Conductive rolling bearing and conductive member
The conductive rolling bearing design with a metal conductive member having a circular outer frame, elliptical inner frame, and crescent-shaped windows addresses the issues of high contact pressure and rigidity, achieving low rotational torque and stable conductivity through flexible axial design and press molding.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NTN CORP
- Filing Date
- 2025-12-23
- Publication Date
- 2026-07-23
AI Technical Summary
Existing electrically conductive rolling bearings face challenges in achieving low rotational torque and stable conductivity due to high contact pressure and rigidity issues with metal shield plates, leading to unstable conductive performance.
A conductive rolling bearing design featuring a metal conductive member with a circular outer frame, elliptical inner frame, and crescent-shaped windows, allowing for low axial rigidity and high circumferential rigidity, reducing contact pressure and rotational torque while maintaining stable conductivity.
The design achieves low rotational torque and stable conductivity by allowing the inner frame to flex axially while maintaining circumferential rigidity, ensuring consistent electrical performance and reducing manufacturing costs through press molding.
Smart Images
Figure JP2025045079_23072026_PF_FP_ABST
Abstract
Description
Electrically Conductive Rolling Bearing and Electrically Conductive Member
[0001] This invention relates to an electrically conductive rolling bearing and an electrically conductive member used for the electrically conductive rolling bearing.
[0002] A rolling bearing that supports the rotating shaft of a device that uses electricity, such as the rotating shaft of an electric motor or the rotating shaft of a speed reducer connected to the electric motor, may cause a spark to occur between the outer ring raceway surface or the inner ring raceway surface and the rolling element surface when an electric current flows through the inside of the bearing, and the damage to the outer ring raceway surface, the inner ring raceway surface, or the rolling element surface gradually progresses due to the spark (electrical erosion).
[0003] As a rolling bearing capable of preventing this electrical erosion, an electrically conductive rolling bearing provided with an electrically conductive member that electrically conducts between the outer ring and the inner ring is known (for example, Patent Documents 1 to 3).
[0004] Each of the electrically conductive rolling bearings of Patent Documents 1 to 3 has an outer ring, an inner ring disposed radially inward of the outer ring, a plurality of rolling elements that rollingly contact an outer ring raceway surface formed on the inner circumference of the outer ring and an inner ring raceway surface formed on the outer circumference of the inner ring, and an electrically conductive member that electrically conducts between the outer ring and the inner ring.
[0005] The electrically conductive member of Patent Document 1 has an annular metal plate, an outer peripheral rubber portion made of conductive rubber vulcanized and adhered to the outer periphery of the metal plate, and an inner peripheral rubber portion made of conductive rubber vulcanized and adhered to the inner periphery of the metal plate. The outer peripheral rubber portion is fixed in a fixing groove formed on the inner circumference of the outer ring, and the inner peripheral rubber portion is in sliding contact with the outer circumference of the inner ring. A plurality of through holes for releasing the pressure inside the bearing to the outside of the bearing during high-speed rotation are formed in the metal plate at intervals in the circumferential direction.
[0006] The electrically conductive members of Patent Documents 2 and 3 are shield plates entirely formed of metal without using conductive rubber. The outer peripheral portion of the shield plate is fixed in a fixing groove formed on the inner circumference of the outer ring, and the inner peripheral portion of the shield plate is in sliding contact with a sliding contact surface formed on the outer circumference of the inner ring. The sliding contact surface is a tapered surface inclined with respect to the direction perpendicular to the axis in Patent Document 2, and a planar surface perpendicular to the axial direction in Patent Document 3.
[0007] Japanese Patent Publication No. 2023-046521, Japanese Patent Publication No. 2011-163356, Japanese Utility Model Publication No. 05-058954 (Figures 1 and 2)
[0008] In Patent Document 1, the conductive member has a portion that slides against the inner ring made of rubber (conductive rubber), which makes it possible to keep the contact pressure of the conductive member against the inner ring low and effectively suppress the rotational torque of the bearing. However, although conductive rubber is conductive, its conductivity is inferior to that of general metals. Therefore, the conductive rolling bearing in Patent Document 1 has a low effect in preventing electrolytic corrosion by the conductive member.
