A new subcutaneous retractor

Abstract

A novel subcutaneous traction device includes a locking device and a penetrating pull rod. The locking device includes a locking block, a locking cylinder, and an elastic element. The locking cylinder includes a bolt and an unlocking arm connected to and extending outward therefrom. The bolt has a locking lug. The locking block includes a lock housing defined by a proximal end, a distal end, and a side end. The lock housing has a lock cavity inside, which includes a cavity proximal end and a cavity distal end. A main lock hole penetrates the cavity proximal end through the cavity proximal end and communicates with the lock cavity to form a proximal lock hole. The main lock hole penetrates the cavity distal end and extends to the distal end face to form a distal lock hole. A side lock hole extends laterally relative to the main lock hole, penetrates the side lock face, and communicates with the lock cavity. The locking cylinder is installed inside the locking block, its bolt is installed in the lock cavity, the unlocking arm is installed in the side lock hole and extends beyond the outside of the locking block, and the pull rod is inserted through the main lock hole. The elastic element is installed between the side wall of the lock cavity and the bolt and is in a compressed state. The restoring force pushes the bolt to keep the locking lug and the ring groove engaged to form an engagement pair, thereby preventing the pull rod from disengaging from the locking block.

Description

Technical Field

[0001] This invention relates to surgical instruments, and more particularly to a minimally invasive surgical instrument. Background Technology

[0002] Subcutaneous organ resections or tumor resections, such as thyroidectomy, mastectomy, parotid gland resection, and gasless endoscopic surgery, often involve making a large incision in the patient's skin. A traction device is used to open the incision, exposing the internal tissue and creating surgical space. This results in significant scarring for the patient. A transfer incision technique allows for a small incision at a suitable location on the patient, creating a subcutaneous channel directly to the lesion for surgery. Transfer incision techniques face two challenges: first, how to create a local subcutaneous cavity at the lesion site to create subcutaneous surgical space? Second, since transfer incisions typically only open a single channel, how can video monitoring and the collaboration of two or more instruments be achieved within this single channel to dissect tissue and expose the lesion? Minimally invasive transfer incision techniques are already in clinical use, but currently, there are no suitable instruments to solve the first two problems. Utility Model Content

[0003] Therefore, in order to solve the problems of existing technologies, a variety of solutions have been proposed.

[0004] In one aspect of the invention, a novel subcutaneous traction device is provided, comprising a locking device and a penetrating lever. The locking device includes a locking block, a locking cylinder, and an elastic element. The locking cylinder includes a bolt and an unlocking arm connected thereto and extending outwardly, the bolt having a locking lug. The locking block includes a lock housing defined by a lock proximal end, a lock distal end, and a lock side surface. The lock housing has a lock cavity inside, the lock cavity including a cavity proximal end and a cavity distal end. A lock master hole extends from the lock proximal end through the cavity proximal end and communicates with the lock cavity to form a proximal lock hole; the lock master hole penetrates the cavity distal end and extends to the lock distal end face to form a distal lock hole; a lock side hole extends laterally relative to the lock master hole through the lock side surface and communicates with the lock cavity. The lever includes a proximal lever handle, a distal inclined lever tip, and a lever bar extending therebetween. An annular groove is provided in the region adjacent to the tip, the annular groove including an annular groove proximal end, an annular groove distal end, and a locking cylinder bar. The lock cylinder is installed inside the lock block, its bolt is installed in the lock cavity, the unlocking arm is installed in the lock side hole and extends beyond the outside of the lock block, the pull rod is inserted through the lock main hole, the elastic element is installed between the side wall of the lock cavity and the bolt and is in a compressed state, its restoring force pushes the bolt to keep the lock opening and the ring groove engaged to form an engagement pair, thereby preventing the pull rod from coming out of the lock block.

[0005] In one embodiment, the puller includes a locked state and an unlocked state: in the locked state, the unlocking arm extends beyond the lock block through the lock side hole, the elastic element is in a compressed state, and its restoring force pushes the lock opening and the ring groove to maintain mutual engagement to form an engagement pair, thereby restricting the pull rod from disengaging from the lock block; in the unlocked state, applying external force to the unlocking arm can continue to compress the elastic element, causing the lock opening to disengage from the ring groove, thereby allowing the pull rod to disengage from the lock block.

