Method and system for stress monitoring of elevator steel wire ropes

Abstract

The application discloses a stress monitoring method and system of an elevator steel wire rope. The method provided by the application comprises the following steps: winding an excitation coil and an induction coil on the elevator steel wire rope respectively; providing an excitation current to the excitation coil to generate a uniform excitation magnetic field which can make the elevator steel wire rope reach saturation magnetization; acquiring an induction electromotive force signal output by the induction coil in real time under the condition that the elevator steel wire rope reaches saturation magnetization; extracting a second harmonic of the excitation current frequency in the induction electromotive force signal; and monitoring the stress of the elevator steel wire rope based on the induction electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, wherein the piezomagnetic effect model stores a mapping relationship between the induction electromotive force and mechanical force. The scheme of the embodiment of the application can improve the precision of elevator steel wire rope stress monitoring.

Description

Technical Field

[0001] This application relates to the field of electromagnetic technology, and in particular to a method and system for stress monitoring of elevator wire ropes. Background Technology

[0002] Steel wire rope (also known as steel cable or steel strand) is a flexible load-bearing component with good tensile strength, high fatigue strength, and strong impact resistance. It is a major force-bearing and force-transmitting component in elevators, lifting machinery, and other equipment. Uneven stress or failure of elevator steel wire ropes due to corrosion, overload, torsion, fatigue, and defects can easily lead to safety accidents such as elevator runaway, unexpected car movement, overshooting, and bottoming out, posing a significant threat to passenger safety. The stress state of elevator steel wire ropes plays a crucial role in assessing the safety and health of elevators. Therefore, monitoring the stress in elevator steel wire ropes is of great significance for ensuring the safe operation of elevators.

[0003] Existing methods for measuring stress in elevator wire ropes mainly include pressure sensor method, strain monitoring method, and vibration frequency method. Among them, the pressure sensor method has high accuracy in the short term, but the sensor is prone to data distortion or failure due to long-term stress and material creep. The strain monitoring method can only monitor the stress change value, not the absolute value, and is easily affected by temperature and boundary conditions, making it difficult to obtain the true stress. The vibration frequency method has low accuracy due to the influence of boundary conditions, bending stiffness, and vibration damping devices, and is only suitable for long wire ropes.

[0004] The technical problem that needs to be solved is to propose a stress monitoring method for elevator wire ropes to improve the accuracy of elevator wire rope stress measurement, thereby enabling real-time and accurate monitoring of the stress and its changes during operation, timely elimination of potential safety hazards, and ensuring the safe operation of elevators. Summary of the Invention

[0005] The purpose of this application is to provide a stress monitoring method and system for elevator wire ropes to solve the problem of low accuracy in existing wire rope stress measurement.

[0006] To solve the above-mentioned technical problems, this specification is implemented as follows:

[0007] Firstly, a method for stress monitoring of elevator wire ropes is provided, including:

[0008] An excitation coil and an induction coil are wound onto the elevator wire rope, respectively.

[0009] An excitation current is supplied to the excitation coil to generate a uniform excitation magnetic field that can saturate the elevator wire rope.

[0010] When the elevator wire rope reaches saturation magnetization, the induced electromotive force signal output by the induction coil is acquired in real time.

[0011] Extract the second harmonic of the excitation current frequency from the induced electromotive force signal;

[0012] Based on the induced electromotive force corresponding to the second harmonic and the preset piezomagnetic effect model, the stress of the elevator wire rope is monitored, wherein the piezomagnetic effect model stores the mapping relationship between the induced electromotive force and the mechanical force.

[0013] Optionally, the uniform excitation magnetic field is an alternating periodic excitation magnetic field.

[0014] Optionally, the excitation coil and the induction coil are wound on the elevator wire rope in a non-contact manner.

[0015] Optionally, based on the induced electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, the stress of the elevator wire rope is monitored, including:

[0016] Obtain the mechanical force that has a mapping relationship with the induced electromotive force corresponding to the current second harmonic from the preset piezomagnetic effect model;

[0017] Based on the obtained mechanical force and the effective cross-sectional area of ​​the elevator wire rope, the current stress of the elevator wire rope is calculated.

[0018] Optionally, before monitoring the stress of the elevator wire rope based on the induced electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, the method further includes a step of constructing the piezomagnetic effect model, specifically including:

[0019] A first excitation coil and a first induction coil are respectively wound on the target ferromagnetic material;

[0020] A first excitation current is provided to the first excitation coil to generate a uniform excitation magnetic field that can saturate the target ferromagnetic material.

