Endoscope bend angle follow-up stop control method and device

Abstract

The application discloses an endoscope bend angle control method and device, and relates to the medical treatment technical field.The endoscope bend angle control method comprises the following steps: 1, endoscope bend angle, comprising: 1-1, radial compression of the elastic sheet; 1-2, the resistance end of the locking block moves radially inward along with the elastic sheet, the frictional fit between the brake surface and the friction surface is released, and then the endoscope snake bone is bent; 2, endoscope stop, comprising: 2-1, removing the external force F, the driving wheel stops rotating, the elastic sheet returns and moves radially outward; 2-2, while the elastic sheet moves radially outward, the resistance end of the locking block moves radially outward along with the elastic sheet, the brake surface of the locking block is frictionally fitted with the friction surface of the locking wheel; at the same time, the power end of the locking block moves radially inward and is locked with the outer wall surface of the transmission shaft, so that the transmission shaft immediately stops rotating, and then the endoscope snake bone stops bending.The application can realize the bend and stop of the endoscope bend angle, and can ensure the automatic locking of the traction steel wire rope in the stop state and prevent slippage.

Description

Technical Field

[0001] This invention relates to the field of endoscopy, and in particular to a method and apparatus for controlling the bend angle of an endoscope to stop as it bends. Background Technology

[0002] When using an endoscope, it is necessary to be able to lock the bend at any time so that the probe can be fixed at the optimal angle for observation of the target. In actual use, existing endoscopes usually require one hand to hold the endoscope and manipulate the bend to locate the target, while the other hand operates the bend locking mechanism to fix the observation. That is, both hands need to be used at the same time, and the observation may be affected by probe shaking during operation.

[0003] Chinese invention patent application CN109730623A, entitled "Diameter Reduction Device and Corner Locking Device," includes an elastic covering ring, a central shaft, multiple outer peripheral units, and an elastic plate. It employs a diameter reduction device in conjunction with a locking surface to achieve corner locking of the wire rope. This patent application, to a certain extent, enables immediate stopping at bends. However, during corner locking, it relies solely on the elastic force of the elastic plate to re-engage the outer surface of the outer peripheral unit with the locking surface for locking. This locking method results in a certain degree of slippage between the outer surface of the outer peripheral unit and the locking surface after locking, causing the wire rope to slip. Consequently, the corner control accuracy is low, failing to meet the requirements for precise observation or use. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing an endoscope bending angle control method that can stop the endoscope bending angle as it bends, and ensure that the traction steel wire rope is automatically and accurately locked in the stopped state to prevent slippage.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for controlling the bend angle of an endoscope to stop as it bends includes the following steps:

[0007] Step 1, Endoscope bend, including:

[0008] Step 1-1: An external force F causes the drive wheel to rotate, and under the action of the external force F, the spring is radially compressed.

[0009] Steps 1-2: While the spring is being radially compressed, the locking block of the lever structure rotates around the pivot pin, and the resistance end of the locking block located outside the spring moves radially inward with the spring; the braking surface at the top of the resistance end releases its frictional engagement with the friction surface of the outer locking wheel.

[0010] Steps 1-3: The drive wheel drives the transmission shaft and the locking wheel to rotate synchronously; the transmission shaft directly or indirectly drives the traction rope disc to rotate, thereby causing the traction rope wound on the traction rope disc to extend and retract, and thus controlling the bending of the endoscope snake bone at the end of the traction rope.

[0011] Step 2, Endoscope stops, including:

[0012] Step 2-1: Remove the external force F, the drive wheel stops rotating, the spring returns to its original position and moves radially outward.

[0013] Step 2-2: As the spring moves radially outward, the locking block rotates around the pivot pin. The resistance end of the locking block moves radially outward with the spring, causing the braking surface of the locking block to rub against the friction surface of the locking wheel. At the same time, the power end of the locking block moves radially inward and locks against the outer wall of the drive shaft, causing the drive shaft to stop rotating immediately, thereby stopping the endoscope snake bone from bending.

[0014] Let a be the average distance from the braking surface to the rotating pin, and b be the average distance from the locking hook to the rotating pin. Then the lever ratio k = a:b = 1.2~2. The lever ratio k reduces the frictional force required between the braking surface and the friction surface, thereby reducing the restoring force of the spring in step 2-1. At the same time, the lever ratio k can also amplify the restoring force of the spring, increasing the locking force between the power end diameter of the locking block and the outer wall of the transmission shaft in step 2-2.

