JPH0645663Y2 - Actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an actuator configured to operate by electrically heating a driving member made of a shape memory alloy so as to actuate, for example, a bending drive of an insertion portion of an endoscope. Regarding actuators.

[Prior Art] Conventionally, a shape memory alloy is known as a drive source of an actuator. For example, in Japanese Patent Application Laid-Open No. 58-25140, a member made of a shape memory alloy is provided in the bending portion of the insertion portion of the endoscope, and the member is deformed by electrically heating to bend the bending portion. Has become.

[Problems to be Solved by the Invention] However, in these conventional techniques in which a member made of a shape memory alloy is used as a drive source of an actuator, various problems have been caused by various current experiments.

That is, in the process of heating a member made of Joule heat by energizing a member made of shape memory alloy, the member made of shape memory alloy is excessively heated by the Joule heat and the member made of shape memory alloy is driven more strongly than the original operation purpose. May result in abnormal operation.

In the case of using a specific example in the bending operation of the endoscope described above, if overvoltage or overcurrent is given to the member made of the shape memory alloy for some reason, the shape recovery beyond the original target value is performed. This causes a phenomenon that the amount of bending becomes excessive or the bending becomes sharp.

Further, overheating may damage other built-in components such as an image guide fiber and a light guide fiber, and may cause a visual field defect. Further, the wall of the body cavity may be damaged during observation inside the body cavity, and it may be difficult to remove the insertion portion.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an actuator that can ensure the safety even if a driving member made of a shape memory alloy is overheated. It is in.

[Means and Actions for Solving the Problems] In order to solve the above problems, the present invention provides a driving unit driven by a deforming operation of a shape memory alloy member having a continuous and substantially uniform cross-sectional area, and the shape memory alloy member. To hold
An actuator having first and second shape memory alloy member supporting means provided separately from the drive unit and an electric heating means for energizing and heating the shape memory alloy member, wherein the first and second actuators are provided. In a part of the shape memory alloy member held by the shape memory alloy supporting means, a small cross-sectional area portion having a cross-sectional area smaller than that of another portion having a substantially uniform cross-sectional area is formed by a notch or the like. is there.

Since the small cross-sectional area portion of this shape memory alloy member has a smaller cross-sectional area than the other portions, it has a high electric resistance value and is mechanically weaker than the other portions. Therefore, when the shape memory alloy member is energized, the small cross-sectional area part thereof has a higher temperature than other parts, rises to a considerably high temperature due to overvoltage or overcurrent, and is melted at that temperature, so that the shape memory alloy member When an overvoltage or an overcurrent is applied to, the small cross-sectional area portion is melted and the force to the drive unit can be released.

[Embodiment] FIGS. 1 to 4 show a first embodiment of the present invention. The endoscope 1 shown in FIG. 1 includes an insertion portion 2, an operation portion 3 and a universal cord 4, and a connector 6 which is detachable from a light source device 5 is provided at the extension tip of the universal cord 4.

A curved portion 7 is formed in the insertion portion 2 of the endoscope 1. The bending portion 7 is configured to be driven to bend as will be described later, so that the orientation of the distal end portion 8 of the insertion portion 2 can be changed. That is, the coil spring 9 is installed inside the curved portion 7 at the center axis thereof, and the drive coil members 11 and 12 made of a shape memory alloy are installed at the upper and lower positions thereof. The front and rear ends of the coil spring 9 and the upper and lower drive coil members 11 and 12 are fixedly provided to the support plates 13 and 14. The shape memory alloy forming the drive coil members 11 and 12 is made of, for example, a NiTi alloy, a CuZnA1 alloy, or the like, is formed into a coil, and is stored in a close-wound shape, which is shown in FIG. As shown, it is extended and fixed to the support plates 13 and 14. The transformation temperature Af of the shape memory alloy used for the driving coil members 11 and 12 is set to 30 to 60 ° C, for example.

Further, the tip ends of the drive coil members 11 and 12 are connected by a common lead wire 16, and another lead wire 17 is connected to the common lead wire 16. In addition, the driving coil member 1
Lead wires 18 and 19 are individually connected to the other ends of the terminals 1 and 12. Further, the lead wires 18 and 19 are bending operation switches formed of bidirectional contacts provided in the operation section 3 through the insertion section 2.
Separately connected to 21 fixed terminals. Further, another lead wire 22 is connected to the switching movable terminal of the bending operation switch 21. The lead wire 22 and the lead wire 17 are connected to the energizing power supply 23 provided in the light source device 5 through the universal cord 4.

