INJECTOR 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

1 / 18 “INJECTOR PEN”

[001] This application claims priority over Chinese patent application no. 202410058059.X, entitled INJECTION PEN, filed on January 16, 2024 with the National Intellectual Property Administration of China, which is incorporated herein by reference in its entirety. FIELD

[002] This application relates to the technical field of medical instruments and, in particular, to an injector pen. FUNDAMENTALS

[003] Insulin injection therapy is a treatment method most commonly used in clinical work and, consequently, an injector pen was created to inject insulin. The injector pen can be used repeatedly and can precisely adjust the injection dosage, and only one cartridge containing insulin needs to be replaced. In addition to insulin, the injector pen can also be used to inject other drugs.

[004] In the related technique, the injector pen includes an upper pen tube assembly and a lower pen cap. The upper pen tube assembly includes a push-button mechanism, a dosage adjustment mechanism, and a transmission mechanism, and the lower pen cap is configured to be mounted on a cartridge. Kinetic energy can be stored by operating the dosage adjustment mechanism, and the kinetic energy stored in the dosage adjustment mechanism can be released when the push-button mechanism is pressed, so as to push the cartridge plunger through the transmission mechanism, thus performing the drug injection.

[005] In practice, it has been found that the engagement structure of the existing button mechanism and dosage adjustment mechanism tends to come loose, and the button of the button mechanism tends to come loose, making the injector pen unusable. SUMMARY Petition 870250073148, dated 08 / 19 / 2025, page 34 / 66 2 / 18

[006] One of the objectives of the present application is to provide an injector pen that can guarantee the reliability of the connection between a push-button mechanism and a dosage adjustment mechanism, by optimizing the engagement structure of the push-button mechanism and the dosage adjustment mechanism.

[007] To solve the above technical problem, an injector pen is provided, including a button mechanism and a dosage adjustment mechanism. The button mechanism includes a button assembly comprising a button body and a button cap detachably connected to each other. The dosage adjustment mechanism includes a power lever.

[008] The button body includes an engagement portion that extends downward, and the engagement portion has a first limiting surface facing upward. The power lever includes a hook portion that extends upward, and the hook portion has a second limiting surface facing downward.

[009] The button cover includes a pin portion that extends downward, and the pin portion can be inserted into the hook portion to push the hook portion outward in a radial direction, so that the second limiting surface comes into contact with the first limiting surface.

[010] In one implementation, the power lever is provided with two or more hook portions, arranged at intervals in a circumferential direction. The hook portion includes a rod portion and a hook provided at an upper end of the rod portion, and the upper end of the rod portion extends outward in the radial direction to form the hook.

[011] In one implementation, the lower ends of the rod portions of the hook portions are connected by means of a connecting portion in an integrated structure, and an upper section of the rod portion has elastic deformation capability in the radial direction.

[012] In one implementation, an inclined guide surface is provided at an upper end of an inner wall of the rod portion of the hook portion and configured to guide the insertion of the rod portion. Petition 870250073148, dated 08 / 19 / 2025, page 35 / 66 3 / 18

[013] In one implementation, the hook portions are arranged around a central axis of the power lever, and a central axis of the rod portion coincides with the central axis of the power lever.

[014] In one implementation, a central region of the button body is recessed to form the engagement portion. The engagement portion has a through hole through which the hook portion passes, and the first bounding surface is an annular surface.

[015] In one implementation, the rod portion has a hollow structure.

[016] In one implementation, the button cover is detachably attached to the button body via a quick snap-fit ​​mechanism.

[017] In one implementation, the injector pen further includes a selector assembly. A circumferential limiting structure is provided between the selector assembly and the power lever and is configured to allow the selector assembly to cause the power lever to rotate when the selector assembly rotates.

[018] The button assembly is connected to the selector assembly so as to be sliding in an axial direction and is configured to cause the power lever to move downward when the button assembly moves downward relative to the selector assembly, so as to release the circumferential limit between the power lever and the selector assembly.

