Injection pen

Abstract

The application relates to an injection pen. The injection pen comprises an injection needle, an injection pen barrel having a medicine cavity in a first direction for accommodating a medicine to be injected, a needle seat having a front end for mounting the injection needle and a rear end connected with the injection pen barrel, the injection needle being mounted on the front end of the needle seat and extending forward, a pen cap configured to be sleeved on the front end of the needle seat to seal the injection needle and the front end of the needle seat, the pen cap being deformed and wrapped when being sleeved on the needle seat, and with the increase of the sleeving depth, the pen cap continuously increases the sleeving stroke in the axial direction, the outer wall of the needle seat continuously forms a radial expansion stress on the inner wall of the pen cap, the pen cap is continuously deformed to compensate, the pen cap further wraps the needle seat, and the sealing performance is improved. The technical scheme of the application can obtain a good sealing effect.

Description

Technical Field

[0001] This application relates to the field of medical devices, and in particular to an injection pen. Background Technology

[0002] Injection pens, as medical devices used for subcutaneous injection of quantitative drugs, are widely used in the long-term treatment of chronic diseases such as diabetes, obesity, and breast cancer. With the increasing prevalence of biologics in clinical treatment, higher requirements are placed on the sealing performance of injection devices during storage and use.

[0003] However, existing injection pen sealing solutions suffer from technical problems such as insufficient sealing reliability or high manufacturing costs, making it difficult to fully meet the requirements for long-term stable drug storage.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] In view of this, this application provides an injection pen to solve at least one problem existing in the prior art.

[0006] To achieve the above objectives, the technical solution of this application is implemented as follows: This application provides an injection pen, comprising: Injection needle; The syringe holder has a cavity in a first direction for containing the drug to be injected; The needle hub has a front end for mounting the injection needle and a rear end for connecting to the injection pen barrel; the injection needle is mounted on the front end of the needle hub and extends forward; The pen cap is configured to be fitted onto the front end of the needle hub to seal the injection needle and the front end of the needle hub. When the pen cap is fitted onto the needle hub, it deforms and wraps around the needle hub. As the insertion depth increases, the pen cap continuously deepens the fitting stroke along the axial direction. The outer wall of the needle hub continuously forms radial expansion stress on the inner wall of the pen cap, driving the pen cap to produce continuous deformation compensation, so that the pen cap further wraps around the needle hub, thereby improving the sealing performance.

[0007] In one optional embodiment, the depth of the pen cap cavity is set such that after the pen cap is inserted into the needle seat to a preset position, the tip of the injection needle at least partially penetrates the bottom wall of the pen cap, thereby squeezing the pen cap and further improving the sealing performance.

[0008] In one alternative embodiment, the pen cap is made of an elastic material, or the pen cap includes an outer shell and a sealing liner, the sealing liner being made of an elastic material; The elastic material is one of silicone, thermoplastic elastomer, or rubber.

[0009] In one alternative embodiment, the interference fit between the pen cap and the needle seat is between 0.03 mm and 0.5 mm.

[0010] In an optional embodiment, the inner wall of the pen cap or the outer wall of the needle holder is provided with at least one annular rib to form a local stress concentration area when the needle holder is fitted, thereby enhancing the sealing and fitting force.

[0011] In an optional embodiment, the outer peripheral surface of the needle holder is provided with a positioning step or a tapered guide section for guiding the pen cap into place and restricting its axial displacement.

[0012] In one alternative embodiment, after the pen cap is fitted onto the needle seat, its free end face is flush with or recessed by no more than 2.0 mm from the front end face of the needle seat to reduce the risk of snagging.

[0013] In one alternative embodiment, at least one inwardly protruding sealing ring is provided on the inner wall of the rear end of the injection pen body, and the sealing ring forms an interference fit with the outer surface of the push rod passing through the inner hole.

[0014] In one optional embodiment, the cross-sectional shape of the sealing ring is triangular, rectangular, or arc-shaped, wherein the triangular or arc-shaped cross-section forms point contact with the push rod, and the rectangular cross-section forms surface contact with the push rod.

[0015] In one optional embodiment, the number of sealing protrusions is two or more, and they are spaced apart along the axial direction of the injection pen barrel, with the spacing between adjacent sealing protrusions being 1.0 mm to 5.0 mm.

[0016] In one optional embodiment, the injection pen body is provided with a fully enclosed puncture membrane at one end near the push rod. When not in use, the puncture membrane completely seals the inner channel of the injection pen body. When the push rod punctures the puncture membrane, the edge of the puncture forms an interference fit with the outer wall of the push rod due to the elastic recoil of the material, thereby maintaining the sealing after puncture.

[0017] In one alternative embodiment, the puncture membrane has a thickness of 0.05 mm to 1.0 mm and is made of medical-grade polypropylene, cyclic olefin copolymer, or cyclic olefin polymer.

[0018] In one optional embodiment, after the push rod punctures the puncture membrane, the edge of the puncture forms an interference fit of 0.03 mm to 0.50 mm with the outer wall of the push rod.

