Multilayer coil

Abstract

To provide a multilayer coil that rotates well in both directions.SOLUTION: A multilayer coil includes a first coil including a first strand wound in a spiral shape, and a second coil including a second strand wound in a spiral shape around the outer periphery of the first coil. One of the first strand and the second strand has a protrusion that protrudes in a radial direction of the multilayer coil toward where the other of the first strand and the second strand is arranged, in a cross section of the multilayer coil, and the other strand has a recess that fits into the protrusion.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology disclosed in this specification relates to a multilayer coil.

Background Art

[0002] Multilayer coils are used as part of medical devices. For example, Patent Document 1 discloses a multilayer coil used as part of a catheter.

[0003] A multilayer coil includes a first coil and a second coil. The first coil includes a first wire element wound in a helical shape. The second coil includes a second wire element wound in a helical shape on the outer periphery of the first coil.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the multilayer coil is rotated in a direction opposite to the twisting direction of the second wire element, a force that opens the second coil is applied to the second coil, so that the first coil and the second coil are separated, and there is a possibility that the torque transmission performance decreases. For this reason, the rotation of the multilayer coil in the direction opposite to the twisting direction of the second wire element has been restricted.

[0006] Note that such a problem is not limited to the multilayer coil for medical devices, but is a common problem for various multilayer coils.

[0007] This specification discloses a technology capable of solving the above-described problems.

Means for Solving the Problems

[0008] The technology disclosed in this specification can be realized in the following forms, for example.

[0009] (1) The multilayer coil disclosed in this specification includes a first coil including a first wire element wound in a helical shape, and a second coil including a second wire element wound in a helical shape on the outer periphery of the first coil. One of the first wire element and the second wire element has a convex portion that protrudes in a direction in which the other wire element of the first wire element and the second wire element is arranged in the radial direction of the multilayer coil in the cross section of the multilayer coil, and the other wire element has a concave portion that fits into the convex portion.

[0010] According to this multilayer coil, an anchor effect is brought about between the first coil and the second coil, and separation between the first coil and the second coil is suppressed. As a result, the torque transmission performance of the multilayer coil when rotating in a direction opposite to the twisting direction of the second wire element is improved. Therefore, the multilayer coil can be rotated well in both the twisting direction of the second wire element and the direction opposite to the twisting direction of the second wire element.

[0011] (2) In the above multilayer coil, the one wire element may be configured to have a higher hardness than the other wire element. According to this configuration, the shape of the other wire element is likely to follow the shape of the one wire element. As a result, a better anchor effect is brought about between the first coil and the second coil. Therefore, the multilayer coil can be rotated better in both the twisting direction of the second wire element and the direction opposite to the twisting direction of the second wire element.

[0012] Note that the technology disclosed in this specification can be realized in various forms, and can be realized, for example, in forms such as a multilayer coil and a method for manufacturing a multilayer coil.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0014] A. Embodiment: A-1. Configuration of the multilayer coil 10: FIG. 1 is a side view showing the appearance of the multilayer coil 10. In FIG. 1 and each subsequent figure, XYZ axes orthogonal to each other are shown. In FIG. 1, the multilayer coil 10 is shown in a straight state parallel to the Z-axis direction as a whole, but the multilayer coil 10 has flexibility to the extent that it can be curved.

[0015] The multilayer coil 10 is used as part of a medical device to be inserted into a blood vessel or the like, such as a catheter or an atelectomy device. The multilayer coil 10 is a hollow cylindrical coil member in which a space 20 is formed by winding a metal wire in a spiral shape (see FIG. 2 etc.).

[0016] FIG. 2 is an explanatory drawing showing a cross section of the multilayer coil 10 at the position of II-II in FIG. 1. FIG. 3 is an explanatory drawing showing a cross section of the multilayer coil 10 at the position of III-III in FIG. 1. The cross section of the multilayer coil 10 refers to a cross section (XY cross section) perpendicular to the direction (Z-axis direction) along the central axis AX of the multilayer coil 10. Hereinafter, the direction along the central axis AX may be simply referred to as the "axial direction".