[0021] Different mechanical forces are applied to the saturated magnetized target ferromagnetic material, and the first induced electromotive force signal output by the first induction coil under different mechanical forces is obtained;

[0022] The piezomagnetic effect model is established based on the second harmonic of the frequency of the first excitation current in the first induced electromotive force signal and the corresponding mechanical force.

[0023] Optionally, based on the second harmonic of the frequency of the first excitation current in the first induced electromotive force signal and the corresponding mechanical force, the piezomagnetic effect model is established, including:

[0024] Amplify the target induced electromotive force signal output by the first induction coil under the target mechanical force;

[0025] The second harmonic of the first excitation current frequency is extracted from the amplified target induced electromotive force signal using a synchronous detector.

[0026] Determine the induced electromotive force corresponding to the second harmonic;

[0027] The piezomagnetic effect model is obtained by establishing the mapping relationship between the induced electromotive force and the target mechanical force.

[0028] Optionally, determining the target induced electromotive force corresponding to the second harmonic includes:

[0029] The target induced electromotive force is obtained by measuring the second harmonic using a voltage measuring instrument.

[0030] Secondly, a stress monitoring system for elevator wire ropes is provided, comprising:

[0031] The excitation coil and the induction coil are respectively wound on the elevator wire rope;

[0032] An excitation circuit, connected to the excitation coil, is used to generate an AC excitation current of a specific amplitude and frequency and provide it to the excitation coil so that the excitation coil generates a uniform excitation magnetic field based on the AC excitation current that can saturate the elevator wire rope.

[0033] A monitoring device, connected to the induction coil, is used to acquire the induced electromotive force signal output by the induction coil in real time when the elevator wire rope reaches saturation magnetization, and to monitor the stress of the elevator wire rope based on the second harmonic of the AC excitation current frequency in the induced electromotive force signal and a preset piezomagnetic effect model, wherein the piezomagnetic effect model stores the mapping relationship between induced electromotive force and mechanical force.

[0034] Optionally, the system further includes: a clock device for outputting the secondary frequency of the AC excitation current frequency;

[0035] The monitoring device also includes:

[0036] A synchronization detector, connected to the clock device, is used to extract the second harmonic of the AC excitation current frequency from the induced electromotive force signal based on the second frequency output by the clock device.

[0037] A voltage measurement module, connected to the synchronous detector, is used to measure the second harmonic and obtain the induced electromotive force corresponding to the second harmonic;

[0038] The stress monitoring module, connected to the voltage measurement module, is used to obtain the mechanical force that has a mapping relationship with the induced electromotive force corresponding to the current second harmonic from the piezomagnetic effect model, and to calculate the current stress of the elevator wire rope based on the obtained mechanical force and the effective cross-sectional area of ​​the elevator wire rope.

[0039] Optionally, the system further includes:

[0040] A frequency divider is connected between the excitation circuit and the clock device to obtain the AC excitation current frequency by taking half of the secondary frequency output by the clock device and providing it to the excitation circuit.

[0041] In this embodiment, an excitation coil and an induction coil are wound around the elevator wire rope. An excitation current is provided to the excitation coil to generate a uniform excitation magnetic field that can saturate the elevator wire rope. When the elevator wire rope reaches saturation magnetization, the induced electromotive force signal output by the induction coil is acquired in real time. The second harmonic of the excitation current frequency in the induced electromotive force signal is extracted. Based on the induced electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, the stress of the elevator wire rope is monitored. The piezomagnetic effect model stores the mapping relationship between the induced electromotive force and the mechanical force, thereby enabling accurate measurement of stress during the operation of the elevator wire rope, improving the accuracy of elevator wire rope stress measurement, and enabling real-time and accurate monitoring of the elevator wire rope stress and its changes during operation. This allows for timely elimination of elevator safety hazards, greatly reducing the elevator failure rate, improving elevator ride comfort, and extending the service life of the traction sheave and suspension wire rope, thus effectively ensuring the safety performance of the elevator. Attached Figure Description

[0042] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0043] Figure 1 This is a flowchart illustrating the stress monitoring method for elevator wire ropes according to an embodiment of this application.

[0044] Figure 2 This is a flowchart illustrating the method for constructing the piezomagnetic effect model according to an embodiment of this application.

[0045] Figure 3a This is a schematic diagram of the magnetic induction intensity-magnetic field intensity curves of the target ferromagnetic material under different stresses.

[0046] Figure 3b This is a schematic diagram of the stress-permeability curve of the target ferromagnetic material under a uniform magnetic field.

[0047] Figure 3c This is a schematic diagram of the stress-differential permeability curve of the target ferromagnetic material under a uniform magnetic field.

