Automatic injection pen

Abstract

This application relates to an automatic injection pen. It includes: a housing; a screw; a dosage setting knob; a dosage indicator ring; a screw sleeve; a dosage indicator ring support frame, wherein during dosage setting, the dosage indicator ring support frame rotates in conjunction with the dosage indicator ring and the screw sleeve; a circumferentially arranged elastic arm is provided at the distal end of the dosage indicator ring support frame, and at least one first externally projecting tooth is provided on the elastic arm; a first internal toothed ring is provided on the inner wall of the distal end of the housing, engaging with the first externally projecting tooth; a gripper extending through the dosage indicator ring support frame and capable of clamping the elastic arm is provided on the outer wall of the screw sleeve; a torsion spring; and an injection button. When subjected to an axial force towards the distal end, the screw sleeve moves distally, the gripper radially compresses the elastic arm inward, causing the first externally projecting tooth to disengage, the torsion of the torsion spring is released, pushing the dosage indicator ring support frame to rotate, and driving the screw sleeve to rotate, thereby driving the screw to perform a helical motion for injection. The technical solution of this application makes the dosage setting process more stable.

Description

Technical Field

[0001] This application relates to the field of medical devices, and in particular to an automatic injection pen. Background Technology

[0002] A syringe is a common medical device. The principle of the syringe was understood as early as the 15th century. It primarily uses a needle to draw or inject gas or liquid. Syringes can also be used in medical devices and as containers for injectable solutions, such as in some chromatographic instruments where injection is performed through a rubber diaphragm. A syringe consists of a syringe barrel with a small hole at the front and a matching piston rod. It is used to inject small amounts of liquid or other substances into or extract them from areas inaccessible by other methods. When the piston rod is pulled out, the liquid or gas is drawn in through the small hole at the front of the syringe barrel; when the piston rod is pushed in, the liquid or gas is expelled.

[0003] For diabetic patients, artificial insulin is administered via subcutaneous injection. To prevent contamination, the insulin is contained in a specially designed vial with a plunger at one end. During injection, the syringe pushes the plunger, squeezing the insulin out through the needle and into the body. Since the dosage varies among different diabetic patients, the syringe needs a precisely controlled dosage mechanism. However, current syringes for precise dosage control suffer from complex structures and high manufacturing costs. Summary of the Invention

[0004] In view of this, the present application provides an automatic injection pen to solve at least one problem existing in the background art.

[0005] To achieve the above objectives, the technical solution of this application is implemented as follows:

[0006] This application provides an automatic injection pen, comprising:

[0007] shell;

[0008] The screw is used to move the piston inside the injection container to perform injection;

[0009] Dosage setting knob, used to set the dosage by turning it;

[0010] A dose indicator ring is used to indicate the dose to be injected.

[0011] The screw sleeve rotates in sync with the rotation of the dosage setting knob when the dosage is set.

[0012] A dose indicator ring support frame, when setting the dose, rotates in conjunction with the dose indicator ring and the screw sleeve to transmit the torque of the screw sleeve to the dose indicator ring; an elastic arm is circumferentially provided at the distal end of the dose indicator ring support frame, and at least one first external protruding tooth is provided on the elastic arm; a first internal toothed ring that meshes with the first external protruding tooth is provided on the inner wall of the distal end of the outer shell; the outer wall of the screw sleeve is provided with a clamping claw that extends through the dose indicator ring support frame and can clamp the elastic arm;

[0013] A torsion spring, which rotates along with the rotation of the dose indicator ring support frame when the dose is set, in order to accumulate torque potential energy;

[0014] The injection button axially abuts against the screw sleeve. When the injection button is subjected to an axial force towards the distal end, it drives the screw sleeve to move axially towards the distal end. The gripper radially squeezes the elastic arm to retract inward, causing the first external tooth to disengage from the first internal tooth ring. This releases the torque of the torsion spring, pushes the dose indicator ring support frame to rotate, and drives the screw sleeve to rotate, thereby driving the screw to perform a spiral descent motion for injection.

[0015] Optionally, the meshing edges of the teeth of the first internal tooth ring and the first external tooth are asymmetrical on both sides, so that the rotational resistance of the dose indicator ring support frame in the first direction is less than the rotational resistance in the second direction; the first direction is the rotation direction of the dose setting knob to increase the dose, and the second direction is the rotation direction of the dose setting knob to decrease the dose.

[0016] Optionally, the elastic arm is provided with a reversing protrusion located on one side of the circumferential rotation trajectory of the gripper; when the screw sleeve rotates in the second direction, the gripper can circumferentially squeeze the reversing protrusion, forcing the elastic arm to contract inward, reducing the meshing depth between the first external tooth and the first internal tooth ring, thereby reducing the resistance to reversal.

[0017] Optionally, the inner wall of the housing is provided with a hook groove for accommodating the hook of the torsion spring; the radial width of the hook groove is greater than the radial width of the hook.

[0018] Optionally, the circumferential length of the hook groove abutting the inner wall of the hook is shorter than the circumferential length of the hook, so that the hook does not contact the outer casing at the opening of the hook groove.

[0019] Optionally, the automatic injection pen further includes:

[0020] A dose-limiting lock is installed on the inner wall of the screw sleeve and fitted onto the screw. When setting the dose, the rotation of the screw sleeve drives the dose-limiting lock to move helically towards the proximal end until the top of the dose-limiting lock abuts against the screw and can no longer move helically upwards. During injection, the dose-limiting lock remains axially stationary relative to the screw. When setting the dose, the stroke of the dose-limiting lock's helical movement on the screw corresponds to the amount of injection solution remaining in the injection container.

[0021] Optionally, the outer shell includes a tube, and the inner wall of the distal end of the tube is provided with a first positioning groove and a second positioning groove arranged in axial sequence, both extending axially; the outer wall of the screw support is provided with a first positioning protrusion that cooperates with the first positioning groove to limit the circumferential position of the screw support; the second positioning groove is used to limit the circumferential position of the injection container.

[0022] Optionally, the automatic injection pen further includes:

[0023] The first sound-generating device includes a first sound-generating structure and a second sound-generating structure that cooperate with each other; the first sound-generating structure is disposed at the proximal end of the dose indicator ring and includes a third positioning groove and an inclined surface extending to the third positioning groove; the second sound-generating structure is disposed at the proximal end of the housing and includes a third positioning protrusion that matches the third positioning groove; during injection, the dose indicator ring rotates spirally until the third positioning protrusion passes the inclined surface and enters the third positioning groove.

[0024] Optionally, the dose indicator ring includes a scale marking, which includes an exhaust mark; the exhaust mark is located between the zero mark and the maximum mark.

