A reusable auto-injector

Abstract

The present application relates to a kind of reusable automatic injector, belong to the technical field of medicine injector.The present application provides a kind of reusable automatic injector, including: pen body, pen core frame, clutch lever, injection button, small push rod and torsion spring;Injection structure, including injection tooth and clutch tooth, when pen core frame is connected to pen body, injection tooth and clutch tooth are combined, by pressing injection button to make clutch lever descend, clutch lever lower section is engaged with injection tooth, clutch lever rotates under the torsion of torsion spring and drives injection tooth and clutch tooth synchronous rotation, clutch tooth drives small push rod to rotate downward to push rubber plug to reach injection purpose, when pen core frame is separated from pen body, clutch tooth moves downward and separates from injection tooth.The present application realizes that torsion spring of automatic injector drives injection and reliable reuse, by pressing button to make clutch lever and injection tooth combine to realize that torsion spring drives injection.

Description

Technical Field

[0001] This invention relates to a reusable automatic injector, belonging to the field of drug injector technology. Background Technology

[0002] In the field of medical devices, autoinjectors, with their ease of operation, high injection efficiency, and precise dosage, have become core devices for clinical treatment and daily self-administration of patients with diabetes, cardiovascular diseases, and autoimmune diseases. They are widely used in the precise delivery of various drugs such as insulin, vaccines, and anticoagulants. The core structure of existing autoinjectors typically includes a drive mechanism, injection needle, reservoir, delivery component, dosage adjustment components (such as adjustment knobs, transmission screws, and memory devices), and safety protection components. Their design logic revolves around the basic injection function, but in practical applications, they have revealed many key structural defects that seriously affect reliability, economy, and accuracy: 1. Lack of a practical reusable mechanism: Current mainstream autoinjectors generally adopt a disposable design, with the drive mechanism, pre-filled syringe, and safety protection components integrated into a non-separable shell. This integrated shell, with its single-use connection, is difficult to disassemble, fundamentally limiting the reusability of the device. Even designs that mention a detachable structure have failed to achieve practicality due to complex repositioning operations and poor compatibility. This design prevents the device from being reused multiple times, resulting not only in high medical costs and resource waste but also failing to meet the practical needs of multi-dose injections and resource-scarce scenarios. 2. Lack of Dosage Adjustment Feedback and Positioning Function: Traditional autoinjectors are mostly designed for fixed-dose injection. Even those few with dosage adjustment functions have significant drawbacks: First, they lack intuitive prompts for the adjusted and injected doses, making it impossible for users to accurately know the current adjusted dose and the actual injected dose. Users can only rely on experience to estimate, easily leading to dosage errors. Second, there are no clear maximum dose positioning indicators or limit prompts, potentially causing users to over-adjust beyond the safe range or fail to reach the required maximum therapeutic dose due to concerns about overdose. Third, there is no clear feedback on the extreme dose; only mechanical limiters provide rigid obstruction. Users can only perceive increased resistance and cannot confirm whether the limit has been reached visually or tactilely, easily causing component wear, jamming, or dosing errors. 3. Lack of Convenient Dosage Correction Mechanism: Traditional dosage adjustment structures are mostly designed for unidirectional dose increases, with the adjustment mechanism closed and internal, lacking external bidirectional adjustment feedback. When a user accidentally sets an excessive dose, there is no clear prompt during the correction process, making it difficult to accurately return to the required dose. Repeated attempts are necessary, making operation cumbersome and prone to insufficient dose or incomplete correction, seriously affecting drug administration safety and ease of operation. 4. Lock-up of the memory element and the small screw: In quantitative syringes with memory elements, the memory element and the small screw achieve precise dosage control through threaded engagement. However, the engagement point is prone to lock-up, a common problem in the industry. This issue stems from manufacturing deviations (insufficient thread precision, dimensional errors, etc.), improper assembly operations (poor coaxiality control), and environmental and usage factors (temperature and humidity deformation, excessive operating force), leading to localized stress concentration, plastic deformation, or a surge in friction on the thread, ultimately causing jamming.Current technologies rely solely on passive control measures such as optimizing processing precision and standardizing assembly processes, which have limited effectiveness and increase production costs. No solution has yet emerged that fundamentally addresses this issue at the structural design level. Locking directly leads to the failure of the dosage preset function, affecting medication adherence and even delaying treatment. These shortcomings mean that existing autoinjectors fail to meet clinical needs and user expectations in terms of reusability, dosage adjustment accuracy, ease of operation, and reliability. Therefore, developing an autoinjector structure that can solve these problems has significant clinical application value and market potential. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a reusable automatic injector, comprising: a pen body, a pen refill holder, a clutch lever, an injection button, a small push rod, and a torsion spring; an injection structure including injection teeth and clutch teeth, wherein the clutch teeth are in transmission engagement with the small push rod, and the injection teeth and clutch teeth are detachably connected and engaged via a ratchet structure; when the pen refill holder is connected to the pen body, the injection teeth and clutch teeth engage; pressing the injection button causes the clutch lever to move downward, and the lower section of the clutch lever engages with the injection teeth; the clutch lever rotates under the torque of the torsion spring, causing the injection teeth and clutch teeth to rotate synchronously; the clutch teeth cause the small push rod to rotate downward to push the rubber stopper to achieve the injection purpose; when the pen refill holder is separated from the pen body, the clutch teeth move downward and separate from the injection teeth; the clutch teeth can rotate freely relative to the injection teeth, at which point they can push the small push rod to rotate and move towards the injection button, thereby achieving the reset of the small push rod.

