Cable and damage detector

Abstract

To provide a cable capable of preventing a bending tendency while having a conductive tape for detecting a damage of the cable, and to provide a damage detector for detecting the damage of the cable.SOLUTION: A cable 1 includes: a wire bundle 10 twisting first to third wires 2-4 together; a press roll tape 5 wound spirally around an outer periphery of the wire bundle 10; a conductive tape 6 having electrical conductivity and wound spirally around an outer periphery of the press roll tape 5; and a sheath 8 coating the press roll tape 5 and the conductive tape 6. The conductive tape 6 is wound around the outer periphery of the press roll tape 5 so that one edge portion in a width direction does not overlap the other edge portion. A twisting direction of the first to third wires 2-4 in the wire bundle 10 is opposite to a spiral direction of the press roll tape 5, and the spiral direction of the press roll tape 5 is the same as a spiral direction of the conductive tape 6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a cable and a damage detection device for detecting damage to the cable.

Background Art

[0002] Conventionally, when damage occurs to a cable having a plurality of electric wires, a cable and a detection device capable of electrically detecting the occurrence of the damage are known (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a cable having an outer detection layer composed of a conductive tape on the outer periphery of a tape layer composed of a tape body wound around the outer periphery of a group of electric wires bundled together so as to be able to detect damage caused by trauma when a sudden impact is applied from the outside. The conductive tape is wound in a spiral shape around the group of electric wires with the group of electric wires as the center along the axial direction of the group of electric wires. The tape body forming the tape layer is made of an insulating material such as paper or resin. When a break occurs in the conductive tape, the characteristic impedance of the conductive tape changes, and this change in the characteristic impedance is detected by a detection device.

[0004] Further, in Patent Document 1, it is said that this cable can be suitably used for applications where the influence is great when an electric wire is disconnected, such as in an automobile brake system, and the significance of detecting the disconnection of the electric wire in advance is great.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] For example, a cable used for power supply and control of an electric parking brake device that locks the rotation of wheels when a vehicle stops or an electric brake device that brakes the rotation of wheels while the vehicle is running has a part of its longitudinal direction strung in the air inside the tire house. In this case, if the cable has a large bending tendency, there is a risk that wear and trauma may occur due to the cable coming into contact with components of the suspension device or the like. Note that the bending tendency of the cable is caused by, for example, twisting a plurality of electric wires together, and refers to the property that the cable naturally bends in a certain direction even when no external force is acting on the cable in its single state. For example, when a conductive tape or an insulating tape body is wound around the outer periphery of a group of electric wires as in the cable described in Patent Document 1, there is a possibility that the winding of this conductive tape or tape body may also cause a bending tendency in the cable.

[0007] Therefore, an object of the present invention is to provide a cable capable of suppressing a bending tendency while having a conductive tape for detecting damage to the cable, and a damage detection device for detecting damage to the cable.

Means for Solving the Problems

[0008] The present invention aims to solve the above problems, and includes an electric wire bundle formed by twisting a plurality of electric wires, a pressing tape spirally wound around the outer periphery of the electric wire bundle, a conductive conductive tape spirally wound around the outer periphery of the pressing tape, and a sheath covering the pressing tape and the conductive tape. The conductive tape is spirally wound around the outer periphery of the pressing tape so that one end and the other end in the width direction do not overlap, the twisting direction of the plurality of electric wires in the electric wire bundle is opposite to the spiral winding direction of the pressing tape, and the spiral winding direction of the pressing tape is the same as the spiral winding direction of the conductive tape. A cable is provided.

[0009] Also, the present invention aims to solve the above problems, and provides a damage detection device for detecting damage to the cable described above, which further includes a linear conductor electrically connected to the conductive tape at one terminal portion in the longitudinal direction of the cable. The damage detection device passes a current through the conductive tape and the linear conductor, and outputs a damage detection signal indicating that damage has occurred to the cable when the current is in a non-conductive state.

Effects of the Invention

[0010] According to the cable and the damage detection device of the present invention, it is possible to suppress the bending habit of the cable while having a conductive tape for detecting damage to the cable.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0012] [First Embodiment] FIG. 1 is a cross-sectional view of a cable 1 according to a first embodiment of the present invention. The cable 1 includes an electric wire bundle 10 formed by twisting a plurality of electric wires 2 to 4, a holding tape 5 spirally wound around the outer periphery of the electric wire bundle 10, a conductive conductive tape 6 spirally wound around the outer periphery of the holding tape 5, a linear conductor 7 and an inclusion 100 covered by the holding tape 5 together with the electric wire bundle 10, and a sheath 8 covering the holding tape 5 and the conductive tape 6.

