A reusable pre-filled syringe assisted injection device

Abstract

The application discloses a reusable pre-filled auxiliary injection device, which comprises a shell, a bushing, a sleeve, a trigger, a push rod and a trigger spring. The bushing is fixed in the shell and is provided with an elastic arm, and the elastic arm is provided with a stop surface. The sleeve is movably arranged in the bushing, and the outer wall of the sleeve is provided with a first limiting protrusion capable of being clamped with the stop surface and an opening. The trigger is movably arranged in the sleeve and is provided with a second protrusion, and the second protrusion is extended out of the sleeve through the opening to act on the elastic arm. The push rod is movably arranged in the sleeve and is arranged in the trigger. The trigger spring is arranged between the sleeve and the trigger, and the trigger spring applies an elastic force to the trigger. When injection is performed, the push rod pushes the trigger to make the second protrusion push and deform the elastic arm, and the clamping of the stop surface and the first limiting protrusion is released. After the pushing force is removed, the trigger spring drives the trigger to drive the push rod to actively rebound, the second protrusion is separated from the elastic arm, and the elastic arm restores the deformation. The application solves the problem that the push rod cannot be reset, the elastic arm is disabled, the reliability and safety of the device are improved.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more specifically to a reusable pre-filled auxiliary injection device. Background Technology

[0002] Prefilled injection devices, which integrate drug storage and injection functions, offer advantages such as precise drug delivery and ease of operation, and are increasingly widely used in patient self-medication scenarios.

[0003] However, in practical use, existing pre-filled injection devices often lack an active springback mechanism for the push rod used to unlock and trigger needle withdrawal after injection. This causes the push rod to remain in the working position after the user stops applying force, continuously pressing against the locking spring arm. Under prolonged or repeated exposure to this continuous stress, the spring arm is prone to plastic deformation, leading to weakened elasticity and ultimately causing the locking structure to fail, severely impacting the service life and safety of the injection device.

[0004] There is currently no effective solution to the aforementioned problems in the existing technology. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a reusable pre-filled auxiliary injection device. This device enables the push rod to actively rebound, ensuring the long-term reliable elastic locking performance of the spring arm, thereby guaranteeing the service life and safety of the injection device.

[0006] Specifically, the following technical solutions are included: This invention provides a reusable pre-filled injection aid device, comprising: case; A bushing is fixedly disposed inside the housing. The bushing is provided with a spring arm, and the spring arm is provided with a stop surface. A sleeve is movably disposed within the bushing. The outer wall of the sleeve is provided with a first limiting protrusion and an opening. The first limiting protrusion can engage with the stop surface to restrict the sleeve from moving away from the bushing. A trigger is movably disposed within the sleeve, the trigger having a second protrusion extending through the opening to act on the spring arm; A push rod is movably disposed within the sleeve and passes through the trigger member. The push rod is capable of abutting against the trigger member to push the trigger member to move towards the end closer to the bushing when the push rod moves towards the end closer to the bushing, and to push the push rod to move towards the end farther from the bushing when the trigger member moves towards the end farther from the bushing. A trigger spring is disposed between the sleeve and the trigger member, and applies an elastic force to the trigger member toward the end away from the bushing; During the injection process, the push rod pushes the trigger member to move towards the end closer to the bushing, causing the second protrusion to push the spring arm outward and elastically deform, thereby releasing the engagement between the stop surface and the first limiting protrusion; when the pushing force on the push rod is removed, the trigger spring drives the trigger member to move away from the bushing, and drives the push rod to rebound away from the bushing, the second protrusion disengages from the spring arm, and the spring arm returns to its original deformation.

[0007] In one embodiment of the present invention, the elastic arm is a cantilevered elastic body extending from the side wall of the bushing, and its inner side is also provided with an inclined guide surface; the first limiting protrusion can slide along the inclined guide surface and force the elastic arm to expand outward when the sleeve moves towards the end close to the bushing, until it passes the stop surface and is blocked by the stop surface.

[0008] In one embodiment of the present invention, the trigger includes a trigger sleeve and an extension arm extending outward from the end of the trigger sleeve, the second protrusion being disposed on the outer edge of the end of the extension arm; the sleeve has a receiving cavity inside, one end of the receiving cavity is provided with an abutment surface, the trigger is movably received in the receiving cavity, one end of the trigger spring abuts against the abutment surface, and the other end abuts against the inside of the trigger sleeve.

[0009] In one embodiment of the present invention, the extendable arm passes through the opening and abuts against the sliding surface provided on the outer wall of the sleeve; the outer wall of the sleeve is also provided with a second limiting protrusion, the second limiting protrusion being offset from the sliding surface, and the second protrusion being restricted between the first limiting protrusion and the second limiting protrusion to limit the axial movement range of the trigger.

[0010] In one embodiment of the present invention, the outer wall of the push rod is further provided with an elastic buckle, and the inner wall of the sleeve is provided with a third limiting protrusion. The elastic buckle can pass over and engage below the third limiting protrusion to prevent the push rod from coming out of the sleeve. The side of the elastic buckle is provided with an elastic damping boss, which is used to rub against the inner wall of the sleeve.

