Rolling bearing and method of manufacturing the same

Abstract

To suppress electrolytic corrosion of a rolling bearing without performing insert molding of resin to a bearing ring.SOLUTION: A resin part 50 for covering an outer peripheral surface 12 as a peripheral surface on the bearing outside of the bearing ring 10 is formed of a pair of annular members 51 and 52. The annular members 51 and 52 are welded to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rolling bearing provided with a resin portion covering the inner or outer peripheral surface of a raceway ring, and to a method for manufacturing the same. [Background technology]

[0002] When rolling bearings are used to support rotating parts in electrical devices such as electric motors or e-axles that integrate an electric motor and a reducer, voltage may be applied to the rolling bearings. If this voltage causes electricity to flow from the outer ring to the inner ring of the rolling bearing, or from the inner ring to the outer ring, electrolytic corrosion occurs at the contact points between the rolling elements of the rolling bearing and the outer or inner ring.

[0003] One measure to suppress this electrolytic corrosion is to insert-mold a resin part into the raceway ring to cover the circumferential surface of the raceway ring on the outside of the bearing (the inner circumferential surface in the case of an inner ring, and the outer circumferential surface in the case of an outer ring) (see, for example, Patent Document 1). When the rolling bearing is installed between a shaft and a housing, the resin part is interposed between the circumferential surface of the raceway ring on the outside of the bearing and the corresponding shaft or housing. This provides insulation between the circumferential surface of the raceway ring on the outside of the bearing and the shaft or housing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3068311 Summary of the Invention [Problem to be solved by the invention]

[0005] In this insert molding, it is necessary to integrate the resin and the raceway so that the resin portion does not come off the raceway when the rolling bearing is assembled. For this reason, not only is a resin portion molded to cover the circumferential surface of the raceway on the outer side of the bearing, but also a resin portion that covers the width surface extending radially between the inner and outer circumferential surfaces, and a resin filling portion that fits into a circumferential groove on the circumferential surface on the outer side of the bearing.

[0006] However, when a resin portion is formed by insert molding, it is necessary to mask and clean the raceway surface to prevent dust from adhering to it during post-processing such as removing gate marks after molding, which increases costs.

[0007] In view of the above background, an object of the present invention is to suppress electrolytic corrosion of a rolling bearing without insert molding a resin into the raceway. [Means for solving the problem]

[0008] As a first means for solving the above problems, the present invention employs Configuration 1, which is a rolling bearing comprising a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway, wherein the peripheral surface of the first raceway on the outer side of the bearing is covered with a resin portion, wherein the resin portion is formed by a pair of annular members fitted together to sandwich the first raceway in the axial direction, and the annular members are welded to each other.

[0009] According to the above-mentioned configuration 1, the resin portion is formed by a pair of annular members that are mating components, so the resin portion is formed without insert molding. Also, the annular members that sandwich the first raceway ring in the axial direction are welded to each other, so the pair of annular members are integrated with the first raceway ring so as not to come off the first raceway ring, without insert molding. Therefore, the resin portion provides insulation between the circumferential surface of the first raceway ring on the outer side of the bearing and the corresponding shaft or housing, making it possible to suppress electrolytic corrosion of the rolling bearing.

[0010] In the above configuration 1, configuration 2 can be adopted in which an axial gap is formed between the annular members, and a welded portion is formed by melting the opposing portions of the annular members and allowing them to flow into the axial gap.

[0011] According to the above configuration 2, the welding cross section between the annular members can be expanded in the circumferential direction within the axial gap, thereby strengthening the joining between the annular members.

[0012] In the above configuration 1 or 2, a configuration 3 can be adopted in which the first annular member includes a first step portion having a step that is open toward one radial side and one axial side, and the second annular member includes a second step portion having a step that is open toward one radial side and another axial side at a position axially opposite to the first step portion, and a welded portion is formed by melting only the first step portion and the second step portion.

[0013] According to the above-mentioned configuration 3, the first step portion of the first annular member and the second step portion of the second annular member, which are fitted onto the outer peripheral surface of the first raceway to form a resin portion, are adjacent to each other in the axial direction with a radial depth, and only these first step portion and second step portion are welded together. Therefore, even if a burr is formed in the welded portion, it can be prevented from protruding from the first step portion and the second step portion, eliminating the need for deburring.

[0014] In any one of the above configurations 1 to 3, a configuration 4 can be adopted in which the peripheral surface on the outer side of the bearing includes a recessed portion having a radially recessed shape at a position overlapping the pair of annular members, and a welded portion is formed by melting the recessed portion in the pair of annular members and flowing it into the recessed portion.

[0015] According to the above configuration 4, the welding cross section of the annular members can be expanded in the radial direction within the recessed portion, thereby strengthening the joining of the annular members.

[0016] In any one of the above configurations 1 to 4, configuration 5 can be adopted, in which each annular member is formed so as to cover the entire surface of the corresponding side surface portion extending between the inner and outer peripheral surfaces of the first bearing ring.

[0017] According to the above configuration 5, even in an environment where an annular member covering the side portion of the first bearing ring is positioned by axially butting it against a corresponding mechanical element, the corresponding mechanical element and the first bearing ring can be insulated from each other.

[0018] In any one of the above configurations 1 to 5, a configuration 6 can be adopted in which the first annular member has a first cylindrical portion overlapping one axial end side of the circumferential surface on the outer side of the bearing and a first flange portion overlapping a width face on one axial end side of the first raceway ring, the second annular member has a second cylindrical portion overlapping the other axial end side of the circumferential surface on the outer side of the bearing and a second flange portion overlapping a width face on the other axial end side of the first raceway ring, and a first corner portion or a second corner portion connecting the first cylindrical portion or the second cylindrical portion to the corresponding first flange portion or the second flange portion has a shape recessed in the axial direction from the corresponding first flange portion or the second flange portion.

[0019] According to the above-mentioned configuration 6, the stress at the first corner or the second corner can be reduced, thereby preventing cracks at the corner.

[0020] As a second means for solving the above-mentioned problems, the present invention employs Configuration 7, which is a rolling bearing comprising a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway, wherein the circumferential surface of the first raceway on the outer side of the bearing is covered with a resin part, wherein the resin part is formed by one or more annular members fitted onto the circumferential surface on the outer side of the bearing, the circumferential surface on the outer side of the bearing includes a recessed portion having a radially recessed shape in each region overlapping the annular members, and a molten portion is formed by melting a portion of the annular member located above the recessed portion and allowing it to flow into the recessed portion.

