Rolling bearings

Abstract

To provide a bearing that ensures electrical conductivity. [Solution] A bearing used in motors, reducers, and transmissions is provided, comprising a first raceway 12, a second raceway 13, a plurality of rolling elements 15 assembled at circumferential intervals in an annular bearing space 14 formed between the first raceway 12 and the second raceway 13, and a sealing member 16 that seals the bearing space 14, wherein the sealing member 16 is conductive, the sealing member 16 is fitted to the first raceway 12, and a solid lubricant 17 containing conductive grease is placed on the sealing surface 16a between the sealing member 16 and the second raceway 13, or on the sealing side surface 16b of the sealing member 16.

Description

Technical Field

[0001] The present invention relates to rolling bearings, more specifically, rolling bearings such as main shaft bearings used in motors, speed reducers, and transmissions used in electric vehicles (EVs), hybrid cars (HEVs), etc.

Background Art

[0002] The electric motors (motors) used in electric vehicles (EVs), hybrid cars (HEVs), etc. may vary the frequency by inverter control for higher efficiency. However, when the frequency increases, an EDM current due to capacitance and a high-frequency circulating current may flow inside the motor support bearing, and electrical erosion may occur inside the bearing. As a countermeasure, there is a method of imparting conductivity to the bearing by using a conductive seal member and a conductive lubricant.

[0003] Examples of bearings with conductive grease encapsulated inside the bearing include, for example, the energized grease encapsulated bearings described in Patent Documents 1 and 2. The bearings of these patent documents include, as shown in FIG. 7 of the present application, an outer ring 2, an inner ring 3, a plurality of rolling elements 4 interposed between the raceway surface 2a of the outer ring 2 and the raceway surface 3a of the inner ring 3, a cage 5 that holds the rolling elements 4 at a predetermined circumferential interval, a conductive seal member 6 that seals the inside of the bearing, and a conductive grease 7 disposed between the tip of the lip portion of the conductive seal member 6 and the inner ring 3. The tip portion of the lip portion of this conductive seal member 6 has a predetermined shape and has a function of holding the conductive grease 7. Therefore, it becomes possible to conduct electricity through the conductive seal member 6 and the conductive grease 7, and conductivity can be imparted to the bearing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] Incidentally, in the conductive grease 7 described above, the conductive material used is metallic soap or graphite in Patent Document 1, and carbon black or an ionic fluid in Patent Document 2. When electricity flows through the bearing 1 described in Patent Documents 1 and 2, the electricity flows through the conductive material that constitutes the conductive grease 7. However, since the conductive seal member 6 is located close to the outside of the bearing, the conductive grease 7 is also located close to the outside of the bearing. As a result, there is a risk that the conductive grease 7 may leak out due to rotation during use. If the conductive grease 7 leaks out, only an oil film will remain between the tip of the lip portion of the conductive seal member 6 and the inner ring 3, making it difficult to maintain the conductive function. Furthermore, during the rotation of the bearing 1, if the distribution of conductive material in the conductive grease 9 becomes uneven, there may be areas between the tip of the lip portion of the conductive seal member 6 and the inner ring 3 where no conductive material exists, making it difficult to form an electrical circuit and ensure current flow. In these cases, a discharge may occur between the tip of the lip portion of the conductive seal member 6 and the inner ring 3, potentially leading to electrolytic corrosion inside the bearing.

[0006] The inventors of this invention focused on the fact that during bearing rotation, conductive grease can leak to the outside or conductive material can become unevenly distributed within the conductive grease, making it impossible to ensure conductivity. They then focused on the fact that if these issues could be suppressed, conductivity could be ensured. [Means for solving the problem]

[0007] Based on this focus, this invention provides a bearing with the following configuration in order to solve the aforementioned problems. [Configuration 1] A rolling bearing for use in motors, speed reducers, and transmissions, comprising a first raceway, a second raceway, a plurality of rolling elements arranged at circumferential intervals in an annular bearing space formed between the first and second raceway, and a sealing member that seals the bearing space, wherein the sealing member is conductive, the sealing member is fitted to the first raceway, and a solid lubricant containing conductive grease is placed on the sealing surface between the sealing member and the second raceway, or on the sealing side surface of the sealing member.