[0009] On the other hand, the conductive member in Patent Document 2 is a shield plate formed entirely of metal without using conductive rubber, and since the part that slides against the inner ring is metal, it has excellent conductivity and a high effect in preventing electrolytic corrosion. However, because the shield plate is made of metal, it has high rigidity, and the contact pressure against the inner ring tends to be high. Therefore, the conductive rolling bearing in Patent Document 2 has the problem of having a large rotational torque.
[0010] Therefore, as an electrically conductive rolling bearing, the one described in Patent Document 3 has been proposed, which uses a metal shield plate with excellent conductivity as an electrically conductive member, as in Patent Document 2, and reduces the rotational torque generated by sliding the shield plate against the inner ring.
[0011] The current-carrying member (shielding plate) of Patent Document 3 has an outer peripheral edge fixed to the outer ring, a plurality of slits extending radially and opening to the inner ring side, and a plurality of sliding contact pieces separated in the circumferential direction by the plurality of slits, the tips of which are pressed axially against the sliding contact surface on the outer circumference of the inner ring and are in sliding contact with it.
[0012] Since this conductive member has multiple slits that extend radially and open towards the inner ring, the portion that slides against the inner ring (the sliding contact piece separated circumferentially by the slits) is relatively easy to deform in the axial direction. Therefore, it is possible to keep the contact pressure of the conductive member against the inner ring relatively low.
[0013] Here, the inventors of the present application investigated whether the contact pressure with the inner ring could be further reduced in the conductive member described in Patent Document 3. To reduce the contact pressure of the conductive member with respect to the inner ring, they considered increasing the number of slits that extend radially and open to the inner ring side, and reducing the spacing between adjacent slits in the circumferential direction (i.e., making each sliding contact piece thinner).
[0014] However, if the number of slits is increased and each sliding contact piece is made thinner, the axial rigidity of each sliding contact piece decreases. Although this reduces the contact pressure of the conductive member against the inner ring, it also reduces the circumferential rigidity of each sliding contact piece. As a result, each sliding contact piece may twist or vibrate circumferentially due to friction with the inner ring, leading to unstable contact between the sliding contact piece and the inner ring. Consequently, the conductive performance of the conductive member may become unstable.
[0015] The problem that this invention aims to solve is to provide a conductive rolling bearing with low rotational torque and stable conductivity of the conductive member.
[0016] In order to solve the above problems, this invention provides an electrically conductive rolling bearing having the following configuration: [Configuration 1] An electrically conductive rolling bearing having an outer ring, an inner ring disposed radially inward of the outer ring, a plurality of rolling elements that roll in contact with the outer ring raceway surface formed on the inner circumference of the outer ring and the inner ring raceway surface formed on the outer circumference of the inner ring, and an electrically conductive member that electrically conducts between the outer ring and the inner ring, wherein a sliding contact surface is formed on the outer circumference of the inner ring with which the electrically conductive member slides, and the sliding contact surface is formed in a tapered shape inclined perpendicular to the axis or in a planar shape perpendicular to the axial direction, wherein the electrically conductive member has a circular outer frame portion, an elliptical inner frame portion with both ends in the major axis direction connected to the inner circumference of the outer frame portion, and a pair of crescent-shaped window portions formed between the inner circumference of the outer frame portion and the outer circumference of the inner frame portion, the radial width of which gradually decreases toward both sides in the circumferential direction from positions corresponding to both ends in the minor axis direction of the inner frame portion, An electrically conductive rolling bearing characterized in that the outer frame portion is fixed to the inner circumference of the outer ring, and both ends of the inner frame portion in the short-axis direction slide in contact with the sliding contact surface.
