Diagnostic method for scrolling device, diagnostic device, and program

Abstract

In a method for diagnosing a rolling device provided with a rolling element and a peripheral member of the rolling element, an AC voltage is applied to a circuit comprising the rolling element and the peripheral member, and the impedance and phase angle when the AC voltage is applied are measured. The measured impedance and the measured phase angle are corrected using a correction formula based on a Kirchhoff's law solution, the correction formula being defined in accordance with the resistance and reactance of a wiring component in the circuit, and the correction formula being configured to correct the measured impedance and the measured phase angle based on the corrected impedance and the corrected phase angle. And calculating the thickness of the lubricating film and the metal contact ratio.

Description

Technical Field

[0001] The present invention relates to a diagnostic method, a diagnostic device and a program for a rolling device. Background Art

[0002] Rolling devices such as bearings are used in a wide range of industrial fields, such as automobiles and various industrial machinery. From the perspective of ensuring the smooth operation of the machinery and the life of the rolling device, it is extremely important to understand the internal lubrication state of the rolling device. By properly understanding it, various lubricants (oil, grease, etc.) can be supplied and the rolling device can be replaced at the best time, without excessive or insufficient maintenance. However, since it is difficult to directly observe the lubrication state visually, a method of monitoring vibration, sound, and oil film state has been proposed as a diagnostic method for rolling devices.

[0003] For example, Patent Document 1 discloses a method for diagnosing the lubrication state inside a rolling device by applying an AC power supply to the rolling device, measuring impedance and phase angle, and calculating lubricant film thickness and metal contact ratio.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6380720 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The lubricating film thickness and the metal contact ratio can be calculated by the method of Patent Document 1. On the other hand, in the method of Patent Document 1, there is a problem that the measurement accuracy may be reduced under the condition that the lubricating film thickness is lower than a certain value, such as when the rotation speed of the rolling device to be diagnosed is low.

[0009] In view of the above-mentioned problems, an object of the present invention is to provide a method for diagnosing the lubrication state inside a rolling device with higher accuracy than conventional methods.

[0010] Means for solving problems

[0011] In order to solve the above-mentioned problems, the present invention has the following configuration. That is, a rolling device diagnostic method is a rolling device diagnostic method having a rolling element and a peripheral component of the rolling element, wherein:

[0012] applying an AC voltage to a circuit formed by the rolling element and the peripheral components,

[0013] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0014] The measured impedance and the measured phase angle are corrected using a modified formula of the solution based on Kirchhoff's law, the modified formula being a modified formula of the solution based on Kirchhoff's law defined corresponding to the resistance and reactance of the wiring components in the circuit.

[0015] Based on the corrected impedance and the corrected phase angle, the lubricating film thickness and the metal contact ratio between the peripheral component and the rolling element are calculated.

[0016] In addition, another aspect of the present invention has the following configuration. That is, a diagnostic device for a rolling device, characterized in that it is a diagnostic device for a rolling device having a rolling element and a peripheral component of the rolling element, and has:

[0017] An acquisition unit that acquires the impedance and phase angle of the circuit when an alternating voltage is applied to the circuit composed of the rolling element and the peripheral component;

[0018] A correction unit that corrects the acquired impedance and the acquired phase angle using a modified formula of the solution based on Kirchhoff's law, the modified formula being a modified formula of the solution based on Kirchhoff's law defined corresponding to the resistance and reactance of the wiring components in the circuit; and

[0019] A calculation unit that calculates the lubricating film thickness and the metal contact ratio between the peripheral component and the rolling element based on the corrected impedance and the corrected phase angle.

[0020] In addition, another aspect of the present invention has the following configuration. That is, a program

[0021] The program causes a computer to function as an acquisition unit, a correction unit, and a calculation unit,

[0022] The acquisition unit acquires the impedance and phase angle of the circuit when an alternating voltage is applied to the circuit composed of a rolling element and a peripheral component of the rolling element in the rolling device,

[0023] The correction unit corrects the acquired impedance and the acquired phase angle using a modified formula of the solution based on Kirchhoff's law, the modified formula being a modified formula of the solution based on Kirchhoff's law defined corresponding to the resistance and reactance of the wiring components in the circuit,

[0024] A calculation unit that calculates the lubricating film thickness and the metal contact ratio between the peripheral component and the rolling element based on the corrected impedance and the corrected phase angle.