[0015] In steps 1-2, while the resistance end of the locking block moves radially inward, the power end of the locking block moves radially outward simultaneously. The power end of the locking block can be locked with the locking groove on the outer wall of the transmission shaft through the locking hook. By making the depth of the locking groove greater than the radial compression of the spring, the power end of the locking block remains in the locking groove after moving radially outward simultaneously. Therefore, in step 2-2, the power end of the locking block can move radially inward under the guidance of the locking groove.

[0016] In step 2-2, the locking groove is a V-shaped groove set on the drive shaft. When the endoscope snake stops bending, the locking block locks the drive shaft by setting the opening angle β of the V-shaped groove; wherein, the opening angle β of the V-shaped groove is obtained by the following calculation formula:

[0017] ;

[0018] In the formula, k is the leverage ratio of the locking block; For the restoring force of shrapnel;

[0019] The coefficient of friction between the V-groove and the locking hook;

[0020] The radius of the drive shaft; This refers to the torque of the drive shaft.

[0021] In steps 1-2, the locking wheel is made of chrome steel and the locking block is made of polytetrafluoroethylene.

[0022] The braking surface is a smooth arc surface, the friction surface is a triangular tooth surface, and the coefficient of dynamic friction between the braking surface and the friction surface is 0.02~0.08.

[0023] Using Hertzian contact theory, the parameters of the triangular tooth surface were calculated and designed, including the bus contact area between the braking surface and the triangular tooth surface. The specific formulas for calculating tooth pitch P and total number of teeth N are as follows:

[0024] ;

[0025] ;

[0026] ;

[0027] in:

[0028] ;

[0029] In the formula, For the restoring force of shrapnel; W is the radius of the braking surface; W is the axial thickness of the braking surface.

[0030] The equivalent elastic modulus of the locking block and the locking wheel;

[0031] and These are the elastic moduli of the materials corresponding to the locking block and the locking wheel, respectively.

[0032] and These are the Poisson's ratios of the materials corresponding to the locking block and the locking wheel, respectively.

[0033] The minimum locking resolution for the friction mating surfaces is set based on the endoscope's bending stop accuracy.

[0034] D1 is the inner diameter of the locking wheel.

[0035] In step 1-1, the maximum radial compression δ of the spring and the restoring force of the spring in step 2-1 The following calculation formula must be met:

[0036] ;

[0037] ;

[0038] In the formula, k is the lever ratio of the locking block; n is the number of locking blocks; and r is the distance from the lowest point of the locking groove to the center axis of the drive shaft.

[0039] T is the torque of the drive shaft; R is the initial radius of curvature of the spring in its natural, uncompressed state.

[0040] E is the elastic modulus of the spring; b is the width of the longitudinal section of the spring; h is the height of the longitudinal section of the spring.

[0041] In steps 1-2 and 2-2, the maximum rotation angle θ of the locking block is related to the maximum radial compression δ of the spring, and the specific calculation formula is as follows:

[0042] ;

[0043] In the formula, This is the absolute distance from the pivot point of the locking block to the center point of the drive wheel;

[0044] This represents the maximum rotation angle of the drive wheel.

[0045] An endoscope bend angle control device that stops as the endoscope bends, employing an endoscope bend angle stop-as-you-go control method.

[0046] The present invention has the following beneficial effects: Through the design of the locking block and spring plate of the arc-shaped lever structure, when bending, due to inertia and the gravity of the lever resistance end, the locking block rotates clockwise or counterclockwise, the braking surface of the locking block disengages from the friction surface of the locking wheel, and the locking hook on the bottom of the other side of the locking block is released from the locking groove on the transmission shaft; when bending stops, the locking block rotates in the opposite direction under the elastic force of the spring plate, the braking surface of the locking block rubs against the friction surface of the locking wheel, and the locking hook on the locking block locks into the locking groove on the transmission shaft, ensuring automatic locking of the traction wire rope when it is stopped and preventing slippage. Attached Figure Description

[0047] Figure 1 This paper presents a three-dimensional overall structural schematic diagram of an endoscope bending angle control method that stops as the endoscope bends, according to this application.

[0048] Figure 2 This image shows a three-dimensional longitudinal section of an endoscope bending angle control method according to the present application.

[0049] Figure 3 An exploded view of an endoscope bending angle control method according to this application is shown.

