Shaft grounding member and rolling bearing unit for rolling bearings

Abstract

The present invention provides a shaft grounding member and a rolling bearing unit equipped with the shaft grounding member, which suppress the generation of wear particles from conductive members or wear particles due to sliding contact between conductive members and mating materials, as well as suppress damage to the mating material and temperature rise due to sliding, without forming new processing on the bearing and without restrictions on the type of bearing, and which can be used with existing bearings. [Solution] The shaft grounding member for the rolling bearing comprises a spring plate composed of an annular portion and one or more elastic portions extending radially from the annular portion, and a soft conductive member that contains a lubricant in advance and is mounted on the surface of the elastic portion facing the rotating wheel, and the soft conductive member is capable of contacting the side surface of the rotating wheel. The rolling bearing unit also includes the shaft grounding member.

Description

Technical Field

[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] In recent years, the practical application of electric vehicles that drive wheels by arranging an electric motor as a drive source inside or near the wheels has been progressing. Such a drive motor is generally called an in-wheel motor. The structure of a general in-wheel motor is such that a stator (stator) is fixed to a motor housing, and a rotor (rotor) is arranged with a gap in the radial direction on the inner diameter side of the stator, which is a so-called inner rotor type motor. Further, as a driving method of an in-wheel motor, a brushless DC motor driven by an inverter is widely used in consideration of the performance and control performance of the motor.

[0003] In a driving method using an inverter, a potential difference occurs between the stator and the rotor due to a parasitic capacitance or the like between the stator and the rotor. Due to this potential difference, so-called shaft voltage and shaft current are generated. When this shaft current passes through a rolling bearing that supports the rotor, a phenomenon called "electric erosion" that damages the rolling bearing occurs. Specifically, current flows locally at the contact portions between the rolling surfaces of the outer and inner rings of the rolling bearing and the rolling elements, and the raceway surface or the rolling surface melts or the like to form irregularities, which not only roughens the rolling surface and the surface of the rolling elements of the bearing, causing noise and vibration, but also affects the life of the bearing when excessive electric erosion occurs.

[0004] In order to prevent electric erosion of a rolling bearing, it has also been practiced to interpose a conductive member. For example, in Patent Documents 1 and 2, it is proposed to be composed of a contact body for electrically connecting to the rotor of the motor, an elastic body for pressing the contact body toward the rotor side, and a storage portion for housing the contact body and the elastic body, and to provide the storage portion in the motor housing and electrically connect to the motor stator through the motor housing.

[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 project] [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 raceway ring in a biased state, wear powder of the conductive brush is generated. At the same time, the other raceway ring, 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 raceway ring, which imposes a large load on the raceway ring.

[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] Therefore, an object of the present invention is to suppress the generation of wear powder from the conductive member, or wear powder associated with the sliding contact between the conductive member and the mating material, and the temperature rise due to sliding, and also suppress damage to the mating material. In addition, without forming new processing on the bearing, and without being restricted by the type of bearing, it can be applied to existing bearings. The present invention provides a space-saving and inexpensive shaft grounding member and a rolling bearing unit equipped with the shaft grounding member.

Means for Solving the Problems

[0023] The above object of the present invention is achieved by the following configurations [1] to

[14] .

[0024] [1] A shaft grounding member to be mounted on a rolling bearing unit including a rolling bearing in which one raceway ring is a fixed ring and the other raceway ring is a rotating ring, A spring plate made of a thin sheet of conductive material is composed of an annular portion and at least one elastic portion that extends radially continuously from the annular portion, In the elastic portion, a soft conductive member is mounted on the surface facing the rotating wheel or the rotating member into which the rotating wheel is fitted, Equipped with, The soft conductive member contains a lubricant in advance and is capable of contacting at least a portion of the surface of the rotating wheel or at least a portion of the surface of the rotating member. A shaft grounding member for rolling bearings, characterized by the above.

[0025] [2] The shaft grounding member for rolling bearings according to [1], wherein the shaft grounding member is used in a dry environment where no lubricating fluid such as oil is flowing, and the lubricant is non-volatile.

[0026] [3] The shaft grounding member for rolling bearings according to [1] or [2], 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.

[0027] [4] The spring plate is composed of the annular portion and a plurality of elastic portions that extend radially in a continuous manner from the annular portion, The soft conductive member is mounted on the surface of the elastic portion facing the rotating wheel. The soft conductive member is capable of contacting the side surface of the rotating wheel. A bearing shaft grounding member according to any one of [1] to [3], characterized in that it is a bearing shaft grounding member.

