JP2000262464A - Multi-directional bending mechanism, and head oscillating structural body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-directional bending mechanism easily bendable in any direction, without impairing flexibility of a long article, and suitable for reduction in diameter when bending the long article such as an endoscope in a multiple direction. SOLUTION: This multi-directional bending mechanism comprises a bias coil spring 2 arranged on an endoscope body 1, three shape memory alloy coil springs 3 continuously arranged on the outer circumference of the bias coil spring 2 with angular intervals of 120 deg., and nodal rings 4 fixed with specified intervals in the longitudinal direction of the bias coil spring 2, having fixed portions to the shape memory alloy coil springs 3. When the bias coil spring 2 is densely wound, the bias coil spring 2 and three shape memory alloy coil springs 2 are in a balanced condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-directional bending mechanism capable of bending a long body having a bent portion in multiple directions, and a swing structure using the same. The present invention relates to a multidirectional bending mechanism that can be suitably used for a ruled body.

[0002]

BACKGROUND OF THE INVENTION One of the applications of a bending mechanism is, for example,
A swing endoscope that allows the distal end portion of the endoscope to be bent in multiple directions is exemplified. Conventionally, as a bending mechanism used in a swinging endoscope, a pulling wire having one end fixed to the distal end side of the insertion portion of the endoscope and the other end fixed to the operation portion on the hand side is provided in the operation portion. In some cases, by operating an operation knob, the pulling wire is directly pulled to bend the endoscope tip in a desired direction. However, such a swiveling endoscope requires a high level of skill in operation, and cannot be said to be an ideal method.

As an alternative to such a method, for example, Japanese Patent Application Laid-Open No. Hei 4-227223 discloses that one end of a pulling wire extending to an operation section of an endoscope is connected to an actuator made of a shape memory alloy coil. A bending mechanism has been proposed in which the actuator is driven to pull a pulling wire and swing the endoscope end. However, according to the bending mechanism, when the length of the insertion portion of the endoscope is long, or when the conduit for inserting the endoscope is complicatedly bent, due to friction or elongation of the pulling wire, There is a problem that the endoscope does not perform a swing operation even when the actuator is driven, or the device becomes large in size to obtain a large driving force for performing the swing operation.

[0004] As another example of a swinging endoscope using an actuator composed of a shape memory alloy coil, a method in which a metal coil spring and a shape memory alloy coil actuator are arranged in a bending portion has been proposed. The shape memory alloy coil actuator has to increase the strain at the time of mounting when increasing the operating power generation force, but in this case, there is a problem that the bent portion buckles due to the shape recovery force generated at the time of mounting. . In order to solve this problem, a method of using a metal coil spring as a bias spring to antagonize the shape recovery force has been used.

[0005] However, since the shape memory alloy coil actuator has a wider elastic deformation range than a normal metal bias spring, it is necessary to increase the wire diameter of the metal coil spring in order to antagonize it. Is not suitable for diameter reduction because of the size increase. Another problem is that in the above structure, since the pitch of the metal coil spring is larger than the wire diameter, when the shape memory alloy coil actuator is driven by heating, in addition to the force in the bending direction, There is an inconvenience that a force in the direction of compressing the bent portion acts and the force in the bending direction suffers a loss.

[0006]

SUMMARY OF THE INVENTION Therefore, according to the present invention, when a long body such as an endoscope is bent in multiple directions, the long body can be easily bent in any direction. It is an object of the present invention to provide a multi-directional bending mechanism that is suitable for reducing the diameter without impairing flexibility and that can arrange a plurality of bending portions.

[0007]

According to the present invention, there is provided a multidirectional bending mechanism comprising: a bias coil spring disposed at a center axis position; and a plurality of shape memory alloy coil springs disposed in parallel on the outer periphery of the bias coil spring. A node ring fixed at a predetermined interval in the longitudinal direction of the bias coil spring, and having a fixing portion with the shape memory alloy coil spring, when the bias coil is in a tightly wound state. The bias coil spring and the plurality of shape memory alloy coil springs are configured to exhibit an antagonistic state.

Further, the swing structure of the present invention is an elongated body having a partial bending portion, such as an endoscope having a bending portion at the distal end, wherein the multi-directional bending mechanism is provided with the multi-directional bending mechanism. It is characterized by being incorporated in a bent portion.

