Injection spring locking excitation mechanism for automatic injection pen

Abstract

The utility model provides an injection spring locking excitation mechanism for an automatic injection pen, which comprises a pen shell, a push rod, an injection spring, a safety pin, a retraction sleeve, an injection spring support and the like, a special mechanism is designed aiming at the functions of the injection spring and the requirements of storage and transportation locking, unlocking and releasing, and locking and safety insurance are realized through the safety pin. During unlocking, the excitation pin column is separated from the safety pin containing cavity in the top of the push rod with small force, and then the fixed arm of the push rod is inwards contracted and separated from the top of the retraction sleeve under the elastic force action of the excitation spring, so that the push rod is in a free state of downward movement, and a piston in the injector can be pushed for medicine pushing injection.

Description

Technical Field

[0001] This utility model relates to an injection spring in an automatic injection pen that enables the injection function, and a mechanism for locking and activating it, belonging to the field of medical syringes. Background Technology

[0002] An automatic injection pen is a syringe product that is convenient for patients or the general public to operate. During production, the manufacturer pre-fills the syringe with medication, forming a pre-filled syringe (PFS, also known as a drug-loaded syringe). Figure 4 As shown; the PFS is then installed into an automatic injection device to form an automatic injection pen for transportation and sale. After receiving the automatic injection pen, the consumer uses it as needed, removing the pen cap and pressing it onto the patient's injection site to initiate the injection. Finally, the pen is removed, completing the automatic injection of the medication. Compared to traditional syringes, it eliminates the need for drawing, inserting, and pushing medication with a disposable syringe, making operation more convenient and ensuring a guaranteed dosage without deviations due to operator inexperience.

[0003] Currently, there are many automated injection pens for PFS (Prophylactic Assistive Device) on the market with disposable, fully automated injection functions, which makes it convenient for patients to use. However, due to regulatory requirements, the needle must be covered before and after use to prevent needle injury. Therefore, it generally requires two sets of spring systems to perform the functions of pushing the drug into the injection and removing the needle for covering. As a result, the structure of automated injection pens is generally quite complex, which makes the assembly of automated injection devices with PFS also more complicated.

[0004] The injection spring in the PFS automatic injection pen is used to push the drug into the injection. Therefore, it is relatively long and has a large elastic force. It needs to be carefully compressed and locked to ensure that it will not be accidentally activated during storage and transportation. When activation is required, it is hoped that activation can be performed smoothly with a small force, that is, at the end of the injection, without the operator having to apply more force, so as to carry out the drug injection.

[0005] In existing automatic injection pen designs, due to safety considerations, the mechanism surrounding the injection spring is often quite complex, with multiple internal safety mechanisms to ensure safe storage and transportation. This results in the operator needing to apply more force to unlock and activate the pen.

[0006] Therefore, to address the aforementioned shortcomings, it is necessary to design an injection spring locking and actuation mechanism for automatic injection pens, which can both meet the safety and security requirements during storage and transportation, reduce the actuation force requirements, and facilitate operation. Utility Model Content

[0007] The purpose of this invention is to provide an injection spring locking and triggering mechanism for an automatic injection pen. A specialized mechanism is designed to address the functions of the injection spring and the requirements for locking, unlocking, and releasing during storage and transportation. A safety pin enables locking and safety protection. Unlocking requires only a small force to disengage the triggering pin from the safety pin housing at the top of the push rod. Then, the elastic force of the triggering spring retracts and disengages the fixed arm of the push rod from the top of the retractable sleeve, allowing the push rod to move freely downwards and push the piston inside the syringe to inject the medication.

[0008] To achieve the above-mentioned utility model objectives, this utility model provides an injection spring locking and actuation mechanism for an automatic injection pen, including a pen shell, a push rod, an injection spring, a safety pin, a retractable sleeve, and an injection spring support.

[0009] The injection spring support is fixed inside the retractable sleeve; the retractable sleeve is temporarily fixed in position (in the injection spring locked state and during the drug injection stage after unfolding) and installed inside the pen shell;

[0010] The safety pin is equipped with a flexible trigger claw, and the trigger claw is equipped with a trigger hook, which can be detachably snapped into the pen case; the top of the safety pin is equipped with a protruding trigger pin post; after the trigger hook of the safety pin is detached from the pen case, the safety pin can move along the axis of the pen case.

[0011] The plunger is connected at the bottom to the piston of the syringe; the plunger contains an injection spring.

[0012] The top of the push rod is provided with a flexible fixing arm; the top of the fixing arm protrudes outward to form a fixing claw, and a retraction guide is formed below the end of the fixing claw; a safety pin receiving cavity is formed on the inner side of the top of the fixing arm; the excitation pin is matched with the safety pin receiving cavity;

[0013] The top of the injection spring rests against the injection spring support, and the top and bottom of the injection spring rest against the push rod.

[0014] When the safety pin's activation hook engages with the pen casing, the safety pin's activation pin is located within the safety pin's receiving cavity, the fixing arm at the top of the push rod cannot move inward, and the fixing claw hook is at the top of the retractable sleeve; when the injection spring bracket and the push rod are simultaneously fixed on the retractable sleeve, the injection spring is compressed.

[0015] When the safety pin's trigger hook moves off the pen casing, the safety pin moves along the pen casing, causing the trigger pin to disengage from the safety pin receiving cavity. The fixed arm at the top of the push rod can then move inward. The injection spring pushes the push rod downward, and the contraction guide converts the downward force of the fixed arm into an inward contraction deformation force. The fixed claw slides along the top of the sleeve through the contraction guide. Once the fixed claw is completely disengaged from the top plane of the sleeve, it enters the interior of the sleeve, the injection spring is fully unlocked, and the injection spring unfolds, pushing the push rod downward.

[0016] As a further improvement of this utility model, an excitation sleeve is provided inside the pen shell, and the excitation sleeve can move along the axis of the pen shell; an excitation head is provided at the top of the excitation sleeve.

