JP5215037B2 - Shield member abnormality detection method and shield member abnormality detection device - Google Patents

Description

  The present invention relates to a shield member abnormality detection method and apparatus, and more particularly to a conductive core wire, an internal insulator covering the core wire, a shield member wound around an outer periphery of the internal insulator, and the shield The present invention relates to a shield member abnormality detection method and apparatus for detecting abnormality of the shield member in an electric wire having an external insulator covering the member.

  A CV cable 10 for supplying high-voltage power as shown in FIG. 1 is known as the electric wire described above. As shown in the figure, the CV cable 10 includes a core wire 11, an insulator 12 as an internal insulator, a copper tape 13 as a shield member, and a sheath 14 as an external insulator.

  The core wire 11 is made of a conductive conductor. The insulator 12 is made of crosslinked polyethylene or the like and covers the core wire 11. The copper tape 13 is provided to prevent noise from entering from the outside. The copper tape 13 is provided in a tape shape and is wound around the outer periphery of the insulator 12. The sheath 14 is made of polyethylene or the like and covers the copper tape 13.

  In the CV cable 10 described above, the copper tape 13 may be displaced due to laying conditions or secular changes. Due to this deviation, an abnormal portion that is not covered with the copper tape 13 may occur in the core wire 11 depending on the location. Thereby, there existed a problem that the performance quality of the CV cable 10 deteriorated.

  Conventionally, methods using X-ray imaging have been proposed to detect the displacement of the copper tape 13 (for example, Patent Documents 1 to 4). However, an apparatus capable of X-ray imaging has a problem that the apparatus itself is large and expensive, and qualification is required for imaging, so that versatility is low.

Therefore, the present applicant has proposed a shield member abnormality detection device having a configuration in which the CV cable 10 is sandwiched between a transmission antenna that transmits radio waves and a reception antenna that receives radio waves (Patent Documents 5 and 6). This abnormality detection device for the shield member detects the displacement of the copper tape 13 by the variation in the reception level of the receiving antenna depending on the presence or absence of the copper tape 13. However, this abnormality detection device for the shield member requires two antennas, a transmission antenna and a reception antenna, and has a problem in cost and size.
Japanese Patent Publication No. 6-81396 Japanese Examined Patent Publication No. 7-21468 JP-A-6-207826 Japanese Patent Laid-Open No. 5-26647 Japanese Patent Application No. 2006-254559 Japanese Patent Application No. 2007-200583

  Accordingly, the present invention focuses on the above problems and provides an apparatus for detecting an abnormality of a shield member that reduces the cost and size by detecting the displacement of the copper tape with only one antenna. And

  The invention according to claim 1, which has been made to solve the above-mentioned problems, includes a conductive core wire, an internal insulator covering the core wire, a shield member wound around an outer periphery of the internal insulator, and the shield member In an abnormality detection method for a shield member that detects an abnormality of the shield member in an electric wire having an external insulator that covers the outer surface of the electric wire, the normal portion where the shield member is located is scanned so that the shield member can be scanned along the electric wire. And placing the antenna so that the antenna impedance changes when scanning an abnormal part without the shield member, oscillating an oscillator and inputting radio waves to the antenna, An abnormality of the shield member is detected based on a reflected wave from the antenna toward the oscillator among the radio waves on the feeding path between the oscillators. It is carried out and steps, sequentially resides in the abnormality detecting method of the shield member, wherein.

  The invention according to claim 2 includes a conductive core wire, an internal insulator that covers the core wire, a shield member that is wound around an outer periphery of the internal insulator, and an external insulator that covers the shield member. In an abnormality detection device for a shield member that detects an abnormality of the shield member in an electric wire, an abnormal part that does not have the shield member and when the normal part with the shield member is scanned so that scanning can be performed along the electric wire. An antenna disposed so that the antenna impedance changes when scanned, an oscillator that inputs radio waves to the antenna, and radio waves on the feeding path between the antenna and the oscillator, from the antenna to the oscillator An abnormality detecting means for detecting an abnormality of the shield member based on a reflected wave traveling to the seal. It lies in the abnormality detecting apparatus member.

