Rolling bearing, bearing device and motor

Abstract

To provide a rolling bearing having low torque and a long service life even when rotated at a high speed.SOLUTION: A rolling bearing comprises an outer ring, an inner ring arranged on an inner peripheral side of the outer ring, a plurality of rolling bodies provided between a raceway groove of the outer ring and a raceway groove of the inner ring, a holder having pockets for rotatably holding the rolling bodies, and grease arranged in a bearing space surrounded by the outer ring and the inner ring. The grease is charged on the inner peripheral surface side of the outer ring on both one side in an axial direction and the other side in the axial direction across the plurality of rolling bodies in the bearing space. The grease has a loss tangent value of 0.1 or more and 0.2 or less when measured at a temperature of 25°C, a frequency of 1 Hz, and a strain of 0.07 (fixation)%, and contains synthetic hydrocarbon oil, urea-based thickener and phosphorus-based friction modifier. Further, the raceway groove of the outer ring and the raceway groove of the inner ring are coated with antirust oil, and the antirust oil contains synthetic hydrocarbon oil and phosphorus-based friction modifier.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a rolling bearing, a bearing device, and a motor. [Background technology]

[0002] In rolling bearings such as ball bearings, grease is normally held in the bearing space between the inner and outer rings to improve the lubrication performance of the inner and outer rings, rolling elements, and cage. Patent Document 1 describes a bearing in which grease is placed on the opening side of a crown cage so as not to come into contact with the raceway surfaces of the inner and outer rings.

[0003] Incidentally, a bearing cartridge in which a sleeve and a shaft are bonded to multiple bearings is advantageous for high-speed rotation applications because the multiple bearings have high concentricity (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-129872 A [Patent Document 2] JP 2010-196707 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a bearing in a bearing cartridge is used in which grease is disposed on the opening side of the crown cage, as in Patent Document 1, there is a problem that the torque is high and the life is short when rotated at high speed.

[0006] The present invention has been made in view of the above, and an object of the present invention is to provide a rolling bearing which has low torque and a long life even when rotated at high speed. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, a rolling bearing according to one embodiment of the present invention comprises an outer ring, an inner ring arranged on the inner peripheral side of the outer ring, a plurality of rolling elements provided between a raceway groove of the outer ring and a raceway groove of the inner ring, a cage having pockets that rotatably hold the rolling elements, and grease arranged in a bearing space surrounded by the outer ring and the inner ring, the grease being filled on the inner peripheral surface side of the outer ring on both one axial side and the other axial side of the bearing space with the plurality of rolling elements between them, the grease having a loss tangent of 0.1 or more and 0.2 or less when measured under conditions of a temperature of 25°C, a frequency of 1 Hz, and a strain amount of 0.07 (fixed)%, and containing a synthetic hydrocarbon oil, a urea-based thickener, and a phosphorus-based friction modifier, and further comprising a rust-preventive oil adhered to the raceway groove of the outer ring and the raceway groove of the inner ring, the rust-preventive oil containing a synthetic hydrocarbon oil and a phosphorus-based friction modifier. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a rolling bearing that has low torque and a long life even when rotated at high speed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a partially cutaway plan view of the non-opening side of a crown type cage in a rolling bearing according to an embodiment. [Diagram 2] FIG. 2 is a partially cutaway plan view of the opening side of a crown type cage in the rolling bearing according to the embodiment. [Diagram 3] FIG. 3 is a vertical cross-sectional view of FIG. [Figure 4] FIG. 4 is a partial plan view of the non-opening side of a crown type cage in a rolling bearing according to a modified example. [Diagram 5] FIG. 5 is a cross-sectional view of the motor according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0011] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0012] <Rolling bearings> FIG. 1 is a partially cutaway plan view of the non-opening side of a crown type cage in a rolling bearing according to an embodiment. FIG. 2 is a partially cutaway plan view of the opening side of a crown type cage in a rolling bearing according to an embodiment. FIG. 3 is a vertical cross-sectional view of FIG. 1. The rolling bearing 1 has an outer ring 2, an inner ring 3 arranged on the inner circumferential side of the outer ring 2, a plurality of rolling elements 4, and a cage 5, and grease 6 is arranged therein. The plurality of rolling elements 4 are provided between a raceway groove 21 of the outer ring 2 and a raceway groove 31 of the inner ring 3. The cage 5 has a pocket that rotatably holds the rolling elements 4. The grease 6 is arranged in a bearing space S surrounded by the outer ring 2 and the inner ring 3. The grease 6 is filled on the inner circumferential surface side of the outer ring 2 on both sides of the bearing space S in the axial direction and on the other side of the axial direction, sandwiching the plurality of rolling elements 4.

