Wire rope flaw detector

Abstract

To provide a wire rope flaw detection device that can detect occurrence of wire breaking off an orientation area or at a deep part on the basis of a minutely leaking magnetic signal even if a magneto-sensitive element has directivity.SOLUTION: A wire rope flaw detection device detecting damage to a wire rope, comprises: a magnetizer that forms a magnetic path in a prescribed section of the wire rope; a magnetic sensor that can detect a leaking magnetic flux from the damage to the wire rope while being magnetically insulated from the magnetizer; a ferromagnetic material that changes the direction of the leaking magnetic flux occurring because of damage to a wire of the wire rope put in the magnetic path, and converges the leaking magnetic flux on the magnetic sensor; a signal collection unit that collects a magnetic signal from the magnetic sensor detecting the leaking magnetic flux; and a signal processing unit that calculates a damage position of the wire on the basis of the magnetic signal collected by the signal collection unit, in which the magnetic sensor is disposed between the wire rope put in the magnetic path and the ferromagnetic material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wire rope flaw detector that inspects the deterioration state of a wire rope made of a magnetic metal material. [Background technology]

[0002] As an inspection technique for hoisting ropes applied to the safety monitoring of elevators, a device that detects breakage of wires in a rope based on leakage magnetic flux generated in a wire rope placed in a magnetic path (for example, Patent Document 1) is known. The wire ropes used as hoisting ropes for elevator cars are made by twisting together wires of magnetic metal material. Small coils and Hall elements have been used as magnetic sensors suitable for inspecting such wire ropes.

[0003] Also known is a leakage magnetic flux detector (see, for example, Patent Document 2) that detects minute defects by disposing a ferromagnetic body near a magnetic sensor for the purpose of detecting defects in a metal conduit wall. This device has the effect of being able to detect even minute magnetic signals in a metal conduit wall by selectively passing magnetic flux through the ferromagnetic body rather than through the space around the ferromagnetic body placed in a magnetic field. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6715951 [Patent Document 2] JP 2002-156365 A Summary of the Invention [Problem to be solved by the invention]

[0005] The technique disclosed in Patent Document 1 and others, which applies an excessive saturation magnetic field to the test object in order to increase the signal strength of the leakage magnetic flux, has the risk of multiple wire ropes being magnetically attracted to each other due to residual magnetism generated in the magnetic metal wire rope. In addition, the distance between the wire break that occurs deep inside the wire rope and the magnetic sensor located on the outer periphery of the wire rope increases, so the detectable signal becomes smaller. In addition, with the technique disclosed in Patent Document 2, it is difficult to identify the position of the wire break in the direction of rotation of the wire rope.

[0006] In addition, due to recent changes in the industrial structure, there is a tendency to rely on Hall elements, which are easy to procure, while small coils are difficult to procure as devices suitable for magnetic sensors. However, the detection sensitivity characteristics of highly directional magnetic sensing elements such as Hall elements are more sensitive than small coils when leakage magnetic flux is present in the immediate vicinity along the direction of the direction, but the greater the distance from the target outside that area, the more disadvantageous they become. Therefore, directional magnetic sensing elements have the disadvantage of not necessarily being suitable for use as wire rope flaw detectors to detect wire breaks outside the directional area or deep inside.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a wire rope flaw detector that can detect the occurrence of a wire break outside or deep within the directional range based on a minute leaking magnetic signal, even when using a directional magnetic sensing element. [Means for solving the problem]

[0008] The present invention, which solves the above problems, is a wire rope flaw detector for detecting damage to a wire rope, and includes a magnetizer that forms a magnetic path in a predetermined section of the wire rope, a magnetic sensor that is magnetically insulated from the magnetizer and can detect leakage magnetic flux from damage to the wire rope, a ferromagnetic body that changes the direction of leakage magnetic flux generated when a wire of the wire rope placed in the magnetic path is damaged and concentrates it on the magnetic sensor, a signal collection unit that collects magnetic signals from the magnetic sensor that detect the leakage magnetic flux, and a signal processing unit that calculates the location of damage to the wire based on the magnetic signals collected by the signal collection unit, and the magnetic sensor is disposed between the wire rope placed in the magnetic path and the ferromagnetic body. Effect of the Invention

