Composite cable

Abstract

This invention provides a composite cable that enables miniaturization while achieving high bending durability. [Solution] The composite cable 1 has multiple 2, 3 and multiple wires 4. The coaxial wires 2, 3 have central conductors 21, 31, insulators 22, 32 covering the central conductors 21, 31, multiple outer conductors 23, 33 arranged on the outer circumference of the insulators 22, 32, and outer sheaths 24, 34 covering the multiple outer conductors 23, 33. The insulated wire 4 consists of a stranded conductor 40 made by twisting together multiple strands 41, and an insulating sheath 42 covering the stranded conductor 40. The central conductors 21, 31 of the coaxial wires 2, 3 are single wires, and the conductor diameter D of the central conductors 21, 31 11 ,D 21 However, the wire diameter D3 or less of multiple strands 41 of the insulated wire 4.

Description

[Technical Field]

[0001] The present invention relates to a composite cable having a coaxial cable and an insulated wire. [Background technology]

[0002] Conventionally, a composite cable having multiple coaxial cables and multiple insulated wires is known, for example, the one described in Patent Document 1.

[0003] The composite cable (multi-core cable) described in Patent Document 1 comprises 10 coaxial wires and 8 insulated wires, a retaining winding made by spirally winding resin tape around these wires (10 coaxial wires and 8 insulated wires), a shielding layer covering the retaining winding, and an outer sheath covering the shielding layer. Each coaxial wire has a central conductor made of a single wire or stranded wire, an insulator covering the central conductor, an outer conductor arranged on the outer circumference of the insulator, and an outer sheath covering the outer conductor. The insulated wire has a conductor made of multiple strands twisted together and covered with an outer sheath. The overall outer diameter (cable diameter) of the cable is, for example, 2.0 mm to 6.0 mm, preferably 4.0 mm to 5.0 mm. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-29262 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] For example, composite cables used in intravascular endoscopy catheters require extremely thinness, such as a cable diameter of 1.0 mm or less, and high bending durability. To achieve thinness, it is desirable to use single wires for the central conductor of the coaxial cable and the conductors of the insulated wires. On the other hand, to improve bending durability, it is desirable to use stranded wires for the central conductor of the coaxial cable and the conductors of the insulated wires. The inventors of this invention have conducted extensive research to achieve both extremely thinness and bending durability in composite cables, and by combining single wires and stranded wires to satisfy predetermined conditions, they have succeeded in realizing a composite cable that can be used, for example, in intravascular endoscopy catheters. In other words, the present invention aims to provide a composite cable that enables thinness while achieving high bending durability. [Means for solving the problem]

[0006] The present invention aims to solve the above problems and provides a composite cable having a coaxial cable and an insulated wire, wherein the coaxial cable has a central conductor, an insulator covering the central conductor, a plurality of outer conductors arranged on the outer circumference of the insulator, and an outer sheath covering the plurality of outer conductors, the insulated wire consists of a stranded conductor formed by twisting together a plurality of strands and an insulating sheath covering the stranded conductor, the central conductor of the coaxial cable is a single wire, and the conductor diameter of the central conductor is less than or equal to the strand diameter of the plurality of strands of the insulated wire. [Effects of the Invention]

[0007] The composite cable according to the present invention makes it possible to achieve high bending durability while enabling a reduction in diameter. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of a composite cable according to an embodiment of the present invention. [Figure 2] (a) is a cross-sectional view showing a large-diameter coaxial line in an enlarged view. (b) is a cross-sectional view showing a small-diameter coaxial line in an enlarged view. [Figure 3] This is a magnified cross-sectional view of an insulated wire. [Figure 4] It is a cross-sectional view showing an enlarged view of an insulated wire according to a modified example.

Mode for Carrying Out the Invention

[0009] [Embodiment] FIG. 1 is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of a composite cable according to an embodiment of the present invention. This composite cable 1 is used, for example, in an intravascular endoscope catheter, and connects an imaging unit inserted into a blood vessel of a human body and an external device arranged outside the body that performs image processing and the like.

[0010] The composite cable 1 includes a cable core 10 including a plurality of coaxial lines 2 and 3 and a plurality of insulated wires 4, an intervening member 11 made of a fibrous body such as aramid fiber or Kevlar (registered trademark), and a tape layer 5 made of a belt-shaped pressing tape 50 spirally wound around the cable core 10. And a shield layer 6 disposed on the outer periphery of the tape layer 5 and a sheath 7 made of resin. The outer diameter D of the composite cable 1 is, for example, 1.0 mm or less.