[0004] In some embodiments of the present invention, the auto-injector further includes a fixed chamber, the refill holder is connected to the pen body through the fixed chamber, the injection teeth and the clutch teeth are both assembled in the fixed chamber, a clutch bracket is provided at the lower part of the fixed chamber, a clutch spring is provided between the clutch bracket and the fixed chamber, the refill holder is detachably connected to the lower part of the fixed chamber and can cooperate with the clutch bracket; the fixed chamber is fixedly connected to the pen body; when the refill holder is separated from the fixed chamber, the clutch bracket moves downward under the action of the clutch spring, and when the clutch bracket moves downward, it drives the clutch teeth to move downward and separate from the injection teeth.

[0005] In some embodiments of the present invention, the auto-injector further includes a dose adjustment structure, which includes a knob, a jumping tooth, a meshing tooth, a bushing cover, a spring tooth, and a release spring. The meshing tooth has a lower meshing tooth and an upper meshing tooth. The lower meshing tooth engages with the spring tooth, and the upper meshing tooth engages with the jumping tooth. When the knob is rotated counterclockwise, the knob engages with the jumping tooth and drives the jumping tooth to rotate synchronously. The jumping tooth simultaneously drives the meshing tooth and the clutch lever to rotate synchronously for dose adjustment. The spring tooth is disposed on the inner circumference of the bushing cover. After each rotation of the meshing tooth by one scale unit, it re-engages with the spring tooth and makes a clicking sound.

[0006] In some embodiments of the present invention, the auto-injector further includes a graduated cylinder, with a limiting element disposed below the graduated cylinder to limit the maximum stroke of the graduated cylinder's downward rotation.

[0007] In some embodiments of the present invention, the bottom of the jumping tooth includes a primary tooth root shaft and a secondary tooth root shaft. The primary tooth root shaft is provided with a primary jumping lower tooth that meshes with the meshing upper tooth of the meshing tooth. The secondary tooth root shaft is provided with a secondary jumping lower tooth that meshes with the knob inner ratchet provided inside the knob. The inner circumference of the jumping tooth is also provided with a jumping inner ratchet. The jumping inner ratchet meshes with the clutch rod ratchet of the upper section of the clutch rod for transmission. By axial pressing, the clutch rod ratchet can be disengaged from the jumping inner ratchet.

[0008] In some embodiments of the present invention, the inner wall of the knob is connected to an inner ring platform via an inner knob bracket. The inner ratchet of the knob is disposed on the inner ring platform. The engagement height between the secondary lower jumping tooth and the inner ratchet of the knob is greater than the engagement height between the upper meshing tooth and the primary lower jumping tooth. There is a back-off gap between the inner ring platform of the knob and the jumping tooth in the clockwise rotation direction. When the dosage is adjusted, the knob is rotated clockwise, and the inner ratchet of the knob pushes the secondary lower jumping tooth upward, thereby disengaging the upper meshing tooth from the primary lower jumping tooth. When the jumping tooth rotates in the opposite direction under the action of the torsion spring to the next meshing tooth position with the meshing tooth, the jumping tooth re-engages with the meshing tooth due to the downward force given by the release spring and emits a meshing sound.

[0009] In some embodiments of the present invention, the lower section of the clutch is provided with a clutch rod limiting groove, and the clutch rod limiting groove cooperates with the scale cylinder limiting boss on the inner wall of the scale cylinder for transmission; the outer wall of the scale cylinder is provided with multiple turns of scale thread and forms a cooperation with the inner wall thread of the bushing of the automatic injector; when the clutch rod drives the scale cylinder to rotate, the scale cylinder will rotate downward relative to the bushing.

[0010] In some embodiments of the present invention, the upper outer periphery of the injection tooth is provided with an upper engagement tooth capable of engaging with the lower end of the clutch lever, the outer periphery of the clutch tooth is provided with a clutch ratchet, the lower inner periphery of the injection tooth is provided with a lower ratchet that engages with the clutch ratchet, and at least one injection tooth spring arm is arranged around the lower outer periphery of the injection tooth. The injection tooth spring arm engages with the upper ratchet of the fixed chamber provided on the inner periphery of the fixed upper section. When the injection tooth rotates, the injection tooth spring arm and the upper ratchet of the fixed chamber bounce radially and emit a bouncing sound to indicate to the user that an injection is being performed.

[0011] In some embodiments of the present invention, the lower section of the fixed chamber has a nested double-layer structure formed by a fixed inner tube and a fixed outer tube. A clutch spring is sleeved between the fixed inner tube and the fixed outer tube. The lower section of the fixed inner tube is provided with a thread that engages with the thread of the small push rod. A clutch engagement boss is provided on the inner circumference of the clutch teeth. The clutch engagement boss engages with the screw limiting recess provided on the outer circumference of the small push rod.

[0012] In some embodiments of the present invention, the auto-injector further includes a memory element, which is movably fitted inside the clutch rod via a sliding groove structure. The memory element is threadedly fitted with the small push rod. There is an adjustment gap at the fit between the injection tooth and the fixed chamber. A memory spring is provided inside the injection tooth. When the memory element abuts against the injection tooth, the memory spring and the adjustment gap cause the injection tooth to move downward.

[0013] In some embodiments of the present invention, the clutch lever has an outer rod ring and an inner rod ring disposed on the outer rod ring, the small push rod is disposed in a cavity within the inner rod ring, and the torsion spring is disposed in the gap space between the outer rod ring and the inner rod ring.