[019] In one implementation, the button mechanism further includes a return elastic member, which is provided between the button assembly and the selector assembly.

[020] With the above solution, the hook portion of the power lever can extend to the engagement portion of the button body. After the button cover is detachably connected to the button body, the rod portion of the button cover can be inserted into the hook portion, and the hook portion will be pushed out in the radial direction, so that the second limiting surface of the hook portion touches the first limiting surface of the engagement portion. In this way, under the engagement between the engagement portion and the hook portion, the relative position of the button body and the power lever in the axial direction is limited and, Petition 870250073148, dated 08 / 19 / 2025, page 36 / 66 4 / 18 When the button assembly is pressed down, the power lever can be moved down along with the button assembly. Furthermore, the rod portion of the button cover is inserted inside the hook portion, so that the hook portion always rests against the engagement portion, thus ensuring the reliability of the axial limit between the power lever and the button assembly and effectively preventing the hook portion of the power lever from detaching from the engagement portion. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic structural view of an injector pen according to an embodiment of the present application; FIG. 2 is a schematic cross-sectional view of the injector pen shown in FIG. 1; FIG. 3 is a partial enlarged view of the area where an upper pen tube assembly is located in FIG. 2; FIG. 4 is a schematic cutaway view of an assembly of a button and a power lever in one embodiment; FIG. 5 is an enlarged partial view of part A of FIG. 4; FIG. 6 is a schematic structural view of a button body in one embodiment; FIG. 7 is a schematic cross-sectional view of the button body shown in FIG. 6; FIG. 8 is a schematic structural perspective view of a button cover in one embodiment; FIG. 9 is another schematic perspective structural view of a button cover in one embodiment; and FIG. 10 is a schematic structural view of a power lever in one embodiment.

[021] List of reference numbers: 100. injector pen; 10. upper pen tube assembly; Petition 870250073148, dated 08 / 19 / 2025, page 37 / 66 5 / 18 20. Lower pen cap assembly; 11. Upper pen tube; 111. Display window; 12. button mechanism; 121. button body; 1211. engagement portion; 12111. first limiting surface; 1212. passage hole; 1213. coupling opening; 1214. protrusion; 122. button cover; 1221. pin portion; 1222. fitting; 1223. notch; 123. elastic return member; 13. Dosage adjustment mechanism; 131. Selector assembly; 1311. Selector; 1312. stop support; 13121. first portion of inner toothed ring; 132. power lever; 1324. first tooth; 1325. hook portion; 13251. second limiting surface; 13252. rod portion; 13253. hook; 13254. guide surface; 1326. orifice portion; 1327. connecting portion; 133. cylinder; 134. sphere; 135. glove; 136. torsion spring; 137. torsion spring support; 138. dial; 14. transmission mechanism; 141. drive wheel; 142. screw; 143. cartridge support cover; 21. Bottom pen cap; 22. cartridge support; 23. carpule; 231. carpule plunger. DETAILED DESCRIPTION OF THE MODALITIES

[022] An injector pen is provided according to an embodiment of the present application, in which the reliability of the connection between the button mechanism and the dosage adjustment mechanism can be ensured by optimizing the structure. Petition 870250073148, dated 08 / 19 / 2025, page 38 / 66 6 / 18 matching of a button mechanism and a dosage adjustment mechanism, in order to improve the reliability of use of the injector pen.

[023] In order for those skilled in the art to better understand the solutions of the present application, it will be described in more detail below, together with the accompanying drawings and specific embodiments.

[024] Here, the side on which the injector pen's push-button mechanism is located is defined as the top, and correspondingly, the side on which the injector pen's injection tip is located, or the side near an injection site when in use, is defined as the bottom. The direction of the injector pen's length is defined as an axial direction, and the side near the center of the injector pen is defined as the inside, and correspondingly, the side away from the center of the injector pen is defined as the outside. It may be understood that the orientation terms are used only to facilitate description and understanding, and do not constitute a limitation to the scope of protection.

