Insulated bearing arrangement

Abstract

An insulating film (20) is provided on the surface of the outer ring (3) to electrically insulate the housing (2) from the outer ring (3), the insulating film (20) has a straight portion (21) having a constant outer diameter in the axial direction provided along the outer periphery of the outer ring (3), an inner peripheral cylindrical surface (24) is formed on the inner periphery of the housing hole (1) and at a position intersecting the axial center line (L) of the rolling element (5), the inner peripheral cylindrical surface (24) is fitted and contacted by the straight portion (21), and the axial length of the contact range (A) of the inner peripheral cylindrical surface (24) with the straight portion (21) is shorter than the entire axial length of the straight portion (21).

Description

Technical Field

[0001] This invention relates to an insulating bearing device for preventing electrolytic corrosion. Background Technology

[0002] In electric vehicles such as EVs (battery electric vehicles) and HEVs (hybrid electric vehicles), an electric motor is used as the prime mover for driving the vehicle. On the other hand, in electric vehicles, an inverter is used to convert the DC power from the battery into AC power in order to supply AC power to the electric motor. In order to achieve high efficiency of the electric motor, the frequency of the AC power supplied to the electric motor is set to a higher frequency.

[0003] Here, if high-frequency alternating current is supplied to the electric motor, the current tends to flow to the rolling bearing that supports the motor's main shaft. Moreover, if the current flows to the rolling bearing, it will generate electric sparks between the raceway surface and the rolling elements, resulting in a gradual damage to the raceway surface caused by these electric sparks (electrolytic erosion).

[0004] Therefore, in order to prevent this electrolytic corrosion, insulated bearings are typically used (e.g., Patent Document 1). An insulated bearing has an outer ring embedded in a housing bore formed in the housing, an inner ring coaxially arranged radially inside the outer ring, and a plurality of rolling elements assembled between the outer ring and the inner ring, with an insulating film provided on the surface of the outer ring to electrically insulate the housing from the outer ring.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-298060

[0006] However, even with an insulating film that electrically insulates the housing from the outer ring, if an alternating voltage is applied between the housing and the outer ring, the housing and outer ring, separated by the insulating film, act as capacitors, repeatedly storing and discharging electricity, thus allowing alternating current to flow into the interior of the rolling bearing. The magnitude of this alternating current increases as the impedance between the housing and the outer ring decreases (i.e., the electrostatic capacitance between them increases). In other words, the magnitude of the alternating current increases as the area of ​​the opposing metal surfaces of the housing and the outer ring separated by the insulating film increases, and also as the distance between their metal surfaces increases.

[0007] Therefore, in order to suppress the magnitude of this alternating current, as described in Patent Document 1, ... Figure 1As in (a), an insulated bearing is proposed, wherein a recess is provided at the axial center of the outer peripheral surface of the outer ring, and an insulating film of constant thickness is provided on the surface of the outer ring including the recess. Here, the insulating film has an outer peripheral facet provided along the outer periphery of the outer ring, a pair of end faces provided along the axial sides of the outer ring, and a pair of chamfered portions with an arc-shaped cross section connecting the outer peripheral facet and the pair of end faces. Moreover, the outer peripheral facet of the insulating film is recessed in a shape that matches the recessed portion of the outer periphery of the outer ring.

[0008] If the patent document 1 is adopted Figure 1 The insulated bearing of (a) increases the distance between the housing and the metal surface of the outer ring, which are separated by an insulating film, by a recessed portion provided at the axial center of the outer circumferential surface of the outer ring. As a result, the impedance between the housing and the outer ring increases by an amount equivalent to the depth of the recess, thereby suppressing the magnitude of the alternating current flowing into the interior of the rolling bearing when an alternating voltage is applied between the housing and the outer ring to a lower level.

[0009] However, as in Patent Document 1 Figure 1 As shown in (a), if a recess is provided at the axial center of the outer circumferential surface of the outer ring, and an insulating film is provided on the surface of the outer ring including the recess, the formability of the insulating film is poor. Therefore, there is a problem of low mass production of insulated bearings.

