Injection pen and dose adjustment mechanism thereof

Abstract

An injection pen and a dose adjustment mechanism thereof. The dose adjustment mechanism comprises a power rod, a barrel body, a ball, a sleeve, and a torsion spring. The barrel body is sleeved outside the power rod. A spiral channel extending in an axial direction of the power rod is formed between an inner barrel wall of the barrel body and an outer rod wall of the power rod. The ball is rollably arranged in the spiral channel. The barrel body is relatively fixed to an upper pen barrel of the injection pen in a circumferential direction. The upper end of the torsion spring is relatively fixed to the upper pen barrel, and the lower end of the torsion spring is connected to the sleeve. The power rod can rotate relative to the barrel body under the action of external force. The sleeve is in circumferential limiting connection to the power rod. The sleeve is configured for being in transmission fit with a transmission mechanism of the injection pen. By means of structural optimization, the rolling smoothness of the ball in the dose adjustment mechanism can be ensured, so that the ball can be smoothly reset, thereby improving the reliability and safety during the use of the injection pen.

Description

Injection pen and dosage adjustment mechanism thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 16, 2024, with application number 202410058074.4 and invention name “A injection pen and its dosage adjustment mechanism”, 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 and a dosage adjustment mechanism thereof. 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] To achieve precise control of drug injection, the ball screw principle is often used in the dosage adjustment mechanism. However, in existing dosage adjustment mechanisms, after storing kinetic energy, the ball cannot be reset during the release process, and the mechanism has many parts and components, which reduces the reliability of the injection pen.

[0006] Summary of the Invention

[0007] The purpose of this application is to provide an injection pen and a dose adjustment mechanism thereof, which can ensure the smooth rolling of the ball in the dose adjustment mechanism through structural optimization, so that the ball can be smoothly reset, thereby improving the reliability and safety of the injection pen.

[0008] To solve the above technical problems, the present application provides a dose adjustment mechanism for an injection pen, comprising a power rod, a barrel, a ball, a sleeve and a torsion spring;

[0009] The cylinder is externally mounted on the power rod, a spiral channel extending along the axis of the power rod is formed between the inner wall of the cylinder and the outer wall of the power rod, and the ball is rollably disposed in the spiral channel;

[0010] The barrel and the upper barrel of the injection pen are relatively fixed in the circumferential direction; the upper end of the torsion spring is relatively fixed to the upper barrel, and the lower end is connected to the sleeve;

[0011] The power rod can rotate relative to the barrel under the action of external force; the sleeve is circumferentially limitedly connected to the power rod, and the sleeve is used for transmission cooperation with the transmission mechanism of the injection pen.

[0012] In one feasible solution, the sleeve includes an insertion rod portion, the power rod has a socket portion extending along its axial direction, the insertion rod portion is inserted into the socket portion, the outer peripheral wall of the insertion rod portion has a planar portion in the circumferential direction, and the inner hole wall of the socket portion has a planar wall that cooperates with the planar portion.

[0013] In a feasible solution, an axial limiting structure is further provided between the power rod and the sleeve to limit the relative position of the power rod and the sleeve in the axial direction.

[0014] In a feasible solution, one of the power rod and the sleeve is provided with a radially extending convex portion, and the other is provided with a concave portion, and the convex portion can be snapped into the concave portion; the axial limiting structure includes the convex portion and the concave portion.

[0015] In one feasible solution, the bottom end of the power rod has an extension portion extending axially downward, the extension portion is provided with the recess, the sleeve includes an inner cylinder portion, and the inner cylinder wall of the inner cylinder portion near the top end is provided with the convex portion extending radially inward.

[0016] In one feasible solution, a plurality of ribs extending radially outward are provided on the outer wall of the sleeve near the bottom end, and the plurality of ribs are arranged along the circumference of the sleeve to correct the concentricity of the sleeve and the upper pen barrel.