[0008] By adopting this configuration, a solid lubricant containing conductive grease is used, which suppresses grease leakage and uneven distribution of conductive material. Furthermore, since this solid lubricant is placed on the sealing surface between the seal member and the second raceway ring, or on the sealed side surface of the seal member, the supply of lubricating oil within the bearing is ensured, and electricity can flow through the seal member within the bearing. As a result, stable conductive performance can be maintained, and since the circuit through which electricity flows within the bearing is maintained and current flow is ensured, discharge between the rolling elements and the inner first raceway ring can be suppressed, thereby extending the lifespan of the bearing.

[0009] [Configuration 2] The rolling bearing according to [Configuration 1], wherein the solid lubricant disposed on the sealing surface is distributed in multiple locations in the circumferential direction of the sealing surface, or is distributed over the entire surface of the sealing surface. By adopting this configuration, current is ensured between the sealing member and the second raceway. As a result, an electrical circuit is maintained within the bearing, ensuring current flow. This suppresses discharge between the rolling elements and the first or second raceway, thereby extending the lifespan of the bearing.

[0010] [Configuration 3] The sealing member is a member having an annular core and on its sealing side, an annular first resin part and a second resin part having conductive peripheral edges on the outer and inner peripheral edges of the core; the peripheral edge of the sealing member on the side having the first resin part is fitted into a first raceway ring; the second resin part has a main lip of an annular lip formed at its tip and an annular convex resin part formed on the inner peripheral side of the annular lip; a notch is formed in a part of the convex resin part; and the solid lubricant is distributed from the first resin part to the lip on the sealing side of the sealing member, as described in [Configuration 1]. By adopting this configuration, current is ensured between the first raceway, the sealing member, and the second raceway. As a result, an electrical circuit is maintained within the bearing, ensuring current flow. This suppresses discharge between the rolling elements and the first or second raceway, thereby extending the lifespan of the bearing.

[0011] [Configuration 4] The rolling bearing according to [Configuration 3], wherein the first resin portion is provided with a recess for preventing the solid lubricant from coming off, and the first resin portion and the convex resin portion are provided with an undercut portion for preventing the solid lubricant from coming off. This configuration prevents the solid lubricant from detaching, thus preventing interruptions in the supply of lubricating oil.

[0012] [Configuration 5] A rolling bearing according to [Configuration 3], wherein the circumferential surface of the solid lubricant disposed on the sealing side surface of the sealing member faces the tapered surface provided on the second raceway, the tip of the main lip protrudes from the circumferential surface of the solid lubricant toward the tapered surface of the second raceway, and the tip of the main lip and the tapered surface are in contact. By adopting this configuration, contact between the sealing member and the second raceway can be more reliably ensured, and current flow between them is maintained. As a result, an electrical circuit is maintained within the bearing, ensuring current flow, which suppresses discharge between the rolling elements and the first and second raceway rings, thereby extending the lifespan of the bearing.

[0013] [Configuration 6] The rolling bearing according to [Configuration 5], wherein the lip portion has a dust lip together with the main lip, the tip of the main lip and the tapered surface are in contact, and the dust lip is in a non-contact state or in contact state with the second raceway ring. By adopting this configuration, contact between the sealing member and the second raceway can be made even more reliable, ensuring current flow between them. As a result, an electrical circuit is maintained within the bearing, ensuring current flow. This suppresses discharge between the rolling elements and the first and second raceway rings, thereby extending the lifespan of the bearing.

[0014] [Configuration 7] The rolling bearing according to [Configuration 1], wherein the solid lubricant is a conductive lubricant having the conductive grease. This configuration allows for the solidification of conductive grease.

[0015] [Configuration 8] The conductive material contained in the conductive grease is a substance containing metal, carbon black, graphite, graphite, conductive carbon fiber, and ionic liquid, as described in [Configuration 1]. These may be used individually or in combination. Adopting this configuration can further improve conductivity.