[0025] Optionally, the dose indicator ring has a circumferential fourth positioning groove at its proximal end, and the outer shell is provided with a fourth positioning protrusion that is inserted into the fourth positioning groove to limit the axial position of the dose indicator ring at the zero mark.

[0026] The automatic injection pen of this application embodiment features an elastic arm and a first external tooth on the dose indicator ring support frame, and a first internal toothed ring on the outer shell. The engagement of the first external tooth and the first internal toothed ring maintains the stable position of the dose indicator ring during dose setting. During injection, the elastic arm is radially gripped by a jaw on the screw sleeve, causing the elastic arm to retract inward. This disengages the first external tooth from the first internal toothed ring, and the torsion of the torsion spring drives the screw to descend spirally for injection. The structure is simpler, and the scale is more stable and accurate during dose setting and injection. Therefore, the automatic injection pen of this application embodiment has a simpler structure and provides more stable and accurate scale during dose setting and injection.

[0027] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0029] Figure 1 This is a schematic diagram of the appearance of the automatic injection pen provided in the embodiments of this application;

[0030] Figure 2 for Figure 1 A sectional view;

[0031] Figure 3 for Figure 2 A diagram showing the disassembled injection container;

[0032] Figure 4 An exploded view (dissolved diagram) of the automatic injection pen provided in the embodiments of this application.

[0033] Figure 5 A schematic diagram of the main components of the automatic injection pen provided in the embodiments of this application;

[0034] Figure 6 A schematic diagram of the screw and dose-limiting lock in an automatic injection pen provided in an embodiment of this application;

[0035] Figure 7 A schematic diagram of the dosage setting knob in the automatic injection pen provided in the embodiments of this application;

[0036] Figure 8 A schematic diagram of the screw sleeve in the automatic injection pen provided in the embodiments of this application;

[0037] Figure 9 A schematic diagram of a dose indicator ring in an automatic injection pen provided in an embodiment of this application;

[0038] Figure 10 A schematic diagram of the dose indicator ring support frame in the automatic injection pen provided in the embodiments of this application;

[0039] Figure 11 for Figure 10 A magnified view of a portion of the central structure;

[0040] Figure 12 A schematic diagram of the screw anti-rotation bracket in the automatic injection pen provided in the embodiments of this application;

[0041] Figure 13A schematic diagram of one perspective of the fixed end cap in an automatic injection pen provided in an embodiment of this application;

[0042] Figure 14 A schematic diagram of the tube in an automatic injection pen provided in an embodiment of this application;

[0043] Figure 15 A schematic diagram of the dose indicator ring and fixed end cap in the automatic injection pen provided in the embodiments of this application;

[0044] Figure 16 for Figure 15 A magnified view of a portion of the central structure;

[0045] Figure 17 An assembly diagram of the fixed end cap and torsion spring in an automatic injection pen provided in this application embodiment;

[0046] Figure 18 A schematic diagram of the screw support in the automatic injection pen provided in the embodiments of this application;

[0047] Figure 19 A schematic diagram of the tube in an automatic injection pen provided in an embodiment of this application;

[0048] Figure 20 A schematic diagram showing the connection between the screw sleeve and the injection button in the automatic injection pen provided in this application embodiment;

[0049] Figure 21 for Figure 20 A magnified view of a portion of point A in the middle;

[0050] Figure 22 Another schematic diagram of the dosage indicator ring in the auto-injection pen provided in the embodiments of this application.

[0051] Explanation of reference numerals in the attached figures:

[0052] 10. Outer shell; 11. Tube body; 111. First positioning groove; 112. Second positioning groove; 113. First internal gear ring; 114. Second internal thread; 12. Fixed end cap; 122. Third positioning protrusion; 123. Hook groove; 124. Fourth positioning protrusion; 125. Snap protrusion; 13. Screw bracket; 131. First internal thread; 14. Snap groove; 15. Viewing window;

[0053] 20. Screw; 21. First external thread; 23. First outer plane; 24. Dosage limiting lock; 241. Rotary linkage positioning protrusion; 25. Second stop;

[0054] 30. Screw anti-rotation bracket; 31. Fifth external gear ring; 32. First inner plane;

[0055] 40. Dosage setting knob; 41. Second internal gear ring;

[0056] 50. Dosage indicator ring; 51. Second external thread; 52. Fourth internal rib; 53. Third positioning groove; 54. Inclined surface; 55. Fourth positioning groove; 56. Exhaust mark;

[0057] 60. Dosage indicator ring support frame; 61. Third inner protrusion; 62. Fourth outer rib; 63. Elastic arm; 631. First outer tooth; 632. Injection protrusion; 633. Reversal protrusion;

[0058] 70. Screw sleeve; 71. Second external gear ring; 72. Third external protrusion; 73. Fifth internal gear ring; 74. Rotary linkage positioning groove; 75. Stepped hole; 76. Clamping jaw;

[0059] 81. Injection button; 811. Barb; 812. Button return spring; 82. Torsion spring; 821. Hook;

[0060] 90. Injection container; 91. Piston. Detailed Implementation

[0061] To make the technical solution and beneficial effects of this application more apparent and understandable, a detailed description is provided below by listing specific embodiments. The accompanying drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features; unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical field to which this application pertains.

[0062] In the description of this application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "height", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used for the purpose of simplifying the description of this application and do not indicate that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. In other words, they should not be construed as limitations on this application.

[0063] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating the relative importance of the indicated features or the number of indicated technical features. Therefore, a feature specified as "first" or "second" may explicitly include at least one of those features. In the description of this application, "multiple" means at least two, such as two, three, etc.; "several" means at least one, such as one, two, three, etc., unless otherwise explicitly specified.

[0064] In this application, unless otherwise expressly defined, the terms "installation," "connection," "linking," "fixing," "setting," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0065] In this application, unless otherwise expressly defined, the terms "above," "on top of," "over," "above," "below," "below," "below," or "below" for "first feature over second feature" can refer to the first and second features being in direct contact, or to the first and second features being in indirect contact through an intermediate medium. Furthermore, "above," "over," and "below" for "first feature over second feature" can mean the first feature is directly above or diagonally above the second feature, or simply indicates that the horizontal height of the first feature is higher than the horizontal height of the second feature. Similarly, "below," "below," and "below" for "first feature over second feature" can mean the first feature is directly below or diagonally below the second feature, or simply indicates that the horizontal height of the first feature is lower than the horizontal height of the second feature.

[0066] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solution of this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0067] To address the technical problems in related technologies, embodiments of this application provide an automatic injection pen. (Reference) Figures 1-5 The automatic injection pen includes:

[0068] 10 for the outer casing;

[0069] Specifically, the housing 10 may include a distal end connected to the injection container 90 and an opposite proximal end; the housing 10 may have an axially extending accommodating cavity.

