Diagnostic method for scrolling device, diagnostic device, and program

Abstract

In a method for diagnosing a rolling device in which a rolling element and a peripheral member are lubricated with a lubricant, an AC voltage is applied to a circuit comprising the rolling element and the peripheral member, and the impedance and phase angle of the circuit when the AC voltage is applied are measured. On the basis of the measured impedance and phase angle, the angular frequency of the AC voltage, and the number and number of contact points of the rolling elements in the rolling device, an evaluation value indicating the lubrication state in the rolling device is derived using a prescribed calculation formula, and the lubrication state of the rolling device is diagnosed using the evaluation value.

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, but a large number of parameters are required to realize the calculation, and most of these parameters are difficult to set uniquely. On the other hand, a simpler method is required for diagnosis depending on the object of diagnosis, etc.

[0009] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for diagnosing the lubrication condition inside a rolling device by a method that is simpler 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 diagnostic method is a diagnostic method for a rolling device that lubricates rolling elements and peripheral parts with a lubricant, wherein:

[0012] applying an alternating 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] deriving an evaluation value indicating the lubrication state in the rolling device using a calculation formula defined based on the measured impedance and phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points,

[0015] The lubrication condition of the rolling device is diagnosed using the evaluation value.

[0016] In addition, another embodiment of the present invention has the following configuration. That is, a diagnostic device is a diagnostic device for a rolling device that lubricates a rolling element and peripheral parts with a lubricant, and has:

[0017] an acquisition unit configured to acquire impedance and a phase angle of a circuit formed by the rolling element and the peripheral component when an alternating voltage is applied to the circuit;

[0018] a deriving unit that derives an evaluation value indicating a lubrication state in the rolling device using a calculation formula defined based on the impedance and the phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points; and

[0019] The lubrication condition of the rolling device is diagnosed using the evaluation value.

[0020] In addition, another embodiment of the present invention has the following configuration. That is, a program that causes a computer to function as an acquisition unit, a derivation unit, and a diagnosis unit.

[0021] The acquisition unit acquires the impedance and phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to a circuit composed of a rolling element constituting a rolling device and peripheral components of the rolling element.

[0022] The deriving unit derives an evaluation value indicating a lubrication state in the rolling device using a calculation formula defined based on the impedance and the phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points.

[0023] The lubrication condition of the rolling device is diagnosed using the evaluation value.

[0024] Effects of the Invention

[0025] According to the present invention, the lubrication condition inside the rolling device can be diagnosed by a method simpler than the conventional method. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 2 This is a conceptual diagram for explaining the contact area of ​​a rolling bearing.

[0028] Figure 3 This is a diagram for explaining an equivalent circuit around a contact region of a rolling bearing.

[0029] Figure 4 This is a flowchart of a diagnostic process according to one embodiment of the present invention.

[0030] Figure 5A It is a graph for explaining the diagnosis result of the conventional method.

[0031] Figure 5B This is a graph for explaining the diagnosis results of the diagnosis method according to one embodiment of the present invention.

[0032] Figure 6 This is a diagram for explaining problems in conventional methods. DETAILED DESCRIPTION

[0033] 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 the configurations described in each embodiment are not limited to the configurations 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.

[0034] <First Embodiment>

[0035] 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 for description, 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.

[0036] 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 1In FIG. 1 , the bearing device 10 is shown to include two rolling bearings 8 , but the present invention is not limited thereto and a larger number of rolling bearings may be provided.

[0037] 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.

[0038] 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.

[0039] The motor 14 is a driving motor, and supplies 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.

[0040] 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.

[0041] 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.

[0042] Figure 2 1 is a conceptual diagram and a physical model diagram showing a rolling bearing 8 included in a bearing device 10 to be diagnosed. Figure 1 As shown, the rolling bearing 8 includes: a fixed outer ring (outer member) 1; an inner ring (inner member) 3 as a rotating ring fitted with a rotating shaft 7; and a plurality of rolling elements 5 between a raceway surface formed on the inner circumference of the outer ring 1 and a raceway surface formed on the outer circumference of the inner ring 3. In addition, an oil film (lubricating film) composed of a lubricant such as oil or grease supplied for lubrication exists between the outer ring 1 and the rolling elements 5, and between the inner ring 3 and the rolling elements 5.

