Residue monitoring and locking structure and injection device

Abstract

The invention relates to the technical field of pen type injection devices, in particular to an allowance monitoring and locking structure and an injection device. Comprising a shell, a push rod, a clutch, a driving rod, a limiting ring, a termination ring and a dose setting ring, the limiting ring is fixedly connected into the shell, the clutch is sleeved with the limiting ring, the termination ring is arranged at the end, away from the limiting ring, of the clutch, the driving rod is arranged in the shell, one end of the driving rod extends out of the shell, and the push rod is arranged in the driving rod; the push rod extending out of the driving rod sequentially penetrates through the terminating ring, the clutch and the limiting ring; the dose setting ring sleeves the end part of the shell, and the dose setting ring is meshed with the driving rod; the termination ring reciprocates in the axial direction of the push rod and is used for monitoring the residual amount of the injection liquid medicine; the termination ring is provided with a push rod termination surface, the push rod is provided with an injection termination surface, and when the push rod termination surface is in contact with the injection termination surface, injection locking is performed; the locking function after injection is achieved, and the allowance monitoring function is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of pen-type injection devices, and in particular to a residual amount monitoring and locking structure and an injection device. Background Art

[0002] Currently, there are single-disposable mechanical injection devices on the market, primarily used for administering single (small) doses of medications at regular intervals (e.g., weekly). There are also multi-disposable mechanical injection devices, primarily used for administering multiple doses of medications at frequent intervals (e.g., daily). Compared to single-disposable devices, multi-disposable mechanical injection devices offer lower costs, flexible dosage adjustments, and can be discarded after a cycle or a set number of injections. Therefore, multi-disposable mechanical injection devices are more suitable for specific needs.

[0003] The currently available multiple-shot mechanical injection device products cannot determine whether there are any remaining injection times after multiple injections or cannot accurately determine the specific remaining number of injections. They cannot achieve post-injection locking, nor can they achieve remaining amount monitoring during use.

[0004] Therefore, there is an urgent need to provide a residual amount monitoring and locking structure and an injection device, which can realize the post-injection locking function and the residual amount monitoring function compared with the existing technology. Summary of the Invention

[0005] The present invention solves the technical problems existing in the prior art and provides a residual quantity monitoring and locking structure and an injection device.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A residual quantity monitoring and locking structure comprises a housing, a push rod, a clutch, a drive rod, a limiting ring, a stop ring, and the dose setting ring. The limiting ring is fixedly connected to the interior of the housing, the clutch is sleeved inside the limiting ring, and the stop ring is provided at the end of the clutch away from the limiting ring. The drive rod is provided inside the housing, one end of the drive rod extends out of the housing. The push rod is provided inside the drive rod, one end of the push rod extends out of the drive rod, and the push rod extending out of the drive rod passes through the stop ring, the clutch, and the limiting ring in sequence. The dose setting ring is sleeved on the end of the housing and meshes with the drive rod. The inner wall of the termination ring is engaged with the push rod, and the outer wall is engaged with the drive rod; during the process of metering setting and injection, the termination ring reciprocates along the axial direction of the push rod to realize the remaining amount of the injection liquid; A push rod terminating surface is provided on the terminating ring, and an injection terminating surface is provided on the push rod. When the push rod terminating surface contacts the injection terminating surface, injection locking is performed.

[0007] Furthermore, the outer wall of the termination ring is provided with a third engaging rib, the inner wall of the driving rod is provided with a second engaging rib, and the third engaging rib and the second engaging rib are engaged with each other.

[0008] Furthermore, the inner wall of the termination ring is provided with a spiral groove, and the outer wall of the push rod is provided with threaded teeth, and the threaded teeth are engaged in the spiral groove; the drive rod rotates forward for metering setting, and the termination ring moves from an initial position along the axial direction of the push rod.

[0009] Furthermore, the outer wall of the clutch is provided with a plurality of first engaging ribs, and during the injection process, the second engaging ribs are engaged with the first engaging ribs, and the termination ring moves toward the initial position along the axial direction of the push rod.

[0010] Furthermore, the outer wall of the clutch is provided with a plurality of ratchet gears, and the inner wall of the limiting ring is provided with a plurality of second meshing teeth. The ratchet gears are engaged with the second meshing teeth, and the ratchet gears only move in one direction relative to the second meshing teeth; the extension direction of the plurality of ratchet gears is arranged opposite to the rotation direction of the clutch; the ratchet gears are elastic, and the ratchet gears are interference fit with the second meshing teeth.

