INJECTION PEN AND DOSE ADJUSTING MECHANISM FOR IT

Abstract

Provided are an injection pen and a dose adjustment mechanism thereof. The dose adjustment mechanism comprises a knob, a stop bracket, and a torsion spring bracket. The knob can drive the stop bracket to rotate relative to the torsion spring bracket. The stop bracket is provided with a cantilever, and the torsion spring bracket is provided with an inner ratchet ring. The cantilever is in a unidirectional rotation fit with the inner ratchet ring in a direction of adjusting the dose. The knob is provided with an arm part located on an outer side of the cantilever. The knob can also rotate relative to the stop bracket so as to switch between a first position and a second position. In the first position, the knob can directly drive the stop bracket to rotate in the direction of adjusting the dose, and the cantilever is in a unidirectional rotation fit with the inner ratchet ring. In the second position, the arm part compresses the cantilever inwards in a radial direction, such that the cantilever is separated from the inner ratchet ring. The knob can directly drive the stop bracket to rotate in a direction opposite to adjusting the dose. By the structural optimization, the present disclosure reduces the return force of the knob assembly, such that the knob assembly can be reversely rotated upon the overadjustment of the dose.

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 202410058049.6 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] Among them, the dose adjustment mechanism drives the torsion spring to rotate by rotating the knob to store kinetic energy in the torsion spring, and the dial rotates accordingly to display the adjusted dose, and the torsion spring is kept in the energy storage position by the limit cooperation of the stop bracket engaged with the knob and the torsion spring bracket. After the kinetic energy stored in the torsion spring is released to achieve injection, the limit of the stop bracket and the torsion spring bracket is released, and the knob and the stop bracket can be reset and drive the dial to reset.

[0006] During use, when adjusting the dose, the knob may be rotated too far in the forward direction and needs to be rotated back in the reverse direction. However, in the design of the existing dose adjustment mechanism, the rotation force of the knob is too large, making it difficult to operate. Summary of the Invention

[0007] The purpose of the present application is to provide an injection pen and a dose adjustment mechanism thereof, which can reduce the rotational force of the knob assembly through structural optimization, facilitate reverse rotation of the knob assembly when the dose is over-adjusted, and improve operability.

[0008] To solve the above technical problems, the present application provides a dose adjustment mechanism for an injection pen, comprising a knob, a stop bracket and a torsion spring bracket;

[0009] The knob can drive the stop bracket to rotate relative to the torsion spring bracket;

[0010] The stop bracket is provided with a cantilever, the torsion spring bracket has an inner ratchet ring, the cantilever and the inner ratchet ring are engaged in a one-way rotation in the direction of adjusting the dosage; the knob is provided with an arm portion located outside the cantilever;

[0011] The knob can also rotate relative to the stop bracket to switch between a first position and a second position. In the first position, the knob can directly drive the stop bracket to rotate in the direction of adjusting the dose, and the cantilever cooperates with the inner ratchet ring for unidirectional rotation. In the second position, the arm presses radially inward against the cantilever to disengage the cantilever from the inner ratchet ring; the knob can directly drive the stop bracket to rotate in the direction opposite to the direction of adjusting the dose.

[0012] In a feasible solution, one of the knob and the stop bracket is provided with a protrusion extending in the radial direction, and the other is provided with a sliding groove extending in the circumferential direction, the protrusion extends into the sliding groove and can rotate circumferentially in the sliding groove, the sliding groove has a first groove wall and a second groove wall in the circumferential direction, the protrusion abuts against the first groove wall, and the knob is in the first position, the protrusion abuts against the second groove wall, and the knob is in the second position.

[0013] In a feasible solution, there are more than two groups of the mutually cooperating protrusions and the sliding grooves, and they are evenly arranged along the circumference of the knob.

[0014] In a feasible solution, a reset structure is provided between the knob and the stop bracket, and when the knob is in the second position, the reset structure can generate a reset force to rotate the knob to the first position in the direction of adjusting the dose.

[0015] In one feasible solution, the reset structure includes a limiting rib and a limiting hole extending along the circumferential direction, one of the limiting rib and the limiting hole is provided on the knob, and the other is provided on the stop bracket, the limiting rib extends into the limiting hole, and is configured as follows: when the knob is in the second position, the limiting rib is squeezed by the wall of the limiting hole to generate a deformation force causing the knob to rotate toward the first position.

