Spline diagnosis device, hoist, and electric vehicle

Abstract

Provided is a spline diagnosis device, a hoist, and an electric vehicle that can confirm the wear and deterioration state of the gear of a spline shaft without removing the spline shaft from a wheel hub and that does not need to open the vicinity of the spline shaft for sensor maintenance. There are a current measurement section that measures the current of a motor that drives the spline shaft, a frequency component calculation section that calculates a specific frequency component by frequency analyzing the current measured by the current measurement section, and a wear state estimation section that estimates the wear state of the gear of the spline shaft based on the specific frequency component calculated by the frequency component calculation section. Because the wear and deterioration state of the gear of the spline shaft can be estimated based on the current of the motor, there is no need for open inspection of the spline. Because a current sensor is provided in a cable that supplies power to the motor, the vicinity of the spline shaft does not need to be opened even in the event of a failure in the sensor.

Description

Technical Field

[0001] This invention relates to a spline diagnostic device for diagnosing the wear and deterioration of splines, which are part of a transmission mechanism, a winch, and an electric vehicle. Background Technology

[0002] A spline is a connection method used to transmit mechanical rotational force. On one shaft that constitutes the spline (hereinafter referred to as the spline shaft), there are teeth that are machined into the shape of gears on the outer circumference. On the other shaft (hereinafter referred to as the hub), there are grooves that are machined into the shape of gears for insertion into the spline shaft.

[0003] By engaging the splined shaft with the hub, a larger rotational force can be transmitted. Because the splined shaft's gear engages with the hub's grooves, it has the advantage of not slipping even under large rotational forces, compared to transmission mechanisms such as couplings. Therefore, it is often used for transmitting large rotational forces.

[0004] Furthermore, because the gear of the splined shaft engages with the axial grooves formed in the hub, there is a slight gap between them. Therefore, since it is axially movable, it can absorb even a slight axial displacement on one side of the splined shaft or the hub.

[0005] One application of splines is the hoist. A hoist is an industrial machine equipped with an electric motor, which moves a suspended load by raising it by winding up a wire rope and moves it by lowering it by winding down a wire rope.

[0006] In a winch, there is a risk of tilting the load if slip occurs in the rotational force transmission section when lifting a load. To prevent this slip, a spline connection is used when transmitting the rotational force of the motor to the winch mechanism.

[0007] As described above, because there is a tiny gap between the gear on the splined shaft and the groove on the hub, when the motor rotates, there is a phenomenon where the gear located on the outer periphery of the splined shaft contacts the groove on one side of the hub. In the case of a winch, the motor rotates in opposite directions during the lifting and lowering of the load, and during forward and reverse rotation, the tooth surfaces on different sides of the gear contact the wall of the groove on one side.

[0008] Then, with prolonged use of the winch, the tooth surfaces of the splined shaft gears gradually wear and deteriorate, posing a risk of poor transmission of rotational force. Therefore, it is important to regularly inspect the splined shaft to confirm its deterioration condition. However, because the splined shaft gears are engaged with the grooves of the hub, this cannot be visually confirmed while in the engaged state. Consequently, inspection requires removing the splined shaft from the hub for open inspection, resulting in a significant workload. Furthermore, this method cannot predict the signs of malfunction.

[0009] To address this issue, methods described in Japanese Patent Application Publication No. 5-164656 (Patent Document 1) and Japanese Patent Application Publication No. 5-346323 (Patent Document 2) are known as methods for confirming the wear and deterioration of splines without removing the spline shaft from the hub.

[0010] Patent Document 1 describes a method using a vibration sensor installed near the splined shaft. Specifically, because there is a very high correlation between the vibration velocity or vibration acceleration detected by the vibration sensor and the measured wear of the gears on the splined shaft, the wear of the gears on the splined shaft can be estimated based on the value of the vibration velocity or vibration acceleration.

