Insulated bearing

Abstract

The present invention provides an insulated bearing in which the insulating layer between the outer ring and the housing shoulder is less likely to be degraded by wear particles. [Solution] The device comprises an inner ring 10, an outer ring 20, a plurality of rolling elements 30 arranged between them, and an insulating layer 40 overlapping the outer circumference and side surface of the outer ring 20. The inner circumference 43 of the lateral layer portion 42 of the insulating layer 40 that overlaps the side surface of the outer ring 20 has a shape that includes at least one inclined surface that is tilted radially outward by 5° or more toward the axially outward direction. The total width of at least one inclined surface relative to the total width of the inner circumference 43 of the lateral layer portion 42 is 1 / 2 or more of the total width of the inner circumference 43.

Description

Technical Field

[0006] , , , , , , , ,

[0005]

[0001] The present invention relates to a rolling bearing having an insulating layer laminated on the outer circumference and side surface of an outer ring to achieve insulation of the rolling bearing.

Background Art

[0002] When a rotating part is supported by a rolling bearing in a device using electricity, such as an electric motor or an e-Axle in which an electric motor and a speed reducer are integrated, a voltage may be applied to the rolling bearing. When electricity flows from the outer ring of the rolling bearing to the inner ring side or from the inner ring to the outer ring side due to this voltage, electric corrosion occurs at the contact portions between the rolling elements and the outer and inner rings of the rolling bearing.

[0003] To prevent such electric corrosion, conventionally, an insulating layer overlapping the outer circumference and side surface of the outer ring has been provided to insulate between the housing and the outer ring. The insulating layer is laminated on the outer ring by coating the outer ring with an insulating material such as ceramics by spraying, coating, etc., insert molding a resin onto the outer ring, or attaching a preformed resin part to the outer ring.

[0004] In particular, for the insulation between the outer ring and the housing shoulder, the creepage distance formed by the surface of the insulating material between them is important. To increase this creepage distance and strengthen the bond between the insulating layer and the outer ring, a circumferential groove portion is formed near the end of the inner circumference of the outer ring, and the insulating layer is also inserted into this circumferential groove portion, so that there is a rolling bearing in which the inner circumference of the insulating layer portion located between the outer ring and the housing shoulder is formed in a cylindrical surface shape with a predetermined width (Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In light of the above background, the problem that this invention aims to solve is to provide an insulated bearing in which the insulating performance of the insulating layer between the outer ring and the housing shoulder is less likely to be reduced by wear particles. [Means for solving the problem]

[0008] To solve the above problems, this invention adopts a configuration 1 for an insulating bearing comprising an inner ring, an outer ring, a plurality of rolling elements disposed between the outer ring and the inner ring, and an insulating layer overlapping the outer circumference and side surface of the outer ring, wherein the inner circumference of at least one of a pair of lateral layer portions overlapping the side surface of the outer ring has a shape that includes at least one inclined surface portion that is tilted radially outward by 5° or more toward the axial outward direction, and when the total width of the inner circumference of at least one of the pair of lateral layer portions is defined as L (mm) and the total width of the at least one inclined surface portion in relation to the total width L is defined as Lt (mm), the condition Lt ≥ 0.3L is satisfied.

[0009] According to the above configuration 1, the inner circumference of the lateral layer that overlaps the side surface of the outer ring is located between the outer ring and the housing shoulder when an insulated bearing is used, forming a creepage distance. If one or more inclined surfaces with an inclination angle of 5° or more radially outward toward the axially outward direction occupy more than half of the total width of the inner circumference of the lateral layer, then when an insulated bearing is used, oil will flow down more easily over the inner circumference of the lateral layer. As a result, wear particles are less likely to accumulate on the bottom of the inner circumference of the lateral layer. In addition, the creepage distance obtained by inclined surfaces with respect to the axial direction is longer than that when they extend axially, so even if wear particles accumulate on the inner circumference of the lateral layer, the insulation between the outer ring and the housing shoulder is less likely to be destroyed. These effects make it possible to prevent a decrease in the insulation performance between the outer ring and the housing shoulder.

[0010] In the above configuration 1, configuration 2 can be adopted, in which the inclination angle of the slope portion is set to 45° or less.

[0011] According to the above configuration 2, it becomes possible to ensure strength while avoiding an increase in the cross-sectional height of the lateral layer and avoiding thinning of the lateral layer near the side surface of the outer ring.

[0012] In the above configuration 1 or 2, configuration 3 can be adopted, in which at least one of the inclined surfaces is an inclined surface having curvature in a cross-section along the axial direction.

[0013] According to the above configuration 3, the creepage distance obtained in the slope portion having curvature in the cross-section along the axial direction is longer than that of the slope portion with a straight cross-section, making it possible to increase the creepage distance obtained on the inner circumference of the lateral layer portion.

[0014] In any one of the above configurations 1 to 3, configuration 4 can be adopted, in which the inner circumference of at least one of the pair of lateral layers has a plurality of the aforementioned sloping portions.

[0015] According to the above configuration 4, it becomes possible to make the creepage distance of the lateral layer longer.

[0016] In the above configuration 4, a configuration 5 can be adopted in which the inclination angle of the inclined surface located furthest inward in the axial direction among the plurality of inclined surfaces is set to be smaller than the inclination angles of the other inclined surfaces.

