Electric hoisting machine and electric hoisting system

Abstract

In electric hoisting machines, the degree of deterioration of mechanical components constituting the hoisting device is estimated with high precision, regardless of the usage pattern at the site. [Solution] The sampling period for the current flowing to the hoisting motor is updated based on the steady-state operating time and the motor drive frequency.

Description

Technical Field

[0001] The present invention relates to an electric hoist and an electric hoisting system.

Background Art

[0002] A hoist, which is a type of electric hoist, is an industrial machine that raises a suspended load hung from a crane hook attached to a wire rope by winding up the wire rope with a winding device equipped with a motor, and lowers the load by unwinding the wire rope.

[0003] The hoist has a rotational force transmission unit that transmits the rotational force of the motor to the winding device that actually raises and lowers the suspended load. Specifically, as the configuration of the rotational force transmission unit, for example, a spline shaft is connected to the output shaft of the winding motor, which outputs the rotational force at a constant rotational speed, then reduces the rotational speed with a reduction gear, and transmits a large torque to the winding device.

[0004] Here, the spline shaft is a shaft used for transmitting rotational force. One shaft (spline) has a shape in which teeth of a gear are machined on the outer circumference. The other shaft (boss) has a shape in which concave and convex holes for inserting the spline gear are machined. By fitting the spline into the boss, it becomes possible to transmit the rotational force.

[0005] Since the gears are fitted together, compared with a power transmission mechanism such as a coupling, there is an advantage that slippage does not occur when a large rotational force acts, so it is often used for applications that transmit a large rotational force. Also, there is a minute gap because the spline is axially fitted into the boss. Therefore, since it is movable in the axial direction, it is possible to absorb the movement even when the spline side or the boss side is slightly displaced in the axial direction.

[0006] As mentioned above, in a hoist, if slippage occurs in the rotational force transmission section while lifting a suspended load, there is a risk that the suspended load may tilt. Therefore, to prevent slippage, spline shafts or reduction gears are used in the section that transmits the rotational force of the motor to the hoisting mechanism. In this case, for example, there is a tiny gap between the spline and the boss, so when the motor rotates, the gear on the outer circumference of the spline makes uneven contact with the grooves in the boss.

[0007] In the case of a hoist, the motor rotates in different directions during the lifting and lowering of the load, resulting in uneven contact between the tooth surfaces of the gears during forward and reverse rotation. Over time, prolonged use of a hoist can cause the spline tooth surfaces to gradually wear down and deteriorate, potentially leading to poor transmission of rotational force. Therefore, it is crucial to regularly inspect the spline shaft to check its condition.

[0008] Since the teeth of a spline are fitted into a boss, it is impossible to visually inspect them directly. Therefore, it is necessary to remove the spline from the boss and inspect it openly for inspection. A method for checking the deterioration state of a spline without removing it from the boss is known, as described in Patent Document 1. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2023-115945 [Overview of the project] [Problems that the invention aims to solve]

[0010] According to Patent Document 1, the device includes a current measuring unit that measures the current of an electric motor that rotates a spline shaft, a frequency component calculation unit that performs frequency analysis on the current measured by the current measuring unit to calculate specific frequency components, and a wear state estimation unit that estimates the wear state of the gears of the spline shaft based on the specific frequency components calculated by the frequency component calculation unit.

[0011] This makes it possible to estimate the wear and deterioration state of the gears on the spline shaft based on the electric motor current. As a result, opening the spline for inspection becomes unnecessary, and since the current sensor is installed on the cable supplying power to the electric motor, there is no need to open the area near the spline shaft even if a sensor malfunction occurs.

[0012] The above-mentioned Patent Document 1 describes a technology for estimating the wear of a spline shaft incorporated into electric hoisting machines such as hoists and cranes based on the current flowing through the electric motor used for hoisting. However, in order to perform this wear estimation with high accuracy, current data detected with required data specifications (for example, the time width of the data and the sampling period) is necessary.

[0013] In contrast, with hoisting machines such as hoists and cranes, the usage varies depending on the factory where they are installed, and the time and speed at which the suspended load is raised and lowered are not uniformly determined.

[0014] Therefore, in order to accurately estimate the wear of mechanical parts such as spline shafts and reduction gears incorporated into hoisting machines like hoists and cranes, it is necessary to understand the usage patterns at the factory or other site where they are used and to update the current detection specifications of the electric hoisting motor accordingly.