[0017] The bottom of the safety pin extends downward to form an elastic trigger claw, and the bottom of the trigger claw protrudes outward to form an trigger hook; the lower part of the trigger hook is provided with a trigger guide.

[0018] The trigger head is matched with the trigger guide. When unlocking the trigger, the trigger sleeve moves upward, causing the trigger head to squeeze the trigger guide, which causes the trigger hook to disengage from the pen shell. The safety pin is also driven upward by the trigger sleeve, causing the trigger pin to disengage from the safety pin receiving cavity.

[0019] As a further improvement of this utility model, the top of the push rod cylinder is provided with two or more fixed arms, and the space between adjacent fixed arms is a clearance cavity.

[0020] The top of the injection spring holder is provided with a narrow spring seat; the top of the injection spring rests against the bottom of the narrow spring seat;

[0021] When the fixed arm at the top of the push rod is connected to the top of the retracting sleeve, the narrow spring seat of the injection spring bracket passes through the clearance cavity between the fixed arms.

[0022] As a further improvement of this utility model, the retractable sleeve is a cylinder with openings at both ends, having a sleeve body, and a spring bracket fixing groove is provided at the lower part of the sleeve body.

[0023] The injection spring bracket has downwardly extending connecting arms on both sides, and a bracket hook is provided at the bottom of the connecting arm. The bracket hook matches and connects with the spring bracket fixing groove of the retractable sleeve.

[0024] As a further improvement of this utility model, the top of the injection spring bracket extends downward to form a slender spring positioning post, which is inserted into the inside of the injection spring.

[0025] As a further improvement of this utility model, the push rod includes a push rod cylinder, the inner side of which is a spring cavity, and the injection spring is located inside the spring cavity.

[0026] The present invention relates to an injection spring locking and actuation mechanism for an automatic injection pen. The pen shell, the retractable sleeve, and the injection spring bracket are assembled together to form a top support mechanism for the injection spring, while the push rod sleeves the injection spring as a bottom support mechanism. The top of the push rod is engaged with the top of the retractable sleeve, and the actuation pin of the safety pin is engaged in the safety pin receiving cavity at the top of the push rod fixing arm, so that the fixing arm remains in an open state, thereby locking and protecting the injection spring.

[0027] The activation claw at the bottom of the safety pin is installed inside the pen casing; the activation sleeve can move relative to the pen casing; the activation sleeve disengages the activation claw of the safety pin from the pen casing and pushes the safety pin a certain distance relative to the pen casing, thereby causing the activation pin to disengage from the safety pin receiving cavity at the top of the push rod fixing arm. At this time, there is no further limit to the internal position of the fixing claw. Then, under the action of the elastic unfolding force of the injection spring, the push rod tends to move downward. At this time, the contraction guide converts the downward force of the fixing arm into the inward contraction deformation force of the fixing arm, causing the fixing claw to slide along the top of the sleeve body through the contraction guide; finally, the fixing claw completely disengages from the top plane of the sleeve body and enters the interior of the sleeve body, so that the push rod is in a state of being pushed downward by the injection spring. The injection spring gradually unfolds, pushing the push rod to continue to move downward and extend into the syringe, pushing the piston to continue to move downward, pushing the drug in the syringe out for injection.

[0028] The automatic injection pen of this invention features an injection spring locking and actuation mechanism that is simple yet ingenious in design. The top of the push rod is locked and limited by the actuation pin of the safety pin. The displacement of the safety pin allows the push rod to be actuated by the injection spring, thus enabling drug injection. To unlock, the actuation pin of the safety pin only needs to be dislodged from the safety pin receiving cavity at the top of the push rod fixing arm, requiring minimal unlocking force. Once unlocked, the separation of the push rod from the retracting sleeve is provided by the injection spring and proceeds continuously.

[0029] The present invention relates to an injection spring locking and triggering mechanism for an automatic injection pen, which can be applied to an automatic injection pen to achieve reliable safety locking and convenient unlocking for drug injection. Attached Figure Description

[0030] Figure 1 This is an overall outline drawing of the automatic injection pen of the present invention;

[0031] Figure 2 This is a schematic diagram of the pre-assembled module of the automatic injection pen of the present invention;

[0032] Figure 3 This is an exploded view of the components of the automatic injection pen of the present invention;

[0033] Figure 4 This is a schematic diagram of the overall structure of a prefilled syringe (PFS).

[0034] In the diagram, 1-Prefilled syringe (PFS); 11-Sliding sleeve; 12-Piston; 13-Injection needle; 14-Cap (also known as protective sheath); 15-Flange (also known as flange).

[0035] Figure 5 This is a schematic diagram of the overall structure of the lower pen shell of the present invention.

[0036] Figure 6 This is a cross-sectional view of the internal structure of the lower pen shell of the present invention;

[0037] Figure 7 This is a structural outline of the pen cap of the present invention;

[0038] Figure 8 This is a cross-sectional view of the internal structure of the pen cap of the present invention;

[0039] Figure 9 This is an overall structural outline of the excitation sleeve of the present invention;

[0040] Figure 10 This is a partial cross-sectional schematic diagram of the excitation sleeve of the present invention;

[0041] Figure 11 This is a schematic diagram of the structure of the PFS mounting sleeve of the present invention;

[0042] Figure 12 This is a schematic diagram of the structure of the PFS of the present invention installed in the lower pen shell component;

[0043] Figure 13 This is an overall cross-sectional view of the PFS after it has been installed in the lower pen shell pre-assembly module.