[0011] In one embodiment of the present invention, the bushing has a first protrusion on its outer periphery, and the inner wall of the housing has an embedding groove, wherein the first protrusion is embedded in the embedding groove to fix the bushing; the inner wall of the housing has an inwardly protruding boss, and the outer wall of the sleeve has an abutment platform, wherein the boss can abut against the abutment platform to limit the axial displacement of the sleeve; the inner wall of the bushing has an axially extending guide rib, and the outer wall of the sleeve has an axially extending guide groove, wherein the guide rib and the guide groove are slidably engaged to limit the relative rotation between the sleeve and the bushing; the inner wall of the housing also has an avoidance notch, which is located on the outside of the spring arm to provide space for the spring arm to expand outward.

[0012] In one embodiment of the present invention, the top of the bushing is provided with a first abutting ring, and the top of the sleeve is provided with a second abutting ring. The second abutting ring can abut against the first abutting ring to limit the movement of the sleeve toward one end closer to the bushing. The outer wall of the push rod is provided with a third abutting ring, which is used to abut against the end face of the trigger.

[0013] In one embodiment of the present invention, a pen refill holder detachably connected to the housing is further included. The pen refill holder is provided with a needle ejector and a needle ejector spring. The needle ejector is movably disposed within the pen refill holder and is capable of pushing the sleeve to move away from the bushing. The needle ejector spring is disposed between the needle ejector and the pen refill holder and is used to apply an elastic force toward the sleeve to the needle ejector. The end of the needle ejector is provided with an elastic buckle, and the inner wall of the pen refill holder is provided with a fastening boss. The elastic buckle is hooked onto the fastening boss.

[0014] In one embodiment of the present invention, the pen refill holder is further provided with an adjusting ring, a hidden needle component, and a hidden needle spring; the adjusting ring is rotatably connected to the pen refill holder, the hidden needle component is movably sleeved inside the adjusting ring, and the hidden needle spring is disposed between the hidden needle component and the pen refill holder to apply an elastic force away from the pen refill holder to the hidden needle component; the outer wall of the hidden needle component is provided with a limiting boss, and the inner wall of the adjusting ring is provided with a stepped surface that changes in a stepped manner along the axial direction, and the limiting boss can abut against the stepped surface to limit the retraction stroke of the hidden needle component.

[0015] In one embodiment of the present invention, the outer wall of the adjusting ring is provided with a plurality of positioning grooves, and the inner wall of the pen refill holder is provided with a plurality of protruding ribs. The positioning grooves and the protruding ribs cooperate to provide gear feedback when the adjusting ring is rotated. The outer wall of the hidden needle is provided with a limiting buckle, which can abut against the end face of the adjusting ring to limit the extreme position of the hidden needle away from the pen refill holder.

[0016] The beneficial effects of this invention are: 1. This invention achieves active springback of the push rod, completely preventing fatigue failure of the locking spring arm and significantly improving the service life and reliability of the injection device. In existing technologies, the push rod lacks a springback mechanism after injection, continuously pressing on the locking spring arm, which can easily cause plastic deformation and failure. This invention constructs an active springback structure by setting a trigger spring between the sleeve and the trigger element. When the injection stroke ends, once the thrust on the push rod is removed, the elastic force stored in the trigger spring is immediately released, driving the trigger element and pushing the push rod to actively and quickly spring back to its original position. This action ensures that the second protrusion on the trigger element can be quickly and reliably pulled away from the inside of the bushing's spring arm, allowing the spring arm to fully recover its deformation. This fundamentally avoids the risk of stress relaxation or plastic deformation of the spring arm due to prolonged continuous stretching, ensuring that the injection device maintains long-term, stable locking performance even after multiple uses, greatly improving the device's safety and durability.

[0017] 2. The injection operation is comfortable, and the needle withdrawal process is smooth and reliable, providing a superior user experience. At the start of injection, the first limiting protrusion on the sleeve slides along the inclined guide surface inside the bushing spring arm, forcing the spring arm to expand outward until it is locked by the stop surface. This inclined surface engagement mechanism not only makes the downward pressing and locking process of the sleeve smooth and effortless, but also provides clear tactile feedback upon arrival. At the end of injection, the push rod pushes the trigger element, using its second protrusion to precisely push the inclined guide surface of the spring arm, efficiently converting the axial motion into the radial opening motion of the spring arm, achieving sensitive and effortless locking release. Combined with the aforementioned push rod active rebound characteristic, the entire sequence of locking, injection, unlocking, and needle withdrawal is coherent, without jamming or delay, greatly optimizing the user's operating experience.

[0018] 3. Precise needle depth adjustment with tactile feedback solves the problems of inconvenient adjustment and lack of tactile feedback, making operation more precise and user-friendly. Addressing the issue of existing adjustment mechanisms being continuously stepless and lacking feedback, this invention designs a collaborative component involving an adjustment ring, a concealed needle, and a refill holder. By using a stepped surface on the inner wall of the adjustment ring that engages with the limiting protrusion of the concealed needle, multi-level precise adjustment of the needle protrusion length is achieved. A positioning groove on the outer wall of the adjustment ring and a corresponding protruding rib on the inner wall of the refill holder, when rotated for adjustment, produce a clear "click" sound and tactile feedback, providing the user with clear auditory and tactile feedback. This design allows even patients with poor eyesight or limited experience to easily and accurately set the desired needle depth, ensuring the accuracy of drug injection and patient comfort, and avoiding adverse effects caused by improper depth.

