Composite cable
The composite cable design addresses the challenge of miniaturization and durability by arranging power or drain lines in the valleys between signal lines, using high-tensile strength materials, resulting in a cable that withstands bending without breaking and facilitates easy connection.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- PROTERIAL LTD
- Filing Date
- 2022-11-17
- Publication Date
- 2026-06-30
AI Technical Summary
The challenge is to provide an extremely thin composite cable with a diameter of 1.0 mm or less that can withstand repeated bending and other movements without breaking, as robots have become miniaturized and require increased cable wiring due to improved functions and performance.
A composite cable design comprising a cable core with signal lines, power lines, and drain lines, where the outermost layer is a shielding layer, and the power or drain lines are arranged in the valleys between contact signal lines, with a binding tape and sheath, using high-tensile strength copper alloy wires and fluororesin insulators to enhance durability.
The design results in a cable that is less prone to breakage even with repeated bending, allowing for easier connection to connectors and components, and reduces the overall cable diameter to 1.0 mm or less.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a composite cable.
Background Art
[0002] Conventionally, for example, in robots such as industrial robots, there is a composite cable that is connected to a servo motor via a connector as a cable wired inside the robot. As a composite cable, there is known a composite cable in which each of a power line and a signal line is covered with a shield, and these power line and signal line are collectively covered with a sheath (see, for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In recent years, robots have been miniaturized, so the wiring space for wiring cables has become very narrow. In addition, in robots, the improvement of functions and performance has also progressed, and accordingly, the types and the number of cables wired in the robot have increased. Therefore, as a cable wired in a robot, an extremely thin composite cable having an outer diameter of, for example, 1.0 mm or less is desired.
[0005] The composite cable wired in a robot is wired through a movable part. Therefore, even for an extremely thin composite cable, it is required that it is difficult to break when operations such as bending, twisting, and swinging (hereinafter also referred to as "operations such as bending") are repeatedly applied.
[0006] Therefore, an object of the present invention is to provide an extremely thin composite cable that is difficult to break even when operations such as bending are repeatedly applied. [Means for solving the problem]
[0007] The present invention aims to solve the above problems and provides a composite cable having an outer diameter of 1.0 mm or less, comprising a cable core composed of a plurality of signal lines, power lines having a smaller outer diameter than the signal lines, and drain lines having a smaller outer diameter than the power lines, a binding tape wrapped around the cable core, and a sheath covering the binding tape, wherein the outermost layer of the signal lines is a shielding layer, and the cable core has either the power lines or the drain lines arranged in each of the valleys between the plurality of signal lines which are arranged in contact with each other. [Effects of the Invention]
[0008] According to the present invention, it is possible to provide an ultra-thin composite cable that is less prone to breakage even when subjected to repeated bending and other movements. [Brief explanation of the drawing]
[0009] [Figure 1] This is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of a composite cable according to one embodiment of the present invention. [Figure 2] This diagram shows the terminal end of a composite cable during wiring. [Modes for carrying out the invention]
[0010] [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0011] Figure 1 is a cross-sectional view showing a cross-section perpendicular to the longitudinal direction of the composite cable 1 according to this embodiment. The composite cable 1 is used, for example, as a cable wired to a robot such as a small industrial robot, and is a cable for movable parts that is wired through movable parts. Furthermore, the composite cable 1 is an extremely thin cable with an outer diameter of 1.0 mm or less. In addition to the movable parts of robots, the composite cable 1 according to this embodiment may also be applied to cables wired to automobiles, medical devices, etc. Examples of medical devices include endoscopic catheters inserted into blood vessels, etc.
[0012] The outer diameters of the composite cable 1, signal line 2, power line 3, and drain line 4, described later, can be measured using a caliper, micrometer, or microscope in accordance with the test method compliant with JIS C 3005.
[0013] As shown in Figure 1, the composite cable 1 comprises a cable core 5 formed by twisting together multiple signal lines 2 for signal transmission, multiple power lines 3 for power supply, and a drain line 4 for grounding, a binding tape 6 wrapped around the cable core 5, and a sheath 7 covering the binding tape 6.
