with an opening or a protrusion structure to achieve the structure with the first spring coil 110 and the second spring coil 130.

[0080] Combination Figure 3 As shown, in a specific embodiment, a middle section protrusion 221 is provided on the outer surface of the extension cylinder 220. The middle section protrusion 221 is located between the two axial ends of the sleeve 30 in the axial direction and protrudes from the cylindrical outer surface of the extension cylinder 220.

[0081] The proximal end of the first spring coil 110 and the distal end of the second spring coil 130 are connected to the middle protrusion 221. A connection hole can be provided on the middle protrusion 221, or it can be directly hooked onto the middle protrusion 221.

[0082] In one specific embodiment, the middle section protrusion 221 is used to engage with the middle section connecting part 120, and torque is applied to the middle section connecting part 120 through the middle section protrusion 221.

[0083] The axial length l of the middle section protrusion 221 is less than the axial length L of the axial rod 122, l < L. When the entire torsion spring assembly 10 and the shell cover component 20 are assembled together axially, there is a certain amount of axial movement between the middle section protrusion 221 and the middle section connecting part 120. During assembly, the two ends of the torsion spring assembly 10 are first connected to the sleeve 30, and then the shell cover component 20 is inserted into the near end along the axial direction. When the middle section connecting part 120 is just hooked onto the middle section protrusion 221, the shell cover component 20 is not yet fixed. At this time, the shell cover component 20 can rotate relative to the sleeve 30 around the axis. After the shell cover component 20 drives the middle section connecting part 120 to rotate a predetermined number of turns, the pre-tightening torque is reached. Then, the shell cover component 20 is further moved to the near end, and the shell cover component 20 and the pen shell 40 are engaged with each other. The shell cover component 20 cannot rotate and is fixed relative to the pen shell 40. The torsion spring assembly 10 maintains the pre-tightening torque. During use, when it is necessary to adjust the injection dosage, the shell cover component 20 remains fixed, and the sleeve 30 is rotated to increase the torque of the torsion spring assembly 10.

[0084] Theoretically, a single mid-section protrusion 221 on the outer surface of the extension tube 220 is sufficient for normal operation. However, in some embodiments, combined with... Figure 5A As shown, the outer surface of the extension cylinder 220 is centrally symmetrically provided with two or more intermediate protrusions 221, but only one intermediate protrusion 221 hooks onto the intermediate connecting part 120. With multiple intermediate protrusions 221, when the axial position of the intermediate protrusion 221 coincides with the intermediate connecting part 120, it can automatically hook onto the intermediate connecting part 120 by simply rotating the cover member 20 by a certain angle. For example, when two intermediate protrusions 221 are provided, the cover member 20 can be rotated up to 180° to hook the intermediate protrusions 221 onto the intermediate connecting part 120; when three intermediate protrusions 221 are provided, the cover member 20 can be rotated up to 120° to hook the intermediate protrusions 221 onto the intermediate connecting part 120. The use of two or more intermediate protrusions 221 facilitates quick hooking during assembly.

[0085] Along the circumferential direction, one end of the middle section protrusion 221 forms an acute angle with the outer surface of the extension cylinder 220, and the other end forms an obtuse angle with the outer surface of the extension cylinder 220. Figure 5B As shown, viewed from below, the obtuse angle between the tangent at one end of the middle protrusion 221 and the tangent on the outer surface of the extension cylinder 220 is α, and the acute angle between the tangent at the other end of the middle protrusion 221 and the tangent on the outer surface of the extension cylinder 220 is β, where α > β. Furthermore, one end of the obtuse angle has a smooth arc-shaped surface. Figure 5BTaking the direction of the display as an example, when the cover component 20 rotates counterclockwise, the middle connecting part 120 can pass over the middle protrusion 221 at the obtuse angle and then be inserted into the acute angle of the middle protrusion 221. The counterclockwise rotation of the cover component 20 cannot cause the torsion spring assembly 10 to twist and generate preload torque. When the cover component 20 rotates clockwise, the acute angle of the middle protrusion 221 hooks the middle connecting part 120, causing the torsion spring assembly 10 to twist and generate torque.

[0086] Combination Figure 2 , Figure 4A As shown, a distal hook 111 is provided at the distal end of the first spring coil 110. The distal hook 111 is hooked onto a first inner protrusion 310 that protrudes from the inner surface of the sleeve 30. The first inner protrusion 310 is a block structure that protrudes radially from the inner surface of the sleeve 30. The distal hook 111 is bent at an "L" shaped right angle and is hooked onto the first inner protrusion 310.

