Urethral catheter bending resistance test tool

Abstract

The invention belongs to the technical field of instrument testing, and particularly relates to a catheter bending resistance testing tool which comprises a testing main support, an extending edge is arranged on one side of the testing main support, a bent edge is arranged on the side, away from the extending edge, of the testing main support, and a shaft rod is movably connected to the position, close to the edge, of the surface of one side of the extending edge through a rotating shaft. Threaded holes are formed in the upper surface of the shaft rod, a coupling piece is fixedly installed at one end of the shaft rod through a bolt, threaded holes are formed in the two sides of the outer arc face of the coupling piece, and the catheter can be subjected to additional direction adjusting acting force in the process of penetrating through the guide sleeve piece through the guide sleeve piece and the locking teeth. The adjustment simulates the tiny direction change of the catheter caused by factors such as movement and extrusion of tissues and organs in a complex physiological environment of a human body, and meanwhile, the bending and twisting plate continuously rotates back and forth according to a set angle and frequency to apply a composite bending effect on the catheter, so that the catheter is subjected to secondary analysis.

Description

Technical Field

[0001] This invention belongs to the field of instrument testing technology, specifically a catheter bending resistance testing tool. Background Technology

[0002] Urinary catheters are commonly used medical devices in clinical practice to help patients drain urine. They are widely used in fields such as urology. They are usually made of materials such as natural rubber, silicone rubber or polyvinyl chloride. During use, urinary catheters will frequently undergo bending and twisting operations. For example, when inserted into the urethra and during the patient's daily activities, the urinary catheter will bend to varying degrees.

[0003] To ensure the safety and reliability of urinary catheters in practical applications, relevant medical device industry standards have put forward clear requirements for the bending resistance of urinary catheters. For example, the YY0325-2016 standard "Disposable Sterile Urinary Catheters" stipulates that the middle part of the urinary catheter must be bent into a ring with a circumference of 15d (d is the nominal outer diameter of the urinary catheter) using specific testing tools, and then relevant flow tests are carried out to evaluate the bending resistance of the urinary catheter.

[0004] Chinese invention patent publication number CN112113827B discloses a catheter bending resistance testing tool, specifically relating to the field of instrument testing technology. The tool includes a testing platform and a catheter. The testing platform has a movable first test block and a second test block. A first slide rail is provided at the bottom of the first test block, and a second slide rail is provided at the bottom of the second test block. The first slide rail is parallel to the edge of the testing platform, and the second slide rail is intersected with the first slide rail. A sliding component for the catheter to pass through is provided on the first test block, and a rotating fixing component for the catheter to pass through is provided on the second test block. During testing, the tool uses a rotatable fixing tube at one end to secure the catheter, and a ball bearing and conduit at the other end to limit the catheter's movement. When the user pulls the catheter, it can adaptively rotate, preventing the catheter from twisting.

[0005] However, the above-mentioned technologies often have the following drawbacks: In actual medical practice, the urinary catheter will be subjected to complex and varied bending conditions due to the patient's different body position, activity status and other factors, and can only achieve a limited number of simple bending forms. This makes the assessment of the urinary catheter's bending resistance extremely one-sided and unable to accurately reflect its actual performance in real clinical environments.

[0006] Therefore, the present invention provides a tool for testing the bending resistance of a urinary catheter. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0008] The technical solution adopted by the present invention to solve its technical problem is as follows: A catheter bending resistance test tool of the present invention includes a test main support. One side of the test main support is provided with an extension edge, and the side of the test main support away from the extension edge is provided with a bending edge. A shaft is movably connected to one side surface of the extension edge near the edge via a rotating shaft. A threaded hole is opened on the upper surface of the shaft. A coupling is fixedly installed at one end of the shaft by bolts. Threaded holes are provided on both sides of the outer arc surface of the coupling. A rotating assembly is fixedly installed on the inner arc surface of the coupling by bolts. A hinge arm is provided at the bottom of the outer arc surface of the rotating assembly. A first rotating rod is fixedly installed at one end of the hinge arm. A bending and twisting plate is connected through one end of the first rotating rod. A second rotating rod is connected through the top of one side surface of the bending and twisting plate. One end of the second rotating rod is fixedly connected to the inner side wall of the rotating assembly. The rotating assembly and the bending and twisting plate are in the same plane. A groove is provided on the outer arc surface of the bending and twisting plate. A test side support is movably connected to one end of the second rotating rod that passes through the bending and twisting plate via a rotating shaft.

