Insulated bearing

Abstract

A resin insulating member is attached to the raceway to insulate it from the raceway, and this prevents defects from occurring in the insulating member due to the difference in the coefficient of thermal expansion between the raceway and the insulating member. [Solution] The device comprises a first raceway 3, a second raceway 4, a plurality of rolling elements 5 positioned between the first raceway 3 and the second raceway 4, and a plurality of insulating members 2 made of resin. Each insulating member 2 has an arc-shaped portion 2a that covers the first raceway 3 from the radially outward direction, and retaining portions 2b that protrude radially inward from both axial ends of the arc-shaped portion 2a and engage with the first raceway 3 to prevent it from falling off. The circumference of each insulating member 2 is set to be less than or equal to half the circumference of the outer diameter of the first raceway 3. The retaining portion 2b includes a projection 2d that protrudes axially inward.

Description

Technical Field

[0001] This invention relates to an insulating bearing in which a raceway ring is covered with resin in order to insulate a rolling bearing.

Background Art

[0002] When a rotating part is supported by a rolling bearing in a device that uses 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 to the inner ring side or from the inner ring to the outer ring side of the rolling bearing due to that voltage, electric erosion occurs at the contact parts between the rolling elements and the outer and inner rings of the rolling bearing. Conventionally, measures have been taken to insulate the rolling bearing in order to prevent such electric erosion.

[0003] As one of the insulation measures, there is a structure in which a resin with high insulating properties is insert-molded onto a raceway ring (inner ring or outer ring), and the fitting surface and side surface of the raceway ring are covered with resin over the entire circumference (Patent Document 1).

[0004] In addition, there is a structure in which an insulating member made of a resin ring having a cross-sectional L shape that covers the fitting surface of the raceway ring in the radial direction and covers one side surface of the raceway ring in the axial direction is press-fitted over the entire circumference onto the fitting surface of the raceway ring (Patent Document 2). The insulating bearing of Patent Document 2 forms a circumferential groove on the fitting surface of the raceway ring, and the insulating member includes a protrusion that fits into the aforementioned circumferential groove, thereby enhancing the performance of preventing the insulating member from coming out in the axial direction with respect to the raceway ring.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when the resin covering the raceway and the raceway itself are integrated by insert molding, as in Patent Document 1, there are many things to be careful about, such as removing gate marks after insert molding, and masking and cleaning to prevent debris from adhering to the raceway surface during post-processing after molding, which leads to increased costs and leaves room for improvement.

[0007] On the other hand, when the insulating member and the raceway are integrated by press-fitting, as in Patent Document 2, in order to avoid insert molding, the insulating member and the raceway are fitted together around the entire circumference with a tight radial interference fit. If a temperature change occurs while the insulated bearing is in use in this state, there is a concern that defects may occur in the insulating member due to the relationship that the coefficient of linear expansion of the insulating member > the coefficient of linear expansion of the raceway. In other words, when the temperature changes, a difference in the amount of expansion / contraction of the insulating member and the raceway occurs, and especially when cold, the amount of contraction of the insulating member becomes larger than the amount of contraction of the raceway, causing circumferential tensile stress in the insulating member. This tensile stress may cause defects such as cracks in the insulating member.

[0008] In light of the above-mentioned background, the problem that this invention aims to solve is to prevent defects from occurring in the insulating member due to the difference in the coefficient of linear expansion between the raceway and the insulating member when the insulating member is attached to the raceway to insulate the raceway. [Means for solving the problem]

[0009] To solve the above problems, this invention adopts an insulating bearing configuration 1 comprising a first raceway, a second raceway, a plurality of rolling elements disposed between the first raceway and the second raceway, and a plurality of insulating members made of resin, wherein each insulating member has an arc-shaped portion that covers the first raceway from the radially outward direction, and retaining portions that protrude radially inward from both axial ends of the arc-shaped portion and engage with the first raceway to prevent it from falling off, the circumference of each insulating member is set to be half the circumference of the outer diameter of the first raceway, and the retaining portion includes a projection that protrudes axially inward.

[0010] According to the above configuration 1, although the circumference of each insulating member is less than half the circumference of the outer diameter of the first raceway in the circumferential direction, it is attached to the first raceway by a retaining portion including a projection without relying on radial tightening relative to the first raceway. Therefore, even if the amount of shrinkage of the insulating member when cold is greater than the amount of shrinkage of the raceway, it is not possible to tighten the first raceway radially, and it is possible to prevent excessive circumferential tensile stress from being generated in each insulating member.