[0014] (Signal line 2) The signal line 2 consists of an inner conductor 21, an insulator 22 surrounding the inner conductor 21, and a shield layer 23 that surrounds the insulator 22 and forms the outermost layer of the signal line 2. The inner conductor 21 is made up of a stranded conductor formed by concentrically twisting together multiple strands 21a made of copper alloy wire. In this embodiment, tin-plated copper alloy wire is used as the strands 21a of the inner conductor 21. In this embodiment, the outer diameter of the cable is extremely thin, less than 1.0 mm, and the inner conductor 21 is also very thin (for example, the outer diameter is less than 0.1 mm). Therefore, it is necessary to use a high-strength copper alloy wire as the strands 21a of the inner conductor 21 to increase its resistance to repeated bending and other movements (i.e., to make it less prone to breakage). Specifically, it is preferable to use a copper alloy wire with a tensile strength of 800 MPa or more as the strands 21a used for the inner conductor 21. Examples of copper alloy wires with a tensile strength of 800 MPa or more include Cu-Sn-In alloys containing tin (Sn) and indium (In), with the remainder being copper (Cu) and unavoidable impurities; Cu-In alloys containing indium (In), with the remainder being copper (Cu) and unavoidable impurities; and Cu-Ag alloys containing silver (Ag), with the remainder being copper and unavoidable impurities.
[0015] Here, three signal wires 2 were used, but the number of signal wires 2 is not limited to these. However, from the perspective of reducing the outer diameter, it is desirable to use three signal wires 2 so that no dead space is created in the center when bundled. Here, three signal wires 2 with the same structure were used.
[0016] As the insulator 22, it is desirable to use a fluororesin that can be made thin. The fluororesin used for the insulator 22 of the signal line 2 should be one that provides good transmission characteristics, for example, PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) can be used.
[0017] The shield layer 23 consists of a horizontally wound shield formed by spirally winding multiple strands 23a made of copper alloy wire. Similar to the internal conductor 21, it is desirable to use copper alloy wire with a tensile strength of 800 MPa or higher for the strands 23a used in the shield layer 23. Examples of copper alloy wires with a tensile strength of 800 MPa or higher include Cu-Sn-In alloys containing tin (Sn) and indium (In), with the remainder being copper (Cu) and unavoidable impurities; Cu-In alloys containing indium (In), with the remainder being copper (Cu) and unavoidable impurities; and Cu-Ag alloys containing silver (Ag), with the remainder being copper and unavoidable impurities.
[0018] Furthermore, in order to prevent wear on the surfaces of other components that come into contact with the strands 23a due to repeated bending and other movements (for example, the insulator 22, the insulator 32 of the power line 3, etc.) and wear on the strands 23a due to friction between the shield layers 23, it is desirable to use strands 23a with good surface slipperiness for the shield layer 23. Here, tin-plated copper alloy wire was used as the strands 23a.
[0019] In this embodiment, the signal line 2 has a shield layer 23 as its outermost layer, and the jacket covering the shield layer 23 is omitted. This makes it possible to reduce the outer diameter of the composite cable 1 (i.e., it becomes easy to make a composite cable 1 with an outer diameter of 1 mm or less), and when processing the end of the composite cable 1, multiple signal lines 2 can be extended from the end of the sheath 7 with the shield layer 23 as the outermost layer and connected to the connector, making it easier to arrange the internal conductors 21 at a narrow pitch when the multiple extended signal lines 2 are arranged in parallel on the connector. The outer diameter of the signal line 2 should be larger than the outer diameter of the power line 3 and drain line 4, which will be described later. For example, the outer diameter of the signal line 2 is 0.3 mm or less. Here, the outer diameter of the signal line 2 is set to 0.3 mm. The conductor size of the signal line 2 is set to 40 AWG.