[0009] The bottom of one side surface of the test side bracket is provided with a receiving end, the top of the side of the test side bracket away from the receiving end is provided with a series end, and a connecting side plate is fixedly installed on the top of the side of the test side bracket near the receiving end by bolts.

[0010] One side of the upper surface of the connecting side plate is provided with a through hole, one side of the series end is placed at the front end of the bending and twisting plate and forms a gap with the bending and twisting plate, and one side of the outer arc surface of the coupling is provided with gear A.

[0011] A gear B is movably connected between the extended side and the bent side of one side of the main test support via a rotating shaft. The outer arc surface serrations of the gear A are meshed with the gear B.

[0012] A fixing plate is fixedly installed on the upper surface of the series end by bolts. Positioning wings are provided on both sides of the upper surface of the fixing plate, and a connection hole is opened in the middle of one side surface of the positioning wing.

[0013] A locking rod is connected through the inner arc surface of the connecting hole. A locking tooth is fixedly installed in the middle of the outer arc surface of the locking rod. A slot is opened on the outer arc surface of the locking tooth. A guide kit is connected through the locking rod near the edge of the outer arc surface. The inner arc surface of the guide kit has a stepped end.

[0014] A through hole is provided in the middle of one side surface of the guide kit, and a sliding groove is provided at the bottom of the outer arc surface of the guide kit. A top rod is slidably engaged on the inner arc surface of the sliding groove, and the outer arc surface of the top rod is movably engaged with the groove of the locking tooth.

[0015] The upper surface of the stepped end is movably abutted against an inner retractable component. One side surface of the inner retractable component is provided with a contact surface. A conical spring is provided on the side of the contact surface near the guide component. One end of the conical spring abuts against the outer arc surface of the locking rod.

[0016] The inner retraction kit has a top head on the side away from the conical spring. A sleeve is fitted onto the outer arc surface of the inner retraction kit. A braking end is provided at the top of the inner arc surface of the sleeve. The lower surface of the braking end abuts against the outer arc surface of the inner retraction kit.

[0017] A receiving cavity is provided between the sleeve and the outer arc surface of the inner retraction kit. A compression spring is sleeved on the inner arc surface of the receiving cavity. One end of the compression spring abuts against one side end face of the guide kit, and the other end of the compression spring is disposed between the sleeve and the braking end.

[0018] The beneficial effects of this invention are as follows: 1. The bottom of the bending and twisting plate deflects to the right and fits tightly against the surface of the catheter, while the top deflects to the left, forming a specific angle with the series end. This causes a secondary bend in the catheter, simulating the complex bending conditions that the catheter experiences during clinical use due to the patient's complex body position and activities. As the bending and twisting plate rotates back and forth at a set angle and frequency, the catheter is continuously subjected to bending effects of different degrees and directions. Testers can monitor the morphological changes and internal fluid flow of the catheter in real time during this process, thereby comprehensively evaluating the catheter's bending resistance and providing a reliable basis for improving product quality and the safety of clinical applications.

[0019] 2. As the catheter passes through the guide kit and locking teeth, it is subjected to an additional directional adjustment force. This adjustment simulates the minute directional changes of the catheter caused by the movement and compression of tissues and organs in the complex physiological environment of the human body. At the same time, the bending and twisting plate continuously rotates back and forth at a predetermined angle and frequency, applying a compound bending effect to the catheter, thereby performing a secondary analysis of the catheter.

[0020] 3. The inner sleeve and the inner fitting provide stable and uniform support and constraint for the catheter before it is filled with water. As the subsequent test process progresses, the bending and twisting plate rotates back and forth at a predetermined angle and frequency, applying a compound bending effect to the catheter. At the same time, the guide fitting also swings continuously at an inclined angle to adjust the direction of the catheter. Throughout the test, the constraint structure formed by the sleeve and the top head can effectively counteract the influence of gravity on the catheter, ensuring that the catheter maintains a circular cross-section and improving the accuracy of the test data. Attached Figure Description

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] Figure 1 This is a three-dimensional view of the main experimental support of the present invention.

