JP7701848B2 - bending structure - Google Patents

Description

The present invention relates to a bending structure used in a joint function part of a robot, etc.

Conventional bending structures include those in which the bending rigidity is partially changed in the axial direction depending on the application, etc., as in Patent Document 1, for example.

The bending structure of Patent Document 1 is a flexible tube for an endoscope, and has a stiffness varying device that includes a coil pipe and a core material. The stiffness varying device partially improves the bending stiffness of the flexible tube by increasing the tensile stress of the core material when the coil pipe is bent.

In such a bent structure, the coil pipe and the core material must work together, so although it is possible to partially improve the rigidity in the axial direction, there is a problem in that the structure becomes complicated.

International Publication No. 2017/203740

The problem to be solved was the complexity of the structure that partially changes the rigidity in the axial direction.

The present invention provides a bending structure comprising an inner coil portion and an outer coil portion, in which adjacent winding portions of the outer coil portion are fitted between corresponding winding portions of the inner coil portion, and in which the entire structure can be bent and extended according to its bending rigidity, and in which the bending rigidity is partially changed in the axial direction by partially changing the amount of deflection of at least one of the inner coil portion and the outer coil portion in response to an axial load.

The present invention allows partial change in bending stiffness in the axial direction with a simple structure.

FIG. 1 is a cross-sectional view showing a bent structure according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing a cross section of a winding portion of the bent structure of FIG. 3A and 3B are schematic cross-sectional views showing cross sections of the winding portions of the inner coil portion of the bent structure of FIG. 2, with FIG. 3A showing the main coil portion and FIG. 3B showing the sub-coil portion. 4(A) to (C) are schematic cross-sectional views showing the cross-sections of the winding portions of the outer coil portion of the curved structure of FIG. 2, with FIG. 4(A) being the main coil portion and FIGS. 4(B) and (C) being the sub-coil portion. FIG. 5 is a schematic cross-sectional view showing a cross section of a winding portion of a bent structure according to a second embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing a cross section of a winding portion of the inner coil portion of FIG. FIG. 7 is a schematic cross-sectional view showing a cross section of a winding portion of the outer coil portion of FIG. FIG. 8 is a schematic cross-sectional view showing a cross section of a winding portion of a bent structure according to a third embodiment of the present invention. 9(A) and (B) are schematic cross-sectional views showing the cross section of the winding portion of the inner coil portion of the bent structure of FIG. 8, with FIG. 9(A) being the soft coil portion and FIG. 9(B) being the hard coil portion. FIG. 10 is a schematic cross-sectional view showing an enlarged cross section of a winding part of a bent structure according to a fourth embodiment of the present invention. 11(A) and (B) are schematic cross-sectional views showing the cross section of the winding portion of the inner coil portion of the bent structure of FIG. 10, with FIG. 11(A) showing the small diameter coil portion and FIG. 11(B) showing the large diameter coil portion.

The goal of partially varying the bending rigidity in the axial direction with a simple structure was achieved by partially varying the amount of deflection in response to an axial load in at least one of the inner coil section and the outer coil section that make up the bending structure.

That is, the bending structure (1) has an inner coil portion (3) and an outer coil portion (5), and the corresponding winding portions (7a, 9a) of the inner coil portion (3) fit between adjacent winding portions (15a, 17a, 19a) of the outer coil portion (5), allowing bending and extension according to the bending rigidity as a whole.

This bent structure (1) has a bending rigidity that varies partially in the axial direction by partially changing the amount of deflection of at least one of the inner coil section (3) and the outer coil section (5) in response to an axial load.

At least one of the inner coil section (3) and the outer coil section (5) may be configured to include a main coil section (7) whose pitch is partially expanded in the axial direction, and one or more sub-coil sections (9) whose windings (9a) are located within the expanded pitch of the main coil section (7). In this case, the sub-coil section (9) may have the same pitch as the expanded pitch of the main coil section (7). However, the pitch of the sub-coil section (9) does not have to be the same as the expanded pitch of the main coil section (7).

At least one of the inner coil section (3) and the outer coil section (5) may be configured so that the pitch is partially narrow in the axial direction, and the narrow pitch is expanded by fitting the winding section (23a) of the inner coil section (3) between the adjacent winding sections (15a) of the outer coil section (5), thereby applying initial tension.

At least one of the inner coil section (3) and the outer coil section (5) may be configured with a soft coil section (25) made of a relatively soft material and a hard coil section (27) made of a relatively hard material.

At least one of the inner coil section (3) and the outer coil section (5) may be configured to include a small-diameter coil section (29) having a relatively small wire diameter of the winding section (29a) and a large-diameter coil section (31) having a relatively large wire diameter of the winding section (31a).