[0014] Advantages and effects of the invention: The invention enables reliable reusability of the automatic injector. Through the detachable connection design between the cartridge holder and the fixed chamber, when the cartridge holder is removed, the clutch bracket, under the action of the clutch spring, drives the clutch teeth to separate from the injection teeth, and the small push rod can be smoothly pushed back to the 0 position to complete the reset. When the cartridge holder is installed, it can drive the clutch teeth to re-engage with the injection teeth and compress the clutch spring, so that the injector can be used multiple times, effectively reducing medical costs, reducing resource waste, and meeting the practical needs of multi-dose injection and resource-scarce scenarios.

[0015] This invention optimizes the intuitiveness and precision of dosage adjustment. During dosage adjustment, the meshing teeth engage with the spring teeth and make a clicking sound every time they rotate one scale unit. Combined with the scale markings on the scale cylinder, users can clearly know the current dosage adjustment. The limiting component limits the maximum stroke of the scale cylinder through the collision point structure, clearly defining the maximum dosage position and avoiding over-adjustment or failure to reach the required treatment dose. At the same time, the radial movement and sound design of the injection tooth spring arm and the ratchet on the fixed chamber during injection can provide real-time indication of the injection status, improving the safety and reliability of use.

[0016] This invention achieves a convenient and accurate dose reversal function. When the knob is rotated clockwise, the reversal gap between the inner ring of the knob and the jumping tooth can be used to lift the jumping tooth upward and disengage it from the meshing tooth. Under the action of the torsion spring, the jumping tooth rotates in the opposite direction to the next meshing tooth position. The target dose can be accurately reversed without repeated attempts, avoiding the problem of insufficient dose due to excessive reversal or overdose due to incomplete reversal. This significantly improves the convenience of operation and the accuracy of drug administration.

[0017] This invention effectively avoids the risk of locking between the memory element and the push rod. By setting an adjustment gap between the injection tooth and the fixed chamber, and with the support of the memory spring for the injection tooth, when the memory element is stuck by the injection tooth during the reset process, the injection tooth can be lowered to avoid it, reducing stress concentration at the thread engagement part of the memory element and the push rod, avoiding plastic deformation or jamming of the thread profile, fundamentally solving the locking problem from the structural design level, improving the reliability of the syringe, and at the same time, it does not require high-precision machining or complex assembly processes, reducing production costs and ensuring patient medication adherence.

[0018] This invention simplifies the operation process and improves safety. During injection, simply pressing the injection button drives the clutch lever to move the injection teeth, clutch teeth, and small push rod together to achieve injection. The overall structure has stable transmission. The ratchet engagement and spring reset design of each component ensures controllable stroke and clear feedback during operation, which reduces the difficulty of operation and human error, making it suitable for the daily self-medication needs of people with chronic diseases. Attached Figure Description

[0019] Figure 1 A schematic diagram of the overall structure for use with an auto-injector (with the pen cap on).

[0020] Figure 2 A schematic diagram of the overall structure of an auto-injector in injection mode (with the pen cap removed).

[0021] Figure 3 This is an exploded view of an autoinjector.

[0022] Figure 4 This is an external schematic diagram of the injection structure.

[0023] Figure 5 This is a cross-sectional view of the injection structure.

[0024] Figure 6 This is a sectional view of the lower section of the small push rod's mating structure.

[0025] Figure 7 This is an exploded view of the mating structure of the lower section of the small push rod.

[0026] Figure 8 This is a schematic diagram of the injection tooth structure.

[0027] Figure 9 This is a schematic diagram of the clutch lever.

[0028] Figure 10 This is a structural diagram of the dose-regulating structure.

[0029] Figure 11 An exploded view of the dose-regulating structure.

[0030] Figure 12 This is a schematic diagram of the meshing teeth.

[0031] Figure 13-1 This is a schematic diagram of the upper structure of the jumping tooth.

[0032] Figure 13-2 This is a schematic diagram of the lower structure of the jumping tooth.

[0033] Figure 14 This is a structural schematic diagram of the fixed chamber.

[0034] Figure 15 This is a schematic diagram of the clutch teeth.

[0035] Figure 16 This is a schematic diagram of the memory device.

[0036] Figure 17 This is a schematic diagram of the normal injection state when the pen refill holder is connected.

[0037] Figure 18 This is a diagram showing the injection completion state when the pen refill holder is not connected.

[0038] Figure 19 This is a schematic diagram of the knob.

[0039] In the diagram, 1. graduated cylinder; 2. bushing cover; 3. spring tooth; 4. meshing tooth; 5. clutch lever; 6. ratchet tooth; 7. limit component; 8. knob; 9. bushing; 10. torsion spring; 41. upper meshing tooth; 42. lower meshing tooth; 51. outer rod ring; 52. inner rod ring; 61. first-stage ratchet tooth; 62. second-stage ratchet tooth; 63. ratchet inner ratchet tooth; 11. injection tooth; 12. clutch tooth; 13. fixed chamber; 14. injection button; 5. Gap space; 16. Small push rod; 17. Release spring; 18. Clutch spring; 19. Clutch bracket; 20. Pen refill holder; 21. Rubber stopper; 22. Memory element; 23. Memory spring; 24. Cartridge bottle; 25. Pen body; 26. Viewing window; 27. Pen cap; 111. Engaging tooth on injection tooth; 112. Injection tooth spring arm; 121. Clutch ratchet; 131. Racket on fixing chamber; 221. Limiting protrusion; 81. Internal ratchet of knob. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can 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 invention based on the specific circumstances.

