Injection pen body and injection pen

Abstract

This utility model belongs to the field of medical technology, and particularly relates to syringes. This utility model provides an upper pen body and an injection pen, including: an upper shell; a positioning bracket disposed inside the upper shell; the positioning bracket includes: an annular base concentrically disposed inside the upper shell, the annular base being adapted to fit over the plunger of the injection pen, and its inner diameter matching the outer diameter of the plunger; several connecting ears, one end of which is integrally connected to the annular base, and the other end connected to the inner wall of the upper shell; wherein, when the plunger is configured to move along the axis of the upper shell, the annular base is adapted to constrain the radial movement of the plunger; by providing an annular base, this utility model ensures a tight fit between the plunger and the plunger, suppressing radial offset of the plunger during movement, and ensuring that the force of the plunger is transmitted linearly along the axial direction, ultimately guaranteeing a high degree of accuracy and consistency in the dosage of each injection, greatly improving the safety and reliability of injection therapy.

Description

Technical Field

[0001] This utility model belongs to the field of medical technology, specifically relating to syringes, and more particularly to the upper body of an injection pen and an injection pen. Background Technology

[0002] For chronic diseases, medical professionals and patients who self-administer medications at home often use injection pens to administer drugs for treatment. Injection pen therapy can be categorized into diabetes treatment, growth hormone therapy, osteoporosis treatment, fertility treatment, and other therapies.

[0003] In related technologies, such as the injection pen and push rod fixing structure with application number 202520541155X, the radial positioning of the push rod is achieved through an activation spring and a long rod. The long rod is fixed to the back cover, the activation spring is sleeved on the spring of the back cover, and the push rod is sleeved on the activation spring. Since the activation spring itself has no radial support strength, and the outer diameter of the long rod differs significantly from the inner diameter of the push rod, the push rod is prone to radial offset (eccentricity) during the process of being activated and pushed outward, resulting in the inability to drive the medicine bottle to dispense liquid or inaccurate dispensing.

[0004] Therefore, how to avoid radial displacement when the push rod is excited is a technical problem that urgently needs to be solved in this field.

[0005] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Utility Model Content

[0006] This disclosure provides at least one upper pen body and injection pen for injection, in order to solve the technical problem of radial displacement when the push rod is activated.

[0007] In a first aspect, embodiments of this disclosure provide an upper pen body for injection, comprising: an upper housing; a positioning bracket disposed inside the upper housing; the positioning bracket comprising: an annular base concentrically disposed inside the upper housing, the annular base being adapted to be fitted onto the plunger body of the injection pen, and its inner diameter being adapted to the outer diameter of the plunger body; a plurality of connecting ears, one end of which is integrally connected to the annular base, and the other end of which is connected to the inner wall of the upper housing; wherein, when the plunger body is configured to move along the axis of the upper housing, the annular base is adapted to constrain the radial movement of the plunger body.

[0008] In one optional embodiment, the first end face of the annular base is provided with a guide surface, which is an arc-shaped surface or a chamfered surface.

[0009] In one alternative embodiment, the second end face of the annular base is an abutment surface adapted to fit with the end of the syringe pen vial.

[0010] In one alternative embodiment, a weight-reducing hollow section is formed between the adjacent connecting lugs and the sidewall of the annular base.

[0011] In one alternative embodiment, a deformation groove is provided near the annular base of the connecting ear.

[0012] In one alternative embodiment, the connecting lug includes two bends that form a multi-segmented, zigzag-shaped cross-section connecting lug, the bends being adapted to counteract the recoil force of the medicine bottle.

[0013] In one optional embodiment, one end of the upper housing is provided with a plug-in portion, the outer diameter of which is smaller than the outer diameter of the upper housing, and the positioning bracket is located inside the plug-in portion.

[0014] Secondly, this disclosure also provides an injection pen, comprising: a rear cover with an activation spring sleeved at its center; an upper shell inserted into the rear cover and having a positioning bracket inside; a lower shell inserted into the other end of the upper shell, with a cap inserted into the end of the lower shell away from the upper shell; and a push rod disposed within the positioning bracket, one end of the push rod abutting against the activation spring, and the other end having a guide rod adapted to abut against a medicine bottle.