[0006] In another embodiment, the lock cylinder includes a first convex slide rail and a second convex slide rail, and the lock block includes a first concave slide rail and a second concave slide rail. The first concave slide rail and the first convex slide rail are matched to form a sliding bearing, and the second concave slide rail and the second convex slide rail are matched to form a second sliding bearing.

[0007] In another embodiment, the feature is that it further includes a lock side cover, which is embedded in the lock cavity entrance and is interference-fitted, welded or bonded to the lock housing.

[0008] In another embodiment, the diameter D1 of the proximal lock hole, the projection plane profile of the lock block along the axial projection direction of the proximal lock hole includes the minimum circumcircle D2, where D2≥3×D1, and 0.8mm≤D1≤2.6mm.

[0009] In another embodiment, the lock case includes a lock cover and a lock handle. The lateral dimension of the lock cover is B1, and the lateral dimension of the lock handle is B2, wherein B1 > B2, forming an outer extension cover for installing an unlocking arm with a lock side hole located below the outer extension cover.

[0010] In another embodiment, the lock opening includes a first U-shaped lock opening and a second U-shaped lock opening, wherein the first and second U-shaped lock openings constitute a closed irregular ring lock opening.

[0011] In another embodiment, the diameter of the pull rod is D5, the diameter of the lock cylinder is D6, and the length of the unlocking arm protruding outside the lock block in the locked state is L3, where L3 > 0.5 × (D5 - D6).

[0012] In another embodiment, the first U-shaped lock opening includes an arc-shaped lock opening with a radius of R1, where 0.5×D5<R1<0.5×D6.

[0013] In another embodiment, the second U-shaped lock opening includes an arc-shaped lock opening with a radius of R2, where R2 > 0.5 × D5, and the distance between the centers of the two arcs is L2 > 0.5 × (D5 - D6). Attached Figure Description

[0014] To gain a fuller understanding of the essence of the present invention, a detailed description will be provided below in conjunction with the accompanying drawings, wherein: Figure 1 This is a 3D schematic diagram of traction device 1; Figure 2 This is a schematic diagram of the explosion of puller 1; Figure 3 This is a 3D schematic diagram of lock cylinder 30; Figure 4 yes Figure 3 Sectional view 4-4; Figure 5 This is a 3D schematic diagram of lock block 20; Figure 6 This is a side projection view of lock block 20; Figure 7 This is a projection view of the locking block 20 from the near end to the far end; Figure 8 yes Figure 7 Sectional view 8-8; Figure 9 This is a side projection view of the pull rod 10; Figure 10 This is a partial 3D schematic diagram of the distal end of the traction device 1 in the locked state (locking block 20 is partially cut open). Figure 11 This is a partial 3D schematic diagram of the distal end of the puller 1 in the unlocked state (lock block 20 is partially cut open). Figure 12 This is a 3D schematic diagram of the 20a lock cylinder. Figure 13 This is a projection view of the lock cylinder 20a from the near end to the far end; Figure 14 It is a projection view of the lock block 20a from the near end to the far end; Figure 15 This is a side projection view of lock block 20a; Figure 16 yes Figure 14 Sectional view 16-16; Figure 17 This is a 3D schematic diagram of lock block 20a; Figure 18 This is a 3D schematic diagram of the lock 2a (a partial cut-out of the lock block 20a). Figure 19 This is an exploded schematic diagram of the lock side cover 40 of the locker 2a; Figure 20 This is a schematic diagram of the fixing of the lock side cover 40 of the locker 2a; Figure 21 This is a partial side projection view of the distal end of traction device 1a; Figure 22 yes Figure 21 Sectional view 22-22 Figure 23 yes Figure 21 Sectional view 23-23; Figure 24 yes Figure 23 Schematic diagram of unlocking displacement; In all views, the same label indicates the same part or component. Detailed Implementation

[0015] Embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the invention, and the invention can be implemented in different ways. Therefore, the disclosure herein is not to be construed as limiting, but rather serves only as the basis for the claims and as a means of teaching those skilled in the art how to use the invention. For ease of description, the side closer to the operator will be defined as the proximal end, and the side farther from the operator will be defined as the distal end.

[0016] Figures 1-2 A subcutaneous traction device 1 is described, comprising a locking device 2 and a penetrating lever 10. For example... Figure 2-3 The locking device 2 includes a locking block 20, a locking cylinder 30, and an elastic element 9.