[0017] With this configuration, a crescent-shaped window is formed between the outer circumference of the elliptical inner frame and the inner circumference of the circular outer frame. Because the inner frame is separated from the outer frame by this crescent-shaped window, except for the ends in the major axis direction, the inner frame can flex in the axial direction, resulting in low axial rigidity of the inner frame. Therefore, it is possible to keep the contact pressure of the conductive member against the inner ring low and reduce the rotational torque of the conductive rolling bearing. In addition, because the elliptical inner frame is connected to the outer frame at two points separated in the circumferential direction (the ends in the major axis direction), the inner frame is less likely to deform in the circumferential direction, resulting in high circumferential rigidity of the inner frame. Therefore, the inner frame (the part of the conductive member that contacts the inner ring) is less likely to twist or vibrate in the circumferential direction due to friction, and the conductive performance of the conductive member is stable.
[0018] [Configuration 2] The electrically conductive rolling bearing according to Configuration 1, wherein the electrically conductive member is a press-formed product of a metal plate in which the outer frame portion and the inner frame portion are integrally formed.
[0019] This configuration allows for the efficient manufacturing of numerous conductive components through press molding of metal sheets, resulting in low costs.
[0020] [Configuration 3] The energized rolling bearing according to Configuration 1 or 2, wherein the pair of crescent-shaped window portions are each formed with a circumferential length corresponding to a central angle of 100° or more.
[0021] With this configuration, the circumferential length of the crescent-shaped window section is long, resulting in a longer circumferential length of the portion of the inner frame that is separated from the outer frame, making the inner frame more prone to axial bending. Therefore, it is possible to effectively reduce the axial rigidity of the inner frame.
[0022] [Configuration 4] An electrically conductive rolling bearing according to any one of Configurations 1 to 3, wherein a crescent-shaped radial gap is formed between the inner circumference of the inner frame and the outer circumference of the inner ring, with the radial width gradually decreasing from positions corresponding to both ends in the long axis direction of the inner frame toward both sides in the circumferential direction.
[0023] By adopting this configuration, it is possible to secure a circumferential length of the inner frame that can flex in the axial direction, thereby effectively reducing the axial rigidity of the inner frame.
[0024] [Configuration 5] The energized rolling bearing according to any one of Configurations 1 to 4, wherein the outer frame portion is formed in a straight shape extending straight in the radial direction in a cross section perpendicular to the circumferential direction, and the outer frame portion is fitted into a fixing groove formed on the inner circumference of the outer ring.
[0025] [Configuration 6] The energized rolling bearing according to any one of Configurations 1 to 4, wherein the outer frame portion has a plurality of notches extending perpendicular to the circumferential direction at regular intervals in the circumferential direction, a plurality of crimped portions formed by folding the portions between adjacent notches in the circumferential direction radially inward, and an annular portion extending in the circumferential direction so as to connect the bases of the plurality of crimped portions, and the crimped portions and the annular portion are fitted into a fixing groove formed on the inner circumference of the outer ring.
[0026] Furthermore, this invention also provides an electrically conductive member for use in the above-mentioned electrically conductive rolling bearing, having the following configuration: [Configuration 7] An electrically conductive member that electrically conducts between the outer ring and the inner ring of a rolling bearing, comprising: a circular outer frame portion; an elliptical inner frame portion with both ends in the major axis direction connected to the inner circumference of the outer frame portion; and a pair of crescent-shaped window portions formed between the inner circumference of the outer frame portion and the outer circumference of the inner frame portion, wherein the outer frame portion is fixed to the inner circumference of the outer ring, and both ends in the minor axis direction of the inner frame portion slide in contact with the sliding contact surface of the outer circumference of the inner ring.