[0044] Figure 14 This is a schematic diagram of the overall structure of the upper pen shell of the present invention;

[0045] Figure 15 This is a cross-sectional view of the internal structure of the upper pen shell of the present invention;

[0046] Figure 16 This is a schematic diagram of the overall structure of the push rod of the present invention;

[0047] Figure 17 This is a cross-sectional view of the internal structure of the push rod of the present invention;

[0048] Figure 18 This is an overall structural outline drawing of the safety pin of the present invention;

[0049] Figure 19 This is a cross-sectional view of the internal structure of the safety pin of the present invention;

[0050] Figure 20 This is an overall structural outline of the retractable sleeve of the present invention;

[0051] Figure 21 This is a cross-sectional view of the internal structure of the retractable sleeve of the present invention;

[0052] Figure 22 This is an overall structural diagram of the injection spring support of the present invention;

[0053] Figure 23 A schematic diagram of the assembly of the push rod, injection spring, and injection spring support on the retraction sleeve;

[0054] Figure 24 This is an overall structural outline of the needle retraction spring base of the present invention;

[0055] Figure 25 This is a cross-sectional view of the internal structure of the needle retraction spring base of the present invention;

[0056] Figure 26 This is an overall structural outline of the upper pen shell pre-assembly module of the present invention;

[0057] Figure 27 This is a cross-sectional view of the internal structure of the upper pen shell pre-assembly module of the present invention;

[0058] Figure 28 This is the fully assembled, unused state of the automatic injection system of the present invention.

[0059] Figure 29 The automatic injection process of this invention is in step 1, with the pen cap removed.

[0060] Figure 30 This is a schematic diagram of the initial stage of step 2 in the use of the automatic injection method of the present invention. Figure 1 ;

[0061] Figure 31 This is a schematic diagram of the initial stage of step 2 in the use of the automatic injection method of the present invention. Figure 2 ;

[0062] Figure 32 This is a schematic diagram of step 2.1 of the automatic injection process of the present invention;

[0063] Figure 33 This is a schematic diagram of step 2.2 of the automatic injection process of the present invention;

[0064] Figure 34 This is a schematic diagram of the initial stage of step 2.3 of the automatic injection process of the present invention;

[0065] Figure 35 This is a schematic diagram of step 2.3 of the automatic injection process of the present invention;

[0066] Figure 36 This is a schematic diagram showing the imminent termination of step 2.3 of the automatic injection process of the present invention;

[0067] Figure 37 This is a schematic diagram illustrating steps 2.4 to 2.5 of the automatic injection process of the present invention;

[0068] Figure 38 This is a schematic diagram of step 2.6 of the automatic injection process of the present invention;

[0069] Figure 39 This is a schematic diagram of step 3 of the automatic injection process of the present invention;

[0070] Figure 40 This is a schematic diagram of the inward retraction and deformation process of the fixing claw in step 2.1 of the automatic injection process of the present invention. Figure 1 ;

[0071] Figure 41 This is a schematic diagram of the inward retraction and deformation process of the fixing claw in step 2.1 of the automatic injection process of the present invention. Figure 2 ;

[0072] Figure 42 This is a schematic diagram showing the fixing claw sliding inside the sleeve in step 2.3 of the automatic injection process of the present invention.

[0073] Figure 43 This is a schematic diagram illustrating the injection spring pushing the plunger for injection in steps 2.2 and 2.3 of the automatic injection process of the present invention.

[0074] Figure 44 This is a schematic diagram of the movement of the push rod relative to the injection spring support in step 2.3 of the automatic injection process of the present invention.

[0075] Figure 45 This is a schematic diagram of the process in which the clearance cavity continuously approaches the needle retraction fixing claw at the end of step 2.3 of the automatic injection process of the present invention.

[0076] Figure 46 This is a schematic diagram illustrating the change process of the needle-retracting fixing claw in step 2.5 of the automatic injection process of the present invention.

[0077] Figure 47 This is a schematic diagram of step 2.6 of the automatic injection process of the present invention. Detailed Implementation

[0078] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0079] The purpose of this invention is to provide an automatic injection pen, the overall structure of which, when not in use, is as follows: Figure 1As shown, from bottom to top, it includes a pen cap 22, a lower pen shell 21, and an upper pen shell 31. An observation window is provided on the lower pen shell 21, through which the internal syringe 11 can be seen through the transparent or also provided-with-an-observation-window PFS mounting sleeve, and through the transparent wall of the syringe 11, the state of the internal medicine can be observed.

[0080] The automatic injection pen of the present invention is manufactured and pre-assembled by an injection device manufacturer into a lower pen shell pre-assembly module 2 and an upper pen shell pre-assembly module 3. These two pre-assembly modules are delivered to the drug manufacturer and then assembled with a pre-filled syringe 1. Figure 2 As shown, the pre-filled syringe 1 is inserted into the lower pen shell pre-assembly module 2, and then the upper pen shell pre-assembly module 3 is installed, thus quickly forming the automatic injection pen of the present invention. All components of the automatic injection pen of the present invention are as follows... Figure 3 As shown.

[0081] Pen shell pre-assembly module 2 ,like Figure 3 As shown, it includes four parts: lower pen housing 21, pen cap 22, excitation sleeve 23, and PFS mounting sleeve 24.

[0082] Pen case 21 ,like Figure 5 , Figure 6 As shown, it includes an outer shell 211, inside which is a shell cavity 212; an observation window 213 is provided on the outer shell 211; the inner wall of the outer shell 211 and inside the shell cavity 212 are provided with two protrusions, namely an excitation guide protrusion 215 and a PFS support protrusion 216; the two protrusions are spaced apart.

[0083] The top of the outer shell 211 is provided with a structure for connecting and fixing with the upper pen shell 31 of the upper pen shell pre-assembly module 3. In this embodiment, a shell fixing groove 218 is provided on the top wall of the outer shell 211.

