Sensor wire, sensor device, and wire harness

Abstract

Provided are a sensor wire serving as a member capable of sensitively detecting mechanical deformation and environmental change, a sensor device provided with the sensor wire, and a wire harness.　A sensor wire 1 that has a first insulated wire 12a and a second insulated wire 12b each provided with a conductor and an insulation coating for covering the outer periphery of the conductor. The first insulated wire 12a and the second insulated wire 12b are assembled by bending in a state in which the longitudinal axes are aligned with each other to configure a wire aggregate 11. The sensor wire 1 has a region where the first insulated wire 12a and the second insulated wire 12b are alternately arranged in a plurality of units on a straight line B crossing the wire aggregate 11 by using a set of the first insulated wire 12a and the second insulated wire 12b as one unit.

Description

Sensor wire, sensor device, and wire harness

[0001] The present disclosure relates to a sensor wire, a sensor device, and a wire harness.

[0002] Electric wires are installed or laid in various electrical and electronic devices, transportation equipment, buildings, public facilities, etc., and damage to the wires may occur over long-term use. To prevent damage from seriously affecting the performance of the wire, it is desirable to detect the occurrence of damage early and sensitively. One method for detecting damage to an electric wire is to attach a component that functions as a damage-detecting sensor to the electric wire and inspect the electric wire for damage using the component. For example, Patent Document 1 discloses an electric wire in which a conductive tape or laminated tape is disposed around the outer periphery of a core wire having a conductor and an insulating coating. The conductive tape is wound spirally around the surface of the insulating coating along the axial direction of the core wire, and gaps not occupied by the conductive tape are provided between the spiral turns of the conductive tape. The laminated tape has a substrate formed as a tape-shaped insulator or semiconductor and conductive coating layers formed on both sides of the substrate. When a defect is formed in the electric wire, the damage to the conductive tape changes the characteristic impedance between the conductive tape and the conductor that constitutes the core wire, and the damage to the laminated tape changes the characteristic impedance between the two coating layers included in the laminated tape, so that the formation of a defect in the electric wire can be sensitively detected.

[0003] JP 2021-162449 A

[0004] By attaching a material whose electrical properties change when damaged, such as the conductive tape or laminated tape used in the above-mentioned Patent Document 1, to an electric wire, damage caused by external force or the like can be detected with high sensitivity. However, electric wires may be frequently subjected to deformation due to mechanical loads or changes in the surrounding environment, even if they do not result in irreversible damage. These mechanical deformations and environmental changes may change the operation and characteristics of the electric wire, which may cause the electric wire itself or the equipment to which the electric wire is connected to to fail to perform its intended function. Furthermore, if the effects of mechanical deformations and environmental changes accumulate in an electric wire, they may eventually lead to damage or deterioration of the electric wire. To avoid such situations, it is desirable to be able to sensitively detect mechanical deformations and environmental changes in an electric wire that do not immediately result in damage or deterioration.

[0005] In view of the above, an object of the present invention is to provide a sensor wire as a member capable of sensitively detecting mechanical deformation and environmental changes, and a sensor device and a wire harness including such a sensor wire.

[0006] The sensor wire according to the present disclosure includes a first insulated wire and a second insulated wire, each of which has a conductor and an insulating coating that covers the outer periphery of the conductor. The first insulated wire and the second insulated wire are bent and assembled together with their longitudinal axes aligned to form a wire assembly. A pair of the first insulated wire and the second insulated wire constitutes one unit, and a region is formed on a straight line that crosses the wire assembly, in which multiple units of the first insulated wire and the second insulated wire are lined up alternately.

[0007] The sensor device according to the present disclosure includes the sensor wire and a monitoring means that inputs a differential signal to the first insulated wire and the second insulated wire that constitute the sensor wire to obtain a response signal and monitors changes in the response signal.

[0008] The wire harness according to the present disclosure includes a target electric wire consisting of at least one electric wire and the sensor device, and the sensor electric wire constituting the sensor device is arranged in at least a partial area along the longitudinal direction of the target electric wire.

[0009] The sensor wire, sensor device, and wire harness according to the present disclosure are sensor wires that are components capable of sensitively detecting mechanical deformation and environmental changes, and are sensor devices and wire harnesses that include such sensor wires.

[0010] FIG. 1A is a perspective view showing a spiral-wound sensor wire as an example of a sensor wire according to an embodiment of the present disclosure. FIG. 1B is a perspective view showing a coil-type sensor wire as another example of a sensor wire according to an embodiment of the present disclosure. FIG. 2A is a schematic diagram showing a configuration of a sensor device according to an embodiment of the present disclosure. FIG. 2B is a perspective view showing a configuration of a wire harness according to an embodiment of the present disclosure. FIGS. 3A and 3B are schematic cross-sectional views showing a state change when a force is applied to an electric wire assembly in a direction increasing the distance between the electric wires, where FIG. 3A shows the state before the force is applied and FIG. 3B shows the state after the force is applied. FIGS. 4A and 4B are schematic cross-sectional views showing a state change when a liquid is brought into contact with the electric wire assembly, where FIG. 4A shows the state before contact with the liquid and FIG. 4B shows the state after contact with the liquid. FIGS. 5A and 5B are schematic cross-sectional views showing a state change associated with melting of a substance in contact with the electric wire assembly, where FIG. 5A shows the state before melting and FIG. 5B shows the state after melting. 6A and 6B are schematic cross-sectional views showing state changes accompanying chemical changes in a substance in contact with an electric wire assembly, with FIG. 6A showing a low-dielectric-constant state before the chemical change and FIG. 6B showing a high-dielectric-constant state after the chemical change. FIG. 7 shows measurement results showing changes in the reflection coefficient accompanying stretching of the coiled sensor wire. FIG. 8 shows measurement results showing changes in the reflection coefficient accompanying bending of the coiled sensor wire. FIG. 9 shows measurement results showing changes in the reflection coefficient of the coiled sensor wire accompanying stretching due to heating. FIG. 10 shows measurement results showing changes in the reflection coefficient accompanying contact of the spiral-wound sensor wire with an electrolyte solution. FIG. 11 shows measurement results showing changes in the reflection coefficient accompanying contact of a finger with the spiral-wound sensor wire. FIG. 12 shows measurement results showing changes in the reflection coefficient accompanying contact of two types of rubber with the spiral-wound sensor wire.

[0011] [Description of the embodiment of the present disclosure] First, the embodiment of the present disclosure will be described.

[0012] [1] The sensor wire of the present disclosure includes a first insulated wire and a second insulated wire, each of which has a conductor and an insulating coating that covers the outer periphery of the conductor. The first insulated wire and the second insulated wire are bent and assembled together with their longitudinal axes aligned to form a wire assembly. A pair of the first insulated wire and the second insulated wire constitutes one unit, and a region is formed on a straight line that crosses the wire assembly, in which multiple units of the first insulated wire and the second insulated wire are lined up alternately.

[0013] The sensor wire sensitively detects mechanical deformation and environmental changes applied to the sensor wire and outputs the detected electrical signals. Specifically, by inputting a differential signal to two insulated wires constituting a wire assembly and acquiring a response signal such as characteristic impedance, the response signal can change to reflect the mechanical deformation and environmental changes applied to the sensor wire. This is because, in a structure in which two insulated wires are alternately arranged on a straight line crossing the wire assembly, an electric field is generated between adjacent insulated wires, and the state of this electric field changes with changes in the distance between the insulated wires due to deformation of the wire assembly and changes in the dielectric constant of materials surrounding the wire assembly. This change in the state of the electric field also changes the response signal such as characteristic impedance. Therefore, by placing the sensor wire in the path of a target wire whose effects of mechanical deformation and environmental changes are to be monitored, inputting an inspection signal to the sensor wire, and detecting the response signal, mechanical deformation and environmental changes applied to the target wire and the sensor wire assembly can be sensitively detected as changes in the response signal. In addition, in equipment used with the target wire, the equipment can be constructed so that instructions and information can be input from outside by utilizing mechanical deformation of the sensor wire or changes in the environment, and the input instructions and information can be read by changes in the response signal in the sensor wire.

[0014] Here, in a sensor wire, two insulated wires are bent and assembled with their longitudinal axes aligned. This allows for more sensitive detection of mechanical deformation and environmental changes as changes in the response signal than when the two insulated wires run straight parallel to each other. This is because the long insulated wires are housed in a predetermined length region, allowing the entire area along their actual length to be used as a sensor. Furthermore, the sensor wire can be deformed significantly by utilizing changes in the shape of the wire assembly. Furthermore, because the insulated wires are bent into a specific shape (such as a spiral or helical shape), a magnetic field may be generated when viewed individually as a unit when an AC signal is input. However, because the two insulated wires are assembled with their longitudinal axes aligned and the signals input to the two insulated wires are differential signals with opposite polarities, the magnetic fields generated by the two insulated wires cancel each other out. This reduces the likelihood of the magnetic field affecting the detection results of the sensor wire or the operation of the target wire.

[0015] [2] In the above aspect [1], the first insulated wire and the second insulated wire may be wound around a common central axis to form the wire assembly. In this case, a wire assembly in which two insulated wires are densely packed can be easily obtained. By aligning the longitudinal axes of the two insulated wires with each other and packing them densely together, and repeating many sets of structures in which two insulated wires are arranged alternately, a wire assembly that produces a large change in response signal when mechanical deformation or an environmental change is applied can be obtained.

[0016] [3] In the above aspect [1] or [2], the first insulated wire and the second insulated wire may be assembled in a planar shape in the wire assembly. In this case, if mechanical deformation or an environmental change occurs anywhere in the plane formed by the sensor wires, the event can be detected as a change in the response signal. This makes it easier to monitor mechanical deformation and environmental changes over a wide area.

[0017] [4] In any one of the above aspects [1] to [3], the first insulated wire and the second insulated wire may be spirally wound. In this case, the wire assembly can be configured by accumulating a pair of two insulated wires in a planar manner at high density. This results in a sensor wire that can detect mechanical deformation and environmental changes over a wide range with high sensitivity.

[0018] [5] In any one of the above aspects [1] to [4], the first insulated wire and the second insulated wire may each be configured as an enameled wire. This allows the insulating coating of the insulated wire to be thinned and the distance between adjacent conductors in the wire assembly to be reduced, so that deformation of the wire assembly and changes in the dielectric constant of the material surrounding the wire assembly are more likely to be reflected as changes in the electric field. As a result, mechanical deformation and environmental changes in the sensor wire are more likely to cause large changes in the response signal.

