Multi-directional adjustment oral cavity supporting mechanism for mandibular protraction position

Abstract

The invention relates to the technical field of medical instruments, and provides a mandibular protraction position multidirectional adjustment oral cavity supporting mechanism which comprises a head hoop body worn on the head, two first fixing frames symmetrically installed on the head hoop body, metal arms inserted into the inner sides of the first fixing frames and a plurality of insertion holes formed in the metal arms. The device is worn on the head of a patient through the head band main body, and then the height and the angle of the metal arm upper and lower jaw supporting frame can be adjusted under the cooperation of the fixing assembly, the inserting holes, the T-shaped rotary knob and the positioning mechanism. Meanwhile, under the cooperation of the clamping mechanism, the elastic clamp and the dilator, the mouth of the patient can be dilated, then the airway of the patient can be kept smooth, the situation that an anesthetist manually lifts the lower jaw for a long time is avoided, the airway is rapidly established in first aid, and the suffocation risk is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly relates to a multi-directionally adjustable oral support mechanism in the mandibular protrusion position. Background Art

[0002] Oral surgery is a branch of stomatology, mainly involving the treatment and surgery of oral and maxillofacial diseases. Oral surgeons can solve various oral and maxillofacial diseases through surgical treatment, usually including damaged teeth, periapical periodontitis, alveolitis, etc.

[0003] Currently, during each comfortable anesthesia treatment, in order to prevent asphyxia caused by the patient's mandibular retraction after general anesthesia, anesthesiologists usually hold the patient's mandible forward and open the mouth with their hands. After a long time, it will cause muscle fatigue in the doctor's hands and affect the stability and accuracy of surgical operations. Therefore, a multi-directionally adjustable oral support mechanism in the mandibular protrusion position is needed. Summary of the Invention

[0004] The present invention provides a multi-directionally adjustable oral support mechanism in the mandibular protrusion position, which solves the problem in the related art that during each comfortable anesthesia treatment, in order to prevent asphyxia caused by the patient's mandibular retraction after general anesthesia, anesthesiologists usually hold the patient's mandible forward and open the mouth with their hands. After a long time, it will cause muscle fatigue in the doctor's hands and affect the stability and accuracy of surgical operations.

[0005] The technical solution of the present invention is as follows: A multi-directionally adjustable oral support mechanism in the mandibular protrusion position, comprising:

[0006] A headband main body worn on the head;

[0007] Two first fixing frames symmetrically installed on the headband main body;

[0008] A metal arm inserted inside the first fixing frame;

[0009] Multiple insertion holes formed on the metal arm, and the multiple insertion holes are arranged in sequence from top to bottom;

[0010] A fixing component arranged on the first fixing frame, and one end of the fixing component is inserted into one of the insertion holes for locking the metal arm with adjusted height inside the first fixing frame;

[0011] A mandibular support frame inserted at the bottom of the metal arm;

[0012] An elastic clip fixedly installed on the front side of the mandibular support frame;

[0013] A spreader clamped inside the elastic clip;

[0014] And a T-shaped knob rotatably mounted on the metal arm, and the lower jaw support frame is fixedly mounted on the T-shaped knob;

[0015] Wherein a positioning mechanism is arranged on the metal arm, and the positioning mechanism is in contact with the T-shaped knob;

[0016] A strip-shaped groove is formed in a position close to the end of the lower jaw support frame, an inverted T-shaped rod is inserted into the strip-shaped groove, a fixing plate is fixedly mounted on the top of the inverted T-shaped rod, and a clamping mechanism is arranged on the top of the fixing plate.

[0017] Preferably, a sponge pad is arranged on the inner side of the headband main body, a pasting mechanism is arranged on one side of the sponge pad, and the sponge pad is fixed on the inner side of the headband main body through the pasting mechanism.

[0018] Preferably, the pasting mechanism includes a hook surface of a magic tape fixedly mounted on one side of the sponge pad, a loop surface of the magic tape is fixedly mounted on the inner side of the headband main body, and the sponge pad is pasted to the loop surface of the magic tape and the headband main body respectively through the hook surface of the magic tape.