[0048] Figure 4 This is a structural block diagram of the stress monitoring system for elevator wire ropes according to an embodiment of this application. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. The drawing numbers in this application are only used to distinguish the various steps in the solution and are not used to limit the execution order of the various steps. The specific execution order is subject to the description in the specification.

[0050] To address the problems existing in the prior art, embodiments of this application provide a method for stress monitoring of elevator wire ropes, such as... Figure 1 As shown, it includes the following steps:

[0051] Step 102: Wrap an excitation coil and an induction coil on the elevator wire rope, respectively;

[0052] Step 104: Provide an excitation current to the excitation coil to generate a uniform excitation magnetic field that can saturate the elevator wire rope.

[0053] Step 106: When the elevator wire rope reaches saturation magnetization, the induced electromotive force signal output by the induction coil is acquired in real time.

[0054] Step 108: Extract the second harmonic of the excitation current frequency from the induced electromotive force signal;

[0055] Step 110: Based on the induced electromotive force corresponding to the second harmonic and the preset piezomagnetic effect model, monitor the stress of the elevator wire rope, wherein the piezomagnetic effect model stores the mapping relationship between the induced electromotive force and the mechanical force.

[0056] In step 102, an excitation coil and an induction coil are wound on the elevator wire rope. The excitation coil is used to generate an excitation magnetic field through an excitation current, and the induction coil is used to generate an induced electromotive force based on the elevator wire rope magnetized by the excitation magnetic field.

[0057] In step 104, the excitation magnetic field generated by the excitation current supplied to the excitation coil is a uniform excitation magnetic field that enables the elevator wire rope to achieve saturation magnetization. Saturation magnetization refers to the maximum magnetization intensity that the elevator wire rope can achieve when magnetized in an applied excitation magnetic field. After the elevator wire rope reaches saturation magnetization, the magnetic attraction force of the elevator wire rope will not increase with the increase of the excitation magnetic field strength. A uniform excitation magnetic field refers to a magnetic field with constant magnetic field strength.

[0058] The uniform excitation magnetic field is an alternating periodic excitation magnetic field. Correspondingly, the elevator wire rope can periodically reach saturation magnetization.

[0059] Elevator wire rope is a ferromagnetic material with high magnetic permeability. When placed in an external magnetic field of a certain strength, it can be strongly magnetized and exhibit strong magnetism. When the elevator wire rope is placed in a uniform magnetic field and subjected to external mechanical force, a change in elastic energy occurs inside, causing its magnetization to reorient and resulting in a change in magnetic permeability. This change in magnetic permeability generates an equivalent magnetic field, which leads to a change in the magnetic induction intensity inside the elevator wire rope. This change in magnetic induction intensity can be reflected by the induced electromotive force (EMF). That is, there is a corresponding relationship between the mechanical force on the elevator wire rope and the induced EMF. In step 106, the induced EMF signal output by the induction coil is acquired for subsequent measurement of the mechanical force on the elevator wire rope.

[0060] The embodiments of this application are based on the induced electromotive force signal output by the elevator wire rope under stress when it reaches saturation magnetization, and the pre-constructed piezomagnetic effect model that stores the mapping relationship between induced electromotive force and mechanical force, to monitor the stress of the elevator wire rope in real time.

[0061] Specifically, the mechanical force on the elevator wire rope can be directly reflected by the second harmonic component of the excitation current frequency in the induced electromotive force signal output by the induction coil, as will be explained in detail later. Therefore, in step 108, the second harmonic of the excitation current frequency is extracted from the induced electromotive force signal. Taking the excitation current frequency as f as an example, the second harmonic with a frequency of 2f is extracted from the induced electromotive force signal.

[0062] Optionally, the excitation coil and the induction coil are wound on the elevator wire rope in a non-contact manner.

[0063] For example, the excitation coil and the induction coil can be fixedly installed at the target position of the elevator, and the elevator wire rope can pass through the corresponding turns of the excitation coil and the induction coil, without the excitation coil and the induction coil moving with the elevator wire rope.

[0064] When the elevator wire rope is saturated with a uniform excitation magnetic field, the magnitude of the magnetization intensity on the elevator wire rope can be guaranteed to remain unchanged. This can eliminate the magnetic field attenuation caused by air gaps or intervals between the elevator wire rope and the induction coil, thereby ensuring the accuracy of stress measurement.

[0065] Furthermore, the excitation coil and induction coil do not move with the elevator wire rope, so they will not interfere with the movement of the elevator wire rope or damage its structure, thus avoiding affecting the safety of elevator operation.