[0016] In one feasible solution, the dosage adjustment mechanism further includes a power rod.

[0017] At least a portion of the stop bracket is sheathed within the knob, the upper end of the power rod passes through the stop bracket, and a circumferential limiting structure is provided between the power rod and the stop bracket, so that the stop bracket can drive the power rod to rotate;

[0018] The power rod can move axially relative to the stop bracket to switch between a position where the power rod is circumferentially limited with the stop bracket and a position where the power rod is released from the circumferential limit with the stop bracket.

[0019] In one feasible solution, the stop bracket includes a frame tube portion, the knob includes an outer tube member and an inner tube member, the frame tube portion is sleeved within the inner tube member, and the outer tube member is used to rotatably cooperate with the upper pen barrel of the injection pen; the circumferential limiting structure is arranged between the power rod and the frame tube portion.

[0020] In one feasible solution, the dose adjustment mechanism further includes a barrel, a ball, a sleeve, and a torsion spring;

[0021] The cylinder is externally mounted on the power rod and internally inserted into the frame tube portion. 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. The ball is rollably disposed in the spiral channel.

[0022] The cylinder is connected to the torsion spring bracket in a circumferential limiting manner; the power rod and the sleeve are relatively fixed, the upper end of the torsion spring is connected to the torsion spring bracket, and the lower end of the torsion spring is connected to the sleeve.

[0023] 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 barrel of the injection pen.

[0024] 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.

[0025] The present application scheme optimizes the structure of the knob assembly of the dose adjustment mechanism of an injection pen. When adjusting the dose of the injection pen, the knob is rotated forward. After the knob rotates to the first position, it drives the stop bracket to rotate together to achieve dose adjustment. After the knob is excessively rotated forward, it can be rotated backward. At the beginning of the reverse rotation, the knob is in the first position relative to the stop bracket. At this time, when the knob is rotated backward, the stop bracket will not rotate with the knob until the knob rotates to the second position. When the knob rotates from the first position to the second position relative to the stop bracket, the arm of the knob presses radially inward against the cantilever, causing the cantilever to disengage from the inner ratchet ring. As a result, when the knob continues to rotate backward from the second position, it can drive the stop bracket to rotate backward without being hindered by the inner ratchet ring, thereby achieving dose adjustment and facilitating accurate adjustment of the over-adjusted dose. The setting of the knob assembly and the associated structure of the dose adjustment mechanism makes it possible to adjust the dose by rotating the knob assembly after excessive dose adjustment, and the rotational resistance is small, which is conducive to rotational adjustment, making it convenient for the injection pen to control the injection dose more accurately, and improving the operability and safety of the injection pen. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic structural diagram of an injection pen according to an embodiment of the present application;

[0027] FIG2 is a schematic cross-sectional view of the injection pen shown in FIG1 ;

[0028] FIG3 is a partial enlarged view of the area where the upper pen holder assembly is located in FIG2;

[0029] FIG4 is a cross-sectional view of the assembled power rod, knob, stop bracket and torsion spring bracket in a specific embodiment;

[0030] FIG5 is a top view of the knob, the stop bracket and the torsion spring bracket in the first position in a specific embodiment;

[0031] FIG6 is a top view of the knob, the stop bracket and the torsion spring bracket in the second position in a specific embodiment;

[0032] FIG7 is a schematic structural diagram of the cooperation between the stop bracket and the torsion spring bracket in a specific embodiment;

[0033] FIG8 is a schematic structural diagram of a stop bracket in a specific embodiment;

[0034] FIG9 is a front view of the stop bracket shown in FIG8;

[0035] FIG10 is a top view of the stop bracket shown in FIG9 ;

[0036] FIG11 is a bottom view of the stop bracket shown in FIG9 ;

[0037] FIG12 is a schematic diagram of the structure of the knob in a specific embodiment from a top view;

[0038] FIG13 is a schematic diagram of the structure of the knob in a specific embodiment when viewed from above;

[0039] FIG14 is a schematic structural diagram of a torsion spring bracket according to a specific embodiment;

[0040] FIG15 is a schematic structural diagram of a sleeve in a specific embodiment.