[0009]

The multi-directional bending mechanism constructed as described above, for example, assumes that the shape memory alloy coil spring is in a contracted state and stores one of a plurality of shape memory alloy coils.
When the book is heated, the coil contracts, and the nodes between which the coil is fixed move in directions approaching each other. As a result, it bends in a desired direction. In this case, in the present invention, when the bias coil is in a close wound state, the bias coil spring and the plurality of shape memory alloy coil springs are configured to exhibit an antagonistic state. When the power supply is driven, the bias coil is in a tightly wound state, so that a force in the direction of compressing the bent portion does not act. Therefore, only the force in the bending direction is applied, and the generated power of the operating power is effectively used. Can be.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing a multi-directional swing endoscope to which the multi-directional bending mechanism of the present invention is applied. Referring to the drawings, the endoscope main body 1 has a bent portion 10 on the distal end side, a bias coil spring 2 is attached to the center axis position of the bent portion 10, and the endoscope main body 1 is disposed therein. They are arranged in a stored manner. The bias coil spring 2 is a compression coil spring, and is fixed to the bent portion 10 in a compressed state. Reference numeral 4 denotes a node ring, and a plurality of nodes are attached to the bias coil spring 2 at regular intervals in the longitudinal direction.

Around the bias coil spring 2, a shape memory alloy coil spring 3 serving as an actuator for performing a swing drive is disposed every 120 degrees with respect to the center axis of the endoscope body 10. ing. The actuators formed of the shape memory alloy coil springs 3 are respectively fixed to the periphery of the node ring 4 so that the bias coil spring 2 and the plurality of shape memory alloy coil springs 3 can be organically linked. It has been done.

Each of the shape memory alloy coil springs 3 has a tightly wound shape stored therein, and is attached in an extended state. The coil springs 3 are connected to the lead wires 25, respectively, and are capable of performing an operation of recovering the shape to a tightly wound state by heating with a conducting means (not shown). The above-described multi-directional bending mechanism and the endoscope main body 1 are housed in an outer skin 5.

In the present invention, the bias coil spring 2
Is characterized in that the bias coil spring 2 and the plurality of shape memory alloy coil springs 3 are assembled so as to antagonize each other when the coil is in a close wound state. That is, when exemplified in the above embodiment, the force of the bias coil spring 2 in the tightly wound state and the force of the plurality of shape memory alloy coil springs 3 in the extended state connected to the bias coil spring 2 via the node ring 4 are combined. Each spring force is adjusted so as to be balanced and to maintain the bent portion 10 in the upright state in normal times. When bending, the shape memory alloy coil spring 3 positioned in the intended swing direction is energized and heated to recover the shape, thereby swinging in a desired direction. FIG. 2 shows a state where the head is swung.

As the bias coil spring 2, various metal springs can be used irrespective of their material as long as they can antagonize the shape recovery force of the shape memory alloy coil spring 3 at room temperature. Therefore, a bias coil spring utilizing the superelastic effect of a shape memory alloy is preferable. In order to reduce the diameter, it is necessary to reduce the wire diameter of the bias spring. However, if the wire diameter is reduced, the spring constant becomes small, and the bias spring cannot compete with the shape memory alloy coil spring 3. In order for a bias spring having a reduced wire diameter to compete with the shape memory alloy coil spring 3, it is necessary to increase the shear strain of the bias spring. However, since a normal metal spring has a small elastic deformation range, the shear strain is reduced. If it is increased, plastic deformation occurs, and it cannot be used as a spring. On the other hand, a super-elastic coil spring can be used as a spring even if a large shear strain is applied due to its wide elastic deformation range.

The transformation temperature of the shape memory alloy bias spring may be lower than the transformation temperature of the shape memory alloy coil spring 3, and is particularly preferably lower than room temperature. In this way, it is preferable to antagonize the stress caused by the superelasticity of the lower transformation temperature (bias spring) and the elasticity of the higher transformation temperature of the two types of shape memory alloy coils having different transformation temperatures. It is an embodiment. Two types of shape memory alloy coils having different transformation temperatures are, for example, Ti-Ni
When an alloy is used, it can be prepared by a method using a different composition ratio of Ni, or using a material having different shape memory heat treatment conditions.

In order to enable bending in multiple directions, a plurality of shape memory alloy coil springs 3 are arranged around a plurality of bias coil springs. In the above embodiment, the example in which the shape memory alloy coil spring 3 is arranged every 120 degrees with respect to the center axis of the bias coil spring 2 has been described. And many may be arranged.