[0066] Optionally, the frequency range of the excitation current is 10kHz to 50kHz.

[0067] By using a relatively high excitation current frequency, interference from low-frequency environmental noise signals can be reduced, thereby improving the accuracy of stress measurement.

[0068] Specifically, in step 110, the stress of the elevator wire rope is monitored based on the induced electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, including: obtaining the mechanical force that has a mapping relationship with the induced electromotive force corresponding to the current second harmonic from the preset piezomagnetic effect model; and calculating the current stress of the elevator wire rope based on the obtained mechanical force and the effective cross-sectional area of ​​the elevator wire rope.

[0069] If the effective cross-sectional area of ​​the elevator wire rope is S, and the mechanical force obtained based on the induced electromotive force corresponding to the second harmonic is F, the stress on the elevator wire rope can be calculated as σ = F / S.

[0070] By continuously providing a uniform excitation magnetic field to the elevator wire rope through the excitation coil, which enables the elevator wire rope to reach saturation magnetization, and by acquiring the induced electromotive force of the second harmonic of the excitation current frequency in the induced electromotive force signal output by the induction coil in real time, the stress on the elevator wire rope can be determined in real time by combining the mapping relationship between induced electromotive force and mechanical force stored in the piezomagnetic effect model, thus achieving high-precision stress monitoring of the elevator wire rope.

[0071] The construction method of the piezomagnetic effect model will be described below with reference to the accompanying drawings.

[0072] Optionally, before monitoring the stress of the elevator wire rope based on the induced electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, the method further includes a step of constructing the piezomagnetic effect model, such as... Figure 2 As shown, it specifically includes:

[0073] Step 202: Wind a first excitation coil and a first induction coil onto the target ferromagnetic material, respectively;

[0074] Step 204: Provide a first excitation current to the first excitation coil to generate a uniform excitation magnetic field that can saturate the target ferromagnetic material.

[0075] Step 206: Apply different mechanical forces to the saturated magnetized target ferromagnetic material respectively, and obtain the first induced electromotive force signal output by the first induction coil under different mechanical forces;

[0076] Step 208: Based on the second harmonic of the first excitation current frequency in the first induced electromotive force signal and the corresponding mechanical force, establish the piezomagnetic effect model.

[0077] In this embodiment, a ferromagnetic material of a certain metal alloy is selected as the experimental object to study the piezomagnetic effect and construct a piezomagnetic model. Elevator steel wire rope is a ferromagnetic material; in this embodiment, the target ferromagnetic material can be elevator steel wire rope.

[0078] An excitation coil and an induction coil are wound onto the selected target ferromagnetic material. The excitation coil is used to generate an excitation magnetic field through an excitation current, and the induction coil is used to generate an induced electromotive force based on the target ferromagnetic material magnetized by the excitation magnetic field.

[0079] In this embodiment, the excitation magnetic field generated by the excitation current supplied to the excitation coil is a uniform excitation magnetic field that enables the target ferromagnetic material to achieve saturation magnetization. The uniform excitation magnetic field is an alternating periodic excitation magnetic field, and correspondingly, the target ferromagnetic material can periodically achieve saturation magnetization.

[0080] Assuming the target ferromagnetic material is in a uniform magnetic field and subjected to external mechanical force, the embodiments of this application study the variation law of magnetization intensity by changing the magnitude of the mechanical force on the target ferromagnetic material while keeping the external excitation magnetic field strength constant, and establish a specific model of nonlinear piezomagnetic effect.

[0081] The field strength permeability is defined as μ = B / H, where H is the magnetic field strength, B is the magnetic flux density, and μ is the permeability of the target ferromagnetic material. The differential permeability is Δμ = ΔB / ΔH. Both the field strength permeability μ and the differential permeability Δμ are functions of stress. The magnetic flux density B-magnetic field strength H curves of ferromagnetic materials under different stresses are shown below. Figure 3a As shown, the stress-permeability curve of a ferromagnetic material under a uniform magnetic field is as follows: Figure 3b As shown, the stress-differential permeability curve of a ferromagnetic material under a uniform magnetic field is as follows: Figure 3c As shown.

[0082] from Figure 3a As can be seen, under applied stress, the BH magnetization curve of ferromagnetic materials will change, correspondingly from... Figure 3band Figure 3c As can be seen, both its field strength permeability and differential permeability vary with different applied stresses. Furthermore, from... Figure 3b It can also be clearly seen that the field strength and permeability change nonlinearly with the applied magnetic field under different stresses.

