Shaft grounding member and rolling bearing unit for rolling bearings

Abstract

The present invention provides a shaft grounding member that suppresses the generation of wear particles from conductive members or wear particles associated with the sliding contact between conductive members and mating materials, does not hinder lubricant discharge, ensures conductivity, does not require any new processing on the bearing, and is applicable to existing bearings without restrictions on bearing type. [Solution] The shaft grounding member for rolling bearings is mounted on a rolling bearing unit that has a rolling bearing in which one raceway is a fixed ring and the other raceway is a rotating ring. The shaft grounding member is composed of a spring plate made of a thin sheet of conductive material, which consists of an annular portion, a connecting portion that extends radially continuously from the annular portion, and an elastic portion that bends in the axial direction of the rotating ring from the connecting portion, and a soft conductive member mounted on the elastic portion on the surface facing the rotating member into which the rotating ring is fitted. The soft conductive member is capable of contacting at least a portion of the circumferential surface of the rotating member.

Description

Technical Field

[0002] ,

[0004] , , , , ,

[0003]

[0001] The present invention relates to a shaft grounding member for a rolling bearing, which is mounted to suppress the occurrence of electric erosion or electromagnetic noise of a rolling bearing in a rolling bearing unit, and a rolling bearing unit equipped with the shaft grounding member for a rolling bearing.

Background Art

[0002] ​​​​​​​​​​

[0005] Furthermore, Patent Document 3 proposes an earthing device in which the tip of a broom-shaped conductive fiber is brought into contact with the outer surface of a rotating shaft.

[0006] Furthermore, Patent Document 4 proposes an electrolytic corrosion prevention device in which an annular seat portion that contacts the end face of the bearing outer ring is bent into a wave washer shape, and an elastic conductor having a contact piece that extends from the inside of the annular seat portion and contacts the vicinity of the center of the end face of the rotating shaft is used, and the annular seat portion is superimposed on the end face of the bearing outer ring fitted into the bearing housing, and the contact piece is in contact with the vicinity of the center of the end face of the rotating shaft fitted into the bearing inner ring, and the surface of the annular seat portion is pressed by the lid-shaped wall of the bearing housing to make it electrically conductive.

[0007] Furthermore, Patent Document 5 proposes housing a rod-shaped conductive brush in a support hole provided in one of the two raceway rings, and using an elastic member to bias the tip of the conductive brush toward the other raceway ring, thereby electrically connecting the two raceway rings.

[0008] Patent Document 6 proposes providing a carbon filament shaft grounding brush with its tip in contact with the extension shaft to ground and remove the shaft voltage generated on the shaft, thereby preventing electrolytic corrosion that occurs in the bearing.

[0009] Incidentally, bearings require measures to counter electromagnetic noise generated by electromagnetic interference, and various devices have been proposed to suppress the generation of electromagnetic noise. For example, Patent Document 7 proposes housing a conductive rod-shaped carbon brush between an inner ring and a metal ring, and biasing the tip of the carbon brush, which is attached to the metal ring by a spring, against the inner ring to bring it into sliding contact. This imparts conductive properties to the conductive bearing and also allows the current flowing through the conductive bearing to flow out of the system via the metal ring and brush, thereby eliminating electromagnetic noise.

[0010] Patent Document 8 proposes a conductive device that can dissipate electromagnetic noise by suppressing the formation of an oil film between a conductive rubber lip and a metal housing attached to a rotating shaft using centrifugal force, or by controlling the thickness of the oil film. By suppressing the formation of the oil film or reducing its thickness, the electrical resistance of the oil film is reduced, making it possible to dissipate electromagnetic noise from the rotating shaft to the housing.

[0011] Patent Document 9 proposes improving electromagnetic noise prevention and electrolytic corrosion prevention by ensuring a path for electric charge by having conductive rolling elements roll between the outer and inner rings while the oil film is broken, thereby significantly reducing the impedance between the outer and inner rings, or the entire bearing.

