Automatic injection pen with replaceable pre-filling and sealing needle

Abstract

The invention discloses an automatic injection pen with a replaceable pre-filling and sealing needle, which relates to the technical field of injection pens and comprises a lower pen shell, an upper pen shell, a pen cap, a button assembly and an automatic injection assembly. The upper pen shell is in threaded connection with the lower pen shell, the pen cap is clamped with the end of the lower pen shell, the button assembly comprises an inner nut in threaded connection with the upper pen shell, and the end of the inner nut is elastically connected with a button. A patient does not need to adjust the dosage before injection, injection operation is carried out by manually pushing the driving mechanism, automatic injection can be achieved under the action of the internal automatic injection assembly only by shifting the plug pin and pressing the button, operation is easy and convenient, and high practicability is achieved; according to the dosage, the liquid medicine in the pre-filling and sealing needle can be completely set according to the requirement of a patient, or the moving distance of the automatic injection assembly is set according to the requirement, so that quantitative injection to the patient is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of injection pens, in particular to an automatic injection pen with a replaceable prefilled needle. Background Art

[0002] The injection pen, also known as the insulin injection pen, refers to an insulin injection device that contains a pre-filled needle. After removing the rubber plug on the outside of the needle, the needle is inserted into the human body's subcutaneous tissue. Then, the push rod is driven by pressing the button at the rear end of the injection pen. The piston in the needle tube is pushed to move through the linkage of the driving mechanism in the injection pen, so that the medicine in the needle tube is injected into the human body through the needle. However, this method requires the patient to adjust the injection dose according to the instructions before injection, and then use it according to standard operations to ensure the injection dose. However, this method is inconvenient for some patients, and may even result in dosage adjustment and injection operation errors, resulting in unsatisfactory final injection effect. Therefore, it is necessary to design a new injection pen to solve the above problems. Summary of the invention

[0003] The purpose of the present invention is to design an automatic injection pen with a replaceable prefilled needle to solve the problem that the existing injection pen mentioned in the above background technology requires dosage adjustment before injection and standard injection operation according to the instructions for use. For some patients, it is inconvenient to use and errors in dosage adjustment and injection operation may occur, resulting in unsatisfactory final injection effect.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The replaceable prefilled needle automatic injection pen comprises a lower pen shell, an upper pen shell, a pen cap, a button assembly and an automatic injection assembly; the upper pen shell and the lower pen shell are threadedly connected, so that the upper pen shell and the lower pen shell are easy to disassemble and assemble, and then the subsequent disassembly and assembly of the prefilled needle is convenient; the pen cap and the end of the lower pen shell are engaged, so that the pen cap and the lower pen shell are convenient to disassemble and assemble; the button assembly comprises an inner nut threadedly connected to the upper pen shell, and the end of the inner nut is elastically connected to a button, so that the button assembly and the upper pen shell are easy to disassemble and assemble through the threaded connection; The automatic injection assembly comprises a holder elastically connected to the interior of the lower pen housing, wherein a prefilled needle is clamped in the holder, and the prefilled needle and the holder are conveniently disassembled and assembled by clamping, thereby realizing installation and replacement of the prefilled needle; A connecting rod is provided inside the upper pen shell, and the end of the connecting rod is engaged with the inner nut. A base push rod is elastically connected to the outer surface of the connecting rod. The base push rod pushes the base and the prefilled needle so that the needle tip of the prefilled needle is automatically inserted into the subcutaneous tissue of the patient. A latch is provided on the inner nut, and a latch groove is provided on the surface of the base push rod to cooperate with the latch. The locking and unlocking of the base push rod are achieved through the cooperation of the latch and the latch groove. A first protrusion is fixed on one side of the push rod of the card seat extending into the interior of the button, a second elastic card block cooperating with the first protrusion is fixed in the inner nut, and a second limiting clamping ring cooperating with the second elastic card block is fixed on one side of the interior of the button, the first protrusion can be engaged and limited by the second elastic card block, and the engagement or disengagement of the second elastic card block with the first protrusion can be controlled by the second limiting clamping ring; The cartridge push rod is provided with an injection push rod inside, and the injection push rod is used to push the medicine liquid inside the prefilled needle to realize automatic injection of the medicine liquid. The injection push rod is elastically connected to the connecting rod, and a first elastic block is provided at the end of the connecting rod. The injection push rod is provided with a second protrusion that cooperates with the first elastic block, and the second protrusion can be engaged and limited by the first elastic block. The cartridge push rod is provided with a first limiting clamping ring that cooperates with the first elastic clamping ring. Through the design of the first limiting clamping ring, the engagement or disengagement of the first elastic clamping ring with the second protrusion can be controlled. A positioning block that cooperates with the first limiting clamping ring is provided on the surface of the injection push rod. Through the design of the positioning block, after the injection of the medicine liquid, before the new prefilled needle is installed into the injection pen, the cartridge push rod can be driven back to its original position by pushing the injection push rod, so as to realize automatic injection and also facilitate the replacement of the prefilled needle so that the automatic injection assembly can be returned to its original position for recycling.

