Injection pen

Abstract

Provided is an injection pen, comprising a button mechanism and a dose adjustment mechanism. The button mechanism comprises a button assembly. The button assembly comprises a button body and a button cover, and the button body and the button cover are detachably connected. The dose adjustment mechanism comprises a power rod. The button body comprises a snap engaging part extending downwards, and the snap engaging part is provided with a first limiting surface facing upwards. The power rod comprises a snap hook part extending upwards, and the snap hook part is provided with a second limiting surface facing downwards. The button cover comprises a post part extending downwards, and the post part can be inserted into the inner side of the snap hook part so as to push the snap hook part outwards in the radial direction, such that the first limiting surface and the second limiting surface are kept in an abutting state. By optimizing the mating structures of the button mechanism and the dose adjustment mechanism, the connection reliability of the button mechanism and the dose adjustment mechanism can be ensured.

Description

An injection pen

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 16, 2024, with application number 202410058059.X and invention name “A Injection Pen”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of medical devices, and in particular to an injection pen. Background Art

[0003] Insulin injection therapy is the most commonly used treatment in clinical practice. This has led to the development of reusable insulin pens, which can precisely adjust the dosage simply by replacing the insulin cartridge. In addition to insulin injection, injection pens can also be used to administer other medications.

[0004] In the related art, the injection pen includes an upper pen barrel assembly and a lower pen cap. The upper pen barrel assembly includes a button mechanism, a dose adjustment mechanism and a transmission mechanism. The lower pen cap is used to install a cartridge bottle. Kinetic energy can be stored by operating the dose adjustment mechanism. When the button mechanism is pressed, the kinetic energy stored in the dose adjustment mechanism can be released, and the cartridge bottle stopper is pushed through the transmission mechanism to achieve drug injection.

[0005] In actual applications, it is found that the matching structure between the existing button mechanism and the dose adjustment mechanism is easy to loosen, and the button of the button mechanism is easy to loosen, causing the injection pen to be unusable. Summary of the Invention

[0006] The purpose of the present application is to provide an injection pen, which can ensure the reliability of the connection between the button mechanism and the dose adjustment mechanism by optimizing the matching structure of the button mechanism and the dose adjustment mechanism.

[0007] To solve the above technical problems, the present application provides an injection pen, comprising a button mechanism and a dose adjustment mechanism, wherein the button mechanism comprises a button assembly, the button assembly comprises a button body and a button cover, the button body and the button cover being detachably connected; the dose adjustment mechanism comprises a power rod;

[0008] The button body includes a clamping portion extending downward, and the clamping portion has a first limiting surface facing upward; the power rod includes a hook portion extending upward, and the hook portion has a second limiting surface facing downward;

[0009] The button cover includes a column portion extending downward, and the column portion can be inserted into the inner side of the hook portion to push the hook portion radially outward, so that the first limiting surface and the second limiting surface maintain an abutting state.

[0010] In one achievable manner, the power rod is provided with more than two hook portions, and each hook portion is arranged at intervals along the circumferential direction; the hook portion includes a rod portion and a hook portion provided at the top end of the rod portion, and the top end of the rod portion extends radially outward to form the hook portion.

[0011] In one achievable manner, the bottom ends of the rod portions of the hook portions are connected as a whole via a connecting portion, and the top sections of the rod portions have elastic deformation capability in the radial direction.

[0012] In one achievable manner, the top end of the inner wall of the rod portion has an inclined guide surface for guiding the insertion of the column portion.

[0013] In one achievable manner, the hook portions are arranged around the central axis of the power rod; and the central axis of the column portion coincides with the central axis of the power rod.

[0014] In one achievable manner, a middle area of ​​the button body is recessed downward to form the engaging portion, the engaging portion has a through hole for the hook portion to pass through, and the first limiting surface is an annular surface.

[0015] In one achievable manner, the column portion is a hollow structure.

[0016] In one achievable manner, the button body and the button cover are detachably connected by snapping.

[0017] In one possible implementation, the injection pen further comprises a knob assembly, wherein a circumferential limiting structure is provided between the knob assembly and the power rod, and when the knob assembly rotates, the power rod can be driven to rotate via the circumferential limiting structure;

[0018] The button assembly is slidably connected to the knob assembly along the axial direction. When the button assembly moves downward relative to the knob assembly, it can drive the power rod to move downward to release the circumferential limitation of the power rod and the knob assembly.