[0017] In a feasible solution, the dose adjustment mechanism further includes a knob assembly, and a circumferential limiting structure is provided between the knob assembly and the power rod. When the knob assembly rotates, the power rod can be driven to rotate through the circumferential limiting structure.

[0018] In a feasible solution, the power rod can move relative to the barrel in the direction of the lower cap of the injection pen under the action of an external force, so as to release the circumferential limitation with the knob assembly.

[0019] In a feasible solution, the dose adjustment mechanism further includes a torsion spring bracket, the torsion spring bracket is relatively fixed to the upper pen barrel, the barrel body is relatively fixed to the torsion spring bracket; the torsion spring bracket is connected to the upper end of the torsion spring.

[0020] The present application also provides an injection pen, comprising an upper pen barrel and a dose adjustment mechanism installed on the upper pen barrel, wherein the dose adjustment mechanism is any of the dose adjustment mechanisms described above.

[0021] In one feasible solution, the injection pen further includes a transmission mechanism, the sleeve can be axially moved downward relative to the upper pen barrel to engage with a drive wheel of the transmission mechanism, or can be axially moved upward relative to the upper pen barrel to separate from the drive wheel; the sleeve is in an engaged state with the drive wheel, and the sleeve can drive the drive wheel to rotate; the drive wheel includes a cylindrical portion extending into the sleeve, and the outer peripheral wall of the cylindrical portion is provided with a plurality of circumferentially arranged ridges for correcting the concentricity of the drive wheel and the sleeve.

[0022] In one feasible solution, the driving wheel includes a base portion fixedly connected to the lower end of the cylindrical portion, and the base portion is provided with a plurality of protrusions protruding axially upward near the outer edge, and the plurality of protrusions are arranged circumferentially to correct the concentricity of the driving wheel and the upper pen barrel.

[0023] The structural arrangement of the dose adjustment mechanism of the injection pen enables the injection pen to adopt a transmission method in which the power rod, barrel and ball cooperate during the dose adjustment process, resulting in high transmission precision and ensuring the accuracy of drug dose adjustment. At the same time, during the dose adjustment process, the power rod can rotate forward relative to the barrel, and during the drug injection process, the power rod can still rotate relative to the barrel. In other words, the power rod can rotate relative to the barrel during both the energy storage and release processes of the torsion spring, so that the ball rolls smoothly and resets reliably, thereby ensuring the accuracy of dose adjustment and improving the reliability and safety of the injection pen operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG1 is a schematic structural diagram of an injection pen according to an embodiment of the present application;

[0025] FIG2 is a cross-sectional schematic diagram of the injection pen shown in FIG1 in a first state;

[0026] FIG3 is a partial enlarged view of the area where the upper pen holder assembly is located in FIG2;

[0027] FIG4 is a schematic diagram of the matching structure of the power rod and the sleeve in a specific embodiment;

[0028] FIG5 is a cross-sectional schematic diagram of the power rod and sleeve shown in FIG4 ;

[0029] FIG6 is a schematic structural diagram of the power rod in FIG4 ;

[0030] FIG7 is a schematic structural diagram of the sleeve in FIG4 ;

[0031] FIG8 is a schematic structural diagram of a driving wheel in a specific embodiment;

[0032] FIG9 is a partial enlarged view of the joint between the pressing mechanism and the dose adjustment mechanism when the injection pen shown in FIG1 is in the second state;

[0033] FIG10 is a partial enlarged view of the fitting portion between the sleeve and the driving wheel when the injection pen shown in FIG1 is in the second state.