[0084] Pen Cap 22 ,like Figure 7 , Figure 8 As shown, an outer cap shell 221 is provided, and the upper part of the cap shell 221 is a connecting shell 222, which is used to connect with the pen cap mounting surface 217 at the bottom of the lower pen shell 21; preferably, the inner wall of the cap shell 221 is provided with a pen cap positioning protrusion 2222, which matches the size and position of the pen cap positioning groove 2172 to realize the positioning between the lower pen shell 21 and the pen cap 22.

[0085] The pen cap 22 has a protective cap holder 223 inside for storing the protective cap 14 of the pre-filled syringe 1. The upper part of the protective cap holder 223 has two or more cap claws 224 (two cap claws 224 are symmetrically arranged in this embodiment). The cap claws 224 are elastic bodies, and the top of the cap claws 224 forms a cap hook 225 inward. The upper part of the cap hook 225 is an inwardly inclined guide slope. When the pre-filled syringe 1 is installed into the lower pen shell pre-assembly module 2, the bottom of the protective cap 14 contacts the guide slope, so that the cap hook 225 can be pushed outward. At this time, the cap claws 224 elastically deform outward. The bottom of the cap hook 225 is a flat surface. When the pre-filled syringe 1 is installed in the lower pen shell pre-assembly module 2, the protective cap 14 is exactly located inside the protective cap holder 223. At this time, the cap claws 224 elastically reset, so that the cap hook 225 is just locked in the top of the protective cap 14, so that the protective cap 14 is completely located inside the protective cap holder 223. When the pen cap 22 is pulled, the protective cap 14 will be pulled off the syringe 11, thereby exposing the needle 13. Furthermore, the bottom of the protective cap holder 223 is provided with a retainer 226, which keeps the protective cap 14 inside the protective cap holder 223 and prevents it from being lost.

[0086] The lower part of the protective cap holder 223 of the pen cap 22 is provided with several retaining claws 227. The lower part of the retaining claws 227 protrudes outward to form a pen cap retaining protrusion 228. The upper part of the pen cap 22 is limited by the lower pen shell 21 and cannot move upward. The lower part of the pen cap 22 is connected to the excitation sleeve 23 through the pen cap retaining protrusion 228. When it is necessary to remove the pen cap 22, force needs to be applied downward. At this time, the pen cap retaining protrusion 228 moves inward against the bottom of the excitation sleeve 23, causing the retaining claws 227 to retract inward until the pen cap retaining protrusion 228 leaves the excitation sleeve 23, at which point the pen cap 22 can be removed.

[0087] Excitation sleeve 23 ,like Figure 9 , Figure 10 As shown, an excitation cylinder 231 is provided at the bottom, and the excitation cylinder 231 can be slidably installed on the bottom inner side of the outer shell 211 of the lower pen shell 21; the bottom plane of the excitation cylinder 231 shrinks inward to form a protective ring 232, the size of the protective ring 232 matches the pen cap fixing protrusion 228, and can be locked on the pen cap fixing protrusion 228; at the same time, the size of the protective ring 232 is also small, which can prevent fingers or other objects from being inserted and avoid touching the needle 13.

[0088] The excitation sleeve 23 has two excitation plates 233 forming an upward-facing excitation cylinder 231. The excitation plates 233 are slidably disposed within the channel 214 of the lower pen shell 21. An excitation head 234 is provided at the top of the excitation plate 233, and an inclined excitation slope 235 is provided at the top of the excitation head 234. Preferably, the excitation plate 233 is provided with a longitudinal guide groove 236, which matches the excitation guide protrusion 215, and the two together form a sliding guide.

[0089] PFS Installation Sleeve 24 ,like Figure 11 As shown, an installation cylinder 241 is provided, which contains a PFS receiving cavity 242. A support cylinder 243 is provided on the outside of the installation cylinder 241. The support cylinder 243 matches the housing cavity 212 of the lower pen shell 21, and the two are connected and fixed. At this time, the bottom surface 244 of the support cylinder 243 is connected to the PFS support protrusion 216. The top surface of the installation cylinder 241 and the support cylinder 243 are connected to form a PFS flange platform, which is used to support the flange 15 of the PFS.

[0090] like Figure 12 As shown, the lower pen housing 21, the excitation sleeve 23, and the PFS mounting sleeve 24 are pre-assembled together to form a structure that accommodates the PFS. At this time, in order to observe the pre-filled syringe 1 through the observation window 213, the PFS mounting sleeve 24 can be made entirely transparent, or the position of the PFS mounting sleeve 24 between the lower pen housing 21 can be locked, and then a corresponding observation window can also be opened on the wall of the PFS mounting sleeve 24 inside the observation window 213.

[0091] Further as Figure 13 As shown, the pre-filled syringe 1 is inserted into the open opening at the top of the lower pen shell pre-assembly module 2. The syringe 11 is inserted into the PFS mounting sleeve 24, and the protective cap 14 is inserted into the protective cap holder 223. The flange 15 contacts the top surface of the mounting cylinder 241 to achieve positioning. The PFS receiving cavity 242 positions the pre-filled syringe 1 as a whole. Thus, the assembly of the pre-filled syringe 1 and the lower pen shell pre-assembly module 2 is completed.

[0092] Upper Pen Shell Pre-assembly Module 3 ,like Figure 3 As shown, it includes eight parts: upper pen shell 31, push rod 41, injection spring 42, safety pin 43, retraction sleeve 51, injection spring bracket 52, needle retraction spring base 61, and needle retraction spring 62.

[0093] Upper pen case 31 ,like Figure 14 , Figure 15 As shown, it includes an upper shell 311, which is a cylindrical shell with an open lower end and a closed top 312; the lower part of the upper shell 311 is provided with a connector 313 for connecting to the top of the lower pen shell 21.

