Spline diagnostic device, hoist, and electric vehicle

Abstract

To provide a diagnostic apparatus of a spline, a hoist and an electric vehicle which can confirm the abrasion and deterioration states of a gear of a spline shaft without detaching the spline shaft from a boss and in which there is no need to open the vicinity of the spline shaft for maintenance of a sensor itself.SOLUTION: A diagnostic apparatus of a spline comprises: a current measurement unit which measures the current of an electric motor that drives a spline shaft; a frequency component calculation unit which calculates a specific frequency component by performing frequency analysis of the current measured by the current measurement unit; and an abrasion state estimation unit which estimates an abrasion state of a gear of the spline shaft on the basis of the specific frequency component calculated by the frequency component calculation unit. Since the abrasion and deterioration states of the gear of the spline shaft can be estimated on the basis of the current of the electric motor, an open inspection of the spline becomes unnecessary. Since the current sensor is installed in a cable for supplying the power to the electric motor, there is no need to open the vicinity of the spline shaft even when a malfunction occurs in the sensor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a spline diagnostic device for diagnosing the wear and deterioration of a spline, which is one of the power transmission mechanisms, a hoist, and an electric vehicle. [Background technology]

[0002] A spline is a connection method used to transmit mechanical rotational force. One of the shafts that make up the spline (hereinafter referred to as the spline shaft) has gear teeth machined on its outer periphery, and the other shaft (hereinafter referred to as the boss) has a groove machined into which the gear of the spline shaft is inserted.

[0003] By fitting a spline shaft into a boss, it becomes possible to transmit large rotational forces. In this way, because the gear of the spline shaft is fitted into the concave and convex grooves of the boss, there is an advantage that slippage does not occur even when a large rotational force is applied compared to power transmission mechanisms such as couplings, so it is often used in applications where large rotational forces are to be transmitted.

[0004] Furthermore, since the gear on the spline shaft fits into the axial groove formed in the boss, there is a small gap between them, allowing for axial movement, and even if the spline shaft or boss is slightly displaced in the axial direction, this movement can be absorbed.

[0005] One application of splines is in hoists, which are industrial machines that use a hoisting device equipped with an electric motor to lift a load by winding up a wire rope and to lower the load by winding down.

[0006] In a hoist, if slippage occurs in the torque transmission section while lifting a load, there is a risk that the load may tilt. To prevent this slippage, a spline connection method is used to transmit the torque of the electric motor to the hoisting mechanism.

[0007] As mentioned above, there is a tiny gap between the gear on the spline shaft and the groove on the boss, so when the electric motor rotates, the gear on the outer periphery of the spline shaft comes into partial contact with the groove on the boss.In the case of a hoist, the rotation direction of the electric motor is reversed when the load is raised and lowered, so the tooth surface on the different side of the gear during forward and reverse rotation comes into partial contact with the wall surface of the groove.

[0008] Furthermore, when a hoist is used for an extended period of time, the tooth surface of the gear on the spline shaft gradually wears down and deteriorates, which can lead to problems with the transmission of rotational force. Therefore, it is important to inspect the spline shaft periodically to check for deterioration. However, because the gear on the spline shaft is fitted into the concave and convex grooves of the boss, it is impossible to check visually in its fitted state. Therefore, for inspection, the spline shaft must be removed from the boss and opened for inspection, which requires a lot of work. Furthermore, this method does not allow for early detection of signs of failure.

[0009] To solve this problem, methods are known for checking the wear and deterioration state of splines without removing the spline shaft from the boss, such as those described in Japanese Patent Laid-Open No. 5-164656 (Patent Document 1) and Japanese Patent Laid-Open No. 5-346323 (Patent Document 2).

[0010] Patent Document 1 describes a method that uses a vibration sensor attached near the spline shaft. Specifically, since there is a very high correlation between the vibration velocity or vibration acceleration detected by the vibration sensor and the actually measured wear amount of the gears on the spline shaft, it is possible to estimate the wear amount of the gears on the spline shaft from the values ​​of the dynamic velocity or vibration acceleration.