[0019] [6] In any one of the above aspects [1] to [5], the sensor wire may further include a support material that contacts the wire assembly and supports the wire assembly. Using the support material makes it easier to use the sensor wire as a freestanding member. Furthermore, using the support material makes the wire assembly less likely to deform under small mechanical loads, such as minute vibrations. This makes it possible to selectively detect mechanical loads that should be detected as abnormal or intentionally applied, as a change in the response signal, while ignoring mechanical loads that are considered normal.

[0020] [7] In the aspect [6] above, the support material may have flexibility that allows it to deform in accordance with the deformation of the wire assembly. In this case, when an external force that causes deformation is applied to the sensor wire, the sensor wire, including the support material, deforms, causing a change in the response signal.

[0021] [8] In any one of the above aspects [1] to [7], it is preferable that an intermediary material containing a substance whose permittivity changes in response to an environmental change in the area surrounding the wire assembly is disposed in contact with the wire assembly. In this case, when there is a change in the environment in which the sensor wire is placed, a change occurs in the response signal of the sensor wire due to the change in the permittivity in the area surrounding the wire assembly and the accompanying change in the state of the electric field. The change in the response signal can then be detected as a change in the environment.

[0022] [9] In the above aspect [8], the change in the dielectric constant may be caused by at least one of a phase transformation and a chemical change of the medium. By using a substance that undergoes a phase transformation or a chemical change as the medium, changes in the environment in which the sensor wire is placed can be sensitively detected as changes in the response signal of the sensor wire.

[0023]

[10] A sensor device according to the present disclosure includes a sensor wire according to any one of [1] to [7] above, and a monitoring means for inputting a differential signal to the first insulated wire and the second insulated wire constituting the sensor wire, acquiring a response signal, and monitoring a change in the response signal.

[0024] This sensor device receives a response signal by inputting a differential signal to a sensor wire having the above-described wire assembly using a monitoring means. When the sensor wire is subjected to mechanical deformation or an environmental change, the response signal changes sensitively via a change in the state of the electric field around the wire assembly. Therefore, the sensor device can be used as a detection device for detecting the application of a mechanical load or a change in the environment. For example, by disposing the sensor wire constituting the sensor device in at least a partial area along a target wire whose effects of mechanical deformation or environmental change are to be monitored and monitoring the response signal, it is possible to sensitively detect mechanical deformation or an environmental change when the target wire and the assembly of sensor wires are subjected to such an event. Because the wire assembly is made up of two insulated wires and a differential signal is input to the wire assembly, the wire assembly is less likely to generate a magnetic field during measurement by the monitoring means.

[0025]

[11] In the aspect

[10] above, the monitoring means may determine that at least one of mechanical deformation, temperature change, and change in a material in contact with the sensor wire has occurred when a change in the response signal exceeding a reference value occurs. Mechanical deformation, temperature change, and change in a material in contact with the sensor wire are all events that cause a change in the response signal obtained from the sensor wire. By setting a predetermined reference value for the change in the response signal and determining that at least one of these events has occurred when a change in the response signal exceeding the reference value occurs, it is possible to detect the occurrence of such an event at a level that exceeds a predetermined level, such as a level that has a non-negligible impact on the operation of a target wire placed near the sensor wire or a level that could lead to irreversible changes in the target wire, and to take measures to address the occurrence.

[0026]

[12] In the above aspect

[10] or

[11] , the monitoring means may monitor, as the response signal, a change in the characteristic impedance or reflection coefficient between the first insulated wire and the second insulated wire that constitute the sensor wire. The characteristic impedance and reflection coefficient are parameters whose values ​​change and sensitively reflect changes in the state of the electric field due to mechanical deformation of the sensor wire or environmental changes. Therefore, by measuring the characteristic impedance or reflection coefficient of the sensor wire, mechanical deformation and environmental changes in the sensor wire can be sensitively detected.

[0027]

[13] In the aspect

[12] above, the monitoring means may measure the characteristic impedance or reflection coefficient using a time-domain reflectometry or a frequency-domain reflectometry. By employing the time-domain reflectometry or the frequency-domain reflectometry, the area where the change occurs in the characteristic impedance or reflection coefficient in the response signal can be associated with a position on the sensor wire through appropriate calculations based on information about the area where the change occurs. Furthermore, the area can be associated with a position where mechanical deformation or an environmental change occurs on the sensor wire. This makes it possible to easily and accurately identify the position where mechanical deformation or an environmental change occurs on the sensor wire.

[0028]

[14] In any one of the above aspects

[10] to

[13] , the wire assembly may be impedance-matched with the monitoring means by adjusting the number of pairs of the first insulated wires and the second insulated wires arranged in the straight line. Matching the impedance between the wire assembly and the monitoring means reduces the effects of loss and noise, allowing a response signal to be acquired and mechanical deformation and environmental changes in the sensor wire to be detected with high accuracy. In the wire assembly, adjusting the number of pairs of alternating insulated wires allows the characteristic impedance to be easily changed, thereby enabling impedance matching with the monitoring means.

[0029]

[15] The wire harness of the present disclosure includes a target electric wire consisting of at least one electric wire and any one of the sensor devices

[10] to

[14] above, and the sensor electric wire constituting the sensor device is arranged in at least a portion of the longitudinal direction of the target electric wire.

[0030] In this wire harness, a sensor wire having an electric wire assembly is disposed in at least a portion of the longitudinal direction of the target electric wire. Therefore, the sensor device can sensitively detect mechanical deformation or environmental changes occurring in the target electric wire and the assembly of sensor electric wires. This makes it possible to detect mechanical deformation or environmental changes that may affect the operation or characteristics of the target electric wire, consider their effects when using the target electric wire, and take measures such as replacing the target electric wire before the mechanical deformation or environmental changes cause irreversible damage or deterioration of the target electric wire. Furthermore, if instructions or information can be input through the application of mechanical deformation or environmental changes to the sensor wire and the instructions or information can be read as changes in the response signal, the sensor device can be used as an input means in equipment used with the wire harness.

[0031] [Details of the embodiment of the present disclosure] A sensor wire, a sensor device, and a wire harness according to the embodiment of the present disclosure will be described in detail below with reference to the drawings. A sensor device is configured including the sensor wire according to the embodiment of the present disclosure. A wire harness is configured including the sensor device. The sensor wire and the sensor device monitor mechanical deformation and environmental changes, and in a wire harness, the sensor device monitors the target electric wire to be monitored. In this specification, terms such as spiral, helical, linear, etc., that indicate the shape or arrangement of components of an electric wire include not only a strict geometric concept but also an allowable range of error for an electric wire.

[0032] <Outline of the Configuration of the Sensor Wire, Sensor Device, and Wire Harness> First, an outline of the configuration of the sensor wire, sensor device, and wire harness according to an embodiment of the present disclosure will be described. Figures 1A and 1B show perspective views of an example of the structure of a sensor wire according to an embodiment of the present disclosure. Figures 1A and 1B each show a different form. Figure 2A also shows a schematic diagram of an example of the configuration of a sensor device according to an embodiment of the present disclosure, and Figure 2B shows a perspective view of an example of the configuration of a wire harness according to an embodiment of the present disclosure.

[0033] 1A and 1B, a sensor wire 1 according to one embodiment of the present disclosure includes a wire assembly 11. The wire assembly 11 includes a pair (two) of insulated wires, a first insulated wire 12a and a second insulated wire 12b. Each of the first insulated wire 12a and the second insulated wire 12b includes a conductor 121 and an insulating coating 122 that covers the outer periphery of the conductor 121 (see FIG. 3A). The type of the insulated wires 12a and 12b is not particularly specified, but it is preferable that each be configured as an enameled wire.

[0034] In the wire assembly 11, a pair of insulated electric wires 12a, 12b are bent and assembled with their longitudinal axes aligned to form the wire assembly 11. The wire assembly 11 has a region where a plurality of units of the first insulated electric wires 12a and the second insulated electric wires 12b are alternately arranged on a reference line B that crosses the wire assembly 11, with each unit being a pair of a first insulated electric wire 12a and a second insulated electric wire 12b. That is, as shown in Fig. 3A , the wire assembly 11 has a region where a plurality of the first insulated electric wires 12a and a plurality of the second insulated electric wires 12b are alternately arranged along the reference line B, in the order of the first insulated electric wire 12a → the second insulated electric wire 12b → the first insulated electric wire 12a → the second insulated electric wire 12b → ... Preferably, such an alternating arrangement is formed over the entire area of ​​the wire assembly 11 except for the ends and peripheral edges. In the wire assembly 11, the pair of insulated wires 12a, 12b are not fixed to each other by, for example, fusing the insulating coating 122, and are movable relative to each other.

[0035] The wire assembly 11 may have any shape as long as the pair of insulated wires 12a, 12b, whose longitudinal axes are aligned, are bent to form the alternating arrangement. However, a preferred example is a configuration in which the wire assembly 11 is configured as a two-wire spiral wire 11A in which the pair of insulated wires 12a, 12b are gathered in a spiral shape, as shown in Fig. 1A, and the sensor wire 1 is configured as a spiral-type sensor wire 1A. In Fig. 2A, the pair of insulated wires 12a, 12b constituting the two-wire spiral wire 11A are schematically indicated by thick and thin lines. Another example is a configuration in which the wire assembly 11 is configured as a two-wire coil wire 11B in which the pair of insulated wires 12a, 12b are gathered by being wound in a spiral shape, as shown in Fig. 1B, and the sensor wire 1 is configured as a coil-type sensor wire 1B. In the two-wire spiral electric wire 11A, if the reference line B is taken as a radial line connecting the center of the spiral shape and a point on the outer periphery, then the alternating arrangement is formed along the reference line B. In the two-wire coil electric wire 11B, if the reference line B is taken as a line parallel to the central axis of the spiral shape, then the alternating arrangement is formed along the reference line B. In addition to the spiral shape and the helical shape, examples of shapes that the pair of insulated electric wires 12a, 12b may take in the electric wire assembly 11 include a shape in which the pair of insulated electric wires 12a, 12b are bent in a zigzag pattern, and a structure in which the pair of insulated electric wires 12a, 12b are repeatedly meandered and laid out in a plane.