[0094] To achieve the connection between the upper pen shell 31 and the lower pen shell 21, the outer dimension of the connecting body 313 is smaller than the outer dimension of the upper shell 311, and the corresponding inner wall of the lower pen shell 21 is thinned to match the connecting body 313. Furthermore, the connecting body 313 is provided with a longitudinal clearance groove 3132, which gives the connecting body 313 elastic deformation space, making it easy to insert into the top of the lower pen shell 21. Furthermore, the connecting body 313 is provided with protruding pen shell fixing blocks 314, the number, position and size of which match the shell fixing groove 218. Furthermore, the lower part of the pen shell fixing block 314 is provided with an insertion guide slope 3142.

[0095] During the process of installing the upper pen shell pre-assembly module 3 into the lower pen shell pre-assembly module 2, the connector 313 of the upper pen shell 31 is inserted into the top of the lower pen shell 21. During the insertion process, the guide slope 3142 first contacts the top wall of the lower pen shell 21, thereby causing the wall of the connector 313 to undergo elastic deformation under force until the pen shell fixing block 314 falls completely into the housing fixing groove 218. At this time, the wall of the connector 313 elastically recovers. Furthermore, the cross-sections of the upper pen shell 31 and the lower pen shell 21 are not completely circular. After insertion, they also have positioning and limiting functions to prevent rotation between the upper pen shell 31 and the lower pen shell 21.

[0096] The upper pen shell 31 is also provided with a safety pin connecting groove 316 and a needle retraction spring base fixing groove 318, two mounting grooves; in this embodiment, the safety pin connecting groove 316 is located at the upper part, while the needle retraction spring base fixing groove 318 is located at the lower part and is located on the connecting body 313. The interior of the upper pen shell 31 is provided with several longitudinally protruding guide strips 317.

[0097] Putter 41 ,like Figure 16 , Figure 17 As shown, the device is a slender cylindrical body, including a push rod cylinder 411. The upper end of the push rod cylinder 411 is open, and the lower end is closed. The inner side of the push rod cylinder 411 is a spring cavity 412 for storing the injection spring 42. The top of the push rod cylinder 411 is provided with two or more fixing arms 413, and the space between adjacent fixing arms 413 is a clearance cavity 414. The top of the fixing arms 413 protrudes outward to form a fixing claw 415, and a retraction guide 416 is formed below the end of the fixing claw 415. In the natural state, the inner walls of the tops of the fixing arms 413 converge to form a safety pin receiving cavity.

[0098] The lower outer diameter of the push rod 411 of the push rod 41 is smaller than the inner diameter of the syringe 11, so that it can be inserted into the syringe 11 without obstruction and move along the axial direction of the syringe 11.

[0099] The bottom of the push rod cylinder 411 of the push rod 41 is provided with a piston cone 417. In this invention, the piston cone 417 of the push rod 41 not only needs to apply a downward pushing force to the piston 12 for injection, but also needs to apply an upward pulling force for needle retraction. Therefore, the piston cone 417 not only has a downward conical surface, but also has a connecting rod with a cross-section smaller than the top cross-section of the piston cone 417 between it and the push rod cylinder 411. This allows the piston cone 417 to be inserted into the piston hole 121 of the piston 12 and then be wrapped by the rubber elasticity of the piston 12, thereby being able to withstand the upward pulling force.

[0100] The lower part of the push rod cylinder 411 of the push rod 41 is provided with an outwardly protruding syringe stop 418. The syringe stop 418 has an inwardly retractable elasticity and can retract inward when subjected to force. The distance between the syringe stop 418 and the piston cone 417 matches the distance between the piston 12 and the top opening of the syringe 11 when the pre-filled syringe 1 is not in use.

[0101] During the process of the upper pen shell pre-assembly module 3 being installed into the lower pen shell pre-assembly module 2, the piston cone 417 is inserted into the top opening of the syringe 11 and finally fully inserted into the piston 12, where it is fixed. At this time, the bottom of the push rod cylinder 411 of the push rod 41 is also inserted into the top opening of the syringe 11, while the syringe stop 418 is positioned outside the top opening of the syringe 11. This prevents the syringe 11 from being subjected to impact force and moving upwards during transportation, which could cause the needle 13 to be accidentally pulled out of the protective cap 14 and result in premature injection of the medication, thus reducing the dosage.

[0102] Injection spring 42 The injection spring 42 is a slender spring, with its lower part installed inside the push rod cylinder 411 of the push rod 41, and its bottom abutting against the bottom of the push rod cylinder 411, applying a downward pushing force to the push rod 41; its upper part contacts the injection spring support 52. The elastic unfolding stroke of the injection spring 42 is relatively long, sufficient to fully push the push rod 41 into the syringe 11, so that the piston cone 417 drives the piston 12 to move along the axial direction of the syringe 11. The piston 12 moves to the bottom of the syringe 11, completely injecting the medicine into the syringe 11.

[0103] Safety pin 43 ,like Figure 18 , Figure 19 As shown, it has two movable arms 431, and the top of the movable arms 431 is provided with a connecting top. Furthermore, a guide arm 432 is provided between the two movable arms 431, and the guide arm 432 is also connected to the bottom of the connecting top; a longitudinal guide groove 433 is formed between the movable arms 431 and the guide arm 432.

[0104] The bottom of the two movable arms 431 extends downward to form mounting arms 434, which can be installed into the upper pen shell 31 along the inner wall of the upper shell 311. Furthermore, the mounting arms 434 are provided with elastic excitation claws 435, the bottom of which protrudes outward to form an excitation hook 436, which can be engaged into the safety pin connecting groove 316. The top of the excitation hook 436 has a flat fixing surface 4362 for hooking the top surface of the safety pin connecting groove 316 to fix the safety pin 43 in the upper pen shell 31. The lower part of the excitation hook 436 is provided with an inwardly inclined excitation guide 4363. Before the automatic injection pen of the present invention is used, the excitation guide 4363 extends inward beyond the safety pin connecting groove 316, protrudes inward from the upper shell 311 of the upper pen shell 31, and matches the excitation head 234 and excitation inclined surface 235 of the excitation sleeve 23 of the lower pen shell pre-assembly module 2.