[0015] In one optional embodiment, the positioning bracket includes: an annular base concentrically disposed within the upper housing, the annular base being adapted to be fitted onto the push rod body, and its inner diameter being adapted to the outer diameter of the push rod body; a plurality of connecting ears, one end of which is integrally connected to the annular base and the other end of which is connected to the inner wall of the upper housing; wherein, when the push rod body is configured to move along the axis of the upper housing, the annular base is adapted to constrain the radial movement of the push rod body.

[0016] In one optional embodiment, the first end face of the annular base is provided with a guide surface, which is an arc-shaped surface or a chamfered surface; the second end face of the annular base is an abutment surface, which is adapted to fit with the end of the syringe bottle.

[0017] The beneficial effects of this utility model are that it provides an upper pen body and an injection pen for injection, which, by setting an annular base, fits tightly with the push rod body, suppressing radial offset (eccentricity) of the push rod body during movement, avoiding jamming, wear, or abnormal friction with other parts inside the pen caused by the eccentricity of the push rod body, thereby ensuring that the force of the push rod body is transmitted in a straight line along the axial direction, ultimately ensuring the high accuracy and consistency of each injection dose, and greatly improving the safety and reliability of injection treatment.

[0018] 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 and the accompanying drawings.

[0019] 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

[0020] 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.

[0021] Figure 1 A perspective view of the push rod and the upper housing after assembly, provided in an embodiment of this disclosure; Figure 2 A perspective view of the push rod and the upper housing before assembly, provided in an embodiment of this disclosure; Figure 3 A perspective view of the positioning bracket provided in an embodiment of this disclosure; Figure 4 A perspective view of an injection pen provided in an embodiment of this disclosure.

[0022] In the picture: 1. Back cover; 2. Upper housing; 21. Insertion part; 3. Lower casing; 4. Cap body; 5. Activate the spring; 6. Positioning bracket; 61. Annular base; 62. Guide surface; 63. Connecting ear; 631. Deformation groove; 632. Bending part; 64. Weight-reducing hollow part; 7. Push rod body; 71. Guide rod; 8. Medicine bottles. Detailed Implementation

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Research has revealed shortcomings in existing technologies. For example, in the injection pen and push rod fixing structure with application number 202520541155X, the radial positioning of the push rod is achieved through an activation spring and a long rod. The long rod is fixed to the back cover, the activation spring is sleeved on the spring of the back cover, and the push rod is sleeved on the activation spring. Since the activation spring itself has no radial support strength, and the outer diameter of the long rod differs significantly from the inner diameter of the push rod, the push rod is prone to radial displacement during the process of being activated and pushed outward, resulting in failure to drive the medicine bottle to dispense liquid or inaccurate dispensing.

[0029] Therefore, how to avoid radial displacement when the push rod is excited is a technical problem that urgently needs to be solved in this field.

[0030] 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.

[0031] 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.

[0032] The following detailed description, with reference to the accompanying drawings, describes some embodiments of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0033] like Figures 1 to 4 As shown, some embodiments provide an upper pen body for injection, including: an upper shell 2; the upper shell 2 is the core structural component and carrier of the injection pen, serving to connect the rear cover 1 and the lower shell 3, while its interior accommodates and fixes the positioning bracket 6, providing a precise guide channel for the movement of the push rod 7.

[0034] The upper shell 2, as the main body of the pen body, integrates and assembles the various functional modules of the injection pen (excitation mechanism, guiding mechanism, medicine bottle), ensuring the integrity and stability of the overall structure.

[0035] The positioning bracket 6 is located inside the upper housing 2. The positioning bracket 6 is an independent functional component, which is fixed in the inner cavity of the upper housing 2 by means of interference fit, snap-fit ​​or welding. The core function of the positioning bracket 6 is to accurately guide and support the push rod body 7.

[0036] The positioning bracket 6 includes an annular base 61, which is concentrically arranged inside the upper housing 2. The annular base 61 is adapted to be fitted onto the outside of the plunger 7 of the injection pen, and its inner diameter is matched with the outer diameter of the plunger 7. The annular base 61 is the core functional part of the positioning bracket 6. Its inner diameter is precisely designed to form a small gap dynamic fit with the outer diameter of the plunger 7. When the plunger 7 moves at high speed under the action of the excitation spring 5, the annular base 61 wraps around it radially, allowing it to move only along the axial direction, effectively suppressing any sway or vibration.