[0027] In this electrically conductive rolling bearing, a crescent-shaped window is formed between the outer circumference of the elliptical inner frame and the inner circumference of the circular outer frame. Because the inner frame is separated from the outer frame by this crescent-shaped window, except for the ends in the major axis direction, the inner frame can flex in the axial direction, resulting in low axial rigidity of the inner frame. Therefore, it is possible to keep the contact pressure of the conductive member against the inner ring low and reduce the rotational torque of the electrically conductive rolling bearing. Furthermore, because the elliptical inner frame is connected to the outer frame at two points separated in the circumferential direction (the ends in the major axis direction), the inner frame is less likely to deform in the circumferential direction, resulting in high circumferential rigidity of the inner frame. Therefore, the inner frame (the part of the conductive member that contacts the inner ring) is less likely to twist or vibrate in the circumferential direction due to friction, and the conductive performance of the conductive member is stable.
[0028] Figure 1 shows a partial cross-sectional view of the energized rolling bearing according to the first embodiment of this invention, cross-sectional view along line II-II in Figure 1, enlarged view of the vicinity of the energized member in Figure 2, a diagram showing the energized member removed from the energized rolling bearing in Figure 1, a diagram showing a modified example of the energized member shown in Figure 4, a diagram showing the energized member, a cross-sectional view of the energized rolling bearing according to the second embodiment of this invention, cross-sectional view along line VII-VII in Figure 6, cross-sectional view along line VIII-VIII in Figure 6, enlarged view of the vicinity of the energized member in Figure 7, a diagram showing the energized member removed from the energized rolling bearing in Figure 6, a diagram showing the process of attaching the energized member to the fixing groove, a diagram showing the state before the crimping portion of the energized member is crimped, and a diagram showing the state after the crimping portion of the energized member is crimped and fitted into the fixing groove, as shown in Figure 11A.
[0029] Figures 1 and 2 show an electrically conductive rolling bearing according to a first embodiment of the present invention. As shown in Figure 2, this electrically conductive rolling bearing includes an outer ring 1, an inner ring 2 coaxially arranged radially inward of the outer ring 1, a plurality of rolling elements 3 mounted between the outer ring 1 and the inner ring 2 at circumferential intervals, a cage 4 that maintains the circumferential intervals of the plurality of rolling elements 3, and an electrically conductive member 5 that electrically conducts between the outer ring 1 and the inner ring 2.
[0030] The axial direction is the direction parallel to the central axis of the outer ring 1 (the central axis of the bearing), the radial direction is the direction perpendicular to the central axis of the outer ring 1, and the circumferential direction is the direction along the circumference that revolves around the central axis of the outer ring 1. The outer ring 1 and the inner ring 2 are formed symmetrically with respect to the axial center. Furthermore, the axial inner side is the side that approaches the center position of the rolling element 3 along the axial direction, and the axial outer side is the side that moves away from the center position of the rolling element 3 along the axial direction.
[0031] The outer ring 1, inner ring 2, and rolling elements 3 are each made of steel. The rolling elements 3 are balls. The rolling elements 3 roll in contact with the outer ring raceway surface 6 formed on the inner circumference of the outer ring 1 and the inner ring raceway surface 7 formed on the outer circumference of the inner ring 2. The outer ring raceway surface 6 and the inner ring raceway surface 7 are the inner surfaces of grooves with an arc-shaped cross-section perpendicular to the circumferential direction. The outer diameter of the outer ring 1 is set within the range of 45 mm to 110 mm.
[0032] As shown in Figure 3, the inner circumference of the outer ring 1 has an outer ring raceway surface 6, an outer ring shoulder portion 8 adjacent to the axially outer side of the outer ring raceway surface 6, a fixing groove 9 adjacent to the axially outer side of the outer ring shoulder portion 8, and a guide surface 10 adjacent to the axially outer side of the fixing groove 9. The outer ring shoulder portion 8 is formed in a constant cylindrical shape with no change in inner diameter along the axial direction.