[025] With regard to FIGS. 1 to 3, FIG. 1 is a schematic structural view of an injector pen according to an embodiment of the present application; FIG. 2 is a schematic cutaway view of the injector pen shown in FIG. 1; and FIG. 3 is an enlarged partial view of the area where an upper pen tube assembly is located in FIG. 2.

[026] In this embodiment, an injector pen 100 includes an upper pen tube assembly 10 and a lower pen cap assembly 20.

[027] The top pen tube set 10 includes one top pen tube 11, a button mechanism 12, a dosage adjustment mechanism 13, and a transmission mechanism 14. The upper pen tube 11 serves as a base for mounting the button mechanism 12, the dosage adjustment mechanism 13, and the transmission mechanism 14.

[028] The lower pen cap assembly 20 includes a lower pen cap 21, a carpule holder 22, and a carpule 23. The carpule holder 22 is inserted into the lower pen cap 21 and configured to mount onto the carpule 23. A Petition 870250073148, dated 08 / 19 / 2025, page 39 / 66 7 / 18 upper end of carpule holder 22 extends out of lower pen cap 21 to be engaged or connected to upper pen tube 11 and is received at a lower end of upper pen tube 11.

[029] The transmission mechanism 14 in the upper pen tube 11 can be cooperated with a carpule plunger 231 of the carpule 23, and the dosage adjustment mechanism 13 can provide a driving force to the transmission mechanism 14, so that the transmission mechanism 14 pushes the carpule plunger 231 down to perform the injection of the drug.

[030] It should be noted that cartridge 23 is a container for storing a drug, which is not essentially a component of the injector pen 100 and is used in conjunction with the injector pen 100. In one application, cartridge 23 is a replaceable component.

[031] In this embodiment, the dosing adjustment mechanism 13 includes a selector assembly 131, a power lever 132, a cylinder 133, a ball 134, a sleeve 135 and a torsion spring 136.

[032] A circumferential limiting structure is provided between the power lever 132 and the selector assembly 131. The power lever 132 can be moved in an axial direction by the button mechanism 12 to release a circumferential limiting state between the power lever 132 and the selector assembly 131 or to restore the circumferential limiting state between the power lever 132 and the selector assembly 131. In one embodiment, the power lever 132 can be moved downwards in the axial direction to release the circumferential limit between the power lever 132 and the selector assembly 131, and the power lever 132 can return. That is, the power lever 132 is moved downwards and then upwards in the axial direction to return in order to restore the circumferential boundary between the power lever 132 and the selector assembly 131. The axial movement of the power lever 132 can be achieved by operating the button mechanism 12.

[033] The power lever 132 is inserted into the cylinder 133. A helical channel extending in the axial direction of the power lever 132 is formed between a. Petition 870250073148, dated 08 / 19 / 2025, page 40 / 66 The inner cylinder wall of cylinder 133 and the outer wall of the power lever 132 are provided, and the ball 134 can be rolled in the helical channel. The axial direction of the power lever 132 is consistent with the axial direction of the injector pen 100.

[034] Cylinder 133 does not move relative to upper pen tube 11 in a circumferential direction. An upper end of torsion spring 136 is fixed relative to upper pen tube 11, and a lower end of torsion spring 136 is connected to sleeve 135.

[035] Power lever 132 is fixed relative to sleeve 135. In other words, power lever 132 and sleeve 135 cannot rotate relative to each other, but they can rotate together.

[036] The sleeve 135 and the transmission mechanism 14 can be switched between an engaged and a disengaged transmission state. In other words, when the sleeve 135 and the transmission mechanism 14 are in the engaged transmission state, power transmission can be performed between them; and when the sleeve 135 and the transmission mechanism 14 are in the disengaged transmission state, power transmission cannot be performed between them.

[037] In one embodiment, the engagement and disengagement between the sleeve 135 and the transmission mechanism 14 are performed by the axial movement of the sleeve 135.