[0013] Furthermore, the rolling bearing 1 includes one shield plate 71 that closes the gap between the outer ring 2 and the inner ring 3 at one axial end side, and the other shield plate 72 that closes the gap between the outer ring 2 and the inner ring 3 at the other axial end side. Therefore, the bearing space S is surrounded by the outer ring 2, the inner ring 3, the one shield plate 71, and the other shield plate 72. Furthermore, the grease 6 is disposed in the bearing space S at one corner X1 formed by the inner circumferential surface of the outer ring 2 and the one shield plate 71, and at the other corner X2 formed by the inner circumferential surface of the outer ring 2 and the other shield plate 72.

[0014] Specifically, the outer ring 2 is made of a metal material such as steel. The raceway groove 21 is formed on the inner peripheral surface of the outer ring 2 so as to extend in the circumferential direction. The surface of this raceway groove 21 constitutes the raceway surface. The inner ring 3 is made of a metal material such as steel. The raceway groove 31 is formed on the outer peripheral surface of the inner ring 3 so as to extend in the circumferential direction. The surface of this raceway groove 31 constitutes the raceway surface.

[0015] The rolling elements 4 are made of a metal material such as steel. The raceway grooves 21 and 31 form a raceway, and the rolling elements 4 roll on the raceway while contacting the raceway surfaces of the raceway grooves 21 and 31. Note that, although the number of rolling elements 4 is eight in Figs. 1 and 2, the number of rolling elements 4 is not particularly limited.

[0016] The cage 5 is a crown-type cage made of synthetic resin or metal, and arranges the multiple rolling elements 4 at equal intervals within the raceway. The cage 5 has multiple openings 51 (pockets) for accommodating the multiple rolling elements 4 at one axial end side, and non-openings 52 at the other axial end side.

[0017] The first and second shield plates 71, 72 are substantially annular plate members made of galvanized steel, stainless steel, rubber, or the like. The first and second shield plates 71, 72 are attached to the outer ring 2 at their respective outer peripheries. Specifically, mounting grooves 8 are formed in the inner peripheral edges of the outer ring 2, and the first and second shield plates 71, 72 are received in the mounting grooves 8 at their outer peripheries and fixed by retaining rings 9. Meanwhile, the first and second shield plates 71, 72 have their inner peripheries extending to the immediate vicinity of the inner ring 3. As a result, the first and second shield plates 71, 72 cover the gap between the outer ring 2 and the inner ring 3, protecting the rolling elements 4 and the grease 7. In addition, since the first and second shield plates 71, 72 are spaced apart from the inner ring 3 in the rolling bearing 1, when the inner ring 3 rotates relative to the outer ring 2, the vibration of the inner ring 3 is unlikely to be transmitted to the first and second shield plates 71, 72. As a result, the shape and position of the grease 6 are more easily maintained.

[0018] As described above, the bearing space S is a space surrounded by the outer ring 2, the inner ring 3, one shield plate 71, and the other shield plate 72. Specifically, the bearing space S is a space surrounded by the outer ring 2, the inner ring 3, a surface obtained by extending the end of the inner periphery of one shield plate 71 to the inner ring 3, and a surface obtained by extending the end of the inner periphery of the other shield plate 72 to the inner ring 3.

[0019] More specifically, the grease 6 is filled in corners X1 (the opening side of the cage 5) and corners X2 (the non-opening side of the cage 5) so as to be biased toward the inner peripheral surface of the outer ring 2 and to form a continuous annular shape along the circumferential direction so as not to come into contact with the outer peripheral surface of the inner ring 3. In addition, the grease 6 is held away from the raceway groove 21 of the outer ring 2 and the raceway groove 31 of the inner ring 3.

[0020] In the rolling bearing 1, since the grease 6 is arranged at the corners X1 and X2 as described above, when the rolling element 4 rolls, the rolling element 4 comes into slight contact with the grease 6 and removes a portion of the grease 6. Furthermore, the removed grease 6 is also supplied in an appropriate amount to the contact surfaces between the rolling element 4 and the raceway groove 21 of the outer ring 2, the raceway groove 31 of the cage 5 and the inner ring 3. This provides good lubrication to these contact surfaces, and minimizes the stirring of the grease 6 caused by the rotation of the outer ring 2 and the inner ring 3, thereby reducing the torque. Therefore, the life of the rolling bearing is extended. Here, since the grease 6 is arranged not only at the corners X2 but also at the corners X1 as described above, the time until the torque is stabilized can be shortened.