[0042] In this invention, the terms "first" and "second" are used only to distinguish similar components / parts in different positions or with different characteristics, and have no other limiting meaning; "upper" refers to the direction in which each component is away from the ground, and "lower" refers to the direction in which each component is away from the ground.

[0043] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0044] This invention provides a reusable automatic injector, comprising: a pen body 25, a refill holder 20, a clutch lever 5, an injection button 14, a small push rod 16, and a torsion spring 10. The top of the clutch lever 5 is connected to the injection button 14. The injection structure includes an injection tooth 11 and a clutch tooth 12 sequentially disposed at the lower section of the small push rod 16. Both the injection tooth 11 and the clutch tooth 12 are assembled in a fixed chamber 13. The clutch tooth 12 is driven to engage with the small push rod 16. The injection tooth 11 and the clutch tooth 12 are also separably engaged by a ratchet structure. A clutch bracket 19 is disposed at the lower part of the fixed chamber 13. A clutch spring 18 is disposed between the clutch bracket 19 and the fixed chamber 13. The refill holder 20 is detachably connected to the lower part of the fixed chamber 13 and can engage with the clutch bracket 19.

[0045] This autoinjector is designed with "detachable reset and reusable" as its core objective. Through the coordinated operation of the clutch structure and detachable components, it breaks the limitation of traditional autoinjectors that can only be used once, enabling multiple safe injection operations. The separable ratchet engagement structure of the injection teeth 11 and the clutch teeth 12 is the key design for achieving reusability. By switching between their separation and engagement, the injection and reset action cycle is completed. Combined with the elastic reset function of the clutch bracket 19 and the clutch spring 18, the stability and reliability of repeated use are further improved.

[0046] In some embodiments of the present invention, when the pen refill holder 20 is connected to the lower part of the fixing chamber 13, the pen refill holder 20 will simultaneously move the clutch bracket 19 and the clutch tooth 12 upwards. The injection tooth 11 and the clutch tooth 12 will engage through a ratchet structure, and the clutch spring 18 will be compressed. After the pen refill holder 20 is connected and installed, the injection tooth 11 and the clutch tooth 12 will engage, allowing for normal injection. The detachable connection design of the pen refill holder 20 and the linkage mechanism of the clutch bracket 19 constitute the core trigger structure for repeated use: the detachable connection between the pen refill holder 20 and the fixing chamber 13, and the fixed connection between the fixing chamber 13 and the pen body, facilitates quick replacement of the cartridge bottle 24, adapting to the need for repeated consumable replacement. In other embodiments, the pen refill holder can also be detachably connected directly to the pen body. The upward push of the pen refill holder against the clutch bracket 19 and clutch teeth 12 automatically engages the injection teeth 11 and clutch teeth 12. This engagement only requires that the injection teeth 11 and clutch teeth 12 rotate together during injection. Simultaneously, the clutch spring 18 is compressed to store elastic potential energy. The entire process requires no manual intervention, making it highly convenient to operate. The design to prevent clutch failure after engagement avoids accidental separation of clutch teeth 12 and injection teeth 11 during injection, ensuring the continuity of injection power transmission, guaranteeing the accuracy of single injection dosage, and laying the foundation for the reset action after injection.

[0047] In some embodiments of the present invention, pressing the injection button 14 causes the clutch lever 5 to move downward, the upper part of the clutch lever 5 to disengage from the jumping tooth 6, and the lower part of the clutch lever 5 to engage with the outer periphery of the injection tooth 11. Under the torsion of the torsion spring 10, the clutch lever 5 rotates counterclockwise and drives the injection tooth 11 and the clutch tooth 12 to rotate synchronously. The clutch tooth 12 drives the small push rod 16 to rotate downward to push the rubber stopper 21 to achieve the injection purpose. The operation logic adopts a "press-to-switch" clutch control method, which is responsive and precise: pressing the injection button 14 disengages the clutch lever 5 from the jumping tooth 6 and engages it with the injection tooth 11, quickly completing the state switch from "dosage adjustment" to "injection execution", adapting to the high-frequency operation requirements of reusable scenarios; the torsion spring 10 serves as the injection power source, with stable output and low power loss, ensuring that the small push rod 16 moves down at a uniform speed to push the rubber stopper 21, avoiding injection pain caused by uneven pushing force and improving the user experience of reusable injections; the synchronous rotation transmission mechanism of multiple components effectively reduces transmission gaps, ensuring the dosage accuracy of each injection and meeting the medication safety requirements of reusable scenarios.

[0048] In some embodiments of the present invention, when the injection is completed and the pen holder 20 is removed, the clutch bracket 19 will move downward a certain distance under the release action of the clutch spring 18. When the clutch bracket 19 moves, it will drive the clutch teeth 12 to move downward synchronously and separate from the injection teeth 11. At this time, the small push rod 16 can be pushed back to the initial position of the small push rod, i.e., position 0; push the small push rod 16 to rotate and move towards the injection button 14, and the small push rod 16 will drive the clutch teeth 12 to rotate in place. This reset mechanism is the core guarantee for reusability: after injection, removing the pen cartridge holder 20 triggers the elastic release of the clutch spring 18, causing the clutch bracket 19 and clutch teeth 12 to move down synchronously, thereby separating the ratchet of the injection teeth 11 and the clutch teeth 12 and releasing their transmission lock; in the separated state, the small push rod 16 can be easily pushed back to the 0 position, preparing for the next dose adjustment and injection. The reset process does not require special tools and is easy to operate; the small push rod 16 drives the clutch teeth 12 to rotate in place, which can avoid tooth surface meshing interference during the reset process, reduce component wear, extend the service life of reusability, and at the same time ensure the stability of the clutch teeth 12's posture, facilitating subsequent re-meshing with the injection teeth 11.

