Adjustable bent sheath handle and adjustable bent sheath tube assembly

Abstract

The invention discloses an adjustable bent sheath handle and an adjustable bent sheath tube assembly, and belongs to the technical field of medical instruments. The handle comprises a handle shell, and a driving mechanism, a differential balance beam mechanism, a winding wheel mechanism and a constant tension module are arranged in the shell. The driving mechanism converts rotary input of the knob into linear reciprocating motion; the differential balance beam mechanism converts linear motion into swing around a fulcrum; the winding wheels are symmetrically arranged on the two sides of the balance beam, long groove driving rods on the winding wheels are in sliding fit with driving pins at the two ends of the balance beam, swing of the balance beam is converted into winding and unwinding reverse rotation of the winding wheels on the two sides, and therefore bending adjusting wires connected to the winding wheels are controlled. The constant tension module continuously applies constant winding direction torque to the winding wheels on the two sides, and it is ensured that the bending adjusting wire is kept in the tensioning state in the winding and unwinding processes. According to the invention, the control return difference and the idle stroke caused by looseness of the bending adjusting wire are effectively reduced, and the consistency, the response speed and the repeated positioning precision of the bidirectional bending adjusting operation are improved.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and specifically to an adjustable curved sheath handle. Background Technology

[0002] In transvascular interventional procedures, surgeons often need to deliver instruments such as guidewires, catheters, ablation catheters, or occluders through blood vessels to target sites such as the heart and peripheral blood vessels. Sheaths, as a crucial access tool, provide stable support for the delivery and exchange of these instruments.

[0003] When the target site is located in an area with complex anatomy or limited space, such as the auricle of the heart, the pulmonary vein orifice, or a vascular bifurcation, it is usually necessary to bend the distal end of the sheath to conform to the physiological anatomical path and stably adhere to the tissue. Traditional straight sheaths or pre-shaped fixed curved sheaths are insufficient to meet the need for flexible adjustments during surgery. Therefore, adjustable curved sheaths have been developed, which control the bending angle of the distal sheath by manipulating the proximal handle to pull or loosen one or more adjusting wires.

[0004] However, existing adjustable bending sheath handles still have some areas for improvement in practical applications. Typical drive structures often use two bending wires to control the bending direction separately. When bending in one direction, one bending wire is actively tightened, while the other is passively released. Due to the lack of an effective tensioning mechanism for the released bending wire, it is easy for the wire to slack during release. This slack causes two main problems: first, it creates a delay between the handle's input and the actual bending response at the distal end of the sheath, i.e., hysteresis; second, during reverse operation, the slack bending wire must first be tightened to drive the sheath to bend in the opposite direction, resulting in an ineffective idle stroke. Hysteresis and idle stroke reduce the precision and intuitiveness of the operation, affecting surgical efficiency.

[0005] In addition, due to factors such as machining and assembly errors and friction, the handle may exhibit inconsistent force feedback and bending angle repeatability when bent in both directions, that is, there is a difference in the control feel and precision when bending to the left and to the right.

[0006] Therefore, it is necessary to provide a new type of adjustable bending sheath handle to improve wire tension control during the bending process, reduce backlash and idle stroke, and improve the consistency and repeatability of bidirectional operation. Summary of the Invention

[0007] The technical problem to be solved by the invention is to provide a new adjustable bending sheath handle and an adjustable bending sheath assembly including the handle, which addresses the problems of backlash and idle stroke caused by the loosening of the bending wire in existing adjustable bending sheath handles, as well as the problem of poor consistency in bidirectional operation.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an adjustable bending sheath handle, including a handle housing, wherein a drive mechanism is provided inside the handle housing for converting input rotational motion into linear reciprocating motion; a differential balance beam mechanism, including a balance beam that can swing around a fulcrum, wherein the input end of the balance beam is connected to the output end of the drive mechanism to convert the linear reciprocating motion into the swing of the balance beam; a winding wheel mechanism, including a first winding wheel and a second winding wheel symmetrically arranged on both sides of the balance beam, wherein a first bending wire and a second bending wire are respectively connected to the first winding wheel and the second winding wheel; wherein both ends of the balance beam are respectively connected to the corresponding winding wheels through a motion conversion structure, so that the swing of the balance beam can drive the winding wheels on both sides to rotate in opposite directions; and a constant tension module, used to apply a constant rotational torque to the first winding wheel and the second winding wheel to keep the bending wire wound on them taut during the winding and unwinding process.