  According to a third aspect of the present invention, the abnormality detecting unit separately generates a traveling wave from the oscillator to the antenna and a reflected wave from the antenna to the oscillator among radio waves transmitted on the feeding path between the oscillator and the antenna. And detecting the abnormality of the shield member on the basis of the ratio of the separately detected reflected wave and traveling wave. It exists in the abnormality detection apparatus of the shield member of Claim 2.

  According to a fourth aspect of the present invention, there is provided the shield member abnormality detecting device according to the second or third aspect, wherein the antenna is bent along the outer periphery of the shield member.

  According to a fifth aspect of the present invention, the level of the antenna reflected wave reflected by the antenna is increased by interference with the electric wire reflected wave received by the antenna reflected by the shield member and reflected by the antenna. The distance between the antenna and the wire, the reflection characteristic of the antenna, the frequency of the oscillator, so that the level of the reflected wave of the antenna is lowered by interference with the reflected wire reflected by the core wire and received by the antenna. 5. The shield member abnormality detecting device according to claim 1, wherein at least one of the two is adjusted and provided.

  The invention according to claim 6 is provided with the antenna having directivity or gain such that the level of the reflected wave of the antenna and the level of the reflected wave of the electric wire are the same, or the reflected wave of the antenna It is characterized in that at least one of the distance between the antenna and the electric wire, the reflection characteristic of the antenna, and the frequency of the oscillator is adjusted so that the level and the level of the electric wave reflected wave are the same. The present invention resides in the abnormality detection device for a shield member according to claim 5.

  As described above, according to the first and second aspects of the invention, when scanning a normal part with a shield member, the antenna impedance decreases and the reflected wave increases, and when an abnormal part without a shield member is scanned. Since the reflected wave can be kept small without lowering the antenna impedance, an abnormality (deviation) of the shield member can be detected based on the reflected wave. Accordingly, it is possible to detect an abnormality (displacement) of the shield member with only one antenna, and it is possible to provide an abnormality detection device for the shield member that is reduced in cost and size.

  According to the invention described in claim 3, since the abnormality detecting means is set to detect the abnormality of the shield member based on the ratio of the reflected wave and the traveling wave detected separately, the fluctuation of the traveling wave The abnormality of the shield member can be accurately detected without depending on the above.

  According to the invention of claim 4, the antenna can be brought close to the shield member. Thereby, the change of the antenna impedance due to the presence or absence of the shield member can be increased, and the abnormality of the shield member can be detected more accurately.

  According to the fifth aspect of the present invention, the fluctuation of the reflected wave due to the presence or absence of the shield member can be increased, and the abnormality of the shield member can be detected more accurately.

  According to the sixth aspect of the present invention, the fluctuation of the reflected wave due to the presence or absence of the shield member can be easily increased, and the abnormality of the shield member can be detected more accurately.

1st Embodiment Next, the abnormality detection apparatus of the copper tape (shield member) of this invention in 1st Embodiment is demonstrated with reference to FIGS. The abnormality detection device 20 is a device that detects an abnormality of the copper tape 13 by scanning the dipole antenna AT1 as one antenna in the longitudinal direction of the CV cable 10, for example. As described in the background art, the CV cable 10 includes a core wire 11, an insulator 12 as an internal insulator, a copper tape 13 as a shield member, and a sheath as an external insulator, as shown in FIG. 14.

  The core wire 11 is made of a conductive conductor. The insulator 12 is made of crosslinked polyethylene or the like and covers the core wire 11. The copper tape 13 is provided in a tape shape and is wound around the outer periphery of the insulator 12. The sheath 14 is made of polyethylene or the like and covers the copper tape 13. Here, the abnormality of the copper tape 13 means that the copper tape 13 is displaced and a part of the core wire 11 that is not covered with the copper tape 13 is generated.

