Flexion structure and joint function

Abstract

Provided are a flexure structure and a joint functional part, which can achieve the stabilization of the flexure movement and simplify the structure. The inner coil part (5) of the flexure structure is located inside the outer coil part (3). The outer coil part (3) has a plurality of gaps (3c) that separate the coil parts (3b) adjacent in the axial direction. The coil part (5a) of the inner coil part (5) is provided corresponding to the gaps (3c) of the outer coil part (3), contacts the adjacent coil parts (3b) of the outer coil part (3), and is fitted between the coil parts (3b). When the axial dimension of the gap (3c) of the outer coil part (3) in the free state is set as P, the number of turns of the outer coil part (3) is set as N, the diameter of the outer coil part (3) is set as R, and the wire diameter of the wire material (5a) of the inner coil part (5) is set as d, the dimension P is set within the range of πR / 4N ≤ P < d - πR / 4N.

Description

Technical Field

[0001] The present invention relates to a flexure structure provided to a joint functional part of a robot or the like, and a joint functional part using the flexure structure. Background Art

[0002] In robots, robotic arms, actuating mechanisms, etc., there are devices having joint functional parts capable of flexing / extending. In such joint functional parts, for example, there is a flexible member used as a flexure structure as in Patent Document 1.

[0003] The flexible member of Patent Document 1 is configured such that a plurality of disk elements are swingably engaged with each other, and the whole performs a flexure action by the swinging of each disk element.

[0004] Therefore, the flexible member can perform a flexure action smoothly, and can ensure rigidity against compression in the axial direction, and can realize stabilization of the flexure action.

[0005] However, since the flexible member engages a plurality of disk elements with each other, there is a problem that the structure is complicated.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-538186 Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] The problem to be solved by the present invention is that the structure becomes complicated in order to realize stabilization of the flexure action.

[0011] Means for Solving the Problems

[0012] The present invention provides a flexure structure capable of realizing stabilization of the flexure action and simplifying the structure. The flexure structure includes: an outer coil part formed of a coil-shaped wire material having a plurality of turns in the axial direction; and an inner coil part formed of a coil-shaped wire material having a plurality of turns in the axial direction and located inside the outer coil part. The outer coil part has a plurality of gaps separating adjacent turns in the axial direction, and the turns of the inner coil part are provided corresponding to the gaps of the outer coil part, and are in contact with and fitted between the adjacent turns of the outer coil part. When the axial dimension of the gap of the outer coil part in the free state is set as P, the number of turns of the outer coil part is set as N, the diameter of the outer coil part is set as R, and the wire diameter of the wire material of the inner coil part is set as d, the dimension P is set within a range satisfying πR / 4N ≤ P < d - πR / 4N.

[0013] The present invention also provides a joint function part using the above-mentioned bending structure, wherein the joint function part includes a base and a movable part displaced relative to the base, wherein the bending structure is provided between the base and the movable part and bends according to the displacement of the movable part relative to the base.

[0014] Effects of the Invention

[0015] According to the present invention, the inner coil portion is located inside the outer coil portion to form a buckled structure, so that the structure can be simplified.

[0016] Furthermore, since the winding portion of the inner coil portion is brought into contact with the adjacent winding portion of the outer coil portion and is fitted between these adjacent winding portions, the rigidity in the axial direction can be ensured.

[0017] As a result, the present invention can stabilize the flexion motion and simplify the structure.

[0018] Furthermore, by setting the gap between the winding parts of the outer coil part, when the flexure structure is bent to 90 degrees and then restored to the original state, it can be operated smoothly without getting stuck. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a cross-sectional view showing a buckling structure according to Example 1 of the present invention.

[0020] Figure 2 Yes means Figure 1 An enlarged view of a part of the buckled structure.

[0021] Figure 3 (A) means Figure 1 3 (B) is a cross-sectional view showing the length of the inner side, the middle side and the outer side of the buckling.

[0022] Figure 4 (A) Yes Figure 3 A magnified view of the lateral side of the flexion, Figure 4 (B) Yes Figure 3 Magnified view of the medial side of the flexion.

[0023] Figure 5 This is a perspective view of a robot arm having a joint function portion to which a flexure structure according to Example 2 of the present invention is applied.