[0009] According to the present invention, a wire rope flaw detector can be provided that can detect the occurrence of a wire break outside the directional range or deep inside based on a minute leaking magnetic signal, even when a directional magnetic sensing element is used. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a sensor unit provided in a wire rope flaw detector according to an embodiment of the present invention (hereinafter also referred to as "this device") taken along a plane perpendicular to the axis (in the direction in which the rope is cut into a ring). FIG. [Diagram 2] This is an axial cross-sectional view of a sensor unit in which the strands and magnetic sensors are arranged in a ratio of 8:9 and are opposed to each other at different circumferential pitches. [Diagram 3] 3 is a functional block diagram showing the configuration of a signal processing unit and the like of the present device formed by connecting the sensor unit of FIG. 1 or FIG. 2. [Figure 4] 2 is a cross-sectional view perpendicular to the axis of a sensor portion according to a first embodiment, which is a modification of the sensor portion in FIG. 1; [Diagram 5] 1. FIG. 4 is an axially orthogonal cross-sectional view of a sensor portion according to a second embodiment, which is a modification of the sensor portion in FIG. [Figure 6] 10 is a cross-sectional view perpendicular to an axis of a sensor portion according to a third embodiment, which is a modification of the sensor portion in FIG. [Figure 7]10 is an axial cross-sectional view of a sensor unit according to a fourth embodiment obtained by modifying the sensor unit in FIG. 1, and a schematic axial cross-sectional view showing a simulation of a state of magnetic flux. [Figure 8] 4 is a graph showing detection sensitivity characteristics of a Hall element. [Figure 9] 13 is a graph showing the sensitivity of the sensor unit to detect a break in a wire, the sensor output for each of 1ch to 4ch, and the difference depending on the condition of whether or not a magnetic body (magnetic material) is present. [Figure 10] 8 is an axial cross-sectional view of a sensor unit according to a comparative example, which is to be compared with the sensor unit in FIG. 7, and a schematic axial cross-sectional view of a simulation of the state of magnetic flux. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The wire rope 2 illustrated in Fig. 1, Fig. 2, Fig. 4 to Fig. 7, and Fig. 10 has eight strands 23 arranged closely around the outer periphery, and the entirety including these eight strands 23 is twisted together into one. The wire rope 2 having such a composition is merely one example of the object to be inspected by the present device 1 (Fig. 3). In addition, the same reference numerals are used in each drawing to designate parts having the same effect, to avoid duplication of explanation.

[0012] As for the sensor units 20A, 20AX, 20AY, 20B to 20D (collectively 20) of the present device 1, Fig. 4 shows sensor unit 20B of Example 1, Fig. 5 shows sensor unit 20C of Example 2, Fig. 6 shows sensor unit 20AY of Example 3, and Fig. 7 shows sensor unit 20D of Example 4. Meanwhile, Fig. 10 shows sensor unit 20E according to a comparative example. Note that the longitudinal direction of the rope is called the axial direction, and the direction in which the rope is cut into rings is called the orthogonal-axis direction.

[0013] Fig. 1 is an axial cross-sectional view of a sensor unit 20A provided in the device 1. Fig. 2 is an axial cross-sectional view of a sensor unit 20AX in which the ratio of the number of strands 23 to the number of magnetic sensors 3 is 8:9 and they are arranged to face each other at different circumferential pitches. The vicinity of the outer periphery of the wire rope 2 is surrounded by a plurality of strands 23 formed by bundling and twisting wires 24. The sensor units 20A and 20AX include a magnetic sensor 3, a ferromagnetic sheet 4A (embodiment of a ferromagnetic material 4), an outer protective cover 21 (omitted except in Fig. 2), and an inner protective cover 22.

[0014] A single wire rope 2 is made up of many wires 24, and if even one of the wires 24 is broken, the function required of this device 1 is to reliably detect it. A magnetizer (not shown) forms a magnetic path in a predetermined section of the wire rope 2. The magnetic sensor 3 is magnetically insulated from the magnetizer and is installed along the outer periphery of the cross section of the wire rope 2. When the broken wire 24 is a valley break (FIGS. 5, 7, and 10) 29 located away from the magnetic sensor 3, the leakage magnetic flux of the broken wire 24 has a hard time reaching the distant magnetic sensor 3, and is therefore unlikely to be detected.