[0019] In one alternative embodiment, the central region of the puncture membrane is provided with a localized thinning zone or stress concentration point to guide the push rod through the puncture path.

[0020] The injection pen provided in this application includes: an injection needle; an injection pen body having a drug cavity in a first direction for containing an injectable drug; a needle hub having a front end for mounting the injection needle and a rear end connected to the injection pen body; and a pen cap configured to be fitted onto the front end of the needle hub to seal the injection needle and the front end of the needle hub. The pen cap is made of an elastic material, deforms and wraps around the needle hub when fitted, and further compresses the pen cap by the insertion of the injection needle, so that the pen cap tightly wraps around the needle hub, thereby improving the sealing performance. Therefore, the injection pen in this application embodiment has a pen cap configured to deform and wrap around the outer periphery of the needle hub when fitted, and as the insertion depth increases, the tip of the injection needle pierces the bottom wall of the pen cap, compressing the pen cap and further wrapping the needle hub, thereby improving the sealing performance. This ensures a good sealing effect throughout the entire supply chain cycle from the completion of pharmaceutical filling to the first use by the patient, preventing external air, moisture, and microorganisms from entering the drug cavity through the needle hub area.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 A schematic diagram of an injection pen provided in an embodiment of this application; Figure 2 A schematic diagram of the mating relationship between the needle hub and the pen cap in the injection pen provided in this application embodiment. Figure 1 ; Figure 3 A schematic diagram of the mating relationship between the needle hub and the pen cap in the injection pen provided in this application embodiment. Figure 2 ; Figure 4 for Figure 3 A magnified view of a portion of point A in the middle; Figure 5 A schematic diagram of the needle hub in an injection pen provided in an embodiment of this application; Figure 6 A schematic diagram of the injection pen barrel provided in the embodiments of this application. Figure 2 ; Figure 7 for Figure 6 Enlarged view of part B in the middle Figure 1 ; Figure 8for Figure 6 Enlarged view of part B in the middle Figure 2 ; Figure 9 for Figure 6 Enlarged view of part B in the middle Figure 3 ; Figure 10 A schematic diagram illustrating the relationship between the injection pen barrel and the push rod in an injection pen provided in an embodiment of this application; Figure 11 for Figure 10 A magnified view of a portion of point C.

[0023] Explanation of reference numerals in the attached figures: 10. Injection pen body; 11. Syringe; 111. Sealing ring; 112. Puncture membrane; 12. Drug chamber; 13. Drug column groove; 21. Button; 22. Push rod; 23. Guide; 31. Needle seat; 311. Annular rib; 312. Positioning step; 32. Injection needle; 40. Pen cap; 50. Sealing area. Detailed Implementation

[0024] To make the technical solutions and beneficial effects of this application more obvious and understandable, the technical solutions in the embodiments of this application are clearly and completely described below by listing specific embodiments. Obviously, the embodiments of this application are not exhaustive, and the described embodiments are only some embodiments of this application, not all embodiments.

[0025] The exemplary embodiments disclosed in this application will now be described in more detail with reference to the accompanying drawings, providing detailed structures and steps to illustrate the technical solution of this application. Note that the drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used herein is for the purpose of describing particular embodiments only and should not be construed as limiting the technical solutions of this application.

[0027] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. To clearly define the inventive concept of this application and avoid confusion with its content, technical features well-known in the art and conventionally understood by those skilled in the art are not elaborated upon. Specifically, this document does not fully list all features of actual embodiments, nor does it provide a detailed description of well-known functions and structures.

[0028] The inventors of this application discovered during research and development that existing injection pens, after being delivered to pharmaceutical companies as semi-components for filling therapeutic drugs, often fail during long-term storage due to inherent defects in the front-end sealing structure. Specifically, the traditional rigid plastic pen cap 40 and needle hub 31 rely only on a gap fit or simple snap-fit ​​connection, failing to form a continuous sealing interface; when the injection needle 32 punctures, the rigid pen cap 40 cannot adapt to deformation, instead creating micron-level gaps around the needle; furthermore, the inner hole of the needle hub 31 often uses a single O-ring or no sealing design, making it prone to drug backflow during the movement of the push rod 22; although some products use a fully enclosed membrane, the puncture site cannot effectively retract after being punctured, resulting in a lack of dynamic sealing. These problems collectively lead to moisture evaporation, oxidative degradation, or microbial contamination of drugs during storage and transportation, seriously affecting drug safety and efficacy. Therefore, through further research and development, the inventors proposed the following technical solution.

