Method, device, and program for predicting grease evaporation amount

Abstract

This grease evaporation amount prediction method comprises: a calculation step for calculating a change in the amount of grease by using the lesser between a first substance amount and a second substance amount, the first substance amount being obtained by a first formula based on a vapor pressure drop caused by a base oil and a thickener included in the grease, and the second substance amount being obtained by a second formula based on a capillary force according to the thickener; and an output step for outputting the calculated change in amount as the amount of evaporation of the grease.

Description

[Technical Field]

[0001] The present invention relates to a method, an apparatus, and a program for predicting the amount of evaporation of grease. [Background technology]

[0002] Conventionally, lubricants have been used in mechanical devices such as bearing devices and sliding devices to reduce friction during operation. Grease is one example of a lubricant. Grease components can evaporate over time. As the grease evaporates, the amount and viscosity of the grease change, which can affect the operation of the mechanical device.

[0003] For example, Patent Document 1 discloses a grease composition that exhibits low torque at low temperatures and excellent oxidation stability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent No. 5319995 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a need to predict the amount of change due to evaporation of a grease in use in order to stabilize the operation of a mechanical device, predict its lifespan, etc. Furthermore, when considering evaporation conditions to design a new grease for a mechanical device, there is a need to easily predict the amount of change due to evaporation of the grease. However, Patent Document 1 does not take into account the amount of change due to evaporation of the grease or its prediction.

[0006] In view of the above problems, an object of the present invention is to provide a method that makes it possible to easily predict the amount of change in grease due to evaporation. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration: That is, a method for predicting the amount of evaporation of grease, comprising: a calculation step of calculating the amount of change of the grease using the smaller of a first amount of substance obtained by a first equation based on the vapor pressure drop caused by the base oil and thickener contained in the grease and a second amount of substance obtained by a second equation based on the capillary force caused by the thickener; an output step of outputting the calculated change amount as the evaporation amount of the grease; A prediction method having the following.

[0008] Another aspect of the present invention has the following configuration: A prediction device for grease evaporation amount, comprising: a calculation means for calculating a change in the amount of the grease using the smaller of a first amount of substance obtained by a first equation based on a vapor pressure drop caused by the base oil and thickener contained in the grease and a second amount of substance obtained by a second equation based on a capillary force caused by the thickener; an output means for outputting the calculated change amount as the evaporation amount of the grease; A prediction device having the following.

[0009] Another aspect of the present invention has the following configuration: a program comprising: On the computer, a calculation step of calculating the amount of change of the grease using the smaller of a first amount of substance obtained by a first equation based on the vapor pressure drop caused by the base oil and thickener contained in the grease and a second amount of substance obtained by a second equation based on the capillary force caused by the thickener; an output step of outputting the calculated change amount as the evaporation amount of the grease; A program to execute. [Effects of the Invention]

[0010] According to the present invention, it is possible to easily predict the amount of grease evaporation. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a conceptual diagram for explaining modeling of grease according to an embodiment of the present invention. [Figure 2] FIG. 10 is a graph illustrating an example of test results relating to evaporation of grease. [Figure 3] FIG. 10 is a graph illustrating an example of test results relating to evaporation of grease. [Figure 4] FIG. 10 is a graph illustrating another example of the results of a test relating to evaporation of grease. [Figure 5] FIG. 10 is a graph illustrating fitting when deriving parameters according to an embodiment of the present invention. [Figure 6A] FIG. 10 is a graph illustrating the effect of parameters on evaporation according to an embodiment of the present invention. [Figure 6B] FIG. 10 is a graph illustrating the effect of parameters on evaporation according to an embodiment of the present invention. [Figure 6C] FIG. 10 is a graph illustrating the effect of parameters on evaporation according to an embodiment of the present invention. [Figure 6D] FIG. 10 is a graph illustrating the effect of parameters on evaporation according to an embodiment of the present invention. [Figure 6E] FIG. 10 is a graph illustrating the effect of parameters on evaporation according to an embodiment of the present invention. [Figure 7] 1 is a block diagram showing an example of the configuration of an apparatus capable of executing a method for predicting the amount of evaporation of grease according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below is one embodiment for explaining the present invention and is not intended to be interpreted as limiting the present invention. Furthermore, not all of the configurations described in each embodiment are necessarily essential configurations for solving the problems of the present invention. Furthermore, in each drawing, the same components are assigned the same reference numerals to indicate corresponding relationships.