[0020] (power line 3) The power line 3 is an insulated wire composed of a conductor 31 and an insulator 32 that covers the periphery of the conductor 31. The conductor 31 is composed of a stranded conductor formed by concentrically twisting a plurality of strands 31a made of copper alloy wires. Here, in order to reduce the conductor resistance as much as possible, silver-plated copper alloy wires were used as the strands 31a of the conductor 31. In order to make it difficult for the wire to break when repeated operations such as bending are applied, as the strand 31a used for the conductor 31, a copper alloy wire with a tensile strength of 800 MPa or more may be used in the same manner as the internal conductor 21 and the shield layer 23 of the signal line 2 described above. Examples of copper alloy wires with a tensile strength of 800 MPa or more include Cu-Sn-In alloys containing tin (Sn) and indium (In) and having the balance being copper (Cu) and inevitable impurities, Cu-In alloys containing indium (In) and having the balance being copper (Cu) and inevitable impurities, and copper alloy wires made of Cu-Ag alloys containing silver (Ag) and having the balance being copper and inevitable impurities, etc.
[0021] As the insulator 32, it is desirable to use a fluororesin that can have a reduced thickness. The fluororesin used for the insulator 32 is preferably harder than the fluororesin used for the insulator 22, and for example, ETFE (ethylene tetrafluoroethylene copolymer) can be used. By using an insulator 32 made of ETFE, when repeated operations such as bending are applied to the composite cable 1, the insulator 32 is less likely to wear due to rubbing against the shield layer 23 of the signal line 2, and disconnection is less likely to occur.
[0022] The outer diameter of the power line 3 is smaller than that of the signal line 2 and larger than that of the drain line 4. More specifically, the outer diameter of the power line 3 is greater than 0.4 times and less than or equal to 0.5 times the outer diameter of the signal line 2. By setting the outer diameter of the power line 3 within the above range, it is possible to achieve both reducing the outer diameter of the composite cable 1 and making it difficult for disconnection to occur when repeated operations such as bending are applied to the composite cable 1. Here, the outer diameter of the power line 3 was set to 0.145 mm, which is about 0.48 times the outer diameter of the signal line 2. Also, the conductor size of the power line 3 was set to 42 AWG.
[0023] Here, two power lines 3 are used, but the number of power lines 3 is not limited to these. However, due to the structure of the cable core 5 described later, the number of power lines 3 is preferably less than the number of signal lines 2, and preferably the number of signal lines 2 minus 1. Note that multiple insulated wires twisted together may be used as a single power line 3. In this case, a covering member that covers the entire area around multiple insulated wires may be provided.
[0024] (Drain wire 4) The drain wire 4 is composed of a stranded conductor made by concentrically twisting together multiple strands 4a made of copper alloy wire. The strands 4a of the drain wire 4 should preferably be copper alloy wire with a tensile strength of 800 MPa or more, similar to the inner conductor 21 and shield layer 23 of the signal wire 2, and the conductor 31 of the power wire 3. While the drain wire 4 shown in Figure 1 is composed of a stranded conductor made concentrically, it is not limited to this and may be composed of a stranded conductor made in a bundled twist. Examples of copper alloy wires with a tensile strength of 800 MPa or more include Cu-Sn-In alloys containing tin (Sn) and indium (In), with the remainder being copper (Cu) and unavoidable impurities; Cu-In alloys containing indium (In), with the remainder being copper (Cu) and unavoidable impurities; and Cu-Ag alloys containing silver (Ag), with the remainder being copper and unavoidable impurities.
[0025] The outer diameter of the drain wire 4 is smaller than that of the signal wire 2 and the power wire 3. More specifically, the outer diameter of the drain wire 4 should be 0.4 times or less the outer diameter of the signal wire 2. By setting the outer diameter of the drain wire 4 within the above range, it is possible to reduce the outer diameter of the composite cable 1 and to make it less likely for the composite cable 1 to break when repeated bending or other movements are applied to it. In this embodiment, the outer diameter of the drain wire 4 is set to 0.09 mm, which is 0.3 times the outer diameter of the signal wire 2.
