Multi-core cable, disconnection detection device

Abstract

Provided is a multicore cable comprising: a plurality of covered wires each including a wire conductor that is a stranded wire of a plurality of wire strands, and a wire cover covering the outer circumference of the wire conductor; a detection wire having a detection wire conductor that is a stranded wire of a plurality of detection wire strands; and an outer cover covering an outer circumference of a core containing the plurality of covered wires and the detection wire. The detection wire is disposed in a region surrounded by the plurality of covered wires, and the strand diameter of the detection wire strand is equal to or greater than the strand diameter of the wire strand.

Description

[Technical Field]

[0001] The present disclosure relates to a multi-core cable and a disconnection detection device. [Background technology]

[0002] Patent Document 1 describes an electric brake cable that includes at least one power supply line for supplying power to a motor that serves as a braking source for an electric brake of a vehicle such as an automobile, and at least one signal line for transmitting signals related to the control of the motor. The cable for electric brakes is characterized by comprising at least one insulatingly coated breakage detection wire that is attached to the power supply wire and the signal wire or spirally wound around the corresponding wires, and is configured to break prior to a break in the power supply wire or the signal wire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-166450 Summary of the Invention

[0004] The multi-core cable of the present disclosure includes a plurality of coated electric wires, each having a conductor that is a strand of a plurality of electric wire strands and a wire coating that coats the outer periphery of the conductor; a detection wire having a detection wire conductor which is a twisted wire of a plurality of detection wire strands; an outer sheath that covers an outer periphery of a core that includes the plurality of coated electric wires and the detection wire; the detection wire is disposed within an area surrounded by the plurality of covered electric wires, The wire diameter of the detection wire is equal to or greater than the wire diameter of the electric wire. [Brief explanation of the drawings]

[0005] [Figure 1A] FIG. 1A is a cross-sectional view of a multi-core cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 1B] FIG. 1B is a cross-sectional view of a multi-core cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 1C] FIG. 1C is a cross-sectional view of a multi-core cable according to one embodiment of the present disclosure taken along a plane perpendicular to the longitudinal direction. [Figure 1D] FIG. 1D is a cross-sectional view of a multi-core cable used in a simulation of a bending resistance test, taken along a plane perpendicular to the longitudinal direction. [Figure 2A] FIG. 2A is a cross-sectional view of a plane perpendicular to the longitudinal direction of a sensing line included in a multi-core cable according to one embodiment of the present disclosure. [Figure 2B] FIG. 2B is a cross-sectional view of a plane perpendicular to the longitudinal direction of a sensing line included in a multi-core cable according to one embodiment of the present disclosure. [Figure 3A] FIG. 3A is a diagram illustrating the configuration of a conductive tape. [Figure 3B] FIG. 3B is a diagram illustrating the configuration of the conductive tape. [Figure 4] FIG. 4 is an explanatory diagram of the twist pitch. [Figure 5] FIG. 5 is an explanatory diagram of the bending resistance test. [Figure 6A] FIG. 6A shows the simulation results of the bending resistance test. [Figure 6B] FIG. 6B shows the simulation results of the bending resistance test. [Figure 6C] FIG. 6C shows the simulation results of the bending resistance test. [Figure 7] FIG. 7 is a diagram illustrating the configuration of a disconnection detection device according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] As disclosed in Patent Document 1, in a cable that is prone to bending motion, a disconnection detection wire that predicts disconnection of the electric wires included in the cable has conventionally been disposed.

[0007] However, in a cross section perpendicular to the longitudinal direction of a multi-core cable including a plurality of insulated electric wires, the insulated electric wires are not arranged symmetrically with respect to the center of the cross section, and insulated electric wires with different configurations are arranged along the circumferential direction, making it difficult to predict the magnitude of the load. For this reason, in a multi-core cable with the above configuration, it was sometimes impossible to predict breakage of the insulated electric wires.

[0008] Therefore, there has been a demand for a multi-core cable that includes a plurality of covered electric wires and that can predict breakage of the covered electric wires.

[0009] An object of the present disclosure is to provide a multi-core cable including a plurality of covered electric wires, in which breakage of the covered electric wires can be predicted.

[0010] [Effects of this disclosure] According to the present disclosure, it is possible to provide a multi-core cable including a plurality of covered electric wires, in which breakage of the covered electric wires can be predicted.

[0011] The embodiments for carrying out the invention are described below.

[0012] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements will be denoted by the same reference numerals, and the same description will not be repeated.

[0013] (1) A multi-core cable according to one aspect of the present disclosure includes a plurality of coated electric wires, each having a wire conductor that is a strand of a plurality of electric wire strands and a wire coating that coats the outer periphery of the wire conductor; a detection wire having a detection wire conductor which is a twisted wire of a plurality of detection wire strands; an outer sheath that covers an outer periphery of a core that includes the plurality of coated electric wires and the detection wire; the detection wire is disposed within an area surrounded by the plurality of covered electric wires, The wire diameter of the detection wire is equal to or greater than the wire diameter of the electric wire.

[0014] By making the wire diameter of the detection wire element of the detection wire equal to or greater than the wire diameter of the electric wire element of the insulated electric wire, the detection wire conductor of the detection wire can be configured to break before the electric wire conductor of the insulated electric wire when repeatedly bent.

[0015] In a multi-core cable including a plurality of covered electric wires according to one embodiment of the present disclosure, the detection wire is disposed within an area surrounded by the plurality of covered electric wires. Therefore, even if covered electric wires with different configurations are disposed along the circumferential direction in a cross section perpendicular to the longitudinal direction of the multi-core cable and the covered electric wires are not disposed symmetrically with respect to the center of the cross section, a greater load is applied to the detection wire than to the other covered electric wires when the multi-core cable is repeatedly bent. Furthermore, by disposing the detection wire within an area surrounded by the plurality of covered electric wires, the position of the detection wire within the core is stable even when the multi-core cable is repeatedly bent. Therefore, by measuring the electrical characteristics of the detection wire conductor and evaluating the condition of the detection wire conductor, it is possible to predict the breakage of the covered electric wire at an appropriate time.

[0016] (2) The diameter of the detection wire may be larger than the diameter of the electric wire.

[0017] By making the diameter of the detection wire strands larger than that of the insulated wire strands, the detection wire is more likely to break than the insulated wire when the multi-core cable is repeatedly bent, which allows for early and accurate prediction of wire breakage in the insulated wire.

[0018] (3) The detection wire includes a detection wire covering that covers the outer periphery of the detection wire conductor. The detection wire may be a coaxial cable having a shield conductor covering the outer periphery of the detection wire covering.

[0019] When measuring the characteristic impedance between two conductors, for example, a measuring device is connected between the detection line conductor and the shield conductor of the detection line. By keeping the positions of the detection line conductor and the shield conductor of the detection line constant and not placing any other covered wires between them, noise can be suppressed when measuring the characteristic impedance, enabling stable measurements.

[0020] (4) The coated electric wire includes a power line, the power supply line includes a first stranded wire formed by twisting together a plurality of the electric wire strands, and a second stranded wire formed by twisting together a plurality of the first stranded wires, The twist pitch of the detection line conductor may be longer than the twist pitch of the first stranded wire.

[0021] By making the twist pitch of the detection wire conductor longer than the twist pitch of the first twisted wire in the power line, the detection wire becomes more susceptible to breakage than the power line. Therefore, by measuring the electrical characteristics of the detection wire conductor in the detection wire and evaluating the condition of the detection wire conductor, it is possible to early and accurately predict breakage in the power line, which is one of the covered wires in a multi-core cable and for which breakage prediction is particularly required.

[0022] (5) The coated electric wire includes a power line and a communication line, a conductor cross-sectional area S1 of the electric wire conductor of the power supply line, a conductor cross-sectional area S2 of the electric wire conductor of the communication line, and a conductor cross-sectional area S3 of the detection line conductor, The relationship may be S1>S2≧S3.

[0023] When the conductor cross-sectional area S1 of the wire conductor of the power line, the conductor cross-sectional area S2 of the wire conductor of the communication line, and the conductor cross-sectional area S3 of the detection line conductor of the detection line satisfy the above relationship, the detection line can be appropriately positioned within an area surrounded by multiple insulated wires.

[0024] (6) The core is formed by twisting together a plurality of the coated electric wires and the detection wire, The coated electric wire includes two power wires, In the core, a first power supply line connected to a ground potential and the detection line may be arranged to be in contact with each other and twisted together.

[0025] By twisting the detection line and the first power line connected to the ground potential together in contact with each other, noise is suppressed when measuring the characteristic impedance, making it possible to measure the characteristic impedance easily and stably.

[0026] (7) A shield layer covering the outer periphery of the core is provided. The shielding layer may be disposed between the core and the jacket.

[0027] In a cross section perpendicular to the longitudinal direction of the multi-core cable, the shield layer is disposed outside the insulated wires and the detection wire. Therefore, when the multi-core cable is suddenly subjected to an external impact or when it comes into contact with or is subjected to friction with an external object, the shield layer is more likely to receive a larger load and break than the insulated wires and the detection wire. Therefore, by disposing the shield layer and detecting damage or breakage in the shield layer, it is possible to sensitively detect signs of damage to the insulated wire caused by impact or external injury. As a result, the accuracy of predicting breakage of the insulated wire can be improved.

[0028] (8) having a drain wire; the shield layer has a structure in which a conductive layer disposed on the core side and a base material containing an insulating material are laminated, The drain line may be in contact with the conductive layer.

[0029] To evaluate whether the shield layer is broken, it is necessary to electrically connect the shield layer to an external measuring device. If the shield layer is made of conductive tape or the like, it may be difficult to connect the shield layer directly to the terminal. For this reason, by providing a drain wire and keeping the drain wire in contact with the shield layer, for example, a conductive layer, the shield layer can be easily connected to the terminal via the drain wire.