[0034] 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 assembly 121, resetting elastic member 123; dose adjustment mechanism 13, knob assembly 131, knob 1311, stop bracket 1312, first inner gear ring portion 13121, power rod 132, insertion hole portion 1321, extension portion 1322, recessed portion 1323, first latching tooth 1324, barrel 133, ball bearing 134, sleeve 135, insertion rod portion 1351, flat portion 13511, inner barrel portion 1352, outer barrel portion 1353, protrusion 1354, protruding rib 1355, second inner gear ring portion 1356, torsion spring 136, torsion spring bracket 137, scale plate 138; Transmission mechanism 14 , driving wheel 141 , cylindrical portion 1411 , base portion 1412 , ridge 1413 , protrusion 1414 , second latching tooth 1415 , screw 142 , bottle holder cover 143 ; lower pen cap 21 , bottle holder 22 , cartridge bottle 23 , bottle stopper 231 . DETAILED DESCRIPTION

[0035] The embodiment of the present application provides an injection pen and a dose adjustment mechanism thereof. By optimizing the structure of the dose adjustment mechanism, the smoothness of the rolling of the ball can be improved, ensuring that the ball can be smoothly reset.

[0036] For ease of understanding and concise description, the following description will be made in conjunction with the injection pen and its dose adjustment mechanism, and the specific embodiment will be described in detail using the injection pen shown in the accompanying drawings as the main body of description.

[0037] 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.

[0038] 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 in a first state; Figure 3 is a partial enlarged view of the area where the upper pen barrel assembly is located in Figure 2.

[0039] In this embodiment, the injection pen 100 includes an upper pen barrel assembly 10 and a lower pen cap assembly 20 .

[0040] 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 .

[0041] 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.

[0042] 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.

[0043] 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.

[0044] In this embodiment, the dose adjustment mechanism 13 of the injection pen 100 includes a power rod 132 , a barrel 133 , a ball 134 , a sleeve 135 and a torsion spring 136 .

[0045] The barrel 133 is externally mounted on the power rod 132. A spiral channel extending along the axis of the power rod 132 is formed between the inner wall of the barrel 133 and the outer wall of the power rod 132. The ball 134 is rollably disposed in the spiral channel. The axis of the power rod 132 is aligned with the axis of the injection pen 100.

[0046] Among them, 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; the power rod 132 and the sleeve 135 are circumferentially limited and connected. In other words, the power rod 132 and the sleeve 135 cannot rotate relative to each other, but can rotate together; 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 separation state, power transmission cannot be achieved between the two.

[0047] Under the action of external force, the power rod 132 can rotate relative to the cylinder 133 and drive the sleeve 135 to rotate together.

[0048] During operation, external force can be applied to the power rod 132 to rotate the power rod 132 in the direction of the set injection dose adjustment. When the power rod 132 rotates, the sleeve 135 can be driven to rotate together, but the cylinder 133 does not move. In this way, the ball 134 can roll in one direction along the spiral channel between the power rod 132 and the cylinder 133. Since the upper end of the torsion spring 136 is relatively fixed to the upper pen barrel 11 and the lower end is connected to the sleeve 135, the lower end of the torsion spring 136 rotates with the sleeve 135 to store energy; after rotating to the required injection dose position, the power rod 132, the sleeve 135 and the torsion spring 136 can be maintained in this position; thereafter, the stored energy of the torsion spring 136 can be released by operation, that is, the position lock of the power rod 132, the sleeve 135 and the torsion spring 136 is released, and the sleeve 135 and the transmission mechanism 14 are in a transmission engagement state. When the torsion spring 136 is in operation, the power rod 132, the sleeve 135 and the torsion spring 136 are in a transmission engagement state. Upon release of the stored energy, the power rod 132 and sleeve 135 rotate in the opposite direction. The engagement of the sleeve 135 with the transmission mechanism 14 transmits the driving force to the transmission mechanism 14, thereby pushing the stopper 231 downward, thereby achieving drug injection. As the power rod 132 and sleeve 135 rotate in the opposite direction, the barrel 133 also remains stationary, allowing the ball 134 to roll in the opposite direction and return to its original position.