[0028] [5] The spring plate is composed of the annular portion and a plurality of elastic portions that extend radially in a continuous manner from the annular portion, The soft conductive member is mounted on the surface of the elastic portion facing the rotating member. The soft conductive member is capable of contacting the side surface of the rotating member. A bearing shaft grounding member according to any one of [1] to [3], characterized in that it is a bearing shaft grounding member.

[0029] [6] The shaft grounding member for a rolling bearing according to any one of [1] to [5], characterized in that the annular portion is pressed against the side surface of the fixed ring with a spacer interposed therebetween.

[0030] [7] The spring plate is composed of the annular portion and a plurality of elastic portions that extend radially in a continuous manner from the annular portion, The rolling bearing shaft grounding member according to any one of [1] to [6], characterized in that the plurality of elastic parts are bent toward the rotating ring.

[0031] [8] The spring plate is composed of the annular portion and a plurality of elastic portions that extend radially in a continuous manner from the annular portion, The rolling bearing shaft grounding member according to any one of [1] to [6], characterized in that the plurality of elastic portions are formed flush with the annular portion.

[0032] [9] 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 [8].

[0033]

[10] The rolling bearing is of the inner ring rotation type, in which the fixed ring is an outer ring fixed to the housing and the rotating ring is an inner ring into which a shaft directly connected to the motor is fitted. The spring plate is composed of the annular portion and the elastic portion which extends from the inner circumferential end of the annular portion to the center of the annular portion, The soft conductive member is mounted on the side of the elastic portion facing the rolling bearing. The soft conductive member is capable of contacting the side surface of the shaft. A bearing shaft grounding member according to any one of [1] to [3], characterized in that it is a bearing shaft grounding member.

[0034]

[11] The shaft grounding member for a rolling bearing according to

[10] , characterized in that the annular portion is pressed against the side surface of the outer ring with a spacer interposed therebetween.

[0035]

[12] The shaft grounding member for a rolling bearing according to

[10] , characterized in that the elastic portion of the spring plate is bent toward the side of the shaft.

[0036]

[13] The shaft grounding member for a rolling bearing according to

[10] , characterized in that the elastic portion of the spring plate is formed flush with the annular portion.

[0037]

[14] The rolling bearing has an inner ring that rotates, with the outer ring fixed to the housing and the inner ring into which a shaft directly connected to the motor is fitted, A rolling bearing unit characterized by being fitted with a rolling bearing shaft grounding member described in any one of

[10] to

[13] . [Effects of the Invention]

[0038] The shaft grounding member of the present invention consists of a soft conductive member containing a lubricant, which is attached to the elastic portion of a spring plate and in contact with at least a portion of the surface of a rotating wheel or rotating member. The biasing force exerted by the spring plate on the soft conductive member against the rotating wheel or rotating member is not very strong, and wear particles are less likely to be generated. Furthermore, because the soft conductive member is made of a soft material, damage to the mating material, the rotating wheel, is minimized, and because the soft conductive member contains a lubricant, frictional heat caused by sliding contact is also suppressed.

[0039] Furthermore, it is highly versatile as it requires no processing of the rolling bearing, has no restrictions on the type of rolling bearing, and can be applied to existing rolling bearings. In addition, the spring plate is thin, which minimizes the increase in space required for the bearing unit it is installed in.

[0040] Since the bearing unit of the present invention is equipped with the shaft grounding member of the present invention, the generation of wear particles and damage to the mating material are suppressed, the reduction in durability due to the generation of frictional heat is suppressed, and furthermore, it is highly versatile and does not increase the space required. [Brief explanation of the drawing]