[0017] The multilayer coil 10 includes a first coil 100 and a second coil 200.

[0018] The first coil 100 is located on the inner peripheral side of the multilayer coil 10. The first coil 100 of the present embodiment includes six first rigid wires 110 and six first soft wires 120. That is, the first coil 100 includes 12 strands. The first rigid wires 110 and the first soft wires 120 are alternately arranged in the circumferential direction. The first rigid wires 110 and the first soft wires 120 are each wound in a helical shape. The first rigid wires 110 and the first soft wires 120 are each an example of a first strand.

[0019] The second coil 200 is located on the outer peripheral side of the multilayer coil 10. The second coil 200 of the present embodiment includes six second rigid wires 210 and six second soft wires 220. That is, the second coil 200 includes 12 strands. The second rigid wires 210 and the second soft wires 220 are alternately arranged in the circumferential direction. The second rigid wires 210 and the second soft wires 220 are each wound in a helical shape around the outer periphery of the first coil 100. The second rigid wires 210 and the second soft wires 220 are each an example of a second strand.

[0020] The first rigid wire 110 has a higher hardness than the first soft wire 120 and a higher hardness than the second soft wire 220. The second rigid wire 210 has a higher hardness than the first soft wire 120 and a higher hardness than the second soft wire 220. The materials of the first rigid wire 110 and the second rigid wire 210 (hereinafter collectively referred to as "rigid wires"), and the first soft wire 120 and the second soft wire 220 (hereinafter collectively referred to as "soft wires") are not particularly limited. For example, the rigid wire may be formed of SUS304WPB and the soft wire may be formed of SUS304HW1, or the rigid wire may be formed of tungsten and the soft wire may be formed of a Ni-Ti alloy.

[0021] The first hard wire 110 and the first soft wire 120 are wound counterclockwise when viewed from the positive Z-axis side (see FIG. 6). The second hard wire 210 and the second soft wire 220 are wound clockwise when viewed from the positive Z-axis side (see FIG. 6). That is, in the present embodiment, the strands included in the first coil 100 and the strands included in the second coil 200 are wound in opposite directions to each other. Therefore, as shown in FIGS. 2 and 3 for example, the cross section of the multilayer coil 10 is not constant from one end to the other end in the Z-axis direction, but changes at a constant period from one end to the other end in the Z-axis direction.

[0022] In the cross section shown in FIG. 2, in the multilayer coil 10, the first hard wire 110 and the second soft wire 220 are arranged side by side in the radial direction of the multilayer coil 10, and the first soft wire 120 and the second hard wire 210 are arranged side by side in the radial direction of the multilayer coil 10. In the cross section shown in FIG. 3, in the multilayer coil 10, the first hard wire 110 and the second hard wire 210 are arranged side by side in the radial direction of the multilayer coil 10, and the first soft wire 120 and the second soft wire 220 are arranged side by side in the radial direction of the multilayer coil 10. Thus, in the multilayer coil 10 of the present embodiment, from one end to the other end in the Z-axis direction, the cross section shown in FIG. 2 and the cross section shown in FIG. 3 appear alternately.

[0023] The cross section shown in FIG. 2 will be described in more detail. The first hard wire 110 has a convex portion 111 that protrudes in the direction in which the second soft wire 220 is arranged in the radial direction of the multilayer coil 10 (that is, the outer peripheral direction of the multilayer coil 10). The second soft wire 220 has a concave portion 222 that fits into the convex portion 111. The second hard wire 210 has a convex portion 211 that protrudes in the direction in which the first soft wire 120 is arranged in the radial direction of the multilayer coil 10 (that is, the central direction of the multilayer coil 10). The first soft wire 120 has a concave portion 122 that fits into the convex portion 211.