[0043] 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 2 This 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. In addition, Figure 2 The variables shown are as follows.

[0044] S: Hertzian contact area (Hertzian contact area)

[0045] c: Hertz contact circle radius (=√(S / π)

[0046] α: Oil film rupture rate (metal contact ratio) (0≤α<1)

[0047] r b : The radius of the spherical piece

[0048] αS: Actual contact area (break area of ​​oil film)

[0049] h: Oil film thickness

[0050] h 1 : Oil film thickness in the Hertzian contact area

[0051] In the Hertzian contact region, the ratio of the metal contact range to the non-contact range is α:(1-α). At this time, the metal contact area is αS. 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.

[0052] And, if Figure 2 As shown in the enlarged view of the contact area between the outer ring 1 and the rolling element 5 in FIG. 1 , if the oil film is regarded as a dielectric and the outer ring 1 and the rolling element 5 are regarded as electrodes, the oil film forms a capacitor C 1 , C 2 . Capacitor C 1 It is equivalent to a capacitor formed by the oil film in the Hertz contact area, and the electrostatic capacitance is C 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 is C 2 On the other hand, the metal contact portion (the oil film break region αS) where the metals are in contact with each other has a resistance R 1 .

[0053] As a result, the derived Figure 3 Shown with Figure 2 The circuit (equivalent circuit) corresponding to the model is E 1 (Circuit formed by outer ring 1 or inner ring 3 and rolling element 5) Hertzian contact area (=S) is formed 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.

[0054] Assuming that the AC voltage applied to the equivalent circuit E1 is V and the current flowing through the equivalent circuit is I, the complex impedance Z of the entire equivalent circuit E1 is expressed by the following equation.

[0055] V=|V|exp(jωt)

[0056] I=|I|exp(j(ωt-θ))

[0057] Z=V / I=|V / I|exp(jθ)=|Z|exp(jθ)

[0058] j: imaginary number

[0059] ω: angular frequency of AC voltage

[0060] t: time

[0061] θ: Phase angle (phase difference between voltage and current)

[0062] As described later, the present invention uses this circuit to calculate not only the lubricating film thickness but also the metal contact ratio α, which is the area ratio of the metal contact portion (αS) to the entire contact region, and can diagnose the lubrication state of the rolling device.

[0063] Although the description of the details is omitted, in Patent Document 1, diagnosis is performed using the following equations (1) and (2) based on the above-mentioned model.

[0064] [Number 1]

[0065]

[0066] [Number 2]

[0067]

[0068] h: Lubricating film thickness

[0069] α: Metal contact ratio

[0070] ω: angular frequency of AC voltage

[0071] ε 1 : Dielectric constant of lubricant

[0072] S: The average area of ​​each contact ellipse when each contact area is approximated as a contact ellipse

[0073] n: The number of rolling elements (balls) in the bearing assembly

[0074] Z: The impedance of the entire circuit

[0075] θ: Phase angle

[0076] R 20 : The resistance of the metal contact part without any oil film

[0077] 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)

[0078] L: Inductance connected in series with the bearing assembly

[0079] R: resistance connected in series with the bearing assembly

[0080] As described above, the above mathematical formula requires many parameters, and most of these parameters are difficult to set uniquely. Therefore, there is also a burden that the calculation load related to the diagnosis becomes high. Therefore, in this embodiment, instead of the above formulas (1) and (2), the following formulas (3) and (4) are used to derive the evaluation value representing the lubrication state, thereby suppressing the processing load and realizing a simpler diagnostic method than before.