[0016] [Configuration 9] A rolling bearing as described in [Configuration 1], used in motors, reducers, and transmissions. The rolling bearing described in [Configuration 1] can maintain conductivity, thus preventing discharge between the rolling elements and the first and second raceways, and can be used in motors, reducers, and transmissions. [Effects of the Invention]

[0017] The bearing of this invention uses a solid lubricant containing conductive grease, which prevents leakage of the conductive grease and prevents the conductive material from becoming unevenly distributed during bearing rotation, thus maintaining stable conductive performance. Therefore, it is possible to suppress discharge within the bearing compared to conventional bearings sealed with conductive grease, thereby extending the lifespan of the bearing. Also, by using a predetermined seal member and disposing a solid lubricant at a predetermined position, even if the solid lubricant is disposed at a position close to the outside, such as the seal member, leakage of lubricating grease is suppressed, lubricity is maintained, and a circuit through which electricity flows inside the bearing is maintained, ensuring energization. Therefore, discharge between the rolling elements and the first and second raceway rings can be suppressed, and the life of the bearing can be extended. From these, the bearing of this invention can be usefully used as a bearing for a motor used in an electric vehicle (EV), a hybrid car (HEV), or the like.

Brief Description of the Drawings

[0018] [Figure 1] (a) Cross-sectional view showing an example of a bearing according to an embodiment of this invention, (b) Cross-sectional view taken along line A-A of the second raceway ring in (a), (c) Another cross-sectional view taken along line A-A of the second raceway ring in (a) [Figure 2] (a) Partial cutaway view of a seal member according to an embodiment of this invention, (b) Partial cutaway view of the seal member in (a) with a solid lubricant disposed thereon, (c) Cross-sectional view of a bearing having the seal member shown in (b), showing the state of being cut at the location C-C in (b), (d) Cross-sectional view of a bearing having the seal member shown in (b), showing the state of being cut at the location D-D in (b) [Figure 3] (a) Partially enlarged cross-sectional view of FIG. 2(c), (b) Another example of (a), showing a partially enlarged cross-sectional view of the first resin portion of the seal [Figure 4] Another example of FIG. 2(c), showing a partially enlarged cross-sectional view of the second resin portion of the seal [Figure 5] (a) Partially enlarged cross-sectional view of FIG. 2(c), (b) Partially enlarged cross-sectional view showing the state where the main lip is worn and in contact with the stepped surface of the second raceway ring [Figure 6] Partial cutaway view showing an example of the seal member shown in FIG. 2(a) with a notch provided in the first resin portion [Figure 7] Cross-sectional view showing an example of a conventional bearing

Embodiments for Carrying Out the Invention

[0019] Bearings 11 and 11' according to embodiments of this invention are shown in Figures 1(a) and 2(c) and 2(d). These bearings 11 and 11' include a first raceway ring 12, a second raceway ring 13 coaxially provided radially inside or outside the first raceway ring 12, a plurality of rolling elements 15 incorporated at regular intervals in the circumferential direction in an annular bearing space 14 formed between the first raceway ring 12 and the second raceway ring 13, a sealing member 16 that seals the bearing space 14, and, if necessary, a cage 18 that holds the plurality of rolling elements 15. In the figures of this application specification, the outer ring is shown as the first raceway ring and the inner ring as the second raceway ring, but the invention is not limited to this representation.

[0020] The axial direction is the direction parallel to the central axes of the first raceway 12 and the second raceway 13 (the central axis of the bearing), the radial direction is the direction perpendicular to the central axes of the first raceway 12 and the second raceway 13, and the circumferential direction is the direction along the circumference that revolves around the central axes of the first raceway 12 and the second raceway 13.

[0021] As shown in Figures 1(a) and 2(c)(d), the inner circumference of the first raceway 12 has a first raceway surface 12a on which the rolling elements 15 roll and make contact, and a pair of first raceway shoulder surfaces 12b that extend circumferentially adjacent to the first raceway surface 12a in the axial direction. The first raceway surface 12a is the inner surface of a groove with a circular arc cross-section that extends circumferentially on the inner circumference of the first raceway 12, and the first raceway shoulder surfaces 12b are cylindrical surfaces with a constant inner diameter along the axial direction.