[0017] According to the above configuration 5, it becomes possible to avoid thinning of the lateral layer near the side surface of the outer ring.

[0018] In any one of the above configurations 1 to 5, configuration 6 can be adopted, in which the side surface of the outer ring has an end face portion located at one end of the total width of the outer ring and a chamfered portion that is continuous radially inward from the end face portion, the inner circumference of the lateral layer portion has an inner periphery that contacts the end face portion at a position radially outward from the chamfered portion, the chamfered portion is arc-shaped in cross-section along the axial direction, point O is defined as the center of curvature of the arc shape, point A is defined as the connection point between the arc shape and the end face portion, and point B is defined as the intersection point of a virtual axial line passing through point O and the end face portion, such that ∠AOB≦20° is satisfied.

[0019] According to the above configuration 6, the chamfered portion and the end face portion are continuous on the side surface of the outer ring without forming a sharp edge at the boundary (point B), making it possible to reduce the likelihood of discharge between the outer ring and the housing shoulder due to the edge effect.

[0020] In any one of the above configurations 1 to 6, configuration 7 can be adopted in which the insulating layer is integrated with the outer ring by insert molding, and the inner circumference of the lateral layer portion does not include an undercut shape that is shaded when viewed from the axial outside.

[0021] According to the above configuration 7, the inner circumference of the lateral layer is easily released from the mold, making it possible to prevent the formation of a gap between the side surface of the outer ring and the inner circumference of the lateral layer.

[0022] In the above-described configuration 7, the side surface of the outer ring has an end face portion located at one end of the entire width of the outer ring, and a shoulder face portion that extends radially outward at a position closer to the inner side in the axial direction than the end face portion. The inner circumference of the side layer portion extends from a position contacting the shoulder face portion to a position closer to the outer side in the axial direction than the end face portion. When the entire width of the inner circumference of at least one of the pair of side layer portions is defined as L (mm) and the width between the end face portion and the shoulder face portion is defined as s (mm), a configuration 8 in which (L / 2) ≤ s is satisfied can be adopted.

[0023] According to the above-described configuration 8, while suppressing the amount of deformation due to creep caused by the viscoelastic properties of the resin in a usage environment where an axial load is applied to the side layer portion, the entire width L of the inner circumference of the side layer portion can be expanded by utilizing the width s between the end face portion and the shoulder face portion of the outer ring, and the creepage distance obtained at the inner circumference of the side layer portion can be lengthened.

[0024] In the above-described configuration 7 or 8, the side surface of the outer ring has an end face portion located at one end of the entire width of the outer ring, and a shoulder face portion that extends radially outward at a position closer to the inner side in the axial direction than the end face portion. An undercut portion that appears as a shadow when viewed from the outer side in the axial direction is formed at a position closer to the inner side in the axial direction than the end face portion and closer to the outer side in the axial direction than the shoulder face portion of the inner circumference of the outer ring. A configuration 9 in which at least one of the pair of side layer portions is filled in the undercut portion can be adopted.

[0025] According to the above-described configuration 9, when the side layer portion is demolded, the side layer portion is caught by the undercut portion of the inner circumference of the outer ring, so that it is possible to prevent the formation of a gap between the side surface of the outer ring and the inner circumference of the side layer portion.

[0026] In any one of the above-described configurations from 7 to 9, the insulating layer does not include a weld, and at least one of the pair of side layer portions includes an annular end face portion machined by shaving on the side surface on the outer side in the axial direction of the side layer portion, and no machining by shaving is performed on the inner circumference of at least one of the pair of side layer portions. A configuration 10 can be adopted.

[0027] According to the above configuration 10, by insert molding in which a disk gate is arranged at a position axially opposed to the side surface of the outer ring, an insulating layer without a weld that becomes a fragile part is formed. At the same time, when demolding, the gate marks that annularly occur on the outer side surface in the axial direction of the side layer part are removed by machining to form an annular end face part with excellent flatness. Therefore, it becomes possible to abut the annular end face part against the housing shoulder to axially position the insulating bearing. On the other hand, by not machining the inner circumference of the side layer part, it becomes possible to prevent the formation of a gap between the inner circumference of the side layer part and the side surface of the outer ring due to the machining pressure.

Effect of the Invention

[0028] <0000t01>As described above, by adopting the above configuration 1, the present invention can provide an insulating bearing in which the performance of insulating between the outer ring and the housing shoulder by the insulating layer is not easily reduced by wear powder.

Brief Description of the Drawings

[0029] [Figure 1] Cross-sectional view showing the lower side of the insulating bearing according to the first embodiment of the present invention [Figure 2] Enlarged view showing the vicinity of the side layer part on the right side of the insulating layer in FIG. 1 [Figure 3] Partial cross-sectional view showing the vicinity of the side layer part of the insulating bearing according to the second embodiment of the present invention [Figure 4] Partial cross-sectional view showing the vicinity of the side layer part of the insulating bearing according to the third embodiment of the present invention [Figure 5] Partial cross-sectional view showing the vicinity of the side layer part of the insulating bearing according to the fourth embodiment of the present invention [Figure 6] Partial cross-sectional view showing the vicinity of the side layer part of the insulating bearing according to the fifth embodiment of the present invention [Figure 7] Partial cross-sectional view showing the vicinity of the side layer part of the insulating bearing according to the sixth embodiment of the present invention [Figure 8] Partial cross-sectional view showing a modified example of the shape of the outer ring of the insulating bearing shown in FIG. 7 [Figure 9] Partial cross-sectional view showing another modified example of the shape of the outer ring of the insulating bearing shown in FIG. 7

Mode for Carrying Out the Invention

[0030] An insulating bearing according to the first embodiment of this invention (hereinafter simply referred to as "this insulating bearing") will be described based on Figures 1 and 2 of the attached drawings.