[0050] Figure 4 This application shows the three-dimensional contact between the braking surface of the locking block and the friction surface of the locking wheel when they are in contact. Figure 1 .

[0051] Figure 5 This application shows the three-dimensional contact between the braking surface of the locking block and the friction surface of the locking wheel when they are in contact. Figure 2 .

[0052] Figure 6 A three-dimensional structural diagram of the drive wheel in this application is shown.

[0053] Figure 7 A three-dimensional structural diagram of the drive shaft in this application is shown.

[0054] Figure 8 A three-dimensional structural diagram of the locking wheel in this application is shown.

[0055] Figure 9 A three-dimensional structural diagram of the spring sheet in this application is shown.

[0056] Figure 10 A three-dimensional structural diagram of the locking block in this application is shown.

[0057] Figure 11 The diagram shows a locking block rotating clockwise when the endoscope is bent, decoupled from the drive shaft and locking wheel.

[0058] Figure 12 The diagram shows a scenario where the frictional mating surfaces between the locking wheel and the locking block are in tooth meshing.

[0059] Among them are:

[0060] 10. Wire rope drive mechanism;

[0061] 11. Drive wheel; 111. Lower bushing; 111a. Winding groove; 112. Limiting arc one; 113. Limiting groove one; 114. Drive shaft hole;

[0062] 12. Drive shaft; 121. Auxiliary locking bar; 121a. Lock groove; 122. Guide bar; 122a. Guide surface;

[0063] 13. Driven wheel;

[0064] 131. Upper bushing; 132. Pin hole; 133. Positioning shaft hole; 134. Limiting arc two; 135. Limiting groove two;

[0065] 20. Locking wheel; 21. Friction surface; 22. Upper limit ring; 23. Lower limit ring;

[0066] 30. Spring clip; 31. Mounting ring;

[0067] 40. Locked block;

[0068] 41. Rotating pin; 42. Power end; 421. Locking hook; 43. Resistance end; 431. Braking surface; 44. Radial clearance. Detailed Implementation

[0069] The present invention will now be described in further detail with reference to the accompanying drawings and specific preferred embodiments.

[0070] In the description of this invention, it should be understood that the terms "left side," "right side," "upper part," "lower part," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. "First," "second," etc., do not indicate the importance of the components, and therefore should not be construed as a limitation of this invention. The specific dimensions used in this embodiment are only for illustrating the technical solution and do not limit the scope of protection of this invention.

[0071] like Figures 1 to 5 As shown, an endoscope bending angle control device includes a wire rope drive mechanism 10, a locking wheel 20, n spring pieces 30, and n locking blocks 40; wherein n≥2, and in this embodiment, n=2 is preferred. This satisfies the bending angle control requirements while having fewer locking blocks, a simpler structure, and lower manufacturing costs. Alternatively, n=3, 4, or other numbers can also be selected, which are also within the scope of protection of this application.

[0072] The wire rope drive mechanism includes a drive wheel 11, a transmission shaft 12, and a traction rope reel drive shaft 13.

[0073] The drive wheel can rotate actively and is preferably coaxially sleeved on the bottom of the transmission shaft via a lower bushing 111. Active rotation of the drive wheel is existing technology and can be directly controlled by a hand crank or remotely controlled. In this embodiment, the bottom of the lower bushing of the drive wheel is preferably provided with a winding groove 111a, in which a control wire is wound. The other end of the control wire is connected to a control lever (either manually or remotely). The control wire and control lever are not shown in the figure.

[0074] like Figure 6 As shown, the top outer periphery of the lower bushing is provided with n limiting arcs 112, and a limiting groove 113 is formed between two adjacent limiting arcs. The bottom of the lower bushing is provided with a drive shaft hole 114 that cooperates with the drive shaft, preferably a square hole or a polygonal hole, which can realize the circumferential positioning of the drive shaft, so that the lower bushing rotates synchronously with the drive shaft.

[0075] like Figure 7As shown, the drive shaft is preferably a square shaft or a polygonal shaft, etc., and n auxiliary locking bars and n guide bars 122 are evenly and alternately arranged along the circumference of the drive shaft. The cross-section of each auxiliary locking bar and each guide bar is preferably a sector-shaped cross-section with a central angle of α, and the height of the sector is preferably equal and h. In this embodiment, α=100° and h=0.34mm are preferred; wherein, a locking groove 121a is provided at the top center of each auxiliary locking bar, and the top surface of each guide bar is a smooth guide surface 122a.