[0024] Figure 6 yes Figure 5 A cross-sectional view of the robotic arm. DETAILED DESCRIPTION

[0025] The purpose of the double coil buckling structure formed by placing the inner coil part inside the outer coil part is to achieve smooth operation, stabilize the buckling motion, and simplify the structure.

[0026] The buckling structure 1 can buckle with respect to the axial direction and includes: an outer coil part 3 formed by a coil-shaped wire material 3a having a plurality of turns 3b in the axial direction; and an inner coil part 5 formed by a coil-shaped wire material 5a having a plurality of turns 5b in the axial direction and located inside the outer coil part 3.

[0027] In addition, buckling means bending or buckling the axis O of the buckling structure 1.

[0028] The outer coil part 3 has a plurality of gaps 3c that separate adjacent turns 3b in the axial direction. The inner coil part 5 is arranged such that the turns 5b correspond to the gaps 3c of the outer coil part 3, and contacts and fits between the adjacent turns 3b of the outer coil part 3.

[0029] The outer coil part 3 may have gaps 3c between each adjacent turn 3b in the axial direction, or may be configured to have gaps 3c only in a part of the axial direction.

[0030] In this buckling structure 1, when the axial dimension of the gap 3c of the outer coil part 3 in the free state is set as P, the number of turns of the outer coil part 3 is set as N, the diameter of the outer coil part 3 is set as R, and the wire diameter of the wire material 5a of the inner coil part 5 is set as d, the dimension P is set within the range of πR / 4N ≤ P < d - πR / 4N.

[0031] The free state means the state in which the buckling structure 1 is not buckled, and refers to the basic posture of a straight line or an arc.

[0032] The cross-sectional shapes of the wire materials 3a and 5a of the outer coil part 3 and the inner coil part 5 can adopt appropriate shapes with a wire diameter such as a circle or an ellipse. However, the wire material 3a of the outer coil part 3 is preferably, for example, a circle, a semicircle, a combination of a semicircle and a semi-ellipse, etc., and at least the cross-sectional shape on the inner side in the radial direction of the coil shape is an arc shape. The cross-sectional shape of the wire material 5a of the inner coil part 5 is the same. However, in the case of the inner coil part 5, it is preferably that at least the cross-sectional shape on the outer side in the radial direction of the coil shape is an arc shape.

[0033] In this case, when the buckling structure 1 buckles by 90 degrees, it is preferable that the contact angle θ between the turn 3b of the outer coil part 3 at the buckling part and the turn 5b of the inner coil part 5 in contact with the turn 3b is 30 degrees or more. The contact angle θ is the angle between the tangent line between the contacted turns 3b and 5b of the outer and inner coil parts 3 and 5 and the line connecting the buckling center C and the center c of the turn 3b of the outer coil part 3.

[0034] When the flexure is 90 degrees, it means that the central angle of the flexure portion (bend portion) of the flexure structure 1 is 90 degrees. In addition, the flexure center C refers to the center of curvature of the flexure portion. In addition, the center c of the roll 3b refers to the cross-sectional center of the roll 3b in the direction intersecting the axial direction. The upper limit of the contact angle θ is the limit that the axial dimension of the gap 3c of the outer coil portion 3 meets the above range.

[0035] In addition, when the overlap amount in the axial direction between the wire 3a of the outer coil portion 3 and the wire 5a of the inner coil portion 5 in the free state is set to a and the wire diameter of the wire 3a of the outer coil portion 3 is set to D, it is preferred that the overlap amount be set within a range satisfying a≤0.3D.

[0036] The lower limit of the overlap amount is a limit at which the dimension of the gap 3c of the outer coil portion 3 in the axial direction satisfies the above-mentioned range.

[0037] The joint function part 11 to which the bending structure 1 is applied may include a base 17 and a movable part 19 displaced relative to the base 17. In this case, the bending structure 1 is provided between the base 17 and the movable part 19 and bends according to the displacement of the movable part 19 relative to the base 17.

[0038] Example 1

[0039] [Structure of a buckled structure]

[0040] Figure 1 2 is a cross-sectional view showing a buckling structure according to Example 1 of the present invention, and circle 2 is an enlarged view showing a part thereof.

[0041] The buckling structure 1 is applied to, for example, a joint function portion of an industrial or medical robot, a robot arm, or an actuator mechanism.