[0036] If the wire assembly 11 is a planar assembly of a pair of insulated wires 12a, 12b, as in the above-described two-wire spiral wire 11A, mechanical deformation and environmental changes can be detected at any location on the surface of the wire assembly 11, and these changes can be monitored over a wide area. Furthermore, it is preferable that the wire assembly 11 is formed by winding the pair of insulated wires 12a, 12b around a common central axis, since this simplifies the fabrication of the wire assembly 11 and allows the insulated wires 12a, 12b to be densely packed together, thereby enhancing the detection sensitivity for mechanical deformation and environmental changes. When the wire assembly 11 is the two-wire spiral wire 11A, the pair of insulated wires 12a, 12b are wound concentrically from the inside to the outside in a planar manner around the central axis. When the wire assembly 11 is a two-wire coil wire 11B, a pair of insulated wires 12a, 12b are wound spirally around a central axis from one side to the other along the central axis.

[0037] The sensor wire 1 further includes, optionally, a support member 13. The support member 13 is a member that is disposed in contact with the wire assembly 11 and supports the wire assembly 11. In the spiral-type sensor wire 1A of FIG. 1A, a plate-shaped support member 13 is provided, which supports the two-wire spiral wire 11A by making surface contact with the surface of the two-wire spiral wire 11A. A shaft portion 131 that protrudes from the plate surface of the support member 13 is integrally provided at the center of the support member 13 and functions as a central shaft for winding the pair of insulated wires 12a, 12b therearound. Furthermore, a circular recess that matches the size of the two-wire spiral wire 11A can be formed in the plate surface of the support member 13, and the two-wire spiral wire 11A can be accommodated in the recess to stably hold the two-wire spiral wire 11A. 1B, a rod-shaped support member 13 is provided and is inserted into the spiral-shaped hollow portion 111 of the two-wire coil electric wire 11B to support the two-wire coil electric wire 11B. The support member 13 functions as a core member of the two-wire coil electric wire 11B, that is, as a central axis around which the pair of insulated electric wires 12a and 12b are wound.

[0038] The presence of the support material 13 in the sensor wire 1 stably maintains the assembled shape of the insulated wires 12a, 12b in the wire assembly 11, such as the spiral shape of the two-wire spiral wire 11A or the helical shape of the two-wire coil wire 11B, making it easier to handle the sensor wire 1 as a free-standing member. Furthermore, by supporting the wire assembly 11 with the support material 13, the wire assembly 11 is less likely to deform under small mechanical loads such as minute vibrations. The support material 13 is preferably made of a non-magnetic insulator, but the specific configuration and material of the support material 13 are preferably selected depending on the change to be detected by the sensor wire 1, as will be described in detail later.

[0039] Furthermore, although not included in the illustrated embodiment, the sensor wire 1 may include an intermediate material in contact with the wire assembly 11. The intermediate material refers to a substance that causes a change in the dielectric constant in the area surrounding the wire assembly 11 (the area outside the wire assembly 11 and the space inside the wire assembly 11, such as the hollow portion 111 of the two-wire coil) due to environmental changes. Environmental changes refer to changes in the temperature of the space in which the sensor wire 1 is placed and changes in the substances present in the surrounding area. The shape of the intermediate material and the manner in which it is attached to the sensor wire 1 are not particularly limited. For example, in the case of the spiral-wound sensor wire 1A, a sheet-like intermediate material may be placed in contact with at least one of the upper and lower surfaces of the two-wire spiral wire 11A. In addition, in the case of the coil-type sensor wire 1B, a sheet-like intermediate material may be filled in the hollow portion 111 of the two-wire coil wire 11B, or a tube-like intermediate material may be fitted around the outer periphery of the two-wire coil wire 11B. In either case, the support material 13 may also serve as a medium. Specific types of medium will be described later.

[0040] (2) Sensor Device As shown schematically in Fig. 2A , a sensor device 2 according to an embodiment of the present disclosure includes the sensor wire 1 and a monitoring unit 21. Fig. 2A illustrates a configuration in which a spiral-wound sensor wire 1A is used as the sensor wire 1. The monitoring unit 21 is a device that inputs an AC inspection signal to the sensor wire 1, acquires a response signal, and monitors changes in the response signal. The inspection signal is a differential signal. That is, AC signals of opposite polarities are input to the insulated wires 12a, 12b, respectively. By inputting a differential signal to the wire assembly 11, the insulated wires 12a, 12b, through which AC currents of opposite polarities flow, are alternately arranged along the reference straight line B of the wire assembly 11 (see Fig. 3A ).

[0041] The monitoring means 21 inputs an inspection signal consisting of a differential signal to the wire assembly 11 of the sensor wire 1, and the characteristic impedance between the pair of insulated wires 12 a, 12 b can be suitably used as the electrical parameter measured as the response signal. As will be described in detail later, when the sensor wire 1 undergoes mechanical deformation or environmental changes (such as temperature changes or changes in contacting materials), the state of the electric field in the space surrounding the sensor wire 1 changes, resulting in a corresponding change in the value of the characteristic impedance. Therefore, the sensor device 2 measures and monitors the value of the characteristic impedance as a response signal while inputting the inspection signal, and can detect mechanical deformation or environmental changes in the sensor wire 1 based on changes in the value. In addition to the characteristic impedance, other parameters that can be measured as the response signal include reflection coefficient, conductance, capacitance, and the like. These parameters are correlated with the characteristic impedance and reflect changes in the state of the electric field in the space surrounding the sensor wire 1. Measuring the characteristic impedance or reflection coefficient as the response signal is preferred in terms of high detection sensitivity to mechanical deformation and environmental changes.

[0042] The monitoring means 21 may be configured with a measuring device capable of generating a differential signal as an inspection signal and detecting a response signal. For example, an impedance meter or the like may be used to measure characteristic impedance as the response signal. When acquiring the response signal using the monitoring means 21, either a transmission method or a reflection method may be used. From the viewpoint of ease of measurement, the reflection method is preferable because the response signal can be acquired by connecting a measuring device to only one end. When using the reflection method, it is preferable to connect the measuring device to one end of the wire assembly 11 and to connect a termination resistor 25 to the other end. In the sensor device 2, impedance matching is preferably performed between the monitoring means 21 and the wire assembly 11 to reduce loss and noise in the response signal. Impedance matching can be easily achieved by adjusting the number of pairs of two insulated wires 12a, 12b arranged along the reference line B in the wire assembly 11. The number of pairs of insulated electric wires 12a, 12b can be adjusted by the number of times the two insulated electric wires 12a, 12b are wound in a spiral shape in the case of the two-wire spiral electric wire 11A, and by the number of turns of the two insulated electric wires 12a, 12b in the spiral shape in the case of the two-wire coil electric wire 11B.

[0043] The sensor device 2 can be used alone as a device that detects mechanical deformation and environmental changes. That is, by detecting mechanical deformation and environmental changes applied to the sensor wire 1 itself, the sensor device 2 can be used as an inspection device that detects mechanical loads occurring in the environment in which the sensor wire 1 is installed, as well as changes in temperature and substances present in that environment. Alternatively, the sensor wire 1 may be incorporated into a wire harness together with other wires, and the sensor device 2 may be used as a component that detects mechanical deformation and environmental changes applied to the entire wire harness. A form in which the sensor device 2 is used as a component of this wire harness will be described below.

[0044] (3) Wire Harness As shown in Fig. 2B , a wire harness 3 according to an embodiment of the present disclosure includes the sensor device 2 and a target electric wire 31. In the illustrated embodiment, the sensor device 2 includes a spiral-type sensor electric wire 1A. The target electric wire 31 is an electric wire that is the target of monitoring mechanical deformation and environmental changes by the sensor device 2, and is configured of at least one electric wire. In the illustrated embodiment, the target electric wire 31 includes only one electric wire. When the target electric wire 31 includes multiple electric wires, the multiple electric wires may be bundled together with their longitudinal directions aligned.

[0045] In the wire harness 3, the sensor wire 1 constituting the sensor device 2 is disposed in at least a partial region along the longitudinal direction of the target electric wire 31. When the sensor wire 1 has a planar structure like the illustrated spiral-type sensor wire 1A, the sensor wire 1 may be disposed in contact with or close to the target electric wire 31 at a partial position along the longitudinal axis of the target electric wire 31, for example, at a position susceptible to mechanical deformation or environmental changes. When the sensor wire 1 has a linear structure like the coil-type sensor wire 1B, the sensor wire 1 may be disposed with its axis aligned with the longitudinal axis of the target electric wire 31. In this case, the sensor wire 1 may be disposed side by side with the target electric wire 31, or the target electric wire 31 may be inserted into a space inside the sensor wire 1, such as the hollow portion 111 of the two-wire coil electric wire 11B constituting the coil-type sensor wire 1B. The target electric wire 31 and the sensor wire 1 are preferably integrated together using an exterior material, tape, or the like to prevent them from separating.

[0046] As described above, the sensor device 2 can detect mechanical deformation or environmental changes that occur to the sensor wire 1 through changes in the response signal. In the wire harness 3, the sensor wire 1 is arranged together with the target electric wire 31, and the entire assembly of the sensor wire 1 and the target electric wire 31 is subjected to mechanical deformation or environmental changes. Therefore, when the sensor device 2 detects that mechanical deformation or environmental changes have occurred to the sensor wire 1, this means that the same type of mechanical deformation or environmental change has also occurred to the target electric wire 31. In this way, when changes such as mechanical deformation or environmental changes that may affect the characteristics or function of the target electric wire 31 occur, the sensor wire 1 can detect these changes. Using the detection results, for example, the target electric wire 31 can be used while taking into consideration the effects that these changes may have on the characteristics and function of the target electric wire 31. Furthermore, measures such as replacing the target electric wire 31 can be taken before the effects of mechanical deformation or environmental changes accumulate and cause irreversible damage or deterioration to the target electric wire 31.

[0047] Alternatively, in the wire harness 3, in addition to using the sensor device 2 as a means for detecting undesired changes in the target electric wires 31 and taking countermeasures, as described above, the sensor device 2 can also be used as a means for inputting instructions and information from outside. For example, in the wire harness 3 connected to a device, the sensor wire 1 may be disposed at the terminal portion or midway along the path of the target electric wires 31, and instructions and information required for operating the device may be input by applying mechanical deformation or environmental changes to the sensor wire 1 from outside. A system may then be configured in which the monitoring means 21 reads the input instructions and information in the form of changes in the response signal and inputs them to the device. Examples of a method for inputting instructions and information that can apply mechanical deformation or environmental changes to the sensor wire 1 include touching or pressing the sensor wire 1 with a finger.