[0029] Before introducing the technical solution of this application, let's first introduce the main structure of the existing injection pen. The injection pen is pen-shaped and mainly consists of a needle assembly at the front end, a drug-containing cavity in the middle, and an injection mechanism at the rear end. Figure 1 As shown, the injection pen includes the following main components: The injection pen body 10 includes a syringe 11 and a drug reservoir 12. The drug reservoir 12 is located at the front end of the body, and the side wall of the drug reservoir 12 is transparent to display the remaining amount of drug. Drug column trough 13: Located inside the drug chamber 12, used to hold the drug column to be injected; Button 21: Located at the end of the injection pen, used to drive the push rod 22 to dispense the medicine; Push rod 22: connected to button 21, extends along the first direction into the inside of the injection pen barrel 10, and its front end contacts the drug column to push the drug through the needle seat 31 and injection needle 32 to be discharged; Needle holder 31: has a front end for mounting the injection needle 32 and a rear end connected to the injection pen barrel 10, and forms a seal with the pen cap 40; Pen cap 40: Sleeves over needle hub 31 and the front end of needle hub 31 to protect injection needle 32 and provide external seal; Injection needle 32: detachably mounted on needle hub 31, used to penetrate human tissue to deliver medication; Guide component 23: It is an auxiliary sealing or positioning structure, and is respectively set inside and outside the injection pen barrel 10 to enhance the sealing performance or support the movement of push rod 22.

[0030] To address the current technical problems, this application provides an injection pen. (Reference) Figure 1 and Figure 2 The injection pen includes: Injection needle 32; The injection pen body 10 has a drug cavity in a first direction for containing the drug to be injected; The needle holder 31 has a front end for mounting the injection needle 32 and a rear end connected to the injection pen barrel 10; the injection needle 32 is mounted on the front end of the needle holder 31 and extends forward. The pen cap 40 is configured to be sleeved on the front end of the needle seat 31 to seal the injection needle 32 and the front end of the needle seat 31. When the pen cap 40 is sleeved on the needle seat 31, it deforms and wraps around the needle seat 31. As the insertion depth increases, the pen cap continuously deepens the sleeve stroke along the axial direction. The outer wall of the needle seat continuously forms radial expansion stress on the inner wall of the pen cap, driving the pen cap to produce continuous deformation compensation, so that the pen cap 40 further wraps around the needle seat 31, thereby improving the sealing performance.

[0031] Without limitation, the injection needle 32 refers to a slender, hollow tubular component used to pierce subcutaneous tissue to deliver medication, typically made of stainless steel or medical polymer materials, with its tip specially ground to reduce puncture pain. The aforementioned injection pen body 10 is the core container for holding the medication, with its internal medication chamber extending along a first direction, which is typically defined as the axial direction in which the medication is delivered from the rear end to the front end.

[0032] In a non-limiting sense, the needle holder 31 is an intermediate transition component connecting the pen barrel and the injection needle 32. Its front end is responsible for fixing the injection needle 32, and its rear end is responsible for sealing the connection with the pen barrel, playing a structural support role. The aforementioned pen cap 40 is the core improved component of this application. Unlike traditional hard pen caps, it is designed to deform and wrap around the needle holder 31 when it is fitted. As the fitting depth increases, the pen cap continuously deepens the fitting stroke along the axial direction. The outer wall of the needle holder continuously forms radial expansion stress on the inner wall of the pen cap, driving the pen cap to produce continuous deformation compensation, so that the pen cap 40 further wraps around the needle holder 31, thereby improving the sealing performance.

[0033] Specifically, the inner surface of the pen cap 40 can be micro-textured, for example, by setting micron-level anti-slip textures, to further increase the coefficient of friction between the inner wall of the pen cap 40 and the outer wall of the needle seat 31, preventing relative slippage under extreme transportation conditions, thereby ensuring continuous sealing pressure.

[0034] For a clearer understanding, please refer to the following: Figure 2 This section briefly introduces the sealing requirements of injection pens. Figure 2The entire sealing area 50 of the injection pen tip, i.e., surrounding the injection needle 32, is marked by a dashed line. The sealing structure of this embodiment is mainly set at sealing positions 1 and 2, namely the seal between the inner wall of the pen cap 40 and the outer wall of the needle seat 31, and the seal between the inner wall of the pen cap 40 and the tip of the injection needle 32. Similarly, in other figures, the approximate sealing areas and positions will be marked with dashed or dotted lines as appropriate, without individually labeling them with serial numbers.

[0035] In this embodiment of the injection pen, the pen cap 40 is configured to deform and wrap around the outer periphery of the needle seat 31 when it is fitted into the needle seat 31. As the insertion depth increases, the tip of the injection needle 32 pierces the bottom wall of the pen cap 40, squeezing the pen cap 40 and causing it to further wrap around the needle seat 31, thereby improving the sealing performance. This ensures a good sealing effect throughout the entire supply chain cycle from the completion of pharmaceutical filling to the patient's first use, thus preventing external air, moisture, and microorganisms from entering the drug cavity through the needle seat area.

[0036] In some other embodiments of this application, the depth of the inner cavity of the pen cap 40 is set such that after the pen cap is fitted into the needle seat 31 to a preset position, the tip of the injection needle 32 at least partially penetrates the bottom wall of the pen cap 40, thereby squeezing the pen cap 40 to further improve the sealing performance.