[0015] The objective of the present invention is to estimate the degree of deterioration of mechanical components constituting a hoisting device with high precision, regardless of the usage pattern at the site where the electric hoisting machine is used. [Means for solving the problem]

[0016] An electric hoisting machine according to one aspect of the present invention comprises a hoisting motor, a power supply for supplying power to the hoisting motor, a hoisting device for raising and lowering a suspended load, and a diagnostic device for detecting the degree of deterioration of mechanical components constituting the hoisting device based on the current flowing through the hoisting motor, wherein the diagnostic device comprises a current detection unit for detecting the current flowing through the hoisting motor, a steady-state interval determination unit for determining the steady-state operating time when raising and lowering the suspended load based on the current flowing through the hoisting motor, a drive frequency detection unit for detecting the drive frequency of the hoisting motor when raising and lowering the suspended load based on the current flowing through the hoisting motor, and a sampling period determination unit for updating the sampling period of the current flowing through the hoisting motor based on the steady-state operating time and the motor drive frequency, wherein the current detection unit detects the current flowing through the hoisting motor based on the updated sampling period. [Effects of the Invention]

[0017] According to one aspect of the present invention, in an electric hoisting machine, the degree of deterioration of the mechanical components constituting the hoisting device can be estimated with high accuracy, regardless of the usage pattern at the site where it is used. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram of the electric hoisting machine of Example 1. [Figure 2] This figure shows the shape and condition of the cross-section of a spline shaft. [Figure 3] This figure shows an example of a hoist motor current waveform. [Figure 4] This figure shows an example of the frequency analysis results for motor current. [Figure 5] This diagram shows the detailed configuration of the steady-state interval determination unit. [Figure 6A] This is a schematic diagram of the electric hoisting machine of Example 2. [Figure 6B] This is a schematic diagram of the electric hoisting machine of Example 3. [Figure 7] This is a schematic diagram showing the relationship between the degree of wear and deterioration. [Figure 8] It is a schematic diagram showing the transitional change of the relationship between the wear degree and the deterioration degree when the operating conditions are changed during operation. [Figure 9] It is a schematic configuration diagram of the electric hoist of Example 4. [Figure 10] It is a diagram showing an example of the occurrence frequency of the operating time for raising and lowering the suspended load. [Figure 11] It is a schematic configuration diagram of the electric hoisting system of Example 5.

Mode for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment

[0020] FIG. 1 shows a schematic configuration diagram of the electric hoist (for example, a hoist) of Example 1.

[0021] A three-phase power supply 2 corresponding to commercial power or an inverter or the like is connected to the hoisting motor 1. By applying a three-phase voltage to the hoisting motor 1, forward and reverse rotations are performed, and the hoisting device 3 winds up and winds down a suspended load (not shown in FIG. 1).

[0022] In this configuration, between the hoisting motor 1 and the hoisting device 3, a spline shaft 4 for transmitting the rotational force from the hoisting motor 1 to the outside and a reduction gear 5 for reducing the rotational speed of the hoisting motor 1 and amplifying the torque are provided. Further, a current sensor 7 for measuring current is provided in at least one phase of the electric wire 6 that electrically connects the three-phase power supply 2 of the hoisting motor 1. The current data measured by the current sensor 7 is input to the diagnostic device 10 to diagnose the states of the spline shaft 4 and the reduction gear 5.

[0023] In Figure 1, an example is shown where the current sensor 7 is installed on the wire 6. However, if the three-phase power supply 2 is an inverter, it is also possible to use information such as the current feedback value input to the inverter instead. Furthermore, the diagnostic device 10 can also be implemented on a microcontroller or other computationally capable component located inside the inverter.

[0024] The diagnostic device 10 includes a current detection unit 42 that detects the current flowing through the hoisting motor 1, a steady-state interval determination unit 43 that determines the steady-state operating time when the suspended load is raised and lowered based on the current flowing through the hoisting motor 1, a drive frequency detection unit 44 that detects the drive frequency of the hoisting motor 1 when the suspended load is raised and lowered based on the current flowing through the hoisting motor 1, and a sampling period determination unit 45 that updates the sampling period of the current flowing through the hoisting motor 1 based on the steady-state operating time and motor drive frequency. The current detection unit 42 detects the current flowing through the hoisting motor 1 based on the updated sampling period.

[0025] Furthermore, the diagnostic device 10 includes a feature quantity calculation unit 40 that calculates predetermined feature quantities based on the current flowing through the hoisting motor 1, and a degradation degree calculation unit 41 that calculates the degree of degradation based on the feature quantities.

[0026] Here, Figure 2(a) shows a diagram simulating a cross-section of a spline axis.

[0027] Note that the tooth shape is just an example and is not limited to this. As shown in the figure, the spline 20 is fitted into the boss 30 from the axial direction. A small gap G exists to allow for fitting. The spline 20 has teeth 21 provided at regular intervals in the circumferential direction.

[0028] Figure 2(b) shows the rotation of the spline 20, which is the drive shaft. When the spline 20 rotates in the direction of arrow F, the tooth surface 21f of the tooth 21 comes into contact with the boss, and rotational force is transmitted from the spline 20 to the boss 30. On the other hand, when the spline 20 rotates in the opposite direction to arrow F, the tooth surface 21f comes into contact with the boss, and rotational force in the opposite direction to arrow F is transmitted from the boss 30 to the spline 20.