[0021] According to the above-mentioned configuration 7, the resin portion is formed by one or more annular members fitted to the circumferential surface on the outer side of the bearing, and a molten portion is formed by melting and flowing into the recessed portion of the circumferential surface of the annular member on the outer side of the bearing, so that each annular member forming the resin portion is integrated with the first raceway so as not to come off from the first raceway without insert molding of resin into the first raceway. Therefore, the resin portion provides insulation between the circumferential surface on the outer side of the bearing of the first raceway and the corresponding shaft or housing, making it possible to suppress electrolytic corrosion of the rolling bearing.

[0022] In the above-mentioned configuration 7, a configuration 8 can be adopted in which the annular member has a cylindrical portion overlapping the peripheral surface on the outer side of the bearing and a flange portion overlapping the width surface on one axial end side or the width surface on the other axial end side of the first bearing ring.

[0023] According to the above-mentioned configuration 8, the flange portion of the annular member is sandwiched between the corresponding width surface of the first raceway and the corresponding mechanical element, thereby achieving insulation between these width surfaces and the mechanical element and eliminating the concern that the annular member will separate axially from the first raceway while the rolling bearing is in use.

[0024] In order to obtain the rolling bearing according to configuration 1 above, the present invention employs configuration 9, which is a method for manufacturing a rolling bearing comprising a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway, and in which the circumferential surface of the first raceway on the outer side of the bearing is covered with a resin portion, characterized in that the resin portion is formed by a pair of annular members that sandwich the first raceway in the axial direction, and the annular members are welded to each other.

[0025] By adopting configuration 10, which is a manufacturing method for a rolling bearing according to configuration 9, in which the first annular member is fitted onto the circumferential surface of the first raceway outside the bearing from one axial end side, and the second annular member is fitted onto the circumferential surface of the first raceway outside the bearing from the other axial end side, the resin portion is formed and an axial gap is formed between the annular members, and a welded portion is formed by melting the opposing portions of the annular members and allowing the melted portions to flow into the axial gap, the rolling bearing according to configuration 2 above can be obtained.

[0026] By employing configuration 11, which is a manufacturing method for a rolling bearing according to configuration 9 or 10, in which a first annular member is used that includes a first step portion having a step that is open toward one radial side and one axial side, and a second annular member is used that includes a second step portion that is open toward one radial side and the other axial side at a position axially opposite to the first step portion, and a welded portion is formed by melting only the first step portion and the second step portion, a rolling bearing according to configuration 3 can be obtained.

[0027] The rolling bearing according to configuration 4 above can be obtained by employing configuration 12, which is a method for manufacturing a rolling bearing according to any one of configurations 9 to 11 above, in which the first bearing ring includes a recessed portion having a radially recessed shape at a position where the circumferential surface on the outer side of the bearing overlaps with the pair of annular members, and a weld is formed by melting the recessed portion in the pair of annular members and allowing it to flow into the recessed portion.

[0028] In order to obtain the rolling bearing according to configuration 7 above, the present invention employs configuration 13, which is a method for manufacturing a rolling bearing comprising a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway, and wherein the circumferential surface of the first raceway on the outer side of the bearing is covered with a resin portion, the resin portion is formed by fitting one or more annular members to the circumferential surface on the outer side of the bearing, the first raceway to which the one or more annular members are fitted includes recessed portions having a radially recessed shape in each area of ​​the circumferential surface on the outer side of the bearing that overlaps with the annular member, and a molten portion is formed by melting the portion of the annular member located above the recessed portion and flowing it into the recessed portion.

[0029] By adopting configuration 14, which is the method for manufacturing a rolling bearing according to configuration 13, in which the annular member has a cylindrical portion that overlaps the peripheral surface of the first raceway ring on the outer side of the bearing, and a flange portion that overlaps the width face of the first raceway ring on one axial end side or the width face of the other axial end side, the rolling bearing according to configuration 8 can be obtained. [Effects of the Invention]

[0030] As described above, by adopting the above configuration 1, 7, 9 or 13, the present invention can suppress electrolytic corrosion of the rolling bearing without insert molding of resin into the raceway ring. [Brief explanation of the drawings]

[0031] [Figure 1] FIG. 1 is a longitudinal sectional front view showing a rolling bearing according to a first embodiment of the present invention; [Figure 2] Longitudinal side view of line II-II in Figure 1 [Figure 3] Figure 1: Plan view of the rolling bearing [Figure 4] A perspective view of the rolling bearing of Figure 1 [Figure 5] FIG. 5 is a perspective view showing a welding process of the pair of annular members shown in FIG. [Figure 6] Cross-sectional view showing the rolling bearing in Figure 1 in use [Figure 7] FIG. 10 is a longitudinal sectional front view showing a rolling bearing according to a second embodiment of the present invention; [Figure 8] Enlarged view of the corner of the annular member in Figure 7 [Figure 9] An enlarged view of the protrusion of the annular member in Figure 7. [Figure 10] An enlarged view of the vicinity of the welded portion of the pair of annular members shown in FIG. 7. [Figure 11] A longitudinal cross-sectional side view of the rolling bearing taken along line XI-XI in Figure 7. [Figure 12] A perspective view of the rolling bearing of FIG. [Figure 13] FIG. 13 is a perspective view showing a welding process of the pair of annular members shown in FIG. 12; [Figure 14] FIG. 10 is a longitudinal sectional front view showing a rolling bearing according to a third embodiment of the present invention; [Figure 15] FIG. 10 is a longitudinal sectional front view showing a rolling bearing according to a fourth embodiment of the present invention. [Figure 16] 16 is a perspective view of the rolling bearing of FIG. 15; [Figure 17] FIG. 10 is a longitudinal sectional front view showing a rolling bearing according to a fifth embodiment of the present invention. [Figure 18] 18 is a perspective view of the rolling bearing of FIG. 17; DETAILED DESCRIPTION OF THE INVENTION

[0032] As an example of the first aspect of the present invention, a rolling bearing according to a first embodiment will be described with reference to the accompanying drawings, FIGS. 1 to 6. FIG.