[0017] Figures 3-4 The structure and composition of a lock cylinder 30 are described. The lock cylinder 30 includes a bolt 310 and an unlocking arm 320 connected to and extending outward therefrom. The bolt 310 has a locking port 330. The locking port 330 includes a first U-shaped locking port 331 and a second U-shaped locking port 332, which form a closed annular locking port. In one design, the proximal end of the locking port 330 includes an inclined guide lip 333. In another design, the first U-shaped locking port 331 includes an arc-shaped locking port with a radius of R1, and the second U-shaped locking port 332 includes an arc-shaped locking port with a radius of R2.

[0018] Figures 5-8 The structure and composition of the lock block 20 are described. The lock block 20 includes a lock housing 210 defined by a lock proximal end face 211, a lock distal end face 212, and a lock side face 213. The lock housing 210 has a lock cavity 220 inside, which includes a cavity proximal end 221 and a cavity distal end 222. A lock main hole 230 extends from the lock proximal end face 211 through the cavity proximal end 221 and communicates with the lock cavity 220 to form a proximal lock hole 231. The lock main hole 230 penetrates the cavity distal end 222 and extends to the adjacent area of ​​the lock distal end face 212 or penetrates the lock distal end face 212 to form a distal lock hole 233. A lock side hole 227 extends laterally relative to the lock main hole 230, penetrates the lock side face 213, and communicates with the lock cavity 220.

[0019] Figure 9The structure and composition of the pull rod 10 are described. The pull rod 10 includes a proximal pull rod handle 11, a distal inclined pull rod tip 19, and a pull rod bar 12 with a diameter of D6 extending therebetween; the area adjacent to the tip 19 is provided with an annular groove 18, the annular groove 18 including an annular groove proximal end 15, an annular groove distal end 16, and a lock cylinder bar 17 with a diameter of D7.

[0020] Figure 10 The cooperation relationship between the locking device 2 and the puller 1 is depicted. The lock cylinder 30 is installed inside the lock block 20, wherein the bolt 310 is installed in the lock cavity 220, and the unlocking arm 320 is installed in the lock side hole 227 and extends beyond the outside of the lock block 20. The elastic member 9 is installed between the side wall of the lock cavity 220 and the bolt 310 and is in a compressed state. Its restoring force pushes the bolt 310 toward the lock main hole 230.

[0021] Figure 10 A schematic diagram of the engagement of the puller 1 in the locked state is depicted. The pull rod 12 is inserted through the proximal lock hole 231, wherein the tip 19 presses against the lock opening 330, forcing the elastic element 9 to be further compressed, pushing the bolt 310 to move away from the main lock hole 230; when the annular groove 18 is fully inserted into the lock cavity 220, the spring restoring force pushes the bolt 310 to move towards the main lock hole 230, so that the lock opening 330 is inserted into the annular groove 18, and the restoring force of the elastic element pushes the bolt 310 to keep the lock opening 330 and the annular groove 18 engaged to form an engagement pair, thereby preventing the pull rod 12 from disengaging from the locker 2.

[0022] Figure 10 A schematic diagram of the engagement of the puller 1 in the unlocked state is depicted. An external force is applied to the unlocking arm 320 to compress the elastic element 9, pushing the bolt 310 to move away from the main lock hole 230, causing the lock jaw 330 to disengage from the annular groove 18, thereby allowing the pull rod 12 to disengage from the locker 2.

[0023] The method of using traction device 1 for subcutaneous cavity creation is roughly as follows: Channel establishment: An incision is made at an appropriate location on the patient's epidermis, and under the guidance of an endoscope, an energy device is used to separate the tissue to establish a subcutaneous channel to the area adjacent to the lesion; Insert the locking device: Use clamps to hold the locking device and advance it along the subcutaneous channel to the intended use position in the lesion area; Assembly of the pull rod: From the outside of the skin at the intended use location, pierce the skin with the penetrating pull rod (or use instruments to assist in piercing), and under the video guidance of the endoscope, insert the pull rod through the proximal locking hole of the lock and make the locking jaw and the ring groove interlock to form an engagement pair; Usage: Pull the proximal end of the lever manually or use an external stent to pull and fix the proximal end of the lever, thereby pulling the lock and moving the surrounding human tissue to form a local cavity (local surgical working cavity). Removal: Under endoscopic guidance, clamps are inserted through the subcutaneous channel and applied external force to compress the elastic element of the unlocking arm, causing the lock to disengage from the ring groove. The lever is then pulled out externally, and the clamps are used to hold the locking device and remove it through the subcutaneous channel. The clamps can be surgical forceps commonly used in minimally invasive surgery, such as the surgical instruments disclosed in Chinese Invention Application 202411443156.7. They can also be long, thin forceps.