[0005] Preferably, a card is fixed on one side of the outer surface of the inner nut, and a waist-round hole is opened on the card. The latch passes through the waist-round hole and is inserted into the latch groove. The design of the waist-round hole facilitates the movement of the latch to achieve locking or unlocking of the card seat push rod; A first waisted round groove is formed on one side of the surface of the latch pin groove, and a second waisted round groove is formed on the other side of the surface of the latch pin groove. The first waisted round groove and the second waisted round groove are connected to each other through an arc-shaped opening transition. The left side of the second waisted round groove is aligned with the right side of the first waisted round groove. The length of the second waisted round groove is greater than the length of the first waisted round groove. Through the design of the first waisted round groove and the second waisted round groove, the latch pin will enter the second waisted round groove from the first waisted round groove when unlocked. At this time, under the action of the elastic restoring force between the card seat push rod and the connecting rod, the card seat push rod moves toward the side of the pre-filled needle until it is blocked by the right side wall of the second waisted round groove. At this time, the first protrusion will move to the position where it abuts against the second elastic block. At this time, the card seat push rod will also push the card seat and the pre-filled needle to move a relative distance toward the pen cap side. The distance between the first protrusion and the second elastic block is equal to the distance that the latch moves in the second waisted groove, so that the seat push rod moves reasonably.

[0006] Preferably, arc-shaped baffles are symmetrically provided on the card outside the latch. The design of the arc-shaped baffles can prevent accidental touch from causing the latch to move when not in use, thereby unlocking the card seat push rod and further unlocking the automatic injection component, affecting the use of subsequent injections.

[0007] Preferably, the holder comprises a cartridge clamped in the lower pen shell, a fixing plate is fixed at one end of the lower pen shell, and a first through hole cooperating with the cartridge is provided on the fixing plate; a hook piece cooperating with the prefilled needle is fixed on one side of the cartridge, and the prefilled needle is installed into the cartridge by inserting the prefilled needle into the cartridge until it is blocked by the hook piece; A first spring is sleeved on the outer side of the cartridge, and the inner diameter of the first spring coil is larger than the outer diameter of the first through hole. Through the design of the first spring, the cartridge and the prefilled needle can synchronously reciprocate in the lower pen housing; The end of the first spring abuts against one side of the diaphragm, and the side of the diaphragm away from the first spring abuts against the second spring; the end of the second spring away from the diaphragm abuts against a gasket, and a positioning piece is fixed on the gasket. The top of the cartridge is set as a first waist round piece that matches the positioning piece, and the end of the prefilled needle is set as a second waist round piece that matches the first waist round piece. Through the design of the first waist round piece, the second waist round piece and the positioning piece, the prefilled needle can only be installed along the set direction, ensuring the normal progress of subsequent operations; At the same time, through the design of the gasket, the positioning piece and the second spring, when the lower pen shell is installed, the positioning piece will be squeezed by the upper pen shell first, until the lower pen shell and the upper pen shell are installed, so that the positioning piece and the second waist round piece are flush with the inside of the upper pen shell, so that the later card seat push rod can synchronously push the card seat and the pre-filled needle.

[0008] Preferably, a second limiting piece is fixed on a side of the spacer close to the first spring, a first limiting piece matched with the second spring is fixed on the spacer, and a positioning groove matched with the second limiting piece is provided in the lower pen shell. The movement of the first spring and the second spring can be limited by the design of the first limiting piece and the second limiting piece, so that the movement of the first spring and the second spring is stable, and the spacer can only be installed according to the position of the positioning groove by the design of the positioning groove, and the cartridge and the prefilled needle can only be installed along the set direction by cooperating with the design of the first waist round piece, the second waist round piece and the positioning piece; A return stop block is provided at the end of the cartridge, and the return stop block is spaced apart from the hook. Through the design of the return stop block, after the cartridge extends into the lower pen housing and passes through the fixing plate, the return stop block will reset after deformation and then abut against the outer side of the fixing plate, so that the cartridge will not fall off.

