Dosage adjustment mechanism and injection pen

Abstract

This utility model belongs to the field of injection pen technology, specifically relating to a dosage adjustment mechanism and an injection pen, comprising: a dosage adjustment mechanism including: a graduated cylinder threadedly connected to the pen body, the inner wall of the graduated cylinder having a plurality of first sound-emitting teeth; a support cylinder inserted into the graduated cylinder and positioned circumferentially by a drug-propelling mechanism, the end of the support cylinder having a second firing part; and a sound-emitting ring sleeved on the end of the support cylinder, the end of the sound-emitting ring having a first firing part, the inner wall of the sound-emitting ring having a plurality of second sound-emitting teeth, wherein: when the graduated cylinder is screwed in, the second sound-emitting teeth are struck by the second firing part to produce sound; when the graduated cylinder is screwed out, the first sound-emitting teeth are struck by the first firing part to produce sound; by providing first sound-emitting teeth in the graduated cylinder and second sound-emitting teeth in the sound-emitting ring, sounds are emitted respectively when the graduated cylinder is screwed in / out to prompt the patient.

Description

Technical Field

[0001] This utility model belongs to the field of injection pen technology, specifically relating to a dosage adjustment mechanism and an injection pen. Background Technology

[0002] An injection pen is a portable medical device used for subcutaneous injection of drugs. It typically includes a dose adjustment mechanism, allowing patients to set the dosage as needed before injection. Patients can judge the dosage through multiple senses, including hearing, vision, and touch, during dose adjustment. Regarding hearing, existing injection pens usually use a sound-producing element; the number of times a sound is emitted when the scale is turned out increases the dosage. However, if too much is turned out and a dose reduction is needed, a rotation (screwing in) operation is performed, but no sound is emitted during rotation, preventing patients from reducing the dosage through hearing.

[0003] Therefore, how to solve the problem of the rotary mechanism failing to produce sound is a technical problem that urgently needs to be solved in this field.

[0004] It should be noted that the information disclosed in this background section is only for understanding the background technology of this application concept, and therefore, the above description is not considered to constitute prior art information. Utility Model Content

[0005] This disclosure provides at least one dosage adjustment mechanism and an injection pen.

[0006] In a first aspect, embodiments of this disclosure provide a dosage adjustment mechanism, comprising: a graduated cylinder threadedly connected to a pen body, the inner wall of the graduated cylinder having a plurality of first sound-emitting teeth; a support cylinder inserted into the graduated cylinder and positioned circumferentially by a drug-push mechanism, the end of the support cylinder having a second firing part; and a sound-emitting ring sleeved on the end of the support cylinder, the end of the sound-emitting ring having a first firing part, the inner wall of the sound-emitting ring having a plurality of second sound-emitting teeth, wherein: when the graduated cylinder is screwed in, the first firing part abuts against the first sound-emitting teeth, so that the sound-emitting ring rotates with the graduated cylinder, and the second sound-emitting teeth are struck by the second firing part to produce sound; when the graduated cylinder is screwed out, the second firing part abuts against the second sound-emitting teeth to restrict the rotation of the sound-emitting ring, and the first sound-emitting teeth are struck by the first firing part to produce sound.

[0007] In one optional embodiment, the first firing part includes a first firing spring; the first firing spring is arc-shaped, with one end connected to a sound-producing ring, and the other end of the first firing spring is provided with a first firing block, the first firing block abutting between first sound-producing teeth, wherein; when the scale cylinder is screwed out, the sound-producing ring is restricted from rotation, the first sound-producing teeth press against the first firing block to deform the first firing spring; when the protrusion of the first sound-producing tooth rotates past the first firing block, the first firing spring returns to its original position, so that the first firing block strikes the first sound-producing tooth to produce sound; when the scale cylinder is screwed in, the first firing block abutting between the first sound-producing teeth, so that the sound-producing ring rotates accordingly.

[0008] In one alternative embodiment, the sidewalls of the first firing block intersect with each other with a side edge, so that the sidewalls of the first firing block fit against the sidewalls of the first sound-producing tooth.