[0076] The locking groove 121a is preferably a V-shaped groove, and the depth of the V-shaped groove is greater than the radial compression of the spring piece.

[0077] The traction rope reel drive shaft is preferably mounted on the top of the transmission shaft via an upper shaft sleeve 131, and can drive the traction rope reel to rotate.

[0078] Furthermore, the top of the upper bushing is provided with a plug-in limiting block, which is used to circumferentially position the traction rope reel so that the traction rope reel rotates synchronously with the drive shaft.

[0079] like Figure 3 As shown, n pin holes 132 are evenly distributed along the circumference of the upper bushing, which cooperate with the rotating pins of the subsequent n locking blocks to provide a fulcrum for rotation.

[0080] The upper bushing is provided with a positioning shaft hole 133 at its center. Preferably, the positioning shaft hole can cooperate with the drive shaft, n auxiliary locking bars and n guide bars, so as to fix the circumferential position of the drive shaft. Furthermore, n limiting arcs 134 are provided on the outer circumference of the bottom of the upper bushing, and a limiting groove 135 is formed between two adjacent limiting arcs.

[0081] The n limiting arcs of the lower bushing and the n limiting arcs of the upper bushing are circumferentially aligned and engaged to form n limiting arcs; the n limiting arcs and the drive shaft form an annular cavity, and the outer diameter of the annular cavity is smaller than the inner diameter of the locking wheel; the n limiting grooves and the n limiting grooves form a one-to-one corresponding set of n limiting grooves.

[0082] The aforementioned locking wheel is coaxially sleeved on the outer periphery of the middle part of the drive shaft, preferably fixed in both axial and circumferential directions, with the inner wall surface of the locking wheel serving as a friction surface 21. A preferred method for fixing the axial and circumferential positions of the locking wheel is as follows: an upper limit ring 22 is provided on the upper surface of the locking wheel, detachably mounted on the upper bushing, which axially limits the position of the upper surface of the locking wheel. A lower limit ring 23 is provided on the lower surface of the locking wheel, detachably mounted on the lower bushing, which axially limits the position of the lower surface of the locking wheel.

[0083] like Figure 9As shown, n spring clips are all mounted on the mounting ring 31, which is coaxially mounted on the drive shaft. Because the mounting ring has a square hole that mates with the drive shaft, it can rotate synchronously with the drive shaft.

[0084] The n locking blocks are preferably arranged in a centrally symmetrical manner in the inner cavity of the locking wheel with the axis of the drive shaft as the center, and more preferably located in the aforementioned annular receiving cavity, and the limiting arc can limit the outer rotational displacement of the locking blocks.

[0085] The materials of the locking wheel and locking block, as well as the friction mating surfaces between the locking wheel and locking block, were determined after long-term experimental research and analysis.

[0086] I. Friction mating surfaces

[0087] In existing methods, after the friction mating surfaces are locked, there is a certain degree of slippage between the outer surface of the outer peripheral unit and the locking surface, which causes the wire rope to slip, resulting in low bending angle control accuracy and failing to meet the requirements for precision observation or use.

[0088] A. Tooth meshing

[0089] like Figure 12 As shown, the friction mating surfaces between the locking wheel and the locking block are toothed, ensuring accurate locking when the endoscopic serpentine stops bending, without slippage or drift. However, this toothed engagement method has the following problems in use:

[0090] (1) The teeth are not easy to engage, making it difficult to start the endoscope when it is bent. To make the teeth engage easily, the usual operating method is: (a) to machine a large chamfer (e.g., 10°~15°) on the tip of the teeth that enter the engagement side; (b) to design the teeth of the half clutch to be connected to be shortened by half every other tooth (or several teeth); (c) to remove one tooth from the inner teeth of the other half every other segment.

[0091] (2) There will be a gap of 0.2mm in the middle of the meshing teeth, which will result in a 1.08° backlash when rotating left and right, thus affecting the control accuracy.

[0092] B. Arc-surface friction fit

[0093] The friction mating surfaces between the locking wheel and the locking block are two arc-shaped friction mating surfaces. In this case, the following shortcomings exist:

[0094] (1) Slippage and inaccurate position control.

[0095] (2) Wear debris is not easy to be discharged, which can lead to unstable friction coefficient.