[0010] That is, if a recess is to be set in the axial center of the outer circumference of the outer ring, and an insulating film is to be formed on the surface of the outer ring including the recess, it is difficult to form a uniform and stable film inside and outside the recess, resulting in low mass production capability. Summary of the Invention

[0011] The problem to be solved by the present invention is to provide an insulating bearing device with high impedance between the housing and the outer ring and high formability of the insulating film.

[0012] To address the aforementioned issues, the present invention provides an insulated bearing device with the following structure.

[0013] An insulated bearing device, characterized in that it comprises:

[0014] The shell, wherein the aforementioned shell has a shell hole;

[0015] The outer ring is embedded in the aforementioned housing hole;

[0016] The inner ring, which is coaxially arranged radially inside the outer ring; and

[0017] Multiple rolling elements are assembled between the outer ring and the inner ring.

[0018] An insulating film is provided on the surface of the outer ring to electrically insulate the housing from the outer ring.

[0019] The insulating film described above has a straight portion with a constant outer diameter in the axial direction, disposed along the outer periphery of the outer ring; a pair of end portions disposed on the end faces on both sides of the outer ring in the axial direction; and a pair of chamfered portions with an arc-shaped cross section connecting the straight portion and the pair of end portions.

[0020] An inner cylindrical surface is formed on the inner circumference of the aforementioned housing bore, at a position intersecting the axial centerline of the aforementioned rolling element. The aforementioned inner cylindrical surface is used for the aforementioned straight portion to fit and contact.

[0021] The axial length of the contact area between the inner cylindrical surface and the straight section is shorter than the total axial length of the straight section.

[0022] Accordingly, the straight portion of the insulating film disposed along the outer periphery of the outer ring does not contact the inner circumferential cylindrical surface of the housing bore along its entire axial length, but rather within a range shorter than the entire axial length of the straight portion of the insulating film. Therefore, corresponding to the shortened contact range, the impedance between the housing and the outer ring increases. Thus, the magnitude of the alternating current flowing between the housing and the outer ring when an alternating voltage is applied can be effectively suppressed to a lower level. Furthermore, since the portion of the insulating film disposed along the outer periphery of the outer ring is formed in a straight portion with a constant outer diameter in the axial direction, the insulating film is easier to form due to the absence of recesses, resulting in excellent mass production capabilities.

[0023] For example, the following structure can be adopted as a structure in which the axial length of the contact range between the inner circumferential cylindrical surface and the straight section is shorter than the total axial length of the straight section.

[0024] The aforementioned inner cylindrical surface has one axial end and the other end.

[0025] The aforementioned end of the inner circumferential cylindrical surface is located at a position offset axially away from the axial centerline of the rolling element relative to the axial end of the aforementioned straight portion.

[0026] The other end of the aforementioned inner circumferential cylindrical surface is located at a position offset axially toward the side closest to the axial centerline of the aforementioned rolling element, relative to the other end of the aforementioned straight portion.

[0027] The housing has an axial inner end face that extends radially inward from one end of the inner circumferential cylindrical surface and contacts one of the pair of end faces, and a non-contact surface that extends radially outward from the other end of the inner circumferential cylindrical surface.

[0028] Accordingly, the outer ring can be axially positioned by the inner end face of the housing, and the resistance between the housing and the outer ring can be increased.

[0029] Furthermore, for example, the following structure can be adopted as a structure in which the axial length of the contact range between the inner cylindrical surface and the straight section is shorter than the total axial length of the straight section.

[0030] The aforementioned inner cylindrical surface has one axial end and the other end.

[0031] The aforementioned end of the inner cylindrical surface is located at a position offset axially from the axial centerline of the aforementioned straight portion relative to the axial end of the aforementioned straight portion.

[0032] The other end of the aforementioned inner circumferential cylindrical surface is located at a position offset axially toward the side closest to the axial centerline of the aforementioned rolling element, relative to the other end of the aforementioned straight portion.