[0019] Preferably, the headband main body includes a headband strip, and both of the first fixing frames are sleeved on the headband strip;

[0020] A second fixing frame is fixedly mounted on a position close to the end of one side of the headband strip, and one end of the headband strip far from the second fixing frame is inserted into the second fixing frame;

[0021] A first hand-tightening screw is threadedly connected to the second fixing frame, and the screw end of the first hand-tightening screw abuts against the headband strip inserted into the inner side of the second fixing frame.

[0022] Preferably, the clamping mechanism includes a fixing rod fixedly mounted on the top of the fixing plate, two clamping jaws are rotatably mounted on the outer side wall of the fixing rod, and a rigid clamp is fixedly mounted on one end of the two clamping jaws together;

[0023] A lead screw is rotatably mounted on one side of the fixing plate, a connecting block is threadedly connected to the outer side wall of the lead screw, connecting plates are pin-connected to both sides of the connecting block, and the other ends of the two connecting plates are respectively pin-connected to the two clamping jaws.

[0024] Preferably, the fixing component includes a T-shaped rod penetrating through the first fixing frame, and the larger end of the T-shaped rod is inserted into the insertion hole, a first spring is sleeved on the T-shaped rod, and the first spring is located between the first fixing frame and the larger end of the T-shaped rod.

[0025] Preferably, one end of the T-shaped rod is fixedly installed with a strip-shaped plate, and the strip-shaped plate is located on the end of the T-shaped rod with a smaller size.

[0026] Preferably, one side of the first fixing frame is fixedly installed with a fixing column, and the fixing column is located above the strip-shaped plate.

[0027] Preferably, one side of the first fixing frame is provided with a plugging slot, and the first fixing frame is sleeved on the headband main body through the plugging slot.

[0028] Preferably, the positioning mechanism includes a connecting column fixedly installed on one side of the metal arm, a pawl is rotatably installed on the outer side wall of the connecting column, a ratchet wheel is fixedly installed on the outer side wall of the T-shaped knob, and one end of the pawl is engaged with the ratchet wheel;

[0029] A second spring is fixedly installed on the inner top wall of the metal arm, a trapezoidal pressing block is fixedly installed at the bottom of the second spring, and the trapezoidal pressing block is in contact with the pawl.

[0030] The working principle and beneficial effects of the present invention are as follows:

[0031] 1. Wear the device on the patient's head through the headband main body, and then with the cooperation of the fixing component, the plugging hole, the T-shaped knob and the positioning mechanism, the height and angle of the upper and lower jaw support frames of the metal arm can be adjusted, so that the lower jaw support frame can fit the mandible and support the mandible. At the same time, with the cooperation of the clamping mechanism, the elastic clip and the spreader, the patient's mouth can be opened, thereby maintaining the patency of the patient's airway, avoiding the anesthesiologist from manually holding the mandible for a long time, and quickly establishing an airway during first aid to reduce the risk of asphyxia.

[0032] 2. Through the pasting mechanism and the sponge pad, the pressure of the headband main body on the head can be effectively dispersed, reducing the discomfort caused by long-term wearing. At the same time, the sponge pad can be detached and cleaned, ensuring hygiene and extending the service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The following further describes the present invention in detail with reference to the drawings and specific embodiments.

[0034] Figure 1 is the overall structural schematic diagram proposed by the present invention;

[0035] Figure 2 is the structural schematic diagram of the headband main body proposed by the present invention;

[0036] Figure 3 is the structural schematic diagram of the T-shaped knob proposed by the present invention;

[0037] Figure 4Schematic cross-sectional structure diagram of the first fixing frame proposed by the present invention;

[0038] Figure 5 Schematic structure diagram of the insertion slot proposed by the present invention;

[0039] Figure 6 Schematic cross-sectional structure diagram of the metal arm proposed by the present invention;

[0040] Figure 7 Schematic structure diagram of the jaw clamp proposed by the present invention;

[0041] Figure 8 Proposed by the present invention Figure 7 Enlarged structure diagram of part A in

[0042] In the figure: 1. Headband main body; 011. Headband strip; 012. Second fixing frame; 013. First hand-tightening screw;