[0011] Furthermore, the outer wall of the push rod is provided with thread teeth, the inner wall of the limiting ring is provided with meshing threads, and the thread teeth are meshed with the meshing threads.

[0012] Furthermore, a guide groove is provided on the outer wall of the push rod, and a push rod engaging rib is provided on the inner wall of the clutch, and the push rod engaging rib extends into the guide groove.

[0013] Furthermore, a torsion spring is sleeved on the outer wall of the driving rod, one end of the torsion spring is clamped and fixed to the outer wall of the driving rod, and the other end is clamped and fixed to the inner wall of the shell.

[0014] Furthermore, the end of the driving rod extending out of the housing is connected to an injection button.

[0015] An injection device comprises a pen cap and a residual amount monitoring and locking structure. The pen cap is connected to the end of the shell away from the injection button.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) In the process of metering setting, the end ring moves from the initial position to the direction close to the injection button. When the required injection amount is reached, the end ring stops at a certain position of the push rod. During injection, the end ring returns to the initial position again and performs such reciprocating motion. Due to the unidirectional motion of the push rod and the repeated motion of the end ring, the accuracy of monitoring the remaining amount of the liquid medicine can be guaranteed.

[0017] (2) In the present invention, the terminating ring is provided with a push rod terminating surface, and the end of the push rod is provided with an injection terminating surface. When the push rod terminating surface contacts the injection terminating surface, the terminating ring locks the push rod, thereby realizing the injection locking function.

[0018] (3) During the entire injection process, the present invention allows the push rod to move only in the direction of injection through the limited relationship between the ratchet gear and the second meshing teeth, and the limited relationship between the thread teeth and the meshing screw teeth. The push rod will not move in the opposite direction, which ensures the injection accuracy while being more convenient to use and having higher stability.

[0019] (4) In the present invention, during the injection process, the interference fit between the ratchet gear and the second meshing tooth and the clutch will produce a "clicking" sound during rotation, which serves as a reminder to the user and is more convenient for the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional view of the overall structure of Example 1 of the present invention.

[0021] Figure 2 Schematic diagram of the structure of the driving rod in Example 1 of the present invention.

[0022] Figure 3 Schematic diagram of the structure of the clutch in embodiment 1 of the present invention.

[0023] Figure 4 It is a schematic structural diagram of the limiting ring in Example 1 of the present invention.

[0024] Figure 5 It is a schematic diagram of the coordination of the limiting ring, the push rod and the clutch in Example 1 of the present invention.

[0025] Figure 6 It is a schematic structural diagram of the termination ring in Example 1 of the present invention.

[0026] Figure 7 It is a structural diagram of embodiment 2 of the present invention.

[0027] Description of reference numerals: 1. Pen cap; 2. Shell; 3. Injection button; 4. Push rod; 41. Termination meshing tooth; 42. Threaded tooth; 43. Guide groove; 5. Clutch; 51. Ratchet teeth; 52. First meshing teeth; 53. First meshing rib; 54. First connecting tube; 55. Second connecting tube; 56. Push rod meshing rib; 6. Driving rod; 61. First connecting portion; 62. Second connecting portion; 63. Second engaging rib; 64. Torsion spring limiting groove; 7. Limiting ring; 71. Second meshing tooth; 72. Meshing screw thread; 73. Inner ring; 74. Outer ring; 8. Torsion spring; 9. Dose setting ring; 10. Torsion spring fixing ring; 11. Termination ring; 111. Third meshing rib; 112. Spiral groove; 113. Push rod termination surface. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", etc. is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0029] Example 1 like Figure 1 As shown, this embodiment provides a residual amount monitoring and locking structure, including a housing 2, an injection button 3, a push rod 4, a clutch 5, a drive rod 6, a limit ring 7, a torsion spring 8, a dose setting ring 9, a stop ring 11 and a torsion spring fixing ring 10.