[0013] In the present embodiment, among the plurality of electric wires 2 to 4, the first electric wire 2 and the second electric wire 3 are power supply lines for supplying an operating power source to a target device. The third electric wire 4 is a multi-core electric wire in which a pair of signal lines 41 and 42 are covered by an inner sheath 43. Further, in the present embodiment, one end of each of the first to third electric wires 2 to 4 of the cable 1 is connected to a spring lower member of the vehicle, and the other end of each of the first to third electric wires 2 to 4 is connected to a control device disposed on the vehicle body side, which is a spring upper member. The target device below the spring to which power is supplied by the first electric wire 2 and the second electric wire 3 is, for example, an electric parking brake device that locks the wheels when the vehicle stops. The pair of signal lines 41 and 42 of the third electric wire 4 are connected to, for example, a wheel speed sensor that detects the rotational speed of the wheel and transmits an output signal of the wheel speed sensor. The cable 1 is repeatedly bent at a part in the longitudinal direction as the suspension spring expands and contracts during the running of the vehicle.

[0014] The first electric wire 2 is an insulated coated wire in which a conductor 21 is coated with an insulator 22. The second electric wire 3 is an insulated coated wire in which a conductor 31 is coated with an insulator 32. The conductors 21 and 31 are stranded wires formed by stranding a plurality of strands 210 and 310 made of a highly conductive metal such as copper. The pair of signal wires 41 and 42 of the third electric wire 4 are each an insulated coated wire in which a conductor 411 or 421 is coated with an insulator 412 or 422. The conductors 411 and 421 are stranded wires formed by stranding a plurality of strands 410 and 420 made of a highly conductive metal such as copper. The insulators 22 and 32 of the first and second electric wires 2 and 3, and the insulators 412 and 422 of the pair of signal wires 41 and 42 of the third electric wire 4 are made of, for example, a fluororesin.

[0015] The signal wires 41 and 42 of the third electric wire 4 have an outer diameter smaller than those of the first electric wire 2 and the second electric wire 3, and the outer diameter of each of the signal wires 41 and 42 is not more than half of the outer diameter of the first electric wire 2 and the second electric wire 3. In the present embodiment, the wire bundle 10 is configured to have one multi-core electric wire (the third electric wire 4), but the plurality of electric wires constituting the wire bundle may include a plurality of multi-core electric wires. Further, the plurality of electric wires constituting the wire bundle may not include a multi-core electric wire.

[0016] FIG. 2 is a configuration diagram showing a state in which the inclusions 100 and the sheath 8 are omitted and the wire bundle 10, the pressing tape 5, the conductive tape 6, and the linear conductor 7 are viewed from the radial direction of the cable 1. In FIG. 2, the conductive tape 6 is shown in gray, the contour of the inner sheath 43 of the third electric wire 4 is shown by a virtual line (two-dot chain line) in a part of the longitudinal direction of the wire bundle 10, and the pair of signal wires 41 and 42 are shown by solid lines.

[0017] As shown in FIG. 2, the first to third electric wires 2 to 4 are twisted together, and the pair of signal wires 41 and 42 of the third electric wire 4 are further twisted inside the inner sheath 43 to form a twisted pair. In FIG. 1, the twisting direction of the first to third electric wires 2 to 4 is indicated by an arrow A 10It is shown by [description in Japanese], and the twisting direction of the pair of signal lines 41 and 42 in the third electric wire 4 is indicated by an arrow A4. As shown in FIGS. 1 and 2, in the present embodiment, the twisting directions of the first to third electric wires 2 to 4 as viewed in the longitudinal direction of the cable 1 and the twisting direction of the pair of signal lines 41 and 42 are the same.

[0018] Also, in FIG. 1, the twisting directions of the plurality of strands 210 in the conductor 21 of the first electric wire 2, the twisting directions of the plurality of strands 310 in the conductor 31 of the second electric wire 3, and the twisting directions of the plurality of strands 410 and 420 of the pair of signal lines 41 and 42 in the third electric wire 4 are respectively indicated by arrows A 21 , A 31 , A 41 , A 42 . These twisting directions of the strands 210, 310, 410, and 420 are the same as the twisting directions of the first to third electric wires 2 to 4 and the twisting direction of the pair of signal lines 41 and 42. As a result, the twists of the first to third electric wires 2 to 4 are less likely to unwind.

[0019] The inclusion 100 is made of a fibrous body such as aramid fiber or Kevlar (registered trademark), and is disposed intervening between the first to third electric wires 2 to 4 and the holding tape 5. Due to this inclusion 100, the shape of the holding tape 5 in a cross section perpendicular to the longitudinal direction of the cable 1 is close to a circular shape. That is, the shape of the holding tape 5 in a cross section perpendicular to the longitudinal direction of the wire bundle 10 is circularized by the inclusion 100. As a result, the cable 1 can be flexibly bent in all directions.

[0020] The outer diameter of the first electric wire 2 and the outer diameter of the second electric wire 3 are the same. Also, the outer diameter of the third electric wire 4 is approximately the same as the outer diameter of the first electric wire 2 and the outer diameter of the second electric wire 3. Specifically, the outer diameter of the third electric wire 4 is 95% or more and 105% or less of the outer diameter of the first electric wire 2 and the second electric wire 3. This dimensional relationship contributes to circularizing the shape of the holding tape 5 in a cross section perpendicular to the longitudinal direction of the wire bundle 10.