[0048] <Monitoring Changes Using a Sensor Wire> Next, a mechanism for monitoring changes such as mechanical deformation and environmental changes in the sensor wire 1 will be described, along with a configuration of the sensor wire 1 suitable for realizing this mechanism. First, a case where mechanical deformation is applied to the sensor wire 1 will be described in detail. Next, a case where an environmental change, that is, a temperature change or a change in a contacting substance, is applied to the sensor wire 1 will be described. In the description of the case where an environmental change is applied, matters common to the case where a mechanical change is applied will be omitted as appropriate. The following description will be given taking as an example a case where characteristic impedance is measured as a response signal.

[0049] (1) When Mechanical Deformation is Applied As a typical example of mechanical deformation, a case will be described in which a mechanical load is applied to the sensor wire 1, causing mechanical deformation in a direction that increases the distance between the insulated wires 12a and 12b that make up the sensor wire 1. Examples of mechanical deformation in a direction that increases the distance between the insulated wires 12a and 12b include a case in which the spiral-wound sensor wire 1A is deformed by lifting the center from its original planar structure to a conical three-dimensional structure, and a case in which the spiral shape is deformed in a direction that expands the spiral shape within the plane. Another example is a case in which the coil-type sensor wire 1B is elongated along its central axis.

[0050] FIG. 3A shows a schematic cross section of the wire assembly 11 taken along a reference line B for the sensor wire 1 in its initial, undeformed state. In the figure, the first insulated wires 12a and the second insulated wires 12b constituting the wire assembly 11 are arranged alternately. A differential signal is input as an inspection signal to the wire assembly 11, causing the polarities of the pair of insulated wires 12a, 12b to be different from each other. In the cross section, the insulated wires 12a, 12b with opposite polarities are arranged alternately (the polarities are indicated by + and - signs in the figure). When the inspection signal is input to the wire assembly 11, an electric field is generated in the space surrounding the wire assembly 11. As shown by the dashed and dotted lines in the figure, electric field lines are generated connecting adjacent insulated wires 12a, 12b. In the figure, the dashed and dotted lines indicate electric field lines pointing in opposite directions. The density of the electric field lines corresponds to the electric field strength. The magnitude of the characteristic impedance measured as the response signal reflects the state of the electric field generated by the wire assembly 11. The display formats of the diagrams are the same in Figures 3B to 6B.

[0051] When the wire assembly 11 is deformed from the state shown in Fig. 3A in a direction increasing the distance between the insulated wires 12a, 12b, the adjacent insulated wires 12a, 12b in the wire assembly 11 move apart along the reference line B, as shown in Fig. 3B. This reduces the density of electric field lines in the space surrounding the wire assembly 11. In other words, the electric field strength decreases. The increase in the distance between the adjacent insulated wires 12a, 12b occurs both between a pair of two insulated wires 12a, 12b that are adjacent with their longitudinal axes aligned, and between two insulated wires 12a, 12b that are adjacent to each other by bending the pair of insulated wires 12a, 12b to form the wire assembly 11 into a predetermined shape.

[0052] In the wire assembly 11, adjacent insulated wires 12a, 12b have opposite polarities, so that the adjacent insulated wires 12a, 12b behave as a type of capacitor, and the capacitor characteristics affect the characteristic impedance between the pair of insulated wires 12a, 12b. The characteristics of a capacitor change depending on the distance between the electrodes. In the sensor wire 1 of this embodiment, when mechanical deformation is applied to the wire assembly 11, the distance between the adjacent insulated wires 12a, 12b with opposite polarities increases, and the electric field strength in the space near the wire assembly 11 weakens, the characteristic impedance measured as a response signal in the sensor wire 1 increases. The greater the deformation of the wire assembly 11, the greater the increase in the characteristic impedance.

[0053] Using this, the sensor wire 1 can detect mechanical deformation in a direction that increases the distance between the insulated wires 12 a, 12 b in the sensor wire 1 itself or in the wire harness 3 including the sensor wire 1. For example, in the wire harness 3, when an inspection signal is input to the sensor wire 1 and the characteristic impedance of the response signal obtained increases beyond a predetermined reference value, it can be determined that a mechanical load is being applied to the sensor wire 1 and the target wire 31 in a direction that increases the distance between the insulated wires 12 a, 12 b that constitute the wire assembly 11. The reference value may be set as the amount of change in the characteristic impedance of the sensor wire 1 that corresponds to the upper limit of the allowable deformation of the target wire 31. Applying an excessive mechanical load to the wire can lead to an abnormality such as a break. Therefore, detecting the load before the target wire 31 experiences a full-scale abnormality due to the accumulated effect of the load allows early countermeasures to be taken.

[0054] In the sensor wire 1 according to this embodiment, the pair of insulated wires 12a, 12b are not arranged with their longitudinal axes aligned and stretched straight, but are bent to form the wire assembly 11 in a spiral or helical shape, allowing for sensitive detection of mechanical deformation as a change in response signal. One reason for this is that, as described above, a change in the characteristic impedance caused by a change in the distance between the insulated wires 12a, 12b having opposite polarities due to deformation of the wire assembly 11, i.e., a change in the overall shape of the wire assembly 11, can be utilized. If the pair of insulated wires 12a, 12b were arranged with their longitudinal axes stretched straight, such a change in the characteristic impedance caused by a change in the distance between the insulated wires 12a, 12b would be unlikely to occur. Another reason is that the insulated wires 12a, 12b constituting the wire assembly 11 are formed with bending, which increases the actual lengths (lengths along the longitudinal direction of the insulated wires 12a, 12b themselves) of the wire assembly 11, thereby increasing the total amount of change in characteristic impedance throughout the wire assembly 11. Furthermore, because the deformation of the wire assembly 11 can occur reversibly, even if mechanical loads are repeatedly and intermittently applied to the wire harness 3, the application of the loads can be detected each time the loads are applied. In this respect, the detection member is different from the conductive tape or laminated tape disclosed in Patent Document 1, which detects the application of an external load by causing irreversible damage.

[0055] In the wire assembly 11 constituting the sensor wire 1, the pair of insulated wires 12a, 12b are bent and shaped. When an AC test signal is input, they may act as electromagnets and generate a magnetic field. In particular, in the coil-type sensor wire 1B, the insulated wires 12a, 12b have a spiral shape, which makes them more likely to act as electromagnets. However, because the pair of insulated wires 12a, 12b are shaped to the predetermined shape of the wire assembly 11 with their longitudinal axes aligned, and the test signal, which is a differential signal, imparts opposite polarities to the pair of insulated wires 12a, 12b, the magnetic fields generated by the pair of insulated wires 12a, 12b are opposite in direction and cancel each other out. Therefore, the wire assembly 11 as a whole generates virtually no magnetic field. To effectively suppress the generation of a magnetic field, the support member 13 is preferably made of a nonmagnetic material. Furthermore, when an AC signal is input to a single insulated wire that has been bent into a spiral or other shape, not only is there a possibility that a magnetic field will be generated, but there will be almost no change in the characteristic impedance as a response signal even when subjected to mechanical deformation or environmental changes, and the wire will not function as a sensor wire.

[0056] As described above, when the sensor wire 1 is deformed in a direction increasing the distance between the insulated wires 12 a, 12 b, the deformation can be detected from a change in the characteristic impedance obtained as a response signal by inputting an inspection signal consisting of a differential signal. However, when other types of mechanical deformation are applied to the sensor wire 1, the mechanical deformation can also be detected from a change in the response signal via a change in the electric field caused by a change in the distance between the alternating insulated wires 12 a, 12 b in the assembled shape of the wire assembly 11. For example, when the sensor wire 1 is deformed from a state in which there is a certain distance between the insulated wires 12 a, 12 b to a state in which that distance decreases, the adjacent insulated wires 12 a, 12 b in the wire assembly 11 move closer to each other along the reference line B, and the characteristic impedance obtained as a response signal when the inspection signal is input decreases. The greater the amount of deformation, the greater the decrease in the response signal.

[0057] Furthermore, when the sensor wire 1 is bent, that is, when the plane defined by the spiral-wound sensor wire 1A is bent or when the central axis of the coil-type sensor wire 1B is bent from a straight state into an arc, the characteristic impedance obtained as the response signal also changes. This is because the sensor wire 1 is elongated in some portions of the bent shape (e.g., the outer side of the bent shape of the coil-type sensor wire 1B), increasing the distance between adjacent insulated wires 12a, 12b, and the sensor wire 1 is compressed in other portions of the bent shape (e.g., the inner side of the bent shape of the coil-type sensor wire 1B), decreasing the distance between adjacent insulated wires 12a, 12b. The direction of the change in the response signal depends on the specific bent shape. However, when a pair of insulated wires 12a, 12b are relatively densely packed in the wire assembly 11, the effect of deformation in the direction increasing the distance between adjacent insulated wires 12a, 12b is stronger, and bending causes an increasing change in the characteristic impedance as the response signal. The amount of change in the response signal increases as the amount of bending increases.

[0058] From the viewpoint of sensitively detecting the mechanical deformation of the sensor wire 1 as a change in the response signal, it is preferable that the insulating coatings 122 of the insulated wires 12a, 12b constituting the wire assembly 11 are thin. This is because, in the assembled shape of the wire assembly 11, the shorter the distance between the conductors 121 constituting the adjacent insulated wires 12a, 12b, the greater the change in the electric field due to the mechanical deformation of the wire assembly 11, resulting in a large change in the characteristic impedance. As will be described later, when detecting environmental changes using the sensor wire 1, the thinner the insulating coating 122, the more easily changes in the surrounding environment are reflected as changes in the electric field formed by the conductors 121. The thinner the insulating coating 122, as long as the insulation properties of the conductors 121 can be ensured, and it is most preferable to use enameled wires for the insulated wires 12a, 12b.

