JP7670096B2 - Rope wire breakage detection device - Google Patents

Description

The present invention relates to a detection device that detects breakage of wires in wire ropes of elevators, etc.

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

Visual inspection of the rope connecting the car and counterweight in an elevator is required by law, but in many cases, for example, when the wire 2a1 is broken on the fiber core 2b side, it is difficult to confirm the break in the wire 2a1 through visual inspection. As a result, various techniques have been proposed to assist with visual inspection, one example of which is the technique disclosed in Patent Document 1. Patent Document 1 discloses a technique for detecting a wire break by utilizing the fact that when the rope is magnetized, leakage magnetic flux is generated at the damaged area due to a broken wire. In Patent Document 1, the leakage magnetic flux is detected using a probe coil.

JP 2009-184769 A

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

The 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.

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.

The determination unit can determine that damage exists when the output signal of the filter crosses a predetermined threshold value two or more times within a specified time.

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

The rope can be a rope for suspending an elevator car.

The rope wire breakage detection device of the present invention can detect damage to a rope based on leakage magnetic flux from a magnetized rope while reducing false detections caused by spike noise.

FIG. 1 is a diagram showing an example of the configuration of a detection device according to an embodiment of the present invention. FIG. 2 is a perspective view showing an example of the appearance of a rope tester. FIG. 3 is a diagram showing an example of a waveform of a detection signal output from a sensor. 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. FIG. 5 is a diagram for explaining a method for determining whether a wire has been broken by the determining unit. 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. 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. FIG. 8 is a diagram showing an example of the structure of a rope that connects a car and a counterweight in an elevator.

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

Figure 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 Figure 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 Figure 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 wire breakage. 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.

Figure 2 is a perspective view showing an example of the appearance of the rope tester 10. As shown in Figure 2, the rope tester 10 has a guide section 10a that passes the rope to be tested in the direction indicated by the arrow Y in Figure 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 Figure 2, the two magnetizers 110 are arranged side by side at a predetermined interval in the direction of the arrow Y, and the sensor 120 is provided between the two magnetizers 110.

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) from 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 from the signal components of the detection signal S1 is as follows.

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

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

The determination unit 220 determines whether the rope is damaged or not depending 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). 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 specified threshold (2 in the example shown in FIG. 5) two or more times within a specified time. The result of the determination by the determination unit 220 that there is damage 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. The detection device 1 may also be permanently installed in the elevator, and the result of the determination by the determination unit 220 may be notified to another device via a communication line.

In this embodiment, the reason for determining whether or not the rope is damaged 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 to the signal component corresponding to the leakage magnetic flux generated by a broken wire, as shown in Figure 4 (C) above, two peaks appear, which correspond to the rising and falling edges of the peak.

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 including a signal component corresponding to the unevenness of the strand, a signal component due to the wire breakage, and a 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. As is clear from Figures 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 wire break is determined by comparing the amplitude of output signal S2 with a threshold value, it is not possible to distinguish between a broken wire and noise, resulting in a false detection.

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

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.

In the above embodiment, an example of application of the present invention to detecting wire breakage in the rope that suspends the elevator car and connects the car to the counterweight has been described, but the rope may not only be a rope that suspends the car, but also a compensation rope, a governor rope, etc. Furthermore, the rope is not limited to that for elevators, but 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 detecting wire breakage in these ropes.

In addition, the filter 210 and the determination unit 220 in the above embodiment were software modules implemented by operating a computer such as a CPU according to software, but they may also be hardware modules configured with electronic circuits.

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, by operating the control device in an existing detection device according to this program, the detection device may 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 also be configured as an integrated device, such as by having the control device 20 built into the rope tester 10.

The above explanation 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.

1 Detection device 10 Rope tester 110 Magnetizer 120 Sensor 20 Control device 210 Filter 220 Judgment unit

Claims (3)

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. 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 . 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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