[0081] [Number 3]

[0082]

[0083] [Number 4]

[0084]

[0085] R: resistance of one contact point of each rolling element

[0086] C: reactance of one contact point of each rolling element

[0087] l: The number of contact points for each rolling element

[0088] k: The number of rows of rolling elements in a rolling bearing

[0089] n: the number of rolling elements in a rolling bearing

[0090] θ: Phase angle

[0091] Z: complex impedance of the circuit

[0092] ω: angular frequency of AC voltage

[0093] In this embodiment, as shown in equations (3) and (4), mathematical equations using parameters that are less in number and easier to measure than the conventional method are used. 1 / R obtained by equation (3) can replace the metal contact ratio α obtained by equation (2) of the conventional method. In addition, 1 / C obtained by equation (4) can replace the lubricating film thickness h obtained by equation (1) of the conventional method.

[0094] [Processing Flow]

[0095] Figure 4 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.

[0096] In S401, 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.

[0097] In S402 , diagnostic device 30 controls LCR meter 20 so as 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 .

[0098] In S403, the diagnostic device 30 starts the rotation of the rotating shaft 7 by the motor 14. Thus, the rolling bearing 8 also starts rotating along with the start of the rotating shaft 7. The motor 14 may be controlled by a device other than the diagnostic device 30.

[0099] In S404, the diagnostic device 30 obtains the impedance |Z| and the phase angle θ as outputs corresponding to the input in S403 from the LCR meter 20. That is, the LCR meter 20 outputs the impedance |Z| and the phase angle θ as detection results of the bearing device 10 corresponding to the AC voltage V and the angular frequency ω of the AC voltage as input to the diagnostic device 30.

[0100] In S405 , the diagnostic device 30 derives 1 / R and 1 / C by applying the impedance |Z| and phase angle θ acquired in S404 , the angular frequency ω of the AC voltage used in S402 , and the specifications of the bearing device 10 to be diagnosed to equations (3) and (4).

[0101] In S406, the diagnostic device 30 uses the evaluation values ​​of 1 / R and 1 / C derived in S405 to diagnose the lubrication state of the bearing device 10. In addition, the diagnostic method here can, for example, pre-set a threshold value for the evaluation value of 1 / R or 1 / C, and diagnose the lubrication state by comparing it with the threshold value. Then, this processing flow ends.

[0102] [Comparison of diagnostic results]

[0103] Figure 5A This is a graph for explaining the results of diagnosis using equations (1) and (2) of Patent Document 1. Figure 5A 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 5A 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 Figure 5A A straight line with the slope shown.

[0104] also, Figure 5A The test conditions are shown in the following examples.

[0105] (Test conditions)

[0106] Ball screw shaft shape:

[0107] Ball screw lead: 10mm

[0108] Surface modification

[0109] Lubricant: Grease

[0110] Grease base oil viscosity: 29mm 2 / s(at 40℃)

[0111] Grease thickener: lithium soap

[0112] Reference Figure 5A 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 problem that 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.

[0113] 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.

[0114] In the case of the conventional method, the impedance Z and the phase angle θ are both as follows at any time when the rotating shaft is stopped (i.e., the initial value) and when it is running (i.e., the measured value). Figure 6 (a) is in the fourth quadrant. Figure 6 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 6 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-mentioned equations (1) and (2). As a result, it is considered that Figure 5A That's the diagnosis.

[0115] [Diagnosis results of this embodiment]

[0116] Figure 5B is a graph for explaining the diagnostic results of the method of this embodiment. Figure 5B In the figure, the vertical axis on the left represents the logarithm of the value obtained by the method (formula (4)) according to the present embodiment, which is Figure 5A The logarithm of the oil film thickness corresponds to Figure 5B In the figure, the vertical axis on the right represents the logarithm of the value obtained based on the method (Formula (3)) according to this embodiment, which is Figure 5A The logarithm of the metal contact ratio corresponds to.

[0117] Right now, Figure 5B This is a graph obtained by calculating the simple evaluation of oil film thickness 1 / C and the simple evaluation of metal contact ratio 1 / R using equations (3) and (4). Figure 5B It can be seen that the simple evaluation of oil film thickness 1 / C and the simple evaluation of metal contact ratio 1 / R are respectively Figure 5A The oil film thickness and metal contact ratio are similar to the waveform.