[0030] The inner wall of the housing 2 is fixedly connected to a limit ring 7, a clutch 5 is sleeved inside the limit ring 7, a drive rod 6 is arranged inside the housing 2, one end of the drive rod 6 extends out of the housing 2, and the end of the drive rod 6 extending out of the housing 2 is connected to the injection button 3, and the drive rod 6 and the injection button 3 are engaged to achieve synchronous movement. A dose setting ring 9 is sleeved on one end of the housing 2 near the injection button 3, and the dose setting ring 9 is engaged with the drive rod 6. A torsion spring fixing ring 10 is also provided inside the housing 2, and the torsion spring fixing ring 10 is fixed to the housing 2 Internally, a torsion spring fixing ring 10 and a limiting ring 7 are respectively arranged on both sides of the interior of the outer shell 2; a torsion spring 8 is sleeved on the outside of the driving rod 6, one end of the torsion spring 8 is clamped and fixed to the outer wall of the driving rod 6, and the other end of the torsion spring 8 is clamped and fixed to the torsion spring fixing ring 10; the push rod 4 is passed through the limiting ring 7 and the clutch 5, and the push rod 4 passes through the end of the clutch 5 and extends into the driving rod 6; a termination ring 11 is also sleeved on the outside of the push rod 4, and the inner wall of the termination ring 11 is engaged with the push rod 4, and the outer wall is engaged with the inner wall of the driving rod 6.

[0031] During metering setting, the dose setting ring 9 engages with the drive rod 6, and the dose setting ring 9 rotates forward, the drive rod 6 rotates synchronously, and the lower end of the torsion spring 8 rotates along with the drive rod 6, while the upper end of the torsion spring 8 is fixed in the housing 2 and does not rotate. Thus, during the metering setting process, the torsion spring 8 accumulates force; during the rotation of the drive rod 6, the stop ring 11 rotates circumferentially and moves axially accordingly, and the axial movement of the stop ring 11 is in a direction close to the injection button 3.

[0032] When injecting the liquid medicine, the injection button 3 is pressed, the driving rod 6 is separated from the dose setting ring 9, and the driving rod 6 is engaged with the clutch 5. Under the action of the torsion spring 8, the driving rod 6 rotates in the opposite direction, driving the clutch 5 to rotate, thereby driving the push rod 4 to rotate. At this time, the push rod 4 performs the injection movement, and the end ring 11 moves in the opposite direction to the metering setting. After each single injection, the end ring 11 is in the Figure 1 the next time the metering setting is performed, the termination ring 11 moves in the direction close to the injection button 3, thereby achieving repeated movement.

[0033] like Figure 1 and Figure 2 As shown, the push rod includes a first connecting part 61 and a second connecting part 62, the first connecting part 61 is integrally connected to the second connecting part 62, the outer diameter of the second connecting part 62 is larger than the outer diameter of the first connecting part 61, and a plurality of second meshing ribs 63 are provided in the second connecting part 62, each second meshing rib 63 is arranged along the axial extension of the second connecting part 62, and the plurality of second meshing ribs 63 are arranged at intervals along the circumference of the second connecting part 62, and each second meshing rib 63 is provided with a guide section at both ends.

[0034] The outer wall of the second connecting portion 62 is further provided with a limiting groove 64 for the torsion spring 8 , and the lower end of the torsion spring 8 is clamped inside the limiting groove 64 for the torsion spring 8 .

[0035] like Figure 3 As shown, the clutch 5 includes a first connecting cylinder 54 and a second connecting cylinder 55. The first connecting cylinder 54 is integrally connected to the second connecting cylinder 55. The outer diameter of the first connecting cylinder 54 is larger than the outer diameter of the second connecting cylinder 55. The inner diameter of the first connecting cylinder 54 is the same as the inner diameter of the second connecting cylinder 55. The outer wall of the first connecting cylinder 54 is provided with at least one ratchet tooth 51. The ratchet gear is elastic, and the extension direction of the two ratchet gears is opposite to the rotation direction of the clutch 5.

[0036] The inner wall of the second connecting tube 55 is provided with a plurality of first meshing teeth 52, preferably two of which are spaced apart along the circumference of the second connecting tube 55. The inner wall of the second connecting tube 55 is also provided with a plurality of push rod meshing ribs 56, preferably two of which are spaced apart along the circumference of the second connecting tube 55. Each push rod meshing rib 56 is disposed adjacent to a first meshing tooth 52, and the two push rod meshing ribs 56 are spaced apart along the circumference of the second connecting tube 55.