[0059] Furthermore, in the wire assembly 11, it is preferable that a pair of insulated electric wires 12 a, 12 b, which are bent with their longitudinal axes aligned to form a predetermined assembled shape, are tightly packed together by reducing the gaps between adjacent portions, such as between the circumferences of the spiral shape or between the turns of the helical shape, due to the bending. This reduces the difference between the distance between the insulated electric wires 12 a, 12 b paired with their longitudinal axes aligned (e.g., the distance between the nth and (n+1)th insulated electric wires from the left in FIG. 3A ; n is a positive odd number) and the distance between the insulated electric wires 12 a, 12 b that have become adjacent due to bending (the distance between the n+1st and (n+2)th insulated electric wires from the left in FIG. 3A ). This allows for highly uniform changes in characteristic impedance due to mechanical deformation or environmental changes throughout the entire wire assembly 11. Furthermore, the amount of change in characteristic impedance due to mechanical deformation or environmental changes increases as a result of the insulated electric wires 12 a, 12 b being arranged at high density in the electric wire assembly 11. Preferably, the electric wire assembly 11 is formed by arranging a pair of insulated electric wires 12 a, 12 b in close contact with each other, excluding unavoidable gaps, and then bending the pair of insulated electric wires 12 a, 12 b to form a group without leaving any gaps between adjacent wires.

[0060] From the viewpoint of allowing the mechanical deformation of the sensor wire 1 to be largely reflected in changes in the response signal, it is preferable not to provide the sensor wire 1 with a support material 13 and to keep the wire assembly 11 in a state in which it is easily deformed. However, from the viewpoint of making it easier for the sensor wire 1 to stand on its own and preventing the sensor wire 1 from detecting minute deformations, such as deformations due to normal minute vibrations, it is preferable to support the wire assembly 11 with a support material 13. It is preferable to use a support material 13 that can deform together with the wire assembly 11 and the target electric wire 31 that is the object of monitoring without excessively interfering with the mechanical deformation of the wire assembly 11 and the target electric wire 31. In other words, it is sufficient to use a support material 13 that has flexibility (flexibility and stretchability) that allows it to deform in accordance with the deformation of the wire assembly 11.

[0061] As a support material 13 that is easily deformed mechanically, a relatively thin plate material can be used for the spiral-wound sensor wire 1A. It is particularly preferable to make the plate material from a resin material. On the other hand, a core material made of a hollow cylinder can be used for the coil-type sensor wire 1B. A hollow cylinder is more likely to deform due to external forces than a solid body. It is particularly preferable to make the hollow cylinder from a resin material. To primarily detect mechanical deformation using the sensor wire 1 and minimize changes in the response signal due to temperature changes, it is preferable to make the hollow cylinder support material 13 open at both ends along the central axis of the two-wire coil electric wire 11B. This is to reduce the effects of expansion / contraction of the air sealed in the hollow portion. If it is desired to minimize changes in the response signal due to mechanical deformation, for example to primarily detect changes in substances in the environment, the support material 13 can be configured to have a shape that is less susceptible to deformation, such as a thick plate material in the spiral-type sensor wire 1A or a solid rod-shaped body in the coil-type sensor wire 1B.

[0062] The sensor wire 1 for detecting mechanical deformation may have any shape of wire assembly 11, but a sensor wire 1 having a linear structure, such as coil-type sensor wire 1B, can detect mechanical deformation more sensitively than a sensor wire 1 having a planar structure, such as spiral-type sensor wire 1A. This is because a sensor wire 1 having a linear structure is prone to undergo large mechanical deformation along the axis of the linear structure, such as expansion and contraction of the spiral shape, when an external force is applied, resulting in a large change in the response signal. On the other hand, when a sensor wire 1 having a planar structure, such as spiral-type sensor wire 1A, is used, mechanical deformation can be detected regardless of where on the surface of the wire assembly 11 the deformation occurs. Therefore, when it is necessary to detect mechanical deformation over a certain area, a sensor wire 1 having a planar structure is preferable.

[0063] (2) When a Change Occurs in the Contacting Material The environmental changes that can occur in the sensor wire 1 include a temperature change and a change in the material that comes into contact with the wire assembly 11. First, we will explain the case where the material that comes into contact with the wire assembly 11 changes. There are two possible cases where the material that comes into contact with the wire assembly 11 changes: when the type of material that comes into contact with the wire assembly 11 changes, that is, when a material different from the material that was initially in contact with the wire assembly 11 comes into contact with the wire assembly 11; and when the state of the material that comes into contact with the wire assembly 11 changes. In either case, a change in the dielectric constant of the material that exists around the wire assembly 11 occurs, and this occurs through a similar mechanism, in that the dielectric constant of the material that exists around the wire assembly 11 changes.

[0064] First, an example will be described in which a liquid comes into contact with the wire assembly 11. Figures 4A and 4B schematically show a cross section of the wire assembly 11 cut along a reference line B when the wire assembly 11 comes into contact with a liquid. Figure 4A shows the wire assembly 11 before contact with the liquid, and is the same as that shown in Figure 3A. Figure 4B shows the state after the liquid L comes into contact with the wire assembly 11.

[0065] The electric field formed when an inspection signal is input to the wire assembly 11 depends on the dielectric constant of the surrounding material; the higher the dielectric constant, the higher the electric field strength. In other words, the density of electric field lines between adjacent insulated wires 12a, 12b increases. In the state before contact with the liquid L shown in FIG. 4A , the wire assembly 11 is surrounded by and in contact with air. Because air has a relative dielectric constant of approximately 1, the density of electric field lines is low. In contrast, when the liquid L comes into contact with the wire assembly 11, as shown in FIG. 4B , the liquid L not only covers the surface of the wire assembly 11 but also penetrates into the spaces between adjacent insulated wires 12a, 12b in the assembled shape of the wire assembly 11. Typical liquid materials have a higher dielectric constant than air. Therefore, contact with the liquid L increases the electric field strength formed by the wire assembly 11, and the density of electric field lines formed between adjacent insulated wires 12a, 12b increases, as shown in FIG. 4B . As a result, the characteristic impedance measured as a response signal in the sensor wire 1 decreases. The larger the area of ​​the wire assembly 11 that is in contact with the liquid L, the greater the decrease in the characteristic impedance.

[0066] Using this, the sensor wire 1 can detect contact of the liquid L with the sensor wire 1 itself or the wire harness 3 including the sensor wire 1. For example, in the wire harness 3, when a response signal obtained by inputting an inspection signal to the sensor wire 1 decreases beyond a predetermined reference value, it can be determined that the liquid L has come into contact with the sensor wire 1 and the target wire 31. The reference value may be defined as the amount of change in the characteristic impedance of the sensor wire 1 corresponding to the upper limit of the allowable amount of contact. When a liquid such as water or oil comes into contact with an electric wire, the performance of the electric wire may be affected, such as by a decrease in insulation due to the conductivity of the electric wire if the liquid is conductive, or by the liquid's deterioration of the electric wire components. In particular, with electric wires for automobiles, water from the external environment or oil from the interior of the automobile, such as engine oil, may enter the contact points with the electric wire due to defective sealing, making it important to detect the intrusion of such water or oil early. In the configuration described above for detecting mechanical deformation in a direction increasing the distance between the insulated wires 12 a, 12 b, it was preferable to form the insulated wires 12 a, 12 b into a predetermined assembled shape without providing gaps between adjacent portions of the wire assembly 11 by bending. However, in the configuration described here for detecting contact of the liquid L, from the viewpoint of increasing the change in the response signal caused by the liquid L entering between the insulated wires 12 a, 12 b that constitute the wire assembly 11, it is preferable to configure the wire assembly 11 so that a certain amount of gap is provided between adjacent insulated wires 12 a, 12 b by bending, allowing the liquid L to easily enter.

[0067] In cases where the substance in contact with the wire assembly 11 is a liquid or a solid, a change in the substance in contact with the wire assembly 11 can be detected by a change in the characteristic impedance, which serves as a response signal. In the case of a solid substance, as in the case of the liquid substance described above, the response signal of the sensor wire 1 changes due to a change in the dielectric constant of the substance surrounding the wire assembly 11. However, in the case of a liquid substance, as shown in FIG. 4B , when the liquid substance comes into contact with the wire assembly 11, it penetrates into the gaps between the insulated wires 12 a and 12 b that make up the wire assembly 11. However, in the case of a solid substance, it cannot penetrate into the gaps between the insulated wires 12 a and 12 b in this way and only comes into contact with the wire assembly 11 on its surface (see FIG. 5A ). Therefore, when a substance with a similar dielectric constant comes into contact with the wire assembly 11, if the substance is solid, the change in the response signal is less likely to be large compared to when the substance is liquid. The change in the response signal due to contact of a solid substance with the wire assembly 11 can be suitably used, for example, to input instructions or information by touching with a finger.

[0068] In the embodiment described above, the change in the substance in contact with the wire assembly 11 is such that the type of substance in contact with the wire assembly 11 changes from air to another liquid or solid substance. However, a case where the type of substance in contact with the wire assembly 11 remains the same but the state of the substance changes will also be described. Examples of changes in the state of a substance include a phase transformation and a chemical change. The dielectric constant of the substance in contact with the wire assembly 11 changes through a phase transformation or a chemical change, and the distribution of the substance around the wire assembly 11 also changes, which changes the state of the electric field formed by the wire assembly 11 and causes a change in the response signal obtained from the sensor wire 1. The change in the state of the substance in contact with the wire assembly 11 can be detected based on the change in the response signal.

[0069] An example of a phase transformation occurring among changes in the state of a substance (contact substance) in contact with the electric wire assembly 11 is when the contact substance melts and changes from a solid to a liquid. In many substances, the dielectric constants of solids and liquids are different, so when a phase transformation occurs from a solid to a liquid, a change occurs in the characteristic impedance obtained as a response signal in the sensor wire 1. In addition, when the contact substance in contact with the electric wire assembly 11 acquires fluidity through melting, the spatial distribution of the contact substance changes, as shown in Figures 5A and 5B, and this spatial distribution also changes the characteristic impedance.

[0070] FIG. 5A shows the state of the solid contact material C before it melts, and FIG. 5B shows the state of the contact material C after it melts, in a cross-sectional view of the wire assembly 11. As shown in FIG. 5A , before it melts, the contact material C is only in contact with the wire assembly 11 on its solid surface. However, as it melts and acquires fluidity, it penetrates into the gaps between the insulated wires 12 a and 12 b that make up the wire assembly 11, as shown in FIG. 5B . As a result, the contact material C becomes distributed near the insulated wires 12 a and 12 b that make up the wire assembly 11, increasing the dielectric constant in the region near the insulated wires 12 a and 12 b. As a result, the electric field strength near the wire assembly 11 increases, and the density of the electric field lines also increases. This reduces the characteristic impedance obtained as a response signal. This mechanism is the same as that described above for the contact of the liquid L with reference to FIGS. 4A and 4B .