[0041] Description 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 130, arm 1301, slide groove 1302, first groove wall 13021, Second groove wall 13022, limiting hole 1303, outer cylinder 1304, inner cylinder 1305, stop bracket 131, cantilever 1311, protrusion 1312, limiting rib 1313, cylinder portion 1314, first inner gear ring portion 1315, power rod 132, first latching tooth 1324, cylinder body 133, ball bearing 134, sleeve 135, insertion rod portion 1351, inner cylinder portion 1352, outer cylinder portion 1353, protruding rib 1355, torsion spring 136, torsion spring bracket 137, inner ratchet ring 1371, scale plate 138; transmission mechanism 14, driving wheel 141, screw 142, bottle holder cover 143; lower pen cap 21, bottle holder 22, cartridge bottle 23, bottle stopper 231. DETAILED DESCRIPTION

[0042] 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 rotation force of the knob assembly can be reduced, and the reverse rotation of the knob assembly is facilitated when the dose is over-adjusted, thereby enhancing operability.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] In this embodiment, the injection pen 100 includes an upper pen barrel assembly 10 and a lower pen cap assembly 20 .

[0047] 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 .

[0048] 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.

[0049] 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.

[0050] 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.

[0051] In this embodiment, the dose adjustment mechanism 13 includes a knob assembly that rotates relative to the upper barrel 11 to adjust the dose. Specifically, when the knob assembly is rotated in the dose adjustment direction, a driving force corresponding to the injection dose is stored. The button mechanism 12 releases this stored driving force and transmits it to the stopper 231 via the transmission mechanism 14, causing the stopper 231 to move downward by a distance corresponding to the injection dose, thereby injecting the prescribed dose of medication.

[0052] To simplify the description and facilitate understanding, 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.

[0053] In this embodiment, the dose adjustment mechanism 13 further includes a power rod 132 , a cylinder 133 , a ball 134 , a sleeve 135 and a torsion spring 136 .

[0054] A circumferential limiting structure is provided between the power rod 132 and the knob assembly.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] When the knob assembly is rotated forward, the knob assembly drives the power rod 132 to rotate. When the power rod 132 rotates, it can drive the sleeve 135 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; because 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, thereby forming a driving force for subsequently driving the bottle stopper 231 to move downward to achieve injection; after the knob assembly is rotated to the required injection dose position, the knob assembly can be kept in this position, from The power rod 132, sleeve 135, and torsion spring 136 also remain in this position; thereafter, the stored energy of the torsion spring 136 can be released by operating the aforementioned button mechanism 12. Specifically, operating the button mechanism 12 can release the positional lock of the power rod 132, sleeve 135, and torsion spring 136, and place the sleeve 135 in a transmission engagement state with the transmission mechanism 14. Under the action of the released stored energy of the torsion spring 136, the power rod 132 and sleeve 135 rotate in opposite directions. The engagement of the sleeve 135 with the transmission mechanism 14 transmits a driving force to the transmission mechanism 14, thereby pushing the bottle stopper 231 downward to achieve drug injection. When the power rod 132 and sleeve 135 rotate in opposite directions, the cylinder 133 also does not move, thereby allowing the ball 134 to roll in the opposite direction and return to its original position.

[0060] 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.

[0061] As can be seen from the above process, the dosage can be adjusted by rotating the knob assembly forward. During this process, the display window 111 of the upper pen barrel 11 can be used to observe whether the knob assembly is rotated in place. However, in actual operation, the problem of over-rotation often occurs. For example, according to the dosage to be injected, the knob assembly should be rotated forward one circle. However, during operation, the knob assembly is rotated more than one circle. At this time, in order to avoid safety accidents caused by excessive drug injection, the knob assembly needs to be rotated in the reverse direction, that is, it needs to be reversed to ensure accurate dosage adjustment. However, the structural design of the existing knob assembly makes the knob assembly only unidirectional (i.e., forward rotation), or although it can rotate in both directions, the rotational resistance during the reverse callback is very large, making it difficult to operate. The present application focuses on improving the knob assembly of the dosage adjustment mechanism 13, in order to reduce the rotational force of the knob, that is, to reduce the rotational resistance of the knob assembly, so as to facilitate the reverse rotation of the knob assembly when the dosage is excessively adjusted.

[0062] The aforementioned structure for storing energy when the knob assembly rotates in the forward direction is merely an exemplary description. In actual applications, the structure for driving the torsion spring 136 to rotate and store energy may have other different forms, not limited to the arrangement of the aforementioned power rod 132, cylinder 133, ball 134 and sleeve 135.