[0042] The bendable structure 1 of the present embodiment is a double coil that is bendable in the axial direction, and includes an outer coil portion 3 and an inner coil portion 5 .

[0043] The outer coil portion 3 is a helical spring, which is composed of a coiled wire 3a having a plurality of coils 3b in the axial direction. In addition, the coil 3b means a circle constituting the coil shape, and the number of the coils 3b means the number of coils N (the same is true for the inner coil portion 5). The outer coil portion 3 of the present embodiment is a helical spring, which has elasticity that can be bent and restored relative to the axial direction of the coil shape.

[0044] The material of the wire 3a can be metal or resin, etc. In this embodiment, the cross-sectional shape of the wire 3a is circular.

[0045] The diameter R of the outer coil portion 3 is constant from one end to the other end in the axial direction. However, the diameter R of the outer coil portion 3 can also vary in the axial direction. Additionally, the diameter R in this embodiment is the center diameter of the coil shape of the outer coil portion 3, but it can also be the outer diameter or the inner diameter of the coil shape.

[0046] The outer coil portion 3 has a plurality of gaps (spacing) 3c that separate adjacent coil portions 3b in the axial direction from each other in the axial direction. The gaps 3c in this embodiment are formed between adjacent coil portions 3b in the axial direction, and all the gaps 3c have the same axial dimension P. However, the gaps 3c can also be provided only between a part of the coil portions 3b in the axial direction. Additionally, the axial dimension P of the gaps 3c can be varied.

[0047] The axial dimension P of the gaps 3c in the free state of the outer coil portion 3 is set within the range satisfying πR / 4N ≤ P < d - πR / 4N in relation to the number of turns N of the outer coil portion 3, the diameter R of the outer coil portion 3, and the wire diameter d of the wire material 5a of the inner coil portion 5. The setting of the dimension P can be carried out by means of the diameter R of the outer coil portion 3, the wire diameter D of the wire material 3b, the diameter r of the inner coil portion 5 described later, and the wire diameter d of the wire material 5a.

[0048] The inner coil portion 5, like the outer coil portion 3, is a helical spring formed of a wire material 5a having a plurality of coil portions in the axial direction. Thus, the inner coil portion 5 has elasticity that can bend and recover together with the outer coil portion 3 with respect to the axial direction of the coil shape.

[0049] The material of the wire material 5a of the inner coil portion 5 can be metal or resin, and the cross-sectional shape of the wire material 5a is circular.

[0050] The inner coil portion 5 is located concentrically inside the outer coil portion 3 and is threadedly engaged within the outer coil portion 3. Through this threaded engagement, the coil portions 5b of the inner coil portion 5 are located between each adjacent coil portion 3b of the outer coil portion 3. Thus, the inner coil portion 5 is configured such that the coil portions 5b are provided corresponding to the gaps of the outer coil portion 3.

[0051] Additionally, the coil portions 5b of the inner coil portion 5 contact and fit between the adjacent coil portions 3b of the outer coil portion 3 through the setting of the diameter r and the wire diameter d of the wire material 5a. Additionally, the diameter r is the center diameter of the coil shape of the inner coil portion 5, but it can also be the outer diameter or the inner diameter of the coil shape according to the diameter R of the outer coil portion 3.

[0052] Through this fitting, the wire material 3a of the outer coil portion 3 and the wire material 5a of the inner coil portion 5 are partially overlapped in the axial direction. The amount of overlap a in the axial direction is set within the range satisfying a ≤ 0.3D with respect to the wire diameter D of the wire material 3a of the outer coil portion 3.

[0053] The diameter r of the inner coil portion 5 is constant from one end to the other end in the axial direction. However, the diameter r of the inner coil portion 5 may be changed in the axial direction according to the diameter R of the outer coil portion 3 .

[0054] The wire diameter d of the wire 5a is the same as the wire diameter D of the wire 3a of the outer coil portion 3. However, the wire diameter d of the wire 5a may be larger or smaller than the wire diameter D of the wire 3a of the outer coil portion 3.

[0055] The inner coil portion 5 has a plurality of gaps (spacings) 5c that separate adjacent winding portions 5b in the axial direction. The gaps 5c are formed between adjacent winding portions 5b according to the threaded connection with the outer coil portion 3, and all the gaps 5c have the same axial dimension. However, the gaps 5c may be provided only between a portion of the winding portions 5b in the axial direction, or the axial dimensions may be different, as in the case of the outer coil portion 3.