[038] In a specific implementation, the transmission mechanism 14 includes a drive wheel 141, a screw 142, and a carpule support cover 143. The drive wheel 141 can be engaged or disengaged from the sleeve 135. The screw 142 is circumferentially limited relative to the drive wheel 141 and is threaded into connection with the carpule support cover 143. A lower end of the screw 142 passes through the carpule support cover 143 and abuts the carpule piston 231. Typically, a gasket is placed between the screw 142 and the carpule piston 231.

[039] A coupling structure is provided between the drive wheel 141 and the sleeve. 135. The coupling structure is provided in such a way as to allow the sleeve 135 and the Petition 870250073148, dated 08 / 19 / 2025, page 41 / 66 9 / 18 drive wheel 141 are in the engaged state, wherein the sleeve 135 can cause the drive wheel 141 to rotate together as the sleeve 135 moves downward in the axial direction; and to allow the sleeve 135 and the drive wheel 141 to be in the disengaged state, wherein the rotation of the sleeve 135 does not affect the drive wheel 141 as the sleeve 135 moves upward in the axial direction.

[040] As the sleeve 135 is fixed in relation to the power lever 132, when the button mechanism 12 is actuated, the power lever 132 and the sleeve 135 can be moved downwards in the axial direction, so that the sleeve 135 is in transmission engagement with the drive wheel 141. And, under the action of the button mechanism 12, the power lever 132 and the sleeve 135 can also move upwards in the axial direction, so that the sleeve 135 is disengaged from the drive wheel 141.

[041] FIGS. 2 and 3 show the structure of the injector pen 100 in a normal state. The normal state mentioned here and above refers to the state in which the relative positions of various structures of the injector pen 100 are shown when the injector pen 100 is not being operated.

[042] In a specific implementation, the button mechanism 12 includes a button assembly and a return elastic member 123. The return elastic member 123 is provided between the button assembly and the selector assembly 131, and the axial position of the selector assembly 131 remains unchanged relative to the injector pen 100. The button assembly is pressed to actuate the power lever 132 and the sleeve 135 so that they move downwards in the axial direction, and in this process the return elastic member 123 is compressed and stores energy. After the pressure force on the button assembly is removed, the power lever 132 and the sleeve 135 can move upwards in the axial direction to return under the action of the return elastic force of the return elastic member 123.

[043] In a specific implementation, the dosage adjustment mechanism further includes a dial 138, which is disposed outside the sleeve 135. The dial 138 is circumferentially limited in relation to the sleeve 135 and connected to it. The upper pen tube 11 is provided on an outer side of the dial 138, and the tube of Petition 870250073148, dated 08 / 19 / 2025, page 42 / 66 10 / 18 top pen 11 has a display window 111. When adjusting the dosage, the dial 138 can rotate along with the sleeve 135, so that the user can determine the adjusted dosage by means of the dial scale 138 displayed in the display window 111.

[044] In a specific implementation, the dosing adjustment mechanism of the injector pen 100 further includes a torsion spring support 137, which is fixed in relation to the upper pen tube 11. The upper end of the torsion spring 136 can be connected to the torsion spring support 137. The cylinder 133 is received in the torsion spring support 137. The cylinder 133 can be fixed in relation to the upper pen tube 11, fixing it in relation to the torsion spring support 137.

[045] The relative fastening between the torsion spring support 137 and the upper pen tube 11 and the relative fastening between the cylinder 133 and the torsion spring support 137 can be achieved by press fitting or any other fastening means, which is convenient for disassembly and assembly and is beneficial for maintenance.

[046] In a specific implementation, a limiting structure is provided between the selector assembly 131 and the torsion spring support 137, and the limiting structure is configured so that the selector assembly 131 can only rotate in one direction relative to the torsion spring support 137 and cannot rotate in the opposite direction. In the injector pen configuration 100, the selector assembly 131 can rotate in a dosage adjustment direction relative to the torsion spring support 137, but cannot rotate in a direction opposite to the dosage adjustment direction.