  Next, before describing the configuration of the abnormality detection device 20 of the present invention, the principle of abnormality detection of the abnormality detection device 20 of the present invention will be described. In general, when an antenna such as the dipole antenna AT1 is close to a metal body, the antenna impedance decreases, and impedance matching between the antenna and the feeding path cannot be achieved, and reflection at the antenna increases. Therefore, when the normal portion with the copper tape 13 is scanned with the antenna, the antenna and the copper tape 13 which is a metal body are close to each other, and reflection at the antenna increases. On the other hand, when the abnormal portion where the deviation is generated in the copper tape 13 is scanned with the antenna, the antenna and the copper tape 13 do not come close to each other, and the reflection at the antenna is lowered. The present inventors considered that it is possible to detect the displacement of the copper tape 13 with one antenna by observing the reflected wave from the antenna.

  Therefore, the inventors simulated S11 (reflection amount) of the dipole antenna AT1 when the dipole antenna AT1 is scanned along the longitudinal direction of the CV cable 10 shown in FIG. The results are shown in FIG. As shown in FIG. 3, in this simulation, the longitudinal direction of the CV cable 10 is assumed to be along the X axis, and the length is set to 50 mm. Since the center in the X-axis direction of the CV cable 10 is x = 0 mm, the CV cable 10 exists at x = −25 mm to +25 mm.

  In order to simplify the calculation by the simulation, the cross section of the CV cable 10 is approximated by a square instead of a circle, the core wire 11 is present in a square of 50 mm × 50 mm, and the copper tape 13 is present in a square cross section of 10 mm × 10 mm. The deviation of the copper tape 13 was assumed to occur with a width of 6 mm with the center of the X axis of the CV cable 10 (x = 0 mm) as the center. The sheath 14 around the copper tape 13 is assumed to have a thickness of 1 mm, and a dipole antenna AT1 is arranged along the Z axis at a point y = 6 mm away from the copper tape 13 by changing the value of x for simulation. went. Since the length of the dipole antenna AT1 is 10 mm, it resonates at about 14 GHz.

  As shown in FIG. 2, when the position x of the dipole antenna AT1 is changed, S11 (boundary between the abnormal portion where the copper tape 13 is shifted and the normal portion where the copper tape 13 is not shifted) is defined as x. It was found that dB) increased rapidly. S11 (dB) is −8 dB or less at the center position (x = 0) of the deviation of the copper tape 13, whereas it is −2 dB or more at the position where the copper tape 13 is not displaced. From this, it was found that the deviation of the copper tape 13 can be detected by setting the threshold to, for example, about −4 dB between −2 dB and −8 dB.

  In addition, the present inventors arranged the dipole antenna AT1 at the position of x = 0, measured S11 (unit) with respect to frequency, and measured impedance characteristics. The results are shown in FIG. As shown in the figure, when the dipole antenna AT1 is disposed at the position of x = 0 (that is, the abnormal portion where the deviation of the copper tape 13 is generated), impedance matching with the feeding path is achieved at the resonance frequency of 14 GHz of the dipole antenna AT1. As a result, S11 (unit) is 0.4 or less. In addition, the present inventors arranged the dipole antenna AT1 at a position of x = 5 mm, measured S11 (unit) with respect to frequency, and measured impedance characteristics. The results are shown in FIG.

  As shown in the figure, when the dipole antenna AT1 is arranged at the position of x = 5 mm (that is, the normal part where the deviation of the copper tape 13 is not generated), the copper tape 13 is close to the dipole antenna AT1 and the antenna impedance is lowered. Therefore, it was found that impedance matching with the feeding path could not be achieved, and S11 (unit) at a resonance frequency of 14 GHz rapidly increased to 0.83 or more. From this, it can be seen that the displacement of the copper tape 13 can be detected.

  Next, the configuration of the abnormality detection device 20 that detects an abnormality of the copper tape 13 from the difference of S11 of the dipole antenna AT1 described above will be described below with reference to FIG. As shown in the figure, the abnormality detection device 20 includes a dipole antenna AT1, an oscillator 21, a coaxial cable 22, a directional coupler 23 as detection means, a traveling wave receiver 24, and a reflected wave receiver 25. And a determiner 26 as an abnormality detection means. The dipole antenna AT1 is composed of two antenna elements arranged in a straight line. In the dipole antenna AT1, two antenna elements are arranged along the Z axis perpendicular to the X axis.