[0029] In the case of a hoist, for example, when it rotates in the direction of arrow F, the suspended load is raised, and when it rotates in the opposite direction of arrow F, the suspended load is lowered. Repeating these actions causes the tooth surface 21f to wear down or become damaged, leading to wear progression. As the wear of the tooth surface 21f progresses, the tooth 21 deteriorates, resulting in poor transmission of rotational force. Therefore, it is necessary to detect the wear (degree of deterioration; hereafter, wear is referred to as the degree of deterioration) of the tooth 21 before any abnormalities occur.

[0030] Next, we will explain an example of a method for calculating the degree of deterioration of the teeth on spline axis 4.

[0031] First, Figure 3 shows an example of the current waveform flowing through the hoisting motor 1 when a suspended load is raised or lowered by an electric hoisting machine (for example, a hoist).

[0032] As shown in Figure 3, an excessive current flows during the transient state at the beginning of operation, then it transitions to a steady state where a constant current flows according to the weight of the suspended load, and then stops. The current in section T flowing through the hoisting motor 1 during this operation is acquired by the current sensor 7.

[0033] This is because, in order to estimate the degree of degradation of the spline shaft 4 described later, the magnitude of specific frequency components is used, and therefore current data from the "steady-state operation section" where the current amplitude and drive frequency of the hoisting motor 1 are constant are used. Next, frequency analysis such as Fast Fourier Transform (FFT) is performed on the detected current in section T to calculate the frequency spectrum.

[0034] Regarding the method for extracting steady-state current data in the frequency analysis here, as shown in Figure 3, the frequency analysis may be performed using data from the entire T interval. However, depending on the configuration of the computing device performing the analysis, it is also possible to divide the data into smaller intervals such as Δt as shown in Figure 3 and perform the frequency analysis in each interval.

[0035] In particular, when the diagnostic device 10 is configured with a computing device using a microprocessor or the like, the number of data to be processed is limited, so it is effective to perform calculations using the data width of the small interval Δt as described above.

[0036] Figure 4 shows an example of the results obtained when the frequency analysis described above is performed.

[0037] As shown in Figure 4, when motor current is frequency-analyzed, the frequency spectrum of the current has a peak at the fundamental frequency of the current, and then decreases from there to the lower and higher frequency sides.

[0038] From this frequency spectrum, the spectrum of a specific frequency is extracted and stored as parameter P. In the example of diagnosing the spline shaft of a hoist, the value of the rotational frequency component that appears as a sideband of the fundamental frequency of the current is extracted as parameter P. In addition to spline shafts, a similar frequency analysis is used to estimate the degree of wear of reduction gears incorporated into hoisting machines.

[0039] The frequency components (parameter P) used in this process will be different from the parameter P used to estimate the degree of deterioration of the spline shaft 4 due to the relationship with the reduction ratio. In this embodiment, deterioration is diagnosed by focusing on the change in the distribution of parameter P due to the effect of rotational wobble caused by spline shaft wear. This change is defined as a feature quantity.

[0040] The part that calculates these features is the feature calculation unit 40 located within the diagnostic device 10. Furthermore, the degree of deterioration of the spline axis 4 is determined by the degree of change from the normal state of the aforementioned features. The part that calculates this degree of deterioration is the deterioration degree calculation unit 41 located within the diagnostic device 10. As for the method of calculating this degree of deterioration, for example, statistical quantities of information related to the distribution of parameter P are extracted as features.

[0041] Specific examples of statistics include, in the frequency distribution of a parameter P, the maximum, minimum, and mean values, as well as the median, which represents the point where the areas under the distribution are equal, and the mode, which is the value that occurs most frequently.

[0042] Furthermore, statistics that represent the spread of the distribution, such as range (the difference between the maximum and minimum values), variance, and standard deviation, may also be used. In addition, statistics that represent the shape of the frequency distribution, such as skewness and kurtosis, can also be used. Moreover, the number of features is not limited to one; multiple statistics may be used, or a new evaluation metric calculated from multiple statistics may be used as a feature.

[0043] The above is an overview of the method for calculating the degree of deterioration of the spline shaft 4 incorporated into an electric hoisting machine (for example, a hoist). As explained above, in order to calculate the degree of deterioration, current data from the hoisting motor 1 is acquired, and frequency analysis is performed on that data.

[0044] Generally, frequency analysis requires acquiring data within a predetermined time interval. In contrast, the operating time for raising and lowering loads in electric hoists and cranes varies depending on the location, environment, and type of load, and cannot be determined uniformly, even roughly.

[0045] Therefore, when calculating the degree of deterioration of spline shafts 4 and reduction gears 5 (mechanical components that make up the hoisting device) incorporated into electric hoisting machines (for example, hoists), it is necessary to determine the time width and sampling time of the current data required for calculating the degree of deterioration each time the equipment is installed in a factory or other location.