[0022] On the outer circumference of the second raceway 13, there is a second raceway surface 13a on which the rolling elements 15 roll and make contact, and a pair of second raceway shoulder surfaces 13b that extend circumferentially adjacent to the second raceway surface 13a in the axial direction. The second raceway surface 13a is the outer surface of a groove with a circular arc cross-section that extends circumferentially around the outer circumference of the second raceway 13, and the second raceway shoulder surfaces 13b are cylindrical surfaces with a constant outer diameter along the axial direction.

[0023] The rolling elements 15 are in rolling contact with the raceway surface 12a of the first raceway ring and the raceway surface 13a of the second raceway ring. In Figures 1(a) and 2(c)(d), the raceway surface 12a of the first raceway ring is formed symmetrically with respect to the axial center of the first raceway ring 12, and the raceway surface 13a of the second raceway ring is also formed symmetrically with respect to the axial center of the second raceway ring 13, but symmetry is not necessarily required. This bearing 11 is a rolling bearing in which the rolling elements 15 are balls or rollers, and examples of bearings in which the rolling elements 15 are balls include ball bearings such as deep groove ball bearings.

[0024] The retainer 18 is a component that partially surrounds the rolling elements 15 and maintains them at a constant distance in the circumferential direction. This retainer 18 may be formed from a metal plate such as an iron plate or from resin.

[0025] The sealing member 16 is a member having conductivity, comprising a metal annular core portion 16c and a conductive resin disposed on this core portion 16c. This conductive resin is disposed on at least two peripheral edges: the outer edge and the inner edge. The conductive resin is preferably a rubber material with a high elastic limit and low elastic modulus, and a conductive filler such as carbon black or graphite. Among these, resins with high heat resistance, such as acrylic rubber, hydrogenated nitrile rubber, and fluororubber, are particularly preferred. Using these conductive resins prevents the conductive resin from hardening when the solid lubricant is fired, as will be described later. This conductive resin is applied to the first resin part 16d and the second resin part 16e below.

[0026] As shown in Figures 1(a) and 2(c)(d), one peripheral edge of the sealing member 16 is fitted onto the first raceway ring 12. This prevents the sealing member 16 from coming off during use of the bearings 11 and 11'. The resin portion of the peripheral edge of the sealing member 16 that is fitted onto the first raceway ring 12 is referred to as the first resin portion 16d. The resin portion of the other peripheral edge of the sealing member 16 is referred to as the second resin portion 16e. The second resin portion 12e of the sealing member 16 has an annular lip portion formed at its tip. This lip portion may consist only of a main lip 16f, or it may have a main lip 16f and a dust lip 16m. In the figures of this patent application, the peripheral edge of the sealing member 16 that fits onto the first raceway 12 is shown as the outer peripheral edge, but it is not limited to this.

[0027] As shown in Figure 1(a), a solid lubricant 17 containing conductive grease can be placed on the sealing surface 16a between the tip of the main lip 16f of the sealing member 16 and the second raceway ring 13. This ensures lubrication at the sealing sliding portion and ensures electrical conductivity between the sealing member 16 and the second raceway ring 13. In Figure 1(a), the sealing surface 16a is provided in the groove 13e provided in the second raceway shoulder 13b, but it is not limited to this, and may be a stepped portion 13f as shown in Figures 2(c) and 2(d). The groove 13e and stepped portion 13f provided in the second raceway shoulder 13b are collectively referred to as the stepped surface 13c.

[0028] As for the method of applying a solid lubricant 17 containing conductive grease to the sealing surface 16a between the tip of the main lip 16f of the sealing member 16 and the second raceway ring 13, as shown in Figure 1(b), one method is to apply the solid lubricant 17 to the entire surface of the area where the tip of the main lip 16f is located, or as shown in Figure 1(c), one method is to distribute the solid lubricant 17 in multiple locations where the tip of the main lip 16f is located. When distributing in a scattered manner, it is preferable to distribute it evenly without bias, such as by making equal distributions, as this facilitates quality control.