  The dipole antenna AT1 is attached to the CV cable 10 so that it can be scanned along the CV cable 10 by an attaching portion (not shown). In addition, when the dipole antenna AT1 is attached to the CV cable 10 by the attachment portion, the antenna impedance changes between when the normal portion with the copper tape 13 is scanned and when the abnormal portion without the copper tape 13 is scanned. It is arranged close to the CV cable 10. For example, the dipole antenna AT1 is arranged so that the distance between the dipole antenna AT1 and the copper tape 13 is λ / 4 or less and the distance between the dipole antenna AT1 and the core wire 11 is λ / 4 or more. Note that λ is a wavelength at the resonance frequency of the dipole antenna AT1.

  In FIG. 1, the shape of the dipole antenna AT1 is linear, but the shape of the dipole antenna AT1 is not limited to this. For example, the circular CV cable 10 may be bent in a circular shape along the outer periphery thereof. As a result, the distance between the dipole antenna AT1 and the copper tape 13 becomes closer, and a difference in S11 occurs between the abnormal portion where the copper tape 13 is not present and the normal portion where the copper tape 13 is present, thereby accurately detecting the abnormality. Can do.

  The oscillator 21 oscillates at a resonance frequency of 14 GHz of the dipole antenna AT1 and outputs a radio wave input to the dipole antenna AT1. The coaxial cable 22 is a feeding path between the dipole antenna AT1 and the oscillator 21. A radio wave traveling from the oscillator 21 toward the dipole antenna AT1 is transmitted to the coaxial cable 22 as a traveling wave. The coaxial cable 22 transmits a radio wave reflected from the dipole antenna AT1 and transmitted to the oscillator 21 as a reflected wave among radio waves input from the oscillator 21 to the dipole antenna AT1. The coaxial cable 22 is provided so that impedance matching with the dipole antenna AT1 can be obtained at a resonance frequency of 14 GHz of the dipole antenna AT1 when the abnormal portion of the copper tape 13 is scanned.

  A directional coupler 23 as a detecting means is provided on the coaxial cable 22. The directional coupler 23 outputs a traveling wave from the oscillator 21 toward the dipole antenna AT1 among the radio waves transmitted on the coaxial cable 22 to the traveling wave receiver 24. The directional coupler 23 outputs a reflected wave from the dipole antenna AT 1 to the oscillator 21 among the radio waves transmitted on the coaxial cable 22 to the reflected wave receiver 25.

  The traveling wave receiver 24 receives the traveling wave output from the directional coupler 23 and outputs the reception level to the determination unit 26. The reflected wave receiver 25 receives the reflected wave output from the directional coupler 23 and outputs the reception level to the determination unit 26. For example, every time a predetermined time elapses or every time the CV cable 10 is scanned for a certain distance, the determiner 26 calculates and obtains S11 (dB) (or (init)) which is a ratio of the reflected wave and the traveling wave. Compare S11 (dB) with the threshold (-4 dB) described above. If the determined S11 (dB) is equal to or less than the threshold, the determiner 26 determines that the antenna impedance is not lowered and the reflection is small because the copper tape 13 is not close to the dipole antenna AT1. Then, the determiner 26 determines that the displacement of the copper tape 13 has occurred. On the other hand, if the determined S11 (dB) is larger than the threshold, the determiner 26 determines that the antenna impedance is lowered and the reflection is large because the copper tape 13 is close to the dipole antenna AT1. To do. Then, the determiner 26 determines that the displacement of the copper tape 13 has not occurred.

