JPS63136014A - Active bending device for flexible tube - Google Patents

Abstract

PURPOSE:To bent the whole of the external end of a lead wire actively in an optional shape by providing a bending angle command part and a shift command part which controls currents applied to shape memory allow materials of respective segments. CONSTITUTION:A control lever for tip direction control 22 and a control lever 23 for inserting operation are operated over a look at an image from a fiber scope 9. When a manual command is sent, it is led from an input/output device 20 to a microcomputer 21, which processes it and supplies the result to respective servo-units 181-18n and 19, so that the servo-unit 181 serves as a bending angle command part. The bending of a tip segment #1 is propagated to following segments #2-#n in order in synchronism with the moving speed of a body trunk 1, which moves while bent in the shape of the large intestine 14, so that the servo-units 182-18n become the shift command part. Consequently, the many segments can be bent actively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a flexible tube that can be moved through a narrow winding passage, and in particular, to a flexible tube that is actively bent as it moves. The present invention relates to an active bending device for a flexible tube.

(Prior technology) When examining internal organs such as the stomach, intestines, and trachea of a living body, and inspecting the inside or back side of various industrial equipment that cannot be seen from the outside, such as atomic couplants, jet engines, and boilers, , a flexible endoscope that can be inserted through narrow, winding passages is used. Such endoscopes generally include a fiberscope using an optical fiber bundle inserted into a trunk made of a flexible tube.

By the way, especially in the case of medical endoscopes, the large intestine, etc. that are inserted have great mobility, so it is possible to actively bend the trunk according to the bent shape of the large intestine, etc. It is desirable that

Therefore, in conventional medical endoscopes, four wires are connected to the inner peripheral surface of the distal end of the torso, and by selectively pulling the wires from the outside, the distal end of the torso can be bent in any direction. It was possible to do so.

(Problem to be solved by the invention) However, in such a device in which only the tip of the trunk is actively bent, the other parts must be bent passively by the reaction force of the intestinal wall, etc. Not only does the insertion operation require a high level of skill, but it also gives the patient an uncomfortable feeling of pressure.

It would be better to be able to actively bend the entire torso, but with conventional bending devices that use wire tension, it is difficult to do this by using a large number of wires that do not interfere with each other. Since it must be inserted into the trunk in this way, it is necessary to make the trunk large in diameter. Therefore, such an active bending device cannot be applied to an endoscope that is required to have a diameter as small as possible.

The present invention has been made in view of the above circumstances, and its purpose is to form a flexible tube constituting the trunk of a flexible endoscope into an arbitrary shape, even though it has a small diameter. The purpose is to enable active bending.

(Means for Solving the Problem) In order to achieve this object, the present invention uses a shape memory alloy (Shape) as an actuator for bending a flexible tube.
eMemory A11oy (hereinafter abbreviated as SMA) material is used. A flexible tube is formed by connecting in series a plurality of flexible segments having flanges at both ends. A plurality of SMA materials are stretched and stretched at intervals in the circumferential direction between the flanges at both ends of each segment in a state where they are elongated and deformed at a temperature below the transformation point. Each SMA material is connected to an external control device via a lead wire inserted into the flexible tube. The control device includes a bending angle command unit that applies a command current to the SMA material of the tip segment, and controls a current to be applied to the SMA material of the subsequent segment according to the bending angle of the tip segment and the moving speed of the flexible tube. and a shift command section.

(Function) With this configuration, when a command current is applied to the SMA material of the tip segment while moving the flexible tube,
Since the SMA material has an electrical resistance about 25 to 50 times that of copper, the SMA material generates Joule heat. When the SMA material reaches a temperature above its transformation point due to the heat,
The SMA material attempts to return to its memorized original shape.

Therefore, the SMA material stretched at a temperature below its transformation point and stretched between the flanges contracts due to its own heat. As a result, the tip segment bends by a commanded angle toward the shrinking SMA material.

Then, by controlling the current applied to the SMA material of the next segment according to the tip segment and the moving speed of the flexible tube, when the first segment reaches the location where the tip segment was located, that segment It bends in the same way as the tip segment. Thus, the bending of the tip segment
It is sequentially propagated to each succeeding segment, causing the flexible tube to move in a meandering manner.