[0024] FIG. 4 is an explanatory diagram showing an enlarged view of the interface between the first rigid wire 110 and the second flexible wire 220 in FIG. 2. P1, P2, and P3 shown in FIG. 4 are the contact points between the first rigid wire 110 and the second flexible wire 220, respectively. P1 is the most protruding position on the convex portion 111. P2 is located on one side in the circumferential direction of the multilayer coil 10 with respect to P1, and is the position closest to the central axis AX among the contact points between the first rigid wire 110 and the second flexible wire 220. P3 is located on the other side in the circumferential direction of the multilayer coil 10 with respect to P1, and is the position closest to the central axis AX among the contact points between the first rigid wire 110 and the second flexible wire 220. P2 is located farther from the central axis AX of the multilayer coil 10 than P3.

[0025] In the multilayer coil 10, even when the interface between the first rigid wire 110 and the second flexible wire 220 has an irregular shape, for example, a portion where the outer surface of the first rigid wire 110 is very smooth does not correspond to the "convex portion" defined in this specification. Specifically, a portion where the ratio (h1 / w1) of the height h1, which is the radial length of the multilayer coil 10 from P1 to P3, to the width w1, which is the circumferential length of the multilayer coil 10 from P2 to P3, is 0.001 or more, and the ratio (h2 / h1) of the height h2, which is the radial length of the multilayer coil 10 from P1 to P2, to the height h1 is 0.001 or more, is defined as the "convex portion" in this specification. Note that the "circumferential length of the multilayer coil 10 from P2 to P3" more precisely means the circumferential length from P3 to P4 (see FIG. 4), which is a position on the virtual straight line passing through the central axis AX and P2 and having the same distance from the central axis AX as P3. Since the torque transmission performance in both directions can be further improved, h1 / w1 is preferably 0.01 or more, h2 / h1 is preferably 0.01 or more, more preferably h1 / w1 is 0.1 or more, and h2 / h1 is 0.1 or more.

[0026] FIG. 5 is an explanatory diagram showing an enlarged view of the interface between the second rigid wire 210 and the first flexible wire 120 in FIG. 2. P5, P6, and P7 shown in FIG. 5 are the contact points between the second rigid wire 210 and the first flexible wire 120, respectively. P5 is the most protruding position on the convex portion 211. P6 is located on one side in the circumferential direction of the multilayer coil 10 with respect to P5 and is the position farthest from the central axis AX among the contact points between the second rigid wire 210 and the first flexible wire 120. P7 is located on the other side in the circumferential direction of the multilayer coil 10 with respect to P5 and is the position farthest from the central axis AX among the contact points between the second rigid wire 210 and the first flexible wire 120. P6 is closer to the central axis AX of the multilayer coil 10 than P7.

[0027] In the multilayer coil 10, even when the interface between the second rigid wire 210 and the first flexible wire 120 has an irregular shape, for example, a portion where the inner surface of the second rigid wire 210 is very smooth does not correspond to the "convex portion" defined in this specification. Specifically, a portion where the ratio (h3 / w2) of the height h3, which is the radial length of the multilayer coil 10 from P5 to P7, to the width w2, which is the circumferential length of the multilayer coil 10 from P6 to P7, is 0.001 or more, and the ratio (h4 / h3) of the height h4, which is the radial length of the multilayer coil 10 from P5 to P6, to the height h3 is 0.001 or more is defined as the "convex portion" in this specification. Note that the "circumferential length of the multilayer coil 10 from P6 to P7" more precisely means the circumferential length from P7 to P8 (see FIG. 5), which is a position on the virtual straight line passing through the central axis AX and P6 and having the same distance from the central axis AX as P7. Since the torque transmission performance in both directions can be further improved, h3 / w2 is preferably 0.01 or more, h4 / h3 is preferably 0.01 or more, more preferably h3 / w2 is 0.1 or more, and h4 / h3 is 0.1 or more.