[0049] In some embodiments of the present invention, the dosage adjustment structure includes a knob 8, a ratchet tooth 6, a meshing tooth 4, a bushing cover 2, a spring tooth 3, and a release spring 17. The meshing tooth 4 has a lower meshing tooth 42 and an upper meshing tooth 41. The lower meshing tooth 42 engages with the spring tooth 3, and the upper meshing tooth 41 engages with the ratchet tooth 6. The ratchet tooth 6 also engages with the upper section of the clutch lever 5 via a ratchet structure, and engages with the knob 8 via the ratchet structure. When the knob 8 is rotated counterclockwise, the knob 8 engages with the ratchet tooth 6 and drives the ratchet tooth 6 to rotate synchronously. The ratchet tooth 6 simultaneously drives the meshing tooth 4, the clutch lever 5, and the scale cylinder 1 to rotate synchronously for dosage adjustment. The dosage adjustment structure also includes a scale cylinder 1 that engages with the lower section of the clutch lever 5 of the automatic injector. A bushing cover 2 is fitted to the upper end of the scale cylinder 1, and spring teeth 3 are arranged around the inner circumference of the bushing cover 2. The meshing tooth 4 engages with the spring tooth 3 after rotating one scale unit. The meshing mechanism re-engages and produces a clicking sound. A limiting element 7 is located below the graduated cylinder 1 to restrict its maximum downward rotation. Once the graduated cylinder 1 reaches the three collision points at the top of the limiting element 7, it is stopped and its movement is restricted, preventing further dosage increases and allowing only dosage reduction or injection. This dosage adjustment structure provides precise dosage control for repeated injections: the unidirectional transmission path formed by multiple ratchet engagements ensures no reverse slippage during dosage adjustment, maintaining consistent dosage accuracy in each repetition and avoiding medication risks due to adjustment deviations; the clicking sound feedback from the spring tooth 3 and meshing tooth 4 provides clear scale switching prompts for accurate dosage control during repeated operations; the three-point positioning and limiting design of the limiting element 7 prevents medication safety hazards caused by over-adjustment and avoids component overload damage, adapting to the structural stability requirements of repetitive use scenarios.

[0050] In some embodiments of the present invention, the bottom of the jumping tooth 6 includes a first-stage tooth root shaft and a second-stage tooth root shaft that taper inward in sequence. The first-stage tooth root shaft is provided with four sets of first-stage jumping lower teeth 61 that mesh with the meshing upper teeth 41 of the meshing tooth 4. The second-stage tooth root shaft is provided with second-stage jumping lower teeth 62 that mesh with the knob internal ratchet provided inside the knob 8. The four sets of first-stage jumping lower teeth 61 are centrally symmetrically distributed on the first-stage tooth root shaft. The inner circumference of the jumping tooth 6 is also provided with jumping internal ratchet 63. The jumping internal ratchet 63 meshes with the clutch rod ratchet of the upper section of the clutch rod 5 for transmission. By axial pressing, the clutch rod ratchet can be disengaged from the jumping internal ratchet 63. The graded symmetrical structure of the ratchet 6 provides stable transmission support for repeated use: the stepped design of the first-stage and second-stage tooth root shafts allows the ratchet 6 to simultaneously achieve precise engagement with the meshing teeth 4 and the knob 8, resulting in a compact structure and efficient transmission, reducing power loss during repeated operations; the four sets of centrally symmetrical first-stage ratchet lower teeth 61 can evenly distribute the transmission force, avoid localized overload wear of the tooth surfaces, significantly extend the life of the components, and meet the high-frequency operation requirements of repeated use; the axial pressing disengagement structure of the ratchet inner ratchet 63 and the clutch ratchet is responsive and reliable, enabling rapid completion of dose adjustment and injection state switching, ensuring the continuity of repeated operations.

[0051] In some embodiments of the present invention, the inner wall of the knob 8 is connected to an inner ring platform via an inner knob bracket, and the upper part of the meshing tooth 4 is engaged with a jumping tooth 6 via a ratchet structure; the height of the meshing point between the jumping tooth 6 and the ratchet on the upper surface of the inner ring platform is greater than the height of the meshing point between the jumping tooth 6 and the meshing tooth 4. When the knob 8 is rotated clockwise, due to the backlash gap between the inner ring platform and the jumping tooth 6 in the reverse direction, the knob 8 can push the jumping tooth 6 upward through the inner ratchet 81 provided on the upper part of the inner ring platform, thereby disengaging the jumping tooth 6 from the meshing tooth 4 below and rotating it to the next meshing position with the meshing tooth 4; the injection button 14 is detachably engaged with the top of the clutch lever 5 via a locking piece; the injection button 14 is provided with a release spring 17 inside, and when the jumping tooth 6 rotates in the opposite direction under the action of the torsion spring 10 to the next meshing position with the meshing tooth 4, the jumping tooth 6... The downward force exerted by the release spring 17 and the meshing teeth 4 produce a meshing sound. This dosage adjustment structure and button design further optimize the reusability experience: the engagement height between the jumping teeth 6 and the inner ring of the knob is greater than the engagement height between the jumping teeth 6 and the meshing teeth 4, and the adjustment gap design allows for precise dose reduction, a smooth and uninterrupted adjustment process, and adapts to the dosage adjustment needs during repeated injections; the release spring 17 provides a continuous downward preload to the jumping teeth 6, ensuring a tight engagement with the meshing teeth 4 and preventing loosening during repeated adjustments. The meshing sound also provides feedback on the adjusted position, improving operational accuracy; the detachable snap-fit ​​design of the injection button 14 facilitates component disassembly and maintenance. If the button or clutch lever 5 is damaged, it can be replaced individually without requiring complete scrapping, reducing maintenance costs for repeated use.