[0070] Understandably, the proximal end can be Figure 2 The right end of the middle, the far end can be Figure 2 The left end of the middle. It is understood that distal and proximal are relative terms; for example, screw 20 is located distal to dose setting knob 40 but proximal to injection container 90.

[0071] The screw 20 is used to move the piston 91 inside the injection container 90 to perform injection;

[0072] Specifically, the screw 20 can be located within the accommodating cavity; see reference. Figure 6 and Figure 18 The outer surface of the screw 20 has a first external thread 21, and the distal end of the housing 10 is provided with a first internal thread 131 that matches the first external thread 21. During injection, the screw 20 is driven to rotate and forms a spiral motion through the cooperation of the first external thread 21 and the first internal thread 131 to push the piston 91 in the injection container 90 to move axially.

[0073] Understandably, since the automatic injection pen is designed with a standard, full-capacity injection container 90 in mind, in order to ensure that the injection dosage is accurate enough, the injection container 90 installed on the automatic injection pen must be removed from the automatic injection pen only after the injection is completed, and cannot be repeatedly removed and reused.

[0074] Specifically, the first external thread 21 and the first internal thread 131 can be a type of transmission thread. More specifically, the first external thread 21 and the first internal thread 131 can be trapezoidal threads.

[0075] Dosage setting knob 40 is used to set the dosage by rotating it;

[0076] Specifically, the dosage setting knob 40 can be used to set the dosage. When setting the dosage, the dosage setting knob 40 rotates in a first direction around the axis of the screw 20 to increase the dosage, or the dosage setting knob 40 rotates in a second direction around the axis of the screw 20 to decrease the dosage.

[0077] Understandably, the first and second directions are relative and not specifically defined. For example, assuming the first direction is clockwise when viewed from the near end, then the second direction is counterclockwise. It's also understandable that by adjusting the structural settings of the components, it could be that if the first direction is counterclockwise when viewed from the near end, then the second direction is clockwise.

[0078] Specifically, refer to Figure 7 and Figure 8 The dosage setting knob 40 has a first inner hole, and the inner wall of the first inner hole is provided with a second internal gear ring 41 including at least one meshing tooth. The outer wall of the screw sleeve 70 is provided with a second external gear ring 71 that mates with the second internal gear ring 41. Through the second internal gear ring 41 and the second external gear ring 71, the dosage setting knob 40 and the screw sleeve 70 establish a rotational linkage relationship. It is understood that other structures capable of establishing rotational linkage can also be used.

[0079] More specifically, the meshing teeth of the second internal gear ring 41 and the second external gear ring 71 can be arranged circumferentially or arranged in a circle circumferentially.

[0080] More specifically, in order to facilitate quick switching between forward and reverse rotation, at least one of the second internal gear ring 41 and the second external gear ring 71 is configured to have at least two meshing teeth, and the spacing between adjacent meshing teeth can only accommodate one meshing tooth of the other gear ring.

[0081] Dosage indicator ring 50, used to indicate the dose to be injected;

[0082] Specifically, the dose indicator ring 50 can be used to indicate the dose to be injected and can rotate spirally in response to the rotation of the dose setting knob 40.

[0083] Specifically, refer to Figure 9 The outer wall of the dose indicator ring 50 is provided with dose numbers arranged in a spiral direction, i.e., scale.

[0084] The screw sleeve 70 can rotate in conjunction with the rotation of the dosage setting knob 40 when the dosage is set;

[0085] Specifically, the screw sleeve 70 can rotate in accordance with the rotation of the dosage setting knob 40; when setting the dosage, the screw sleeve 70 and the dosage indicator ring 50 rotate in linkage; during injection, the screw sleeve 70, the screw 20, and the dosage indicator ring 50 rotate in linkage.

[0086] Intuitively, rotational linkage means that when one rotates circumferentially, the other also rotates circumferentially, without distinguishing between active and passive; it is a two-way linkage.

[0087] Specifically, refer to Figure 14 and Figure 15 The dose indicator ring 50 is provided with a second external thread 51, and the outer casing 10 is provided with a second internal thread 114 that mates with the second external thread 51. Thus, when the dose indicator ring 50 rotates under the drive of the screw sleeve 70, the dose indicator ring 50 spirals up and down.

[0088] More specifically, in order to make the dose indicator ring 50 fit the housing 10 more closely, the thread of the second external thread 51 is recessed into the outer wall of the dose indicator ring 50, and the second internal thread 114 protrudes from the inner wall of the housing 10.

[0089] Specifically, refer to Figure 8 and Figure 10 The outer wall of the screw sleeve 70 is provided with a third outer protrusion 72, and the inner wall of the dose indicator ring support frame 60 is provided with a third inner protrusion 61 that mates with the third outer protrusion 72. Through the third inner protrusion 61 and the third outer protrusion 72, the screw sleeve 70 and the dose indicator ring support frame 60 establish a rotational linkage relationship. It is understood that other structures capable of establishing rotational linkage could also be used.

[0090] More specifically, the meshing teeth of the third inner protrusion 61 and the third outer protrusion 72 can be arranged circumferentially or arranged in a circle.

[0091] More specifically, in order to facilitate quick switching between forward and reverse rotation, at least one of the third inner protrusion 61 and the third outer protrusion 72 is configured to have at least two protrusions, and the spacing between adjacent protrusions is only able to accommodate one of the other protrusions.

[0092] The dose indicator ring support frame 60, when setting the dose, rotates in conjunction with the dose indicator ring 50 and the screw sleeve 70 to transmit the torque of the screw sleeve 70 to the dose indicator ring 50; an elastic arm 63 is circumferentially provided at the distal end of the dose indicator ring support frame 60, and at least one first external protruding tooth 631 is provided on the elastic arm 63; a first internal tooth ring 113 that meshes with the first external protruding tooth 631 is provided on the inner wall of the distal end of the outer casing 10; the outer wall of the screw sleeve 70 is provided with a clamping claw 76 that extends out of the dose indicator ring support frame 60 and can clamp the elastic arm 63.

[0093] Specifically, the dose indicator ring support 60 can be used to transmit the torque of the screw sleeve 70 to the dose indicator ring 50; when setting the dose, the dose indicator ring support 60 is rotated in conjunction with the dose indicator ring 50 and the screw sleeve 70; Reference Figure 8 and Figure 10 The dose indicator ring support frame 60 is provided with an elastic arm 63 circumferentially at its distal end. The elastic arm 63 is provided with at least one first external tooth 631. The inner wall of the distal end of the outer shell 10 is provided with a first internal tooth ring 113 that meshes with the first external tooth 631. The outer wall of the screw sleeve 70 is provided with a gripper 76 that extends out of the dose indicator ring support frame 60 and can clamp the elastic arm 63.