[0046] To solve this problem, in Embodiment 1 of the present invention, as shown in Figure 1, the diagnostic device 10 for the electric hoist is provided with means for determining the detection conditions for current data necessary for calculating the degree of deterioration and for detecting current data accordingly. Specifically, this means is configured to include a current detection unit 42, a steady-state interval determination unit 43, a drive frequency detection unit 44, and a sampling period determination unit 45.

[0047] The operation of the electric hoisting machine in Example 1 will be described below.

[0048] First, as described above, the diagnostic device 10 performs frequency analysis using the current data of the hoisting motor 1. In this frequency analysis, the magnitude of the frequency band components corresponding to the part to be diagnosed (here, the spline shaft 4 is assumed) is calculated, and the frequency resolution Δf and current amplitude resolution ΔI required for the diagnosis are determined in advance.

[0049] The respective resolutions are expressed by (Equation 1) and (Equation 2) below.

[0050] [Mathematics 1] Δf = fs / N (where fs is the sampling frequency and N is the number of data points)

[0051] [Math 2] ΔI = A × f1 / fs (where A is the current amplitude and f1 is the motor drive frequency) Here, the number of data points N is often predetermined by the processing speed and memory capacity of the diagnostic device 10, and the required range of the sampling period fs is determined from the required resolution.

[0052] On the other hand, the time width T of the current data is determined to fall within the "steady-state operating time" under the following conditions (Equation 3), such that the motor drive frequency and current amplitude remain constant.

[0053] [Math 3] T = x / f1 (where x is any integer) From (Equation 2) and (Equation 3) above, it is clear that it is necessary to know the motor drive frequency during diagnosis. Finally, the sampling period of the current data is determined by (Equation 4) below. At this time, the sampling period fs is determined by the required range of the sampling period fs mentioned above and the value of the integer x.

[0054] [Math 4] fs = T / N The procedure described above makes it possible to determine the steady-state operating time T and sampling period fs such that the frequency resolution Δf and current amplitude resolution ΔI have sufficient accuracy for diagnosis. In this way, the steady-state interval in which the accuracy of calculating the degree of degradation is highest can be determined.

[0055] The operation of each block of the diagnostic device 10 shown in Figure 1 will be explained in accordance with the above determination conditions.

[0056] First, the current detection unit 42 detects current data from the hoisting motor 1 at a preset sampling period (initial setting value). Furthermore, based on this current data, the steady-state interval determination unit 43 measures the motor drive frequency and the time interval (steady-state operation time [sec]) at which the current amplitude value remains constant.

[0057] At this time, the steady-state interval determination unit 43 extracts the steady-state operating time (data time width) that occurs most frequently in the usage site of the equipment over a predetermined period (for example, one week to several weeks).

[0058] Here, referring to Figure 10, we will explain an example of the frequency of occurrence of the steady-state operation time T (data time width) for raising and lowering the suspended load.

[0059] The time per cycle, which is the steady-state operation time (data time width) for raising and lowering a suspended load, varies depending on the installation conditions of the electric hoist (e.g., a hoist).

[0060] For example, in Figure 10(a), the number of steady-state operation times (T1) is 10. In Figure 10(b), the number of steady-state operation times (T2) is 7. In Figure 10(c), the number of steady-state operation times (T3) is 1.

[0061] Therefore, we extract the steady-state operating time (T1) shown in Figure 10(a) as the steady-state operating time (data time width) that occurs most frequently in the actual use of the equipment.

[0062] Furthermore, at the equipment's usage site, the steady-state operating time T1 to Tn is extracted from among the steady-state operating times that yield the highest accuracy in detecting the degree of degradation.

[0063] Figure 5 shows the detailed processing configuration of the steady-state interval determination unit 43.

[0064] In the steady-state interval determination unit 43, current data from the current detection unit 42 and drive frequency from the drive frequency detection unit 44 are input to the data storage unit 50 for one step, and data for one step each of upward and downward movements is first stored.

[0065] Furthermore, the steady-state time measurement unit 51 measures the steady-state operating time from the data for that one cycle and the motor drive frequency at that time. The conditions for the steady-state section at this time are that the current amplitude value and the drive frequency are approximately constant. The condition for being constant is, for example, that the change in the amplitude value and the drive frequency falls within a predetermined value.

[0066] Next, the steady-state time storage unit 52 stores the measured steady-state time value, and finally, the steady-state time determination unit 53 outputs the most frequently occurring steady-state time as a data time width.

[0067] It should be noted that the frequency of occurrence mentioned here does not need to be very frequent, as the value calculated here represents the degree of deterioration (wear) of the teeth of spline shaft 4. The current data width is determined from the steady-state time with the highest frequency of occurrence obtained here so as to satisfy the above determination conditions. In this process, the steady-state time that yields the highest accuracy in calculating the degree of deterioration is specified among the multiple steady-state times extracted. However, the determination of the current data width is not limited to the above determination method; for example, the steady-state time with the highest frequency of occurrence may be selected.