[0023] Figure 2 This is a schematic diagram of the disassembly structure of the coupling component of the present invention.

[0024] Figure 3 This is a cross-sectional view of the side-view guide kit in this invention.

[0025] Figure 4 This is a schematic diagram of the overall structure of the gear set in this invention.

[0026] Figure 5 This is a schematic diagram of the internal disassembly structure of the guide kit in this invention.

[0027] Figure 6 In this invention Figure 3 A magnified structural diagram of point A in the middle.

[0028] Figure 7 This is a partial cross-sectional schematic diagram of the internal structure of the guide kit in this invention.

[0029] Figure 8 This is a top view schematic diagram of the overall structure of this invention.

[0030] In the diagram: 1. Main test support; 101. Extension edge; 102. Bending edge; 2. Shaft; 3. Coupling; 4. Rotating assembly; 401. Hinge arm; 5. First rotating rod; 6. Bending and twisting plate; 7. Second rotating rod; 8. Test side support; 801. Series end; 9. Connecting side plate; 901. Through hole; 10. Clearance; 11. Gear A; 12. Gear B; 13. Fixing plate; 131. Positioning side wing; 132. Connecting hole; 14. Locking rod; 15. Locking tooth; 151. Slot; 16. Guide assembly; 161. Stepped end; 162. Slide groove; 17. Top rod; 18. Retracting assembly; 181. Contact surface; 182. Top head; 19. Conical spring; 20. Sleeve; 201. Braking end; 21. Receiving cavity; 22. Compression spring. Detailed Implementation

[0031] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0032] like Figure 1 , Figure 2 , Figure 4 and Figure 8As shown, this embodiment of the invention includes a test main support 1. One side of the test main support 1 has an extension edge 101, and the side of the test main support 1 away from the extension edge 101 has a bent edge 102. A shaft 2 is movably connected to one side surface of the extension edge 101 near its edge via a rotating shaft. A threaded hole is formed on the upper surface of the shaft 2. A coupling 3 is fixedly installed at one end of the shaft 2 by bolts. Threaded holes are formed on both sides of the outer arc surface of the coupling 3. A rotating assembly 4 is fixedly installed on the inner arc surface of the coupling 3 by bolts. A hinge arm 401 is provided at the bottom of the outer arc surface of the rotating assembly 4. A first rotating rod 5 is fixedly installed at one end of the hinge arm 401. A bent-torsion plate 6 is connected through one end of the first rotating rod 5. A [missing information - likely a component or part] is connected through the top of one side surface of the bent-torsion plate 6. The second rotating rod 7 has one end fixedly connected to the inner wall of the rotating assembly 4. The rotating assembly 4 and the bending and twisting plate 6 are in the same plane. The outer arc surface of the bending and twisting plate 6 is provided with a groove. The second rotating rod 7 passes through one end of the bending and twisting plate 6 and is movably connected to the test side bracket 8 through a rotating shaft. The bottom of one side surface of the test side bracket 8 is provided with a receiving end. The top of the side of the test side bracket 8 away from the receiving end is provided with a series end 801. The top of the side of the test side bracket 8 near the receiving end is fixedly installed with a connecting side plate 9 by bolts. One side of the upper surface of the connecting side plate 9 is provided with a through hole 901. One side of the series end 801 is placed at the front end of the bending and twisting plate 6 and forms a gap 10 with the bending and twisting plate 6. The outer arc surface of the coupling 3 is provided with a gear A11.