[0025] Advantages of the Invention

[0026] According to the present invention, the lubrication state inside the rolling device can be diagnosed with higher accuracy than before. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram showing a configuration example of a system to which the diagnostic processing according to one embodiment of the present invention can be applied.

[0028] Figure 2 This is a conceptual diagram for explaining the contact area of ​​a rolling bearing.

[0029] Figure 3 This is a circuit diagram for explaining an equivalent circuit around the contact area of ​​a rolling bearing.

[0030] Figure 4 This is a circuit diagram for explaining an equivalent circuit of a conventional rolling bearing.

[0031] Figure 5 This is a circuit diagram for explaining an equivalent circuit of a rolling bearing according to one embodiment of the present invention.

[0032] Figure 6 This is a flowchart of a diagnostic process according to one embodiment of the present invention.

[0033] Figure 7 This is a diagram for explaining problems in conventional methods.

[0034] Fig. 8A It is a graph for explaining the diagnosis result of the conventional method.

[0035] Figure 8B This is a graph for explaining the diagnosis results of the diagnosis method according to one embodiment of the present invention.

[0036] Fig.9A This is a graph for explaining the comparison results between the diagnostic method according to one embodiment of the present invention and the conventional method.

[0037] Fig. 9B This is a graph for explaining the comparison results between the diagnostic method according to one embodiment of the present invention and the conventional method. DETAILED DESCRIPTION

[0038] Hereinafter, the mode for implementing the present invention will be described with reference to the accompanying drawings and the like. In addition, the embodiment described below is used to illustrate one embodiment of the present invention and is not intended to limit the present invention. In addition, all structures described in each embodiment are not limited to structures necessary to solve the problems of the present invention. In addition, in each of the drawings, the same constituent elements are indicated by marking the same reference numerals to indicate the corresponding relationship.

[0039] <First Embodiment>

[0040] Hereinafter, the first embodiment of the present invention will be described. In addition, in the following description of the device structure, a ball bearing is used as an example, but it is not limited to this, and the present invention can also be applied to devices of other structures. For example, it can also be applied to rolling bearings such as rolling elements (needle-shaped, conical, cylindrical). In addition, it is not limited to rolling bearings, and can generally be applied to devices having structures such as ball screws, linear guides, actuators, sliding bearings, and engine pistons. As examples of such devices, mobile bodies such as automobiles, two-wheeled vehicles, and railway vehicles, industrial machinery, machine tools, etc. can be listed.

[0041] Figure 1 1 is a schematic diagram showing an example of the overall structure of a diagnosis device 30 that executes the diagnosis method of this embodiment. Figure 1 A bearing device 10 to which the diagnostic method of this embodiment is applied and a diagnostic device 30 for performing the diagnosis are provided. It should be noted that, Figure 1 The structure shown is an example, and a different structure may be used depending on the structure of the bearing device 10, etc. Figure 1 In FIG. 1 , the bearing device 10 is shown to include two rolling bearings 8 , but the present invention is not limited thereto and a plurality of rolling bearings may be provided.

[0042] The bearing device 10 is configured to include a ball bearing as a rolling bearing. In the bearing device 10, the rolling bearing 8 is provided around the rotating shaft 7 to support the rotating shaft 7 so as to be rotatable. A load is applied to the bearing device 10 in a predetermined direction by a load device (not shown). In the present embodiment, a case where a radial load is applied in a direction orthogonal to the rotating shaft 7 by the load device is described, but the direction of the load is not particularly limited.

[0043] The rolling bearing 8 is composed of an outer ring 1, an inner ring 3, a plurality of rolling elements 5 (balls in this example), and a retainer (not shown) that holds the rolling elements 5 so that they can roll freely. Here, the outer ring 1 is a fixed ring, and the inner ring 3 is a rotating ring. Figure 1 Although not shown in the figure, the shape of the retainer is not particularly limited, and can be changed according to the shape of the rolling element 5, for example. In addition, the shape of the peripheral parts of the rolling element 5, such as the outer ring 1 and the inner ring 3, and the structure of the rolling surface can also be different according to the structure of the rolling device. Inside the rolling bearing 8, the friction between the outer ring 1 and the rolling element 5, and between the inner ring 3 and the rolling element 5 is reduced by a predetermined lubrication method. The lubrication method is not particularly limited, and for example, grease lubrication, oil lubrication, etc. are used to supply it to the inside of the rolling bearing 8. There is no particular limitation on the type of lubricant.