[0118] In the conventional method, although the average value of the area of ​​the contact ellipse has a great influence on the conversion of the oil film thickness, it is necessary to use a parameter that is difficult to accurately estimate. In addition, since the physical property value of the dielectric constant of the lubricant is also required, a lubricant for dielectric constant measurement must be prepared separately, which makes it impossible to diagnose the lubrication state when the lubricant used is unknown.

[0119] In contrast, with respect to the present embodiment, particularly 1 / C, diagnosis can be performed even under conditions that cannot be diagnosed by the above-mentioned previous methods, such as when the specifications of the diagnosis object (the ball screw in this embodiment) and the dielectric constant of the lubricant are unknown or when the rotation speed of the rotating shaft is in a region where the rotation speed is low.

[0120] As described above, according to the present embodiment, the lubrication state inside the rolling device can be diagnosed by a method that is simpler than the conventional method. In particular, by using only parameters that are easy to measure and the specifications of the bearing device that can be set in advance, the processing load during diagnosis can be reduced. Therefore, compared with the conventional method, the calculation load can be greatly reduced.

[0121] In addition, in the conventional method, the impedance and phase angle of the rolling device in the stopped state are required to derive the metal contact ratio α, but in the method of this embodiment, such information is not required. Therefore, diagnosis can be performed simply and in real time using only the information of the operating state.

[0122] <Other Implementation Methods>

[0123] For example, the embodiments of the present invention are directed to rolling devices, but are not limited thereto. For example, an equivalent circuit may be created and corrected for a mechanical device consisting only of sliding elements having 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.

[0124] In addition, in the present invention, it is also possible to supply a program or application for implementing the functions of one or more of the above-mentioned embodiments to a system or device using a network or storage medium, and have one or more processors in a computer of the system or device read out and execute the processing of the program to implement the above-mentioned functions.

[0125] 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)).

[0126] Thus, the present invention is not limited to the above-mentioned embodiments, and combining the structures of the embodiments with each other, and making changes and applications 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.

[0127] As described above, the following matters are disclosed in this specification.

[0128] (1) A diagnostic method for a rolling device that lubricates rolling elements and peripheral components with a lubricant, wherein:

[0129] applying an alternating voltage to a circuit formed by the rolling element and the peripheral components,

[0130] measuring the impedance and phase angle of the circuit when the AC voltage is applied,

[0131] deriving an evaluation value indicating the lubrication state in the rolling device using a calculation formula defined based on the measured impedance and phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points,

[0132] The lubrication condition of the rolling device is diagnosed using the evaluation value.

[0133] According to this structure, the lubrication state inside the rolling device can be diagnosed by a method that is simpler than the previous method. In particular, by using only parameters that are easy to measure and the specifications of the bearing device that can be set in advance, the processing load during diagnosis can be reduced. Therefore, compared with the previous method, it is possible to achieve a significant labor saving in calculation.

[0134] (2) The diagnostic method according to (1) above, wherein:

[0135] The calculation formula is:

[0136] [Number 5]

[0137]

[0138] [Number 6]

[0139]

[0140] R: resistance of one contact point of each rolling element

[0141] C: reactance of one contact point of each rolling element

[0142] l: The number of contact points for each rolling element

[0143] k: The number of rows of rolling elements in a rolling bearing

[0144] n: the number of rolling elements in a rolling bearing

[0145] θ: Phase angle

[0146] Z: complex impedance of the circuit

[0147] ω: angular frequency of the AC voltage,

[0148] 1 / R corresponds to the contact ratio between the rolling element and the surrounding parts.

[0149] 1 / C corresponds to the thickness of the oil film between the rolling element and the peripheral member.

[0150] According to this configuration, evaluation values ​​corresponding to the contact ratio between the rolling element in the rolling device and the peripheral member and the oil film thickness between the rolling element in the rolling device and the peripheral member can be calculated by simple mathematical formulas.