[0041] [Figure 1] Figure 1 shows an example of an inner ring rotating type bearing unit as a shaft grounding member according to the first embodiment of the present invention. Figure (A) is a plan view thereof, Figure (B) is a cross-sectional view of (A) AA, and Figure (C) is an enlarged view showing the bent portion between the annular portion and the elastic portion in Figure (B). [Figure 2] Figure 2 is a cross-sectional view showing how the shaft grounding member shown in Figure 1 is attached to the bearing unit. [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 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 plan view thereof, and Figure (B) is a cross-sectional view of (A) AA. [Figure 5] Figure 5 is a cross-sectional view showing how the shaft grounding member shown in Figure 4 is attached to the bearing unit. [Figure 6] Figure 6 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 4. [Figure 7] Figure 7 is a cross-sectional view showing an example of an inner ring rotating type bearing unit equipped with a shaft grounding member according to the third embodiment of the present invention. [Figure 8] Figure 8 is a cross-sectional view showing an example of an inner ring rotating type bearing unit equipped with another shaft grounding member according to the third embodiment of the present invention. [Figure 9] Figure 9 is a cross-sectional view showing an example of an outer ring rotating type bearing unit equipped with a shaft grounding member according to the fourth embodiment of the present invention. [Figure 10]Figure 10 is a cross-sectional view showing an example of an outer ring rotating type bearing unit equipped with another shaft grounding member according to the fourth embodiment of the present invention. [Figure 11] Figure 11 shows an example of a shaft grounding member according to the fifth embodiment of the present invention, where Figure (A) is a plan view thereof, Figure (B) is a cross-sectional view of Figure (A) AA, and Figure (C) is an enlarged view showing the bent portion of the elastic part in Figure (B). [Figure 12] Figure 12 is a cross-sectional view showing how the shaft grounding member shown in Figure 11 is attached to the bearing unit. [Figure 13] Figure 13 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 11. [Figure 14] Figure 14 is a cross-sectional view of a modified axial grounding member according to the present invention, corresponding to Figure 1(B). [Figure 15] Figure 15 is a cross-sectional view of a modified axial grounding member according to the present invention, corresponding to Figure 4(B). [Figure 16] Figure 16 is a cross-sectional view of a modified axial grounding member according to the present invention, corresponding to Figure 11(B). [Figure 17] Figure 17 is a cross-sectional view showing an example of a bearing unit fitted with the shaft grounding member shown in Figure 14. [Figure 18] Figure 18 is a cross-sectional view showing an example of a bearing unit equipped with the shaft grounding member shown in Figure 15. [Figure 19] Figure 19 is a cross-sectional view showing an example of a bearing unit fitted with the shaft grounding member shown in Figure 16. [Figure 20] Figure 20 is a schematic diagram showing an example of an apparatus used for conductivity evaluation and temperature evaluation. [Figure 21] Figure 21 shows an example of a shaft grounding member used for conductivity and temperature evaluation, where Figure (A) is a plan view and Figure (B) is a rear view. [Modes for carrying out the invention]

[0042] 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."

[0043] (First embodiment: Shaft grounding member and bearing unit for inner ring rotation) Figure 1 shows an example of a shaft grounding member of the present invention that is applied when the rotating ring is the inner ring. Figure (A) is a plan view thereof, Figure (B) is a cross-sectional view of AA in Figure (A), and Figure (C) is an enlarged view showing the bent portion between the annular portion and the elastic portion in Figure (B). Figure 2 is a cross-sectional view showing how the shaft grounding member shown in Figure 1 is mounted on a bearing unit. Figure 3 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 1.

[0044] As shown in Figure 1, the shaft grounding member 1A for inner ring rotation comprises a spring plate 10A composed of an annular portion 11A and a plurality of elastic portions 13A that are bent at the inner diameter end 12A of the annular portion 11A and extend radially from the annular portion 11A toward the radial center. Notches 16A are formed on both sides of the bent portion of the elastic portion 13A toward the annular portion 11A, to maintain the bent state of the elastic portion 13A.

[0045] The spring plate 10A is made entirely 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.

[0046] A soft conductive member 20 is attached to the bending side surface of each elastic part 13A, and the spring plate 10A and the soft conductive member 20 constitute the shaft grounding member 1A. The soft conductive member 20 contains a lubricant in advance and is attached to the elastic part 13A using an adhesive or the like. Flexible conductive materials and lubricants will be described in detail later.

[0047] As shown in Figures 2 and 3, the bearing unit 100A according to the first embodiment is equipped with a rolling bearing and has the shaft grounding member 1A shown in Figure 1 attached. 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. The bearing lubricant is sealed by a seal material 55. Here, the rotating ring is the inner ring 52, and a shaft 60 directly connected to a motor (not shown) is fitted into the inner diameter side of the inner ring 52. The outer ring 51 is a stationary ring and is fixed to the housing 70.

[0048] The flexible conductive member 20 is mounted on the elastic portion 13A on the side facing the inner ring (rotating ring) 52 (right side in the figure), and the flexible conductive member 20 is mounted on the bearing unit 100A with the bent side facing the inner ring 52.