[0044] The motor 14 is a driving motor, and provides power to the rotating shaft 7 by rotating. The rotating shaft 7 is connected to the LCR meter 20 via the rotating connector 12. The rotating connector 12 can be formed using, for example, a carbon brush or a slip ring, but is not limited thereto. In addition, the rolling bearing 8 of the bearing device 10 is also electrically connected to the LCR meter 20, and at this time, the LCR meter 20 also functions as an AC power supply for the bearing device 10.

[0045] The diagnostic device 30 operates as a diagnostic device capable of executing the diagnostic method of the present embodiment. During diagnosis, the diagnostic device 30 uses the angular frequency ω and the AC voltage V of the AC power supply as inputs to indicate the LCR meter 20, and obtains the impedance |Z| (|Z| represents the absolute value of Z) and the phase angle θ of the bearing device 10 from the LCR meter 20 as corresponding outputs. Then, the diagnostic device 30 uses these values ​​to diagnose the bearing device 10. The details of the diagnostic method will be described later.

[0046] The diagnostic device 30 can be realized, for example, by an information processing device that includes a control device, a storage device, and an output device (not shown). The control device can be composed of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Single Processor), or a dedicated circuit. The storage device is composed of volatile and non-volatile storage media such as HDD (Hard Disk Drive), ROM (Read Only Memory), and RAM (Random Access Memory), and can input and output various information according to instructions from the control device. The output device is composed of a display device such as a speaker, a lamp, or a liquid crystal display, and notifies the operator according to instructions from the control device. The notification method of the output device is not particularly limited, for example, it can be an auditory notification based on sound, or it can be a visual notification based on screen output. In addition, the output device can be a network interface with a communication function, and can also perform a notification action by sending data to an external device (not shown) via a network (not shown). The content of the notification here is not limited to, for example, the result of the diagnosis or notification when an abnormality is detected, but may include notification indicating that the bearing device 10 is normal.

[0047] [Physical model]

[0048] use Figure 2 The contact state between the rolling element 5 and the outer ring 1 (or the inner ring 3 ) in the bearing device 10 will be described. Figure 2This is a diagram showing the physical model when the spherical piece and the disc piece are in contact. The spherical piece corresponds to the rolling element, and the disc piece corresponds to the outer ring 1 (or inner ring 3). The h-axis represents the direction of the oil film thickness (lubricating film thickness), and the y-axis represents the direction orthogonal to the oil film thickness direction. The h-axis sets the surface of the disc piece to 0, and the y-axis sets the axis passing through the center of the spherical piece to 0. In addition, Figure 2 The variables shown are as follows.

[0049] S 1 : Hertzian contact area (Hertzian contact area)

[0050] c: Hertz contact circle radius (=√(S 1 / π)

[0051] α: Oil film rupture rate (metal contact ratio) (0≤α<1)

[0052] r b : The radius of the spherical piece

[0053] αS 1 :Actual contact area (break area of ​​oil film)

[0054] h: Oil film thickness

[0055] h 1 : Oil film thickness in the Hertzian contact area

[0056] In the Hertzian contact region, the ratio of the metal contact range to the non-contact range is α:(1-α). In addition, in the ideal state where the spherical plate and the disc plate are not in contact, α=0, and h>0 when y=0.

[0057] Figure 2 The oil film thickness h shown is expressed by the following formula.

[0058] h=0(-αS 1 / 2≤y≤αS 1 / 2)

[0059] h=h 1 (-c≤y<-αS 1 / 2 or αS 1 / 2 <y≤c)

[0060] h=h 1 +√(r b 2 -c 2 )-√(r b 2 - y 2 ) (-r b ≤y<-c or c <y≤r b ) (1)

[0061] It should be noted that in an actual rolling bearing, the rolling element 5 undergoes elastic deformation when subjected to a load, and therefore is not strictly a sphere, but in this embodiment, the above formula (1) is used as a sphere. Therefore, the formula used when calculating the oil film thickness is not limited to formula (1), and other calculation formulas may also be used. In addition, in the above, a two-dimensional formula is used for explanation, but a three-dimensional formula may also be used for calculation.