[0019] 4. The complete retraction and concealed needle mechanism reset provides reliable secondary needle protection, eliminating the risk of needlestick injuries. Existing devices may experience incomplete internal structure reset after needle retraction, resulting in the concealed needle component failing to securely protect the needle. This invention employs a linked design between the sleeve, the needle retraction component, and the needle retraction spring. Before injection, pressing down the sleeve compresses the needle retraction spring and locks it in place. Upon completion of injection, the trigger releases the lock, instantly releasing the powerful spring force that pushes the needle retraction component and sleeve upwards to reset, completing automatic needle retraction. This rigidly linked reset mechanism, combined with the active rebound of the push rod, ensures that the moving parts reliably return to their initial position after injection. After the needle retracts, the concealed needle component remains securely in the extended needle-protecting position under the action of the concealed needle spring, unaffected by other mechanisms, thus providing reliable secondary protection and completely preventing the risk of needlestick injuries due to accidental needle re-extension before and after injection. Attached Figure Description

[0020] Figure 1 This is a perspective view of the reusable pre-filled auxiliary injection device of the present invention.

[0021] Figure 2 This is an exploded view of the reusable pre-filled auxiliary injection device of the present invention.

[0022] Figure 3 This is a cross-sectional perspective view of the housing of the present invention.

[0023] Figure 4 This is a perspective view of the bushing of the present invention.

[0024] Figure 5 This is a cross-sectional perspective view of the bushing of the present invention.

[0025] Figure 6 This is a perspective view of the sleeve of the present invention.

[0026] Figure 7 This is a cross-sectional perspective view of the sleeve of the present invention.

[0027] Figure 8 This is a perspective view of the trigger element of the present invention.

[0028] Figure 9 This is a perspective view of the push rod of the present invention.

[0029] Figure 10 This is a cross-sectional view of a portion of the reusable pre-filled auxiliary injection device of the present invention during the injection process.

[0030] Figure 11 for Figure 10 A magnified view of A in the middle.

[0031] Figure 12 This is a perspective view of the hidden needle component of the present invention.

[0032] Figure 13 This is a perspective view of the adjusting ring of the present invention.

[0033] Figure 14 This is a three-dimensional cross-sectional view of the adjusting ring of the present invention.

[0034] Figure 15 This is a perspective view of the pen refill holder of the present invention.

[0035] Figure 16 This is a cross-sectional perspective view of the pen refill holder of the present invention.

[0036] Figure 17 This is a perspective view of the needle retraction component of the present invention.

[0037] In the diagram: 1. Housing; 1001. Embedded groove; 1002. Boss; 1003. Clearance notch; 2. Bushing; 20. Spring arm; 21. First protrusion; 22. Guide rib; 23. Stop surface; 24. First abutment ring; 25. Inclined guide surface; 3. Sleeve; 30. Second abutment ring; 31. Abutment platform; 32. Guide groove; 33. First limiting protrusion; 34. Second limiting protrusion; 35. Third limiting protrusion; 36. Receiving cavity; 37. Abutment surface; 38. Opening; 39. Sliding surface; 4. Trigger spring; 5. Trigger element; 51. Second protrusion; 52. Extending arm; 53. Trigger sleeve; 6. Push rod; 61. Elastic buckle; 62. Elastic damping boss; 63. Third abutment ring; 64. Pressing end; 7. Pen cap; 8. Hidden needle component; 81. Limiting boss; 82. Limiting buckle; 9. Hidden needle spring; 10. Adjusting ring; 101. Stepped surface; 102. Positioning groove; 103. Annular protrusion; 11. Pen refill holder; 111. Annular groove; 112. Protruding rib; 113. Snapping boss; 12. Needle retraction spring; 13. Needle retraction component; 131. Elastic buckle. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described 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.

[0039] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

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

[0041] like Figures 1 to 11 As shown, the present invention provides a reusable pre-filled auxiliary injection device, including a housing 1 and a pen refill holder 11 detachably connected to the housing 1; a bushing 2 is fixedly installed inside the housing 1, a movable sleeve 3 is provided inside the bushing 2, a movable trigger 5 and a push rod 6 are provided inside the sleeve 3, a trigger spring 4 is provided between the sleeve 3 and the trigger 5, and the push rod 6 passes through the trigger 5 and the trigger spring 4; a movable needle retraction member 13 is installed inside one end of the pen refill holder 11, the needle retraction member 13 is used to drive the sleeve 3 to move upward, a needle retraction spring 12 is provided between the needle retraction member 13 and the pen refill holder 11, a rotatable adjusting ring 10 is installed at the other end of the pen refill holder 11, a hidden needle member 8 is installed inside the adjusting ring 10, a hidden needle spring 9 is provided between the hidden needle member 8 and the pen refill holder 11, and a pen cap 7 is sleeved on the outer side of the pen refill holder 11 facing the hidden needle member 8.