[0049] As shown in Figure 3, the bearing unit 100A is used with the annular portion 11A of the shaft grounding member 1A pressed against the side surface of the outer ring 51 by a conductive pressing member 80 with a conductive spacer 30 interposed between them. Therefore, the outer diameter side of the outer ring 51 and the outer peripheral end face 15A of the annular portion 11A of the spring plate 10A are fixed in contact with the housing 70, and the soft conductive member 20 can contact the side surface 52a of the inner ring 52. The spring plate 10A is made of a thin plate and is elastic, so when the annular portion 11A of the shaft grounding member 1A is pressed against the side of the outer ring 51, the elastic force due to the pressing acts on the elastic portion 13A, causing it to be pushed open so that the bending angle θ shown in Figure 1(C) becomes larger. Consequently, the portion of the soft conductive member 20 that was separated from the side surface 52a of the inner ring 52 in Figure 2 also moves towards the rolling bearing 50, and almost the entire soft conductive member 20 comes into contact with the side surface 52a of the inner ring 52.

[0050] The thickness of the spacer 30 should be determined considering the amount of pressure applied by the spring plate 10A and the thickness of the soft conductive member 20. Alternatively, 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.

[0051] The flexible conductive member 20 is made by mixing or supporting a conductive material on a flexible base material. As the flexible base material, porous materials such as paper, cloth, nonwoven fabric, or resin sheets can be used. Alternatively, commercially available products referred to as "conductive sheets" can be used as the flexible conductive member. Examples of conductive materials include metal fibers, pulverized materials, and powders of silver, copper, gold, aluminum, stainless steel, or conductive carbon fibers, pulverized materials, and powders. In particular, it is preferable that the member be composed of at least one selected from resin-impregnated nonwoven fabric, nonwoven fabric, resin-impregnated woven fabric, woven fabric, resin-impregnated soft porous material such as sponge, and soft porous material such as sponge.

[0052] The type of lubricant to be contained in the flexible conductive member 20 can be lubricating oil or grease, but it is not particularly limited as long as it is non-volatile in the operating environment of the flexible conductive member 20, and a lubricant commonly used in bearings can be used. The lubricant contained in the flexible conductive member 20 and the lubricant inside the bearing may be the same or different. However, it is preferable to use the same lubricant because mixing different lubricants makes processing difficult when disassembling a deteriorated bearing unit.

[0053] There are no restrictions on the viscosity of the lubricant, as long as it is within a range that prevents leakage from the soft conductive member 20 when it is stationary. This is because, in the first embodiment, the soft conductive member 20 does not rotate and no leakage occurs due to centrifugal force, so as long as leakage is prevented when it is stationary, it can withstand long-term use.

[0054] Specifically, lubricants can include mineral oil, synthetic oil, grease containing mineral oil or synthetic oil and a thickener, or mixtures thereof. Examples of mineral oil include paraffinic mineral oil and naphthenic mineral oil. Examples of synthetic oil include hydrocarbon oil, aromatic oil, ester oil, and ether oil. Examples of thickeners include urea compounds and metal soaps.

[0055] Furthermore, there are no particular restrictions on the method of incorporating the lubricant into the flexible conductive member 20. For example, methods such as applying the lubricant to the flexible conductive member 20 or impregnating it with the lubricant can be selected.

[0056] In an inner-ring rotating bearing unit 100A that does not incorporate a shaft grounding member, 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 mounted on the housing 70 so as to abut against the side surface 52a of the inner ring 52. Furthermore, 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, and is also electrically connected to a conductive retaining member 80.

[0057] As a result, in the first embodiment, current from a motor (not shown) that drives the shaft 60 flows to the inner ring 52. Subsequently, the current flows from the soft conductive member 20 through the inner ring 52 to the elastic portion 13A and the annular portion 11A of the spring plate 10A, and then flows to the grounded housing 70 via the outer peripheral end face 15A of the annular portion 11A, the retaining member 80, the spacer 30 and the outer ring 51. In this way, by grounding the rotating member, the shaft 60, and the fixed member, the housing 70, current does not flow inside the bearing, 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 reduced. Furthermore, because the outer ring 51 has a large contact area with the housing 70, the current flowing through the outer ring 51 does not pass through the rolling elements 53, but instead flows to the housing 70.