[0011] Furthermore, Patent Document 2 describes a method that uses a displacement meter installed on a spline shaft. Specifically, the displacement meter measures the circumferential gap when the spline shaft is accelerated or decelerated, and the amount of wear of the gears on the spline shaft is estimated from the value of the gap, making it possible to inspect the wear of the gears on the spline shaft without releasing the spline. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 5-164656 [Patent Document 2] Japanese Patent Application Publication No. 5-346323 Summary of the Invention [Problem to be solved by the invention]

[0013] However, the methods described in Patent Documents 1 and 2 require the installation of a vibration sensor or displacement meter near the spline shaft, which may make it impossible to install the sensor due to spatial constraints. Also, if an abnormality occurs in the vibration sensor or displacement meter, the area near the spline shaft must be opened for maintenance of the sensor itself.

[0014] An object of the present invention is to provide a spline diagnostic device, a hoist, and an electric vehicle that can check the wear and deterioration state of the gears of a spline shaft without removing the spline shaft from a boss, and that does not require opening the area near the spline shaft for maintenance of the sensor itself. [Means for solving the problem]

[0015] The present invention is characterized by a spline diagnostic device having a current measurement unit that measures a current of an electric motor that drives a spline shaft, a frequency component calculation unit that performs frequency analysis of the current measured by the current measurement unit to calculate specific frequency components, and a wear state estimation unit that estimates the wear state of gears of the spline shaft based on the specific frequency components calculated by the frequency component calculation unit. [Effects of the Invention]

[0016] According to the present invention, it is possible to estimate the wear and deterioration state of the gears of the spline shaft based on the current of the electric motor that drives the spline shaft, thereby eliminating the need for open inspection of the spline. Furthermore, since the current sensor is installed on the cable that supplies power to the electric motor, there is an advantage that even if a malfunction occurs in the sensor, there is no need to open the vicinity of the spline shaft. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a configuration diagram showing the configuration of a crane to which the present invention is applied. [Figure 2(a)] 10 is an explanatory diagram showing the state in which the spline shaft and the boss portion are fitted together, showing a state in which the teeth of the spline and the concave-convex grooves of the boss are not in contact with each other. FIG. [Figure 2(b)] 10 is an explanatory diagram showing the state in which the spline shaft and the boss portion are fitted together, showing the state in which the teeth of the spline and the concave-convex grooves of the boss are in contact with each other. FIG. [Figure 3] FIG. 4 is a flowchart showing a flow of diagnosis of wear of a spline according to an embodiment of the present invention. [Figure 4] 4 is an explanatory diagram illustrating a process from current measurement to calculation of a parameter P (current intensity) according to an embodiment of the present invention. FIG. [Figure 5(a)] FIG. 10 is an explanatory diagram illustrating the feature amount of a normal spline. [Figure 5(b)] FIG. 10 is an explanatory diagram illustrating a feature amount of a worn spline. [Figure 5(c)] FIG. 10 is an explanatory diagram illustrating the distribution of the number of driving operations and the feature amount. [Figure 6]FIG. 10 is a configuration diagram showing the configuration of a crane according to another embodiment of the present invention. [Figure 7(a)] 7 is an explanatory diagram illustrating the relationship between the amount of lifting load and the characteristic amount of a normal spline in hoist A in the embodiment shown in FIG. 6. FIG. [Figure 7(b)] 7 is a diagram illustrating the relationship between the amount of suspended load and the feature amount of a spline in which wear has occurred in hoist A in the embodiment shown in FIG. 6. [Figure 8(a)] 7 is an explanatory diagram illustrating the relationship between the amount of lifting load and the characteristic amount of a normal spline in hoist B in the embodiment shown in FIG. 6. FIG. [Figure 8(b)] 7 is a diagram illustrating the relationship between the amount of suspended load and the feature amount of a spline in which wear has occurred in hoist B in the embodiment shown in FIG. 6. [Figure 9(a)] 7 is an explanatory diagram illustrating the relationship between the amount of lifting load and the characteristic amount of a normal spline in hoist C in the embodiment shown in FIG. 6. FIG. [Figure 9(b)] 7 is a diagram illustrating the relationship between the amount of suspended load and the feature amount of the spline where wear has occurred in the hoist C in the embodiment shown in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications and application examples within the technical concept of the present invention are also included within its scope.

[0019] As an example of application of the spline coupling method, the splines of a hoist are shown below as an example, but the present invention is not limited to hoists and can be applied to any spline shaft driven by an electric motor, and can also be applied to mechanisms that drive wheels with an electric motor, such as electric vehicles and hybrid vehicles.