FIG. 2 shows the structure of the driving coil members 11 and 12, and the respective end portions 24 and 25 of the driving coil members 11 and 12 are formed linearly and are provided in the support plates 13 and 14. It is inserted in the mounting holes 26, 27. Then, fasteners 31, 32 with collars 28, 29 are fixed to the penetrating portions of the respective end portions 24, 25 by mechanical caulking. The collars 28, 29 of the fixtures 31, 32 hit the support plates 13, 14 to support the tension of the drive coil members 11, 12. The lead wire 16 and the lead wires 18 and 19 are the fixtures 3
It is fixed with solder to 1,32.

Further, the linear proximal end portion 2 of the driving coil members 11 and 12 is
A notch 35 is formed in the middle portion of 5 as shown in FIGS. 3 and 4. Then, the cross-sectional area in this intermediate portion is reduced. Therefore, in the drive coil members 11 and 12, the middle portion where the notch 35 is provided is the easiest to cut. Then, this portion constitutes means for operating (disconnecting) when the driving coil members 11, 12 are excessively heated by energization to release the driving force of the driving portions 11, 12.

Next, the operation of the endoscope 1 having the above configuration will be described. Insertion part 2
When the bending portion 7 is bent, the bending operation switch 21 is tilted from the neutral position to the direction in which the bending operation is to be performed. For example, if tilted backward, the lead wire that leads to the upper drive coil member 11
By electrically connecting 18 and the lead wire 22, the drive coil member 11 on the upper side is energized. The upper driving coil member 11 generates heat due to its own resistance and is heated to the transformation temperature Af or higher. Therefore, the driving coil member
11 restores the tightly wound state, which is the initial memory shape, and drives the bending portion 7 to bend upward by this restoring force.

If such an operation is normally performed, there is no problem, but if an overvoltage or an overcurrent is applied to the driving coil members 11 and 12 for some reason, the driving coil members 11 and 12 will not be affected.
Causes overheating. Then, the middle portion of the end portion 25 provided with the notch 35 having the smallest cross-sectional area, that is, the resistance value partially increases, becomes higher in temperature and is broken. Also,
Since this small cross-sectional area portion is formed thin, it is weak in terms of force and easily melts due to high temperature.

Therefore, the driving force of the driving coil members 11 and 12 is released, and further bending is not caused, and the bent state is released.

FIG. 5 shows a second embodiment of the present invention. This embodiment does not form the notch 35 in the middle of the proximal end 25 of the driving coil members 11 and 12, but the narrow diameter portion 41 over the entire length of the proximal end 25. It is a thing. This small diameter part
41 penetrates through the mounting holes 26, 27 formed in the support plates 13, 14, and fixing ends 31, 26 with collars 28, 29 are attached to the penetrating tips.
32 is fixed by mechanical caulking. The collars 28, 29 of the fixtures 31, 32 hit the support plates 13, 14 to receive the tension of the drive coil members 11, 12. The lead wire 16 and the lead wires 18 and 19 are fixed to the fixtures 31 and 32 by soldering. The other structure is similar to that of the first embodiment.

Thus, also in this embodiment, the driving coil member 1
The parts of the small-diameter portion 41 of 1,12 are the easiest to cut mechanically. Moreover, when the driving coil members 11 and 12 are energized,
The largest amount of heat is generated due to its own resistance. Therefore, even if there is no problem in normal operation, if overvoltage or overcurrent is applied to the driving coil members 11 and 12 for some reason, the cross-sectional area is the smallest, that is, the resistance value is partially large. The small-diameter portion 41, which has become higher, becomes hotter and breaks.

Therefore, the driving force of the driving coil members 11 and 12 is released, and further bending can be prevented and the bent state can be released.

FIG. 6 shows a third embodiment of the present invention. In this embodiment, as in the second embodiment, the small diameter portion 41 is formed over the entire length of the proximal end portion 25 of the driving coil members 11 and 12, and further,
Fixtures 31 and 32 with collars 28 and 29 are fixed to the small-diameter portion 41 by mechanical caulking, and the fixtures 31 and 32 interpose a fixing ring 45 made of a heat-soluble material. Support plate 1
The difference is that they were supported by 3,14. The heat-soluble material forming the fixing ring 45 is appropriately selected from polyurethane resin, vinyl chloride resin and the like.