[0056] In addition, the outer coil portion 3 and the inner coil portion 5 have gaps 3c and 5c between adjacent coils 3b and coils 5b in a separate free state. However, the outer coil portion 3 and the inner coil portion 5 may also be a structure (closed spring) in which adjacent coils 3b and coils 5b are in close contact with each other in a separate free state. Furthermore, only one of the outer coil portion 3 and the inner coil portion 5 may be a close contact spring. The separate free state is a separate free state of the outer coil portion 3 and the inner coil portion 5 when the inner coil portion 5 is not located in the outer coil portion 3.

[0057] When one or both of the outer coil portion 3 and the inner coil portion 5 are close-contact springs in a separate free state, the close-contact winding portions 3b and winding portions 5b are separated from each other by threading the inner coil portion 5 with the outer coil portion 3. Thus, one or both of the gap 3c of the outer coil portion 3 and the gap 5c of the inner coil portion 5 are formed. In this case, an initial tension can be applied to the buckling structure 1 of the double coil.

[0058] [Movement of the flexural structure]

[0059] Figure 3 (A) means Figure 1 A cross-sectional view of the buckled structure 1 in a buckled state, Figure 3 (B) is a cross-sectional view showing the lengths of the inner and outer sides of the bend. Figure 4 (A) Yes Figure 3 A magnified view of the lateral side of the flexion, Figure 4 (B) is an enlarged view of the inner side of the bend.

[0060] like Figure 1 and Figure 2As shown, when the bent structure 1 is in a straight line without bending about the axis O, the turn 5b of the inner coil portion 5 contacts the adjacent turn 3b of the outer coil portion 3 and fits between the adjacent turn 3b.

[0061] Therefore, even if an axial compressive force acts on the flexural structure 1, the roll 5b of the inner coil portion 5 and the roll 3b of the outer coil portion 3 will respectively limit the gap 3c of the outer coil portion 3 and the gap 5c of the inner coil portion 5 to become smaller due to compression, thereby suppressing the overall compression.

[0062] Therefore, the buckling structure 1 can suppress its own compression. As a result, the length L on the axis O can be kept constant, and interference with members inserted inside can be suppressed.

[0063] like Figure 3 (A)~ Figure 4 As shown in (B), when the axis O of the flexural structure 1 flexes, the gap 3c of the outer coil portion 3 on the inner side of the flexure becomes smaller, and the gap 3c of the outer coil portion 3 on the outer side of the flexure becomes larger.

[0064] At this time, the inner coil portion 5 is displaced radially outward, so that the flexion structure 1 can be flexed smoothly. In particular, in this embodiment, a series of actions of flexing the flexion angle to 90 degrees and restoring the flexion angle can be performed smoothly. If the flexion angle is less than 90 degrees, the action can be performed smoothly as well.

[0065] That is, the gap 3c of the outer coil portion 3 becomes smaller on the inner side of the bend of the bend structure 1, thereby squeezing each turn 5b of the inner coil portion 5 in the bend radius direction. In this embodiment, the bend radius direction is the direction along the curvature radius of the bend structure 1.

[0066] The cross-sectional shape of the extrusion through the radial inner side of the outer coil portion 3 is an arc shape, and the contact angle (free contact angle) α between the rolls 3b and 5b of the inner and outer coil portions 3 and 5 in the free state becomes larger, and it can be easily performed. In addition, the free contact angle α refers to the angle between the tangent of the contact part of the roll 3b of the outer coil portion 3 and the roll 5b of the inner coil portion 5 that contacts on both sides in the axial direction (reference Figure 2 ).

[0067] Due to the extrusion of the turn portions 5 b , the entire inner coil portion 5 is displaced outward in the bending radial direction. However, this displacement allows each turn portion 5 b of the inner coil portion 5 to enter the enlarged gap 3 c of the outer coil portion 3 .

[0068] Therefore, the flexure structure 1 has a structure capable of limiting compression in the axial direction without hindering flexibility. As a result, the flexure structure 1 can achieve stabilization of the flexure motion.

[0069] In addition, when the bending structure 1 bends, as described above, the gap 3c of the outer wire coil portion 3 on the inner side of the bend becomes smaller, and the gap 3c of the outer wire coil portion 3 on the outer side of the bend becomes larger. Therefore, the size of the gap 3c on the axis O does not change compared to when it is in a straight shape.