[0033] The rolling bearing 1 shown in Figure 1 comprises a first raceway 10, a second raceway 20, a plurality of rolling elements 30 arranged between the first raceway 10 and the second raceway 20, a retainer 40 that holds the plurality of rolling elements 30, and a pair of annular members 51, 52 fitted to the first raceway 10.

[0034] The first bearing ring 10 is a bearing component having, seamlessly, an inner peripheral surface 11, an outer peripheral surface 12, a width surface 13a at one axial end that is located on one end (the right end in FIG. 1) of both ends that define the bearing ring width of the first bearing ring 10 and extends radially, and a width surface 13b at the other axial end that is located on the opposite axial end (the left end in FIG. 1) and extends radially. The second bearing ring 20 is similar.

[0035] Here, the direction along the central axis of the first bearing ring 10 is referred to as the “axial direction,” the direction perpendicular to the central axis is referred to as the “radial direction,” and the direction along the circumference centered on the central axis is referred to as the “circumferential direction.” The axial direction corresponds to the left-right direction in FIG.

[0036] The first bearing ring 10 in the illustrated example is the outer ring. Of the inner peripheral surface 11 and outer peripheral surface 12 of the first bearing ring 10, the inner peripheral surface 11 is the peripheral surface on the inside of the bearing and includes the raceway 11a, while the opposite outer peripheral surface 12 is the peripheral surface on the outside of the bearing and does not include the raceway.

[0037] The second bearing ring 20 has an inner peripheral surface 21 and an outer peripheral surface 22, of which the outer peripheral surface 22 is an inner ring including a raceway 22a.

[0038] The outer peripheral surface 12 of the first bearing ring 10 on the outer side of the bearing is composed of an outer diameter surface 12a extending in the circumferential direction and chamfers 12b formed between the outer diameter surface 12a and each of the width surfaces 13a, 13b. The outer diameter surface 12a is formed into a cylindrical surface that forms the outer diameter of the first bearing ring 10.

[0039] Each of the width surfaces 13a, 13b of the first bearing ring 10 is formed in a flat shape along the radial direction, and has a constant radial width over the entire circumference.

[0040] The outer peripheral surface 12 and both width surfaces 13a, 13b of the first bearing ring 10 are covered with a resin portion 50 formed by a pair of annular members 51, 52.

[0041] The rolling elements 30 are bearing components that roll on the raceways 11a of the first bearing ring 10 and the raceways 21a of the second bearing ring 20. The rolling elements 30 in the illustrated example are balls. The circumferential spacing between the multiple rolling elements 30 is maintained at a predetermined value by a cage 40.

[0042] In the illustrated example, the first bearing ring 10, the second bearing ring 20, and the plurality of rolling elements 30 are configured as a deep groove ball bearing, but it is also possible to change to other bearing types such as angular contact ball bearings and self-aligning bearings.

[0043] The first bearing ring 10, the second bearing ring 20 and the rolling elements 30 are each made of a metal, for example, steel.

[0044] Of the pair of annular members 51, 52, the first annular member 51 is made of a molded part that is fitted onto the outer peripheral surface 12 of the first bearing ring 10 from one axial end side. Of the pair of annular members 51, 52, the second annular member 52, which is different from the first annular member 51, is made of a molded part that is fitted onto the outer peripheral surface 12 of the first bearing ring 10 from the other axial end side.

[0045] Each of the annular members 51 and 52 is made of a thermoplastic resin.

[0046] The first annular member 51 has a seamless first cylindrical portion 51a that radially overlaps one axial end side of the outer peripheral surface 12 of the first bearing ring 10, and a first flange portion 51b that axially overlaps the width surface 13a at one axial end side.

[0047] The second annular member 52 has a seamless second cylindrical portion 52a that radially overlaps the other axial end side of the outer peripheral surface 12 of the first raceway ring 10, and a second flange portion 52b that axially overlaps the width surface 13b on the other axial end side.

[0048] The first annular member 51 and the second annular member 52 in the illustrated example are mirror-symmetrical with respect to an imaginary radial plane that bisects the axial width of the first bearing ring 10 .

[0049] Each of the cylindrical portions 51a, 52a has an outer diameter surface and an inner diameter surface along the circumferential direction. The inner diameter surface of each of the cylindrical portions 51a, 52a is fitted into the outer diameter surface 12a of the first bearing ring 10. The inner diameter surface of each of the cylindrical portions 51a, 52a has a smaller diameter than the outer diameter surface 12a of the first bearing ring 10, and is press-fitted onto the outer diameter surface 12a of the first bearing ring 10.

[0050] The first cylindrical portion 51a and the second cylindrical portion 52a have opposing ends facing each other in the axial direction, and an axial gap g is formed between these opposing ends.

[0051] The first cylindrical portion 51a and the second cylindrical portion 52a are welded together. By welding the first cylindrical portion 51a and the second cylindrical portion 52a, the first annular member 51 and the second annular member 52 are joined and integrated with the first bearing ring 10. That is, the cylindrical portions 51a and 52a of the pair of annular members 51 and 52, which are prepared in advance as fitting parts for the first bearing ring 10, are radially overlapped on the outer peripheral surface 12 of the first bearing ring 10, thereby fixing the radial positional relationship between the annular members 51 and 52 and the first bearing ring 10. Furthermore, the flanges 51b, 52b of the pair of annular members 51, 52 are overlapped in the axial direction on the corresponding width faces 13a, 13b of the first bearing ring 10, and these cylindrical portions 51a, 52a are welded together, so that the flanges 51b, 52b of the two annular members 51, 52 hold the first bearing ring 10 in the axial direction. Therefore, without insert molding of resin into each of the bearing rings 10, 20, the resin portion 50 covering the outer peripheral surface 12 of the first bearing ring 10 is formed by the pair of annular members 51, 52, and the annular members 51, 52 are integrated with the first bearing ring 10 so as not to come off from the first bearing ring 10.

[0052] The welded portions 53 of the first cylindrical portion 51a and the second cylindrical portion 52a are formed at a plurality of locations in the circumferential direction, as shown in Figures 1 to 4. These welded portions 53 are evenly arranged in the circumferential direction.