[0011] In the above configuration 1, a configuration 2 can be adopted in which a circumferential distance is provided between adjacent insulating members in the circumferential direction, and the thickness of the insulating member is 0.3 mm or more.

[0012] According to the above configuration 2, it becomes easier to control the dimensions of the circumferential length of each insulating member. The first raceway ring will be partially exposed between the insulating members, but if the thickness of the insulating member is 0.3 mm or more, a creepage distance of 0.3 mm or more will be provided by the resin surface of the insulating member from the exposed portion of the first raceway ring, so that insulation that can withstand an applied voltage of 100 V can be ensured.

[0013] In the above configuration 1 or 2, configuration 3 can be adopted, in which the retaining portion is provided in a flange shape that protrudes radially from the arc-shaped portion.

[0014] According to the above configuration 3, a retaining portion is inserted axially between the mechanical element of the other device incorporating the insulating bearing and the first raceway ring, thereby providing insulation between the two and eliminating concerns that the insulating member may separate axially from the raceway ring during use of the insulating bearing.

[0015] In any one of the above configurations 1 to 3, configuration 4 can be adopted, in which a groove extending circumferentially is formed on the side surface of the first raceway, and each of the protrusions that catch on the axial end of the first raceway is arranged to fit into the groove.

[0016] According to the above configuration 4, each projection corresponding to the groove of the first raceway can be inserted and radially hooked onto the axial end of the first raceway. Therefore, it is not necessary to change the specifications inside the bearing in order to hook the projections, and the circumferential mounting position of the insulating member relative to the first raceway can be made irrelevant.

[0017] In the above configuration 4, a configuration 5 can be adopted in which the retaining portion consists of a first flange protruding radially from one axial end of the arc-shaped portion and a second flange protruding radially from the other axial end of the arc-shaped portion, and is provided so as to axially sandwich the axial ends on both sides of the first raceway ring with the two flanges, the first flange and the second flange each have the projection, and the grooves are formed on both sides of the axial surface of the first raceway ring.

[0018] According to the above configuration 5, the mounting strength of the insulating member can be increased compared to the case where the retaining portion is provided only on one axial side of the arc-shaped portion. Furthermore, even if the mechanical elements of other devices incorporating the insulating bearing are located on either the axial side or the other side of the first raceway, insulation can be provided by sandwiching the corresponding first or second flange, and concerns about the insulating member separating axially from the raceway during use of the insulating bearing can be eliminated.

[0019] In any one of the above configurations 1 to 5, configuration 6 can be adopted, in which the insulating member is made of a molded product that does not contain weld lines.

[0020] According to the above configuration 6, since the insulating member does not have welds which are weak points in the molded product, the strength of the insulating member against circumferential tensile stress can be increased.

[0021] In any one of the above configurations 1 to 6, configuration 7 can be adopted in which the insulating member is made of fiber-reinforced resin, and the insulating member has a gate mark only on one end face in the circumferential direction of the insulating member.

[0022] According to the above configuration 7, the fiber-reinforced resin injected from the gate opening into the cavity portion forming one end face in the circumferential direction of the insulating member flows in the circumferential direction and is filled up to the cavity portion forming the other end face in the circumferential direction of the insulating member, resulting in an insulating member that does not include a weld and in which the fibers in the resin are generally oriented in the circumferential direction. Therefore, the fiber reinforcement effect can be exerted against the tensile stress in the circumferential direction, and the strength of the insulating member can be made higher against the tensile stress in the circumferential direction.

Advantages of the Invention

[0023] As described above, by adopting the above configuration 1, this invention can prevent defects from occurring in the insulating member due to the difference in the linear expansion coefficients between the track wheel and the insulating member in a state where the resin-made insulating member is attached to the track wheel so as to insulate the track wheel.

Brief Description of the Drawings

[0024] [Figure 1] Side view showing the insulating bearing according to an embodiment of this invention [Figure 2] Side view showing the state where the insulating member in FIG. 1 is removed [Figure 3] Cross-sectional view taken along line III-III in FIG. 1 [Figure 4] Perspective view of the insulating member according to the embodiment [Figure 5] Side view of the insulating member in FIG. 4 [Figure 6] Cross-sectional view taken along line VI-VI in FIG. 5 [Figure 7] Enlarged view near the protrusion in FIG. 3

Modes for Carrying Out the Invention

[0025] An insulating bearing according to an embodiment as an example of this invention (hereinafter simply referred to as "this insulating bearing") will be described based on the accompanying drawings.