[0011] The plurality of insulated wires 4 are used, for example, as power supply lines for supplying an operating power source to a camera of the imaging unit or a light emitting element for illuminating an imaging target by the camera. The plurality of coaxial lines 2 and 3 are used, for example, as signal lines for transmitting a control signal or an image information signal for controlling the camera.

[0012] The intervening member 11 is formed by bundling fibrous bodies into a string shape and is disposed at the center of the composite cable 1. The plurality of coaxial lines 2 and 3 and the plurality of insulated wires 4 are arranged so as to surround the intervening member 11 and are twisted together in a spiral shape. In the present embodiment, the cable core 10 is composed of two large-diameter coaxial lines 2, one small-diameter coaxial line 3, and three insulated wires 4. The large-diameter coaxial line 2 and the insulated wire 4 have the same outer diameter. The small-diameter coaxial line 3 is formed with an outer diameter smaller than that of the large-diameter coaxial line 2 and the insulated wire 4.

[0013] The retaining tape 50 is made of a resin such as PET (polyethylene terephthalate) and is wound spirally so that a portion of it overlaps in the width direction. The shield layer 6 is made by spirally winding multiple shield wires 60 made of, for example, a copper alloy. However, the structure of the shield layer 6 is not limited to this, and for example, the wires may be braided together in a grid pattern.

[0014] The spiral winding direction of the multiple coaxial wires 2, 3 and multiple insulated wires 4 in the cable core 10 is opposite to the spiral winding direction of the retaining tape 50, and the spiral winding direction of the retaining tape 50 is opposite to the spiral winding direction of the multiple shield wires 60. This suppresses the bending tendency of the composite cable 1.

[0015] The sheath 7 is formed into a tubular shape by extruding resin around the outer circumference of the shield layer 6. As the material for the sheath 7, a fluororesin such as PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) can be used.

[0016] Figure 2(a) is a cross-sectional view showing an enlarged view of one of the two large-diameter coaxial cables 2. The other large-diameter coaxial cable 2 is constructed in a similar manner.

[0017] The large-diameter coaxial cable 2 has a central conductor 21, an insulator 22 covering the central conductor 21, a plurality of outer conductors 23 arranged on the outer circumference of the insulator 22, and an outer sheath 24 covering the plurality of outer conductors 23. In this embodiment, 20 outer conductors 23 are arranged on the outer circumference of the insulator 22, and these outer conductors 23 are wound horizontally in a spiral shape. The insulator 22 and the outer sheath 24 are made of a fluororesin such as PFA, and are extruded onto the outer circumference of the central conductor 21 and the outer circumference of the outer conductors 23, respectively.

[0018] The central conductor 21 and the outer conductor 23 are single wires with a circular cross-section, made of, for example, a copper alloy. Here, a single wire refers to a single conductive material formed in a linear shape. As shown in Figure 2, the conductor diameter of the central conductor 21 is D 11 The conductor diameter of the outer conductor 23 is set to D. 12When it is D 12 / D 11 The value of is desirably 0.35 or more and 1.0 or less, more desirably 0.5 or more and 0.85 or less.

[0019] FIG. 2(b) is a cross-sectional view showing an enlarged view of the coaxial line 3 with a small diameter. The coaxial line 3 with a small diameter has a center conductor 31, an insulator 32 covering the center conductor 31, a plurality of external conductors 33 disposed on the outer periphery of the insulator 32, and an outer covering 34 covering the plurality of external conductors 33. In the present embodiment, twelve external conductors 33 are spirally wound around the outer periphery of the insulator 32. The insulator 32 and the outer covering 34 are made of a fluororesin such as PFA, and are extrusion-molded on the outer periphery of the center conductor 31 and the outer periphery of the external conductor 33, respectively.

[0020] The center conductor 31 and the external conductors 33 are single wires having a circular cross-section made of, for example, a copper alloy. The center conductor 31 is formed thinner than the center conductor 21 of the coaxial line 2 with a large diameter. The conductor diameter of the external conductor 33 is equivalent to the conductor diameter of the external conductor 23 of the coaxial line 2 with a large diameter. As shown in FIG. 2(b), when the conductor diameter of the center conductor 31 is D 21 and the conductor diameter of the external conductor 33 is D 22 when it is, D 22 / D 21 The value of is, like the value of D 12 / D 11 in the coaxial line 2 with a large diameter, desirably 0.35 or more and 1.0 or less, more desirably 0.5 or more and 0.85 or less.

[0021] FIG. 3 is a cross-sectional view showing an enlarged view of one of the three insulated electric wires 4. Note that the other insulated electric wires 4 are configured in the same manner.