[0052] In some embodiments of the present invention, the lower section of the clutch lever 5 is provided with a strip-shaped clutch lever limiting groove, which engages with the strip-shaped scale cylinder limiting boss on the inner wall of the scale cylinder 1 for transmission; the outer wall of the scale cylinder 1 is provided with multiple turns of scale thread and engages with the inner wall thread of the bushing 9 of the automatic injector. When the clutch lever 5 drives the scale cylinder 1 to rotate, the scale cylinder 1 will rotate downward relative to the bushing 9. The engagement structure between the clutch lever 5 and the graduated cylinder 1 provides a stable guarantee for repeated dose adjustment: the concave-convex fit between the clutch lever limiting groove and the graduated cylinder limiting boss ensures that the two rotate synchronously and can slide relative to each other axially. The dose adjusted each time strictly corresponds to the displacement of the graduated cylinder 1, improving the consistency of dose control. The fine thread engagement between the graduated cylinder 1 and the bushing 9 has a small lead and high adjustment accuracy, which can meet the dose requirements of different medication scenarios. At the same time, the thread engagement has strong self-locking properties, preventing the graduated cylinder 1 from moving on its own during repeated use, thus ensuring dose stability.

[0053] In some embodiments of the present invention, the upper outer periphery of the injection tooth 11 is provided with an upper engagement tooth 111 capable of engaging with the lower end of the clutch lever 5, and the lower inner periphery of the injection tooth 11 is provided with a lower ratchet tooth that engages with the clutch ratchet 121 on the clutch tooth 12. At least one injection tooth spring arm 112 is arranged around the lower outer periphery of the injection tooth 11. The injection tooth spring arm 112 engages with the upper ratchet 131 of the fixed chamber 13 provided on the upper inner periphery of the fixed chamber. When the injection tooth 11 rotates, the injection tooth spring arm 112 and the upper ratchet 131 of the fixed chamber bounce radially and emit a bouncing sound to indicate to the user that an injection is being performed. The multiple engagement structure of the injection tooth 11 provides real-time status feedback for repeated injections: the radial runout engagement between the injection tooth spring arm 112 and the ratchet 131 on the fixed chamber provides audible feedback on the injection progress, allowing the user to clearly perceive whether the injection is proceeding normally and avoid errors caused by misjudgment of status during repeated operations; the multiple meshing structure ensures continuous power transmission, reduces transmission jamming during repeated injections, and the elastic deformation of the spring arm can buffer impacts, reduce tooth surface wear, and extend component life.

[0054] In some embodiments of the present invention, the lower section of the fixed chamber 13 has a nested double-layer structure formed by a fixed inner tube and a fixed outer tube. A clutch spring 18 is sleeved between the fixed inner tube and the fixed outer tube, and the lower section of the fixed inner tube is threaded. The outer periphery of the clutch tooth 12 is provided with a clutch tooth ratchet 121, and the inner periphery of the clutch tooth 12 is provided with a clutch engagement boss. The clutch engagement boss is in transmission engagement with the screw limiting recess provided on the outer periphery of the small push rod 16. At the same time, the small push rod 16 is also in threaded engagement with the inner periphery of the lower section of the fixed chamber 13. The double-layer structure design of the fixed chamber 13 enhances the structural stability for repeated use: the nested double-layer structure provides an independent installation space for the clutch spring 18, avoiding interference with other components during repeated extension and contraction, and ensuring the reliability of the elastic reset function; the threaded design of the inner tube of the fixed chamber facilitates precise connection with the pen refill holder 20, ensuring the assembly accuracy after each consumable replacement, while the threaded engagement between the small push rod 16 and the fixed chamber 13 enables precise conversion from rotational motion to axial movement, ensuring the consistency of dosage during repeated injections.

