Flexure structure

Abstract

To provide a bent structure of which flexural rigidity is partially changed in an axial direction with a simple structure.SOLUTION: A bent structure comprises an inner coil part 3 and an outer coil part 5, corresponding wound parts 7a, 9a of the inner coil part 3 are fitted between adjacent wound parts 15a, 17a, 19a of the outer coil part 5, and as a whole, bending and extension according to flexural rigidity are possible. By partially changing an amount of deflection against a load in an axial direction of at least one of the inner coil part 3 and the outer coil part 5, the flexural rigidity is partially changed in the axial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a bending structure used for a joint functional part such as a robot.

Background Art

[0002] As a conventional bending structure, for example, as in Patent Document 1, there is one that partially changes the bending rigidity in the axial direction according to the application or the like.

[0003] The bending structure of Patent Document 1 is a flexible tube of an endoscope and has a rigidity variable device including a coil pipe and a core material. The rigidity variable device partially improves the bending rigidity of the flexible tube by increasing the tensile stress of the core material when the coil pipe bends.

[0004] In such a bending structure, since it is necessary to cooperate the coil pipe and the core material, there is a problem that although the rigidity can be partially improved in the axial direction, the structure becomes complicated.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem to be solved is that the structure for partially changing the rigidity in the axial direction is complicated.

Means for Solving the Problems

[0007] The present invention includes an inner coil part and an outer coil part, and a corresponding coil part of the inner coil part is fitted between adjacent coil parts of the outer coil part is entirely but according to the bending rigidity te bending and stretching canIt is possible to provide a bent structure 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 with respect to the axial load.

Effect of the Invention

[0008] According to the present invention, the bending rigidity can be partially changed in the axial direction with a simple structure.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiment for Carrying Out the Invention

[0010] The object of changing the bending rigidity partially in the axial direction with a simple structure is achieved by partially changing the amount of deflection with respect to the axial load in at least one of the inner coil portion and the outer coil portion constituting the bending structure.

[0011] That is, the bending structure (1) includes an inner coil portion (3) and an outer coil portion (5), and corresponding winding portions (7a, 9a) of the inner coil portion (3) are fitted between adjacent winding portions (15a, 17a, 19a) of the outer coil portion (5), enabling bending and extension according to the bending rigidity as a whole.

[0012] This bending structure (1) has a bending rigidity that changes partially in the axial direction by partially changing the amount of deflection of at least one of the inner coil portion (3) and the outer coil portion (5) with respect to the axial load.

[0013] At least one of the inner coil portion (3) and the outer coil portion (5) may be configured to include a main body coil portion (7) whose pitch is partially expanded in the axial direction, and one or more sub-coil portions (9) in which winding portions (9a) are located within the expanded pitch of the main body coil portion (7). In this case, the sub-coil portion (9) may have the same pitch as the expanded pitch of the main body coil portion (7). However, the pitch of the sub-coil portion (9) does not necessarily have to be the same as the expanded pitch of the main body coil portion (7).

[0014] At least one of the inner coil portion (3) and the outer coil portion (5) may be configured such that the pitch is partially formed narrower in the axial direction, and the pitch formed narrower is expanded and an initial tension is applied by fitting the winding portion (23a) of the inner coil portion (3) between adjacent winding portions (15a) of the outer coil portion (5).

[0015] At least one of the inner coil portion (3) and the outer coil portion (5) may be configured to include a soft coil portion (25) made of a relatively soft material and a hard coil portion (27) made of a relatively hard material.

[0016] At least one of the inner coil portion (3) and the outer coil portion (5) may be configured to include a small-diameter coil portion (29) having a relatively small wire diameter of the winding portion (29a) and a large-diameter coil portion (31) having a relatively large wire diameter of the winding portion (31a).

Embodiment

[0017] FIG. 1 is a cross-sectional view showing a bending structure according to Embodiment 1 of the present invention, and FIG. 2 is a schematic cross-sectional view showing a cross-section of the winding portion of the bending structure.

[0018] The bending structure 1 is applied to joint functional parts of various devices such as medical and industrial devices such as manipulators, robots, and actuators, and enables relative displacement of the members on the device side coupled to both sides by bending and extending operations.

[0019] The bending structure 1 of the present embodiment includes an inner coil portion 3 and an outer coil portion 5, and is configured such that the rigidity changes partially in the axial direction. The axial direction means the direction along the axis of the bending structure 1, and it is not necessary to strictly interpret it, and it also includes a direction slightly inclined with respect to the axis.