[0033] When conducting the catheter bending resistance test, firstly, the lower surface of the main test support 1 is placed stably at the bottom of the instrument to ensure the entire test device has a stable foundation. Then, the catheter at the top is slowly extended downwards from one end and placed at the bottom of the bending and twisting plate 6. To ensure the high accuracy of the test results, the torque output of the servo motor is used to control the rotation angle of gear A11 for in-depth analysis. When the control gear B12 rotates, the other gear A11 meshing with it will rotate synchronously. A shaft 2 is installed on one end face of gear A11. The power generated by the rotation of shaft 2 is transmitted sequentially to the coupling 3 and the interior of the rotating assembly 4. The bottom of the outer arc surface of the rotating assembly 4 is provided with a hinge arm 401. The bottom of the hinge arm 401 is connected to the middle of the rotating assembly 4 via a first rotating rod 5 and a second rotating rod 7, respectively. A bent-twist plate 6 is connected to one end of both the first rotating rod 5 and the second rotating rod 7. At this time, the catheter is bent and fits against the bottom of the outer arc surface of the bent-twist plate 6. Simultaneously, a test-side support 8 is movably connected to one end of the second rotating rod 7. A series end 801 is provided at the front end of one side of the test-side support 8. A gap 10 is reserved between the series end 801 and the bent-twist plate 6 so that the catheter, fitting against the bottom end of the bent-twist plate 6, extends upward into the gap 10. The bent-twist plate 6 rotates around the first rotating rod 5. When gear A11 rotates, the top of one end of the bent-twist plate 6 begins to rotate around the first rotating rod 5. Figure 3In the indicated state, when the bending and twisting plate 6 deflects to the right, its bottom deflects to the right and comes into close contact with the surface of the catheter. At the same time, its top deflects to the left, forming a specific angle with the series end 801, thus subjecting the catheter to a secondary bend. This secondary bend simulates the complex bending conditions that the catheter experiences during clinical use due to the patient's complex body position and activities. As the bending and twisting plate 6 rotates back and forth at a set angle and frequency, the catheter continuously undergoes bending actions of different degrees and directions. The test personnel can monitor the morphological changes and internal fluid flow of the catheter in real time during this process, thereby comprehensively evaluating the bending resistance of the catheter and providing a reliable basis for improving product quality and the safety of clinical applications.

[0034] like Figure 3 , Figure 5 , Figure 6 and Figure 7 As shown, a gear B12 is movably connected between one side extension 101 and the bent side 102 of the main test support 1 via a rotating shaft. The outer arc surface serration of gear A11 meshes with gear B12. A fixing plate 13 is fixedly installed on the upper surface of the series end 801 by bolts. Positioning wings 131 are provided on both sides of the upper surface of the fixing plate 13. A connecting hole 132 is opened in the middle of one side surface of the positioning wing 131. A locking rod 14 is connected through the inner arc surface of the connecting hole 132. A locking tooth 15 is fixedly installed in the middle of the outer arc surface. The outer arc surface of the locking tooth 15 has a slot 151. A guide kit 16 is connected through the locking rod 14 near the edge of the outer arc surface. The inner arc surface of the guide kit 16 has a stepped end 161. A through hole is opened in the middle of one side surface of the guide kit 16. A sliding groove 162 is opened at the bottom of the outer arc surface of the guide kit 16. A top rod 17 is slidably engaged with the inner arc surface of the sliding groove 162. The outer arc surface of the top rod 17 is movably engaged with the slot 151 of the locking tooth 15.