[0031] This insulated bearing consists of an inner ring 10, an outer ring 20, a plurality of rolling elements 30 positioned between the inner ring 10 and the outer ring 20, and an insulating layer 40 that overlaps the outer circumference and sides of the outer ring 20.

[0032] The inner ring 10 is a bearing component having a raceway 11 formed on its outer circumference. The inner ring 10 is fitted onto the shaft S. The shaft S is, for example, a motor shaft in an e-Axle or the first stage shaft of a reduction gear. Note that each figure shows a cross-sectional view of the lower end of this insulated bearing when supporting a horizontal shaft S.

[0033] The outer ring 20 is a bearing component having a raceway 21 formed on its inner circumference. The outer ring 20 is positioned axially by a housing shoulder Hs provided in a bearing housing such as an e-Axle.

[0034] The rolling elements 30 are bearing components that roll along the raceways 11 and 21.

[0035] The inner ring 10, outer ring 20, and rolling elements 30 are each made of a metal such as steel.

[0036] The rolling elements 30 are balls. The raceways 11 and 12 are raceway grooves. The inner ring 10, the outer ring 20, and the multiple rolling elements 30 constitute a deep groove ball bearing. The inner ring 10 and the outer ring 20 are mirror-symmetric with respect to a virtual plane that bisects their total width (raceway width).

[0037] The outer circumference of the outer ring 20 is formed with an outer diameter surface 22 that defines the outer diameter of the outer ring 20, and an outer circumferential groove 23 that extends circumferentially with radial depth from the outer diameter surface 22. The outer diameter surface 22 is cylindrical in shape, extending in the circumferential and axial directions. The outer circumferential groove 23 is located in the center of the overall width of the outer ring 20. The outer diameter surface 22 is formed on one axial side and the other axial side of the outer ring 20 relative to the outer circumferential groove 23.

[0038] Here, the axial direction refers to the direction along the central axis of the outer ring 20 (not shown in the diagram; the same applies hereafter), the radial direction refers to the direction perpendicular to that central axis, and the circumferential direction refers to the direction along the circumference around that central axis. One axial side of the outer ring 20 refers to one half of the outer ring separated by a virtual plane that bisects the entire width of the outer ring 20, and the other axial side of the outer ring is the opposite half of the outer ring 20.

[0039] The side surface of the outer ring 20 has an end face portion 24 located at one end of the total width of the outer ring 20, and a circumferential groove portion 25 extending circumferentially with axial depth from the end face portion 24. Here, the side surface of the outer ring 20 refers to the portion exposed in the axial direction when one axial side or the other axial side of a single outer ring 20 (outer ring 20 without the insulating layer 40) is viewed from the axial outside. Furthermore, the axial outside refers to the side that is further in the axial direction from a virtual plane that bisects the total width of the outer ring 20.

[0040] The end face portion 24 is an annular planar shape extending in the radial and circumferential directions. The end face portion 24 is formed radially outward and radially inward relative to the side circumferential groove portion 25. Here, radially outward means the side that is farther from the central axis of the outer ring 20 in the radial direction, and radially inward means the side that is closer to the central axis of the outer ring 20 in the radial direction.

[0041] The insulating layer 40 has a circular layer portion 41 that overlaps the outer diameter surfaces 22 and outer peripheral groove portion 23 on both sides of the outer ring 20, and two lateral layer portions 42 that overlap the corresponding side surfaces of the outer ring 20. The insulating layer 40 is mirror-symmetric with respect to a virtual plane that bisects the entire width of the outer ring 20.

[0042] The insulating layer 40 is integrated with the outer ring 20 by insert molding in which the outer ring 20 is placed in a mold (not shown; the same applies hereinafter) and resin is injected around it.

[0043] The circular layer portion 41 defines the outer diameter of the insulating layer 40. The outer diameter of this insulating bearing coincides with the outer diameter of the circular layer portion 41.

[0044] The side layer portion 42 extends from the edge of the corresponding outer diameter surface 22 of the outer ring 20 to the middle of the corresponding end face portion 24 on the inner side in the radial direction in a cross section along the axial direction. Here, the cross section along the axial direction means a cross section within a virtual plane having the central axis of the outer ring 20 as one side. <000017३> The inner circumference 43 of the side layer portion 42 is composed of a cylindrical surface portion 44 extending in the circumferential direction and the axial direction, and a plurality of inclined surface portions 45, 46 inclined outward in the radial direction by 5° or more toward the outer side in the axial direction. The inner circumference 43 of the side layer portion 42 becomes an exposed surface that contacts the oil for lubricating this insulating bearing or the like. The inner circumference 43 of the side layer portion 42 does not include an undercut shape that becomes shaded when the side layer portion 42 is viewed from the outer side in the axial direction. Here, the inner circumference 43 of the side layer portion 42 means a portion that is exposed in the radial direction when the side layer portion 42 is viewed from the inner side in the radial direction.