[0063] The following is a detailed description of the knob assembly and its associated structure. Please refer to Figures 4 to 7. Figure 4 is a cross-sectional schematic diagram of the assembled power rod, knob, stop bracket and torsion spring bracket in a specific embodiment; Figure 5 is a top view of the knob, stop bracket and torsion spring bracket in the first position in a specific embodiment; Figure 6 is a top view of the knob, stop bracket and torsion spring bracket in the second position in a specific embodiment; Figure 7 is a structural schematic diagram of the stop bracket and torsion spring bracket in a specific embodiment.

[0064] In this embodiment, the dose adjustment mechanism 13 further includes a torsion spring bracket 137, which is specifically fixed relative to the upper pen barrel 11. 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 relatively fixed to the upper pen barrel 11 by being relatively fixed to the torsion spring bracket 137.

[0065] 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.

[0066] The knob assembly of the dose adjustment mechanism 13 includes a knob 130 and a stop bracket 131; wherein, the lower end of the knob 130 can be rotatably mounted on the upper end of the upper pen barrel 11, and the stop bracket 131 and the torsion spring bracket 137 are both located on the inner side of the knob 130, and the stop bracket 131 can cooperate with the torsion spring bracket 137.

[0067] The knob 130 can drive the stop bracket 131 to rotate relative to the torsion spring bracket 137; the stop bracket 131 is provided with a cantilever 1311, and the torsion spring bracket 137 has an inner ratchet ring 1371. The cantilever 1311 and the ratchet teeth of the inner ratchet ring 1371 rotate unidirectionally in the direction of adjusting the dose. That is to say, after the cantilever 1311 and the ratchet teeth of the inner ratchet ring 1371 cooperate, the cantilever 1311 can rotate smoothly in the positive direction (towards the direction of adjusting the dose) along the inner ratchet ring 1371, but when rotating in the reverse direction, it will be resisted by the inner ratchet ring 1371 and cannot rotate smoothly.

[0068] The knob 130 includes an arm 1301 located outside the cantilever 1311. The knob 130 can rotate relative to the stop bracket 131 between a first position and a second position. In the first position, the knob 130 can directly drive the stop bracket 131 to rotate forward, and the cantilever 1311 and the inner ratchet ring 1371 cooperate for unidirectional rotation, that is, the inner ratchet ring 1371 prevents the cantilever 1311 from rotating in the reverse direction. In the second position, the arm 1301 of the knob 130 presses radially inward against the cantilever 1311 to disengage the cantilever 1311 from the inner ratchet ring 1371, and the knob 130 can directly drive the stop bracket 131 to rotate in the reverse direction.

[0069] As shown in Figure 5, the knob 130 is in a first position relative to the stop bracket 131. As shown in Figure 6, the knob 130 is in a second position relative to the stop bracket 131. In the orientations shown in Figures 5 and 6, clockwise rotation is the forward rotation direction for adjusting the dosage, and counterclockwise rotation is the reverse rotation direction, which is opposite to adjusting the dosage.

[0070] It will be appreciated that, in the second position, the arm 1301 of the knob 130 radially inwardly presses against the cantilever 1311, causing the cantilever 1311 to disengage from the inner ratchet ring 1371. Therefore, the cantilever 1311 is now free from the obstruction of the inner ratchet ring 1371 and can rotate in the opposite direction. The aforementioned one-way rotational engagement of the cantilever 1311 and the inner ratchet ring 1371 refers to a state in which the cantilever 1311 is engaged with the ratchet teeth of the inner ratchet ring 1371, or in other words, a state in which the cantilever 1311 is embedded in the tooth groove between two adjacent ratchet teeth of the inner ratchet ring 1371. It can also be understood that when in the first position, the arm 1301 of the knob 130 does not apply a radially inward pressing force to the cantilever 1311, or even if the arm 1301 applies force to the cantilever 1311, it is not sufficient to cause the cantilever 1311 to disengage from the inner ratchet ring 1371, and the cantilever 1311 and the inner ratchet ring 1371 maintain a one-way rotational engagement state.