[0015] Unless some measure is taken against this, the sensitivity of the wire rope flaw detector will remain low and its reliability will remain poor. On the other hand, it is known that magnetic flux tends to be absorbed by ferromagnetic materials with high magnetic permeability. Therefore, it is conceivable to form a sheet-shaped ferromagnetic sheet 4A and have it act to absorb the leakage magnetic flux generated near the broken part of the wire 24. This device 1 applies this effect, and finds a positional relationship that increases the proportion of magnetic flux input to the magnetic sensor 3, and brings the ferromagnetic sheet 4A closer to the magnetic sensor 3. As a result, this device 1 can improve its sensitivity to the valley break 29.

[0016] The wire rope 2 is inspected by inserting it into the loop of the annular sensor unit 20. However, it is extremely difficult to insert the wire rope 2 into the closed annular sensor unit 20 for inspection in an elevator that is completed and in operation, and then detach it. Therefore, in actual inspection, the annular or tubular sensor unit 20 is split into two, opened up, the wire rope 2 is clamped inside, and then the loop is closed back to its original position before inspection. The sensor unit 20A can be separated and combined at the dashed line YY (omitted except in Figures 2 and 6). A detailed explanation of this separation mechanism will be omitted.

[0017] As the type of the magnetic sensor 3, other than the Hall element, for example, a TMR (Tunnel Magneto Resistive) sensor, an AMR (Anisotropic Magneto Resistive) sensor, a GMR (Giant Magneto Resistive effect) sensor, or a detection coil can be listed. The arrangement of the magnetic sensors 3 constituting the sensor unit 20 may be optimally formed in different ways depending on the type of the magnetic sensor 3.

[0018] In order to efficiently detect the breakage of the wire 24 using a minimum number of magnetic sensors 3, it is preferable to arrange a plurality of magnetic sensors at a predetermined interval (pitch) around the circumference of the wire rope 2 in positions facing the outer periphery of the wire rope 2. The arrangement of the magnetic sensors 3 that enables highly sensitive detection of the valley break 29 located far from the magnetic sensors 3 will be described later with reference to Figs. 5, 7 and 10.

[0019] The Hall elements serving as magnetic sensors 3 constituting the actual sensor unit 20 are arranged in a ring-shaped sensor group of eight (Figs. 1, 5, 7 and 10) or nine (Fig. 2) equally spaced elements in one row going around the outer circumference of the wire rope 2. Two rows of ring-shaped sensor groups may be offset in the axial direction and adjacent to each other on the same axis (Figs. 6 and 10). The more magnetic sensors 3 constituting the sensor unit 20, the more precisely they can cover all breaks in the wire 24, allowing for more accurate detection. In practice, the sensor unit 20 is designed to be as efficient as possible, with as few elements as possible.

[0020] Fig. 3 is a functional block diagram showing the configuration of a signal processing unit and the like of the present device 1 configured by connecting the sensor unit 20 of Fig. 1 or 2. As shown in Fig. 3, the present device 1 is configured with the sensor unit 20, a magnetic sensor circuit 5, a signal analysis unit 7, a data display unit 8, and a data input unit 9. The data input unit 9 has an operation console (not shown) connected to a power source 10 and a control circuit 11, and the user operates it to control the present device 1. The control circuit 11 controls the magnetic sensor circuit 5 and the signal analysis unit 7. The data display unit 8 displays the detected disconnection location of the wire 24 in an easily visible manner.

[0021] 3 shows only two representative paths (channels, hereinafter also referred to as "ch") corresponding to two magnetic sensors 3. However, as described above, the magnetic sensors 3 that make up the actual sensor unit 20 are basically 8, 16, or 24ch (9ch only in FIG. 1), which is an integer multiple of eight strands 23. The magnetic signal detected by the magnetic sensor 3 is amplified and noise is removed by the magnetic sensor circuit 5, and the signal is output to the signal analysis unit 7.

[0022] The magnetic sensor circuit 5 has a magnetic signal amplifier 12 and a filter circuit 13. The magnetic signal amplifier 12 amplifies the output signal from the magnetic sensor 3. The filter circuit 13 performs general analog filtering on the output signal amplified by the magnetic signal amplifier 12, and outputs an analog signal. The analog filtering removes commercial frequencies and other noise components and passes only the desired frequency range.