[0026] (Cable core 5) The cable core 5 is constructed by twisting together three signal lines 2, two power lines 3, and one drain line 4. More specifically, in the cable core 5, the three signal lines 2 are arranged in contact with each other. Then, in each of the three valleys 9 located outside the portion in the cable radial direction, between adjacent signal lines 2 in the circumferential direction of the cable where the signal lines 2 are in contact with each other, the two power lines 3 and the one drain line 4 are individually arranged. Here, "the three signal lines 2 are arranged in contact with each other" means that the three signal lines 2 are twisted together or bundled together with their outermost shield layers 23 in contact with each other. In this embodiment, in the cable core 5, the three signal lines 2 are twisted together in contact with each other and arranged at the center of the cable.
[0027] In this embodiment, the outer diameter of the drain wire 4 is smaller than the outer diameters of the signal wire 2 and the power wire 3 (less than 0.4 times the outer diameter of the signal wire 2). As a result, in the composite cable 1, as shown in Figure 1, a clearance (gap) 8 is formed around the drain wire 4, allowing the drain wire 4 to move in the radial direction of the cable between it and the binding tape 6 (i.e., a clearance for moving the drain wire 4 in the radial direction of the cable). No interposition is placed in this clearance 8. This prevents the drain wire 4 from breaking due to friction at the point where it contacts the shield layer 23 of the signal wire 2 when the composite cable 1 is repeatedly subjected to bending or other movements. Although a clearance 8 exists, the cable core 5 is twisted together as a whole, so the drain wire 4 will inevitably come into contact with the shield layer 23 of the signal wire 2 at some point along the longitudinal direction of the cable due to the effects of gravity, etc., and will be electrically connected.
[0028] Furthermore, it is desirable that the winding direction of the multiple strands 23a constituting the shield layer 23, which consists of a horizontally wound shield, the twisting direction of the multiple strands 4a constituting the drain wire 4, and the twisting direction of the cable core 5 (i.e., the twisting direction when the signal line 2, power line 3, and drain wire 4 are twisted together) be the same. This allows the shield layer 23, drain wire 4, and cable core 5 to loosen and tighten their twists in sync when the composite cable 1 is repeatedly subjected to bending or other movements, thereby suppressing excessive load on each of the signal line 2, power line 3, and drain wire 4, and also suppressing friction caused by them coming into contact with each other. As a result, the composite cable 1 is less likely to break even when repeatedly subjected to bending or other movements. Note that the winding direction of the shield layer 23 is the direction in which the strands 23a rotate from one end to the other when viewed from one end in the longitudinal direction of the composite cable 1. The twisting direction of the drain wire 4 is the direction in which the strands 4a rotate from one end to the other when viewed from one end in the longitudinal direction of the drain wire 4 (the end on the longitudinal side of the composite cable 1). The twisting direction of the cable core 5 is the direction in which the signal wire 2, power wire 3, and drain wire 4 rotate from one end to the other when viewed from one end in the longitudinal direction of the composite cable 1.
[0029] (Bind Tape 6) The binding tape 6 consists of a tape material that is spirally wrapped around the cable core 5 and serves to hold the twist of the cable core 5 in place so that it does not unravel. The binding tape 6 can be made of nonwoven fabric, paper, resin, or the like. As shown in Figure 1, the binding tape 6 is spirally wrapped around the cable core 5 in a cross section perpendicular to the longitudinal direction of the composite cable 1, in contact with the signal lines 2 and power lines 3 that make up the cable core 5. The direction in which the binding tape 6 is wrapped should be the same as the twist direction of the cable core 5. This makes it less likely for the cable to break even if the composite cable 1 is repeatedly subjected to bending or other movements.