[047] For example, the limiting structure between the selector assembly 131 and the torsion spring support 137 may be a one-way ratchet structure.

[048] Next, rotation in the direction of dosage adjustment is called forward rotation, and rotation in the opposite direction to the direction of dosage adjustment is called reverse rotation.

[049] The drug injection operation of the injector pen 100 can be divided into a dosage adjustment stage and an injection stage. Petition 870250073148, dated 08 / 19 / 2025, page 43 / 66 11 / 18

[050] During the dosage adjustment stage, the user can rotate the selector assembly. 131 forward to cause the power lever 132 to rotate, and the power lever 132 causes the sleeve 135 and the torsion spring 136 to rotate together, so that the torsion spring 136 stores energy. In this process, the adjusted dosage can be determined by means of the display window 111 of the upper pen tube 11. After the dosage is adjusted and the force applied to the selector assembly 131 is removed, the selector assembly 131 can be held in this position under the action of the limiting structure between the selector assembly 131 and the torsion spring support 137. Similarly, the power lever 132, the sleeve 135 and the torsion spring 136, which are circumferentially limited with respect to the selector assembly 131, are held in this position.

[051] In the injection stage, the button assembly of the button mechanism 12 is pressed down to push the power lever 132 to move down in the axial direction, and the power lever 132 causes the sleeve 135 to move down together, so that the sleeve 135 is engaged with the drive wheel 141 of the transmission mechanism 14. Furthermore, the power lever 132 is free from the circumferential limit relative to a stop support 1312, so that the energy stored in the torsion spring 136 is released. Under the action of the stored energy released by the torsion spring 136, the sleeve 135 and the power lever 132 rotate together in the opposite direction. The drive wheel 141 engaged with the sleeve 135 is rotated to cause the screw 142 to rotate together.When screw 142 rotates, due to the threaded engagement between screw 142 and the carpule holder cap 143, screw 142 also moves downwards in the axial direction to push the carpule plunger 231 to perform the drug injection.

[052] The button assembly of the button mechanism 12 is axially limited with respect to and connected to the power lever 132, such that when the button assembly is pressed, the button assembly can cause the power lever 132 to move downwards in the axial direction as a unit. The present application focuses on improving the connection structure between the button assembly and Petition 870250073148, dated 08 / 19 / 2025, page 44 / 66 12 / 18 the power lever 132 to ensure the reliability of the connection between the button assembly and the power lever 132, which will be described in detail below.

[053] See FIGS. 4 to 10. FIG. 4 is a schematic cutaway view of the assembly of a button and power lever in one embodiment; FIG. 5 is an enlarged partial view of part A of FIG. 4; FIG. 6 is a schematic structural view of the body of a button in one embodiment; FIG. 7 is a schematic cutaway view of the body of the button shown in FIG. 6; FIG. 8 is a schematic structural perspective view of a button cover in one embodiment; FIG. 9 is another schematic structural perspective view of a button cover in one embodiment; and FIG. 10 is a schematic structural view of a power lever in one embodiment.

[054] In this embodiment, the button assembly of the button mechanism 12 includes a button body 121 and a button cover 122. The button body 121 and the button cover 122 are detachably connected to each other.

[055] The button body 121 includes an engagement portion 1211 that extends downwards, and the engagement portion 1211 has a first limiting surface 12111 facing upwards. The power lever 132 includes a hook portion 1325 that extends upwards, and the hook portion 1325 has a second limiting surface 13251 facing downwards.

[056] The button cover 122 includes a pin portion 1221 that extends downwards. The pin portion 1221 can be inserted into the hook portion 1325 to push the hook portion 1325 radially outwards, so that the second limiting surface 13251 of the hook portion 1325 touches the first limiting surface 12111 of the engagement portion 1211. It can be understood that the hook portion 1325 has a movable space in the radial direction to ensure that the pin portion 1221 can push the hook portion 1325 outwards.