[0023] In this way, the magnetic sensor circuit 5 performs analog processing on the magnetic detection signal output from the magnetic sensor 3, and outputs an analog magnetic signal to the signal analysis unit 7. The signal analysis unit 7 is composed of an A / D converter 16, a signal collector 17, and a signal processor 18. The A / D converter 16 converts the analog magnetic signal output from the magnetic sensor circuit 5 into a digital signal, and outputs it to the signal collector 17. The signal processor 18 is a one-chip microcomputer or a general-purpose computer (hereinafter also referred to as "PC 18").

[0024] The PC 18 stores the digital magnetic signal output from the A / D converter 16 in the signal collector 17 and other devices by having the CPU (Central Processing Unit) read and execute a program stored in a memory or storage. The signal analysis unit 7 may be a dedicated device, but may also be realized by expanding and enhancing the functions of the PC 18 beyond the scope of FIG.

[0025] When the signal analysis unit 7 is the PC 18, the processing by the signal analysis unit 7 can be realized by program processing in the PC 18, and the data display unit 8 and the data input unit 9 can also be related devices of the PC 18, such as a keyboard and a liquid crystal display. Fig. 3 is only an example, and the functional configuration in the signal processing from the magnetic sensor 3 to the data display unit 8 can be modified in any way as long as the functions of the present device 1 can be realized. EXAMPLES

[0026] Fig. 4 is an axially orthogonal cross-sectional view of a sensor unit 20B according to a first embodiment, which is a modification of the sensor unit 20A in Fig. 1, with the essential parts enlarged and the same contents omitted. The sensor unit 20B of the first embodiment shown in Fig. 4 emphasizes the magnetic sensor 3 which is in one-to-one correspondence with the strand 23, and the sheet-like ferromagnetic sheet 4B (embodiment of the ferromagnetic material 4) which is in one-to-one correspondence with the magnetic sensor 3.

[0027] In contrast, the ferromagnetic sheet 4A illustrated in Figures 1 and 2 is rolled into a ring or cylinder shape and continuously covers the 8ch or 9ch magnetic sensor 3. As in the example illustrated in Figures 1 and 2, in the first embodiment, a magnetizer (not shown) forms a magnetic path in a predetermined section of the wire rope 2. The magnetic sensor 3 is magnetically insulated from the magnetizer and is disposed in a position facing the outer periphery of the wire rope 2. The ferromagnetic sheet 4B acts to absorb magnetism generated in its vicinity.

[0028] In the first embodiment of Fig. 4, the magnetic sensor 3 can monitor the strand 23 located within the detection area of ​​the directivity that extends in front of it. The leakage magnetic flux generated when the wire 24 in the strand 23 within the detection area breaks is directed so as to be absorbed into the ferromagnetic sheet 4B. If the directivity area of ​​the magnetic sensor 3 extends midway through this direction, the leakage magnetic flux generated by the broken wire 24 can be detected with high sensitivity.

[0029] When the broken wire 24 is located away from the magnetic sensor 3, and the ferromagnetic body 4B is not present, the proportion of leakage magnetic flux from the broken wire 24 that is detected by the magnetic sensor 3 is small. In addition, a ferromagnetic body 4 (including other examples) with high magnetic permeability has the property of attracting magnetic flux, and the proportion of magnetic flux that is attracted to the ferromagnetic body 4B and input to the magnetic sensor 3 in contact with the ferromagnetic body 4B increases. As described above, the device 1 of the first embodiment shown in FIG. 4 can efficiently obtain the leakage magnetic flux generated from the broken wire 24 of the wire rope 2 to be analyzed by the magnetic sensor 3, and can analyze the deterioration state of the wire rope 2 with high accuracy. EXAMPLES

[0030] 5 is an axially orthogonal cross-sectional view of a sensor unit 20C according to a second embodiment, which is a modification of the sensor unit 20A in FIG. 1. As shown in FIG. 5, the ferromagnetic sheet 4 has a multiple arch shape with legs attached to the rear of the magnetic sensor 3 and folded back. Such multiple arch shaped ferromagnetic sheet 4C (embodiment of the ferromagnetic material 4) captures weak magnetic signals like a parabolic antenna, and by attaching legs to the rear of the magnetic sensor 3 and folding back, it allows magnetic flux to penetrate from the front to the rear of the magnetic sensor 3 in a concentrated manner. As a result, the ferromagnetic sheet 4C exhibits an effect of being able to detect both the mountain notch 28 close to the magnetic sensor 3 and the valley notch 29 far from the magnetic sensor 3 with higher sensitivity than when the ferromagnetic sheet 4C is not present. EXAMPLES