[0096] (3) Friction generates significant heat.

[0097] Therefore, in this application, the friction mating surfaces of the friction surface and the braking surface are selected as a triangular toothed surface and a smooth arc surface. In this embodiment, the locking wheel is preferably made of steel such as Cr steel, and each locking block is preferably made of polytetrafluoroethylene. The friction surface is preferably as follows: Figure 8 The triangular tooth surface shown has a brake surface that is preferably a smooth arc surface, and the coefficient of dynamic friction between the brake surface and the friction surface is preferably 0.02~0.08, more preferably 0.04.

[0098] The aforementioned locking block preferably uses polytetrafluoroethylene (PTFE) with the following advantages:

[0099] 1. PTFE has an extremely low coefficient of friction (0.04~0.15 for dry friction) and excellent self-lubricating properties, which can achieve low-resistance braking and reduce energy loss and noise during braking (no metal impact sound under dry friction conditions).

[0100] 2. PTFE is non-adhesive and has strong chemical stability. Even under unlubricated conditions, it can avoid adhesive wear with chromium steel ("cold welding" phenomenon) and ensure the smoothness of the friction process.

[0101] 3. It has low hardness (Shore D50~60) and belongs to "soft self-lubricating material". The wear mode is mainly slight abrasive wear, which will not cause cutting damage to hard friction rings and play the role of "protecting mating parts".

[0102] The aforementioned locking wheel preferably uses chrome steel, which has the following advantages:

[0103] 1. After heat treatment, chromium steel can reach a hardness of HRC60~65, with excellent wear resistance. It can resist the slight cutting action of PTFE friction and avoid premature failure of the friction ring surface.

[0104] 2. The high strength and rigidity of chromium steel ensure that the tooth surface structure does not deform under braking pressure, maintains the fitting accuracy of the contact surface, and avoids fluctuations in the coefficient of friction due to structural deformation.

[0105] Alternatively, the locking block can be made of other materials with lower density or lower strength than the locking wheel.

[0106] The friction mating surface composed of the triangular tooth surface and the smooth arc surface described above has the following significant advantages.

[0107] 1. It forms a classic "soft-hard combination", which not only achieves stable friction coefficient (braking reliability), but also reduces wear on both sides through the self-lubrication of PTFE, significantly extending the service life of the device, and eliminating the need for frequent lubricant addition, thus reducing maintenance costs.

[0108] 2. The braking surface adopts a smooth arc surface. The core is to compensate for installation errors and motion deviations in the mechanical system through the self-adaptability of the curved surface contact.

[0109] 3. Automatic centering function: When the smooth arc surface mates with the triangular tooth surface, the posture can be automatically adjusted by the normal force of the contact surface to compensate for the coaxiality error during installation (allowing a deviation of ±0.1~0.3mm), ensuring that the contact center of the locking block and the locking wheel always coincides with the axis and avoiding "one-sided contact".

[0110] 4. Uniform contact stress: The contact of the smooth arc surface is a "line contact to surface contact". Compared with the plane contact, the stress distribution is more uniform, which can avoid the early peeling of PTFE blocks or the chipping of chrome steel tooth surface caused by local stress concentration.

[0111] 5. Buffering impact load: The relative motion during braking is achieved through the gradual contact of the arc surface, which reduces "rigid collision", lowers the impact load at the moment of braking, and improves the smoothness of operation (especially suitable for braking under high speed or heavy load conditions).

[0112] 6. The friction surface adopts a triangular tooth surface, which is not simply to increase the friction area, but to achieve the following multiple functions through the groove structure:

[0113] A. Chip Removal and Anti-clogging: PTFE generates a small amount of micron-sized wear debris during friction. The tooth grooves can act as a "chip removal channel" to promptly remove wear debris and external dust impurities, preventing wear debris from accumulating between the friction surfaces and forming "third-party wear" (aggravated abrasive wear), thus ensuring the long-term stability of the friction coefficient.

[0114] B. Enhanced heat dissipation: If the heat generated during friction cannot be dissipated in time, it will cause the PTFE temperature to rise (performance will decline when it exceeds 260℃). The toothed groove increases the heat dissipation area of ​​the locking wheel (compared to the smooth surface, the heat dissipation area can be increased by 30%~50%), reducing the friction temperature rise and avoiding thermal decomposition or thermal deformation of PTFE.