[0042] In some embodiments, an annular insert groove 1001 is provided on the inner wall of one end of the housing 1, and a first protrusion 21 that mates with the insert groove 1001 is provided on the outer periphery of the bushing 2. The first protrusion 21 can be inserted into the insert groove 1001 so that the bushing 2 is fixedly installed in the housing 1. The other end of the housing 1 is detachably connected to the pen refill holder 11. An inwardly protruding boss 1002 is provided on the inner wall of the housing 1, and an abutment platform 31 that mates with the boss 1002 is provided on the outer wall of the sleeve 3. The boss 1002 can abut against the abutment platform 31 to lock the sleeve 3 in the housing 1, thereby restricting the axial displacement of the sleeve 3 and preventing the sleeve 3 from coming out of the housing 1.

[0043] In some embodiments, the bushing 2 is provided with a spring arm 20. The end of the spring arm 20 is provided with a stop surface 23 for locking the sleeve 3. The inner side of the spring arm 20 is provided with an inclined guide surface 25. The outer wall of the sleeve 3 is provided with an outwardly protruding first limiting protrusion 33, which cooperates with the spring arm 20. When the sleeve 3 is pressed down, the first limiting protrusion 33 contacts the inclined guide surface 25, causing the spring arm 20 to expand outward under the pressure of the first limiting protrusion 33. After the first limiting protrusion 33 passes the inclined guide surface 25 and the stop surface 23 of the spring arm 20, the spring arm 20 retracts inward to return to its initial position using its own elastic force. At this time, the stop surface 23 will engage with the upper end of the first limiting protrusion 33, thereby restricting the sleeve 3 from moving upward, that is, achieving locking and limiting the upward movement of the sleeve 3.

[0044] Optionally, the spring arm 20 is a cantilevered or sheet-like elastomer extending from the sidewall of the bushing 2. In the free state, the protruding portion on the inner side of the end of the spring arm 20 elastically retracts inward, wherein one side of the protruding portion is a stop surface 23 and the other side is an inclined guide surface 25.

[0045] Optionally, the inner wall of the housing 1 is provided with a clearance notch 1003 that cooperates with the spring arm 20. When the first limiting protrusion 33 squeezes the spring arm 20 to expand outward, the clearance notch 1003 provides space for the spring arm 20 to expand outward, so that the spring arm 20 has enough space to deform, thereby allowing the first limiting protrusion 33 to smoothly pass over the inclined guide surface 25 and the stop surface 23 of the spring arm 20 and be stuck at the lower end of the stop surface 23.

[0046] Optionally, the top of the bushing 2 is provided with an outwardly protruding first abutting ring 24, which abuts against the top surface of the housing 1; the top of the sleeve 3 is provided with an outwardly protruding second abutting ring 30, which abuts against the first abutting ring 24 to limit the downward movement of the sleeve 3 relative to the bushing 2.

[0047] Optionally, the inner wall of the bushing 2 is provided with a plurality of inwardly protruding guide ribs 22 extending axially, and the outer wall of the sleeve 3 is provided with a plurality of outwardly protruding guide grooves 32 extending axially. The guide ribs 22 and the guide grooves 32 cooperate to allow the sleeve 3 to slide within the bushing 2 and to restrict relative rotation between the sleeve 3 and the bushing 2. In this embodiment, the plurality of guide ribs 22 and the plurality of guide grooves 32 are arranged in a ring, and the plurality of guide grooves 32 are slidably connected within the plurality of guide grooves 32, so that the sleeve 3 can slide stably axially within the bushing 2, and there is no relative rotation between the two.

[0048] In some embodiments, the upper end of the sleeve 3 is provided with a receiving cavity 36 for accommodating the trigger member 5 and the trigger spring 4, and a contact surface 37 is provided on one side of the receiving cavity 36; the trigger member 5 includes a trigger sleeve 53, an extension arm 52 disposed on one side of the trigger sleeve 53, and a second protrusion 51 disposed on the outer edge of the bottom of the extension arm 52; one end of the trigger spring 4 abuts against the contact surface 37, and the other end abuts against the inside of the trigger sleeve 53. The trigger spring 4 is compressed between the contact surface 37 of the sleeve 3 and the trigger sleeve 53 of the trigger member 5, and always applies an upward elastic force to the trigger member 5 to ensure that the trigger member 5 can automatically bounce upward after it is disengaged from the sleeve 3.

[0049] In some embodiments, the outer wall of the sleeve 3 is provided with an opening 38 communicating with the receiving cavity 36, a second limiting protrusion 34 located at one end of the opening 38, and a sliding surface 39 located at the other end of the opening 38. The first limiting protrusion 33 is located at the end of the sliding surface 39 away from the opening 38, and the second limiting protrusion 34 is offset from the sliding surface 39 so that the extension arm 52 of the trigger 5 can extend from the opening 38 and abut against the sliding surface 39. The second protrusion 51 is restricted between the first limiting protrusion 33 and the second limiting protrusion 34 to limit the axial movement range of the trigger 5.

