First-aid injection pen structure capable of automatically hiding needle after injection

Abstract

The invention relates to the technical field of medical instrument manufacturing, in particular to a first-aid injection pen structure with a self-hidden needle after injection, which comprises an upper component, a lower component and a PFS component. The upper assembly limits the displacement of an excitation rod through an inner main body and an outer main body, and an excitation spring and an auxiliary spring respectively provide injection power and needle head hiding power; a starting shell of the lower assembly triggers injection under the jacking force of a human body; and the PFS assembly realizes liquid medicine release. The needle head is hidden in the starting shell initially, the starting shell moves upwards during excitation, the excitation rod pushes the piston to inject under the action of the excitation spring, and meanwhile the spring is assisted in storing energy. After injection is finished, the auxiliary spring releases potential energy to push the outer body and the starting shell to move downwards, and the needle is hidden again. The structure is linked with the upper assembly and the lower assembly through double-spring driving, full-process hiding of the injection needle is achieved, the advantages of being easy and convenient to operate, high in safety, stable and reliable in structure and the like are achieved, and the problem of exposure risk of an existing first-aid injection pen needle is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of medical device manufacturing, and in particular to a structure of an emergency injection pen in which the needle automatically retracts after injection. Background Art

[0002] In the field of medical first aid, emergency injection pens have become an important tool for dealing with sudden situations such as anaphylactic shock and hypoglycemic coma due to their portability and the characteristics of single - use to avoid cross - infection. However, after the existing single - use emergency injection pens complete injection, the needles are still in an exposed state, which is bound to pose a safety hazard. The exposed needles are extremely likely to injure the user again, and can also stab the staff during the medical waste treatment process, increasing the risk of blood - borne diseases such as hepatitis B and AIDS.

[0003] Regarding the current industry situation, although some emergency injection pens on the market are equipped with a needle - hiding function, there are many problems in actual application. For example, some devices use a complex mechanical linkage structure combining multi - stage gear transmission and connecting rods to achieve needle hiding. This design not only requires precise processing technology to ensure the fitting accuracy of components, but also involves multiple assembly processes, resulting in an extended production cycle and increased costs. Moreover, some emergency injection pens rely on manual operations such as rotation and pressing to trigger the hiding mechanism. In actual emergency treatment scenarios, users are often unable to accurately complete the hiding step due to factors such as unfamiliar operation, and even misoperations may cause the needle to hide in advance, delaying the treatment time. In addition, some hiding structures lack reliability. Taking the spring - driven hiding mechanism as an example, in the bump test simulating long - distance transportation, when the vibration frequency reaches 20 - 30 Hz, about 15% of the samples show accidental triggering of the spring and premature hiding of the needle. Therefore, it is urgent for technical personnel to solve the above problems. Summary of the Invention

[0004] The present invention provides a structure of an emergency injection pen in which the needle automatically retracts after injection, aiming to solve the problems of safety hazards caused by exposed needles, complex hiding structures, and low reliability existing in the existing emergency injection pens.

[0005] The present invention relates to a structure of an emergency injection pen in which the needle automatically retracts after injection, which includes:

[0006] An upper component, including a firing spring, a firing rod, a spring storage member, an inner main body, an outer main body, an auxiliary spring, and an upper housing that are sleeved in sequence from the inside out. Under the coordinated action of the inner main body and the outer main body, the axial displacement freedom of the firing rod is restricted. The firing spring is used to drive the firing rod, and it is received by the spring storage member and axially pressed against it. And under the coordinated action of the upper housing and the outer main body, the auxiliary spring stores elastic potential energy due to axial compression;

[0007] The lower assembly includes a starter shell and a lower shell. The starter shell is used to directly apply a push force to the outer body and is sleeved in the lower shell.

[0008] The PFS component is contained in the activation shell and releases the liquid medicine due to the push force directly from the trigger rod. The PFS component includes a syringe barrel, a piston and an injection needle.

[0009] In the initial state, the injection needle is hidden in the starting shell, and the axial displacement of the trigger rod is limited.

[0010] When the emergency injection pen is activated, the activation shell moves upward due to the top contact force of the human body, the relative position relationship between the inner body and the outer body changes, the axial displacement freedom of the activation rod is restored, and the activation rod drives the piston to inject under the push force from the activation spring. At the same time, the auxiliary spring is compressed to synchronously store elastic potential energy;

[0011] After the injection is completed and the starter shell is separated from the human body, the elastic potential energy stored in the auxiliary spring is released instantaneously to push the outer body downward, and the starter shell moves downward synchronously therewith, so that the injection needle is retracted.