[0115] C. Improved braking sensitivity: The tooth tip is a local contact area, which has a greater contact pressure than a smooth surface (according to Hertzian contact theory, line contact pressure is higher than surface contact pressure), which can quickly establish effective frictional resistance and shorten braking response time; at the same time, the "concave-convex structure" of the tooth surface can increase the "mechanical meshing effect" of the friction surface, further improving braking reliability (especially suitable for low-speed heavy-load conditions).

[0116] D. Adapting to variable working conditions: When the device is subjected to impact load or variable load, the grooves on the tooth surface can absorb some energy, reduce the vibration of the friction surface, avoid "friction chatter" (stick-slip phenomenon), and ensure the smoothness of the braking process.

[0117] In this invention, Hertzian contact theory is used to calculate and design the parameters of the triangular tooth surface, including the bus contact area between the braking surface and the triangular tooth surface. The specific formulas for calculating tooth pitch P and total number of teeth N are as follows:

[0118] ;

[0119] ;

[0120] ;

[0121] in:

[0122] ;

[0123] In the formula, For the restoring force of shrapnel; Where is the radius of the braking surface; W is the axial thickness of the braking surface.

[0124] This is the equivalent elastic modulus of the locking block and the locking wheel.

[0125] and These are the elastic moduli of the materials corresponding to the locking block and the locking wheel, respectively.

[0126] and These are the Poisson's ratios of the materials corresponding to the locking block and the locking wheel, respectively.

[0127] The minimum locking resolution for the friction mating surfaces is set based on the endoscope's bending stop accuracy.

[0128] D1 is the inner diameter of the locking wheel.

[0129] In this embodiment, the number of triangular teeth on the friction surface is preferably 120, evenly distributed along the friction surface. Since the smooth arc coverage angle of the braking surface in the locking block of this invention is preferably 45 degrees, the number of triangular teeth rubbing against the smooth arc surface of the braking surface is 16. Each triangular tooth has a thickness of 0.3 mm and a width of 0.6 mm, therefore, the contact area of ​​each triangular tooth is 0.18 mm². 2 .

[0130] like Figure 4 , Figure 5 and Figure 10 As shown, each locking block is an arc-shaped lever structure, including a rotating pin 41, a power end 42, and a resistance end 43; wherein, the rotating pin is the fulcrum of rotation, the power end and the resistance end are located on both sides of the rotating pin, and the mass of the resistance end is greater than the mass of the power end.

[0131] The aforementioned rotating pins 41 are all installed in the corresponding pin holes 132 of the upper bushing, so that the locking block can rotate synchronously with the drive wheel.

[0132] Each power end has a locking hook 421 on its inner outer edge pointing towards the center of the locking wheel, and can be locked with the aforementioned locking groove.

[0133] Each resistance end has a sector-shaped brake block on its outer edge. The sector-shaped brake blocks protrude from the corresponding limiting grooves. The top surface of the sector-shaped brake block has an arc-shaped brake surface 431. The brake surface is preferably a smooth arc surface that can cooperate with the friction surface at any time.

[0134] Let the average distance from the braking surface to the rotating pin be *a*, and the average distance from the locking hook to the rotating pin be *b*. Then the transmission ratio *k* = *a*: *b* = 1.2~2, more preferably 1.5 or 1.6. The above-mentioned lever ratio *k* reduces the required frictional force between the braking surface and the friction surface, thereby reducing the restoring force of the spring in step 2-1. Simultaneously, the lever ratio *k* also amplifies the restoring force of the spring, increasing the locking force between the power end diameter of the locking block and the outer wall of the transmission shaft in step 2-2.

[0135] A method for controlling the bend angle of an endoscope to stop as it bends includes the following steps.

[0136] Step 1, Endoscope bend

[0137] Step 1-1: An external force F causes the drive wheel to rotate, and under the action of the external force F, the spring is radially compressed.

[0138] The maximum radial compression δ of the aforementioned shrapnel is calculated using the following formula:

[0139] ;

[0140] in:

[0141] ;

[0142] In the formula, k is the lever ratio of the locking block; n is the number of locking blocks; and r is the distance from the lowest point of the locking groove to the center axis of the drive shaft.

[0143] T is the torque of the drive shaft; R is the initial radius of curvature of the spring in its natural, uncompressed state.

[0144] E is the elastic modulus of the spring; b is the width of the longitudinal section of the spring; h is the height of the longitudinal section of the spring.