[0019] In one achievable manner, the button mechanism further includes a reset elastic member, and the reset elastic member is disposed between the button assembly and the knob assembly.

[0020] After adopting the above solution, the hook portion of the power rod can be extended into the clamping portion of the button body. After the button cover is detachably connected to the button body, the column portion of the button cover can be inserted into the inner side of the hook portion, pushing the hook portion radially outward so that the second limiting surface of the hook portion and the first limiting surface of the clamping portion remain in abutment. In this way, under the cooperation of the clamping portion and the hook portion, the relative position of the button body and the power rod in the axial direction is limited. When the button assembly is pressed downward, the power rod can be driven downward together. At the same time, the column portion of the button cover is inserted into the inner side of the hook portion, so that the hook portion and the clamping portion can always remain in abutment, thereby ensuring the reliability of the axial limit of the power rod and the button assembly, and effectively preventing the hook portion of the power rod from being separated from the clamping portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic structural diagram of an injection pen according to an embodiment of the present application;

[0022] FIG2 is a schematic cross-sectional view of the injection pen shown in FIG1 ;

[0023] FIG3 is a partial enlarged view of the area where the upper pen holder assembly is located in FIG2;

[0024] FIG4 is a cross-sectional view of the button assembly and the power rod after assembly in a specific embodiment;

[0025] FIG5 is a partial enlarged view of portion A in FIG4 ;

[0026] FIG6 is a schematic structural diagram of a button body in a specific embodiment;

[0027] FIG7 is a schematic cross-sectional view of the button body shown in FIG6 ;

[0028] FIG8 is a schematic structural diagram of a button cover in a specific embodiment at one viewing angle;

[0029] FIG9 is a schematic structural diagram of the button cover in another perspective in a specific embodiment;

[0030] FIG10 is a schematic structural diagram of a power rod in a specific embodiment.

[0031] Explanation of Reference Numerals: Injection pen 100, upper barrel assembly 10, lower cap assembly 20; upper barrel 11, display window 111; button mechanism 12, button body 121, engaging portion 1211, first limiting surface 12111, through hole 1212, bayonet 1213, boss 1214, button cover 122, column 1221, buckle 1222, notch 1223, resetting elastic member 123; Dose adjustment mechanism 13, knob assembly 131, knob 1311, stop bracket 1312, first inner gear ring 13121, power rod 132, first latching tooth 1324, hook portion 1325, second limiting surface 13251, rod portion 13252, hook portion 13253, guide surface 13254, hole portion 1326, connecting portion 1327, barrel 133, ball bearing 134, sleeve 135, torsion spring 136, torsion spring bracket 137, scale plate 138; transmission mechanism 14, drive wheel 141, screw 142, bottle holder cover 143; lower pen cap 21, bottle holder 22, cartridge bottle 23, bottle stopper 231. DETAILED DESCRIPTION

[0032] An embodiment of the present application provides an injection pen, which can ensure the reliability of the connection between the button mechanism and the dose adjustment mechanism by optimizing the matching structure of the button mechanism and the dose adjustment mechanism, thereby improving the reliability of the injection pen.

[0033] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0034] In this document, the side of the injection pen where the button mechanism is located is defined as "up." Accordingly, the side of the injection pen, or the side closest to the injection site during use, is defined as "down." The longitudinal direction of the injection pen is defined as the axial direction, with the side closest to the center of the pen being defined as "inner," and the side further from the center being defined as "outer." It should be understood that the use of these directional terms is solely for ease of description and understanding and does not constitute a limitation on the scope of protection.

[0035] Please refer to Figures 1 to 3, Figure 1 is a structural schematic diagram of an injection pen in an embodiment provided in the present application; Figure 2 is a cross-sectional schematic diagram of the injection pen shown in Figure 1; and Figure 3 is a partial enlarged view of the area where the upper pen barrel assembly is located in Figure 2.

[0036] In this embodiment, the injection pen 100 includes an upper pen barrel assembly 10 and a lower pen cap assembly 20 .

[0037] The upper pen barrel assembly 10 includes an upper pen barrel 11 , a button mechanism 12 , a dose adjustment mechanism 13 and a transmission mechanism 14 . The upper pen barrel 11 serves as a mounting base for the button mechanism 12 , the dose adjustment mechanism 13 and the transmission mechanism 14 .