[0046] The total width L (mm) of the inner circumference 43 of the side layer portion 42 coincides with the axial thickness where the side layer portion 42 overlaps the corresponding end face portion 24 of the outer ring 20. Since the entire outer circumference of the outer ring 20 is covered with the insulating layer 40, it is possible to ensure insulation between the outer circumference of the outer ring 20 and the inner circumference of the housing even if the radial thickness h where the circular layer portion 41 overlaps the outer diameter surface 22 of the outer ring 20 is set small. On the other hand, ensuring insulation between the end face portion 24 of the outer ring 20 and the housing shoulder Hs depends on the axial thickness (total width L of the inner circumference 43) where the side layer portion 42 overlaps the end face portion 24 of the outer ring 20, and thus is provided with the relationship of h < L. The total width of the outer ring 20 is set smaller than the total width of the inner ring 10, and the total width of the insulating layer 40 coincides with the total width of the inner ring 10.

[0047] Wear particles (not shown; the same applies hereafter) generated from mechanical parts such as gears flow together with the lubricating oil. Since wear particles have a higher specific gravity than the lubricating oil, they may accumulate in areas where the flow of the lubricating oil is stagnant. The inner circumference of each lateral layer 42 is an area where this flow is likely to stagnate, and if wear particles accumulate there, there is a risk that current will flow between the outer ring 20 and the housing shoulder Hs, making it impossible to ensure insulation. However, because the aforementioned slanted surfaces 45 and 46 are formed, each lateral layer 42 has a shape that makes it difficult for wear particles to accumulate.

[0048] An annular end face portion 47, located on the axially outer side of the lateral layer portion 42, is formed. The annular end face portion 47 is an annular plane extending in the circumferential and radial directions. Here, the axially outer side of the lateral layer portion 42 refers to the portion that is exposed in the axial direction when the lateral layer portion 42 is viewed from the axially outer side.

[0049] The relationship d1 of the inner diameter of the outer ring 20 < d2 of the inner diameter of the lateral layer portion 42 is satisfied. The axially inner edge of the cylindrical surface portion 44 is in contact with the corresponding end surface portion 24. Here, the axially inner side refers to the side that is closer in the axial direction to a virtual plane that bisects the entire width of the outer ring 20.

[0050] The cylindrical surface portion 44 is formed to prevent a wedge-shaped space from forming near the abutment between the mold and the end face portion 24 of the outer ring 20 during insert molding, thereby suppressing the pressure of the resin trying to enter the abutment and making it less likely for burrs to form on the lateral layer portion 42. The total width of the cylindrical surface portion 44 is set to, for example, 1 mm. In addition, since the mold seals the space between the outer ring 20 and the mold by sandwiching the end faces 24 on both sides of the outer ring 20 in the axial direction, it is necessary to ensure an exposed area on each side of the outer ring 20 where the lateral layer portion 42 does not overlap (in the illustrated case, a part of the radially inward end face portion 24). This exposed area should be an annular planar shape extending in the circumferential and radial directions, with a width of 1 mm or more in the radial direction.

[0051] Of the multiple inclined surfaces 45 and 46, the inclined surface 45 located furthest inward in the axial direction (hereinafter referred to as the "innermost inclined surface 45") is continuous with the cylindrical surface 44. Of the multiple inclined surfaces 45 and 46, the inclined surface 46 located furthest outward in the axial direction (hereinafter referred to as the "outermost inclined surface 46") is continuous with the annular end surface 47 and forms a chamfered portion connecting the innermost inclined surface 45 and the annular end surface 47.

[0052] The inclination angle θ that each of the inclined surfaces 45 and 46 makes radially outward toward the axial outward direction is set to be between 5° and 45°. This restriction on the inclination angle θ holds true at any position on each of the inclined surfaces 45 and 46. This angle θ is the angle between the line segment formed by connecting the points at both ends of each inclined surface in the axial direction and the line segment parallel to the axial direction in a cross section along the axial direction.

[0053] The total width Lt (mm) of the multiple sloped sections 45 and 46 on the inner circumference 43 of the lateral layer section 42 satisfies the condition Lt ≥ 0.3L.

[0054] If the inclination angle θ of each inclined surface 45, 46 is set to 5° or more, the speed at which oil flows down each inclined surface 45, 46 can be effectively increased. If such inclined surfaces 45, 46 are provided over a wide area such that they occupy more than half of the total width L of the inner circumference 43 of the lateral layer 42, the oil can be made to flow down actively over the inner circumference 43 of the lateral layer 42 when the insulating bearing is in use. As a result, wear particles are less likely to accumulate on the bottom of the inner circumference 43 of the lateral layer 42 (on the cross-section of the inner circumference 43 shown in Figure 1). On the other hand, if the inclination angle θ of each inclined surface 45, 46 that occupies more than half of the total width L of the inner circumference 43 of the lateral layer 42 is set to be greater than 45°, it becomes difficult to secure the thickness between the inner circumference 43 of the lateral layer 42 and the side surface of the outer ring 20 in the region close to the outer ring 20, which is undesirable.