Since the lead wires may be minute, even a large number of lead wires can be inserted into a flexible tube having a sufficiently small diameter.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

In the figure, Figures 1 to 3 show an embodiment in which the active bending device for a flexible tube according to the present invention is applied to a colonoscope, and Figures 1 and 2 are longitudinal sections of the trunk of the endoscope. FIG. 3 is an explanatory diagram of the endoscope system.

As clearly shown in Figure 1.2, the trunk l is a flexible tube.
is a plurality of segments)2,2. ... are connected in series. Each segment 2 has side flanges 5.5 perpendicular to its axis attached to both ends of a stainless steel coil spring 4, which serves as a central skeleton covered by a cylindrical exterior 3. The flanges 5.5 are connected to each other by joints 6. Each segment 2 is further provided with a pair of intermediate flanges 7.7 between the flanges 5.5 at both ends. The plurality of segments 2゜2, . . . connected in this manner are entirely covered with a flexible jacket 8 made of a material similar to that of an artificial blood vessel.

In this way, each segment 2 is configured as a flexible tube having low bending rigidity but high rigidity against expansion/contraction and torsion.

A fiberscope 9 and a pair of reciprocating cooling water pipes 10, 10 are inserted into the coil spring 4 at the center of each segment 2, extending through the entire length of the trunk l from one end to the outside. Further, in the space between the outer sheath 3 and the outer sheath 8 of the coil spring 4, a pair of lead wire bundles 12 and 12 are arranged, which are made of six SMA materials, one material color, and several lead wires bundled together. .

SMA material 1 Material color 1 Fine wire material is formed into a coil spring shape with an outer diameter of about 1 mm, and the shape is memorized so that it becomes tightly wound at a temperature above the transformation point. and,
Segment 2 is stretched and deformed at a temperature below the transformation point.
It is stretched between the flanges 5.5 at both ends, and both ends are fixed to the flanges 5.5, respectively. Therefore, when the SMA material 1 is heated to a temperature above the material color 1 transformation point, it will shrink.

One set of three pieces of SMA material, one color, and three pieces of wood arranged close to each other are arranged in axially symmetrical positions on both sides of the central coil spring 4, respectively. The ends of each set of three SMA materials are connected to each other as appropriate so that they are electrically connected in series. One end of the SMA material 1 electrically connected in series in this way is connected to an independent lead wire in the lead wire bundle 12, and the other end is connected to a ground wire in the lead wire bundle 12. .

The lead wire bundle 12 is placed in the neutral plane of flexure of each segment 2 and has one trunk l! This is done in such a way that it does not affect e-quality. This lead wire bundle 12 extends through the entire length of the trunk l, extends to the outside from one end, and extends to the outside of each S.
A current can be applied to the MA material 11 independently.

The intermediate flange 7 is provided with through holes 13, 13, . . . through which the SMA material 11 and the lead wire bundle 12 are inserted.

As is clear from FIG. 3, the colonoscope has segments #1, #2, and 2, which are configured as described above. ..., the trunk 1i consisting of #n: full.

Then, the trunk 1 is inserted into the large intestine 14, and the intestinal wall and the like are observed from the tip thereof using a fiber scope 9.

Outside the trunk l, there is a servo motor 15 for inserting and moving the trunk l, a control device 16 for controlling the insertion and bending of the trunk l, and a cooling water supply through a cooling wood tube 10.10 inside the trunk l. A water pump 17 for circulating water is provided.

The control bag 2t16 is a servo unit (servo unit) as a command unit that controls the bending angle of each segment #l to #n.181. 1
82, m, 18n, and a motor servo unit 19 that controls the moving speed of the trunk l. These servo units 181 to 18n, 19 are connected to the input/output device 20.
It is operated based on instructions from the microcomputer 21 given by the microcomputer 21.