[057] With the above solution, the hook portion 1325 of the power lever 132 can extend to the engagement portion 1211 of the button body 121. After the button cover 122 is detachably connected to the button body Petition 870250073148, dated 08 / 19 / 2025, pp. 45 / 66 13 / 18 121, the pin portion 1221 of the button cover 122 can be inserted into the hook portion 1325 to push the hook portion 1325 outward in the radial direction, so that the second limiting surface 13251 of the hook portion 1325 touches the first limiting surface 12111 of the engagement portion 1211. In this way, with the engagement between the engagement portion 1211 and the hook portion 1325, the relative position of the button body 121 and the power lever 132 in the axial direction is limited. When the button assembly is pressed down, the power lever 132 can be caused to move down along with the button assembly.Meanwhile, the pin portion 1221 of the button cover 122 is inserted into the hook portion 1325, so that the hook portion 1325 always rests against the engagement portion 1211, thus ensuring the reliability of the axial limit between the power lever 132 and the button assembly and effectively preventing the hook portion 1325 of the power lever 132 from coming loose from the engagement portion 1211.

[058] In a specific implementation, the power lever 132 is provided with two or more hook portions 1325, arranged at intervals in the circumferential direction. Each hook portion 1325 includes a rod portion 13252 and a hook 13253 provided at an upper end of the rod portion 13252. The upper end of the rod portion 13252 extends radially outward to form the hook 13253. A hole portion 1326 is defined by the hook portions 1325. During assembly, the pin portion 1221 of the button cover 122 can be inserted into the hole portion 1326 defined by the hook portions 1325, so as to push all the rod portions 13252 outward in the radial direction, so that all the hooks 13253 can abut the engagement portion 1211 and be constrained by it.

[059] In one embodiment, the lower ends of the hook portions 1325 of the power lever 132 are connected by means of a connecting portion 1327 in a single piece, as shown in FIG. 2. In this way, the strength of the connection between each hook portion 1325 and a main body of the Petition 870250073148, dated 08 / 19 / 2025, pp. 46 / 66 The 14 / 18 power lever 132 can be improved. There is a notch formed between two adjacent rod portions 13252, and the notch passes through a face of the upper end of the power lever 132, so that an upper section of each rod portion 13252 can move radially. It is convenient that the pin portion 1221 pushes the rod portion 13252 into a position where the hook 13253 touches the engagement portion 1211.

[060] Specifically, an upper section of the rod portion 13252 has an elastic deformation capacity in the radial direction. On the one hand, this can alleviate the problem of the structure's strength being affected by the stress concentration of the rod portion 13252 generated due to the thrust of the pin portion 1221. On the other hand, this can facilitate the disassembly of the button mechanism 12 from the power lever 132. After the button cover 122 is removed, the rod portions 13252 can be conveniently moved back inside in the radial direction, and it is convenient for the power lever 132 to separate from the button body 121. In this way, the power lever 132 can be removed without damaging the button mechanism 12, which is beneficial for maintenance.

[061] In a specific implementation, a central region of the button body 121 is recessed to form the engagement portion 1211. The engagement portion 1211 has a through hole 1212 through which the hook portion 1325 passes, and the first limiting surface 12111 of the engagement portion 1211 is an annular surface. Thus, during assembly, it is not necessary to adjust the relative circumferential position between the power lever 132 and the button body 121, since the hook portions 1325 of the power lever 132 can touch the first limiting surface 12111 after passing through the through hole 1212 of the engagement portion 1211.

[062] In the example shown, the power lever 132 is provided with four hook portions 1325 arranged at intervals in the circumferential direction. In other implementations, the number of hook portions 1325 may be adjusted as needed. Petition 870250073148, dated 08 / 19 / 2025, page 47 / 66 15 / 18

[063] In a specific implementation, the hook portions 1325 are arranged around a central axis of the power lever 132, and a central axis of the pin portion 1221 coincides with the central axis of the power lever 132. In this way, it is advantageous to balance the thrust force applied to each hook portion 1325 by the pin portion 1221 to move the hook portion 1325 outward in the radial direction, so as to ensure that each hook portion 1325 can properly engage the engagement portion 1211.