[0068] Thus, the steady-state interval determination unit 43 determines the steady-state operating interval based on the steady-state operating time and motor drive frequency that occur most frequently during the operation of the electric hoisting machine.

[0069] Furthermore, the steady-state section determination unit 43 extracts multiple steady-state operating times during the operation of the electric hoisting machine and determines a steady-state operating section based on the steady-state operating time and motor drive frequency that yield the highest accuracy in detecting the degree of deterioration when determining the degree of deterioration.

[0070] Furthermore, in parallel with the operation of the steady-state interval determination unit 43, the drive frequency detection unit 44 measures the motor drive frequency when the steady-state operation time is being extracted. Electric hoists (e.g., hoists) come in two types: commercial power-driven and inverter-driven. If it is a commercial power-driven type, only the commercial power frequency in that area needs to be considered. If it is an inverter-driven type, the drive frequency can be changed at any time, so the function of the drive frequency detection unit 44 is necessary.

[0071] The steady-state operating time and motor drive frequency obtained through the above process are input to the sampling period determination unit 45 to determine the sampling period of the current data used for calculating the degree of degradation, and the sampling period in the current detection unit 42 is updated. The method for determining the sampling period at that time is as described above.

[0072] Furthermore, if the steady-state operating period or motor drive frequency is changed during the operation of the electric hoist, the sampling period of the current is updated by the sampling period of the current based on the steady-state operating period and motor drive frequency that occur most frequently during the operation of the electric hoist after the change.

[0073] According to Example 1, in an electric hoisting machine, the degree of deterioration of mechanical components constituting the hoisting device can be estimated with high accuracy, regardless of the usage pattern at the site. For example, the degree of deterioration of spline shafts and reduction gears incorporated into hoisting machines such as hoists and cranes can be calculated with high accuracy, regardless of the usage pattern at the site. [Examples]

[0074] Figure 6A is a schematic diagram of the electric hoisting machine of Example 2.

[0075] The difference between the electric hoist of Embodiment 2 shown in Figure 6A and the electric hoist of Embodiment 1 shown in Figure 1 is that a deterioration degree display unit 55 is provided inside the diagnostic device 10. The other configurations are the same as those of the electric hoist of Embodiment 1 shown in Figure 1, so their explanation will be omitted.

[0076] Next, we will explain the output format of the deterioration level of the diagnostic device 10.

[0077] The output format for the degree of deterioration is not particularly limited, but one example is to provide a deterioration display unit 55 in addition to the configuration shown in Figure 1, as shown in Figure 6A, to display the progression of the degree of deterioration.

[0078] First, as mentioned above, when calculating the degree of deterioration under the same conditions as the lifting and lowering times of the suspended load and the motor drive frequency in a hoist operating at a particular site, the degree of deterioration increases in a manner that is roughly proportional to the amount of wear, as shown in the schematic diagram in Figure 7. In the characteristics shown in Figure 7, a linear relationship is shown between the amount of wear and the degree of deterioration, but this example is merely a schematic diagram, and in reality, the relationship is likely to be distorted due to differences in failure modes, shaft materials, etc.

[0079] Next, Figure 8 shows the characteristics of degradation when the time for raising and lowering is changed in the operating environment, or when the motor drive frequency is changed midway through.

[0080] As shown in the schematic diagram in Figure 8, when the rise / fall time or motor drive frequency is changed, the trend of degradation changes deviates from the previous trend, and then returns to the trend of degradation before the change by updating the steady-state operating time and current data sampling time after the change.

[0081] Note that the example shown in Figure 8 automatically updates the sampling period of current data after changing the rise / fall time or motor drive frequency, and automatically continues the degradation diagnosis. However, the sampling period of current data may not be updated automatically, and the degradation level display unit 55 shown in Figure 6A may be notified that the rise / fall time or motor drive frequency has been changed, and the degradation level calculation may be temporarily suspended. [Examples]

[0082] Figure 6B is a schematic diagram of the electric hoisting machine of Embodiment 3.

[0083] The difference between the electric hoist of Embodiment 3 shown in Figure 6B and the electric hoist of Embodiment 2 shown in Figure 6A is that a deterioration degree display unit 55 is provided outside the diagnostic device 10. The other configurations are the same as those of the electric hoist of Embodiment 2 shown in Figure 6A, so their explanation will be omitted.