[0049] According to the above operation, the degree of rotation of the sleeve 135 driven by the power rod 132 determines the energy storage size of the torsion spring 136, and the energy storage size of the torsion spring 136 is related to the final stroke of pushing the bottle stopper 231 downward, that is, related to the dosage of the drug injection.

[0050] It can be understood that the reverse rotation of the power rod 132 and the sleeve 135 is a rotation in the opposite direction to the aforementioned rotation toward the setting injection dose, and the reverse rolling of the ball 134 is also a rolling in the opposite direction to the previous direction.

[0051] Here, the rotation in the direction of adjusting the dosage is defined as forward rotation, and correspondingly, the rotation in the direction opposite to the direction of adjusting the dosage is defined as reverse rotation.

[0052] With the above-described solution, the injection pen 100 utilizes a transmission method in which the power rod 132, the barrel 133, and the ball 134 cooperate during dose adjustment, resulting in high transmission precision and ensuring accurate drug dose adjustment. Furthermore, during dose adjustment, the power rod 132 can rotate in a positive direction relative to the barrel 133. During drug injection, the power rod 132 can still rotate relative to the barrel 133, thereby ensuring smooth rolling and reliable reset of the ball 134. This ensures accurate dose adjustment and improves the reliability and safety of the injection pen 100.

[0053] In this embodiment, the dose adjustment mechanism 13 further includes a knob assembly 131 . A circumferential limiting structure is provided between the knob assembly 131 and the power rod 132 . When the knob assembly 131 rotates, the power rod 132 can be driven to rotate by the circumferential limiting structure.

[0054] In a specific implementation, 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 .

[0055] 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 .

[0056] 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 (labeled in Figures 4 to 6) provided on the outer wall of the power rod 131. Under normal conditions, the first latching tooth 1324 of the power rod 131 can be embedded in the tooth groove of the first inner gear ring portion 13121, thereby limiting the circumferential position of the power rod 131 and the stop bracket 1312, so that when the stop bracket 1312 rotates, it can also drive the power rod 132 to rotate together.

[0057] In the illustrated example, the power rod 131 is provided with four first latching teeth 1324 along the circumference. In actual applications, the power rod 131 may have other numbers of first latching teeth 1324, such as two, three, or more. The plurality of first latching teeth 1324 are preferably evenly distributed along the circumference to ensure balanced force between the power rod 131 and the stop bracket 1312.

[0058] In other implementations, a circumferential limiting structure may also be provided between the power rod 132 and the knob 1311 .

[0059] During use, the user can rotate the rotating member 1311 to drive the stop bracket 1312 and the power rod 132 to rotate together to adjust the dosage.

[0060] In this embodiment, the dose adjustment mechanism 13 further includes a torsion spring bracket 137 , which is relatively fixed to the upper pen barrel 11 , and the barrel 133 is sleeved inside the torsion spring bracket 137 . The barrel 133 can be relatively fixed to the upper pen barrel 11 by being relatively fixed to the torsion spring bracket 137 .

[0061] 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 both adopt a snap-fit ​​structure, which is convenient for disassembly and assembly and is conducive to maintenance.

[0062] The upper end of the aforementioned torsion spring 136 can be specifically connected to the torsion spring bracket 137.

[0063] 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, preventing reverse rotation. In the structural configuration of the injection pen 100, the knob assembly 131 can rotate forward relative to the torsion spring bracket 137, but cannot rotate backward. Thus, after the knob assembly 131 drives the power rod 132 to rotate forward to the desired dosage adjustment position, the power rod 132, sleeve 135, and torsion spring 136 remain in that position.

[0064] 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.