[0009] Preferably, the drive mechanism includes a knob, a sleeve coaxially connected to the knob, and a slider threaded into the sleeve and restricted to linear movement only; the slider is hinged to the balance beam via a connecting rod.

[0010] Preferably, the inner wall of the sleeve is provided with a first thread and a second thread in opposite directions, and the slider includes a first slider connected to the first thread and a second slider connected to the second thread, both of which are hinged to the balance beam through a first connecting rod and a second connecting rod, respectively.

[0011] Preferably, the sleeve is formed by splicing two half-tubes together.

[0012] Preferably, the handle housing is provided with a guide seat, and the slider is slidably connected to the guide seat.

[0013] Preferably, the motion conversion structure includes a first long slot drive rod and a second long slot drive rod respectively disposed on the first winding reel and the second winding reel, and a first drive pin and a second drive pin disposed at both ends of the balance beam. The first long slot drive rod and the second long slot drive rod are respectively provided with long slots along their length for the first drive pin and the second drive pin to be inserted.

[0014] Preferably, the winding reel is provided with a set screw for fixing the bending wire.

[0015] Preferably, the constant tension module includes a first constant force spring and a second constant force spring, which are respectively connected to the first reel and the second reel.

[0016] The present invention also provides an adjustable bending sheath assembly, comprising an adjustable bending sheath handle as described in any of the preceding claims and a sheath connected to the handle housing, the sheath having a proximal end located inside the handle housing and a distal end located outside the handle housing, one end of the bending wire extending to the distal end of the sheath.

[0017] Preferably, the distal end of the sheath is provided with an adjusting ring that is connected to the first adjusting wire and the second adjusting wire.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] First, by setting a constant tension module, a constant rotational torque is continuously applied to the first and second winding reels. This ensures that the bending wire is always taut during both the winding and unwinding processes, effectively preventing slackness caused by the unconstrained bending wire on the unwinding side. Because the bending wire remains taut, the drive mechanism can immediately act on it during reversing operations, thereby reducing backlash and idle travel during operation and improving the synchronization and consistency between the handle input and the bending response at the distal end of the sheath.

[0020] Secondly, the differential balance beam mechanism combined with the symmetrically arranged constant tension module provides symmetrical and stable mechanical conditions for the double-sided bending wire. When the balance beam swings, it drives the two winding wheels simultaneously, equally, but in opposite directions through the motion conversion structure, ensuring that the transmission ratio and force feedback for bending to the left and right are theoretically symmetrical. The constant tension module further balances nonlinear factors such as friction in the system. This design helps improve the consistency and repeatability of the bidirectional bending operation of the handle, allowing the operator to obtain a more consistent control feel in different directions.

[0021] Third, the constant torque provided by the constant tension module can, to some extent, compensate for the slight elongation of the bending wire or the slight increase in system clearance that may be caused by long-term use, temperature changes, or material creep. This helps maintain the stability of the bending performance of the handle after prolonged use and extends the reliable service life of the product.

[0022] Fourth, this invention integrates functions such as drive, differential conversion, and constant tension compensation into the handle housing, resulting in a compact structure. The intuitive operation of rotating the knob allows for smooth and precise bidirectional bending of the distal end of the sheath, conforming to the operating habits of clinicians and reducing the learning curve. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall appearance and structure of the present invention.

[0024] Figure 2 This is a schematic diagram of the exploded structure of the present invention.

[0025] Figure 3This is a schematic diagram of the exploded structure of the present invention after the outer shell has been removed.

[0026] Figure 4 This is a schematic diagram of the internal structure of the present invention.

[0027] Figure 5 This is a cross-sectional structural diagram of the present invention.

[0028] Figure 6 This is a schematic diagram of the set screw structure of the present invention.

[0029] Figure 7 This is a schematic diagram of the balance beam structure of the present invention.

[0030] Figure 8 This is a schematic diagram of the structure of the first and second bending wires of the present invention installed in the sheath tube.

[0031] Figure 9 This is a schematic diagram of the connection structure of the first and second bending wires and the bending ring of the present invention.