[0009] Preferably, a partition is fixed inside the upper pen shell near one side of the lower pen shell, and a third through hole cooperating with the injection push rod is opened on the partition; arc grooves are symmetrically opened on the partition located on both sides of the third through hole, and an arc plate cooperating with the arc groove is fixed to the end of the base push rod; the first waist round piece, the second waist round piece and the positioning piece are all abutted against the partition; the positioning piece and the arc groove are spaced apart to avoid the positioning piece from interfering with the movement of the base push rod, thereby ensuring that the base push rod can push the base and the prefilled needle normally.

[0010] Preferably, a fourth spring is abutted between the outer surface of the seat push rod and the outer surface of the connecting rod to achieve an elastic connection between the seat push rod and the connecting rod, and the fourth spring is in a compressed state at this time and has a restoring force; an insertion rod is provided inside the connecting rod, and a fifth spring is sleeved on the outer surface of the insertion rod, and the fifth spring is inserted inside the injection push rod and abuts against the inner wall of the injection push rod to achieve an elastic connection between the injection push rod and the connecting rod, and the fifth spring is in a compressed state at this time, so that the injection push rod has a restoring force; the inner nut and the button are connected by a sixth spring to achieve an elastic connection between the button and the inner nut.

[0011] Preferably, the lower pen housing located outside the fixing plate is elastically connected to a protective cover via a third spring, and a second through hole cooperating with the prefilled needle is provided on the side of the protective cover; the inner diameter of the ring of the third spring is larger than the outer diameter of the second through hole, and the design of the protective cover prevents the patient from seeing the needle of the prefilled needle when injecting the liquid medicine, thereby alleviating the fear in the patient's heart and avoiding affecting the injection operation; The protective cover surface is provided with an opening, an elastic slider is fixed on the opening, and the lower pen shell surface is provided with a slide groove cooperating with the elastic slider. Through the design of the elastic slider and the slide groove, the protective cover is stably connected to the lower pen shell and the protective cover moves stably during the subsequent extension and retraction process.