[0105] The safety pin 43 has a downwardly protruding trigger pin 437 on its connecting top, the size of which matches the safety pin receiving cavity formed by the top of the fixed arm 413 of the push rod 41.

[0106] Retraction sleeve 51 ,like Figure 20 , Figure 21 As shown, it is a cylinder with openings at both ends, having a sleeve body 511. The lower part of the sleeve body 511 is provided with a spring bracket fixing groove 512 for connecting and fixing the injection spring bracket 52.

[0107] The bottom of the sleeve body 511 of the retracting sleeve 51 is connected to a connecting sleeve with a smaller outer diameter, thereby forming a stepped surface at the bottom of the sleeve body 511 to abut against the top of the take-off spring 62.

[0108] The lower part of the connecting sleeve of the retractable sleeve 51 is an elastic needle retraction fixing claw 513. The bottom of the needle retraction fixing claw 513 protrudes outward to form a needle retraction fixing hook 514. The upper part of the needle retraction fixing hook 514 has an inclined needle retraction guide 515.

[0109] The needle retraction fixing claw 513 forms a push rod guide cavity inside, which matches the push rod cylinder 411. When the cylindrical tube of the push rod cylinder 411 is located in the push rod guide cavity, the needle retraction fixing claw 513 cannot retract and deform inward. When the cylindrical tube of the push rod cylinder 411 is not in the push rod guide cavity, the inner side of the needle retraction fixing claw 513 is free and can retract and deform inward.

[0110] Injection spring stent 52 ,like Figure 22As shown, it has a slender spring positioning post 521, and a narrow spring seat 522 at the top of the spring positioning post 521 for limiting the top of the injection spring 42; the two sides of the narrow spring seat 522 extend downward to form connecting arms 523, and the bottom of the connecting arms 523 is provided with a bracket hook 524 for matching and connecting with the spring bracket fixing groove 512 of the retracting sleeve 51.

[0111] like Figure 23 As shown, the push rod 41, retractable sleeve 51, and injection spring bracket 52 are assembled together to compress and fix the injection spring 42, which is the pre-use state of the automatic injection pen of the present invention; the injection spring 42 is located inside the push rod cylinder 411 of the push rod 41, and the spring positioning post 521 of the injection spring bracket 52 is inserted into the injection spring 42; the bottom of the injection spring 42 abuts against the bottom of the inner cavity of the push rod cylinder 411 of the push rod 41, applying a downward pushing force to the push rod 41, while at this time, the outer side of the fixing claw 415 of the push rod 41 rests on the top plane of the sleeve body 511 of the retractable sleeve 51, achieving a limiting position; The top of the injection spring 42 abuts against the narrow spring seat 522 of the injection spring bracket 52, applying an upward thrust to the injection spring bracket 52. At this time, the bracket hook 524 of the injection spring bracket 52 is engaged in the spring bracket fixing groove 512 of the sleeve body 511 of the retractable sleeve 51, thus achieving fixation. In the use of this invention, the bracket hook 524 is always located in the spring bracket fixing groove 512, so that the injection spring bracket 52 is always fixedly installed in the retractable sleeve 51. The position of the push rod 41 and the injection spring bracket 52 is locked by the retractable sleeve 51, thereby compressing and fixing the injection spring 42.

[0112] 61 needle take-off spring base ,like Figure 24 , Figure 25 As shown, it is a cylinder with open ends and has a spring cylinder 611. The needle take-up spring 62 is sleeved on the spring cylinder 611. The bottom of the spring cylinder 611 extends outward to form an annular spring seat 612, which is used to support the bottom of the needle take-up spring 62. The inside of the spring cylinder 611 is a connecting cavity 613, which is used to insert the connecting cylinder at the bottom of the retractable sleeve 51.

[0113] The spring seat 612 of the needle retraction spring base 61 extends further outward to form a base fixing claw 614, which is used to engage with the needle retraction spring base fixing groove 318 of the upper pen shell 31. In the use of the present invention, the base fixing claw 614 is always located in the needle retraction spring base fixing groove 318, so that the needle retraction spring base 61 is always fixed in the upper pen shell 31.

[0114] 62 needle take-off springThe spring has a relatively large outer diameter and a relatively short length. The bottom of the retractable spring 62 abuts against the spring seat 612 of the retractable spring base 61. Since the retractable spring base 61 is always fixed inside the upper pen shell 31, the bottom of the retractable spring 62 is fixed in position relative to the upper pen shell 31. The top of the retractable spring 62 abuts against the bottom plane of the sleeve body 511 of the retractable sleeve 51, applying an upward thrust to the retractable sleeve 51.