[0012] As a further improvement of the technical solution disclosed in the present invention, the inner body is formed with a radial rebound blocking structure at a set distance near its top. The excitation rod is formed with a radial extension limit structure that cooperates with the radial rebound blocking structure at a set distance near its top. In the initial state, the radial rebound blocking structure and the radial extension limit structure are interlocked to limit the axial displacement movement freedom of the excitation rod.

[0013] As a further improvement of the technical solution disclosed in the present invention, an avoidance gap is formed on the outer body. In the initial state, the radial rebound blocking structure and the avoidance gap are misaligned with each other, and they are surrounded by the outer body, and their radial expansion freedom is constrained. The radial extension limiting structure is subject to the blocking force from the radial rebound blocking structure, and its axial displacement freedom is limited; when the radial rebound blocking structure and the avoidance gap are in a positive alignment state, the radial rebound blocking structure expands radially by itself due to the radial component force from the extension limiting structure, and the radial rebound blocking structure and the radial extension limiting structure are released from interlocking. After the injection is completed, the outer body performs a downward return movement due to the pushing force from the auxiliary spring until the top wall of the avoidance gap touches the expanded radial rebound blocking structure.

[0014] As a further improvement of the technical solution disclosed by the present invention, the radial outward extension limiting structure includes N built-in limiting protrusions. The built-in limiting protrusions are formed by continuously extending radially from the circumferential outer wall of the excitation rod. The radial spring-back blocking structure includes N radial spring-back arms. The radial spring-back arms are formed by processing the circumferential outer wall of the inner main body through slitting to remove materials, and near its free end, an external limiting protrusion adapted to the built-in limiting protrusion is formed. The avoidance notch is formed by processing the circumferential outer wall of the outer main body through material removal, and the number thereof is N; N≥1.

[0015] As a further improvement of the technical solution disclosed by the present invention, the upper component and the lower component are assembled into one body by an opposing insertion method. At a set distance near the insertion surface, an axial limiting step is formed in the inner cavity of the lower housing, and the maximum downward movement strokes of the inner main body and the outer main body are both limited.

[0016] As a further improvement of the technical solution disclosed by the present invention, the excitation rod is formed with a receiving cavity for vertically inserting the excitation spring. In the initial state, the upper and lower ends of the excitation spring respectively abut against the top wall of the spring receiving member and the bottom wall of the receiving cavity.

[0017] As a further improvement of the technical solution disclosed by the present invention, in the initial state, the auxiliary spring is elastically compressed between the upper housing and the outer main body. When the outer main body undergoes an axial displacement under the action of the pushing force of the starting shell, the compression amount of the auxiliary spring changes accordingly, and the change amount of the potential energy has a linear positive correlation with the axial displacement amount of the outer main body.

[0018] As a further improvement of the technical solution disclosed by the present invention, an upper radial outward extension anti-detachment structure and a lower radial spring-back damping structure are axially spaced along the starting shell. Upper and lower blocking steps are spaced on the inner side wall of the lower housing. In the initial state, the upper radial outward extension anti-detachment structure abuts against the upper blocking step, and the lower radial spring-back damping structure is in critical contact with the lower blocking step. When the first-aid injection pen is activated, during the process of the starting shell moving upward, the lower radial spring-back damping structure abuts against the lower blocking step, and the lower radial spring-back damping structure radially elastically contracts by itself due to the reaction force from the lower blocking step. At the same time, the upper radial outward extension anti-detachment structure moves away from the upper blocking step. As the upward movement process of the starting shell continues, the lower radial spring-back damping structure passes over the upper blocking step, and it radially expands by itself due to the loss of physical constraint; after the injection is completed, the starting shell moves downward under the action of the pushing force from the outer main body until the expanded lower radial spring-back damping structure abuts against the upper blocking step.

[0019] As a further improvement of the technical solution disclosed in the present invention, the upper radial extension anti-slip structure includes M upper radial extension anti-slip protrusions. The upper radial extension anti-slip protrusions are formed by continuing to radially extend from the circumferential outer wall of the starter shell. The lower radial rebound damping structure includes M radial rebound damping hook arms. The radial rebound damping hook arms are formed by the circumferential outer wall of the starter shell through cutting and removing material; M≥1.