[0071] The meshing configuration between the cantilever 1311 and the inner ratchet ring 1371 is such that the cantilever 1311 can rotate along the inner ratchet ring 1371 in the forward direction for adjusting the dose, but is blocked from rotating in the reverse direction. In other words, when the stop bracket 131 rotates in the forward direction, the cantilever 1311 can rotate smoothly along the inner ratchet ring 1371, eliminating the rotational force applied to the stop bracket 131. The cantilever 1311 and the inner ratchet ring 1371 cooperate to maintain the relative position of the stop bracket 131. In the absence of external force, the cantilever 1311 cannot rotate in the reverse direction along the inner ratchet ring 1371. The meshing configuration of the cantilever 1311 and the inner ratchet ring 1371 can be seen in FIG7 . In the orientation shown in FIG7 , the cantilever 1311 can rotate clockwise relative to the inner ratchet ring 1371, but due to the obstruction of the inner ratchet ring 1371, the cantilever 1311 cannot rotate counterclockwise relative to the inner ratchet ring 1371.

[0072] It can be understood that the knob 130 can rotate relative to the stop bracket 131 between a first position and a second position.

[0073] After adopting the above solution, when adjusting the dose of the injection pen 100 , the knob 130 is rotated forward. After the knob 130 is rotated to the first position, it drives the stop bracket 131 to rotate together to achieve dose adjustment. When the knob 130 is rotated excessively in the forward direction, the knob 130 can be rotated in the reverse direction. At the beginning of the reverse rotation, the knob 130 is in the first position relative to the stop bracket 131. At this time, when the knob 130 is rotated in the reverse direction, the stop bracket 131 will not rotate with the knob 130 until the knob 130 rotates to the second position. When the knob 130 is rotated from the first position to the second position relative to the stop bracket 131, the arm 1301 of the knob 130 presses radially inward against the cantilever 1311, so that the cantilever 1311 disengages from the inner ratchet ring 1371. Therefore, when the knob 130 continues to rotate in the reverse direction from the second position, it can drive the stop bracket 131 to rotate in the reverse direction without being hindered by the inner ratchet ring 1371, thereby realizing the callback of the dose, which is convenient for accurately calling back the over-adjusted dose.

[0074] As can be seen from the above, the arrangement of the knob assembly and associated structures of the dose adjustment mechanism 13 enables the dose to be adjusted back by rotating the knob assembly after excessive dose adjustment, thereby facilitating the injection pen 100 to more accurately control the injection dose and improving the operability and safety of the injection pen 100.

[0075] In this embodiment, a reset structure is provided between the knob 130 and the stop bracket 131. When the knob 130 is in the aforementioned second position, the reset structure can generate a reset force that causes the knob 130 to rotate forward to the first position. With this arrangement, after the knob 130 is rotated back and the external force applied to the knob 130 is removed, the knob 130 can be rotated forward relative to the stop bracket 131 to the first position under the reset action of the reset structure. This allows the arm 1301 of the knob 130 to no longer exert a radially inward compressive force on the cantilever 1311, allowing the cantilever 1311 to move radially outward to resume engagement with the inner ratchet ring 1371, thereby maintaining the stop bracket 131 in the adjusted position.

[0076] Please refer to Figures 8 to 14, Figure 8 is a structural schematic diagram of the stop bracket in a specific embodiment; Figure 9 is a front view of the stop bracket shown in Figure 8; Figure 10 is a top view of the stop bracket shown in Figure 9; Figure 11 is a bottom view of the stop bracket shown in Figure 9; Figure 12 is a structural schematic diagram of the knob in a specific embodiment from a top view; Figure 13 is a structural schematic diagram of the knob in a specific embodiment from a bottom view; Figure 14 is a structural schematic diagram of the torsion spring bracket in a specific embodiment.

[0077] In a specific implementation, the knob 130 is provided with a sliding groove 1302 extending in the circumferential direction, and the stop bracket 131 is provided with a protrusion 1312 extending in the radial direction. After the stop bracket 131 is assembled with the knob 130, the protrusion 1312 of the stop bracket 131 can extend into the sliding groove 1302 and can rotate circumferentially in the sliding groove 1302; the sliding groove 1302 has a first groove wall 13021 and a second groove wall 13022 in the circumferential direction, which is used to limit the relative position of the knob 130 and the stop bracket 131.

[0078] Specifically, when the protrusion 1312 abuts against the first groove wall 13021, the knob 130 is in the first position relative to the stop bracket 131, as shown in Figure 5. When the knob 130 rotates in the direction of the hollow arrow in Figure 5, that is, in the clockwise direction, since the first groove wall 13021 abuts against the protrusion 1312, the knob 130 can directly drive the stop bracket 131 to rotate in the clockwise direction.

