Torsion spring anti-collision device of injection pen

Abstract

The torsion spring anti-collision device of the injection pen comprises a shell, the front end of the shell is a near end, the rear end of the shell is a far end, one end of a torsion spring is connected to a dose dial support, and the other end of the torsion spring is connected to a spring fixing structure. The side wall, close to the torsion spring, of the torsion spring installation groove of the spring fixing structure is shortened till no blocking force exists when a torsion spring hook of the torsion spring is inserted into the torsion spring installation groove, meanwhile, the side wall, away from the torsion spring, of the torsion spring installation groove is gradually increased along the walking track of the torsion spring hook of the torsion spring, and the installation difficulty of the torsion spring is lowered; the structure is simple, the cost is reduced, the phenomenon that the torsion spring is deformed and exploded due to additional radial force generated in the force storage process when the torsion spring hook is radially extruded after the torsion spring is installed is avoided, meanwhile, the phenomenon that an injection button cannot rebound is avoided, the failure caused by deformation of the torsion spring is avoided, the injection precision is improved, the reliability of the structure is improved, and the failure rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of adjustable-dose injection devices, and more specifically, to a torsion spring anti-collision device for an injection pen. Background Art

[0002] The structure of an adjustable dose injection device includes a dose adjustment and injection mechanism and a cartridge bottle fixing mechanism. When adjusting the dose, the user rotates a dose adjustment member of the dose pouring mechanism, and the force applied by the user is stored in a torsion spring for later use. In order to pour out the dose adjusted in this way, the user presses a pouring button on the proximal end of the syringe, and the torsion force accumulated in the torsion spring can be delivered to the drive element to drive the liquid out of the injection device.

[0003] The existing Chinese invention patent with patent publication number CN118490935A discloses a torsion spring anti-collision device for an injection pen, comprising a shell, the front end of the shell is the proximal end, the rear end of the shell is the distal end, the distal end of the shell is provided with a fixed end cover, the fixed end cover is sleeved with a screw bracket 141, one end of the screw bracket 141 passes through the fixed end cover and is connected to a dose setting element, the outer periphery of the screw bracket 141 is sleeved with a dose display bracket, and the dose display bracket and the fixed end cover are meshed through ratchet teeth with an inclined surface at the end, so that the screw bracket 141 can only move forward and backward along the axial direction relative to the dose setting element and the dose display bracket, the dose setting element is connected to the distal end of the shell, so that the dose setting element can only rotate relative to the shell, and a torsion spring is provided between the screw bracket 141 and the dose display bracket, one end of the torsion spring is connected to the proximal end of the dose display bracket close to the shell, and the other end is connected to the fixed end cover.

[0004] However, the existing torsion spring 70 is difficult to install with the fixed end cover and cannot be screwed in directly. In addition, the torsion spring 70 will explode during the pre-tightening process, causing the injection button 80 to be unable to return to its original position. Therefore, how to solve the above problem has become a problem that needs to be solved at present. Summary of the invention

[0005] In view of this, the present invention proposes a torsion spring anti-collision device for an injection pen, comprising a shell 10, wherein the front end of the shell 10 is the proximal end, and the rear end of the shell 10 is the distal end, one end of the torsion spring 70 is connected to the dosage dial bracket 60, and the other end is connected to the spring fixing structure 20, and the side wall of the torsion spring installation groove 23 of the spring fixing structure 20 close to the torsion spring 70 is shortened until there is no blocking force when the torsion spring hook 71 of the torsion spring 70 is inserted into the torsion spring installation groove 23, and at the same time, the side wall of the torsion spring installation groove 23 away from the torsion spring 70 is gradually enlarged along the walking trajectory of the torsion spring hook 71 of the torsion spring 70, thereby reducing the installation difficulty of the torsion spring 70 and reducing the cost, and avoiding that when the torsion spring 70 is installed with the torsion spring hook 71 and subjected to radial compression, the accumulation process of force will generate additional radial force, causing the torsion spring 70 to deform and thus explode, and at the same time avoiding the phenomenon that the injection button 80 cannot rebound, and avoiding failure caused by deformation of the torsion spring 70, thereby improving injection accuracy, improving structural reliability, and reducing failure rate.