Figure 1 is a cross-sectional view showing a bent structure according to Example 1 of the present invention, and Figure 2 is a schematic cross-sectional view showing a cross section of the winding portion of the bent structure.

The bending structure 1 is applied to the joint function parts of various medical and industrial devices such as manipulators, robots, and actuators, and enables the components of the device connected to both sides to be displaced relatively by bending and extending movements.

The bent structure 1 of this embodiment includes an inner coil section 3 and an outer coil section 5, and is configured so that the rigidity changes partially in the axial direction. The axial direction means the direction along the axis of the bent structure 1, and does not need to be interpreted strictly, but also includes a direction slightly tilted relative to the axis.

In the bending structure 1 of this embodiment, the bending rigidity is partially changed by partially changing the amount of deflection in response to an axial load in both the inner coil section 3 and the outer coil section 5.

To partially change the bending rigidity of the bent structure 1, it is sufficient to partially change the amount of deflection in response to an axial load in at least one of the inner coil section 3 and the outer coil section 5.

This bending structure 1 is capable of bending and extending according to its bending rigidity as a whole, and the parts with relatively high bending rigidity are less likely to bend.

Figures 3(A) and (B) are schematic cross-sectional views showing the cross-section of the winding portion of the inner coil portion 3 of the bent structure 1, where Figure 3(A) shows the main coil portion 7 and Figure 3(B) shows the sub-coil portion 9.

As shown in Figures 2 and 3, the inner coil section 3 comprises a main coil section 7 and a sub-coil section 9.

The main coil section 7 is an elastic unequal pitch coil spring made of metal, resin, etc., with a small pitch section 11 on one side in the axial direction and a large pitch section 13 on the other side.

The small pitch section 11 has a relatively small, constant pitch, and the large pitch section 13 has a relatively large, constant pitch. Therefore, the main coil section 7 has a configuration in which the pitch is partially expanded in the axial direction in the pitch section 13. The pitch is the axial gap between adjacent windings 7a of the main coil section 7.

The main coil section 7 has a circular cross-sectional shape of the winding section 7a and a constant wire diameter. The material of the main coil section 7, the cross-sectional shape and wire diameter of the winding section 7a, etc. may be any appropriate material.

The central diameter of the main coil portion 7 is constant in the small pitch portion 11 and the large pitch portion 13. However, the central diameter of the main coil portion 7 can be changed in the axial direction.

The secondary coil section 9 is a coil spring having elasticity, such as metal or resin. The secondary coil section 9 has the same pitch as the expanded pitch of the main coil section 7, i.e., the large pitch section 13. The central diameter of the secondary coil section 9 is the same as that of the main coil section 7.

The secondary coil section 9 has a winding portion 9a located within the pitch of the large pitch portion 13 of the main coil section 7. The position of the winding portion 9a of the secondary coil section 9 is midway between adjacent winding portions 7a of the main coil section 7.

As a result, the combined portion of the sub-coil section 9 and the large pitch section 13 on the other side of the inner coil section 3 has the same pitch as the small pitch section 11. In other words, the inner coil section 3 has a constant pitch overall.

In addition, because the pitch of the sub-coil section 9 and the large pitch section 13 of the inner coil section 3 are both wider, the amount of deflection due to a load is smaller on the other axial side than on one axial side. This improves the bending rigidity of the inner coil section 3.

The combination of the sub-coil section 9 and the large pitch section 13 does not need to have the same pitch as the small pitch section 11, so it may have a smaller pitch than the small pitch section 11.

Figures 4 (A) to (C) are schematic cross-sectional views showing the cross-section of the winding portion of the outer coil part of the bent structure of Figure 2, with Figure 4 (A) showing the main coil part and Figures 4 (B) and (C) showing the sub-coil part.

As shown in Figures 2 and 4, the outer coil section 5 comprises a main coil section 15 and sub-coil sections 17 and 19.

The main coil portion 15 is a coil spring having elasticity, such as metal or resin. The main coil portion 15 has the same pitch as the small pitch portion 11 of the inner coil portion 3, and the cross-sectional shape of the winding portion 15a is circular and the wire diameter is constant. The material of the main coil portion 15, the cross-sectional shape and wire diameter of the winding portion 15a, etc. may be appropriately selected.

The main coil section 15 is formed with a center diameter larger than that of the inner coil section 3, and is screwed onto the outside of the small pitch section 11 of the inner coil section 3. This allows the winding section 15a of the main coil section 15 to fit between the winding sections 7a of the small pitch section 11 of the inner coil section 3.