[0079] Specifically, when the protrusion 1312 abuts against the second groove wall 13022, the knob 130 is in the second position relative to the stop bracket 131, as shown in Figure 6. When the knob 130 rotates in the direction of the hollow arrow in Figure 6, that is, counterclockwise, since the second groove wall 13022 abuts against the protrusion 1312, the knob 130 can directly drive the stop bracket 131 to rotate in the counterclockwise direction.

[0080] It can be understood that in the state shown in Figure 5, if the knob 130 rotates in the counterclockwise direction, due to the circumferential gap between the protrusion 1312 and the slide groove 1302, the knob 130 first rotates relative to the stop bracket 131 until the second groove wall 13022 of the slide groove 1302 abuts against the protrusion 1312, and then the stop bracket 131 can be driven to rotate in the counterclockwise direction; in the state shown in Figure 6, if the knob 130 rotates in the clockwise direction, due to the circumferential gap between the protrusion 1312 and the slide groove 1302, the knob 130 first rotates relative to the stop bracket 131 until the first groove wall 13021 of the slide groove 1302 abuts against the protrusion 1312, and then the stop bracket 131 can be driven to rotate in the clockwise direction.

[0081] In a specific configuration, two or more sets of mutually cooperating protrusions 1312 and sliding grooves 1302 may be provided between the knob 130 and the stop bracket 131, and the two sets of mutually cooperating protrusions 1312 and sliding grooves 1302 are evenly arranged along the circumference of the knob 130. In this way, the relative rotation between the knob 130 and the stop bracket 131 is smooth, and the force applied to the two when they rotate together is also balanced.

[0082] The figure illustrates a structure with two sets of mutually cooperating protrusions 1312 and slide grooves 1302 between the knob 130 and the stop bracket 131. In other implementations, if the structure allows, the mutually cooperating protrusions 1312 and slide grooves 1302 can be set to three, four or more sets.

[0083] In the illustrated example, the protrusion 1312 is provided on the stop bracket 131, and the slide groove 1302 is provided on the knob 130. In other implementations, the protrusion 1312 and the slide groove 1302 can also be provided in reverse, that is, the protrusion 1312 is provided on the knob 130, and the slide groove 1302 is formed on the stop bracket 131.

[0084] In a specific implementation, the reset structure between the aforementioned knob 130 and the stop bracket 131 includes a limiting rib 1313 and a limiting hole 1303 extending along the circumferential direction. In the illustrated example, the limiting rib 1313 is provided on the stop bracket 131, and the limiting hole 1303 is provided on the knob 130. The limiting rib 1313 extends into the limiting hole 1303. The two are configured as follows: when the knob 130 is in the second position, the limiting rib 1313 is squeezed and deformed by the wall of the limiting hole 1303 to generate a deformation force that causes the knob 130 to rotate toward the first position. In other words, when the knob 130 rotates relative to the stop bracket 131, the limiting rib 1313 can also slide circumferentially in the limiting hole 1303, but the sliding stroke of the limiting rib 1313 in the limiting hole 1303 is smaller than the sliding stroke of the protrusion 1312 in the slide groove 1302. In this way, after the knob 130 is rotated to the second position relative to the stop bracket 131, the limiting rib 1313 is limited by the sliding stroke in the limiting hole 1303 and is squeezed and deformed by the hole wall of the limiting hole 1303. After the external force on the knob 130 is removed, the limiting rib 1313 is reset under the action of the deformation force and the knob 130 is rotated toward the first position, so as to release the pressing force of the arm 1301 of the knob 130 on the cantilever 1311, so that the cantilever 1311 can be reset to cooperate with the inner ratchet ring 1371 for unidirectional rotation.

[0085] Obviously, the limiting rib 1313 has the ability of compression deformation.

[0086] In other implementations, the limiting rib 1313 may also be provided on the knob 130 , and the limiting hole 1303 matching the limiting rib 1313 may also be formed on the stop bracket 131 .

[0087] In a specific implementation, at least a portion of the stop bracket 131 is internally sheathed within the knob 130. The upper end of the aforementioned power rod 132 passes through the stop bracket 131. A circumferential restraining structure is provided between the power rod 132 and the stop bracket 131, enabling the stop bracket 131 to drive the power rod 132 in rotation. Simultaneously, the power rod 132 is also capable of axial movement relative to the stop bracket 131, switching between a position circumferentially restrained with the stop bracket 131 and a position in which the circumferential restraint with the stop bracket 131 is released. In this way, the stored energy of the torsion spring 136 is released by releasing the circumferential restraint between the power rod 132 and the stop bracket 131.