[0055] Furthermore, the housing shoulder portion Hs only needs to be structured in such a way that it does not block the flow of oil from the inner circumference 43 of the lateral layer portion 42. For example, the inner diameter d3 of the housing shoulder portion Hs should be set to be equal to or greater than the maximum inner diameter of the inner circumference 43 of the lateral layer portion 42.

[0056] Of the multiple inclined surfaces 45 and 46, the inclination angle θ of the innermost inclined surface 45 is set to be smaller than the inclination angle θ of the other inclined surfaces 46. This makes it easier to secure the axial thickness that the lateral layer 42 has between the inner circumference 43 and the side surface of the outer ring 20 in a region close to the outer ring 20.

[0057] On the other hand, the outermost sloped portion 46 also serves as a chamfered portion to prevent corner cracking and chipping of the lateral layer portion 42. For this reason, the inclination angle θ of the outermost sloped portion 46 is set to be greater than the inclination angle θ of the innermost sloped portion 45.

[0058] Of the multiple inclined surfaces 45 and 46, the overall width of the innermost inclined surface 45 is set to be larger than the overall width of the other inclined surfaces 46. This allows the innermost inclined surface 45, which has a relatively small inclination angle θ, to be set to be relatively wide, making it easier to secure the axial thickness that the lateral layer 42 has between the inner circumference 43 and the side surface of the outer ring 20 in the region closer to the outer ring 20.

[0059] Each of the inclined surfaces 45 and 46 has a shape with curvature in its cross-section along the axial direction. For example, it is possible to keep the cylindrical surface 44 and the outermost inclined surface 46 as they are and change the innermost inclined surface 45 to have a straight cross-section, but using the innermost inclined surface 45, which has a curved cross-section, results in a longer length of the innermost inclined surface 45 in the cross-section compared to the case where it has a straight cross-section. In other words, the creepage distance obtained on the inner circumference 43 between the outer ring 20 and the housing shoulder Hs becomes longer. In the illustration, the case where the center of curvature (not shown) of each inclined surface 45, 46 is set to a position radially outward relative to the inclined surfaces 45, 46 is shown as a convex curved surface, but it is also possible to change it to a concave curved surface where the center is set to a position radially inward.

[0060] The insulating layer 40 does not contain welds. Here, a weld refers to a weak area where the resin flowing within the mold cavity merges and solidifies. Such an insulating layer 40 can be insert molded by pressing the mold against the parts of the outer ring 20 that do not overlap with the lateral layer 42, and by making the mold's gate structure a disc gate that faces axially on one of the outer ring 20's sides.

[0061] The side surface of the lateral layer portion 42 of the insulating layer 40 released from the mold has a disk gate and sheared gate marks, resulting in a rough surface with a radial width around its entire circumference. By removing these gate marks through appropriate machining such as turning and grinding, the annular end face portion 47 of one side of the lateral layer portion 42 is formed into the aforementioned annular planar shape. Therefore, the annular end face portion 47 with excellent flatness can be abutted against the housing shoulder portion Hs in the axial direction to position the insulating bearing in the axial direction.

[0062] On the other hand, the inner circumference 43 of the lateral layer portion 42 is a part where gate marks are not formed, or even if gate marks are formed, it does not abut against the housing shoulder portion Hs. For this reason, the inner circumference 43 of the lateral layer portion 42 is not machined. Machining the inner circumference 43 of the lateral layer portion 42 after demolding would apply a large radial stress to the lateral layer portion 42 due to the machining pressure, making it more susceptible to damage such as peeling of the lateral layer portion 42 from the side of the outer ring 20 or cracking of the lateral layer portion 42, which is undesirable.

[0063] As the resin forming the insulating layer 40, for example, one with a dielectric strength of 500 V / mm or more can be used. Here, dielectric strength refers to the value measured by a test method compliant with the ASTM D149 standard Step-by-step Test.

[0064] Furthermore, as the resin forming the insulating layer 40, for example, one having a surface current resistance index of 600V or higher can be used. Here, the surface current resistance index refers to the CTI value measured in a tracking resistance test in accordance with the IEC60112 standard. Examples of such resins include polyphenylene sulfide (PPS) and polyphthalamide (PPA).

[0065] Furthermore, a fiber-reinforced resin may be used as the resin forming the insulating layer 40. The fiber-reinforced resin is obtained by dispersing non-conductive fiber fillers such as glass fibers and polyamide fibers in a matrix resin at a desired blending ratio. The aforementioned PPA or the like can be used as the matrix resin.