[0055] In some embodiments of the present invention, a memory element 22 is also included. The memory element 22 is movably fitted inside the clutch lever 5 via a sliding groove structure and can move up and down along the internal space of the clutch lever 5. It is also threaded onto the small push rod 16. There is an adjustment gap at the engagement point between the injection tooth 11 and the fixed chamber 13. A memory spring 23 is also provided on the upper part of the clutch tooth 12 inside the injection tooth 11. The clutch tooth 12 is driven to engage with the small push rod 16. The injection tooth 11 and the clutch tooth 12 are also connected and engaged via a ratchet structure. By pressing the injection button 14, the clutch lever 5 moves down. The upper part of the clutch lever 5 disengages from the jumping tooth 6, and the lower part of the clutch lever 5 engages with the outer periphery of the injection tooth 11. Under the torque of the torsion spring 10, the clutch lever 5 rotates counterclockwise and drives the injection tooth 11 and the clutch tooth 12 to rotate synchronously. The clutch tooth 12 drives the small push rod 16 to rotate downward to push the rubber stopper 21. The injection purpose is achieved. The original position of the memory element 22 is above the injection tooth 11. In the original position, the memory spring 23 supports the memory element 22 by pushing up the injection tooth 11. When the memory element 22 is reset, there is a possibility of contact with the injection tooth. If the injection tooth is fixed upward in the axial direction, the memory element may be stuck by the small push rod 16 and the injection tooth and cannot rotate. In this embodiment, the injection tooth 11 can be adjusted downward to avoid jamming the memory element 22. The design of the memory element 22 and the adjustment gap provides anti-locking protection for repeated use: the sliding groove and thread double-fit structure of the memory element 22 ensures that there is no offset or jamming during repeated up and down movement, and accurately records the dosage of each injection; the adjustment gap between the injection tooth 11 and the fixed chamber 13 can provide clearance space when the memory element 22 is blocked during reset, completely solving the lock-up problem of traditional structures during repeated use; the pushing action of the memory spring 23 ensures the stability of the memory element 22 in the original position and avoids displacement deviation caused by unstable support during repeated operation.

[0056] In some embodiments of the present invention, the clutch lever 5 has an outer rod coil 51 and an inner rod coil 52 disposed within the outer rod coil 51. The small push rod 16 is disposed in a chamber within the inner rod coil 52, and the torsion spring 10 is disposed in the gap space 15 between the outer rod coil 51 and the inner rod coil 52. The double-layer coil structure of the clutch lever 5 provides structural support for repeated use: the separation design of the inner and outer double coils provides independent installation space for the torsion spring 10 and the small push rod 16, avoiding interference between components during repeated movements; the double-layer structure enhances the overall rigidity of the clutch lever 5, preventing bending deformation after long-term repeated use and extending the service life of the syringe.

[0057] In some embodiments of the present invention, a pen body 25 is fitted over the clutch lever 5, the dosage adjustment structure, and the injection structure. A viewing window 26 for observing the dosage is provided on the surface of the pen body 25. A refill holder 20 is disposed outside the cartridge bottle 24 and connected to the lower part of the fixing chamber 13. The cartridge bottle 24 is disposed inside the refill holder, and the cartridge bottle 24 stores the medication to be injected. A pen cap 27 is detachably connected to the pen body 25 outside the refill holder 20, and the pen cap 27 can be removed when injection is required. The design of the pen body 25 and pen cap 27 provides comprehensive protection for reusability: the viewing window 26 of the pen body 25 allows users to intuitively read the dosage during repetitive operations, improving operational convenience; the detachable design of the cartridge bottle 24 enables rapid replacement of consumables and is the core carrier for reusability; the pen cap 27 protects the injection end when not in use, preventing contamination or damage from impacts, extending the lifespan of reusability. Its detachable connection method adapts to high-frequency disassembly and assembly requirements, making operation convenient.

[0058] In other embodiments of the present invention, the connection between the pen refill holder 20 and the fixing chamber 13 adopts a foolproof design. The concave-convex positioning structure ensures that the pen refill holder 20 can only be assembled in a single direction, avoiding damage to the components due to incorrect orientation during repeated installation, and further improving the safety and convenience of repeated use. The viewing window 26 of the pen body 25 is made of a highly transparent and wear-resistant material, which can withstand wiping and friction during long-term repeated use and maintain a clear dose observation effect.

[0059] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A reusable automatic injector, characterized in that, include: The pen body (25), pen refill holder (20), clutch lever (5), injection button (14), small push rod (16), and torsion spring (10) are included. The injection structure includes injection teeth (11) and clutch teeth (12), wherein the clutch teeth (12) are engaged with the small push rod (16), and the injection teeth (11) and clutch teeth (12) are separably connected via a ratchet structure. When the pen refill holder (20) is connected to the pen body (25), the injection teeth (11) and clutch teeth (12) engage. Pressing the injection button (14) causes the clutch lever (5) to move downwards, and the lower section of the clutch lever (5) engages with the injection teeth (11). 1) Engagement: The clutch lever (5) rotates under the torque of the torsion spring (10) and drives the injection tooth (11) and the clutch tooth (12) to rotate synchronously. The clutch tooth (12) drives the small push rod (16) to rotate downward to push the rubber stopper (21) to achieve the injection purpose. When the pen cartridge holder (20) is separated from the pen body (25), the clutch tooth (12) moves downward and separates from the injection tooth (11). The clutch tooth (12) can rotate freely relative to the injection tooth (11). At this time, it can push the small push rod (16) to rotate and move towards the injection button (14), thereby realizing the reset of the small push rod (16). It also includes a fixing chamber (13), through which the pen refill holder (20) is connected to the pen body (25). The injection tooth (11) and the clutch tooth (12) are both assembled in the fixing chamber (13). A clutch bracket (19) is provided at the lower part of the fixing chamber (13). A clutch spring (18) is provided between the clutch bracket (19) and the fixing chamber (13). The pen refill holder (20) is detachably connected to the lower part of the fixing chamber (13) and can cooperate with the clutch bracket (19). The fixing chamber is fixedly connected to the pen body. When the pen refill holder (20) is separated from the fixing chamber (13), the clutch bracket (19) moves downward under the action of the clutch spring (18). When the clutch bracket (19) moves downward, it drives the clutch tooth (12) to move downward and separate from the injection tooth (11).