[0145] In this embodiment, the drive shaft is preferably driven by a control wire. Assuming the tension of the control wire is 5N and the effective radius of the drive shaft is 6mm, then the torque of the drive shaft... Furthermore, let r = 3.6 mm, n = 2, a = 5.29 mm, b = 3.92 mm, and k = 1.349, then... Not less than 3.08N, maximum radial compression δ=0.8mm. Since the spring does not produce positive deformation, the effective deformation of the spring is -0.8mm~-0.2mm. When the spring is at -0.2mm, the braking surface and the friction plate are in frictional engagement; when the spring is at -0.8mm, the braking surface and the friction plate are in contact frictional engagement, and the endoscope is operated at the bend angle.

[0146] Steps 1-2: As the spring is radially compressed, the locking block of the lever structure rotates around the pivot pin, and the resistance end of the locking block located outside the spring moves radially inward with the spring; the braking surface at the top of the resistance end releases its frictional engagement with the friction surface of the outer locking wheel, specifically as follows... Figure 11 As shown. While the resistance end of the locking block moves radially inward, the power end of the locking block moves radially outward simultaneously. The power end of the locking block is locked with the locking groove on the outer wall of the transmission shaft through the locking hook. By making the depth of the locking groove greater than the radial compression of the spring, the power end of the locking block remains within the locking groove after moving radially outward simultaneously.

[0147] The maximum rotation angle θ of the locking block is related to the maximum radial compression δ of the spring, and the specific calculation formula is as follows:

[0148] ;

[0149] In the formula, This is the absolute distance from the pivot point of the locking block to the center point of the drive wheel;

[0150] This represents the maximum rotation angle of the drive wheel.

[0151] In this embodiment, the maximum rotation angle θ = 2.3°, so the rotation range of the locking block is 0~2.3°. When the locking block is at 0°, the spring is at a compression deformation position of -0.2mm; when the locking block is at 2.3°, the spring is at a compression deformation position of -0.8mm.

[0152] Steps 1-3: The drive wheel drives the transmission shaft and the locking wheel to rotate synchronously; the transmission shaft directly or indirectly drives the traction rope disc to rotate, thereby causing the traction rope wound on the traction rope disc to extend and retract, and thus controlling the bending of the endoscope snake bone at the end of the traction rope.

[0153] Step 2, Endoscope stops

[0154] Step 2-1: Remove the external force F, the drive wheel stops rotating, the spring returns to its original position and moves radially outward.

[0155] Step 2-2: As the spring moves radially outward, the locking block rotates around the pivot pin. The resistance end of the locking block moves radially outward with the spring, causing the braking surface of the locking block to engage with the friction surface of the locking wheel. Simultaneously, the power end of the locking block preferably moves radially inward under the guidance of the locking groove, locking with the outer wall of the drive shaft, causing the drive shaft to stop rotating immediately, thereby stopping the endoscope's serpentine frame from bending. At this time, if... Figure 5 As shown, the height of the spring piece is higher than the top surface height of the guide bar, that is, there is a radial gap 44 between the guide bar and the bottom surface of the locking block.

[0156] In this invention, the locking block secures the drive shaft by setting the V-groove opening angle β; wherein the V-groove opening angle β is obtained by the following calculation formula:

[0157] ;

[0158] In the formula, k is the leverage ratio of the locking block; For the restoring force of shrapnel;

[0159] The coefficient of friction between the V-groove and the locking hook;

[0160] The radius of the drive shaft; This refers to the torque of the drive shaft.

[0161] In this embodiment, β=45° is preferred.

[0162] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A method for controlling the bend angle of an endoscope to stop as it bends, characterized in that: Includes the following steps: Step 1, Endoscope bend, including: Step 1-1: An external force F causes the drive wheel to rotate, and under the action of the external force F, the spring is radially compressed; Steps 1-2: While the spring is radially compressed, the locking block of the lever structure rotates around the pivot pin, and the resistance end of the locking block located on the outer side of the spring moves radially inward with the spring; the braking surface at the top of the resistance end releases friction from the friction surface of the outer locking wheel; the locking wheel is made of chrome steel, and the locking block is made of polytetrafluoroethylene; the braking surface is a smooth arc surface, and the friction surface is a triangular tooth surface. Steps 1-3: The drive wheel drives the transmission shaft and the locking wheel to rotate synchronously; the transmission shaft directly or indirectly drives the traction rope disc to rotate, thereby causing the traction rope wound on the traction rope disc to extend and retract, and thus controlling the bending of the endoscope snake bone at the end of the traction rope. Step 2, stop the endoscope, including: Step 2-1: Remove the external force F, the drive wheel stops rotating, the spring returns to its original position and moves radially outward; Step 2-2: As the spring moves radially outward, the locking block rotates around the pivot pin. The resistance end of the locking block moves radially outward with the spring, causing the braking surface of the locking block to rub against the friction surface of the locking wheel. At the same time, the power end of the locking block moves radially inward and locks against the outer wall of the drive shaft, causing the drive shaft to stop rotating immediately, thereby stopping the endoscope snake bone from bending.