[0013] First Embodiment A first embodiment of the present invention will be described below. The grease used as a lubricant in this embodiment can be used in, for example, rolling bearings, rotating devices, sliding devices, etc., but is not limited to these. Furthermore, the method according to this embodiment can be used in any environment in which grease is used or designed, and its use is not particularly limited.

[0014] In the following, explanations will be given using multiple mathematical formulas. Some of the expressions for the parameters in each mathematical formula may overlap. In such cases, the meaning of the parameters will be shown in association with each mathematical formula. Furthermore, the units and granularity of the variables are merely examples and can be interpreted as appropriate.

[0015] [Grease modeling] Grease is primarily composed of a base oil and a thickener. Although other components may also be included in grease, their content is extremely small compared to the base oil and thickener, and so will not be discussed here.

[0016] FIG. 1 is a schematic diagram for explaining grease modeling. FIG. 1(a) shows an example in which a base oil 101, which is the main component of grease, is contained in an arbitrary container 100. The container 100 has a cylindrical configuration and is open at the top. Arrows 102 indicate the flow of gas around the container 100. In this case, the base oil 101 may evaporate from its liquid surface and flow out. When the base oil 101 evaporates and flows out, its liquid surface height z changes (decreases).

[0017] Fig. 1(b) shows an example in which grease 110 is contained in a container 100. As described above, the grease 110 is composed of a base oil and a thickener, and due to its composition, its evaporation behavior differs from that of the base oil shown in Fig. 1(a). More specifically, the evaporation behavior of the grease 110 can be determined by the relationship between the evaporation of the base oil due to a drop in vapor pressure at the liquid surface and the movement of the base oil due to capillary forces based on the structure of the thickener in the grease 110.

[0018] Generally, compared to a pure solvent (here, a base oil as shown in FIG. 1(a)), a solution (here, grease) in which a non-volatile solute (here, a thickener) is dissolved has a lower vapor pressure. This phenomenon is called vapor pressure depression, and this is also taken into consideration in this embodiment.

[0019] Figure 1(c) shows a curved flow path model of the grease, taking into account the structure of the thickener. t In this case, the liquid level after time t has passed (=Δt) is z t+Δt In this case, the change in the liquid level is Δz (= z t -z t+Δt )

[0020] [Evaporation test] Figure 2 is a graph showing test results related to grease evaporation under the following test conditions. In Figure 2, the horizontal axis represents time t [min], and the vertical axis represents the amount of change in grease ΔM [mg]. Plot 201 shows the actual measured value of the amount of change in grease.

[0021] (Test conditions) Grease type: PAO (polyalphaolefin)-urea grease Consistency: 250 Thickener ratio: 16.8% Initial amount: 21.49[mg] Ambient temperature: 180[℃] Atmospheric gas: N2 Gas flow rate: 100 [ml / min]

[0022] As a result of the above test, the amount of change ΔM, i.e., the amount of evaporation, stabilized at 17.88 mg. The remaining amount of grease at this point was 16.79% (= (21.49 - 17.88) / 21.49), which is approximately equal to the ratio of thickener contained in the grease. Therefore, when considering the evaporation of grease, it is sufficient to consider the evaporation behavior of the base oil in the grease. In this embodiment, focusing on the evaporation of the base oil in the grease, parameters related to evaporation are set and a calculation formula is constructed.

[0023] In the model shown in Figure 1(c), if the base oil in grease 110 evaporates and the amount of gas that moves is defined as the amount of grease 110 that moves, i.e., the amount of grease 110 (base oil) that evaporates, the amount of evaporation of grease 110 can be defined by the following equation (1).

[0024]

number

[0025] N: Amount of substance transferred per unit time and unit area [mol / s m 2 ] A: cross-sectional area of ​​particle layer [m 2 ] ρ: Density of the liquid (here, base oil) [g / m 3 ] M: Molecular weight of the liquid (here, base oil) [g / mol]

[0026] In equation (1), "0" on the left side means that no gas flows into the grease 110, and "NA" on the left side indicates that gas flows out of the grease 110. In other words, it is assumed that the grease 110 evaporates and flows out of the container 100. The right side is the amount of movement of the grease 110, which corresponds to Δz shown in FIG. 1(c).