[0038] The lower pen cap assembly 20 includes a lower pen cap 21, a bottle holder 22 and a cartridge bottle 23. The bottle holder 22 is inserted into the lower pen cap 21 for mounting the cartridge bottle 23. The upper end of the bottle holder 22 extends out of the lower pen cap 21 for sleeve engagement with the upper pen barrel 11. The lower end of the upper pen barrel 11 is sleeved onto the upper end of the bottle holder 22.

[0039] The transmission mechanism 14 in the upper pen barrel 11 can cooperate with the bottle stopper 231 of the cartridge bottle 23, and the dosage adjustment mechanism 13 can provide driving force to the transmission mechanism 14, so that the transmission mechanism 14 pushes the bottle stopper 231 to move downward to achieve drug injection.

[0040] It should be noted that the cartridge 23 is a container for storing medicine, which is not essentially part of the injection pen 100 and is used in conjunction with the injection pen 100. In use, the cartridge 23 is a replaceable component.

[0041] In this embodiment, the dose adjustment mechanism 13 includes a knob assembly 131 , a power rod 132 , a barrel 133 , a ball 134 , a sleeve 135 and a torsion spring 136 .

[0042] A circumferential restraining structure is provided between the power rod 132 and the knob assembly 131. Under the action of the aforementioned button mechanism 12, the power rod 132 can also move axially to release or restore the circumferential restraint between the power rod 132 and the knob assembly 131. Specifically, the power rod 132 can be moved axially downward to release the circumferential restraint between the power rod 132 and the knob assembly 131. The power rod 132 can also be reset, that is, after moving axially downward, it can be moved axially upward to restore the circumferential restraint between the power rod 132 and the knob assembly 131. Axial movement of the power rod 132 can be achieved by operating the button mechanism 12.

[0043] The power rod 132 is inserted into the cylinder 133. A spiral channel extending along the axial direction of the power rod 132 is formed between the inner wall of the cylinder 133 and the outer wall of the power rod 132. The ball 134 is rollably arranged in the spiral channel. The axial direction of the power rod 132 is consistent with the axial direction of the injection pen 100.

[0044] The cylinder 133 is relatively fixed to the upper pen barrel 11 in the circumferential direction; the upper end of the torsion spring 136 is relatively fixed to the upper pen barrel 11, and the lower end of the torsion spring 136 is connected to the sleeve 135.

[0045] The power rod 132 and the sleeve 135 are relatively fixed. In other words, the power rod 132 and the sleeve 135 cannot rotate relative to each other but can rotate together.

[0046] The sleeve 135 and the transmission mechanism 14 can switch between a transmission engagement state and a transmission release separation state. In other words, when the sleeve 135 and the transmission mechanism 14 are in a transmission engagement state, power transmission can be achieved between the two. When the sleeve 135 and the transmission mechanism 14 are in a transmission release state, power transmission cannot be achieved between the two.

[0047] In a specific configuration, the sleeve 135 is engaged with and separated from the transmission mechanism 14 by axial movement of the sleeve 135 .

[0048] Specifically, the transmission mechanism 14 includes a drive wheel 141, a screw 142, and a bottle holder cover 143. The drive wheel 141 can be engaged or disengaged with the sleeve 135. The screw 142 is circumferentially limited to the drive wheel 141 and is threadedly connected to the bottle holder cover 143. The lower end of the screw 142 passes through the bottle holder cover 143 and can abut the bottle stopper 231. Typically, a gasket is provided between the screw 142 and the bottle stopper 231.

[0049] A clutch structure is provided between the driving wheel 141 and the sleeve 135. When the sleeve 135 moves axially downward, the sleeve 135 and the driving wheel 141 are in an engaged state, so that the sleeve 135 can drive the driving wheel 141 to rotate together. When the sleeve 135 moves axially upward, the sleeve 135 and the driving wheel 141 are in a separated state, so that the rotation of the sleeve 135 does not affect the driving wheel 141.

[0050] Since the sleeve 135 is relatively fixed to the power rod 132, when the button mechanism 12 is operated, the power rod 132 and the sleeve 135 can be driven to move downward in the axial direction together, thereby realizing the transmission engagement of the sleeve 135 and the driving wheel 141. Under the action of the button mechanism 12, the power rod 132 and the sleeve 135 also move upward in the axial direction together, thereby realizing the separation of the sleeve 135 and the driving wheel 141.