[0030] (Sheath 7) The sheath 7 is provided to surround the binding tape 6 and serves to protect the cable core 5. It is desirable to use a fluororesin that can be made thin for the sheath 7. In the composite cable 1, the shield layer that covers the cable core 5 as a whole is omitted in order to reduce the diameter. That is, in the composite cable 1, the sheath 7 is provided in a state where the inner surface of the sheath 7 is in contact with the surface of the binding tape 6, by extruding a fluororesin resin in a tubular shape onto the surface of the binding tape 6. The outer diameter of the sheath 7, i.e., the outer diameter of the composite cable 1, is 1.0 mm or less. Here, the outer diameter of the composite cable 1 is set to approximately 0.9 mm.
[0031] (Wiring of composite cable 1) Because the composite cable 1 has an outer diameter of 1.0 mm or less, it can be difficult to connect connectors, sensor modules, and other connected components to the ends of the composite cable 1 after it has been wired to an industrial robot or the like. Furthermore, when connecting connectors, sensor modules, and other components to the ends of the wired composite cable 1 after it has been wired to an industrial robot or the like, it is difficult to process the ends of the wired composite cable 1 or connect them to the non-connected components. Therefore, when wiring the composite cable 1 to an industrial robot or the like, it is desirable to attach the connected components 91 to the ends of the composite cable 1 in advance, as shown in Figure 2, and then wire the composite cable 1 with the connected components 91 attached.
[0032] In this case, to prevent the connected member 91 from being damaged by colliding with surrounding members of the wiring path, it is preferable to cover the connected member 91 and the terminal portion of the composite cable 1 with a protective cover member 92, and to perform the wiring of the unconnected member 91 and the composite cable 1 with the protective cover member 92 attached. The cover member 92 can be made of a resin such as rubber. The cover member 92 is formed in the shape of a bag (dome-shaped or cap-shaped) with an opening into which the connected member 91 and the terminal portion of the composite cable 1 are inserted. However, the shape of the cover member 92 is not limited to this.
[0033] (Operation and Effects of the Embodiment) As described above, in the composite cable 1 according to this embodiment, the outermost layer of the signal line 2 is a shield layer 23, and in the cable core 5, either a power line 3 or a drain line 4 is placed in each of the valleys 9 between the multiple signal lines 2 which are arranged in contact with each other, the outer diameter of the drain line 4 is smaller than the outer diameters of the signal line 2 and the power line 3, and there is a gap 8 between the drain line 4 and the binding tape 6 that allows the drain line 4 to move in the radial direction of the cable.
[0034] By omitting the jacket of signal line 2, the diameter of the composite cable 1 can be reduced. However, since the outermost layer of signal line 2 becomes the shield layer 23, friction with this shield layer 23 makes the drain wire 4 prone to breakage. In this embodiment, the outer diameter of the drain wire 4 is deliberately made smaller than the outer diameters of signal line 2 and power line 3, and the structure is designed so that the drain wire 4 can move into the gap 9 between adjacent signal lines 2. This creates a gap 8 around the drain wire 4, suppressing breakage of the drain wire 4 due to friction with the shield layer 23. As a result, it is possible to realize an extremely thin composite cable 1 with an outer diameter of 1.0 mm or less that is less prone to breakage even when repeatedly bent at a small bending radius, such as five times or less of the outer diameter of the composite cable 1.
[0035] Furthermore, by omitting the jacket for signal line 2, the distance between signal lines 2 can be reduced and they can be arranged in parallel when processing the terminals of the composite cable 1, making it easier to connect them to connectors and other connected components at a narrow pitch. In addition, the exposed length of the cable core 5 at the terminal of the composite cable 1 (the length of the cable core 5 extending from the end of the sheath 7) can be shortened, and this also contributes to miniaturization of the connected components 91, such as connectors, that are connected to the ends of the composite cable 1.