  According to the abnormality detection device 20 described above, the antenna impedance can be scanned when the normal portion with the copper tape 13 is scanned and when the abnormal portion without the copper tape 13 is scanned so as to be scanned along the CV cable 10. The dipole antenna AT1 is arranged so that changes. Then, the determiner 26 detects an abnormality of the copper tape 13 based on a reflected wave from the dipole antenna AT1 toward the oscillator 21 among the radio waves on the coaxial cable 22 between the dipole antenna AT1 and the oscillator 21. Therefore, when the normal part with the copper tape 13 is scanned, the antenna impedance of the dipole antenna AT1 decreases and the reflected wave increases, and when the abnormal part without the copper tape 13 is scanned, the antenna impedance of the dipole antenna AT1 decreases. Therefore, the abnormality (displacement) of the copper tape 13 can be detected based on the reflected wave at the dipole antenna AT1. Thereby, the abnormality (displacement) of the copper tape 13 can be detected with only one dipole antenna AT1, and the abnormality detection device 20 for the copper tape 13 can be provided in which cost and size are reduced.

  In addition, according to the abnormality detection device 20 described above, the abnormality of the copper tape 13 is set to be detected based on S11 which is the ratio of the reflected wave and the traveling wave separately detected by the directional coupler 23. Yes. Thereby, the abnormality of the copper tape 13 can be accurately detected without depending on the fluctuation of the traveling wave.

  In addition, according to the abnormality detection apparatus 20 mentioned above, S11 was calculated | required from the reflected wave and the traveling wave, and the abnormality of the copper tape 13 was detected based on calculated | required S11, but this invention is limited to this. is not. For example, it is conceivable to detect an abnormality of the copper tape 13 only by the level of the reflected wave.

  Further, according to the first embodiment described above, the dipole antenna AT1 is scanned along the CV cable 10, but the present invention is not limited to this. Other types of antennas may be scanned along the CV cable 10.

Second Embodiment In the first embodiment described above, the abnormality of the copper tape 13 is detected from the difference in S11 of the dipole antenna AT1. However, in the abnormality detection device 20 shown in the first embodiment, it is difficult to increase the difference in S11 of the dipole antenna AT1 between the normal part and the abnormal part. Therefore, in the abnormality detection apparatus 20 in the second embodiment, the reflected wave at the CV cable 10 is adjusted to increase the level difference of the reflected wave between when the normal part is scanned and when the abnormal part is scanned. Anomalies can be detected from reflected waves more accurately.

  The abnormality detection device 20 in the second embodiment will be described below with reference to FIG. In FIG. 6, parts that are the same as those already described in the first embodiment with reference to FIG. 1 are given the same reference numerals, and detailed descriptions thereof are omitted. As shown in the figure, the abnormality detection device 20 includes a transmission / reception antenna AT2, an oscillator 21, a coaxial cable 22, a circulator 27 as detection means, a reflected wave receiver 25, and a determination unit 26. Yes. The transmission / reception antenna AT2 is arranged so as to be able to scan along the CV cable 10 similarly to the dipole antenna AT1 described above, for example.

  Since the oscillator 21 and the coaxial cable 22 are the same as those in the first embodiment described above, a detailed description thereof is omitted here. In the second embodiment, a circulator 27 is provided instead of the directional coupler 23. The circulator 27 is provided on the coaxial cable 22, and among the radio waves transmitted on the coaxial cable 22 between the oscillator 21 and the transmission / reception antenna AT 2, the reflected wave W 2 from the transmission / reception antenna AT 2 to the oscillator 21 is transmitted to the reflected wave receiver 25. Output. The reflected wave receiver 25 receives the reflected wave W2 output from the circulator 27 and outputs the reception level to the determiner 26, as in the first embodiment. The determiner 26 detects the abnormality of the CV cable 10 by comparing the reception level of the reflected wave W2 output from the circulator 27 and the threshold.

  Next, the abnormality detection principle of the abnormality detection device 20 in the second embodiment will be described. As shown in the figure, the traveling wave W1 output from the oscillator 21 is transmitted through the coaxial cable 22 and reaches the transmission / reception antenna AT2. When the traveling wave W1 is input, the transmission / reception antenna AT2 radiates the traveling wave W1 toward the CV cable 10. A part of the traveling wave W1 is reflected by the transmission / reception antenna AT2 as shown by a one-dot chain line, becomes an antenna reflected wave W21, and transmits the coaxial cable 22 from the transmission / reception antenna AT2 toward the oscillator 21.