[0009] In one optional embodiment, the second firing part includes a second firing spring; the second firing spring is arc-shaped, with one end connected to a support cylinder, and the other end of the second firing spring is provided with a second firing block, the second firing block abutting between the second sound-producing teeth, wherein; when the scale cylinder is screwed in, the sound-producing ring rotates accordingly, the second sound-producing teeth press against the second firing block to deform the second firing spring; when the protrusion of the second sound-producing tooth rotates past the second firing block, the second firing spring returns to its original position, so that the second firing block strikes the second sound-producing tooth to produce sound; when the scale cylinder is screwed out, the second firing block abuts between the second sound-producing teeth to restrict the rotation of the sound-producing ring.

[0010] In one alternative embodiment, the sidewalls of the second firing block intersect with each other with a side edge, so that the sidewalls of the second firing block fit against the sidewalls of the second sound-producing tooth.

[0011] In one optional embodiment, a support ring is provided inside the graduated cylinder, the first sound-emitting tooth is disposed on the inner wall of the support ring, and the sound-emitting ring abuts against the end face of the support ring.

[0012] In one alternative embodiment, the first firing part includes a first firing spring adapted to strike a first sound-producing tooth; the second firing part includes a second firing spring adapted to strike a second sound-producing tooth; and the first and second firing springs have different thicknesses so that the sound produced when the graduated cylinder is screwed out / screwed in is different.

[0013] In one alternative implementation, the widths of the first firing clip and the second firing clip are not equal.

[0014] Secondly, this disclosure also provides an injection pen, comprising: a pen body; the aforementioned dosage adjustment mechanism, wherein the scale cylinder is threadedly connected to the pen body, and a limiting block is provided on the inner wall of the support cylinder; and a drug pushing mechanism disposed within the pen body, the drug pushing mechanism comprising a drug pushing cylinder, one end of which is inserted into the support cylinder, a limiting groove being formed along the axial direction on the side wall of the drug pushing cylinder, and the limiting block being engaged within the limiting groove.

[0015] The beneficial effect of this utility model is that, by setting a first sound-emitting tooth in the graduated cylinder and a second sound-emitting tooth in the sound-emitting ring, the first and second sound-emitting teeth emit sounds when the graduated cylinder is screwed out / screwed in, so as to prompt the patient and enable the patient to reduce the corresponding dose through hearing.

[0016] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objectives and other advantages of this invention are realized and obtained through the structures particularly pointed out in the description, claims, and drawings.

[0017] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 A perspective view of an injection pen provided in an embodiment of this disclosure; Figure 2 A cross-sectional view of an injection pen provided in an embodiment of this disclosure; Figure 3 An exploded view of an injection pen provided in an embodiment of this disclosure.

[0020] In the picture: 1. Scale cylinder; 11. First sound-producing tooth; 12. Support ring; 2. Support cylinder; 21. Second firing mechanism; 21a. Second firing fragment; 21b. Second firing block; 22. Limit block; 3. Sound-emitting ring; 31. First firing mechanism; 31a. First firing fragment; 31b. First firing block; 32. Second vocal tooth; 4. Pen body; 5. Drug pushing mechanism; 51. Drug pushing cylinder; 51a. Limiting groove. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0022] In this document, when it is mentioned that a first component is located on a second component, this can mean that the first component can be directly formed on the second component, or that a third component can be inserted between the first and second components. Furthermore, in the accompanying drawings, the thickness of the components may be exaggerated or reduced for the purpose of effectively describing the technical content.

[0023] In this document, when an element or layer is referred to as “located,” “joined to,” “connected to,” “attached to,” or “coupled to” another element or layer, it may be directly located, joined, connected, attached to, or coupled to the other element or layer, or there may be intermediate elements or layers present. Conversely, when an element is referred to as “directly on another element or layer,” “directly joined to,” “directly connected to,” “directly attached to,” or “directly coupled to” another element or layer, there may be no intermediate elements or layers present. Other terms used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items.

[0024] In this document, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0025] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0026] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0027] Research has found that in existing technologies, patients may over-rotate the graduated cylinder when increasing the dosage, and when it is necessary to screw it in, no sound is emitted, making it impossible for patients to reduce the dosage through hearing. This is the problem and purpose that the utility model aims to solve.

[0028] Based on the above research, this disclosure provides a dosage adjustment mechanism and an injection pen, which emits sound when the graduated cylinder is screwed in or out by providing a first sound-emitting tooth and a second sound-emitting tooth inside the graduated cylinder.