[0011] Furthermore, Patent Document 2 describes a method using a displacement gauge installed in a splined shaft. Specifically, the displacement gauge measures the circumferential clearance when the splined shaft is accelerated or decelerated, and the wear of the gears on the splined shaft is calculated based on the value of this clearance. Thus, the wear of the gears on the splined shaft can be checked without opening the spline.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: Japanese Patent Application Publication No. 5-164656

[0015] Patent Document 2: Japanese Patent Application Publication No. 5-346323 Summary of the Invention

[0016] The problem that the invention aims to solve

[0017] However, the methods described in Patent Documents 1 and 2 require a vibration sensor or displacement gauge to be installed near the splined shaft, which can lead to situations where the sensor cannot be installed due to space constraints. Furthermore, in the event of an malfunction in the vibration sensor or displacement gauge, the area near the splined shaft needs to be opened for the sensor's maintenance.

[0018] The purpose of this invention is to provide a diagnostic device, winch, and electric vehicle that can confirm the wear and deterioration state of the gears of the spline shaft without removing it from the hub, and without exposing the splines near the spline shaft for sensor maintenance.

[0019] Methods for solving problems

[0020] The present invention is a diagnostic device for a spline shaft, characterized in that it comprises: a current measuring unit that measures the current of a motor driving a spline shaft; a frequency component calculation unit that performs frequency analysis on the current measured by the current measuring unit to calculate a specific frequency component; and a wear condition estimation unit that estimates the wear condition of the gear on the spline shaft based on the specific frequency component calculated by the frequency component calculation unit.

[0021] Invention Effects

[0022] According to the present invention, the wear and deterioration state of the gears on the spline shaft can be calculated based on the current of the motor driving the spline shaft, thus eliminating the need for spline opening checks. Furthermore, because a current sensor is installed in the cable supplying power to the motor, it is possible to avoid opening the area near the spline shaft even if a sensor malfunctions. Attached Figure Description

[0023] Figure 1 This is a structural diagram showing the structure of the crane to which the present invention is applied.

[0024] Figure 2(a) is an explanatory diagram showing the engagement state of the spline shaft and the hub, and the state in which the spline teeth and the grooves of the hub are not in contact.

[0025] Figure 2(b) is an explanatory diagram showing the fit between the spline shaft and the hub, and the contact between the spline teeth and the grooves of the hub.

[0026] Figure 3 This is a flowchart illustrating the spline wear diagnosis process according to an embodiment of the present invention.

[0027] Figure 4 This is an explanatory diagram illustrating the process from current measurement to calculation of parameter P (current intensity) in an embodiment of the present invention.

[0028] Figure 5(a) is an illustration of the characteristic quantities of a normal spline.

[0029] Figure 5(b) is an illustration of the characteristic quantities of a worn spline.

[0030] Figure 5(c) is an explanatory diagram illustrating the distribution of the number of operations and characteristic quantities.

[0031] Figure 6This is a structural diagram illustrating the structure of a crane according to another embodiment of the present invention.

[0032] Figure 7(a) illustrates Figure 6 The diagram illustrates the relationship between the normal spline load and characteristic quantity in the winch A in the illustrated embodiment.

[0033] Figure 7(b) illustrates Figure 6 The diagram illustrates the relationship between the weight of the worn spline in winch A and the characteristic quantity in the illustrated embodiment.

[0034] Figure 8(a) illustrates Figure 6 The diagram illustrates the relationship between the normal lifting weight and characteristic quantity of the spline in winch B in the illustrated embodiment.

[0035] Figure 8(b) illustrates... Figure 6 The diagram illustrates the relationship between the weight of the worn spline in winch B and the characteristic quantity in the illustrated embodiment.

[0036] Figure 9(a) illustrates Figure 6 The diagram illustrates the relationship between the normal lifting weight of the spline in the winch C and the characteristic quantity in the illustrated embodiment.

[0037] Figure 9(b) illustrates Figure 6 The diagram illustrates the relationship between the weight of the worn spline in the winch C and the characteristic quantity in the illustrated embodiment.