[0021] In addition, when the rolling bearing rotates, centrifugal force is usually generated in the cage as the rolling bearing rotates. In the case of a crown-type cage, it not only spreads in the circumferential direction of rotation, but also deforms and moves in the direction of the non-opening side, and may come into contact with the shield plate. This contact may cause wear, shorten the life of the rolling bearing, and generate noise. In particular, in small-diameter ball bearings with an outer diameter of 22 mm or less, and especially in bearings with an outer diameter of 13 mm or less, such problems become more pronounced at high speed rotation (for example, 150,000 rpm or more). In contrast, in the rolling bearing 1, the grease 6 is arranged at the corner portion X2 as described above, so that wear between the cage 5 and the other shield plate 72 is suppressed. Therefore, even at high speed rotation, the life of the rolling bearing is extended and noise generation is suppressed.

[0022] As described above, in the rolling bearing 1, since the grease 6 is disposed at the corners X1 and X2 as described above, the life can be extended even during high speed rotation (for example, 150,000 rpm or more).

[0023] Furthermore, a sufficient amount of grease 6 can be retained and good lubricating performance can be maintained for a longer period of time if it is filled from the inner circumferential surface of the outer ring 2 to near the outer circumferential surface of the inner ring 3. Furthermore, because the grease 6 is filled in a continuous annular shape, filling is simple and can also be easily automated.

[0024] Furthermore, the loss tangent tanδ of the grease 6 is 0.1 to 0.2 when measured under predetermined conditions, i.e., a temperature of 25°C, a frequency of 1 Hz, and a strain of 0.07% (fixed). This makes it possible to more appropriately achieve both a reduction in rotational torque and the maintenance of good lubricating performance over a long period of time.

[0025] Specifically, when the loss tangent tanδ is 0.2 or less, the amount of grease 6 removed when the rolling element 4 slightly contacts the grease 6 becomes appropriate. However, when the loss tangent tanδ is greater than 0.2, the viscosity of the grease increases and the grease is dragged by the ball, so that the amount of grease removed per contact of the rolling element increases, and there is a concern of oversupply. As a result, the rotational torque increases and the grease is quickly reduced, so that the period during which good lubrication performance can be maintained is shortened. On the other hand, when the loss tangent tanδ is less than 0.1, the elasticity of the grease increases, so that it becomes difficult to fill the bearing space between the outer ring and the inner ring with the appropriate amount and shape of grease. In addition, when the loss tangent tanδ is within the above range, it becomes easier to maintain the arrangement of the grease 6 described above. For the above reasons, the loss tangent tanδ of the grease 6 is preferably a value of 0.1 or more and 0.2 or less.

[0026] Furthermore, the grease 6 has a loss tangent tan δ within the above range, and contains a synthetic hydrocarbon oil, a urea-based thickener, and a phosphorus-based friction modifier (phosphorus-containing friction modifier).

[0027] Synthetic hydrocarbon oils are preferably used as base oils from the viewpoint of reducing torque and extending the life of rolling bearings. Examples of synthetic hydrocarbon oils include normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, 1-decene ethylene oligomer, and other polyalphaolefins. Synthetic hydrocarbon oils can be used alone or in combination. The content of synthetic hydrocarbon oil in 100 wt% of grease is, for example, in the range of 70 wt% to 90 wt%, but is not particularly limited as long as the above-mentioned range of loss tangent tanδ can be realized.

[0028] The urea-based thickener is preferably used from the viewpoints of heat resistance and noise reduction. The content of the urea-based thickener in 100 wt% of the grease is, for example, in the range of 10 wt% to 30 wt%, but is not particularly limited as long as the above-mentioned range of the loss tangent tan δ can be realized.

[0029] As the urea-based thickener, a urea compound such as a diurea compound, a triurea compound, or a polyurea compound can be used. The urea compounds can be used alone or in combination. In particular, from the viewpoints of heat resistance and noise reduction, a diurea compound is preferred. The diurea compound can be represented by the following formula (1). R1-NHCONH-R2-NHCONH-R3(1) Here, R1 and R3 may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group, and there is no particular limitation on the number of carbon atoms. R2 is an aromatic hydrocarbon group, which is substituted with one or two phenyl groups. The raw materials used in synthesizing these are amine compounds and isocyanate compounds. As amine compounds, aliphatic amines such as hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, stearylamine, and oleylamine, and alicyclic amines such as hexylamine, as well as aromatic amines such as aniline, p-toluidine, and ethoxyphenylamine are used. As isocyanate compounds, phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, and hexane diisocyanate are used. It is preferable to use an aliphatic-aromatic diurea compound (aliphatic aromatic diurea compound) synthesized by using an aliphatic amine and an aromatic amine as the amine raw material and synthesizing it with an aromatic isocyanate. In other words, it is preferable that in the diurea compound, R1 and R3 are aliphatic hydrocarbon groups or aromatic hydrocarbon groups, and R2 is an aromatic hydrocarbon group.