[0050] In this embodiment, after the trigger 5 is inserted into the receiving cavity 36 of the sleeve 3 from the upper end, the second limiting protrusion 34 is misaligned with the sliding surface 39. Specifically, the second limiting protrusion 34 is higher than the sliding surface 39, allowing the extension arm 52 of the trigger 5 to extend from the opening 38 and abut against the sliding surface 39. At this time, the extension arm 52 can slide on the sliding surface 39. Simultaneously with the extension arm 52 extending from the opening 38, the second protrusion 51 on the outer edge of the extension arm 52 forcibly crosses the second limiting protrusion 34 and is stuck between the first limiting protrusion 33 and the second limiting protrusion 34. Because one end of the second protrusion 51 can abut against the first limiting protrusion 33, the downward movement limit of the trigger 5 is restricted; because the other end of the second protrusion 51 can abut against the second limiting protrusion 34, the upward movement limit of the trigger 5 is restricted, allowing the second protrusion 51 to be rigidly stuck below the second limiting protrusion 34. Thus, the abutting engagement between the first limiting protrusion 33, the second limiting protrusion 34, and the second protrusion 51 can fix the trigger 5 and the trigger spring 4 within the receiving cavity 36 of the sleeve 3, and restrict the trigger 5 from moving upward and dislodging from the sleeve 3. Optionally, the second limiting protrusion 34 is a cantilever-shaped or sheet-shaped protrusion extending from the outer wall material of the sleeve 3.

[0051] In some embodiments, an elastic buckle 61 is provided on the outer wall of the push rod 6 near the bottom position, and a third limiting protrusion 35 is provided on the inner wall of the sleeve 3 on one side of the receiving cavity 36. The elastic buckle 61 can abut against the third limiting protrusion 35.

[0052] In this embodiment, the push rod 6 is inserted into the sleeve 3 from the top. The third limiting protrusion 35 first contacts the inclined side of the elastic buckle 61 and squeezes the elastic buckle 61 to retract inward. Thus, the elastic buckle 61 can smoothly pass over the third limiting protrusion 35 and be locked below the third limiting protrusion 35. After the elastic buckle 61 passes over the third limiting protrusion 35, the elastic buckle 61 expands outward using its own elastic force. When the push rod 6 is driven to retract upward, the upper end face of the elastic buckle 61 can cooperate and abut against the lower end face of the third limiting protrusion 35, so that the elastic buckle 61 is tightly locked below the third limiting protrusion 35, thereby preventing the push rod 6 from coming out of the sleeve 3.

[0053] Optionally, the upper part of the inclined side of the elastic buckle 61 is provided with an elastic damping boss 62 that mates with the inner wall of the sleeve 3. When the push rod 6 slides inside the sleeve 3, the elastic damping boss 62 will rub slightly against the inner wall of the sleeve 3, providing a damping feel during operation.

[0054] Optionally, the top of the push rod 6 is provided with a pressing end 64 for the user to press, and the outer wall of the push rod 6 is provided with an outwardly protruding third abutting ring 63 near the pressing end 64. The third abutting ring 63 can abut against the upper end surface of the trigger member 5 so that the push rod 6 can drive the trigger member 5 to move downward.

[0055] The working principle of the push rod 6 of the reusable pre-filling auxiliary injection device of the present invention, which actively rebounds to prevent locking failure, will be described in detail below.

[0056] Before use, the needle insertion depth can be set by rotating the adjusting ring 10. After setting the needle insertion depth, install the pre-filled injection device packaging material and remove the pen cap 7. In the initial state, the sleeve 3 is away from the bushing 2.

[0057] Before the injection begins, the user first presses down on the second abutment ring 30 of the sleeve 3, causing the sleeve 3 to move downward relative to the bushing 2. The first limiting protrusion 33 of the sleeve 3 contacts the inclined guide surface 25 of the bushing 2, causing the spring arm 20 to expand outward under the pressure of the first limiting protrusion 33. When the first limiting protrusion 33 passes the inclined guide surface 25 and the stop surface 23 of the spring arm 20, the spring arm 20 retracts inward to return to its initial position using its own elastic force. At this time, the stop surface 23 of the spring arm 20 will be inserted into the upper end of the first limiting protrusion 33, and the inclined guide surface 25 of the spring arm 20 will be inserted below the second protrusion 51 of the trigger 5. That is, the protruding part on the inner side of the end of the spring arm 20 is located on the sliding surface 39 and is inserted between the first limiting protrusion 33 and the end of the extension arm 52. The first abutting ring 24 abuts against the second abutting ring 30 to limit the downward movement of the sleeve 3 relative to the bushing 2. The first limiting protrusion 33 abuts against the stop surface 23 of the spring arm 20 to limit the upward movement of the sleeve 3 relative to the bushing 2. The sleeve 3 is locked by the spring arm 20 of the bushing 2. At the same time, as the sleeve 3 moves downward and presses against the needle retraction member 13, the needle retraction member 13 compresses the needle retraction spring 12 and causes the needle retraction spring 12 to store force.