[0037] In this application, the injection needle 32 not only serves as a drug delivery channel but also as a key medium for triggering the secondary deformation of the pen cap 40. That is, when the needle tip pierces the interior of the pen cap 40, it undergoes greater deformation due to compression, thereby improving the sealing performance.

[0038] In other embodiments of this application, the pen cap 40 is made of an elastic material, or the pen cap 40 includes a shell and a sealing liner, the sealing liner being made of an elastic material; The elastic material can be one of silicone, thermoplastic elastomer, or rubber.

[0039] In a non-limiting sense, elastic materials refer to polymeric materials that can undergo significant deformation under external force and quickly return to their original shape after the force is removed. Silicone, in particular, possesses excellent high and low temperature resistance and biocompatibility, making it suitable for applications requiring high-temperature sterilization; specifically, it can be medical-grade silicone. Thermoplastic elastomers (TPEs) combine the elasticity of rubber with the processing ease of plastics, making them suitable for large-scale injection molding production. Rubber, on the other hand, exhibits extremely high wear resistance and durable sealing. In this application, the above materials were selected to ensure that the pen cap 40 does not age or harden during a storage period of several years, maintaining sufficient resilience to preserve the adhesion of the sealing interface. All these materials meet the biological evaluation standards for medical devices and will not chemically react with drugs or release harmful substances.

[0040] Furthermore, an appropriate amount of antibacterial agent or antioxidant can be added to the elastic material to give the pen cap 40 a certain antibacterial function, build a second biological barrier, and further reduce the risk of microorganisms penetrating through the pen cap 40 material itself.

[0041] In some other embodiments of this application, the interference fit between the pen cap 40 and the needle holder 31 can be 0.03 mm to 0.5 mm.

[0042] In a non-restrictive sense, interference fit refers to the numerical difference between the inner diameter of the pen cap 40 and the outer diameter of the needle holder 31 in the unloaded state. This difference is converted into radial clamping force after the two are assembled. The range of 0.03 mm to 0.5 mm is the optimal range verified by extensive experiments: if the interference fit is less than 0.03 mm, sufficient initial contact pressure may not be generated to resist the internal chemical vapor pressure; if the interference fit is greater than 0.5 mm, it will lead to excessive assembly resistance, increase the difficulty of production line operation, and may even cause the pen cap 40 to tear or the needle holder 31 to deform. This interference fit design ensures reliable airtight sealing through material elasticity alone, without the need for an additional locking mechanism.

[0043] Specifically, the interference fit can also be designed as a gradient distribution, that is, the interference fit at the front end of the pen cap 40 is slightly larger than that at the rear end, in order to adapt to the stress concentration requirements when the injection needle 32 is inserted, so that the sealing force is strengthened in the key area.

[0044] In other embodiments of this application, reference is made to Figure 3 and Figure 4 The inner wall of the pen cap 40 or the outer wall of the needle seat 31 is provided with at least one annular rib 311, which is used to form a local stress concentration area when the needle seat 31 is fitted, thereby enhancing the sealing and fitting force.

[0045] In a general sense, the annular rib 311 refers to a protruding structure extending circumferentially along the inner wall of the pen cap 40. When the pen cap 40 is fitted into the needle seat 31, the annular rib 311 forms line contact or narrow surface contact on the mating surface, thereby generating local stress at the contact area that is much higher than the average level. This stress concentration effect can force the elastic material to fill deeper into the microscopic unevenness of the needle seat 31 surface, and even fill in machining defects that are not visible to the naked eye, thereby significantly improving the tightness of the sealing interface. In addition, the annular structure can also provide a certain limiting effect in the axial direction, preventing the pen cap 40 from easily coming off when subjected to axial tensile force.

[0046] Specifically, in one embodiment, the outer wall of the needle holder 31 is provided with at least one annular rib 311, for reference. Figure 3 and Figure 4 .

[0047] Furthermore, the annular rib 311 can also be designed with a serrated or wavy surface profile in the circumferential direction to increase the tortuosity of the contact interface, extend the possible leakage path of gas or liquid, and further improve the sealing effect.

[0048] In other embodiments of this application, reference is made to Figure 5 The outer circumferential surface of the needle seat 31 is provided with a positioning step 312 or a conical guide section, which is used to guide the pen cap 40 to be fitted and restrict its axial displacement.

[0049] In a non-restrictive sense, the positioning step 312 is a stepped structure that abruptly changes on the outer circumference of the pointer seat 31, and the aforementioned tapered guide section is a sloping structure whose outer diameter at the front end of the pointer seat 31 gradually decreases. The function of the tapered guide section is to provide a smooth guide trajectory during the initial assembly of the pen cap 40, preventing the edge of the pen cap 40 from folding or breaking due to forced compression. The function of the positioning step 312 is to act as an axial stop surface after the pen cap 40 is fitted into place, restricting the pen cap 40 from continuing to move forward or fall back, ensuring that the pen cap 40 is always in the preset optimal sealing position. This structural design simplifies the assembly process and improves production efficiency and product consistency.