[0030] (9) having a drain wire; the shield layer has a structure in which a base material containing an insulating material and a conductive layer are laminated together and are disposed on the core side, The drain wire may be in contact with the substrate containing the insulating material.

[0031] By winding the shielding layer in contact with the drain wire, noise generated when measuring the characteristic impedance is suppressed, making it possible to measure the characteristic impedance easily and stably.

[0032] (10) The device may have an interposition portion disposed within the area surrounded by the outer covering.

[0033] The presence of the intervening wire within the area surrounded by the sheath of the multi-core cable prevents the detection wire from shifting in position when the multi-core cable is bent or over time, and also improves the accuracy of the detection wire in predicting breakage of the covered electric wire.

[0034] (11) The coated electric wire includes two power supply lines, a first power supply line and a second power supply line, and two communication lines, The two communication lines are twisted together to form a twisted pair communication line. The intervening portion includes a first intervening portion and a second intervening portion, In a cross section perpendicular to the longitudinal direction of the core, the detection line is disposed within an area surrounded by the two power supply lines, the twisted pair communication line, and the interposer; the first interposer is arranged to be in contact with the first power supply line and the twisted pair communication line; The second intervening portion may be disposed so as to be in contact with the second power supply line and the twisted pair communication line.

[0035] By arranging the interposer as described above and placing the detection wire within the area surrounded by the two power wires, the twisted pair communication wire, and the interposer, it is possible to prevent the detection wire from shifting in position when the multi-core cable is bent or over time, and also to improve the accuracy of the detection wire in predicting disconnection of the insulated electric wire.

[0036] (12) A wire breakage detection device according to one aspect of the present disclosure includes: a multi-core cable according to any one of (1) to (11); and a measuring device configured to input a test signal having an AC component to the sensing line conductor and measure the characteristic impedance.

[0037] According to one aspect of the present disclosure, the wire break detection device uses the multi-core cable described above, and therefore can accurately predict wire breaks in the insulated wire by measuring electrical characteristics such as the characteristic impedance of the detection line conductor of the detection line.

[0038] [Details of the embodiments of the present disclosure] Specific examples of a multi-core cable and a wire breakage detection device according to one embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. (1) Components of multi-core cables First, the multi-core cable of this embodiment will be described with reference to FIGS. 1A to 6C.

[0039] FIG. 1A shows a cross-sectional view of a multi-core cable 10 of this embodiment, taken along a plane perpendicular to the longitudinal direction. FIG. 1B shows a cross-sectional view of a multi-core cable 100 of this embodiment, taken along a plane perpendicular to the longitudinal direction. FIG. 1C shows a cross-sectional view of a multi-core cable 110 of this embodiment, taken along a plane perpendicular to the longitudinal direction. FIG. 1D shows a cross-sectional view of a multi-core cable 111 used in a simulation of a bending resistance test, taken along a plane perpendicular to the longitudinal direction. FIGS. 2A and 2B show cross-sectional views of a detection line, taken along a plane perpendicular to the longitudinal direction. FIGS. 3A and 3B are explanatory diagrams of the configuration of a conductive tape. FIG. 4 is an explanatory diagram of the twist pitch. FIG. 5 is an explanatory diagram of the bending resistance test, and FIGS. 6A to 6C show the simulation results of the bending resistance test.

[0040] 1A, multi-core cable 10 of this embodiment has a plurality of covered electric wires 11, a detection wire 12, and an outer sheath 13. In Figures 1A to 1D, the Z-axis direction perpendicular to the paper surface corresponds to the longitudinal direction of multi-core cable, covered electric wires 11, detection wire 12, core 17, etc., and the XY plane formed by the X-axis and Y-axis is a plane perpendicular to the longitudinal direction of multi-core cable 10, etc.

[0041] Although the multi-core cable 10 shown in FIG. 1A includes two power lines 14 and two communication lines 15 as the covered electric wires 11, the configuration of the covered electric wires included in the multi-core cable of this embodiment is not limited to this configuration. For example, the multi-core cable may include three or more power lines or communication lines. Furthermore, the multi-core cable of this embodiment may include covered electric wires other than power lines or communication lines. The multi-core cable of this embodiment may include any number of covered electric wires of any configuration depending on the device to which the multi-core cable is connected. As is clear from FIG. 1A , in a cross section perpendicular to the longitudinal direction, the covered electric wires included in the multi-core cable 10 are not arranged symmetrically with respect to the center of the cross section, but rather, covered electric wires with different configurations are arranged along the circumferential direction. Therefore, the bending center of the multi-core cable 10 does not coincide with the center of the cross section.

[0042] The components of the multi-core cable 10 of this embodiment will be described below. (1-1) Insulated wire The insulated electric wire 11 is an electric wire that performs functions required in devices, such as power supply, voltage application, and communication, and is an electric wire for which signs of damage should be detected. As described above, the number and configuration of the insulated electric wire 11 are not particularly limited, but may include multiple types of insulated electric wires with different configurations, for example, as shown in FIG. 1A .

[0043] The covered electric wire 11 can have a wire conductor which is a strand of a plurality of electric wire strands, and a wire coating which covers the outer periphery of the electric conductor.

[0044] The power supply line 14 has a conductor 141 which is a strand of wires, and a wire coating 142 which coats the outer periphery of the conductor 141 .

[0045] The communication line 15 has a wire conductor 151 which is a twisted wire of wire elements, and a wire coating 152 which coats the outer periphery of the wire conductor 151. With regard to the communication line 15, two communication wires 15 are twisted together along the longitudinal direction, which is the Z-axis direction perpendicular to the plane of the paper in Fig. 1A, to form a twisted pair communication line 16. In Fig. 1A, the outer edge of the twisted pair communication line 16 is indicated by a dashed line.

[0046] The diameter and number of the wires constituting the wire conductor of the coated electric wire 11 can be selected depending on the electrical properties required for each coated electric wire 11.

[0047] For example, when the covered electric wire 11 is a power line 14, the diameter of the electric wire strands is preferably 0.05 mm or more and 0.16 mm or less, and more preferably 0.05 mm or more and 0.10 mm or less. The power line 14 can also be formed by twisting electric wire strands together in multiple stages to form the electric wire conductor 141. For example, the electric wire conductor 141 of the power line 14 can have a first stranded wire (child stranded wire) twisted together with electric wire strands, and a second stranded wire (parent stranded wire) twisted together with a plurality of the first stranded wires. The second stranded wire can be the electric wire conductor 141, or the electric wire conductor 141 can also be, for example, a third stranded wire twisted together with a plurality of the second stranded wires.

[0048] The following configuration example is given as an example of the wire conductor 141 of the power line 14. Note that the following is an example, and the present invention is not limited to the following example.

[0049] The wire diameter of the electric wire element is 0.08 mm. Then, 48 electric wire element wires are twisted together to form a first stranded wire (right twist, 10 mm pitch), and seven first stranded wires are twisted together to form a second stranded wire (right twist, 30 mm pitch). Note that the 10 mm pitch and 30 mm pitch refer to the twisting pitch. As shown in FIG. 1A, the second stranded wire, which is formed by twisting seven first stranded wires, can be used as the electric wire conductor 141. In this case, the conductor cross-sectional area S1 of the power line 14 is 1.69 mm 2 The outer diameter of the power line 14 including the wire coating 142 is 2.7 mm.

[0050] When the coated electric wire 11 is a communication wire 15, the diameter of the electric wire strand is preferably 0.05 mm or more and 0.16 mm or less, and more preferably 0.05 mm or more and 0.10 mm or less.

[0051] The electric wire conductor 151 of the communication line 15 can also be formed by twisting electric wire strands together in multiple stages. That is, the electric wire conductor 151 of the communication line 15 can have a first stranded wire (child stranded wire) made by twisting electric wire strands together, and a second stranded wire (parent stranded wire) made by twisting together multiple first stranded wires. The second stranded wire can be the electric wire conductor 151, or a third stranded wire, for example, made by further twisting multiple second stranded wires, can also be the electric wire conductor 151. The electric wire strands of the communication line 15 can be single twisted, or the first stranded wire can be the electric wire conductor 151.

[0052] As described above, the communication lines 15 may be formed as a twisted pair communication line 16 by twisting two communication lines 15 together.

[0053] The following configuration example is given as an example of the electric wire conductor 151 of the communication line 15. Note that the following is an example, and the present invention is not limited to the following example.

[0054] The wire diameter of the electric wire element is 0.08 mm. Then, a first stranded wire (right twist, 5 mm pitch) is formed by twisting together 16 electric wire element wires, and a second stranded wire (right twist, 9 mm pitch) can be formed by twisting together three first stranded wires. Note that the 5 mm pitch and 9 mm pitch in parentheses refer to the twisting pitch. As shown in FIG. 1A, the second stranded wire formed by twisting together three first stranded wires can be used as the electric wire conductor 151. In this case, the conductor cross-sectional area S2 of the communication line 15 is 0.24 mm 2 The outer diameter of the communication wire 15 including the wire coating 152 is 1.5 mm. Furthermore, two communication wires 15 can be twisted together (right twist, 25 mm pitch) to form a twisted pair communication wire 16. In this case, the outer diameter of the twisted pair communication wire 16 is 3.0 mm.

[0055] In another example, the electric wire conductor 151 of the communication line 15 can be configured as a single twist. In other words, the above-mentioned first twisted wire can be used as the electric wire conductor. By configuring the electric wire conductor 151 of the communication line 15 as a single twisted wire, the outer diameter of the communication line 15, etc. can be reduced. For example, a first twisted wire (right twist, 12 mm pitch) can be formed by twisting together 48 electric wire strands. The first twisted wire can be used as the electric wire conductor 151. In this case, the conductor cross-sectional area S2 of the communication line 15 is 0.24 mm 2 The outer diameter of the communication wire 15 including the wire coating 152 is 1.1 mm. Furthermore, two communication wires 15 can be twisted together (right twist, 20 mm pitch) to form a twisted pair communication wire 16. The outer diameter of the twisted pair communication wire 16 is 2.2 mm.