[0021] In the example shown in FIG. 1, in the vicinity of the center of the cable 1, a part of the outer peripheral surfaces 2a, 3a, and 4a of the first to third electric wires 2 to 4 are in contact with each other, and a part of the outer peripheral surfaces 2a, 3a, and 4a of the first to third electric wires 2 to 4 are in contact with one surface 5a of the holding tape 5. However, the outer peripheral surfaces 2a, 3a, and 4a of the first to third electric wires 2 to 4 do not necessarily have to be in contact with each other, and the outer peripheral surfaces 2a, 3a, and 4a of the first to third electric wires 2 to 4 do not necessarily have to be in contact with the holding tape 5.

[0022] In FIG. 2, the inclination angle of the holding tape 5 with respect to the longitudinal direction of the cable 1 is indicated by θ1, and the inclination angle of the conductive tape 6 with respect to the longitudinal direction of the cable 1 is indicated by θ2. Also, the spiral winding pitch of the holding tape 5 in the longitudinal direction of the cable 1 is indicated by P1, and the spiral winding pitch of the conductive tape 6 in the longitudinal direction of the cable 1 is indicated by P2. Here, the spiral winding pitch means the length that the holding tape 5 and the conductive tape 6 advance in the longitudinal direction of the wire bundle 10 while making one round around the outer periphery of the wire bundle 10 when the holding tape 5 and the conductive tape 6 are wound around the outer periphery of the wire bundle 10.

[0023] As shown in FIG. 2, the inclination angle θ2 of the conductive tape 6 with respect to the longitudinal direction of the cable 1 is larger than the inclination angle θ1 of the holding tape 5, and the spiral winding pitch P2 of the conductive tape 6 in the longitudinal direction of the cable 1 is narrower than the spiral winding pitch P1 of the holding tape 5.

[0024] FIG. 3 is a perspective view showing the holding tape 5 and the conductive tape 6 alone. FIG. 4 is a cross-sectional view showing the holding tape 5 wound in a spiral shape and the conductive tape 6 wound around the outer periphery thereof.

[0025] The conductive tape 6 is a strip having conductivity. In the present embodiment, the conductive tape 6 is a strip-shaped metal foil made of a highly conductive metal such as copper, silver, or aluminum. One surface 6a of the conductive tape 6 is in contact with the other surface 5b of the holding tape 5 and is wound around the outer periphery of the holding tape 5. One surface 6a of the conductive tape 6 is provided with adhesiveness by an adhesive and adheres to the other surface 5b of the holding tape 5. The other surface 6b of the conductive tape 6 is in contact with the sheath 8. Note that if the positional displacement of the conductive tape 6 in the longitudinal direction of the cable 1 can be sufficiently suppressed by the frictional force with the holding tape 5 or the sheath 8 and the one end and the other end in the width direction of the conductive tape 6 of different turns can be prevented from coming into contact with each other, adhesiveness does not have to be provided on one surface 6a of the conductive tape 6.

[0026] In FIG. 3, the width of the holding tape 5 is indicated by W1, and the width of the conductive tape 6 is indicated by W2. The width W1 of the holding tape 5 is wider than the width W2 of the conductive tape 6, and a desirable range of the width W2 of the conductive tape 6 with respect to the width W1 of the holding tape 5 is, for example, 10% or more and 30% or less. Also, in the present embodiment, the thickness of the conductive tape 6 is thinner than the thickness of the holding tape 5. However, the present invention is not limited to this, and the conductive tape 6 may be thicker than the holding tape 5. The narrower the width and the thinner the thickness of the conductive tape 6, the higher the sensitivity when the cable 1 is damaged. On the other hand, for example, wear and kinking are likely to occur due to friction with the sheath 8 when the cable 1 is bent. Therefore, it is desirable to appropriately adjust the width and thickness of the conductive tape 6 according to the use and the usage environment of the cable 1.

[0027] The pressing tape 5 is a strip made of, for example, a resin such as non-woven fabric, paper, or polyester, and is wound around the first to third electric wires 2 to 4 so as to press them toward the center of the cable 1. Further, the pressing tape 5 is wound around the outer periphery of the wire bundle 10 so that the end portions in the width direction overlap each other in the radial direction of the cable 1. More specifically, one surface 5a of the end portion on one side in the width direction of the pressing tape 5 and the other surface 5b of the end portion on the other side in the width direction of the pressing tape 5 overlap and contact each other in the thickness direction of the pressing tape 5. In the longitudinal direction of the cable 1 (the left-right direction in FIG. 4), the ratio of the overlapping length L2 of the pressing tape 5 to the length L1 of the pressing tape 5 for one turn is, for example, 10% or more and 40% or less.