[0033] The aforementioned housing has a first non-contact surface extending radially outward from one end of the aforementioned inner circumferential cylindrical surface, and a second non-contact surface extending radially outward from the other end of the aforementioned inner circumferential cylindrical surface.

[0034] Accordingly, the area between the shell and the outer ring, which are separated by an insulating film, can be reduced particularly effectively, thereby effectively increasing the impedance between the shell and the outer ring.

[0035] In this case, the housing may further have a first auxiliary support portion that supports the outer periphery of the straight portion at a position axially away from the first non-contact surface, and a second auxiliary support portion that supports the outer periphery of the straight portion at a position axially away from the second non-contact surface.

[0036] Therefore, the support of the outer ring remains stable even when there is a misalignment between the center of the housing bore and the center of the rotating shaft.

[0037] Preferably, the inner circumferential cylindrical surface is formed such that the major axis of the contact ellipse formed by the contact between the rolling element and the outer ring falls within the contact range between the inner circumferential cylindrical surface and the straight portion.

[0038] Therefore, when a large load is applied between the rotating shaft and the housing, the support of the housing bore to the outer ring remains stable.

[0039] In the insulating bearing device of the present invention, the straight portion of the insulating film provided along the outer periphery of the outer ring does not contact the inner circumferential cylindrical surface of the housing bore along the entire axial length of the straight portion of the insulating film, but rather contacts the inner circumferential cylindrical surface of the housing bore within a range shorter than the entire axial length of the straight portion of the insulating film. Therefore, corresponding to the shortened contact range, the impedance between the housing and the outer ring becomes higher. Thus, the magnitude of the alternating current flowing between the housing and the outer ring when an alternating voltage is applied can be effectively suppressed to a lower level. In addition, the portion of the insulating film provided along the outer periphery of the outer ring is formed in a straight portion with a constant outer diameter in the axial direction. Since there is no recess in the insulating film, the forming of the insulating film is easier, resulting in excellent mass production capabilities. Attached Figure Description

[0040] Figure 1 This is a cross-sectional view showing the insulating bearing device according to the first embodiment of the present invention.

[0041] Figure 2 yes Figure 1 Enlarged sectional view.

[0042] Figure 3 Is with Figure 2 The diagram correspondingly illustrates the insulating bearing device of the second embodiment of the present invention.

[0043] Figure 4 It means Figure 3 A diagram showing a modified example of the insulated bearing device.

[0044] Figure 5 It means Figure 2 A diagram showing a modified example of the insulated bearing device.

[0045] Figure 6 Is with Figure 2 A diagram corresponding to the insulated bearing device of the comparative example is shown. Detailed Implementation

[0046] Figure 1 This describes an insulated bearing device according to a first embodiment of the present invention. The insulated bearing device includes: a housing 2 having a housing bore 1; an outer ring 3 inserted into the housing bore 1; an inner ring 4 coaxially disposed radially inside the outer ring 3; a plurality of rolling elements 5 assembled between the outer ring 3 and the inner ring 4; a retainer 6 maintaining the circumferential spacing of the plurality of rolling elements 5; and a rotating shaft 7 fitted with the inner ring 4. The outer ring 3, inner ring 4, and rolling elements 5 are all made of metal. The rolling elements 5 are balls.

[0047] The rotating shaft 7 is the main shaft of the electric motor used for driving the electric vehicle. The rotating shaft 7 has a small-diameter shaft portion 8 that fits into the inner circumference of the inner ring 4, and a large-diameter shaft portion 9 that contacts the axial end face of the inner ring 4. The outer diameter of the large-diameter shaft portion 9 is larger than the outer diameter of the small-diameter shaft portion 8. The rotating shaft 7 is made of metal. The housing 2 is also made of metal.

[0048] An inner ring raceway groove 10 for rolling contact of the rolling elements 5 and inner ring shoulders 11 located on both axial sides of the inner ring raceway groove 10 are formed on the outer circumference of the inner ring 4. An outer ring raceway groove 12 for rolling contact of the rolling elements 5 and outer ring shoulders 13 located on both axial sides of the outer ring raceway groove 12 are also formed on the inner circumference of the outer ring 3. Both the inner ring raceway groove 10 and the outer ring raceway groove 12 are grooves with a circular arc cross-section.