[0030] Phosphorus-based friction modifiers are preferably used from the viewpoint of extending the life of rolling bearings. Examples of phosphorus-based friction modifiers include phosphate esters such as tricresyl phosphate (TCP) and triphenyl phosphorothioate (TPPT), phosphites, and thiophosphates such as zinc dialkyldithiophosphate (ZnDTP). Phosphorus-based friction modifiers can be used alone or in combination. The content of phosphorus-based friction modifiers in 100 wt% of grease is, for example, in the range of 0.5 wt% to 3.0 wt%, but is not particularly limited as long as the above-mentioned range of loss tangent tanδ can be realized.

[0031] Furthermore, the grease 6 may contain other additives such as a dispersant, an antioxidant, a metal deactivator, a rust inhibitor, an oiliness agent, and a viscosity index improver, as required.

[0032] Furthermore, in the rolling bearing 1, anti-rust oil is attached to the raceway groove 21 of the outer ring 2 and the raceway groove 31 of the inner ring 3. This anti-rust oil contains a synthetic hydrocarbon oil and a phosphorus-based friction modifier. In the case of a rolling bearing in which grease is arranged as described above, since grease is not arranged in the raceway groove, there is a concern that the lubricity is poor especially at the beginning of rotation, wear occurs on the raceway surface, balls and cage, and the rolling bearing will have a short life. In contrast, since the rolling bearing 1 has a specific anti-rust oil attached to the above-mentioned parts, the lubricity is improved at the beginning of rotation even at high speed rotation, and the torque of the rolling bearing can be reduced and the life of the rolling bearing can be extended. Note that the anti-rust oil only needs to be attached to at least the raceway grooves 21 and 31, and may also be attached to other parts of the rolling bearing 1, such as the inner and outer circumferential surfaces of the outer ring 2 and the inner ring 3 other than the raceway grooves 21 and 31, and the cage 5.

[0033] As with the above-mentioned grease 6, synthetic hydrocarbon oil is preferably used as the base oil for the rust preventive oil. The details of the synthetic hydrocarbon oil are also the same as those for grease 6. As for the rust preventive oil, synthetic hydrocarbon oil is used as the base oil rather than an ester-based base oil, because it has lower compatibility with phosphorus-based friction modifiers, which makes it easier for the phosphorus-based friction modifier to be adsorbed to the metal surface, improving lubricity. From the viewpoint of improving lubricity at the beginning of rotation, the synthetic hydrocarbon oil should have a kinetic viscosity of 30 mm at 40°C. 2 The content of the synthetic hydrocarbon oil in 100 wt % of the rust preventive oil is preferably, for example, in the range of 80 wt % to 98 wt %.

[0034] The phosphorus-based friction modifier is preferably used from the viewpoint of improving lubricity. Details of the phosphorus-based friction modifier are the same as those of Grease 6. The content of the phosphorus-based friction modifier in 100 wt% of the rust preventive oil is preferably in the range of 0.5 wt% to 3.0 wt%, for example.

[0035] The rust-preventive oil preferably contains a sulfur-based rust-preventive additive. The sulfur-based rust-preventive additive may be used alone or in combination. When using a sulfur-based rust-preventive additive, the content of the sulfur-based rust-preventive additive in 100 wt% of the rust-preventive oil is preferably in the range of, for example, 0.5 wt% to 3.0 wt%. Note that the rust-preventive oil usually contains other additives in addition to the friction modifier and the sulfur-based rust-preventive additive.

[0036] Furthermore, in the rolling bearing 1, it is preferable that the amount of grease 6 arranged at one corner X1 on the opening 51 side is the same as the amount of grease 6 arranged at the other corner X2 on the non-opening 52 side. Alternatively, it is preferable that the amount of grease 6 arranged at one corner X1 on the opening 51 side is less than the amount of grease 6 arranged at the other corner X2 on the non-opening 52 side. This makes it possible to achieve further torque reduction and longer life in the rolling bearing even during high-speed rotation.

[0037] In addition, when the spatial volume of the bearing space S in the rolling bearing 1 is taken as 100%, the total volume of the grease 6 disposed in one corner X1 and the other corner X2 is preferably in the range of 5% to 20%, and more preferably 7.5% to 12.5%. When the total volume of the grease (the total volume of the grease 6 disposed in one corner X1 and the other corner X2) is taken as 100%, the volume of the grease 6 disposed in one corner X1 is preferably in the range of 20% to 60%, and the volume of the grease 6 disposed in the other corner X2 is preferably in the range of 40% to 80%. This makes it possible to achieve further torque reduction and longer life in the rolling bearing even during high-speed rotation.