[0012] Preferably, a limiting protrusion is fixed on the surface of the protective cover, and a limiting groove cooperating with the limiting protrusion is opened on the inner wall of the lower pen shell. Through the design of the limiting protrusion and the limiting groove, a limiting effect is played on the contraction of the protective cover, thereby preventing the protective cover from being completely immersed in the lower pen shell during injection and exposing the needle tip of the prefilled needle. At the same time, the end face of the lower pen shell directly contacts the patient's skin, reducing the effect of positioning support.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention makes the cartridge push rod and the injection push rod both in a power storage state through the design of the cartridge push rod, the injection push rod, the connecting rod, the fourth spring and the fifth spring. At the same time, with the design of the first protrusion, the second elastic block, the second limit clamp ring, the second protrusion, the first elastic block and the first limit clamp ring, the automatic injection component after power storage is divided into two strokes, namely, the cartridge push rod pushes the prefilled needle to move outward as a whole and the injection push rod pushes the internal liquid of the prefilled needle to complete the injection. At this time, the design of the latch, the latch groove, the first waist round groove and the second waist round groove is used to lock the automatic injection components such as the cartridge push rod; when automatic injection is required, the two strokes are as follows: The card base push rod pushes the pre-filled needle to move outward as a whole: first, the latch is pushed into the second waist round groove to release the lock on the card base push rod, and under the action of the restoring force of the fourth spring, the card base push rod moves to the side of the lower pen shell, at this time, the first protrusion just fits and abuts with the second elastic block, and the arc plate just passes through the arc groove and abuts with the second waist round piece on the pre-filled needle; then, the button is pressed to release the second limit clamp ring from limiting the second elastic block, and then the first protrusion squeezes the second elastic block under the action of the restoring force of the fourth spring, and at this time, the card base push rod will continue to move into the lower pen shell, pushing the pre-filled needle to move as a whole; The injection push rod pushes the liquid medicine inside the prefilled needle to complete the injection: until the first limit clamp ring on the holder push rod fits with the positioning block on the injection push rod, at which time the first limit clamp ring releases the limit on the first elastic block, so that the second convex block squeezes the first elastic block under the action of the fifth spring restoring force, so that the injection push rod pushes the liquid medicine inside the prefilled needle under the action of the fifth spring restoring force to achieve liquid medicine injection; According to the above content, the present invention does not require the patient to adjust the dosage before injection. The injection operation is performed by manually pushing the driving mechanism. Only by turning the latch and pressing the button, the automatic injection can be achieved under the action of the internal automatic injection component. The operation is simple and convenient, and it has strong practicality. Moreover, the dosage can be completely set according to the needs of the patient, by setting the liquid in the pre-filled needle, or by setting the moving distance of the automatic injection component according to the needs, so as to achieve quantitative injection of the patient. The present invention realizes directional installation of the prefilled needle through the design of the threadedly connected lower pen shell and upper pen shell, cartridge, spacer, first limit plate, second limit plate, positioning groove, gasket, positioning plate, first waist round plate and second waist round plate, and cooperates with the setting of the above-mentioned automatic injection component so that the automatic injection component can be reversed and restored to its original position, thereby allowing the prefilled needle to be repeatedly replaced for easy recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic front view of the structure of the present invention; Figure 2 It is a schematic cross-sectional view of the structure of the present invention; Figure 3 It is a front view cross-sectional schematic diagram of the internal structure of the lower pen housing in the present invention; Figure 4 It is a front view cross-sectional schematic diagram of the structure of the lower pen housing in the present invention; Figure 5 It is a schematic diagram of the three-dimensional structure of the card seat in the present invention; Figure 6 This is a schematic diagram of the three-dimensional structure of the card holder installed with the pre-filled needle in the present invention; Figure 7 It is a schematic diagram of the three-dimensional structure of the protective cover in the present invention; Figure 8 It is a front view cross-sectional schematic diagram of the structure inside the upper pen shell of the present invention; Fig. 9 It is a schematic diagram of the partial three-dimensional structure of the automatic injection component in the present invention.

[0015] Indicated in the figure: Lower pen housing; 111, fixing plate; 112, first through hole; 113, slide groove; 114, limiting groove; 115, positioning groove; 120, cartridge; 121, hook piece; 122, first waist round piece; 123, return check spring block; 130, prefilled needle; 131, second waist round piece; 140, spacer; 141, first limiting piece; 142, second limiting piece; 150, first spring; 160, gasket; 161, positioning piece; 170, second spring; 180, protective cover; 181, second through hole; 182, opening; 183, elastic slider; 184, limiting protrusion; 190, third spring; Upper pen shell; 211, partition; 212, third through hole; 213, arc groove; 220, connecting rod; 221, first elastic block; 230, card seat push rod; 231, first convex block; 232, first limit clamp ring; 233, arc plate; 234, latch groove; 235, first waist round groove; 236, second waist round groove; 240, fourth spring; 250, plug rod; 260, injection push rod; 261, second convex block; 262, positioning block; 270, fifth spring; Pen cap; Inner nut; 411, second elastic block; 420, button; 421, second limit clamp; 430, card; 431, waist round hole; 432, arc-shaped baffle; 440, latch; 510. Sixth spring. DETAILED DESCRIPTION