[0056] The wire diameter of a wire such as an electric wire can be measured and calculated according to the following procedure, for example, in accordance with JIS C3002 (1992).

[0057] First, in an arbitrary cross section perpendicular to the longitudinal direction of the wire, the wire diameter is measured using a micrometer along two orthogonal diameters of the wire. The average value of these measurements can be used as the wire diameter of the wire. In this specification, the wire diameter of a wire can be measured and calculated in the same manner.

[0058] In addition, when the multi-core cable 10 has the power line 14 and the communication line 15 as the coated electric wires 11 like the multi-core cable 10 shown in FIG. 1A, the conductor cross-sectional area S1 of the electric wire conductor 141 of the power line 14 is set to 1.5 mm 2 Over 2.5mm 2 In this case, the conductor cross-sectional area S2 of the electric wire conductor 151 of the communication line 15 is set to 0.1 mm 2 More than 0.5mm 2 The following forms can be exemplified.

[0059] The conductor cross-sectional area S2 of the electric wire conductor 151 of the communication line 15 is preferably smaller than the conductor cross-sectional area S1 of the electric wire conductor 141 of the power supply line 14. It is more preferable that the conductor cross-sectional area S1 of the electric wire conductor 141 of the power supply line 14 is 3 to 15 times the conductor cross-sectional area S2 of the electric wire conductor 151 of the communication line 15.

[0060] The conductor cross-sectional area of ​​the electric wire conductor can be calculated by the following procedure. First, the wire diameters of the electric wire element wires constituting the electric wire conductor are measured and calculated by the method described above, and the cross-sectional area of ​​each electric wire element wire is calculated using the wire diameters. Then, the conductor cross-sectional area of ​​the electric wire conductor can be calculated by calculating the product of the cross-sectional area of ​​the electric wire element wire and the number of electric wire element wires contained in the electric wire conductor.

[0061] The material of the wire element of the coated electric wire 11 is not particularly limited, but examples thereof include copper, aluminum, copper alloy, etc. The surface of the wire element may be plated with silver or tin. Therefore, the wire element may be made of, for example, a silver-plated copper alloy or a tin-plated copper alloy.

[0062] The material for the wire coating is not particularly limited, and can be, for example, one or more resins selected from fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polyethylene and polypropylene, etc. The resin for the wire coating may or may not be crosslinked.

[0063] In addition to the above resins, the wire coating may also contain additives such as flame retardants, flame retardant assistants, antioxidants, lubricants, colorants, reflectivity imparting agents, opacifying agents, processing stabilizers, and plasticizers. (1-2) Detection line (1-2-1) Configuration The detection wire 12 is an electric wire that detects the occurrence of a sign of a wire breakage in the coated electric wire 11 by causing damage or breakage (wire breakage) itself.

[0064] Here, the term "fracture" or "disconnection" as used in this specification does not only mean actual disconnection of the detection wire, shield layer, etc., but also refers to partial damage or disconnection of the detection wire, detection wire element, or shield layer, or a thinning of the film thickness. Rather than simply measuring the electrical resistance of a single conductor such as the detection wire or shield layer, an inspection signal containing an AC component can be input to two conductors and the characteristic impedance between the two conductors is measured as a response signal, thereby making it possible to more accurately detect abnormalities before a break.

[0065] As shown in FIG. 2A, the detection wire 12 may have a detection wire conductor 121 which is a twisted wire of a plurality of detection wire strands, and may further have a detection wire covering 122 which covers the outer periphery of the detection wire conductor 121.

[0066] 1A shows an example in which the multi-core cable 10 has one detection wire 12, but is not limited to this configuration and may have multiple detection wires 12. When multiple detection wires 12 are provided, it is sufficient that at least one detection wire 12 is disposed within an area surrounded by multiple covered electric wires 11.

[0067] By disposing the detection wire 12 within an area surrounded by multiple insulated electric wires 11, the detection wire conductor 121 of the detection wire 12 is more likely to break than the wire conductor of the insulated electric wire 11 when a load is applied to the multi-core cable 10 due to repeated bending or vibration. Therefore, when a load is repeatedly applied to the multi-core cable of this embodiment due to bending or vibration, the detection wire conductor 121 of the detection wire 12 breaks in a shorter time than the wire conductor of the insulated electric wire 11. Then, the electrical characteristics of the detection wire conductor 121 are measured, such as by measuring the characteristic impedance, and the condition of the detection wire conductor 121, such as damage or breakage, can be detected from changes in the measured values. Therefore, by measuring the electrical characteristics of the detection wire conductor 121, it is possible to detect signs of a break in the insulated electric wire 11 before the insulated electric wire 11 actually breaks. In other words, it is possible to predict a break in the insulated electric wire 11. (Detection wire element, detection wire conductor) According to the research of the inventors of the present invention, the bending characteristics of an electric wire such as a covered electric wire are affected by the wire diameter of the wires that make up the conductor, and the thicker the wire diameter, the more likely it is to break when repeatedly bent and subjected to a load. For this reason, it is preferable that the wire diameter of the detection wire wires of the detection wire 12 is equal to or greater than the wire diameter of the electric wire wires of the covered electric wire 11.

[0068] By making the wire diameter of the detection wire elements of the detection wire 12 equal to or larger than the wire diameter of the electric wire elements of the insulated electric wire 11, it is possible to configure the detection wire conductor 121 of the detection wire 12 to break before the electric wire conductor of the insulated electric wire 11 when the detection wire 12 is repeatedly bent. As will be described later, by arranging the detection wire 12 within a specific area, when the multi-core cable is repeatedly bent and a load is applied, a greater load is applied to the detection wire 12 than to the insulated electric wire 11. For this reason, the detection wire 12 is more susceptible to breakage than the insulated electric wire 11, and by measuring the electrical characteristics of the detection wire conductor 121 of the detection wire 12 and evaluating the state of the detection wire conductor, it is possible to understand the state of the insulated electric wire 11 and predict breakage of the insulated electric wire 11.

[0069] It is more preferable that the wire diameter of the detection wire element of the detection wire 12 is larger than the wire diameter of the electric wire element of the covered electric wire 11. By making the wire diameter of the detection wire element of the detection wire 12 larger than the wire diameter of the electric wire element of the covered electric wire 11, when the multi-core cable 10 is repeatedly bent, the detection wire 12 is more likely to break than the covered electric wire 11. Therefore, breakage of the covered electric wire 11 can be predicted early and accurately.

[0070] When the multi-core cable has multiple types of covered electric wires, it is preferable that the detection wire elements of the detection wire have a diameter equal to or larger than that of the covered electric wire 11 whose breakage is required to be predicted.

[0071] 1A, when multi-core cable 10 has power line 14 and communication line 15, as described above, it is preferable that the wire diameter of the detection wire elements of detection line 12 is at least equal to or greater than the wire diameter of the electric wire elements of power line 14. That is, when the wire diameter of the detection wire elements of detection line 12 is D1211 and the wire diameter of the electric wire elements of power line 14 is D1411, it is preferable that D1211 ≧ D1411. It is particularly preferable that D1211 > D1411.

[0072] The wire diameter of the detection wire element wires of the detection wire 12 is preferably equal to or greater than the wire diameter of all the insulated wires contained in the multi-core cable 10. In the case of the multi-core cable 10, the wire diameter of the detection wire element wires of the detection wire 12 preferably satisfies the relationships D1211 ≥ D1411 and D1211 ≥ D1511 with the wire diameters of the electric wire element wires of the power line 14 and the electric wire element wires of the communication line 15. It is particularly preferable that D1211 > D1411 and D1211 > D1511. In the above formula, the wire diameter of the detection wire element wires of the detection wire 12 is expressed as D1211, the wire diameter of the electric wire element wires of the power line 14 is expressed as D1411, and the wire diameter of the electric wire element wires of the communication line 15 is expressed as D1511. The same notation is used below.

[0073] The wire diameter of the detection wire element wires in the detection wire 12 can also be made equal to the wire diameter of the electric wire element wires in all of the insulated electric wires contained in the multi-core cable 10. In the case of the multi-core cable 10, the wire diameter of the detection wire element wires in the detection wire 12 can have the relationship D1211 = D1411 = D1511 with the wire diameter of the electric wire element wires in the power line 14 and the wire diameter of the electric wire element wires in the communication line 15. By making the wire diameters of the insulated electric wires 11 and the wires contained in the detection wire 12 of the multi-core cable the same, the number of types of wires required when manufacturing the multi-core cable can be reduced, and productivity can be improved.

[0074] The conductor cross-sectional area S3 of the detection line conductor 121 is, for example, 0.08 mm 2 Over 0.42mm 2 The following embodiments can be exemplified: The conductor cross-sectional area S3 of the detection line conductor 121 of the detection line 12 is preferably smaller than the conductor cross-sectional area S1 of the electric wire conductor 141 of the power supply line 14. Furthermore, the conductor cross-sectional area S3 of the detection line conductor 121 of the detection line 12 is preferably the same as or smaller than the conductor cross-sectional area S2 of the electric wire conductor 151 of the communication line 15.

[0075] Therefore, when the coated electric wire 11 includes a power line 14 and a communication line 15, it is preferable that the conductor cross-sectional area S1 of the electric wire conductor 141 of the power line 14, the conductor cross-sectional area S2 of the electric wire conductor 151 of the communication line 15, and the conductor cross-sectional area S3 of the detection line conductor 121 satisfy the relationship of formula (A).

[0076] S1>S2≧S3 (A) When the conductor cross-sectional area S1 of the wire conductor 141 of the power line 14, the conductor cross-sectional area S2 of the wire conductor 151 of the communication line 15, and the conductor cross-sectional area S3 of the detection line conductor 121 of the detection line 12 satisfy the relationship of the above formula (A), the detection line 12 can be appropriately positioned within the area A surrounded by multiple insulated wires 11.