[0094] The elastic arm 63 is elastic enough to maintain the meshing state of the first external tooth 631 and the first internal tooth ring 113.

[0095] Understandably, the meshing state of the first external tooth 631 and the first internal tooth ring 113 can hinder the circumferential rotation of the dose indicator ring support frame 60, thereby overcoming the torque potential energy of the torsion spring 82 and maintaining the position of the dose indicator ring 50 in the dose setting stage when the injection stage has not yet begun.

[0096] Specifically, refer to Figure 9 and Figure 10The outer wall of the dose indicator ring support frame 60 is provided with a fourth outward protruding rib 62, and the inner wall of the dose indicator ring 50 is provided with a fourth inward protruding rib 52 that cooperates with the fourth outward protruding rib 62. Through the fourth inward protruding rib 52 and the fourth outward protruding rib 62, the dose indicator ring 50 and the dose indicator ring support frame 60 establish a rotational linkage relationship. It is understood that other structures capable of establishing rotational linkage could also be used.

[0097] When the screw sleeve 70 and the dose indicator ring support frame 60 establish a rotational linkage relationship, and the dose indicator ring 50 and the dose indicator ring support frame 60 establish a rotational linkage relationship, the screw sleeve 70 and the dose indicator ring 50 establish a rotational linkage relationship. It is understood that other structures capable of establishing a rotational linkage may also be used.

[0098] More specifically, the ribs of the fourth inner rib 52 and the fourth outer rib 62 can be arranged circumferentially or arranged in a circle.

[0099] More specifically, in order to facilitate quick switching between forward and reverse rotation, at least one of the fourth inner rib 52 and the fourth outer rib 62 is configured to have at least two ribs, and the spacing between adjacent ribs is only enough to accommodate one of the other ribs.

[0100] Understandably, the elastic arm 63 is a cantilever at one end in the circumferential direction, so the cantilever can generate radial elasticity to maintain the meshing state of the first external tooth 631 and the first internal tooth ring 113.

[0101] Torsion spring 82 rotates along with the rotation of the dose indicator ring support frame 60 when the dose is set, in order to accumulate torque potential energy;

[0102] Specifically, the proximal end of the torsion spring 82 is connected to the housing 10, and the distal end is connected to the dose indicator ring support frame 60; when setting the dose, the torsion spring 82 rotates along with the rotation of the dose indicator ring support frame 60 to accumulate torque potential energy.

[0103] Specifically, refer to Figure 11 The torsion spring 82 has connecting portions at both its proximal and distal ends. More specifically, the connecting portion can be a hook 821. The connecting portion at the proximal end of the torsion spring 82 is connected to the housing 10, and the connecting portion at the distal end is connected to the dose indicator ring support frame 60.

[0104] Injection button 81 axially abuts against the screw sleeve 70; when injection button 81 is subjected to an axial force toward the distal end, it drives the screw sleeve 70 to move axially toward the distal end, the gripper 76 radially squeezes the elastic arm 63 to retract inward, causing the first external tooth 631 to disengage from the meshing state with the first internal tooth ring 113, thereby releasing the torque of the torsion spring 82, pushing the dose indicator ring support frame 60 to rotate, and driving the screw sleeve 70 to rotate, thereby driving the screw 20 to perform a spiral descent motion for injection.

[0105] Specifically, the injection button 81 can axially abut against the screw sleeve 70; the injection button 81 moves axially distally, and the automatic injection pen enters the injection working state; the injection button 81 drives the screw sleeve 70 to move axially distally, and the elastic arm 63 is radially clamped by the gripper 76, causing the elastic arm 63 to retract inward, thereby causing the first external protruding tooth 631 to disengage from the first internal tooth ring 113; the dose indicator ring support frame 60 rotates in the second direction under the torque of the torsion spring 82; driving the screw sleeve 70 to rotate, thereby driving the screw 20 to perform a spiral descent motion for injection.

[0106] Specifically, refer to Figure 8 and Figure 10 The elastic arm 63 is provided with an injection protrusion 632. The outer diameter of the injection protrusion 632 gradually increases from the proximal end to the distal end. Therefore, as the screw sleeve 70 moves axially towards the distal end, the gradually increasing clamping radius of the injection protrusion 632 forces the elastic arm 63 to retract inward. Specifically, the gripper 76 extends through the dose indicator ring support 60, allowing the gripper 76 to radially clamp the elastic arm 63. When not injecting, the gripper 76 remains axially stationary, only lightly contacting the elastic arm 63. During injection, the axial movement of the screw sleeve 70 allows the gripper 76 to gradually contact the larger outer diameter portion of the injection protrusion 632, thereby achieving the effect of retracting the elastic arm 63.

[0107] More specifically, the injection protrusion is provided with a conical or arcuate surface, so that the outer diameter gradually increases from the proximal end to the distal end.

[0108] Specifically, refer to Figure 1 The injection button 81 is equipped with a button reset spring 812 to push the injection button 81 to reset after the injection is completed.

[0109] Specifically, the automatic injection pen may further include a screw anti-rotation bracket 30, which is rotatably mounted on the inner wall of the distal end of the housing 10 and rotates in linkage with the screw 20; during injection, the screw sleeve 70 moves axially to the distal end and establishes rotational linkage with the screw anti-rotation bracket 30, so that the screw sleeve 70 and the screw 20 rotate in linkage.

[0110] Specifically, during injection, the screw sleeve 70 moves distally under the push of the injection button 81. After moving to a certain position, it circumferentially couples with the screw anti-rotation bracket 30, establishing a rotational linkage. When the screw sleeve 70 is rotated by the dose indicator ring support frame 60, the screw anti-rotation bracket 30 rotates along with the screw sleeve 70. Furthermore, the screw anti-rotation bracket 30 and the screw 20 have a rotational linkage relationship. Therefore, the rotation of the screw anti-rotation bracket 30 will drive the rotation of the screw 20. Combined with the engagement of the first external thread 21 and the first internal thread 131 described above, the screw 20 performs a helical rotation.

[0111] Specifically, refer to Figure 8 The inner wall of the screw sleeve 70 is provided with a fifth internal gear ring 73, which includes at least one meshing tooth. The outer wall of the screw anti-rotation bracket 30 is provided with a fifth external gear ring 31 that mates with the fifth internal gear ring 73. Through the fifth internal gear ring 73 and the fifth external gear ring 31, the screw sleeve 70 and the screw anti-rotation bracket 30 establish a rotational linkage relationship. It is understood that other structures capable of establishing rotational linkage can also be used.

[0112] More specifically, the meshing teeth of the fifth internal gear ring 73 and the fifth external gear ring 31 can be arranged circumferentially, or arranged in a circle circumferentially.