[0020] The basic configuration of a hoist is shown in Figure 1. As shown in Figure 1, a hoist motor 10 is connected to a power source 12 via an electric wire 11, and a three-phase voltage is applied to the hoist motor 10. When the three-phase voltage is applied, the hoist motor 10 rotates, and accordingly, a shaft 13 of the hoist motor 10 rotates. The outer peripheral surface of one end of the shaft 13 is a spline shaft 13S that is shaped like a gear and is fitted into a concave-convex groove of a boss 14 for connection.

[0021] As a result, the rotational force of the hoisting motor 10 is transmitted to the hoisting mechanism (hoist drum) 15. When the hoisting mechanism 15 rotates, the wire rope 16 attached to the hoisting mechanism 15 is wound up, and the hook 17 at the end and the suspended load 18 fixed to the hook 17 are raised. Furthermore, when the rotation direction of the hoisting motor 10 is reversed, the wire rope 16 is unwound, and the hook 17 moves downward. As a result, the suspended load 18 also moves downward, allowing it to be lowered.

[0022] In this way, the basic operation of the hoist is to hoist the load 18 using the rotational force of the hoisting motor 10. Furthermore, current measurement means 19 for measuring current is provided in at least one phase of the electric wire 11. Current data measured by the current measurement means 19 is input to a diagnostic device 20, which diagnoses the wear and deterioration state of the spline shaft 13S. The diagnosis results are displayed on a display unit 21.

[0023] 1 shows an example in which the current measuring means 19 is installed on the electric wire 11, but if the power supply 12 is an inverter, it is also possible to use information such as a current feedback value or a current command value used to control the inverter instead. Also, the diagnostic device 20 can be implemented in an electronic component capable of performing calculations, such as a microcomputer inside the inverter.

[0024] FIG. 2(a) shows a diagram illustrating a cross section of the spline shaft 13S and the concave-convex grooves of the boss 14. Note that the cross-sectional shape of the gear of the spline shaft 13S is an example and is not limited to this. As shown in FIG. 2(a), the spline 22 is such that the gear 23 of the spline shaft 13S is fitted into the concave-convex groove 24 of the boss 14 in the axial direction and coupled. To enable this fitting coupling, a small gap G exists between the gear 23 and the concave-convex groove 24. The gears 23 are provided on the spline shaft 13S at regular intervals in the circumferential direction. The gear 23 has tooth surfaces 23f and 23r that come into contact with the concave-convex groove 24 of the boss 14.

[0025] 2(b) is a diagram showing the rotation of the spline shaft 13S, which is the drive shaft. When the spline shaft 13S rotates in the direction of arrow (F), the tooth surface 23f of the gear 23 comes into contact with the wall surface of the concave-convex groove 24 of the boss 14, and the rotational force is transmitted from the spline shaft 13S to the boss 14. Although not shown, when the spline shaft 13S rotates in the direction opposite to the direction of arrow (F), the tooth surface 23r of the gear 23 comes into contact with the opposite wall surface of the concave-convex groove 24 of the boss 14, and the rotational force in the direction opposite to the arrow (F) is transmitted to the boss 14.

[0026] In the case of a hoist, for example, rotating in the direction of arrow (F) raises the load 18, and rotating in the opposite direction to arrow (F) lowers the load 18. By repeating these operations, the spline shaft 13S rotates forward and backward repeatedly, which causes the tooth surfaces 23f and 23r to wear down and become damaged, leading to increased wear.

[0027] Furthermore, because the operation differs between the forward and reverse directions as described above, wear may not progress uniformly on tooth surfaces 23f and 23r of gear 23. If wear progresses on tooth surfaces 23f and 23r, gear 23 may lose its functionality, resulting in poor transmission of rotational force. Therefore, it is necessary to detect deterioration of gear 23 before it loses its functionality.

[0028] Next, the operation (wear detection method) of the spline diagnostic device 20 proposed in the present invention to address the above-mentioned issues will be described. Note that the following description can also be applied to diagnosing the occurrence of a failure and predicting the occurrence of a failure.

[0029] FIG. 3 shows a flowchart illustrating the processing flow of the diagnostic device 20, and FIG. 4 shows a method for diagnosing a fault using a current.

[0030] In "Step S1," as shown in Fig. 4(a), the current flowing through the hoisting motor 10 for the Δt interval is acquired by the current measurement means 19. The method of acquiring the current for the Δt interval may involve moving to "Step S2" (sequential calculation) once only the Δt interval has been acquired, or may involve measuring data for the entire interval (here, the T interval) and then dividing the data into Δt intervals and moving to Step S2 (constant calculation).