[0038] The rolling bearing 1 can be produced, for example, as follows. First, the outer ring 2, inner ring 3, rolling elements 4 and cage 5 are assembled. The assembled outer ring 2, inner ring 3, rolling elements 4 and cage 5 are immersed in rust-preventive oil. Next, grease 6 is filled from the opening 51 side and the non-opening 52 side. After filling with grease 6, one and the other shield plates 71, 72 are attached to both ends of the outer ring 2. In this way, the rolling bearing 1 is obtained.

[0039] Here, the operation of the rolling bearing 1 will be described in summary for the case where the outer ring 2 is fixed and the inner ring 3 is rotated. When the rolling bearing 1 starts operating, the rolling element 4 rolls on the raceway formed by the raceway grooves 21 and 31. At the start of operation, the grease 6 is held away from the raceway grooves 21 and 31. However, the rust-preventive oil adhering to the raceway grooves 21 and 31 provides good lubrication between the rolling element 4 and the raceway grooves 21 and 31. As the rolling element 4 continues to roll, it comes into slight contact with the grease 6 and removes a portion of the grease 6. Furthermore, the removed grease 6 is also supplied in an appropriate amount to the contact surfaces between the rolling element 4 and the raceway grooves 21 of the outer ring 2, the cage 5, and the raceway grooves 31 of the inner ring 3. As a result, these contact surfaces continue to be well lubricated. In addition, the grease 6 arranged at the corner portion X2 also suppresses wear between the cage 5 and the other shield plate 72. In this way, reduced torque and increased life of the rolling bearings can be achieved.

[0040] The rolling bearing 1 may also be used such that the inner ring 3 is fixed and the outer ring 2 is rotated. In this case, when centrifugal force acts on the grease 6 due to the rotation of the outer ring 2, the grease 6 tends to move towards the outer ring 2, without coming into contact with the inner ring 3, which has the advantage of suppressing an increase in rotational torque.

[0041] Conventionally, in rolling bearings, grease is generally applied on grease pockets or raceway surfaces, which causes problems such as high initial torque and instability, which makes it difficult to achieve high-speed rotation. In addition, since a large amount of grease is applied, the grease becomes an obstacle to rotation. This causes vibrations, which in turn causes wear on the raceway surfaces, balls, and cages, resulting in a short lifespan of the rolling bearing. In contrast, as described above, in the rolling bearing according to the embodiment, specific grease and rust-preventive oil are disposed in specific locations, so that even during high-speed rotation, the lubrication at the beginning of rotation is improved, and the torque of the rolling bearing can be reduced and its lifespan extended.

[0042] <Modification> FIG. 4 is a partial plan view of the non-opening side of the crown type cage in the rolling bearing according to the modified example. In the rolling bearing according to the embodiment, the grease 6 is arranged in the corner portion X2 so as to be a continuous annular shape along the circumferential direction of the outer ring 2. However, as in the rolling bearing 1A shown in FIG. 4, a plurality of greases 6A may be arranged in the corner portion X2 so as to be spaced apart from each other along the circumferential direction of the outer ring 2. In this case, the amount of grease filled into the bearing space can be easily controlled by adjusting the filling interval of the grease and the filling length in the radial direction. Also, in the corner portion X1, a plurality of greases 6A may be arranged in the outer ring 2 so as to be spaced apart from each other along the circumferential direction. Note that the plurality of greases 6A are not limited to being spaced apart, and may be arranged so as to be partially in contact with each other.

[0043] In addition, in the rolling bearing, it is sufficient that the grease is filled on the inner peripheral surface side of the outer ring on both axial sides of the rolling elements in the bearing space. In other words, the one and the other shield plates 71, 72 do not have to be provided. In addition, the cage is not limited to a crown cage, and may be an annular cage.

[0044] In any of the modified examples, similarly to the rolling bearing according to the embodiment, the lubricity improves even during high speed rotation, and it is possible to achieve reduced torque and a longer life for the rolling bearing.

[0045] <Bearing device and motor> 5 is a cross-sectional view of a motor according to an embodiment. The motor 100 has a shaft 101, a rotor core 102 attached to the shaft 101, and a bearing device 103. The bearing device 103 has a pair of the above-mentioned rolling bearings 1, a spring 104 that applies a preload to each of the rolling bearings 1, and a sleeve 105 that surrounds the pair of rolling bearings 1. The outer peripheral surface of the outer ring 2 of the pair of rolling bearings 1 is fixed to the sleeve 105. Also, the inner peripheral surface of the inner ring 3 of the pair of rolling bearings 1 is fixed to the shaft 101. Since such a motor 100 has the above-mentioned rolling bearings 1, it can achieve a long life even when used for high-speed rotation applications.

[0046] The motor 100 can further include an impeller 106 attached thereto to form a rotor assembly. This rotor assembly is suitable for use in high-speed rotation applications such as hair dryers, electric fans, humidifier fans, vacuum cleaners, and the like.