[0029] Furthermore, as shown in Figures 2(c) and 2(d), a solid lubricant 17 containing conductive grease can be placed on the sealed side surface 16b of the seal member 16. This ensures lubrication in the seal sliding portion and allows for current flow between the seal member 16 and the second raceway ring 13. In addition to the solid lubricant 17 placed on the sealed side surface 16b of the seal member 16, rolling bearing grease or a solid lubricant may be sealed in the bearing space 14 to ensure lubrication of the rolling contact portion.

[0030] Furthermore, as shown in Figure 2(a), the second resin portion 16e of the sealing member 16 is provided with an annular convex resin portion 16g on the inner circumference side of the annular lip portion having the annular main lip 16f. A notch 16h is formed in a part of this convex resin portion 16g. As shown in Figure 2(b), the solid lubricant 17 is distributed from the first resin portion 16d to the main lip 16f of the second resin portion on the sealing side surface 16b of the sealing member 16. At this time, the solid lubricant 17 is distributed up to the vicinity of the top of the main lip 16f of the lip portion of the first resin portion 16d and the second resin portion 16e. Furthermore, the top of the convex resin portion 16g may be in a state where it is not covered by the distributed solid lubricant 17, or it may be in a state where it is covered and embedded by the solid lubricant 17. On the other hand, the notch portion 16h is covered within the solid lubricant 17. For this reason, the solid lubricant 17 distributed between the convex resin portion 16g and the tip of the main lip 16f and the solid lubricant 17 distributed between the first resin portion 16d and the convex resin portion 16g are continuous at least through the portion of the notch portion 16h.

[0031] In this case, the second resin portion 16e of the sealing member 16 is positioned on the second raceway 13 side, so the lubricating components of the solid lubricant 17 located on the second resin portion 16e side are supplied to the second raceway 13. Over time, this may lead to insufficient lubrication from the solid lubricant 17 positioned between the convex resin portion 16g and the tip of the main lip 16f. However, since lubricating components can be supplied from the solid lubricant 17 positioned between the first resin portion 16d and the convex resin portion 16g, insufficient lubrication can be avoided. Furthermore, since the bearing 11' rotates, there is a possibility that the solid lubricant 17 may rotate independently of the sealing member 16. If this happens, there is a risk that the solid lubricant 17 will become detached from the sealing member 16. However, the stepped surface between the convex resin portion 16g and the notched portion 16h prevents the solid lubricant 17 from rotating independently of the sealing member 16. This prevents the solid lubricant 17 from becoming detached from the sealing member 16 and ensures the supply of lubricating components.

[0032] Incidentally, the first resin part 16d is provided with a semicircular recess 16i for preventing the solid lubricant 17 from detaching, as shown in Figure 3(a). By providing this recess, when the solid lubricant 17 is introduced and solidified, the solid lubricant flows into the recess 16i and solidifies therein, thus preventing the solid lubricant 17 from detaching. Note that the shape of the recess 16i is not limited to a semicircular shape; for example, it may be a triangular recess 16i' as shown in Figure 3(b), and its shape is not limited.

[0033] Furthermore, the first resin portion 16d and the convex resin portion 16f are provided with undercut portions 16j and 16k to prevent the solid lubricant from detaching. An undercut is a stepped or inclined portion provided from the inside of the frame toward the open end to prevent the internal resin molded product from coming out in the open direction of the surrounding frame. By providing these undercut portions 16j and 16k, the detachment of the solid lubricant 17 can be prevented.