[0020] As a further improvement of the technical solution disclosed in the present invention, when the injection needle is hidden, the starter shell is flush with the bottom end of the lower shell, or the starter shell is retracted into the lower shell by 0.5 to 1.0 mm.

[0021] In practical applications, the first aid injection pen structure disclosed in the present invention, in which the needle automatically retracts after injection, can achieve at least the following beneficial technical effects, specifically:

[0022] 1) Through the innovative design of the excitation spring + auxiliary spring drive and the linkage mechanism of the upper and lower components, the needle is hidden and protected throughout the entire process. In the initial state, the injection needle is hidden in the starter shell, eliminating the risk of accidental puncture when not in use; after the injection is completed, the auxiliary spring quickly releases the accumulated potential energy, drives the outer body and the starter shell to move downward in coordination, and retracts the injection needle into the starter shell, effectively avoiding the risk of medical staff or users being punctured by the needle during the handling process, and significantly improving the safety of use;

[0023] 2) The human body top-touch trigger design greatly simplifies the operation process. The user only needs to press the injection pen against the injection site, and the trigger shell can move upward under the action of the top-touch force, triggering the relative displacement of the inner body and the outer body, releasing the axial movement freedom of the trigger rod, so that the trigger spring quickly pushes the piston to complete the injection of the liquid medicine, and simultaneously compresses the auxiliary spring to store energy. The entire operation process does not require complicated steps, which meets the needs of every second in emergency scenarios. Even non-professionals can quickly get started;

[0024] 3) The double limit design of the inner body and the outer body for the trigger rod, combined with the auxiliary spring and the energy storage structure of the upper shell, ensures that the emergency injection pen remains highly stable when idle, and prevents the trigger rod from being accidentally triggered;

[0025] 4) The overall structural design is sophisticated. Through the efficient integration and coordinated operation of upper and lower components, complex transmission components and additional control systems are eliminated, which significantly reduces the difficulty and cost of the production process. It is also easy to assemble quickly and adapts to the needs of large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0027] Figure 1 It is a three-dimensional schematic diagram of the structure of the first-aid injection pen in which the needle automatically retracts after injection disclosed by the present invention.

[0028] Figure 2 is Figure 1 the side view of.

[0029] Figure 3 is Figure 2 the A-A sectional view of.

[0030] Figure 4 is Figure 3 the enlarged view of the I part of.

[0031] Figure 5 is Figure 3 the enlarged view of the II part of.

[0032] Figure 6 is Figure 3 the enlarged view of the III part of.

[0033] Figure 7 is Figure 4 the enlarged view of the IV part of.

[0034] Figure 8 is Figure 4 the enlarged view of the V part of.

[0035] Figure 9 is Figure 5 the enlarged view of the VI part of.

[0036] Figure 10 It is a three-dimensional schematic diagram of the actuating rod in the structure of the first-aid injection pen in which the needle automatically retracts after injection disclosed by the present invention.

[0037] Figure 11 It is a three-dimensional schematic diagram of the spring storage member in the structure of the first-aid injection pen in which the needle automatically retracts after injection disclosed by the present invention.

[0038] Figure 12 It is a three-dimensional schematic diagram of the inner main body in the structure of the first-aid injection pen in which the needle automatically retracts after injection disclosed by the present invention.

[0039] Figure 13 is Figure 12 the side view of.

[0040] Figure 14 is Figure 13 the B-B sectional view.

[0041] Figure 15 is the three-dimensional schematic diagram of the outer main body in the emergency injection pen structure where the needle automatically retracts after injection disclosed by the present invention.

[0042] Figure 16 is the three-dimensional schematic diagram of the upper shell in the emergency injection pen structure where the needle automatically retracts after injection disclosed by the present invention.

[0043] Figure 17 is the three-dimensional schematic diagram of the starting shell in the emergency injection pen structure where the needle automatically retracts after injection disclosed by the present invention.

[0044] Figure 18 is the three-dimensional schematic diagram of the lower shell in the emergency injection pen structure where the needle automatically retracts after injection disclosed by the present invention.

[0045] Figure 19 is Figure 18 the side view.