[0006] A torsion spring anti-collision device for an injection pen comprises a shell 10, wherein the front end of the shell 10 is a proximal end, the rear end of the shell 10 is a distal end, the distal end of the shell 10 is provided with a spring fixing structure 20, a screw sleeve 30 is sleeved in the shell 10, the screw sleeve 30 passes through an adjustment knob 50 and is sleeved with an injection button 80, a torsion spring 70 and a dosage dial bracket 60 are sleeved on the outer periphery of the screw sleeve 30, one end of the torsion spring 70 is connected to the dosage dial bracket 60, and the other end is connected to the spring fixing structure 20, the spring fixing structure 20 is provided with a torsion spring mounting groove 23, one end of the torsion spring 70 is provided with a torsion spring hook 71, the torsion spring mounting groove 23 of the spring fixing structure 20 is shortened to a side wall close to the torsion spring 70 until the torsion spring hook 71 of the torsion spring 70 is inserted into the torsion spring mounting groove 23 without any blocking force, and the torsion spring mounting groove 23 is moved away from the torsion spring. The side wall of the torsion spring 70 gradually increases along the walking trajectory of the torsion spring hook 71 of the torsion spring 70. Since the size and shape of the torsion spring mounting groove 23 are basically consistent with the shape of the torsion spring 70 when it is mounted on the injection pen, especially when the torsion spring hook 71 of the torsion spring 70 is installed on the spring fixing structure 20, the direction in which the torsion spring hook 71 enters the torsion spring mounting groove 23 is completely consistent, so that the torsion spring 70 will not be deformed due to the force on the torsion spring hook 71, thereby reducing the installation difficulty and cost of the torsion spring 70, and avoiding the torsion spring 70 being subjected to radial compression when the torsion spring hook 71 is installed, and the accumulation process of force will generate additional radial force, causing the torsion spring 70 to deform and explode, thereby avoiding the phenomenon that the injection button 80 cannot rebound, and avoiding failure caused by deformation of the torsion spring 70, thereby improving injection accuracy, improving structural reliability, and reducing failure rate.

[0007] Furthermore, the torsion spring installation groove 23 gradually increases in size from the time when the torsion spring hook 71 is inserted.

[0008] Furthermore, the outer wall of the torsion spring installation groove 23 gradually increases from the insertion of the torsion spring hook 71 .

[0009] Furthermore, the torsion spring installation slot 23 is enlarged by enlarging the slot in an involute manner.

[0010] Furthermore, a limiting step 24 is provided at the bottom of the torsion spring installation groove 23, and a most curved arc surface 72 is provided at the connection between the torsion spring 70 and the torsion spring 70. When the torsion spring 70 and the spring fixing structure 20 are installed, the most curved arc surface 72 is in contact with the free end of the limiting step 24.

[0011] Furthermore, the moving track of the torsion spring hook 71 of the torsion spring 70 always moves along the torsion spring installation slot 23 of the spring fixing structure 20 close to the side wall of the torsion spring 70 .

[0012] Furthermore, a guide surface 25 toward the torsion spring installation slot 23 is provided at the free end of the inner wall of the side wall of the torsion spring installation slot 23 close to the torsion spring 70, for guiding the torsion spring hook 71 of the torsion spring 70 to enter the torsion spring installation slot 23.

[0013] Furthermore, the guide surface 25 and the torsion spring installation groove 23 are arranged in a staggered manner, so that the torsion spring hook 71 of the torsion spring 70 does not interfere with the guide surface 25 .

[0014] In some embodiments, a plurality of first hooks 21 are disposed on the outer periphery of the spring fixing structure 20 , and corresponding positions of the distal end of the shell 10 are provided with first slots 11 correspondingly engaged therewith, and the first hooks 21 are matched and engaged with the first slots 11 .

[0015] Furthermore, a first protrusion 22 is provided on the outer periphery of the spring fixing structure 20, and a first notch 12 is provided at a corresponding position of the distal end of the shell 10. When the shell 10 and the spring fixing structure 20 are matched and installed, the first protrusion 22 is just engaged with the first notch 12, thereby enhancing the connectivity between the spring fixing structure 20 and the shell 10.