[0050] Specifically, the positioning step 312 can also be designed as a snap-fit ​​part with an inverted structure, which cooperates with the corresponding slot on the inner wall of the pen cap 40 to achieve audible clicking feedback, allowing the operator to intuitively confirm that the assembly is in place.

[0051] Specifically, in one embodiment, the outer peripheral surface of the needle holder 31 is provided with a positioning step 312, for reference. Figure 5 .

[0052] In some other embodiments of this application, after the pen cap 40 is fitted onto the needle holder 31, its free end face is flush with or recessed by no more than 2.0 mm from the front end face of the needle holder 31.

[0053] In a general sense, the free end face refers to the open edge of the pen cap 40 away from the pen body, and the front end face of the aforementioned needle seat 31 is the plane at the very front of the needle seat 31. A design that is flush with or recessed by no more than 2.0 mm means that the pen cap 40 will not protrude significantly from the front end of the needle seat 31, thus eliminating the risk of the protruding edge snagging on clothing, gloves, or packaging materials. This low-profile design not only enhances the overall aesthetics of the product but, more importantly, avoids the potential hazard of the pen cap 40 loosening or falling off due to accidental snagging, thereby compromising the sealed environment. This is particularly suitable for scenarios where patients carry the pen with them.

[0054] Specifically, the free end face of the pen cap 40 can also be designed as a rounded transition or a chamfered structure to further eliminate sharp edges and improve the user's grip and operation comfort and safety.

[0055] In other embodiments of this application, reference is made to Figure 6 The inner wall of the rear end of the injection pen barrel 10 is provided with at least one inwardly protruding sealing ring 111, and the sealing ring 111 forms an interference fit with the outer surface of the push rod 22 passing through the inner hole.

[0056] Unrestricted, the sealing ring 111 can be an annular protrusion integrally formed or separately installed on the inner wall of the injection pen barrel 10, with its inner diameter slightly smaller than the outer diameter of the push rod 22. When the push rod 22 slides in the inner hole of the injection pen barrel 10, the sealing ring 111 undergoes elastic deformation and tightly hugs the surface of the push rod 22, forming a dynamic seal. This structure is mainly used to prevent the drug from leaking from the rear end of the inner hole during the reciprocating motion of the push rod 22, and also to prevent external air from entering the drug cavity. The presence of the sealing ring 111 makes the inside of the injection pen barrel 10 an independent sealing unit, which, together with the external pen cap 40 seal, constitutes a multi-layer protection system.

[0057] Furthermore, the surface of the sealing ring 111 can also be coated with a low-friction coefficient lubricating coating, such as silicone oil or polytetrafluoroethylene coating, to reduce the starting force and sliding resistance of the push rod 22 movement while ensuring sealing performance, and improve the smoothness of the injection operation.

[0058] In other embodiments of this application, reference is made to Figures 7-9 The cross-sectional shape of the sealing ring 111 can be triangular, rectangular or arc-shaped.

[0059] In a non-restrictive sense, the triangular, rectangular, or arc-shaped shape refers to the geometric profile of the cross-section of the sealing ring 111. A triangular or arc-shaped cross-section forms an approximate point contact or narrow line contact when in contact with the push rod 22, resulting in a small contact area and therefore lower sliding friction resistance. This is suitable for patients sensitive to the force applied to the push rod 22 or for high-precision drug delivery scenarios. A rectangular cross-section forms a wider surface contact when in contact with the push rod 22, providing a larger contact area and offering greater sealing bandwidth and stronger leak resistance. This is suitable for long-term storage scenarios with extremely high sealing requirements. By selecting different cross-sectional shapes, an optimal balance can be achieved between sealing performance and operational feel.

[0060] Furthermore, the cross-sectional shape of the sealing ring 111 can also be designed as an asymmetrical lip structure. Utilizing the one-way sealing characteristics of the lip, it automatically opens to reduce resistance when the push rod 22 moves forward, and automatically closes to enhance the seal when the push rod 22 stops or moves backward, thereby achieving dynamic seal adjustment.

[0061] In some other embodiments of this application, the number of sealing protrusions 111 may be two or more, and they are spaced apart along the axial direction of the injection pen barrel 10.

[0062] Non-restricted, having two or more rings implies multiple lines of sealing within the inner bore of the syringe barrel 10. When one sealing ring 111 temporarily fails due to wear from prolonged use, foreign matter adhesion, or localized damage, the remaining sealing rings 111 can still maintain basic sealing functionality, preventing significant leakage or contamination of the medication. This redundant design improves the reliability of the syringe under extreme conditions, ensuring safe medication administration to patients in critical situations. The space between adjacent rings also buffers or accommodates minute leaks, preventing direct contact with the external environment.

[0063] Specifically, the multiple sealing rings 111 can also be designed with different hardness or different compression amounts. For example, the front ring is softer to reduce friction, while the rear ring is harder to provide the main sealing force, thus optimizing the overall sealing performance through differentiated design.