[0028] The conductive tape 6 is roughly wound around the outer periphery of the pressing tape 5 so that one end portion and the other end portion in the width direction do not overlap. A gap is formed between one end portion and the other end portion in the width direction of the conductive tape 6, through which the other surface 5b of the pressing tape 5 is exposed. The sheath 8 contacts one surface 5a of the pressing tape 5 in this gap.

[0029] The sheath 8 is made of, for example, a urethane resin such as thermoplastic polyurethane, and is extrusion-molded around the outer periphery of the pressing tape 5. The pressing tape 5 covers the entire circumference of the wire bundle 10 in a cross-sectional view. This prevents the liquid thermoplastic resin forming the sheath 8 from entering between the first to third electric wires 2 to 4 during the molding of the sheath 8.

[0030] In FIG. 1, the spiral winding direction of the pressing tape 5 is indicated by an arrow A5, and the spiral winding direction of the conductive tape 6 is indicated by an arrow A6. As shown in FIG. 1, when the wire bundle 10, the pressing tape 5, and the conductive tape 6 are viewed in the longitudinal direction of the cable 1 from a cross-section perpendicular to the longitudinal direction of the cable 1, the twisting direction of the first to third electric wires 2 to 4 in the wire bundle 10 is opposite to the spiral winding directions of the pressing tape 5 and the conductive tape 6. Also, the spiral winding direction of the pressing tape 5 is the same as the spiral winding direction of the conductive tape 6.

[0031] As described above, the cable 1 configured as such may be damaged, for example, by a flying stone or the like hitting it during the running of a vehicle, or the sheath 8 may be severely worn due to friction with the outside. In the present embodiment, when the cable 1 is damaged due to such trauma or wear, the occurrence of the damage is detected by a damage detection device described below.

[0032] FIG. 5(a) is a circuit diagram showing a configuration example of a damage detection device 11 for detecting damage to the cable 1. FIG. 5(b) is a cross-sectional view showing a configuration example of the linear conductor 7. The damage detection device 11 includes a conductive tape 6 and a linear conductor 7 as components, and has a damage detection circuit 110 that electrically detects the occurrence of damage in the cable 1.

[0033] As shown in FIG. 5(b), the linear conductor 7 is an insulated wire having a conductor 71 and an insulator 72 covering the conductor 71. In the example shown in FIG. 5(b), the conductor 71 is a stranded wire formed by twisting a plurality of strands 710, but it is not limited to this, and the conductor 71 may be a single wire. Further, the insulator 72 may be omitted, and the linear conductor 7 may be an uncoated wire (bare wire).

[0034] The linear conductor 7 is disposed inside the holding tape 5 together with the first to third electric wires 2 to 4, and the conductor 71 of the linear conductor 7 is electrically connected to the conductive tape 6 at one end portion in the longitudinal direction of the cable 1. In the present embodiment, this end portion corresponds to the end portion below the spring of the vehicle. In the example shown in FIG. 5(a), the case where the conductive tape 6 and the linear conductor 7 are connected by a termination resistor Rt is shown, but it is not limited to this, and the conductor 71 of the linear conductor 7 may be directly connected to the conductive tape 6 to short-circuit them.

[0035] The linear conductor 7 has lower bending durability than the first to third electric wires 2 to 4, and when the cable 1 is repeatedly bent, it breaks before any of the first to third electric wires 2 to 4 breaks. Further, the conductor cross-sectional area of the conductor 71 of the linear conductor 7 is smaller than the conductor cross-sectional area of the conductor 21 of the first electric wire 2, the conductor cross-sectional area of the conductor 31 of the second electric wire 3, and the conductor cross-sectional areas of the conductor 411 and 421 of the signal lines 41 and 42 of the third electric wire 4, respectively.

[0036] In the present embodiment, as shown in FIG. 1, the linear conductor 7 is disposed between the first electric wire 2 and the second electric wire 3 and the pressing tape 5. However, the arrangement position of the linear conductor 7 is not limited to this, and for example, the linear conductor 7 may be disposed at the center of the cable 1 surrounded by the first to third electric wires 2 to 4. The linear conductor 7 may be separated from the wire bundle 10 or may be in contact with the wire bundle 10 as shown in FIG. 1.

[0037] The damage detection circuit 110 is provided on the side opposite to the side where the conductive tape 6 and the conductor 71 of the linear conductor 7 are electrically connected in the longitudinal direction of the cable 1 (the upper side of the spring). A current is passed through the conductive tape 6 and the linear conductor 7, and when this current is in a non-conducting state, a damage detection signal indicating that damage has occurred in the cable 1 is output. When the damage detection signal is output, for example, the occurrence of damage to the cable 1 is notified to the driver by the lighting of a lamp on the instrument panel of the vehicle.