[0066] This insulated bearing is as described above, and comprises an inner ring 10, an outer ring 20, a plurality of rolling elements 30 arranged between the outer ring 20 and the inner ring 10, and an insulating layer 40 overlapping the outer circumference and side surface of the outer ring 20. In particular, the inner circumference 43 of the lateral layer portion 42 of the insulating layer 40 that overlaps the side surface of the outer ring 20 includes at least one inclined portion 45, 46 that is inclined radially outward by 5° or more toward the axial outward direction. When the total width of the inner circumference 43 of the lateral layer portion 42 is defined as L (mm) and the total width of at least one inclined portion 45, 46 within that total width L is defined as Lt (mm), the condition Lt ≥ 0.3L is satisfied. As a result, when this insulated bearing is in use, oil can easily flow down the inner circumference 43 of the lateral layer portion 42 that is located between the outer ring 20 and the housing shoulder Hs and forms a creepage distance, and wear particles are less likely to accumulate on the bottom of the inner circumference 43 of the lateral layer portion 42. Furthermore, the creepage distance obtained from the inclined surfaces 45 and 46, which are tilted at an angle of 5° or more with respect to the axial direction, is longer than that obtained when the surface is cylindrical and extends in the axial direction. Therefore, even if wear particles accumulate on the inner circumference 43 of the lateral layer 42, the insulation between the outer ring 20 and the housing shoulder Hs is less likely to be destroyed. Due to these effects, it is possible to prevent a decrease in the insulation performance between the outer ring 20 and the housing shoulder Hs obtained from the lateral layer 42. Thus, this insulating bearing can provide an insulating bearing in which the insulating performance between the outer ring 20 and the housing shoulder Hs by the insulating layer 40 is less likely to be reduced by wear particles. It is preferable that Lt ≥ 0.5L is satisfied, as this makes it easier to secure a greater creepage distance and further improves the effect of preventing the accumulation of wear particles.

[0067] Furthermore, in this insulated bearing, the inclination angle of the inclined surfaces 45 and 46 is set to 45° or less, which makes it possible to avoid increasing the cross-sectional height of the lateral layer 42 within the cross-section along the axial direction, while also avoiding thinning of the lateral layer 42 near the side surface of the outer ring 20, thereby ensuring the strength of the lateral layer 42.

[0068] Furthermore, in this insulated bearing, since the inclined surfaces 45 and 46 have curvature in a cross-section along the axial direction, the creepage distance obtained from the inclined surfaces 45 and 46 with curvature is longer than that of an inclined surface with a straight cross-section, thus increasing the creepage distance obtained on the inner circumference 43 of the lateral layer 42.

[0069] Furthermore, because the inner circumference 43 of the lateral layer 42 has multiple inclined surfaces 45 and 46, the inner circumference 43 of the lateral layer 42 extends in a complex linear pattern in a cross-section along the axial direction. This allows for a longer creepage distance on the inner circumference 43 of the lateral layer 42 compared to a single inclined surface.

[0070] Furthermore, in this insulated bearing, the inclination angle θ of the inclined surface 45 located furthest in the axial direction among the multiple inclined surfaces 45 and 46 is set to be smaller than the inclination angle θ of the other inclined surfaces 46, thereby avoiding thinning of the lateral layer 42 near the side surface of the outer ring 20.

[0071] Furthermore, in this insulated bearing, the insulating layer 40 is integrated with the outer ring 20 by insert molding, and the inner circumference 43 of the lateral layer 42 does not include an undercut shape that would be hidden when viewed from the axial outside. As a result, the inner circumference 43 of the lateral layer 42 is easily released from the mold, thus preventing the formation of a gap between the side surface of the outer ring 20 and the inner circumference 43 of the lateral layer 42. Naturally, the absence of an undercut shape in the inner circumference 43 of the lateral layer 42, which would easily trap wear particles, is also advantageous in preventing the aforementioned decrease in insulation performance.

[0072] Furthermore, this insulated bearing has an insulating layer 40 that does not contain welds, and the lateral layer 42 includes an annular end face 47 machined on the axially outer side surface of the lateral layer 42, and the inner circumference 43 of the lateral layer 42 is not machined. As a result, the insulating layer 40 is made without welds, which would be a weak point, by insert molding in which the disc gate is positioned axially opposite to the side surface of the outer ring 20, and the gate marks that form annularly on the axially outer side surface of the lateral layer 42 during demolding are removed by machining to form an annular end face 47 with excellent flatness. Therefore, the annular end face 47 can be abutted against the housing shoulder Hs to position the insulated bearing axially, and on the other hand, by not machining the inner circumference 43 of the lateral layer 42, it is possible to prevent the formation of a gap between the inner circumference 43 of the lateral layer 42 and the side surface of the outer ring 20 due to machining pressure.

[0073] In the following embodiments, only the differences from the first embodiment will be described, and the same reference numerals will be used to indicate components corresponding to those in the first embodiment.

[0074] A second embodiment of this invention is shown in Figure 3. The inner circumference 43 of the lateral layer portion 42 according to the second embodiment has a plurality of slanted portions 45, 46 that extend in a straight line in cross-section.

[0075] A third embodiment of this invention is shown in Figure 4. The side surface of the outer ring 20 according to the third embodiment further has a shoulder surface 26 that extends radially outward at a position closer to the axially inward side than the end surface 24 located at one end of the total width of the outer ring 20.

[0076] The outer ring 20 does not have a circumferential groove formed on its side surface to reinforce the integration of the insulating layer 40 with the outer ring 20. Instead, an undercut portion 27 is formed on the inner circumference of the outer ring 20 at a position that is axially inward from the end face portion 24 and axially outward from the shoulder surface portion 26, and the lateral layer portion 42 overlaps the end face portion 24, the undercut portion 27, and the shoulder surface portion 26.

[0077] The undercut portion 27 is groove-shaped and extends around the entire circumference, and is continuous with the shoulder portion 26 on the axially inward side. There is a small chamfer between the groove edge on the axially outward side of the undercut portion 27 and the end face portion 24. During insert molding of the insulating layer 40, the resin that forms the lateral layer portion 42 is filled into the undercut portion 27.