[0058] Subsequently, the user holds the injection device, bringing the hidden needle 8 into contact with the skin and pressing down, while simultaneously pressing the pressing end 64 of the push rod 6 to inject. At the end of the injection stroke, the third abutment ring 63 of the push rod 6 contacts and presses against the upper end face of the trigger 5, causing the trigger 5 to move downward against the elastic force of the trigger spring 4. This action causes the second protrusion 51 at the bottom outer edge of the extended arm 52 of the trigger 5 to contact and slide downward against the inclined guide surface 25 of the spring arm 20, ultimately pushing the spring arm 20 outward and releasing the locking of the spring arm 20 of the bushing 2 to the sleeve 3. The inclined guide surface 25 increases the contact area between the spring arm 20 and the second protrusion 51, thereby enabling the second protrusion 51 to stably push the spring arm 20 outward.

[0059] At the instant the lock is released, the needle retraction component 13, under the elastic force of the needle retraction spring 12, pushes the sleeve 3 upward to retract, completing the automatic needle retraction. At this time, the injection is completed, and the user stops pressing the push rod 6. The pressing force acting on the trigger 5 disappears, and the compressed trigger spring 4 immediately extends, driving the trigger 5 to move upward relative to the sleeve 3. At the same time, the trigger 5 drives the push rod 6 to retract upward relative to the sleeve 3, thereby realizing the active rebound of the push rod 6. At this time, the second protrusion 51 of the trigger 5 moves away from the inclined guide surface 25 inside the spring arm 20 of the bushing 2, causing the spring arm 20 of the bushing 2 to retract inward and return to its initial state. This active rebound action allows the second protrusion 51 of the trigger 5 to be quickly and reliably withdrawn from the inclined guide surface 25 inside the spring arm 20, allowing the spring arm 20 to return to its initial state. This process effectively avoids the situation where the spring arm 20 is continuously stretched open for a long time due to the failure of the push rod 6 to rebound, thereby preventing the spring arm 20 from undergoing plastic deformation and failing, ensuring the long-term reliable elastic locking performance of the spring arm 20, and thus guaranteeing the service life and safety of the injection device.

[0060] Furthermore, since the second protrusion 51 of the trigger element 5 can abut against the second limiting protrusion 34 of the sleeve 3, the upper limit position of the trigger element 5 is restricted, so that the trigger element 5 is stuck below the second limiting protrusion 34, preventing the trigger element 5 from falling out of the sleeve 3. It should be noted that the trigger spring 4 only needs to drive the trigger element 5 to move upward relative to the sleeve 3 by a small distance. There is no specific limitation on this. It is only necessary to separate the second protrusion 51 of the trigger element 5 from the inclined guide surface 25 inside the spring arm 20 of the bushing 2.

[0061] like Figure 2 , Figures 12 to 17 As shown, in some embodiments, the inner wall of the lower end of the pen refill holder 11 is provided with an annular groove 111 and a plurality of protruding ribs 112 located on one side of the annular groove 111 and extending axially. The outer wall of the adjusting ring 10 is provided with an annular protrusion 103 and a plurality of positioning grooves 102 located on one side of the annular protrusion 103 and extending axially. The annular protrusion 103 is rotatably embedded in the annular groove 111 so that the adjusting ring 10 is rotatably connected to the pen refill holder 11 and will not detach. The plurality of positioning grooves 102 cooperate with the plurality of protruding ribs 112.

[0062] In some embodiments, the concealed needle 8 is slidably sleeved within the adjusting ring 10 and the pen refill holder 11. The concealed needle spring 9 is disposed between the concealed needle 8 and the lower end of the pen refill holder 11, providing the concealed needle 8 with a downward extension force to move it away from the pen refill holder 11. The outer wall of the upper end of the concealed needle 8 is provided with a limiting buckle 82, which can abut against the upper end surface of the adjusting ring 10 to limit the downward movement of the concealed needle 8 relative to the adjusting ring 10 and the pen refill holder 11, preventing the concealed needle 8 from disengaging from the adjusting ring 10 and the pen refill holder 11. The outer wall of the lower end of the concealed needle 8 is provided with symmetrically arranged limiting bosses 81, and the inner wall of the adjusting ring 10 is provided with a stepped surface 101 that changes in a stepped shape along the axial direction, which cooperates with the limiting bosses 81. When injected, the bottom end of the hidden needle 8 contacts the skin and retracts upward under force. Its limiting boss 81 will eventually stop against the stepped surface 101 of the adjusting ring 10, thereby limiting the continued retraction of the hidden needle 8 and determining the length of the needle tip exposed from the hidden needle 8, i.e. the needle insertion depth.