[0065] In this embodiment, the power rod 132 can move relative to the barrel 133 toward the lower cap 21 of the injection pen 100 under the action of an external force, thereby releasing the circumferential restraint between the power rod 132 and the knob assembly 131. In other words, the power rod 132 can move axially downward relative to the upper barrel 11 under the action of an external force to release the circumferential restraint between the power rod 132 and the knob assembly 131, thereby releasing the stored energy in the torsion spring 136. It will be appreciated that after the power rod 132 releases the circumferential restraint between the power rod 132 and the knob assembly 131, the power rod 132 is no longer constrained by the knob assembly 131, and the sleeve 135 and torsion spring 136 are no longer constrained by their positional limitations. The energy in the torsion spring 136 can be released, causing the sleeve 135 and power rod 132 to rotate in opposite directions.

[0066] Specifically, when the power rod 132 moves downward in the axial direction, its first latch tooth 1324 moves downward accordingly, while the axial position of the stop bracket 1312 of the knob assembly 131 remains unchanged, so that the first latch tooth 1324 disengages from the first inner gear ring portion 13121, thereby releasing the circumferential limit between the power rod 132 and the knob assembly 131.

[0067] In this embodiment, the sleeve 135 can also be moved axially downward relative to the upper pen barrel 11 to engage with the transmission mechanism 14 to achieve power transmission, or moved axially upward relative to the upper pen barrel 11 to separate from the transmission mechanism 14 to achieve power cutoff.

[0068] In a specific implementation, the sleeve 135 and the power rod 132 are axially limitedly connected so as to move axially together under the action of an external force.

[0069] In a specific implementation, the button mechanism 12 of the aforementioned injection pen 100 serves as a structure capable of applying a downward force to the power rod 132 .

[0070] The button mechanism 12 includes a button assembly 121 and a reset elastic member 123 . The button assembly 121 is axially limitedly connected to the power rod 132 .

[0071] During operation, the button mechanism 12 is pressed downward, which drives the power rod 132 and the sleeve 135 downward together, releasing the circumferential limit connection between the power rod 132 and the knob assembly 131, and engaging the sleeve 135 with the transmission mechanism 14. In this way, the stored energy of the torsion spring 136 can be released, driving the sleeve 135 and the power rod 132 to rotate in the opposite direction. At this time, the sleeve 135 is engaged with the transmission mechanism 14, and when the sleeve 135 rotates, it can transmit power to the transmission mechanism 14 to push the bottle stopper 231. After the button assembly 121 is pressed, the reset elastic member 123 stores energy, which is used to reset the button assembly 121 after the pressing force on the button mechanism 12 is released.

[0072] In terms of layout, the button mechanism 12 , the dose adjustment mechanism 13 and the transmission mechanism 14 are arranged roughly from top to bottom; the main body of the sleeve 135 of the dose adjustment mechanism 13 is located below the power rod 132 .

[0073] In a specific implementation, a dial 138 is mounted on the sleeve 135. The sleeve 135 and the dial 138 are circumferentially connected. The upper pen barrel 11 is located outside the dial 138, and the upper pen barrel 11 has a display window 111. When adjusting the dose, the dial 138 rotates 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.

[0074] Please refer to Figures 4 to 7 together. Figure 4 is a schematic diagram of the matching structure of the power rod and the sleeve in a specific embodiment; Figure 5 is a cross-sectional schematic diagram of the power rod and the sleeve shown in Figure 4; Figure 6 is a structural schematic diagram of the power rod in Figure 4; and Figure 7 is a structural schematic diagram of the sleeve in Figure 4.

[0075] In this embodiment, the power rod 132 has a socket portion 1321 extending along its axial direction, and the sleeve 135 includes a rod insertion portion 1351. The rod insertion portion 1351 is inserted into the socket portion 1321 of the power rod 132. The outer peripheral wall of the rod insertion portion 1351 has a flat portion 13511 in the circumferential direction, and the inner hole wall of the socket portion 1321 has a flat wall that cooperates with the flat portion 13511. In this way, after the rod insertion portion 1351 of the sleeve 135 is inserted into the socket portion 1321 of the power rod 132, when the power rod 132 rotates, the sleeve 135 can be driven to rotate together under the action of the mutually cooperating flat portion 13511 and the flat wall. Obviously, the flat portion 13511 and the flat wall constitute a circumferential limiting connection structure between the power rod 132 and the sleeve 135.