[0046] Figure 20 is Figure 19 the C-C sectional view.

[0047] 1 - upper component; 11 - firing spring; 12 - firing rod; 121 - radially extending limiting structure; 1211 - built-in limiting protrusion; 122 - accommodating cavity; 13 - spring receiving member; 14 - inner main body; 141 - radially resilient blocking structure; 1411 - radially resilient arm; 14111 - externally disposed limiting protrusion; 15 - outer main body; 151 - avoiding notch; 16 - auxiliary spring; 17 - upper shell; 2 - lower component; 21 - starting shell; 211 - upper radially extending anti-disengagement structure; 2111 - upper radially extending anti-disengagement protrusion; 212 - lower radially resilient damping structure; 2121 - radially resilient damping hook arm; 22 - lower shell; 221 - axial limiting step; 222 - upper blocking step; 223 - lower blocking step; 3 - PFS component; 31 - syringe barrel; 32 - piston; 33 - injection needle; 4 - safety locking soft cap. Detailed implementation manners

[0048] In the description of the present invention, it should be understood that the positional or positional relationships indicated by the terms "left", "right", "front", "rear", "upper", "lower", etc. are based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and thus should not be construed as a limitation to the present invention.

[0049] The emergency injection pen is a portable automatic injection device designed for emergency treatment scenarios. It is used to quickly and accurately inject emergency drugs (such as adrenaline, insulin, etc.) into the patient's body. Its core function is to complete puncture and drug delivery in a short time.

[0050] The structure of the emergency injection pen with the needle automatically retracting after injection disclosed by the present invention is further described in detail below in conjunction with specific embodiments. Figures 1 - 6 As shown in the figure, it is mainly composed of several parts such as an upper component 1, a lower component 2, a PFS component 3 and a safety locking soft cap 4. The upper component and the lower component are assembled into one by opposite plugging. The PFS component 3 is accommodated in the lower component 2. The safety locking soft cap 4 is pre-assembled at the lower end of the lower component 2 to tightly cover the PFS component 3 to form a physical isolation barrier, which effectively prevents the PFS component 3 from being contaminated or accidentally touched when not in use. When an injection operation is required, the user only needs to remove the safety locking soft cap 4 to release the protection state.

[0051] like Figure 4 As shown in the figure, the upper component 1 includes an excitation spring 11, an excitation rod 12, a spring receiving member 13, an inner body 14, an outer body 15, an auxiliary spring 16 and an upper shell 17, and is assembled in sequence from the inside to the outside. Under the synergistic effect of the inner body 14 and the outer body 15, the axial displacement freedom of the excitation rod 12 is limited. The excitation spring 11 is used to drive the excitation rod 12.

[0052] like Figure 16 As shown in , the upper shell 17 is in an outer layer wrapping form, and is coaxially mounted with the outer body 15 , the inner body 14 and other components along the axial direction, and its inner wall is tightly matched with the outer body 15 .

[0053] like Figure 10 As shown in FIG. 1 , the trigger rod 12 is formed with a receiving cavity 122 for vertically inserting the trigger spring 11 .

[0054] like Figure 11 As shown in FIG. 1 , the spring receiving member 13 for receiving the spring receiving member 13 is an integral injection molded part.

[0055] In the initial state, the upper and lower ends of the trigger spring 11 respectively contact the top wall of the spring receiving member 13 and the bottom wall of the accommodating chamber 122. Under the coordinated action of the upper shell 17 and the outer body 15, the auxiliary spring 16 stores elastic potential energy due to axial compression. The double limit design of the inner body 14 and the outer body 15 on the trigger rod 12, combined with the energy storage structure of the auxiliary spring 16 and the upper shell 17, ensures that the emergency injection pen remains highly stable when idle, and prevents the trigger rod from being accidentally triggered.

[0056] like Figure 5As shown in , the lower assembly 2 includes a starter shell 21 and a lower shell 22. The starter shell 21 is used to directly apply a push force to the outer body 15, and is sleeved in the lower shell 22.

[0057] like Figure 6 As shown in FIG. 1 , the PFS assembly 3 is received by the starter housing 21 and releases the liquid medicine due to the push force directly from the trigger rod 12. The PFS assembly 3 includes a syringe barrel 31, a piston 32 and an injection needle 33. The safety locking cap 4 is assembled based on the lower housing 22.