[0012] Patent Document 10 proposes an electromagnetic noise suppression device that electrically connects the metal case of the electric motor and the rotating shaft inside the electric motor using conductive means such as a sliding contact member, thereby diverting electromagnetic noise induced on the rotating shaft to a metal electric motor housing grounded to the vehicle body. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Japanese Patent Publication No. 2011-135720 [Patent Document 2] Japanese Patent Publication No. 2011-135722 [Patent Document 3] Japanese Patent Publication No. 2020-127257 [Patent Document 4] Japanese Patent Publication No. 2002-146568 [Patent Document 5] Japanese Utility Model Publication No. 4-8820 [Patent Document 6] Japanese Patent Publication No. 2017-060401 [Patent Document 7] Japanese Patent Publication No. 2024-130948 [Patent Document 8] Japanese Patent Publication No. 2023-018214 [Patent Document 9] Japanese Patent Publication No. 2022-139252 [Patent Document 10] Japanese Patent Publication No. 2000-244180 [Overview of the Initiative] [Problems that the invention aims to solve]

[0014] However, in all the technologies described in the patent documents, wear particles generated from the conductive member may contaminate the lubricant or grease composition sealed inside for lubrication, potentially damaging the rolling surface or contact surface. Furthermore, the conductive member may damage the mating material, generating wear particles from that material as well.

[0015] To explain in more detail, in Patent Documents 1 and 2, the contact body, elastic body, and housing are made of metal, and metal powder is generated when these slide against each other due to the vibration of the motor. In addition, the contact body, elastic body, and housing need to be installed in the motor housing, and space is required for this.

[0016] Furthermore, in Patent Document 3, the tip of the broom-shaped conductive fiber is brought into contact with the outer surface of the rotating shaft. However, in order to increase the contact area between the tip of the broom-shaped conductive fiber and the rotating shaft compared to simply bringing them into contact, the broom-shaped conductive fiber is brought into contact with the outer surface of the rotating shaft in a bent state. That is, the tip of the broom-shaped conductive fiber is in contact with the outer surface of the rotating shaft with a certain degree of strong pressure, and wear particles are generated. At the same time, the outer surface of the rotating shaft, which is the mating material of the broom-shaped conductive fiber, is also damaged.

[0017] Furthermore, in Patent Document 4, both the elastic conductor and the rotating shaft are made of metal, and metal powder is generated when the two come into contact. At the same time, the end face of the rotating shaft, which is the mating material of the elastic conductor, is damaged.

[0018] In Patent Document 5, since the tip of the rod-shaped conductive brush is in contact with the other track wheel in a biased state, wear powder of the conductive brush is generated. At the same time, the other track wheel, which is the mating material of the conductive brush, is also damaged. Furthermore, it is necessary to form a support hole for accommodating the conductive brush and the elastic member in the track wheel, which imposes a large load on the track wheel.

[0019] In Patent Document 6, since the tip of the shaft grounding brush made of carbon filaments is provided so as to abut on the extension shaft, wear powder of the shaft grounding brush is generated. At the same time, the extension shaft, which is the mating material of the shaft grounding brush, is also damaged.

[0020] Furthermore, in the bearings shown in Patent Documents 1 to 9, frictional heat may be generated due to the sliding contact between the conductive member and the mating material during use, which reduces the durability of the bearing. In addition, with the recent improvement in the performance of motors, the peripheral speed of the rotating member has also increased, so further suppression of temperature rise is required.

[0021] Regarding Patent Document 10, although a wear-resistant member is selected as the sliding contact member, the effect of reducing wear is not sufficient.

[0022] By the way, although a lubricant is usually introduced into the bearing, depending on the structure of the conductive member or the shaft grounding brush, the flow of the lubricant may be obstructed. When the lubricant is excessively supplied into the bearing, the stirring resistance increases, and the temperature and torque rise. Therefore, a shaft grounding member that can appropriately discharge the lubricant is required.

[0023] In recent years, for the purpose of cost reduction and weight reduction, the demand for smaller products has been increasing. As the product is miniaturized, the diameters of the bearing and the rotating body provided in the motor incorporated in the product also become smaller, but the area of the contact portion between the conductive member and the rotating shaft or the inner ring depends on the diameters of the bearing and the rotating body and the shape of the conductive member. Therefore, if the area of the contact portion is designed to be widened in order to improve conductivity, the discharge of the lubricant may be inhibited.

[0024] Therefore, the present invention aims to provide a shaft grounding member that can suppress the generation of wear particles from a conductive member or wear particles and damage to the mating material due to sliding contact between a conductive member and a mating material, ensure excellent conductivity without hindering the discharge of lubricant, reduce the shaft voltage which is the potential difference between a rotating member and a stationary member to prevent electrolytic corrosion of rolling bearings, dissipate electromagnetic noise through the space between the rotating member and the stationary member, and is applicable to existing bearings without restrictions on the type of bearing, as well as a rolling bearing unit equipped with the shaft grounding member. [Means for solving the problem]

[0025] The above objectives of the present invention are achieved by the configurations described in [1] to [6] below.