[0029] The shortcomings of the above solutions are the result of the utility model inventor's practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure should be considered as contributions made by the utility model inventor to this disclosure.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0032] See Figures 1 to 3 This embodiment illustrates a dosage adjustment mechanism, comprising: a graduated cylinder 1 threadedly connected to a pen body 4, the inner wall of the graduated cylinder 1 having a plurality of first sound-emitting teeth 11; a support cylinder 2 inserted into the graduated cylinder 1 and positioned circumferentially by a drug-push mechanism 5, the end of the support cylinder 2 having a second firing part 21; and a sound-emitting ring 3 sleeved on the end of the support cylinder 2, the end of the sound-emitting ring 3 having a first firing part 31, the inner wall of the sound-emitting ring 3 having a plurality of second sound-emitting teeth 32, wherein; when the graduated cylinder 1 is screwed in, the first firing part 31 abuts against the first sound-emitting teeth. The first sound-emitting tooth 11 is provided so that the sound-emitting ring 3 rotates with the scale cylinder 1, and the second sound-emitting tooth 32 is struck by the second firing part 21 to produce sound; when the scale cylinder 1 is rotated out, the second firing part 21 abuts against the second sound-emitting tooth 32 to restrict the rotation of the sound-emitting ring 3, and the first sound-emitting tooth 11 is struck by the first firing part 31 to produce sound; in short, by providing the first sound-emitting tooth 11 in the support cylinder 2 and the second sound-emitting tooth 32 in the sound-emitting ring 3, when the scale cylinder 1 is rotated out / in, the first sound-emitting tooth 11 and the second sound-emitting tooth 32 respectively emit sounds to prompt the patient, so that the patient can reduce the corresponding dose through hearing.

[0033] See Figures 1 to 3 In some embodiments, the first firing part 31 includes a first firing spring 31a; the first firing spring 31a is arc-shaped, with one end connected to the sound-emitting ring 3, and the other end of the first firing spring 31a is provided with a first firing block 31b, the first firing block 31b abutting between the first sound-emitting teeth 11, wherein; when the scale cylinder 1 is rotated out, the sound-emitting ring 3 is restricted from rotation, the first sound-emitting teeth 11 press the first firing block 31b to deform the first firing spring 31a, and when the protrusion of the first sound-emitting tooth 11 passes the first firing block 31b, the first firing spring 31a returns to its original position. The first firing block 31b strikes the first sound-producing tooth 11 to produce sound. When the scale cylinder 1 is screwed in, the first firing block 31b abuts against the first sound-producing tooth 11, so that the sound-producing ring 3 rotates accordingly. In short, one end of the first firing spring 31a is connected to the sound-producing ring 3, and its other end extends clockwise. When the scale cylinder 1 is screwed out clockwise, the first sound-producing tooth 11 can push the first firing block 31b, so that the first firing block 31b strikes the first sound-producing tooth 11 to produce sound. Furthermore, when the scale cylinder 1 is screwed in counterclockwise, the first firing block 31b abuts against the first sound-producing tooth 11, so that the sound-producing ring 3 rotates with the scale cylinder 1.

[0034] See Figures 2 to 3In some embodiments, the sidewalls of the first firing block 31b intersect with each other with a side edge, so that the sidewalls of the first firing block 31b fit against the sidewalls of the first sound-producing teeth 11; in short, the sidewalls of the first firing block 31b can fit against the sidewalls of adjacent first sound-producing teeth 11 respectively, so as to increase the compression distance of the first firing spring 31a, improve the striking force of the first firing spring 31a, and ensure stable sound production.

[0035] See Figures 1 to 3 In some embodiments, the second firing part 21 includes a second firing spring 21a; the second firing spring 21a is arc-shaped, with one end connected to the support cylinder 2, and the other end of the second firing spring 21a is provided with a second firing block 21b, which abuts against the second sound-emitting teeth 32; wherein, when the scale cylinder 1 is screwed in, the sound-emitting ring 3 rotates accordingly, and the second sound-emitting teeth 32 press the second firing block 21b to deform the second firing spring 21a; when the protrusion of the second sound-emitting teeth 32 passes the second firing block 21b, the second firing spring 21a returns to its original position. The second firing block 21b strikes the second sound-producing tooth 32 to produce sound. When the scale cylinder 1 is screwed out, the second firing block 21b abuts against the second sound-producing tooth 32 to restrict the rotation of the sound-producing ring 3. In short, one end of the second firing spring 21a is connected to the support cylinder 2, and the other end extends counterclockwise. When the scale cylinder 1 is screwed in counterclockwise, the second sound-producing tooth 32 can push the second firing block 21b, causing the second firing block 21b to strike the second sound-producing tooth 32 to produce sound. Furthermore, when the scale cylinder 1 is screwed out clockwise, the second firing block 21b abuts against the second sound-producing tooth 32, restricting the rotation of the sound-producing ring 3.