[0024] Those skilled in the art should understand that, to date, the trocars used in laparoscopic minimally invasive surgery mainly include the 3, 5, 8, 10, 11, 12, and 15 mm series. The numbers represent the nominal inner diameter of the trocar, not its outer diameter. A 3 mm trocar has an inner diameter of approximately 3.5–3.9 mm and an outer diameter of approximately 5.5–6.0 mm; a 5 mm trocar has an inner diameter of approximately 5.5–5.9 mm and an outer diameter of approximately 7.5–8.0 mm. Studies have shown that incisions of 5 mm or larger will result in significant scarring on the patient's skin.

[0025] like Figure 6 , Figure 7 and Figure 8 In another embodiment, the diameter D1 of the near-end locking hole 231 is such that the planar profile of the locking block 20 projected along the axial direction of the hole 231 includes a minimum circumscribed circle D2, where D2 ≥ 3 × D1, and 0.8 mm ≤ D1 ≤ 2.6 mm. In yet another preferred embodiment, 0.8 mm ≤ D1 ≤ 1.6 mm. In yet another design embodiment, the locking block 20 is projected along any direction perpendicular to the axial direction of the hole 231, and its planar profile includes a minimum circumscribed circle D3, where D3 ≥ D2 ≥ 3 × D1.

[0026] like Figure 9 In another design, the diameter of the pull rod 12 is D5, and the diameter of the lock cylinder rod 17 is D6, where 0.7mm ≤ D5 ≤ 2.5mm, and the length of the pull rod L1 ≥ 100mm. This size design facilitates recovery after the pull rod penetrates the patient's skin during surgery without leaving significant scars, while ensuring a secure fit between the pull rod and the lock cylinder. In another preferred design, 0.7mm ≤ D5 ≤ 1.5mm, this design results in even less trauma.

[0027] like Figure 5 , Figure 6 and Figure 8In another embodiment, the lock housing 210 includes a lock cover 214a and a lock handle 214b. The lateral dimension of the lock cover 214a is B1, and the lateral dimension of the lock handle 214b is B2, where B1 > B2, forming an outer extension cover 214c. A side hole 227 for installing the unlocking arm strap is located below the outer extension cover 214c. In yet another design, the thickness dimension of the lock cover 214a is H1, and the thickness dimension of the lock handle 214b is H2, where H1 < H2. This design simplifies the structure and facilitates the insertion and exit of the lock block through a subcutaneous or puncture channel into the patient's body.

[0028] Figures 12-24 Another puller 1a is depicted, comprising a through pull rod 10 and a locking device 2a. The locking device 2a includes a locking block 20a, a lock cylinder 30a, and an elastic element 9.

[0029] like Figures 12-13 The lock cylinder 30a includes a bolt 310 and an unlocking arm 320 connected to and extending outward therefrom. The bolt 310 includes a proximal end face 311, a distal end face 312, and a first convex slide rail 313 and a second convex slide rail 314 disposed on both sides. A locking port 330 penetrates the faces 311 and 312. The locking port 330 includes a first U-shaped locking port 331 and a second U-shaped locking port 332, the first and second U-shaped locking ports forming a closed irregular ring locking port. The proximal end of the locking port 330 includes an inclined guide lip 333.

[0030] like Figures 4-7 The lock block 20a includes a lock housing 210 defined by a lock proximal end face 211, a lock distal end face 212, and a lock side face 213. The lock housing 210 has a lock cavity 220, which includes a cavity proximal end 221, a cavity distal end 222, and a first concave slide rail 223 and a second concave slide rail 224 disposed on both sides. One end of the lock cavity 220 penetrates the lock side face 213 to form a lock cavity entrance 225, while the other end extends laterally into the lock housing to the cavity bottom surface 226. A lock side hole 227 penetrates the lock side face 213 and the lock cavity bottom surface 226 and communicates with the lock cavity 220. A lock main hole 230 penetrates the lock proximal end face 211 and the cavity proximal end 221 and communicates with the lock cavity 220 to form a lock proximal end hole 231, which includes a proximal end guide hole 232. The main lock hole 230 extends through the distal end 222 of the cavity and the distal lock end face 212 to form the distal lock end hole 233.