The secondary coil sections 17 and 19 are elastic coil springs made of metal, resin, or the like. The secondary coil sections 17 and 19 have the same pitch as the large pitch section 13 of the main coil section 7 of the inner coil section 3. The central diameter of the secondary coil sections 17 and 19 is the same as that of the main coil section 15 of the outer coil section 5.

These secondary coil sections 17, 19 are screwed to the outside of the combination of the large pitch section 13 and secondary coil section 9, which is the other side of the inner coil section 3. The windings 17a, 19a of these secondary coil sections 17, 19 are fitted between the windings 7a, 9a of the inner coil section 3, respectively.

The sub-coil sections 17 and 19, when combined, have the same pitch as the main coil section 15. Therefore, the outer coil section 5 has a constant pitch overall.

In addition, because the outer coil section 5 is formed of two strands of secondary coil sections 17 and 19, the amount of deflection due to a load is smaller on the other axial side than on one axial side. As a result, the bending rigidity of the areas of the outer coil section 5 that correspond to the secondary coil sections 17 and 19 is improved compared to the areas that correspond to the main coil section 15.

Note that the sub-coil sections 17 and 19 do not need to have the same pitch as the main coil section 15, and may have a smaller pitch than the main coil section 15.

The configuration of the outer coil section 5 and the inner coil section 3 may be reversed. Since it is only necessary to partially change the amount of deflection in response to an axial load in at least one of the inner coil section 3 and the outer coil section 5, the outer coil section 5 or the inner coil section 3 may be configured with a coil spring of equal pitch that continues from one side in the axial direction to the other side.

The outer coil section 5 is screwed to the outside of the inner coil section 3 as a whole, making it possible to change the bending rigidity in part of the axial direction with a simple structure.

In addition, by screwing the outer coil section 5 and the inner coil section 3 together, the corresponding windings 7a and 9a of the inner coil section 3 are fitted between the windings 15a on one side of the outer coil section 5 and between the windings 17a and 19a on the other side.

This structure allows the bent structure 1 to withstand axial compression. In addition, when the bent structure 1 is bent, the gaps between adjacent windings 15a, 17a, and 19a of the outer coil portion 5 on the inside of the bend become smaller, and the gaps between adjacent windings 15a, 17a, and 19a of the outer coil portion 5 on the outside of the bend become larger. Therefore, the length of the outer coil portion 5 at its axis when bent does not change compared to when it is straight.

For this reason, when the bending structure 1 is used to guide a flexible member such as a push-pull cable on its inner circumference so that it can move in the axial direction, the path length of the flexible member can be kept constant.

In addition, the bending structure 1 of this embodiment has a relatively low bending stiffness on one side in the axial direction and a relatively high bending stiffness on the other side in the axial direction, which can improve insertability when applied to an endoscope, for example.

In this embodiment, the rigidity of only one part of the bending structure 1, that is, the other side, is improved, but the rigidity may be improved at multiple points in the axial direction.

Figure 5 is a schematic cross-sectional view showing a cross section of the winding portion of a bent structure according to Example 2 of the present invention, Figure 6 is a schematic cross-sectional view showing a cross section of the winding portion of the inner coil portion of the bent structure, and Figure 7 is a schematic cross-sectional view showing a cross section of the winding portion of the outer coil portion of the bent structure. Note that in Example 2, the basic configuration is the same as in Example 1, so the same reference numerals are used for corresponding configurations and duplicated explanations are omitted.

In Example 2, the pitch of the inner coil portion 3 is formed to be narrow in some parts. That is, the inner coil portion 3 is composed of a coil spring having a one-side coil portion 21 on one side in the axial direction and an other-side coil portion 23 on the other side in the axial direction. The outer coil portion 5 is composed of a coil spring with an equal pitch from one side to the other side in the axial direction. The rest is the same as Example 1.

The coil portion 21 on one side of the inner coil portion 3 is made of a coil spring with an equal pitch, and has the same pitch as the outer coil portion 5. The coil portion 23 on the other side is made of a tightly packed coil spring, and adjacent windings 23a in the axial direction are in close contact with each other. In other words, the coil portion 23 on the other side is formed with a narrow pitch. The coil portion 21 on one side and the coil portion 23 on the other side are continuous and integral.

The other side coil section 23 does not have to be a tight coil spring as long as the pitch is narrower than that of the one side coil section 21. The pitch of the one side coil section 21 may be smaller than that of the outer coil section 5. Conversely, the pitch of the outer coil section 5 may be smaller than the pitch of the one side coil section 21 of the inner coil section 3. The configurations of the outer coil section 5 and the inner coil section 3 may be reversed. The pitch may also be narrowed at multiple points in the axial direction.