[0026] [1] A shaft grounding member to be mounted on a rolling bearing unit which has a rolling bearing in which one raceway is a fixed wheel and the other raceway is a rotating wheel, A spring plate made of a thin sheet of conductive material is composed of an annular portion, a connecting portion extending radially continuously from the annular portion, and an elastic portion bending in the axial direction of the rotating wheel from the connecting portion. The elastic portion comprises a soft conductive member mounted on the surface facing the rotating member into which the rotating ring is fitted, The soft conductive member is capable of contacting at least a portion of the circumferential surface of the rotating member. A shaft grounding member for rolling bearings, characterized by the above.

[0027] [2] The shaft grounding member for rolling bearings according to [1], characterized in that the flexible conductive member is composed of at least one selected from a resin-impregnated nonwoven fabric, a nonwoven fabric, a resin-impregnated woven fabric, a woven fabric, a resin-impregnated flexible porous body, and a flexible porous body.

[0028] [3] The shaft grounding member for a rolling bearing according to [1] or [2], characterized in that the annular portion is pressed against the side surface of the fixed ring with a spacer interposed therebetween.

[0029] [4] The shaft grounding member for a rolling bearing according to any one of [1] to [3], characterized in that the spring plate is composed of the annular portion, a single connecting portion extending radially continuously from the annular portion, and an elastic portion that bends from the connecting portion in the axial direction of the rotating wheel.

[0030] [5] The shaft grounding member for a rolling bearing according to [4], characterized in that the elastic portion extends while curving or bending along the circumferential direction of the rotating member.

[0031] [6] A rolling bearing is provided in which one raceway is a fixed ring and the other raceway is a rotating ring, A rolling bearing unit characterized by being fitted with a rolling bearing shaft grounding member described in any one of [1] to [5]. [Effects of the Invention]

[0032] The shaft grounding member of the present invention prevents current from flowing into the bearing, reduces the shaft voltage which is the potential difference between the rotating member and the stationary member, prevents electrolytic corrosion of the rolling bearing, and allows electromagnetic noise to escape through the space between the rotating member and the stationary member. Furthermore, the shaft grounding member has a spring plate, which is composed of an annular portion, a connecting portion extending radially from the annular portion, and an elastic portion that bends axially from the connecting portion in the direction of the rotating wheel. Therefore, the area of ​​the elastic portion can be freely designed, and there is no need to increase the number or size of the connecting portion, so excellent conductivity can be ensured without hindering the discharge of lubricant.

[0033] Furthermore, the shaft grounding member of the present invention does not exert a very strong biasing force on the rotating member by the spring plate of the soft conductive member, and since the soft conductive member attached to the elastic part is made of a soft material, the generation of wear particles can be suppressed, and damage to the mating rotating wheel is also reduced.

[0034] Furthermore, the shaft grounding member of the present invention is highly versatile because it can be applied to existing rolling bearings without any modification to the rolling bearing, and is not limited to any type of rolling bearing. Moreover, the spring plate is thin, which helps to minimize the increase in space required for the bearing unit to which it is installed.

[0035] The bearing unit of the present invention, equipped with the shaft grounding member of the present invention, can ensure excellent conductivity without hindering the discharge of lubricant and can reduce shaft voltage. Furthermore, the bearing unit of the present invention can suppress the generation of wear particles and damage to components, as well as the reduction in durability due to the generation of frictional heat. [Brief explanation of the drawing]

[0036] [Figure 1] Figure 1 shows an example of an axial grounding member according to the first embodiment of the present invention, applied to an inner ring rotating type bearing unit. Figure (A) is a perspective view thereof, and Figure (B) is a front view of (A). [Figure 2] Figure 2 is a perspective view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 1. [Figure 4] Figure 4 shows a shaft grounding member according to a first modification of the first embodiment of the present invention, where Figure (A) is a perspective view thereof and Figure (B) is a front view thereof. [Figure 5] Figure 5 shows a shaft grounding member according to a second modification of the first embodiment of the present invention, where Figure (A) is a perspective view thereof and Figure (B) is a front view thereof. [Figure 6] Figure 6 shows an example of an axial grounding member according to a second embodiment of the present invention, applied to an outer ring rotating type bearing unit. Figure (A) is a perspective view thereof, and Figure (B) is a front view of (A). [Figure 7] Figure 7 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 6. [Modes for carrying out the invention]

[0037] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the embodiments described below, and can be modified and implemented as desired without departing from the spirit of the invention. Hereafter, "shaft grounding member for rolling bearing" will be simply referred to as "shaft grounding member," and "rolling bearing unit" will be simply referred to as "bearing unit."