[0076] In a specific implementation, the cross-sections of the mating rod portion 1351 and the socket portion 1321 only need to be non-circular structures, such as rectangular, square, triangular or polygonal; they can also be other irregular shapes with a planar structure.

[0077] The axial limiting structure between the power rod 12 and the sleeve 135 can be in various forms. The following describes a relatively simple and reliable method.

[0078] A convex portion 1354 extending radially inward is provided on the sleeve 135, and a concave portion 1323 cooperating with the convex portion 1354 is provided on the power rod 132. After the rod insertion portion 1351 of the sleeve 135 is inserted into the socket portion 1321 of the power rod 132, the convex portion 1354 of the sleeve 135 can be snapped into the concave portion 1323 of the power rod 132. As shown in Figure 5, the axial position of the sleeve 135 and the power rod 12 is limited by the snap action of the convex portion 1354 and the concave portion 1323.

[0079] In a specific implementation, the power rod 132 has an extension portion 1322 extending axially downward near the bottom end of the sleeve 135, and a recess 1323 is formed on the side wall of the extension portion 1322 facing the sleeve 135. The recess 1323 can be in the form of a groove or a hole.

[0080] The sleeve 135 includes an inner tube portion 1352 connected to the insertion rod portion 1351. The inner tube wall of the inner tube portion 1352 near the top is provided with the aforementioned protrusion 1354. After assembly, the extension portion 1322 of the power rod 132 can extend into the inner tube portion 1352. The bottom end of the insertion rod portion 1351 is also partially located within the inner tube portion 1352 to facilitate the snap-fitting of the protrusion 1354 and the recess 1323.

[0081] In other implementations, the aforementioned convex portion 1354 and concave portion 1323 may also be arranged in reverse, that is, the convex portion 1354 is arranged on the power rod 132 , and the concave portion 1323 is arranged on the sleeve 135 .

[0082] The sleeve 135 also includes an outer tube portion 1353 which is arranged outside the inner tube portion 1352. The bottom ends of the inner tube portion 1352 and the outer tube portion 1353 are connected together, and a space for accommodating the aforementioned torsion spring 136 is formed between the inner tube portion 1352 and the outer tube portion 1353. A hook hole can be provided at the bottom end of the sleeve 135 to facilitate hooking and connection with the lower end of the torsion spring 136.

[0083] Specifically, the power rod 132 and sleeve 135 can be provided with two or more sets of mutually cooperating recesses 1323 and protrusions 1354, evenly arranged along the circumference of the power rod 132, so as to ensure uniform force on the connection between the power rod 132 and the sleeve 135 and avoid deflection. The figure shows the structure of two sets of recesses 1323 and protrusions 1354.

[0084] In a specific implementation, the outer wall of the sleeve 135 near the bottom end is provided with a plurality of radially outwardly extending ribs 1355, which are arranged along the circumference of the sleeve 135 to correct the concentricity of the sleeve 135 and the upper pen barrel 11. In this way, the deflection of the sleeve 135 can be prevented from affecting the transmission effect with the transmission mechanism 14.

[0085] In this embodiment, the transmission mechanism 14 of the injection pen 100 includes a drive wheel 141, a screw 142, and a bottle holder cover 143. The drive wheel 141 can engage or disengage with the sleeve 135. The screw 142 is circumferentially limited to the drive wheel 141 and threadedly connected to the bottle holder cover 143. The lower end of the screw 142 passes through the bottle holder cover 143 and abuts the bottle stopper 231. Typically, a gasket is provided between the screw 142 and the bottle stopper 231.

[0086] 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.

[0087] Please also refer to FIG8 , which is a schematic structural diagram of a driving wheel in a specific embodiment.