[0058] Furthermore, since the side surface 52a of the inner ring 52 is in contact with the soft conductive member 20, the side surface 52a of the inner ring 52 is not damaged, and a decrease in the rotational torque of the inner ring 52 can be suppressed. In addition, the biasing force of the soft conductive member 20 on the side surface of the inner ring 52 by the spring plate 10A is not very strong, and since the soft conductive member 20 contains a lubricant, the generation of wear particles can be suppressed.

[0059] Furthermore, the bearing lubricant filled around the rolling elements 53 is sealed by the seal material 55, and the soft conductive member 20 is expected to be used in a dry environment where no lubricating fluid such as oil is flowing. In the first embodiment, by simply using a shaft grounding member 1A having a soft conductive member 20 that contains lubricant in advance, it is possible to suppress the temperature rise caused by sliding between the soft conductive member 20 and the bearing 50 in a dry environment, and the durability of the shaft grounding member 1A can be improved.

[0060] Honjitsu When a porous material is selected as the flexible conductive member 20 in the application configuration, the lubricant content is maintained by the surface tension of the lubricant by controlling the pore structure of the porous material. Furthermore, when the amount of lubricant on the surface decreases, the lubricant inside moves to the surface by capillary action. As a result, a lubricating film is always formed on the side surface of the inner ring 52 that contacts the flexible conductive member 20, suppressing the generation of frictional heat and further reducing the temperature rise due to sliding.

[0061] In the first embodiment, the outer peripheral end surface 15A of the annular portion 11A and the spacer 30 are in contact with the housing 70, but they may not be in contact with the housing 70, but instead be held between the outer ring 51 and the retaining member 80. In that case, the current flowing through the annular portion 11A flows to the housing 70 via the outer ring 51 and the retaining member 80. Alternatively, the annular portion 11A of the shaft grounding member 1A may be pressed directly against the side surface of the outer ring 51 with a conductive spacer 30 interposed between them, without the presence of a retaining member 80, and fixed in contact with the housing 70.

[0062] Furthermore, as shown in Figure 1(C), the bending angle θ between the annular portion 11A and the elastic portion 13A can be appropriately set according to the length (L) of the elastic portion 13A and the size of the soft conductive member 20, so that when mounted on the bearing unit 100A, the soft conductive member 20 contacts the side surface 52a of the inner ring 52 of the rolling bearing 50. The biasing force of the soft conductive member 20 on the side surface 52a of the inner ring 52 of the rolling bearing 50 can also be adjusted by the bending angle θ; the biasing force can be increased by decreasing the bending angle θ, and conversely, the biasing force can be decreased by increasing the bending angle θ.

[0063] By adjusting the pressing force applied by the retaining member 80 to the outer ring 51, the contact area between the soft conductive member 20 of the shaft grounding member 1A and the side surface 52a of the inner ring 52 of the rolling bearing 50 changes. Therefore, by increasing the contact area between the soft conductive member 20 and the side surface 52a of the inner ring 52, electrolytic corrosion of the rolling bearing 50 can be prevented more effectively, electromagnetic noise can be reduced, and temperature rise due to friction can be suppressed.

[0064] (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 4 is a diagram showing the shaft grounding member for the rotation of the outer ring, with Figure (A) being a plan view thereof and Figure (B) being a cross-sectional view of Figure (A) AA. Figure 5 is a cross-sectional view showing how the shaft grounding member shown in Figure 4 is attached to the bearing unit. Figure 6 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 4. 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.

[0065] As shown in Figure 4, the shaft grounding member 1B for outer ring rotation comprises a spring plate 10B composed of an annular portion 11B and a plurality of elastic portions 13B that are bent at the outer diameter end 12B of the annular portion 11B and extend radially from the annular portion 11B toward the outer circumference in the radial direction. As shown in Figure 5, the elastic portions 13B are bent toward the right in the figure so that they face the outer ring 51 of the rolling bearing 50 when mounted on the bearing unit 100B. In addition, arc-shaped notches 16B are formed on both sides of the bent portion of the elastic portion 13B toward the annular portion 11B.

[0066] A soft conductive member 20 containing a lubricant is attached in advance to the surface of each elastic part 13B facing the outer ring 51 of the rolling bearing 50 using an adhesive or the like, and the spring plate 10B and the soft conductive member 20 constitute the shaft grounding member 1B.