[0020] In the bending structure 1 of the present embodiment, in both the inner coil portion 3 and the outer coil portion 5, the bending rigidity changes partially by partially changing the amount of deflection with respect to the axial load.

[0021] Note that, in order to partially change the bending rigidity of the bending structure 1, it is sufficient to partially change the amount of deflection with respect to the axial load in at least one of the inner coil portion 3 and the outer coil portion 5.

[0022] This bending structure 1 can be bent and extended according to the bending rigidity as a whole, and the portion with relatively high bending rigidity is difficult to bend.

[0023] Figs. 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 bending structure 1, Fig. 3(A) shows the main body coil portion 7, and Fig. 3(B) shows the sub-coil portion 9.

[0024] As shown in Figs. 2 and 3, the inner coil portion 3 includes a main body coil portion 7 and a sub-coil portion 9.

[0025] The main body coil portion 7 is a variable pitch coil spring having elasticity such as metal or resin, with a small pitch portion 11 on one side in the axial direction and a large pitch portion 13 on the other side.

[0026] The small pitch portion 11 has a relatively small constant pitch, and the large pitch portion 13 has a relatively large constant pitch. Therefore, the main body coil portion 7 has a configuration in which the pitch is partially expanded in the axial direction at the large pitch portion 13. The pitch is the axial gap between adjacent winding portions 7a of the main body coil portion 7.

[0027] The main body coil portion 7 has a circular cross-sectional shape of the winding portion 7a and a constant wire diameter. The material of the main body coil portion 7, the cross-sectional shape of the winding portion 7a, the wire diameter, etc. may be appropriately adopted.

[0028] The center diameter of the main body coil portion 7 is constant at the small pitch portion 11 and the large pitch portion 13. However, the center diameter of the main body coil portion 7 can also be changed in the axial direction.

[0029] The sub-coil portion 9 is a coil spring having elasticity such as metal or resin. The sub-coil portion 9 has the same pitch as the expanded pitch of the main body coil portion 7, that is, the large pitch portion 13. The center diameter of the sub-coil portion 9 is the same as that of the main body coil portion 7.

[0030] This auxiliary coil portion 9 has a winding portion 9a positioned within the pitch of the large pitch portion 13 of the main body coil portion 7. The position of the winding portion 9a of the auxiliary coil portion 9 is intermediate between adjacent winding portions 7a of the main body coil portion 7.

[0031] As a result, the combined portion of the auxiliary coil portion 9, which is on the other side of the inner coil portion 3, and the large pitch portion 13 has the same pitch as the small pitch portion 11. That is, the inner coil portion 3 has a constant pitch as a whole.

[0032] Also, due to the pitches of the auxiliary coil portion 9 and the large pitch portion 13 of the inner coil portion 3 being respectively expanded, the amount of deflection with respect to the load on the other side in the axial direction is smaller than that on one side in the axial direction. As a result, the bending rigidity of the inner coil portion 3 is improved.

[0033] Note that the combination of the auxiliary coil portion 9 and the large pitch portion 13 does not necessarily have to have the same pitch as the small pitch portion 11, and may have a pitch smaller than that of the small pitch portion 11.

[0034] Figs. 4(A) to (C) are schematic cross-sectional views showing the cross-section of the winding portion of the outer coil portion of the bent structure of Fig. 2, where Fig. 4(A) is the main body coil portion, and Figs. 4(B) and (C) are the auxiliary coil portions.

[0035] As shown in Figs. 2 and 4, the outer coil portion 5 includes a main body coil portion 15 and auxiliary coil portions 17 and 19.

[0036] The main body coil portion 15 is a coil spring having elasticity such as metal or resin. The main body coil portion 15 has the same pitch as the small pitch portion 11 of the inner coil portion 3, the cross-sectional shape of the winding portion 15a is circular, and the wire diameter is constant. Note that appropriate materials, cross-sectional shapes of the winding portion 15a, wire diameters, etc. of the main body coil portion 15 may be adopted.

[0037] The main body coil portion 15 is formed with a larger center diameter than the inner coil portion 3 and is screwed onto the outside of the small pitch portion 11 of the inner coil portion 3. As a result, the winding portion 15a of the main body coil portion 15 fits between the winding portions 7a of the small pitch portion 11 of the inner coil portion 3.

[0038] The sub-coil parts 17 and 19 are coil springs having elasticity such as metal or resin. The sub-coil parts 17 and 19 have the same pitch as the large-pitch part 13 of the main coil part 7 of the inner coil part 3. The center diameter of the sub-coil parts 17 and 19 is the same as that of the main coil part 15 of the outer coil part 5.