[0071] When the contact material C is heated and melted, and then cooled, the contact material C returns to a solid state, but the spatial distribution of the molten contact material C, i.e., the state in which the contact material C has penetrated into the gaps between the insulated electric wires 12a and 12b that make up the electric wire assembly 11, as shown in Fig. 5B, is maintained. In other words, even though the dielectric constant of the contact material C is the same as in the state before melting as shown in Fig. 5A, the distribution of the contact material C near the insulated electric wires 12a and 12b that make up the electric wire assembly 11 increases the dielectric constant in the regions near the insulated electric wires 12a and 12b, which results in a decrease in the characteristic impedance obtained as a response signal.

[0072] Next, among the changes in the state of a substance in contact with the electric wire assembly 11, an example of a case in which a chemical change occurs is when the contact substance C in contact with the electric wire assembly 11 undergoes a chemical reaction with other substances, such as components in the atmosphere in which the contact substance C is placed, or when the contact substance C undergoes decomposition or deterioration, resulting in a change in the dielectric constant of the contact substance C. Figures 6A and 6B show cross-sectional views of such cases in which the contact substance C undergoes a chemical change.

[0073] 6A shows the state of the contact material C before it undergoes a chemical change, and FIG. 6B shows the state after it has undergone the chemical change. Here, it is assumed that the chemical change is a chemical reaction that increases the dielectric constant of the contact material C. As shown in FIG. 6B, when the dielectric constant of the contact material C increases due to a chemical change, the electric field strength formed by the electric wire assembly 11 increases, and the density of the electric field lines also increases. This reduces the characteristic impedance obtained as a response signal in the sensor wire 1. Conversely, if the dielectric constant of the contact material C decreases due to a chemical change, the characteristic impedance increases.

[0074] In this way, a chemical change in the contact material C can be detected by a change in the response signal obtained in the sensor wire 1. This detection of a chemical change can be applied when the dielectric constant of the contact material C changes due to a chemical change, or when the conductivity, which is a physical property correlated with the dielectric constant, changes. By detecting a phase transformation or chemical change in the contact material C, it is possible to detect changes in the environment in which the sensor wire 1 itself and the wire harness 3 including the sensor wire 1 are placed.

[0075] The contact substance C that comes into contact with the wire assembly 11 of the sensor wire 1 is assumed to be a substance external to the sensor wire 1 that is present near the sensor wire 1 in the environment in which the sensor wire 1 is placed, but it may also be a substance internal to the sensor wire 1. That is, the sensor wire 1 may be configured with the contact substance C incorporated therein in advance. By disposing a material, whose dielectric constant changes sensitively in response to changes in the environment in which the sensor wire 1 is placed, as the contact substance C in contact with the wire assembly 11, when a change in the environment occurs, the change in the dielectric constant of the contact substance C can be detected with high sensitivity as a change in the response signal of the sensor wire 1. The intermediary material described above in connection with the outline of the configuration of the sensor wire 1 corresponds to the contact substance C that is intentionally incorporated into the sensor wire 1 in this way. As described above, the intermediary material is a substance that causes a change in the dielectric constant in the area surrounding the wire assembly 11 in response to a change in the environment, and the intermediary material is disposed in contact with the wire assembly 11. The phenomenon that causes the change in the dielectric constant of the medium can include a phase transformation and a chemical change of the medium.

[0076] An example of a configuration using an intermediary material is a configuration using a water-absorbent polymer. The water-absorbent polymer is a substance that transforms from a solid state to a gel state upon absorbing water. In the sensor wire 1, a dry water-absorbent polymer may be placed in contact with the wire assembly 11 by filling the space inside the wire assembly 11 (e.g., the hollow portion 111 of the two-wire coil electric wire 11B) or by forming it into a sheet or tube and placing it on the surface of the wire assembly 11. In this state, when water is introduced into the space in which the sensor wire 1 is placed and comes into contact with the water-absorbent polymer, the water-absorbent polymer absorbs the water and gels. Compared to the water-absorbent polymer before absorbing water, the water-absorbent polymer often has a higher dielectric constant. Furthermore, as the water-absorbent polymer gels, it swells and adheres closely to the insulated electric wires 12a and 12b that make up the wire assembly 11. As a result, the characteristic impedance obtained as a response signal from the sensor wire 1 increases. In this way, by using a water-absorbing polymer as an intermediary material, it is possible to sensitively detect water being introduced into the sensor wire 1 itself or into the space in which the wire harness 3 equipped with the sensor wire 1 is placed.

[0077] Another example of a configuration using an intermediary material is a configuration using a functional material (gas sensing material) that undergoes a chemical reaction upon contact with specific gas molecules. In the sensor wire 1, such gas sensing material may be brought into contact with the wire assembly 11 by filling the space inside the wire assembly 11, forming it into a sheet or tube shape, and placing it on the surface of the wire assembly 11. In this state, when gas molecules that cause a chemical reaction in the gas sensing material are introduced into the space in which the sensor wire 1 is placed, the gas sensing material comes into contact with the gas molecules and initiates a chemical reaction. When the dielectric constant or conductivity of the gas sensing material changes due to the chemical reaction, a change occurs in the characteristic impedance obtained as a response signal in the sensor wire 1. By detecting this change, it is possible to detect the introduction of the gas molecules into the space in which the sensor wire 1 is placed. For example, in a hydrogen-powered vehicle, if a sensor wire 1 having a gas sensing material that selectively detects hydrogen as an intermediary material is placed in a location where a hydrogen leak is likely to occur, a hydrogen leak can be detected early.

[0078] The sensor wire 1 for detecting a change in a substance with which it comes into contact may have any shape of wire assembly 11, but if a sensor wire 1 having a planar structure, such as spiral-type sensor wire 1A, is used, it will be possible to detect a change in the substance with which it comes into contact, regardless of where that change occurs on the surface of wire assembly 11. Therefore, when it is necessary to detect a change in a substance with which it comes into contact over a region that extends over a certain area, it is preferable to use a sensor wire 1 having a planar structure. On the other hand, when it is necessary to detect a change in a substance with which it comes into contact over a region that extends over a certain length, it is sufficient to use a sensor wire 1 having a linear structure, such as coil-type sensor wire 1B.

[0079] (3) When a Temperature Change is Added Next, a case where a temperature change occurs among the environmental changes applied to the sensor wire 1 will be described. The temperature change in the sensor wire 1 can be detected directly through a change in the dielectric constant of the surrounding material due to a temperature change, or it can be detected through the mechanical deformation of the wire assembly 11, among the change phenomena described above, or through a change in the material with which the wire assembly 11 comes into contact. In many cases, the change in the dielectric constant of a material due to a temperature change that does not involve a phase transformation is small, and when direct detection is performed through a change in the dielectric constant of the surrounding material, the amount of change in the response signal is small. However, by incorporating a mechanical deformation of the wire assembly 11 or a change in the material with which the wire assembly 11 comes into contact, the change in the response signal can be increased.

[0080] An example of a mode in which a temperature change is detected via mechanical deformation of the wire assembly 11 is when, in a sensor wire 1 in which the wire assembly 11 is supported by a support material 13, the support material 13 expands when the sensor wire 1 is heated, causing deformation in the wire assembly 11, such as elongation of the two-wire coil wire 11B and expansion of the spiral shape of the two-wire spiral wire 11A. When such deformation occurs, accompanied by a change in the distance between adjacent insulated wires 12a, 12b, the characteristic impedance as a response signal changes due to a mechanism similar to that described above for the deformation of the wire assembly 11 due to a mechanical load, that is, due to a change in the state of the electric field. The greater the temperature rise and the greater the amount of expansion of the support material 13, the greater the change in the response signal.

[0081] To sensitively reflect temperature changes as changes in the response signal, it is preferable to use a support material 13 that undergoes significant expansion / contraction in response to temperature changes. Examples of such support materials 13 include those with an internal space filled with gas. For example, the support material 13 used in the coil-type sensor wire 1B may be a core material configured as a hollow cylinder with both ends closed. When such support material 13 is heated, the gas enclosed therein expands, and the expansion of the gas also pushes open the outer wall of the support material 13, expanding it. By utilizing the expansion of the gas in this way, the deformation of the support material 13 increases as the temperature rises, and as a result, the change in the response signal also increases. The gas enclosed in the support material 13 may be air or a gas other than air. The pressure of the enclosed gas may be atmospheric pressure, but if the gas is enclosed at a pressure higher than atmospheric pressure, the amount of expansion during temperature rise can be increased.

[0082] As an example of a mode in which a temperature change is detected via a change in a material that comes into contact with the electric wire assembly 11, a medium that includes a material that causes a change in the dielectric constant in the area surrounding the electric wire assembly 11 due to a temperature change may be used as the medium that constitutes the sensor electric wire 1. Even if the temperature of the gas in the space in which the electric wire assembly 11 is placed changes, the change in the dielectric constant is very small. However, a large change in the dielectric constant around the electric wire assembly 11 occurs due to a change in state or chemical change of the medium due to temperature, which can be detected as a large change in the response signal.

[0083] An example of such a configuration for detecting temperature changes using an intermediary material is a configuration in which an adhesive-backed material is disposed on the outside of the wire assembly 11. The adhesive-backed material refers to a material in which an adhesive layer made of a material (thermoplastic material) that softens or melts, preferably melts, when heated is provided on the surface of a sheet-like or tubular substrate. For a sensor wire 1 having a planar structure, such as the spiral-wound sensor wire 1A, a material in which an adhesive layer is provided on one side of a sheet-like substrate may be used as the intermediary material. The adhesive layer of this type of intermediary material may be brought into contact with the surface of the wire assembly 11. On the other hand, for a sensor wire 1 having a linear structure, such as the coil-type sensor wire 1B, a material in which an adhesive layer is provided on the inner surface of a tubular substrate may be used as the intermediary material. The outer periphery of the wire assembly 11 may be covered with this type of intermediary material. A heat-shrinkable tube may be used as the tubular material having an adhesive layer on the inner surface. Heat-shrinkable tubing with an adhesive layer is widely used as a member for insulating and protecting electrical components.