[0016] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0017] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents some embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0019] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0020] The embodiments of the present invention are: See also Figure 1-9 As shown, the replaceable prefilled needle automatic injection pen includes a lower pen shell 110, an upper pen shell 210, a pen cap 310, a button assembly and an automatic injection assembly; The upper pen housing 210 is threadedly connected to the lower pen housing 110, the pen cap 310 is engaged with the end of the lower pen housing 110, and the button assembly includes an inner nut 410 threadedly connected to the upper pen housing 210, and a button 420 is elastically connected to the end of the inner nut 410; The upper pen housing 210 and the lower pen housing 110, and the inner nut 410 and the upper pen housing 210 are connected by a threaded connection, so that the upper pen housing 210 and the lower pen housing 110, and the inner nut 410 and the upper pen housing 210 are easy to install and disassemble; at the same time, the pen cap 310 and the lower pen housing 110 are engaged, which also facilitates the installation and disassembly of the pen cap 310; The internal structure of the lower pen housing 110 is as follows: A fixing plate 111 is fixed to the side of the lower pen housing 110 close to the pen cap 310, a first through hole 112 is provided in the middle of the fixing plate 111, and a positioning groove 115 is symmetrically provided to the side of the lower pen housing 110 away from the pen cap 310. The cartridge 120 is inserted into the lower pen housing 110 by the engagement of the second limiting piece 142 and the first limiting piece 141 with the positioning groove 115, and the end of the cartridge 120 passes through the first through hole 112; The second limiting piece 142 and the first limiting piece 141 are respectively installed on both sides of the spacer 140, and the spacer 140 is fixed to the surface of the cartridge 120. The surface of the cartridge 120 located inside the second limiting piece 142 is sleeved with a first spring 150, one end of the first spring 150 abuts against the fixed plate 111, and the other end of the first spring 150 abuts against the spacer 140; A first round piece 122 is provided on one side of the cartridge 120 close to the upper pen housing 210, a gasket 160 is sleeved on the outer side of the first round piece 122, and a second spring 170 is provided between the gasket 160 and the spacer 140; a positioning piece 161 is symmetrically fixed on the gasket 160, and a second round piece 131 matching the first round piece 122 is provided at the end of the prefilled needle 130. Through the action of the positioning piece 161, the prefilled needle 130 is inserted into the cartridge 120 along the relative position of the positioning piece 161 until it is abutted by the hook piece 121, and the hook piece 121 is symmetrically fixed at the end of the cartridge 120; A return spring block 123 is symmetrically fixed on the cartridge 120 on the same side as the hook piece 121. The return spring block 123 is spaced apart from the hook piece 121. When the cartridge 120 passes through the first through hole 112, the return spring block 123 will be squeezed and deformed. After completely passing through the first through hole 112, the return spring block 123 will return to its original position under the action of the restoring force and abut against the outer side of the fixing plate 111, so that the cartridge 120 will not fall off. The lower pen housing 110 located outside the fixing plate 111 is elastically connected to a protective cover 180 through a third spring 190. A second through hole 181 cooperating with the prefilled needle 130 is provided on the side of the protective cover 180. The inner diameter of the third spring 190 is larger than the outer diameter of the second through hole 181. The design of the protective cover 180 prevents the patient from seeing the needle of the prefilled needle 130 when injecting the drug solution, thereby alleviating the fear in the patient's heart and avoiding affecting the injection operation. An opening 182 is provided on the surface of the protective cover 180, and an elastic slider 183 is fixed on the opening 182. A slide groove 113 cooperating with the elastic slider 183 is provided on the surface of the lower pen housing 110. The design of the elastic slider 183 and the slide groove 113 ensures that the protective cover 180 is stably connected to the lower pen housing 110, and also ensures that the protective cover 180 moves stably during the subsequent extension and retraction process. A limiting protrusion 184 is fixed on the surface of the protective cover 180, and a limiting groove 114 is provided on the inner wall of the lower pen housing 110 to cooperate with the limiting protrusion 184. The design of the limiting protrusion 184 and the limiting groove 114 can limit the contraction of the protective cover 180, thereby preventing the protective cover 180 from being completely immersed in the lower pen housing 110 during injection, thereby exposing the needle head of the prefilled needle 130, and at the same time, the end face of the lower pen housing 110 directly contacts the patient's skin, thereby reducing the effect of positioning support; The internal structure of the upper pen housing 210 is as follows: A partition 211 is fixed to one side of the upper pen shell 210 near the lower pen shell 110, and a third through hole 212 for the injection push rod 260 to move is provided in the middle of the partition 211, and arc grooves 213 are provided on the partitions 211 located on both sides of the third through hole 212, and the arc grooves 213 are used for the movement of the arc plate 233; when the lower pen shell 110 and the upper pen shell 210 are installed, the positioning piece 161 inside the lower pen shell 110 will first compress the second spring 170 under the resistance of the partition 211 until it is flush with the second waist round piece 131 at the end of the prefilled needle 130 and abuts against the surface of the partition 211, and at this time, the installation of the lower pen shell 110 and the upper pen shell 210 is realized under the action of the threaded connection; at this time, the positioning piece 161 and the arc groove 213 are spaced apart to avoid interference with the movement of the arc plate 233; Two groups of arc plates 233 are symmetrically fixed to the end of the card seat push rod 230. One end of the card seat push rod 230 away from the arc plate 233 is sleeved on the outer surface of the connecting rod 220. The outer surface of the connecting rod 220 and the outer surface of the card seat push rod 230 are abutted by the fourth spring 240. A first elastic block 221 is fixed to the end surface of the connecting rod 220. The outer side of the first elastic block 221 abuts against a first limiting snap ring 232. The first limiting snap ring 232 is fixed inside the card seat push rod 230. The connecting rod 220 is internally engaged