[0053] As shown in Fig. 5, the first cylindrical portion 51a and the second cylindrical portion 52a are welded together in a state in which they are press-fitted onto the outer diameter surface 12a of the first bearing ring 10. In the fitted state before welding shown in Fig. 5, an axial gap g between the first cylindrical portion 51a and the second cylindrical portion 52a is formed to a constant depth in the radial direction around the entire circumferential direction. In the fitted state shown in Fig. 5, the opposing portions of the first cylindrical portion 51a and the second cylindrical portion 52a (i.e., regions including circumferential portions of both cylindrical portions 51a, 52a and opposing ends of each other) are heated and melted from the radial direction by a cylindrical heater H and pressurized to cause the molten resin to flow into the axial gap g, and then cooled, forming the welded portion 53 shown in Figs. 1 to 4. Therefore, the welded portion 53 is recessed radially from the outer diameter surface of each cylindrical portion 51a, 52a due to the molten resin flowing into the axial gap g, and is composed of a circular welded portion 53a that is directly pressurized by the heater H, and enlarged welded portions 53b, 53b on both sides that have flowed circumferentially from the circular welded portion 53a within the axial gap g.

[0054] As shown in FIG. 6 , the rolling bearing 1 is disposed between a shaft 100 of a rotary electric machine and a housing 110 surrounding the shaft 100. The second bearing ring 20 is fitted onto the shaft 100. The outer diameter surfaces of the resin part 50 (both cylindrical parts 51 a, 52 a) integrated with the first bearing ring 10 are fitted into bearing seats 111 of the housing 110. Each cylindrical part 51 a, 52 a is radially sandwiched between the outer diameter surface 12 a of the first bearing ring 10 and the bearing seat 111. The flange part 51 b or 52 b of the annular member 51 or 52 abuts against a shoulder 112 of the housing 110 in the axial direction. In the illustrated example, the flange part 51 b of the first annular member 51 is axially sandwiched between the corresponding width surface 13 a of the first bearing ring 10 and the shoulder 112 of the housing 110. A relative potential difference occurs between the potential of the housing 110 and the potential of the shaft 100, and therefore a voltage is applied to the rolling bearing 1. The pair of annular members 51, 52 insulates the first bearing ring 10 from the housing 110, which is the corresponding fitting partner.

[0055] Since the radial thickness of each cylindrical portion 51a, 52a is greater than the creepage distance required to insulate the bearing seat 111 of the housing 110 from the outer peripheral surface 12 of the first bearing ring 10, it is possible to insulate the bearing seat 111 from the outer peripheral surface 12 of the first bearing ring 10 even if the outer diameter surface 12a of the first bearing ring 10 is exposed from the axial gap g.

[0056] In addition, if the thickness of each cylindrical portion 51a, 52a is smaller than the desired creepage distance or if the joining strength between the first cylindrical portion 51a and the second cylindrical portion 52a is important, the first cylindrical portion 51a and the second cylindrical portion 52a may be welded together around the entire circumference.

[0057] 1 to 4 need only be joined so that they cannot be separated from the first bearing ring 10 without damaging the welded portion 53, and it is not essential that the flanges 51b and 52b completely cover the width faces 13a and 13b of the first bearing ring 10. If the creepage distance between the width face of the first bearing ring and the shoulder is insufficient in an operating environment where the flanges abut against the corresponding shoulders (see FIG. 6), it is sufficient to completely cover the width face of the first bearing ring with the flanges.

[0058] Furthermore, the outer diameter surfaces of the cylindrical portions 51a, 52a in the fitted state before welding shown in Fig. 5 do not need to be along the axial direction, and may have, for example, a draft angle to facilitate demolding of the annular members 51, 52. If it is desired to form the outer diameter surfaces of the cylindrical portions 51a, 52a into a precise cylindrical shape in consideration of the fitting dimensions with the corresponding bearing seats 111 shown in Fig. 6, post-processing such as turning or grinding may be performed after welding the first cylindrical portion 51a and the second cylindrical portion 52a. When this post-processing is performed, it is only necessary to ensure in advance a radial interference and joint strength between the pair of annular members and the first ring so that they can resist the processing force during post-processing.

[0059] Furthermore, the axial gap g in the fitted state before welding shown in Fig. 5 is preferably set to 0.5 mm or less. The formation of the axial gap g makes it possible to form expanded fusion zones 53b, 53b and expand the weld cross section of the welded portion 53 in the circumferential direction even during the welding process, which melts only a portion in the circumferential direction. On the other hand, if the axial gap g exceeds 0.5 mm, the opposing portions of the first tubular portion 51a and the second tubular portion 52a may not be connected by the molten resin even when they are melted, or even if they are connected, the welded portion may be too thin and the joining strength of the welded portion may be insufficient, which may cause the first annular member 51 and the second annular member 52 to separate when they are assembled between the shaft 100 and the housing 110, as shown in Fig. 6.

[0060] As shown in FIG. 5, the diameter d of the resin region melted by heater H (i.e., the diameter of circular fused portion 53a) is preferably three times the thickness of the resin region (i.e., the thickness of tubular portions 51a and 52a before welding, and the thickness of the unwelded portions of tubular portions 51a and 52a after welding). If diameter d is too small compared to the thickness of the resin region, the resulting weld cross section will be small, potentially resulting in insufficient bonding strength at the welded portion. Conversely, if diameter d is too large compared to the thickness of the resin region, as shown in FIG. 6, the outer diameter surface area of ​​resin portion 50 (the unwelded regions of both tubular portions 51a and 52a) that radially contacts the corresponding bearing seat 111 will be reduced, potentially resulting in a local increase in contact pressure near the welded portion or localized large deformation of first bearing ring 10 near the welded portion when a bearing load is applied.

[0061] The thermoplastic resin used to form each of the annular members 51, 52 may have, for example, a dielectric strength of 500 V / mm or more. Here, the dielectric strength refers to a value measured by a test method conforming to the ASTM D149 Step-by-Step Test. The thermoplastic resin used to form each of the annular members 51, 52 may have, for example, a surface current resistance index of 600 V or more. Here, the surface current resistance index refers to a CTI value measured in a tracking resistance test conforming to the IEC 60112 standard. Examples of such thermoplastic resins include polyphenylene sulfide (PPS) and polyphthalamide (PPA).