[0039] These sub-coil parts 17 and 19 are screwed to the outside of the combined part of the large-pitch part 13 and the sub-coil part 9 on the other side of the inner coil part 3. The winding parts 17a and 19a of these sub-coil parts 17 and 19 are respectively fitted between the winding parts 7a and 9a of the inner coil part 3.

[0040] The sub-coil parts 17 and 19 have the same pitch as the main coil part 15 by their combination. Therefore, the outer coil part 5 has a constant pitch as a whole.

[0041] Also, since the outer coil part 5 is formed by two sub-coil parts 17 and 19, the amount of deflection with respect to the load on the other side in the axial direction is smaller than that on one side in the axial direction. As a result, the bending rigidity of the portion corresponding to the sub-coil parts 17 and 19 of the outer coil part 5 is improved compared to the portion corresponding to the main coil part 15.

[0042] Note that the sub-coil parts 17 and 19 do not necessarily have the same pitch as the main coil part 15, and may have a pitch smaller than that of the main coil part 15.

[0043] Also, the configurations of the outer coil part 5 and the inner coil part 3 may be reversed. Since the amount of deflection with respect to the axial load may be partially changed in at least one of the inner coil part 3 and the outer coil part 5, the outer coil part 5 or the inner coil part 3 may be configured by a constant-pitch coil spring or the like that is continuous from one side to the other side in the axial direction.

[0044] Since such an outer coil part 5 is screwed to the outside of the inner coil part 3 as a whole, the bending rigidity of a part in the axial direction can be changed with a simple structure.

[0045] Further, due to the screwing between the outer coil portion 5 and the inner coil portion 3, the corresponding coil portions 7a or 9a of the inner coil portion 3 are fitted between the coil portions 15a on one side of the outer coil portion 5 and between the coil portions 17a and 19a on the other side.

[0046] With this structure, the bending structure 1 can withstand axial compression. Further, when the bending structure 1 is bent, the gap between the adjacent coil portions 15a, 17a, and 19a of the outer coil portion 5 becomes smaller on the inner side of the bend, and the gap between the adjacent coil portions 15a, 17a, and 19a of the outer coil portion 5 becomes larger on the outer side of the bend. Therefore, the length of the outer coil portion 5 at the axis during bending does not change compared to when it is straight.

[0047] For this reason, when the bending structure 1 is used to axially movably guide a flexible member such as a push-pull cable on its inner peripheral side, the path length of the flexible member can be kept constant.

[0048] Further, since the bending structure 1 of the present embodiment has relatively low bending rigidity on one side in the axial direction and relatively high bending rigidity on the other side in the axial direction, for example, when applied to an endoscope, the insertability can be improved.

[0049] In addition, in the present embodiment, only the rigidity of the other side, which is a part of the bending structure 1, is improved, but the rigidity may be improved at a plurality of locations in the axial direction.

Embodiment

[0050] FIG. 5 is a schematic cross-sectional view showing a cross-section of a coil portion of a bending structure according to Embodiment 2 of the present invention, FIG. 6 is a schematic cross-sectional view showing a cross-section of a coil portion of the inner coil portion of the bending structure, and FIG. 7 is a schematic cross-sectional view showing a cross-section of a coil portion of the outer coil portion of the bending structure. In addition, in Embodiment 2, since the basic configuration is common to Embodiment 1, the corresponding configurations are denoted by the same reference numerals and redundant descriptions are omitted.

[0051] In Example 2, the pitch of the inner coil portion 3 is partially formed to be narrow. That is, the inner coil portion 3 is constituted by a coil spring including 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 in Example 1.

[0052] The one-side coil portion 21 of the inner coil portion 3 is composed of a coil spring with an equal pitch and has the same pitch as the outer coil portion 5. The other-side coil portion 23 is composed of a close-contact coil spring, and the adjacent turns 23a in the axial direction are in close contact with each other. That is, the other-side coil portion 23 has a narrow pitch. The one-side coil portion 21 and the other-side coil portion 23 are integrally continuous.

[0053] Note that the other-side coil portion 23 does not have to be a close-contact coil spring as long as its pitch is narrower than that of the one-side coil portion 21. Also, the pitch of the one-side coil portion 21 may be smaller than the pitch of the outer coil portion 5. Conversely, the pitch of the outer coil portion 5 may be made smaller than the pitch of the one-side coil portion 21 of the inner coil portion 3. Also, the configurations of the outer coil portion 5 and the inner coil portion 3 may be reversed. Also, the pitch may be made narrow at a plurality of locations in the axial direction.