[0084] In a sensor wire 1 having an intermediary material with an adhesive layer, when the temperature of the environment rises and the temperature exceeds the temperature at which the adhesive softens or melts and becomes flowable, the adhesive flows and penetrates into the gaps between the insulated wires 12a, 12b of the wire assembly 11, as shown in the transition from Figure 5A to Figure 5B . In addition, if the intermediary material is a heat-shrinkable tube, when the temperature rises to the temperature at which the heat-shrinkable tube shrinks, the heat-shrinkable tube shrinks, applying a force that presses the adhesive toward the wire assembly 11 and promoting penetration of the adhesive into the gaps between the insulated wires 12a, 12b. Even if the environmental temperature subsequently drops, the adhesive solidifies while remaining in the gaps between the insulated wires 12a, 12b of the wire assembly 11, as shown in Figure 5B . In this way, penetration of the adhesive into the gaps between the insulated wires 12a, 12b of the wire assembly 11 reduces the characteristic impedance of the sensor wire 1, which is obtained as a response signal.

[0085] Temperature changes in electric wires for automobiles and the like can affect the functionality of the wire, such as by changing transmission characteristics. Furthermore, large or repeated temperature changes can cause irreversible damage or deterioration to the components of the wire, such as the insulating coating, and to surrounding components. By detecting temperature changes using the sensor wire 1, whether installed alone or in a wire harness 3 that includes the sensor wire 1 together with a target electric wire 31, it becomes possible to take measures against these events.

[0086] (4) Various Forms of Monitoring Using the Sensor Wire As described above, by using the sensor wire 1, it is possible to detect environmental changes, such as mechanical deformation, temperature change, and change in a contact material, in the sensor wire 1 itself or in the wire harness 3 including the sensor wire 1, based on a change in the response signal obtained when an inspection signal consisting of a differential signal is input. For example, when a change exceeding a reference value occurs in the response signal, it can be determined that one of the following change events has occurred in the sensor wire 1: mechanical deformation, temperature change, or change in a contact material. If the sensor wire 1 is used to monitor for unwanted changes, the monitoring means 21 of the sensor device 2 can be configured to appropriately notify personnel, such as a system administrator, of the system including the sensor wire 1 by issuing an alarm or the like. On the other hand, if the sensor wire 1 is used to input instructions or information from outside, it can be configured to determine that a specific instruction or information required for operation has been input to a device to which the sensor wire 1 is connected when a change exceeding a reference value occurs in the response signal, and to execute an operation corresponding to the instruction or information. In either case, the reference value of the response signal may be determined so as to correspond to the lower limit of the amount of change at which a change event should be considered to have occurred.

[0087] As explained above for each form, which of the various change events is to be sensitively detected can be set by selecting the assembly shape of the insulated electric wires 12a, 12b in the electric wire assembly 11, the presence or absence, structure, and constituent materials of the support material 13 and intermediate material. Generally, linear sensor electric wires 1 such as the coil-type sensor electric wire 1B are particularly suited to detecting mechanical deformation and temperature changes, while planar sensor electric wires 1 such as the spiral-type sensor electric wire 1A are particularly suited to detecting changes in materials with which they come into contact.

[0088] The sensor device 2 may be configured to monitor the intensity of a specific frequency of the response signal when receiving an inspection signal and acquiring a response signal. If a predetermined change occurs in the intensity of the response signal received at that frequency, it may determine that a change event has occurred in the sensor wire 1. Furthermore, the greater the change in the response signal, the greater the degree of change in the change event. Alternatively, an inspection signal over a certain frequency range may be input, and the occurrence and extent of the change event may be determined based on the change in the response signal within that frequency range. Furthermore, by measuring the response signal using the time domain method or the frequency domain method, the area where a change occurs in the response signal can be associated with position information, thereby identifying the location of a change event, such as local deformation or local contact with an external object, in the sensor wire 1. In the time domain method, the time axis can be converted to a position on the sensor wire 1 based on the propagation speed of the inspection signal. On the other hand, in the frequency domain method, the frequency information can be converted to a position on the sensor wire 1 by performing an inverse Fourier transform on the response signal obtained relative to the frequency axis. Preferably, the time domain method or the frequency domain method may be used. In the sensor device 2, the response signal may be acquired continuously to constantly monitor whether or not a change event has occurred in the sensor wire 1, or the response signal may be acquired intermittently so that when a change event occurs in the sensor wire 1, it can be detected with little delay.

[0089] In the wire harness 3, the sensor wire 1 may be disposed to monitor the occurrence of a change event over the entire longitudinal length of the target electric wire 31, or may be disposed only in a partial region, such as a position where a change event such as mechanical deformation is likely to occur. The wire harness 3 may include only one sensor wire 1, or multiple sensor wires 1 may be disposed along the longitudinal length of the target electric wire 31. For example, if there are multiple discontinuous positions along the longitudinal length of the target electric wire 31 where a change event such as mechanical deformation is likely to occur, a sensor wire 1 may be disposed at each of those positions. When multiple sensor wires 1 are disposed, the multiple sensor wires 1 may be connected in series. In this case, an inspection signal can be input and a response signal can be acquired collectively for a group of multiple serially connected sensor wires 1. Then, based on the behavior of the obtained response signal, it is possible to detect which sensor wire 1 is experiencing a change event. For example, when a response signal is acquired over a certain frequency range, the resulting spectral shape changes depending on which sensor wire 1 is experiencing a change event. Therefore, it is possible to identify which sensor wire 1 is experiencing a change event based on the spectral shape. Alternatively, as described above, by applying the time domain method or frequency domain method, it is possible to identify with high accuracy which sensor wire 1 is experiencing a change event. The multiple sensor wires 1 connected in series may all be of the same type, such as those suitable for detecting mechanical extension, or multiple types of sensor wires 1 having configurations suitable for detecting different change events may be connected. Furthermore, multiple types of sensor wires 1 having configurations suitable for detecting different change events may be arranged in parallel in a single wire harness 3, and the response signal may be monitored independently for each sensor wire 1. When multiple types of sensor wires 1 are arranged in series or parallel, the sensor wires 1 may be linear sensor wires 1 such as coil-type sensor wire 1B, planar sensor wires 1 such as spiral-type sensor wire 1A, or a mixture of both. In addition, the sensor wire 1 may be one that only monitors unwanted changes, one that only inputs instructions or information, or a combination of both.

[0090] Examples are shown below. However, the present invention is not limited to these examples. Here, it was confirmed whether various change events can be detected by the sensor wire.

[0091] [1] Detection of mechanical deformation First, a coil-type sensor wire was used to verify the case where the sensor wire was mechanically deformed.

[0092] (Test Method) First, a coil-type sensor wire having the structure shown in Fig. 1B was fabricated as a sample sensor wire. Specifically, a hollow cylindrical silicone tube with open ends was used as a base material, and two insulated enameled wires with an outer diameter of 0.4 mm were spirally wound around the outer periphery of the base material to fabricate a wire assembly consisting of a two-wire coil wire. The wire assembly had an outer diameter of 3 mm, a length of 33 mm, and 42 turns.

[0093] A differential signal was input as an inspection signal to the sensor wire, and the reflection coefficient was measured as a response signal between a pair of insulated wires. A vector network analyzer (VNWA) was used for the measurement. One end of a pair of insulated wires constituting the wire assembly was connected to one port (port 1) of the VNWA, and the other end was connected to another port (port 2). Then, the reflection coefficient S １１ The measurements were carried out in the frequency range of 1 to 100 MHz, and the evaluation was mainly carried out on the measured value at 10 MHz.

[0094] Here, the characteristic impedance of a pair of insulated wires that make up the sensor wire is Z at a point that is not affected by the change event. ０ , Z at the point affected by the change event Ｌ Then, the reflection coefficient S １１ is expressed by the following equation (1): １１ = (Z Ｌ -Z ０ ) / (Z Ｌ +Z ０ ) (1) In other words, when the characteristic impedance changes at a location affected by a change event, the reflection coefficient also changes. Therefore, in this embodiment, the reflection coefficient is measured as a characteristic instead of the characteristic impedance.

[0095] In this test, first, to confirm whether mechanical elongation can be detected, the above measurement was performed in a state where the sensor wire was at its natural length with no force applied to it, and also in a state where both ends of the sensor wire were pulled to stretch the wire assembly and the substrate together. The elongation amount of the sensor wire was determined so that the length (coil length) of the wire assembly was 105%, 109%, and 116%, with the natural length of the wire assembly being 100%.

[0096] Separately, to confirm whether mechanical bending could be detected, similar measurements were performed while bending the sensor wire. The wire assembly and the substrate were integrated, and the central axis of the sensor wire was bent into an approximately arc shape. The reflection coefficient was measured in this state. The amount of bending was measured in 10-mm increments from 50 mm to 20 mm in bending diameter. The smaller the bending diameter, the greater the amount of bending, which indicates a more severe bending. (Test Results) Figure 7 shows the measurement results of the reflection coefficient for each coil length when the sensor wire was stretched. Table 1 below summarizes the change in reflection coefficient at 10 MHz.

[0097]

[0098] As shown in Figure 7, in the frequency range lower than the region where the reflection coefficient drops sharply around 50 MHz, the reflection coefficient is higher when the sensor wire is stretched compared to when it is not stretched (coil length 100%). Furthermore, the reflection coefficient increases as the amount of stretch increases. This trend is even more clearly shown in Table 1, which summarizes the change in measured value at 10 MHz. Table 1 shows that the reflection coefficient increases nearly proportionally as the amount of coil stretch increases. These evaluation results confirm that when the sensor wire is stretched and mechanical deformation is applied in a direction that increases the distance between the insulated wires that make up the wire assembly, the stretch can be detected as an increase in the reflection coefficient. The sharp drop in the reflection coefficient around 50 MHz in Figure 7 is due to a resonance phenomenon, and changes in the reflection coefficient can be evaluated at frequencies lower than that.

[0099] Furthermore, Figure 8 shows the measurement results of the reflection coefficient for each bending diameter when the sensor wire is bent. The figure is an enlarged view of the area around 10 MHz. As shown in Figure 8, the reflection coefficient is higher when the sensor wire is bent compared to when the sensor wire is not bent (str). There is also a tendency for the reflection coefficient to increase as the bending diameter decreases and the amount of bending increases. These results confirm that even when the sensor wire is mechanically bent, the bending can be detected as an increase in the reflection coefficient.