[0033] The fixing groove 9 has an axially facing inner side surface 11 and an axially outer side surface 12, and a bottom surface 13 connecting the axially inner side surface 11 and the axially outer side surface 12. Both the axially inner side surface 11 and the axially outer side surface 12 of the fixing groove 9 are formed in a planar shape perpendicular to the axial direction. The axially outer groove shoulder height of the fixing groove 9 (the radial dimension from the radially inner end of the guide surface 10 to the bottom surface 13 of the fixing groove 9) is smaller than the axially inner groove shoulder height (the radial dimension from the outer ring shoulder portion 8 to the bottom surface 13 of the fixing groove 9). The axially outer groove shoulder height of the fixing groove 9 is set to 0.5 mm or less. The guide surface 10 is a tapered surface that gradually decreases in diameter toward the axially inward side.
[0034] The outer circumference of the inner ring 2 is formed with an inner ring raceway surface 7, an inner ring shoulder portion 14 adjacent to the axially outer side of the inner ring raceway surface 7, and a sliding contact surface 15 adjacent to the axially outer side of the inner ring shoulder portion 14. The inner ring shoulder portion 14 is formed in a constant cylindrical shape with no change in outer diameter along the axial direction. The sliding contact surface 15 is formed in a tapered shape inclined with respect to the direction perpendicular to the axis. The inclination angle of the sliding contact surface 15 with respect to the direction perpendicular to the axis (the inclination angle of the portion that contacts the conductive member 5) is set in the range of 10° to 30°.
[0035] As shown in Figure 4, the conductive member 5 has a circular outer frame portion 16, an elliptical inner frame portion 17, and a pair of crescent-shaped window portions 18 formed between the inner circumference of the outer frame portion 16 and the outer circumference of the inner frame portion 17. This conductive member 5 is a press-formed metal plate in which the outer frame portion 16 and the inner frame portion 17 are integrally formed, and the entire structure is made of metal (steel, copper, etc.) without using conductive rubber. The thickness of the metal plate forming the conductive member 5 is set to 0.5 mm or less.
[0036] The outer circumference of the outer frame portion 16 is a perfect circle. The inner circumference of the inner frame portion 17 is formed in an elliptical shape, having a major axis direction (left-right direction in the figure) and a minor axis direction (up-down direction in the figure) perpendicular to the major axis direction. Both ends of the inner frame portion 17 in the major axis direction are connected to the inner circumference of the outer frame portion 16.
[0037] Each pair of window sections 18 is formed in a crescent shape, with the radial width gradually decreasing from positions corresponding to both ends in the minor axis direction (up and down direction in the figure) of the inner frame section 17 toward both sides in the circumferential direction (left and right direction in the figure). Each window section 18 is formed with a circumferential length corresponding to a central angle of 100° or more (preferably 115° or more). The central angle of the window section 18 is the angle between the line connecting one circumferential end of the window section 18 and the center of the circle on the outer circumference of the outer frame section 16, and the line connecting the other circumferential end of the window section 18 and the center of the circle on the outer circumference of the outer frame section 16.
[0038] The window portion 18 has a radially outward concave arc edge 20, a radially inward convex arc edge 21, a semicircular R-edge 22 that smoothly connects one circumferential end of the concave arc edge 20 and the convex arc edge 21, and another semicircular R-edge 22 that smoothly connects the other circumferential ends of the concave arc edge 20 and the convex arc edge 21. The concave arc edge 20 and the convex arc edge 21 are radially opposite to each other when viewed from the axial direction.
[0039] As shown in Figure 3, the outer frame portion 16 is formed in a straight shape extending straight in the radial direction in a cross section perpendicular to the circumferential direction, and the outer frame portion 16 is fitted and fixed into the fixing groove 9 of the outer ring 1. In addition, both ends of the inner frame portion 17 in the minor axis direction (up and down direction in the figure) shown in Figure 1 are pressed axially against the sliding contact surface 15 on the outer circumference of the inner ring 2 and are in sliding contact. As shown in Figure 3, the inner frame portion 17 is subjected to axial preload due to contact with the sliding contact surface 15, and is in a state of bending deformation in the axial direction (left and right direction in Figure 3, and perpendicular to the plane of the paper in Figure 4) with both ends of the inner frame portion 17 in the major axis direction (i.e., the parts connected to the outer frame portion 16) as fulcrums.