[0031] Next, in "Steps S2" to S4," a frequency analysis such as a fast Fourier transform (FFT) is performed on the current in the Δt section to calculate the frequency spectrum, as shown in Figure 4(b).The frequency spectrum of the current has a peak at the fundamental frequency of the current, as shown in Figure 4(b), and then declines from there to the low-frequency and high-frequency sides.

[0032] Of this frequency spectrum, a spectrum of a specific frequency is extracted and stored as parameter P. In the example of diagnosis of a hoist spline, the value of a specific frequency component (the part indicated by the arrow (P) in Figure 4(b)) that appears as a sideband of the fundamental frequency of the current is extracted as parameter P (current intensity).

[0033] The specific frequency component is a sideband component of the drive frequency (Fb) of the current in the frequency spectrum obtained by frequency analysis of the current, and is the current intensity of at least one of the frequencies (Fb+Fr and Fb-Fr) resulting from the rotation frequency (Fr) of the motor.

[0034] This embodiment is characterized in that the phenomenon of rotational wobble caused by wear on the tooth surface of the gear 23 of the spline shaft 13S of the hoist is detected using the current flowing through the hoist motor 10. In this embodiment, in order to extract multiple parameters P from the current data during one drive of the hoist motor 10, data in a T section is divided into multiple Δt sections (T>Δt), and the parameter P is calculated for each Δt section. Here, the Δt section is set to be larger than the reciprocal (1 / Fb) of the current drive frequency (Fb).

[0035] By dividing in this way, it is possible to calculate and store T / Δt parameters P. The stored parameters P have a frequency distribution similar to that shown in Fig. 4(c). As will be described later, diagnosis is performed by focusing on the fact that the distribution of parameters P changes due to the influence of rotational wobble caused by wear of the spline 22.

[0036] Therefore, in "Step S5", it is determined whether T / Δt (predetermined number) of parameters P have been stored. If the predetermined number of parameters P have not been stored, the process returns to "Step S1" and executes the same process. On the other hand, if the predetermined number of parameters P have been stored, the process proceeds to "Step S6".

[0037] In "Step S6", statistics of information related to the distribution of T / Δt parameters P (hereinafter referred to as parameter group) are extracted as features. Specific examples of statistics include the following. In the frequency distribution of FIG. 4(c), in addition to the maximum value, minimum value, and average value, there are also the median, which indicates the position where the left and right areas of the distribution are equal, and the mode, which is the most frequent value. In this embodiment, the above-mentioned average value is used as the feature.

[0038] In addition, range (the difference between the maximum and minimum), variance, and standard deviation, which are statistics that represent the spread of the distribution, may also be used. Furthermore, skewness and kurtosis, which are statistics that represent the shape of the frequency distribution, may also be used. Furthermore, the feature is not limited to one, and multiple statistics may be used, or a new evaluation index calculated from multiple statistics may be used as the feature. In this way, the key point is that the statistical quantity of information related to the distribution of a group of parameters may be used as the feature.

[0039] Finally, in "Step S7," the state of the spline is judged based on the feature amount (average value). To explain an example of the judgment method, first, the feature amount (average value) when the spline 22 is in a normal state is set as learning data (criterion value for judgment = threshold value). Next, the deviation between the feature amount (average value) at the time of diagnosis and the learning data (criterion value for judgment = threshold value) is calculated, and if this deviation exceeds a predetermined deviation, it is judged that "the state of the spline is abnormal (worn)."

[0040] Figures 5(a) and 5(b) show the frequency distribution of the parameter P when the spline 22 of the hoist is in a normal state and when wear has progressed. Note that only the state of the spline 22 is different, and the load of the suspended load, operating time, etc. are the same.

[0041] As shown in Figures 5(a) and 5(b), it can be seen that the shape of the frequency distribution differs depending on the state of wear of the gear 23 of the spline shaft 13S of the spline 22. In this example, the average value of the distribution of the parameter P is lower in the frequency distribution of Figure 5(b), which shows a deteriorated spline 22, than in the frequency distribution of Figure 5(a), which shows a normal spline 22. In this way, wear of the gear 23 of the spline shaft 13S can be determined using feature quantities.