In this bent structure 1, the inner coil section 3 and the outer coil section 5 are screwed together, and the winding section 23a of the inner coil section 3 is fitted between the winding sections 15a of the outer coil section 5, widening the narrow pitch between the winding sections 23a of the other coil section 23 of the inner coil section 3. As a result, the winding sections 23a of the inner coil section 3 are forced into intimate contact with the winding sections 15a of the outer coil section 5 with a relatively high frictional force.

As a result, the other side of the bending structure 1 is given an initial tension, improving the bending rigidity. Therefore, even in this embodiment, it is possible to change the bending rigidity of part of the axial direction with a simple structure.

As mentioned above, even in the structure of Example 1, the pitch of the inner coil portion 3, etc. may be made smaller as in Example 2.

Figure 8 is a schematic cross-sectional view showing a cross section of the winding portion of a bent structure according to Example 3 of the present invention, and Figures 9(A) and (B) are schematic cross-sectional views showing a cross section of the winding portion of the inner coil portion of the bent structure, where Figure 9(A) shows the soft coil portion and Figure 9(B) shows the hard coil portion. Note that in Example 3, the basic configuration is the same as in Example 1, so the corresponding configurations are given the same reference numerals and duplicated explanations are omitted.

In the third embodiment, the inner coil portion 3 is constructed as a coil spring having a soft coil portion 25 on one axial side and a hard coil portion 27 on the other axial side.

The soft coil portion 25 and the hard coil portion 27 are coil springs with equal pitch, but are made of different materials. That is, the soft coil portion 25 is made of a relatively soft material, and the hard coil portion 27 is made of a relatively hard material.

Due to this difference in material, the hard coil section 27 deflects less in response to an axial load than the soft coil section 25.

The outer coil portion 5 is made of a coil spring with an equal pitch from one side to the other in the axial direction. The rest is the same as in Example 1.

Therefore, in this embodiment, by screwing together the inner coil portion 3 and the outer coil portion 5, it is possible to change the bending rigidity in part of the axial direction with a simple structure.

The soft coil section 25 may be provided on the other axial side, and the hard coil section 27 may be provided on one axial side. The configurations of the outer coil section 5 and the inner coil section 3 may be reversed. A soft coil section and a hard coil section may be provided on both the outer coil section 5 and the inner coil section 3. Furthermore, one or both of the soft coil section and the hard coil section may be provided at multiple locations in the axial direction.

In addition, in Example 1, the secondary coil portions 9, 17, 19, etc. may be hard coil portions, as in Example 3. Also, in Example 2, the other side coil portion 23 may be a hard coil portion and may be joined to the one side coil portion 21 by welding or the like.

Figure 10 is a schematic cross-sectional view showing a cross section of the winding portion of a bent structure according to Example 4 of the present invention, and Figures 11(A) and (B) are schematic cross-sectional views showing cross sections of the winding portion of the inner coil portion of the bent structure, where Figure 11(A) shows the small diameter coil portion and Figure 11(B) shows the large diameter coil portion. Note that in Example 4, the basic configuration is the same as in Example 1, so the corresponding configurations are given the same reference numerals and duplicated explanations are omitted.

In Example 4, the inner coil section 3 is constructed as a coil spring having a small diameter coil section 29 on one axial side and a large diameter coil section 31 on the other axial side.

The small diameter coil section 29 and the large diameter coil section 31 are coil springs with equal pitch, but the wire diameters of the windings 29a, 31a are different. That is, the small diameter coil section 29 has a relatively small wire diameter in the winding 29a, and the large diameter coil section 31 has a relatively large wire diameter in the winding 31a.

Due to this difference in wire diameter, the large diameter coil section 31 deflects less in response to an axial load than the small diameter coil section 29. The outer coil section 5 is made of a coil spring with an equal pitch from one side to the other in the axial direction. The rest is the same as in Example 1.

Therefore, in this embodiment, by screwing together the inner coil portion 3 and the outer coil portion 5, it is possible to change the bending rigidity in part of the axial direction with a simple structure.

The small diameter coil section 29 may be provided on the other axial side, and the large diameter coil section 31 may be provided on one axial side. The configurations of the outer coil section 5 and the inner coil section 3 may be reversed. A small diameter coil section and a large diameter coil section may be provided on both the outer coil section 5 and the inner coil section 3. Furthermore, one or both of the small diameter coil section and the large diameter coil section may be provided at multiple axial locations.