[0070] Therefore, the bending structure 1 can keep the length L on the axis O constant not only when it is in a straight shape but also when it is bent, suppressing interference with the member inserted inside.

[0071] In addition, in this embodiment, when the bending structure 1 returns from the bent state to the straight state, it can operate smoothly by the restoring force of the outer wire coil portion 3 and the inner wire coil portion 5.

[0072] In this way, when bending up to 90 degrees and restoring, by setting the size P of the gap 3c of the outer wire coil portion 3, the bending structure can operate smoothly without the inner wire coil portion 5 getting stuck in the outer wire coil portion 3.

[0073] In order to prevent the inner wire coil portion 5 from getting stuck in the outer wire coil portion 3, it is necessary to make the coiled portion 5b of the inner wire coil portion 5 and the coiled portion 3b of the outer wire coil portion 3 inconsistent in the axial direction on the outer side of the bend. This is because when the bending structure 1 returns from the bent state, the coiled portion 3b of the outer wire coil portion 3 can reliably push back the coiled portion 5b of the inner wire coil portion 5 to its original position.

[0074] Therefore, on the outer side of the bend at 90-degree bending, the size PO of the gap 3c of the outer wire coil portion 3 needs to be smaller than the wire diameter d of the wire material 5a of the inner wire coil portion 5 (PO < d). In addition, when the cross-sectional shape of the wire material 5a of the inner wire coil portion 5 is elliptical, the minor axis or major axis along the axis O can be set as d.

[0075] The size PO is equivalent to the value obtained by dividing the elongation amount (LO - L) of the axial length of the outer wire coil portion 3 on the outer side of the bend by the number of turns N and then adding the size P. L is the axial length of the outer wire coil portion 3 on the axis O at 90-degree bending, and LO is the length on the outer side of the bend, which can be expressed as LO = 2π(2L / π + R / 2)(1 / 4) = L + πR / 4.

[0076] In this way, the size PO can be expressed as PO = P + (πR / 4)(1 / N). Therefore, the condition for preventing the inner wire coil portion 5 from getting stuck in the outer wire coil portion 3 on the outer side of the bend can be expressed as P + (πR / 4N) < d. From this formula, the upper limit of the size P is P < d - (πR / 4N).

[0077] On the other hand, on the inner side of the bend at 90-degree bending, in order not to let the inner coil part 5 get stuck in the outer coil part 3, the dimension Pi only needs to be 0 or more (Pi≥0). The dimension Pi is equivalent to the compression amount of the axial length of the outer coil part 3 on the inner side of the bend (Li - L) divided by the number of turns N plus the value of the dimension P.

[0078] Li is the axial length of the outer coil part 3 on the inner side of the bend at 90-degree bending, and can be expressed as Li = 2π(2L / π - R / 2)(1 / 4) = L - πR / 4.

[0079] In this way, the dimension Pi can be expressed as Pi = P - (πR / 4)(1 / N). Therefore, the condition for not letting the inner coil part 5 get stuck in the outer coil part 3 on the inner side of the bend can be expressed as P - (πR / 4N)≥. From this formula, the lower limit of the dimension P is P≥πR / 4N.

[0080] Therefore, the dimension P for not letting the inner coil part 5 get stuck in the outer coil part 3 is πR / 4N≤P < d - (πR / 4N). By setting this dimension P, the bending structure 1 of this embodiment can perform smooth actions when bending up to 90 degrees and restoring.

[0081] When the inner coil part 5 is displaced during the bending of the bending structure 1, by making at least the cross-sectional shape of the inner side in the radial direction of the coil of the outer coil part 3 be arc-shaped, even if the winding part 3b of the outer coil part 3 is not made large in the axial direction, it is possible to prevent the inner coil part 5 from falling off the outer coil part 3.

[0082] In the state where the bending structure l is bent 90 degrees, the contact angle (contact angle during bending) θ between the winding part 3b of the outer coil part 3 located at the bending part and the winding part 5b of the inner coil part 5 contacting the winding part 3b becomes 30 degrees or more.