[0032] In the diagram: 1. Handle housing; 2. Knob; 3. Sheath; 4. Hemostatic valve; 5. Silicone plug; 6. Tube; 7. First slider; 8. Second slider; 9. First connecting rod; 10. Second connecting rod; 11. Guide seat; 12. Balance beam; 13. Pivot shaft; 14. First drive pin; 15. Second drive pin; 16. First winding reel; 17. Second winding reel; 18. First long slot drive rod; 19. Second long slot drive rod; 20. First bending screw; 21. Second bending screw; 22. Set screw; 23. First constant force spring; 24. Second constant force spring; 25. Bending ring; 26. First spring box; 27. Second spring box. Detailed Implementation

[0033] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides an adjustable curved sheath handle; please refer to the overall structure for details. Figures 1 to 5 The handle mainly includes a handle housing 1, a drive mechanism, a differential balance beam mechanism, a winding wheel mechanism, and a constant tension module.

[0036] The handle housing 1 is formed by connecting two housings, upper and lower, and forming a cavity inside to accommodate various components.

[0037] Please refer to Figure 2 , Figure 4 and Figure 5 The drive mechanism converts the operator's rotary input into linear reciprocating motion. In this embodiment, the drive mechanism includes a knob 2, a sleeve 6, and a slider. The knob 2 is rotatably mounted at one end of the handle housing 1, and its inner side has a non-circular hole or keyway for fixed connection with the sleeve 6 to achieve coaxial rotation. The sleeve 6 extends along the axial direction of the handle. To facilitate the installation of the slider inside the sleeve 6, the sleeve 6 is composed of two half-tubes joined together. The inner wall of the sleeve 6 has a first thread and a second thread in opposite directions. The slider includes a first slider 7 connected to the first thread and a second slider 8 connected to the second thread, both of which are hinged to the balance beam 12 via a first connecting rod 9 and a second connecting rod 10, respectively.

[0038] To restrict the rotational freedom of the slider to linear movement only, a guide seat 11 is fixedly installed inside the handle housing 1. The guide seat 11 is located inside the sleeve 6 and coaxially connected to the sleeve 6. The guide seat 11 is cylindrical and has a through hole for the sheath 3 to pass through. The guide seat 11 has a guide hole or guide groove that matches the shape of the slider, such as a rectangular groove or an arc groove. The slider is assembled in the guide hole or guide groove, so that it can only slide along the axial direction of the handle and cannot rotate with the sleeve 6. When the knob 2 drives the sleeve 6 to rotate, since the slider is restricted from rotating by the guide seat 11, the first slider 7 and the second slider 8 will move linearly in opposite directions simultaneously when the knob 2 is rotated.

[0039] Please refer to Figure 3 and Figure 7 The differential balance beam mechanism includes a balance beam 12. The middle portion of the balance beam 12 is rotatably connected to the handle housing 1 via a fulcrum shaft 13. The fulcrum shaft 13 can be a pin fixed to the handle housing 1, with a through hole in the middle of the balance beam 12 fitted onto the pin; alternatively, the balance beam 12 may have a rotating shaft in its middle, with both ends supported in corresponding bearing seats in the handle housing 1. The balance beam 12 can swing within a predetermined angle range around the fulcrum shaft 13.

[0040] The input end of the balance beam 12 is connected to the output end of the drive mechanism, i.e., the moving end of the slider. The connection is achieved through a hinged connection via a connecting rod. Specifically, the first slider 7 is hinged to the first input point at one end of the balance beam 12 via a first connecting rod 9, and the second slider 8 is hinged to the second input point at the other end of the balance beam 12 via a second connecting rod 10. The first and second input points are located on opposite sides of the fulcrum shaft 13. The hinge can be achieved through a pin and a shaft hole. When the sliders move linearly, they push or pull the balance beam 12 to swing around the fulcrum shaft 13 via the connecting rod. Because the two sliders move in opposite directions, the forces they exert on both ends of the balance beam 12 via the connecting rod are also opposite, thus efficiently converting linear motion into the swinging motion of the balance beam 12.

[0041] Please refer to Figure 4 and Figure 5 The winding mechanism includes a first winding reel 16 and a second winding reel 17. The first winding reel 16 and the second winding reel 17 are rotatably mounted inside the handle housing 1 via their respective axles and are symmetrically arranged on the left and right sides of the balance beam 12. The axles are fixed to the handle housing 1, and the winding reels are mounted on the axles via bearings or bushings, allowing them to rotate freely. A first bending wire 20 is wound on the first winding reel 16, and a second bending wire 21 is wound on the second winding reel 17.