  The traveling wave W1 radiated from the transmission / reception antenna AT2 is reflected by the copper tape 13 or the core wire 11 of the CV cable 10 and received by the transmission / reception antenna AT2 as a cable reflection wave W22 (wire reflection wave). The cable reflected wave W22 received by the transmission / reception antenna AT2 transmits the coaxial cable 22 from the transmission / reception antenna AT2 toward the oscillator 21. Therefore, a reflected wave W2 in which the antenna reflected wave W21 and the cable reflected wave W22 interfere is transmitted to the coaxial cable 22 from the transmission / reception antenna AT2 toward the oscillator 21. In the normal part where the copper tape 13 is present and the abnormal part where the copper tape 13 is not present, the path length of the radio wave from the transmission (radiation) from the transmission / reception antenna AT2 to the reception by the transmission / reception antenna AT2 after being reflected by the CV cable 10 is As a result, the reception level of the cable reflected wave W22 at the transmission / reception antenna AT2 is different.

  Therefore, in the second embodiment, for example, the reception level of the cable reflected wave W22 at the transmission / reception antenna AT2 is adjusted by adjusting the distance between the CV cable 10 and the transmission / reception antenna AT2. That is, the level of the antenna reflected wave W21 is reflected by the copper tape 13 and is increased by interference with the cable reflected wave W22 (FIG. 6A) received by the transmission / reception antenna AT2 (W2> W21), and the antenna reflection The CV cable 10-transmission / reception antenna AT2 so that the level of the wave W21 is reduced by interference with the cable reflected wave W22 (FIG. 6B) reflected by the core wire 11 and received by the transmission / reception antenna AT2 (W2 <W21). Adjust the distance between. Most preferably, the antenna reflected wave W21 and the cable reflected wave W22 reflected by the copper tape 13 and received by the transmission / reception antenna AT2 interfere with each other in the same phase, and are reflected by the antenna reflected wave W21 and the core wire 11 for transmission / reception. The distance between the CV cable 10 and the transmission / reception antenna AT2 is adjusted so that the cable reflected wave W22 received by the antenna AT2 interferes with the opposite phase. In this way, by adjusting the distance between the CV cable 10 and the transmission / reception antenna AT2, the level difference of the reflected wave W2 transmitted through the coaxial cable 22 with or without the copper tape 13 can be increased.

  Next, the inventors measured the level of the reflected wave W2 when the distance between the CV cable 10 and the transmission / reception antenna AT2 was changed using the abnormality detection device 20 shown in FIG. The results are shown in FIG. In the figure, the solid line is the level of the reflected wave W2 when the copper tape 13 is present, and the dotted line is the level of the reflected wave W2 when the copper tape 13 is not present. At this time, the oscillator 21 is set to oscillate at 5.65 GHz. As the CV cable 10, the outer diameter of the cable is 40 mm, the thickness of the sheath 14 is 3 mm, the diameter of the copper tape 13 is about 34 mm, the thickness of the insulator 12 is 5 mm, and the diameter of the core wire 11 is about 24 mm. Then, the copper tape 13 at the center in the longitudinal direction of the CV cable 10 was cut 50 mm, and the reflected wave W2 when the portion was scanned was measured as the reflected wave W2 when the copper tape 13 was not present.

  As shown in FIG. 7, as the distance between the CV cable 10 and the transmission / reception antenna AT2 is increased, the level difference of the reflected wave W2 due to the presence or absence of the copper tape 13 increases and decreases after peaking at 20 mm. Thereafter, it increases again after reaching 0 at around 32 mm, decreases after reaching a peak at 40 mm, and thereafter the same change is repeated. The difference in level of the reflected wave W2 depending on the presence or absence of the copper tape 13 is 17 dB at 20 mm and 20 dB at 40 mm.