[0064] In some other embodiments of this application, the spacing between adjacent sealing protrusions 111 can be 1.0 mm to 5.0 mm.

[0065] In a non-restrictive sense, the spacing refers to the axial distance between the center lines of two adjacent sealing rings 111. A range of 1.0 mm to 5.0 mm ensures that each ring functions independently, avoiding excessive material fatigue due to stress superposition caused by excessive distance, while also ensuring that sufficient sealing units are accommodated within the limited length of the injection pen barrel 10. A reasonable spacing design also helps to form a stable pressure gradient between the rings, further improving the overall sealing efficiency.

[0066] Specifically, the spacing can also be dynamically adjusted according to the movement speed of the push rod 22 or the viscosity of the agent. For example, for high-viscosity agents, the spacing can be appropriately increased to reduce the influence of shear heat on the properties of the agent.

[0067] In other embodiments of this application, reference is made to Figure 10 and Figure 11 The injection pen body 10 has a fully enclosed puncture membrane 112 at one end near the push rod 22. When not in use, the puncture membrane 112 completely seals the inner hole channel of the injection pen body 10. When the push rod 22 punctures the puncture membrane 112, the edge of the puncture forms an interference fit with the outer wall of the push rod 22 due to the elastic recoil of the material, thereby maintaining the sealing after puncture.

[0068] In a non-restrictive sense, the puncture membrane 112 is a thin film structure covering the rear opening of the syringe barrel 10. It remains completely sealed during manufacturing and transportation, completely isolating the inner pore of the syringe barrel 10 from the external environment, forming an absolute airtight barrier to effectively prevent the escape of drug vapors and the reverse infiltration of external microorganisms and dust. When a patient or medical staff pushes the plunger 22 for injection, the sharp tip of the plunger 22 punctures the membrane. Crucially, the material used for the puncture membrane 112 possesses excellent elastic memory properties. After being punctured, the puncture edge does not permanently open but instead contracts inwards due to the material's own elastic recovery force, tightly gripping the outer surface of the plunger 22 to form a new interference fit seal. This mechanism achieves a seamless switch from static absolute sealing to dynamic plunger 22 sealing, making it particularly suitable for semi-finished products that require long-term storage after pharmaceutical filling, ensuring sealing safety throughout the entire lifecycle from production to use.

[0069] In some other embodiments of this application, the thickness of the puncture membrane 112 may be 0.05 mm to 1.0 mm, and it is made of medical-grade polypropylene, cyclic olefin copolymer or cyclic olefin polymer.

[0070] Unrestricted, the thickness range is determined based on the balance between puncture force and sealing performance: a lower limit of 0.05 mm ensures that the push rod 22 can easily puncture with minimal force, avoiding operational difficulties; an upper limit of 1.0 mm ensures that the membrane has sufficient mechanical strength and barrier properties to prevent accidental breakage during transport vibrations. Medical-grade polypropylene offers excellent chemical stability and low cost; cyclic olefin copolymers (COC) and cyclic olefin polymers (COP) possess extremely high transparency, extremely low water vapor permeability, and excellent biocompatibility, making them particularly suitable for moisture-sensitive biological agents. All these materials can be sterilized by gamma rays or ethylene oxide, meeting the hygiene standards for medical devices.

[0071] Furthermore, the puncture membrane 112 can also adopt a multi-layer composite structure, for example, the outer layer is a high-barrier material to prevent water vapor penetration, and the inner layer is a low-friction material to facilitate the insertion and sliding of the push rod 22, thereby further optimizing the overall performance through material composite technology.

[0072] In some other embodiments of this application, when the push rod 22 punctures the puncture membrane 112, the interference fit between the edge of the puncture and the outer wall of the push rod 22 can be 0.03 mm to 0.50 mm.

[0073] In a non-restrictive sense, the interference fit refers to the difference between the inner diameter of the punctured membrane 112 after retraction and the outer diameter of the push rod 22. A range of 0.03 mm to 0.50 mm is sufficient to maintain a continuous radial clamping force during the reciprocating motion of the push rod 22, preventing leakage of the drug along the gap in the push rod 22. At the same time, this fit is not too large, which would generate excessive frictional resistance and affect the accuracy of dosage control. Precise control of this parameter is key to achieving dynamic sealing after puncture.

[0074] Specifically, the interference fit amount can also be designed as a variable that changes with the position of the push rod 22. For example, the fit amount is larger at the beginning position of the push rod 22 to cope with high pressure, and smaller at the end of the stroke of the push rod 22 to reduce resistance, thereby achieving adaptive sealing.

[0075] In some other embodiments of this application, the central region of the puncture membrane 112 is provided with a local thinning area or stress concentration point to guide the push rod 22 through the puncture path.