[0034] Next, as shown in Figure 4, a stepped surface 13c such as a stepped portion 13f is provided on the shoulder surface 13b of the second raceway, and a tapered surface 13d is formed on the stepped surface between the shoulder surface 13b of the second raceway 13 and the stepped surface 13c. Specifically, a tapered surface 13d having an inclination of 90° or less from the second raceway shoulder surface 13b towards the bottom surface of the stepped surface 13c. Furthermore, the sealing member 16 is positioned on the stepped surface 13c such that the circumferential surface of the solid lubricant 17, which is placed on the sealing side surface 16b of the sealing member 16, faces the tapered surface 13d. At this time, as shown in Figure 4, the tip of the main lip 16f of the lip portion of the second resin portion 16e of the sealing member 16 is provided to protrude from the circumferential surface of the solid lubricant 17 toward the tapered surface 13d.

[0035] Then, the tip of the main lip 16f is brought into contact with the tapered surface 13d of the opposing surface of the second raceway 13. This ensures that current flows between the sealing member 16 and the second raceway 13. Furthermore, it is preferable that the tip of the main lip 16f is pressed against the tapered surface 13d. Although the tip of the main lip 16f wears down due to the rotation of the bearing 11' according to this invention, the lip portion is elastic, so by pressing the tip of the main lip 16f against the tapered surface 13d, it is possible to maintain contact between the tip of the main lip 16f and the tapered surface 13d until the main lip 16f wears down to a certain extent and loses its return elasticity.

[0036] Incidentally, when the lip portion has a dust lip 16m together with the main lip 16f, it is preferable that the tip of the main lip 16f and the tapered surface 13d of the opposing surface of the stepped surface 13c are in contact, as shown in Figures 5(a) and (b), and that the tip of the dust lip 16m is either in contact with or not in contact with the stepped surface 13c of the second raceway 13. Even if the tip of the dust lip 16m is not in contact with the stepped surface 13c of the second raceway 13, as the tip of the main lip 16f is worn down and loses its return elasticity, the lip portion rotates as shown by the arrow in Figure 5(b), and the tip of the dust lip 16m comes into contact with the stepped surface 13c. For this reason, even if the tip of the main lip 16f is worn down, the contact between the lip portion and the second raceway 13 can be maintained, and current can be ensured between the sealing member 16 and the second raceway 13.

[0037] This is due to the following mechanism: When the tip of the main lip 16f is not worn, as shown in Figure 5(a), the tip of the dust lip 16m is in a non-contact state, separated from the bottom surface of the stepped surface 13c of the second raceway shoulder 13b. Next, as the tip of the main lip 16f wears down due to the rotation of the bearing 11' of the present invention, the main lip 16f and the dust lip 16m of the lip portion rotate in the direction of the tapered surface 13d of the second raceway ring 13, as shown by the arrow in Figure 5(b). As a result, the tip of the dust lip 16m comes into contact with the bottom surface of the stepped surface 13c of the second raceway ring 13.

[0038] The solid lubricant 17 is a conductive lubricant formed by solidifying a mixture of conductive grease and a resin component as lubricating components. The conductive grease consists of a conductive component and a lubricating component. Lubrication is imparted to the solid lubricant by the seepage of base oil contained in the conductive grease, and conductivity is also imparted to the solid lubricant 17 by the conductive substance. The mixture of solid lubricants may have additional conductive components added to further enhance conductivity. The physical state of this conductive component can be selected from powdery, fibrous, foil-like solids or liquids.

[0039] The lubricating component can be a base oil of grease, or a mixture of this base oil with lubricating oil or solid lubricant as needed. Examples of the base oil or lubricating oil of the grease include, but are not limited to, one or more types of oils such as liquid paraffin, PAO oil, vegetable oil, animal oil, and normal paraffin components whose most frequent content in the linear carbon number distribution is between 30 and 33 linear carbon atoms. Furthermore, the thickeners and additives (viscosity index improvers, rust inhibitors, etc.) used in the grease are not limited and any can be used. Examples of the solid lubricant include molybdenum disulfide, polytetrafluoroethylene (PTFE), and graphite. Furthermore, wax may be added to prevent leakage of lubricating components from the bearing. This lubricating component can be used in an amount of 5% by mass or more relative to the conductive grease, which can be freely adjusted.