[0054] In this bending structure 1, the inner coil portion 3 and the outer coil portion 5 are screwed together, and the turns 23a of the inner coil portion 3 are fitted between the turns 15a of the outer coil portion 5, so that the narrow pitch formed between the turns 23a of the other-side coil portion 23 of the inner coil portion 3 is expanded. As a result, the turns 23a of the inner coil portion 3 are in close contact with the turns 15a of the outer coil portion 5 with a relatively high frictional force due to the urging force.

[0055] As a result, an initial tension is applied to the other side of the bending structure 1, and the bending rigidity is improved. Therefore, also in this embodiment, the bending rigidity of a part in the axial direction can be changed with a simple structure.

[0056] Note that as described above, also in the structure of Example 1, the pitch of the inner coil portion 3 or the like may be made smaller as in Example 2.

Example

[0057] FIG. 8 is a schematic cross-sectional view showing a cross-section of a wound portion of the bending structure according to Embodiment 3 of the present invention, FIGS. 9(A) and 9(B) are schematic cross-sectional views showing a cross-section of a wound portion of the inner coil portion of the bending structure, FIG. 9(A) shows a soft coil portion, and FIG. 9(B) shows a hard coil portion. In Embodiment 3, since the basic configuration is common to Embodiment 1, the corresponding configurations are denoted by the same reference numerals and redundant descriptions are omitted.

[0058] In Embodiment 3, the inner coil portion 3 is configured by a coil spring including a soft coil portion 25 on one axial side and a hard coil portion 27 on the other axial side.

[0059] The soft coil portion 25 and the hard coil portion 27 are coil springs with equal pitches, but different in material. 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.

[0060] Due to this difference in material, the hard coil portion 27 has a smaller amount of deflection with respect to an axial load than the soft coil portion 25.

[0061] The outer coil portion 5 is composed of a coil spring with an equal pitch from one axial side to the other side. The rest is the same as in Embodiment 1.

[0062] Therefore, also in this embodiment, by screwing the inner coil portion 3 and the outer coil portion 5 together, the bending rigidity of a part in the axial direction can be changed with a simple structure.

[0063] Note that the soft coil portion 25 may be provided on the other axial side, and the hard coil portion 27 may be provided on one axial side. Also, the configurations of the outer coil portion 5 and the inner coil portion 3 may be reversed. Further, soft coil portions and hard coil portions may be provided on both the outer coil portion 5 and the inner coil portion 3. Furthermore, one or both of the soft coil portion and the hard coil portion may be provided at a plurality of locations in the axial direction.

[0064] In addition, in Example 1, similar to Example 3, the auxiliary coil portions 9, 17, 19, etc. may be made of rigid coil portions. Also, in Example 2, it is also possible to make the other-side coil portion 23 a rigid coil portion and couple it to the one-side coil portion 21 by welding or the like.

Example

[0065] FIG. 10 is a schematic cross-sectional view showing a cross-section of a winding portion of a bent structure according to Example 4 of the present invention, FIGS. 11(A) and (B) are schematic cross-sectional views showing cross-sections of winding portions of an inner coil portion of the bent structure, FIG. 11(A) shows a small-diameter coil portion, and FIG. 11(B) shows a large-diameter coil portion. In Example 4, since the basic configuration is common to Example 1, corresponding components are denoted by the same reference numerals and redundant descriptions are omitted.

[0066] In Example 4, the inner coil portion 3 is constituted by a coil spring including a small-diameter coil portion 29 on one side in the axial direction and a large-diameter coil portion 31 on the other side in the axial direction.

[0067] The small-diameter coil portion 29 and the large-diameter coil portion 31 are coil springs with equal pitch, but the wire diameters of the winding portions 29a and 31a are different. That is, in the small-diameter coil portion 29, the wire diameter of the winding portion 29a is relatively small, and in the large-diameter coil portion 31, the wire diameter of the winding portion 31a is relatively large.

[0068] Due to this difference in wire diameter, the large-diameter coil portion 31 has a smaller amount of deflection with respect to an axial load than the small-diameter coil portion 29. The outer coil portion 5 is composed of a coil spring with equal pitch from one side to the other side in the axial direction. The rest is the same as in Example 1.

[0069] Therefore, also in this embodiment, by screwing the inner coil portion 3 and the outer coil portion 5 together, it is possible to change the bending rigidity of a part in the axial direction with a simple structure.