[0017]

Embodiment 1 A specific embodiment will be described below. In this embodiment, an example in which the multi-directional bending mechanism of the present invention is applied to a multi-directional swing endoscope will be described. More specifically, referring to FIG. 1, the endoscope main body 1 has a bent portion 10 on the distal end side, and a bias coil spring 2 made of a superelastic coil is attached to the center of the bent portion 10. Inside diameter 0.8m inside
m of the endoscope main body 1 is inserted. The super-elastic coil spring is a compression coil spring, and is fixed to the bent portion 10 in a compressed state. The superelastic coil spring 2 has a transformation temperature of 10
° C (Af point), wire diameter 0.2 mm, coil outer diameter 1.4 m
m, a pitch of 1.2 mm, and a number of windings of 25 were mounted in a longitudinal direction by using five pieces in a state compressed to 5 mm.

Around the superelastic coil spring 2, an actuator composed of a shape memory alloy coil spring 3 serving as a driving unit is disposed at every 120 degrees with respect to the center axis of the endoscope main body 1. In the present embodiment, three drive parts each having one shape memory alloy coil spring 3 folded back at the tip are attached to three places. The shape memory alloy coil spring 3 has a transformation temperature of 65 ° C. (Af point), a wire diameter of 0.1 mm, a coil outer diameter of 0.3 mm, a pitch of 0.1 mm, a number of windings of 20, and a natural length of 20 mm (excluding the mounting portion). 27.5m
m and fixed. The superelastic coil spring 2 and the shape memory alloy coil spring 3 were fixed to a node ring 4 provided at intervals in the longitudinal direction.

The size of the superelastic coil spring 2 was selected so that when it antagonized the shape memory alloy coil spring 3 at room temperature, it would be in a tightly wound state. The node ring 4 has a thickness of 0.
A 4 mm polyamideimide sheet prepared by excimer laser processing was used, and the outer diameter was 2.75 mm. A lead wire 25 is connected to each of the shape memory alloy coils 3 used in the drive unit, and a shape recovery operation can be performed by energizing and heating. An endoscope having a multidirectional bending mechanism was produced by attaching an outer skin having an outer diameter of 3 mm to the outer periphery of this structure.

As a result of operating the bending mechanism of the endoscope obtained as described above, 100
As a result of applying a current of mA, 3
A swing motion of 0 degrees was possible.

If the bending mechanism as shown in the above embodiment is arranged at two or more points of the endoscope, inflection points can be set at multiple points in the longitudinal direction, so that a more complicated insertion Applicable to the target. Further, by arranging two or more sets of the bending mechanisms in series, it is possible to increase the swing angle or to bend the distal end into an arbitrary shape within a predetermined swing angle.

[0022]

According to the multi-directional bending mechanism and the swing structure of the present invention as described above, since the actuator composed of the shape memory alloy coil spring is disposed in the bent portion, it becomes unnecessary to use a pulling wire. As a result, there is no danger of a loss of force due to friction between the pulling wire and the other mechanism, and the size of the actuator for bending and the swing angle can be improved.

Further, since the bias coil spring is configured to antagonize the shape memory alloy coil spring when the bias coil spring is in the tightly wound state, loss of force in the compression direction during bending operation is prevented, and the force is effectively generated only in the bending direction. Power can be used. Therefore, a large swing angle can be obtained irrespective of the miniaturization, and the effect of improving the functionality of the endoscope when incorporated in an endoscope or the like is achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a swinging endoscope using a multi-directional bending mechanism of the present invention.

FIG. 2 is a perspective view showing a bent state of the endoscope of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Endoscope main body 10 Bending part 2 Vice coil spring 25 Current lead 3 Shape memory coil spring 4 Section ring 5 Skin

Claims (2)

[Claims] 1. A bias coil spring disposed at a center axis position, a plurality of shape memory alloy coil springs disposed parallel to an outer periphery of the bias coil spring, and a predetermined interval in a longitudinal direction of the bias coil spring. And a node ring having a fixing portion for fixing the shape memory alloy coil spring to the bias coil spring and the plurality of shape memory alloys when the bias coil is in a tightly wound state. A multidirectional bending mechanism characterized in that the coil spring is configured to exhibit an antagonistic state. 2. A long body having a partially bent portion, wherein the multidirectional bending mechanism according to claim 1 is incorporated in the bent portion.