[0078] The inner circumference 43 of the lateral layer 42 extends from a position in contact with the shoulder surface 26 to a position further axially outward than the end surface 24. The total width L of the inner circumference 43 of the lateral layer 42 is increased by the width s (mm) between the end surface 24 and the shoulder surface 26.

[0079] The total width of the cylindrical surface portion 44 is set to a size of less than s / 2. The innermost inclined surface portion 45 extends to a position further axially outward than the end surface portion 24. The outermost inclined surface portion 46 extends in a straight line in cross-section. The combined width of the inclined surfaces 45 and 46 in relation to the total width L of the inner circumference 43 of the lateral layer portion 42 is set to be greater than the width s. The thickness between the groove edge on the axially outward side of the undercut portion 27 and the inner circumference 43 of the lateral layer portion 42 is determined by the innermost inclined surface portion 45, which has a relatively small incline, making it easy to secure the thickness of the lateral layer portion 42 in this area.

[0080] In the third embodiment, the insulating bearing has an outer ring 20 with an end face portion 24 on its side surface and a shoulder portion 26 extending radially outward at a position axially inward from the end face portion 24. An undercut portion 27 is formed on the inner circumference of the outer ring 20 at a position axially inward from the end face portion 24 and axially outward from the shoulder portion 26, and the lateral layer portion 42 is filled into the undercut portion 27. As a result, when the inner circumference 43 of the lateral layer portion 42 is demolded, the lateral layer portion 42 catches axially on the undercut portion 27 of the inner circumference of the outer ring 20, thereby preventing the formation of a gap between the side surface (shoulder surface portion 26) of the outer ring 20 and the inner circumference 43 of the lateral layer portion 42. Furthermore, by utilizing the width s between the end surface portion 24 and the shoulder surface portion 26 of the outer ring 20, the total width L of the inner circumference 43 of the lateral layer portion 42 can be increased, thereby increasing the creepage distance obtained on the inner circumference 43 of the lateral layer portion 42.

[0081] A fourth embodiment of this invention is shown in Figure 5. Since the fourth embodiment is a further modification of the third embodiment, only the changes from the third embodiment will be described here. The inner circumference 43 of the lateral layer portion 42 according to the fourth embodiment has a plurality of slanted portions 45, 46 that extend in a straight line in cross-section. The same effects and advantages as the third embodiment can be obtained in the fourth embodiment as well.

[0082] A fifth embodiment of this invention is shown in Figure 6. Since the fifth embodiment is a further modification of the fourth embodiment, only the changes from the fourth embodiment will be described here. In the fifth embodiment, the width s between the end face portion 24 and the shoulder portion 26 of the outer ring 20 is set to be larger than the width s of the fourth embodiment. For this reason, the end face portion 24 is formed at a position closer to the axially outward position compared to the fourth embodiment, and the undercut portion 27 is expanded axially outward. Due to these changes, the relationship between the width s and the total width L satisfies (L / 2) ≤ s. Because the insulated bearing according to the fifth embodiment satisfies (L / 2) ≤ s, in addition to the same effects as the third embodiment, it can suppress the amount of deformation due to creep caused by the viscoelastic properties of the resin in an operating environment where an axial load is applied to the lateral layer portion 42. In addition, in the fifth embodiment as well, it is possible to make the inclined portions 45 and 46 into a cross-sectional curve shape as appropriate.

[0083] A sixth embodiment of this invention is shown in Figure 7. The sixth embodiment is a further modification of the first embodiment. The side surface of the outer ring 20 according to the sixth embodiment further has a chamfered portion 28 that is continuous in the radial direction with respect to the end face portion 24 located at one end of the total width of the outer ring 20.

[0084] The chamfered portion 28 is arc-shaped in cross-section along the axial direction.

[0085] The inner circumference 43 of the lateral layer portion 42 of the insulating layer 40 has an inner peripheral edge 48 that contacts the end face portion 24 at a position radially outward from the chamfered portion 28.

[0086] When the center of curvature of the arc shape of the chamfered portion 28 in a cross section along the axial direction is defined as point O, the connection point between the arc shape and the end face portion 24 is defined as point A, and the intersection point of the virtual axial line passing through point O and the end face portion 24 is defined as point B, the condition ∠AOB≦20° is satisfied. As a result, in the insulated bearing according to the sixth embodiment, the chamfered portion 28 and the end face portion 24 are continuous on the side surface of the outer ring 20 without forming a sharp edge at the boundary (point B), so that discharge between them and the housing shoulder portion Hs (see Figure 1) due to the edge effect can be made less likely.

[0087] Furthermore, the smaller ∠AOB becomes, the less likely the boundary between the chamfered portion 28 and the end face portion 24 is to become an edge. For example, setting ∠AOB to 10° as shown in Figure 8 can further enhance the aforementioned discharge generation suppression effect, and ultimately, it is best to set ∠AOB to 0° as shown in Figure 9.

[0088] Furthermore, since the edge relaxation of the arc-shaped chamfered portion 28 and the end face portion 24 is important, the outer ring shape radially inward from the chamfered portion 28 is not particularly limited, and other chamfered portions may be formed radially inward from the chamfered portion 28, and these other chamfered portions can be made, for example, arc-shaped in cross-section or C-shaped.