2. The auto-injector according to claim 1, characterized in that, It also includes a dose adjustment structure, which includes a knob (8), a jumping tooth (6), a meshing tooth (4), a bushing cover (2), a spring tooth (3), and a release spring (17). The meshing tooth (4) has a lower meshing tooth (42) and an upper meshing tooth (41). The lower meshing tooth (42) engages with the spring tooth (3), and the upper meshing tooth (41) engages with the jumping tooth (6). When the knob (8) is rotated counterclockwise, the knob (8) engages with the jumping tooth (6) and drives the jumping tooth (6) to rotate synchronously. The jumping tooth (6) simultaneously drives the meshing tooth (4) and the clutch lever (5) to rotate synchronously for dose adjustment. The spring tooth (3) is located on the inner circumference of the bushing cover. After the meshing tooth (4) rotates by one scale unit, it will re-engage with the spring tooth (3) and make a clicking sound.

3. The auto-injector according to claim 2, characterized in that, It also includes a scale cylinder (1), and a limiter (7) is provided below the scale cylinder (1) to limit the maximum stroke of the scale cylinder (1) rotating downward.

4. The auto-injector according to claim 2, characterized in that, The bottom of the jumping tooth (6) includes a primary tooth root shaft and a secondary tooth root shaft. The primary tooth root shaft is provided with a primary jumping lower tooth (61) that meshes with the meshing upper tooth (41) of the meshing tooth (4). The secondary tooth root shaft is provided with a secondary jumping lower tooth (62) that meshes with the knob inner ratchet provided inside the knob (8). The inner circumference of the jumping tooth (6) is also provided with a jumping inner ratchet (63). The jumping inner ratchet (63) meshes with the clutch rod ratchet of the upper section of the clutch rod (5) for transmission. By axial pressing, the clutch rod ratchet can be disengaged from the jumping inner ratchet (63).

5. The auto-injector according to claim 4, characterized in that, The inner wall of the knob (8) is connected to the inner ring platform of the knob via the inner knob bracket. The inner ratchet of the knob is set on the inner ring platform of the knob. The engagement height of the secondary jumping lower tooth (62) and the inner ratchet of the knob is greater than the engagement height of the upper tooth (41) and the primary jumping lower tooth (61). There is a back-off gap between the inner ring platform of the knob and the jumping tooth (6) in the clockwise rotation direction. When the dosage is adjusted, the knob (8) is rotated clockwise, and the inner ratchet of the knob pushes the secondary jumping lower tooth (62) upward, thereby disengaging the upper tooth (41) from the primary jumping lower tooth (61). When the jumping tooth (6) rotates in the opposite direction under the action of the torsion spring (10) to the next engagement position with the engagement tooth (4), the jumping tooth (6) re-engages with the engagement tooth (4) due to the downward force given by the release spring (17) and makes a meshing sound.

6. The auto-injector according to claim 2, characterized in that, The lower section of the clutch rod (5) is provided with a clutch rod limiting groove, which cooperates with the scale cylinder limiting boss on the inner wall of the scale cylinder (1) for transmission; the outer wall of the scale cylinder (1) is provided with multiple turns of scale thread and forms a cooperation with the inner wall thread of the bushing (9) of the automatic injector. When the clutch rod (5) drives the scale cylinder (1) to rotate, the scale cylinder (1) will rotate downward relative to the bushing (9).

7. The auto-injector according to claim 1, characterized in that, The upper outer periphery of the injection tooth (11) is provided with an upper engagement tooth (111) that can engage with the lower end of the clutch lever (5). The outer periphery of the clutch tooth (12) is provided with a clutch ratchet (121). The lower inner periphery of the injection tooth (11) is provided with a lower ratchet that engages with the clutch ratchet (121). At least one injection tooth spring arm (112) is arranged around the lower outer periphery of the injection tooth (11). The injection tooth spring arm (112) engages with the upper ratchet (131) of the fixed chamber provided on the inner periphery of the upper section of the fixed chamber (13). When the injection tooth (11) rotates, the injection tooth spring arm (112) and the upper ratchet (131) of the fixed chamber bounce radially and make a bouncing sound to indicate to the user that an injection is being performed.

8. The auto-injector according to claim 7, characterized in that, The lower section of the fixed chamber (13) has a nested double-layer structure formed by a fixed inner tube and a fixed outer tube. A clutch spring (18) is sleeved between the fixed inner tube and the fixed outer tube. The lower section of the fixed inner tube is provided with a thread that engages with the small push rod. The inner circumference of the clutch tooth (12) is provided with a clutch engagement boss. The clutch engagement boss engages with the screw limiting recess provided on the outer circumference of the small push rod (16).

9. The automatic injector according to claim 1, characterized in that, It also includes a memory element (22), which is movably fitted inside the clutch rod (5) through a sliding groove structure. The memory element (22) is threadedly fitted with the small push rod. There is an adjustment gap at the fit between the injection tooth (11) and the fixed chamber (13). A memory spring (23) is provided inside the injection tooth (11). When the memory element abuts against the injection tooth, the memory spring (23) and the adjustment gap cause the injection tooth to move downward.

10. The auto-injector according to claim 1, characterized in that, The clutch lever (5) has an outer rod ring (51) and an inner rod ring (52) disposed on the outer rod ring (51). The small push rod (16) is disposed in the cavity inside the inner rod ring (52). The torsion spring (10) is disposed in the gap space (15) between the outer rod ring (51) and the inner rod ring (52).

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