[0049] like Figure 2 As shown, a cylindrical surface 14 with a constant outer diameter in the axial direction is formed on the outer periphery of the outer ring 3, and a chamfered portion 16 with an arc-shaped cross section connecting the cylindrical surface 14 to the end faces 15 on both sides of the outer ring 3 in the axial direction. The cylindrical surface 14 is a complete cylindrical surface without any depressions.

[0050] An insulating film 20, which electrically insulates the housing 2 from the outer ring 3, is provided on the surface of the outer ring 3. The insulating film 20 can be a ceramic film. As a ceramic, metal oxides such as alumina (Al2O3), titanium dioxide (TiO2), and chromium oxide (Cr2O3) can be used. In addition to ceramics, the insulating film 20 can also be formed from resins such as epoxy resin and polyamide-imide resin. The epoxy resin or polyamide-imide resin film can be formed by firing a substance in which a curing agent has been added. The thickness of the insulating film 20 can be set within the range of 0.15 mm to 0.45 mm.

[0051] The insulating film 20 has a straight portion 21 with a constant outer diameter in the axial direction, which is provided along the outer periphery of the outer ring 3; a pair of end faces 22 provided on both sides of the end faces 15 along the axial direction of the outer ring 3; and a pair of chamfered portions 23 with an arc-shaped cross section connecting the straight portion 21 and the pair of end faces 22. The outer periphery of the straight portion 21 is a complete cylindrical surface without any recesses.

[0052] The housing 2 has an inner circumferential cylindrical surface 24, an axial inner end face 25, and a non-contact surface 26. The inner circumferential cylindrical surface 24 is a cylindrical inner surface with a constant inner diameter in the axial direction, formed on the inner circumference of the housing bore 1. The inner circumferential cylindrical surface 24 is formed at a position intersecting the axial centerline L of the rolling element 5. The straight portion 21 of the insulating film 20 is engaged and in contact with the inner circumferential cylindrical surface 24.

[0053] One axial end of the inner circumferential cylindrical surface 24 (left end in the figure) is located offset from the axial end of the straight portion 21 of the insulating film 20 (left end in the figure) on the side away from the axial centerline L of the rolling element 5 (left side in the figure). The other axial end of the inner circumferential cylindrical surface 24 (right end in the figure) is located offset from the other axial end of the straight portion 21 of the insulating film 20 (right end in the figure) on the side closer to the axial centerline L of the rolling element 5 (left side in the figure).

[0054] The axial inner end face 25 of the housing 2 is formed to extend radially inward from one end (left end in the figure) of the inner circumferential cylindrical surface 24. The axial inner end face 25 contacts one of the two end faces 22 of the insulating film 20 (the left end face 22). The non-contact surface 26 of the housing 2 is formed to extend radially outward from the other end (right end in the figure) of the inner circumferential cylindrical surface 24.

[0055] The axial length of the contact range A between the inner circumferential cylindrical surface 24 and the straight portion 21 is shorter than the total axial length of the straight portion 21. Here, the inner circumferential cylindrical surface 24 is formed such that the major axis range B of the contact ellipse formed by the contact between the rolling element 5 and the outer ring 3 falls within the contact range A between the inner circumferential cylindrical surface 24 and the straight portion 21. The contact ellipse is an elliptical surface contact portion formed between the rolling element 5 and the outer ring 3 when a load is applied between them. Its dimensions are calculated based on the longitudinal elastic modulus and Poisson's ratio of the outer ring 3, the longitudinal elastic modulus and Poisson's ratio of the rolling element 5, the curvature of the surface of the outer ring raceway groove 12, the curvature of the surface of the rolling element 5, and the magnitude of the load acting between the rolling element 5 and the outer ring 3, and according to the formula of Hertz theory. When calculating the dimensions of the contact ellipse, the magnitude of the load acting between the rolling element 5 and the outer ring 3 can be obtained using the basic static radial rated load.