[0022] The insulated electric wire 4 is composed of a stranded conductor 40 formed by twisting a plurality of strands 41 and an insulating coating 42 covering the stranded conductor 40. The strands 41 are made of, for example, a copper alloy. The insulating coating 42 is made of a fluororesin such as PFA, and is extrusion-molded on the outer periphery of the stranded conductor 40. In the present embodiment, the stranded conductor 40 is formed by twisting seven strands 41 having a circular cross-section.

[0023] If the wire diameter of the strands 41 of the insulated wire 4 is D3, then the conductor diameter D of the central conductor 21 of the large-diameter coaxial cable 2 is... 11 The wire diameter D3 of the wire 41 is less than or equal to the wire diameter D3 of the wire 41, and is more than half of the wire diameter D3 of the wire 41. In other words, D 11 The value of / D3 is between 0.5 and 1.0. Also, the conductor diameter D of the central conductor 21 of the large-diameter coaxial cable 2. 11 It is 0.05 mm or less.

[0024] When the conductor cross-sectional area is the sum of the cross-sectional areas of the central conductor 21 and multiple outer conductors 23 of the large-diameter coaxial cable 2, and the conductor cross-sectional area is the sum of the cross-sectional areas of multiple strands 41 in the stranded conductor 40 of the insulated wire 4, if the value of S2 / S1 is too large, stress tends to concentrate in the insulated wire 4 when the composite cable 1 is bent. Conversely, if the value of S2 / S1 is too small, stress tends to concentrate in the large-diameter coaxial cable 2. The desirable range for the value of S2 / S1 is 0.6 to 4.5, and more preferably 1.0 to 3.0.

[0025] In this embodiment, since the number of outer conductors 23 in the large-diameter coaxial cable 2 is 20, the conductor cross-sectional area S1 of the large-diameter coaxial cable 2 is S1 = ((D 11 / 2) 2 +(D 12 / 2) 2 It can be calculated using the formula (x20)xπ. Also, the conductor cross-sectional area S2 of insulated wire 4 is S2 = (D3 / 2). 2 It can be calculated using the formula ×7 × π.

[0026] Incidentally, in composite cables having multiple wires (coaxial wires and insulated wires), the thickness and composition of the conductors constituting each wire affect bending durability. For example, when comparing single wires of different diameters, the one with the larger diameter is more prone to greater bending stress and therefore more likely to break. Also, when comparing a single wire with a stranded wire made by twisting together multiple strands of the same diameter as the single wire, the single wire is more prone to breakage. The upper and lower limits of the above numerical ranges are set to take these factors into consideration and to suppress the concentration of stress in some conductors that causes breakage when the composite cable 1 is bent.

[0027] For example, the conductor diameter D of the central conductor 21 of the large-diameter coaxial cable 2. 11 If the wire diameter D3 of the strands 41 of the insulated wire 4 is greater than the wire diameter D3 of the central conductor 21 when the composite cable 1 is bent, stress will concentrate on the central conductor 21 and wire breakage will be more likely to occur. On the other hand, if the wire diameter D3 of the strands 41 of the insulated wire 4 is greater than the conductor diameter D of the central conductor 21 11 If the wire is, for example, more than twice as large, breakage is more likely to occur in the strand 41.

[0028] Furthermore, if the difference between the conductor cross-sectional area S1 of the large-diameter coaxial cable 2 and the conductor cross-sectional area S2 of the insulated wire 4 is too large, the wire with the larger conductor cross-sectional area is more prone to breakage. In this embodiment, the insulated wire 4 is used as a power line, and considering that the required current capacity is relatively large, the desirable numerical range for S2 / S1 is set as described above. Note that the small-diameter coaxial cable 3 is less susceptible to bending stress compared to the large-diameter coaxial cable 2, so here the conductor cross-sectional area S1 of the large-diameter coaxial cable 2 is used as the comparison point with the conductor cross-sectional area S2 of the insulated wire 4.

[0029] Furthermore, in a large-diameter coaxial cable 2, the number of outer conductors 23 is greater than the number of central conductors 21, so the conductor diameter D of the outer conductors 23 12 The conductor diameter D of the central conductor 21 is 11 The following is acceptable. However, the conductor diameter D of the outer conductor 23 is... 12 If it is too thin, manufacturing difficulties will increase, so as mentioned above, D 12 / D 11 A desirable numerical range is set. The same applies to the small-diameter coaxial cable 3.