[0031] Fig. 6 is an axially orthogonal cross-sectional view of a sensor unit 20AY according to a third embodiment, which is a modification of the sensor unit 20A in Fig. 1. The Hall elements as the magnetic sensors 3 constituting the sensor unit 20AY are arranged in a row of eight elements at equal intervals around the outer periphery of the wire rope 2 to form an annular sensor group, and two rows of the Hall elements are shifted in the axial direction and adjacent to each other on the same axis. The sensor unit 20AY in Fig. 6 can be divided and combined at the dashed line YY.

[0032] The more magnetic sensors 3 constituting the sensor unit 20, the more accurate the detection becomes, so that all broken parts of the wire 24 can be covered. In practice, the sensor unit 20 (including other examples) is designed to be as efficient as possible with the minimum number of sensors necessary. Therefore, the sensor unit 20AY in Fig. 6 may have eight magnetic sensors 31-34, 35-38 concentrated in two rows on only the inner circumferential surface of one half of the split mechanism.

[0033] Alternatively, the sensor unit 20AY in Fig. 6 may be provided on the entire inner circumferential surface of both sides of the split mechanism, not on one half of the split mechanism, with 16 magnetic sensors, which is twice as many as the magnetic sensors 31 to 34 and 35 to 38. In this configuration, the ferromagnetic sheet 4A exhibits the effect of being able to detect both the mountain notch 28 close to the magnetic sensor 3 and the valley notch 29 far from the magnetic sensor 3 with higher sensitivity than when the ferromagnetic sheet 4A is not provided.

[0034] Next, the results of magnetic simulation of wire rope flaw inspection for sensor unit 20D according to Example 4 shown in Fig. 7 and sensor unit 20E according to Comparative Example shown in Fig. 10 will be described with reference to Figs. 8 and 9. The difference between Example 4 (Fig. 7) and Comparative Example (Fig. 10) is the presence or absence of ferromagnetic body 4D (embodiment of ferromagnetic body 4), and Example 4 equipped with magnetic body 4D performed better (see G3 and G4 in Fig. 8). EXAMPLES

[0035] Fig. 7 is an orthogonal sectional view of a sensor unit 20D according to a fourth embodiment obtained by modifying the sensor unit 20A in Fig. 1, and a schematic axial sectional view simulating the state of the magnetic flux MF. As shown in Fig. 7, the magnetic flux MF is leakage magnetic flux generated from the notch 28. The magnetic sensors 31-34... have directivity in the front direction, and are disposed in a position facing the axial center from the outer periphery of the wire rope 2. The magnetic sensors 31-34... have no directivity in the rear direction, and a ferromagnetic body 4D is attached to the back surface of each of them.

[0036] The ferromagnetic sheet 4A of Example 1 shown in Fig. 1 and Fig. 2 was annular or cylindrical, and continuously covered the 8-channel magnetic sensor 3. In contrast, the ferromagnetic sheet 4B illustrated in Fig. 4 is different in that it is in one-to-one correspondence with the magnetic sensor 3. It can be seen that the simulation diagram of Example 4 shown in the lower part of Fig. 7 has more magnetic flux MF passing through the center of the magnetic sensor 3 than the simulation diagram of the comparative example shown in the lower part of Fig. 10.

[0037] Fig. 8 is a graph showing the detection sensitivity characteristics of a Hall element. In the graph of Fig. 8, the horizontal axis shows the distance (mm) between the sensor and the magnet, and the vertical axis shows the signal (mT) detected by the Hall element. As the graph shows, the detection output is roughly inversely proportional to the square of the distance, so in the sensor unit 20 of this device 1, the mountain edge 28, which is closer to the detection object to the magnetic sensor 3, is detected with higher sensitivity than the valley edge 29, which is farther from the detection object.