[0042] Both ends of the balance beam 12 are connected to the corresponding winding reels via a motion conversion structure. In this embodiment, the motion conversion structure includes a long slot drive rod and a drive pin. Specifically, a first long slot drive rod 18 is fixedly connected to or integrally formed on the wheel body or axle of the first winding reel 16. Similarly, a second long slot drive rod 19 is fixedly connected to or integrally formed on the second winding reel 17. A long slot is formed along the length of each long slot drive rod. The long slot can be a straight slot or an arc-shaped slot adapted to the swing trajectory.

[0043] Please refer to Figure 4 and Figure 5 A first drive pin 14 is fixedly installed at one end of the balance beam 12. The axial direction of the first drive pin 14 is perpendicular to the swing plane of the balance beam 12, and its end extends into the long groove of the first long groove drive rod 18. Similarly, a second drive pin 15 is fixedly installed at the other end of the balance beam 12, and its end extends into the long groove of the second long groove drive rod 19. The drive pin and the long groove are in a sliding fit relationship.

[0044] When the balance beam 12 swings around the fulcrum axis 13, the first drive pin 14 slides within the long groove of the first long groove drive rod 18. Since the position of the drive pin is constrained by the swing trajectory of the balance beam 12, and the position of the long groove drive rod is constrained by the rotation center of the winding reel, the drive pin exerts a force on the long groove wall. This force can be decomposed into a force along the long groove direction and a force perpendicular to the long groove direction. The component force perpendicular to the long groove direction forms the tangential force that drives the first long groove drive rod 18 and the first winding reel 16 to rotate around their axles. When the balance beam 12 swings to the left, the first drive pin 14 drives the first winding reel 16 to rotate along the take-up direction, tightening the first bending wire 20; simultaneously, the second drive pin 15 moves within the long groove of the second long groove drive rod 19, driving the second winding reel 17 to rotate along the unwinding direction, releasing the second bending wire 21. When the balance beam 12 swings to the right, the actions are reversed: the second winding reel 17 takes in the wire, and the first winding reel 16 unwinds the wire. Thus, a single swinging motion of the balance beam 12 can differentially drive the two winding wheels to perform opposite rotational motions, one winding and one unwinding.

[0045] Please refer to Figures 4 to 6The constant tension module provides a constant rotational torque to the winding reel. In this embodiment, the constant tension module includes a first constant force spring 23 and a second constant force spring 24. A constant force spring is an elastic element whose output force or torque remains essentially constant, and its force value does not change significantly with the number of stretching or winding turns. The first constant force spring 23 is housed in a first spring box 26, and the second constant force spring 24 is housed in a second spring box 27. The spring boxes are fixedly installed inside the handle housing 1. One end of the first constant force spring 23 is fixed to the first spring box 26, and its output end, i.e., the movable end, is fixedly connected to the axle or wheel body of the first winding reel 16. One end of the second constant force spring 24 is fixed to the second spring box 27, and its output end is fixedly connected to the axle or wheel body of the second winding reel 17.

[0046] The first constant force spring 23 and the second constant force spring 24 are pre-tightened, and the rotational torque they provide is always directed to drive the corresponding reel in the take-up direction. This constant torque is designed to be less than the torque that the drive pin can apply when driving the reel to unload the wire via the long slot drive rod. This means that when the reel needs to unload, the driving force provided by the balance beam 12 through the drive pin is sufficient to overcome the holding torque of the constant force spring, allowing the reel to unload the wire smoothly. During the unloading process and when stationary, the torque of the constant force spring always acts on the reel, keeping the released bending wire taut and preventing it from slack. Similarly, during take-up, the torque of the constant force spring is in the same direction as the drive, assisting in take-up.

[0047] Please refer to Figure 5 and Figure 6 To reliably secure the bending wire, threading holes or grooves are provided on the outer circumferential or end faces of the first winding reel 16 and the second winding reel 17. After the proximal end of the bending wire passes through the threading hole, it is radially tightened and secured by a set screw 22. To further enhance the firmness, a small amount of medical-grade adhesive can be applied after tightening.

[0048] The working process and technical effects of the adjustable curved sheath handle in this embodiment are as follows:

[0049] In the initial state, the balance beam 12 is in a neutral position, and the bending wires on both sides are kept in an initial tension state under the pre-tensioning action of their respective constant force springs, and the distal end of the sheath tube 3 is straight.