[0028] As used herein, "hardness" specifically refers to Vickers hardness. The method for measuring the Vickers hardness at each position in the cross-section of the multi-layer coil 10 is as follows, for example. That is, a test piece is obtained by cutting the multi-layer coil 10 at an arbitrary position in the direction of the central axis AX. Then, a square pyramid-shaped indenter is pressed against the cross-section of the test piece with a constant load (test force: F (N), 0.1 N / second), and after removing the indenter, the average length d (mm) of the diagonal line in the indentation (depression) formed is measured. By substituting the test force F and the average length d of the diagonal line into the following formula and calculating, the Vickers hardness at each part of the cross-section of the multi-layer coil 10 is determined. Vickers hardness = 0.01891 × F / d 2

[0029] A-2. Manufacturing method of the multi-layer coil 10: The multi-layer coil 10 as described above can be manufactured by the following manufacturing method, for example. FIG. 6 is an explanatory diagram showing a multi-layer coil precursor 10m. The multi-layer coil precursor 10m represents one form in the manufacturing process of the multi-layer coil 10.

[0030] First, six hard wires 110m and six soft wires 120m are wound spirally along the outer circumference of a mandrel (not shown). At this time, the hard wires 110m and the soft wires 120m are alternately arranged in the circumferential direction of the mandrel. Thereby, a coil body 100m, which is a precursor of the first coil 100, is formed. The cross-sectional shapes of the hard wires 110m and the soft wires 120m are arbitrary, but for example, they are circular.

[0031] Next, six hard wires 210m and six soft wires 220m are wound spirally along the outer circumference of the coil body 100m. At this time, the hard wires 210m and the soft wires 220m are alternately arranged in the circumferential direction of the mandrel and are wound in the opposite direction to the first hard wire 110 and the first soft wire 120. Thereby, a coil body 200m, which is a precursor of the second coil 200, is formed. The cross-sectional shapes of the hard wires 210m and the soft wires 220m are arbitrary, but for example, they are circular. Thus, the multi-layer coil precursor 10m is formed.

[0032] Next, swaging of the multilayer coil precursor 10m is performed. Specifically, with the multilayer coil precursor 10m still wound around the mandrel, the outer periphery of the multilayer coil precursor 10m is struck with a die toward the center direction of the multilayer coil precursor 10m. As a result, the coil body 100m and the coil body 200m are in close contact with each other. In addition, at locations where the hard wire and the soft wire are arranged side by side in the radial direction of the multilayer coil precursor 10m, due to the difference in hardness between the hard wire and the soft wire, a convex portion is formed on the hard wire, and a concave portion is formed on the soft wire. Through the above steps, the multilayer coil 10 can be manufactured.

[0033] A-3. Effects of this embodiment: As described above, the multilayer coil 10 of this embodiment includes a first coil 100 including a first hard wire 110 and a first soft wire 120 wound in a spiral shape, and a second coil 200 including a second hard wire 210 and a second soft wire 220 wound in a spiral shape on the outer periphery of the first coil 100. The first hard wire 110 has a convex portion 111 protruding in the direction in which the second soft wire 220 is arranged in the radial direction of the multilayer coil 10 in the cross section of the multilayer coil 10, and the second soft wire 220 has a concave portion 222 fitted to the convex portion 111. The second hard wire 210 has a convex portion 211 protruding in the direction in which the first soft wire 120 is arranged in the radial direction of the multilayer coil 10 in the cross section of the multilayer coil 10, and the first soft wire 120 has a concave portion 122 fitted to the convex portion 211.

[0034] According to the multilayer coil 10 of this embodiment, an anchor effect is brought about between the first coil 100 and the second coil 200, and separation between the first coil 100 and the second coil 200 is suppressed. As a result, the multilayer coil 10 has improved torque transmission performance when rotating in the direction opposite to the twisting directions of the second hard wire 210 and the second soft wire 220. Therefore, the multilayer coil 10 can be rotated well in both the twisting directions of the second hard wire 210 and the second soft wire 220 and the direction opposite to the twisting directions of the second hard wire 210 and the second soft wire 220.