2. The endoscope bending angle control method according to claim 1, characterized in that: Let the average distance from the braking surface to the rotating pin be... The average distance from the locking hook to the rotating pin is The leverage ratio Setting the lever ratio k reduces the frictional force required between the braking surface and the friction surface, thereby reducing the restoring force of the spring in step 2-1; simultaneously, the lever ratio It can also amplify the restoring force of the spring and increase the locking force between the power end diameter of the locking block and the outer wall of the transmission shaft in step 2-2.

3. The endoscope bending angle control method according to claim 1 or 2, characterized in that: In steps 1-2, while the resistance end of the locking block moves radially inward, the power end of the locking block moves radially outward simultaneously. The power end of the locking block can be locked with the locking groove on the outer wall of the transmission shaft through the locking hook. By making the depth of the locking groove greater than the radial compression of the spring, the power end of the locking block remains in the locking groove after moving radially outward simultaneously. Therefore, in step 2-2, the power end of the locking block can move radially inward under the guidance of the locking groove.

4. The endoscope bending angle control method according to claim 3, characterized in that: In step 2-2, the locking groove is a V-shaped groove set on the drive shaft. When the endoscope snake stops bending, the locking block locks the drive shaft by setting the opening angle β of the V-shaped groove; wherein, the opening angle β of the V-shaped groove is obtained by the following calculation formula: ； In the formula, The leverage ratio of the locking block; For the restoring force of shrapnel; for The coefficient of friction between the groove and the locking hook; The radius of the drive shaft; This refers to the torque of the drive shaft.

5. The endoscope bending angle control method according to claim 1, characterized in that: The coefficient of dynamic friction between the braking surface and the friction surface is 0.02~0.

08.

6. The endoscope bending angle control method according to claim 1, characterized in that: Using Hertzian contact theory, the parameters of the triangular tooth surface were calculated and designed, including the bus contact area between the braking surface and the triangular tooth surface. The specific formulas for calculating the tooth pitch P and the total number of teeth N are as follows: ； ； ； in: ； In the formula, For the restoring force of shrapnel; W is the radius of the braking surface; W is the axial thickness of the braking surface. The equivalent elastic modulus of the locking block and the locking wheel; and These are the elastic moduli of the materials corresponding to the locking block and the locking wheel, respectively. and These are the Poisson's ratios of the materials corresponding to the locking block and the locking wheel, respectively. The minimum locking resolution for the friction mating surfaces is set based on the endoscope's bending stop accuracy. To lock the inner diameter of the wheel.

7. The endoscope bending angle control method according to claim 1, characterized in that: In step 1-1, the maximum radial compression δ of the spring and the restoring force of the spring in step 2-1 The following calculation formula must be met: ； ； In the formula, k is the lever ratio of the locking block; n is the number of locking blocks; and r is the distance from the lowest point of the locking groove to the center axis of the drive shaft. T is the torque of the drive shaft; R is the initial radius of curvature of the spring in its natural, uncompressed state. E is the elastic modulus of the spring; b is the width of the longitudinal section of the spring; h is the height of the longitudinal section of the spring.

8. The endoscope bending angle control method according to claim 2, characterized in that: In steps 1-2 and 2-2, the maximum rotation angle θ of the locking block is related to the maximum radial compression δ of the spring, and the specific calculation formula is as follows: ； In the formula, This is the absolute distance from the pivot point of the locking block to the center point of the drive wheel; This represents the maximum rotation angle of the drive wheel.

9. An endoscope bending angle control device that stops as it bends, characterized in that: The endoscope bending angle control method according to any one of claims 1-8 is adopted.

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