  When the copper tape 13 is 20 mm and the antenna reflected wave W21 and the cable reflected wave W22 reflected by the copper tape 13 interfere with each other at substantially the same phase and level, the reception level becomes high (the level of the reflected wave W2 = −14 dBm). In the case without the copper tape 13, the antenna reflected wave W21 and the cable reflected wave W22 reflected by the core wire 11 interfere with each other at almost the same phase and at the same level, so the reception level is low (the level of the reflected wave W2 = −31 dBm). . On the other hand, when the copper tape 13 is present at 40 mm, the antenna reflected wave W21 and the cable reflected wave W22 reflected by the copper tape 13 interfere with each other in the opposite phase and at the same level, so that the reception level becomes considerably low (the reflected wave W2 In the case where the level is −43 dBm) and the copper tape 13 is not provided, the level of the cable reflected wave W22 reflected by the core wire 11 becomes small and the level of the antenna reflected wave W21 becomes dominant. Level (−23 dBm).

  Further, when the distance between the transmission / reception antenna AT2 and the CV cable 10 is small, the level difference of the reflected wave W2 appears remarkably, and the level of the cable reflected wave W22 may be equal to the level of the antenna reflected wave W21. I understand. When the distance between the CV cable 10 and the transmission / reception antenna AT2 is 50 mm or more, the level difference of the reflected wave W2 is small regardless of the presence or absence of the copper tape 13. This is considered to be because the reception level of the cable reflected wave W22 is reduced and the influence of interference with the cable reflected wave W22 is reduced. Therefore, in order to increase the influence of the interference by the cable reflected wave W22, the distance between the CV cable 10 and the transmission / reception antenna AT2 is provided to be short, and the level of the cable reflected wave W22 is set to be higher than the level of the antenna reflected wave W21. I understand that

  According to the abnormality detection device 20 described above, the level of the antenna reflected wave W21 is increased by interfering with the cable reflected wave W22 reflected by the copper tape 13, and the level of the antenna reflected wave W21 is reflected by the core wire 11. The distance between the transmission / reception antenna AT2-CV cable 10 is adjusted so as to be lowered by interference with the cable reflected wave W22. Thereby, the fluctuation | variation of the reflected wave W21 by the presence or absence of the copper tape 13 can be enlarged, and abnormality of the copper tape 13 can be detected still more correctly.

  In the second embodiment described above, the cable reflection wave W22 is adjusted by adjusting the distance between the CV cable 10 and the transmission / reception antenna AT2, and the level of the antenna reflection wave W21 is reflected by the copper tape 13. The level of the antenna reflected wave W21 is increased by interfering with the wave W22, and the level of the antenna reflected wave W21 is decreased by interfering with the cable reflected wave W22 reflected by the core wire 11. However, the present invention is not limited to this. . For example, the cable reflected wave W22 may be adjusted by adjusting the reflection characteristics of the transmission / reception antenna AT2 and the frequency of the oscillator 21.

  In the second embodiment described above, the level of the cable reflected wave S22 is adjusted by adjusting the distance between the CV cable 10 and the transmission / reception antenna AT2, so that the cable reflected wave W22 and the antenna reflected wave W21 have the same level. However, the present invention is not limited to this. For example, by adjusting the reflection characteristics of the transmitting / receiving antenna AT2 and the frequency of the oscillator 21 to adjust the levels of both the antenna reflected wave W21 and the cable reflected wave W22, the antenna reflected wave W21 and the cable reflected wave W22 are set to the same level. May be. Further, by selecting the type of the transmission / reception antenna AT2 and adjusting the directivity and gain of the transmission / reception antenna AT2 to adjust the level of the cable reflected wave W22, the antenna reflected wave W21 and the cable reflected wave W22 are set to the same level. Also good.

  In the first and second embodiments described above, the determination device 26 detects an abnormality of the copper tape 13 based on the level of the reflected wave W1 flowing through the coaxial cable 22. However, the present invention is not limited to this. . For example, the level of the reflected wave W2 flowing through the coaxial cable 22 may be simply displayed, and the operator may determine the abnormality of the copper tape 13 from the level.