[0115] After assembly, the upper pen shell pre-assembly module 3, as follows: Figure 26 , Figure 27 As shown; the take-off spring 62 is fitted onto the take-off spring base 61, then the bottom of the sleeve body 511 of the retracting sleeve 51 abuts against the top of the take-off spring 62, moving towards the take-off spring base 61, causing the take-off fixing hook 514 to pass over the spring sleeve 611 and abut against the bottom of the spring sleeve 611, while the take-off fixing claw 513 is located inside the spring sleeve 611, compressing the take-off spring 62; then the push rod 41 is inserted, so that the lower middle part of the push rod cylinder 411 of the push rod 41 is located in the push rod guide cavity inside the take-off fixing claw 513, preventing the take-off fixing claw 513 from retracting and deforming inward. This causes the retractable sleeve 51 to disengage from the needle-retracting spring base 61 under the thrust of the needle-retracting spring 62; at this time, the fixing claw 415 at the top of the push rod 41 hooks onto the top plane of the sleeve body 511 of the retractable sleeve 51; the injection spring 42 is installed in the spring cavity 412 of the push rod 41, and then the injection spring bracket 52 is installed on top of the injection spring 42, the spring positioning post 521 is inserted into the injection spring 42, the narrow spring seat 522 abuts against the top of the injection spring 42 and compresses the injection spring 42 downward, and finally the narrow spring seat 522 is inserted into the relief cavity 414 of the push rod 41, and the connection is complete. The connecting arm 523, along with the bracket hook 524, is inserted into the sleeve body 511. The connecting arm 523 retracts and deforms inward until the bracket hook 524 is engaged in the spring bracket fixing groove 512, thus compressing and fixing the injection spring 42. Then, the safety pin 43 is installed, so that the excitation pin 437 is inserted into the safety pin receiving cavity formed by the top of the fixing arm 413 of the push rod 41, preventing the fixing arm 413 from retracting and deforming inward, and allowing the fixing claw 415 to reliably hook onto the top plane of the sleeve body 511. Finally, the entire assembly is inserted into the upper pen shell 31, and the guide strip 317 is engaged in the safety pin holder. Within the guide groove 433 of the safety pin 43, the actuation claw 435 of the safety pin 43 retracts and deforms inward until the actuation hook 436 engages with the safety pin connecting groove 316. Meanwhile, the connecting body 313 elastically deforms until the base fixing claw 614 of the needle-retracting spring base 61 engages with the needle-retracting spring base fixing groove 318 of the upper pen shell 31. At this point, both the safety pin 43 and the needle-retracting spring base 61 are fixed within the upper pen shell 31, and the positions of the various parts are relatively locked. In particular, the parts that compress and fix the injection spring 42 and the needle-retracting spring 62 are mechanically limited by other parts, achieving a safety lock. Thus, the upper pen shell pre-assembly module 3 of the present invention is formed.

[0116] The upper pen shell pre-assembly module 3 needs to be assembled with the pre-filled syringe 1 and the lower pen shell pre-assembly module 2. The connector 313 of the upper pen shell 31 is inserted into the top of the lower pen shell 21. The guide slope 3142 is compressed, causing the connector 313 to contract inwards until the pen shell fixing block 314 completely falls into the shell fixing groove 218, and the pen shell positioning strip 315 is inserted into the pen shell positioning groove 219. Simultaneously, the piston cone 417 is inserted into the piston 12. As the connector 313 is inserted, the excitation head 234, against the inner wall of the upper pen shell 31, reaches the upper pen shell pre-assembly module 3, aligning with the excitation guide 4363 of the excitation hook 436. This completes the unused state of the automatic injection pen of the present invention, ready for storage and transportation. Figure 28 As shown.

[0117] When the automatic injection pen of the present invention is delivered to the patient for use, the following steps are included:

[0118] Step 1: The patient removes the pen cap 22; as Figure 29 As shown, hold the pen body (lower pen shell 21, upper pen shell 31) with one hand and the pen cap 22 with the other hand. Apply force to remove the pen cap 22 from the lower pen shell 21. At this time, the pen cap 22 will remove the protective cap 14 along with it, so that the needle 13 inside the excitation sleeve 23 is exposed, but the needle 13 is still inside the excitation sleeve 23 and is covered by the excitation sleeve 23.

[0119] Step 2: The patient performs the injection; The patient holds the pen body and places the bottom plane of the protective ring 232 of the excitation sleeve 23 against the injection site, and then applies pressure towards the body, causing the excitation sleeve 23 to retract into the lower pen shell 21; At this time, the needle 13 gradually passes over the protective ring 232 and enters the injection site, completing the injection action.

[0120] As the excitation sleeve 23 moves upward relative to the lower pen housing 21, the excitation head 234 comes into contact with the excitation guide 4363 of the excitation hook 436. Along the inclined surface of the excitation guide 4363, the longitudinal force is converted into an inward contraction deformation force of the excitation hook 436, causing the excitation hook 436 to disengage from the safety pin connecting groove 316. Figure 30 As shown; furthermore, the excitation head 234 pushes the safety pin 43 upward, thereby causing the excitation pin 437 to disengage from the safety pin receiving cavity at the top of the push rod 41 fixed arm 413, as shown. Figure 31 As shown, the internal mechanism of the automatic injection pen of the present invention continuously realizes injection and needle retraction under the pushing force of the injection spring 42 and the needle retraction spring 62. The specific operation process is as follows:

[0121] Action 2.1: The fixed claw 415 retracts inward; as... Figure 32As shown, when the trigger pin 437 disengages from the safety pin receiving cavity at the top of the fixed arm 413, the fixed claw 415 becomes infinitely movable. Then, under the elastic unfolding force of the injection spring 42, the push rod 41 tends to move downwards. At this time, the retraction guide 416 converts the downward force of the fixed arm 413 into a force causing the fixed arm 413 to retract and deform inwards, causing the fixed claw 415 to slide along the top of the sleeve body 511 through the retraction guide 416. Figure 40 , Figure 41 As shown; finally, the fixing claw 415 completely disengages from the top plane of the sleeve body 511 and enters the interior of the sleeve body 511, causing the push rod 41 to be in a downward state under the thrust of the injection spring 42, as shown. Figure 34 As shown;

[0122] Action 2.2, During the injection process, the syringe stop 418 is compressed and squeezed into the syringe 11; as... Figure 33 As shown, after the push rod 41 moves downward a certain distance, the syringe stop 418 contacts the top of the syringe 11, and the syringe stop 418 is compressed and deformed inward until it is completely squeezed into the syringe 11, as shown. Figure 43 As shown; at this time, the push rod 41 has driven the piston 12 to move downward a certain distance, realizing the injection of the drug;

[0123] Action 2.3, during the injection process, push rod 41 pushes piston 12 to continue moving downwards; as... Figure 34 , Figure 35 , Figure 36 ,and Figure 44 As shown, the narrow spring seat 522 is located exactly in the relief cavity 414 between the fixed arms 413, which does not affect the downward movement of the push rod 41.