[0040] As shown in Figure 1, a crescent-shaped radial gap 23 is formed between the inner circumference of the inner frame portion 17 and the outer circumference of the inner ring 2, with the radial width gradually decreasing from positions corresponding to both ends in the long axis direction of the inner frame portion 17 toward both sides in the circumferential direction.
[0041] The energizing member 5 shown in Fig. 4 is inserted axially into the outer ring 1 from the outside in the axial direction of the outer ring 1 shown in Fig. 3, the outer periphery of the outer frame portion 16 is brought into contact with the guide surface 10 on the inner periphery of the outer ring 1, and in this state, the outer frame portion 16 is strongly pressed axially inward, and the outer frame portion 16 is elastically deformed to reduce its diameter by the reaction force received from the guide surface 10, and can be fitted into the fixing groove 9.
[0042] As shown in Fig. 1, in this energized rolling bearing, a crescent-shaped window portion 18 is formed between the outer periphery of the elliptical inner frame portion 17 and the inner periphery of the circular outer frame portion 16. Due to the crescent-shaped window portion 18, the inner frame portion 17 is separated from the outer frame portion 16 except for both end portions in the major axis direction (left - right direction in the figure). Therefore, the inner frame portion 17 can bend in the axial direction (direction perpendicular to the paper surface in the figure), and the axial rigidity of the inner frame portion 17 is small. For this reason, it is possible to keep the contact pressure of the energizing member 5 against the inner ring 2 low and reduce the rotational torque of the energized rolling bearing. Also, since the elliptical inner frame portion 17 is connected to the outer frame portion 16 at two circumferentially separated locations (both end portions in the major axis direction), the inner frame portion 17 is difficult to deform in the circumferential direction, and the circumferential rigidity of the inner frame portion 17 is large. Therefore, the inner frame portion 17 (contact portion of the energizing member 5 with the inner ring 2) is less likely to be twisted or vibrate circumferentially due to friction with the sliding contact surface 15 on the outer periphery of the inner ring 2 (see Fig. 3), and the energizing performance of the energizing member 5 is stable.
[0043] Further, in this energized rolling bearing, the energizing member 5 is a press - formed product of a metal plate, and since a large number of energizing members 5 can be efficiently manufactured by press - forming, the cost is low.
[0044] Also, as shown in Fig. 4, in this energized rolling bearing, a pair of crescent - shaped window portions 18 are formed with a circumferential length corresponding to a central angle of 100° or more (preferably 115° or more) each. Since the circumferential length of the crescent - shaped window portion 18 is long, the circumferential length of the portion where the inner frame portion 17 is separated from the outer frame portion 16 is long, and the inner frame portion 17 is easily bent in the axial direction. Therefore, it is possible to effectively reduce the axial rigidity of the inner frame portion 17.
[0045] Further, as shown in FIG. 1, in this current-carrying slewing bearing, a crescent-shaped radial gap 23 is formed between the inner circumference of the inner frame portion 17 and the outer circumference of the inner ring 2, with the radial width gradually decreasing from positions corresponding to both ends in the major axis direction (left-right direction in the figure) of the inner frame portion 17 toward both circumferential sides (both upper and lower sides in the figure). Therefore, it is possible to ensure the circumferential length of the inner frame portion 17 that can flex in the axial direction and effectively reduce the axial rigidity of the inner frame portion 17.
[0046] Further, as shown in FIG. 3, in this current-carrying slewing bearing, the sliding contact surface 15 on the outer circumference of the inner ring 2 is formed in a tapered shape inclined with respect to the direction perpendicular to the axis, and the inner frame portion 17 is pressed against the sliding contact surface 15 in the axial direction. Therefore, it is possible to effectively reduce the contact pressure of the current-carrying member 5 against the inner ring 2.