[0088] In the specific setting, the stop bracket 131 includes a frame tube portion 1314, and the knob 130 includes an outer cylinder part 1304 and an inner cylinder part 1305. The outer cylinder part 1304 is rotatably matched with the upper pen barrel 11, and the frame tube portion 1314 of the stop bracket 131 can be inserted into the inner cylinder part 1305. A structure that cooperates with the stop bracket 131 can be set at the connection part between the outer cylinder part 1304 and the inner cylinder part 1305, such as the aforementioned slide groove 1302, limiting hole 1303, etc.

[0089] In this way, the upper end of the power rod 132 specifically passes through the bracket tube portion 1314 of the stop bracket 131 , and the aforementioned circumferential limiting structure is provided between the power rod 132 and the bracket tube portion 1314 .

[0090] Specifically, the circumferential limiting structure between the power rod 132 and the bracket 1314 includes a first inner gear ring 1315 provided on the bracket 1314 and a first latching tooth 1324 provided on the power rod 132. Under normal conditions, the first latching tooth 1324 of the power rod 132 and the first inner gear ring 1315 of the stop bracket 131 are in the same axial position. The first latching tooth 1324 can be engaged with the tooth groove of the first inner gear ring 1315, thereby driving the power rod 132 to rotate when the stop bracket 131 rotates. When the power rod 132 moves axially relative to the stop bracket 131 under the action of an external force, the first latching tooth 1324 of the power rod 132 can disengage from the first inner gear ring 1315, thereby releasing the circumferential limit between the power rod 132 and the stop bracket 131.

[0091] In this embodiment, the axial movement of the power rod 132 is achieved by operating the aforementioned button mechanism 12. The button mechanism 12 is provided at the upper end of the power rod 132 and includes a button assembly 121 and a reset elastic member 123. The button assembly 121 is axially limitedly connected to the power rod 132.

[0092] After pressing the button assembly 121, the power rod 132 can be pushed axially downward to release the circumferential limit with the stop bracket 131. After the pressing force on the button assembly 121 is cancelled, the button assembly 121 can be reset under the action of the reset elastic member 123, driving the power rod 132 to move axially upward to restore the circumferential limit with the stop bracket 131.

[0093] 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.

[0094] 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.

[0095] Since the sleeve 135 and the power rod 132 are relatively fixed, the power rod 132 can drive the sleeve 135 to move downward in the axial direction when the button mechanism 12 is pressed, thereby realizing the transmission engagement between the sleeve 135 and the driving wheel 141. When resetting, the power rod 132 and the sleeve 135 move upward in the axial direction together, thereby realizing the separation of the sleeve 135 and the driving wheel 141.

[0096] 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.

[0097] Please also refer to FIG. 15 , which is a schematic structural diagram of the sleeve in a specific embodiment.

[0098] In this embodiment, the sleeve 135 includes an insertion rod portion 1351, which can be inserted into the socket of the power rod 132. The cross-section of the insertion rod portion 1351 and the socket of the power rod 132 is a non-circular structure, so that when the power rod 132 rotates, it can drive the sleeve 135 to rotate together.

[0099] A convex portion and a concave portion that are embedded in the radial direction are further provided between the sleeve 135 and the power rod 132 to achieve axial limitation of the sleeve 135 and the power rod 132, so that the power rod 132 can drive the sleeve 135 to move axially together.

[0100] The sleeve 135 further includes an inner tube portion 1352 and an outer tube portion 1353 , the bottom ends of which are connected to form a space therebetween for accommodating the aforementioned torsion spring 136 .

[0101] A plurality of radially outwardly extending ribs 1355 are provided on the outer wall of the sleeve 135 near the bottom end, i.e., at the bottom end of the outer cylindrical portion 1353. The ribs 1355 are arranged along the circumference of the sleeve 135 to correct the concentricity of the sleeve 135 and the upper barrel 11. This ensures reliable engagement of the sleeve 135 with the transmission mechanism 14, thereby achieving reliable power transmission.