In addition, in Example 1, the sub-coil sections 9, 17, 19, etc. may be large-diameter coil sections, as in Example 3. In addition, in Example 2, the other-side coil section 23 may be a hard coil section and connected to the one-side coil section 21 by welding or the like. Furthermore, in Example 3, the hard coil section 27 may be an even larger-diameter coil section.

In addition, the structures of Examples 1 to 4 can be appropriately combined to change the rigidity of the bending structure 1 in the axial direction.

1 Bent structure 3 Inner coil section 5 Outer coil section 7 Main coil section (inner coil section)
7a, 9a Winding portion 9 Sub-coil portion (inner coil portion)
11 small pitch portion 13 large pitch portion 15 main body coil portion 15a, 17a, 19a winding portion 17, 19 auxiliary coil portion (outer coil portion)
25 Soft coil section 27 Hard coil section 29 Small diameter coil section 31 Large diameter coil section

Claims (10)

An inner coil portion and an outer coil portion are provided,
The entire coil in which adjacent windings of the outer coil are fitted to corresponding windings of the inner coil can be bent and stretched according to its bending rigidity,
The bending rigidity is partially changed in the axial direction by partially changing the amount of deflection of at least one of the inner coil portion and the outer coil portion against the load in the axial direction.
bending structure. An inner coil portion and an outer coil portion are provided,
The coil is capable of bending and extending in accordance with its bending rigidity as a whole, with the coil being fitted between adjacent coils of the inner coil, and the coil being fitted between adjacent coils of the outer coil,
A bent structure in which the bending rigidity is partially changed in the axial direction by partially changing a deflection amount of at least one of the inner coil portion and the outer coil portion against an axial load ,
At least one of the inner coil section and the outer coil section includes a main coil section whose pitch is partially expanded in the axial direction, and one or more sub-coil sections whose windings are located within the expanded pitch of the main coil section.
bending structure. 3. The bent structure according to claim 2,
The sub-coil portion has the same pitch as the expanded pitch of the main coil portion.
bending structure. An inner coil portion and an outer coil portion are provided,
The coil is capable of bending and extending in accordance with its bending rigidity as a whole, with the coil being fitted between adjacent coils of the inner coil, and the coil being fitted between adjacent coils of the outer coil,
A bent structure in which the bending rigidity is partially changed in the axial direction by partially changing a deflection amount of at least one of the inner coil portion and the outer coil portion against an axial load ,
At least one of the inner coil portion and the outer coil portion is formed so that the pitch is partially narrow in the axial direction, and the narrow pitch is expanded by fitting a winding portion of the inner coil portion between adjacent winding portions of the outer coil portion, thereby applying an initial tension.
bending structure. An inner coil portion and an outer coil portion are provided,
The coil is capable of bending and extending in accordance with its bending rigidity as a whole, with the coil being fitted between adjacent coils of the inner coil, and the coil being fitted between adjacent coils of the outer coil,
A bent structure in which the bending rigidity is partially changed in the axial direction by partially changing a deflection amount of at least one of the inner coil portion and the outer coil portion against an axial load ,
At least one of the inner coil portion and the outer coil portion includes a soft coil portion made of a relatively soft material and a hard coil portion made of a relatively hard material.
bending structure. An inner coil portion and an outer coil portion are provided,
The coil is capable of bending and extending in accordance with its bending rigidity as a whole, with the coil being fitted between adjacent coils of the inner coil, and the coil being fitted between adjacent coils of the outer coil,
A bent structure in which the bending rigidity is partially changed in the axial direction by partially changing a deflection amount of at least one of the inner coil portion and the outer coil portion against an axial load ,
At least one of the inner coil portion and the outer coil portion includes a small diameter coil portion having a relatively small wire diameter of the winding portion and a large diameter coil portion having a relatively large wire diameter of the winding portion.
bending structure. The bent structure according to any one of claims 4 to 6,
At least one of the inner coil section and the outer coil section includes a main coil section whose pitch is partially expanded in the axial direction, and one or more sub-coil sections whose windings are located within the expanded pitch of the main coil section.
bending structure. The bent structure according to claim 7,
The sub-coil portion has the same pitch as the expanded pitch of the main coil portion.
bending structure. The bent structure according to claim 4,
At least one of the inner coil portion and the outer coil portion includes a soft coil portion made of a relatively soft material and a hard coil portion made of a relatively hard material.
bending structure. The bent structure according to claim 4 or 5,
At least one of the inner coil portion and the outer coil portion includes a small diameter coil portion having a relatively small wire diameter of the winding portion and a large diameter coil portion having a relatively large wire diameter of the winding portion.
bending structure.

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