[0038] (First embodiment: Shaft grounding member and bearing unit for inner ring rotation) Figure 1 shows a shaft grounding member for inner ring rotation according to a first embodiment of the present invention, where Figure (A) is a perspective view thereof and Figure (B) is a front view of Figure (A). Figure 2 is a perspective view showing an example of a rolling bearing equipped with the shaft grounding member shown in Figure 1. Figure 3 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 1.

[0039] The shaft grounding member 1A shown in Figure 1 comprises a spring plate 10A and a soft conductive member 20. The spring plate 10A has an annular portion 11A, a connecting portion 12A that extends continuously from the annular portion 11A toward the radial center, and an elastic portion 13A that bends from the tip of the connecting portion 12A. The elastic portion 13A is composed of a first flat plate portion 13b that extends in the axial direction of the rotating ring of the rolling bearing, which will be described later, and a curved plate portion 13a that extends from the first flat plate portion 13b while curving along the circumferential direction of the shaft (rotating member). That is, the elastic portion 13A extends in the circumferential direction relative to the connecting portion 12A. In this specification, "axial direction of the rotating ring" is synonymous with "axial direction of the rotating member." A linearly extending bent portion 15A is formed between the connecting portion 12A and the first flat plate portion 13b, and notches 17A are formed on both sides of the bent portion 15A, which makes it easier to bend the elastic portion 13A. In addition, notches 18A are formed on both sides of the boundary portion 16A between the first flat plate portion 13b and the curved plate portion 13a, which makes it easier to bend the curved plate portion 13a.

[0040] The spring plate 10A is entirely made of a thin sheet of a conductive material such as metal. When the conductive material is metal, stainless steel is preferred because it is easy to process and less prone to rusting.

[0041] A soft conductive member 20 is attached to the inner diameter side surface of the curved plate portion 13a, that is, the surface facing the shaft, using an adhesive or the like.

[0042] As the flexible conductive member 20, a flexible base material into which a conductive material is mixed or supported, or commercially available products referred to as "conductive sheets" can be used. As the flexible base material, at least one selected from porous materials and resin-impregnated porous materials can be used. As the porous material, paper, cloth, nonwoven fabric, resin sheet, or a soft porous material such as sponge can be used. Of these, it is preferable to use at least one selected from soft porous materials such as nonwoven fabric, woven fabric and sponge, and resin-impregnated soft porous materials such as resin-impregnated nonwoven fabric, resin-impregnated woven fabric and sponge as the base material. When a resin-impregnated porous material is used as the base material for the flexible conductive member 20, the resin coats its skeleton, allowing the flexible conductive member 20 to be strengthened to the desired level while maintaining its flexible properties. Therefore, it is more preferable to use at least one selected from resin-impregnated nonwoven fabrics, resin-impregnated woven fabrics, and resin-impregnated soft porous materials such as sponges as the base material.

[0043] Furthermore, when using a resin-impregnated porous material as the base material, it is preferable to use a thermosetting resin as the resin to impregnate the porous material. Any thermosetting resin that can be impregnated into the base material in a varnish-like form and that is thermosetting can be used, and examples include phenolic resins, modified phenolic resins, epoxy resins, modified epoxy resins, polyimide resins, silicone resins, polyester resins, polyurethane resins, and rubber resins.

[0044] As the conductive material to be mixed into or supported on the soft substrate, it is preferable to use at least one selected from metal fibers such as silver, copper, gold, aluminum, and stainless steel, and their pulverized or powdered forms, as well as conductive carbon fibers, and their pulverized or powdered forms.

[0045] As shown in Figures 2 and 3, the bearing unit 100A according to the first embodiment includes a rolling bearing 50 and is fitted with the shaft grounding member 1A shown in Figure 1. The rolling bearing 50 has an outer ring 51 that constitutes one raceway, an inner ring 52 that constitutes the other raceway, and a plurality of rolling elements (balls) 53 that are held to roll freely between the outer ring 51 and the inner ring 52 by a cage 54. The rolling elements 53 roll smoothly with bearing lubricant such as lubricating oil or grease composition. Here, the rotating ring is the inner ring 52, and a shaft (rotating member) 60 directly connected to a motor (not shown) is fitted to the inner diameter side of the inner ring 52. The outer ring 51 is a stationary ring and is fixed to the housing 70.