[0083] Assuming the effective cross-sectional area of ​​the target ferromagnetic material is s, its magnetic permeability is μ, and the magnitude of the external mechanical force acting on the target ferromagnetic material is F = σS. In step 106, by applying different mechanical forces F to the saturated magnetized target ferromagnetic material, different applied stresses can be obtained. Based on these different stresses, the variation law of magnetization intensity can be studied to analyze the corresponding piezomagnetic effect and construct a piezomagnetic effect model.

[0084] In the embodiments of this application, a piezomagnetic effect model is established based on the induced electromotive force signal output by the induction coil under different mechanical forces and the corresponding mechanical forces.

[0085] The following section will explain the relationship between the induced electromotive force signal and the mechanical force by combining the principles of piezomagnetic effect and electromagnetic induction. This will provide the theoretical basis for constructing a magnetic effect model based on the induced electromotive force signal and the target ferromagnetic material, and applying it to the measurement of the mechanical force on different ferromagnetic materials, including elevator steel wire ropes.

[0086] For a target ferromagnetic material with an effective cross-sectional area of ​​S and a permeability of μ, the stress σ of the target ferromagnetic material under external mechanical force F is given by equation (1) as: σ = F / S

[0087] Due to the piezomagnetic effect, under an alternating periodic uniform excitation magnetic field of intensity H generated by the excitation coil based on the excitation current, the permeability of the target ferromagnetic material will change, and the equivalent magnetic field H generated by the change in permeability will... σ The stress σ experienced by the target ferromagnetic material has the following relationship as shown in formula (2):

[0088]

[0089] Where, λ s M is the magnetostriction constant. s denoted as saturation magnetization, M as magnetization, and μ0 as free permeability.

[0090] Assume the angular frequency of the excitation current supplied to the excitation coil is ω = 2πf, and the amplitude of the uniform excitation magnetic field is H. m Then, the magnetic induction intensity B inside the target ferromagnetic material at this time is:

[0091] B=μ(H+H σ )=μ(H m sinωt+Hσ Equation (3)

[0092] Where H is the intensity of the uniform excitation magnetic field, and μ is the permeability.

[0093] According to Faraday's law of electromagnetic induction, assuming the number of turns in the induction coil is N, the induced electromotive force E generated in the induction coil is:

[0094]

[0095] For equation (4), it can be seen that the main factor affecting the output of induced electromotive force is the differential of permeability with respect to time.

[0096] Since the uniform excitation magnetic field is a function of time, the permeability is also a function of time. Because the instantaneous value of the uniform excitation magnetic field is directional, while the permeability varies with the absolute value of the uniform excitation magnetic field and is not directional, the permeability of the target ferromagnetic material is an even function of time. Expanding the periodically varying permeability μ(t) using a Fourier series yields:

[0097]

[0098] Where, μ d μ is the DC component of the permeability. i The amplitude of the second harmonic component of the excitation current frequency at different times is given by equation (5). Substituting equation (5) into equation (4), the induced electromotive force E can be expressed as:

[0099]

[0100] From equation (6), it can be concluded that the induced electromotive force output by the induction coil includes the intensity H caused by stress σ. σ The equivalent magnetic field and its strength are H m The information of the uniform excitation magnetic field, the induced electromotive force signal and the mechanical force that causes the equivalent magnetic field are related.

[0101] From equation (6), it can be seen that when the strength H of the equivalent magnetic field is... σ When the value is zero, the induced electromotive force signal output by the induction coil only contains a value of H. m The information from the uniform excitation magnetic field means that the output induced electromotive force signal contains only odd harmonic components of the excitation current frequency. When the strength H of the equivalent magnetic field is... σ When the value is not zero, the induced electromotive force signal output by the induction coil includes both a strength of H and a value of H. m The information of the uniform excitation magnetic field also includes the information of the equivalent magnetic field, and the information of the equivalent magnetic field in the frequency domain is the even harmonic of the frequency f of the excitation current.

[0102] Therefore, a piezomagnetic effect model can be established based on the target even harmonic of the excitation current frequency in the induced electromotive force signal and the corresponding mechanical force.

[0103] In this embodiment, the sensitive process of the target ferromagnetic material is a stress-magnetic parameter-induced electromotive force conversion. The even-order harmonics output by the induction coil can characterize the stress magnitude of the target ferromagnetic material under mechanical force. The amplitude of the even-order harmonics output by the induction coil decreases with increasing order, meaning the second harmonic has the largest amplitude. Furthermore, under the saturation state of the target ferromagnetic material, other higher harmonics are more difficult to extract due to their poor stability. Compared to other higher harmonics, the second harmonic has the best stability and is easier to extract.