[0038] Explanation of reference numerals in the attached figures

[0039] 10… Electric motor for hoisting

[0040] 11…electric wires

[0041] 12… power supply

[0042] 13S…spline switch

[0043] 14…wheel hubs

[0044] 15… Hoisting Mechanism

[0045] 19… Current Measurement Unit

[0046] 20…diagnostic devices

[0047] 21… Display Department

[0048] 22… spline

[0049] 23… Gear

[0050] 23f, 23r… tooth surfaces

[0051] 24…groove. Detailed Implementation

[0052] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments, and various modifications and applications of the technical concept of the present invention are also included within its scope.

[0053] In addition, as an example of the application of spline connection, the following example is shown with the spline of a winch as the object, but it is not limited to winches. The present invention can be applied to any spline shaft driven by an electric motor. For example, it can also be applied to mechanisms that drive wheels with electric motors, such as electric vehicles and hybrid vehicles.

[0054] exist Figure 1 The basic structure of a winch is shown in the diagram. For example... Figure 1 As shown, the winch motor 10 is connected to the power supply 12 via wire 11, and a three-phase voltage is applied to the winch motor 10. When the three-phase voltage is applied, the winch motor 10 rotates, and the shaft 13 of the winch motor 10 rotates accordingly. The outer peripheral surface of one end of the shaft 13 is made into a gear shape as a spline shaft 13S, which engages with the groove of the hub 14.

[0055] Thus, the rotational force of the winch motor 10 is transmitted to the winch mechanism (drum) 15. When the winch mechanism 15 rotates, the wire rope 16 mounted on the winch mechanism 15 is wound up, and the hook 17 at the front end and the load 18 fixed to the hook 17 rise. Conversely, when the rotation direction of the winch motor 10 is reversed, the wire rope 16 is unwound, so the hook 17 moves in the downward direction. As a result, the load 18 also moves in the downward direction, enabling unloading.

[0056] Thus, using the rotational force of the hoisting motor 10 to lift the suspended load 18 is the basic operation of the hoist. Additionally, a current measuring unit 19 for measuring current is installed in at least one phase of the power line 11. The current data measured by the current measuring unit 19 is input to the diagnostic device 20 to diagnose the wear and deterioration condition of the spline shaft 13S. The diagnostic results are displayed on the display unit 21.

[0057] in addition, Figure 1 The example shown is an example where the current measurement unit 19 is installed in the wire 11, but if the power supply 12 is an inverter, it is also possible to use information such as the current feedback value or current command value used in the control of the inverter. In addition, the diagnostic device 20 can also be implemented in an electronic component capable of calculation and processing, such as a microcomputer inside the inverter.

[0058] Figure 2(a) shows a cross-section of the spline shaft 13S and the groove of the hub 14.

[0059] The cross-sectional shape of the gear in the spline shaft 13S is one example and is not limited to this. As shown in Figure 2(a), in the spline 22, the gear 23 of the spline shaft 13S and the groove 24 of the hub 14 are axially engaged. Because they can be engaged, there is a small gap G between the gear 23 and the groove 24. The gears 23 are arranged at certain intervals in the circumferential direction on the spline shaft 13S. On the gears 23, tooth surfaces 23f and 23r that contact the groove 24 of the hub 14 are formed.

[0060] On the other hand, Figure 2(b) is a diagram of the spline shaft 13S rotating as the drive shaft. When the spline shaft 13S rotates in the direction of arrow (F), the tooth surface 23f of the gear 23 contacts the wall of the groove 24 of the hub 14, so the rotational force is transmitted from the spline shaft 13S to the hub 14.

[0061] Although the illustration is omitted, when the spline shaft 13S rotates to the side opposite to the direction of arrow (F), the tooth surface 23r of gear 23 contacts the opposite wall surface of the groove 24 of hub 14, transmitting the rotational force in the opposite direction of arrow (F) to hub 14.

[0062] In the case of a winch, for example, rotating in the direction of arrow (F) raises the load 18, and rotating in the opposite direction of arrow (F) lowers the load 18. Because of these repeated actions, the spline shaft 13S rotates repeatedly in both directions, thereby causing wear or damage to the tooth surfaces 23f and 23r, and the wear progresses.