[0046] As shown in Figure 3, the annular portion 11A of the spring plate 10A and the spacer 30 are sandwiched between the flange portion 71 and the outer ring 51, which are provided to protrude on the inner diameter side of the housing 70. Therefore, the outer diameter side of the outer ring 51 and the outer peripheral end face 19A of the annular portion 11A of the spring plate 10A are fixed in contact with the housing 70.

[0047] Furthermore, the flexible conductive member 20 is attached to the elastic portion 13A of the spring plate 10A on the surface (lower side in Figure 3) facing the circumferential surface 60a of the shaft 60. Therefore, the flexible conductive member 20 can contact at least a portion of the circumferential surface 60a of the shaft 60. In this embodiment, the curved plate portion 13a extends from the first flat plate portion 13b while curving along the circumferential direction of the shaft 60.

[0048] In an inner ring rotating type bearing unit 100A that does not incorporate a shaft grounding member 1A, current from the motor usually flows through the shaft 60 to the inner ring 52, energizing the rolling elements 53 and the outer ring 51 inside the bearing, causing electrolytic corrosion of the rolling bearing 50. In contrast, in the first embodiment, the soft conductive member 20 of the shaft grounding member 1A is in contact with the circumferential surface 60a of the shaft 60, and the annular portion 11A of the spring plate 10A is electrically connected to the side surface of the outer ring 51 via a conductive spacer 30.

[0049] In the bearing unit 100A configured in this way, current from a motor (not shown) that drives the shaft 60 flows from the shaft 60 to the flexible conductive member 20. The current then flows through the flexible conductive member 20 to the elastic portion 13A, the connecting portion 12A, and the annular portion 11A of the spring plate 10A, and from the annular portion 11A, it flows directly to the grounded housing 70, either through the spacer 30 or the outer ring 51. Since the outer ring 51 has a large contact area with the housing 70, the current that flows through the outer ring 51 does not pass through the rolling elements 53 and flows to the housing 70. In this way, the shaft grounding member 1A grounds the rotating member, the shaft 60, and the fixed member, the housing 70, so that the inside of the bearing is not energized, and the shaft voltage, which is the potential difference between the rotating member and the fixed member, can be significantly reduced. Therefore, electrolytic corrosion of the rolling bearing 50 can be prevented, and electromagnetic noise can be dissipated through the space between the rotating member, the shaft 60, and the fixed member, the housing 70.

[0050] Furthermore, in the shaft grounding member 1A, the area of ​​the elastic portion 13A can be freely designed, and the number and size of the connecting portions 12A can also be freely designed. For example, to increase the area of ​​the elastic portion 13A, it is possible to increase the number of connecting portions 12A or increase their width. However, by reducing the width of the connecting portions 12A or decreasing the number of connecting portions 12A, the area of ​​the elastic portion 13A can be increased without hindering the discharge of lubricant sealed or applied inside the bearing, thereby ensuring excellent conductivity. Moreover, the shaft grounding member 1A according to this embodiment does not require any processing of the rolling bearing, is not limited to the type of rolling bearing, and can be applied to existing rolling bearings, making it extremely versatile. Furthermore, the spring plate 10A is a thin plate, which can also reduce the increase in space required for the bearing unit to which it is installed.

[0051] Furthermore, since the circumferential surface 60a of the shaft 60 is in contact with the soft conductive member 20, the circumferential surface 60a of the shaft 60 is not damaged, and the reduction in the rotational torque of the shaft 60 can be suppressed. In addition, since the biasing force of the soft conductive member 20 on the circumferential surface 60a of the shaft 60 by the spring plate 10A is not very strong, the generation of wear particles can be suppressed.

[0052] As shown in Figure 1(B), the first flat plate portion 13b and the curved plate portion 13a of the elastic portion 13A may be bent at their boundary. When the angle between the first flat plate portion 13b and the tangent near the boundary line of the curved plate portion 13a is defined as the bending angle θ, the bending angle θ should be appropriately set so that the soft conductive member 20 contacts the circumferential surface 60a of the shaft 60. The biasing force of the soft conductive member 20 on the circumferential surface 60a of the shaft 60 can also be adjusted by this bending angle θ. By reducing the bending angle θ, the elastic portion 13A of the shaft grounding member 1A becomes elastically deformed, thereby increasing the biasing force of the soft conductive member 20 on the shaft 60. As a result, the gap between the shaft 60 and the circumferential surface 60a is reduced, and the contact area is increased, thereby stably reducing the axial voltage between the rotating member and the fixed member. Conversely, by increasing the bending angle θ, the biasing force is weakened, and the generation of wear particles can be suppressed. Furthermore, the extension length L of the curved plate portion, the size of the soft conductive member 20, and the curvature of the curved plate portion 13a can also be set as appropriate, and by adjusting these, the aforementioned axial voltage can be reduced more stably.