with an insert rod 250, and the surface of the insert rod 250 is sleeved with a fifth spring 270. The insert rod 250 and the fifth spring 270 are both inserted into the injection push rod 260. A second protrusion 261 is fixed to one end of the injection push rod 260 close to the connecting rod 220, and the second protrusion 261 is engaged with the first elastic block 221. A positioning block 262 is fixed on the surface of the injection push rod 260 between the first limiting clamp ring 232 and the partition plate 211, and is used to push the first limiting clamp ring 232 on the seat push rod 230; A latch groove 234 is fixed on the surface of the card seat push rod 230, the connecting rod 220 is engaged in the inner nut 410, a card 430 is fixed on the outer surface of the inner nut 410, a waist-shaped hole 431 is opened on the card 430, and the latch 440 passes through the waist-shaped hole 431 and is inserted into the latch groove 234, so as to lock the card seat push rod 230; One side of the surface of the latch groove 234 is provided with a first waisted round groove 235, and the other side of the surface of the latch groove 234 is provided with a second waisted round groove 236. The first waisted round groove 235 and the second waisted round groove 236 are connected through an arc-shaped opening transition. The left side of the second waisted round groove 236 is aligned with the right side of the first waisted round groove 265. The length of the second waisted round groove 236 is greater than the length of the first waisted round groove 235. Through the design of the first waisted round groove 235 and the second waisted round groove 236, the latch 440 can be unlocked. At a certain time, it will enter the second waisted round groove 236 from the first waisted round groove 235. At this time, under the elastic restoring force between the card base push rod 230 and the connecting rod 220, the card base push rod 230 moves to the side of the pre-filled needle 130 until it is blocked by the right side wall of the second waisted round groove 236. At this time, the first protrusion 231 will move to the abutment position with the second elastic block 411. At this time, the card base push rod 230 will also push the card base and the pre-filled needle 130 to move a relative distance to the pen cap 310 side. The distance between the first protrusion 231 and the second elastic block 411 is equal to the distance that the latch 440 moves in the second waist groove 236, so that the card seat push rod 230 moves reasonably; The card 430 outside the latch 440 is symmetrically provided with an arc-shaped blocking piece 432. The arc-shaped blocking piece 432 is designed to prevent the latch 440 from being moved due to accidental touch when not in use, thereby releasing the lock of the card seat push rod 230, and further releasing the lock of the automatic injection component, which affects the use of subsequent injections; The first protrusion 231 is fixed to one end of the base push rod 230 that passes through the inner nut 410 and extends into the interior of the button 420. A second elastic block 411 that matches the first protrusion 231 is fixed to the inner nut 410. A second limit ring 421 that matches the second elastic block 411 is fixed to the end of the button 420. The button 420 and the inner nut 410 are connected via a sixth spring 510. Automatic injection principle: First, the latch 440 is pushed into the second waisted round groove 236 to release the lock on the base push rod 230. Under the restoring force of the fourth spring 240, the base push rod 230 moves to the side of the lower pen housing 110. At this time, the first protrusion 231 just fits and abuts against the second elastic block 411, and the arc plate 233 just passes through the arc groove 213 and abuts against the second waisted round piece 131 on the prefilled needle 130. Then, the button 420 is pressed to release the second limiting clamp ring 421 from limiting the second elastic block 411, so that the first protrusion 231, under the restoring force of the fourth spring 240, The second elastic block 411 is squeezed open, and the base push rod 230 will continue to move into the lower pen housing 110, pushing the prefilled needle 130 to move as a whole; until the first limit ring 232 on the base push rod 230 fits with the positioning block 262 on the injection push rod 260, and the first limit ring 232 releases the limit on the first elastic block 221, so that the second convex block 261 squeezes open the first elastic block 221 under the action of the restoring force of the fifth spring 270, so that the injection push rod 260 pushes the liquid medicine inside the prefilled needle 130 under the action of the restoring force of the fifth spring 270, and the liquid medicine injection is realized; Prefilled needle 130 replacement principle: First, insert the new prefilled needle 130 into the cartridge 120 under the cooperation of the second waist round piece 131 and the positioning piece 161 until it is blocked by the hook piece 121; Then, press and hold the button 420, and then push the injection push rod 260 to the bottom inside the upper pen shell 210. The second protrusion 261 on the surface of the injection push rod 260 squeezes the first elastic block 221 and continues to move into the connection rod 220 until it cannot move. At this time, the positioning block 262 on the surface of the injection push rod 260 contacts the first limiting snap ring 232, and continues to push the first limiting snap ring 232 to move, that is, drives the base push rod 230 to move together. In this process, the first limiting snap ring 232 will limit the first elastic block 221 again; at the same time, the first protrusion 231 at the end of the base push rod 230 will squeeze the second elastic block 411 on the inner nut 410 and abut against the button 420. At the same time, The latch 440 in the second waisted groove 236 on the latch groove 234 will move along the second waisted groove 236 to the left end of the first waisted groove 235, and then the button 420 is released, and it returns to its original position under the restoring force of the sixth spring 510, and the second limiting clamp ring 421 limits the second elastic block 411 again, and then the injection push rod 260 is released. At this time, the second protrusion 261 on the injection push rod 260 will retreat to the abutment with the first elastic block 221, and the base push rod 230 will retreat partly under the restoring force of the fourth spring 240, that is, the latch 440 moves from the left end of the first waisted groove 235 to the right end, so as to achieve the locking of the base push rod 230, so as to achieve the reset of the automatic injection assembly; Finally, dock the lower pen shell 110 with the upper pen shell 210 until the lower pen shell 110 and the upper pen shell 210 are completely threadedly connected. At this time, the positioning piece 161 is flush with the second waist round piece 131 and abuts against the partition 211, so that the prefilled needle 130 can be reinstalled after replacement and the injection pen can be recycled.