[0050] When the operator needs to bend the distal end of the sheath 3 downwards, facing the proximal end of the handle, turn the knob 2 clockwise. The knob 2 causes the sleeve 6 to rotate synchronously. The inner wall of the sleeve 6 has two threads with opposite directions of rotation, forming threaded engagements with the first slider 7 and the second slider 8, respectively. Because the sliders are constrained by the guide seat 11 inside the handle housing 1 and can only slide along the handle axis, when the sleeve 6 rotates, the first slider 7 and the second slider 8 move in opposite directions along the axial direction. The first slider 7 pulls the left end of the balance beam 12 via the first connecting rod 9, and the second slider 8 pushes the right end of the balance beam 12 via the second connecting rod 10, thereby causing the balance beam 12 to swing clockwise around its central pivot axis 13.

[0051] When the balance beam 12 swings clockwise, its left end first drive pin 14 slides within the long groove of the first long groove drive rod 18, pushing the first long groove drive rod 18 to rotate the first winding wheel 16 counterclockwise, which is the winding direction. This causes the first winding wheel 16 to wind the first bending wire 20, applying a downward pulling force to the distal end of the sheath tube 3. Simultaneously, the right end second drive pin 15 slides within the long groove of the second long groove drive rod 19, pushing the second long groove drive rod 19 to rotate the second winding wheel 17 clockwise, which is the unwinding direction. This releases the second bending wire 21. During the unwinding process, the second constant force spring 24 consistently applies a constant counterclockwise rotational torque to the second winding wheel 17. This torque forces the released second bending wire 21 to remain taut, preventing the wire from slack. Under the combined action of the tightening of the first bending wire 20 and the release of the tension of the second bending wire 21, the distal end of the sheath tube 3 bends smoothly downwards.

[0052] When it is necessary to bend or retract the distal end of the sheath 3 upwards, the operator rotates the knob 2 counterclockwise. The knob 2 causes the sleeve 6 to rotate in the opposite direction, driving the first slider 7 and the second slider 8 to make a linear motion along the axial direction opposite to the aforementioned direction, which in turn drives the balance beam 12 to swing counterclockwise around the fulcrum axis 13 through the first connecting rod 9 and the second connecting rod 10.

[0053] When the balance beam 12 swings counterclockwise, its right end's second drive pin 15 drives the second long slot drive rod 19, causing the second winding reel 17 to rotate counterclockwise to wind up the line and tighten the second bending wire 21. Simultaneously, its left end's first drive pin 14 drives the first long slot drive rod 18, causing the first winding reel 16 to rotate clockwise to unwind the line and release the first bending wire 20. Similarly, under the constant clockwise rotational torque applied by the first constant force spring 23, the releasing first bending wire 20 remains taut. At this time, the distal end of the sheath 3 bends upward or straightens back under the pull of the second bending wire 21.

[0054] Throughout the bending process, regardless of the direction of operation, the constant tension module consistently provides a constant torque to both winding reels, tending towards the take-up direction. This design ensures that the bending wire on the let-out side does not slack, eliminating gaps between the drive pin and the long slot drive rod, as well as throughout the entire drivetrain. Therefore, the handle experiences no backlash or idle travel during reversing operations, resulting in a direct response.

[0055] Meanwhile, based on the symmetrical layout of the differential balance beam 12 and the constant tension compensation that is exactly the same on both sides, the handle has a highly consistent operating force feedback and bending angle repeatability when bending in both directions, which effectively improves the intuitiveness, accuracy and reliability of surgical operation.

[0056] The constant torque provided by the constant force spring can also, to some extent, offset the gaps caused by slight stretching of the first and second adjusting wires 20 or wear of components after long-term use, which helps to maintain the stability of the handle's long-term performance.

[0057] Example 2

[0058] Please refer to Figure 1 , Figure 2 , Figure 8 and Figure 9 This embodiment provides an adjustable bending sheath assembly. The assembly includes the adjustable bending sheath handle described in Embodiment 1 and a sheath 3. One end of the handle housing 1, connected to a knob 2, has a first interface for the sheath 3 to pass through. The sheath 3 is sealed to the knob 2 via a silicone plug 5. The other end of the handle housing 1 has a second interface for installing a hemostatic valve 4. The sheath 3 is a slender tubular component with at least one through-hole for delivering instruments or injecting liquids. The second interface houses a hemostatic valve 4 that communicates with the lumen of the sheath 3.