[0036] See Figures 2 to 3 In some embodiments, the sidewalls of the second firing block 21b intersect with each other with a side edge, so that the sidewalls of the second firing block 21b fit against the sidewalls of the second sound-producing teeth 32; in short, the sidewalls of the second firing block 21b can fit against the sidewalls of adjacent second sound-producing teeth 32 respectively, so as to increase the compression distance of the second firing spring 21a, improve the striking force of the second firing spring, and ensure stable sound production.

[0037] See Figure 2 In some embodiments, a support ring 12 is provided inside the scale cylinder 1, the first sound-emitting tooth 11 is disposed on the inner wall of the support ring 12, and the sound-emitting ring 3 abuts against the end face of the support ring 12; in short, when the scale cylinder 1 is rotated out, it will slide radially, and the support ring 12 can drive the sound-emitting ring 3 to rise, so as to prevent the first sound-emitting tooth 11 and the first firing block 31b from disengaging.

[0038] See Figures 2 to 3In some embodiments, the first firing part 31 includes a first firing spring 31a, which is adapted to strike the first sound-producing tooth 11; the second firing part 21 includes a second firing spring 21a, which is adapted to strike the second sound-producing tooth 32; and the first firing spring 31a and the second firing spring 21a have different thicknesses so that the sound produced when the scale cylinder 1 is screwed out / screwed in is different; and the first firing spring 31a and the second firing spring 21a have different widths; in short, the thickness and width of the first firing spring 31a and the second firing spring 21a are both designed to be different in order to change the elasticity of the first firing spring 31a and the second firing spring 21a, so that the timbre and / or volume are different when the scale cylinder 1 is screwed out / screwed in.

[0039] See Figures 1 to 3 This embodiment illustrates an injection pen, comprising: a pen body 4; the aforementioned dosage adjustment mechanism, wherein the scale cylinder 1 is threadedly connected inside the pen body 4, and a limiting block 22 is provided on the inner wall of the support cylinder 2; and a drug delivery mechanism 5 disposed inside the pen body 4, the drug delivery mechanism 5 including a drug delivery cylinder 51, one end of which is inserted into the support cylinder 2, and a limiting groove 51a is formed along the axial direction on the side wall of the drug delivery cylinder 51, and the limiting block 22 is engaged in the limiting groove 51a; in short, the support cylinder 2 and the drug delivery cylinder 51 are connected by a keyway and a key block, so that the support cylinder 2 can only slide radially along the drug delivery cylinder 51.

[0040] In the description of the embodiments of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0041] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence unless expressly indicated herein. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed above may be referred to as the second element, component, region, layer, or segment.

[0042] Spatially relative terms, such as “inside,” “outside,” “below,” “below,” “down,” “above,” “up,” etc., may be used herein to describe the relationship between one element or feature illustrated in the figures and another element or feature. In addition to the orientations depicted in the figures, spatially relative terms may be intended to cover different orientations of the device in use or operation. For example, if the device in the figure is flipped, an element described as “below” or “below” other elements or features would be oriented as “above” other elements or features. Thus, the example term “below” can cover both above and below orientations. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein are interpreted accordingly.

[0043] In the above discussion, unless otherwise stated, when used to describe numerical values, the terms “about,” “approximately,” “basically,” etc., indicate a change of + / - 10% in that value.