[0056] The outer ring 3, inner ring 4, and rolling elements 5 constitute a deep groove ball bearing. This deep groove ball bearing positions the outer ring 3 on one side of the axial direction via the axial inner end face 25 of the housing 2, and positions the inner ring 4 on the other side of the axial direction via the large-diameter shaft portion 9 of the rotating shaft 7, thus achieving overall axial positioning. Here, the end portion 22 of the insulating film 20 on the other side (right side in the figure) of the end face 15 on both axial sides of the outer ring 3 is exposed, and there are no parts to contact it. Similarly, the end face 17 on one side (left side in the figure) of the end face 17 on both axial sides of the inner ring 4 is also exposed, and there are no parts to contact it.

[0057] However, even with an insulating film 20 that electrically insulates between the housing 2 and the outer ring 3, if an alternating voltage is applied between the housing 2 and the outer ring 3, the housing 2 and the outer ring 3, separated by the insulating film 20, repeatedly store and discharge electricity as capacitors, resulting in an alternating current flowing into the interior of the rolling bearing. The magnitude of this alternating current is greater when the impedance between the housing 2 and the outer ring 3 is lower (i.e., the electrostatic capacitance between the housing and the outer ring is greater). In other words, the magnitude of the alternating current is greater when the area of ​​the opposing metal surfaces of the housing 2 and the outer ring 3 separated by the insulating film 20 is larger, and also greater when the distance between the metal surfaces of the housing 2 and the outer ring 3 separated by the insulating film 20 is closer.

[0058] Therefore, in the insulating bearing device of this embodiment, in order to increase the impedance between the housing 2 and the outer ring 3 (i.e., reduce the electrostatic capacitance between the housing 2 and the outer ring 3), such as Figure 2 As shown, the axial length of the contact range A between the inner circumferential cylindrical surface 24 and the straight portion 21 is shorter than the total axial length of the straight portion 21. Accordingly, the straight portion 21 of the insulating film 20, which is provided along the outer circumference of the outer ring 3, does not contact the inner circumferential cylindrical surface 24 of the housing hole 1 along its entire axial length, but rather contacts the inner circumferential cylindrical surface 24 of the housing hole 1 within a range shorter than the total axial length of the straight portion 21 of the insulating film 20. Therefore, as... Figure 6 As shown, compared to the case where the entire axial length of the straight portion 21 of the insulating film 20 contacts the inner circumferential cylindrical surface 24 of the housing hole 1, the contact range A between the inner circumferential cylindrical surface 24 and the straight portion 21 is shorter. Consequently, the impedance between the housing 2 and the outer ring 3 increases accordingly. Therefore, the magnitude of the alternating current flowing between the housing 2 and the outer ring 3 when an alternating voltage is applied can be effectively suppressed to a lower level.

[0059] Furthermore, in this insulated bearing device, the portion of the insulating film 20 disposed along the outer periphery of the outer ring 3 is formed in a straight section 21 with a constant outer diameter in the axial direction. Since there are no recesses in the insulating film 20, its forming is easy, resulting in excellent mass production capabilities. Additionally, it is designed for low cost.

[0060] In addition, the insulating bearing device positions the outer ring 3 in the axial direction through the axial inner end face 25 of the housing 2, and can improve the impedance between the housing 2 and the outer ring 3.

[0061] In addition, this insulated bearing device has excellent heat dissipation because the area of ​​the portion of the insulating film 20 of the outer ring 3 that is not in contact with other components is large.

[0062] Furthermore, since the major axis range B of the contact ellipse formed by the contact between the rolling element 5 and the outer ring 3 falls within the contact range A between the inner circumferential cylindrical surface 24 and the straight portion 21, the support of the outer ring 3 by the housing bore 1 is stable even when a large load is applied between the rotating shaft 7 and the housing 2.

[0063] Figure 3 This indicates the insulating bearing device according to the second embodiment of the present invention. The parts corresponding to those in the first embodiment are labeled with the same reference numerals, and descriptions are omitted.