The servo units 181 to 18n that control the bending angle of each segment #1 to #n control the bending angle of the corresponding segment #1 to #n.
The SMA material 1 material 1 supplies current through the above-mentioned independent lead wires, and its servo unit 18
1 to 18n, the corresponding SMA material 1 material resistance value is fed back. In other words, the servo units/) 181 to 18n are constructed by assembling three resistors R of constant resistance value on one SMA material into a pre-fuji circuit, as shown in FIG. It consists of a circuit that feeds back the resistance value and adds it to the input signal. And each servo unit tai~181
1 is to be controlled at 1 o'clock on two sets of SMA materials 1 of corresponding segments #l to #n.

This control device 16 works as follows.

That is, when using this endoscope, these commands are manually given by a doctor who operates the tip direction control control lever 22 and the insertion operation control lever 23 while viewing the image from the fiberscope 9. Input/output device 20
After being guided to the microcomputer 21 and processed by the microcomputer 21, each servo unit 18, ~18n, 19 is passed through the input/output device 20 again.
given to. A command from the tip direction control control lever 22 is given to the servo unit 18z, and a command current is sent from the servo unit 181 to the tip segment #l, so that the tip segment #l is bent in the commanded direction and angle. . That is, this servo unit 18t serves as a bending angle command section.

A command from the insertion operation control lever 23 is given to the motor servo unit 19, and the servo motor 15 is driven based on the command signal to move the trunk l at the command speed. In addition, these commands are translated into shift commands by the microcomputer 21, and the servo units) 182 to
A command current is sent from 18n to the corresponding segments #2 to #n, and each of the segments #2 to #n is bent in the commanded direction and angle.

This shift command means that the tip segment #l is bent in synchronization with the moving speed of the trunk l, and the subsequent segments #2 to
It propagates sequentially to #n, thereby causing trunk 1 to:
It moves while bending along the bent shape of the large 11114.

That is, these servo units 182 to 18n serve as a shift command section.

Next, the action of the trunk 1 configured as shown in FIG. 1.2 will be explained.

A controlled current is applied to the SMA material 11 of each segment 2 as described above. SMA#ll is approximately 70
At temperatures below the transformation point of °C, it is relatively flexible and easy to stretch, but when heated above the transformation point, it becomes hard and returns to its memorized shape. Therefore, each SMA material 1
1 is not energized, the segment 2 extends linearly due to the elastic force of the coil spring 4.
When any one of the SMA materials 11 is energized, the SMA material 11 reaches a temperature equal to or higher than its transformation point due to Joule heat, and contracts into a memorized shape. As a result, the segment 2 bends toward the shrinking SMA material 11. The electrical resistance value of the SMA material 11 changes with phase transformation, but by controlling the input current by feeding back the resistance value as described above, the bending angle becomes the angle as commanded.

When the power supply to the SMA material 11 is stopped, the SMA material 11
is cooled by the cooling water circulating through the cooling water pipe 10 and reaches a temperature below the transformation point and loses its contractile force, so that the segment 2 is restored to its linear shape by the elastic force of the coil spring 4.

During this time, the three SMA materials 11 are set as one set and are electrically connected in series, so that the following effects can be obtained.

■ The electrical resistance of a set of three SMA materials 11 becomes extremely large. Therefore, the resistance of the lead wire that sends current to the SMA material 11 becomes negligible, and the lead wire can be made thinner. In addition, when using the change in electrical resistance value due to phase transformation of the SMA material 11 as a monitor value for the bending angle of the segment 2, the amount of change increases as the overall resistance increases, and the accurate bending angle measurement becomes possible.

(2) Since the surface area of the SMA material 11 is increased, cooling is quickly performed when the current is interrupted, and the response speed can be increased.

■ Even if each SMA material ti has a small diameter.

It is possible to obtain the same driving force as a single large-diameter one.

Thus, each lead wire, including the insulating jacket, has a diameter Q, 1
It is possible to make the lead wire bundle 12 as fine as mm, and even if independent lead wires are bundled for each segment 2, the diameter of the lead wire bundle 12 will be extremely small. Therefore, the diameter of the trunk l can be suppressed to about 10 to 15 am in total, and a fully satisfactory colonoscope can be obtained.