[0076] In a general sense, a locally thinned area refers to a thin sheet structure where the thickness at the center of the punctured membrane 112 is significantly less than that of the surrounding area. The aforementioned stress concentration points refer to pre-designed indentations, pits, or material weakening points on the membrane surface. These structures artificially create a weak point, ensuring that when the push rod 22 contacts the membrane, it always prioritizes puncturing from the center and expands the tear along a predetermined trajectory. This avoids irregular, skewed, or excessively large tears caused by random punctures, thus preventing sealing failure or debris shedding due to uncontrolled tear shape. The design guiding the puncture path significantly improves the reliability and consistency of product use.

[0077] Furthermore, the local thinning zone can also be designed as a radial microcrack pattern or a cross-shaped line to further control the direction and shape of the crack expansion, ensuring that the crack edge is neat and smooth, which is conducive to elastic retraction and sealing.

[0078] In some other embodiments of this application, the outer surface of the injection pen barrel 10 is provided with a dose display window and a dose adjustment knob, the dose display window being configured to display the currently set drug dose.

[0079] Without limitation, the dosage display window is a transparent area located on the side of the pen body, used to display the value of the internal dosage indicator mechanism; the dosage adjustment knob is a rotating component located at the end of the pen, used to set the dosage of a single injection.

[0080] It should be noted that the various embodiments or implementation methods in this document can be described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to mutually. It should be understood that in the various embodiments of this application, the embodiment numbers are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments.

[0081] Understandably, without conflict, the technical features in the technical solutions described in each embodiment can be arbitrarily combined to form new embodiments. For example, each structure in each embodiment can be implemented as an independent embodiment, and the structures can be arbitrarily combined; some or all of the structures in different embodiments can be arbitrarily combined. Each step in each embodiment can be implemented as an independent embodiment, and the steps can be arbitrarily combined; the order of the steps can be arbitrarily interchanged; some or all of the steps in different embodiments can be arbitrarily combined. Furthermore, regarding the table in the embodiments, each element, each row, or each column in the table can be implemented as an independent embodiment.

[0082] In this document, when the terms "embodiment," "implementation," or "example" are used, it means that the specific features described in connection with these implementations or examples are included in at least one implementation, embodiment, or example of this application. It should be noted that the illustrative expressions of the above terms do not necessarily refer to the same implementation, embodiment, or example. Furthermore, the specific features described, such as structures or steps, can be appropriately combined in any one or more implementations, embodiments, or examples.

[0083] In some embodiments, prefixes such as "first" and "second" are used merely to distinguish different descriptive objects and do not impose restrictions on the position, order, priority, or value of the descriptive objects. The description of the descriptive objects is given in the context of the embodiments, and the use of prefixes does not constitute unnecessary restrictions. For example, the numerical value of a descriptive object is not limited by ordinal numbers and can be one or more. Taking "first device" as an example, the numerical value of "device" can be one or more. Furthermore, objects modified by different prefixes can be the same or different. For example, if the descriptive object is "device," then "first device" and "second device" can be the same device or different devices, and their types can be the same or different. Describing "first" does not necessarily imply the existence of "second," and discussing "second" does not necessarily imply the existence of "first."

[0084] In some embodiments, unless otherwise stated, elements expressed in the singular form, such as “a,” “the,” “the,” “the,” “the,” “the,” etc., can mean “one and only one,” or “one or more,” “at least one,” etc. For example, when using articles such as “a,” “an,” “the,” etc. in translation, the noun following the article can be understood as either a singular or a plural expression. In some embodiments, “multiple” refers to two or more.

[0085] In some embodiments, the terms “at least one of”, “one or more”, “a plurality of”, “multiple”, etc., may be used interchangeably.

[0086] In some embodiments, the notation "at least one of A and B", "A and / or B", "A in one case, B in another", "A in one case, B in another", etc., may include the following technical solutions depending on the situation: in some embodiments, A (A is executed regardless of B); in some embodiments, B (B is executed regardless of A); in some embodiments, execution is selected from A and B (A and B are selectively executed); in some embodiments, both A and B are executed. The same applies when there are more branches such as A, B, C, etc.

[0087] In some embodiments, the notation "A or B" may include the following technical solutions, depending on the situation: in some embodiments, A (execution of A regardless of B); in some embodiments, B (execution of B regardless of A); in some embodiments, selective execution from A and B (A and B are selectively executed). The same applies when there are more branches such as A, B, and C.

[0088] In some embodiments, unless otherwise expressly defined, the terms "installation," "connection," "linking," "fixing," "setting," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment according to the specific circumstances.

[0089] In some embodiments, the terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “height,” “up,” “down,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” and “counterclockwise” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used for the purpose of simplifying the description of this application and do not indicate that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. That is, they should not be construed as limitations on this application.

[0090] In some embodiments, unless otherwise expressly defined, "above" or "below" the second feature can mean that the first and second features are in direct contact, or indirect contact via an intermediate medium, or that they are not in contact, but simply indicate that the horizontal level of the first feature is higher than that of the second feature. Furthermore, "above" or "below" the second feature can mean that the first feature is directly above or diagonally above, directly below, or diagonally below the second feature.