[0027] Based on equation (1), the liquid level after t has elapsed (Δt) from a certain point t can be defined by the following equation (2).

[0028]

number

[0029] z t : Liquid level at time t [m] z t+Δt : Liquid level [m] after time t has elapsed from time t Δz: Change in z [m] M: Molecular weight [g / mol] ρ: Density of the liquid (here, base oil) [g / m 3 ] N: Amount of substance transferred per unit time and unit area [mol / s m 2 ] Δt: elapsed time [s]

[0030] Here, the parameter N included in the formulas (1) and (2) will be explained. As mentioned above, the evaporation of grease is caused by the amount of substance (hereinafter referred to as "N m ") and the amount of substance (hereinafter referred to as "N c These relationships will be described with reference to FIGS. 3 to 6E.

[0031] (Test 1) 3 is a graph showing test results relating to the evaporation of grease under the following test conditions: For convenience, the grease used in Test 1 is referred to as "Grease A." Base oil: PAO2 Thickener: Urea (C18-MDI) Thickener ratio: 16.8% Kinematic viscosity: 5.54 (below 40℃), 1.9 (below 100℃) [mm 2 / s] Consistency: 250 Temperature: 180[℃] Atmospheric gas: N2 Gas flow rate: 100 [ml / min] Container height: 5 mm

[0032] In Figures 3(a) to 3(c), the horizontal axis represents time t [min], which corresponds to each other. The vertical axis of Figure 3(a) represents the amount of change ΔM [mg]. The vertical axis of Figure 3(b) represents the concentration [-]. The vertical axis of Figure 3(c) represents the evaporation-related parameter N [mol / m 2 ·s].

[0033] In addition, in FIG. 3(a), plot 301 indicates the measured value of temperature, and plot 302 indicates the measured value of the evaporation amount of grease A. In FIG. 3(b), solid line 311 indicates the calculated value of the thickener concentration in grease A. In other words, it indicates the ratio of the thickener to the entire grease A. In FIG. 3(c), solid line 321 indicates the amount of substance (N c ) in Fig. 3(c). The solid line 322 in Fig. 3(c) shows the amount of substance (N m ) is shown. As shown by the solid lines 321 and 322, at a certain point in time after the reference time (t=0), the amount of substance (N c ) and the amount of substance (N m ) are reversed. Initially, the amount of substance (N c ) is larger, but after a certain time has passed, the amount of substance (N m The timing at which this magnitude is reversed is indicated by dashed line 323.

[0034] (Test 2) 4 is a graph showing the test results for grease evaporation under the following test conditions: The grease used in Test 2 is referred to as "Grease B" for convenience. Base oil: PAO2 Thickener: Urea (C18-MDI) Thickener ratio: 13.3% Kinematic viscosity: 5.54 (below 40℃), 1.9 (below 100℃) [mm 2 / s] Consistency: 350 Temperature: 180[℃] Atmospheric gas: N2 Gas flow rate: 100 [ml / min] Container height: 5 mm

[0035] The configuration of each axis in Figures 4(a) to 4(c) is the same as in Figure 3. In Figure 4(a), plot 401 shows the measured value of temperature, and plot 402 shows the measured value of the evaporation amount of grease B. Solid line 411 in Figure 4(b) shows the calculated value of the thickener concentration in grease B. In other words, it shows the ratio of the thickener to the entire grease. Solid line 421 in Figure 4(c) shows the mass of substance (N c ) in Fig. 4(c). The solid line 422 in Fig. 4(c) shows the amount of substance (N m ) in the case of FIG. 3. As shown by solid lines 421 and 422, at a certain point in time, the amount of substance (N c ) and the amount of substance (N m ) are reversed. Initially, the amount of substance (N c ) is larger, but after a certain time has passed, the amount of substance (N m The timing at which this magnitude is reversed is indicated by dashed line 423.

[0036] In this embodiment, a calculation formula is defined for calculating predicted values ​​corresponding to the actual measurement values ​​shown in the plot 302 in FIG. 3(a) and the plot 402 in FIG. 4(a).