[0016] In some embodiments, the proximal end of the housing 10 is provided with a screw injection mechanism 14, the screw sleeve 30 passes through the adjustment knob 50 and is sleeved with the injection button 80, the adjustment knob 50 is connected to the distal end of the housing 10, the adjustment knob 50 can only rotate relative to the housing 10, the outer periphery of the screw sleeve 30 is sleeved with a torsion spring 70, a dose dial bracket 60 and a dose display element 90, the dose display element 90 is spirally connected to the housing 10, when the injection is performed, the screw sleeve 30 is separated from the injection button 80, and the screw sleeve 30 moves toward the proximal end. After the screw injection mechanism 14 is engaged, the torsion spring 70 releases energy, the screw sleeve 30, the dosage dial bracket 60, the dosage display element 90 and the adjusting knob 50 rotate in opposite directions, and the dosage display element 90 moves toward the distal end along with the thread of the housing 10. When metering adjustment is performed, the adjusting knob 50 is rotated forward to drive the screw sleeve 30, the dosage dial bracket 60 and the dosage display element 90 to rotate synchronously, and to store energy in the torsion spring 70, and the dosage display element 90 moves toward the proximal end along with the thread of the housing 10.

[0017] In some embodiments, a plurality of first ribs 61 spaced and arranged in parallel are provided along the axial direction on the outer periphery of the dose dial bracket 60, which are used to match and connect with the first grooves on the inner wall of the dose display element 90. The dose display element 90 is rotationally connected to the inner wall of the housing 10 through a spiral pattern, so that the dose display element 90 can only move forward and backward along the axial direction relative to the dose dial bracket 60.

[0018] Furthermore, the housing 10 is provided with a dose display window, which cooperates with the dose display element 90 to display the required injection dose and the injection volume during the injection process.

[0019] In some embodiments, a second groove 63 is provided on the inner wall of the dose dial bracket 60 near the proximal end of the shell 10, and a second rib 31 is provided at a corresponding position of the screw sleeve 30. The second groove 63 is matched and connected with the second rib 31, so that the screw sleeve 30 can only move forward and backward along the axial direction relative to the dose dial bracket 60.

[0020] In some embodiments, the screw sleeve 30 is provided with a third rib 32 at the distal end close to the shell 10, and a third groove is provided at a corresponding position on the inner wall of the adjusting knob 50. The third groove is matched and connected with the third rib 32, so that the screw sleeve 30 can only move forward and backward along the axial direction relative to the adjusting knob 50.

[0021] Beneficial effects of the present invention: The present invention provides a torsion spring anti-collision device for an injection pen, comprising a shell 10, wherein the front end of the shell 10 is a proximal end, and the rear end of the shell 10 is a distal end, wherein one end of the torsion spring 70 is connected to a dosage dial bracket 60, and the other end is connected to a spring fixing structure 20, and the side wall of the torsion spring installation slot 23 of the spring fixing structure 20 close to the torsion spring 70 is shortened until there is no blocking force when the torsion spring hook 71 of the torsion spring 70 is inserted into the torsion spring installation slot 23, and at the same time, the side wall of the torsion spring installation slot 23 away from the torsion spring 70 is gradually enlarged along the walking track of the torsion spring hook 71 of the torsion spring 70, and due to the size and shape of the torsion spring installation slot 23 and the torsion spring 70 being installed to the injection pen The shapes of the shooting pen when subjected to force are basically the same, especially when the torsion spring hook 71 of the torsion spring 70 is installed on the spring fixing structure 20, the direction in which the torsion spring hook 71 enters the torsion spring mounting groove 23 is completely consistent, so that the torsion spring 70 will not be deformed due to the force on the torsion spring hook 71, thereby reducing the difficulty of installing the torsion spring 70 and reducing the cost, and preventing the torsion spring 70 from being subjected to radial compression when the torsion spring hook 71 is installed, and the accumulation process will not generate additional radial force, causing the torsion spring 70 to deform and thus explode, and at the same time avoiding the phenomenon that the injection button 80 cannot rebound, and avoiding failure caused by deformation of the torsion spring 70, thereby improving injection accuracy, improving structural reliability, and reducing failure rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a cross-sectional view of the entire injection pen of the present invention.