[0062] Examples of the aforementioned rotating electric machine include electric motors and e-axles in electric vehicles. Currently, the system voltage of electric vehicles is mainly 400V, but this is expected to increase to around 1000V in the future. When the system voltage is 1000V, the relative potential difference between the housing and the shaft is thought to be about 1 / 10 of the system voltage. In other words, the voltage applied to the rolling bearing 1 between the housing and the shaft is expected to be around 100V. According to the IEC 60664-1 Ed2.0 standard, regardless of the material group of the insulating material that forms the creepage surface, if the creepage distance is 0.3 mm, insulation up to an effective voltage of 100V is possible. In other words, when achieving insulation capable of withstanding an applied voltage of 100 V in the rolling bearing 1 interposed between the bearing seat 111 and shoulder 112 of the housing 110 shown in Figure 6 and the shaft 100, the resin thickness (creepage distance) required for each of the annular members 51, 52 existing between the first raceway ring 10 and the housing 110 is 0.3 mm or more, so it is sufficient to set the resin thickness of all of the annular members 51, 52 to 0.3 mm or more.

[0063] Furthermore, as a method for welding the first cylindrical portion 51a and the second cylindrical portion 52a, thermal welding has been exemplified, in which a heated heater H is used to melt the cylindrical portions from the surface and then pressurize them to join them before they cool and harden, as shown in FIG. 5 . However, other welding methods may also be used, such as high-frequency welding, in which both cylindrical portions are heated from the inside using high-frequency waves, ultrasonic welding, in which both cylindrical portions are heated from the inside using ultrasonic waves, or laser welding, in which both cylindrical portions are heated from the surface using the heat of laser light.

[0064] The rolling bearing 1 (see Figures 1 to 4) is as described above, and comprises a first raceway 10, a second raceway 20, and a plurality of rolling elements 30 arranged between the first raceway 10 and the second raceway 20, and the outer peripheral surface 12 of the first raceway 10, which is the peripheral surface on the outside of the bearing, is covered with a resin part 50.

[0065] In particular, the rolling bearing 1 has a resin portion 50 formed by a pair of fitting members 51, 52, so that the resin portion 50 is formed without insert molding. Furthermore, the annular members 51, 52 that axially sandwich the first bearing ring 10 are welded to each other, so that the pair of annular members 51, 52 are integrated with the first bearing ring so as not to come off the first bearing ring, without insert molding. Therefore, the rolling bearing 1 uses the resin portion 50 to insulate the circumferential surface (outer peripheral surface 12) of the first bearing ring 10 on the outer side of the bearing from the corresponding housing 110 (see FIG. 6 ), without insert molding the bearing rings 10, 20 with resin, and can suppress electrolytic corrosion of the rolling bearing 1.

[0066] Furthermore, in the rolling bearing 1 (see Figures 1 to 4), an axial gap g is formed between the annular members 51, 52, and a welded portion 53 is formed by melting the opposing portions of the annular members 51, 52 and allowing the melted portions to flow into the axial gap g, thereby expanding the weld cross section between the annular members 51, 52 in the circumferential direction within the axial gap g, thereby strengthening the bond between the annular members 51, 52.

[0067] As another example of the first aspect of the present invention, a rolling bearing according to a second embodiment will be described with reference to the accompanying drawings, Figures 7 to 13. Note that, hereinafter, only differences from the first embodiment will be described, and the same reference numerals will be used for corresponding components.

[0068] As shown in FIGS. 7 to 9 , the first annular member 51 according to the second embodiment is formed so as to cover the entire side surface portion extending between one axial end of the inner peripheral surface 11 of the first bearing ring 10 and one axial end of the outer peripheral surface 12 in both the axial and radial directions. For this reason, a first protrusion 51c is added, extending from the first flange 51b to a position overlapping radially with the one axial end of the inner peripheral surface 11. The second annular member 52 is formed so as to cover the entire side surface portion extending between the other axial end of the inner peripheral surface 11 of the first bearing ring 10 and the other axial end of the outer peripheral surface 12 in both the axial and radial directions. For this reason, a second protrusion 52c is added, extending from the second flange 52b to a position overlapping radially with the other axial end of the inner peripheral surface 11.

[0069] 7 and 8, a first corner 51d connecting the first cylindrical portion 51a and the first flange 51b has a shape recessed in the axial direction from the first flange 51b. A second corner 52d connecting the second cylindrical portion 52a and the second flange 52b has a shape recessed in the axial direction from the second flange 52b. The inner surface of each corner 51d, 52d is composed of a tapered region inclined radially from the corresponding flange 51b, 52b, and an arc-shaped region extending from the tapered region to the corresponding cylindrical portion 51a, 52a. Compared to the first embodiment, in which the corresponding tubular portion and the flange portion are connected by a single arc-shaped inner surface, by adopting corner portions 51d, 52d that form a concave shape on the inner surface as described above, when the corresponding tubular portions 51a, 52a are pressed into the outer peripheral surface 12 of the first bearing ring 10, stress concentration at the corresponding corner portions 51d, 52d is alleviated, and the maximum stress at the corresponding corner portions 51d, 52d is reduced.

[0070] As shown in FIGS. 7, 10, and 12, the first cylindrical portion 51a includes a first stepped portion 51e having a step that opens toward one radial side and one axial side. Here, the first radial side refers to the side radially away from the outer peripheral surface 12 of the first bearing ring 10, which is the peripheral surface on the outer side of the bearing, and the first axial side refers to the side axially approaching the second annular member 52. The first stepped portion 51e has a smaller diameter than the outer diameter surface 51f that defines the outer diameter of the first cylindrical portion 51a and is continuous around the entire circumference. Therefore, the first stepped portion 51e has a stepped surface extending radially inward from the outer diameter surface 51f and a concave bottom surface extending from this stepped surface to the axial gap g. Meanwhile, the second cylindrical portion 52a includes a second stepped portion 52e that is axially opposite the first stepped portion 51e and has a step that opens toward one radial side and the other axial side. Here, the other axial side is the side opposite to the one axial side and closer to the first annular member 51 in the axial direction. The second step portion 52e has a diameter smaller than that of the outer diameter surface 52f that defines the outer diameter of the second tubular portion 52a and the same diameter as that of the first step portion 52e, and is continuous around the entire circumferential direction. Therefore, the second step portion 52e has a step surface that extends radially inward from the outer diameter surface 52f and a concave bottom surface that extends from this step surface to the axial gap g.