[0077] When the coated electric wire 11 includes the power line 14, the electric wire conductor 141 of the power line 14 may include a first stranded wire (child stranded wire) formed by twisting together a plurality of electric wire strands, and a second stranded wire (parent stranded wire) formed by twisting together a plurality of the first stranded wires, as described above. In this case, the twist pitch of the detection line conductor 121 is preferably longer than the twist pitch of the first stranded wire of the power line 14.

[0078] By making the twist pitch of the detection line conductor 121 longer than the twist pitch of the first twisted wire of the power line 14, the detection line 12 becomes more susceptible to breakage than the power line 14. Therefore, by measuring the electrical characteristics of the detection line conductor 121 of the detection line 12 and evaluating the state of the detection line conductor 121, it is possible to quickly and accurately predict breakage of the power line 14, which is one of the covered electric wires 11 of the multi-core cable 10 and for which breakage prediction is particularly required.

[0079] The twist pitch refers to the length of a single twist of the cables, such as the wires that make up the twisted wire. This length refers to the length along the central axis of the twisted wire.

[0080] 4 shows a side view of stranded wire 40. Stranded wire 40 has a configuration in which a total of ten cables, cables 400 to 409, are twisted together.

[0081] 4, the distance between the same cables, for example, between cables 400, along the central axis CA on the side of the stranded wire 40 is the twist pitch Pt of the stranded wire 40. The twist pitch can be determined by measuring the twist pitch Pt.

[0082] In this specification, the twist pitch and winding pitch can be measured and calculated in the same manner.

[0083] Furthermore, when the coated electric wire 11 includes the communication wire 15, the electric wire conductor 151 of the communication wire 15 may include a first stranded wire (child stranded wire) formed by twisting together a plurality of electric wire element wires, and a second stranded wire (parent stranded wire) formed by twisting together a plurality of the first stranded wires, as described above. In this case, the twist pitch of the detection line conductor 121 is preferably longer than the twist pitch of the first stranded wire of the communication wire 15.

[0084] The electric conductor 151 of the communication line 15 may be single twisted. In this case, it is preferable that the twist pitch of the detection line conductor 121 is longer than the twist pitch of the electric conductor 151 of the communication line 15.

[0085] By making the twist pitch of the detection line conductor 121 longer than the twist pitch of the first twisted wire of the communication line 15, the detection line 12 becomes more susceptible to breakage than the communication line 15. Note that the same applies when the wire conductor 151 of the communication line 15 is single twisted and the twist pitch of the detection line conductor 121 is longer than the twist pitch of the wire conductor 151 of the communication line 15.

[0086] Therefore, by measuring the electrical characteristics of the detection line conductor 121 of the detection line 12 and evaluating the state of the detection line conductor 121, disconnection of the communication line 15 can be predicted early and accurately.

[0087] The following configuration examples can be given for the wire diameter of the electric wire element of each coated electric wire 11 included in the multi-core cable 10 and the wire diameter of the detection wire element of the detection wire 12. Note that the following are merely examples and are not limited to the following examples.

[0088] In a first example, the wire diameter of the detection wire element of the detection wire 12 can be made equal to the wire diameter of the wire element of one or more covered electric wires selected from the power line 14 and the communication line 15. For example, the wire diameter of the wire element of the power line 14 and the communication line 15 is 0.08 mm as in the above-described configuration example. The wire diameter of the detection wire element is also 0.08 mm. Forty-two detection wire elements are twisted together (right twist, 14 mm pitch) to form the detection wire conductor 121. In this case, the conductor cross-sectional area S3 of the detection wire 12 is 0.21 mm. 2 The outer diameter of the detection wire 12 including the detection wire coating is 1.3 mm.

[0089] In a second example, the wire diameter of the detection wire element of the detection wire 12 is larger than the wire diameter of the wire element of one or more covered electric wires selected from the power line 14 and the communication line 15. For example, the wire diameter of the electric wire element of the power line 14 and the communication line 15 is 0.08 mm as in the above-described configuration example. The wire diameter of the detection wire element is 0.10 mm. 28 detection wire elements are twisted together (right twist, 14 mm pitch) to form the detection wire conductor 121. In this case, the conductor cross-sectional area S3 of the detection wire 12 is 0.22 mm. 2 The outer diameter of the detection wire 12 including the detection wire coating is 1.3 mm. By forming it in this manner, the detection wire element of the second example can be more easily broken than the detection wire element of the first example.

[0090] In any of the above examples, as already mentioned, the detection wire 12 is more likely to break than the power wire 14, so it is preferable that the twist pitch of the detection wire conductor 121 of the detection wire 12 is longer than the twist pitch of the first twisted wire of the electric wire conductor 141 of the power wire 14, for example.

[0091] In addition, to make the detection line 12 more susceptible to breakage than the communication line 15, it is preferable that the twist pitch of the detection line conductor 121 of the detection line 12 is longer than the twist pitch of the first twisted wire of the electric wire conductor 151 of the communication line 15, for example.

[0092] In addition, when the electric wire conductor 151 of the communication line 15 is single twisted, it is preferable that the twist pitch of the detection line conductor 121 of the detection line 12 is longer than the twist pitch of the electric wire conductor 151 of the communication line 15, for example.

[0093] The material of the detection wire is not particularly limited, but examples thereof include copper, aluminum, copper alloy, etc. The surface of the detection wire may be plated with silver or tin. Therefore, for example, a silver-plated copper alloy or a tin-plated copper alloy can also be used as the material of the detection wire. (Detection wire coating)

[0094] The material of the detection wire coating 122 is not particularly limited, and may be one or more resins selected from fluororesins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer (ETFE), polyester resins such as polyethylene terephthalate (PET), and polyolefin resins such as polyethylene and polypropylene. The resin of the detection wire coating 122 may or may not be crosslinked.

[0095] In addition to the above resins, the detection wire coating 122 may also contain additives such as flame retardants, flame retardant assistants, antioxidants, lubricants, colorants, reflecting agents, opacifying agents, processing stabilizers, and plasticizers. (shield conductor, outer coating) 2B, the detection wire may be configured as a coaxial cable. That is, the detection wire 120 may include a detection wire conductor 121, which is a twisted wire of multiple detection wire strands, a detection wire coating 122 that coats the outer periphery of the detection wire conductor 121, and a shield conductor 123 that coats the outer periphery of the detection wire coating 122. The shield conductor 123 may be configured by twisting multiple shield wire strands together, or may be configured from a metal foil such as copper foil. Furthermore, the detection wire 120 may include an outer coating 124 that coats the outer periphery of the shield conductor 123.

[0096] When measuring the characteristic impedance between two conductors, for example, a measuring device is connected between the detection line conductor 121 and the shield conductor 123 of the detection line 12. The positions of the detection line conductor 121 and the shield conductor 123 of the detection line 12 are fixed, and no other covered electric wire is sandwiched between them, which suppresses noise when measuring the characteristic impedance and enables stable measurement. In addition, by providing an outer covering 124 around the outer periphery of the shield conductor 123, the shield conductor 123, the detection line covering 122, and the detection line conductor 121 can be protected. Therefore, the detection line conductor 121 can be prevented from breaking, regardless of whether or not a sign of a broken covered electric wire is being detected. (1-2-2) Placement When considering a multi-core cable in which the included covered electric wires are arranged symmetrically with respect to the center of the cross section perpendicular to the longitudinal direction, the bending center of the multi-core cable coincides with the center of the cross section, and the bending strain at the center is 0. Therefore, the covered electric wires arranged at the center are unlikely to break.

[0097] When the bending center and the cross-sectional center of the multi-core cable 10 do not coincide, as in the case of the multi-core cable 10 of this embodiment, it is particularly difficult to predict the magnitude of the load that the multi-core cable will be subjected to when repeatedly bending the multi-core cable, depending on the arrangement of the detection wire 12 within the multi-core cable 10. Therefore, the inventors of the present invention conducted a study and determined the difference in the magnitude of the load that the multi-core cable 10 will experience depending on the arrangement of the detection wire 12 within the multi-core cable 10 when the multi-core cable 10 is repeatedly bent. As a result, it was found that in the multi-core cable 10, when the detection wire 12 is arranged in an area surrounded by multiple insulated electric wires 11 in a cross-section perpendicular to the longitudinal direction of the multi-core cable 10, the load applied to the detection wire 12 increases when the multi-core cable is repeatedly bent. For this reason, when the detection wire 12 is arranged in an area surrounded by multiple insulated electric wires 11 in a cross-section perpendicular to the longitudinal direction of the multi-core cable 10, the detection wire 12 is more likely to break.

[0098] Furthermore, if the bending center of a multi-core cable does not coincide with the center of its cross section, the magnitude of the load applied to the detection wire 12 varies depending on the arrangement of the detection wire 12 within the multi-core cable, making it particularly difficult to predict the breakage of the insulated electric wire 11 from the evaluation results of the detection wire 12. Specifically, for example, when a multi-core cable is manufactured having a core in which multiple insulated electric wires and a detection wire are twisted together, the arrangement of the detection wire 12 is likely to be misaligned between multi-core cables from different production lots, resulting in differences in the timing of breakage. In contrast, in the multi-core cable 10 of this embodiment, the detection wire 12 is arranged within an area surrounded by multiple insulated electric wires 11 in a cross section perpendicular to the longitudinal direction of the multi-core cable 10. This stabilizes the arrangement of the detection wire 12 within the multi-core cable, even for multi-core cables from different production lots. This also contributes to suppressing positional misalignment between the insulated electric wires 11 and the detection wire 12 over time along the longitudinal direction.

[0099] From the above-mentioned study results, it is preferable that the multi-core cable 10 of this embodiment has the detection wire 12 disposed within an area surrounded by the plurality of coated electric wires 11 in a cross section perpendicular to the longitudinal direction.