[0053] In Figure 3, the outer peripheral end surface 19A of the annular portion 11A and the spacer 30 are in contact with the housing 70, but a configuration in which they do not contact the housing 70 is also possible.

[0054] The annular portion 11A and the spacer 30 may be sandwiched between the outer ring 51 by the flange portion 71 or a retaining member that replaces the flange portion 71. In that case, the current flowing through the annular portion 11A flows to the housing 70 via the outer ring 51 or the retaining member.

[0055] Furthermore, although the curved plate portion 13a extends from one side of the first flat plate portion 13b in Figure 1, it may extend from both sides of the first flat plate portion 13b. The shape of the first flat plate portion 13b does not need to perfectly match the curvature of the shaft in the circumferential direction.

[0056] Furthermore, there is no limit to the thickness of the spacer 30, and as long as the connecting portion 12A of the shaft grounding member 1A is configured not to come into contact with the inner ring 52, the annular portion 11A of the shaft grounding member 1A may directly contact the side surface of the outer ring 51 without the spacer 30 being interposed.

[0057] (First modified example of the shaft grounding member for inner ring rotation) Figure 4 shows a first modified example of the shaft grounding member for inner ring rotation shown in Figure 1, where Figure (A) is a perspective view thereof and Figure (B) is a front view of Figure (A). In the first modified example, the elastic portion 13A is a portion that bends in the axial direction of the shaft 60 from the tip of the connecting portion 12A, and extends on both sides of the shaft 60 in the circumferential direction relative to the connecting portion 12A while curving along the surface of the shaft 60.

[0058] (Second modified example of the shaft grounding member for inner ring rotation) Figure 5 shows a second modified example of the shaft grounding member for inner ring rotation shown in Figure 1, where Figure (A) is a perspective view thereof and Figure (B) is a front view of Figure (A). In the second modified example, the elastic portion 13A is composed of a first flat plate portion 13b that is bent in the axial direction of the rolling bearing shaft (rotating member), and a second flat plate portion 13c that extends from the first flat plate portion 13b while bending along the circumferential direction of the rotating member. In Figure 5, the second flat plate portion 13c extends from one side of the first flat plate portion 13b, but it may extend from both sides of the first flat plate portion 13b. Furthermore, in the present invention, the elastic portion may consist of three or more flat plate portions and be repeatedly bent to extend in the circumferential direction of the rotating member.

[0059] As shown in the first and second modified examples above, in this embodiment, the extension length and bending angle can be freely designed, thereby preventing current from flowing into the bearing, more stably reducing the shaft voltage, which is the potential difference between the rotating member and the stationary member, preventing electrolytic corrosion of the rolling bearing, and reducing electromagnetic noise through the space between the rotating member and the stationary member.

[0060] (Second embodiment: Shaft grounding member and bearing unit for outer ring rotation) In the first embodiment, the case in which the inner ring 52 of the rolling bearing 50 is a rotating ring was described, but in the second embodiment, a bearing unit in which the outer ring 51 is a rotating ring will be described. Figure 6 is a diagram showing the shaft grounding member for the rotation of the outer ring, with Figure (A) being a perspective view thereof and Figure (B) being a front view of Figure (A). Figure 7 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 6. In the bearing unit according to the second embodiment, the same reference numerals are used for the same components as in the first embodiment, and their detailed descriptions are omitted or simplified.

[0061] As shown in Figure 6, the shaft grounding member 1B for outer ring rotation comprises a spring plate 10B and a soft conductive member 20. The spring plate 10B has an annular portion 11B, a connecting portion 12B that extends radially outward from the annular portion 11B, and an elastic portion 13B that bends from the tip of the connecting portion 12B. The elastic portion 13B is composed of a first flat plate portion 13b that is bent in the axial direction of the rotating member, which will be described later, and a curved plate portion 13a that extends from the first flat plate portion 13b while curving along the circumferential direction of the rotating member.

[0062] A soft conductive member 20 is attached to the side of the curved plate portion 13a facing the inner circumferential surface 65a of the rotating member 65 using adhesive or the like, and the spring plate 10B and the soft conductive member 20 constitute the shaft grounding member 1B.