[064] In a particular implementation, an inclined guide surface 13254 is provided at an upper end of an inner wall of the rod portion 13252 of the hook portion 1325 to guide the insertion of the pin portion 1221. This facilitates the insertion of the pin portion 1221 into the power lever 132 when the button cover 122 is mounted.

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

[066] In a specific implementation, the button cover 122 can be detachably connected to the button body 121 in a press-fit. The button body 121 may have an engagement opening 1213, and the button cover 122 may have a fitting 1222 that can be engaged in the engagement opening 1213. The button cover 122 can be fitted into the button body 121. When the button cover 122 is fitted, the fitting 1222 of the button cover 122 can extend into the engagement opening 1213 under an external force and abut a face of the inner end of the button body 121 facing downwards, thus limiting the position of the button cover 122 relative to the button body 121.

[067] In the example illustrated, when four groups of mutually engaging fittings 1222 and engagement openings 1213 are provided between the button cover 122 and the button body 121. The four groups of mutual engagement fittings 1222 and engagement openings 1213 can be arranged uniformly in the circumferential direction, so that the engagement force between the button cover 122 and the button body 121 is Petition 870250073148, dated 08 / 19 / 2025, pp. 48 / 66 16 / 18 relatively uniform, improving the connection between button cover 122 and button body 121.

[068] In other implementations, other numbers of mutual coupling sockets 1222 and mutually engaged engagement openings 1213 may also be provided between the button cover 122 and the button body 121. For example, two or three groups of fittings 1222 and engagement openings 1213 may be provided.

[069] In other implementations, the button cover 122 may be engaged to the button body 121 in any other manner. For example, a fastening portion is provided on an outer edge of the button body 121 and configured to press the button cover 122 down, and the fastening portion is rotatable relative to the button body 121 to be toggled between a position where the button cover 122 is pressed and a position where the button cover 122 is released.

[070] In this embodiment, a fail-safe structure may also be provided between the button cover 122 and the button body 121 to facilitate identification of the circumferential position of the button cover 122 relative to the button body 121 when they are assembled.It should be noted that if the engagement structure between button cover 122 and button body 121 is symmetrical around the center, the relative circumferential position of button cover 122 and button body 121 will not affect the assembly of the two, and in this case, the fail-safe structure may not be provided.

[071] In one implementation, the fail-safe structure may include a notch 1223 formed on an outer edge of the button cover 122 and a protrusion 1214 provided on an outer edge of the button body 121. The notch 1223 is compatible with the protrusion 1214. When the button cover 122 is engaged in the button body 121, the protrusion 1214 is located in the notch 1223.

[072] In this embodiment, to facilitate pressing the button assembly of the button mechanism 12, the button assembly is connected to the selector assembly 131 in such a way as to be sliding in the axial direction. The elastic return member 123 of the button mechanism 12 is provided between the button assembly and the selector assembly. Petition 870250073148, dated 08 / 19 / 2025, page 49 / 66 17 / 18 131.

[073] The elastic return member 123 may be a spring or something similar.

[074] In this embodiment, the selector assembly 131 includes a selector 1311 and a stop support 1312. The stop support 1312 is connected to the selector 1311 so as to be circumferentially limited with respect to the selector 1311. A portion of the stop support 1312 is disposed within the selector 1311, and a lower end of the selector 1311 is rotatably disposed outside the upper pen tube 11.

[075] In one implementation, the power lever 132 passes through the stop support 1312, and a circumferential limiting structure is provided between the power lever 132 and the stop support 1312.