[0067] As shown in Figures 5 and 6, the bearing unit 100B according to the second embodiment includes a rolling bearing 50 and is fitted with the shaft grounding member 1B shown in Figure 4. The inner ring 52 of the rolling bearing 50 is fixed to the fixed member 75, and the rotating member 65 is fitted to the outer ring 51. As shown in Figure 5, the soft conductive member 20 is fitted to the elastic portion 13B on the surface (right side in the figure) facing the outer ring (rotating ring) 51, and the bearing unit 100B is fitted with the flexible conductive member 20 with the bent side facing the outer ring 51.

[0068] Furthermore, as shown in Figure 6, the bearing unit 100B is used with the annular portion 11B of the shaft grounding member 1B pressed against the side surface of the inner ring 52 by the retaining member 80 with a conductive spacer 30 interposed between them. Therefore, the inner diameter side of the inner ring 52 and the inner circumferential end surface of the annular portion 11B on the spring plate 10B are fixed in contact with the fixing member 75, and the soft conductive member 20 is able to contact the side surface of the outer ring 51.

[0069] In the second embodiment, current from a motor (not shown) that drives the rotating member 65 flows to the outer ring 51. The current then flows from the soft conductive member 20 through the outer ring 51 to the elastic portion 13B and the annular portion 11B of the spring plate 10B, and then through the inner circumferential end face 14B of the annular portion 11B, the retaining member 80, the spacer 30, and the inner ring 52 to the grounded 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 reduced.

[0070] Furthermore, similar to the first embodiment, the biasing force exerted by the spring plate 10B on the side surface of the outer ring 51 of the flexible conductive member 20 is not very strong, and since the flexible conductive member 20 contains a lubricant, wear particles are less likely to be generated. In addition, since the flexible conductive member 20 already contains a lubricant, it is possible to suppress the temperature rise caused by sliding between the flexible conductive member 20 and the outer ring 51.

[0071] Furthermore, by adjusting the pressing force applied by the retaining member 80 to the outer ring 51 and increasing the contact area between the soft conductive member 20 and the side surface 51a of the outer ring 51, electrolytic corrosion of the rolling bearing 50 can be prevented more effectively, and the temperature rise due to friction can be suppressed.

[0072] Furthermore, in this embodiment as well, the annular portion 11B of the shaft grounding member 1B may directly contact the side surface of the inner ring 52 without providing the spacer 30. Furthermore, the inner circumferential end surface 14B of the annular portion 11B and the spacer 30 may be in contact with the fixing member 75, or they may not be in contact with the fixing member 75 but may be held between the inner ring 52 by the retaining member 80.

[0073] (Third embodiment: Shaft grounding member and bearing unit for inner ring rotation) Figure 7 shows the case in which the shaft grounding member 1A is mounted on a bearing unit in which the rotating ring is the inner ring, similar to the first embodiment. In the bearing unit according to the third embodiment, the same reference numerals are used for the same components as in the first embodiment, and their detailed descriptions are omitted or simplified.

[0074] In the third embodiment, the shaft 60, which is a rotating member into which the inner ring 52 is fitted, has a stepped surface 60c formed thereon that is smaller in diameter than the fitting surface 60b into which the inner ring 52 is fitted. The soft conductive member 20, which contains lubricant in advance, is mounted on the surface of the elastic portion 13A that faces the shaft 60 in the axial direction, specifically on the side surface 60a between the fitting surface 60b into which the inner ring 52 is fitted and the stepped surface 60c. The shaft grounding member 1A is mounted on the housing 70 by elastically deforming the elastic portion 13A. 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 toward the inner diameter side of the housing 70.

[0075] As shown in Figure 7, in this type of inner ring rotating bearing unit 100A, the soft conductive member 20 of the shaft grounding member 1A is mounted on the housing 70 so as to contact the side surface 60a of the shaft 60. As a result, the annular portion 11A of the spring plate 10A is electrically connected to the side surface of the outer ring 51 via the conductive spacer 30, and is also electrically connected to the end face of the flange portion 71 of the housing 70.

[0076] In the bearing unit 100A shown in Figure 7, the current from the shaft 60 flows from the soft conductive member 20 through the side surface 60a of the shaft 60 to the elastic portion 13A and the annular portion 11A of the spring plate 10A. Subsequently, the current flows to the housing 70 via the spacer 30 and the outer ring 51, or via the outer peripheral end face 15A of the annular portion 11A to the grounded housing 70. In this way, by grounding the rotating member, the shaft 60, and the stationary member, the housing 70, current does not flow inside the bearing, and the shaft voltage, which is the potential difference between the rotating member and the stationary member, can be significantly reduced. Therefore, electrolytic corrosion of the rolling bearing 50 can be prevented, and electromagnetic noise can be reduced.