[0026] This insulating bearing shown in FIG. 1 is composed of a rolling bearing 1 and a plurality of insulating members 2 formed of resin.

[0027] As shown in Figures 2 and 3, the rolling bearing 1 has a first raceway 3, a second raceway 4, and a plurality of rolling elements 5 arranged between the first raceway 3 and the second raceway 4.

[0028] The first raceway ring 3 is a bearing component that seamlessly has an inner circumferential surface 3a, an outer circumferential surface 3b, a width surface 3c on one end that extends radially between the axial ends of the inner circumferential surface 3a and the outer circumferential surface 3b, and a width surface 3c on the other end that extends radially between the axial ends of the inner circumferential surface 3a and the outer circumferential surface 3b. The second raceway ring 4 is similar.

[0029] Here, the direction along the central axis of the first raceway ring 3 is called the "axial direction," the direction perpendicular to that central axis is called the "radial direction," and the direction along the circumference of the circle centered on that central axis is called the "circumferential direction." Note that the axial direction corresponds to the left-right direction in Figure 3, and the radial direction corresponds to the up-down direction in Figure 3. The axial outer direction refers to the side away from the rolling element, the axial inner direction refers to the side approaching the rolling element, the radial inner direction refers to the direction approaching the bearing center, and the radial outer direction refers to the direction away from the bearing center.

[0030] The first raceway ring 3 has an outer ring in which the inner circumferential surface 3a, which is one of the inner circumferential surfaces 3a and the outer circumferential surface 3b, includes the raceway 3d.

[0031] Furthermore, in the second raceway 4, of the inner circumferential surface 4a and the outer circumferential surface 4b, the outer circumferential surface 4b is an inner ring that includes the raceway 4c.

[0032] Of the inner circumferential surface 3a and outer circumferential surface 3b of the first raceway ring 3, the outer circumferential surface 3b, which is different from the inner circumferential surface 3a, is composed of an outer diameter surface 3e extending in the circumferential direction and chamfers 3f formed between the outer diameter surface 3e and each width surface 3c. The outer diameter surface 3e is formed in a cylindrical shape that forms the outer diameter of the first raceway ring 3.

[0033] Each width surface 3c of the first raceway ring 3 is formed to be flat along the radial direction.

[0034] Grooves 3g are formed on both axial sides of the first raceway ring 3. The grooves 3g extend axially from the corresponding width surface 3c and have groove depth around the entire circumference. The groove 3g at one axial end and the groove 3g at the other axial end are arranged symmetrically with respect to each other in the axial direction. The groove shoulder on one radial side (radially outward in the illustrated example) of the groove 3g constitutes an axial end 3h used to attach a plurality of insulating members 2 to the first raceway ring 3.

[0035] The rolling elements 5 are bearing components that roll on the raceway 3d of the first raceway ring 3 and the raceway 4c of the second raceway ring 4. The rolling elements 5 consist of balls. The circumferential spacing between the multiple rolling elements 5 is maintained at a predetermined level by the cage 6.

[0036] The first raceway 3, the second raceway 4, and the rolling element 5 are each made of metal, such as steel.

[0037] As shown in Figure 1, all of the outer surface 3b and both width surfaces 3c of the first raceway ring 3, except for two circumferential regions that are 180° apart in the circumferential direction, are covered by multiple insulating members 2.

[0038] The multiple insulating members 2 all have the same shape and are mirror-symmetric with respect to a virtual radial plane that bisects the axial width of the first raceway ring 3. The insulating members 2 are made from molded products formed seamlessly by injection molding of synthetic resin.

[0039] As shown in Figures 1, 4, and 5, each of the multiple insulating members 2 is provided with a circumferential length of less than half the circumference of the outer diameter of the first raceway ring 3. As shown in Figures 1 and 3, the insulating member 2 consists of an arc-shaped portion 2a that covers the outer circumferential surface 3b of the first raceway ring 3 from the radially outward direction, and retaining portions 2b that protrude radially inward from both axial ends of the arc-shaped portion 2a and engage with the first raceway ring 3 to prevent them from falling off.