[0084] As shown in Figure 6B, the diagnostic device 10 has a transmitter 61. The diagnostic device 10 is wirelessly connected to an external mobile terminal 62. The mobile terminal 62 has a receiver 63 and a degradation level display unit 55. The degradation level calculated by the degradation level calculation unit 41 of the diagnostic device 10 is received wirelessly from the transmitter 61 by the receiver 63 of the mobile terminal 62 and displayed on the degradation level display unit 55. [Examples]

[0085] The deterioration diagnosis of the spline shaft 4 can also be achieved by pre-setting the steady-state operating time for raising and lowering movements and the motor drive frequency in the diagnostic device 10. The configuration of the diagnostic device 10 in that case is shown in Figure 9. Figure 9 is a schematic diagram of the electric hoisting machine of Embodiment 4.

[0086] The difference between the electric hoist of Embodiment 4 shown in Figure 9 and the electric hoist of Embodiment 1 shown in Figure 1 is that in Figure 9, instead of the steady-state interval determination unit 43 and the drive frequency detection unit 44 in Figure 1, a condition input unit 56 and an operating condition setting unit 57 are provided.

[0087] The steady-state operating time and motor drive frequency for raising and lowering the suspended load are input to the condition input unit 56 from an external source. The operating condition setting unit 57 determines the operating conditions according to the input set values, determines the sampling period according to those set values, and updates the sampling period of the current detection unit 42. The other configurations are the same as those of the electric hoisting machine in Embodiment 1 shown in Figure 1, so their explanation is omitted.

[0088] The operating condition setting unit 57 performs the processing of the block shown in Figure 5 described above.

[0089] Specifically, the operating condition setting unit 57 inputs current data from the current detection unit 42 and the drive frequency from the condition input unit 56 into the data storage unit 50 for one step, and first stores data for one step each for upward and downward movement.

[0090] Furthermore, the steady-state time measurement unit 51 measures the steady-state operating time from the data for that one cycle and the motor drive frequency at that time. The conditions for the steady-state section at this time are that the current amplitude value and the drive frequency are approximately constant. The condition for being constant is, for example, that the change in the amplitude value and the drive frequency falls within a predetermined value.

[0091] Next, the steady-state time storage unit 52 stores the measured steady-state time value, and finally, the steady-state time determination unit 53 outputs the most frequently occurring steady-state time as a data time width.

[0092] It should be noted that the frequency of occurrence mentioned here does not need to be very frequent, as the value calculated here represents the degree of deterioration (wear) of the spline shaft teeth. The current data width is determined from the steady-state time with the highest frequency of occurrence obtained here to satisfy the above determination conditions, and in doing so, the steady-state operating time that yields the highest accuracy in calculating the degree of deterioration is specified among the multiple steady-state times extracted. However, the determination of the current data width is not limited to the above determination method; for example, the steady-state operating time with the highest frequency of occurrence may be selected.

[0093] In this way, the operating condition setting unit 57 determines the steady-state operating interval based on the steady-state operating time and motor drive frequency that occur most frequently during the operation of the electric hoisting machine.

[0094] Furthermore, the operating condition setting unit 57 extracts multiple steady-state operating times during the operation of the electric hoisting machine and determines a steady-state operating interval based on the steady-state operating time and motor drive frequency that yield the highest detection accuracy for determining the degree of deterioration. [Examples]

[0095] Figure 11 is a schematic diagram of the electric hoisting system of Example 5. The electric hoisting system of Example 5 is an example of a configuration that utilizes the cloud.

[0096] The difference between the electric hoisting system of Embodiment 5 shown in Figure 11 and the electric hoisting machine of Embodiment 1 shown in Figure 1 is that the electric hoisting machine and the diagnostic device 110 are connected via the network 100.

[0097] In the electric hoisting system of Embodiment 5 shown in Figure 11, the diagnostic device 110 is located on the cloud side via the network 100.

[0098] Thus, in the electric hoisting system of Example 5, the electric hoisting machine and the diagnostic device 110 are connected via a network 110, which is a communication line.

[0099] The electric hoisting machine includes a hoisting motor 1, a three-phase power supply 2 that supplies power to the hoisting motor 1, a hoisting device 3 that raises and lowers the suspended load, and a current detection unit 42 that detects the current flowing through the hoisting motor 1.

[0100] The diagnostic device 110 detects the degree of deterioration of the mechanical components constituting the hoisting device based on the current flowing through the hoisting motor 1.

[0101] Specifically, the diagnostic device 110 includes a steady-state interval determination unit 43 that determines the steady-state operating time when the suspended load is raised or lowered based on the current flowing through the hoisting motor 1, a drive frequency detection unit 44 that detects the drive frequency of the hoisting motor 1 when the suspended load is raised or lowered based on the current flowing through the hoisting motor 1, and a sampling period determination unit 45 that updates the current sampling period based on the steady-state operating time and the motor drive frequency.

[0102] The current detection unit 42 of the electric hoisting machine detects the current flowing to the hoisting motor 1 based on the sampling period updated by the sampling period determination unit 45 of the diagnostic device 110.