[0062] [Equivalent circuit]

[0063] Figure 3 It is expressed as an electrically equivalent circuit (equivalent circuit) Figure 2 The equivalent circuit E1 includes a resistor R 1 、Capacitor C 1 and capacitor C 2 . Resistance R 1 Equivalent to the fracture area (=αS 1 ) in the resistor. Capacitor C 1 The capacitance C is equivalent to the capacitor formed by the oil film in the Hertzian contact area. 1 . Capacitor C 2 Equivalent to the periphery of the Hertz contact area ( Figure 2 -r b ≤y<-c and c<y≤r b ) is formed by the oil film, and the electrostatic capacitance C 2 . Hertz contact area (=S 1 )form Figure 3 The resistor R in the equivalent circuit E1 is 1 With capacitor C 1 In addition, capacitor C 2 With the resistor R 1 and capacitor C 1 The circuits formed are connected in parallel. At this time, around the Hertz contact area ( Figure 2 -r b ≤y<-c and c<y≤r b ) is filled with lubricant.

[0064] The impedance of the equivalent circuit E1 is represented by Z. Here, the AC voltage V applied to the equivalent circuit E1, the current I flowing through the equivalent circuit E1, and the complex impedance Z of the entire equivalent circuit E1 are represented by the following equations (2) to (4).

[0065] V=|V|exp(jωt) (2)

[0066] I=|I|exp(j(ωt-θ)) (3)

[0067] Z=V / I=|V / I|exp(jθ)=|Z|exp(jθ) (4)

[0068] j: imaginary number

[0069] ω: angular frequency of AC voltage

[0070] t: time

[0071] θ: Phase angle (phase difference between voltage and current)

[0072] Figure 4 is based on Figure 3 The equivalent circuit E1 shown shows Figure 1 The figure shows the electrical equivalent circuit around the rolling element 5. If we focus on one rolling element 5, an equivalent circuit E2 is formed between the outer ring 1 and the rolling element 5, and between the inner ring 3 and the rolling element 5. Here, the upper side is described as a circuit formed by the outer ring 1 and the rolling element 5, and the lower side is described as a circuit formed by the inner ring 3 and the rolling element 5, but the reverse is also possible. Around one rolling element 5, these circuits are connected in series to form an equivalent circuit E2. In addition, although Figure 4 and Figure 5 Although only one equivalent circuit E2 is shown in the figure, actually, the same number of equivalent circuits E2 as the number of rolling elements are connected in parallel.

[0073] [About existing methods]

[0074] Here, as a comparative example with the diagnosis method of one embodiment of the present invention, Patent Document 1 is described as a conventional method. Although detailed description is omitted, in Patent Document 1, diagnosis is performed using the following equations (5) and (6) based on a model composed of the rolling element and its peripheral components as described above.

[0075] [Number 1]

[0076]

[0077] [Number 2]

[0078]

[0079] h: Oil film thickness (corresponding to Figure 2 h 1 )

[0080] α: Metal contact ratio

[0081] ω: angular frequency of AC voltage

[0082] ε 1 : Dielectric constant of lubricant

[0083] S: The average value of the area of ​​each contact ellipse when each contact area is approximated as a contact ellipse

[0084] n: The number of rolling elements (balls) in the bearing assembly

[0085] Z: The impedance of the entire circuit

[0086] θ: Phase angle

[0087] R 20 : The resistance of the metal contact part without any oil film

[0088] θ 1 : Phase angle in the state where the oil film is completely present (the state where there is no contact area with the metal parts)

[0089] L: Inductance connected in series with the bearing assembly

[0090] R: resistance connected in series with the bearing assembly

[0091] Fig. 8A is a graph used to illustrate the diagnostic results of the existing method. Fig. 8A In the figure, the left vertical axis represents the logarithm of the oil film thickness, the right vertical axis represents the logarithm of the metal contact ratio, and the horizontal axis represents the logarithm of the rotation speed of the rotating shaft. The horizontal axis has higher values ​​as it goes to the right. Fig. 8A The dashed line represents the approximate theoretical oil film thickness calculated using the well-known Hamrock-Dowson formula. According to the Hamrock-Dowson formula, the oil film thickness is proportional to the speed, so Fig. 8A A straight line with the slope shown.