[0100] With this arrangement, insulated electric wires with different configurations are arranged along the circumferential direction in a cross section perpendicular to the longitudinal direction of the multi-core cable. Even if the insulated electric wires are not arranged symmetrically with respect to the center of the cross section, a greater load is applied to the detection wire than to the other insulated electric wires when the multi-core cable is repeatedly bent. Furthermore, by arranging the detection wire in an area surrounded by multiple insulated electric wires, the position of the detection wire within the core is stable even when the multi-core cable is repeatedly bent. Therefore, by measuring the electrical characteristics of the detection wire conductor and evaluating the condition of the detection wire conductor, it is possible to predict the breakage of the insulated electric wire at the appropriate time.

[0101] In a cross section perpendicular to the longitudinal direction of the multi-core cable 10, the area A surrounded by the multiple insulated electric wires 11 is an area surrounded by the centers of the multiple insulated electric wires 11 and also surrounded by the outer periphery of the multiple insulated electric wires 11. For example, in the configuration of FIG. 1A, the detection wire 12 is located between the center O of the insulated electric wires 11 and the outer periphery O of the insulated electric wires 11. 141 , O 142 , O 151 , O 152 The insulated electric wires 11 are arranged in an area A surrounded by the outer periphery of the insulated electric wires 11.

[0102] Here, the results of a simulation of the relationship between the arrangement of the detection wires 12 and the magnitude of the load applied to the detection wires are shown in FIGS. 6A to 6C.

[0103] The above simulation is a result of a bending resistance test shown in FIG. 5. The bending resistance test can be performed according to the following procedure. First, as shown in FIG. 5, multi-core cable 50 to be evaluated is placed and sandwiched between first mandrel 511 and second mandrel 512, both of which have a diameter of 20 mm and are arranged horizontally and parallel to each other, and a load of 500 g is applied vertically downward to multi-core cable 50. Then, in this state, the upper end of multi-core cable 50 is bent horizontally by 90° so as to abut against the upper side of first mandrel 511, and then repeatedly bent horizontally by 90° so as to abut against the upper side of second mandrel 512.

[0104] 6A to 6C show the change in the maximum curvature of the detection wire and the insulated wire included in the multi-core cable when the bending angle and direction of the multi-core cable are changed for each step during the bending resistance test. The maximum curvature indicates the degree to which the detection wire and the insulated wire are bent, i.e., corresponds to the load applied to the detection wire and the insulated wire.

[0105] FIG. 6A shows the simulation results when multi-core cable 10 shown in FIG. 1A, in which detection wire 12 is arranged in area A surrounded by a plurality of coated electric wires 11, is subjected to the above-mentioned bending resistance test.

[0106] 6B shows the simulation results of the above-mentioned bending resistance test performed on multi-core cable 111 shown in FIG. 1D, in which detection wire 12A is arranged outside area A surrounded by multiple covered electric wires 11. In multi-core cable 111, detection wire 12A is arranged on the outer periphery of multiple covered electric wires 11, specifically between two power wires 14 and outer sheath 13. Multi-core cable 111 shown in FIG. 1D has the same configuration as multi-core cable 10 shown in FIG. 1A, except for the change in the arrangement of the detection wire.

[0107] Figure 6C shows the results for the detection line from the simulation results of the bending resistance test shown in Figures 6A and 6B. In Figure 6C, the center of the detection line shows the simulation results for the detection line in Figure 6A, and the outside of the detection line shows the simulation results for the detection line in Figure 6B.

[0108] 6A and 6B, power line 1 and power line 2 correspond to power line 14 in multi-core cable 10 in FIG. 1A, and communication line 1 and communication line 2 correspond to communication line 15 in multi-core cable 10 in FIG. 1A. Also, in FIGS. 6A to 6C, dotted line 61 indicates the state where the multi-core cable is bent to 90 degrees, i.e., in contact with first mandrel 511, and dotted line 62 indicates the state where the multi-core cable is bent to -90 degrees, i.e., in contact with second mandrel 512. In FIGS. 6A to 6C, step 0 on the horizontal axis corresponds to a 0-degree bend in the multi-core cable, and step 2.5 corresponds to a 90-degree bend. Also, step 7.5 corresponds to a -90-degree bend, and step 12.5 corresponds to a 90-degree bend. That is, one step on the horizontal axis corresponds to an 18-degree bend.

[0109] By arranging the detection wire 12 in an area A surrounded by multiple insulated wires 11, as in the multi-core cable 10 shown in Fig. 1A, it can be confirmed that at the position where the maximum value of the curvature is at a local maximum, as shown in Fig. 6A, the detection wire 12 is subjected to a greater load than the insulated wire 11. The position where the maximum value of the curvature is at a local maximum refers to the position where the bending angle, indicated by dotted line 61, reaches 90 degrees, and the position where the bending angle, indicated by dotted line 62, reaches -90 degrees, and so on.

[0110] In contrast, by arranging the detection wire 12 outside the area A surrounded by the multiple covered electric wires 11, as in the multi-core cable 111 shown in Fig. 1D, it can be confirmed that the load applied to the detection wire 12 is smaller than that of the covered electric wire 11 at the position where the maximum value of the curvature is the local maximum value, as shown in Fig. 6B. In the multi-core cable 111 shown in Fig. 1D, the detection wire 12 is arranged within the area surrounded by the power wire 14 and the outer sheath 13, as already described.

[0111] 6C is a graph showing the change in maximum curvature of the detection wire from the results shown in Fig. 6A (center of the detection wire) and Fig. 6B (outside of the detection wire). It can be seen that when the detection wire 12 is placed within the area A surrounded by multiple insulated electric wires 11 (center of the detection wire), the load on the detection wire is greater than when the detection wire 12 is placed outside the area A surrounded by multiple insulated electric wires 11 (outside of the detection wire).

[0112] Therefore, by arranging the detection wire 12 in an area A surrounded by a plurality of covered electric wires 11 in a cross section perpendicular to the longitudinal direction of the multi-core cable 10, when the multi-core cable 10 is repeatedly bent and a load is applied, a greater load is applied to the detection wire 12 than to the covered electric wires 11. For this reason, the detection wire 12 is more likely to break earlier than the covered electric wires 11, and by measuring the electrical characteristics of the detection wire conductor 121 of the detection wire 12 and evaluating the condition of the detection wire conductor 121, it is possible to predict breakage of the covered electric wire 11. (1-3) Core The multi-core cable 10 can include a core 17 including the above-described multiple covered electric wires 11 and the detection wire 12. The core 17 can be configured by twisting the above-described multiple covered electric wires 11 and the detection wire 12 together in the longitudinal direction.

[0113] The arrangement of the multiple coated electric wires 11 and the detection wire 12 that make up the core 17 can be selected depending on the configuration of the multiple coated electric wires 11 contained in the core 17. For example, the coated electric wire 11 may include two power supply wires 14, a first power supply wire 14A and a second power supply wire 14B. For example, the first power supply wire 14A may be connected to a ground potential. In this case, it is preferable that the first power supply wire 14A and the detection wire 12, among the power supply wires 14, are arranged in the core 17 so as to be in contact with each other and twisted together.

[0114] As will be described later, characteristic impedance is measured between the detection line 12 and the coated electric wire 11, shield conductor 123, or shield layer 20 of either the power line 14 or the communication line 15. Therefore, by twisting the detection line 12 and the first power line 14A connected to the ground potential in contact with each other, noise generated when measuring characteristic impedance can be suppressed, making it possible to measure characteristic impedance easily and stably.

[0115] As shown in FIG. 1A, the sensing wire 12 may be twisted together with the two power wires 14 so as to be in contact with both of them.

[0116] The twist direction of the core 17 can be selected arbitrarily, but one example is right-handed twist.

[0117] The twist pitch of the core 17 can also be selected arbitrarily, but one example is 90 mm.

[0118] The twist direction and twist pitch are merely examples and are not limited to the above examples. (1-4) Outer covering The multi-core cable 10 may have an outer jacket 13 that covers the outer periphery of the cores 17. The outer jacket 13 may be configured as an extrusion molded body of an insulating material whose main component is a polymer material, for example, and may form the outermost periphery of the multi-core cable 10.

[0119] The configuration of the outer jacket 13 is not particularly limited, and may be, for example, one layer or two or more layers. For example, as shown in Fig. 1A, the outer jacket 13 may be configured with two layers: an inner layer 131 and an outer layer 132. In this case, the outer layer 132, which is disposed on the outermost periphery, is preferably configured from a material that has better mechanical properties, such as wear resistance, than the inner layer 131.

[0120] The material of the outer jacket 13 is not particularly limited. However, when the outer jacket 13 has an inner layer 131 and an outer layer 132 as shown in FIG. 1A, the inner layer 131 may contain, as a resin component, one or more types selected from polyolefins such as polyethylene and ethylene-vinyl acetate copolymer (EVA), polyurethane elastomers, polyester elastomers, and the like.

[0121] Since outer layer 132 is disposed on the outermost surface of multi-core cable 10, it is preferable that it is made of a material that is excellent in resistance to external damage and abrasion, and for example, it may contain polyurethane or the like as a resin component.

[0122] The resin component of the jacket 13 may or may not be cross-linked.

[0123] In addition to the above resin components, the jacket 13 may also contain additives such as flame retardants, flame retardant assistants, antioxidants, lubricants, colorants, reflectivity imparting agents, opacifying agents, processing stabilizers, and plasticizers. (1-5) Shield layer 1B, the multi-core cable 100 of this embodiment may also have a shielding layer 20 that covers the outer periphery of the core 17. In this case, the shielding layer 20 can be disposed between the core 17 and the outer jacket 13.

[0124] The detection wire 12 described above uses damage or breakage of the detection wire conductor 121 as an indicator to predict breakage due to accumulation of metal fatigue in the wire conductor of the insulated electric wire 11.

[0125] However, insulated electric wires included in multi-core cables, damage may occur other than breakage of the electric wire conductor due to metal fatigue. For example, breakage of the electric wire conductor due to metal fatigue progresses over a long period of time due to repeated bending and vibration, while breakage of the electric wire conductor may also occur when the insulated electric wire is suddenly subjected to a large impact due to an external force, etc. Furthermore, contact with an external object or friction may cause external damage to the insulated electric wire, which may lead to breakage of the electric wire coating or even the electric wire conductor.