[0102] The use process of the injection pen 100 can be briefly described as follows: dose adjustment stage: rotate the knob 130 forward, driving the stop bracket 131 and the power rod 132 to rotate together, 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; if the adjustment is excessive, the knob 130 can be rotated backward to adjust; after the dose is adjusted, the cantilever 1311 of the stop bracket 131 cooperates with the inner ratchet ring 1371 of the torsion spring bracket 137, so that the stop bracket 131, the power rod 132, the sleeve 135 and the torsion spring 136 are kept in this position; injection stage: press the button The button assembly 121 of the button mechanism 12 pushes the power rod 132 to move downward in the axial direction, 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 131, 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 downward in the axial direction to push the bottle stopper 231 to realize drug injection.

[0103] 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 an injection pen, characterized in that, It includes a knob, a stop bracket, and a torsion spring bracket; The knob is capable of driving the stop bracket to rotate relative to the torsion spring bracket; The stop bracket is provided with a cantilever, the torsion spring bracket has an internal ratchet ring, and the cantilever and the internal ratchet ring are in one-way rotational cooperation in the direction of adjusting the dose; the knob is provided with an arm portion located outside the cantilever; The knob is also capable of rotating relative to the stop bracket to switch between a first position and a second position. In the first position, the knob can directly drive the stop bracket to rotate in the direction of adjusting the dose, and the cantilever and the internal ratchet ring are in one-way rotational cooperation. In the second position, the arm portion presses the cantilever radially inward to disengage the cantilever from the internal ratchet ring; the knob can directly drive the stop bracket to rotate in the direction opposite to the adjustment of the dose.

2. The dose adjustment mechanism according to claim 1, characterized in that, Among the knob and the stop bracket, one is provided with a convex block extending radially, and the other is provided with a chute extending circumferentially. The convex block extends into the chute and can rotate circumferentially in the chute. The chute has a first groove wall and a second groove wall in the circumferential direction. The convex block abuts against the first groove wall, and the knob is in the first position. The convex block abuts against the second groove wall, and the knob is in the second position.

3. The dose adjustment mechanism according to claim 2, characterized in that, There are more than two sets of the mutually cooperating convex block and the chute, and they are evenly arranged along the circumference of the knob.

4. The dose adjustment mechanism according to claim 1, characterized in that, A reset structure is provided between the knob and the stop bracket. When the knob is in the second position, the reset structure can generate a reset force that causes the knob to rotate in the direction of adjusting the dose to the first position.

5. The dose adjustment mechanism according to claim 4, characterized in that, The reset structure includes a limiting rib and a limiting hole extending circumferentially. One of the limiting rib and the limiting hole is provided on the knob, and the other is provided on the stop bracket. The limiting rib extends into the limiting hole and is configured such that when the knob is in the second position, the limiting rib is squeezed by the hole wall of the limiting hole to generate a deformation force that causes the knob to rotate in the direction of the first position.

6. The dose adjustment mechanism according to any one of claims 1-5, characterized in that, The dose adjustment mechanism further includes a power rod, At least a part of the stop bracket is sleeved inside the knob, the upper end of the power rod passes through the stop bracket, and a circumferential limiting structure is provided between the power rod and the stop bracket so that the stop bracket can drive the power rod to rotate; The power rod can axially move relative to the stop bracket to switch between a position where it is circumferentially limited to the stop bracket and a position where the circumferential limitation with the stop bracket is released.

7. The dose adjustment mechanism according to claim 6, characterized in that, The stop bracket includes a barrel portion, the knob includes an outer barrel member and an inner barrel member, the barrel portion is sleeved inside the inner barrel member, and the outer barrel member is used for rotatably cooperating with the upper barrel of the injection pen; the circumferential limiting structure is provided between the power rod and the barrel portion.

8. The dose adjustment mechanism according to claim 7, characterized in that, The dose adjustment mechanism further includes a cylinder body, a ball, a sleeve, and a torsion spring; The cylinder body is sleeved outside the power rod and inserted inside the barrel portion. A spiral channel extending along the axial direction of the power rod is formed between the inner barrel wall of the cylinder body and the outer rod wall of the power rod, and the ball is rotatably provided in the spiral channel; The cylinder body is circumferentially and limit-connected to the torsion spring bracket; the power rod and the sleeve are relatively fixed, the upper end of the torsion spring is connected to the torsion spring bracket, and the lower end of the torsion spring is connected to the sleeve.

9. The dose adjustment mechanism according to claim 8, characterized in that, A plurality of ribs extending radially outward are provided on the outer cylinder wall of the sleeve near the bottom end, and the plurality of ribs are arranged circumferentially along the sleeve to correct the concentricity between the sleeve and the upper pen barrel of the injection pen.

10. An injection 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 1-9.