In this endoscope, since the SMA material 11 is arranged in an axially symmetrical position, its bending has only one degree of freedom, but considering the two-dimensional arrangement of the large parts 11i14, It can be put to practical use. In addition, if better operability is required, the tip segment 12
3 sets of SMA materials 11 are arranged at 120° intervals, and 2
It is also possible to perform bending with a degree of freedom.

5 to 7 show an embodiment in which the flexible tube active bending device according to the present invention is applied to a cardiac catheter, and FIG. 5 is a cutaway perspective view showing a part of the trunk thereof, and FIG. 7 is a perspective view showing different embodiments of synthetic resin tubes forming the skeleton of the trunk.

As is clear from FIG. 5, the trunk 30 includes a plurality of segments 33 each having flanges 32 and 32 attached to both ends of a tube 31 made of a synthetic resin material having elasticity such as silicone rubber or nylon. It is constructed by connecting them in series through. As shown in FIG. 6, the tube 31 has a working hole 35 in the center for measuring blood pressure, collecting blood, etc.
There are three sets of SMA material insertion holes 36 on the surrounding wall.
Three lead wire insertion holes 37 are provided at intervals of 120'. The flange 32 also has a center working hole 35. SMA material insertion hole 36
A center hole 38 corresponding to the lead wire insertion hole 37, an SMA material locking hole 39, and a lead wire insertion hole 40 are provided, respectively.

It is a wire-like material that is elongated and deformed at a temperature below the first transformation point on the SMA material 4, and is bent at one flange 32 side, fixed in the SMA material locking hole 39, and placed close to the inside of the tube 31. A pair of SMA material insertion holes 36 are inserted through the holes 36 arranged in the same direction. The upper end of the SMA material 4 is fixed to the SMA material locking hole 39 of the other flange 32, and the independent lead wires in the lead wire bundle 42 inserted into the lead wire insertion holes 37.40. Each is connected to the ground wire. In this way, two pieces located close to each other on the SMA material 4 are made into a set, which are mechanically in parallel and electrically in series.

Each lead wire is connected to an external control device similar to the embodiment of FIGS. 1-4.

Next, the operation of the cardiac catheter having such a trunk 30 will be explained.

A cardiac catheter is inserted into a blood vessel to reach various parts of the heart, aorta, etc. to check the state of blood circulation, etc. The insertion operation is performed under X-ray fluoroscopy, for example, by moving the body according to the curvature of the blood vessel, etc. This is done by inserting the trunk 30 while bending it.

Similar to the embodiment shown in FIGS. 1 to 3, the bending of the trunk 30 is performed by controlling the current flowing across the four SMA members of each segment 33. When , the temperature of the SMA material 4 is raised to above the transformation point by 1 ule of heat, and the SMA material 4 shrinks by 1. Therefore, the segment 33 bends toward the shrinking SMA material 41. Furthermore, when a current is applied to the two sets of SMA materials 4 and 11, the segments 33 bend toward the middle of the SMA materials 4 and 11. In this way, the trunk 30 can be bent in any direction.

Since such a cardiac catheter generally has a substantially constant body temperature, the temperature environment in which it is used is kept substantially constant. Then, when the current supply is stopped, the SMA material 4 is sufficiently cooled by body heat. Therefore, the cooling water pipes as in the embodiments of FIGS. 1 to 3 can be omitted.

Further, by forming the SMA material 4 into a wire-like material as described above, the space for accommodating the material can be extremely small. As a result, the diameter of the trunk 30 can be approximately 3 to 5 m, making it suitable as a cardiac catheter.