[0047] In the above embodiment, as shown in FIG. 4, the current-carrying member 5 having a continuous shape without interruption between the outer frame portion 16 and the inner frame portion 17 over the entire circumference has been described as an example. However, as shown in FIG. 5, it is also possible to adopt a C-shaped current-carrying member 5 provided with a cutting portion 24 that separates one end (right end in the figure) in the major axis direction (left-right direction in the figure) of the inner frame portion 17 from the outer frame portion 16 in the circumferential direction. By doing so, it becomes easier to incorporate the current-carrying member 5 into the outer ring 1.
[0048] FIGS. 6 to 8 show a current-carrying slewing bearing according to the second embodiment of the present invention. The second embodiment differs only in the configuration of the outer frame portion 16 of the current-carrying member 5 and the configuration of the fixing groove 9 on the inner circumference of the outer ring 1 compared to the first embodiment, and the other configurations are basically the same. Therefore, the parts corresponding to the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
[0049] As shown in FIGS. 9 and 10, the outer frame portion 16 has a plurality of cutouts 30 extending in a direction perpendicular to the circumferential direction at regular intervals in the circumferential direction, a plurality of caulking portions 31 formed by folding back the portions between adjacent cutouts 30 in the circumferential direction toward the radially inner side, and an annular portion 32 extending in the circumferential direction so as to connect the bases of the plurality of caulking portions 31. The caulking portions 31 and the annular portion 32 are fitted and fixed in a fixing groove 9 (see FIG. 9) formed in the outer ring 1.
[0050] As shown in Figure 9, the inner circumference of the outer ring 1 has an outer ring raceway surface 6, an outer ring shoulder portion 8 adjacent to the outer ring raceway surface 6 on the axially outer side, a fixing groove 9 adjacent to the outer ring shoulder portion 8 on the axially outer side, and a groove shoulder surface 33 adjacent to the fixing groove 9 on the axially outer side. The axially inner side surface 34 of the fixing groove 9 is formed as a flat surface perpendicular to the axial direction, and the axially outer side surface 35 of the fixing groove 9 is an inclined surface that slopes axially outward toward the radially inward side. The groove shoulder surface 33 is a cylindrical surface with a constant inner diameter.
[0051] As shown in Figure 10, the conductive member 5 is fixed to the fixing groove 9 by crimping the crimping portion 31, as shown in Figures 11A and 11B. Specifically, as shown in Figure 11A, first, the conductive member 5, in its state before crimping the crimping portion 31, is inserted axially into the outer ring 1 from the axially outer side of the outer ring 1, and the annular portion 32 abuts against the axially inner side surface 34 of the fixing groove 9. At this stage, the crimping portion 31 extends straight outwards in the axial direction from the radially outer end of the annular portion 32, and the outer diameter of the crimping portion 31 is the same as or slightly smaller than the inner diameter of the groove shoulder surface 33. Next, as shown in Figure 11B, the crimping portion 31 is pressed radially inward to cause plastic deformation (= crimping). This plastic deformation displaces the root portion of the crimping portion 31 radially outward, allowing the root portion of the crimping portion 31 and the radially outer portion of the annular portion 32 to be fitted into the fixing groove 9.
[0052] This energized rolling bearing provides the same effects and advantages as the first embodiment.
[0053] In the embodiments described above, as shown in Figures 3 and 9, a tapered surface inclined perpendicular to the axis was used as an example to describe the sliding contact surface 15 to which both ends of the inner frame portion 17 of the current-carrying member 5 in the short-axis direction slide against each other. However, it is also possible to use a planar surface perpendicular to the axial direction.
[0054] Furthermore, although the above embodiments were described using examples where the current-carrying members 5 are arranged on both sides in the axial direction, as shown in Figures 2 and 7, the current-carrying members 5 may be arranged on only one side in the axial direction.
[0055] Furthermore, although the above embodiments described an example of a metal plate press-formed product as the conductive member 5, it is also possible to use a resin injection-molded product with a conductive coating as the conductive member 5.