[0038] In the circuit configuration example of the damage detection circuit 110 shown in FIG. 5(a), a shunt resistor Rs, a conductive tape 6, a termination resistor Rt, and a linear conductor 7 are connected in series between the + side and the - side of the DC power supply V. Further, the damage detection circuit 110 has first and second reference resistors Ra and Rb connected in series between the + side and the - side of the DC power supply V, and a comparator C. A reference voltage Vref, which is a voltage obtained by resistively dividing the voltage of the DC power supply V by the first and second reference resistors Ra and Rb, and a detection voltage Vd, which is the voltage on the conductive tape 6 side of the shunt resistor Rs, are input to the comparator C.

[0039] When there is no disconnection in either the conductive tape 6 or the conductor 71 of the linear conductor 7, and a predetermined current is flowing through the series circuit composed of the shunt resistor Rs, the conductive tape 6, the terminal resistor Rt, and the linear conductor 7, a voltage drop corresponding to the magnitude of the current occurs across the shunt resistor Rs, and the detected voltage Vd becomes lower than the voltage of the DC power supply V. On the other hand, when there is a disconnection in either the conductive tape 6 or the conductor 71 of the linear conductor 7, no current flows through this series circuit, and the detected voltage Vd becomes equal to the voltage of the DC power supply V.

[0040] The reference voltage Vref is adjusted to be a value between the detected voltage Vd when there is no disconnection in the conductor 71 of the conductive tape 6 and the linear conductor 7, and the detected voltage Vd when there is a disconnection in either the conductive tape 6 or the conductor 71 of the linear conductor 7. When there is a disconnection in either the conductive tape 6 or the conductor 71 of the linear conductor 7, the output voltage Vout of the comparator C changes. The output voltage Vout of the comparator C is output from the damage detection circuit 110 as a damage detection signal indicating that damage has occurred in the cable 1.

[0041] [Comparative Example] FIG. 6 is a cross-sectional view showing a cable 1A according to a comparative example. In FIG. 6, for the components common to the components of the cable 1 according to the first embodiment, the same reference numerals as those given in FIGS. 1 and the like are used, and the overlapping description is omitted.

[0042] In the cable 1A, the shape of the holding tape 5 in a cross-section perpendicular to the longitudinal direction is a triangular shape with rounded corners. That is, at each corner of this triangular shape, the holding tape 5 curves along the outer peripheral surfaces 2a, 3a, and 4a of the first electric wire 2, the second electric wire 3, and the third electric wire 4 with the curvature of these outer peripheral surfaces 2a, 3a, 4a.

[0043] In this cable 1A, compared with the cable 1 according to the first embodiment, the conductive tape 6 is subjected to stress due to being bent with a large curvature at each of the above-mentioned triangular corners, and this stress makes the conductive tape 6 liable to break, and false detection of damage is likely to occur. On the other hand, in the cable 1 according to the first embodiment, the shape of the pressing tape 5 in a cross-section perpendicular to the longitudinal direction of the wire bundle 10 is circularized, and the curvature of the pressing tape 5 is smaller than the curvatures of the outer peripheral surfaces 2a, 3a, and 4a of the first to third wires 2 to 4. Therefore, it is difficult for bending stress to occur in the conductive tape 6 wound around the outer periphery of the pressing tape 5, and the occurrence of false detection can be suppressed.

[0044] (Effect of the First Embodiment) According to the first embodiment described above, since the twisting direction of the first to third wires 2 to 4 in the wire bundle 10 is opposite to the spiral winding direction of the pressing tape 5 and the conductive tape 6, the kink of the cable 1 caused by the twisting of the first to third wires 2 to 4 cancels out the kink of the cable 1 caused by the spiral winding of the pressing tape 5 and the conductive tape 6, and the kink of the cable 1 as a whole is suppressed.

[0045] Also, according to the first embodiment, since the spiral winding pitch of the conductive tape 6 is narrower than the spiral winding pitch of the pressing tape 5, for example, compared with the case where the conductive tape 6 is spiral wound with the spiral winding pitch P1 of the pressing tape 5 shown in FIG. 2, the number of turns of the conductive tape 6 per unit length in the longitudinal direction of the cable 1 increases, and even if the size of the damage is small when an injury occurs in the sheath 8, it is possible to detect the occurrence of the damage.

[0046] Also, in the first embodiment, since the width of the pressing tape 5 is wider than the width of the conductive tape 6 and the inclination angle of the pressing tape 5 with respect to the longitudinal direction of the cable 1 is smaller than the inclination angle of the conductive tape 6, for example, when the pressing tape 5 is spirally wound at the inclination angle θ2 of the conductive tape 6 shown in FIG. 2, the number of turns of the pressing tape 5 per unit length of the cable 1 can be reduced as compared with the case where the pressing tape 5 is spirally wound, and it becomes possible to reduce the man-hours in manufacturing the cable 1. That is, in the first embodiment, by making the spiral winding pitch of the conductive tape 6 narrower than the spiral winding pitch of the pressing tape 5 and making the width of the pressing tape 5 wider than the width of the conductive tape 6, both an improvement in the sensitivity to damage to the cable 1 and a suppression of the manufacturing cost are achieved. When overlapping and winding a strip-like body such as the pressing tape 5, there is a correlation between the width and the inclination angle of the strip-like body. When the width is widened, the inclination angle becomes smaller, and when the width is narrowed, the inclination angle becomes larger.