[0058] Initial protection state: When not in use, the safety locking cap 4 is tightly fitted on the lower end of the lower shell 22, completely covering the PFS assembly 3, thereby forming a reliable physical isolation to protect the injection needle 33 from contamination and accidental touch. At this time, the inner body 14 and the outer body 15 work together to limit the axial displacement freedom of the trigger rod 12; at this time, the trigger spring 11 is compressed and stored in the spring storage part 13, accumulating elastic potential energy to provide power for the subsequent injection triggering action; the auxiliary spring 16 is in a compressed state under the joint extrusion of the upper shell 17 and the outer body 15, storing elastic potential energy, and providing power for the subsequent insertion of the injection needle 33.

[0059] Trigger injection process: When the user is ready to inject, first remove the safety locking soft cap 4, and then press the emergency injection pen against the injection site to apply a human body top contact force. The top contact force acts on the starter shell 21, causing it to move upward along the lower shell 22. During the upward movement of the starter shell 21, a push force is applied to the outer body 15, causing the relative positions of the inner body 14 and the outer body 15 to change, so as to release the restriction on the axial displacement freedom of the trigger rod 12. At this time, the trigger spring 11 quickly releases its elastic potential energy, driving the trigger rod 12 to move axially, and the trigger rod 12 pushes the piston 32 to move axially, so that the liquid in the syringe barrel 31 is accurately injected into the human body through the injection needle 33. At the same time, the outer body 15 moves upward synchronously due to the push force from the starter shell 21, further compressing the auxiliary spring 16 to store more elastic potential energy.

[0060] After injection, the injection needle is retracted: After the injection of the liquid medicine is completed, when the starter shell 21 is no longer subjected to the top contact force due to the separation from the human body, the auxiliary spring 16 in the compressed state instantly releases the stored elastic potential energy. The auxiliary spring 16 pushes the outer body 15 to move downward. Due to the linkage relationship between the starter shell 21 and the outer body 15, the starter shell 21 moves downward synchronously until the injection needle 33 is retracted into the starter shell 21, and the safety protection state is re-formed.

[0061] In the above technical solution, through the innovative design of the excitation spring 11 + auxiliary spring 16 to drive the linkage mechanism between the upper component 1 and the lower component 2, the full-process hidden protection of the injection needle 33 is realized. In the initial state, the injection needle 33 is hidden in the starting shell 21, eliminating the risk of accidental stabbing in the unused state; after the injection is completed, the auxiliary spring 16 quickly releases the accumulated potential energy, driving the outer main body 15 and the starting shell 21 to move downward in coordination, and taking the injection needle 33 into the starting shell 21 again, effectively avoiding the risk of being stabbed by the injection needle 33 during the handling process by medical staff or users, and significantly improving the use safety.

[0062] Furthermore, as can be clearly known from the above description, the emergency injection pen adopts a human body touch-trigger design, and the operation process is extremely simplified. The user only needs to press the injection pen against the injection site, and the starting shell 21 can move upward under the action of the touch force, triggering the relative displacement between the inner main body 14 and the outer main body 15, releasing the axial movement freedom of the excitation rod 12, so that the excitation spring 11 quickly pushes the piston 32 to complete the injection of the liquid medicine, and simultaneously compresses the auxiliary spring 16 to store elastic potential energy. The entire operation process does not require complex steps, meeting the needs of racing against time in the first aid scenario, and even non-professionals can quickly get started.

[0063] Here, it should also be noted that the overall structure of the first aid injection pen is exquisitely designed. Through the efficient integration and coordinated operation of the upper component 1 and the lower component 2, complex transmission components and additional control systems are eliminated, significantly reducing the production process difficulty and cost, and being convenient for rapid assembly, adapting to the needs of large-scale industrial production.