[0037] Regarding N in the above formula (2), the amount of substance due to evaporation of oil taking into account the vapor pressure drop (N m) can be defined by the following formulas (3) to (6). Formulas (3) to (6) are based on Raoult's law and Fick's law. These are well known and will not be described in detail here, but for example, see "James R. Welty, Gregory L. Rorrer, David G. Foster, A. N. Bhaskarwar, "Fundamentals of Momentum, Heat and Mass Transfer Sixth Edition," Wiley, 2013" for more information. Here, the liquid base oil will also be referred to as liquid A, and the gaseous base oil will also be referred to as gas A. The gas around the container will also be referred to as gas B. Therefore, in the example of FIG. 1(b), liquid A corresponds to the base oil in the grease 110, and gas A corresponds to the vaporized base oil in the container 100. The flow of gas B is indicated by arrow 102.

[0038]

number

[0039] P: Absolute pressure [Pa] P vap : Vapor pressure of liquid A (base oil) [Pa] n oil : Amount of substance of liquid A (base oil) [mol] n thick : Amount of thickener [mol] D AB : Two-component (gas A and gas B) diffusion coefficient [m 2 / s] y B,lm : Value that changes due to the influence of convection in the atmospheric gas (gas B) [-] R: Gas constant [J / K mol] T: Temperature [K] Z: Distance from the top of the container to the liquid surface (= z2-z1) [m] z1: Liquid level [m] z2: Container height (> z1) [m] y B1 : Molar fraction of gas B at liquid level z1 [-] yB2 : Molar fraction of gas B at container height z2 [-] M A : Molecular weight of gas A [g / mol] M B : Molecular weight of gas B [g / mol] σ AB :Collision distance [nm](=(σ A +σ B ) / 2) σ A : Molecular diameter of gas A [nm] σ B : Molecular diameter of gas B [nm] Ω D :collision integral [-]

[0040] In addition, regarding N in the above formula (2), the amount of substance N in the base oil movement due to capillary force c can be defined by the following equations (7) and (8).

[0041]

number

[0042] δ: fitting parameter [m 2 ] ε: void ratio of particle layer [-] k: fitting parameter [-] k': fitting parameter [-] m: fitting parameter [-] ρ: Liquid density [g / m 3 ] T: Temperature [K] θ: Contact angle of the liquid to the particle [rad.] M: Molecular weight [g / mol] μ: Viscosity of the liquid [Pa s] z: length of particle layer [m] z a :Average length of the curved channel [m]

[0043] The constant k' is derived based on the evaporation test of the base oil as shown in Figure 2. In this embodiment, N m and N c The smaller of these is used as N in equation (2).

[0044]

number

[0045] [Fitting parameters] Here, the fitting parameters δ, k, and m included in Equation (7) and Equation (8) will be described. In this embodiment, these fitting parameters are determined by performing a centrifugal oil separation test assuming capillary force and performing fitting on the measured values. In the centrifugal oil separation test, grease is sealed in a container with a filter at the opening, and the container is rotated with the filter facing outward around the rotation axis to apply centrifugal force. At this time, oil separation occurs in the grease due to the difference between the centrifugal force and the capillary force of the grease. The test is then continued until the grease no longer separates, i.e., until the outward centrifugal force and the inward capillary force become equal. For detailed information on the centrifugal oil separation test, see, for example, "Soma, Minamoto et al., 'Measurement of Grease Permeability by Centrifugal Oil Separation Test,'" Tribology Conference 2018 Autumn Proceedings" and "Soma, Minamoto et al., 'Measurement of Grease Permeability by Centrifugal Oil Separation Test (Second Report)'" Tribology Conference 2019 Spring Proceedings."

[0046] Based on the above oil separation test, the degree of oil separation of grease can be defined by the following equations: First, the pressure gradient due to centrifugal force acting on the grease is defined by the following equation (10).

[0047]

number

[0048] ΔP e / L: Pressure gradient due to centrifugal force acting on the grease [Pa / m] L: Grease thickness in the centrifugal direction [m] ω: Rotation angular velocity [rad / s] ρ: Density of the solution [kg / m 3 ] R: Radius of rotation [m]

[0049] The pressure gradient due to the capillary force acting on the grease is defined by the following formulas (11) and (12).