[0113] More specifically, in order to facilitate quick switching between forward and reverse rotation, at least one of the fifth internal gear ring 73 and the fifth external gear ring 31 is configured to have at least two meshing teeth, and the spacing between adjacent meshing teeth can only accommodate one meshing tooth of the other gear ring.

[0114] Specifically, refer to Figure 6 and Figure 12 The outer surface of the screw 20 is provided with at least one first outer plane 23, and the screw anti-rotation bracket 30 has a second inner hole and is sleeved on the push rod. The inner wall of the second inner hole is provided with at least one first inner plane 32 that mates with the first outer plane 23. Through the first outer plane 23 and the first inner plane 32, the screw 20 and the screw anti-rotation bracket 30 establish a rotational linkage relationship.

[0115] More specifically, the outer surface of the screw 20 can be provided with two symmetrical first outer planes 23, and correspondingly, two first inner planes 32 are also provided in the second inner hole to form an oblong hole. This makes it easier to process.

[0116] It should be noted that when setting the dosage, the axial position of the screw sleeve 70 remains stationary, and the screw anti-rotation bracket 30 is not circumferentially linked with the screw sleeve 70. Therefore, the screw sleeve 70 and the screw 20 cannot establish rotational linkage. Thus, when setting the dosage, the screw sleeve 70 rotates, driving the dosage indicator ring support bracket 60 to rotate, which in turn drives the dial to rotate, while the screw 20 remains stationary.

[0117] Understandably, the automatic injection pen of this application embodiment is an injection pen that injects a set dose, and therefore includes two working states: setting the dose and injection, or two stages: setting the dose and injection. The working process of the two working states is briefly described below:

[0118] 1) Setting the dosage. Rotating the dosage setting knob 40 causes the screw sleeve 70 to rotate, which in turn causes the dosage indicator ring support frame 60 to rotate. The dosage indicator ring support frame 60 then causes the dosage indicator ring 50 to rotate. Since the dosage indicator ring 50 has a second external thread 51 and the outer casing 10 has a second internal thread 114, the dosage indicator ring 50 spirals up and down. The corresponding scale can be seen through the transparent or perforated viewing window 15 of the outer casing 10. Therefore, the required dosage can be set by rotating the dosage setting knob 40.

[0119] Specifically, before setting the dose, the dose indicator ring 50 is located proximally, and the viewing window 15 of the housing 10 displays a zero scale. The dose indicator ring 50 can only move distally and cannot move in the opposite direction (this is called the proximally locked position). The dose setting knob 40 can only rotate in the first direction of increasing the dose, i.e., forward rotation, and cannot rotate in the opposite direction. Only when the scale is not zero can the dose setting knob 40 rotate in the second direction of decreasing the dose. For example, if the dose adjustment exceeds the required dose, it can be rotated in the opposite direction to decrease the dose. The dose indicator ring 50 moves in the opposite direction, but the resistance to reverse rotation is greater than the resistance to forward rotation.

[0120] Simultaneously, the rotation of the dose indicator ring support frame 60 will drive the torsion spring 82 to rotate, thus accumulating torque potential energy. Furthermore, the first external tooth 631 and the first internal tooth ring 113 remain engaged under the elastic force of the elastic arm 63. Without the action of external force, the torque potential energy accumulated by the torsion spring 82 cannot drive the dose indicator ring support frame 60 to rotate in the opposite direction.

[0121] It should be noted that when setting the dosage, the screw 20 remains stationary in both the axial and circumferential directions to maintain the accuracy of the injection dosage.

[0122] 2) Injection. Press the injection button 81 axially. The injection button 81 axially pushes the screw sleeve 70 to move axially to the distal end. The jaws 76 of the screw sleeve 70 radially clamp the elastic arm 63, causing the elastic arm 63 to retract inward. This causes the first external tooth 631 to disengage from the first internal tooth ring 113, releasing the torque potential energy of the torsion spring 82. This releases the dose indicator ring support frame 60, causing it to rotate in the opposite direction. The reverse rotation of the dose indicator ring support frame 60 causes the screw sleeve 70 to rotate in the opposite direction. The reverse rotation of the screw sleeve 70 causes the screw 20 to rotate in the opposite direction, causing the screw 20 to move spirally to the distal end, squeezing the piston 91 in the injection container 90 and ejecting the injection solution.

[0123] Simultaneously, the dose indicator ring 50 spirals up and down as the dose indicator ring support frame 60 rotates, gradually decreasing the scale until the viewing window 15 of the housing 10 returns to zero, and the dose indicator ring 50 returns to the proximal locking position. Since the dose indicator ring 50 can no longer move after returning to the proximal locking position, the torque potential energy of the torsion spring 82 can no longer drive the dose indicator ring support frame 60 to rotate in the opposite direction, and correspondingly, the torque potential energy accumulated in the torsion spring 82 is also completely released.

[0124] Understandably, as mentioned earlier, injection can only be performed if the display window 15 of the housing 10 does not show a zero scale after the dosage is set, i.e., the scale is greater than zero. Understandably, when the scale is greater than zero, the position of the dosage indicator ring 50 (called the dosage setting position), i.e., the spiral lifting stroke from the proximal locking position, corresponds to the scale. That is, during injection, the dosage indicator ring 50 moves from the dosage setting position to the proximal locking position, or in other words, the display window 15 of the housing 10 changes from the set scale to the zero scale, and the screw 20 can cause the injection container 90 to inject the set dosage through axial movement. This requires structural design through calculation to adapt the movement of the dosage indicator ring 50 and the screw 20, for example, to make the first external thread 21 and the second external thread 51 have appropriate pitches, etc.

[0125] Understandably, the automatic injection pen of this application embodiment needs to be used in conjunction with an injection container 90. The injection container 90 can be a cartridge bottle, with the distal end of the cartridge bottle serving as the injection outlet and the proximal end equipped with a piston 91, which is generally a rubber stopper. After the injection container 90 is installed on the automatic injection pen, the screw 20 is axially connected to the piston 91. In this way, the axial movement of the screw 20 can push the piston 91 to move distally, squeezing the injection fluid out from the injection outlet. It is understood that other types of injection containers 90 can also be used.

[0126] The automatic injection pen of this application embodiment features an elastic arm 63 and a first external tooth 631 on the dose indicator ring support frame 60, and a first internal toothed ring 113 on the outer shell. The engagement of the first external tooth 631 and the first internal toothed ring 113 maintains the stable position of the dose indicator ring 50 during dose setting. During injection, the gripper 76 on the screw sleeve 70 radially clamps the elastic arm 63, causing it to retract inward. This disengages the first external tooth 631 from the first internal toothed ring 113, and the torsion of the torsion spring 82 drives the screw 20 to descend spirally for injection. The structure is simpler, and the calibration is more stable and accurate during dose setting and injection.