[0021] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the drawings, or is the orientation or positional relationship commonly understood by those skilled in the art. Such terms are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0022] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the above specific implementation methods. Therefore, any modification or equivalent replacement of the present invention; and all technical solutions and improvements thereof that do not depart from the spirit and scope of the invention are included in the scope of the claims of the present invention.

Claims

1. An automatic injection pen with replaceable prefilled needle, characterized in that: include downPenShell(110); An upper pen housing (210), the upper pen housing (210) and the lower pen housing (110) being threadedly connected; A pen cap (310), the pen cap (310) being engaged with an end portion of the lower pen housing (110); A button assembly, the button assembly comprising an inner nut (410) threadedly connected to the upper pen housing (210), the end of the inner nut (410) being elastically connected to a button (420); and An automatic injection assembly, the automatic injection assembly comprising a holder elastically connected to the interior of the lower pen housing (110), a pre-filled needle (130) being held in the holder; A connecting rod (220) is provided inside the upper pen housing (210), the end of the connecting rod (220) is engaged with the inner nut (410), the outer surface of the connecting rod (220) is elastically connected to a base push rod (230), the inner nut (410) is provided with a latch pin (440), and the surface of the base push rod (230) is provided with a latch pin groove (234) that cooperates with the latch pin (440); A first protrusion (231) is fixed to one side of the base push rod (230) extending into the interior of the button (420); a second elastic block (411) cooperating with the first protrusion (231) is fixed to the interior of the inner nut (410); and a second limit ring (421) cooperating with the second elastic block (411) is fixed to one side of the interior of the button (420); An injection push rod (260) is provided inside the seat push rod (230), and the injection push rod (260) is elastically connected to the connecting rod (220). A first elastic clamping block (221) is provided at the end of the connecting rod (220), and a second protrusion (261) cooperating with the first elastic clamping block (221) is provided on the injection push rod (260). A first limiting clamping ring (232) cooperating with the first elastic clamping ring (221) is provided on the seat push rod (230), and a positioning block (262) cooperating with the first limiting clamping ring (232) is provided on the surface of the injection push rod (260).

