Rope wire breakage detection device

Abstract

To provide a detection device for detecting damage to a rope based on a leakage magnetic flux of a magnetized rope while reducing false detection caused by spike noise.SOLUTION: A detection device 1 for detecting damage to a rope includes: a magnetizer 110 for magnetizing a rope to be detected as to the presence or absence of a damage; a sensor 120 for detecting a leakage magnetic flux of the rope magnetized by the magnetizer and outputting a detection signal S1 according to the detection result; a filter 120 for removing a frequency component higher than a predetermined frequency from the detection signal; and a determination unit 220 for determining the presence or absence of a damage to the rope according to the number of times the output signal of the filter crosses a predetermined threshold within a predetermined time.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a detection device for detecting breakage of a wire in a wire rope of an elevator or the like. [Background technology]

[0002] 8 is a diagram showing an example of the configuration of a wire rope 2 (hereinafter simply referred to as a "rope") that connects a car and a counterweight in an elevator. The rope 2 is configured by twisting together multiple strands 2a around a fiber core 2b, and the strands 2a are configured by twisting together multiple steel wires 2a1, each having a predetermined thickness.

[0003] Although visual inspection of the rope connecting the car and the counterweight in an elevator is required by law, it is often difficult to confirm the breakage of the wire 2a1 by visual inspection, for example, when the wire 2a1 is broken on the fiber core 2b side. Therefore, various techniques have been proposed to assist visual inspection, one example of which is the technique disclosed in Patent Document 1. Patent Document 1 discloses a technique for detecting a wire breakage by utilizing the fact that leakage magnetic flux occurs at a damaged portion caused by a wire breakage when the rope is magnetized. In Patent Document 1, the leakage magnetic flux is detected using a probe coil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-184769 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the output signal of the probe coil contains sudden or momentary noise (spike noise), the noise may be erroneously detected as damage to the rope.

[0006] An object of the present invention is to provide a detection device that detects damage to a rope based on leakage magnetic flux from a magnetized rope while reducing false detections caused by spike noise. [Means for solving the problem]

[0007] The wire breakage detection device of the present invention is a magnetizer for magnetizing a rope to be detected for damage; a sensor that detects leakage magnetic flux from the rope magnetized by the magnetizer and outputs a detection signal according to the detection result; a filter for removing frequency components higher than a predetermined frequency from the detection signal; a determination unit that determines whether or not the rope is damaged based on the number of times that the output signal of the filter crosses a predetermined threshold within a predetermined time; Equipped with.

[0008] The determination unit can determine that there is damage when the output signal of the filter crosses a predetermined threshold value two or more times within a predetermined time.

[0009] The predetermined frequency can be set according to the period of the unevenness appearing on the surface of the rope.

[0010] The rope may be a rope for suspending an elevator car.

[0011] According to the rope wire breakage detection device of the present invention, it is possible to detect damage to a rope based on leakage magnetic flux from a magnetized rope while reducing erroneous detections caused by spike noise. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a detection device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing an example of the appearance of a rope tester. [Diagram 3]FIG. 3 is a diagram showing an example of a waveform of a detection signal output from a sensor. [Figure 4] FIG. 4 is a diagram showing an example of the waveforms of a signal component corresponding to a break in a wire, a signal corresponding to unevenness in a strand, and a signal obtained by subjecting these signal components to high-pass filtering. [Diagram 5] FIG. 5 is a diagram for explaining a method for determining whether a wire has been broken by the determining unit. [Figure 6] FIG. 6 is a diagram showing an example of a signal component corresponding to spike noise and a waveform of a signal obtained by subjecting this signal component to high-pass filtering. [Figure 7] FIG. 7 is a diagram showing an example of a waveform of a signal including a signal component corresponding to a broken wire and a signal component corresponding to spike noise, and in addition, a signal component corresponding to unevenness of the strand. [Figure 8] FIG. 8 is a diagram showing an example of the structure of a rope that connects a car and a counterweight in an elevator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment in which a detection device 1 of the present invention is used to inspect a wire breakage of an elevator rope 2 will be described with reference to the drawings.

[0014] FIG. 1 is a diagram showing an example of the configuration of a detection device 1 according to an embodiment of the present invention. The detection device 1 is a device for detecting a break in a wire in a rope (for example, rope 2 shown in FIG. 8) that suspends a car in an elevator and connects the car to a counterweight. A worker who performs maintenance work on an elevator carries the detection device 1 and visits the installation site of the elevator to be inspected, and uses the detection device 1 to perform a visual inspection of the rope and to check for breaks that are difficult to see with the naked eye. As shown in FIG. 1, the detection device 1 has a rope tester 10 and a control device 20. The rope tester 10 has a magnetizer 110 and a sensor 120. The magnetizer 110 includes a permanent magnet for magnetizing the rope to be detected for a break in the wire. The sensor 120 is, for example, a Hall element. The sensor 120 detects leakage magnetic flux from the rope magnetized by the magnetizer 110, and outputs a detection signal S1 according to the detection result to the control device 20.