Thus, also in this embodiment, the driving coil member 1
The parts of the small diameter part 41 of 1,12 are the easiest to cut mechanically,
Further, when excessive heat is generated, the fixing ring 45 made of a heat-soluble material is melted and separated from the support plates 13 and 14.

Therefore, the driving force of the driving coil members 11 and 12 is released, and further bending can be prevented and the bent state can be released.

7 and 8 show a fifth embodiment of the present invention. In this embodiment, an actuator that performs a contraction operation in the axial direction is configured. This is one in which both ends of a wire 55 made of a shape memory alloy are fixed to mounting members 56 and 57, respectively, and between the mounting members 56 and 57. Bias coil spring 5
Insert 8. Also, one mounting member 56 has a rod 58
Is fixed. Further, lead wires 59 and 59 are connected to both ends of the wire 55 made of a shape memory alloy, and the lead wires 59 and 59 are connected to a power supply 61 for energization.

As shown in FIG. 8, small diameter portions 62, 63 are formed on the end side portion of the wire 55 made of shape memory alloy, and the lead wires 59, 59 are soldered to the small diameter portions 62, 63. It is connected by attachment.

Thus, in this actuator, the bias coil spring 58 applies a force in the extension direction to the attachment members 56 and 57, whereby the wire 55 made of the shape memory alloy is subjected to an extended strain.

Therefore, when the wire 55 made of a shape memory alloy is energized by the energization power source 61 through the lead wires 59, 59, the wire
55 tries to return to its original length. Also, when the power is turned off,
Restore the initial state. By repeating this, the rod 60 can be reciprocally driven in the axial direction.

When such an operation is normally performed, there is no problem, but if an overvoltage or an overcurrent is applied to the wire 55 for some reason, the wire 55 will be overheated. Then, the small-diameter portions 62, 63 having the smallest cross-sectional area, that is, the resistance value partially increased, become higher in temperature and break.

Therefore, the driving force of the wire 55 is released and the stability is secured.

The present invention is not limited to the above embodiments.

[Effects of the Invention] As described above, the present invention is such that a part of the shape memory alloy member held by the first and second shape memory alloy supporting means has a substantially uniform cross-sectional area due to, for example, a notch. A small cross-sectional area portion having a cross-sectional area smaller than that of another continuous portion is formed, and the small cross-sectional area portion of this shape memory alloy member has a smaller cross-sectional area than other portions, and thus has a high electric resistance value. Also,
It is also weaker than other parts. Therefore, when the shape memory alloy member is energized, the small cross-sectional area portion has a higher temperature than the other portions, and the temperature rises to a considerably high temperature due to overvoltage or overcurrent, and the material is melted at that temperature. Therefore, when an overvoltage or overcurrent is applied to the shape memory alloy member,
The small cross-sectional area is melted and the force applied to the drive unit can be released, an excessive drive force does not work, and safety can be ensured.

[Brief description of drawings]

FIG. 1 is a schematic structural explanatory view of an endoscope to which the first embodiment is applied, FIG. 2 is a sectional view of a state where the driving coil member is mounted, and FIG. 3 is a driving coil member thereof. FIG. 4 is a side sectional view of the mounting main part of the driving coil member, FIG. 4 is a vertical sectional view of the mounting main part of the driving coil member, and FIG. 5 is a side sectional view of the mounting main part of the driving coil member in the second embodiment. FIG. 6 is a side sectional view of an essential part for mounting a driving coil member in the third embodiment, FIG. 7 is a side sectional view of an actuator in the fourth embodiment, and FIG. It is a sectional side view of a part. DESCRIPTION OF SYMBOLS 1 ... Endoscope, 2 ... Insertion part, 7 ... Bending part, 11,12 ... Driving coil member, 16,17,18,19,22 ... Lead wire, 23 ... Energizing power supply, 35 ... Notch, 41 … Thin portion, 45… Fixing ring, 51… Heat shrink tube, 55… Wire, 62,63… Thin portion.

Claims (1)

[Scope of utility model registration request] 1. A drive unit that is driven by a deforming operation of a continuous shape memory alloy member having a substantially uniform cross-sectional area, and a first unit provided to be spaced apart from the drive unit for holding the shape memory alloy member. An actuator having a second shape memory alloy member supporting means and an electric heating means for energizing and heating the shape memory alloy member, wherein the shape held by the first and second shape memory alloy supporting means An actuator characterized in that a small cross-sectional area portion having a cross-sectional area smaller than that of another portion where the cross-sectional area continues substantially uniformly is formed in a part of the memory alloy member.