[0063] While existing pre-filled injection devices possess needle depth adjustment capabilities, their adjustment mechanisms are mostly continuous and stepless, making it difficult for users to accurately perceive the current setting and lacking clear auditory or tactile feedback. This not only makes it difficult to guarantee adjustment accuracy, potentially affecting drug absorption and patient comfort due to improper needle depth, but is also particularly inconvenient for inexperienced users or those with poor vision. The reusable pre-filled auxiliary injection device provided by this invention allows the user to change the circumferential alignment between the limiting boss 81 and the stepped surface 101 by rotating the adjustment ring 10. Since the stepped surface 101 has different axial heights at different angles, rotating the adjustment ring 10 changes the maximum retractable stroke of the concealed needle 8, thus exposing different lengths of the needle tip within the concealed needle 8, achieving needle depth adjustment. To improve the user experience and address the issue of unclear settings in existing technologies, the outer wall of the adjustment ring 10 is provided with multiple annularly distributed positioning grooves 102, and the pen refill holder 11 is correspondingly provided with protruding ribs 112. When the adjusting ring 10 is rotated, the protruding ribs 112 slide into or out of the positioning grooves 102 in sequence, producing a clear "click" sound and a tactile feedback, providing the user with good auditory and tactile feedback and achieving precise gear adjustment. At the same time, several positioning grooves 102 cooperate with several protruding ribs 112 to fix the rotation angle of the adjusting ring 10 corresponding to different needle depths when the adjusting ring 10 is rotated to adjust different needle depths, so that the adjusting ring 10 no longer rotates after the needle depth is determined, ensuring the accuracy of gear adjustment.

[0064] In some embodiments, the upper end of the refill holder 11 is threaded to the housing 1. This detachable design facilitates the installation and replacement of the reusable pre-filled auxiliary injection device. The refill holder 11 contains a needle retraction member 13, which pushes the injection device packaging material upwards during needle retraction, causing the sleeve 3 to move upwards as well, returning it to its initial state. A needle retraction spring 12 is compressed between the needle retraction member 13 and the refill holder 11, always providing an upward elastic force to the needle retraction member 13. The lower end of the needle retraction member 13 is provided with an elastic buckle 131, which hooks onto a fastening boss 113 inside the refill holder 11, preventing it from popping out.

[0065] Existing pre-filled injection devices do not provide reliable secondary protection for the needle tip after automatic needle retraction. The concealed needle element 8, which covers the needle tip, may not remain securely in the needle-protecting position due to incomplete internal mechanism reset, leading to the risk of accidental needle re-extendment and making it difficult to completely prevent needlestick injuries after injection. The reusable pre-filled auxiliary injection device provided by this invention addresses this issue. Before injection, when the sleeve 3 is pressed, it pushes the needle retraction element 13 downwards, compressing the needle retraction spring 12. At this time, the spring arm 20 locks the sleeve 3, and the needle retraction spring 12 stores force. After injection, the trigger 5 opens the spring arm 20 to release the lock, and the stored force of the needle retraction spring 12 is released instantaneously, pushing the needle retraction element 13 and the sleeve 3 upwards together, thus achieving automatic needle retraction, with the needle tip retracting into the concealed needle element 8. Combined with the active rebound push rod structure, this ensures complete mechanism reset and reliable needle retraction, solving the problem of insufficient secondary needle protection.

[0066] In summary, the reusable pre-filled auxiliary injection device provided by this invention, by setting a trigger spring 4 between the sleeve 3 and the trigger element 5, constructs an active rebound push rod structure, solving the technical problem that the locking spring arm 20 is continuously squeezed and thus fails due to the push rod 6 failing to reset, significantly improving the reliability of the device. Furthermore, by integrating a needle depth adjustment structure with auditory and tactile feedback, as well as a reliable automatic needle withdrawal and concealed needle structure, the problems of inconvenient needle depth adjustment and unreliable secondary needle protection are solved, making product operation more precise and safer, and providing an excellent user experience.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A reusable pre-filled auxiliary injection device, characterized in that, include: Shell (1); The bushing (2) is fixedly installed inside the housing (1). The bushing (2) is provided with a spring arm (20) and a stop surface (23). The spring arm (20) is a cantilevered elastic body extending from the side wall of the bushing (2) and an inclined guide surface (25) is provided on its inner side. A sleeve (3) is movably disposed inside the bushing (2). The outer wall of the sleeve (3) is provided with a first limiting protrusion (33) and an opening (38). The first limiting protrusion (33) can engage with the stop surface (23) to restrict the sleeve (3) from moving away from the bushing (2). When the sleeve (3) moves towards the end closer to the bushing (2), the first limiting protrusion (33) can slide along the inclined guide surface (25) and force the spring arm (20) to expand outward until it passes the stop surface (23) and is blocked by the stop surface (23). A trigger (5) is movably disposed within the sleeve (3). The trigger (5) includes a trigger sleeve (53) and an extension arm (52) extending outward from the end of the trigger sleeve (53). The trigger (5) has a second protrusion (51) that extends through the opening (38) to act on the spring arm (20). The extension arm (52) passes through the opening (38) and abuts against a sliding surface (39) on the outer wall of the sleeve (3). The outer wall of the sleeve (3) also has a second limiting protrusion (34) that is offset from the sliding surface (39). A push rod (6) is movably disposed inside the sleeve (3) and passes through the trigger (5). The push rod (6) is able to abut against the trigger (5) to push the trigger (5) to move closer to the bushing (2) when the push rod (6) moves closer to the bushing (2), and push the push rod (6) to move further away from the bushing (2) when the trigger (5) moves further away from the bushing (2). A trigger spring (4) is disposed between the sleeve (3) and the trigger member (5) to apply an elastic force to the trigger member (5) toward the end away from the bushing (2); During the injection process, the push rod (6) pushes the trigger (5) to move closer to the bushing (2), causing the second protrusion (51) to push the spring arm (20) outward elastically to release the engagement between the stop surface (23) and the first limiting protrusion (33); when the pushing force on the push rod (6) is removed, the trigger spring (4) drives the trigger (5) to move away from the bushing (2), and drives the push rod (6) to rebound away from the bushing (2), the second protrusion (51) disengages from the spring arm (20), and the spring arm (20) returns to its original shape.