[0035] The end of the catheter that passes through the gap 10 passes through the guide kit 16 connected to the top of the fixing plate 13. To effectively prevent the catheter from falling off during the bending test, positioning wings 131 are provided on both sides of the fixing plate 13. Locking rods 14 are connected to the connecting holes 132 on both sides of the positioning wings 131. The locking rods 14 and the guide kit 16 are rotatably connected and fixedly installed with the locking teeth 15. Thus, the guide kit 16 can rotate around the locking rods 14. At the stepped end 161 of the guide kit 16, it abuts against the inner retracting kit 18. The inner retracting kit 18 has a contact surface 181 at the bottom and a top head 182 at the top. A conical spring 19 is fixedly installed on the contact surface 181 of the part. Since the conical spring 19 has a structure with a small front end and a large rear end, the smaller end face of one side abuts against the middle of the outer arc surface of the push rod 17, and the push rod 17 is connected to the slide groove 162 on the surface of the guide kit 16. In this way, under the action of the conical spring 19, the push rod 17 always remains tightly engaged with the slot 151 on the outer arc surface of the locking tooth 15. When the guide kit 16 is swung, once the push rod 17 contacts the protruding end of the locking tooth 15, it will compress the conical spring 19 backward and then disengage from the slot 151 on one side. Since the spacing of the slots 151 is consistent, the angle of each swing of the guide kit 16 is also equal. The upper surface of the stepped end 161 is movably abutted against the inner retractable component 18. One side surface of the inner retractable component 18 is provided with a contact surface 181. A conical spring 19 is provided on the side of the contact surface 181 near the guide component 16. One end of the conical spring 19 abuts against the outer arc surface of the locking rod 14. A top head 182 is provided on the side of the inner retractable component 18 away from the conical spring 19. A sleeve 20 is sleeved on the outer arc surface of the inner retractable component 18. A braking end 201 is provided at the top of the inner arc surface of the sleeve 20. The lower surface of the braking end 201 abuts against the outer arc surface of the inner retractable component 18. A receiving cavity 21 is provided between the sleeve 20 and the outer arc surface of the inner retractable component 18. A compression spring 22 is sleeved on the inner arc surface of the receiving cavity 21. One end of the compression spring 22 abuts against one side end face of the guide component 16. The other end of the compression spring 22 is located between the sleeve 20 and the braking end 201.

[0036] As the guide kit 16 continues to swing at a set angle, the catheter experiences additional directional adjustment force as it passes through the guide kit 16. This adjustment simulates the minute directional changes of the catheter caused by the movement and compression of tissues and organs in the complex physiological environment of the human body. At the same time, the bending and twisting plate 6 continuously rotates back and forth at a predetermined angle and frequency, applying a compound bending effect to the catheter. With the help of existing measuring instruments, testers can monitor the subtle morphological changes of the catheter in this complex process in real time, such as local wrinkles in the catheter wall, slight contraction or expansion of the diameter, and precise fluctuation data of the internal fluid flow. This allows for a more comprehensive and accurate assessment of the catheter's bending resistance, providing solid data support for further optimization of catheter product quality and the safety and reliability of clinical applications.

[0037] The top head 182 connected to the inner retraction kit 18 adopts an elastic structure design. Its material has good flexibility and resilience. After the catheter is successfully passed through, in order to effectively avoid the catheter deforming into an ellipse under the action of gravity after being filled with water, which would cause errors in the test results, a sleeve 20 is precisely placed at the front end of the inner retraction kit 18. The top of the inner arc surface of the sleeve 20 is provided with a braking end 201. One end face of the sleeve is open and a compression spring 22 is installed inside. When the sleeve 20 moves backward under the action of external force, the compression spring 22 connected to it will then undergo elastic deformation. As the sleeve 20 continues to move backward, it will gradually apply pressure to the elastic part extending to the front end of the inner retraction kit 18. During this process, when the sleeve 20 is compressed, the top head 182 at its top will tighten inward due to the force and finally press against the outer arc surface of the catheter. Before the catheter is filled with water, it can provide stable and uniform support and constraint. As the subsequent test process progresses, the bending and twisting plate 6 continues to rotate back and forth at a predetermined angle and frequency, applying a compound bending effect to the catheter. At the same time, the guide kit 16 also continuously swings at an inclined angle to adjust the direction of the catheter. During the entire test, the constraint structure composed of the sleeve 20 and the top head 182 can effectively counteract the influence of gravity on the catheter, ensuring that the catheter maintains a circular cross-section and improving the accuracy of the test data.