[0063] Furthermore, as mentioned above, because the actions differ in the forward and reverse directions, the wear on the tooth surfaces 23f and 23r of gear 23 may not progress uniformly. Moreover, as wear progresses on tooth surfaces 23f and 23r, there is a risk of gear 23 losing its function and resulting in poor transmission of rotational force. Therefore, it is necessary to detect the deterioration of gear 23 before it loses its function.

[0064] Next, the operation (wear detection method) of the spline diagnostic device 20 proposed in this invention to address the aforementioned issues will be explained. Furthermore, the following description can also be applied to diagnosing and predicting fault occurrence.

[0065] exist Figure 3 The flowchart shown below illustrates the processing flow of the diagnostic device 20. Figure 4 This describes a method for fault diagnosis based on current.

[0066] In "Step S1", as Figure 4As shown in (a), the current flowing through the hoisting motor 10 in the Δt interval is obtained using the current measurement unit 19. The method for obtaining the current in the Δt interval can be to proceed to "step S2" (calculation sequentially) after only the Δt interval has been obtained, or to divide the data into each Δt interval and proceed to step S2 (calculation at any time) after measuring the data of the entire interval (here, interval T).

[0067] Next, in steps S2 to S4, as follows: Figure 4 As shown in (b), the frequency spectrum is calculated by performing a Fast Fourier Transform (FFT) on the current in the Δt interval. The current spectrum is as follows: Figure 4 (b) shows the characteristic of having a peak at the fundamental frequency of the current, which decreases towards the low-frequency and high-frequency sides.

[0068] Extract the spectrum of a specific frequency from the spectrum as parameter P and store it. In the example of diagnosing the spline of a winch, extract the specific frequency component appearing in the sideband of the fundamental frequency of the current. Figure 4 The value of the part indicated by arrow (P) in (b) is used as the parameter P (current intensity).

[0069] The aforementioned specific frequency components are the sideband components of the current driving frequency (Fb) in the spectrum obtained by frequency analysis of the current, and are the current intensity of at least one of the frequencies (Fb+Fr and Fb-Fr) caused by the rotational frequency (Fr) of the motor.

[0070] In this embodiment, the rotational vibration caused by wear on the tooth surface of the gear 23 of the splined shaft 13S of the winch is detected using the current flowing through the winch motor 10. In this embodiment, to extract multiple parameters P from the current data of a single drive of the winch motor 10, the data in the T interval is divided into multiple Δt intervals (T > Δt), and the parameters P are calculated for each Δt interval. Here, the Δt interval is set to be greater than the reciprocal (1 / Fb) of the current drive frequency (Fb).

[0071] By dividing the data in this way, we can calculate and store T / Δt parameters P. Then, the stored parameters P become... Figure 4 The frequency distribution is shown in (c). As will be described later, the diagnosis focuses on the changes in the distribution of parameter P due to the effects of rotational vibration caused by wear of spline 22.

[0072] Therefore, in "Step S5", it is determined whether T / Δt (the specified number) of parameters P have been stored. If the specified number of parameters P have not been stored, the process returns to "Step S1" and performs the same procedure. On the other hand, if the specified number of parameters P have been stored, the process proceeds to "Step S6".

[0073] In "Step S6", a statistic related to the distribution of the T / Δt parameters P (hereinafter referred to as the parameter set) is extracted as a feature quantity. Specific examples of the statistic are as follows. Figure 4 In the frequency distribution of (c), in addition to the maximum and minimum values ​​and the average value, there are also the median, which represents the position where the areas to the left and right 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 quantity.

[0074] In addition, the range (difference between the maximum and minimum), variance, and standard deviation can also be used as statistics representing the width of the distribution. Furthermore, skewness or kurtosis can be used as statistics representing the shape of the frequency distribution. Moreover, the feature quantity is not limited to one; multiple statistics can be used, or new evaluation indicators calculated from multiple statistics can be used as feature quantities. Thus, the key is to use statistics that provide information related to the distribution of the parameter set as feature quantities.