[0063] As shown in Figure 7, the bearing unit 100B according to the second embodiment includes a rolling bearing 50 and is fitted with a shaft grounding member 1B. In this embodiment, the inner ring 52 of the rolling bearing 50 is a fixed ring and is fixed to the fixed member 75. The outer ring 51 is a rotating ring and is fitted to a rotating member 65 which is directly connected to a motor (not shown). The shaft grounding member 1B is mounted on the bearing unit 100B with the soft conductive member 20 facing the inner circumferential surface 65a of the rotating member 65.

[0064] Furthermore, the annular portion 11B of the shaft grounding member 1B and the spacer 30 are sandwiched between the flange portion 76 and the inner ring 52, which are provided to protrude from the outer diameter side of the fixing member 75. Therefore, the inner diameter side of the inner ring 52 and the inner circumferential end face 19B of the annular portion 11B on the spring plate 10B are fixed in contact with the fixing member 75.

[0065] The flexible conductive member 20 is mounted on the elastic portion 13B of the spring plate 10B on the surface (upper side in Figure 7) facing the inner circumferential surface 65a of the rotating member 65. Therefore, the flexible conductive member 20 can contact at least a portion of the inner circumferential surface 65a of the rotating member 65. Also, in the second embodiment, similar to the first embodiment, the curved plate portion 13a extends from the first flat plate portion 13b while curving along the circumferential direction of the shaft 60.

[0066] In an outer ring rotating type bearing unit 100B that does not incorporate a shaft grounding member 1B, current from the motor usually flows through the rotating member 65 to the outer ring 51, energizing the inside of the bearing to the rolling elements 53 and inner ring 52, causing electrolytic corrosion of the rolling bearing 50. In contrast, in the second embodiment, the soft conductive member 20 of the shaft grounding member 1B is in contact with the inner circumferential surface 65a of the rotating member 65, and the annular portion 11B of the spring plate 10B is electrically connected to the side surface of the inner ring 52 via a conductive spacer 30.

[0067] In the bearing unit 100B configured in this way, current from a motor (not shown) that drives the rotating member 65 flows to the soft conductive member 20. The current then flows from the rotating member 65 to the soft conductive member 20, then to the elastic portion 13B, connecting portion 12B, and annular portion 11B of the spring plate 10B, and from the annular portion 11B, it flows directly to the grounded fixed member 75, either through the spacer 30 or the inner ring 52. Since the inner ring 52 has a large contact area with the fixed member 75, the current that flows through the inner ring 52 does not pass through the rolling elements 53, but flows to the fixed member 75. By grounding the rotating member 65 and the fixed member 75 in this way, the inside of the bearing is not energized, and the shaft voltage, which is the potential difference between the rotating member and the fixed member, can be significantly reduced. Therefore, electrolytic corrosion of the rolling bearing 50 can be prevented, and electromagnetic noise can be dissipated through the space between the rotating member 65 and the fixed member 75.

[0068] Furthermore, similar to the first embodiment, the area of ​​the elastic portion 13B and the number and size of the connecting portions 12B can be freely designed. Also, since the connecting portion 12B extends radially outward from the annular portion 11B, it is possible to ensure excellent conductivity without hindering the discharge of lubricant sealed or applied inside the bearing. Moreover, the shaft grounding member 1B of the present invention can be applied to existing rolling bearings without any processing of the rolling bearing, and there are no restrictions on the type of rolling bearing, making it extremely versatile. Furthermore, since the spring plate 10B is a thin plate, it is possible to minimize the increase in space required for the bearing unit to which it is installed.

[0069] Furthermore, since the inner circumferential surface 65a of the rotating member 65 is in contact with the soft conductive member 20, the inner circumferential surface 65a of the rotating member 65 is not damaged, and the rotational torque of the rotating member 65 can be reduced. In addition, the biasing force exerted by the spring plate 10B on the side surface of the inner circumferential surface 65a of the rotating member 65 by the soft conductive member 20 is not very strong, so the generation of wear particles can be suppressed.

[0070] Similar to the first embodiment, the biasing force on the inner circumferential surface 65a of the rotating member 65 can be adjusted by appropriately setting the bending angle between the curved plate portion 13a and the first flat plate portion 13b in Figure 6(B). This further improves the effect of reducing the axial voltage between the rotating member 65 and the fixed member 75, and the effect of suppressing the generation of wear particles. Furthermore, the extension length of the curved plate portion 13a, the size of the soft conductive member 20, and the degree of curvature of the curved plate portion 13a can also be appropriately set, and by adjusting these, the aforementioned axial voltage can be reduced more stably.