[0044] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A dosage adjustment mechanism, characterized in that, include: The scale cylinder (1) is threadedly connected inside the pen body (4), and the inner wall of the scale cylinder (1) is provided with a number of first sound-producing teeth (11). The support cylinder (2) is inserted into the graduated cylinder (1) and positioned in the circumferential position by the pusher mechanism (5). The end of the support cylinder (2) is provided with a second firing part (21). A sound-generating ring (3) is sleeved on the end of the support cylinder (2). The end of the sound-generating ring (3) is provided with a first firing part (31). The inner wall of the sound-generating ring (3) is provided with a plurality of second sound-generating teeth (32). When the scale cylinder (1) is screwed in, the first firing part (31) abuts against the first sound-producing tooth (11), so that the sound-producing ring (3) rotates with the scale cylinder (1), and the second sound-producing tooth (32) is struck by the second firing part (21) to produce sound; When the scale cylinder (1) is rotated out, the second firing part (21) abuts against the second sound-producing tooth (32) to restrict the rotation of the sound-producing ring (3), and the first sound-producing tooth (11) is struck by the first firing part (31) to produce sound.

2. The dosage adjustment mechanism as described in claim 1, characterized in that, The first firing part (31) includes a first firing piece (31a); The first firing spring (31a) is arc-shaped, with one end connected to the sound ring (3), and the other end of the first firing spring (31a) is provided with a first firing block (31b), which abuts against the first sound teeth (11). When the scale cylinder (1) is rotated out, the sound ring (3) is restricted from rotating. The first sound tooth (11) squeezes the first firing block (31b) to deform the first firing spring (31a). When the protrusion of the first sound tooth (11) passes the first firing block (31b), the first firing spring (31a) resets so that the first firing block (31b) strikes the first sound tooth (11) to produce sound. When the scale cylinder (1) is screwed in, the first firing block (31b) abuts against the first sound-producing teeth (11) so that the sound-producing ring (3) rotates accordingly.

3. The dosage adjustment mechanism as described in claim 2, characterized in that, The sidewalls of the first firing block (31b) intersect with each other with a side edge, so that the sidewalls of the first firing block (31b) fit against the sidewalls of the first sound-emitting tooth (11).

4. The dosage adjustment mechanism as described in claim 1, characterized in that, The second firing part (21) includes a second firing fragment (21a); The second firing spring (21a) is arc-shaped, with one end connected to the support cylinder (2), and the other end of the second firing spring (21a) is provided with a second firing block (21b), which abuts against the second sound-emitting teeth (32). When the scale cylinder (1) is screwed in, the sound ring (3) rotates accordingly, and the second sound tooth (32) squeezes the second firing block (21b) to deform the second firing spring (21a). When the protrusion of the second sound tooth (32) passes the second firing block (21b), the second firing spring (21a) resets, so that the second firing block (21b) strikes the second sound tooth (32) to produce sound. When the scale cylinder (1) is rotated out, the second firing block (21b) abuts against the second sound-producing teeth (32) to restrict the rotation of the sound-producing ring (3).

5. The dosage adjustment mechanism as described in claim 4, characterized in that, The sidewalls of the second firing block (21b) intersect with each other with a side edge so that the sidewalls of the second firing block (21b) fit against the sidewalls of the second sound-producing tooth (32).

6. The dosage adjustment mechanism as described in claim 1, characterized in that, A support ring (12) is provided inside the graduated cylinder (1), the first sound-emitting tooth (11) is provided on the inner wall of the support ring (12), and the sound-emitting ring (3) abuts against the end face of the support ring (12).

7. The dosage adjustment mechanism as described in claim 1, characterized in that, The first firing part (31) includes a first firing spring (31a), which is adapted to strike the first sound-emitting tooth (11). The second firing part (21) includes a second firing spring (21a), which is adapted to strike the second sound-emitting tooth (32); The first firing spring (31a) and the second firing spring (21a) have different thicknesses so that the sound produced when the scale cylinder (1) is screwed out / screwed in is different.

8. The dosage adjustment mechanism as described in claim 7, characterized in that, The widths of the first firing piece (31a) and the second firing piece (21a) are not equal.

9. An injection pen, characterized in that, include: Pen body (4); The dosage adjustment mechanism as described in any one of claims 1-8, wherein the scale cylinder (1) is threadedly connected to the pen body (4), and the inner wall of the support cylinder (2) is provided with a limit block (22). The medicine pushing mechanism (5) is located inside the pen body (4). The medicine pushing mechanism (5) includes a medicine pushing cylinder (51). One end of the medicine pushing cylinder (51) is inserted into the support cylinder (2). A limiting groove (51a) is opened along the axial direction on the side wall of the medicine pushing cylinder (51). The limiting block (22) is locked in the limiting groove (51a).

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