[0051] FIG2 and FIG3 show the structure of the injection pen 100 in a normal state. The normal state mentioned here and above refers to the relative position relationship state of various structures of the injection pen 100 when the injection pen 100 is not operated.

[0052] In a specific implementation, the button mechanism 12 includes a button assembly and a resilient reset member 123. The resilient reset member 123 is disposed between the button assembly and the knob assembly 131. The knob assembly 131 maintains a constant axial position relative to the injection pen 100. Pressing the button assembly causes the power rod 132 and sleeve 135 to move axially downward. During this process, the resilient reset member 123 is compressed and stores energy. Once the pressing force on the button assembly is released, the resilient reset member 123 allows the power rod 132 and sleeve 135 to move axially upward to reset.

[0053] In a specific implementation, the dose adjustment mechanism 13 also includes a dial 138, which is externally mounted on the sleeve 135. The sleeve 135 and the dial 138 are circumferentially limited. The outer side of the dial 138 is the upper pen barrel 11, which has a display window 111. When adjusting the dose, the dial 138 can rotate with the sleeve 135, so that the user can determine the adjusted dose size by the scale on the dial 138 displayed in the display window 111.

[0054] In a specific implementation, the dose adjustment mechanism 13 of the injection pen 100 further includes a torsion spring bracket 137. The torsion spring bracket 137 is fixed relative to the upper barrel 11, and the upper end of the torsion spring 136 can be specifically connected to the torsion spring bracket 137. The barrel 133 is internally sleeved within the torsion spring bracket 137, and the barrel 133 can be fixed relative to the upper barrel 11 by being fixed relative to the torsion spring bracket 137.

[0055] The relative fixing method between the torsion spring bracket 137 and the upper pen holder 11 and the relative fixing method between the barrel 133 and the torsion spring bracket 137 can adopt a snap-fit ​​structure, etc., which is convenient for disassembly and assembly and is conducive to maintenance.

[0056] In a specific implementation, a limiting structure is provided between the knob assembly 131 and the torsion spring bracket 137. This limiting structure allows the knob assembly 131 to rotate in only one direction relative to the torsion spring bracket 137, but not in the opposite direction. In the structural configuration of the injection pen 100, the knob assembly 131 can rotate relative to the torsion spring bracket 137 in the direction of adjusting the dosage, but cannot rotate in the opposite direction.

[0057] For example, the limiting structure between the knob assembly 131 and the torsion spring bracket 137 can be a one-way ratchet and ratchet tooth matching structure.

[0058] Hereinafter, the rotation in the direction of adjusting the dosage is referred to as forward rotation, and the rotation opposite to the direction of adjusting the dosage is referred to as reverse rotation.

[0059] The drug injection operation of the injection pen 100 can be divided into a dose adjustment phase and an injection phase.

[0060] During the dose adjustment stage, the user can rotate the knob assembly 131 in the forward direction to drive the power rod 132 to rotate, and the power rod 132 drives the sleeve 135 and the torsion spring 136 to rotate together, so that the torsion spring 136 stores energy; during this process, the adjusted dose can be judged through the display window 111 of the upper pen barrel 11; after adjusting the dose and canceling the force on the knob assembly 131, the knob assembly 131 can be maintained in this position under the action of the limiting structure between the knob assembly 131 and the torsion spring bracket 137, and accordingly, the power rod 132, sleeve 135 and torsion spring 136 that are circumferentially limited with the knob assembly 131 are all maintained in this position.

[0061] During the injection stage, the button assembly of the button mechanism 12 is pressed downward, pushing the power rod 132 to move axially downward, and the power rod 132 drives the sleeve 135 to move downward together, so that the sleeve 135 engages with the driving wheel 141 of the transmission mechanism 14, and at the same time the power rod 132 disengages from the circumferential limit of the stop bracket 1312, so that the stored energy of the torsion spring 136 is released. Under the action of the torsion spring 136 releasing the stored energy, the sleeve 135 and the power rod 132 rotate in the opposite direction together, and the driving wheel 141 engaged with the sleeve 135 rotates together, driving the screw 142 to rotate together. When the screw 142 rotates, under the threaded cooperation with the bottle holder cover 143, the screw 142 also moves axially downward to push the bottle stopper 231 to realize drug injection.