[0040] A conductive material is used as the conductive component. This conductive material can be either a conductive filler or an ionic liquid, or both can be used in combination. The conductive filler can be a metal-based material such as a metal containing metal powder such as copper powder (including metal plating systems) or a metal compound (including metal oxides), or a carbon-based material such as carbon black, graphite, conductive carbon fiber, etc. These can be in powder, fibrous, or foil form, and multiple sizes and shapes can be combined. Furthermore, a dispersant (dispersibility enhancer) or colorant may be added to alleviate the aggregation of the conductive filler.

[0041] The resin component of the solid lubricant 17 can be either thermoplastic or thermosetting resins, such as general-purpose plastics or engineering plastics like ultra-high molecular weight polyolefins, polyamides, polyacetals, fluororesins, silicones, polyurethanes, polyolefins, polystyrenes, and polyvinyl chlorides. If heat resistance is required, it is preferable to use a thermosetting resin.

[0042] Specific examples of the aforementioned ultra-high molecular weight polyolefin include powders made from polyethylene, polypropylene, polybutene, or copolymers thereof, or mixed powders containing each of these powders individually. Here, the average molecular weight of each powder, as measured by the viscosity method, is 1 × 10⁻⁶. 6 The above is preferable. Polyolefins within this molecular weight range are superior to low molecular weight polyolefins in terms of rigidity and oil retention. Furthermore, among ultra-high molecular weight polyolefins, it is preferable to use ultra-high molecular weight polyethylene. As an example of a solid lubricant using ultra-high molecular weight polyolefins such as ultra-high molecular weight polyethylene as the resin component, one example is "Polyloop" manufactured by NTN Corporation.

[0043] In the aforementioned solid lubricant, ultra-high molecular weight polyolefin is contained in an amount of 10-90% by mass, and conductive grease is contained in an amount of 90-10% by mass. This configuration allows for moderate suppression of oil separation.

[0044] The mixture of conductive grease and resin component can be solidified by methods such as heating and firing, curing with ultraviolet light (light), or two-component curing (epoxy resin). A method for producing the solid lubricant by the heating and sintering method described above includes uniformly mixing the lubricating component and the resin component, directly filling the mixture into a mold or bearing of a predetermined shape, heating it to a temperature above the gelling point (melting point) of the resin component, and then cooling it to solidify it. The method for mixing the lubricating component and the resin component is not particularly limited, and commonly used agitators such as Henschel mixers and ribbon mixers can be used. Furthermore, it is preferable that the heating (firing) conditions are above the gelling point of the resin component and below the dropping point of the lubricating component. For example, the resin component may have an average molecular weight of 1 × 10⁻⁶ 6 In the case of the above-mentioned ultra-high molecular weight polyolefins, heating at a temperature of 150 to 200°C is preferable.

[0045] Furthermore, the aforementioned methods of curing with ultraviolet light (light) or by mixing two components eliminate the need for heating and cooling compared to methods involving heating and firing, thus improving time efficiency and preventing deterioration of the parts of the material that are heated and fired.

[0046] Since the resulting solid lubricant is solidified by the method described above, the conductive component in the lubricating component is immobilized, preventing the lubricating component from leaking out of the seal member 16 or from becoming unevenly distributed within the conductive grease during bearing rotation, thereby maintaining the conductivity of the bearing.

[0047] Incidentally, it is preferable to perform the aforementioned heating (sintering) on ​​the seal member 16 alone. If it is sintered while assembled in the bearing, there is a concern that the grease sealed inside the bearing may deteriorate due to heat depending on the sintering temperature, or that the bearing steel may be tempered and softened. Furthermore, since the seal member 16 alone is smaller in size than the bearing, it can be fed into the sintering furnace in large quantities at once, which is also preferable from the viewpoint of productivity. Furthermore, providing a notch 16n in a part of the outer peripheral edge of the sealing member 16 is preferable because it allows for the release of internal pressure when the bearing temperature rises and suppresses changes in the contact pressure of the seal lip by suppressing the pressure difference between the inside and outside of the bearing.

[0048] The volume resistivity of the solid lubricant is set to 1 × 10⁻⁶ for the purpose of increasing conductivity. 6 A value of Ω·cm or less is preferable.