[0071] Furthermore, in the second embodiment, the inner circumferential end surface 19B of the annular portion 11B and the spacer 30 are in contact with the fixing member 75, but a configuration in which they are not in contact with the fixing member 75 is also possible.

[0072] The annular portion 11B and the spacer 30 may be sandwiched between the inner ring 52 by the flange portion 76 or a retaining member that replaces the flange portion 76. In that case, the current flowing through the annular portion 11B flows to the fixing member 75 via the inner ring 52 or the retaining member.

[0073] Furthermore, there is no limit to the thickness of the spacer 30, and as long as the connecting portion 12B of the shaft grounding member 1B is configured not to come into contact with the outer ring 51, the annular portion 11B of the shaft grounding member 1B may directly contact the side surface of the inner ring 52 without the spacer 30 being interposed.

[0074] Similar to the first modification in the first embodiment described above, the elastic portion 13B may have a continuous curved plate portion and may extend from the tip side of the connecting portion along the circumferential direction on both sides of the rotating member while curving.

[0075] Furthermore, similar to the second modified example in the first embodiment described above, the elastic portion 13B may be composed of a first flat plate portion 13b that is bent in the axial direction of the fixing member of the rolling bearing, and a second flat plate portion that extends from the first flat plate portion while bending along the circumferential direction of the rotating member. The second flat plate portion may extend from one side of the first flat plate portion 13b, or from both sides of the first flat plate portion 13b.

[0076] In this way, by changing the shape of the elastic part and increasing the contact area with the rotating member, it becomes possible to efficiently reduce the shaft voltage, further improving conductivity and reducing electromagnetic noise. In all embodiments, there are no restrictions on the shape of the flexible conductive member 20. Furthermore, the flexible conductive member 20 may consist of multiple small pieces.

[0077] Furthermore, the axial grounding member of the present invention can also be suitably used when only one of the following is required: prevention of electrolytic corrosion and suppression of electromagnetic noise generation.

[0078] In the above embodiment, the case where there is one connecting part was described considering the discharge of lubricant, but in the present invention, the number of connecting parts is not limited to one, and there may be multiple parts. [Explanation of Symbols]

[0079] 1A, 1B Axle grounding member 10A, 10B Spring Plate 11A, 11B Annular section 12A,12B connection part 13A, 13B Elastic part 13a Curved plate part 13b 1st flat plate part 13c 2nd flat plate part 15A bent part 19A Outer edge 19B Inner circumferential end face 20 Flexible conductive material 30 Spacers 50 bearings 51 Outer ring 52 Inner Ring 60 shaft 60a circumferential surface 65 Rotating member 65a Inner surface 70 Housing 71,76 Flange section 75 Fixing member 100A, 100B Bearing Unit

Claims

1. A shaft grounding member that is mounted on a rolling bearing unit having a rolling bearing in which one raceway is a fixed wheel and the other raceway is a rotating wheel, A spring plate made of a thin sheet of conductive material is composed of an annular portion, a connecting portion extending radially continuously from the annular portion, and an elastic portion bending in the axial direction of the rotating wheel from the connecting portion. The elastic portion comprises a soft conductive member mounted on the surface facing the rotating member into which the rotating ring is fitted, The soft conductive member is capable of contacting at least a portion of the circumferential surface of the rotating member. The elastic portion extends along the circumferential direction of the rotating member while curving or bending. A shaft grounding member for rolling bearings, characterized by the above.

2. The shaft grounding member for a rolling bearing according to claim 1, characterized in that the flexible conductive member is composed of at least one selected from a resin-impregnated nonwoven fabric, a nonwoven fabric, a resin-impregnated woven fabric, a woven fabric, a resin-impregnated flexible porous body, and a flexible porous body.

3. The shaft grounding member for a rolling bearing according to claim 1, characterized in that the annular portion is pressed against the side surface of the fixed ring with a spacer interposed therebetween.

4. The shaft grounding member for a rolling bearing according to claim 1, characterized in that the spring plate is composed of the annular portion, a single connecting portion extending radially continuously from the annular portion, and an elastic portion that bends from the connecting portion in the axial direction of the rotating wheel.

5. It is equipped with a rolling bearing in which one raceway is a fixed ring and the other raceway is a rotating ring, A rolling bearing unit characterized by being fitted with a rolling bearing shaft grounding member according to any one of claims 1 to 4.

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