[0042] Figure 5(c) shows the results of confirming reproducibility. A spline 22 in a normal state and a spline 22 with advanced wear were assembled to a hoist, and the hoist was operated multiple times. A feature value (in this example, the average value of the parameter P) was extracted from the current data for each operation.

[0043] As can be seen from FIG. 5(c), if the state is the same, the characteristic quantity changes stably, and it is possible to determine whether the gear 23 of the spline shaft 13S is normal or the wear is progressing from the magnitude of the characteristic quantity. Thus, in the present embodiment, based on the event that the distribution of the parameter P calculated from the current changes depending on the wear state of the spline 22 under a certain same operating condition, the wear state of the spline 22 is diagnosed. Note that the parameter P uses the current intensity in the present embodiment, but it is not limited thereto as long as it represents the wear of the spline.

[0044] Next, FIG. 6 shows an embodiment for improving the diagnostic accuracy of the spline 22. This embodiment is different in that a load weighing meter 25 is added as an input for diagnosis in addition to the configuration of FIG. 1 described above. The principle by which the diagnostic accuracy is improved by adding the load weight will be described below.

[0045] FIGS. 7 to 9 show the results of measuring the current of the hoisting motor 10 when the load weights of three different hoists (A, B, C) are changed to three types of loads (W1 < W2 < W3) and driven, and calculating the above-described characteristic quantity (the average value of the parameter P shown in FIGS. 5(a) and 5(b)). Note that these show the characteristic quantities when the hoist is operated a plurality of times with each load weight, and are the results of evaluation including measurement variations.

[0046] FIG. 7(a) is a diagram showing the correlation between the characteristic quantity and the load weight obtained from the current of the hoisting motor 10 measured when a normal spline is incorporated in an arbitrary hoist (denoted as hoist A). On the other hand, FIG. 7(b) is a diagram showing the correlation between the characteristic quantity and the load weight obtained from the current of the hoisting motor 10 measured by recombining only the spline of the hoist A with worn parts.

[0047] As shown in Fig. 7(a), in the case of a normal spline, the feature quantity has a positive correlation (the slope Sn is positive) with respect to the increase in the suspended load weight (W1 < W2 < W3). On the other hand, as shown in Fig. 7(b), in the case of a worn spline, it can be seen that the feature quantity has a negative correlation (the slope Sd is negative) with respect to the increase in the suspended load weight (W1 < W2 < W3).

[0048] In this study, since only the spline is changed from a normal product to a worn product, it can be said that the change in the correlation between the feature quantity and the suspended load weight is due to the influence of spline wear. Therefore, it becomes possible to diagnose spline wear based on the correlation between the feature quantity and the suspended load weight (for example, the difference between the slope Sn and the slope Sd).

[0049] Also, the reason for diagnosing based on the correlation between the feature quantity and the suspended load weight instead of the magnitude of the feature quantity will be explained. For example, in the examples of Fig. 7(a) and Fig. 7(b), the feature quantity at the suspended load weight (W2) is almost the same value for the normal spline and the worn spline. Therefore, it can be seen that it is difficult to diagnose based only on the feature quantity. On the other hand, by evaluating including the feature quantities at other suspended load weights (W1 and W3), the wear of the spline can be accurately diagnosed.

[0050] Next, the cases examined with another hoist (denoted as Hoist B) are shown in Fig. 8(a) and Fig. 8(b). In the case of Hoist B, for both the normal spline and the worn spline, the correlation between the feature quantity and the suspended load weight is positive (both the slope Sn and the slope Sd are positive). However, it can be seen that the magnitude of the slope is "Sn > Sd".

[0051] Also in this study case, as described above, since only the spline in Hoist B is changed from a normal product to a worn product, it can be inferred that the change in the correlation between the feature quantity and the suspended load weight is due to the influence of spline wear. Therefore, this case also shows that spline wear can be detected by the correlation (the magnitude of the slope) between the feature quantity and the suspended load weight.

[0052] Similar to Hoist A, when diagnosing only based on the magnitude of the characteristic quantity, the characteristic quantity when the suspended load weight is (W2) is almost the same for normal splines and worn splines. Therefore, it can be seen that it is difficult to diagnose based only on the characteristic quantity. From the above results, it is also possible to accurately detect the wear of the spline by diagnosing based on the correlation between the characteristic quantity and the suspended load weight.