[0040] As shown in Figures 4 and 6, the retaining portion 2b consists of a first flange 2c protruding radially from one axial end of the arc-shaped portion 2a and a second flange 2c protruding radially from the other axial end of the arc-shaped portion 2a. As shown in Figure 3, the retaining portion 2b can axially clamp the axial ends 3h on both axial sides of the first raceway ring 3 with both flanges 2c.

[0041] Each flange 2c has a projection 2d that protrudes axially inward so as to fit into the groove 3g of the corresponding first raceway 3, as shown in Figures 1, 3, and 7. The projection 2d can hook onto the axial end 3h of the first raceway 3 from one radial direction to the other.

[0042] The insulating member 2 is fitted between its two flanges 2c relative to the outer circumferential surface 3b of the first raceway 3 from one radial position toward the other radially, and the projections 2d of both flanges 2c are allowed to overcome the corresponding width surfaces 3c and enter the groove 3g, thereby engaging the retaining portion 2b with the first raceway 3. In this way, the insulating member 2 is attached to the first raceway 3 so that it does not fall off.

[0043] As shown in Figure 1, a circumferential distance Lc is provided between adjacent insulating members 2, 2 in the circumferential direction. In this insulated bearing, the first raceway 3 is insulated by two insulating members 2, so by setting the circumferential length of each insulating member 2 to less than half the circumferential length of the outer diameter surface 3e of the first raceway 3, a circumferential distance Lc is provided between the insulating members 2, 2 at two locations in the circumferential direction. The outer circumferential surface 3b and each side surface of the first raceway 3 are partially exposed through the gap of the circumferential distance Lc. Even if the surface portion of the first raceway 3 is exposed at the circumferential distance Lc, it is possible to obtain insulation based on the creepage distance due to the thickness t of the insulating member 2, as shown in Figure 7. The circumferential distance Lc is preferably less than or equal to the ball pitch, and more preferably less than or equal to the thickness t of the insulating member 2. This is because if the circumferential distance Lc is too long, there is a risk that the housing and the raceway will come into contact and conduct electricity.

[0044] When this insulating bearing (see Figures 1 and 3) is positioned between a shaft and housing of another device (not shown), the arc-shaped portions 2a of the multiple insulating members 2 attached to the first raceway 3 are fitted into the corresponding housing and sandwiched between the outer circumferential surface 3b of the first raceway 3 and the inner circumference of the housing. In addition, the first flange 2c or second flange 2c of the multiple insulating members 2 abut against the shoulder of the housing in the axial direction and sandwiched between the corresponding width surface 3c of the first raceway 3 and the shoulder of the housing. When a relative potential difference occurs between the housing and the shaft, a voltage is applied to this insulating bearing. If the thickness of the insulating member 2 is greater than the creepage distance required to insulate the housing from the exposed portion of the first raceway 3, the first raceway 3 and the housing are insulated, thereby preventing electrolytic corrosion of the rolling bearing 1.

[0045] Other devices that incorporate this insulated bearing include, for example, electric motors and e-axles in electric vehicles (EVs). Currently, the system voltage of EV vehicles is mainly 400V, but it is expected that it will 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 insulated bearing interposed between the housing and the shaft is expected to be around 100V. According to the IEC60664-1 Ed2.0 standard, regardless of the material group of the insulating material forming the creepage, if the creepage distance is 0.3 mm, it is possible to insulate up to an effective voltage of 100V. In other words, when configuring this insulated bearing to withstand an applied voltage of 100V, the required thickness of the resin part (creepage distance) from the surface of the first raceway ring 3 is 0.3 mm or more. Therefore, the thickness t of the insulating member 2 (see Figure 7) is set to 0.3 mm or more. This thickness t value is satisfied at all points on the insulating member 2. As a result, a creepage distance of 0.3 mm or more is ensured by the resin surface of the insulating member 2 from the exposed surface of the first raceway ring 3.

[0046] As the resin forming the insulating member 2, 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.

[0047] Furthermore, as the resin forming the insulating member 2, 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).

[0048] A fiber-reinforced resin is used as the resin for forming the insulating member 2. The fiber-reinforced resin is made by dispersing non-conductive fibers such as glass filler and polyamide filler in a matrix resin at a desired ratio. The aforementioned PPA can be used as the matrix resin.