[0047] [Example] <Grease and rust preventative oil> In the examples and comparative examples, the following greases A to E were prepared, and an evaluation test of their dynamic viscoelasticity was carried out to determine the loss tangent. Grease A: Loss tangent tanδ=0.15 Base oil is PAO8 (poly alpha olefin, kinematic viscosity 8mm at 100℃) 2 / s) 81wt%, aliphatic-alicyclic urea as a urea-based thickener 12wt%, and ZnDTP 2wt% as a phosphorus-based friction modifier. Grease B: Loss tangent tanδ=0.14 Base oil is PAO8 (poly alpha olefin, kinematic viscosity 8mm at 100℃) 2 / s) 81wt%, alicyclic urea as a urea-based thickener, and TCP 2wt% as a phosphorus-based friction modifier. Grease C: Loss tangent tanδ=0.15 Base oil is PAO8 (poly alpha olefin, kinematic viscosity 8mm at 100℃) 2 / s) 81wt%, alicyclic urea as a urea-based thickener, and TPPT as a phosphorus-based friction modifier, 12wt%. Grease D: Loss tangent tanδ=0.15 Base oil is PAO8 (poly alpha olefin, kinematic viscosity 8mm at 100℃) 2 / s) 83wt%, and alicyclic urea 12wt% as a urea-based thickener. Grease E: Loss tangent tanδ=0.15 It contains 81 wt% PET oil (ester oil) as a base oil, 12 wt% fatty-aromatic urea as a urea-based thickener, and 2 wt% TCP as a phosphorus-based friction modifier.

[0048] Here, the dynamic viscoelasticity evaluation test was performed according to the following procedure. For the evaluation test, a stress-controlled Paar Physica MCR300 was used as the rheometer to measure frequency dependence. Grease was placed between the upper and lower plates, and the frequency of the upper plate was gradually changed at a constant strain to evaluate responsiveness. The frequency dependence measurement allowed the evaluation of the mechanical relaxation time from the temporal response of the sample's network structure. The measurement conditions were as follows: the grease to be measured was sandwiched between parallel plates of 25 mm diameter with a gap of 0.5 mm, and the temperature was 25°C, the frequency was 1 Hz, and the strain was 0.07 (fixed)%. The storage modulus (G') and loss modulus (G") were measured. In addition, the loss tangent tan δ was calculated from the storage modulus (G') and loss modulus (G") using the following formula (2). A large loss tangent tan δ value indicates that the substance is viscous, and a small value indicates that the substance is elastic. Loss tangent tanδ=G” / G’ (2)

[0049] In addition, the following rust preventive oils I to II were prepared. Anti-rust oil I: The base oil is PAO8 (polyalphaolefin, kinematic viscosity 48mm at 40℃). 2 / s) 93 wt%, and ZnDTP 2 wt% as a phosphorus-based friction modifier. Anti-rust oil II: It contains 93 wt% PET oil (ester oil) as a base oil and 2 wt% ZnDTP as a phosphorus-based friction modifier. All of the above samples contain 5% of metal deactivators, antioxidants, and rust inhibitors as other additives.

[0050] [Example 1] Using grease A and anti-rust oil I as shown in Table 1, a rolling bearing 1 shown in Figs. 1 to 3 was obtained. First, the outer ring 2, inner ring 3, rolling elements 4, and cage 5 were assembled. The assembled outer ring 2, inner ring 3, rolling elements 4, and cage 5 were coated with anti-rust oil I. Next, grease A was filled from the opening 51 side and non-opening 52 side. Here, grease A was placed in the corners X1 and X2 so as to form a continuous annular shape along the circumferential direction of the outer ring 2. After filling with grease A, one and the other shield plates 71, 72 (steel shields) were attached to both ends of the outer ring 2. In the obtained rolling bearing 1, when the spatial volume of the bearing space S was taken as 100%, the volume of the grease A arranged at one corner X1 and the other corner X2 was 12.5% ​​in total. When the total amount of filled grease was taken as 100 wt%, the amount of grease A arranged at one corner X1 on the opening 51 side was 60 wt%, and the amount of grease A arranged at the other corner X2 on the non-opening 52 side was 40 wt%. The outer diameter of the outer ring 2 was 13 mm, the inner diameter of the inner ring 3 was 8 mm, and the axial length was 4 mm.

[0051] [Example 2] A rolling bearing 1 was obtained in the same manner as in Example 1, except that the amount of grease A placed at one corner X1 on the opening 51 side and the amount of grease A placed at the other corner X2 on the non-opening 52 side were changed. When the total amount of filled grease was 100 wt%, the amount of grease A placed at one corner X1 on the opening 51 side was 50 wt%, and the amount of grease A placed at the other corner X2 on the non-opening 52 side was 50 wt%.