[0075] Finally, in "Step S7", the spline state is determined based on the feature quantity (average value). To illustrate the determination method, firstly, the feature quantity (average value) of spline 22 in a normal state is used as learning data (the judgment benchmark = threshold). Next, the deviation between the feature quantity (average value) at the time of diagnosis and the learning data (the judgment benchmark = threshold) is calculated. If this deviation exceeds a predetermined deviation, it is determined that "the spline state is abnormal (worn)".

[0076] Figures 5(a) and 5(b) show the frequency distribution of parameter P when the spline 22 of the winch is in a normal state and when wear has progressed. Only the state of the spline 22 differs; the load and operating time remain the same.

[0077] As shown in Figures 5(a) and 5(b), the frequency distribution shapes differ depending on the wear state of the gear 23 on the spline shaft 13S of the spline 22. In this example, compared to the frequency distribution of the spline 22 in Figure 5(a) under normal conditions, the average value of parameter P is lower in the frequency distribution of the deteriorated spline 22 in Figure 5(b). Thus, the wear of the gear 23 on the spline shaft 13S can be determined using characteristic quantities.

[0078] Figure 5(c) shows the results confirming reproducibility. This is the result of installing spline 22 in normal condition and spline 22 with progressive wear in the winch and running it multiple times, extracting characteristic quantities (in this case, the average value of parameter P) based on the current data of each run.

[0079] As shown in Figure 5(c), if the same conditions are met, the characteristic quantity shifts steadily, and the magnitude of the characteristic quantity can be used to determine whether the gear 23 of the spline shaft 13S is normal or has progressed in wear. Thus, in this embodiment, based on the phenomenon that the distribution of parameter P calculated from the current changes due to the wear state of the spline 22 under the same operating conditions, the wear state of the spline 22 is diagnosed. Furthermore, regarding parameter P, current intensity is used in this embodiment, but it is not limited to any parameter that represents spline wear.

[0080] Next, in Figure 6 The diagram illustrates an implementation method for improving the diagnostic accuracy of spline 22. In this implementation, in the above-described... Figure 1 This differs from other designs by adding a suspended weight gauge 25 as a diagnostic input. The principle behind this additional suspended weight gauge improving diagnostic accuracy will be explained below.

[0081] Figures 7-9 show the results of measuring the current of the winch motor 10 when three different winches (A, B, and C) are driven with varying lifting weights to three different loads (W1 < W2 < W3), and calculating the average values ​​of the aforementioned characteristic quantities (parameter P shown in Figures 5(a) and 5(b)). These represent characteristic quantities obtained by repeatedly operating the winch under each lifting weight, and are the results of an evaluation including measurement deviations.

[0082] Figure 7(a) is a graph showing the correlation between a characteristic quantity obtained from the current of the winch motor 10 measured when the spline of winch A is installed normally and the weight of the load. On the other hand, Figure 7(b) is a graph showing the correlation between a characteristic quantity obtained from the current of the winch motor 10 measured when only the spline of winch A is replaced with a worn part and the weight of the load.

[0083] As shown in Figure 7(a), under normal spline conditions, the increase in characteristic quantity relative to the weight of the load (W1 < W2 < W3) is positively correlated (the slope Sn is positive). In contrast, as shown in Figure 7(b), under worn spline conditions, the increase in characteristic quantity relative to the weight of the load (W1 < W2 < W3) is negatively correlated (the slope Sd is negative).

[0084] In this study, since only the spline was changed from a normal product to a worn product, the change in the correlation between the characteristic quantity and the load weight can be considered to be the effect of spline wear. Therefore, spline wear can be diagnosed based on the correlation between the characteristic quantity and the load weight (e.g., the difference between slope Sn and slope Sd).

[0085] Furthermore, the reason for diagnosing based on the correlation between the characteristic quantity and the load weight, rather than the magnitude of the characteristic quantity, will be explained. For example, in the examples of Figures 7(a) and 7(b), the characteristic quantity for the load weight (W2) is approximately the same for both normal and worn splines, so it can be seen that diagnosis is difficult using only the characteristic quantity. On the other hand, by evaluating the characteristic quantity to include other load weights (W1 and W3), spline wear can be diagnosed with good accuracy.