[0064] A positioning ring 18 is fixedly provided on the small diameter shaft portion 8 of the rotating shaft 7. The positioning ring 18 contacts the end face 17 on both sides of the axial direction of the inner ring 4 and the end face 17 on the opposite side (left side in the figure) of the end face 17 that contacts the side of the large diameter shaft portion 9 of the rotating shaft 7.

[0065] The housing 2 has an inner cylindrical surface 24, a first non-contact surface 27, and a second non-contact surface 28. The inner cylindrical surface 24 is a cylindrical inner surface with a constant inner diameter in the axial direction, formed on the inner circumference of the housing bore 1. The inner cylindrical surface 24 is formed at a position intersecting the axial centerline L of the rolling element 5. The straight portion 21 of the insulating film 20 is engaged and in contact with the inner cylindrical surface 24.

[0066] One axial end of the inner circumferential cylindrical surface 24 (left end in the figure) is offset from the axial end of the straight portion 21 of the insulating film 20 (left end in the figure) on one side (right side in the figure) closer to the axial centerline L of the rolling element 5. The other axial end of the inner circumferential cylindrical surface 24 (right end in the figure) is offset from the other axial end of the straight portion 21 of the insulating film 20 (right end in the figure) on one side (left side in the figure) closer to the axial centerline L of the rolling element 5. The axial length of the inner circumferential cylindrical surface 24 is shorter than the axial length of the straight portion 21 of the insulating film 20.

[0067] The first non-contact surface 27 of the housing 2 is formed to extend radially outward from one end (left end in the figure) of the inner circumferential cylindrical surface 24. The second non-contact surface 28 of the housing 2 is also formed to extend radially outward from the other end (right end in the figure) of the inner circumferential cylindrical surface 24.

[0068] The axial length of the contact range A between the inner circumferential cylindrical surface 24 and the straight portion 21 is shorter than the total axial length of the straight portion 21. Here, the inner circumferential cylindrical surface 24 is formed such that the major axis range B of the contact ellipse formed by the contact between the rolling element 5 and the outer ring 3 falls within the contact range A between the inner circumferential cylindrical surface 24 and the straight portion 21.

[0069] The outer ring 3, inner ring 4, and rolling elements 5 constitute a deep groove ball bearing. This deep groove ball bearing positions the inner ring 4 axially to one side via a locating ring 18 fixed to the small-diameter shaft portion 8 of the rotating shaft 7, and to the other axially via the large-diameter shaft portion 9 of the rotating shaft 7, thus achieving overall axial positioning. Here, the pair of end faces 22 of the insulating film 20 on both axially opposite end faces 15 of the outer ring 3 are exposed, and there are no parts that need to contact each other.

[0070] Similar to the first embodiment, the impedance between the housing 2 and the outer ring 3 of this insulated bearing device is relatively high. Therefore, the magnitude of the alternating current flowing between the housing 2 and the outer ring 3 when an alternating voltage is applied can be effectively suppressed to a low level.

[0071] Furthermore, in this insulated bearing device, the portion of the insulating film 20 disposed along the outer periphery of the outer ring 3 is formed in a straight section 21 with a constant outer diameter in the axial direction. Since the insulating film 20 has no recesses, its forming is easy, resulting in excellent mass production capabilities. Additionally, it is designed for low cost.

[0072] In addition, since neither one end of the axial direction of the straight portion 21 of the insulating film 20 nor the other end of the insulating film 20 contacts the housing 2, the insulating bearing device can effectively reduce the opposing area between the housing 2 and the outer ring 3 separated by the insulating film 20, thereby effectively increasing the impedance between the housing 2 and the outer ring 3.

[0073] In addition, this insulated bearing device has excellent heat dissipation because the large exposed area of ​​the insulating film 20 of the outer ring 3 is not in contact with other components.