[0071] 13, in the welding process of both cylindrical portions 51a, 52a, heater H is brought into radial contact only with the concave bottom surfaces, which are the deepest parts in the radial direction, of first step portion 51e and second step portion 52e, to melt both step portions 51e, 52e while applying pressure and cooling, thereby forming welded portion 53 shown in Figures 10 to 12. Therefore, compared to the first embodiment, welded portion 53 is formed thinner at a position that is recessed radially deeper from outer diameter surfaces 51f, 52f of both cylindrical portions 51a, 52a.

[0072] During the welding process of the cylindrical portions 51a, 52a, a small amount of molten resin may protrude from between the heater H and the non-welded portions of the cylindrical portions 51a, 52a when the heater H pressurizes the molten resin, or the unsolidified resin may be slightly pulled up by the heater H when the heater H is separated from the cylindrical portions 51a, 52a, resulting in the formation of burrs at the welded portions 53. Even if burrs are formed at the welded portions 53, the burrs are formed at positions deeper radially from the outer diameter surfaces 51f, 52f of the cylindrical portions 51a, 52a than in the first embodiment. This prevents the burrs from protruding from the stepped portions 51e, 52e above the outer diameter surfaces 51f, 52f. Burrs that do not protrude above the outer diameter surfaces 51f, 52f can be ignored when fitting the outer diameter surfaces 51f, 52f to the corresponding mechanical element, the housing 110, and therefore do not need to be removed in post-processing.

[0073] In this way, in the rolling bearing of the second embodiment (see Figures 7 to 12), the first annular member 51 includes a first step portion 51e having a step that is open toward one radial side and one axial side, and the second annular member 52 includes a second step portion 52e at a position axially opposite the first step portion 51e, having a step that is open toward one radial side and the other axial side, and a welded portion 53 is formed by melting only the first step portion 51e and the second step portion 52e.Therefore, even if a burr is formed in the welded portion, it can be prevented from protruding from the first step portion 51e and the second step portion 52e, and deburring can be omitted.

[0074] Although the example in which the step portions 51e, 52e are formed all around the circumference has been shown, they may be formed at one or more locations in the circumferential direction of both the annular members 51, 52.

[0075] Furthermore, in the rolling bearing according to the second embodiment, each of the annular members 51, 52 is formed to cover the entire surface of the side surface portion extending between the inner peripheral surface 11 and the outer peripheral surface 12 of the first bearing ring 10, and therefore even in an environment in which the first flange 51b or the second flange 52b is abutted against the corresponding mechanical element (housing 110) in the axial direction for axial positioning, it is possible to insulate the side surface portion of the first bearing ring 10 from the corresponding mechanical element (housing 110). Furthermore, in order to ensure this insulation, it is no longer necessary to thicken each of the flanges 51b, 52b to provide a large creepage distance in the axial direction.

[0076] In the rolling bearing according to the second embodiment, the first annular member 51 has a first cylindrical portion 51a overlapping one axial end side of the peripheral surface (outer peripheral surface 12) on the outer side of the bearing, and a first flange portion 51b overlapping the width surface 13a on one axial end side of the first bearing ring 10, and the second annular member 52 has a second cylindrical portion 52a overlapping the other axial end side of the peripheral surface (outer peripheral surface 12) on the outer side of the bearing, and a first flange portion 51b overlapping the width surface 13a on the other axial end side of the first bearing ring 10. 3b, and the corresponding first corner portion 51d or second corner portion 52d connecting the first tubular portion 51a or the second tubular portion 52a to the corresponding first flange portion 51b or second flange portion 52b has a shape recessed in the axial direction from the corresponding first flange portion 51b or second flange portion 52b, so that the stress at each corner portion 51d, 52d can be reduced and cracking at each corner portion 51d, 52d can be prevented.

[0077] As yet another example of the first aspect of the present invention, a rolling bearing according to a third embodiment is shown in FIG. 14 of the accompanying drawings.

[0078] The outer peripheral surface 12 of the first bearing ring 10 according to the third embodiment, which serves as the peripheral surface on the outside of the bearing, includes recesses 12c recessed radially from the outer diameter surface 12a, which serve as mating surfaces for the cylindrical portions 51a and 52a. The recesses 12c face the axial gap g in the radial direction and are positioned so as to overlap the first cylindrical portion 51a and the second cylindrical portion 52a in the radial direction. The recesses 12c are groove-shaped and have a constant radial depth from the outer diameter surface 12a around the entire circumferential direction. The welded portions 53 are formed by heating and melting the portions of the first cylindrical portion 51a and the second cylindrical portion 52a above the recesses 12c (portions radially facing the recesses 12c) using a heater H (see FIG. 5) from the radial direction, applying pressure, and causing the molten resin to flow into the recesses 12c, followed by cooling. Since the recessed portion 12c is a groove-like portion extending in the circumferential direction, the molten resin flows in the circumferential direction within the recessed portion 12c during the welding process, and the expanded molten portion described above is formed within the recessed portion 12c.

[0079] The rolling bearing of the third embodiment includes a recess 12c having a radially recessed shape at a position where the peripheral surface (outer peripheral surface 12) of the first raceway 10 on the outer side of the bearing overlaps with a pair of annular members 51, 52, and a welded portion 53 is formed by melting the recessed portion 12c in the pair of annular members 51, 52 and flowing it into the recessed portion 12c, so that the weld cross section between the annular members 51, 52 can be expanded radially within the recessed portion 12c, thereby strengthening the bond between the annular members 51, 52.

[0080] Although the recessed portion 12c is formed around the entire circumference in the example shown, it may be formed at one or more locations in the circumferential direction on the circumferential surface of the first bearing ring on the outer side of the bearing. Also, in the third embodiment, it is possible to adopt the corner shape and protrusion of the annular member shown in the second embodiment.

[0081] The pair of annular members 51, 52 do not need to be provided symmetrically as in the first to third embodiments, and may be provided asymmetrically. As an example, a fourth embodiment relating to the first aspect of the present invention is shown in the accompanying drawings in Figures 15 and 16. The rolling bearing according to the fourth embodiment is a further modification of the third embodiment. This explanation will be limited to describing the changes from the third embodiment.