[0083] In addition, the contact angle θ during bending is the angle between the tangent line between the winding parts 3b, 5b of the contacting outer and inner coil parts 3, 5 and the line connecting the bending center C and the center c of the winding part 3b of the outer coil part 3.

[0084] Through this contact angle θ during bending, when the bending structure 1 restores from the bent state, on the outer side of the bend, the winding part 3b of the outer coil part 3 can reliably push the winding part 5b of the inner coil part 5.

[0085] Moreover, in this embodiment, the overlapping amount a in the axial direction of the wire material 3a of the outer coil part 3 and the wire material 5a of the inner coil part 5 is set within the range of satisfying a≤0.3D, and the contact angle θ during bending is reliably made 30 degrees or more to ensure the smooth action of the bending structure 1.

[0086] [Effect of Embodiment 1]

[0087] As described above, the flexure structure 1 of the present embodiment can flex with respect to the axial direction and includes: an outer coil portion 3 formed of a wire material 3a in a coil shape having a plurality of turns 3b in the axial direction; and an inner coil portion 5 formed of a wire material 5a in a coil shape having a plurality of turns 5b in the axial direction and located inside the outer coil portion 3.

[0088] Therefore, the flexure structure 1 is configured with the inner coil portion 5 located inside the outer coil portion 3, thereby simplifying the structure.

[0089] The outer coil portion 3 has a plurality of gaps 3c that separate adjacent turns 3b in the axial direction. The turns 5a of the inner coil portion 5 are provided corresponding to the gaps 5c of the outer coil portion 3, contact the adjacent turns 3b of the outer coil portion 3, and are fitted between the turns 3b.

[0090] In addition, even when an axial compressive force acts on the flexure structure 1, the turns 5b of the inner coil portion 5 and the turns 3b of the outer coil portion 3b limit the compression of the gaps 3c of the outer coil portion 3 and the gaps 5c of the inner coil portion 5, and can suppress the overall compression.

[0091] In addition, when the flexure structure 1 flexes, the gaps 3c of the outer coil portion 3 on the inner side of the flexure become smaller and the inner coil portion 5 is displaced to the outer side of the flexure, and the gaps of the outer coil portion 3 become larger on the outer side of the flexure to allow the displacement of the inner coil portion 5. Thus, even if the axial rigidity is ensured, sufficient flexibility can be ensured.

[0092] As a result, the flexure structure 1 can stabilize the flexure action and simplify the structure, and thus can ensure the stability of the actions of machines having joint functional parts such as robots, robotic arms, or actuating mechanisms.

[0093] Then, when the axial dimension of the gap 3c of the outer coil portion 3 is set to p, the number of turns of the outer coil portion 3 is set to N, the diameter of the outer coil portion 3 is set to R, and the wire diameter of the wire material 5a of the inner coil portion 5 is set to d, the dimension P is set within the range of πR / 4N ≤ P < d - πR / 4N.

[0094] Therefore, in the present embodiment, by setting the dimension P of the gap 3c of the outer coil portion 3, when flexing up to 90 degrees and restoring, the inner coil portion 5 can smoothly operate without getting stuck in the outer coil portion 3.

[0095] In addition, in the present embodiment, between the bent state and the straight state, the flexure structure 1 can be repeatedly and smoothly operated by the elasticity of the outer coil portion 3 and the inner coil portion 5.

[0096] In addition, the buckled structure 1 of this embodiment can suppress the collapse or deformation caused by the external force acting in the radial direction by the radial restoring force of the outer coil part 3 and the inner coil part 5, so as to protect the components inserted inside.

[0097] In addition, the gap 3c of the bent inner outer coil portion 3 of the flexural structure 1 of the present embodiment becomes smaller, and the gap 3c of the bent outer outer coil portion 3 becomes larger, so the length at the axial center of the outer coil portion 3 does not change compared to when it is in a straight line, which can suppress interference with components inserted into the interior.

[0098] The cross-sectional shape of the outer coil portion 3 of the present embodiment at least in the inner radial direction of the coil is an arc shape, thereby increasing the free contact angle α between the winding portions 3b, 5b of the inner and outer coil portions 3, 5, thereby facilitating the displacement of the inner coil portion 5 during bending.

[0099] Furthermore, when the inner coil portion 5 is displaced, the cross-sectional shape of the inner side of the coil-shaped radial direction of the wire 3a of at least the outer coil portion 3 is an arc shape, which can prevent the inner coil portion 5 from falling off from the outer coil portion 3 without enlarging the winding portion of the outer coil portion 3 in the axial direction.