[0062] The button assembly of button mechanism 12 is connected to the power rod 132 at an upper axial limit position, so that when the button assembly is pressed, it can drive the power rod 132 downward along the axial direction. This article focuses on improving the connection structure between the button assembly and the power rod 132 to ensure the reliability of the connection between the two. This is the focus of the following description.

[0063] Please refer to Figures 4 to 10 together. Figure 4 is a cross-sectional schematic diagram of the button assembly and the power rod after assembly in a specific embodiment; Figure 5 is a partial enlarged view of part A in Figure 4; Figure 6 is a structural schematic diagram of the button body in a specific embodiment; Figure 7 is a cross-sectional schematic diagram of the button body shown in Figure 6; Figure 8 is a structural schematic diagram of the button cover in a specific embodiment from one perspective; Figure 9 is a structural schematic diagram of the button cover in a specific embodiment from another perspective; Figure 10 is a structural schematic diagram of the power rod in a specific embodiment.

[0064] In this embodiment, the button assembly of the button mechanism 12 includes a button body 121 and a button cover 122 , and the button body 121 and the button cover 122 are detachably connected.

[0065] The button body 121 includes a downwardly extending engaging portion 1211 , which has an upwardly facing first limiting surface 12111 . The power rod 132 includes an upwardly extending hook portion 1325 , which has a downwardly facing second limiting surface 13251 .

[0066] The button cover 122 includes a downwardly extending post 1221 that can be inserted into the inner side of the hook portion 1325 to push the hook portion 1325 radially outward, so that the second limiting surface 13251 of the hook portion 1325 maintains an abutting state with the first limiting surface 12111 of the engaging portion 1211. It will be appreciated that the hook portion 1325 has radially movable space to ensure that the post 1221 can push the hook portion 1325 outward.

[0067] With the above solution, the hook portion 1325 of the power rod 132 can be inserted into the engaging portion 1211 of the button body 121. After the button cover 122 is detachably connected to the button body 121, the column portion 1221 of the button cover 122 can be inserted into the inner side of the hook portion 1325, pushing the hook portion 1325 radially outward so that the second limiting surface 13251 of the hook portion 1325 maintains an abutting state with the first limiting surface 12111 of the engaging portion 1211. In this way, the engaging portion 1211 and the hook portion 1325 cooperate to limit the relative axial position of the button body 121 and the power rod 132. When the button assembly is pressed downward, the power rod 132 can be driven downward together. At the same time, the column portion 1221 of the button cover 122 is inserted into the inner side of the hook portion 1325, so that the hook portion 1325 and the clamping portion 1211 can always maintain an abutment state, thereby ensuring the reliability of the axial upper limit of the power rod 132 and the button assembly, and effectively preventing the hook portion 1325 of the power rod 132 from detaching from the clamping portion 1211.

[0068] In a specific implementation, the power rod 132 is provided with more than two hook portions 1325, and each hook portion 1325 is arranged at intervals along the circumferential direction; each hook portion 1325 includes a rod portion 13252 and a hook portion 13253 provided at the top end of the rod portion 13252, and the top end of the rod portion 13252 extends radially outward to form the hook portion 13253; each hook portion 1325 is surrounded to form a hole portion 1326. During assembly, the column portion 1221 of the button cover 122 can be inserted into the hole portion 1326 surrounded by each hook portion 1325 to push all the rod portions 13252 radially outward, so that all the hook portions 13253 can abut against the clamping portion 1211 for limiting position.

[0069] In specific configuration, the bottom ends of the hook portions 1325 of the power rod 132 are connected as a whole via a connecting portion 1327, as can be understood with reference to FIG10 . This improves the connection strength between each hook portion 1325 and the main body of the power rod 132. A notch extending through the top surface of the power rod 132 is defined between two adjacent rod portions 13252, allowing the top section of each rod portion 13252 to move radially, facilitating the column portion 1221 to push against the rod portion 13252 until the hook portion 13253 abuts the engaging portion 1211.