[0038] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0039] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A catheter bending resistance testing tool, characterized in that: The test main support (1) includes an extension edge (101) on one side and a bent edge (102) on the side away from the extension edge (101). A shaft (2) is movably connected to one side of the extension edge (101) near its edge via a rotating shaft. A threaded hole is provided on the upper surface of the shaft (2). A coupling (3) is fixedly installed at one end of the shaft (2) by bolts. Threaded holes are provided on both sides of the outer arc surface of the coupling (3). A rotating assembly (4) is fixedly installed on the inner arc surface of the coupling (3) by bolts. A hinge arm (401) is provided at the bottom of the outer arc surface. A first rotating rod (5) is fixedly installed at one end of the hinge arm (401). A bent and twisted plate (6) is connected through one end of the first rotating rod (5). A second rotating rod (7) is connected through the top of one side surface of the bent and twisted plate (6). One end of the second rotating rod (7) is fixedly connected to the inner wall of the rotating kit (4). The rotating kit (4) and the bent and twisted plate (6) are in the same plane. The outer arc surface of the bent and twisted plate (6) is provided with a groove. The test side bracket (8) is movably connected through a rotating shaft to one end of the second rotating rod (7) that passes through the bent and twisted plate (6).

2. The catheter bending resistance testing tool according to claim 1, characterized in that: The bottom of one side surface of the test side bracket (8) is provided with a receiving end, and the top of the side of the test side bracket (8) away from the receiving end is provided with a series end (801). The top of the side of the test side bracket (8) near the receiving end is fixedly installed with a connecting side plate (9) by bolts.

3. The catheter bending resistance testing tool according to claim 2, characterized in that: The upper surface of the connecting side plate (9) is provided with a perforation (901), one side of the serial end (801) is placed at the front end of the bending and twisting plate (6) and a gap (10) is formed between it and the bending and twisting plate (6). The outer arc surface of the coupling (3) is provided with a gear A (11).

4. The catheter bending resistance testing tool according to claim 3, characterized in that: A gear B (12) is movably connected between the extended side (101) and the bent side (102) of the test main support (1) via a rotating shaft. The outer arc surface sawtooth of the gear A (11) meshes with the gear B (12).

5. The catheter bending resistance testing tool according to claim 2, characterized in that: The upper surface of the series end (801) is fixedly mounted with a fixing plate (13) by bolts. Both sides of the upper surface of the fixing plate (13) are provided with positioning wings (131), and a connection hole (132) is opened in the middle of one side surface of the positioning wing (131).

6. The catheter bending resistance testing tool according to claim 5, characterized in that: A locking rod (14) is connected through the inner arc surface of the connecting hole (132). A locking tooth (15) is fixedly installed in the middle of the outer arc surface of the locking rod (14). A slot (151) is opened on the outer arc surface of the locking tooth (15). A guide kit (16) is connected through the locking rod (14) near the edge of the outer arc surface. A stepped end (161) is provided on the inner arc surface of the guide kit (16).

7. The catheter bending resistance testing tool according to claim 6, characterized in that: A through hole is provided in the middle of one side surface of the guide kit (16), and a sliding groove (162) is provided at the bottom of the outer arc surface of the guide kit (16). A top rod (17) is slidably engaged on the inner arc surface of the sliding groove (162), and the outer arc surface of the top rod (17) is movably engaged with the groove (151) of the locking tooth (15).

8. The catheter bending resistance testing tool according to claim 7, characterized in that: The upper surface of the stepped end (161) is movably abutted against the inner retractable kit (18). One side surface of the inner retractable kit (18) is provided with a fitting surface (181). A conical spring (19) is provided on the side of the fitting surface (181) near the guide kit (16). One end of the conical spring (19) abuts against the outer arc surface of the locking rod (14).

9. The catheter bending resistance testing tool according to claim 8, characterized in that: The inner retractable kit (18) has a top head (182) on the side away from the conical spring (19). A sleeve (20) is sleeved on the outer arc surface of the inner retractable kit (18). A braking end (201) is provided on the top of the inner arc surface of the sleeve (20). The lower surface of the braking end (201) abuts against the outer arc surface of the inner retractable kit (18).

10. A catheter bending resistance testing tool according to claim 9, characterized in that: A receiving cavity (21) is provided between the outer arc surface of the sleeve (20) and the inner arc surface of the inner retraction kit (18). A compression spring (22) is sleeved on the inner arc surface of the receiving cavity (21). One end of the compression spring (22) abuts against one side end face of the guide kit (16), and the other end of the compression spring (22) is disposed between the sleeve (20) and the braking end (201).

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