[0031] In one design, the lock cavity 220 further includes a drive chamber 228 disposed at the lock cavity entrance 225. The maximum dimension of the chamber 228 along the axial direction of the lock main hole 230 is greater than or equal to the distance between the proximal end 221 and the distal end 222 of the cavity. This arrangement facilitates the precise positioning of the elastic element, thereby enabling precise control of the direction of the elastic force.

[0032] like Figure 17In one embodiment, the junction area between the lock side surface 213 and the lock cavity entrance 225 further includes an outwardly protruding lip 241. After shaping and polishing, the outwardly protruding lip 241 can be deformed to form an inner extension arm 242 to prevent the elastic element from dislodging out of the lock cavity 220.

[0033] like Figure 18 The lock cylinder 30a is installed in the lock cavity 220 of the lock block 20a. Its first convex slide rail 313 matches the first concave slide rail 223, and its second convex slide rail 314 matches the second concave slide rail 224. The proximal end face 311 of the cylinder matches the proximal end 221 of the cavity, and the distal end face 312 of the cylinder matches the distal end 222 of the cavity. Its unlocking arm 320 extends to the outside of the lock block 20a through the lock side hole 227. The elastic element 9 is installed between the lock cylinder 30a and the cavity extension arm 242 and is in a compressed state. Its restoring force drives the first U-shaped lock opening 331 of the lock cylinder 30a to move towards the main lock hole. To intuitively illustrate its mating relationship, Figure 18 The locking block 20a in the middle is cut open, and can be combined Figures 14-16 Understand their cooperative relationship.

[0034] like Figures 19-20 In one embodiment, the locking device 2a further includes a lock side cover 40, which is installed at the lock cavity inlet 225 and fixed together with the locking block 20a. Interference fitting, welding, bonding, and other processes can be used. Those skilled in the art will readily understand that when the lock side cover is used to fix the elastic element, the locking block 20a may or may not include the inner extension arm 242.

[0035] Figures 21-23 The structure and assembly relationship of the puller 1a are depicted. The 1a includes a locking device 2a and a through-rod 10. Figure 23 The puller 1a in the locked state is depicted. The pull rod 12 is inserted through the main lock hole 230, where the inclined tip 19 presses against the lock opening 330, forcing the elastic element 9 to be further compressed, pushing the bolt 310 to move away from the main lock hole 230; when the annular groove 18 is fully inserted into the lock cavity 220, the spring restoring force pushes the bolt 310 to move closer to the main lock hole 230, causing the first U-shaped lock opening 331 to engage in the annular groove 18; and the bolt 310 is clamped between the proximal end 221 and the distal end 222 of the cavity. At this time, pulling or pushing the pull rod along the axial direction of the pull rod 6, the restoring force of the elastic element pushes the bolt 310 to keep the first U-shaped lock opening 331 and the annular groove 18 engaged to form an engagement pair, thereby preventing the pull rod 12 from disengaging from the locker 2a.

[0036] Figure 24The puller 1a is depicted in the unlocked state. An external force is applied to the unlocking arm 320 to compress the elastic element 9, pushing the bolt 310 to move away from the main lock hole 230, so that the first U-shaped lock mouth 331 is completely disengaged from the annular groove 18, thereby allowing the pull rod 12 to disengage from the locker 2.

[0037] like Figure 21 In another embodiment, the diameter of the pull rod 11 is D5, the diameter of the lock cylinder 17 is D6, and in the locked state, the length of the unlocking arm 320 protruding outside the lock block 20 is L3, where L3 > 0.5 × (D5 - D6). This configuration is beneficial for achieving intracavitary unlocking under endoscopy.

[0038] like Figure 13 In another design, the first U-shaped lock opening 331 includes an arc-shaped lock opening with a radius of R1, where 0.5×D5 < R1 < 0.5×D6. The second U-shaped lock opening 332 includes an arc-shaped lock opening with a radius of R2, where R2 > 0.5×D5. The distance between the centers of the two arcs is L2 > 0.5×(D5-D6).