[0126] The detection method using the breakage of the detection wire 12 described above can sensitively detect signs of wire conductor breakage due to metal fatigue, etc. However, it is difficult to detect signs of wire conductor breakage due to a sudden impact, or the formation of external damage to the insulated wire 11 due to contact or friction with an external object, or signs of such damage.

[0127] Therefore, the multi-core cable of this embodiment has the shield layer 20 functioning as an outer detection layer in addition to the detection wire 12, making it possible to detect signs of damage to the insulated wire 11 caused by sudden impact or external injury, as well as signs of disconnection due to metal fatigue. The shield layer 20, which functions as the outer detection layer, is preferably not electrically connected to ground potential or earth potential in order to input an inspection signal for measuring the characteristic impedance.

[0128] The location of the shielding layer 20 is not particularly limited, and it can be located on the outer periphery of the cores 17 included in the multi-core cable. The shielding layer 20 can be located on the outer periphery of the jacket 13 to detect signs of damage to the covered electric wires 11, but from the viewpoint of continuing accurate damage detection and protecting the shielding layer 20 from the external environment, it is preferable to locate the shielding layer 20 inside the jacket 13. For this reason, it is preferable to locate the shielding layer 20 between the cores 17 and the jacket 13 as described above.

[0129] When the multi-core cable 100 of this embodiment has a pressure winding 18 described below, the shielding layer 20 is preferably disposed inside the pressure winding 18, for example, between the core 17 and the pressure winding 18. By disposing the shielding layer 20 inside the pressure winding 18, the shielding layer 20 can be easily removed when removing the coated electric wire 11 and the detection wire 12 at the longitudinal end of the multi-core cable 10.

[0130] In a cross section perpendicular to the longitudinal direction of the multi-core cable 100, the shield layer 20 is disposed outside the covered electric wires 11 and the detection wire 12. Therefore, when the multi-core cable 100 is suddenly subjected to an external impact or when it comes into contact with or is rubbed against an external object, the shield layer 20 is more likely to receive a larger load and break than the covered electric wires 11 and the detection wire 12. Therefore, by disposing the shield layer 20 and detecting damage or breakage in the shield layer 20, it is possible to sensitively detect the occurrence of signs of damage to the covered electric wires 11 due to an impact or external injury. As a result, the accuracy of predicting breakage of the covered electric wires 11 can be improved.

[0131] The multi-core cable of this embodiment can detect and predict breaks in the insulated electric wires 11, which are mainly caused by metal fatigue, using the detection wire 12 described above. Furthermore, the multi-core cable 100 of this embodiment has the shield layer 20 that functions as an outer detection layer, so that signs of damage to the insulated electric wires 11 caused by impact or external injury can also be detected. Therefore, the multi-core cable 100 of this embodiment has the shield layer 20, so that signs of various damages to the insulated electric wires 11 can be detected.

[0132] The shield layer 20 may be made of any conductive material, and may be made of any suitable material, such as conductive tape, metal wire, or braid, as described below.

[0133] The shield layer 20 may have a conductive member as described above, but it is preferable that the thickness of the conductive member is smaller than the outer diameter of the detection wire conductor 121 of the detection wire 12. The thickness of the conductive member means, for example, the thickness of the conductive layer when the following conductive tape is used, or the thickness of the conductive layer formed by the metal wire when a metal wire is used.

[0134] By making the thickness of the conductive member smaller than the outer diameter of the detection wire conductor 121, the conductive member of the shield layer is more likely to break when a sudden impact that does not break the detection wire 12 is applied, or when the detection wire 12 is subjected to contact or friction with an external object. Therefore, the shield layer 20 can sensitively detect signs of damage to the insulated electric wire 11 that cannot be detected by the detection wire 12 alone.

[0135] The shield layer 20 can be formed by disposing a layer containing a conductive material such as a metal on the outer periphery of the core 17 .

[0136] For example, the shield layer 20 can be formed by spirally winding a conductive tape including a conductive layer around the outer periphery of the core 17 along the longitudinal direction of the core 17 .

[0137] In this case, the conductive tape can have a conductive layer on one of the upper and lower surfaces of the substrate. Therefore, as shown in FIG. 3A, for example, the conductive tape 30 can have a laminated structure of a substrate 31 and a conductive layer 32. The conductive tape 30 preferably has the conductive layer 32 located on the core 17 side so as to be electrically connected to the drain wire 21 (described later). That is, the surface 30A is preferably located on the core 17 side. Therefore, the shielding layer 20 can have a laminated structure of the conductive layer 32 located on the core side and the substrate 31 located on the jacket side. The conductive tape 30 is preferably wound spirally so that the layers are in contact with each other to detect abnormalities without gaps. When the conductive tape 30 is wound around the core 17, the substrate 31 is provided on the outside, so that the conductive layers 32 do not come into contact with each other even when wrapped, and the location of the break can be identified, as described later.

[0138] As will be described later, the shield layer 20 can also have a substrate placed on the core 17 side. In this case, the shield layer 20 can have a laminated structure of a substrate 31 placed on the core side and a conductive layer 32 placed on the jacket side.

[0139] 3B, the conductive tape 300 may have a laminated structure of a first conductive layer 321, a base material 31, and a second conductive layer 322. In this case, either surface may face the core 17.

[0140] 3A and 3B are cross-sectional views of the conductive tape taken along the lamination direction of each layer. When conductive layers are provided on both sides of a substrate, as in the case of conductive tape 300 shown in FIG. 3B, it is preferable to wrap the conductive tapes with gaps between them so that they do not come into contact with each other. This configuration makes it possible to pinpoint the location of the break.

[0141] The materials of the conductive layer 32, the first conductive layer 321, and the second conductive layer 322 are not particularly limited, but preferably contain a metal, and may be, for example, a metal foil. When the conductive layer 32, the first conductive layer 321, and the second conductive layer 322 contain a metal, the metal material is not particularly limited, but may be, for example, copper, a copper alloy, aluminum, an aluminum alloy, or the like.

[0142] The material of the substrate 31 is not particularly limited, but it is preferably made of an insulating material such as an organic polymer material or nonwoven fabric. Examples of organic polymer materials include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene, and vinyl resins such as polyvinyl chloride. The substrate 31 can be a substrate containing an insulating material, or can be made of only an insulating material.

[0143] As described above, when forming shield layer 20 by winding conductive tape, the winding direction of the conductive tape can be selected arbitrarily, and may be the same as or different from the twisting direction of core 17. In particular, it is preferable that the twisting direction of core 17 and the winding direction of the conductive tape are the same.

[0144] The winding pitch of the conductive tape can be selected arbitrarily, but one example is 18 mm.

[0145] The above winding pitch is an example and is not limited to the above example.

[0146] Although the shielding layer 20 has been described above as functioning as an outer sensing layer, it may also be used simply to shield the covered wires in a multi-core cable, in which case the shielding layer 20 is electrically connected to the ground potential.

[0147] A material for fixing the conductive tape, such as an adhesive, may or may not be placed between the core 17 and the conductive tape.

[0148] The shielding layer 20 can also be formed by arranging metal wires in a spiral winding or braided structure around the outer periphery of the core 17. That is, the shielding layer 20 can be formed of metal wires. Materials that can be used for the metal wires include copper, aluminum, copper alloys, etc. Therefore, hard copper wires, etc. can also be used for the metal wires. The surfaces of the metal wires may be plated with silver or tin. Therefore, for example, silver-plated copper alloys, tin-plated copper alloys, etc. can also be used for the metal wires. (1-6) Drain wire 1B, the multi-core cable 100 of this embodiment may also have a drain wire 21. The drain wire 21 is in contact with the above-described shielding layer 20, and more specifically, when the shielding layer 20 is formed of a conductive tape 30, it is preferable that the drain wire 21 be in contact with the conductive layer 32.

[0149] To evaluate whether the shield layer 20 is broken, it is necessary to electrically connect the shield layer 20 to an external measuring device. If the shield layer 20 is formed using the aforementioned conductive tape or the like, it may be difficult to directly connect the shield layer 20 to a terminal. For this reason, by providing a drain wire 21 and bringing the drain wire 21 into contact with the shield layer 20, for example, the aforementioned conductive layer 32, the first conductive layer 321, or the second conductive layer 322, the shield layer 20 can be easily connected to the terminal via the drain wire 21.

[0150] The drain wire 21 may be in contact with the shield layer 20 at least at one point, i.e., may be electrically connected, but it is preferable that the drain wire 21 be in contact with the shield layer 20 at multiple points along the longitudinal direction of the drain wire 21.

[0151] There is no particular limitation on the configuration of the drain wire 21. The drain wire 21 is preferably a stranded wire formed by twisting together a plurality of drain wires, for example.

[0152] The wire diameter and number of the drain wires are not particularly limited and can be selected depending on the electrical properties required of the drain wire 21. For example, the wire diameter of the drain wires is preferably 0.05 mm or more and 0.16 mm or less, and more preferably 0.05 mm or more and 0.10 mm or less. The following are examples of the wire diameter and conductor cross-sectional area of ​​the drain wire 21. Note that the following are merely examples and are not intended to be limiting.

[0153] In one example, the diameter of the drain wire is 0.08 mm. 42 drain wires are twisted together (right twist, 12 mm pitch) to form the drain wire 21. At this time, the conductor cross-sectional area of ​​the drain wire 21 is 0.21 mm. 2 is.

[0154] The material of the drain wire is not particularly limited, but examples thereof include copper, aluminum, copper alloy, etc. The surface of the drain wire may be plated with silver or tin. Therefore, the drain wire may be made of, for example, a silver-plated copper alloy or a tin-plated copper alloy.