[0038] Fig. 9 is a graph showing the sensor output for each of 1ch to 4ch and the difference in sensitivity of the sensor unit 20 to detect a break in the wire depending on the condition of whether or not there is a magnetic body (magnetic material) 4D. The left side of Fig. 9 shows the results of the sensor unit 20E according to the comparative example of Fig. 10, which does not have a magnetic material, i.e., does not have a ferromagnetic material, divided into the magnetic sensors 31 to 34 of ch1 to ch4. The right side of Fig. 9 shows the results of the example 3 of Fig. 7, which has a magnetic material, i.e., has a ferromagnetic material 4D, divided into the magnetic sensors 31 to 34 of ch1 to ch4.

[0039] 7 detects leakage magnetic flux from a wire 24 that has been broken at a nearby notch 28 with high sensitivity, as shown by G3 and G4. Furthermore, since magnetic flux tends to be absorbed by ferromagnetic material 4D, which has high magnetic permeability, the proportion of magnetic flux input to magnetic sensor 32 increases when ferromagnetic material sheet 4D is in contact with magnetic sensor 32. Therefore, magnetic sensor 32, which has forward directionality, detects notch 28 more strongly due to the presence of ferromagnetic material sheet 4D.

[0040] In addition, on the right side of FIG. 9, ch4 is the output of magnetic sensor 34 that is unrelated to the break, and therefore has the smallest output. ch3 is the output of magnetic sensor 33 adjacent to crest 28 at a shallow angle, and therefore has a larger output than ch4. ch1 is the output of magnetic sensor 31 that captures valley cut 29 within its directional range, and therefore has a larger output than ch3. When comparing the left and right for each ch in FIG. 9, that is, comparing the presence and absence of ferromagnetic body 4D (magnetic material), of ch1 to ch3 that are effective for detection, the output is larger when ferromagnetic body 4D (magnetic material) is present. Comparative Example

[0041] FIG. 10 is an axial cross-sectional view of the sensor unit 20E according to the comparative example, which is compared with the sensor unit 20D in FIG. 7, and a schematic axial cross-sectional view simulating the state of the magnetic flux. As described above, by comparing G1 and G2 on the left side with G3 and G4 on the right side in FIG. 9, it can be clearly confirmed that the output of G1 and G2 without the ferromagnetic body 4D (magnetic material) is small. It can be confirmed that the simulation diagram of the comparative example shown in the lower part of FIG. 10 has less magnetic flux MF passing through the center of the magnetic sensor 3 than the simulation diagram of the embodiment 4 shown in the lower part of FIG. 7. In addition, the sensor unit 20E in FIG. 10 compensates for the lack of sensitivity of each magnetic sensor by densely arranging 16 magnetic sensors including 31 to 34 and 35 to 38 around the entire inner circumferential surface.

[0042] The wire rope flaw detector (this device) 1 according to the embodiment of the present invention can be summarized as follows. [1] As shown in Figures 1 to 3, this device 1 is a wire rope flaw detector 1 that detects damage to a wire rope 2 and includes a magnetizer (not shown), a magnetic sensor 3, a ferromagnetic material 4, a signal collection unit 5, and a signal processing unit 7.

[0043] The magnetizer forms a magnetic path in a predetermined section of the wire rope 2. The magnetic sensor 3 is magnetically insulated from the magnetizer and is disposed around the wire rope 2 in a position that allows it to face the outer periphery of the wire rope 2, and is capable of detecting leakage magnetic flux from a damaged portion of the wire rope 2. The ferromagnetic body 4 disposed at a position opposite the wire rope 2 changes the direction of leakage magnetic flux that occurs when an element wire 24 of the wire rope 2 placed in the magnetic path breaks, and concentrates the leakage magnetic flux at the magnetic sensor 3.

[0044] The signal collector 5 collects the magnetic signal from the magnetic sensor 3 that detects the leakage magnetic flux. The signal processor 7 calculates the breakage position of the wire 24 based on the magnetic signal collected by the signal collector 5. The magnetic sensor 3 is disposed so as to be sandwiched between the wire rope 2 placed in the magnetic path and the ferromagnetic body 4. This device 1 can detect the occurrence of a wire break (valley break 29) outside the directional range or deep inside based on the minute leaking magnetic signal even with a directional magnetic sensing element (magnetic sensor 3) such as a Hall element 3. The breakage of the wire 24 outside the directional range or deep inside of the wire rope 2 can be detected based on the minute leaking magnetic signal even with a directional magnetic sensing element.