[0091] In some embodiments, spatial relation terms such as “upper” and “lower” may be used for convenience of description to describe the relationship of one element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientation shown in the figures, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figures is flipped, the description of an element or feature “below” other elements or features will change it to “upper” other elements or features. Therefore, the exemplary terms “upper” and “lower” can include both upper and lower orientations. The device may also be otherwise oriented (rotated 90 degrees or otherwise), and the spatial descriptive terms used herein will be interpreted accordingly.

[0092] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations of the technical solutions of this application. Various modifications and changes can be made to the above embodiments without departing from the scope of this application. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of this application that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of this application and do not limit the scope of protection of this patent application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. An injection pen, characterized in that, include: Injection needle (32); The injection pen holder (10) has a drug cavity in a first direction for containing the drug to be injected; The needle hub (31) has a front end for mounting the injection needle (32) and a rear end connected to the injection pen body (10); the injection needle (32) is mounted on the front end of the needle hub (31) and extends forward; The pen cap (40) is configured to be sleeved on the front end of the needle seat (31) to seal the injection needle (32) and the front end of the needle seat (31). When the pen cap (40) is sleeved on the needle seat (31), it deforms and wraps around the needle seat. As the insertion depth increases, the pen cap continuously deepens the sleeve stroke along the axial direction. The outer wall of the needle seat continuously forms radial expansion stress on the inner wall of the pen cap, driving the pen cap to produce continuous deformation compensation, so that the pen cap (40) further wraps around the needle seat (31), thereby improving the sealing performance.

2. The injection pen as described in claim 1, characterized in that, The depth of the inner cavity of the pen cap (40) is set such that after the pen cap is inserted into the needle seat (31) to a preset position, the tip of the injection needle (32) is at least partially inserted into the bottom wall of the pen cap (40), thereby squeezing the pen cap (40) to further improve the sealing performance.

3. The injection pen as described in claim 1, characterized in that, The pen cap (40) is made of an elastic material, or the pen cap (40) includes an outer shell and a sealing liner, the sealing liner being made of an elastic material; the elastic material is one of silicone, thermoplastic elastomer, or rubber.

4. The injection pen as described in claim 1, characterized in that, The interference fit between the pen cap (40) and the needle holder (31) is between 0.03 mm and 0.5 mm.

5. The injection pen as described in claim 1, characterized in that, The inner wall of the pen cap (40) or the outer wall of the needle seat (31) is provided with at least one annular rib (311) to form a local stress concentration area when the needle seat (31) is fitted, thereby enhancing the sealing and fitting force.

6. The injection pen as described in claim 1, characterized in that, The outer circumferential surface of the needle holder (31) is provided with a positioning step (312) or a conical guide section, which is used to guide the pen cap (40) to be fitted and restrict its axial displacement.

7. The injection pen as described in claim 1, characterized in that, After the pen cap (40) is fitted onto the needle seat (31), its free end face is flush with or recessed by no more than 2.0 mm from the front end face of the needle seat (31) to reduce the risk of snagging.

8. The injection pen according to any one of claims 1 to 7, characterized in that, At least one inwardly protruding sealing ring (111) is provided on the inner wall of the rear end of the injection pen barrel (10), and the sealing ring (111) forms an interference fit with the outer surface of the push rod (22) passing through the inner hole.

9. The injection pen as described in claim 8, characterized in that, The sealing ring (111) has a triangular, rectangular or circular arc cross-section, wherein the triangular or circular arc cross-section forms a point contact with the push rod (22), and the rectangular cross-section forms a surface contact with the push rod (22).

10. The injection pen as described in claim 8, characterized in that, The number of sealing protrusions (111) is two or more, and they are spaced apart along the axial direction of the injection pen body (10). The distance between adjacent sealing protrusions (111) is 1.0 mm to 5.0 mm.

11. The injection pen according to any one of claims 1 to 7, characterized in that, The injection pen body (10) has a fully enclosed puncture membrane (112) at one end near the push rod (22). When not in use, the puncture membrane (112) completely seals the inner channel of the injection pen body (10). When the push rod (22) punctures the puncture membrane (112), the edge of the puncture forms an interference fit with the outer wall of the push rod (22) due to the elastic recoil of the material, thereby maintaining the sealing after puncture.

12. The injection pen as described in claim 11, characterized in that, The puncture membrane (112) has a thickness of 0.05 mm to 1.0 mm and is made of medical-grade polypropylene, cyclic olefin copolymer or cyclic olefin polymer.

13. The injection pen as described in claim 11, characterized in that, When the push rod (22) punctures the puncture membrane (112), the edge of the puncture forms an interference fit of 0.03 mm to 0.50 mm with the outer wall of the push rod (22).

14. The injection pen as described in claim 11, characterized in that, The central area of ​​the puncture membrane (112) is provided with a local thinning zone or stress concentration point to guide the push rod (22) through the puncture path.

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