[0039] In the various embodiments described in this invention, each embodiment focuses on different features and their beneficial effects, which are interchangeable and can be combined in combination. Many variations have been shown, and more are conceivable, but will not be exhaustive here. Those skilled in the art will understand that the terms "first," "second," etc., are not in a strict order, but are used only for the sake of brevity and accuracy, and for ease of understanding.

Claims

1. A novel subcutaneous traction device, characterized in that: 1) Includes a locking mechanism and a through-bar; the locking mechanism includes a locking block, a lock cylinder, and a resilient element. 2) The lock cylinder includes a bolt and an unlocking arm connected thereto and extending outward, the bolt having a locking port; 3) The lock block includes a lock housing defined by a lock proximal end, a lock distal end, and a lock side surface. The lock housing has a lock cavity inside. The lock cavity includes a cavity proximal end and a cavity distal end. The lock main hole extends from the lock proximal end through the cavity proximal end and communicates with the lock cavity to form a proximal lock hole. The lock main hole penetrates the cavity distal end and extends to the lock distal end face to form a distal lock hole. The lock side hole extends laterally relative to the lock main hole, penetrates the lock side surface, and communicates with the lock cavity. 4) The pull rod includes a proximal pull rod handle, a distal inclined pull rod tip, and a pull rod bar extending therebetween. An annular groove is provided in the vicinity of the tip, and the annular groove includes a proximal end of the annular groove, a distal end of the annular groove, and a lock cylinder bar. 5) The lock cylinder is installed inside the lock block, its bolt is installed in the lock cavity, the unlocking arm is installed in the lock side hole and extends beyond the outside of the lock block, the pull rod is inserted through the lock main hole, the elastic element is installed between the side wall of the lock cavity and the bolt and is in a compressed state, its restoring force pushes the bolt to keep the lock opening and the ring groove engaged to form an engagement pair, thereby restricting the pull rod from coming out of the lock block.

2. The traction device as described in claim 1, characterized in that, Includes locked and unlocked states: 1) In the locked state, the unlocking arm extends beyond the lock block through the lock side hole, and the elastic element is in a compressed state. Its restoring force pushes the lock opening and the ring groove to maintain mutual engagement to form an engagement pair, thereby preventing the pull rod from coming out of the lock block; 2) In the unlocked state, applying external force to the unlocking arm can continue to compress the elastic element, causing the locking port to disengage from the ring groove, thereby allowing the pull rod to disengage from the lock block.

3. The traction device as described in claim 1, characterized in that, The lock cylinder includes a first convex slide rail and a second convex slide rail, and the lock block includes a first concave slide rail and a second concave slide rail. The first concave slide rail and the first convex slide rail are matched to form a sliding bearing, and the second concave slide rail and the second convex slide rail are matched to form a second sliding bearing.

4. The traction device as described in claim 3, characterized in that, It also includes a lock side cover, which is embedded in the lock cavity entrance and is press-fitted, welded or bonded to the lock housing.

5. The traction device as described in claim 1, characterized in that, The diameter D1 of the proximal lock hole, the lock block projection plane profile along the axial projection direction of the proximal lock hole includes the minimum circumcircle D2, where D2≥3*D1, and 0.8mm≤D1≤2.6mm.

6. The traction device as described in claim 1, characterized in that, The lock case includes a lock cover and a lock handle. The lateral dimension of the lock cover is B1, and the lateral dimension of the lock handle is B2, wherein B1 > B2, forming an outer extension cover for installing an unlocking arm. The lock side hole is located below the outer extension cover.

7. The traction device as described in claim 1, characterized in that, The lock opening includes a first U-shaped lock opening and a second U-shaped lock opening, and the first and second U-shaped lock openings form a closed irregular ring lock opening.

8. The traction device as described in claim 7, characterized in that, The diameter of the pull rod is D5, the diameter of the lock cylinder is D6, and the length of the unlocking arm protruding outside the lock block in the locked state is L3, where L3 > 0.5 * (D5 - D6).

9. The traction device as described in claim 8, characterized in that, The first U-shaped lock opening includes an arc-shaped lock opening with a radius of R1, where 0.5*D5 < R1 < 0.5*D6.

10. The traction device as described in claim 9, characterized in that, The second U-shaped lock includes an arc-shaped lock with a radius of R2, where R2 > 0.5 * D5, and the distance between the centers of the two arcs is L2 > 0.5 * (D5 - D6).

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