[0045] [2] In the above [1], the strands 23 formed by bundling and twisting the wires 24 may be faced to the magnetic sensor 3 at different circumferential pitches. Even if the magnetic sensor 3 has a sharp and low directivity, the facing orientations of the magnetic sensors are irregular and varied, with some close to the tangent line of the strands 23 and some far from it, so that a wide range of targets can be covered. In other words, the possibility of capturing the breakage position of the wires 24 is increased within the highly sensitive, directional capture range that expands forward from the center of the magnetic sensor 3.

[0046] 2, if the number of strands 23 and magnetic sensors 3 are arranged in a ratio of 8:9, a wide variety of facing positions can be realized. For example, in a sensor unit 20AX configured by combining a minimum of 9 magnetic sensors 3 in a single ring-shaped row in contrast to the standard 8 strands 23, the effect of being able to detect both the mountain gap 28 close to the magnetic sensor 3 and the valley gap 29 far from the magnetic sensor 3 with high sensitivity can be obtained.

[0047] [3] In the above [1], the outer circumference of the wire rope 2 is surrounded by a plurality of strands 23 formed by bundling and twisting wires 24. In addition, the magnetic sensors 3, the number of which is an integral multiple (one or more times the number of strands 23) of the strands 23, are positioned so as to approach the tangents of each of the strands 23. In the device 1 configured in this way, the directional area of ​​the magnetic sensors 3 is efficiently deployed forward.

[0048] Therefore, it is easy to detect leakage magnetic flux caused by breakage of the wires 24 of the wire rope 2, both for the mountain break 28 close to the magnetic sensor 3 and the valley break 29 far from the magnetic sensor 3. As a result, the device 1 has the effect of being able to detect with high sensitivity.

[0049] [4] In the above [3], as shown in FIG. 10, the magnetic sensors 3 should be an integer multiple of at least two times the number of strands 23, and should be a mixture of sensors positioned close to and away from the tangents of each strand 23.

[0050] With this configuration, the device 1 covers a wide range of targets because the directional area of ​​the magnetic sensor 3 more closely faces those close to and far from the tangent of the strand 23. Therefore, it is easy to detect leakage magnetic flux caused by breakage of the wires 24 of the wire rope 2 for both the mountain break 28 close to the magnetic sensor 3 and the valley break 29 far from the magnetic sensor 3. As a result, the device 1 has the effect of being able to detect with high sensitivity.

[0051] [5] In the above [4], as shown in Figures 1, 2, 5 and 6, the ferromagnetic material 4 is formed into a sheet-like ferromagnetic material sheet 4, which covers the back of the magnetic sensor 3 arranged in a position facing the outer periphery of the wire rope 2. The sheet-like ferromagnetic material sheet 4 for such purposes is easy to procure and process the relevant members.

[0052] Furthermore, the ferromagnetic body 4 disposed on the opposite side of the wire rope 2 from the magnetic sensor 3 attracts leakage magnetic flux generated when the strands 24 of the wire rope 2 placed in the magnetic path break, changing its direction and concentrating it on the magnetic sensor 3. The device 1 configured in this way has the effect of being able to detect with high sensitivity both the mountain break 28 close to the magnetic sensor 3 and the valley break 29 far from the magnetic sensor 3.

[0053] [6] In the above [5], as shown in Fig. 5, the ferromagnetic sheet 4 may be in a multiple arch shape with legs attached to the back of the magnetic sensor 3 and folded back. The multiple arch shaped ferromagnetic sheet 4C captures weak magnetic signals like a parabolic antenna, and by attaching legs to the back of the magnetic sensor 3 and folding back, it allows magnetic flux to penetrate from the back of the magnetic sensor 3 to the front in a concentrated manner.

[0054] As a result, the ferromagnetic sheet 4C has the effect of being able to detect both the mountain notch 28 close to the magnetic sensor 3 and the valley notch 29 far from the magnetic sensor 3 with higher sensitivity than in the absence of the ferromagnetic sheet 4C.