[0043] 2. First fixing frame; 3. Metal arm; 4. Insertion hole;

[0044] 5. Fixing component; 51. T-shaped rod; 52. First spring;

[0045] 6. Mandibular support frame; 7. Elastic clip; 8. Spreader; 9. T-shaped knob; 10. Sponge pad; 11. Hook surface of Velcro; 12. Fuzzy surface of Velcro; 13. Strip-shaped plate; 14. Fixed column; 15. Insertion slot; 16. Ratchet; 17. Connecting column; 18. Pawl; 19. Second spring; 20. Trapezoidal pressing block; 21. Fixed plate; 22. Fixed rod; 23. Jaw clamp; 24. Rigid clamp; 25. Lead screw; 26. Connecting block; 27. Connecting plate; 28. Inverted T-shaped rod. Detailed implementation method

[0046] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0047] Embodiment 1

[0048] Please refer to Figure 1 - Figure 8 , a multi-directionally adjustable oral support mechanism in the mandibular protrusion position, including:

[0049] A headband main body 1 worn on the head;

[0050] Two first fixing frames 2 symmetrically installed on the headband main body 1;

[0051] The metal arm 3 inserted inside the first fixing frame 2;

[0052] Multiple insertion holes 4 opened on the metal arm 3, and the multiple insertion holes 4 are arranged in sequence from top to bottom;

[0053] The fixing component 5 arranged on the first fixing frame 2, and one end of the fixing component 5 is inserted into one of the insertion holes 4, which is used to lock the metal arm 3 with adjusted height inside the first fixing frame 2;

[0054] The mandibular support frame 6 inserted at the bottom of the metal arm 3;

[0055] The elastic clip 7 fixedly installed on the front side of the mandibular support frame 6;

[0056] The retractor 8 clamped inside the elastic clip 7;

[0057] And the T-shaped knob 9 rotatably installed on the metal arm 3, and the mandibular support frame 6 is fixedly installed on the T-shaped knob 9;

[0058] Wherein a positioning mechanism is arranged on the metal arm 3, and the positioning mechanism is in contact with the T-shaped knob 9;

[0059] A strip-shaped groove is opened at a position of the mandibular support frame 6 close to the end, an inverted T-shaped rod 28 is inserted into the strip-shaped groove, a fixing plate 21 is fixedly installed at the top of the inverted T-shaped rod 28, and a clamping mechanism is arranged at the top of the fixing plate 21.

[0060] When using a multi-directionally adjustable oral support mechanism in the mandibular protrusion position provided by the present invention, the headband main body 1 is worn on the patient's head, then the fixing component 5 is manually pulled, and one end of it is moved away from the metal arm 3, so that the height of the mandibular support frame 6 can be adjusted. After the adjustment is completed, the fixing component 5 is manually inserted into the insertion hole 4 again, so that the adjusted metal arm 3 and the mandibular support frame 6 can be fixed. Then, the retractor 8 on the elastic clip 7 can open the patient's mouth corners. Then, the clamping mechanism is manually pushed forward or backward, so that it can move back and forth under the action of the strip-shaped groove, the inverted T-shaped rod 28 and the fixing plate 21, and then the clamping mechanism can clamp the patient's posterior teeth or anterior teeth according to the situation. After the clamping is completed, the T-shaped knob 9 is manually rotated, so that it can drive the mandibular support frame 6 to move, and then, with the cooperation of the clamping mechanism, it can drive the patient's mandible to open and support the mandible. Finally, through the positioning mechanism, the adjusted mandibular support frame 6 can be fixed. On the contrary, the positioning mechanism is manually pressed down, so that the mandibular support frame 6 can be reset, and then the patient's airway can be kept unobstructed, avoiding the anesthesiologist from manually holding the mandible for a long time, and quickly establishing an airway during first aid, reducing the risk of asphyxia.

[0061] Furthermore, the headband body 1 includes a headband strip 011, and both of the two first fixing frames 2 are sleeved on the headband strip 011;

[0062] A second fixing frame 012 is fixedly installed at a position near the end of one side of the headband strip 011, and one end of the headband strip 011 away from the second fixing frame 012 is inserted into the second fixing frame 012;

[0063] A first hand-tightening screw 013 is threadedly connected to the second fixing frame 012, and the screw end of the first hand-tightening screw 013 abuts against the headband strip 011 inserted into the inner side of the second fixing frame 012.