[0037] The annular base 61 has a precise guiding effect: ensuring that the movement trajectory of the push rod 7 is strictly along the axial direction, preventing problems such as jamming, accelerated wear, or misalignment with the medicine bottle 8 caused by push rod misalignment.

[0038] The annular base 61 ensures reliable injection: precise linear motion ensures that the guide rod 71 at the end of the push rod 7 is aligned with the rubber stopper of the vial 8, allowing the liquid to be smoothly dispensed with accurate dosage. The annular base 61 has the effect of reducing friction and wear: it provides uniform support through surface contact, which is more stable and less wear-prone than line contact (such as guide ribs).

[0039] Several connecting ears 63, one end of which is integrally connected to the annular base 61 and the other end is connected to the inner wall of the upper housing 2; wherein, when the push rod body 7 is configured to move along the axis of the upper housing 2, the annular base 61 is adapted to constrain the radial movement of the push rod body 7.

[0040] The connecting ear 63 is the connection structure between the positioning bracket 6 and the upper shell 2. One end of it is integrally connected to the outer wall of the annular base 61 (by injection molding), and the other end extends in the form of a cantilever and is fixed on the inner wall of the upper shell 2, thereby "suspending" the annular base 61 and positioning it at the center of the upper shell 2.

[0041] The connecting ears 63 enable the positioning bracket 6 and the push rod body 7 to be positioned concentrically: multiple connecting ears 63 are evenly distributed circumferentially, which can ensure that the axis of the annular base 61 and the upper shell 2 are concentric, thereby ensuring that the push rod body 7 and the entire pen body are concentric.

[0042] The connecting lug 63 provides structural support: when the push rod moves, its reaction force is transmitted to the connecting lug 63 through the annular base 61, and then distributed to the upper shell 2, ensuring the strength and stability of the structure.

[0043] The first end face of the annular base 61 is provided with a guide surface 62, which is an arc-shaped surface or a chamfered surface; the second end face of the annular base 61 is an abutment surface, which is adapted to fit with the end of the vial 8 of the injection pen.

[0044] The guide surface 62 is an arc-shaped or chamfered surface machined on the first end face of the annular base 61 (usually the upper end face facing the excitation spring 5); it can guide and correct the deviation when the push rod body 7 is initially installed or if a slight deviation occurs, so that the end of the push rod body 7 can smoothly and easily enter the inner hole of the annular base 61.

[0045] The guide surface 62 facilitates assembly by significantly reducing the difficulty of accurately inserting the slender push rod 7 into the inner hole, thus improving production and assembly efficiency. The guide surface 62 also prevents jamming: even if the push rod 7 undergoes slight deformation after long-term use or is misaligned during initial installation, the guide surface 62 can guide it into the correct position, preventing the end from impacting the end face of the annular base 61 and causing jamming or damage.

[0046] The second end face of the annular base 61 (typically the lower end face facing the vial 8) is designed as a flat abutting surface that matches the shape and size of the end of the vial 8 (typically a flat bottom) which the end of the vial 8 will abut against or be very close to when the injection pen is assembled.

[0047] It should be further explained that the second end face cooperates with other structures such as the lower shell 3 to restrict the axial movement of the medicine bottle 8, ensuring that the medicine bottle is fixed in position during transportation and use; at the same time, it transmits force. During the injection process, the push rod 7 pushes the medicine bottle stopper, and the reaction force of the medicine bottle body will be transmitted through the bottom of the bottle to the contact surface of the annular base 61, making the force flow transmission path more direct and stable.

[0048] A weight-reducing hollow portion 64 is formed between the adjacent connecting ear 63 and the side wall of the annular base 61. The weight-reducing hollow portion 64 is a naturally formed hollow area between the adjacent connecting ear 63 and the side wall of the annular base 61, which is used to reduce weight, that is, to reduce unnecessary material use and make the product lighter overall.

[0049] A deformation groove 631 is provided near the annular base 61 of the connecting ear 63; the connecting ear 63 includes two bent parts 632, which form a multi-segment broken-line cross section of the connecting ear 63, and the bent parts are suitable for counteracting the recoil force of the medicine bottle 8.