[0070] Note that the small-diameter coil portion 29 may be provided on the other side in the axial direction, and the large-diameter coil portion 31 may be provided on one side in the axial direction. Also, the configurations of the outer coil portion 5 and the inner coil portion 3 may be reversed. Further, small-diameter coil portions and large-diameter coil portions may be provided on both the outer coil portion 5 and the inner coil portion 3. Additionally, one or both of the small-diameter coil portion and the large-diameter coil portion may be provided at a plurality of locations in the axial direction.

[0071] Also, in Example 1, similar to Example 3, the sub-coil portions 9, 17, 19, etc. may be large-diameter coil portions. In Example 2, the other-side coil portion 23 may be a rigid coil portion and may be coupled to the one-side coil portion 21 by welding or the like. Further, in Example 3, the rigid coil portion 27 may be made into an even larger-diameter coil portion.

[0072] In addition, it is possible to appropriately combine the structures of Examples 1 to 4 to vary the rigidity of the bending structure 1 in the axial direction.

Explanation of Reference Numerals

[0073] 1 Bending structure 3 Inner coil portion 5 Outer coil portion 7 Main body coil portion (inner coil portion) 7a, 9a Turns 9 Sub-coil portion (inner coil portion) 11 Small pitch portion 13 Large pitch portion 15 Main body coil portion 15a, 17a, 19a Turns 17, 19 Sub-coil portion (outer coil portion) 25 Soft coil portion 27 Rigid coil portion 29 Small-diameter coil portion 31 Large-diameter coil portion

Claims

1. Comprising an inner coil part and an outer coil part, The whole in which the corresponding winding parts of the inner coil part are fitted between adjacent winding parts of the outer coil part is bendable and extensible according to the bending rigidity, By partially changing the amount of deflection of at least one of the inner coil part and the outer coil part with respect to an axial load, the bending rigidity is partially changed in the axial direction, A bending structure.

2. Comprising an inner coil part and an outer coil part, The whole in which the corresponding winding parts of the inner coil part are fitted between adjacent winding parts of the outer coil part is bendable and extensible according to the bending rigidity, A bending structure in which by partially changing the amount of deflection of at least one of the inner coil part and the outer coil part with respect to an axial load, the bending rigidity is partially changed in the axial direction, At least one of the inner coil part and the outer coil part comprises a main body coil part in which the pitch is partially expanded in the axial direction, and one or more sub-coil parts in which winding parts are located within the expanded pitch of the main body coil part, A bending structure.

3. The bending structure according to Claim 2, The sub-coil part has the same pitch as the expanded pitch of the main body coil part, A bending structure.

4. Comprising an inner coil part and an outer coil part, The whole in which the corresponding winding parts of the inner coil part are fitted between adjacent winding parts of the outer coil part is bendable and extensible according to the bending rigidity, A bending structure in which by partially changing the amount of deflection of at least one of the inner coil part and the outer coil part with respect to an axial load, the bending rigidity is partially changed in the axial direction, At least one of the inner coil part and the outer coil part has a pitch that is partially formed narrower in the axial direction, and the pitch formed narrower is expanded by fitting the winding part of the inner coil part between adjacent winding parts of the outer coil part to apply an initial tension, A bending structure.

5. Comprising an inner coil part and an outer coil part, The whole in which the corresponding winding parts of the inner coil part are fitted between adjacent winding parts of the outer coil part is bendable and extensible according to the bending rigidity, A bending structure in which by partially changing the amount of deflection of at least one of the inner coil part and the outer coil part with respect to an axial load, the bending rigidity is partially changed in the axial direction, 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, a bending structure. **Claim 6**: A bending structure comprising an inner coil portion and an outer coil portion, wherein corresponding coil portions of the inner coil portion are fitted between adjacent coil portions of the outer coil portion, and bending and extension corresponding to the bending rigidity are possible as a whole, and 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 with respect to an axial load, wherein 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 coil portion and a large-diameter coil portion having a relatively large wire diameter of the coil portion, a bending structure. **Claim 7**: The bending structure according to any one of Claims 4 to 6, wherein at least one of the inner coil portion and the outer coil portion includes a main body coil portion whose pitch is partially expanded in the axial direction, and one or a plurality of sub-coil portions whose coil portions are located within the expanded pitch of the main body coil portion, a bending structure. **Claim 8**: The bending structure according to Claim 7, wherein the sub-coil portion has the same pitch as the expanded pitch of the main body coil portion, a bending structure. **Claim 9**: The bending structure according to Claim 4, wherein 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, a bending structure. **Claim 10**: The bending structure according to Claim 4 or 5, wherein 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 coil portion and a large-diameter coil portion having a relatively large wire diameter of the coil portion, a bending structure.

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