[0092] Reference Fig. 8A The higher the rotation speed, the higher the oil film thickness, and the lower the metal contact ratio. In addition, below a certain rotation speed, the diagnostic results of the existing method show a tendency to deviate from the theoretical oil film thickness value. On the other hand, when the rotation speed is further reduced, there is a situation where the oil film thickness cannot be calculated. In addition, below a certain rotation speed, the metal contact ratio rises sharply, and the output is an unreasonable value exceeding 1.

[0093] One of the reasons why the measurement accuracy is reduced (or cannot be calculated) when the rotating shaft is at a low speed as described above is considered to be related to the use of cosθ as a main factor in calculating the oil film thickness in the above-mentioned formula (1) and formula (2) in the method of Patent Document 1. That is, in the method of Patent Document 1, the initial value and the measured value are used, and the ratio of their cosθ is used.

[0094] In the case of the conventional method, the impedance Z and the phase angle θ are the same in both the case when the rotating shaft is stopped (i.e., the initial value) and the case when the rotating shaft is running (i.e., the measured value). Figure 7 (a) is in the fourth quadrant. Figure 7 In the figure, the horizontal axis represents resistance (R) and the vertical axis represents reactance (C+L). In the fourth quadrant, the impedance Z is positive and the phase angle θ is negative. In actual measurement, Figure 7 As shown in (b), the impedance Z and the phase angle θ are sometimes located in the first quadrant. That is, when the impedance Z and the phase angle θ are both positive, it is outside the application condition range of the above equations (1) and (2). As a result, we get Fig. 8A That's the diagnosis.

[0095] [Diagnostic method of this embodiment]

[0096] In the diagnostic method of the present embodiment, a diagnostic method with higher accuracy than the above-mentioned existing methods is provided. In the present embodiment, a method that takes into account the wiring structure of the diagnostic object is used with an eye on the structure of the diagnostic object. When performing a diagnosis, for example, in order to connect a rolling device and an LCR meter, a certain length of wiring must be required. In the existing impedance method shown in Patent Document 1, since a certain high-frequency AC voltage is used, it is believed that there is an influence of the wiring. The inventors have determined through analysis, etc. that: in particular, in the low-speed area where the oil film is thin and in the initial value measured when stopped, the impedance of the wiring component in the measured value becomes the dominant factor. The wiring component here includes, in addition to the wiring for connecting the rolling device and the LCR meter, terminal contacts (not shown) configured on the wiring are also included. Therefore, the inventors have taken into account the influence of the wiring and corrected the parameters used in the previous method, thereby correcting the situation outside the application condition range of the above-mentioned Patent Document 1 to within the application range, thereby improving the diagnostic accuracy.

[0097] Figure 5 It is to use Figure 4 The circuit described above further considers the wiring circuit diagram. As mentioned above, the circuit to be measured includes resistance R corresponding to wiring and terminal contacts. E With reactance L E Therefore, the value calculated by the above formula (1) is equivalent to Figure 5 In this embodiment, the circuit shown in FIG. 1 is derived by removing the resistor R from Z. E and reactance L E Z C .

[0098] Z C =|Z C |exp(jθ c ) (7)

[0099] In this embodiment, based on Figure 5 The circuit shown in FIG. 1 uses a correction formula based on the solution of Kirchhoff's law. Moreover, this correction formula can be used to calculate the value of the measured value both when the system is stopped (i.e., the initial value) and when the system is running (i.e., the measured value). Figure 7 The impedance and phase angle are corrected to the fourth quadrant as shown in (a). As a result, the corrected parameters can be set within the application condition range of the above-mentioned equations (5) and (6). As the correction formula of this embodiment, the following equations (8) and (9) are used.

[0100] [Number 3]

[0101]

[0102] [Number 4]

[0103]

[0104] θ C : Corrected phase angle

[0105] Z C : Corrected impedance

[0106] R E : Equivalent to the resistance of wiring components

[0107] L E : Equivalent to the reactance of wiring components

[0108] In addition, the correction formulas shown in the above equations (8) and (9) are examples and are not limited thereto. When the circuit changes based on the structure of the bearing device 10, the correction formula can also be adjusted according to the change. For example, in the case where the structure of the bearing device 10 is changed except Figure 1 In the case where the bearing device includes a journal bearing, a sliding part such as a cylinder and a piston having a lubricating film between the two parts, according to the structure of the bearing device 10, Figure 4 , Figure 5 Add in series or parallel to the equivalent circuit Figure 3 Such an equivalent circuit can also be generated according to this correction formula.