[0088] Specifically, the drive wheel 141 includes a cylindrical portion 1411 that extends into the sleeve 135. The outer peripheral wall of the cylindrical portion 1411 is provided with a plurality of circumferentially arranged ridges 1413 to adjust the concentricity of the drive wheel 141 and the sleeve 135. This helps ensure the smooth engagement and disengagement of the sleeve 135 and the drive wheel 141, prevents them from getting stuck, and improves the reliability of the injection pen 100.

[0089] The driving wheel 141 further includes a base portion 1412 fixed to the lower end of the cylindrical portion 1411. The base portion 1412 is provided with a plurality of protrusions 1414 protruding axially upward near the outer edge. The protrusions 1414 are arranged circumferentially to correct the concentricity of the driving wheel 141 and the upper pen barrel 11. This helps to improve the reliability of the transmission cooperation between the driving wheel 141 and the sleeve 135.

[0090] In application, the aforementioned plurality of ridges 1413 can be evenly arranged along the circumference, and the aforementioned plurality of protrusions 1414 can also be evenly arranged along the circumference, so that the forces on the corresponding components are more balanced and more conducive to the correction of concentricity.

[0091] In a specific implementation, the bottom end of the sleeve 135 has a second inner gear ring portion 1356, and the driving wheel 141 is provided with a second latching tooth 1415. When the sleeve 135 moves downward in the axial direction, the second latching tooth 1415 on the driving wheel 141 can be embedded in the tooth groove of the second inner gear ring portion 1356, thereby realizing the engagement of the driving wheel 141 and the sleeve 135, so that the sleeve 135 can drive the driving wheel 141 to rotate together. When the sleeve 135 moves upward in the axial direction, the second inner gear ring portion 1356 disengages from the second latching tooth 1415 of the driving wheel 141, thereby separating the driving wheel 141 and the sleeve 135, and the driving wheel 141 does not rotate with the sleeve 135.

[0092] In a specific implementation, the barrel cavity of the inner barrel portion 1352 of the sleeve 135 serves as a space for accommodating the screw 142 . In other words, the bottom of the sleeve 135 is an opening structure that passes through the barrel cavity of the inner barrel portion 1352 .

[0093] When the dosage is adjusted by rotating the knob assembly 131 and the button assembly 121 is pressed, the power rod 132 and the sleeve 135 move downward along the axial direction together, the power rod 132 disengages from the circumferential limit of the knob assembly 131, and the sleeve 135 engages with the driving wheel 141. Under the action of the stored energy release of the torsion spring 136, the power rod 132 and the sleeve 135 rotate together, driving the driving wheel 141 to rotate. When the driving wheel 141 rotates, it drives the screw 142 with its circumferential limit to rotate together, and the screw 142 is threadedly connected to the bottle holder cover 143. Under the action of the thread, the screw 142 moves downward along the axial direction, pushing the bottle stopper 231 downward, thereby realizing drug injection.

[0094] Comparing Figures 2 and 3 with Figures 9 and 10, in Figures 2 and 3, the injection pen 100 is in a first state in which the power rod 132 and the knob assembly 131 are circumferentially limited, and the sleeve 135 and the drive wheel 141 are separated. Figure 9 shows a second state in which the circumferential limit of the power rod 132 and the knob assembly 131 is released after the button assembly 121 is pressed. It can be seen from the figure that the first latch tooth 1324 of the power rod 132 is disengaged from the first inner gear ring portion 13121 of the knob assembly 131. Figure 10 shows that after the button assembly 121 is pressed, the sleeve 135 and the drive wheel 141 are in an engaged state.

[0095] The specific structure and connection of the relevant components of the lower cap assembly 20 of the injection pen 100 are not the core of the invention of this application. You can refer to the existing technology for understanding and will not elaborate on them here.