  In the first and second embodiments described above, a directional coupler or a circulator is used as the detection means, but the present invention is not limited to this. For example, any device that can detect a reflected wave flowing through the coaxial cable 22 may be used. For example, an isolator may be used.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

It is a block diagram which shows the abnormality detection apparatus of the copper tape (shield member) in 1st Embodiment. It is a graph which shows the result of having simulated S11 (reflection amount) of a dipole antenna when a dipole antenna is scanned along the longitudinal direction of a CV cable. It is a perspective view which shows the CV cable used for the simulation of FIG. (A) is a graph showing S11 with respect to the frequency of the dipole antenna when x = 0 mm, and (B) is a Smith chart showing the impedance characteristics of the dipole antenna when x = 0 mm. (A) is a graph showing S11 with respect to the frequency of the dipole antenna when x = 5 mm, and (B) is a Smith chart showing the impedance characteristics of the dipole antenna when x = 5 mm. It is a block diagram which shows the abnormality detection apparatus of the copper tape (shield member) in 2nd Embodiment. It is a graph which shows the result of having measured the level of the reflected wave when changing the distance between a CV cable and a transmission / reception antenna using the abnormality detection apparatus shown in FIG.

Explanation of symbols

10 CV cable (electric wire)
11 Core wire 12 Insulator (Internal insulator)
13 Copper tape (shield member)
14 Sheath (external insulator)
20 Abnormality detection device 21 Oscillator 22 Coaxial cable (feeding path)
23 Directional coupler (detection means)
26 Judger AT1 Dipole antenna (antenna)
AT2 Transmit / receive antenna (antenna)
W1 traveling wave W2 reflected wave W21 antenna reflected wave W22 cable reflected wave (electric wire reflected wave)

Claims (6)

An abnormality of the shield member in an electric wire having a conductive core wire, an internal insulator covering the core wire, a shield member wound around an outer periphery of the internal insulator, and an external insulator covering the shield member In the method of detecting an abnormality of the shield member to be detected,
A step of arranging the antenna so that the antenna impedance can be changed between scanning the normal part with the shield member and scanning the abnormal part without the shield member so that the antenna member can be scanned along the electric wire. When,
Oscillating an oscillator and inputting radio waves to the antenna;
Detecting an abnormality of the shield member based on a reflected wave from the antenna toward the oscillator among the radio waves on the feeding path between the antenna and the oscillator;
A method for detecting an abnormality of a shield member, characterized in that the steps are sequentially performed. An abnormality of the shield member in an electric wire having a conductive core wire, an internal insulator covering the core wire, a shield member wound around an outer periphery of the internal insulator, and an external insulator covering the shield member In the abnormality detection device for the shield member to be detected,
An antenna disposed so as to be able to scan along the electric wire, and to change the antenna impedance between when the normal part with the shield member is scanned and when the abnormal part without the shield member is scanned; ,
An oscillator for inputting radio waves to the antenna;
An anomaly detection means for detecting an anomaly of the shield member based on a reflected wave from the antenna toward the oscillator among radio waves on a feeding path between the antenna and the oscillator;
An apparatus for detecting an abnormality of a shield member, comprising: The abnormality detection means includes detection means for separately detecting a traveling wave from the oscillator toward the antenna and a reflected wave from the antenna toward the oscillator among radio waves transmitted on the power supply path between the oscillator and the antenna, And
3. The shield member according to claim 2, wherein the abnormality detection unit is configured to detect an abnormality of the shield member based on a ratio between the separately detected reflected wave and traveling wave. Anomaly detection device. The abnormality detection device for a shield member according to claim 2 or 3, wherein the antenna is provided by being bent along an outer periphery of the shield member. The antenna reflected wave reflected by the antenna and the wire reflected wave reflected by the shield member and received by the antenna interfere in the same phase, and are reflected by the antenna reflected wave reflected by the antenna and the core wire. And at least one of the distance between the antenna and the wire, the reflection characteristic of the antenna, and the frequency of the oscillator is adjusted so that the reflected wire received by the antenna interferes with an opposite phase. The apparatus for detecting an abnormality of a shield member according to claim 4. The antenna having directivity or gain is provided such that the antenna reflected wave and the wire reflected wave interfere with each other at the same level, or the antenna reflected wave and the wire reflected wave interfere with each other at the same level. The shield member abnormality detection device according to claim 5, wherein at least one of a distance between the antenna and the electric wire, a reflection characteristic of the antenna, and a frequency of the oscillator is adjusted. .

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