[0052] [Example 3] A rolling bearing 1 was obtained in the same manner as in Example 1, except that the amount of grease A placed at one corner X1 on the opening 51 side and the amount of grease A placed at the other corner X2 on the non-opening 52 side were changed. When the total amount of filled grease was 100 wt%, the amount of grease A placed at one corner X1 on the opening 51 side was 40 wt%, and the amount of grease A placed at the other corner X2 on the non-opening 52 side was 60 wt%.

[0053] [Example 4] A rolling bearing 1 was obtained in the same manner as in Example 1, except that the amount of grease A placed at one corner X1 on the opening 51 side and the amount of grease A placed at the other corner X2 on the non-opening 52 side were changed. When the total amount of filled grease was 100 wt%, the amount of grease A placed at one corner X1 on the opening 51 side was 20 wt%, and the amount of grease A placed at the other corner X2 on the non-opening 52 side was 80 wt%.

[0054] [Example 5] A rolling bearing 1 was obtained in the same manner as in Example 4, except that grease B was used.

[0055] [Example 6] A rolling bearing 1 was obtained in the same manner as in Example 4, except that grease C was used.

[0056] [Comparative Example 1] A rolling bearing was obtained using grease A and anti-rust oil I as shown in Table 1. First, the outer ring 2, inner ring 3, rolling elements 4 and cage 5 were assembled. The assembled outer ring 2, inner ring 3, rolling elements 4 and cage 5 were immersed in anti-rust oil I. Next, grease A was filled only from the non-opening 52 side. Here, at the corner X2, grease A was placed in a continuous annular shape along the circumferential direction of the outer ring 2. After filling with grease A, one and the other shield plates 71, 72 (steel shields) were attached to both ends of the outer ring 2. In the obtained rolling bearing 1, when the spatial volume of the bearing space S was taken as 100%, the volume of the grease A arranged at one corner X1 and the other corner X2 was 12.5% ​​in total. When the total amount of filled grease was taken as 100 wt%, the amount of grease A arranged at one corner X1 on the opening 51 side was 0 wt%, and the amount of grease A arranged at the other corner X2 on the non-opening 52 side was 100 wt%. The outer diameter of the outer ring 2 was 13 mm, the inner diameter of the inner ring 3 was 8 mm, and the axial length was 4 mm.

[0057] [Comparative Example 2] A rolling bearing was obtained using grease A and anti-rust oil I as shown in Table 1. First, the outer ring 2, inner ring 3, rolling elements 4 and cage 5 were assembled. The assembled outer ring 2, inner ring 3, rolling elements 4 and cage 5 were immersed in anti-rust oil I. Next, grease A was filled only from the opening 51 side. Here, grease A was placed in the corner X1 so as to form a continuous annular shape along the circumferential direction of the outer ring 2. After filling with grease A, one and the other shield plates 71, 72 (steel shields) were attached to both ends of the outer ring 2. In the obtained rolling bearing 1, when the spatial volume of the bearing space S was taken as 100%, the volume of the grease A arranged at one corner X1 and the other corner X2 was 12.5% ​​in total. When the total amount of filled grease was taken as 100 wt%, the amount of grease A arranged at one corner X1 on the opening 51 side was 100 wt%, and the amount of grease A arranged at the other corner X2 on the non-opening 52 side was 0 wt%. The outer peripheral diameter of the outer ring 2 was 13 mm, the inner peripheral diameter of the inner ring 3 was 8 mm, and the axial length was 4 mm.

[0058] [Comparative Example 3] A rolling bearing was obtained in the same manner as in Example 4, except that grease A and rust preventive oil II were used.

[0059] [Comparative Example 4] A rolling bearing was obtained in the same manner as in Example 4, except that grease D and rust preventive oil I were used.

[0060] [Comparative Example 5] A rolling bearing was obtained in the same manner as in Example 4, except that grease E and rust preventive oil II were used.

[0061] [Comparative Example 6] A rolling bearing was obtained using grease A and anti-rust oil I as shown in Table 1. First, the outer ring 2, inner ring 3, rolling elements 4 and cage 5 were assembled. The assembled outer ring 2, inner ring 3, rolling elements 4 and cage 5 were immersed in anti-rust oil I. Next, the transfer section and grease pockets of the cage were filled with grease A, and then one and the other shield plates 71, 72 were attached to both ends of the outer ring 2. In the obtained rolling bearing 1, when the spatial volume of the bearing space S was taken as 100%, the volume of the grease A was 12.5%. The outer peripheral diameter of the outer ring 2 was 13 mm, the inner peripheral diameter of the inner ring 3 was 8 mm, and the axial length was 4 mm.