[0100] In this embodiment, by making the cross-sectional shape of the coil-shaped wire 5a of at least the inner coil portion 5 in the radial direction outer side into an arc shape, the free contact angle α between the winding portions 3b and 5b of the inner and outer coil portions 3, 5 can be reliably increased.

[0101] Furthermore, when the flexure structure 1 of the present embodiment is flexed at 90 degrees, the flexure contact angle θ between the turn 3b of the outer coil 3 located at the flexure portion and the turn 5b of the inner coil 5 contacting the turn 3b is 30 degrees or more.

[0102] Therefore, in this embodiment, the roll portion 5b of the inner coil portion 5 can be reliably pushed back by the roll portion 3b of the outer coil portion 3 on the outer side of the bend, so that the bendable structure 1 can move more smoothly.

[0103] In this embodiment, the overlap amount a between the wire 3a of the outer coil portion 3 and the wire 5a of the inner coil portion 5 in the axial direction is set within a range satisfying a≤0.3D relative to the wire diameter D of the wire 3a of the outer coil portion 3.

[0104] Therefore, in the present embodiment, the contact angle θ during flexion can be reliably set to 30 degrees or more, thereby ensuring smooth movement of the flexure structure 1 .

[0105] Example 2

[0106] Figure 5 A second embodiment of the present invention is a perspective view of a robot arm having a joint function portion to which a flexure structure is applied. Figure 6yes Figure 5 In addition, in the second embodiment, the same symbols are marked for the corresponding structures in the first embodiment and the repeated description is omitted.

[0107] In this embodiment, the bending structure 1 of the embodiment 1 is used to form the joint function part 11 of the robot arm 7.

[0108] In addition, the robot arm 7 is an example of a machine having a joint function part. That is, as a machine having a joint function part, as long as it has a joint function part that performs a flexion action, it can be a robot, a robot arm, or an actuator mechanism in various fields. In addition, in the case of a medical robot arm, in addition to the forceps installed on the surgical robot, it also includes an endoscope camera and manual forceps that are not installed on the surgical robot.

[0109] The robot arm 7 of the present embodiment is composed of a shaft 9 , a joint function unit 11 and an end effector 13 .

[0110] The shaft 9 is formed into a cylindrical shape, for example. A driving lead 15 and a flexible member 20 pass through the shaft 9. The driving lead 15 is used to drive the joint function part, and the flexible member 20 is composed of a push-pull cable for driving the end effector 13. The end effector 13 is provided on the front end side of the shaft 9 across the joint function part 11.

[0111] The joint function part 11 includes a base part 17 , a movable part 19 , a flexible catheter 21 , and a bending structure 1 .

[0112] The base 17 is a cylindrical body formed of resin or metal, etc., and is mounted on the front end of the shaft 9. The driving lead 15 is inserted through the through hole 17a in the axial direction of the base 17, and the flexible member 20 is inserted through the through hole 17b in the axial center.

[0113] The movable part 19 is a cylindrical body formed of resin or metal, etc., and is mounted on the end effector 13. The front end of the driving lead 15 is fixed to the movable part 19. Therefore, by operating the driving lead 15, the movable part 19 is displaced relative to the base 17, so that the end effector 13 is directed to a desired direction. An insertion hole 19b is provided in the axial center of the movable part 19, and the flexible member 20 is inserted therethrough.

[0114] The flexible conduit 21 is interposed between the base 17 and the movable portion 19, and is bent according to the displacement of the movable portion 19 relative to the base 17. The flexible conduit 21 allows the driving wire 15 and the bending structure 1 to pass in the axial direction.

[0115] The flexible conduit 21 of this embodiment is constituted by a telescopic tube formed by a tube body having a corrugated cross section. However, the flexible conduit 21 may also be a coil spring, a cylinder, etc., and is not particularly limited as long as it is a flexible tube.

[0116] The flexure structure 1 has the same structure as that of the embodiment 1. The flexure structure 1 is arranged along the axial center of the flexible conduit 21 and is provided between the base 17 and the movable portion 19.