[0096] 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. The dose adjustment mechanism of the injection pen, characterized in that, It includes a power rod, a cylinder body, a ball, a sleeve and a torsion spring; The cylinder body is sleeved outside the power rod. A spiral channel extending along the axial direction of the power rod is formed between the inner cylinder wall of the cylinder body and the outer rod wall of the power rod. The ball is rollably arranged in the spiral channel; The cylinder body is circumferentially fixed relative to the upper pen barrel of the injection pen; the upper end of the torsion spring is fixed relative to the upper pen barrel, and the lower end is connected to the sleeve; The power rod can rotate relative to the cylinder body under the action of an external force; the sleeve is circumferentially limitedly connected to the power rod, and the sleeve is used for driving cooperation with the transmission mechanism of the injection pen; The sleeve includes an insertion rod part. The power rod has an insertion hole part extending along its axial direction. The insertion rod part is inserted into the insertion hole part. The outer peripheral wall of the insertion rod part has a flat part in the circumferential direction, and the inner hole wall of the insertion hole part has a flat wall cooperating with the flat part; An axial limiting structure is further provided between the power rod and the sleeve to limit the relative position of the power rod and the sleeve in the axial direction.

2. The dose adjustment mechanism according to claim 1, wherein, In the power rod and the sleeve, one is provided with a convex part protruding radially, and the other is provided with a concave part. The convex part can be stuck into the concave part; the axial limiting structure includes the convex part and the concave part.

3. The dose adjustment mechanism according to claim 2, characterized in that, The bottom end of the power rod has an extension part extending axially downward. The concave part is provided on the extension part. The sleeve includes an inner cylinder part. The inner cylinder wall near the top end of the inner cylinder part is provided with the convex part protruding radially inward.

4. The dose adjustment mechanism according to any one of claims 1 to 3, characterized in that, A plurality of convex ribs protruding radially outward are provided on the outer cylinder wall near the bottom end of the sleeve. The plurality of convex ribs are arranged in the circumferential direction of the sleeve to correct the concentricity between the sleeve and the upper pen barrel.

5. The dose adjustment mechanism according to any one of claims 1-3, characterized in that, The dose adjustment mechanism further includes a knob assembly. A circumferential limiting structure is provided between the knob assembly and the power rod. When the knob assembly rotates, it can drive the power rod to rotate through the circumferential limiting structure.

6. The dose adjustment mechanism according to claim 5, characterized in that, Under the action of an external force, the power rod can move relative to the cylinder body in the direction of the lower pen cap of the injection pen to release the circumferential limit with the knob assembly.

7. The dose adjustment mechanism according to any one of claims 1-3, characterized in that, The dose adjustment mechanism further includes a torsion spring bracket. The torsion spring bracket is fixed relative to the upper pen barrel, and the cylinder body is fixed relative to the torsion spring bracket; the torsion spring bracket is connected to the upper end of the torsion spring.

8. Injector pen, comprising an upper pen barrel and a dose adjustment mechanism mounted on the upper pen barrel, characterized in that, The dose adjustment mechanism is the dose adjustment mechanism according to any one of claims 1-7.

9. The injection pen according to claim 8, characterized in that, The injection pen further includes a transmission mechanism. The sleeve can move axially downward relative to the upper pen barrel to engage with the driving wheel of the transmission mechanism, or move axially upward relative to the upper pen barrel to separate from the driving wheel; when the sleeve is in an engaged state with the driving wheel, the sleeve can drive the driving wheel to rotate; the driving wheel includes a cylindrical part extending into the sleeve. A plurality of convex ribs arranged in the circumferential direction are provided on the outer peripheral wall of the cylindrical part to correct the concentricity between the driving wheel and the sleeve.

10. The injection pen according to claim 9, characterized in that, The driving wheel includes a base part fixed to the lower end of the cylindrical part. A plurality of protruding parts protruding axially upward are provided near the outer edge of the base part. The plurality of protruding parts are arranged in the circumferential direction to correct the concentricity between the driving wheel and the upper pen barrel.

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