[0087] The second spring coil 130 has a proximal hook 131 at its proximal end. The proximal hook 131 is bent at an L-shape at a right angle and hooks into the slot 321 of the second inner protrusion 320 that protrudes from the inner surface of the sleeve 30. The second inner protrusion 320 is a block-shaped structure that protrudes radially from the inner surface of the sleeve 30. The second inner protrusion 320 is an arc-shaped block. The slot 321 is opened axially through the second inner protrusion 321. The slot 321 is arc-shaped, and the proximal hook 131 is inserted into the slot 321 to hook and engage.

[0088] The shape design of the distal hook 111 and the proximal hook 131 is not limited to the above description, as long as they can form a hook-and-hang combination.

[0089] Combination Figure 6A , Figure 6B As shown, in one embodiment, the inner surface of the sleeve 30 is provided with two first inner protrusions 310 in a centrally symmetrical manner. At the same time, one of the first inner protrusions 310 is hooked and connected to the distal hook 111. The inner surface of the sleeve 30 is provided with two second inner protrusions 320 in a centrally symmetrical manner. At the same time, a groove 321 provided on one of the second inner protrusions 320 is hooked and connected to the proximal hook 131. By providing two first inner protrusions 310 and two inner protrusions 320, it is convenient to position and hook the distal hook 111 and the proximal hook 131 during assembly.

[0090] The first inner protrusion 310 and the second inner protrusion 320 can also be provided as one each; providing two is for ease of assembly.

[0091] The cover 210 has a radially protruding flange 211, wherein two or more flanges 211 are provided, and they are combined. Figure 5A , Figure 5B As shown, four flanges 211 are provided, each flange 211 protruding radially from the outer peripheral edge of the cover 210.

[0092] Combination Figure 8 As shown, four notches 410 are provided at the distal end of the pen shell 40. The notches 410 and flanges 211 correspond one-to-one. The flanges 211 engage with the notches 410 at the distal end of the pen shell 40 of the automatic injection device to limit the shell cover 210 in both the circumferential and axial directions. The notches 410 are located at the distal end of the pen shell 40 and are U-shaped. When the shell cover component 20 is inserted into the torsion spring assembly 10 in the axial direction, the flanges 211 are embedded in the notches 410, and the shell cover component 20 cannot rotate, forming a circumferential limit. At the same time, the shell cover component 20 contacts the pen shell 40 in the axial direction, and the axial position of the shell cover component 20 is also limited by the pen shell 40.

[0093] The pen shell 40 is the external body of the entire automatic injection device and is held by the user during use. The pen shell 40 can be considered to be fixed. The shell cover component 20 is relatively fixed to the pen shell 40. During use, the shell cover component 20 remains fixed. When adjusting the dosage, the sleeve 30 rotates relative to the shell cover component 20.

[0094] The cover 210 has a rib 213 protruding axially. The rib 213 is a structure that protrudes proximally from the surface of the cover 210. The rib 213 is used to limit the maximum axial distance that the dose indicator 50 of the automatic injection device can move within the injection pen. Figure 7 As shown, the dosage indicator 50 can rotate with the sleeve 30. When adjusting the dosage, as the rotation angle increases, the indication scale of the dosage indicator 50 increases. A display window is provided on the pen housing 40 of the automatic injection device to show the user the current corresponding injection dosage. When the dosage is increased, the dosage indicator 50 and the sleeve 30 rotate synchronously, and the dosage reading increases. During injection, the dosage indicator 50 and the sleeve 30 rotate synchronously towards the smaller dosage value. After the injection is completed, the reading of the dosage indicator 50 returns to zero. By providing a rib 213 on the housing 210, the dosage indicator 50 cannot continue to rotate when it reaches the maximum dosage, thus limiting the maximum dosage of a single injection.

[0095] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An automatic injection device, characterized in that, include: Torsion spring assembly (10), cover assembly (20) and sleeve (30); The torsion spring assembly (10) includes at least a first spring coil (110) and a second spring coil (130) along the axial direction from the distal end to the proximal end. The two ends of the first spring coil (110) are respectively connected to the shell cover component (20) and the sleeve (30); The two ends of the second spring coil (130) are respectively connected to the shell cover component (20) and the sleeve (30); The shell cover component (20) and the sleeve (30) are coaxially arranged and can rotate relative to each other around the axis.