[0064] Figures 12 - 14 As shown in, at a set distance near its top, the inner main body 14 is formed with a radial rebound blocking structure 141. As Figure 10 As shown in, at a set distance near its top, the excitation rod 12 is formed with a radial extension limiting structure 121 that cooperates with the radial rebound blocking structure 141. As Figure 15As shown, an avoidance notch 151 is formed on the outer body 15. In the initial state, the radial springback blocking structure 141 and the avoidance notch 151 are misaligned with each other, and the radial springback blocking structure 141 is surrounded by the outer body 15, and its radial expansion degree of freedom is constrained. The axial displacement degree of freedom of the radially extending limit structure 121 is restricted due to the blocking force from the radial springback blocking structure 141. In the state where the radial springback blocking structure 141 and the avoidance notch 151 are in alignment, the radial springback blocking structure 141 expands radially by itself due to the radial component force from the extending limit structure 121, and the radial springback blocking structure 141 and the radially extending limit structure 121 are unlocked from each other. After injection, the outer body 15 moves downward and returns to its original position due to the pushing force from the auxiliary spring 16 until the top wall of the avoidance notch 151 touches the expanded radial springback blocking structure 141. Through the design and cooperation of the specific structures on the inner body 14, the activation rod 12, and the outer body 15, while ensuring the structural stability of the emergency injection pen, reliable locking of the movement of the activation rod 12 and precise control of the movement are achieved, significantly improving the safety and reliability of use.

[0065] As a further refinement of the above technical solution, the radially extending limit structure 121 is composed of two internally placed limit protrusions 1211 distributed in an axially symmetric state. The internally placed limit protrusions 1211 are formed by further radially extending from the circumferential outer wall of the activation rod 12. The radial springback blocking structure 141 is composed of two radially springback arms 1411 distributed in an axially symmetric state. The radially springback arms 1411 are formed by cutting and removing materials from the circumferential outer wall of the inner body 14, and near its free end, an externally placed limit protrusion 14111 adapted to the above internally placed limit protrusion 1211 is formed. The avoidance notch 151 is formed by removing materials from the circumferential outer wall of the outer body 15, and the number thereof is 2, and they are also distributed in an axially symmetric state. As Figure 7 As shown, in the initial state, the safety locking soft cap 4 covers the PFS assembly 3. The radial springback blocking structure 141 and the avoidance notch 151 are misaligned, and the externally placed limit protrusion 14111 and the internally placed limit protrusion 1211 are locked with each other to restrict the movement of the activation rod 12. At the same time, the activation spring 11 and the auxiliary spring 16 store energy. During injection, the safety locking soft cap 4 is removed, and the human body's pushing force causes the activation shell 21 to move upward and push the outer body 15 until the radial springback blocking structure 141 and the avoidance notch 151 are in alignment. The internally placed limit protrusion 1211 pushes the radially springback arm 1411 to expand radially through the externally placed limit protrusion 14111, and the locking between the internally placed limit protrusion 1211 and the externally placed limit protrusion 14111 is released. The activation spring 11 drives the activation rod 12 to push the piston 32 to complete the injection, and the auxiliary spring 16 stores elastic potential energy synchronously. After injection, the activation shell 21 is separated from the human body, and the auxiliary spring 16 releases energy to push the outer body 15 downward, causing the injection needle 33 to retract into the activation shell 21 to avoid the risk of needle exposure.

[0066] In the above technical solution, two axially symmetrically distributed built-in limit protrusions 1211 cooperate with the radial rebound arms 1411 to construct a stable and balanced mechanical constraint system. In the initial state, it can effectively limit the axial displacement movement of the firing rod 12 and avoid the occurrence of accidental unlocking caused by uneven force; the symmetrically distributed avoidance notches 151 cooperate with the rebound arms 1411 to ensure that the firing rod 12 can stably release its degree of freedom axially when triggering an injection, so as to prevent the occurrence of offset or jamming problems.

[0067] For the purpose of ensuring the positional accuracy among the outer main body 15, the starting shell 21 and the PFS assembly 3, so that the injection needle 33 can accurately retract into the starting shell 21, as a further optimization of the above technical solution, as Figure 8 shown in, a distance is set near the mating surface, and an axial limit step 221 is formed in the inner cavity of the lower shell 22, and the maximum downward travel of the inner main body 14 and the outer main body 15 is limited.