[0015] Fig. 2 is a perspective view showing an example of the appearance of the rope tester 10. As shown in Fig. 2, the rope tester 10 has a guide section 10a through which the rope to be tested passes in the direction indicated by the arrow Y in Fig. 2, a gripping section 10c that is held by the hand of an operator, and a main body section 10b that is provided between the guide section 10a and the gripping section 10c and that is provided with two magnetizers 110 and a sensor 120. As shown in Fig. 2, the two magnetizers 110 are arranged side by side at a predetermined interval in the direction indicated by the arrow Y, and the sensor 120 is provided between the two magnetizers 110.

[0016] The control device 20 is, for example, a personal computer, and functions as the filter 210 and the determination unit 220 by operating a processing device such as a CPU (Central Processing Unit) included in the control device 20 according to a pre-installed program. The filter 210 is a high-pass filter that passes only signal components having a frequency higher than a predetermined frequency (the lower limit frequency of the pass band of the filter 210) among the signal components of the detection signal S1 output from the sensor 120. In this embodiment, the predetermined frequency is determined according to the frequency of the unevenness of the strands on the surface of the rope to be inspected. The reason for extracting only signal components having a frequency higher than the predetermined frequency among the signal components of the detection signal S1 is as follows.

[0017] FIG. 3 is a diagram showing an example of the waveform of the detection signal S1 output from the sensor 120 when the wire breakage occurs in the rope to be inspected. The horizontal axis in FIG. 3 represents time, and the vertical axis represents the signal amplitude (similarly in FIG. 5 to FIG. 7). When the wire breakage occurs in the rope to be inspected, the detection signal S1 contains at least a signal component corresponding to the leakage magnetic flux generated by the wire breakage and a signal component corresponding to the unevenness of the strand. FIG. 4(A) is a diagram showing an example of the waveform of the signal component corresponding to the leakage magnetic flux generated by the wire breakage, and FIG. 4(B) is a diagram showing an example of the waveform of a signal including the signal component corresponding to the leakage magnetic flux generated by the wire breakage and the signal component corresponding to the unevenness of the strand. In the example shown in FIG. 4(B), the signal component corresponding to the leakage magnetic flux generated by the wire breakage is buried in the signal component corresponding to the unevenness of the strand.

[0018] Fig. 4(C) is a diagram showing an example of a waveform of a signal obtained by applying high-pass filtering by filter 210 to the signal components whose waveforms are shown in Fig. 4(A), and Fig. 4(D) is a diagram showing an example of a signal waveform of a signal obtained by applying high-pass filtering by filter 210 to a signal including a signal component corresponding to leakage magnetic flux generated by a wire break and a frequency component corresponding to unevenness of the strand. In Fig. 4(D), the amplitude of the frequency component corresponding to unevenness of the strand is smaller than that of the signal component corresponding to leakage magnetic flux generated by a wire break, in other words, the signal component corresponding to leakage magnetic flux generated by a wire break is emphasized. In other words, filter 210 is provided to extract the signal component buried in the signal corresponding to unevenness of the strand in detection signal S1.

[0019] The determination unit 220 determines whether or not the rope is damaged depending on the number of times that the output signal S2 of the filter 210 crosses a predetermined threshold within a predetermined time (0.1 to 0.3 seconds in this embodiment). In this embodiment, as shown in FIG. 5, the determination unit 220 determines that the rope is damaged due to a broken wire when the output signal S2 of the filter 210 crosses a predetermined threshold (2 in the example shown in FIG. 5) two or more times within a predetermined time. Note that the determination result by the determination unit 220 that the rope is damaged may be notified to an operator by, for example, outputting a beep or a voice message, or by blinking a light-emitting unit provided in the main body unit 10b. In addition, the detection device 1 may be permanently installed in the elevator, and the determination result by the determination unit 220 may be notified to another device via a communication line.

[0020] In this embodiment, the reason why the presence or absence of damage to the rope is determined based on the number of times that the output signal S2 of the filter 210 crosses a predetermined threshold within a specified time (0.1 to 0.3 seconds in this embodiment) is as follows: In the signal waveform of the signal obtained by applying high-pass filtering by the filter 210 to the signal component corresponding to the leakage magnetic flux generated by a broken wire, as shown in Fig. 4(C) above, two peaks appear, which correspond respectively to the rising and falling edges of the peak.