[0047] Further, according to the first embodiment, since the linear conductor 7 has lower bending durability than the first to third electric wires 2 to 4, even when the linear conductor 7 is broken, the occurrence of the break is detected by the damage detection circuit 110. Therefore, in addition to sudden trauma caused by the collision of a flying stone or the like and the wear of the sheath 8, it is possible to detect the sign of breakage of the first to third electric wires 2 to 4 due to metal fatigue caused by repeated bending by the breakage of the linear conductor 7.

[0048] [Modification Example of the First Embodiment] FIG. 7(a) is a perspective view showing the conductive tape 6A according to a modification example of the first embodiment alone. FIG. 7(b) is a cross-sectional view of the conductive tape 6A in a cross-section perpendicular to the longitudinal direction of the conductive tape 6A. In FIGS. 7(a) and 7(b), for clarity of explanation, the thickness of the conductive tape 6A is exaggeratedly shown.

[0049] The conductive tape 6A has a base material 61 made of a strip-shaped insulator and a conductive layer 62 provided on one surface 61a side of the base material 61. The conductive layer 62 is reinforced by the base material 61 and is not easily broken even when repeatedly bent. In this example, a strip-shaped conductive layer 62 is joined to one surface 61a of the base material 61 via an adhesive layer 63. An adhesive layer 64 is provided on the other surface 61b of the base material 61. Note that the conductive layer 62 may be formed on one surface 61a of the base material 61 by vapor deposition.

[0050] The conductive tape 6A replaces the conductive tape 6 of the first embodiment, and like the conductive tape 6, it is spirally wound around the outer periphery of the holding tape 5. When winding the conductive tape 6A, it may be wound so that the conductive layer 62 is on the outer side (sheath 8 side) of the base material 61, or it may be wound so that the conductive layer 62 is on the inner side (holding tape 5 side) of the base material 61. If the conductive layer 62 is on the outer side of the base material 61, damage to the cable 1 can be detected with high sensitivity. Also, if the conductive layer 62 is on the inner side of the base material 61, it is possible to prevent the conductive layer 62 from being worn due to friction with the sheath 8. Note that in order to prevent displacement of the conductive tape 6A, it is preferable to provide an adhesive layer on the surface of the conductive tape 6A on the holding tape 5 side.

[0051] When using this conductive tape 6A, in order for the damage detection device 11 to detect a disconnection of the conductive layer 62, a shunt resistor Rs, the conductive layer 62 of the conductive tape 6A, a terminal resistor Rt, and a linear conductor 7 are connected in series between the + side and the - side of the DC power supply V of the damage detection circuit 110.

[0052] Even when the conductive tape 6A according to this modification is used, the same effects as those of the first embodiment can be obtained. Note that the conductive layer 62 may be provided only on one surface 61a side of the base material 61 as shown in FIGS. 7(a) and 7(b), or the conductive layer 62 may be provided on both one surface 61a side and the other surface 61b side of the base material 61. In this case, at the terminal portion in the longitudinal direction of the conductive tape 6A, the conductive layer 62 on one surface 61a side of the base material 61 and the conductive layer 62 on the other surface 61b side are electrically connected, and one of the two conductive layers 62 is used as the forward path of the current supplied from the damage detection circuit 110, and the other is used as the return path of this current, so that the linear conductor 7 can be omitted.

[0053] [Second Embodiment] FIG. 8(a) is a cross-sectional view showing a cable 1B according to the second embodiment of the present invention. The cable 1B according to the second embodiment is obtained by adding a fragile wire 9 having lower bending durability and being more likely to break than the first to third electric wires 2 to 4 to the cable 1 according to the first embodiment. The fragile wire 9 is disposed at the center of the cable 1B surrounded by the first to third electric wires 2 to 4 and extends in the longitudinal direction of the cable 1B.

[0054] FIG. 8(b) is a cross-sectional view of the fragile wire 9. The fragile wire 9 is an insulated wire having a conductor 91 and an insulator 92 covering the conductor 91. The conductor 91 is a stranded wire formed by twisting a plurality of strands 910, but is not limited thereto, and the conductor 91 may be a single wire. Further, the insulator 92 may be omitted and the fragile wire 9 may be a non-insulated wire (bare wire).

[0055] The fragile wire 9 is used to detect a sign before any of the first to third electric wires 2 to 4 breaks due to repeated bending of the cable 1B. That is, in the present embodiment, the occurrence of sudden trauma such as a flying stone or damage such as wear of the sheath 8 is detected by the disconnection of the conductive tape 6, and the sign of disconnection due to metal fatigue of the conductors 21, 31, 411, 421 of the first to third electric wires 2 to 4 is detected by the disconnection of the fragile wire 9. The conductor thickness of the conductive tape 6 is formed thinner than the conductor diameter of the conductor 91 of the fragile wire 9. Thereby, wear and trauma of the sheath 8 can be detected sensitively.