[0050] The deformation groove 631 is a structural through hole machined on the connecting ear 63, located at the root region where the connecting ear 63 connects to the annular base 61. This through hole artificially creates a structural "weak point" by locally reducing the cross-sectional area of ​​the material. When the connecting ear 63 is subjected to external force (such as the recoil force of the medicine bottle 8), the stress will be concentrated at the preset position of the deformation groove 631, ensuring that deformation occurs at this point. This protects the other parts of the connecting ear 63 and its connection points with the annular base 61 and the upper shell 2 from uncontrollable plastic deformation or breakage, just like a "fuse" for an electrical circuit.

[0051] Specifically, at the moment of injection, the vial 8 generates a reverse impact force (recoil). The deformation groove 631 allows the connecting ear 63 to undergo a small, controllable elastic bending at this point. This bending process can effectively absorb and dissipate a portion of the impact energy, playing a buffering role. By guiding and releasing stress, stress concentration in other unintended areas is avoided, thereby improving the fatigue life of the positioning bracket 6 as a whole under repeated impacts and preventing it from failing due to brittle fracture.

[0052] The multi-segmented zigzag connecting lug 63, composed of the bending portion 632, achieves an excellent balance between axial stiffness (resistance to compression / tension along the direction of the push rod body 7) and radial stiffness (resistance to bending). The zigzag structure can be very rigid in the axial direction to maintain stability, but in a specific direction (such as when subjected to recoil force), it can flexibly absorb energy through the small deformation of the bending portion.

[0053] When the recoil force of the medicine bottle 8 is transmitted to the contact surface of the annular base 61, the force is transmitted to the upper shell 2 through the connecting ear 63. Under the action of this impact force, the multi-segment zigzag structure can generate a much larger recoverable deformation than the straight plate structure through the elastic extension and bending of the bending part, thereby more effectively buffering and absorbing this instantaneous impact energy and greatly offsetting the impact of the recoil force on the overall structure.

[0054] Although the connecting ear 63 is designed for cushioning, its multi-segment zigzag structure still provides sufficient rigidity under normal conditions to ensure that the annular base 61 and the push rod 7 maintain extremely high concentricity and stability in the non-injection state and the pre-injection preparation state, without affecting its core guiding function.

[0055] It should be further explained that by effectively buffering the recoil, the high-frequency vibration caused by the impact and the resulting "click" or metallic impact sound are also reduced, thus improving the product's quality and user experience.

[0056] One end of the upper housing 2 is provided with a plug-in part 21, the outer diameter of which is smaller than the outer diameter of the upper housing 2. The outer diameter of one end of the upper housing 2 is deliberately designed to be smaller, forming a stepped plug-in part 21. The size of this plug-in part 21 is adapted to the inner diameter of the end of the lower housing 3, so as to ensure that the lower housing 3 and the upper housing 2 can be quickly and accurately aligned with the central axis when assembled, and to ensure the concentricity of the medicine bottle 8 and the push rod body 7. This provides a clear assembly benchmark, and the operator can easily plug the two parts into place, improving assembly efficiency and consistency.

[0057] Some embodiments provide an injection pen, including: a rear cover 1, with an actuation spring 5 sleeved at its center; an upper housing 2, which is inserted into the rear cover 1 and has a positioning bracket 6 disposed inside; a lower housing 3, which is inserted into the other end of the upper housing 2, with a cap 4 inserted into the end of the lower housing 3 away from the upper housing 2; and a push rod 7, which is disposed in the positioning bracket 6, with one end of the push rod 7 abutting against the actuation spring 5 and the other end provided with a guide rod 71 adapted to abut against a medicine bottle 8.

[0058] The push rod 7 is the power actuator of the injection pen; its pre-compressed excitation spring 5 stores energy, and when the user triggers the injection mechanism (such as pressing a button), the spring 5 releases the energy, pushing the push rod 7 to move at high speed along the axis.

[0059] The push rod 7 provides injection power, converting the potential energy of the spring into kinetic energy to provide the necessary force for pushing the drug solution; and ensures injection speed. The spring drive can provide an instantaneous and fast enough injection speed to reduce the time the needle stays under the skin and the patient's pain.