[0151] (3) A diagnostic device for a rolling device that lubricates a rolling element and peripheral parts with a lubricant, and comprising:

[0152] an acquisition unit configured to acquire impedance and a phase angle of a circuit formed by the rolling element and the peripheral component when an alternating voltage is applied to the circuit;

[0153] a deriving unit that derives an evaluation value indicating a lubrication state in the rolling device using a calculation formula defined based on the impedance and the phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points; and

[0154] The lubrication condition of the rolling device is diagnosed using the evaluation value.

[0155] According to this structure, the lubrication state inside the rolling device can be diagnosed by a method that is simpler than the previous method. In particular, by using only parameters that are easy to measure and the specifications of the bearing device that can be set in advance, the processing load during diagnosis can be reduced. Therefore, compared with the previous method, it is possible to achieve a significant labor saving in calculation.

[0156] (4) a program that causes a computer to function as an acquisition unit, a derivation unit, and a diagnosis unit,

[0157] The acquisition unit acquires the impedance and phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to a circuit composed of a rolling element constituting a rolling device and peripheral components of the rolling element.

[0158] The deriving unit derives an evaluation value indicating a lubrication state in the rolling device using a calculation formula defined based on the impedance and the phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points.

[0159] The lubrication condition of the rolling device is diagnosed using the evaluation value.

[0160] According to this structure, the lubrication state inside the rolling device can be diagnosed by a method that is simpler than the previous method. In particular, by using only parameters that are easy to measure and the specifications of the bearing device that can be set in advance, the processing load during diagnosis can be reduced. Therefore, compared with the previous method, it is possible to achieve a significant labor saving in calculation.

[0161] 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.

[0162] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2022-158719) filed on September 30, 2022, and the contents are incorporated herein by reference.

[0163] Description of Reference Numerals

[0164] 1 Outer ring (outer part)

[0165] 3 Inner ring (inner part)

[0166] 5 Rolling elements

[0167] 6 Metal contact

[0168] 7 Rotation axis

[0169] 8 Rolling bearings

[0170] 9 Oil film (lubricating film)

[0171] 10 Bearing device (rolling device)

[0172] 12 Rotary connector

[0173] 14 Electric Motor

[0174] 20 LCR Meter

[0175] 30 Diagnostic Devices

Claims

1. A diagnostic method, characterized in that: It is a diagnostic method for rolling devices that use lubricants to lubricate rolling elements and surrounding parts, in which: applying an alternating 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, deriving an evaluation value indicating the lubrication state in the rolling device using a calculation formula defined based on the measured impedance and phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points, The lubrication condition of the rolling device is diagnosed using the evaluation value.

2. The diagnostic method according to claim 1, characterized in that The calculation formula is: [Number 1] [Number 2] R: resistance of one contact point of each rolling element C: reactance of one contact point of each rolling element l: The number of contact points for each rolling element k: The number of rows of rolling elements in a rolling bearing n: the number of rolling elements in a rolling bearing θ: Phase angle Z: complex impedance of the circuit ω: angular frequency of the AC voltage, 1 / R corresponds to the contact ratio between the rolling element and the surrounding parts. 1 / C corresponds to the thickness of the oil film between the rolling element and the peripheral member.

3. A diagnostic device, characterized in that: It is a diagnostic device for rolling devices that lubricates rolling elements and surrounding parts using lubricants, and has: an acquisition unit configured to acquire impedance and a phase angle of a circuit formed by the rolling element and the peripheral component when an alternating voltage is applied to the circuit; a deriving unit that derives an evaluation value indicating a lubrication state in the rolling device using a calculation formula defined based on the impedance and the phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points; as well as The lubrication condition of the rolling device is diagnosed using the evaluation value.

4. A program, characterized in that Make the computer function as an acquisition unit, an export unit, and a diagnosis unit, The acquisition unit acquires the impedance and phase angle of the circuit when the AC voltage is applied, obtained when an AC voltage is applied to a circuit composed of a rolling element constituting a rolling device and peripheral components of the rolling element. The deriving unit derives an evaluation value indicating a lubrication state in the rolling device using a calculation formula defined based on the impedance and the phase angle, the angular frequency of the AC voltage, the number of rolling elements in the rolling device, and the number of contact points. The lubrication condition of the rolling device is diagnosed using the evaluation value.

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