[0056] In addition, in cable 1B, instead of conductive tape 6, conductive tape 6A shown in FIGS. 7(a) and (b) may be used. In this case, the thickness of the conductive layer 62 of the conductive tape 6A is formed thinner than the conductor diameter of the conductor 91 of the fragile line 9.

[0057] FIG. 2 is a circuit diagram showing a configuration example of the damage detection device 12 according to the third embodiment. The damage detection device 12 includes the conductive tape 6, the fragile line 9, and the linear conductor 7 of the cable 1B as components, and is configured to have a damage detection circuit 120. The damage detection circuit 120 has a first circuit portion 121 for detecting a disconnection of the conductive tape 6 and a second circuit portion 122 for detecting a disconnection of the conductor 91 of the fragile line 9.

[0058] The first circuit portion 121 of the damage detection circuit 120 includes reference resistors Ra1 and Rb1 that divide the voltage of the DC power supply V to generate a reference voltage Vref1, a shunt resistor Rs1, and a comparator C1 that compares the detection voltage Vd1, which is the voltage on the conductive tape 6 side of the shunt resistor Rs1, with the reference voltage Vref1. When a disconnection occurs in the conductive tape 6, the output voltage Vout1 of the comparator C1 changes. The conductive tape 6 and the linear conductor 7 are electrically connected by a first terminal resistor Rt1 at the longitudinal terminal portion of the cable 1B corresponding to the end opposite to the damage detection circuit 120.

[0059] The second circuit portion 122 of the damage detection circuit 120 includes reference resistors Ra2 and Rb2 that divide the voltage of the DC power supply V to generate a reference voltage Vref2, a shunt resistor Rs2, and a comparator C2 that compares the detection voltage Vd2, which is the voltage on the fragile line 9 side of the shunt resistor Rs2, with the reference voltage Vref2. When a disconnection occurs in the conductor 91 of the fragile line 9, the output voltage Vout2 of the comparator C2 changes. The conductor 91 of the fragile line 9 and the linear conductor 7 are electrically connected by a second terminal resistor Rt2 at the longitudinal terminal portion of the cable 1B corresponding to the end opposite to the damage detection circuit 120.

[0060] The output voltage Vout1 of the comparator C1 in the first circuit section 121 is output from the damage detection circuit 120 as a damage detection signal indicating that damage has occurred in the cable 1B. The output voltage Vout2 of the comparator C2 in the second circuit section 122 is output from the damage detection circuit 120 as a prediction detection signal indicating that there is a sign of disconnection in the first to third electric wires 2 to 4 of the cable 1B. When the damage detection signal or the prediction detection signal is output, the driver is notified, for example, by the lighting of a lamp on the instrument panel of the vehicle.

[0061] According to this second embodiment, it is possible to reduce the occurrence of detection omission and misdetection while suppressing an increase in man-hours during manufacturing, and it is possible to detect a sign of disconnection due to metal fatigue of the conductors 21, 31, 411, 421 of the first to third electric wires 2 to 4 by the fragile wire 9. In the first embodiment, the linear conductor 7 has lower bending durability than the first to third electric wires 2 to 4. However, in the second embodiment, since a sign of disconnection of the first to third electric wires 2 to 4 can be detected by the fragile wire 9, the bending durability of the linear conductor 7 does not necessarily have to be lower than that of the first to third electric wires 2 to 4. Further, the fragile wire 9 does not necessarily have to be arranged at the center of the cable 1B, and the fragile wire 9 may be arranged between the first to third electric wires 2 to 4 and the pressing tape 5. In this case, the fragile wire 9 is twisted together with the first to third electric wires 2 to 4 and the linear conductor 7.

[0062] (Summary of Embodiments) Next, the technical idea grasped from each of the above-described embodiments and modification examples will be described by referring to the reference numerals and the like in the embodiments and modification examples. However, each reference numeral in the following description is not limited to the members that specifically show the components in the claims in the embodiments.

[0063] [1] A cable (1, 1B) comprising: a wire bundle (10) formed by twisting a plurality of electric wires (2 - 4); a holding tape (5) spirally wound around the outer periphery of the wire bundle (10); a conductive tape (6, 6A) spirally wound around the outer periphery of the holding tape (5); and a sheath (8) covering the holding tape (5) and the conductive tape (6, 6A), wherein the conductive tape (6, 6A) is spirally wound around the outer periphery of the holding tape (5) such that one end and the other end in the width direction do not overlap, the twisting direction of the plurality of electric wires (2 - 4) in the wire bundle (10) is opposite to the spiral winding direction of the holding tape (5), and the spiral winding direction of the holding tape (5) is the same as the spiral winding direction of the conductive tape (6).