[0053] Next, cases examined with another hoist (referred to as Hoist C) are shown in FIGS. 9(a) and 9(b). In the case of Hoist C, the correlation between the characteristic quantity and the suspended load weight is negative (both the slopes Sn and Sd are negative) for both normal splines and worn splines. However, it can be seen that the magnitude of the slope is "Sn < Sd".

[0054] In this study case as well, similar to Hoist A and Hoist B described above, since only the spline is changed from a normal product to a worn product, it can be inferred that the change in the correlation between the characteristic quantity and the suspended load weight is due to the influence of spline wear. Also, for Hoist C, when diagnosing only based on the magnitude of the characteristic quantity, the characteristic quantity when the suspended load weight (W1) is almost the same for normal and worn conditions. Therefore, it can be seen that it is difficult to diagnose based only on the characteristic quantity. From the above results, it is possible to accurately detect the wear of the spline by diagnosing based on the correlation (magnitude of the slope) between the characteristic quantity and the suspended load weight.

[0055] Finally, an example of a method for evaluating the degree of wear (hereinafter referred to as wear degree D) will be described. In the present embodiment, in order to evaluate the wear degree D of the spline based on the "correlation between the characteristic quantity and the suspended load weight", the following evaluation formula (1) can be considered. D = |S - Sn|…(1) In the above formula, "S" is the slope of the correlation between the characteristic quantity and the suspended load weight at the timing of diagnosis, and "Sn" is the slope of the correlation between the reference characteristic quantity and the suspended load weight (for example, the slope calculated when the spline is new).

[0056] By taking the absolute value of the difference between the slope (S) and the slope (Sn) as the wear degree (D), it is possible to evaluate that the wear is progressing when the amount of change in slope is large. Note that the above formula simply shows the simplest way to evaluate the wear degree (D), and it is not limited to this.

[0057] For example, a cluster of normal slope (Sn) may be defined, and the degree of deviation from that cluster may be evaluated as the wear degree (D). In addition, to increase the sensitivity of the wear degree (D), the slope (S) or slope (Sn) may be weighted by multiplying it by a coefficient, or an index that represents the correlation between the feature amount and the amount of lifted load may be used instead of the slope (S) or slope (Sn).

[0058] Although the above-described embodiment relates to a hoist, it can also be applied to electric vehicles such as electric cars and hybrid cars. That is, when the above-described power source 12 is a lithium power source, the hoist motor 10 is a wheel drive motor, and the hoist device 15 is a wheel, the configuration of this embodiment can be applied when power is transmitted using a spline to the connecting mechanism between the wheel drive motor and the wheel. The current measurement unit measures the current flowing in the wheel drive motor that drives the vehicle, and can diagnose spline wear based on the current flowing in the wheel drive motor.

[0059] As described above, the present invention is characterized by a spline diagnosis device having a current measurement unit that measures a current of an electric motor that drives a spline shaft, a frequency component calculation unit that performs frequency analysis of the current measured by the current measurement unit to calculate specific frequency components, and a condition estimation unit that estimates the wear condition of gears of the spline shaft based on the specific frequency components calculated by the frequency component calculation unit.

[0060] This makes it possible to estimate the wear and deterioration of the gears of the spline shaft based on the current of the electric motor that drives the spline shaft, eliminating the need for open inspection of the spline. Also, because the current sensor is installed on the cable that supplies power to the electric motor, there is an advantage that even if a malfunction occurs in the sensor, there is no need to open the area near the spline shaft.

[0061] The present invention is not limited to the above-described embodiments, but includes various modifications. The above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment. [Explanation of symbols]

[0062] 10...hoisting motor, 11...electric wire, 12...three-phase power supply, 13S...spline shaft, 14...boss, 15...hoisting device, 19...current measuring unit, 20...diagnostic device, 21...display unit, 22...spline, 23...gear, 23f, 23r...tooth surface, 24...concave and concave groove.

Claims

1. A spline diagnostic device for diagnosing the wear state of gears on a spline shaft, a current measuring unit that measures a current of an electric motor that drives the spline shaft; a frequency component calculation unit that performs frequency analysis on the current measured by the current measurement unit to calculate a specific frequency component; a wear state estimation unit that estimates a wear state of the spline shaft based on the specific frequency component calculated by the frequency component calculation unit, the frequency component calculation unit divides the current in a predetermined section measured by the current measurement unit into a plurality of analysis sections, and performs frequency analysis on the current in the analysis sections to calculate the specific frequency component; The wear state estimation unit estimates the wear state of the spline shaft based on information related to the distribution of the specific frequency components in the plurality of analysis sections. A diagnostic device for a spline.