[0070] Specifically, the top section of the rod portion 13252 has elastic deformation capability in the radial direction. On the one hand, it can reduce the problem of stress concentration in the rod portion 13252 caused by the push of the column portion 1221, thereby affecting the structural strength. On the other hand, it is convenient for the disassembly between the button mechanism 12 and the power rod 132. After removing the button cover 122, it is convenient for each rod portion 13252 to move radially inward for resetting, which is convenient for the power rod 132 to separate from the button body 121. In this way, it can be disassembled without damaging the button mechanism 12, which is convenient for maintenance.

[0071] In a specific implementation, the central region of the button body 121 is recessed downward to form a snap-fit ​​portion 1211. This snap-fit ​​portion 1211 has a through-hole 1212 for the hook portion 1325 to pass through. The first limiting surface 12111 of the snap-fit ​​portion 1211 is an annular surface. This eliminates the need to adjust the circumferential relative position between the power rod 132 and the button body 121 during assembly. After passing through the through-hole 1212 of the snap-fit ​​portion 1211, each hook portion 1325 of the power rod 132 can abut against the first limiting surface 12111.

[0072] In the illustrated example, the power rod 132 is provided with four hook portions 1325 spaced apart along the circumference. In other implementations, the number of the hook portions 1325 can be adjusted as needed.

[0073] In a specific implementation, the hook portions 1325 are arranged around the central axis of the power rod 132, and the central axis of the column portion 1221 coincides with the central axis of the power rod 132. This facilitates the balanced thrust applied by the column portion 1221 to the hook portions 1325 in the radial outward movement, ensuring that each hook portion 1325 maintains a good abutment with the engaging portion 1211.

[0074] In a specific implementation, the top of the inner wall of the rod portion 13252 of the hook portion 1325 has an inclined guide surface 13254 to guide the insertion of the column portion 1221, thereby facilitating the insertion and fitting between the column portion 1221 and the power rod 132 when the button cover 122 is assembled.

[0075] In a specific implementation, the column portion 1221 of the button cover 122 may be a hollow structure to save materials and reduce the weight of the button cover 122 .

[0076] In a specific implementation, the detachable connection between the button cover 122 and the button body 121 can be achieved by a snap-fit ​​method. Specifically, a snap-fit ​​notch 1213 can be provided on the button body 121, and a buckle 1222 can be provided on the button cover 122 to snap into the snap-fit ​​notch 1213. The button cover 122 can be snapped onto the button body 121. During snapping, the buckle 1222 of the button cover 122 can extend into the snap-fit ​​notch 1213 under the action of an external force and abut against the downward-facing inner end surface of the button body 121, thereby limiting the relative position of the button cover 122 and the button body 121.

[0077] In the illustrated example, four sets of matching buckles 1222 and bayonet holes 1213 are provided between the button cover 122 and the button body 121. These four sets of matching buckles 1222 and bayonet holes 1213 are evenly spaced along the circumference to ensure a relatively uniform latching force between the button cover 122 and the button body 121, thereby enhancing the secure connection between the two.

[0078] In other implementations, the number of the buckles 1222 and the bayonet 1213 that match each other between the button cover 122 and the button body 121 may also be set to other numbers, such as two or three groups.

[0079] In other implementations, the snap connection between the button cover 122 and the button body 121 may also be achieved in other ways. For example, a snap portion that can press the button cover 122 downward may be provided on the outer edge of the button body 121. The snap portion can be rotated relative to the button body 121 to switch between a position that presses the button cover 122 and a position that releases the pressure on the button cover 122.

[0080] In this embodiment, a foolproof structure may be provided between the button cover 122 and the button body 121 to facilitate identification of the circumferential relative position of the button cover 122 and the button body 121 during assembly. It should be noted that if the mating structure between the button cover 122 and the button body 121 is centrally symmetrical, the circumferential relative position of the two does not affect their assembly, and in this case, the foolproof structure may not be provided.

[0081] In one possible implementation, the fool-proof structure may include a notch 1223 formed on the outer edge of the button cover 122 and a boss 1214 provided on the outer edge of the button body 121. The notch 1223 is adapted to the boss 1214. When the button cover 122 is buckled onto the button body 121, the boss 1214 is located in the notch 1223.

[0082] In this embodiment, to facilitate pressing the button assembly of the button mechanism 12 , the button assembly and the aforementioned knob assembly 131 are slidably connected along the axial direction. The reset elastic member 123 of the button mechanism 12 is disposed between the button assembly and the knob assembly 131 .