[0100] [2] Detection of temperature change Next, we used a coil-type sensor wire to verify the case where a temperature change occurs in the environment in which the sensor wire is placed.

[0101] (Test Method) A sensor wire was prepared as a sample. The sensor wire had the same configuration as the coil-type sensor wire used in the above test [1], except for the configuration of the substrate. The substrate was a hollow cylindrical silicone tube with both ends sealed. Air was sealed in the sealed space at atmospheric pressure.

[0102] The reflection coefficient of the sensor wire was measured while it was being heated. The measurement method was the same as in Test [1]. During heating, the sensor wire was housed in a silicone pipe, wrapped in aluminum foil, and heated from the outside using a heater. The temperature of the sensor wire during heating was measured using a thermocouple between the silicone pipe and the sensor wire. The reflection coefficient was measured while the sensor wire was heated to temperatures from 22°C (unheated state) to 72°C in 10°C increments.

[0103] (Test Results) Figure 9 shows the measurement results of the reflection coefficient for each heating temperature. The figure is an enlarged view of the area around 10 MHz. Figure 9 shows that the reflection coefficient is higher when the sensor wire is heated compared to when it is not heated (22°C). Furthermore, the higher the heating temperature, the higher the reflection coefficient. This is thought to be because the air sealed inside the base material expands with heating, which stretches the base material in the longitudinal direction and also stretches the sensor wire as a whole. As confirmed in the above test [1], the stretching of the sensor wire causes an increase in the reflection coefficient. These results confirm that when the sensor wire is heated, a temperature increase can be detected as an increase in the reflection coefficient via the stretching of the sensor wire.

[0104] [3] Detection of contact with substances Finally, we carried out verification of the case where various substances were brought into contact with the spiral-wound sensor wire.

[0105] (Test Method) A spiral-wound sensor wire was fabricated as a sample sensor wire. Specifically, as shown in FIG. 1A, a substrate was prepared, made of a plate-shaped insulating material with an integral shaft portion. Two aligned enameled insulated wires with an outer diameter of 0.4 mm were spirally wound around the shaft portion on the surface of the substrate to fabricate a wire assembly consisting of a two-wire spiral wire. For the wire assembly, the two insulated wires were tightly packed within a roughly circular area with a diameter of 45 mm, with unavoidable gaps removed.

[0106] The reflection coefficient of the spiral-wound sensor wire was measured using the same measurement method as in Test [1]. During the measurements, various substances were brought into contact with the wire assembly that constitutes the sensor wire, and the reflection coefficient was measured. The liquid substances used for the contact were an electrolyte solution (eye drops), and the solid substances were a human finger and two types of rubber. During the measurements, while continuously measuring the reflection coefficient, each substance was brought into contact with the wire assembly, and the change in the reflection coefficient over time at a frequency of 10 MHz was recorded. The finger and rubber were gently brought into contact with each other, and were not pressed against the wire assembly with a force strong enough to cause mechanical deformation.

[0107] (Test Results) Figure 10 shows the measurement results of the reflection coefficient when an electrolyte solution was brought into contact with the wire assembly that constitutes the sensor wire. The graph shows the absolute value of the change in the reflection coefficient at 10 MHz over time when up to three drops of electrolyte solution were dropped onto the surface of the wire assembly. The timing at which each drop of electrolyte solution was dropped is indicated by an arrow in the figure. In addition, Table 2 below summarizes the change in the reflection coefficient for each drop amount. The position at which the electrolyte solution was dropped was changed for each drop.

[0108]

[0109] According to Figure 10 and Table 2, the reflection coefficient increases when the wire assembly is brought into contact with the electrolyte solution compared to when it is not. Furthermore, the change in the reflection coefficient increases as the amount of electrolyte solution increases. Bringing the electrolyte solution into contact with the wire assembly changes the strength of the electric field formed by the wire assembly, which is thought to change the characteristic impedance in the area where contact with the electrolyte solution occurs, thereby changing the reflection coefficient. This confirms that when a substance comes into contact with the wire assembly, the contact can be detected in the form of a change in the reflection coefficient. In Figure 10, the gradual increase in the reflection coefficient after the electrolyte solution is added drop by drop is thought to be due to the gradual penetration of the electrolyte solution into the gaps between the insulated wires that make up the wire assembly.

[0110] Figure 11 shows the measurement results of the reflection coefficient when a finger is placed in contact with the wire assembly that constitutes the sensor wire. The graph shows the absolute value of the change in the reflection coefficient at 10 MHz over time when the number of finger contact points on the surface of the wire assembly is increased from one to three. The timing at which the number of finger contact points is increased is indicated by an arrow in the figure. In addition, Table 3 below summarizes the change in the reflection coefficient for each number of contact points.

[0111]

[0112] According to FIG. 11 and Table 3, when the wire assembly is brought into contact with a finger, the reflection coefficient increases with contact, just as when the wire assembly is brought into contact with an electrolyte solution. Furthermore, the amount of change in the reflection coefficient increases as the number of finger contact points, i.e., the contact area, increases. This confirms that contact with the wire assembly can be detected not only for liquid substances but also for solid substances in the form of a change in the reflection coefficient. However, compared to the case of contact with the above-mentioned electrolyte solution, the amount of change in the reflection coefficient is kept small, even though the contact area is larger. This is interpreted as being due in part to the fact that, unlike liquid substances, solid substances cannot penetrate into the gaps between the insulated wires that make up the wire assembly, and therefore the change in the dielectric constant near the wire assembly is kept small.

[0113] Finally, Figure 12 shows the measurement results of the reflection coefficient when non-conductive rubber and conductive rubber were contacted with the wire assembly constituting the sensor wire. Here, while measuring the reflection coefficient at 10 MHz, non-conductive rubber was contacted with the surface of the wire assembly, left for a while, and then the non-conductive rubber was removed. Then, conductive rubber was contacted with the surface of the wire assembly, left for a while, and then the conductive rubber was removed. The periods during which the non-conductive rubber and conductive rubber were in contact are shown as regions A1 and A2 in the figure. The change in reflection coefficient at 10 MHz is shown in absolute values ​​in the figure. In addition, Table 4 below summarizes the change in reflection coefficient due to contact with each rubber. The contact area was the same for the non-conductive rubber and the conductive rubber, and this contact area was approximately the same as the contact area when two fingers were contacted in the above finger contact test.

[0114]

[0115] According to Figure 12 and Table 4, the reflection coefficient increases when the wire assembly is in contact with both non-conductive rubber and conductive rubber. However, as seen in the results for contact with a finger above, the amount of change is smaller than when contact with an electrolyte solution because solid materials cannot penetrate into the gaps between the insulated wires that make up the wire assembly. When comparing the change in reflection coefficient when the two types of rubber are in contact, the change in reflection coefficient is greater when the conductive rubber is in contact than when the non-conductive rubber is in contact. This result confirms that when the conductivity of the material in contact with the wire assembly changes, the increase in conductivity can be detected as an increase in the change in the reflection coefficient.

[0116] Although the embodiments of the present disclosure have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention.

[0117] REFERENCE SIGNS LIST 1 Sensor wire 1A Spiral-type sensor wire 1B Coil-type sensor wire 11 Wire assembly 11A Two-wire spiral wire 11B Two-wire coil wire 111 Hollow portion 12a First insulated wire 12a Second insulated wire 121 Conductor 122 Insulating coating 13 Support material 131 Shaft portion 2 Sensor device 21 Monitoring means 25 Terminating resistor 3 Wire harness 31 Target wire B Reference straight line C Contact material L Liquid

Claims

1. A sensor wire comprising a first insulated wire and a second insulated wire, each of which has a conductor and an insulating coating covering the outer circumference of the conductor, the first insulated wire and the second insulated wire are bent and assembled with their longitudinal axes aligned to form a wire assembly, and a pair of the first insulated wire and the second insulated wire is regarded as one unit, and a region is formed on a straight line that crosses the wire assembly in which multiple units of the first insulated wire and the second insulated wire are lined up alternately.

2. The sensor wire according to claim 1, wherein the first insulated wire and the second insulated wire are wound around a common central axis to form the wire assembly.

3. The sensor wire according to claim 1, wherein in the wire assembly, the first insulated wire and the second insulated wire are assembled in a planar shape.

4. The sensor wire according to claim 1, wherein in the wire assembly, the first insulated wire and the second insulated wire are wound in a spiral shape.

5. The sensor wire according to claim 1, wherein the first insulated wire and the second insulated wire are each configured as an enameled wire.

6. The sensor wire according to claim 1, further comprising a support member in contact with said wire assembly and supporting said wire assembly.

7. The sensor wire according to claim 6, wherein the support material has flexibility that allows it to deform in accordance with the deformation of the wire assembly.

8. The sensor wire according to claim 1, further comprising an intermediate material disposed in contact with the wire assembly, the intermediate material containing a substance that changes its dielectric constant in response to an environmental change in the area surrounding the wire assembly.

9. The sensor wire according to claim 8, wherein the change in the dielectric constant is caused by at least one of a phase transformation and a chemical change of the medium material.

10. A sensor device comprising: a sensor wire as claimed in any one of claims 1 to 9; and a monitoring means for inputting a differential signal to the first insulated wire and the second insulated wire constituting the sensor wire, acquiring a response signal, and monitoring changes in the response signal.

11. The sensor device according to claim 10, wherein the monitoring means determines that at least one of mechanical deformation, temperature change, and change in the material in contact with the sensor wire has been applied to the sensor wire when a change exceeding a reference value occurs in the response signal.

12. The sensor device according to claim 10, wherein the monitoring means monitors, as the response signal, a change in characteristic impedance or reflection coefficient between the first insulated wire and the second insulated wire constituting the sensor wire.

13. The sensor device according to claim 12, wherein the monitoring means measures the characteristic impedance or reflection coefficient by a time domain reflectometry or a frequency domain reflectometry.

14. The sensor device according to claim 10, wherein the wire assembly is impedance-matched with the monitoring means by adjusting the number of pairs of the first insulated wires and the second insulated wires arranged in the straight line.

15. A wire harness comprising: a target electric wire composed of at least one electric wire; and a sensor device as described in claim 10, wherein the sensor electric wire constituting the sensor device is arranged in at least a portion of the target electric wire along the longitudinal direction thereof.

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