[0037] The outer wall of the second connecting tube 55 is provided with a plurality of first meshing ribs 53, each of which is extended along the axial direction of the second connecting tube 55, and the plurality of first meshing ribs 53 are arranged at intervals along the circumference of the second connecting tube 55; when the driving rod 6 and the clutch 5 rotate synchronously, the second meshing rib 63 extends into the first meshing rib 53, and the second meshing rib 63 is meshed with the first meshing rib 53, so that the driving rod 6 rotates while driving the clutch 5 to rotate synchronously.

[0038] like Figure 4 As shown, the limiting ring 7 is arranged at one end of the inner wall of the housing 2 away from the injection button 3. The limiting ring 7 includes an outer ring 74 and an inner ring 73. The inner ring 73 is integrally connected to the inner part of the outer ring 74. The inner ring 73 and the outer ring 74 are coaxially arranged. The inner ring 73 extends into the first connecting tube 54 and is fixedly connected to the inner wall of the housing 2.

[0039] The inner wall of the outer ring 74 is provided with multiple second meshing teeth 71, the side surface of each second meshing tooth 71 is inclined, and the inclination direction of the side surface of each second meshing tooth 71 is consistent, each second meshing tooth 71 extends along the axis of the outer ring 74, and multiple second meshing teeth 71 are arranged at intervals along the circumference of the outer ring 74.

[0040] The second meshing teeth 71 are meshed with the ratchet teeth 51, and the ratchet teeth 51 and the second meshing teeth 71 are interference fit. During the rotation of the clutch 5, due to the meshing of the ratchet teeth 51 and the second meshing teeth 71, the clutch 5 can only rotate in one direction. In this embodiment, the clutch 5 can only rotate counterclockwise. At the same time, due to the interference fit between the ratchet gear and the second meshing teeth 71, during the rotation of the clutch 5, the ratchet gear will make a "click" sound every time it moves from one second meshing tooth 71 to the adjacent second meshing tooth 71, to remind the user that an injection is in progress. This is a very friendly design in injection interaction.

[0041] The inner wall of the inner ring 73 is provided with meshing screw threads 72 .

[0042] like Figure 5 As shown, the outer wall of the push rod 4 is provided with threaded teeth 42, and the threaded teeth 42 provided on the outer wall of the push rod 4 are engaged with the meshing thread teeth 72; the end of the push rod 4 close to the injection button 3 is integrally connected to a plurality of terminal meshing teeth 41, preferably two of which are arranged at intervals along the circumference of the push rod 4, and each terminal meshing tooth 41 is provided with an injection termination surface.

[0043] The outer wall of the push rod 4 is also provided with multiple guide grooves 43, preferably two guide grooves 43 are provided, and the two guide grooves 43 are arranged at intervals along the circumference of the push rod 4. The push rod engagement ribs 56 are arranged to extend into the guide grooves 43 accordingly. During the rotation of the clutch 5, the push rod 4 rotates synchronously with the clutch 5.

[0044] like Figure 6 As shown, the outer wall of the termination ring 11 is provided with a plurality of third meshing ribs 111, preferably two third meshing ribs 111 are provided, and the two third meshing ribs 111 are meshed with the second meshing rib 63, and the second meshing rib 63 is meshed with the third meshing rib 111, which guides the movement of the termination ring 11.

[0045] A spiral groove 112 is provided on the inner wall of the termination ring 11, which meshes with the threaded teeth 42 on the outer wall of the push rod 4. When the third meshing rib 111 provided on the outer wall of the termination ring 11 meshes with the second meshing rib 63 and the spiral groove 112 provided on the inner wall meshes with the threaded teeth 42, the termination ring 11 can rotate circumferentially and move axially during the rotation of the drive rod 6, thereby realizing that during the metering setting process, the drive rod 6 rotates and the termination ring 11 moves toward the direction close to the injection button 3.

[0046] The termination ring 11 is also provided with a push rod termination surface 113, which is set at one end of the termination ring 11 close to the injection button 3. When the push rod termination surface 113 contacts the injection termination surface of the push rod 4, the termination ring 11 locks the push rod 4, stops the injection, and performs injection locking.