[0103] The steady-state interval determination unit 43 determines the steady-state operating interval based on the most frequently occurring steady-state operating time and motor drive frequency during the operation of the electric hoisting machine.

[0104] Furthermore, the steady-state section determination unit extracts multiple steady-state operating times during the operation of the electric hoisting machine and determines a steady-state operating section based on the steady-state operating time and motor drive frequency that yield the highest detection accuracy for the degree of deterioration when determining the degree of deterioration.

[0105] According to the above embodiment, in an electric hoisting machine, the degree of deterioration of mechanical components constituting the hoisting device can be estimated with high accuracy, regardless of the usage pattern at the site where it is used. For example, the degree of deterioration of spline shafts and reduction gears incorporated into hoisting machines such as hoists and cranes can be calculated with high accuracy, regardless of the usage pattern at the site where it is used.

[0106] Here, the diagnostic device 10 is composed of, for example, a computer.

[0107] Computers execute programs using processors (e.g., CPUs, GPUs) and perform processing defined by the programs, utilizing memory resources (e.g., memory) and interface devices (e.g., communication ports).

[0108] Therefore, the main entity performing the processing by executing the program may be a processor. Similarly, the main entity performing the processing by executing the program may be a controller, device, system, computer, or node having a processor. The main entity performing the processing by executing the program may be an arithmetic unit, and may include dedicated circuits that perform specific processing. Here, dedicated circuits include, for example, FPGAs (Field Programmable Gate Arrays), ASICs (Application Specific Integrated Circuits), CPLDs (Complex Programmable Logic Devices), etc.

[0109] The program may be installed on the computer from the program source. The program source may be, for example, a program distribution server or a storage medium readable by the computer. If the program source is a program distribution server, the program distribution server includes a processor and storage resources for storing the program to be distributed, and the processor of the program distribution server may distribute the program to other computers. In addition, in the embodiment, two or more programs may be implemented as one program, or one program may be implemented as two or more programs.

[0110] For example, in the diagnostic device 10 shown in Figure 1, the feature calculation unit 40, the degradation degree calculation unit 41, the current detection unit 42, the steady-state interval determination unit 43, the drive frequency detection unit 44, and the sampling period determination unit 45 each perform their respective functions when a processor executes a program.

[0111] In the diagnostic device 10 shown in Figure 9, the condition input unit 56 and the operation condition setting unit 57 each perform their respective functions when the processor executes a program.

[0112] Although this embodiment was described using a hoist as an example of an electric hoisting machine, it can be applied without any problems to other electric hoisting machines, such as cranes.

[0113] Furthermore, similar to spline shafts, this method can also be applied to parts where deterioration can be diagnosed using the frequency analysis results of the motor current (for example, reduction gears). [Explanation of Symbols]

[0114] 1. Hoisting motor 2 3 phase power supply 3. Hoisting device 4 spline axes 5. Reduction gear 6 electric wire 7 Current Sensor 10 Diagnostic Systems 40 Feature Analysis Unit 41 Deterioration degree calculation section 42 Current detection unit 43. Steady-state interval determination unit 44 Drive frequency detection unit 45. Sampling period determination unit 50-step data storage unit 51 Steady-state time measurement unit 52 Steady-state time storage unit 53 Steady-state time determination unit 55 Deterioration degree display section 56 Condition Input Section 57 Operating Condition Setting Unit 61 Transmitter 62 Mobile devices 63 Receiving Unit

Claims

1. A hoisting motor and A power supply that provides power to the aforementioned hoisting motor, A hoisting device for raising and lowering suspended loads, An electric hoisting machine having a diagnostic device that detects the degree of deterioration of mechanical components constituting the hoisting device based on the current flowing through the hoisting motor, The diagnostic device is A current detection unit for detecting the current flowing through the aforementioned hoisting motor, A steady-state interval determination unit that determines the steady-state operating time when the suspended load is raised or lowered based on the current flowing through the hoisting motor, A drive frequency detection unit detects the drive frequency of the hoisting motor when the suspended load is raised or lowered, based on the current flowing through the hoisting motor. The system includes a sampling period determination unit that updates the sampling period of the current flowing through the hoisting motor based on the steady-state operating time and the motor drive frequency, The current detection unit is An electric hoisting machine characterized by detecting the current flowing to the hoisting motor based on the updated sampling period.

2. In the electric hoisting machine according to claim 1, The steady-state interval determination unit, An electric hoisting machine characterized in that it determines the steady-state operating interval based on the steady-state operating time and the motor drive frequency, which occur most frequently during the operation of the electric hoisting machine.

3. In the electric hoisting machine according to claim 1, The steady-state interval determination unit, Multiple steady-state operating times are extracted during the operation of the electric hoisting machine, An electric hoisting machine characterized in that, when determining the degree of deterioration, the steady-state operating interval is determined based on the steady-state operating time and the motor drive frequency that yield the highest detection accuracy for the degree of deterioration.