[0064] [2] The cable (1, 1B) according to [1] above, wherein the spiral winding pitch (P2) of the conductive tape (6, 6A) is narrower than the spiral winding pitch (P1) of the holding tape (5).

[0065] [3] The cable (1, 1B) according to [1] above, wherein the width (W1) of the holding tape (5) is wider than the width (W2) of the conductive tape (6, 6A).

[0066] [4] Further comprising a linear conductor (7) electrically connected to the conductive tape (6, 6A) at one terminal portion in the cable longitudinal direction, and the linear conductor (7) is arranged inside the holding tape (5) together with the plurality of electric wires (2 - 4). The cable (1, 1B) according to any one of [1] to [3] above.

[0067] [5] A damage detection device (11, 12) for detecting damage to the cable (1, 1B) according to [4] above, which passes a current through the conductive tape (6, 6A) and the linear conductor (7), and outputs a damage detection signal indicating that the cable (1, 1B) has been damaged when the current is in a non - conducting state.

[0068] The embodiments and modifications of the present invention have been described above. However, the above embodiments and modifications do not limit the invention according to the claims. Also, it should be noted that not all combinations of features described in the embodiments and modifications are essential means for solving the problems of the invention. Further, the present invention can be appropriately modified and implemented without departing from its gist. For example, it can be modified and implemented as follows.

[0069] In the above embodiment, the case where the third wire 4, which is a multi-core wire, has a plurality of signal wires 41 and 42 as small-diameter wires has been described. However, the plurality of small-diameter wires constituting the multi-core wire may be used as power supply wires for supplying operating power to the target device. Examples of the target device include an active suspension device with variable damping force and a pneumatic pressure detection device for detecting the pneumatic pressure of a tire.

[0070] Also, in the above embodiment, the case where the first and second wires 2 and 3 are used as power supply wires for supplying operating power to the electric parking brake device and the signal wires 41 and 42 of the third wire 4 are used for transmitting the output signal of the wheel speed sensor has been described. However, the uses of the first to third wires 2 to 4 are not limited to this. For example, the first wire 2 and the second wire 3 may be used as power supply wires for supplying operating power to an electric brake device that brakes the rotation of the wheels during vehicle travel, and the signal wires 41 and 42 of the third wire 4 may be used for transmitting a control signal for controlling the electric brake device.

[0071] Also, in the above embodiment, the case where three wires (the first to third wires 2 to 4) are bundled to form the wire harness 10 has been described. However, it is not limited to this, and the number of wires may be 2 or 4 or more.

[0072] Also, in the above embodiment, the case where a direct current is always passed through the conductive tapes 6 and 6A to detect the disconnection of the conductive tapes 6 and 6A has been described. However, it is not limited to this. For example, a current may be intermittently passed through the conductive tapes 6 and 6A to detect the disconnection of the conductive tapes 6 and 6A.

[0073] In addition, in the above-described embodiment, the case where the cable 1 is mounted on a vehicle has been described. However, the present invention is not limited to this, and the cable 1 may be used for industrial machines such as robots and machine tools.

Explanation of Reference Numerals

[0074] 1, 1B... Cable 10... Wire harness 11, 12... Damage detection device 2... First electric wire 3... Second electric wire 4... Third electric wire 5... Pressing tape 6, 6A... Conductive tape 7... Linear conductor 8... Sheath

Claims

1. A cable bundle formed by twisting a plurality of electric wires, a pressing tape spirally wound around the outer periphery of the cable bundle, a conductive tape spirally wound around the outer periphery of the pressing tape, and a sheath covering the pressing tape and the conductive tape, wherein the conductive tape is spirally wound around the outer periphery of the pressing tape so that one end and the other end in the width direction do not overlap each other, wherein the twisting direction of the plurality of electric wires in the cable bundle is opposite to the spiral winding direction of the pressing tape, and the spiral winding direction of the pressing tape is the same as the spiral winding direction of the conductive tape, a cable.

2. The cable according to Claim 1, wherein the spiral winding pitch of the conductive tape is narrower than the spiral winding pitch of the pressing tape.

3. The cable according to Claim 1, wherein the width of the pressing tape is wider than the width of the conductive tape.

4. The cable according to Claim 1, further comprising a linear conductor electrically connected to the conductive tape at one terminal portion in the longitudinal direction of the cable, wherein the linear conductor is disposed inside the pressing tape together with the plurality of electric wires.

5. A damage detection device for detecting damage to the cable according to Claim 4, wherein a current is passed through the conductive tape and the linear conductor, and a damage detection signal indicating that damage has occurred to the cable is output when the current is in a non-conductive state.

6. A damage detection device for detecting damage to the cable according to Claim 4, wherein a current is passed through the conductive tape and the linear conductor, and a damage detection signal indicating that damage has occurred to the cable is output when the current is in a non-conductive state. A damage detection device.

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