[0127] Furthermore, compared to other embodiments, the technical solution of maintaining the position of the dose indicator ring 50 by the engagement of the end face toothed ring has the following advantages:

[0128] A) More stable scale. The movement trajectory of the end face gear ring is circular, similar to the direction of torque movement of a torsion spring, making it more susceptible to the influence of the torsion spring's force. This leads to instability in the end face gear ring's state, thus affecting the stability of the scale. In contrast, the technical solution of this embodiment uses an elastic arm, whose movement trajectory is radial, making it less susceptible to the influence of the torsion spring's force and thus preventing undesirable changes in the scale. Furthermore, compared to the axial spring (hereinafter referred to as the gear ring spring) acting on the end face gear ring, the elastic arm in this embodiment is less affected by impacts or vibrations. For example, in impact tests, it is less likely to deform due to impact or vibration, causing the end face gear ring to rotate and change the scale value, thus resulting in more stable scale.

[0129] B) Setting the dosage is easier. When setting the dosage using the end-face toothed ring design, it is necessary to overcome the elastic force of the toothed ring spring (hereinafter referred to as the toothed ring spring), resulting in greater resistance and more effort required. However, in this embodiment, the elastic arm only requires overcoming the radial elastic force of the elastic arm, which can be easily overcome through circumferential rotation during dosage setting.

[0130] C) The injection operation is less strenuous. Similarly, with the end-face toothed ring design, during injection, it is necessary to overcome the spring force of the injection button and the toothed ring spring at the same time, making injection more strenuous. However, the elastic arm in this embodiment has less axial resistance, making injection less strenuous.

[0131] In other embodiments of this application, reference is made to Figure 14 The meshing edges of the teeth of the first internal tooth ring 113 and the first external tooth 631 are asymmetrical on both sides, so that the rotational resistance of the dose indicator ring support frame 60 in the first direction is less than the rotational resistance in the second direction; the first direction is the rotational direction of the dose setting knob to increase the dose, and the second direction is the rotational direction of the dose setting knob to decrease the dose.

[0132] Specifically, the tooth profiles of the first internal gear ring 113 and the first external convex tooth 631 can be non-isosceles triangles. This simplifies the structure. Alternatively, other shapes, such as non-isosceles trapezoids, can also be used.

[0133] Understandably, in this embodiment, viewed from the proximal end, the resistance to clockwise rotation of the dose indicator ring support 60 is less than the resistance to counterclockwise rotation (the outer casing 10 remains stationary). Therefore, in this embodiment, the first direction is the clockwise direction viewed from the proximal end, and the second direction is the counterclockwise direction viewed from the proximal end. It is understood that the opposite is also possible; other components can be designed accordingly.

[0134] Furthermore, the meshing edges of the teeth of the first internal gear ring 113 and the first external convex tooth 631 are asymmetrically arranged on both sides. This not only results in different rotational resistances for forward and reverse rotation, but also different sounds for forward and reverse rotation. This prompts the user to indicate whether the current operation is forward or reverse, reducing operational errors.

[0135] Specifically, the inclination angle of one of the meshing sides of the first internal gear ring 113 and the first external convex tooth 631 is 10°-45°, and the inclination angle of the other meshing side is 60°-90°.

[0136] In some other embodiments of this application, the elastic arm is provided with a reversing protrusion 633, which is located on one side of the circumferential rotation trajectory of the gripper; when the screw sleeve rotates in the second direction, the gripper can squeeze the reversing protrusion 633 circumferentially, forcing the elastic arm to contract inward, reducing the meshing depth between the first external tooth and the first internal tooth ring, so as to reduce the resistance to reversal.

[0137] For example, refer to Figure 10 The screw sleeve rotates in a clockwise direction. Figure 10 (This is from a distance, such as from a near distance, in a counter-clockwise direction). When the screw sleeve's jaws rotate clockwise, they will circumferentially press the reversing protrusion 633, forcing the elastic arm to retract inward.

[0138] In other embodiments of this application, reference is made to Figure 13 and Figure 17 The inner wall of the outer casing 10 is provided with a hook groove 123 for accommodating the hook 821 of the torsion spring 82; the radial width of the hook groove 123 is greater than the radial width of the hook 821.

[0139] This increases the installation space for the torsion spring 82 to be installed in the hook slot 123, reducing the difficulty of installing the torsion spring 82. Furthermore, it increases the space for the torsion spring 82 to deform under stress, reducing the possibility of the torsion spring 82 exploding under stress and causing the automatic injection pen to malfunction.

[0140] Specifically, the radial width of the hook groove 123 is 1.4mm-1.8mm greater than the radial width of the hook 821.

[0141] In other embodiments of this application, reference continues to be made to... Figure 13 The circumferential length of the hook groove 123 abutting the inner wall of the hook 821 is shorter than the circumferential length of the hook 821, so that the hook 821 does not contact the outer shell 10 at the opening of the hook groove 123.

[0142] In this way, the movement of the base of the torsion spring 82 hook 821 is unrestricted, increasing the deformation space of the torsion spring 82 and reducing the possibility of the torsion spring 82 exploding under stress, which could cause the automatic injection pen to malfunction. It also reduces the damage caused by the torsion spring 82 deforming under stress and squeezing the outer casing 10.

[0143] In other embodiments of this application, reference is made to Figure 6 The automatic injection pen also includes:

[0144] A dose-limiting lock 24 is installed on the inner wall of the screw sleeve 70 and sleeved on the screw 20. When setting the dose, the rotation of the screw sleeve 70 drives the dose-limiting lock 24 to move spirally towards the proximal end until the top of the dose-limiting lock 24 abuts against the screw 20 and can no longer move spirally upward. During injection, the dose-limiting lock 24 remains axially stationary relative to the screw 20. When setting the dose, the stroke of the dose-limiting lock 24 that can move spirally on the screw 20 corresponds to the amount of injection solution remaining in the injection container 90.

[0145] It should be noted that a radially protruding second stop 25 is provided at the proximal end of the screw 20. In the initial state before use, the distance between the proximal end of the dose limiting lock 24 and the distal end of the second stop 25 is a set first axial distance, which is adapted to the capacity of the injection container 90 that cooperates with the automatic injection pen, and also determines the maximum injection dose of the automatic injection pen.

[0146] Specifically, in this embodiment, to improve injection accuracy and facilitate portability, the dosage for a single injection is set to be less than the capacity of the injection container 90. Furthermore, the automatic injection pen can administer multiple injections with a single injection container 90 installed, eliminating the need to install a new container 90 for each injection, thus providing greater convenience for the user. An example is provided below.