4. In the electric hoisting machine according to claim 1, The sampling period determination unit is, If the steady-state operating time or the motor drive frequency is changed during the operation of the electric hoisting machine, An electric hoisting machine characterized in that, during the operation of the modified electric hoisting machine, the sampling period of the current flowing to the hoisting motor is updated based on the most frequently occurring steady-state operating time and motor drive frequency.

5. In the electric hoisting machine according to claim 1, The diagnostic device is An electric hoisting machine characterized in that, when the steady-state operating period and the motor drive frequency are changed during the operation of the electric hoisting machine, it notifies that the steady-state operating period and the motor drive frequency have been changed.

6. In the electric hoisting machine according to claim 1, The diagnostic device is A feature quantity calculation unit calculates a predetermined feature quantity based on the current flowing through the aforementioned hoisting motor, A degradation degree calculation unit that calculates the degree of degradation based on the aforementioned feature quantities, An electric hoisting machine characterized by having the following features.

7. In the electric hoisting machine according to claim 1, An electric hoisting machine characterized by having a deterioration degree display unit that displays the degree of deterioration inside or outside the diagnostic device.

8. A hoisting motor and A power supply that provides power to the aforementioned hoisting motor, A hoisting device for raising and lowering suspended loads, An electric hoisting machine having a diagnostic device that detects the degree of deterioration of mechanical components constituting the hoisting device based on the current flowing through the hoisting motor, The diagnostic device is A current detection unit for detecting the current flowing through the aforementioned hoisting motor, A condition input unit for pre-setting the steady-state operating time and motor drive frequency during the raising and lowering of the suspended load, An operating condition setting unit sets the operating conditions of the electric hoisting machine based on the current flowing through the hoisting motor, the steady-state operating time, and the motor drive frequency. The system includes a sampling period determination unit that updates the sampling period of the current flowing through the hoisting motor based on the operating conditions of the electric hoisting machine, The current detection unit is An electric hoisting machine characterized by detecting the current flowing to the hoisting motor based on the updated sampling period.

9. In the electric hoisting machine according to claim 8, The aforementioned operating condition setting unit is An electric hoisting machine characterized in that it determines the steady-state operating interval based on the steady-state operating time and the motor drive frequency, which occur most frequently during the operation of the electric hoisting machine.

10. In the electric hoisting machine according to claim 8, The aforementioned operating condition setting unit is Multiple steady-state operating times are extracted during the operation of the electric hoisting machine, An electric hoisting machine characterized in that, when determining the degree of deterioration, the steady-state operating interval is determined based on the steady-state operating time and the motor drive frequency that yield the highest detection accuracy for the degree of deterioration.

11. In the electric hoisting machine according to claim 8, The diagnostic device is A feature quantity calculation unit calculates a predetermined feature quantity based on the current flowing through the winding motor, A degradation degree calculation unit that calculates the degree of degradation based on the aforementioned feature quantities, An electric hoisting machine characterized by having the following features.

12. In the electric hoisting machine according to claim 8, An electric hoisting machine characterized by having a deterioration degree display unit that displays the degree of deterioration inside or outside the diagnostic device.

13. An electric hoisting system in which an electric hoisting machine and a diagnostic device are connected via a communication line, The aforementioned electric hoisting machine is, A hoisting motor and A power supply that provides power to the aforementioned hoisting motor, A hoisting device for raising and lowering suspended loads, A current detection unit for detecting the current flowing through the aforementioned hoisting motor, It has, The diagnostic device is The degree of deterioration of the mechanical components constituting the hoisting device is detected based on the current flowing through the hoisting motor. The diagnostic device is A steady-state interval determination unit that determines the steady-state operating time when the suspended load is raised or lowered based on the current flowing through the hoisting motor, A drive frequency detection unit detects the drive frequency of the hoisting motor when the suspended load is raised or lowered, based on the current flowing through the hoisting motor. The system includes a sampling period determination unit that updates the sampling period of the current flowing through the hoisting motor based on the steady-state operating time and the motor drive frequency, The current detection unit of the electric hoisting machine is An electric hoisting system characterized by detecting the current flowing to the hoisting motor based on the sampling period updated by the sampling period determination unit of the diagnostic device.

14. In the electric hoisting system according to claim 13, The steady-state interval determination unit, An electric hoisting system characterized by determining a steady-state operating interval based on the steady-state operating time and motor drive frequency that occur most frequently during the operation of the electric hoisting machine.

15. In the electric hoisting system according to claim 13, The steady-state interval determination unit, Multiple steady-state operating times are extracted during the operation of the electric hoisting machine, An electric hoisting system characterized in that, when determining the degree of deterioration, the steady-state operating interval is determined based on the steady-state operating time and the motor drive frequency that yield the highest detection accuracy for the degree of deterioration.

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