[0155] Since the drain wire 21 is electrically connected to the shield layer 20 described above, it is preferable that no coating is provided on the surface of the stranded wire of the drain wire.

[0156] Although the above describes a configuration in which the shield layer 20 and the drain wire 21 are electrically connected, a configuration in which they are not electrically connected can also be used. That is, a configuration in which the substrate 31 is located on the core 17 side and the substrate 31 and the drain wire 21 are in contact with each other. In this case, the shield layer 20 can have a structure in which the substrate 31 containing an insulating material located on the core 17 side and the conductive layer 32 are stacked. Then, a configuration in which the substrate 31 and the drain wire 21 are in contact with each other can be used.

[0157] In the above case, the drain wire 21 is electrically connected to the ground potential, and the shield layer 20 functions as an outer detection layer. By winding the shield layer 20 in contact with the drain wire 21, noise during measurement of the characteristic impedance is suppressed, making it possible to measure the characteristic impedance easily and stably. (1-7) Pressing winding The multi-core cable 10 of this embodiment may also have a pressure winding 18 that covers the outer periphery of the core 17. A suitable example of the pressure winding 18 is a tape made of an insulating material such as paper, nonwoven fabric, or polyester resin that is wound spirally around the outer periphery of the core 17 along the longitudinal direction of the core 17.

[0158] By disposing the pressure winding 18 on the outer periphery of the core 17, the pressure winding 18 serves to keep the positions of the insulated electric wire 11 and the detection wire 12 constituting the core 17 from being separated from each other. This prevents the positions of the insulated electric wire 11 and the detection wire 12 from being displaced within the core 17. That is, it is possible to prevent the positional relationship between the insulated electric wire 11 and the detection wire 12 from changing depending on the position along the longitudinal direction or over time. Therefore, when an external force such as bending or vibration is applied to the multi-core cable, the relationship between the load received by the insulated electric wire 11 and the load received by the detection wire 12 is likely to be maintained constant regardless of the longitudinal position of the multi-core cable or time. Therefore, when a break occurs in the detection wire conductor 121 of the detection wire 12, detecting the break can be used as an indicator that the same level of metal fatigue has accumulated in the wire conductor of the insulated electric wire 11, regardless of the position along the longitudinal direction of the multi-core cable or the time. In other words, signs of disconnection of the insulated electric wire 11 can be accurately detected with sensitivity that is independent of the position and time.

[0159] Furthermore, by placing a pressure winding 18 around the outer periphery of the core 17, direct contact between the core 17 and the outer sheath 13 can be prevented, and therefore the outer sheath 13 can be easily peeled off when removing the coated electric wire 11 or the detection wire 12 at the longitudinal end of the multi-core cable 10.

[0160] As described above, when the tape body is wound around the outer periphery of the core 17 to form the pressure winding 18, the winding direction of the pressure winding 18 can be selected arbitrarily, and for example, it may be the same as or different from the twist direction of the core 17. In particular, it is preferable that the twist direction of the core 17 and the winding direction of the pressure winding 18 are the same direction.

[0161] Furthermore, it is preferable that the winding pitch of the pressure winding 18 is shorter than the winding pitch of the core 17. This is because by making the winding pitch of the pressure winding 18 shorter than the winding pitch of the core 17, it is possible to prevent the tape body forming the pressure winding 18 from falling into the recesses formed between the coated electric wires 11 that constitute the core and the detection wires 12, and to make the surface of the pressure winding 18 smooth.

[0162] The winding pitch of the pressure winding 18 can be selected arbitrarily, but one example is 20 mm.

[0163] The above winding pitch is an example and is not limited to the above example. (1-8) intervention The multi-core cable 10 of this embodiment may also have fillers 19 arranged within the area surrounded by the jacket 13, for example, within the core 17. The fillers 19 may be made of fibers such as staple fiber or nylon fiber. The fillers may also be made of high-tensile strength fibers.

[0164] As described above, the multicore cable 10 of this embodiment can include, as covered electric wires, for example, two power supply lines, that is, the first power supply line 14A and the second power supply line 14B, and two communication lines 15. The two communication lines 15 can be twisted together to form a twisted-pair communication line 16.

[0165] In this case, the interposer 19 can include a first interposer 191 and a second interposer 192 .

[0166] As in the multi-core cable 110 shown in Figure 1C, it is preferable to place the detection line 12 within an area surrounded by two power lines 14, the twisted pair communication line 16, and the interposer 19 in a cross section perpendicular to the longitudinal direction of the core 17.

[0167] 1C, the first interposer 191 can be arranged to contact the first power supply wire 14A and the twisted pair communication wire 16. The second interposer 192 can be arranged to contact the second power supply wire 14B and the twisted pair communication wire 16.

[0168] In the multi-core cable 110 of FIG. 1C, the detection wire 12 and the interposer 19 are arranged apart from each other, but the interposer 19 may be arranged so as to be in contact with the detection wire 12.

[0169] The multi-core cable 10 has the interposition 19 in the area surrounded by the jacket 13, which prevents the detection wire 12 from shifting in position when the multi-core cable 10 is bent or from shifting in position over time. Furthermore, the detection wire 12 can improve the accuracy of predicting breakage of the covered electric wire 11.

[0170] By arranging the interposer 19 as described above and arranging the detection wire 12 in the area surrounded by the two power wires 14, the twisted pair communication wire 16, and the interposer 19, it is possible to prevent the detection wire 12 from shifting in position when the multi-core cable 110 is bent or from shifting in position over time. Furthermore, it is possible to improve the accuracy with which the detection wire 12 can predict breakage of the insulated electric wire 11.

[0171] The multi-core cable of this embodiment described above includes the detection wire 12 in addition to the covered electric wires 11 that perform a predetermined function in equipment, etc. The detection wire 12 is disposed in an area A surrounded by a plurality of covered electric wires in a cross section perpendicular to the longitudinal direction of the multi-core cable, and this area is likely to be subjected to a large force when the multi-core cable is repeatedly bent.

[0172] In addition, the wire diameter of the detection wire element contained in the detection wire 12 is equal to or greater than the wire diameter of the wire element of the coated electric wire 11, and the detection wire conductor 121 of the detection wire 12 can be configured to break before the wire conductor of the coated electric wire 11 when the multi-core cable is repeatedly bent.

[0173] Therefore, when a multi-core cable is repeatedly bent, the detection line conductor 121 of the detection line 12 is more likely to break than the wire conductor of the insulated wire 11, and by measuring the electrical characteristics of the detection line conductor 121 and evaluating the condition of the detection line conductor 121, it is possible to predict breakage of the insulated wire.

[0174] The breakage of the detection line conductor 121 or the shield layer 20 can be detected by electrical measurement such as measurement of characteristic impedance. The evaluation method will be explained in the section on the breakage detection device to be described later.

[0175] The multi-core cable of this embodiment can be used in various applications where it is necessary to predict breakage of the insulated electric wire. The multi-core cable of this embodiment is suitable for use in devices such as automobiles where the multi-core cable is frequently subjected to bending and vibration due to movement, for example, an electric parking brake that electrifies a parking rake. In particular, the multi-core cable is suitable for use in applications where the impact of a break in the insulated electric wire is significant, such as an electric brake system that electrifies the foot brake of an automobile, and where it is therefore very important to detect the breakage of the insulated electric wire before it occurs. In an electric brake system, the power supply line is configured to supply power for driving the motor, and the communication line is configured to transmit electric signals related to motor control and electric signals related to the rotational speed of the wheels. [Disconnection detection device] The wire breakage detection device of this embodiment may include the multi-core cable described above and a measuring device connected to the detection line conductor of the detection line of the multi-core cable. The measuring device may be configured to input an inspection signal including an AC component to the detection line conductor and measure the characteristic impedance.

[0176] Fig. 7 shows a schematic configuration of a wire breakage detection device 70 according to one embodiment of the present disclosure. The wire breakage detection device 70 detects signs of wire breakage, i.e., predicts wire breakage, in the multi-core cable described above. For simplicity, Fig. 7 shows only one wire conductor 711 of the insulated wire and one detection conductor 712 of the detection wire as components of the multi-core cable 71, and illustrates a state in which an abnormality or breakage X1 has occurred in the detection conductor 712.

[0177] The wire break detection device 70 may include a measuring device 72. The measuring device 72 is a device that measures the characteristic impedance of a detection line conductor 712 of a detection line included in a multi-core cable 71, for example, to inspect whether an abnormality or break X1 has occurred in the detection line conductor 712. That is, the measuring device 72 may be configured to measure the characteristic impedance of the detection line conductor 712, for example. The characteristic impedance can be measured by inputting an inspection signal containing an AC component to a conductor, for example, the detection line conductor 712. The characteristic impedance can be measured by inputting an inspection signal containing an AC component to two conductors and measuring the characteristic impedance between the two conductors as a response signal. The characteristic impedance between two conductors may be measured between the detection line conductor 712 of interest and the wire conductor, shield conductor, or conductive layer of the insulated wire 11 of either the power line 14 or the communication line 15. If the multi-core cable has multiple detection lines, the measurement may be performed between two detection line conductors 712. An inspection signal containing an AC component is input to the two conductors, and the characteristic impedance is measured. For this purpose, the measurement device can be configured to input an inspection signal containing an AC component to the detection line conductor and the electric wire conductor, and measure the characteristic impedance between the detection line conductor and the electric wire conductor. Note that the electric wire conductor can be replaced with a shield conductor or a conductive layer of the shield layer, as described above. The response signal is acquired by a reflection method or a transmission method. An LCR meter or the like can be used as the measurement device 72.