[0109] [Processing Flow]

[0110] Figure 6 This process is executed by the diagnostic device 30 , and can be realized by, for example, a control device (not shown) included in the diagnostic device 30 reading a program for realizing the process of the present embodiment from a storage device (not shown) and executing the program.

[0111] In S601, the diagnostic device 30 controls to apply a load in a predetermined direction to the bearing device 10. Here, the control is performed in a manner that a radial load is applied to the rolling bearing 8 included in the bearing device 10. In addition, the control of applying a load to the bearing device 10 may also be performed by a device different from the diagnostic device 30.

[0112] In S602, diagnostic device 30 controls LCR meter 20 to apply an AC voltage of angular frequency ω to bearing device 10 using an AC power source (not shown) provided in LCR meter 20. Thus, an AC voltage of angular frequency ω is applied to bearing device 10.

[0113] In S603 , the diagnostic device 30 starts rotating the rotating shaft 7 via the motor 14 . As a result, the rolling bearing 8 also starts rotating as the rotating shaft 7 starts rotating. The motor 14 may be controlled by a device other than the diagnostic device 30 .

[0114] In S604, the diagnostic device 30 obtains the impedance Z and the phase angle θ from the LCR meter 20 as outputs corresponding to the input in S603. That is, the LCR meter 20 outputs the impedance Z and the phase angle θ to the diagnostic device 30 as the detection result of the bearing device 10 corresponding to the AC voltage V and the angular frequency ω of the AC voltage as input. The impedance Z and the phase angle θ obtained here are as follows: Figure 5 As explained above, the resistance R caused by wiring, etc. E and reactance L E ingredients.

[0115] In S605, the diagnostic device 30 applies the impedance Z and phase angle θ acquired in S604 to the above equations (8) and (9), thereby calculating the impedance Z after removing the components caused by wiring, etc. C and the phase angle θ C .

[0116] In S606, the diagnostic device 30 calculates the impedance Z calculated in S605 by C and phase angle θ C , the angular frequency ω of the AC voltage used in S602 and the specifications of the bearing device 10 to be diagnosed are applied to equations (5) and (6) to derive the oil film thickness h and the metal contact ratio α.

[0117] In S607, the diagnostic device 30 uses the oil film thickness h and the metal contact ratio α derived in S606 to diagnose the lubrication state of the bearing device 10. In addition, the diagnostic method here can, for example, pre-set thresholds for the oil film thickness h and the metal contact ratio α, and diagnose the lubrication state by comparing with the thresholds. Then, this processing flow ends.

[0118] [Comparison of diagnostic results]

[0119] Figure 8B is a diagram for explaining the diagnostic results of the method of this embodiment. Fig. 8A Corresponding, in Figure 8B In the figure, the left vertical axis represents the logarithm of the oil film thickness, the right vertical axis represents the logarithm of the metal contact ratio, and the horizontal axis represents the logarithm of the rotation speed of the rotating shaft. The horizontal axis has higher values ​​as it goes to the right. Figure 8B The dashed line represents the approximate theoretical oil film thickness calculated using the well-known Hamrock-Dowson formula.

[0120] Reference Figure 8B The higher the rotation speed, the higher the oil film thickness. In addition, the metal contact ratio decreases. Fig. 8A The result of the conventional method is different from that of the conventional method. Even when the rotation speed is lower than a certain value, the calculation will not be stopped midway and the calculation can be performed until the stop state. In addition, even when the rotation speed is lower than a certain value, the metal contact ratio will not output an unreasonable value exceeding 1.

[0121] Fig.9A It means from Fig. 8A and Figure 8B The oil film thickness values ​​are extracted and compared in a double logarithmic graph. Fig.9A In FIG. 1 , the vertical axis represents the logarithm of the oil film thickness, and the horizontal axis represents the logarithm of the rotation speed. As described above, when correction is performed by the method of this embodiment, the oil film thickness can be calculated even if the rotation speed is lower than a certain value.