[0023] Figure 2 It is an overall exploded view of the torsion spring anti-collision device of the injection pen of the present invention.

[0024] Figure 3 It is a structural diagram of the connection part of the shell of the torsion spring anti-collision device of the injection pen of the present invention.

[0025] Figure 4 This is a structural diagram of the fixed end cap of the torsion spring anti-collision device of the injection pen of the present invention.

[0026] Figure 5 It is a structural diagram of the screw sleeve of the torsion spring anti-collision device of the injection pen of the present invention.

[0027] Figure 6 This is a structural diagram of the connection between the housing and the spring fixing structure of the torsion spring anti-collision device of the injection pen of the present invention.

[0028] Main component symbols

[0029] Shell 10; first slot 11; first notch 12; screw injection mechanism 14; spring fixing structure 20; first hook 21; first protrusion 22; torsion spring mounting slot 23; limiting step 24; guide surface 25; screw sleeve 30; second rib 31; third rib 32; adjustment knob 50; dosage dial bracket 60; first rib 61; second slot 63; torsion spring 70; torsion spring hook 71; most curved arc surface 72; injection button 80; dosage display element 90.

[0030] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION Example 1

[0031] like Figure 1-4 and Figure 6 As shown, a torsion spring anti-collision device for an injection pen comprises a shell 10, wherein the front end of the shell 10 is a proximal end, the rear end of the shell 10 is a distal end, the distal end of the shell 10 is provided with a spring fixing structure 20, a screw sleeve 30 is sleeved in the shell 10, the screw sleeve 30 passes through an adjusting knob 50 and is sleeved with an injection button 80, a torsion spring 70 and a dosage dial bracket 60 are sleeved on the outer periphery of the screw sleeve 30, one end of the torsion spring 70 is connected to the dosage dial bracket 60, and the other end is connected to the spring fixing structure 20, the spring fixing structure 20 is provided with a torsion spring installation groove 23, and one end of the torsion spring 70 is provided with a torsion spring hook 71, the side wall of the torsion spring installation groove 23 of the spring fixing structure 20 close to the torsion spring 70 is shortened until there is no blocking force when the torsion spring hook 71 of the torsion spring 70 is inserted into the torsion spring installation groove 23, and the distal end of the torsion spring installation groove 23 is extended to the distal end of the torsion spring installation groove 23. The distance between the side wall of the torsion spring 70 and the torsion spring hook 71 of the torsion spring 70 gradually increases. Since the size and shape of the torsion spring mounting groove 23 are basically consistent with the shape of the torsion spring 70 when it is subjected to force after being installed on the injection pen, especially when the torsion spring hook 71 of the torsion spring 70 is installed on the spring fixing structure 20, the direction in which the torsion spring hook 71 enters the torsion spring mounting groove 23 is completely consistent, so that the torsion spring 70 will not be deformed due to the force on the torsion spring hook 71, thereby reducing the installation difficulty of the torsion spring 70 and reducing the cost, and avoiding the torsion spring 70 being subjected to radial compression when the torsion spring hook 71 is installed, and the accumulation process of force will generate additional radial force, causing the torsion spring 70 to deform and explode, and at the same time avoiding the phenomenon that the injection button 80 cannot rebound, and avoiding failure caused by deformation of the torsion spring 70, thereby improving injection accuracy, improving structural reliability, and reducing failure rate.

[0032] The outer wall of the torsion spring installation groove 23 gradually increases from the insertion of the torsion spring hook 71, and the torsion spring installation groove 23 is increased in an involute manner to open a larger groove. A limiting step 24 is provided at the bottom of the torsion spring installation groove 23, and a most curved arc surface 72 is provided at the connection between the torsion spring 70 and the torsion spring 70. When the torsion spring 70 and the spring fixing structure 20 are installed, the most curved arc surface 72 is in contact with the free end of the limiting step 24, and the walking trajectory of the torsion spring hook 71 of the torsion spring 70 always walks along the side wall of the torsion spring installation groove 23 of the spring fixing structure 20 close to the torsion spring 70. The free end of the inner wall of the side wall of the torsion spring installation groove 23 close to the torsion spring 70 is provided with a guide surface 25 toward the torsion spring installation groove 23, which is used to guide the torsion spring hook 71 of the torsion spring 70 to enter the torsion spring installation groove 23 when entering. The guide surface 25 is staggered with the torsion spring installation groove 23, and the torsion spring hook 71 of the torsion spring 70 does not interfere with the guide surface 25.