[0050]

number

[0051] ΔP c / Lk: Pressure gradient due to capillary force acting on the grease [Pa / m] L: Grease thickness in the centrifugal direction [m] k: fitting parameter [-] K p :Permeability [m 2 ] T: Surface tension [kg / s 2 ] θ: Contact angle of the liquid to the particle [rad.] ε: void ratio of particle layer [-]

[0052] The pressure gradient acting on the grease is calculated using equation (13) as the difference between equation (10) and equation (11).

[0053]

number

[0054] Furthermore, based on Darcy's law, the degree of oil separation S can be defined by the following formulas (14) to (16).

[0055]

number

[0056] V: Oil separation volume [m 3 ] t: time [s] A: Cross-sectional area [m 2 ] K p :Permeability [m 2 ] ΔP / L': Pressure gradient acting on the grease [Pa / m] μ0: Base oil viscosity [Pa s] ρ: Liquid density [g / m 3 ] M g0 : Initial amount of grease [g] δ: fitting parameter [m 2 ] S: Oil separation degree [-]

[0057] Then, the measured values ​​of the oil separation test are fitted to the above equations to derive the fitting parameters δ, k, and m, which are then applied to equation (7).

[0058] Figure 5 shows an example of measurement results based on the centrifugal oil separation test described above. Figures 5(a) to 5(c) show the measurement results obtained for Grease A at a temperature of 40°C and a rotational speed of 8000 rpm. Figures 5(d) to 5(f) show the results obtained for Grease A at a temperature of 40°C and a rotational speed of 4000 rpm.

[0059] In Figures 5(a) to 5(c), the horizontal axis represents time [h] and corresponds to each other. In Figure 5(a), the vertical axis represents ΔP / L [MPa / m]. In Figure 5(b), the vertical axis represents dV / dt [m 3 / s]. In Fig. 5(c), the vertical axis represents the oil separation rate S[-].

[0060] Plot 501 shows the pressure gradient due to centrifugal force, and plot 502 shows the pressure gradient due to capillary force. Plot 511 shows the actual measured values, and the fitted values ​​are shown by solid line 512. Similarly, plot 521 shows the actual measured values, and the fitted values ​​are shown by solid line 522.

[0061] In Figures 5(d) to 5(f), the horizontal axis represents time [h] and corresponds to each other. In Figure 5(d), the vertical axis represents ΔP / L [MPa / m]. In Figure 5(e), the vertical axis represents dV / dt [m3 / s]. In Figure 5(f), the vertical axis represents oil separation rate S [-].

[0062] Plot 531 shows the pressure gradient due to centrifugal force, and plot 532 shows the pressure gradient due to capillary force. Plot 541 shows the actual measured values, and the fitted values ​​are shown by solid line 542. Similarly, plot 551 shows the actual measured values, and the fitted values ​​are shown by solid line 552.

[0063] From the above measurement results, as an example, the fitting parameters δ, k, and m for grease A are obtained as follows: δ=1.56×10 -22 k=15.5 m=7.69

[0064] When the evaporation amount for grease A is calculated using these fitting parameters, the result shown by the dashed line 303 in Figure 3(a) is obtained. This is a calculation result with higher accuracy than the actual measured value shown in plot 302.

[0065] When the fitting parameters δ, k, and m for grease B are derived using a similar method, the following values ​​are obtained, for example: δ = 3.88 × 10 -23 k=18.9 m=7.64

[0066] When the evaporation amount for grease B is calculated using these fitting parameters, the result shown by the dashed line 403 in Figure 4(a) is obtained. This is a calculation result with higher accuracy than the actual measured value shown in the plot 402.

[0067] [Parameter Influence] Here, the influence of each parameter used in the calculation formula for calculating the evaporation of grease will be explained. Figures 6A to 6E are graphs for explaining the influence of each parameter on the amount of evaporation. In Figures 6A to 6E, the horizontal axis represents time t [min], and the vertical axis represents the amount of change ΔM [mg].

[0068] The calculation conditions for measuring each parameter are as follows, and are common to all. Initial amount of grease: 10 mg Base oil: PAO2 Temperature: 180[℃] Container diameter: 5 mm Container height: 5 mm

[0069] Figure 6A is a graph illustrating the change in the amount of change ΔM when the thickener concentration 1-ε is changed. Solid lines 601, 602, 603, 604, and 605 represent concentrations of 0.60, 0.45, 0.30, 0.15, and 0.05, respectively. The results in Figure 6A show that the higher the thickener concentration, the more the evaporation of the grease (i.e., base oil) is suppressed.