[0147] For example, a commonly used injection container 90 contains 3 ml, while the single injection volume of the automatic injection pen in this embodiment is 0.75 ml, meaning it requires 4 injections to completely fill the injection container 90. When the initial dose of 0.75 ml is set, the dose limiting lock 24 moves proximally in a spiral motion following the rotation of the screw sleeve 70, stopping after moving 1 / 4 of its maximum stroke. This means the distance between the dose limiting lock 24 and the screw 20 is 3 / 4 of the first axial distance. During the first injection, since the screw 20 also moves in the same direction as the dose limiting lock 24, their axial distance remains constant. When the next dose of 75 ml is set, the distance between the dose limiting lock 24 and the screw 20 is 2 / 4 of the first axial distance. Finally, when the first dose of 75 ml is set, the distance between the dose limiting lock 24 and the screw 20 is zero, completing the maximum injection dose, and the injection container 90 is disassembled and discarded.

[0148] It is understandable that the dosage set each time can be less than 0.75 ml, so the number of injections is more than 4.

[0149] The dose limit lock 24 prevents the set dose from exceeding the remaining amount of injection solution in the injection container 90.

[0150] Specifically, refer to Figure 20 The inner wall of the screw sleeve 70 is provided with a rotary linkage positioning groove 74, and the outer wall of the dose limiting lock 24 is provided with a rotary linkage positioning protrusion 241 that cooperates with the rotary linkage positioning groove 74. Through the rotary linkage positioning groove 74 and the rotary linkage positioning protrusion 241, the screw sleeve 70 and the dose limiting lock 24 establish a rotary linkage relationship. It is understood that other structures capable of establishing rotary linkage can also be used.

[0151] Specifically, the rotary linkage positioning groove 74 and the fifth internal gear ring 73 are axially offset to avoid mutual interference.

[0152] As previously described, when setting the dosage, the dosage indicator ring 50 moves spirally to the distal end to limit the dosage of a single injection. A first stop is provided at the distal end of the housing 10 to axially block the spiral movement of the dosage indicator ring 50, so that the maximum scale setting does not exceed the design value.

[0153] In other embodiments of this application, reference is made to Figure 20 and Figure 21 The injection button 81 and the screw sleeve 70 are provided with an axially connected barb 811 connection structure to make the axial connection more stable. (Reference) Figure 20 and Figure 21The barb 811 connection structure includes a barb 811 and a stepped hole 75. The stepped hole 75 includes a first through hole and a second through hole with a diameter larger than the first through hole. The barb 811 passes through the first through hole and enters the second through hole, and completes the connection by hooking the shoulder between the two through holes.

[0154] In other embodiments of this application, reference is made to Figure 4 The outer casing 10 includes a tube 11 and a screw support 13, the screw support 13 being fixed to the inner wall of the distal end of the tube 11; the screw support 13 is provided with the first internal thread 131.

[0155] Instead of directly machining the screw support 13 into the outer casing 10, the outer casing 10 is divided into a tube body 11 and a screw support 13, with the first internal thread 131 provided on the screw support 13. This makes machining and assembly easier. It is understandable that the screw support 13 can also be integrally formed with the tube body 11.

[0156] In other embodiments of this application, reference is made to Figure 19 The inner wall of the distal end of the tube body 11 is provided with a first positioning groove 111 and a second positioning groove 112 arranged in axial sequence, both extending axially; the outer wall of the screw support 13 is provided with a first positioning protrusion that cooperates with the first positioning groove 111 to limit the circumferential position of the screw support 13; the second positioning groove 112 is used to limit the circumferential position of the injection container 90.

[0157] This design better restricts the circumferential position of the screw support 13, and has a simple structure and low processing cost.

[0158] Similarly, it can better restrict the circumferential position of the injection container 90, and has a simple structure and low processing cost.

[0159] Specifically, the second positioning groove 112 and the first positioning groove 111 are aligned circumferentially. This makes it easier to process the tube body 11.

[0160] In other embodiments of this application, reference is made to Figure 9 and Figure 13 The automatic injection pen also includes:

[0161] The first sound-generating device includes a first sound-generating structure and a second sound-generating structure that cooperate with each other; the first sound-generating structure is disposed at the proximal end of the dose indicator ring 50 and includes a third positioning groove 53 and an inclined surface 54 extending to the third positioning groove 53; the second sound-generating structure is disposed at the proximal end of the housing 10 and includes a third positioning protrusion 122 that matches the third positioning groove 53; during injection, the dose indicator ring 50 rotates spirally until the third positioning protrusion 122 passes the inclined surface 54 and enters the third positioning groove 53.

[0162] Understandably, in the final stage of the injection, the dosage indicator ring 50 rotates spirally, and the inclined surface 54 abuts against the third positioning protrusion 122, forcing the third positioning protrusion 122 to deform during the spiral rotation. As the dosage indicator ring 50 continues to rotate, the third positioning protrusion 122 falls into the third positioning groove 53, and the compressed and deformed part of the third positioning protrusion 122 is released, emitting a sound different from the injection, indicating to the user that the injection is complete.

[0163] Specifically, the deformation of the third positioning protrusion 122 under pressure can be 0.3-1.2mm.

[0164] Understandably, the cooperation between the third positioning groove 53 and the third positioning protrusion 122, in addition to producing sound, can also play a certain role in limiting the circumferential position of the dose indicator ring 50.

[0165] In other embodiments of this application, reference is made to Figure 13 The outer casing 10 also includes a fixed end cap 12, which is fixed to the inner wall of the proximal end of the tube body 11; the second sound-emitting structure is provided at the distal end of the fixed end cap 12.

[0166] That is, instead of directly machining the second sound-generating structure on the outer shell 10, the outer shell 10 is divided into a tube body 11 and a fixed end cap 12, wherein the second sound-generating structure is set on the fixed end cap 12.

[0167] This makes processing and assembly easier. It is understandable that the fixed end cap 12 can also be integrally formed with the tube body 11.

[0168] Furthermore, the third positioning protrusion 122, the fourth positioning protrusion 124 and the hook groove 123 can also be provided on the fixed end cap 12, which makes it easier to process and assemble.

[0169] In other embodiments of this application, the tube body 11 and the fixed end cap 12 are provided with a snap-fit ​​connection structure to make the axial connection more stable. (See reference) Figure 13 and Figure 19 The snap-fit ​​connection structure includes a snap protrusion 125 and a snap groove 14. The snap protrusion 125 snaps into the snap groove 14 to complete the connection.

[0170] In other embodiments of this application, reference is made to Figure 5 and Figure 22 The dose indicator ring 50 includes scale markings, including an exhaust mark 56; the exhaust mark 56 is between the zero mark and the maximum mark.

[0171] This allows the gas in the injection container to be purged before injection, making it safer to use.