[0082] The pair of annular members 51, 52 according to the fourth embodiment differs from the third embodiment in that a difference is provided between the axial widths of the first cylindrical portion 51a and the second cylindrical portion 52a. The axial positions of the axial gap g, the recessed portion 12c, and the welded portion 53 are also changed by the amount of the difference in axial width between the first cylindrical portion 51a and the second cylindrical portion 52a. This prevents the axial gap g and the recessed portion 12c from being located on an extension of the line of action of the load of the rolling bearing 1 configured as a deep groove ball bearing (the imaginary line connecting the contact point between the raceway 11a of the first bearing ring 10 and the rolling element 30 and the contact point between the raceway 21a of the second bearing ring 20 and the rolling element 30).

[0083] As an example of the second aspect of the present invention, a rolling bearing according to a fifth embodiment will be described with reference to the accompanying drawings, Figures 17 and 18. The rolling bearing according to the fifth embodiment is a further modification of the third embodiment. In this description, only the changes from the third embodiment will be described.

[0084] The first cylindrical portion 51a and the second cylindrical portion 52a according to the fifth embodiment are not welded together, and the first annular member 51 and the second annular member 52 are not joined together.

[0085] The outer peripheral surface 12 of the first bearing ring 10 includes recessed portions 12c having a shape recessed radially from the outer diameter surface 12a in each region overlapping with the annular members 51, 52. That is, the first recessed portions 12c are formed in the region of the outer peripheral surface 12 of the first bearing ring 10 that overlaps radially with the first cylindrical portion 51a, and the second recessed portions 12c are formed in the region that overlaps radially with the second cylindrical portion 52a.

[0086] A first molten portion 54 is formed by melting a portion of the first cylindrical portion 51a located above the recessed portion 12c and causing it to flow into the recessed portion 12c, and a second molten portion 54 is formed by melting a portion of the second cylindrical portion 52a located above the recessed portion 12c and causing it to flow into the recessed portion 12c. Each molten portion 54 is formed by melting the first molten portion 51a with the heater, applying pressure to the second molten portion 52a, and causing it to flow into the recessed portion 12c, followed by cooling. The first molten portion 54 and the second molten portion 54 are each formed at multiple locations in the circumferential direction and are evenly distributed in the circumferential direction.

[0087] The formation of the first fusion zone 54 integrates the first annular member 51 with the first bearing ring 10, and the formation of the second fusion zone 54 integrates the second annular member 52 with the first bearing ring 10. That is, the cylindrical portions 51a, 52a of the annular members 51, 52, which are prepared in advance as fitting parts for the first bearing ring 10, are radially overlapped on the outer peripheral surface 12 of the first bearing ring 10, thereby fixing the radial positional relationship between the two annular members 51, 52 and the first bearing ring 10. Furthermore, the axial engagement between the corresponding fusion zones 54 formed in the cylindrical portions 51a, 52a and the corresponding recessed portions 12c fixes the axial positional relationship between the corresponding annular members 51, 52 and the first bearing ring 10. Therefore, without insert molding resin into the raceways 10 and 20, the resin part 50 covering the outer surface 12 of the first raceway 10 is formed by two annular members 51 and 52, and both annular members 51 and 52 are integrated with the first raceway 10 so that they do not come off the first raceway 10.

[0088] It is sufficient that the recessed portion 12c and the fusion portion 54 are formed so that the corresponding annular members 51, 52 cannot be separated from the first bearing ring 10 without damaging the fusion portion 54. Furthermore, even if the annular members 51, 52 do not have corresponding flanges 51b, 52b, the annular members 51, 52 can be integrated with the first bearing ring 10 by axial engagement between the fusion portion 54 and the recessed portion 12c, so that the flanges 51b, 52b can be omitted, and the resin portion 50 can also be formed from only one annular member.

[0089] Thus, the rolling bearing of the fifth embodiment comprises a first raceway 10, a second raceway 20, and a plurality of rolling elements 30 arranged between the first raceway 10 and the second raceway 20, and the peripheral surface (outer peripheral surface 12) of the first raceway 10 on the outside of the bearing is covered with a resin part 50.

[0090] In particular, in the rolling bearing according to the fifth embodiment, the resin portion 50 is formed by one or more annular members 51, 52 fitted onto the circumferential surface (outer peripheral surface 12) on the outer side of the bearing, and the circumferential surface (outer peripheral surface 12) on the outer side of the bearing includes recesses 12c having a radially recessed shape in each region overlapping the annular members 51, 52, and molten portions 54 are formed by melting the portions of each annular member 51, 52 located above the recesses 12c and flowing them into the recesses 12c.As a result, the annular members 51, 52 forming the resin portion 50 are integrated with the first bearing ring 10 so as not to come off from the first bearing ring 10, without the need for resin insert molding on the first bearing rings 10, and the rolling bearing according to the fifth embodiment therefore uses the resin portion 50 to provide insulation between the outer side of the bearing (outer peripheral surface 12) of the first bearing ring 10 and the corresponding housing 110, without the need for resin insert molding on the bearing rings 10, 20, making it possible to suppress electrolytic corrosion of the rolling bearing.

[0091] In addition, in the rolling bearing of the fifth embodiment, the annular members 51, 52 have cylindrical portions 51a, 52a that overlap the peripheral surface (outer peripheral surface 12) of the first raceway 10 on the outer side of the bearing, and flange portions 51b, 52b that overlap the width surface 13a at one axial end side or the width surface 13b at the other axial end side of the first raceway 10.Therefore, the flange portions 51b, 52b of the annular members 51, 52 are sandwiched between the corresponding width surface 13a of the first raceway 10 and the corresponding mechanical element (housing 110), thereby achieving insulation between these width surfaces 13a and the mechanical element (housing 110) and eliminating the concern that the annular member 51 will separate axially from the first raceway 10 during use of this rolling bearing.

[0092] In the fifth embodiment, as in the second embodiment, it is possible to employ a corner portion having a shape recessed in the axial direction from the flange portion, and it is also possible to employ an annular member that covers the entire surface of the corresponding side portion extending between the inner and outer surfaces of the first raceway.