[0030] As an example, consider the conductor diameter D of the central conductor 21 of the large-diameter coaxial cable 2. 11 This is equivalent to 46AWG (American Wire Gauge) with a diameter of 0.04 mm, and the conductor diameter D of the central conductor 31 of the small-diameter coaxial cable 3. 21 This is equivalent to 50AWG, with a diameter of 0.025mm. The conductor diameter D of the outer conductors 23 and 33 of the large and small diameter coaxial cables 2 and 3. 12 ,D 22The diameter is 0.02 mm. Also, the wire diameter D3 of the strand 41 of the insulated wire 4 is 0.04 mm, equivalent to 46 AWG, and the conductor diameter D4 of the stranded conductor 40 is 0.12 mm, equivalent to 38 AWG (three times the wire diameter D3 of the strand 41).

[0031] When the conductor diameter and strand diameter were set in this manner, the composite cable 1 achieved high bending durability. Specifically, when a bending durability test was conducted using a single wire with the same cross-sectional area as the stranded conductor 40 (cross-sectional area of ​​the strand 41 × 7) instead of the stranded conductor 40 of the insulated wire 4, the single wire broke after approximately 4000 bends. However, with the composite cable 1, where the conductor diameter and strand diameter were set as described above, no breaks occurred in any of the wires even after exceeding the number of bends at which breakage occurred when using a single wire with the same cross-sectional area as the stranded conductor 40. This demonstrated high bending durability that met the required specifications for a composite cable for intravascular endoscopy catheters.

[0032] Note that the conductor diameter D of the central conductors 21 and 31 of the large and small diameter coaxial cables 2 and 3 is... 11 ,D 21 For example, the conductor diameter D4 of the stranded conductor 40 of the insulated wire 4 can be set between 0.021 mm (equivalent to 52 AWG) and 0.064 mm (equivalent to 42 AWG).

[0033] (Effects of the embodiment) According to the embodiment described above, when the composite cable 1 is bent, stress concentration on either the central conductors 21, 31 of the large-diameter and small-diameter coaxial wires 2, 3 or the multiple strands 41 of the insulated wire 4 is suppressed. Therefore, it is possible to achieve high bending durability while making the composite cable 1 thinner.

[0034] In the above embodiment, the case where the configuration of multiple insulated wires 4 is the same was described. However, in the case of a composite cable having multiple insulated wires with different conductor cross-sectional areas, which is the sum of the cross-sectional areas of multiple strands, the conductor cross-sectional area of ​​the insulated wire with the largest conductor cross-sectional area is defined as S2, and the value obtained by dividing S2 by the conductor cross-sectional area S1 of the coaxial wire with the largest conductor cross-sectional area (large-diameter coaxial wire 2 in the above embodiment) (S2 / S1) should be within the above numerical range.

[0035] Furthermore, regarding the ratio of the conductor diameter of the central conductor to the conductor diameter of the outer conductors of the coaxial cable, it is sufficient that this ratio (conductor diameter of the outer conductor / conductor diameter of the central conductor) in the coaxial cable with the largest conductor diameter of the central conductor (large-diameter coaxial cable 2 in the above embodiment) is within the above numerical range.

[0036] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0037] [1] A composite cable (1) having coaxial cables (2,3) and insulated wires (4), wherein the coaxial cables (2,3) have a central conductor (21,31), an insulator (22,32) covering the central conductor (21,31), a plurality of outer conductors (23,33) arranged on the outer circumference of the insulator (22,32), and an outer sheath (24,34) covering the plurality of outer conductors (23,33), the insulated wires (4) consist of a stranded conductor (40) made by twisting together a plurality of strands (41), and an insulating sheath (42) covering the stranded conductor (40), the central conductor (21,31) of the coaxial cables (2,3) is a single wire, and the conductor diameter (D 11 ,D 21 The composite cable (1) is such that the diameter of the strands (D3) of the plurality of strands (41) of the insulated wire (4) is less than or equal to the diameter of the strands (D3) of the plurality of strands (41) of the insulated wire (4).

[0038] [2] Conductor diameter (D 11 ,D21 The composite cable (1) described in [1] above, wherein the diameter of the strands (D3) of the plurality of strands (41) of the insulated wire (4) is more than half of the strand diameter (D3) of the plurality of strands (41).

[0039] [3] Conductor diameter (D 11 ,D 21 A composite cable (1) as described in [1] or [2] above, wherein the length of the cable is 0.064 mm or less.

[0040] [4] A composite cable (1) according to any one of [1] to [3] above, wherein S1 is the sum of the cross-sectional areas of the central conductor (21, 31) and the plurality of outer conductors (23, 33), and S2 is the sum of the cross-sectional areas of the plurality of strands (41) in the stranded conductor (40), and the value of S2 / S1 is 0.6 or more and 4.5 or less.