[0059] After the first bending wire 20 and the second bending wire 21 are led out from the handle housing 1, they pass through the wall of the sheath tube 3 or a separate wire cavity, and extend axially along the sheath tube 3 to the distal end of the sheath tube 3. At the distal end of the sheath tube 3, the ends of the first bending wire 20 and the second bending wire 21 are fixed in a specific manner, such that when one of the bending wires is tightened, the distal end of the sheath tube 3 bends to that side. The fixing method can be to directly anchor the ends of the bending wires to different circumferential positions on the side wall of the distal end of the sheath tube 3; or, a bending ring 25 is provided inside or outside the distal end of the sheath tube 3, and the ends of the two bending wires are respectively connected to the two circumferentially opposite sides of the bending ring 25, so that the bending ring 25 can be rotated by differential pulling.

[0060] The adjustable bending sheath 3 component of this embodiment, by integrating a handle with improved maneuverability, can provide a highly capable, precise, and consistent adjustable bending channel tool for clinical interventional surgery, which helps to improve the safety and efficiency of the surgery.

[0061] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An adjustable curved sheath handle, comprising a handle housing (1), characterized in that, The handle housing (1) is provided with a drive mechanism; The differential balance beam mechanism includes a balance beam (12) that can swing around a fulcrum, the input end of the balance beam (12) being connected to the output end of the drive mechanism; The winding mechanism includes a first winding wheel (16) and a second winding wheel (17) symmetrically arranged on both sides of the balance beam (12). The first winding wheel (16) and the second winding wheel (17) are respectively connected to a first bending wire (20) and a second bending wire (21). The two ends of the balance beam (12) are respectively connected to the corresponding winding wheels through a motion conversion structure. The constant tension module is used to apply a constant rotational torque to the first winding reel (16) and the second winding reel (17) so that the bending wire wound on them remains taut during winding and unwinding.

2. The adjustable curved sheath handle according to claim 1, characterized in that, The drive mechanism includes a knob (2), a sleeve (6) coaxially connected to the knob (2), and a slider threaded to the sleeve (6) and restricted to linear movement only; the slider is hinged to the balance beam (12) via a connecting rod.

3. The adjustable curved sheath handle according to claim 2, characterized in that, The inner wall of the sleeve (6) is provided with a first thread and a second thread in opposite directions. The slider includes a first slider (7) connected to the first thread and a second slider (8) connected to the second thread. The two are respectively hinged to the balance beam (12) through a first connecting rod (9) and a second connecting rod (10).

4. The adjustable curved sheath handle according to claim 2, characterized in that, The sleeve (6) is made up of two half-tubes joined together.

5. The adjustable curved sheath handle according to claim 2, characterized in that, The handle housing (1) is provided with a guide seat (11), and the slider is slidably connected to the guide seat (11).

6. The adjustable curved sheath handle according to claim 1, characterized in that, The motion conversion structure includes a first long slot drive rod (18) and a second long slot drive rod (19) respectively disposed on the first winding reel (16) and the second winding reel (17), and a first drive pin (14) and a second drive pin (15) disposed at both ends of the balance beam (12). The first long slot drive rod (18) and the second long slot drive rod (19) are respectively provided with long slots along their length direction for the first drive pin (14) and the second drive pin (15) to be inserted.

7. The adjustable curved sheath handle according to claim 1, characterized in that, The winding reel is provided with a set screw (22) for fixing the bending wire.

8. The adjustable curved sheath handle according to claim 1, characterized in that, The constant tension module includes a first constant force spring (23) and a second constant force spring (24), which are connected to the first reel (16) and the second reel (17), respectively.

9. An adjustable bending sheath assembly, characterized in that, The device includes an adjustable bending sheath handle according to any one of claims 1-8 and a sheath (3) connected to the handle housing (1), the sheath (3) having a proximal end located inside the handle housing (1) and a distal end located outside the handle housing (1), one end of the bending wire extending to the distal end of the sheath (3).

10. The adjustable bending sheath assembly according to claim 9, characterized in that, The distal end of the sheath (3) is provided with an adjusting ring (25) that is connected to the first adjusting wire (20) and the second adjusting wire (21).

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