[0068] As Figure 17 shown in, an upper radial outward extension anti-disengagement structure 211 and a lower radial rebound damping structure 212 are axially spaced along the starting shell 21. The upper radial outward extension anti-disengagement structure 211 is composed of 2 axially symmetrically distributed upper radial outward extension anti-disengagement protrusions 2111. The upper radial outward extension anti-disengagement protrusions 2111 are formed by continuously radially extending from the circumferential outer wall of the starting shell 21. The lower radial rebound damping structure 212 is composed of 2 axially symmetrically distributed radial rebound damping hook arms 2121. The radial rebound damping hook arms 2121 are formed by removing materials through slitting from the circumferential outer wall of the starting shell 21. As Figures 18 - 20 shown in, upper blocking steps 222 and lower blocking steps 223 are spaced on the inner side wall of the lower shell 22. As Figure 5 、 Figure 9As shown in the figure, in the initial state, the upper radially extending anti - detachment protrusion 2111 abuts against the upper stop step 222, while the radially resilient damping hook arm 2121 is in critical contact with the lower stop step 223. When the emergency injection pen is activated, during the process of the activation shell 21 moving upward, the radially resilient damping hook arm 2121 abuts against the lower stop step 223, and the radially resilient damping hook arm 2121 radially elastically contracts on its own due to the reaction force from the lower stop step 223. At the same time, the upper radially extending anti - detachment protrusion 2111 gradually moves away from the upper stop step 222. As the upward movement process of the activation shell 21 continues, the radially resilient damping hook arm 2121 is able to cross over the upper stop step 222 and radially expands on its own because it loses physical restraint. After injection, the activation shell 21 moves downward under the action of the pushing force from the outer main body 15 until the expanded radially resilient damping hook arm 2121 abuts against the upper stop step 222. During the process of the auxiliary spring 16 pushing the activation shell 21 downward after injection, the expanded radially resilient damping hook arm 2121 abuts against the upper stop step 222, thus accurately defining the limit downward movement stroke of the activation shell 21. Through the dynamic cooperation among the upper radially extending anti - detachment protrusion 2111, the radially resilient damping hook arm 2121, the upper stop step 222 and the lower stop step 223, accurate limit and reliable guidance for the whole movement process of the activation shell 21 are achieved.

[0069] Finally, it should also be noted that when the injection needle 33 retracts, the activation shell 21 is flush with the bottom end of the lower shell 22, or the activation shell 21 retracts into the lower shell 22 by 0.5 - 1.0 mm. In this way, on the one hand, it ensures that the injection needle 33 is completely retracted into the activation shell 21, and enhances the protection of the injection needle 33 through the physical barrier of the lower shell 22, which is conducive to eliminating the risk of the injection needle 33 being exposed due to the incomplete downward movement of the activation shell 21.

[0070] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An emergency injection pen structure in which the needle automatically retracts after injection, characterized in that Comprising: An upper component, including an excitation spring, an excitation rod, a spring housing member, an inner main body, an outer main body, an auxiliary spring, and an upper housing that are sleeved in sequence from the inside out; under the combined action of the inner main body and the outer main body, the axial displacement freedom of the excitation rod is restricted; the excitation spring is used to drive the excitation rod, and it is housed by the spring housing member and axially pressed against it; and under the combined action of the upper housing and the outer main body, the auxiliary spring stores elastic potential energy due to axial compression. A lower component, including a starting shell and a lower housing; the starting shell is used to directly apply a pushing force to the outer main body, and it is sleeved in the lower housing. A PFS component, housed by the starting shell, and it releases the liquid medicine due to the direct pushing force from the excitation rod; the PFS component includes a syringe barrel, a piston, and a syringe needle. In the initial state, the syringe needle is hidden inside the starting shell, and the axial displacement of the excitation rod is restricted. When the emergency injection pen is activated, the starting shell moves upward due to the human touch force, the relative position relationship between the inner main body and the outer main body changes, the axial displacement freedom of the excitation rod is restored, and the excitation rod drives the piston for injection under the pushing force from the excitation spring. At the same time, the auxiliary spring stores elastic potential energy synchronously due to being compressed. After the injection is completed and the starting shell is separated from the human body, the elastic potential energy stored in the auxiliary spring is instantaneously released to push the outer main body downward, and the starting shell moves downward synchronously, causing the syringe needle to be hidden again.

2. The structure of the first-aid injection pen with the needle automatically retracting after injection according to claim 1, characterized in that, At a set distance near its top end, the inner main body is formed with a radially resilient blocking structure; at a set distance near its top end, the excitation rod is formed with a radially extending limiting structure that cooperates with the radially resilient blocking structure; in the initial state, the radially resilient blocking structure and the radially extending limiting structure are interlocked to restrict the axial displacement movement freedom of the excitation rod.