[0104] Optionally, the target even harmonic of the excitation current frequency is the second harmonic. That is, a piezomagnetic effect model is established by using the second harmonic of the excitation current frequency in the induced electromotive force signal and the corresponding mechanical force. Since the second harmonic of the uniform excitation magnetic field in the induced electromotive force signal is detected, the signal-to-noise ratio is high, and high-precision stress measurement can be achieved.

[0105] Specifically, based on the second harmonic of the first excitation current frequency in the first induced electromotive force signal and the corresponding mechanical force, the piezomagnetic effect model is established, including: amplifying the target induced electromotive force signal output by the first induction coil under the target mechanical force; extracting the second harmonic of the first excitation current frequency from the amplified target induced electromotive force signal through a synchronous detector; determining the induced electromotive force corresponding to the second harmonic; and obtaining the piezomagnetic effect model by establishing a mapping relationship between the induced electromotive force and the target mechanical force.

[0106] In this embodiment, when the target ferromagnetic material is subjected to external mechanical force, the permeability of the target ferromagnetic material changes, thereby generating an equivalent magnetic field. As mentioned above, the induced electromotive force signal output by the induction coil contains information about the uniform excitation magnetic field and the equivalent magnetic field, and the second harmonic component of the excitation current frequency in the induced electromotive force signal can better reflect the induced electromotive force generated by the equivalent magnetic field.

[0107] The induced electromotive force (EMF) signal output by the induction coil contains many components, so it can be pre-amplified first. For example, a preamplifier can amplify the second harmonic of the excitation current frequency in the induced EMF signal while strongly suppressing signals of other frequencies. Then, a synchronous detector can extract the second harmonic component of the excitation current frequency from the amplified induced EMF signal.

[0108] Taking an excitation current frequency of f as an example, the synchronous detector needs to extract the second harmonic with a frequency of 2f from the induced electromotive force signal. Optionally, the excitation current frequency range is 10kHz to 50kHz.

[0109] By using a higher excitation current frequency, interference from low-frequency environmental noise signals can be reduced, thereby improving the accuracy of stress measurement.

[0110] From equation (6), it can be seen that the second harmonic component of the excitation current frequency can be extracted from the amplified target induced electromotive force signal, i.e. In the above, let i = 1, the induced electromotive force corresponding to the second harmonic is NSH. σ ωμ1sin 2ωt.

[0111] Thus, by applying different mechanical forces to the target ferromagnetic material and detecting the second harmonic of the excitation current frequency in the induced electromotive force signal output by the induction coil after each application of different mechanical forces, the corresponding induced electromotive force can be obtained. The mapping relationship between the induced electromotive force and the corresponding mechanical force is then established and stored, resulting in a piezomagnetic effect model.

[0112] In the embodiments of this application, when the stress of the target ferromagnetic material changes (torsion, tension, or compression), its magnetic property parameters (e.g., permeability) will also change accordingly. By studying the relationship between the stress on the target ferromagnetic material and its magnetic property parameters, a piezomagnetic effect model can be established, enabling stress measurement of different ferromagnetic materials.

[0113] By winding an excitation coil and an induction coil around the target ferromagnetic material and providing an excitation current to the excitation coil, a uniform excitation magnetic field that can saturate the target ferromagnetic material is generated. Different mechanical forces are applied to the saturated magnetized target ferromagnetic material, and the induced electromotive force signals output by the induction coil under different mechanical forces are obtained. Based on the induced electromotive force signals and the corresponding mechanical forces, a piezomagnetic effect model is established, which can realize the accurate measurement of the stress of ferromagnetic materials.

[0114] The piezomagnetic effect model can be applied to stress monitoring of elevator wire ropes. In step 108, based on the induced electromotive force signal output from the induction coil wound on the elevator wire rope, the second harmonic of the excitation current frequency and its corresponding induced electromotive force are determined. Combined with the piezomagnetic effect model constructed above, the stress of the elevator wire rope is monitored in real time.

[0115] In this embodiment, an excitation coil and an induction coil are wound around the elevator wire rope. An excitation current is provided to the excitation coil to generate a uniform excitation magnetic field that can saturate the elevator wire rope. When the elevator wire rope reaches saturation magnetization, the induced electromotive force signal output by the induction coil is acquired in real time. The second harmonic of the excitation current frequency in the induced electromotive force signal is extracted. Based on the induced electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, the stress of the elevator wire rope is monitored. The piezomagnetic effect model stores the mapping relationship between the induced electromotive force and the mechanical force, thereby enabling accurate measurement of stress during the operation of the elevator wire rope, improving the accuracy of elevator wire rope stress measurement, and enabling real-time and accurate monitoring of the elevator wire rope stress and its changes during operation. This allows for timely elimination of elevator safety hazards, greatly reducing the elevator failure rate, improving elevator ride comfort, and extending the service life of the traction sheave and suspension wire rope, thus effectively ensuring the safety performance of the elevator.