In the case of a cardiac catheter, it is desirable that the entire trunk 30 be able to bend with two degrees of freedom as described above, but in the case of a catheter inserted into a blood vessel etc. with relatively few bends, the tip It is also possible for only segment 33 to be able to bend in this way with two degrees of freedom, with subsequent segments 33 being able to bend only in one degree of freedom. In that case, as shown in FIG. 7, the synthetic resin tube 31 of the succeeding segment 33 is
The SMA material insertion holes 36 and the lead wire type through holes 37 may be provided at axially symmetrical positions.If the two sets of SMA material insertion holes 36 are arranged symmetrically in this way, , the number of the insertion holes 36 can be increased to make a set of 4 pieces, for example, as shown in the figure, and a stronger bending force can be applied to the 4 pieces of SMA material inserted through them. It becomes like this.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, the SM
Material A is used as an actuator, and the SMA material is heated by Joule heat by applying a current to it, causing it to contract into a memorized shape, thereby bending the flexible tube, so the actuator itself can be made small in diameter. In addition, each SMA material only needs to be connected to an external control device via a fine lead wire, and even if the lead wire is inserted through the flexible tube, it will not be necessary to connect the flexible tube to a large diameter tube. There will be no need to do so. Therefore, while the flexible tube has a small diameter, it becomes possible to actively bend each of the numerous segments that make up the flexible tube.

Then, the tip segment is bent to a commanded angle, and the bending angle is sequentially propagated to the following segments in synchronization with the moving speed of the flexible tube, so the flexible tube moves in a meandering manner. It becomes like this. Therefore, the flexible tube can be inserted smoothly even through a complicated passage, and discomfort to the patient can be reduced, especially when applied to a medical endoscope.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the trunk of a colonoscope to which the active bending device for a flexible tube according to the present invention is applied; FIG. 2 is a cross-sectional view of the trunk thereof; The figure is a system diagram of the colonoscope. FIG. 4 is a circuit diagram of a part of the endoscope control device, and FIG. 5 is a main part showing an embodiment of the trunk of a cardiac catheter to which the flexible tube active bending device of the present invention is applied. Fig. 6 is a perspective view showing a synthetic resin tube forming the trunk thereof. FIG. 7 is a perspective view showing a different example of the synthetic resin tube. l... Trunk (flexible tube) 2... Segment 5
...Flange 6...Joint 9.
...Fiberscope lO...Cooling water pipe 11...
・Shape memory alloy material 12...Lead wire bundle 14...
・Large fil (passage) 16...control device 18,
~18n... Servo unit (command section) 30... Trunk (flexible tube) 32... Flange 33... Segment 34... Joint 41... Shape memory alloy material 42... Lead Line bundle Figure 3 Figure 4

Claims (9)

[Claims] (1) A flexible tube that is moved along a winding path is configured by a plurality of flexible cylindrical segments connected in series with flanges at both ends, and between the flanges at both ends of each segment. , a plurality of shape memory alloy materials that have been elongated and deformed at a temperature below the transformation point are stretched at intervals in the circumferential direction, and each shape memory alloy material is guided to the outside through the inside of the flexible tube. a bending angle command unit that connects the independent lead wires that are connected to each other, and applies a current to the shape memory alloy material of the tip segment using the outer end of the lead wire according to the commanded bending angle;
The flexible tube is connected to a control device including a shift command section that controls the current applied to the shape memory alloy material of each succeeding segment according to the bending angle and the moving speed of the flexible tube. Bending device. (2) The active bending device for a flexible tube according to claim 1, wherein the shape memory alloy material is in the shape of a coil spring. (3) The shape memory alloy material is wire-shaped. An active bending device for a flexible tube according to claim 1. (4) The shape memory alloy material stretched between the flanges,
The flexible material according to claim 1, wherein the shape memory alloy material is formed into a plurality of sets each having a plurality of shape memory alloy materials disposed close to each other, and the plurality of shape memory alloy materials forming each set are electrically connected in series. Active tube bending device. (5) The active bending device for a flexible tube according to claim 1, wherein the shape memory alloy material is arranged at two axially symmetrical positions in each segment. (6) The active bending device for a flexible tube according to claim 1, wherein the shape memory alloy material is arranged at three positions spaced apart by 120 degrees in the circumferential direction of each segment. (7) The active bending device for a flexible tube according to claim 1, wherein a cooling water pipe for cooling the shape memory alloy material is provided in the flexible tube. (8) The flexible tube according to claim 1, wherein the flexible tube is inserted into a living body, and the shape memory alloy material is cooled by body heat. Active bending device. (9) The control device includes a resistance value feedback system that feeds back the electrical resistance value of each shape memory alloy material and controls the current applied to the shape memory alloy material. Active bending device for flexible tubes.