[0056] Furthermore, although the above embodiments have described an example in which balls are used as the rolling elements 3, other shapes of rolling elements 3, such as cylindrical rollers, may also be used.
[0057] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended.
[0058] 1 Outer ring 2 Inner ring 3 Rolling element 5 Conductive member 6 Outer ring raceway surface 7 Inner ring raceway surface 9 Fixing groove 15 Sliding contact surface 16 Outer frame section 17 Inner frame section 18 Window section 23 Radial clearance 30 Notch 31 Crimping section 32 Annular section
Claims
1. An electrically conductive rolling bearing comprising: an outer ring (1); an inner ring (2) disposed radially inward of the outer ring (1); a plurality of rolling elements (3) that roll and contact the outer ring raceway surface (6) formed on the inner circumference of the outer ring (1) and the inner ring raceway surface (7) formed on the outer circumference of the inner ring (2); and an electrically conductive member (5) that electrically conducts between the outer ring (1) and the inner ring (2), wherein a sliding contact surface (15) is formed on the outer circumference of the inner ring (2) with which the electrically conductive member (5) slides, and the sliding contact surface (15) is formed in a tapered shape inclined perpendicular to the axis or in a planar shape perpendicular to the axial direction, The energizing member (5) comprises a circular outer frame portion (16), an elliptical inner frame portion (17) whose major axis ends are connected to the inner circumference of the outer frame portion (16), and a pair of crescent-shaped window portions (18) formed between the inner circumference of the outer frame portion (16) and the outer circumference of the inner frame portion (17), the radial width of which gradually decreases toward both sides in the circumferential direction from positions corresponding to the minor axis ends of the inner frame portion (17), wherein the outer frame portion (16) is fixed to the inner circumference of the outer ring (1), and the minor axis ends of the inner frame portion (17) slide in contact with the sliding contact surface (15).
2. The electrically conductive rolling bearing according to claim 1, wherein the electrically conductive member (5) is a press-formed product of a metal plate in which the outer frame portion (16) and the inner frame portion (17) are integrally formed.
3. The energized rolling bearing according to claim 1 or 2, wherein each of the pair of crescent-shaped window portions (18) is formed with a circumferential length corresponding to a central angle of 100° or more.
4. The energized rolling bearing according to claim 1 or 2, wherein a crescent-shaped radial gap (23) is formed between the inner circumference of the inner frame portion (17) and the outer circumference of the inner ring (2), the radial width of which gradually decreases toward both sides in the circumferential direction from positions corresponding to both ends in the long axis direction of the inner frame portion (17).
5. The energized rolling bearing according to claim 1 or 2, wherein the outer frame portion (16) is formed in a straight shape extending straight in the radial direction in a cross section perpendicular to the circumferential direction, and the outer frame portion (16) is fitted into a fixing groove (9) formed on the inner circumference of the outer ring (1).
6. The energized rolling bearing according to claim 1 or 2, wherein the outer frame portion (16) has a plurality of notches (30) extending perpendicular to the circumferential direction at regular intervals in the circumferential direction, a plurality of crimping portions (31) formed by folding the portions between adjacent notches (30) in the circumferential direction inward in the radial direction, and an annular portion (32) extending in the circumferential direction so as to connect the bases of the plurality of crimping portions (31), and the crimping portions (31) and the annular portion (32) are fitted into a fixing groove (9) formed on the inner circumference of the outer ring (1).
7. An electrically conductive member (5) that electrically conducts between the outer ring (1) and inner ring (2) of a rolling bearing, comprising: a circular outer frame portion (16); an elliptical inner frame portion (17) whose long-axis ends are connected to the inner circumference of the outer frame portion (16); and a pair of crescent-shaped window portions (18) formed between the inner circumference of the outer frame portion (16) and the outer circumference of the inner frame portion (17), wherein the outer frame portion (16) is fixed to the inner circumference of the outer ring (1), and the short-axis ends of the inner frame portion (17) slide in contact with the sliding contact surface (15) on the outer circumference of the inner ring (2).