[0083] The resetting elastic member 123 may be a spring or the like.

[0084] In this embodiment, the knob assembly 131 includes a knob 1311 and a stop bracket 1312. The knob 1311 and the stop bracket 1312 are circumferentially limitedly connected. Part of the stop bracket 1312 is internally mounted on the knob 1311, and the lower end of the knob 1311 is rotatably mounted on the upper pen holder 11.

[0085] In one practicable manner, the power rod 132 passes through the stop bracket 1312 , and a circumferential limiting structure is provided between the power rod 132 and the stop bracket 1312 .

[0086] Specifically, the circumferential limiting structure between the stop bracket 1312 and the power rod 132 includes a first inner gear ring portion 13121 provided on the stop bracket 1312, and a first latching tooth 1324 provided on the outer wall of the power rod 132. Under normal conditions, the first latching tooth 1324 of the power rod 132 can be embedded in the tooth groove of the first inner gear ring portion 13121, thereby limiting the circumferential position of the power rod 132 and the stop bracket 1312, so that when the stop bracket 1312 rotates, it can drive the power rod 132 to rotate together.

[0087] In actual configuration, the number of the first latching teeth 1324 of the power rod 132 can be set as needed, such as two or three or more. The multiple first latching teeth 1324 are preferably evenly arranged along the circumference to balance the force between the power rod 132 and the stop bracket 1312.

[0088] In other implementations, a circumferential limiting structure may also be provided between the power rod 132 and the knob 1311 .

[0089] During use, the user can rotate the knob 1311 to drive the stop bracket 1312 and the power rod 132 to rotate together to adjust the dosage.

[0090] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core ideas of this application. It should be noted that for those skilled in the art, without departing from the principles of this application, various improvements and modifications can be made to this application, and such improvements and modifications also fall within the scope of protection of the claims of this application.

Claims

1. An injection pen, comprising a button mechanism and a dose adjustment mechanism, characterized in that, The button mechanism includes a button assembly, the button assembly includes a button body and a button cover, and the button body and the button cover are detachably connected; the dose adjustment mechanism includes a power rod; The button body includes a clamping portion extending downward, and the clamping portion has an upward first limiting surface; the power rod includes a hook portion extending upward, and the hook portion has a downward second limiting surface; The button cover includes a column portion extending downward, and the column portion can be inserted into the inner side of the hook portion to push the hook portion radially outward, so that the first limiting surface and the second limiting surface are kept in contact with each other.

2. The injection pen according to claim 1, characterized in that, Two or more of the hook portions are provided on the power rod, and the hook portions are arranged at intervals in the circumferential direction; the hook portion includes a rod portion and a hook portion provided at the top end of the rod portion, and the top end of the rod portion extends radially outward to form the hook portion.

3. The injection pen according to claim 2, wherein, The bottom ends of the rod portions of the hook portions are connected into one body through a connecting portion, and the top section of the rod portion has an elastic deformation ability in the radial direction.

4. The injection pen according to claim 2, characterized in that, The inner wall top end of the rod portion has an inclined guiding surface for guiding the insertion of the column portion.

5. The injection pen according to any one of claims 2 to 4, characterized in that, Each of the hook portions is arranged around the central axis of the power rod; the central axis of the column portion coincides with the central axis of the power rod.

6. The injection pen according to any one of claims 1-4, characterized in that A middle area of the button body is recessed downward to form the clamping portion, the clamping portion has a through hole for the hook portion to pass through, and the first limiting surface is an annular surface.

7. The injection pen according to any one of claims 1-4, characterized in that, The column portion is a hollow structure.

8. The injection pen according to any one of claims 1 to 4, characterized in that, The button body and the button cover are detachably connected by a clamping method.

9. The injection pen according to any one of claims 1-4, characterized in that, The injection pen further includes a knob assembly, a circumferential limiting structure is provided between the knob assembly and the power rod, and when the knob assembly rotates, it can drive the power rod to rotate through the circumferential limiting structure; The button assembly and the knob assembly are slidably connected in the axial direction, and when the button assembly moves downward relative to the knob assembly, it can drive the power rod to move downward to release the circumferential limit between the power rod and the knob assembly.

10. The injection pen according to claim 9, characterized in that, The button mechanism further includes a reset elastic member, and the reset elastic member is arranged between the button assembly and the knob assembly.

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