[0064] Specifically, by manually reversing the first hand-tightening screw 013 and making its screw end away from the contacting headband strip 011, the size of the headband strip 011 can be adjusted. After the adjustment is completed, the first hand-tightening screw 013 is rotated forward, and its screw end tightly abuts against the headband strip 011, so as to fix the adjusted headband strip 011, and then patients with different head circumferences can use the device.

[0065] Furthermore, the clamping mechanism includes a fixing rod 22 fixedly installed on the top of the fixing plate 21. Two clamping jaws 23 are rotatably installed on the outer side wall of the fixing rod 22. A rigid clamp 24 is fixedly installed at one end of the two clamping jaws 23 together;

[0066] A lead screw 25 is rotatably installed on one side of the fixing plate 21. A connecting block 26 is threadedly connected to the outer side wall of the lead screw 25. Connecting plates 27 are pin-connected to both sides of the connecting block 26. The other ends of the two connecting plates 27 are respectively pin-connected to the two clamping jaws 23.

[0067] Specifically, by manually rotating the disc at one end of the lead screw 25, the lead screw 25 can be rotated. Then, the rotating lead screw 25 drives the connecting block 26 threaded thereon. When the connecting block 26 moves, the clamping jaws 23 rotatably installed on the fixing rod 22 can be pushed through the connecting plates 27, so that the end of the clamping jaw 23 away from the lead screw 25 can drive the rigid clamp 24 to clamp the patient's teeth.

[0068] Furthermore, the fixing assembly 5 includes a T-shaped rod 51 penetrating through the first fixing frame 2, and the larger-sized end of the T-shaped rod 51 is inserted into the insertion hole 4. A first spring 52 is sleeved on the T-shaped rod 51, and the first spring 52 is located between the first fixing frame 2 and the larger-sized end of the T-shaped rod 51.

[0069] Specifically, the elastic force of the first spring 52 pushes the T-shaped rod 51, and one end of it is inserted into the parallel insertion hole 4, so as to fix the metal arm 3 and the mandibular support frame 6 after the height adjustment is completed.

[0070] Further, one end of the T-shaped rod 51 is fixedly installed with a strip-shaped plate 13, and the strip-shaped plate 13 is located on the end of the T-shaped rod 51 with a smaller size.

[0071] Specifically, through the strip-shaped plate 13, it is convenient for manual pulling of the T-shaped rod 51, and further convenient for adjusting the heights of the metal arm 3 and the mandibular support frame 6.

[0072] Further, one side of the first fixing frame 2 is fixedly installed with a fixing column 14, and the fixing column 14 is located above the strip-shaped plate 13.

[0073] Specifically, when the position of the strip-shaped plate 13 pulled manually exceeds the fixing column 14, the strip-shaped plate 13 is rotated 180 degrees manually, and then the strip-shaped plate 13 is released manually, so that the strip-shaped plate 13 can tightly contact the fixing column 14 under the action of the first spring 52, and further the T-shaped rod 51 can be limited, so that the T-shaped rod 51 will not be inserted into the insertion hole 4, which can free the doctor's hands and make it convenient for the doctor to adjust the heights of the metal arm 3 and the mandibular support frame 6.

[0074] Further, one side of the first fixing frame 2 is provided with an insertion slot 15, and the first fixing frame 2 is sleeved on the headband main body 1 through the insertion slot 15.

[0075] Specifically, through the insertion slot 15 on the first fixing frame 2, when the size of the headband main body 1 is adjusted, the position of the first fixing frame 2 can also be adjusted.

[0076] Further, the positioning mechanism includes a connecting column 17 fixedly installed on one side of the metal arm 3. A pawl 18 is rotatably installed on the outer side wall of the connecting column 17. A ratchet wheel 16 is fixedly installed on the outer side wall of the T-shaped knob 9, and one end of the pawl 18 is engaged with the ratchet wheel 16;

[0077] A second spring 19 is fixedly installed on the inner top wall of the metal arm 3. The bottom of the second spring 19 is fixedly installed with a trapezoidal pressing block 20, and the trapezoidal pressing block 20 is in contact with the pawl 18.