[0060] The positioning bracket 6 includes: an annular base 61, which is concentrically arranged inside the upper housing 2. The annular base 61 is adapted to be sleeved on the outside of the push rod body 7, and its inner diameter is matched with the outer diameter of the push rod body 7. Several connecting ears 63, one end of which is integrally connected to the annular base 61 and the other end is connected to the inner wall of the upper housing 2; wherein, when the push rod body 7 is configured to move along the axis of the upper housing 2, the annular base 61 is adapted to constrain the radial movement of the push rod body 7.

[0061] The first end face of the annular base 61 is provided with a guide surface 62, which is an arc-shaped surface or a chamfered surface.

[0062] The second end face of the annular base 61 is an abutment surface, which is adapted to fit the end of the vial 8 of the injection pen.

[0063] The user stores energy by rotating or pressing the spring 5 on the back cover 1, which then releases the energy and pushes the push rod 7 to move at high speed along the axis. During the entire movement, the push rod 7 is precisely constrained by the annular base 61 of the positioning bracket 6, ensuring that it does not move radially or swing, and can only move in a straight line. The guide rod 71 at the end of the push rod 7 accurately strikes the rubber stopper of the medicine bottle 8, pushing the medicine out through the needle to complete the injection.

[0064] 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.

[0065] 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.

[0066] 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 syringe upper barrel characterized by comprising: include: Upper shell (2); Positioning bracket (6) is located inside the upper housing (2); The positioning bracket (6) includes: An annular base (61) is concentrically arranged inside the upper housing (2). The annular base (61) is adapted to be sleeved on the outside of the plunger body (7) of the injection pen, and its inner diameter is matched with the outer diameter of the plunger body (7). Several connecting ears (63) are integrally connected at one end to the annular base (61) and at the other end to the inner wall of the upper shell (2); When the push rod (7) is configured to move along the axis of the upper housing (2), the annular base (61) is adapted to constrain the radial movement of the push rod (7).

2. The upper pen body as described in claim 1, characterized in that, The first end face of the annular base (61) is provided with a guide surface (62), which is an arc-shaped surface or a chamfered surface.

3. The upper pen body as described in claim 2, characterized in that, The second end face of the annular base (61) is an abutment surface, which is adapted to fit the end of the vial (8) of the injection pen.

4. The upper pen body as described in claim 3, characterized in that, A weight-reducing hollow section (64) is formed between the adjacent connecting ear (63) and the side wall of the annular base (61).

5. The upper barrel of claim 4, wherein, The connecting ear (63) is provided with a deformation groove (631) near the annular base (61).

6. The upper barrel of claim 5, wherein, The connecting ear (63) includes two bends (632), which together form a multi-segmented zigzag cross section. The bends are adapted to counteract the recoil of the medicine bottle (8).

7. The upper pen body as described in any one of claims 1-6, characterized in that, One end of the upper housing (2) is provided with a plug-in part (21), the outer diameter of which is smaller than the outer diameter of the upper housing (2), and the positioning bracket (6) is located inside the plug-in part (21).

8. An injection pen characterized in that include: The rear cover (1) has a spring (5) fitted at its center. The upper housing (2) is inserted into the rear cover (1), and a positioning bracket (6) is provided inside it. The lower housing (3) is inserted into the other end of the upper housing (2), and a cap (4) is inserted into the end of the lower housing (3) away from the upper housing (2). The push rod (7) is set inside the positioning bracket (6). One end of the push rod (7) abuts against the excitation spring (5), and the other end is provided with a guide rod (71) suitable for abutting against the medicine bottle (8).

9. The injection pen as described in claim 8, characterized in that, The positioning bracket (6) includes: An annular base (61) is concentrically arranged inside the upper shell (2). The annular base (61) is adapted to be sleeved on the outside of the push rod body (7), and its inner diameter is matched with the outer diameter of the push rod body (7). Several connecting ears (63) are integrally connected at one end to the annular base (61) and at the other end to the inner wall of the upper shell (2); When the push rod (7) is configured to move along the axis of the upper housing (2), the annular base (61) is adapted to constrain the radial movement of the push rod (7).

10. The injection pen as described in claim 9, characterized in that, The first end face of the annular base (61) is provided with a guide surface (62), which is an arc-shaped surface or a chamfered surface; The second end face of the annular base (61) is an abutment face, which is adapted to fit with the end of the cartridge (8) of the injection pen.

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