[0178] If an abnormality or break X1 exists in the detection line conductor 712, the inspection signal is reflected at the break X1, resulting in a discontinuous change in the response signal. Therefore, if the characteristic impedance measured by the measuring device 72 changes by a reference value or more, it can be determined that an abnormality or break X1 has occurred in the detection line conductor 712 and that a break in the insulated electric wire conductor 711 is occurring. In other words, a break in the insulated electric wire can be predicted. The reference value can be predetermined as a threshold value for the amount of change that should be considered to be due to an abnormality or break in the detection line conductor 712, based on actual measurement results when no abnormality or break X1 has occurred in the detection line conductor 712. Note that changes in characteristic impedance can also occur due to abnormalities such as damage to the detection line conductor 712 that do not result in a break. While this specification treats changes in characteristic impedance due to a break as a representative example, damage to the detection line conductor 712 other than a break can also be similarly used to detect, i.e., predict, signs of a break in the insulated electric wire.

[0179] Detection of an abnormality or break X1 in the detection conductor 712 is not limited to measuring the characteristic impedance between two conductors, but may also be performed by simply measuring the electrical resistance of one conductor (the detection conductor 712). However, measuring the characteristic impedance between two conductors allows for more sensitive detection of an abnormality in the detection conductor 712 before an actual break occurs. In particular, when measuring the characteristic impedance using the reflection method, the characteristic impedance can be measured by connecting the measuring device 72 to only one end of the multi-core cable 71, rather than connecting it to both ends of the multi-core cable 71. Therefore, as long as the measuring device 72 can be connected to just one end of the detection conductor 712, signs of a break in the insulated electric wire can be detected without removing the multi-core cable or removing obstacles. Therefore, as long as the measuring device 72 can be connected to one end of the detection conductor 712 as described above, signs of a break in the insulated electric wire can be detected even when the multi-core cable 71 is located in an inaccessible location, such as inside a vehicle, or when the multi-core cable 71 has a complex route.

[0180] Furthermore, if the characteristic impedance of the detection line conductor 712 is measured by time domain reflectometry (TDR), it is possible to determine not only whether or not there is a break X1 in the detection line conductor 712, but also the location where the break X1 has occurred.

[0181] If the multi-core cable has the aforementioned shielding layer, breakage of the shielding layer can also be measured using a measuring device. Therefore, if the multi-core cable included in the disconnection detection device of this embodiment has a shielding layer, the disconnection detection device of this embodiment can also have a measuring device connected to the shielding layer of the multi-core cable. The measuring device connected to the aforementioned detection line conductor and the measuring device connected to the shielding layer may be configured as a single measuring device, or may be configured as two separate measuring devices. When the measuring device connected to the detection line conductor and the measuring device connected to the shielding layer are configured as a single measuring device, it is preferable to provide a switch or the like on the wiring so that the connection can be switched depending on the measurement target.

[0182] Shield layer rupture detection is not limited to measuring the characteristic impedance between two conductors; it can also be performed by simply measuring the electrical resistance of a single conductor (shield layer). However, measuring the characteristic impedance between two conductors allows for more sensitive detection of shield layer anomalies before an actual rupture occurs. A rupture in the shield layer results in a discontinuous change in the characteristic impedance. The characteristic impedance of the shield layer can be measured between the shield layer and the wire conductor, shield conductor, or detection line conductor 712 of the insulated wire 11 of either the power line 14 or the communication line 15. An inspection signal containing an AC component is input to these two conductors to measure the characteristic impedance. Measuring the characteristic impedance of the shield layer using the TDR method, as with the detection line conductor, can not only determine the presence or absence of an anomaly or rupture, but also pinpoint the location of the anomaly or rupture. Note that changes in the characteristic impedance of the shield layer can also occur due to damage to the shield layer that does not result in a rupture. In this specification, the change in characteristic impedance due to breakage of the shield layer is treated as a representative example, but damage to the shield layer other than breakage can also be similarly used to detect signs of damage to the insulated electric wire through changes in characteristic impedance.

[0183] The disconnection detection device 70 of this embodiment can also have a notification device 73. A signal regarding the measurement result is transmitted to the notification device 73 from the measurement device 72. When the measurement device 72 determines that a change in the characteristic impedance of the detection line conductor 712 or the shield layer exceeds a reference value and that a disconnection has occurred in the detection line conductor 712 or the shield layer, the notification device 73 can notify an external party of a sign of a disconnection in the wire conductor 711 of the insulated wire.

[0184] The specific method of notifying the outside is not particularly limited, but examples include a method of providing a visual notification by providing a display panel or the like as notification device 73 in a device in which a multi-core cable is installed, such as an automobile, or a method of notifying by an alarm sound. Alternatively, the notification device 73 may be provided as an interlock device that restricts some or all of the functions of the device including the multi-core cable 71. For this reason, examples of the notification device 73 include a display device such as a display panel or a warning light, a transmitter such as a buzzer, a control device that performs interlocking, and the like.

[0185] In devices such as automobiles that have a multi-core cable, it is preferable to connect a measuring device 72 or the like to the multi-core cable at all times and continuously measure the characteristic impedance using the measuring device 72 to monitor whether or not there are signs of a disconnection in the insulated electric wire. In this way, if there are signs of a disconnection in the insulated electric wire included in the multi-core cable 71, the signs can be detected early and notified to the user of the device via the notification device 73. The user who receives the notification can take measures such as replacing the multi-core cable early, allowing the device to be used for a long period of time without any problems. In cases where the possibility or frequency of a disconnection in the insulated electric wire is low, the measuring device 72 may not be constantly monitored for signs of a disconnection in the insulated electric wire, but may be connected to the multi-core cable and inspected only at specified times, such as during periodic inspections of the device equipped with the multi-core cable.

[0186] According to the wire break detection device of this embodiment described above, since the multi-core cable described above is used, by measuring the electrical characteristics such as the characteristic impedance of the detection line conductor of the detection line, it is possible to accurately predict wire breaks in the insulated wire. [Explanation of symbols]

[0187] 10, 100, 110, 111, 50, 71 multi-core cable 11. Insulated wire 12, 120, 12A detection wire 121, 712 Detection line conductor S3 Cross-sectional area of ​​the sensing wire conductor 122 Detection wire coating 123 Shielded Conductor 124 Outer covering 13 Outer cover 131 Inner layer 132 Outer layer 14 Power line 14A 1st power line 14B 2nd power line 15 Communication lines 16 Twisted pair communication line 141, 151, 711 Electrical Wire Conductors S1 Cross-sectional area of ​​the conductor of the power line S2 Cross-sectional area of ​​the conductor of the communication line 142, 152 Wire coating O 141 , O 142 , O 151 , O 152 center 17 cores 18 Retainer 19 Intervention 191 1st intervention 192 Second intervention 20 Shielding Layer 21 Drain wire Area A XX axis YY axis ZZ axis (longitudinal direction) 30, 300 Conductive tape 30A side 31 Base material 32 Conductive layer 321 First conductive layer 322 Second conductive layer 40 strands 400~409 Cable CA center axis Pt twist pitch 511 First Mandrel 512 Second Mandrel 61, 62 dotted lines 70 Disconnection detection device 72 Measuring Equipment 73 Notification device X1 break

Claims

1. A plurality of coated electric wires each having a wire conductor which is a strand of a plurality of electric wire strands and a wire coating which coats the outer periphery of the electric conductor; a detection wire having a detection wire conductor which is a twisted wire of a plurality of detection wire strands; an outer sheath that covers an outer periphery of a core that includes the plurality of coated electric wires and the detection wire; The wire diameter of the detection wire is equal to or greater than the wire diameter of the electric wire, the coated electric wire includes two power supply lines, a first power supply line and a second power supply line, and two communication lines; The two communication lines are twisted together to form a twisted pair communication line, the detection line is disposed within an area surrounded by a center of the first power supply line, a center of the second power supply line, and a center of each of the two communication lines; a conductor cross-sectional area S1 of the electric wire conductor of the first power supply line, a conductor cross-sectional area S2 of the electric wire conductor of the communication line, and a conductor cross-sectional area S3 of the detection line conductor, A multi-core cable in which the relationship S1>S2≧S3 is satisfied.

2. 2. The multi-core cable according to claim 1, wherein the diameter of the detection wire is larger than the diameter of the electric wire.

3. The detection wire includes a detection wire covering that covers an outer periphery of the detection wire conductor.

3. The multi-core cable according to claim 2, which is a coaxial cable having a shield conductor covering the outer periphery of the sensing wire covering.

4. The power supply line includes a second stranded wire formed by twisting together a plurality of first stranded wires, The first stranded wire is formed by twisting together a plurality of the electric wire strands, The multi-core cable according to claim 1 , wherein a twist pitch of the sensing line conductor is longer than a twist pitch of the first stranded wires.

5. The core is formed by twisting together a plurality of the coated electric wires and the detection wire, 5. The multi-core cable according to claim 1, wherein the first power supply line connected to a ground potential and the detection line are arranged in contact with each other in the core and twisted together.

6. a shield layer covering the outer periphery of the core; The multi-core cable according to claim 1 , wherein the shielding layer is disposed between the core and the jacket.

7. A drain wire is provided. the shield layer has a structure in which a conductive layer disposed on the core side and a base material containing an insulating material are laminated, The multi-conductor cable according to claim 6 , wherein the drain wire is in contact with the conductive layer.

8. A drain wire is provided. the shield layer has a structure in which a base material containing an insulating material and a conductive layer are laminated together and are disposed on the core side, The multi-core cable according to claim 6 , wherein the drain wire is in contact with the substrate containing the insulating material.

9. 9. The multi-core cable according to claim 1, further comprising a filler disposed within the area surrounded by the jacket.

10. The intermediary includes a first intermediary and a second intermediary, In a cross section perpendicular to the longitudinal direction of the core, the detection line is disposed within an area surrounded by the two power supply lines, the twisted pair communication line, and the interposer; the first interposer is arranged to be in contact with the first power supply line and the twisted pair communication line; The multi-core cable according to claim 9 , wherein the second interposer is disposed so as to be in contact with the second power supply wire and the twisted pair communication wire.

11. A multi-core cable according to any one of claims 1 to 10; and a measuring device configured to input an inspection signal including an AC component to the detection line conductor and measure the characteristic impedance.

Images