[0035] In the multilayer coil 10 of this embodiment, the first hard wire 110 has a higher hardness than the second soft wire 220, and the second hard wire 210 has a higher hardness than the first soft wire 120. According to the multilayer coil 10 of this embodiment, the shape of the second soft wire 220 can easily follow the shape of the first hard wire 110, and the first soft wire 120 can easily follow the shape of the second hard wire 210. Thereby, a better anchor effect is brought about between the first coil 100 and the second coil 200. Therefore, the multilayer coil 10 can be rotated better in both the twisting direction of the second hard wire 210 and the second soft wire 220 and the direction opposite to the twisting direction of the second hard wire 210 and the second soft wire 220.

[0036] Furthermore, in the multilayer coil 10 of this embodiment, the convex portion 111 of the first hard wire 110 fits with the concave portion 222 of the second soft wire 220, and the convex portion 211 of the second hard wire 210 fits with the concave portion 122 of the first soft wire 120. As a result, since the contact area between the strands included in the first coil 100 and the strands included in the second coil 200 is relatively large, the bending rigidity, torsional rigidity, durability against tensile stress, and durability against compressive stress of the multilayer coil 10 can be improved.

[0037] Furthermore, in the multilayer coil 10 of this embodiment, in the axial direction of the multilayer coil 10, the cross section shown in FIG. 2 and the cross section shown in FIG. 3 appear alternately. That is, according to the multilayer coil 10 of this embodiment, in a cross section parallel to the axial direction of the multilayer coil 10, the first hard wire 110 has a convex portion 111 that protrudes in the direction in which the second soft wire 220 is arranged in the radial direction of the multilayer coil 10, and the second soft wire 220 has a concave portion 222 that fits with the convex portion 111. The second hard wire 210 has a convex portion 211 that protrudes in the direction in which the first soft wire 120 is arranged in the radial direction of the multilayer coil 10, and the first soft wire 120 has a concave portion 122 that fits with the convex portion 211. Therefore, according to the multilayer coil 10 of this embodiment, an anchor effect is brought about between the first coil 100 and the second coil 200, so that the durability of the multilayer coil 10 against tensile stress can be improved.

[0038] B. Modification example: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the gist thereof. For example, the following modifications are also possible.

[0039] In the above embodiment, the first coil 100 includes 12 strands, and the second coil 200 includes 12 strands. However, the first coil only needs to include at least one strand. Similarly, the second coil only needs to include at least one strand. For example, the first coil may be a multilayer coil formed of one first rigid wire, and the second coil may be a multilayer coil formed of one second soft wire.

[0040] In the above embodiment, the strand having the convex portion 111 has a higher hardness than the strand having the concave portion 122, and the strand having the convex portion 211 has a higher hardness than the strand having the concave portion 222. However, the strand having the convex portion may have a higher hardness than the strand having the concave portion, or the strand having the convex portion may have the same hardness as the strand having the concave portion.

[0041] In the above embodiment, the strands included in the first coil 100 and the strands included in the second coil 200 are wound in opposite directions to each other. However, the strands included in the first coil and the strands included in the second coil may be wound in the same direction.

[0042] In the above embodiment, the multilayer coil 10 includes a two-layer coil of the first coil 100 and the second coil 200. However, the multilayer coil may include a coil of three or more layers.

[0043] The multilayer coil 10 of the above embodiment is formed in a hollow cylindrical shape, but is not limited thereto, and the coil body may be formed to have a hollow portion in a shape such as an elliptical column or a polygonal column.

[0044] The manufacturing method of the multilayer coil 10 of the above embodiment is not limited to the above-described manufacturing method.

Claims

1. A multilayer coil (10) comprising: a first coil (100) including first wires (110, 120) wound in a helical shape; a second coil (200) including second wires (210, 220) wound in a helical shape around the outer periphery of the first coil (100); and one of the first wires (110, 120) and the second wires (210, 220) has a convex portion (111, 211) that protrudes in a direction in which the other of the first wires (110, 120) and the second wires (210, 220) is arranged in the radial direction of the multilayer coil (10) in a cross-section of the multilayer coil (10); the other wire has a concave portion (122, 222) that fits into the convex portion (111, 211), the multilayer coil (10).

2. The multilayer coil (10) according to claim 1, wherein the one wire has a higher hardness than the other wire, the multilayer coil (10).

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