[0124] During the process, such as Figure 45 As shown, the clearance cavity 414 between the fixed arms 413 of the push rod 41 moves accordingly and then continuously enters the lower area of ​​the sleeve body 511, gradually approaching the inner side of the needle retraction fixing claw 513.

[0125] Action 2.4: Injection complete. The plunger 41 pushes the piston 12 to the bottom of the syringe 11, as shown. Figure 37 As shown, at this time, the fixing claw 415 of the push rod 41 also moves to the bottom of the sleeve body 511 and rests on the platform at the bottom of the sleeve body 511; while the clearance cavity 414 between the fixing arms 413 also moves to the bottom of the sleeve body 511 and is located inside the needle retraction fixing claw 513.

[0126] Action 2.5, the needle retaining claw 513 retracts inward; as... Figure 37 , Figure 46As shown, when the push rod cylinder 411 of the push rod 41 moves downward away from the position of the needle-retracting fixing claw 513, the clearance cavity 414 between the fixing arms 413 moves to the position of the needle-retracting fixing claw 513. At this time, the inside of the needle-retracting fixing claw 513 is no longer in a position of limit. Then, under the action of the needle-retracting spring 62, the top of the needle-retracting spring 62 pushes the bottom step surface of the sleeve body 511, causing the retracting sleeve 51 to tend to move upward. This causes the needle-retracting fixing claw 513 to move upward as well. The needle-retracting guide 515 on the upper part of the needle-retracting fixing hook 514 contacts the bottom of the spring seat 612, converting the upward force into the force of the needle-retracting fixing claw 513 contracting and deforming inward. This causes the needle-retracting fixing claw 513 to slide along the bottom of the spring seat 612 through the needle-retracting guide 515. Finally, the needle-retracting fixing claw 513 completely disengages from the bottom of the spring seat 612 and enters the spring cylinder 611, so that the retracting sleeve 51 is in a state of being pushed upward by the needle-retracting spring 62. Figure 38 As shown;

[0127] Action 2.6, the finishing stitch process; as follows Figure 38 As shown, the retracting spring 62 gradually unfolds, causing the retracting sleeve 51 to move upward. The bottom of the sleeve body 511 of the retracting sleeve 51 also causes the fixing claw 415 of the push rod 41 to move upward along with it. Figure 47 As shown; during this process, the piston cone 417 of the push rod 41 drives the piston 12, and the piston 12 drives the syringe 11 through friction with the bottom of the syringe 11. The syringe 11 drives the needle 13 through the connecting force, and multiple parts move upward together; as the needle 13 moves upward, it is gradually pulled out from the injection site and retracted into the excitation sleeve 23, as shown. Figure 39 As shown.

[0128] During this process, the push rod 41 will also drive the injection spring bracket 52 and the retraction sleeve 51 to move upward through the injection spring 42.

[0129] Step 3: Complete the injection and remove the needle. The patient should dispose of the automated injection pen of this invention after the injection is complete, such as... Figure 39 As shown.

[0130] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A shot spring lock firing mechanism for an auto-injector pen, characterized in that, Includes pen casing, push rod, injection spring, safety pin, retraction sleeve, and injection spring support; The injection spring support is fixed inside the retractable sleeve; the retractable sleeve is installed inside the pen casing. The safety pin is equipped with a flexible trigger claw, and the trigger claw is equipped with a trigger hook, which can be detachably snapped into the pen case; the top of the safety pin is equipped with a protruding trigger pin post; after the trigger hook of the safety pin is detached from the pen case, the safety pin can move along the axis of the pen case. The plunger is connected at the bottom to the piston of the syringe; the plunger contains an injection spring. The top of the push rod is provided with a flexible fixing arm; the top of the fixing arm protrudes outward to form a fixing claw, and a retraction guide is formed below the end of the fixing claw; a safety pin receiving cavity is formed on the inner side of the top of the fixing arm; the excitation pin is matched with the safety pin receiving cavity; The top of the injection spring rests against the injection spring support, and the top and bottom of the injection spring rest against the push rod.

2. An injection spring lock and cocking mechanism for an auto-injector pen according to claim 1, wherein, An excitation sleeve is provided inside the pen casing, and the excitation sleeve can move along the axis of the pen casing; an excitation head is provided on the top of the excitation sleeve. The bottom of the safety pin extends downward to form an elastic trigger claw, and the bottom of the trigger claw protrudes outward to form an trigger hook; the lower part of the trigger hook is provided with a trigger guide. The excitation head is matched with the excitation guide.

3. An injection spring lock and firing mechanism for an auto-injection pen as defined in claim 1, wherein, The top of the push rod cylinder is provided with two or more fixed arms, and the space between adjacent fixed arms is a clearance cavity; The top of the injection spring holder is provided with a narrow spring seat; the top of the injection spring rests against the bottom of the narrow spring seat; When the fixed arm at the top of the push rod is connected to the top of the retracting sleeve, the narrow spring seat of the injection spring bracket passes through the clearance cavity between the fixed arms.

4. An injection spring lock and cocking mechanism for an auto-injection pen according to claim 1, wherein, The retractable sleeve is a cylinder with openings at both ends, and has a sleeve body. The lower part of the sleeve body is provided with a spring bracket fixing groove. The injection spring bracket has downwardly extending connecting arms on both sides, and a bracket hook is provided at the bottom of the connecting arm. The bracket hook matches and connects with the spring bracket fixing groove of the retractable sleeve.

5. An injection spring lock and firing mechanism for an auto-injection pen as defined in claim 1, wherein, The top of the injection spring holder extends downward to form a slender spring positioning post, which is inserted inside the injection spring.

6. An injection spring lock and cocking mechanism for an auto-injection pen as defined in claim 1, wherein, The push rod includes a push rod sleeve, the inner side of which is a spring cavity, and the injection spring is located inside the spring cavity.

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