[0074] Figure 4 This illustrates a variation of the second embodiment. The housing 2 further includes a first auxiliary support portion 29 that supports the outer periphery of the straight portion 21 at a position axially away from the first non-contact surface 27, and a second auxiliary support portion 30 that supports the outer periphery of the straight portion 21 at a position axially away from the second non-contact surface 28. Accordingly, the support of the outer ring 3 is stable even when there is a misalignment between the center of the housing bore 1 and the center of the rotation shaft 7. The first auxiliary support portion 29 and the second auxiliary support portion 30 are shown in the figure as protrusions provided on the inner periphery of the housing bore 1.

[0075] Figure 5 This illustrates a variation of the first embodiment. The housing 2 has an axially projecting annular protrusion 31 on its inner end face 25. The front end of this protrusion 31 contacts one of the two end faces 22 of the insulating film 20 (the left end face 22). Accordingly, the opposing area between the housing 2 and the outer ring 3, separated by the end faces 22 of the insulating film 20, is reduced, thus further increasing the impedance between the housing 2 and the outer ring 3.

[0076] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the invention is set forth in the claims, rather than in the foregoing description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0077] Explanation of reference numerals in the attached figures

[0078] 1…Housing bore; 2…Housing; 3…Outer ring; 4…Inner ring; 5…Rolling element; 20…Insulating film; 21…Straight section; 22…End section; 23…Chamfered section; 24…Inner circumferential cylindrical surface; 25…Axial inner end face; 26…Non-contact surface; 27…First non-contact surface; 28…Second non-contact surface; 29…First auxiliary support; 30…Second auxiliary support; A…Contact range; B…Major axis range of the contact ellipse; L…Axial centerline.

Claims

1. An insulated bearing device, characterized in that, have: The housing (2) has a housing hole (1). Outer ring (3), the outer ring (3) is embedded in the housing hole (1); Inner ring (4), said inner ring (4) being arranged coaxially on the radially inner side of said outer ring (3); and Multiple rolling elements (5) are assembled between the outer ring (3) and the inner ring (4). An insulating film (20) is provided on the surface of the outer ring (3) to electrically insulate the housing (2) from the outer ring (3). The insulating film (20) has a straight portion (21) with a constant outer diameter in the axial direction, which is provided along the outer periphery of the outer ring (3), a pair of end faces (22) provided along the end faces (15) on both sides of the outer ring (3) in the axial direction, and a pair of chamfered portions (23) with an arc-shaped cross section connecting the straight portion (21) and the pair of end faces (22). An inner cylindrical surface (24) is formed on the inner circumference of the housing hole (1) at a position intersecting with the axial center line (L) of the rolling element (5). The inner cylindrical surface (24) is for the straight portion (21) to fit and contact. The axial length of the contact area (A) between the inner circumferential cylindrical surface (24) and the straight portion (21) is shorter than the total axial length of the straight portion (21). The inner circumferential cylindrical surface (24) has one axial end and the other axial end. One end of the inner circumferential cylindrical surface (24) is located relative to the axial end of the straight portion (21) at a position offset axially toward the side close to the axial centerline (L) of the rolling element (5). The other end of the inner circumferential cylindrical surface (24) is located relative to the other end of the straight portion (21) in the axial direction, offset to one side from the axial centerline (L) of the rolling element (5). The housing (2) has a first non-contact surface (27) extending radially outward from one end of the inner circumferential cylindrical surface (24) and a second non-contact surface (28) extending radially outward from the other end of the inner circumferential cylindrical surface (24).

2. The insulating bearing device according to claim 1, characterized in that, The housing (2) further has a first auxiliary support (29) that supports the outer periphery of the straight portion (21) at a position axially away from the first non-contact surface (27), and a second auxiliary support (30) that supports the outer periphery of the straight portion (21) at a position axially away from the second non-contact surface (28).

3. The insulating bearing device according to claim 1 or 2, characterized in that, The inner circumferential cylindrical surface (24) is formed such that the major axis range (B) of the contact ellipse formed by the contact between the rolling element (5) and the outer ring (3) falls within the contact range (A) between the inner circumferential cylindrical surface (24) and the straight portion (21).

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