[076] In one embodiment, the circumferential limiting structure between the stop support 1312 and the power lever 132 includes a first internal toothed ring portion 13121 provided in the stop support 1312 and a first tooth 1324 provided in the outer wall of the power lever 132. In a normal state, the first tooth 1324 of the power lever 132 can be inserted into a toothed groove of the first internal toothed ring portion 13121, so as to limit the circumferential positions of the power lever 132 and the stop support 1312. Thus, the stop support 1312 can cause the power lever 132 to rotate along with it when it is rotating.

[077] In practice, the number of the first teeth 1324 of the power lever 132 can be determined as needed, for example, two, three or more. Preferably, multiple first teeth 1324 are arranged uniformly in the circumferential direction, so that the force between the power lever 132 and the stop support 1312 is balanced.

[078] In other implementations, a circumferential limiting structure may also be provided between the power lever 132 and the selector 1311.

[079] In one application, the user can rotate the selector 1311 to cause the stop support 1312 and the power lever 132 to rotate together to adjust the Petition 870250073148, dated 08 / 19 / 2025, pp. 50 / 66 18 / 18 dosage.

[080] Specific embodiments are used in this document to describe the principle and implementation of the present application, and the description of the embodiments above is used only to help understand the method and central idea of ​​the present application. It should be noted that, for those skilled in the art, various improvements and modifications can be made to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of protection of the claims of the present application. Petition 870250073148, dated 08 / 19 / 2025, pp. 51 / 66

Claims

1 / 2 CLAIMS 1. Injector pen, characterized in that it comprises a button mechanism and a dosage adjustment mechanism, wherein the button mechanism comprises a button assembly, the button assembly comprises a button body and a button cap, and the button cap is detachably connected to the button body; the dosage adjustment mechanism comprises a power lever; the button body comprises a downward-extending engagement portion, and the engagement portion has a first upward-facing limiting surface; the power lever comprises an upward-extending hook portion, and the hook portion has a second downward-facing limiting surface;and the button cover comprises a pin portion extending downwards, and the pin portion is configured to be inserted within the hook portion to push the hook portion outwards in a radial direction, so that the second limiting surface abuts the first limiting surface.

2. Injector pen according to claim 1, characterized in that the power lever is provided with two or more hook portions, arranged at intervals in a circumferential direction; and wherein each hook portion comprises a rod portion and a hook provided at an upper end of the rod portion, and the upper end of the rod portion extends outward in the radial direction to form the hook.

3. Injection pen according to claim 2, characterized in that the lower ends of the rod portions of the hook portions are connected by means of a connecting portion in a single piece, and an upper section of each rod portion has elastic deformation capability in the radial direction.

4. Injection pen according to claim 2, characterized in that an inclined guide surface is provided at an upper end of an inner wall of each rod portion and configured to guide the insertion of the pin portion.

5. Injector pen according to any one of claims 2 to 4, characterized in that the hook portions are arranged around a central axis of the power lever, and a central axis of the pin portion coincides with the central axis of the power lever.

6. Injection pen according to any one of claims 1 to 4, characterized in that a central region of the button body is recessed to form the engagement portion, the engagement portion has a through hole through which the hook portion passes, and the first limiting surface is an annular surface.

7. Injection pen according to any one of claims 1 to 4, characterized in that the pin portion has a hollow structure.

8. Injection pen according to any one of claims 1 to 4, characterized in that the button cap is detachably connected to the button body in a press-fit.

9. Injection pen according to any one of claims 1 to 4, characterized in that the injection pen further comprises a selector assembly, a circumferential limiting structure is provided between the selector assembly and the power lever and is configured to allow the selector assembly to cause the power lever to rotate when the selector assembly rotates; and the button assembly is connected to the selector assembly so as to be sliding in an axial direction and is configured to cause the power lever to move downwards when the button assembly moves downwards relative to the selector assembly, so as to release the circumferential limit between the power lever and the selector assembly.

10. Injection pen according to claim 9, characterized in that the button mechanism further comprises a return elastic member provided between the button assembly and the selector assembly. Petition 870250073148, dated 19 / 08 / 2025, pp. 53 / 66

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