[0070] 6B is a graph illustrating the change in the amount of change ΔM when the fitting parameter δ is changed. Solid lines 611, 612, 613, 614, and 615 represent the change in the amount of change ΔM when δ is 1.5×10 -30 , 1.5×10 -28 , 1.5×10 -26 , 1.5×10 -24 , 1.5×10 -22 According to the results in Figure 6B, the smaller δ is, the more the evaporation of the grease (i.e., base oil) is suppressed. Note that a small δ corresponds to a large specific area of ​​the thickener. In other words, this corresponds to the presence of more irregularities on the surface of the thickener.

[0071] FIG. 6C is a graph illustrating the change in the amount of change ΔM when the fitting parameter k is changed. Solid lines 621, 622, 623, 624, and 625 represent the cases where k is 5400, 1800, 600, 150, and 15, respectively. According to the results in FIG. 6C, the larger k is, the more the evaporation of the grease (i.e., base oil) is suppressed. A large k corresponds to a longer true flow path in the grease. In other words, this corresponds to a more complexly entangled structure of the thickener network.

[0072] Figure 6D is a graph illustrating the change in the amount of change ΔM when the fitting parameter m is changed. Here, m was changed to 0.001, 0.01, 0.1, 8, and 80, but there was no effect on the value, as shown by solid lines 641 to 645. According to the results in Figure 6D, the value of m does not affect the evaporation of grease (i.e., base oil).

[0073] Figure 6E shows the molecular weight of the thickener, M thick 6E is a graph illustrating the change in the amount of change ΔM when M is changed. Solid lines 651, 652, 653, 654, and 655 show the cases of 1600, 800, 320, 160, and 80, respectively. According to the results of FIG. 6E, M thick The larger the grease (i.e., base oil) evaporation is inhibited.

[0074] [Device configuration] 7 is a diagram showing an example of the configuration of an information processing device capable of measuring or predicting grease evaporation using the method according to this embodiment. The information processing device 700 includes a processing unit 701, a storage unit 702, an external IF (Interface) 703, a display unit 704, an operation unit 705, and a communication unit 706. The information processing device 700 may be configured as a general-purpose information processing device such as a PC (Personal Computer), or may be configured as a dedicated device.

[0075] The processing unit 701 may be configured with a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Single Processor), a dedicated circuit, etc. The storage unit 702 is configured with volatile and non-volatile storage media such as an HDD (Hard Disk Drive), a ROM (Read Only Memory), and a RAM (Random Access Memory), and is capable of inputting and outputting various information in response to instructions from the processing unit 701. The processing unit 701 can implement the above-described calculation method by reading and executing programs, applications, and various data related to the calculation method according to this embodiment from the storage unit 702.

[0076] The external IF 703 is an interface for connecting to an external device. For example, when the method according to this embodiment is used during measurement, it may be connected to a sensor for measuring information such as the temperature and atmospheric pressure in the environment surrounding the measurement target. The display unit 704 is a unit for outputting results obtained by the method according to this embodiment, and outputs the results to the user in response to instructions from the processing unit 701. The operation unit 705 is a unit for receiving input of parameters and various instructions from the user. The communication unit 706 is a network interface for communicating with an external device, and may be configured to output results obtained by the method according to this embodiment to the outside, for example.

[0077] In the information processing device described above, by setting the above-mentioned formula and fitting parameters obtained by fitting, and receiving input of the elapsed time from the initial time (Δt) and the initial grease height (z) from the measurement object, it is possible to predict the amount of grease evaporation over time.

[0078] As described above, the configuration of this embodiment makes it possible to easily predict the amount of evaporation of grease, particularly by taking into account the effects of vapor pressure drop and capillary force depending on the composition of the grease.

[0079] <Other embodiments> In the present invention, a program or application for realizing the functions of one or more of the above-described embodiments can be supplied to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device can read and execute the program.

[0080] Alternatively, it 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)).

[0081] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0082] As described above, the present specification discloses the following: (1) A method for predicting the amount of evaporation of grease, comprising: a calculation step of calculating the amount of change of the grease using the smaller of a first amount of substance obtained by a first equation based on the vapor pressure drop caused by the base oil and thickener contained in the grease and a second amount of substance obtained by a second equation based on the capillary force caused by the thickener; an output step of outputting the calculated change amount as the evaporation amount of the grease; A prediction method having the following. This configuration makes it possible to easily predict the amount of evaporation of the grease, particularly by taking into account the effects of vapor pressure drop and capillary force depending on the composition of the grease.