[0116] Optionally, embodiments of this application also provide a stress monitoring system for elevator wire ropes. Figure 4 This is a structural block diagram of the stress monitoring system for elevator wire ropes according to an embodiment of this application.

[0117] like Figure 4 As shown, the stress monitoring system for elevator wire ropes includes:

[0118] The excitation coil 20 and the induction coil 30 are respectively wound on the elevator wire rope 10;

[0119] Excitation circuit 40, connected to excitation coil 20, is used to generate an AC excitation current with a specific amplitude and frequency and provide it to excitation coil 20, so that excitation coil 20 generates a uniform excitation magnetic field based on the AC excitation current that can saturate the elevator wire rope 10.

[0120] The monitoring device, connected to the induction coil 30, is used to acquire the induced electromotive force signal output by the induction coil 30 in real time when the elevator wire rope 10 reaches saturation magnetization, and to monitor the stress of the elevator wire rope 10 based on the second harmonic of the AC excitation current frequency in the induced electromotive force signal and a preset piezomagnetic effect model, wherein the piezomagnetic effect model stores the mapping relationship between induced electromotive force and mechanical force.

[0121] Optionally, the system further includes: a clock device 70 for outputting the secondary frequency of the AC excitation current frequency;

[0122] The monitoring device also includes:

[0123] A synchronization detector 50, connected to the clock device 70, is used to extract the second harmonic of the AC excitation current frequency from the induced electromotive force signal based on the second frequency output by the clock device 70.

[0124] The voltage measurement module 60 is connected to the synchronous detector 50 and is used to measure the second harmonic and obtain the induced electromotive force corresponding to the second harmonic.

[0125] The stress monitoring module 90, connected to the voltage measurement module 60, is used to obtain the mechanical force that has a mapping relationship with the induced electromotive force corresponding to the current second harmonic from the piezomagnetic effect model, and to calculate the current stress of the elevator wire rope 10 based on the obtained mechanical force and the effective cross-sectional area of ​​the elevator wire rope 10.

[0126] like Figure 4 As shown, the clock device 70 can, for example, output a frequency of 20 kHz, where the AC excitation current frequency f is 10 kHz, and the 20 kHz frequency is twice the AC excitation current frequency. Therefore, the 20 kHz frequency can be provided to the synchronization detector 50 to extract the second harmonic of the AC excitation current frequency f corresponding to the 2f frequency in the induced electromotive force signal output from the induction coil 30.

[0127] Optionally, the system further includes: a frequency divider 80 connected between the excitation circuit 40 and the clock device 70, used to obtain the AC excitation current frequency f by taking half of the secondary frequency output by the clock device 70, and providing it to the excitation circuit 40.

[0128] The 20kHz frequency output from the clock device 70 is processed by the frequency divider 80 to provide a 10kHz frequency as the reference frequency for the excitation current, thereby generating a uniform excitation magnetic field in the excitation coil 20.

[0129] Therefore, the frequency output by the same clock device 70 can be used simultaneously as the second harmonic of the excitation current frequency used to generate the excitation magnetic field for the excitation coil and to extract the induced electromotive force signal output by the induction coil.

[0130] Each component of the elevator wire rope stress monitoring system in this application embodiment can correspondingly implement each process of the above-described elevator wire rope stress monitoring method embodiment. To avoid repetition, it will not be described again here.

[0131] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0132] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0133] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for stress monitoring of elevator wire ropes, characterized in that, include: An excitation coil and an induction coil are wound onto the elevator wire rope, respectively. An excitation current is supplied to the excitation coil to generate a uniform excitation magnetic field that can saturate the elevator wire rope. When the elevator wire rope reaches saturation magnetization, the induced electromotive force signal output by the induction coil is acquired in real time. Extract the second harmonic of the excitation current frequency in the induced electromotive force signal, wherein the even harmonic output by the induction coil characterizes the stress magnitude of the elevator wire rope when subjected to mechanical force, and the second harmonic is the even harmonic corresponding to the maximum amplitude. Based on the induced electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, the stress of the elevator wire rope is monitored. The piezomagnetic effect model stores the mapping relationship between the induced electromotive force and the mechanical force. The stress of the elevator wire rope is the ratio of the mechanical force mapped by the induced electromotive force corresponding to the second harmonic to the effective cross-sectional area of ​​the elevator wire rope.