2. In the spline diagnostic device according to claim 1, When the predetermined section is a T section and the analysis section is a Δt section, the current in the T section measured by the current measurement unit is divided into the Δt sections (<T), the frequency component calculation unit performs frequency analysis on the current in the Δt section to calculate the specific frequency component; The wear state estimation unit estimates the wear state of the spline shaft based on information relating to the distribution of the T / Δt number of specific frequency components. A diagnostic device for a spline.

3. In the spline diagnostic device according to claim 2, The specific frequency component is a sideband component of the drive frequency (Fb) of the current in the frequency spectrum obtained by frequency analysis of the current, and is the current intensity of at least one frequency among frequencies (Fb+Fr and Fb-Fr) resulting from the rotation frequency (Fr) of the electric motor. A diagnostic device for a spline.

4. In the spline diagnostic device according to claim 3, The Δt section is greater than the reciprocal (1 / Fb) of the drive frequency (Fb) of the current. A diagnostic device for a spline.

5. A diagnostic device for a spline according to any one of claims 2 to 4, The information relating to the distribution of the specific frequency components is at least one physical quantity selected from the maximum value, minimum value, average value, median value, and mode value of the T / Δt number of specific frequency components. A diagnostic device for a spline.

6. A diagnostic device for a spline according to any one of claims 2 to 4, The information relating to the distribution of the specific frequency components is at least one physical quantity among the variance, standard deviation, skewness, and kurtosis of the T / Δt specific frequency components. A diagnostic device for a spline.

7. A hoist comprising a hoisting mechanism for hoisting / lowering a suspended load, and a hoisting motor for driving said hoisting mechanism, wherein the shaft of said hoisting motor and the boss of said hoisting mechanism are fitted and connected by a spline, The hoist is a diagnostic device including a current measurement unit that measures a current of the hoisting motor that drives a spline shaft of the spline; a frequency component calculation unit that calculates a specific frequency component by performing frequency analysis on the current measured by the current measurement unit; and a wear state estimation unit that estimates a wear state of the spline shaft based on the specific frequency component calculated by the frequency component calculation unit, the frequency component calculation unit divides the current in a predetermined section measured by the current measurement unit into a plurality of analysis sections, and performs frequency analysis on the current in the analysis sections to calculate the specific frequency component; The wear state estimation unit estimates the wear state of the spline shaft based on information related to the distribution of the specific frequency components in the plurality of analysis sections. A hoist characterized by:

8. A hoist comprising a hoisting mechanism for hoisting / lowering a suspended load, and a hoisting motor for driving said hoisting mechanism, wherein the shaft of said hoisting motor and the boss of said hoisting mechanism are fitted and connected by a spline, The hoist is a diagnostic device including a current measurement unit that measures a current of the hoisting motor that drives a spline shaft of the spline; a frequency component calculation unit that calculates a specific frequency component by performing frequency analysis on the current measured by the current measurement unit; and a wear state estimation unit that estimates a wear state of the spline shaft based on the specific frequency component calculated by the frequency component calculation unit, The wear state estimation unit receives the weight of the load as an input in addition to the current of the hoisting motor, and estimates the wear state of the spline shaft based on information related to the distribution of the specific frequency component derived from the weight of the load and the current. A hoist characterized by:

9. An electric vehicle comprising a drive wheel and a wheel drive motor that rotates and drives the drive wheel, and in which power is transmitted to a connecting mechanism between the wheel drive motor and the drive wheel using a spline, The electric vehicle includes: a diagnostic device including a current measurement unit that measures a current of the wheel drive motor that drives a spline shaft of the spline; a frequency component calculation unit that calculates a specific frequency component by performing frequency analysis on the current measured by the current measurement unit; and a wear state estimation unit that estimates a wear state of the spline shaft based on the specific frequency component calculated by the frequency component calculation unit, the frequency component calculation unit divides the current in a predetermined section measured by the current measurement unit into a plurality of analysis sections, and performs frequency analysis on the current in the analysis sections to calculate the specific frequency component; The wear state estimation unit estimates the wear state of the spline shaft based on information related to the distribution of the specific frequency components in the plurality of analysis sections. An electric vehicle characterized by:

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