[0049] The bearing according to this invention can be used as a bearing for motors, reducers, and transmissions used in electric vehicles (EVs) and hybrid electric vehicles (HEVs), etc. [Explanation of symbols]

[0050] 1 bearing 2 Outer ring 2a Outer ring raceway surface 3. Inner Ring 3a Inner ring raceway surface 4 Rolling elements 5 Cage 6. Conductive sealing member 7. Conductive grease 11, 11' bearing 12. First orbital ring 12a First track ring track surface 12b First track wheel shoulder 13. Second orbital ring 13a Second track wheel track surface 13b Second track wheel shoulder 13c Step surface 13d tapered surface 13e Groove 13f Stepped section 14. Bearing space 15 Rolling element 16. Sealing member 16a Sealing surface 16b Sealed side 16c Core metal part 16d First resin part 16e Second resin part 16f Main Lip 16g convex resin part 16h Notch 16i, 16i' recessed 16j undercut section 16k undercut section 16m Dust Trip 16n notch 17 Solid lubricants 18 Cage

Claims

1. First orbital ring (12), The second orbital ring (13), A plurality of rolling elements (15) are incorporated at circumferential intervals in an annular bearing space (14) formed between the first raceway ring (12) and the second raceway ring (13), and The bearing space (14) is sealed by a sealing member (16), It is a rolling bearing, The sealing member (16) is electrically conductive. The sealing member (16) is fitted onto the first raceway ring (12), A rolling bearing in which a solid lubricant (17) containing conductive grease is placed on the sealing surface (16a) between the sealing member (16) and the second raceway ring (13), or on the sealing side surface (16b) of the sealing member (16).

2. The rolling bearing according to claim 1, wherein the solid lubricant (17) disposed on the sealing surface (16a) is distributed at multiple locations in the circumferential direction of the sealing surface (16a), or is distributed over the entire surface of the sealing surface (16a).

3. The sealing member (16) has an annular core metal portion (16c), and on its sealing side surface (16b), it has an annular first resin portion (16d) and a second resin portion (16e) that are conductive on the outer and inner peripheral edges of the core metal portion (16c). The peripheral edge of the sealing member (16) having the first resin portion (16d) is fitted onto the first raceway ring (12). The second resin portion (16e) has a main lip (16f) of an annular lip portion formed at its tip and an annular convex resin portion (16g) formed on the inner circumference side of the annular lip portion. A notch (16h) is formed in a part of the convex resin portion (16g). The rolling bearing according to claim 1, wherein the solid lubricant (17) is distributed from the first resin portion (16d) to the lip portion on the sealing side surface (16b) of the sealing member (16).

4. The first resin part (16d) is provided with a recess (16i) for preventing the solid lubricant (17) from coming off. The rolling bearing according to claim 3, wherein the first resin portion (16d) and the convex resin portion (16g) are provided with undercut portions (16j, 16k) for preventing the solid lubricant from coming off.

5. The circumferential surface of the solid lubricant (17) disposed on the sealing side surface (16b) of the sealing member (16) and the tapered surface (13d) provided on the second raceway ring (13) face each other. The tip of the main lip (16f) protrudes from the circumferential surface of the solid lubricant (17) toward the tapered surface (13d) of the second raceway ring (13), The rolling bearing according to claim 3, wherein the tip of the main lip (16f) and the tapered surface (13d) are in contact.

6. The lip portion has a dust lip (16m) together with the main lip (16f), The rolling bearing according to claim 5, wherein the tip of the main lip (16f) and the tapered surface (13d) are in contact, and the dust lip (16m) is in non-contact or in contact with the stepped surface (13c) of the second raceway ring (13).

7. The rolling bearing according to claim 1, wherein the solid lubricant is a conductive lubricant having the conductive grease.

8. The rolling bearing according to claim 1, wherein the conductive substance contained in the conductive grease includes metal, carbon black, graphite, graphite, conductive carbon fiber, and ionic liquid.

9. A rolling bearing according to claim 1, used in motors, reducers, and transmissions.

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