[0122] Fig. 9B It means from Fig. 8A and Figure 8B The values ​​of the metal contact ratios were extracted and compared in a double logarithmic graph. Fig. 9B In FIG. 1 , the vertical axis represents the logarithm of the metal contact ratio, and the horizontal axis represents the logarithm of the rotation speed. As described above, when the correction is performed by the method of this embodiment, even if the rotation speed is lower than a certain value, an unreasonable value exceeding 1 is not output.

[0123] As described above, according to this embodiment, the lubrication state inside the rolling device can be diagnosed with higher accuracy than before. In particular, when the rotation speed of the rotating shaft is low, the oil film thickness that cannot be calculated by the conventional method can be calculated. In addition, when the rotation speed of the rotating shaft is low, it is possible to suppress the situation where an unreasonable value is calculated as in the conventional method.

[0124] <Other Implementation Methods>

[0125] For example, the embodiments of the present invention are directed to rolling devices, but are not limited thereto. For example, an equivalent circuit and correction may be made for a mechanical device consisting only of sliding elements with a lubricating film (e.g., a journal bearing, a sliding element consisting of a cylinder and a piston, etc.), and diagnosis may be performed by calculating the lubricating film thickness and the metal contact ratio.

[0126] In addition, in the present invention, a program or application for implementing the functions of one or more of the above-mentioned embodiments can be supplied to a system or device using a network or storage medium, and the program can be read and executed by one or more processors in a computer of the system or device to implement the processing.

[0127] Alternatively, the present invention may be realized by a circuit that realizes one or more functions (for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array)).

[0128] Thus, the present invention is not limited to the above-mentioned embodiments, and combining the structures of the embodiments with each other, and changing and applying them by those skilled in the art based on the description in the specification and known technologies are also the intended contents of the present invention and are included in the scope of the protection required.

[0129] As described above, the following matters are disclosed in this specification.

[0130] (1) A rolling device diagnostic method is a rolling device diagnostic method having a rolling element and a peripheral component of the rolling element, wherein:

[0131] applying an AC voltage to a circuit formed by the rolling element and the peripheral components,

[0132] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0133] The measured impedance and the measured phase angle are corrected using a correction formula based on a solution of Kirchhoff's law, wherein the correction formula is a correction formula based on a solution of Kirchhoff's law defined corresponding to the resistance and reactance of the wiring components in the circuit.

[0134] The lubricating film thickness and the metal contact ratio between the peripheral component and the rolling element are calculated based on the corrected impedance and the corrected phase angle.

[0135] According to this structure, the lubrication state inside the rolling device can be diagnosed with higher accuracy than before. In particular, when the rotation speed of the rotating shaft is low, the oil film thickness that cannot be calculated by the previous method can be calculated. In addition, when the rotation speed of the rotating shaft is low, it is possible to suppress the situation where an unreasonable value is calculated as in the previous method.

[0136] (2) The diagnostic method according to (1), wherein

[0137] The modified form is,

[0138] [Number 5]

[0139]

[0140] θC: Corrected phase angle

[0141] ZC: Corrected impedance

[0142] RE: Resistance of wiring components

[0143] LE: reactance of wiring components

[0144] θ: Measured phase angle

[0145] ω: angular frequency of AC voltage.

[0146] According to this configuration, the impedance and the phase angle can be corrected in consideration of the reactance LE and the resistance RE corresponding to the wiring components of the circuit.

[0147] (3) A rolling device diagnostic device, comprising a rolling element and a peripheral component of the rolling element, comprising:

[0148] an acquisition unit that acquires an impedance and a phase angle of a circuit formed by the rolling element and the peripheral component when an AC voltage is applied to the circuit;

[0149] a correction unit that corrects the acquired impedance and the acquired phase angle using a correction formula based on a solution of Kirchhoff's law, the correction formula being a correction formula based on a solution of Kirchhoff's law specified corresponding to resistance and reactance of wiring components in the circuit; and

[0150] A calculation unit calculates a lubricating film thickness and a metal contact ratio between the peripheral component and the rolling element based on the corrected impedance and the corrected phase angle.

[0151] According to this structure, the lubrication state inside the rolling device can be diagnosed with higher accuracy than before. In particular, when the rotation speed of the rotating shaft is low, the oil film thickness that cannot be calculated by the previous method can be calculated. In addition, when the rotation speed of the rotating shaft is low, it is possible to suppress the situation where an unreasonable value is calculated as in the previous method.