[0033] A plurality of first hooks 21 are disposed on the outer periphery of the spring fixing structure 20 , and corresponding positions of the distal end of the housing 10 are provided with first slots 11 correspondingly engaged therewith, and the first hooks 21 are matched and engaged with the first slots 11 .

[0034] The proximal end of the housing 10 is provided with a screw injection mechanism 14, the screw sleeve 30 passes through the adjustment knob 50 and is sleeved with the injection button 80, the adjustment knob 50 is connected to the distal end of the housing 10, the adjustment knob 50 can only rotate relative to the housing 10, the outer periphery of the screw sleeve 30 is sleeved with a torsion spring 70, a dosage dial bracket 60 and a dosage display element 90, the dosage display element 90 is spirally connected to the housing 10, when an injection is performed, the screw sleeve 30 is separated from the injection button 80, and the screw sleeve 30 moves toward the proximal end to be in contact with the screw After the rod injection mechanism 14 is engaged, injection is performed, the torsion spring 70 releases energy, the screw sleeve 30, the dose dial bracket 60, the dose display element 90 and the adjustment knob 50 rotate in opposite directions, and the dose display element 90 moves toward the distal end along with the thread of the housing 10. When metering adjustment is performed, the adjustment knob 50 is rotated forward to drive the screw sleeve 30, the dose dial bracket 60 and the dose display element 90 to rotate synchronously, and to store energy in the torsion spring 70, and the dose display element 90 moves toward the proximal end along with the thread of the housing 10.

[0035] Figure 4As shown, the outer periphery of the spring fixing structure 20 is further provided with a first protrusion 22, and the corresponding position of the distal end of the shell 10 is provided with a first notch 12. When the shell 10 and the spring fixing structure 20 are matched and installed, the first protrusion 22 is just engaged with the first notch 12, so as to enhance the connectivity between the spring fixing structure 20 and the shell 10. The outer periphery of the dose dial bracket 60 is provided with a plurality of first ribs 61 arranged in parallel and spaced apart in the axial direction, which are used to match and connect with the first grooves on the inner wall of the dose display element 90. The dose display element 90 is rotationally connected to the inner wall of the shell 10 through a spiral pattern, so that the dose display element 90 can only move forward and backward along the axial direction relative to the dose dial bracket 60. The shell 10 is provided with a dose display window, which cooperates with the dose display element 90 to display the required injection dose and the injection amount during the injection process.

[0036] like Figure 2 and Figure 5 As shown, a second groove 63 is provided on the inner wall of the dose dial bracket 60 near the proximal end of the shell 10, and a second rib 31 is provided at a corresponding position of the screw sleeve 30. The second groove 63 is matched and connected with the second rib 31, so that the screw sleeve 30 can only move forward and backward along the axial direction relative to the dose dial bracket 60, and a third rib 32 is provided on the distal end of the screw sleeve 30 near the shell 10. A third groove is provided on the inner wall of the adjusting knob 50 at a corresponding position, and the third groove is matched and connected with the third rib 32, so that the screw sleeve 30 can only move forward and backward along the axial direction relative to the adjusting knob 50.

[0037] Beneficial effects of the present invention: The present invention provides a torsion spring anti-collision device for an injection pen, comprising a shell 10, wherein the front end of the shell 10 is a proximal end, and the rear end of the shell 10 is a distal end, wherein one end of the torsion spring 70 is connected to a dosage dial bracket 60, and the other end is connected to a spring fixing structure 20, and the side wall of the torsion spring installation slot 23 of the spring fixing structure 20 close to the torsion spring 70 is shortened until there is no blocking force when the torsion spring hook 71 of the torsion spring 70 is inserted into the torsion spring installation slot 23, and at the same time, the side wall of the torsion spring installation slot 23 away from the torsion spring 70 is gradually enlarged along the walking track of the torsion spring hook 71 of the torsion spring 70, and due to the size and shape of the torsion spring installation slot 23 and the torsion spring 70 being installed to the injection pen The shapes of the shooting pen when subjected to force are basically the same, especially when the torsion spring hook 71 of the torsion spring 70 is installed on the spring fixing structure 20, the direction in which the torsion spring hook 71 enters the torsion spring mounting groove 23 is completely consistent, so that the torsion spring 70 will not be deformed due to the force on the torsion spring hook 71, thereby reducing the difficulty of installing the torsion spring 70 and reducing the cost, and preventing the torsion spring 70 from being subjected to radial compression when the torsion spring hook 71 is installed, and the accumulation process will not generate additional radial force, causing the torsion spring 70 to deform and thus explode, and at the same time avoiding the phenomenon that the injection button 80 cannot rebound, and avoiding failure caused by deformation of the torsion spring 70, thereby improving injection accuracy, improving structural reliability, and reducing failure rate.