[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 and other symbols 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 an outer diameter of 1.0 mm or less, comprising a cable core (5) composed of a plurality of signal lines (2), power lines (3) having a smaller outer diameter than the signal lines (2), and drain lines (4) having a smaller outer diameter than the power lines (3), a binding tape (6) wrapped around the cable core (5), and a sheath (7) covering the binding tape (6), wherein the outermost layer of the signal lines (2) is a shield layer (23), and the cable core (5) has either the power lines (3) or the drain lines (4) arranged in each of the valleys (9) between the plurality of signal lines (2) which are arranged in contact with each other.
[0038] [2] The composite cable according to [1], wherein there is a gap (8) between the drain wire (4) and the binding tape (6) that allows the drain wire (4) to move in the radial direction of the cable.
[0039] [3] The composite cable (1) according to [1], wherein the outer diameter of the drain wire (4) is 0.4 times or less the outer diameter of the signal wire (2).
[0040] [4] The composite cable (1) according to [1], wherein the outer diameter of the power line (3) is greater than 0.4 times and less than or equal to 0.5 times the outer diameter of the signal line (2).
[0041] [5] The composite cable (1) described in [1], wherein each of the internal conductor (21) of the signal line (2), the conductor (31) of the power line (3), and the drain line (4) is made up of strands (21a, 31a, 4a) made of copper alloy wire having a tensile strength of 800 MPa or more, twisted together, and the shield layer (23) is a horizontally wound shield made by spirally winding strands (23a) made of copper alloy wire having a tensile strength of 800 MPa or more.
[0042] [6] The composite cable (1) according to [5], wherein the winding direction of the horizontally wound shield, the twisting direction of the drain wire (4), and the twisting direction of the cable core (5) are in the same direction.
[0043] [7] The composite cable (1) according to [1], wherein the cable core (5) comprises three signal lines (2), two power lines (3), and one drain line (4).
[0044] [8] The cable core (5) is a composite cable (1) as described in [1], in which the plurality of signal lines (2) are used for signal transmission, the plurality of power lines (3) are used for power supply, and the drain line (4) is used for grounding.
[0045] (Note) 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. In addition, the present invention can be implemented with appropriate modifications without departing from its spirit. [Explanation of Symbols]
[0046] 1…Composite cable 2… Signal line 3...Power line 4…Drain wire 5… Cable core 6…Binding tape 7...Sheath 8... Gap 9... the cleavage area 21…Internal conductor 22...Insulator 23...Shield layer 31...Conductor 32…Insulator
Claims
1. A composite cable with an outer diameter of 1.0 mm or less, A cable core composed of multiple signal lines, power lines having a smaller outer diameter than the signal lines, and drain lines having a smaller outer diameter than the power lines, The binding tape wrapped around the cable core, The binding tape comprises a sheath that covers the periphery of the binding tape, The aforementioned signal line consists of a shielding layer as its outermost layer. In the cable core, either the power line or the drain line is placed in each of the valleys between the plurality of signal lines that are arranged in contact with each other. A gap is provided between the drain wire and the binding tape, allowing the drain wire to move in the radial direction of the cable. Composite cable.
2. The outer diameter of the drain wire is 0.4 times or less the outer diameter of the signal wire. The composite cable according to claim 1.
3. The outer diameter of the power line is greater than 0.4 times that of the signal line and less than or equal to 0.5 times that of the signal line. The composite cable according to claim 1.
4. The internal conductor of the signal line, the conductor of the power line, and the drain wire are each constructed by twisting together strands of copper alloy wire with a tensile strength of 800 MPa or more. The shield layer consists of a horizontally wound shield made by spirally winding strands of copper alloy wire with a tensile strength of 800 MPa or more. The composite cable according to claim 1.
5. The winding direction of the aforementioned horizontally wound shield, the twisting direction of the aforementioned drain wire, and the twisting direction of the aforementioned cable core are all in the same direction. The composite cable according to claim 4.
6. The cable core has three signal lines, two power lines, and one drain line. The composite cable according to claim 1.
7. The cable core is configured such that the multiple signal lines are used for signal transmission, the multiple power lines are used for power supply, and the drain line is used for grounding. The composite cable according to claim 1.