2. The method as described in claim 1, characterized in that, The uniform excitation magnetic field is an alternating periodic excitation magnetic field.

3. The method as described in claim 1, characterized in that, The excitation coil and the induction coil are wound on the elevator wire rope in a non-contact manner.

4. The method as described in claim 1, characterized in that, Based on the induced electromotive force corresponding to the second harmonic and a preset piezomagnetic effect model, the stress of the elevator wire rope is monitored, including: Obtain the mechanical force that has a mapping relationship with the induced electromotive force corresponding to the current second harmonic from the preset piezomagnetic effect model; Based on the obtained mechanical force and the effective cross-sectional area of ​​the elevator wire rope, the current stress of the elevator wire rope is calculated.

5. The method as described in claim 1, characterized in that, Before monitoring the stress of the elevator wire rope based on the induced electromotive force corresponding to the second harmonic and the preset piezomagnetic effect model, the process also includes the step of constructing the piezomagnetic effect model, specifically including: A first excitation coil and a first induction coil are respectively wound on the target ferromagnetic material; A first excitation current is provided to the first excitation coil to generate a uniform excitation magnetic field that can saturate the target ferromagnetic material. Different mechanical forces are applied to the saturated magnetized target ferromagnetic material, and the first induced electromotive force signal output by the first induction coil under different mechanical forces is obtained; The piezomagnetic effect model is established based on the second harmonic of the frequency of the first excitation current in the first induced electromotive force signal and the corresponding mechanical force.

6. The method as described in claim 5, characterized in that, Based on the second harmonic of the first excitation current frequency in the first induced electromotive force signal and the corresponding mechanical force, the piezomagnetic effect model is established, including: Amplify the target induced electromotive force signal output by the first induction coil under the target mechanical force; The second harmonic of the first excitation current frequency is extracted from the amplified target induced electromotive force signal using a synchronous detector. Determine the induced electromotive force corresponding to the second harmonic; The piezomagnetic effect model is obtained by establishing the mapping relationship between the induced electromotive force and the target mechanical force.

7. The method as described in claim 6, characterized in that, Determining the target induced electromotive force corresponding to the second harmonic includes: The target induced electromotive force is obtained by measuring the second harmonic using a voltage measuring instrument.

8. A stress monitoring system for elevator wire ropes, characterized in that, include: The excitation coil and the induction coil are respectively wound on the elevator wire rope; An excitation circuit, connected to the excitation coil, is used to generate an AC excitation current of a specific amplitude and frequency and provide it to the excitation coil so that the excitation coil generates a uniform excitation magnetic field based on the AC excitation current that can saturate the elevator wire rope. A monitoring device, connected to the induction coil, is used to acquire the induced electromotive force signal output by the induction coil in real time when the elevator wire rope reaches saturation magnetization. Based on the second harmonic of the AC excitation current frequency in the induced electromotive force signal and a preset piezomagnetic effect model, the device monitors the stress of the elevator wire rope. The even harmonic output by the induction coil represents the magnitude of the stress of the elevator wire rope when subjected to mechanical force. The second harmonic is the even harmonic corresponding to the maximum amplitude. The piezomagnetic effect model stores the mapping relationship between induced electromotive force and mechanical force. The stress of the elevator wire rope is the ratio of the mechanical force mapped by the induced electromotive force corresponding to the second harmonic to the effective cross-sectional area of ​​the elevator wire rope.

9. The system as described in claim 8, characterized in that, The system further includes: a clock device for outputting the secondary frequency of the AC excitation current frequency; The monitoring device also includes: A synchronization detector, connected to the clock device, is used to extract the second harmonic of the AC excitation current frequency from the induced electromotive force signal based on the second frequency output by the clock device. A voltage measurement module, connected to the synchronous detector, is used to measure the second harmonic and obtain the induced electromotive force corresponding to the second harmonic; The stress monitoring module, connected to the voltage measurement module, is used to obtain the mechanical force that has a mapping relationship with the induced electromotive force corresponding to the current second harmonic from the piezomagnetic effect model, and to calculate the current stress of the elevator wire rope based on the obtained mechanical force and the effective cross-sectional area of ​​the elevator wire rope.

10. The system as described in claim 9, characterized in that, The system also includes: A frequency divider is connected between the excitation circuit and the clock device to obtain the AC excitation current frequency by taking half of the secondary frequency output by the clock device and providing it to the excitation circuit.

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