[0049] The insulating member 2 (see Figures 4 and 5) does not contain weld lines. Injection molding methods capable of obtaining such an insulating member 2 include a method in which the mold gate (not shown) is placed only on the side surface of one axial end of the insulating member 2 to make the resin flow direction (MD direction) the same as the axial direction, and a method in which the gate is placed only on one circumferential end face of the insulating member 2 to make the MD direction the same as the circumferential direction.

[0050] The insulating member 2 has a gate mark G on only one end face 2e in the circumferential direction. The gate mark G is a trace of shearing between the solidified resin portion within the gate and the insulating member 2 when the insulating member 2 is ejected from the mold, and it occurs at a position corresponding to the arrangement of the gate in the mold. In other words, the fiber-reinforced resin injected from a gate that opens into the cavity portion forming one end face 2e in the circumferential direction of the insulating member 2 flows in the circumferential direction and fills the cavity portion forming the other end face 2e in the circumferential direction of the insulating member 2. Therefore, the insulating member 2 does not contain weld lines, and the fibers in the resin are generally oriented in the circumferential direction. In Figure 5, the position of the gate mark G is indicated by a black triangle.

[0051] This insulated bearing (see Figures 1, 3, 4, and 7) is as described above and comprises a first raceway 3, a second raceway 4, a plurality of rolling elements 5 positioned between the first raceway 3 and the second raceway 4, and a plurality of insulating members 2 made of resin. Each insulating member 2 has an arc-shaped portion 2a that covers the first raceway 3 from the radially outward direction, and retaining portions 2b that protrude radially inward from both axial ends of the arc-shaped portion 2a and engage with the first raceway 3 to prevent it from falling off. The circumference of each insulating member is set to be less than half the circumference of the outer diameter of the first raceway 3, and the retaining portion 2b includes a projection 2d that protrudes axially inward.

[0052] In this insulated bearing, although the circumference of each insulating member 2 is less than half the circumference of the outer diameter of the first raceway 3, it is attached to the first raceway 3 by a retaining portion 2b including a projection 2d without relying on radial tightening relative to the first raceway 3. Therefore, even if the amount of shrinkage of each insulating member 2 when cold is greater than the amount of shrinkage of the first raceway 3, the first raceway 3 cannot be tightened radially, and excessive circumferential tensile stress is prevented from being generated in each insulating member 2. Consequently, this insulated bearing can prevent defects from occurring in the insulating member 2 due to the difference in the coefficient of linear expansion between the first raceway 3 and the insulating member 2 when the resin insulating member 2 is attached to insulate the first raceway 3.

[0053] Furthermore, in this insulated bearing, a circumferential distance Lc is provided between adjacent insulating members 2 in the circumferential direction, and since the thickness of the insulating members 2 is 0.3 mm or more, it becomes easier to control the dimensional dimensions of the circumferential length of each insulating member 2 compared to when multiple insulating members 2 are arranged without gaps in the circumferential direction. In addition, a creepage distance of 0.3 mm or more is provided from the exposed portion of the first raceway ring 3 by the resin surface of the insulating member 2, so that insulation that can withstand an applied voltage of 100 V can be ensured.

[0054] Furthermore, since the retaining portion 2b of this insulated bearing is provided in a flange shape that protrudes radially from the arc-shaped portion 2a, the retaining portion 2b is sandwiched axially between the mechanical element of the other device into which this insulated bearing is incorporated and the first raceway ring 3, thereby providing insulation between the first raceway ring 3 and the mechanical element with the retaining portion 2b, and eliminating concerns that the insulating member 2 may separate axially from the first raceway ring 3 during use of this insulated bearing.

[0055] Furthermore, in this insulated bearing, a groove 3g extending circumferentially is formed on the side surface of the first raceway 3, and each projection 2d that hooks onto the axial end 3h of the first raceway 3 is positioned to fit into the groove 3g. This allows the projection 2d corresponding to the groove 3g of the first raceway 3 to be inserted and radially hooked onto the axial end 3h of the first raceway 3. Therefore, this bearing device does not require any modification of the internal specifications of the bearing in order to hook the projections 2d, and the circumferential mounting position of the insulating member 2 relative to the first raceway 3 can be made irrelevant.