[0152] (4) A program that causes a computer to function as an acquisition unit, a correction unit, and a calculation unit,

[0153] The acquisition unit acquires the impedance and phase angle of the circuit when an AC voltage is applied to the circuit composed of the rolling element in the rolling device and the peripheral components of the rolling element.

[0154] The correction unit corrects the acquired impedance and the acquired phase angle using a correction formula based on a solution of Kirchhoff's law, wherein the correction formula is a correction formula based on a solution of Kirchhoff's law defined corresponding to resistance and reactance of wiring components in the circuit.

[0155] A calculation unit calculates a lubricating film thickness and a metal contact ratio between the peripheral component and the rolling element based on the corrected impedance and the corrected phase angle.

[0156] According to this structure, the lubrication state inside the rolling device can be diagnosed with higher accuracy than before. In particular, when the rotation speed of the rotating shaft is low, the oil film thickness that cannot be calculated by the previous method can be calculated. In addition, when the rotation speed of the rotating shaft is low, it is possible to suppress the situation where an unreasonable value is calculated as in the previous method.

[0157] Various embodiments have been described above, but the present invention is certainly not limited to these examples. As long as one skilled in the art can think of various variations or modifications within the scope described in the claims, it is obvious that these variations or modifications also belong to the technical scope of the present invention. In addition, within the scope of not departing from the gist of the invention, the various constituent elements in the above-mentioned embodiments may also be arbitrarily combined.

[0158] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2022-158718) filed on September 30, 2022, and the contents are incorporated herein by reference.

[0159] Description of Reference Numerals

[0160] 1 Outer ring

[0161] 3 Inner ring

[0162] 5 Rolling elements

[0163] 7 Rotation axis

[0164] 10 Bearing device (rolling device)

[0165] 12 Rotary connector

[0166] 14 Electric Motor

[0167] 20 LCR Meter

[0168] 30 Diagnostic Devices

Claims

1. A method for diagnosing a rolling device, It is characterized in that A method for diagnosing a rolling device having a rolling element and peripheral components of the rolling element, wherein: applying an AC voltage to a circuit formed by the rolling element and the peripheral components, measuring the impedance and phase angle of the circuit when the AC voltage is applied, The measured impedance and the measured phase angle are corrected using a correction formula based on a solution of Kirchhoff's law, wherein the correction formula is a correction formula based on a solution of Kirchhoff's law defined corresponding to the resistance and reactance of the wiring components in the circuit. The lubricating film thickness and the metal contact ratio between the peripheral component and the rolling element are calculated based on the corrected impedance and the corrected phase angle.

2. The diagnostic method according to claim 1, It is characterized in that The modified form is, [Number 1] θC: Corrected phase angle ZC: Corrected impedance RE: Resistance of wiring components LE: reactance of wiring components θ: Measured phase angle ω: angular frequency of AC voltage.

3. A diagnostic device for a rolling device, It is characterized in that A diagnostic device for a rolling device having a rolling element and a peripheral component of the rolling element, the diagnostic device comprising: an acquisition unit that acquires an impedance and a phase angle of a circuit formed by the rolling element and the peripheral component when an AC voltage is applied to the circuit; a correction unit that corrects the acquired impedance and the acquired phase angle using a correction formula based on a solution of Kirchhoff's law, wherein the correction formula is a correction formula based on a solution of Kirchhoff's law that is defined corresponding to the resistance and reactance of a wiring component in the circuit; as well as A calculation unit calculates a lubricating film thickness and a metal contact ratio between the peripheral component and the rolling element based on the corrected impedance and the corrected phase angle.

4. A procedure, It is characterized in that The program causes the computer to function as an acquisition unit, a correction unit, and a calculation unit. The acquisition unit acquires the impedance and phase angle of the circuit when an AC voltage is applied to the circuit composed of the rolling element in the rolling device and the peripheral components of the rolling element. The correction unit corrects the acquired impedance and the acquired phase angle using a correction formula based on a solution of Kirchhoff's law, wherein the correction formula is a correction formula based on a solution of Kirchhoff's law defined corresponding to resistance and reactance of wiring components in the circuit. A calculation unit calculates a lubricating film thickness and a metal contact ratio between the peripheral component and the rolling element based on the corrected impedance and the corrected phase angle.

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