[0086] Next, examples using other winches (denoted as winch B) are shown in Figures 8(a) and 8(b). In the case of winch B, both with a normal spline and with a worn spline, the correlation between the characteristic quantity and the weight of the load is positive (both slope Sn and slope Sd are positive). However, it is known that the magnitude of the slope is "Sn > Sd".

[0087] In this case study, as mentioned above, only the spline in winch B was changed from a normal product to a worn product. Therefore, it can be inferred that the change in the correlation between the characteristic quantity and the weight being lifted is due to the wear of the spline. Thus, this case study also demonstrates that spline wear can be detected based on the correlation (the magnitude of the slope) between the characteristic quantity and the weight being lifted.

[0088] Furthermore, similar to winch A, when diagnosing using only the magnitude of the characteristic quantity, the characteristic quantity for the load weight (W2) is approximately the same for both normal and worn splines. Therefore, it can be concluded that diagnosing using only the characteristic quantity is insufficient. Based on the above results, by performing diagnosis based on the correlation between the characteristic quantity and the load weight, spline wear can be detected with good accuracy.

[0089] Next, an example is studied using another winch (referred to as winch C), as shown in Figures 9(a) and 9(b). In the case of winch C, both with a normal spline and with a worn spline, the correlation between the characteristic quantity and the weight of the load is negative (both slope Sn and slope Sd are negative). However, it is known that the magnitude of the slope is "Sn < Sd".

[0090] In this case study, similar to winches A and B mentioned above, only the spline was changed from a normal product to a worn product. Therefore, it can be inferred that the change in the correlation between the characteristic quantity and the lifting weight is due to the wear of the spline. Furthermore, for winch C, also under the condition of diagnosis using only the magnitude of the characteristic quantity, the characteristic quantity at the lifting weight (W1) is approximately the same value in both the normal and worn states. Therefore, it can be concluded that diagnosis using only the characteristic quantity is insufficient. Based on the above results, diagnosis based on the correlation (slope) between the characteristic quantity and the lifting weight can accurately detect spline wear.

[0091] Finally, an example of a method for evaluating the degree of wear (hereinafter referred to as wear degree D) will be described. In this embodiment, since the wear degree D of the spline is evaluated based on the "correlation between the characteristic quantity and the weight of the load", the evaluation formula (1) described below can be considered.

[0092] D=|S-Sn|…(1)

[0093] In the above formula, "S" is the slope of the correlation between the characteristic quantity during diagnosis and the weight of the suspended load, and "Sn" is the slope of the correlation between the characteristic quantity used as a benchmark and the weight of the suspended load (e.g., the slope calculated when the spline is new).

[0094] By using the absolute value of the difference between the slope (S) and the slope (Sn) as the wear degree (D), it is possible to assess the progress of wear when the change in slope is large. However, the above formula only represents the simplest method for evaluating the wear degree (D) and is not limited to this.

[0095] For example, a cluster of slopes (Sn) under normal conditions can be defined, and the deviation from this cluster can be evaluated as wear degree (D). Alternatively, to improve the sensitivity of wear degree (D), slopes (S) and (Sn) can be weighted by multiplying them by a coefficient, or an index representing the correlation between the characteristic quantity and the load weight can be used instead of slopes (S) and (Sn).

[0096] The above-described embodiments relate to winches, but can also be applied to electric vehicles such as electric vehicles and hybrid vehicles. That is, when the power supply 12 is replaced with a lithium power supply, the winch motor 10 is replaced with a wheel drive motor, and the winch device 15 is replaced with a wheel, the structure of this embodiment can be applied when a spline is used to transmit power in the connection mechanism between the wheel drive motor and the wheel. Then, the current measurement unit can measure the current flowing through the wheel drive motor driving the vehicle and diagnose spline wear based on the current flowing through the wheel drive motor.