[0041] [5] The composite cable (1) described in [4] above, wherein the value of S2 / S1 is 1.0 or more and 3.0 or less.

[0042] [6] A composite cable (1) according to any of [1] to [5] above, wherein when the conductor diameter of the central conductor (21) is D1 and the conductor diameters of the plurality of outer conductors (23) are D2, the value of D2 / D1 is 0.35 or more and 1.0 or less.

[0043] [7] The composite cable (1) described in [6] above, wherein the value of D2 / D1 is 0.5 or more and 0.85 or less.

[0044] Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention.

[0045] Furthermore, the present invention can be implemented with appropriate modifications without departing from its spirit. For example, in the above embodiment, a case was described in which the composite cable 1 has two large-diameter coaxial wires 2, one small-diameter coaxial wire 3, and three insulated wires 4, but the configuration of the composite cable is not limited to this, and the number of coaxial wires and insulated wires can be changed as appropriate. Also, the applications of the composite cable are not limited to intravascular endoscopy catheters, but can be used in various applications where a small diameter and flexibility are required.

[0046] Furthermore, although the above embodiment described a case in which seven strands 41 are twisted together to form the stranded conductor 40 of the insulated wire 4, the number of strands in the insulated wire is not limited to seven. For example, as shown in Figure 4, 19 strands 411 may be twisted together to form the stranded conductor 40 of the insulated wire 4. In this case, the strand diameter D of the strands 411 is... 31 0.05mm (conductor diameter D of stranded conductor 40) 41 By setting the thickness to 0.25 mm, a stranded conductor 40 equivalent to 32 AWG can be obtained. [Explanation of Symbols]

[0047] 1…Composite cable 10…Cable core 11…Intervening 2,3…Coaxial line 21, 31… Center conductor 22, 32… Insulator 23, 33…Outer conductor 24, 34…Sheath 4...Insulated wire 40...Stranded conductor 41,411...Strand wire 42...Insulation coating

Claims

1. A composite cable having an interposition made of a fibrous material, a plurality of coaxial wires, and a plurality of insulated wires, Each of the aforementioned coaxial cables has a central conductor, an insulator covering the central conductor, a plurality of outer conductors arranged on the outer circumference of the insulator, and an outer sheath covering the plurality of outer conductors. Each of the aforementioned multiple insulated wires consists of a stranded conductor formed by twisting together multiple strands of wire, and an insulating coating that covers the stranded conductor. The intervening is located in the center of the composite cable. The plurality of coaxial cables and the plurality of insulated wires are arranged to surround the intervening, The aforementioned plurality of coaxial cables include large-diameter coaxial cables and small-diameter coaxial cables. The large-diameter coaxial cable and the small-diameter coaxial cable have a single central conductor. The conductor diameter of the central conductor of the large-diameter coaxial cable is less than or equal to the strand diameter of the plurality of strands of the insulated wire. Composite cable.

2. The conductor diameter of the central conductor of the large-diameter coaxial cable is more than half the diameter of the strands of the plurality of strands of the insulated wire. The composite cable according to claim 1.

3. The conductor diameter of the central conductor of the large-diameter coaxial cable is 0.064 mm or less. The composite cable according to claim 1 or 2.

4. The sum of the cross-sectional areas of the central conductor and the plurality of outer conductors in the large-diameter coaxial cable is S １ Let S be the sum of the cross-sectional areas of the multiple strands in the stranded conductor. ２ In that case, S ２ / S １ The value is between 0.6 and 4.

5. A composite cable according to any one of claims 1 to 3.

5. The aforementioned S ２ / S １ The value is between 1.0 and 3.

0. The composite cable according to claim 4.

6. The conductor diameter of the central conductor of the large-diameter coaxial cable is D. １ The conductor diameter of the plurality of outer conductors is set to D. ２ In that case, D ２ / D １ where the value of is 0.35 or more and 1.0 or less A composite cable according to any one of claims 1 to 5.

7. The conductor diameter of the outer conductor of the large-diameter coaxial cable and the conductor diameter of the outer conductor of the small-diameter coaxial cable are the same. A composite cable according to any one of claims 1 to 6.

8. The conductor diameter of the central conductor of the small-diameter coaxial cable is smaller than the conductor diameter of the central conductor of the large-diameter coaxial cable. A composite cable according to any one of claims 1 to 7.

9. Each of the aforementioned coaxial cables and insulated wires is in contact with an adjacent coaxial cable or insulated wire. A composite cable according to any one of claims 1 to 8.

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