2. The replaceable prefilled needle automatic injection pen according to claim 1, characterized in that: A card (430) is fixed to one side of the outer surface of the inner nut (410), and a waist-shaped hole (431) is provided on the card (430), and the latch (440) passes through the waist-shaped hole (431) and is inserted into the latch groove (234); one side of the surface of the latch groove (234) is provided with a first waist-shaped groove (235), and the other side of the surface of the latch groove (234) is provided with a second waist-shaped groove (236), and the first waist-shaped groove (235) and the second waist-shaped groove (236) are connected to each other through an arc-shaped opening transition; the left side of the second waist-shaped groove (236) is aligned with the right side of the first waist-shaped groove (265); the length of the second waist-shaped groove (236) is greater than the length of the first waist-shaped groove (235); the distance between the first protrusion (231) and the second elastic card block (411) is equal to the distance moved by the latch (440) in the second waist-shaped groove (236).

3. The replaceable prefilled needle automatic injection pen according to claim 2, characterized in that: An arc-shaped blocking piece (432) is symmetrically provided on the card (430) outside the latch (440).

4. The replaceable prefilled needle automatic injection pen according to claim 3, characterized in that: The holder comprises a cartridge (120) which is clamped in the interior of the lower pen shell (110); a fixing plate (111) is fixed at one end of the interior of the lower pen shell (110); a first through hole (112) which cooperates with the cartridge (120) is formed on the fixing plate (111); a hook (121) which cooperates with the prefilled needle (130) is fixed on one side of the cartridge (120); a first spring (150) is sleeved on the outer side of the cartridge (120); the inner diameter of the first spring (150) is larger than the outer diameter of the first through hole (112); the first spring (150) is provided on the outer side of the cartridge (120); The end of the prefilled needle (130) is abutted against one side of the septum (140), and the side of the septum (140) away from the first spring (150) is abutted against the second spring (170); the end of the second spring (170) away from the septum (140) is abutted against the gasket (160), and a positioning piece (161) is fixed on the gasket (160); the top of the cartridge (120) is set as a first waist round piece (122) that cooperates with the positioning piece (161), and the end of the prefilled needle (130) is set as a second waist round piece (131) that cooperates with the first waist round piece (122).

5. The replaceable prefilled needle automatic injection pen according to claim 4, characterized in that: A second limiting plate (142) is fixed to one side of the spacer (140) close to the first spring (150); a first limiting plate (141) cooperating with the second spring (170) is fixed to the spacer (140); a positioning groove (115) cooperating with the second limiting plate (142) is provided in the lower pen housing (110); a return stop spring block (123) is provided at the end of the cartridge (120); the return stop spring block (123) is spaced apart from the hook (121).

6. The replaceable prefilled needle automatic injection pen according to claim 5, characterized in that: A partition plate (211) is fixed inside the upper pen shell (120) on one side close to the lower pen shell (110), and a third through hole (212) cooperating with the injection push rod (260) is formed on the partition plate (211); arc grooves (213) are symmetrically formed on the partition plate (211) located on both sides of the third through hole (212), and an arc plate (233) cooperating with the arc groove (213) is fixed to the end of the seat push rod (230); the first waist round piece (122), the second waist round piece (132) and the positioning piece (161) are all in contact with the partition plate (211); and the positioning piece (161) and the arc groove (213) are arranged at a distance.

7. The replaceable prefilled needle automatic injection pen according to claim 6, characterized in that: A fourth spring (240) is in contact with the outer surface of the seat push rod (230) and the outer surface of the connecting rod (220); an insertion rod (250) is provided inside the connecting rod (220), and a fifth spring (270) is sleeved on the outer surface of the insertion rod (250); the fifth spring (270) is inserted into the injection push rod (260) and in contact with the inner wall of the injection push rod (260); the inner nut (410) and the button (420) are connected via a sixth spring (510).

8. The replaceable prefilled needle automatic injection pen according to claim 7, characterized in that: The lower pen housing (110) located outside the fixing plate (111) is elastically connected to a protective cover (180) via a third spring (190); a second through hole (181) cooperating with the prefilled needle (130) is provided on the side of the protective cover (180); the inner diameter of the ring of the third spring (190) is larger than the outer diameter of the second through hole (181); an opening (182) is provided on the surface of the protective cover (180), an elastic slider (183) is fixed on the opening (182), and a sliding groove (113) cooperating with the elastic slider (183) is provided on the surface of the lower pen housing (110).

9. The replaceable prefilled needle automatic injection pen according to claim 8, characterized in that: A limiting protrusion (184) is fixed on the surface of the protective cover (180), and a limiting groove (114) cooperating with the limiting protrusion (184) is provided on the inner wall of the lower pen housing (110).

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