[0097] Thus, the present invention is a diagnostic device for a spline shaft, characterized by comprising: a current measuring unit that measures the current of a motor driving a spline shaft; a frequency component calculation unit that performs frequency analysis on the current measured by the current measuring unit to calculate a specific frequency component; and a state estimation unit that estimates the wear state of the gears on the spline shaft based on the specific frequency component calculated by the frequency component calculation unit.

[0098] Therefore, since the wear and deterioration of the gears on the spline shaft can be calculated based on the current of the motor driving the spline shaft, there is no need to check for spline opening. Furthermore, because a current sensor is installed in the cable supplying power to the motor, it is possible to avoid opening the area near the spline shaft even if a sensor malfunctions.

[0099] Furthermore, the present invention is not limited to the above-described embodiments, but includes various modifications. The above embodiments are described in detail for ease of understanding of the present invention and are not limited to having all the structures described. Additionally, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, or the structure of another embodiment can be added to the structure of one embodiment. Furthermore, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

Claims

1. A spline diagnostic device for diagnosing the wear condition of gears on a splined shaft of a winch, the winch comprising a winching mechanism for lifting / lowering a load and a winching motor for driving the winching mechanism, the shaft of the winching motor being engaged with the hub of the winching mechanism via the spline, the spline diagnostic device being characterized in that it has: A current measuring unit measures the current of the motor that drives the splined shaft; The frequency component calculation unit performs frequency analysis on the current measured by the current measurement unit to calculate specific frequency components; and The wear condition estimation unit estimates the wear condition of the spline shaft based on specific frequency components calculated by the frequency component calculation unit. In addition to the current of the hoist motor, the wear condition estimation unit also inputs the weight of the hoisted load, and estimates the wear condition of the spline shaft based on the weight of the hoisted load and information related to the distribution of the specific frequency component derived from the current.

2. The diagnostic device for splines as described in claim 1, characterized in that: The frequency component calculation unit divides the current within a specified range measured by the current measurement unit into multiple analysis intervals, and performs frequency analysis on the current in the analysis intervals to calculate the specific frequency component. The wear condition estimation unit estimates the wear condition of the spline shaft based on information related to the distribution of the specific frequency components in multiple analysis intervals.

3. The diagnostic device for splines as described in claim 2, characterized in that: When the specified interval is defined as interval T and the analysis interval is defined as interval Δt, the current measured by the current measurement unit in interval T is divided into interval Δt (<T). The frequency component calculation unit performs frequency analysis on the current in the Δt interval 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 (T / Δt).

4. The diagnostic device for splines as described in claim 3, characterized in that: The specific frequency component is the sideband component of the driving frequency (Fb) of the current in the 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) caused by the rotational frequency (Fr) of the motor.

5. The diagnostic device for splines as described in claim 4, characterized in that: The Δt interval is greater than the reciprocal (1 / Fb) of the driving frequency (Fb) of the current.

6. The diagnostic device for splines as described in any one of claims 3 to 5, characterized in that: Information related to the distribution of the specific frequency component is at least one physical quantity among the maximum, minimum, average, median, and mode of the T / Δt specific frequency components.

7. The diagnostic device for splines as described in any one of claims 3 to 5, characterized in that: Information related to the distribution of the specific frequency component is at least one of the following physical quantities: variance, standard deviation, skewness, and kurtosis of the T / Δt specific frequency components.

8. A winch comprising a winching mechanism for raising / lowering a suspended load, and a winching motor for driving the winching mechanism, wherein the shaft of the winching motor is splinedly engaged with the hub of the winching mechanism, the winch being characterized in that: The winch has a diagnostic device, which includes: A current measuring unit that measures the current of the hoisting motor that drives the spline shaft of the spline; A frequency component calculation unit performs frequency analysis on the current measured by the current measurement unit to calculate a specific frequency component; and a wear condition estimation unit estimates the wear condition of the spline shaft based on the specific frequency component calculated by the frequency component calculation unit. In addition to the current of the hoist motor, the wear condition estimation unit also inputs the weight of the hoisted load, and estimates the wear condition of the spline shaft based on the weight of the hoisted load and information related to the distribution of the specific frequency component derived from the current.

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