2. The automatic injection device according to claim 1, characterized in that, The first spring coil (110) and the second spring coil (130) have opposite helical directions, or the torsion spring assembly (10) includes multiple spring coils, and the helical directions of each spring coil alternately reverse along the axial direction.

3. The automatic injection device according to claim 1, characterized in that, The effective number of coils of the first spring coil (110) and the second spring coil (130) are equal or unequal, or the torsion spring assembly (10) includes multiple spring coils, and the effective number of coils of all spring coils is equal or unequal.

4. The automatic injection device according to claim 1, characterized in that, The shell cover component (20) is connected to the proximal end of the first spring coil (110) and the distal end of the second spring coil (130); The sleeve (30) is connected to the distal end of the first spring coil (110) and the proximal end of the second spring coil (130).

5. The automatic injection device according to claim 2, characterized in that, The proximal end of the first spring coil (110) and the distal end of the second spring coil (130) are integrally connected to form a middle connecting part (120). The middle section connecting part (120) is hooked onto the shell cover component (20).

6. The automatic injection device according to claim 5, characterized in that, The middle connecting part (120) includes a first arc-shaped rod (121), an axial rod (122), and a second arc-shaped rod (123). One end of the first arc-shaped rod (121) is connected to the proximal end of the first spring coil (110), and one end of the second arc-shaped rod (123) is connected to the distal end of the second spring coil (130). The two ends of the axial rod (122) are respectively connected to the other end of the first arc-shaped rod (121) and the other end of the second arc-shaped rod (123). The radial distance between the axial rod (122) and the axis of the torsion spring assembly (10) is less than the radius of the first spring coil (110) and the radius of the second spring coil (130).

7. The automatic injection device according to claim 1, characterized in that, The shell cover component (20) includes a shell cover (210) and an extension tube (220), the extension tube (220) being axially inserted into the spring coil of the torsion spring assembly (10); The extension tube (220) is used to connect the first spring coil (110) and the second spring coil (130).

8. The automatic injection device according to claim 7, characterized in that, The outer surface of the extension tube (220) is provided with a middle section protrusion (221), which is located between the two ends of the sleeve (30) in the axial direction.

9. The automatic injection device according to claim 8, characterized in that, The proximal end of the first spring coil (110) and the distal end of the second spring coil (130) are connected to the middle protrusion (221).

10. The automatic injection device according to claim 8, characterized in that, The middle section protrusion (221) is used to hook the middle section connecting part (120) formed by the integral connection of the proximal end of the first spring coil (110) and the distal end of the second spring coil (130).

11. The automatic injection device according to claim 10, characterized in that, The axial length of the middle section protrusion (221) is less than the axial length of the axial rod (122) of the middle section connecting part (120).

12. The automatic injection device according to claim 8, characterized in that, The outer surface of the extension tube (220) is provided with one or two centrally symmetrical middle section protrusions (221); Along the circumferential direction, one end of the middle section protrusion (221) forms an acute angle with the outer surface of the extension cylinder (220), and the other end forms an obtuse angle with the outer surface of the extension cylinder (220).

13. The automatic injection device according to claim 5, characterized in that, The first spring coil (110) is provided with a distal hook (111) at its distal end, and the distal hook (111) is hooked onto the first inner protrusion (310) that protrudes from the inner surface of the sleeve (30). The second spring coil (130) has a proximal hook (131) at its proximal end, and the distal hook (111) is hooked into the slot (321) of the second inner protrusion (320) that protrudes from the inner surface of the sleeve (30).

14. The automatic injection device according to claim 1, characterized in that, The inner surface of the sleeve (30) is provided with one or two first inner protrusions (310) that are centrally symmetrical, and one or two second inner protrusions (320) that are centrally symmetrical.

15. The automatic injection device according to claim 7, characterized in that, The cover (210) has a flange (211) protruding radially. The flange (211) is used to engage with a notch (410) at the distal end of the pen shell (40) of the automatic injection device to limit the cover (210) circumferentially and axially.

16. The automatic injection device according to claim 7, characterized in that, The cover (210) is provided with ribs (213) protruding axially to limit the maximum axial distance that the dose indicator (50) of the automatic injection device can move in the injection pen.

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