[0055] Here, the direction of the magnetic flux can be reversed to obtain the same effect by reversing the N and S poles. Therefore, the magnetic field lines are concentrated along the direction extending forward from the center of the magnetic sensor 3, thereby improving the detection sensitivity.

[0056] [7] In the above [5], as shown in Figs. 1 and 2, the ferromagnetic sheet 4 is in the shape of a coaxial cylinder, and it is easy to procure and process such a corresponding member.

[0057] [8] In any of the above [1] to [8], the magnetic sensor 3 is a Hall element, and the ferromagnetic body 4 is preferably one having a stronger property of absorbing leakage magnetic flux. Such a ferromagnetic body 4 is preferably provided close to the rear of the magnetic sensor 3, which is provided at a position facing the outer periphery of the wire rope 2, with respect to its directivity.

[0058] If the magnetic sensor 3 is a Hall element, the ferromagnetic body 4 concentrates the magnetic lines along the directivity extending forward from the center of the Hall element. On the other hand, the ferromagnetic body 4 absorbs the leakage magnetic flux from the cut portion of the wire 24 and deflects it so that it is introduced into the magnetic sensing portion of the Hall element 3. In other words, the magnetic sensor 3 can easily capture an object in its directivity area, thereby improving detection sensitivity. [Industrial Applicability]

[0059] The present invention may be employed as a wire rope flaw detector for inspecting hoisting ropes in the safety monitoring of elevators. [Explanation of symbols]

[0060] 1 wire rope flaw detector (this device), 2 wire rope, 3 magnetic sensor, 4, 4A to 4D ferromagnetic body (ferromagnetic material, ferromagnetic sheet), 5 magnetic sensor circuit, 7 signal analysis section, 8 data display section, 9 data input section, 10 power supply, 11 control circuit, 12 magnetic signal amplifier, 13 filter circuit, 12 magnetic signal amplifier, 16 A / D converter, 17 signal collector, 18 signal processor, 20, 20AX, 20A to 20E sensor section, 21 outer protective cover, 22 inner protective cover, 23 strand, 24 wire, 28 (close to magnetic sensor 3) mountain cut, 29 (far from magnetic sensor 3) valley cut

Claims

1. A wire rope flaw detector for detecting damage to a wire rope, comprising: a magnetizer that forms a magnetic path in a predetermined section of the wire rope; a magnetic sensor that is magnetically insulated from the magnetizer and is capable of detecting leakage magnetic flux from a damaged portion of the wire rope; a ferromagnetic body that changes the direction of leakage magnetic flux generated when a strand of the wire rope placed in the magnetic path is damaged and concentrates the flux on the magnetic sensor; a signal collecting unit that collects a magnetic signal from the magnetic sensor that detects the leakage magnetic flux; a signal processing unit that calculates a damage position of the wire based on the magnetic signals collected by the signal collecting unit; Equipped with the magnetic sensor is disposed between the wire rope placed in the magnetic path and the ferromagnetic material; The outer periphery of the wire rope is formed by being surrounded by a plurality of strands formed by bundling and twisting the wires, the magnetic sensors are aligned so as to approach tangents of the respective strands, the number of the magnetic sensors being an integer multiple of one or more times the number of the strands; The number of the magnetic sensors is an integer multiple of two or more times the number of the strands, and some are positioned close to the tangents of the strands and some are positioned away from them; The ferromagnetic material forms a sheet-like ferromagnetic material sheet, and covers the back of the magnetic sensor that is disposed at a position that can face the outer periphery of the wire rope. Wire rope flaw detector.

2. A plurality of strands formed by bundling and twisting the wires are faced to a magnetic sensor at different circumferential pitches.

2. The wire rope flaw detector according to claim 1.

3. The ferromagnetic sheet has a multiple arch shape with legs attached to the rear of the magnetic sensor and folded back.

2. The wire rope flaw detector according to claim 1.

4. The ferromagnetic sheet is a coaxial cylindrical sheet.

2. The wire rope flaw detector according to claim 1.

5. the magnetic sensor is a Hall element, the ferromagnetic material has a property of absorbing the leakage magnetic flux, The magnetic sensor is provided at a position facing the outer periphery of the wire rope, and is located behind the magnetic sensor with respect to the directionality of the magnetic sensor. A wire rope flaw detector according to any one of claims 1 to 4.

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