[0047] In each cycle of metering setting-injection-next metering setting, the termination ring 11 first moves toward the injection button 3 with the movement of the dose setting ring 9, and then moves back to the initial position with the movement of the push rod 4 during injection. During the next metering setting, the distance moved by the termination ring 11 becomes shorter, that is, from its initial position to the position of the engagement tooth 41 after the first injection of the push rod 4. Therefore, assuming that each dose is set to 10 units, when the last dose of medicine is less than 10 units, the push rod 4 moves to a position closer to the termination ring 11. At this time, assuming that there are only 5 units of medicine, the rotational movement displacement of the termination ring 11 relative to the injection end surface is only 5 units. It can be understood that the termination ring 11 also has a last dose setting counting function, which can interact with the user about the last dose setting amount, and exceeding the setting of the medicine dose will not be allowed; thereby realizing the detection function of the remainder.

[0048] The working principle of the residual quantity monitoring and locking structure provided in this embodiment is as follows: When setting the dosage, the drive rod 6 engages with the dose setting ring 9 and rotates the dose setting ring 9 to perform the dosage setting. During the dosage setting process, the lower end of the torsion spring 8 rotates with the drive rod 6, while the upper end of the torsion spring 8 does not rotate, thereby storing force in the torsion spring 8.

[0049] During the metering setting process, the stop ring 11 moves a certain distance from the initial position toward the injection button 3 under the dual effects of the rotation of the driving rod 6 and the threaded engagement of the push rod 4 .

[0050] When an injection is required, the injection button 3 is pressed in the direction closer to the housing 2, which drives the drive rod 6 to move toward the interior of the housing 2. The drive rod 6 disengages from the dose setting ring 9, and the second meshing rib 63 inside the drive rod 6 extends into the first meshing rib 53 provided on the outer wall of the clutch 5, thereby achieving meshing of the drive rod 6 and the clutch 5. At this time, under the action of the restoring force of the torsion spring 8, the drive rod 6 rotates, causing the clutch 5 to rotate synchronously. Due to the cooperation between the ratchet teeth 51 of the clutch 5 and the second meshing teeth 71 of the limiting ring 7, the clutch 5 can only rotate counterclockwise relative to the limiting ring 7, that is, the push rod 4 can only move in the injection direction and cannot move in the opposite direction. The push rod 4 rotates synchronously with the clutch 5. At the same time, the meshing relationship between the threaded teeth 42 on the outside of the push rod 4 and the meshing screw teeth 72 provided inside the limiting ring 7 also restricts the movement direction of the push rod 4.

[0051] During the injection process, the termination ring 11 moves back to the initial position from the metering setting movement position. During each metering setting-injection process, it performs reciprocating motion until the push rod end surface 113 of the termination ring 11 contacts the injection end surface of the push rod 4. The termination ring 11 forms an antagonistic force on the push rod 4, preventing the movement of the push rod 4 and locking the push rod 4, thereby achieving injection locking.

[0052] The reciprocating motion of the termination ring 11 in the single metering setting - injection can monitor the remaining amount of medicine very well. Since the push rod 4 can only move in the direction of injection, that is, it can only move in one direction, the movement distance of the termination ring 11 is limited, ensuring that the distance of each movement of the termination ring 11 will not exceed the longest distance of the push rod 4, that is, the amount of medicine injected each time will not exceed the remaining injection amount; thereby, the remaining amount of the liquid medicine can be monitored very accurately.

[0053] In the present embodiment, during the metering setting process, the stop ring 11 moves from the initial position toward the injection button 3. When the required injection amount is reached, the stop ring 11 stops at a certain position of the push rod 4. During injection, the stop ring 11 returns to the initial position again, performing such a reciprocating motion. Due to the unidirectional motion of the push rod 4 and the repeated motion of the stop ring 11, the accuracy of the remaining liquid monitoring can be guaranteed.

[0054] In this embodiment, the termination ring 11 is provided with a push rod termination surface 113, and the end of the push rod 4 is provided with an injection termination surface. When the push rod termination surface 113 contacts the injection termination surface, the termination ring 11 locks the push rod 4 to achieve the injection locking function.

[0055] In the entire injection process, the push rod 4 can only move in the direction of injection through the limited relationship between the ratchet gear and the second meshing teeth 71, and the limited relationship between the threaded teeth 42 and the meshing threaded teeth 72. The push rod 4 will not move in the opposite direction, which ensures the injection accuracy while being more convenient to use and having higher stability.