[0089] Furthermore, it is preferable that the radial distance between point B and the inner peripheral edge 48 be 1 mm or more in order to secure an area for pressing the mold against the end face portion 24.

[0090] Furthermore, the method for processing the chamfered portion 28 and the end face portion 24 does not need to be the same. For example, the end face portion 24 may be finished by grinding, while the chamfered portion 28 may be formed by turning.

[0091] In the embodiments described above, examples were shown in which multiple sloped sections 45 and 46 were formed on the inner circumference 43 of the lateral layer section 42. However, it is possible to set the total number of sloped sections included on the inner circumference of the lateral layer section to just one, or to set it to three or more, and to appropriately select whether each sloped section has a straight or curved cross-section.

[0092] Furthermore, in the embodiments described above, examples were given in which insulating layers are superimposed on both sides of the outer ring, allowing for insulation between the outer ring and the housing shoulder regardless of which side abuts against the housing shoulder. However, there may be operating environments where insulating only one side of the outer ring is sufficient. To create an insulated bearing suitable for such operating environments, it is not necessary to superimpose the insulating layer on both sides of the outer ring; it is possible to change to an insulating layer having the lateral layer on only one side.

[0093] Furthermore, in the embodiments described above, an example was shown in which an outer circumferential groove was formed on the outer circumference of the outer ring, and the circular layer portion of the insulating layer was filled into the outer circumferential groove to strengthen the integration of the insulating layer and the outer ring. However, it is also possible to omit the outer circumferential groove of the outer ring.

[0094] Furthermore, although the embodiments described above show a deep groove ball bearing configured with an inner ring 10, an outer ring 20, and a plurality of rolling elements 30, it is also possible to change to other bearing types such as angular contact ball bearings, self-aligning bearings, and cylindrical roller bearings.

[0095] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications in the sense and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0096] 10 Inner Ring 20 Outer ring 24 End section 26 Shoulder area 27 Undercut section 28 Chamfered section 30 Rolling elements 40 Insulating layer 42 Lateral layer 43 Inner circumference 45, 46 Sloping section 47 Annular end face 48 Inner periphery

Claims

1. In an insulated bearing comprising an inner ring, an outer ring, a plurality of rolling elements disposed between the outer ring and the inner ring, and an insulating layer overlapping the outer circumference and side surface of the outer ring, Of the insulating layer, at least one of the pair of lateral layer portions that overlap the side surface of the outer ring has a shape in which the inner circumference of at least one inclined surface portion is tilted radially outward by 5° or more toward the axially outward direction. An insulating bearing characterized in that, when the total width of the inner circumference of at least one of the pair of lateral layers is defined as L (mm), and the total width of the at least one inclined surface portion within that total width L is defined as Lt (mm), the condition Lt ≥ 0.3L is satisfied.

2. The insulating bearing according to claim 1, wherein the inclination angle of the inclined surface portion is set to 45° or less.

3. The insulating bearing according to claim 1 or 2, wherein at least one of the inclined surfaces has curvature in a cross-section along the axial direction.

4. The insulating bearing according to claim 1 or 2, wherein the inner circumference of at least one of the pair of lateral layers has a plurality of the inclined surfaces.

5. The insulating bearing according to claim 4, wherein the inclination angle of the inclined portion located furthest inward in the axial direction among the plurality of inclined portions is smaller than the inclination angles of the other inclined portions.

6. The side surface of the outer ring has an end face portion located at one end of the total width of the outer ring, and a chamfered portion that is continuous radially inward from the end face portion. The inner circumference of at least one of the pair of lateral layers has an inner periphery that contacts the end face at a position radially outward from the chamfered portion, The chamfered portion is arc-shaped in cross-section along the axial direction, The insulating bearing according to claim 1 or 2, wherein when the center of curvature of the arc is defined as point O, the connection point between the arc and the end face is point A, and the intersection point of the virtual axial line passing through point O and the end face is point B, the angle ∠AOB ≤ 20° is satisfied.

7. The insulating layer is integrated with the outer ring by insert molding. The insulating bearing according to claim 1 or 2, wherein the inner circumference of the lateral layer portion does not include an undercut shape that is shaded when viewed from the axial outside.

8. The side surface of the outer ring has an end face portion located at one end of the total width of the outer ring, and a shoulder portion extending radially outward at a position closer to the axially inward side than the end face portion. The inner circumference of the lateral layer extends from a position in contact with the shoulder surface to a position that is axially outward from the end surface. The insulating bearing according to claim 7, wherein when the total width of the inner circumference of at least one of the pair of lateral layers is defined as L (mm) and the width between the end face and the shoulder face is defined as s (mm), the condition (L / 2) ≤ s is satisfied.

9. The side surface of the outer ring has an end face portion located at one end of the total width of the outer ring, and a shoulder portion extending radially outward at a position closer to the axially inward side than the end face portion. An undercut portion is formed on the inner circumference of the outer ring at a position that is axially inward from the end face portion and axially outward from the shoulder surface portion, which is shaded when viewed from the axially outward side. The insulating bearing according to claim 7, wherein at least one of the pair of lateral layers is filled in the undercut portion.

10. The insulating layer does not contain welds, At least one of the pair of lateral layers includes an annular end face portion machined from the axially outer side surface of the lateral layer, The insulating bearing according to claim 7, wherein at least one of the pair of lateral layers has not been machined.

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