[0056] Furthermore, this insulated bearing has a retaining portion 2b consisting of a first flange 2c protruding radially from one axial end of the arc-shaped portion 2a and a second flange 2c protruding radially from the other axial end of the arc-shaped portion 2a, and both flanges 2c are provided to axially sandwich the axial ends 3h on both sides of the first raceway 3. The first flange 2c and the second flange 2c each have projections 2d, and grooves 3g are formed on both axial sides of the first raceway 3. This makes it possible to increase the mounting strength of the insulating member 2 compared to the case where the retaining portion 2b is provided only on one axial side of the arc-shaped portion 2a. In addition, even if the mechanical element of another device incorporating this insulated bearing is located on either the axial side of the first raceway 3, the corresponding first flange 2c or second flange 2c can be sandwiched between the first raceway 3 and the mechanical element to provide insulation, and concerns about the insulating member 2 separating axially from the first raceway 3 during use of this insulated bearing are eliminated.

[0057] Furthermore, in this insulated bearing, the strength of the insulating member 2 against circumferential tensile stress can be increased because the insulating member 2 is made of a molded product that does not contain weld lines.

[0058] Furthermore, in this insulated bearing, the insulating member 2 is formed of fiber-reinforced resin, and the insulating member 2 has a gate mark G only on one end face 2e in the circumferential direction of the insulating member 2. This allows the fiber to provide a reinforcing effect against circumferential tensile stress, thereby increasing the strength of the insulating member against circumferential tensile stress.

[0059] In this insulated bearing, the example shown uses a deep groove ball bearing for the rolling bearing 1, but it is also possible to change to other bearing types such as angular contact ball bearings or self-aligning bearings.

[0060] Furthermore, while this insulated bearing shows the case where the first raceway ring 3 to which multiple insulating members 2 are attached is the outer ring, if the first raceway ring is the inner ring, only the radial positional relationship is reversed so that the inner circumferential surface and width surface of the inner ring are covered by multiple insulating members, so the illustration and explanation of this is omitted.

[0061] Furthermore, in this example of an insulated bearing, one projection 2d is provided on each flange 2c of the retaining portion 2b, but the number and arrangement of projections provided on the retaining portion can be changed as appropriate.

[0062] Furthermore, in this insulated bearing, an example was shown in which the retaining portion 2b is composed of both flanges 2c that sandwich the first raceway ring 3 in the axial direction. However, if the required coverage portion of the first raceway ring and the mounting strength of the insulating material necessary for insulating the rolling bearing between the shaft and the housing are satisfied, it is also possible to constitute the retaining portion with only one of the flanges.

[0063] 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]

[0064] 1 Rolling bearing 2. Insulating material 2a Arc-shaped part 2b Retaining part 2c First flange, second flange 2d protrusion 2e End face 3. First orbital ring 3g groove 3h Axial end 4. Second orbital ring 5 Rolling element G Kate marks

Claims

1. It comprises a first raceway, a second raceway, a plurality of rolling elements disposed between the first raceway and the second raceway, and a plurality of insulating members made of resin. Each insulating member has an arc-shaped portion that covers the first raceway from the radially outward direction, and retaining portions that protrude radially inward from both axial ends of the arc-shaped portion and engage with the first raceway to prevent it from falling off. The circumference of each of the aforementioned insulating members is set to be less than or equal to half the circumference of the outer diameter of the first raceway ring. The aforementioned retaining portion is an insulating bearing that includes a projection that protrudes inward in the axial direction.

2. A circumferential distance is provided between adjacent insulating members in the circumferential direction. The insulating bearing according to claim 1, wherein the thickness of the insulating member is 0.3 mm or more.

3. The insulating bearing according to claim 1 or 2, wherein the retaining portion is provided in a flange shape that protrudes radially from the arc-shaped portion.

4. A groove extending circumferentially is formed on the side surface of the first raceway ring. The insulating bearing according to claim 1 or 2, wherein each of the projections that catch on the axial end of the first raceway ring is arranged to fit into the groove.

5. The retaining portion consists of a first flange protruding radially from one axial end of the arc-shaped portion and a second flange protruding radially from the other axial end of the arc-shaped portion, and is provided so as to axially clamp the axial ends on both sides of the first raceway ring with the two flanges. The first flange and the second flange each have the projection, The insulating bearing according to claim 4, wherein the grooves are formed on both axially oriented sides of the first raceway ring.

6. The insulating bearing according to claim 1 or 2, wherein the insulating member is a molded product that does not contain weld lines.

7. The insulating member is formed of fiber-reinforced resin, The insulating bearing according to claim 1 or 2, wherein the insulating member has a gate mark only on one end face in the circumferential direction of the insulating member.

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