[0021] The detection signal S1 output from the sensor 120 includes a frequency component corresponding to the unevenness of the strand in addition to the signal component due to the wire breakage, and may further include white noise or spike noise. Fig. 6(A) is a diagram showing an example of a signal waveform of a signal component corresponding to the spike noise, and Fig. 6(B) is a diagram showing a signal waveform of a signal obtained by subjecting the same signal component to high-pass filtering by the filter 210. Fig. 7(A) is a diagram showing an example of a signal waveform including a signal component due to the wire breakage and a signal component corresponding to the spike noise, and Fig. 7(B) is a diagram showing an example of a signal waveform of a signal including a signal component corresponding to the unevenness of the strand, a signal component due to the wire breakage, and spike noise. Fig. 7(C) is a diagram showing a signal waveform of a signal obtained by subjecting the signal shown in Fig. 7(A) to high-pass filtering by the filter 210, and Fig. 7(D) is a diagram showing a signal waveform of a signal obtained by subjecting the signal shown in Fig. 7(B) to high-pass filtering by the filter 210. 6(B) and 7(C), the signal components corresponding to spike noise cannot be removed by high-pass filtering using filter 210. For this reason, if the presence or absence of a break in the wire is determined by comparing the amplitude of output signal S2 with a threshold value, it is not possible to distinguish between a break in the wire and noise, resulting in erroneous detection.

[0022] As shown in Fig. 4(C) above, the signal waveform of the signal obtained by subjecting the signal component corresponding to the leakage magnetic flux generated by the breakage of the wire to high-pass filtering by the filter 210 has two peaks corresponding to the rising and falling of the peak, respectively. In contrast, the signal component corresponding to the spike noise is a signal component that rises extremely steeply in one sampling period and then immediately falls, and as shown in Fig. 6(B), only one peak appears in the signal waveform of the signal obtained by subjecting the signal component corresponding to the spike noise to high-pass filtering by the filter 210. For this reason, in this embodiment, a configuration is adopted in which the presence or absence of damage to the rope is determined according to the number of times that the output signal S2 of the filter 210 crosses a predetermined threshold within a predetermined time.

[0023] According to this embodiment, it is possible to detect damage to a rope based on leakage magnetic flux from a magnetized rope while reducing false detections caused by spike noise.

[0024] In the above embodiment, an example of application of the present invention to detection of wire breakage in a rope that suspends an elevator car and connects the car to a counterweight has been described, but the rope is not limited to a rope that suspends a car, and may be a compensation rope, a governor rope, etc. Furthermore, the rope is not limited to that for elevators, and may be a long rope such as a rope that raises and lowers a hook in a crane or a rope used in a ropeway or cable car, and the detection device 1 of the present invention can also be applied to detection of wire breakage in these ropes.

[0025] Furthermore, the filter 210 and the determination unit 220 in the above embodiment are software modules that are realized by operating a computer such as a CPU according to software, but they may also be hardware modules configured with electronic circuits.

[0026] Furthermore, a program that causes the processing device included in the control device 20 to function as the filter 210 and the judgment unit 220 may be manufactured or sold separately. Then, the control device in an existing detection device may be operated in accordance with this program, causing the detection device to function as the detection device of the present invention. Also, in the above embodiment, the control device 20 is described as a device separate from the rope tester 10, but the control device 20 and the rope tester 10 may be configured as an integrated device, such as by having the control device 20 built into the rope tester 10.

[0027] The above description of the embodiment is for the purpose of explaining the present invention, and should not be interpreted as limiting the invention described in the claims or narrowing its scope. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims. [Explanation of symbols]

[0028] 1. Detection device 10 Rope Tester 110 Magnetizer 120 Sensors 20 Control device 210 Filter 220 Judgment section

Claims

1. a magnetizer for magnetizing a rope to be detected for damage; a sensor that detects leakage magnetic flux from the rope magnetized by the magnetizer and outputs a detection signal according to the detection result; a filter that passes only a signal component having a frequency higher than a predetermined frequency from the detection signal; a determination unit that determines that the rope is damaged when an output signal of the filter crosses a predetermined threshold value two or more times within a predetermined time; Equipped with The predetermined time is 0.1 to 0.3 seconds. A rope wire breakage detection device characterized by the above.

2. The predetermined frequency is set according to the period of unevenness appearing on the surface of the rope.

2. A rope wire breakage detection device according to claim 1.

3. The rope is a rope for suspending an elevator car.

3. A wire breakage detection device for a rope according to claim 1 or 2.

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