[0083] (2) The prediction method according to (1), wherein the first equation is defined by the following equation:

[0084]

number

[0085] N m : Amount of first substance [mol / s m 2 ] P: Absolute pressure [Pa] P vap : Vapor pressure of base oil [Pa] n oil : Amount of base oil [mol] n thick : Amount of thickener [mol] D AB : Two-component (vaporized base oil and atmospheric gas) diffusion coefficient [m 2 / s] y B,lm : Value that changes due to the influence of convection in the atmospheric gas [-] R: Gas constant [J / K mol] T: Temperature [K] Z: Distance from the top of the container to the liquid surface (= z2-z1) [m] z1: Liquid level [m] z2: Container height (> z1) [m] y B1 : Molar fraction of gas B at liquid level z1 [-] y B2 : Molar fraction of gas B at container height z2 [-] M A : Molecular weight of vaporized base oil [g / mol] M B : Molecular weight of atmospheric gas [g / mol] σ AB :Collision distance [nm](=(σ A +σ B ) / 2) σ A : Molecular diameter of vaporized base oil [nm] σ B : Molecular diameter of atmospheric gas [nm] Ω D :collision integral [-]

[0086] According to this configuration, it is possible to predict the amount of evaporation taking into consideration the effect of a vapor pressure drop depending on the composition of the grease.

[0087] (3) The prediction method according to (1) or (2), wherein the second equation is defined by the following equation:

[0088]

number

[0089] N c : Amount of second substance [mol / s m 2 ] δ: fitting parameter [m 2 ] ε: void ratio of particle layer [-] k: fitting parameter [-] k': fitting parameter [-] m: fitting parameter [-] ρ: Density of base oil [g / m 3 ] T: Temperature [K] θ: Contact angle of base oil particles [rad.] M: Molecular weight [g / mol] μ: Viscosity of base oil [Pa·s] z: length of particle layer [m] z a :Average length of the curved channel [m]

[0090] According to this configuration, it is possible to predict the amount of evaporation taking into consideration the influence of capillary force depending on the composition of the grease.

[0091] The prediction method according to any one of (1) to (3), wherein in the calculation step, the amount of change in the grease is calculated using a third formula defined by the following formula:

[0092]

number

[0093] z t : Liquid level at time t [m] z t+Δt : Liquid level [m] after time t has elapsed from time t Δz: Change in z [m] M: Molecular weight [g / mol] ρ: Liquid density [g / m 3 ] N: Amount of substance transferred per unit time and unit area [mol / s m 2 ] Δt: elapsed time [s] N m : Amount of first substance [mol / s m 2 ] N c : Amount of second substance [mol / s m 2 ]

[0094] According to this configuration, it is possible to predict the amount of evaporation taking into consideration the effects of vapor pressure drop and capillary force depending on the composition of the grease.

[0095] (5) A device for predicting the amount of evaporation of grease, comprising: a calculation means for calculating a change in the amount of the grease using the smaller of a first amount of substance obtained by a first equation based on a vapor pressure drop caused by the base oil and thickener contained in the grease and a second amount of substance obtained by a second equation based on a capillary force caused by the thickener; an output means for outputting the calculated change amount as the evaporation amount of the grease; A prediction device having the following. This configuration makes it possible to easily predict the amount of evaporation of the grease, particularly by taking into account the effects of vapor pressure drop and capillary force depending on the composition of the grease.

[0096] (6) To the computer: a calculation step of calculating the amount of change of the grease using the smaller of a first amount of substance obtained by a first equation based on the vapor pressure drop caused by the base oil and thickener contained in the grease and a second amount of substance obtained by a second equation based on the capillary force caused by the thickener; an output step of outputting the calculated change amount as the evaporation amount of the grease; A program to execute. This configuration makes it possible to easily predict the amount of evaporation of the grease, particularly by taking into account the effects of vapor pressure drop and capillary force depending on the composition of the grease.

[0097] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention. Furthermore, the components of the above-described embodiments may be combined in any manner without departing from the spirit of the invention.