[0078] Specifically, when the T-shaped knob 9 is rotated manually to drive the mandibular support frame 6 to rotate, the T-shaped knob 9 synchronously drives the ratchet wheel 16 to rotate. During the rotation, through the second spring 19 and the trapezoidal pressing block 20, one end of the pawl 18 can always contact the ratchet wheel 16, so that under the action of the pawl 18, the adjusted T-shaped knob 9 and the mandibular support frame 6 can be positioned to prevent the opened mandibular support frame 6 from resetting. After use, by manually pressing the exposed end of the pawl 18 downward, the other end of the pawl 18 is far away from the ratchet wheel 16, and further the mandibular support frame 6 can be rotated for resetting.

[0079] Embodiment 2

[0080] Based on the first embodiment, in this embodiment: a sponge pad 10 is provided on the inner side of the headband body 1, a bonding mechanism is provided on one side of the sponge pad 10, and the sponge pad 10 is fixed to the inner side of the headband body 1 by the bonding mechanism.

[0081] The technical solution provided by this embodiment is: the sponge pad 10 is fixed by a bonding mechanism on the inner side of the headband body 1, so as to effectively disperse the pressure of the headband body 1 on the head, thereby reducing the discomfort caused by wearing the headband body 1 for a long time.

[0082] Furthermore, the sticking mechanism includes a Velcro hook surface 11 fixedly installed on one side of the sponge pad 10, a Velcro fleece surface 12 is fixedly installed on the inner side of the headband body 1, and the sponge pad 10 is respectively stuck to the Velcro fleece surface 12 and the headband body 1 through the Velcro hook surface 11.

[0083] Specifically, through the Velcro hook surface 11 and the Velcro fleece surface 12, the sponge pad 10 can be fixedly mounted on the headband body 1 for protection during use, and the sponge pad 10 can be disassembled and cleaned, thereby ensuring hygiene and cleanliness and extending the service life of the product.

[0084] The working principle and use process of the present invention are as follows: when in use, according to the patient's head circumference, the first hand screw 013 is reversed to make the screw end away from the contacted headband strip 011, so that the size of the headband strip 011 can be adjusted. After adjustment, the first hand screw 013 is turned forward to fix the headband strip 011, and then the headband strip 011 is worn on the patient's head. After that, the T-shaped rod 51 is manually pulled away from the plug-in hole 4 through the strip plate 13, so that the height of the mandibular support frame 6 can be adjusted. After completion, under the action of the first spring 52, the T-shaped rod 51 is reinserted into the parallel plug-in hole 4, so that the mandibular support frame 6 is fixed;

[0085] Then, the screw rod 25 is manually rotated to drive the connecting block 26 threaded thereon, so that the connecting block 26 can push the rotating claw 23 on the fixing rod 22 through the connecting plate 27 while moving, so that the end of the claw 23 away from the screw rod 25 can drive the rigid clamp 24 to clamp the patient's teeth, and then the T-shaped knob 9 is manually rotated to drive the mandibular support frame 6 to move, and then drive the mandible to open and support the mandible. After the adjustment is completed, the pawl 18 is pressed by the second spring 19 and the trapezoidal pressure block 20, so that one end of the pawl 18 is against the ratchet 16, so that the adjusted mandibular support frame 6 can be fixed, thereby avoiding the anesthesiologist from manually lifting the mandible for a long time, and quickly establishing an airway during emergency treatment to reduce the risk of suffocation.