2. The reusable pre-filled auxiliary injection device according to claim 1, characterized in that, The second protrusion (51) is disposed on the outer edge of the end of the extension arm (52); the sleeve (3) is provided with a receiving cavity (36), one end of the receiving cavity (36) is provided with an abutting surface (37), the trigger (5) is movably accommodated in the receiving cavity (36), one end of the trigger spring (4) abuts against the abutting surface (37), and the other end abuts against the trigger sleeve (53).

3. The reusable pre-filled auxiliary injection device according to claim 2, characterized in that, The second protrusion (51) is restricted between the first limiting protrusion (33) and the second limiting protrusion (34) to limit the axial movement range of the trigger (5).

4. The reusable pre-filled auxiliary injection device according to claim 1, characterized in that, The outer wall of the push rod (6) is also provided with an elastic buckle (61), and the inner wall of the sleeve (3) is provided with a third limiting protrusion (35). The elastic buckle (61) can pass over and engage below the third limiting protrusion (35) to prevent the push rod (6) from coming out of the sleeve (3). The side of the elastic buckle (61) is provided with an elastic damping boss (62), which is used to rub against the inner wall of the sleeve (3).

5. The reusable pre-filled auxiliary injection device according to claim 1, characterized in that, The bushing (2) has a first protrusion (21) on its outer periphery, and the inner wall of the housing (1) has an embedding groove (1001). The first protrusion (21) is embedded in the embedding groove (1001) to fix the bushing (2). The inner wall of the housing (1) has an inwardly protruding boss (1002), and the outer wall of the sleeve (3) has an abutment platform (31). The boss (1002) can abut against the abutment platform (31) to limit the axial displacement of the sleeve (3). The inner wall of the sleeve (2) is provided with a guide rib (22) extending along the axial direction, and the outer wall of the sleeve (3) is provided with a guide groove (32) extending along the axial direction. The guide rib (22) and the guide groove (32) are slidably engaged to restrict the relative rotation between the sleeve (3) and the bushing (2). The inner wall of the housing (1) is also provided with a clearance notch (1003). The clearance notch (1003) is located on the outside of the spring arm (20) and is used to provide space for the spring arm (20) to expand outward.

6. The reusable pre-filled auxiliary injection device according to claim 1, characterized in that, The top of the bushing (2) is provided with a first abutting ring (24), and the top of the sleeve (3) is provided with a second abutting ring (30). The second abutting ring (30) can abut against the first abutting ring (24) to limit the movement of the sleeve (3) towards the end of the bushing (2). The outer wall of the push rod (6) is provided with a third abutting ring (63), which is used to abut against the end face of the trigger (5).

7. The reusable pre-filled auxiliary injection device according to claim 1, characterized in that, It also includes a pen refill holder (11) detachably connected to the housing (1). The pen refill holder (11) is provided with a needle ejector (13) and a needle ejector spring (12). The needle ejector (13) is movably disposed in the pen refill holder (11) and can push the sleeve (3) to move away from the bushing (2). The needle ejector spring (12) is disposed between the needle ejector (13) and the pen refill holder (11) and is used to apply an elastic force toward the sleeve (3) to the needle ejector (13). The end of the needle ejector (13) is provided with an elastic buckle (131). The inner wall of the pen refill holder (11) is provided with a fastening boss (113). The elastic buckle (131) is hooked onto the fastening boss (113).

8. The reusable pre-filled auxiliary injection device according to claim 7, characterized in that, The pen refill holder (11) is also provided with an adjusting ring (10), a hidden needle (8) and a hidden needle spring (9); the adjusting ring (10) is rotatably connected to the pen refill holder (11), the hidden needle (8) is movably sleeved inside the adjusting ring (10), and the hidden needle spring (9) is disposed between the hidden needle (8) and the pen refill holder (11) to apply an elastic force away from the pen refill holder (11) to the hidden needle (8); the outer wall of the hidden needle (8) is provided with a limiting boss (81), and the inner wall of the adjusting ring (10) is provided with a stepped surface (101) that changes in a stepped shape along the axial direction. The limiting boss (81) can abut against the stepped surface (101) to limit the retraction stroke of the hidden needle (8).

9. The reusable pre-filled auxiliary injection device according to claim 8, characterized in that, The outer wall of the adjusting ring (10) is provided with a plurality of positioning grooves (102), and the inner wall of the pen refill holder (11) is provided with a plurality of protruding ribs (112). The positioning grooves (102) cooperate with the protruding ribs (112) to provide gear feedback when the adjusting ring (10) is rotated. The outer wall of the hidden needle (8) is provided with a limiting buckle (82). The limiting buckle (82) can abut against the end face of the adjusting ring (10) to limit the hidden needle (8) from the extreme position away from the pen refill holder (11).

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