[0098] This application is based on a Japanese patent application (Patent Application No. 2023-088048) filed on May 29, 2023, the contents of which are incorporated herein by reference. [Industrial Applicability]

[0099] The present invention has the effect of making it possible to easily predict the amount of evaporation of grease, and can be used in, for example, rolling bearings, rotating devices, sliding devices, etc., but is not limited to these, and can be used in any environment in which grease is used or designed. [Explanation of symbols]

[0100] 700...Information processing device 701... Processing section 702...Storage section 703...External IF 704...Display section 705...Operation unit 706…Communications Department

Claims

1. A method for predicting the amount of evaporation of grease, comprising: a calculation step of calculating a change in the amount of the grease using the smaller of a first amount of substance obtained by a first equation based on a vapor pressure drop caused by the base oil and thickener contained in the grease and a second amount of substance obtained by a second equation based on a capillary force caused by the thickener; an output step of outputting the calculated change amount as the evaporation amount of the grease; A prediction method having the following.

2. The method of claim 1 , wherein the first equation is defined by the following equation: [Equation 1] N ｍ : first amount of substance [mol / s m ２ ] P: Absolute pressure [Pa] P ｖａｐ : Vapor pressure of base oil [Pa] n ｏｉｌ : Amount of substance of base oil [mol] n ｔｈｉｃｋ : Amount of substance of thickener [mol] D ＡＢ : Two-component (vaporized base oil and atmospheric gas) diffusion coefficient [m ２ / s] y Ｂ，ｌｍ : Value that changes due to the influence of convection in the atmospheric gas [-] R: gas constant [J / K mol] T: Temperature [K] Z: Distance from the top of the container to the liquid surface (= z ２ -z １ ) [m] z １ : Liquid level height [m] z ２ : Container height (> z １ ) [m] y Ｂ１ : Liquid level height z １ Molar fraction of gas B at position [-] y Ｂ２ : container height z ２ Molar fraction of gas B in [-] M Ａ : Molecular weight of vaporized base oil [g / mol] M Ｂ : Molecular weight of atmospheric gas [g / mol] σ ＡＢ : Conflict distance [nm] (=(σ Ａ +σ Ｂ ) / 2) σ Ａ : Molecular diameter of vaporized base oil [nm] σ Ｂ : Molecular diameter of atmospheric gas [nm] Ω Ｄ Conflict integral [-]

3. The method of claim 1 , wherein the second equation is defined by the following equation: [Equation 2] N ｃ : second amount of substance [mol / s m ２ ] δ: fitting parameter [m ２ ] ε: void ratio of particle layer [-] k: fitting parameter [-] k': fitting parameter [-] m: fitting parameter [-] ρ: Density of base oil [g / m ３ ] T: Temperature [K] θ: Contact angle of the base oil particle [rad.] M: molecular weight [g / mol] μ: Viscosity of base oil [Pa s] z: length of particle layer [m] z ａ : Average length of curved flow path [m]

4. The prediction method according to claim 1 , wherein the calculation step calculates the amount of change in the grease by using a third equation defined by the following equation: [Equation 3] z ｔ : Liquid level at time t [m] z ｔ＋Δｔ : Liquid level height after time t has elapsed from time t [m] Δz: change in z [m] M: molecular weight [g / mol] ρ: density of the liquid [g / m ３ ] N: Amount of substance transferred by the liquid per unit time and unit area [mol / s m ２ ] Δt: elapsed time [s] N ｍ : first amount of substance [mol / s m ２ ] N ｃ : second amount of substance [mol / s m ２ ]

5. A device for predicting the amount of evaporation of grease, a calculation means for calculating a change in the amount of the grease using the smaller of a first amount of substance obtained by a first equation based on a vapor pressure drop caused by the base oil and thickener contained in the grease and a second amount of substance obtained by a second equation based on a capillary force caused by the thickener; an output means for outputting the calculated change amount as the evaporation amount of the grease; A prediction device having the following.

6. On the computer, a calculation step of calculating a change in the amount of the grease using the smaller of a first amount of substance obtained by a first equation based on a vapor pressure drop caused by a base oil and a thickener contained in the grease and a second amount of substance obtained by a second equation based on a capillary force caused by the thickener; an output step of outputting the calculated change amount as the evaporation amount of the grease; A program to execute.

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