[0056] In this embodiment, during the injection process, the interference fit between the ratchet gear and the second meshing teeth 71 will cause a "clicking" sound to be emitted during the rotation of the clutch 5, which serves as a reminder to the user and is more convenient for the user.

[0057] Example 2 like Figure 7 As shown, this embodiment provides an injection device, including the post-injection locking and remaining amount monitoring component and the pen cap 1 provided in Example 1. The pen cap 1 is connected to the housing 2 in the autonomous injection drive component, and the pen cap 1 is arranged at one end of the housing 2 away from the injection button 3.

[0058] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A residual quantity monitoring and locking structure, characterized in that: The device comprises a housing, a push rod, a clutch, a drive rod, a limiting ring, a stop ring, and a dose setting ring. The limiting ring is fixedly connected to the interior of the housing. The clutch is sleeved inside the limiting ring. The end of the clutch away from the limiting ring is provided with the stop ring. The drive rod is provided inside the housing, with one end of the drive rod extending out of the housing. The push rod is provided inside the drive rod, with one end of the push rod extending out of the drive rod. The push rod extending out of the drive rod passes through the stop ring, the clutch, and the limiting ring in sequence. The dose setting ring is sleeved on the end of the housing and is engaged with the drive rod. The inner wall of the termination ring is engaged with the push rod, and the outer wall is engaged with the drive rod; during the process of metering setting and injection, the termination ring reciprocates along the axial direction of the push rod to realize the remaining amount of the injection liquid; A push rod terminating surface is provided on the terminating ring, and an injection terminating surface is provided on the push rod. When the push rod terminating surface contacts the injection terminating surface, injection locking is performed.

2. The residual quantity monitoring and locking structure according to claim 1, characterized in that: The outer wall of the termination ring is provided with a third engaging rib, the inner wall of the driving rod is provided with a second engaging rib, and the third engaging rib and the second engaging rib are engaged with each other.

3. The residual quantity monitoring and locking structure according to claim 2, characterized in that: The inner wall of the termination ring is provided with a spiral groove, and the outer wall of the push rod is provided with threaded teeth, and the threaded teeth are engaged in the spiral groove; the drive rod rotates in the forward direction for metering setting, and the termination ring moves from an initial position along the axial direction of the push rod.

4. The residual quantity monitoring and locking structure according to claim 2, characterized in that: The outer wall of the clutch is provided with a plurality of first engaging ribs. During the injection process, the second engaging ribs are engaged with the first engaging ribs, and the termination ring moves toward the initial position along the axial direction of the push rod.

5. The residual quantity monitoring and locking structure according to claim 4, characterized in that: The outer wall of the clutch is provided with multiple ratchet gears, and the inner wall of the limiting ring is provided with multiple second meshing teeth. The ratchet gears are engaged with the second meshing teeth, and the ratchet gears only move in one direction relative to the second meshing teeth; the extension direction of the multiple ratchet gears is arranged opposite to the rotation direction of the clutch; the ratchet gears are elastic, and the ratchet gears are interference fit with the second meshing teeth.

6. The residual quantity monitoring and locking structure according to claim 1, characterized in that: The outer wall of the push rod is provided with thread teeth, the inner wall of the limiting ring is provided with meshing thread teeth, and the thread teeth are meshed with the meshing thread teeth.

7. The residual quantity monitoring and locking structure according to claim 6, characterized in that: The outer wall of the push rod is provided with a guide groove, and the inner wall of the clutch is provided with a push rod engaging rib, and the push rod engaging rib extends into the guide groove.

8. The residual quantity monitoring and locking structure according to claim 1, characterized in that: A torsion spring is sleeved on the outer wall of the driving rod. One end of the torsion spring is fixedly connected to the outer wall of the driving rod, and the other end is fixedly connected to the inner wall of the shell.

9. The residual quantity monitoring and locking structure according to claim 1, characterized in that: The end of the driving rod extending out of the housing is connected to the injection button.

10. An injection device, characterized in that: The invention comprises a pen cap and a residual amount monitoring and locking structure according to any one of claims 1 to 9, wherein the pen cap is connected to the end of the housing away from the injection button.

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