[0062] <Evaluation method and results> ·Life characteristics The rolling bearing was rotated at room temperature with the inner ring rotated by a test motor. The axial preload Fa was set to 12 N. The rotation speed was set to 150,000 rpm. Bearings that maintained rotation under these conditions for 500 hours or more were judged to pass (○). Bearings that maintained rotation for less than 500 hours were judged to fail (×). Torque stabilization time The rolling bearing was rotated at room temperature with the inner ring rotated by a test motor. The axial preload Fa was set to 12 N. The time it took for the torque to rise to the specified rotation speed (150,000 rpm) was measured. Bearings with a torque stabilization time of 300 seconds or less were deemed to have passed (○). Bearings with a torque stabilization time of more than 300 seconds were deemed to have failed (×). The evaluation results are shown in Table 1.

[0063] [Table 1] [Explanation of symbols]

[0064] 1, 1A: rolling bearing, 2: outer ring, 21: raceway groove, 3: inner ring, 31: raceway groove, 4: rolling element, 5: cage, 51: opening, 52: non-opening, 6, 6A: grease, 71: one shield plate, 72: other shield plate, 8: mounting groove, 9: retaining ring, 100: motor, 101: shaft, 102: rotor core, 103: bearing device, 104: spring, 105: sleeve, 106: impeller

Claims

1. The outer ring and an inner ring disposed on an inner circumferential side of the outer ring; a plurality of rolling elements provided between the raceway groove of the outer ring and the raceway groove of the inner ring; a cage having pockets for rotatably holding the rolling elements; grease disposed in a bearing space surrounded by the outer ring and the inner ring; Equipped with the grease is filled on an inner peripheral surface side of the outer ring on both one axial side and the other axial side of the bearing space with the rolling elements therebetween, The grease has a loss tangent of 0.1 or more and 0.2 or less when measured under conditions of a temperature of 25°C, a frequency of 1 Hz, and a strain amount of 0.07 (fixed)%, and contains only a synthetic hydrocarbon oil as a base oil, a urea-based thickener, and a phosphorus-based friction modifier; Furthermore, a rust-preventive oil is applied to the raceway groove of the outer ring and the raceway groove of the inner ring, The rust-preventive oil contains only a synthetic hydrocarbon oil as a base oil and a phosphorus-based friction modifier. Rolling bearing.

2. a shield plate that closes a gap between the outer ring and the inner ring at one end side in the axial direction; another shield plate that closes a gap between the outer ring and the inner ring at the other end side in the axial direction; Further equipped with the bearing space is surrounded by the outer ring, the inner ring, the one shield plate, and the other shield plate, The grease is disposed in one corner of the bearing space formed by the inner circumferential surface of the outer ring and the one shield plate, and in the other corner of the bearing space formed by the inner circumferential surface of the outer ring and the other shield plate.

2. The rolling bearing according to claim 1.

3. The cage is a crown type cage, and has a plurality of openings for respectively accommodating the plurality of rolling elements at one end side in the axial direction, and has non-openings at the other end side in the axial direction.

3. A rolling bearing according to claim 1 or 2.

4. the cage is a crown type cage, and has a plurality of openings at one end side in the axial direction for respectively accommodating the plurality of rolling elements, and has a non-opening at the other end side in the axial direction, The amount of the grease arranged at the one corner on the opening side is equal to the amount of the grease arranged at the other corner on the non-opening side, or the amount of the grease arranged at the one corner on the opening side is less than the amount of the grease arranged at the other corner on the non-opening side.

3. The rolling bearing according to claim 2.

5. The grease is in a circular ring shape.

5. The rolling bearing according to claim 4.

6. When the total volume of the grease is taken as 100%, the volume of the grease disposed in the one corner is in the range of 20% to 60%, and the volume of the grease disposed in the other corner is in the range of 40% to 80%.

6. A rolling bearing according to claim 4 or 5.

7. When the spatial volume of the bearing space is taken as 100%, the volume of the grease disposed in the one corner portion and the other corner portion is 5% or more and 20% or less in total. A rolling bearing according to any one of claims 1 to 6.

8. The rust-preventive oil further contains a sulfur-based rust-preventive additive. A rolling bearing according to any one of claims 1 to 7.

9. A rolling bearing assembly comprising: a pair of rolling bearings according to any one of claims 1 to 8; a spring that applies a preload to each of the rolling bearings; and a sleeve that surrounds the pair of rolling bearings; The outer circumferential surfaces of the outer rings of the pair of rolling bearings are fixed to the sleeve. Bearing device.

10. A bearing device comprising: a shaft; a rotor core attached to the shaft; and the bearing device according to claim 9. Motor.

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