[0093] Furthermore, while the above-described embodiments have been described with reference to an example in which the first bearing ring 10 is an outer ring, it is also possible to change the first bearing ring to an inner ring (see the second bearing ring 20). In this case, of the inner and outer circumferential surfaces of the first bearing ring, the inner circumferential surface of the inner ring is the surface facing the outside of the bearing. Therefore, a pair or more annular members may be configured to cover the inner circumferential surface of the inner ring with a resin portion, and the resin portion may be used to insulate the inner ring from the shaft. In other words, by referring to the above-described embodiments, it is only necessary to modify the annular members (tubular portions) so that they overlap the inner circumferential surface of the inner ring, the annular members (flange portions) so that they overlap the corresponding width surfaces of the inner ring, and, if a protrusion of each annular member is used, they overlap the outer circumferential surface of the inner ring. Therefore, illustrations and detailed description thereof will be omitted.

[0094] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0095] 1. Rolling bearings 10 First bearing ring 11 Inner surface 11a orbit 12 Outer surface (outer surface of bearing) 12c recess 13a, 13b width side 20 Second bearing ring 30 rolling elements 50 Resin part 51, 52 Annular member 51a, 52a Cylindrical part 51b, 52b Tsuba 51d, 52d corner 51e, 52e Step 53 Welded area 54 Welding section g Axial clearance

Claims

1. a first bearing ring, a second bearing ring, and a plurality of rolling elements disposed between the first bearing ring and the second bearing ring; In the rolling bearing, a peripheral surface of the first bearing ring on an outer side of the bearing is covered with a resin portion, the resin portion is formed by a pair of annular members that sandwich the first bearing ring in the axial direction, A rolling bearing characterized in that the annular members are welded to each other.

2. An axial gap is formed between the annular members, 2. The rolling bearing according to claim 1, wherein a welded portion is formed by melting opposing portions of the annular members and allowing the melted portions to flow into the axial gap.

3. the first annular member includes a first step portion having a step that is open toward one radial side and one axial side, the second annular member includes a second step portion having a step that is open toward one radial side and the other axial side at a position axially opposite to the first step portion, 3. The rolling bearing according to claim 1, wherein a welded portion is formed by melting only the first step portion and the second step portion.

4. the peripheral surface on the outer side of the bearing includes a recessed portion having a shape recessed in the radial direction at a position overlapping the pair of annular members, 3. The rolling bearing according to claim 1, wherein a welded portion is formed by melting the recessed portions of the pair of annular members and allowing the melted portions to flow into the recessed portions.

5. 3. A rolling bearing according to claim 1, wherein each of the annular members is formed so as to cover the entire surface of a corresponding side surface portion extending between the inner peripheral surface and the outer peripheral surface of the first bearing ring.

6. the first annular member has a first cylindrical portion overlapping one axial end side of the circumferential surface on the outer side of the bearing, and a first flange portion overlapping a width surface of the first bearing ring at one axial end side, a second annular member having a second cylindrical portion overlapping the other axial end side of the peripheral surface on the outer side of the bearing, and a second flange portion overlapping the width surface of the other axial end side of the first bearing ring, 3. A rolling bearing according to claim 1 or 2, wherein a first corner portion or a second corner portion connecting the first cylindrical portion or the second cylindrical portion to the corresponding first flange portion or the corresponding second flange portion has a shape recessed in the axial direction from the corresponding first flange portion or the corresponding second flange portion.

7. a first bearing ring, a second bearing ring, and a plurality of rolling elements disposed between the first bearing ring and the second bearing ring; In the rolling bearing, a peripheral surface of the first bearing ring on an outer side of the bearing is covered with a resin portion, the resin portion is formed by one or more annular members fitted to a circumferential surface of the bearing outer side, The outer peripheral surface of the bearing includes a recessed portion having a radially recessed shape in each region overlapping the annular member, A rolling bearing characterized in that a molten portion is formed by melting a portion of the annular member located above the recess and allowing the portion to flow into the recess.

8. 8. A rolling bearing as described in claim 7, wherein the annular member has a cylindrical portion overlapping the peripheral surface on the outer side of the bearing, and a flange portion overlapping the width surface on one axial end side or the width surface on the other axial end side of the first bearing ring.

9. A method for manufacturing a rolling bearing comprising a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway, wherein a peripheral surface of the first raceway on an outer side of the bearing is covered with a resin portion, a first raceway ring and a second raceway ring, the first raceway ring being sandwiched between the first raceway ring and the second raceway ring; a second raceway ring and a second raceway ring, the first raceway ring and the second raceway ring being welded together;

10. 10. A method for manufacturing a rolling bearing as described in claim 9, wherein the resin portion is formed by fitting a first annular member to one axial end side of the peripheral surface outside the bearing and a second annular member to the other axial end side of the peripheral surface outside the bearing, and an axial gap is formed between the annular members, and a weld portion is formed by melting the opposing portions of the annular members and allowing the melted portions to flow into the axial gap.

11. The first annular member includes a first step portion having a step that is open toward one radial side and one axial side, The second annular member includes a second stepped portion having a step that is open toward one radial side and the other axial side at a position axially opposite to the first stepped portion, The method for manufacturing a rolling bearing according to claim 9 or 10, wherein a welded portion is formed by melting only the first step portion and the second step portion.

12. The first bearing ring includes a recessed portion having a radially recessed shape at a position where the peripheral surface on the outer side of the bearing overlaps with the pair of annular members, The method for manufacturing a rolling bearing according to claim 9 or 10, wherein the pair of annular members are melted above the recessed portions and the melted portions are caused to flow into the recessed portions, thereby forming welded portions.

13. A method for manufacturing a rolling bearing comprising a first raceway, a second raceway, and a plurality of rolling elements arranged between the first raceway and the second raceway, wherein a peripheral surface of the first raceway on an outer side of the bearing is covered with a resin portion, The resin portion is formed by fitting one or more annular members onto a circumferential surface of the bearing outer side, The first bearing ring, which is a mating partner of the one or more annular members, includes a recessed portion having a shape recessed in the radial direction in each region of a circumferential surface on the outer side of the bearing that overlaps with the annular member, A method for manufacturing a rolling bearing, characterized in that a portion of the annular member located above the recessed portion is melted and allowed to flow into the recessed portion to form a molten portion.

14. 14. A method for manufacturing a rolling bearing according to claim 13, wherein the annular member has a cylindrical portion overlapping the peripheral surface on the outer side of the bearing, and a flange portion overlapping the width surface on one axial end side or the width surface on the other axial end side of the first bearing ring.

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