[0086] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-directional adjustable oral support mechanism for mandibular protrusion, characterized in that: include: A headband body (1) worn on the head; Two first fixing frames (2) symmetrically mounted on the headband body (1); A metal arm (3) inserted into the inner side of the first fixing frame (2); A plurality of plug holes (4) are provided on the metal arm (3), and the plurality of plug holes (4) are arranged in sequence from top to bottom; a fixing component (5) arranged on the first fixing frame (2), one end of the fixing component (5) being plugged into one of the plug holes (4) to lock the metal arm (3) whose height has been adjusted in the first fixing frame (2); A mandibular support frame (6) inserted into the bottom of the metal arm (3); An elastic clip (7) fixedly mounted on the front side of the mandibular support frame (6); a spreader (8) clamped inside the elastic clip (7); and a T-shaped knob (9) rotatably mounted on the metal arm (3), and the mandibular support frame (6) is fixedly mounted on the T-shaped knob (9); A positioning mechanism is provided on the metal arm (3), and the positioning mechanism is in contact with the T-shaped knob (9); A strip groove is provided near the end of the mandibular support frame (6), an inverted T-bar (28) is inserted into the strip groove, a fixing plate (21) is fixedly installed on the top of the inverted T-bar (28), and a clamping mechanism is provided on the top of the fixing plate (21).

2. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 1, characterized in that: A sponge pad (10) is arranged on the inner side of the headband body (1), a bonding mechanism is arranged on one side of the sponge pad (10), and the sponge pad (10) is fixed to the inner side of the headband body (1) by the bonding mechanism.

3. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 2, characterized in that: The sticking mechanism comprises a Velcro hook surface (11) fixedly mounted on one side of the sponge pad (10), a Velcro fleece surface (12) fixedly mounted on the inner side of the headband body (1), and the sponge pad (10) is respectively stuck to the Velcro fleece surface (12) and the headband body (1) via the Velcro hook surface (11).

4. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 1, characterized in that: The headband body (1) comprises a headband strip (011), and the two first fixing frames (2) are both sleeved on the headband strip (011); A second fixing frame (012) is fixedly installed at a position close to the end of one side of the headband strip (011), and an end of the headband strip (011) away from the second fixing frame (012) is plugged into the second fixing frame (012); The second fixing frame (012) is threadedly connected with a first hand screw (013), and the screw end of the first hand screw (013) is in conflict with the headband strip (011) inserted into the inner side of the second fixing frame (012).

5. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 1, characterized in that: The clamping mechanism comprises a fixing rod (22) fixedly mounted on the top of the fixing plate (21), two clamping claws (23) being rotatably mounted on the outer side wall of the fixing rod (22), and a rigid clamp (24) being fixedly mounted on one end of the two clamping claws (23); A screw rod (25) is rotatably mounted on one side of the fixing plate (21), a connecting block (26) is threadedly connected to the outer wall of the screw rod (25), connecting plates (27) are pin-connected to both sides of the connecting block (26), and the other ends of the two connecting plates (27) are pin-connected to the two clamping jaws (23) respectively.

6. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 1, characterized in that: The fixing assembly (5) comprises a T-shaped rod (51) penetrating the first fixing frame (2), and the larger end of the T-shaped rod (51) is plugged into the plug hole (4); a first spring (52) is sleeved on the T-shaped rod (51), and the first spring (52) is located between the first fixing frame (2) and the larger end of the T-shaped rod (51).

7. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 6, characterized in that: A strip plate (13) is fixedly mounted on one end of the T-shaped rod (51), and the strip plate (13) is located on the end of the T-shaped rod (51) with a smaller size.

8. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 7, characterized in that: A fixing column (14) is fixedly mounted on one side of the first fixing frame (2), and the fixing column (14) is located above the strip plate (13).

9. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 1, characterized in that: A plug-in slot (15) is provided on one side of the first fixing frame (2), and the first fixing frame (2) is sleeved on the headband body (1) through the plug-in slot (15).

10. The multi-directional adjustable oral support mechanism for mandibular protrusion according to claim 1, characterized in that: The positioning mechanism comprises a connecting column (17) fixedly mounted on one side of the metal arm (3), a ratchet (18) rotatably mounted on the outer wall of the connecting column (17), a ratchet (16) fixedly mounted on the outer wall of the T-shaped knob (9), and one end of the ratchet (18) meshes with the ratchet (16); A second spring (19) is fixedly mounted on the inner top wall of the metal arm (3), a trapezoidal pressing block (20) is fixedly mounted on the bottom of the second spring (19), and the trapezoidal pressing block (20) is in contact with the ratchet (18).

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