3. The structure of the first-aid injection pen in which the needle automatically retracts after injection according to claim 2, characterized in that, An avoidance notch is formed on the outer main body; in the initial state, the radially resilient blocking structure and the avoidance notch are misaligned with each other, and it is surrounded by the outer main body, and its radial expansion freedom is restricted. The axial displacement freedom of the radially extending limiting structure is restricted due to the blocking force from the radially resilient blocking structure; in the state where the radially resilient blocking structure and the avoidance notch are in alignment, the radially resilient blocking structure radially expands by itself due to the radial component force from the extending limiting structure, and the radially resilient blocking structure and the radially extending limiting structure are unlocked; after the injection is completed, the outer main body moves downward for return movement due to the pushing force from the auxiliary spring until the top wall of the avoidance notch touches the radially expanded radially resilient blocking structure.

4. The structure of the first-aid injection pen in which the needle automatically retracts after injection according to claim 3, characterized in that, The radially outward extension limiting structure includes N built-in limiting protrusions; the built-in limiting protrusions are formed by continuously extending radially from the circumferential outer wall of the firing rod; the radially resilient blocking structure includes N radially resilient arms; the radially resilient arms are formed by removing materials through slitting from the circumferential outer wall of the inner main body, and near its free end, an external limiting protrusion adapted to the built-in limiting protrusion is formed; the avoidance notch is formed by removing materials from the circumferential outer wall of the outer main body, and the number thereof is N; N≥1.

5. The structure of the first-aid injection pen with the needle automatically retracting after injection according to claim 3, characterized in that, The upper component and the lower component are assembled into one body in an opposing insertion manner; at a set distance near the insertion surface, an axial limiting step is formed in the inner cavity of the lower housing, and the maximum downward travel of the inner main body and the outer main body is limited.

6. The structure of the emergency injection pen with the needle automatically retracting after injection according to claim 1, wherein The firing rod is formed with a receiving cavity for vertically inserting the firing spring; in the initial state, the upper and lower ends of the firing spring respectively abut against the top wall of the spring receiving member and the bottom wall of the receiving cavity.

7. The structure of the emergency injection pen with the needle automatically retracting after injection according to claim 1, wherein, In the initial state, the auxiliary spring is elastically compressed between the upper housing and the outer main body; when the outer main body undergoes an axial displacement under the action of the pushing force of the starting shell, the compression amount of the auxiliary spring changes accordingly, and the change amount of potential energy has a linear positive correlation with the axial displacement amount of the outer main body.

8. The structure of the first-aid injection pen in which the needle automatically retracts after injection according to any one of claims 1-7, characterized in that, An upper radially outward extension anti-disengagement structure and a lower radially resilient damping structure are axially spaced along the starting shell; upper and lower blocking steps are spaced on the inner side wall of the lower housing; in the initial state, the upper radially outward extension anti-disengagement structure abuts against the upper blocking step, and the lower radially resilient damping structure is in critical contact with the lower blocking step; when the emergency injection pen is fired, during the process of the starting shell moving upward, the lower radially resilient damping structure abuts against the lower blocking step, and the lower radially resilient damping structure radially elastically contracts itself due to the reaction force from the lower blocking step. At the same time, the upper radially outward extension anti-disengagement structure moves away from the upper blocking step. As the upward movement of the starting shell continues, the lower radially resilient damping structure crosses the upper blocking step and radially expands itself due to the loss of physical constraint; after the injection is completed, the starting shell moves downward under the action of the pushing force from the outer main body until the expanded lower radially resilient damping structure abuts against the upper blocking step.

9. The structure of the first-aid injection pen with the needle automatically retracting after injection according to claim 8, characterized in that, The upper radially outward extension anti-disengagement structure includes M upper radially outward extension anti-disengagement protrusions; the upper radially outward extension anti-disengagement protrusions are formed by continuously extending radially from the circumferential outer wall of the starting shell; the lower radially resilient damping structure includes M radially resilient damping hook arms; the radially resilient damping hook arms are formed by removing materials through slitting from the circumferential outer wall of the starting shell; M≥1.

10. The structure of the first-aid injection pen with the needle automatically retracting after injection according to claim 8, wherein After the injection needle retracts, the starting shell is flush with the bottom end of the lower housing, or the starting shell retracts into the lower housing by 0.5 - 1.0 mm.

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