[0117] The flexure structure 1 is attached to the insertion holes 17b and 19b of the base 17 and the movable part 19 at both ends thereof, respectively, with the flexible member 20 inserted therein. Thus, the flexure structure 1 supports the movable part 19 in an axially immovable manner relative to the base 17, and flexes together with the flexible member 20 according to the displacement of the movable part 19 relative to the base 17.

[0118] The flexible member 20 is inserted through the flexure structure 1 so as to be movable in the axial direction, and restricts radial displacement of the inner and outer coils 3 and 5. Accordingly, the flexure structure 1 also has a function of guiding the flexible member 20 in the axial direction.

[0119] The end effector 13 of this embodiment is a medical forceps, and axially supports a pair of gripping parts 13a in an openable and closable manner relative to the movable part 19 of the joint functional part 11. The end effector 13 is connected to the flexible member 20 that passes through the joint functional part 11, and the gripping parts 13a are opened and closed by the axial movement (advance and retreat movement) of the flexible member 20.

[0120] In addition, the end effector 13 may be an instrument other than forceps, such as scissors, a gripping retractor, a needle holder, etc. In addition, the end effector 13 is not limited to medical use, and may also be used in industry.

[0121] In the robot arm 7 having this structure, an operator such as a doctor can open and close the gripping portion 13 a of the end effector 13 by moving the flexible member 20 forward and backward.

[0122] In addition, by the operator pulling any one or more driving leads 15, the joint functional part 11 is bent, and the end effector 13 can be directed to a desired direction relative to the axis 9. In this state, as long as the flexible member 20 is moved forward and backward, the gripping part 13a of the end effector 13 can be opened and closed.

[0123] Since the flexible member 20 passes through the axis O of the flexure structure 1 , the amount of movement of the flexible member 2 according to the length L of the flexure structure 1 on the axis O is constant, and the opening and closing operation can be performed stably and accurately.

[0124] In addition, in this embodiment, the same effects as those of the first embodiment can be achieved.

[0125] Explanation of symbols

[0126] 1—bending structure, 3—external coil portion, 3a—wire, 3b—roll portion, 3c—gap, 5—inner coil portion, 5a—wire, 5b—roll portion, 5c—gap, 11—joint functional portion, 17—base portion, 19—movable portion.

Claims

1. A flexure structure that can flex relative to the axial direction, characterized in that: It includes: An outer coil part composed of a coil-shaped wire material having a plurality of turns in the above axial direction; and An inner coil part composed of a coil-shaped wire material having a plurality of turns in the above axial direction and located inside the above outer coil part, The above outer coil part has a plurality of gaps that separate adjacent turns in the above axial direction, The turns of the above inner coil part are arranged corresponding to the above gaps of the above outer coil part, contact the above adjacent turns of the above outer coil part, and are fitted between the turns, When the axial dimension of the above gap of the above outer coil part in the free state is set as P, the number of turns of the above outer coil part is set as N, the diameter of the above outer coil part is set as R, and the wire diameter of the wire material of the above inner coil part is set as d, the above dimension P is set within the range of πR / 4N ≤ P < d - πR / 4N.

2. The flexure structure according to claim 1, characterized in that: In the cross-sectional shape of the wire material of the above outer coil part, at least the cross-sectional shape on the inner side in the radial direction of the above coil shape is arc-shaped, In the cross-sectional shape of the wire material of the above inner coil part, at least the cross-sectional shape on the outer side in the radial direction of the above coil shape is arc-shaped.

3. The flexure structure according to claim 2, characterized in that: When flexing 90 degrees, the contact angle between the turn of the above outer coil part at the flexure part and the turn of the above inner coil part in contact with the turn is 30 degrees or more, The above contact angle is the angle between the tangent line between the turns of the above inner coil part and the outer coil part in contact and the line connecting the flexure center and the center of the turn of the above outer coil part.

4. The flexure structure according to claim 3, characterized in that: When the overlapping amount in the axial direction of the wire material of the above outer coil part and the wire material of the above inner coil part in the free state is set as a and the wire diameter of the wire material of the above outer coil part is set as D, the above overlapping amount is set within the range of a ≤ 0.3D.

5. A joint functional part that applies the flexure structure according to any one of claims 1 to 4, characterized in that: It includes a base part and a movable part that displaces relative to the base part, The above flexure structure is provided between the above base part and the movable part and flexes according to the displacement of the above movable part relative to the above base part.

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