[0172] Specifically, by setting the dosage, rotate the dosage scale to the vent mark 56, and then administer the injection. After the injection is complete, set the dosage again, rotate the dosage scale to the vent mark 56, and administer another injection. Repeat this process several times to complete the venting. Afterward, you can begin normal dosage setting and injection.

[0173] Specifically, the vent mark 56 is located between the zero mark and the "02" mark, so that the gas can be completely vented without affecting the injection.

[0174] In other embodiments of this application, reference is made to Figure 15 and Figure 16 The dose indicator ring 50 has a circumferential fourth positioning groove 55 at its proximal end, and the outer shell 10 is provided with a fourth positioning protrusion 124 that is inserted into the fourth positioning groove 55 to limit the axial position of the dose indicator ring 50 at the zero mark.

[0175] Understandably, after the fourth positioning protrusion 124 enters the fourth positioning groove 55 and circumferentially abuts against it, the dose indicator ring 50 is located at zero scale, or in other words, the viewing window 15 of the housing 10 displays zero scale. Through the fourth positioning groove 55 and the fourth positioning protrusion 124, the dose indicator ring 50 can be reliably maintained at the zero scale position.

[0176] It should be noted that, since the dose indicator ring 50 and the outer shell 10 are connected by the second external thread 51 and the second internal thread 114, and the second internal thread 114 has relatively few threads, the limiting function of the fourth positioning groove 55 and the fourth positioning protrusion 124 can also prevent the second external thread 51 and the second internal thread 114 from disengaging from the threaded connection.

[0177] It should be noted that the fourth positioning protrusion 124 enters the fourth positioning groove 55 and circumferentially abuts after the first sound-emitting device emits sound, to prevent the first sound-emitting device from failing to emit sound. Furthermore, the fourth positioning protrusion 124 enters the fourth positioning groove 55 and circumferentially abuts immediately after the first sound-emitting device emits sound. That is, the two timing points are very close together, which improves the injection accuracy of the automatic injection pen.

[0178] It should be understood that the above embodiments are exemplary and are not intended to encompass all possible implementations included in the claims. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of this application that may not be explicitly described. Therefore, the above embodiments merely illustrate several implementations of this application and do not limit the scope of protection of this patent application.

Claims

1. An automatic injection pen, characterized in that, include: shell; The screw is used to move the piston inside the injection container to perform injection; Dosage setting knob, used to set the dosage by turning it; A dose indicator ring is used to indicate the dose to be injected. The screw sleeve rotates in sync with the rotation of the dosage setting knob when the dosage is set. A dose indicator ring support frame, when setting the dose, rotates in conjunction with the dose indicator ring and the screw sleeve to transmit the torque of the screw sleeve to the dose indicator ring; an elastic arm is circumferentially provided at the distal end of the dose indicator ring support frame, and at least one first external protruding tooth is provided on the elastic arm; a first internal toothed ring that meshes with the first external protruding tooth is provided on the inner wall of the distal end of the outer shell; the outer wall of the screw sleeve is provided with a clamping claw that extends through the dose indicator ring support frame and can clamp the elastic arm; A torsion spring, which rotates along with the rotation of the dose indicator ring support frame during dose setting to accumulate torque potential energy; The injection button axially abuts against the screw sleeve. When the injection button is subjected to an axial force towards the distal end, it drives the screw sleeve to move axially towards the distal end. The gripper radially squeezes the elastic arm to retract inward, causing the first external tooth to disengage from the first internal tooth ring. This releases the torque of the torsion spring, pushes the dose indicator ring support frame to rotate, and drives the screw sleeve to rotate, thereby driving the screw to perform a spiral descent motion for injection.

2. The automatic injection pen according to claim 1, characterized in that, The meshing edges of the teeth of the first internal tooth ring and the first external tooth are asymmetrical on both sides, so that the rotational resistance of the dose indicator ring support frame in the first direction is less than the rotational resistance in the second direction; the first direction is the rotation direction of the dose setting knob to increase the dose, and the second direction is the rotation direction of the dose setting knob to decrease the dose.

3. The automatic injection pen according to claim 1, characterized in that, The elastic arm is provided with a reversing protrusion, which is located on one side of the circumferential rotation trajectory of the gripper. When the screw sleeve rotates in the second direction, the gripper can squeeze the reversing protrusion circumferentially, forcing the elastic arm to contract inward, reducing the meshing depth between the first external tooth and the first internal tooth ring, thereby reducing the resistance to reversal.

4. The automatic injection pen according to claim 1, characterized in that, The inner wall of the outer casing is provided with a hook groove for accommodating the hook of the torsion spring; the radial width of the hook groove is greater than the radial width of the hook.

5. The automatic injection pen according to claim 4, characterized in that, The circumferential length of the hook groove abutting the inner wall of the hook is shorter than the circumferential length of the hook, so that the hook does not contact the outer shell at the opening of the hook groove.

6. The automatic injection pen according to claim 1, characterized in that, The automatic injection pen also includes: A dose-limiting lock is installed on the inner wall of the screw sleeve and fitted onto the screw. When setting the dose, the rotation of the screw sleeve drives the dose-limiting lock to move helically towards the proximal end until the top of the dose-limiting lock abuts against the screw and can no longer move helically upwards. During injection, the dose-limiting lock remains axially stationary relative to the screw. When setting the dose, the stroke of the dose-limiting lock's helical movement on the screw corresponds to the amount of injection solution remaining in the injection container.

7. The automatic injection pen according to claim 6, characterized in that, The outer shell includes a tube, and the inner wall of the distal end of the tube is provided with a first positioning groove and a second positioning groove arranged in axial sequence, both extending axially; the outer wall of the screw support is provided with a first positioning protrusion that cooperates with the first positioning groove to limit the circumferential position of the screw support; the second positioning groove is used to limit the circumferential position of the injection container.

8. The automatic injection pen according to claim 1, characterized in that, The automatic injection pen also includes: The first sound-generating device includes a first sound-generating structure and a second sound-generating structure that cooperate with each other; the first sound-generating structure is disposed at the proximal end of the dose indicator ring and includes a third positioning groove and an inclined surface extending to the third positioning groove; the second sound-generating structure is disposed at the proximal end of the housing and includes a third positioning protrusion that matches the third positioning groove; during injection, the dose indicator ring rotates spirally until the third positioning protrusion passes the inclined surface and enters the third positioning groove.

9. The automatic injection pen according to claim 1, characterized in that, The dose indicator ring includes scale markings, which include venting marks; the venting marks are located between the zero mark and the maximum mark.

10. The automatic injection pen according to claim 1, characterized in that, The dose indicator ring has a circumferential fourth positioning groove at its proximal end, and the outer shell is provided with a fourth positioning protrusion that is inserted into the fourth positioning groove to limit the axial position of the dose indicator ring at the zero mark.

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