[0038] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A torsion spring anti-collision device for an injection pen, comprising a housing (10), the front end of the housing (10) being a proximal end, the rear end of the housing (10) being a distal end, the distal end of the housing (10) being provided with a spring fixing structure (20), a screw sleeve (30) being sleeved in the housing (10), the screw sleeve (30) passing through an adjustment knob (50) and being sleeved with an injection button (80), a torsion spring (70) and a dosage dial bracket (60) being sleeved on the outer periphery of the screw sleeve (30), one end of the torsion spring (70) being connected to the dosage dial bracket (60), and the other end of the torsion spring (70) being connected to the spring fixing structure (20), characterized in that: The spring fixing structure (20) is provided with a torsion spring installation groove (23), and one end of the torsion spring (70) is provided with a torsion spring hook (71).

2. The torsion spring anti-collision device of the injection pen according to claim 1, characterized in that: The torsion spring installation groove (23) gradually increases in size from the time the torsion spring hook (71) is inserted.

3. The torsion spring anti-collision device of the injection pen according to claim 1, characterized in that: The outer wall of the torsion spring installation groove (23) gradually increases from the time when the torsion spring hook (71) is inserted.

4. The torsion spring anti-collision device of the injection pen according to claim 3, characterized in that: The torsion spring installation groove (23) is enlarged by opening the groove in an involute manner.

5. The torsion spring anti-collision device of the injection pen according to claim 4, characterized in that: A limiting step (24) is provided at the bottom of the torsion spring installation groove (23), and a most curved arc surface (72) is provided at the connection between the torsion spring (70) and the torsion spring (70); when the torsion spring (70) and the spring fixing structure (20) are installed, the most curved arc surface (72) abuts against the free end of the limiting step (24).

6. The torsion spring anti-collision device of the injection pen according to claim 5, characterized in that: The travel path of the torsion spring hook (71) of the torsion spring (70) always follows the torsion spring installation slot (23) of the spring fixing structure (20) and is close to the side wall of the torsion spring (70).

7. The torsion spring anti-collision device of the injection pen according to claim 6, characterized in that: A free end of the inner wall of the torsion spring installation slot (23) close to the side wall of the torsion spring (70) is provided with a guide surface (25) toward the torsion spring installation slot (23) for guiding the torsion spring hook (71) of the torsion spring (70) into the torsion spring installation slot (23).

8. The torsion spring anti-collision device of the injection pen according to claim 7, characterized in that: The guide surface (25) and the torsion spring installation groove (23) are arranged in an offset manner, so that the torsion spring hook (71) used for the torsion spring (70) does not interfere with the guide surface (25).

9. The torsion spring anti-collision device of the injection pen according to claim 1, characterized in that: A plurality of first hooks (21) are provided on the outer periphery of the spring fixing structure (20), and corresponding positions of the distal end of the housing (10) are provided with first slots (11) correspondingly engaged therewith, and the first hooks (21) are matched and engaged with the first slots (11).

10. The torsion spring anti-collision device of the injection pen according to claim 9, characterized in that: The outer periphery of the spring fixing structure (20) is further provided with a first protrusion (22), and a first notch (12) is provided at a corresponding position of the distal end of the shell (10); when the shell (10) and the spring fixing structure (20) are matched and installed, the first protrusion (22) is exactly engaged with the first notch (12), thereby enhancing the connectivity between the spring fixing structure (20) and the shell (10).

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