[0077] Furthermore, similar to the first embodiment, the biasing force exerted by the spring plate 10A on the side surface of the shaft 60 by the soft conductive member 20 is not very strong, and since the soft conductive member 20 contains a lubricant, wear particles are less likely to be generated. In addition, since the soft conductive member 20 already contains a lubricant, it is possible to suppress the temperature rise caused by sliding between the soft conductive member 20 and the shaft 60.

[0078] As shown in Figure 8, in this embodiment, the shaft 60 may be provided with a flange portion 62 that protrudes outward from the fitting surface 60b, and the soft conductive member 20 may be in contact with the side surface 60a of this flange portion 62.

[0079] In particular, in the bearing unit 100A shown in Figure 7, the position where the soft conductive member 20 contacts the side surface 60a of the shaft 60 is smaller in diameter than the position where it contacts the side surface 52a of the inner ring 52, as shown in Figure 3. This allows the peripheral speed of the side surface 60a of the shaft 60 to be reduced, further suppressing the generation of wear particles and drag losses.

[0080] Unlike the first embodiment, the third embodiment does not involve contact between the shaft contact member 1A and the side surface 52a of the inner ring 52, thereby improving the design flexibility of the rolling bearing, such as the installation of a snap ring.

[0081] (Fourth embodiment: Shaft grounding member and bearing unit for outer ring rotation) Figure 9 shows the case where the shaft grounding member 1B is mounted on a bearing unit in which the rotating ring is the outer ring 51, similar to the second embodiment. In the bearing unit according to the fourth embodiment, the same reference numerals are used for the same components as in the second embodiment, and their detailed descriptions are omitted or simplified.

[0082] In the fourth embodiment, the rotating member 65 into which the outer ring 51 is fitted has a stepped surface 65c formed thereon that is larger in diameter than the fitting surface 65b into which the outer ring 51 is fitted. The soft conductive member 20, which contains lubricant in advance, is mounted on the surface of the elastic portion 13B that faces the rotating member 65 in the axial direction, specifically on the surface facing the side surface 65a between the fitting surface 65b into which the outer ring 51 is fitted and the stepped surface 65c. Therefore, the soft conductive member 20 can come into contact with the side surface 65a of the rotating member 65.

[0083] As shown in Figure 9, in the outer ring rotating type bearing unit 100B, the soft conductive member 20 of the shaft grounding member 1B is mounted on the fixed member 75 so as to abut against the side surface 65a of the rotating member 65. As a result, the annular portion 11B of the spring plate 10B is electrically connected to the side surface of the inner ring 52 via the conductive spacer 30, and is also electrically connected to the end face of the flange portion 76 of the fixed member 75.

[0084] In the bearing unit 100B shown in Figure 9, the current from the motor (not shown) that drives the rotating member 65 flows from the soft conductive member 20 through the side surface 65a of the rotating member 65, through the elastic portion 13B and the annular portion 11B of the spring plate 10B, and to the inner circumferential end surface 14B of the annular portion 11B. After that, the current flows to the grounded fixed member 75, or directly to the fixed member 75, via the spacer 30 and the inner ring 52. 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 reduced.

[0085] Furthermore, similar to the first embodiment, the biasing force exerted by the spring plate 10B on the side surface of the rotating member 65 by the soft conductive member 20 is not very strong, and since the soft conductive member 20 contains a lubricant, wear particles are less likely to be generated. In addition, since the soft conductive member 20 already contains a lubricant, it is possible to suppress the temperature rise caused by sliding between the soft conductive member 20 and the rotating member 65.

[0086] As shown in Figure 10, in this embodiment, the rotating member 65 may be provided with a flange portion 67 that protrudes inward from the fitting surface 65b, and the soft conductive member 20 may come into contact with the side surface 65a of this flange portion 67.

[0087] In particular, in the bearing unit 100B shown in Figure 10, the position where the soft conductive member 20 contacts the side surface 65a of the rotating member 65 is smaller in diameter than the position where it contacts the side surface 51a of the outer ring 51, as shown in Figure 6. This allows the peripheral speed of the side surface 65a of the rotating member 65 to be reduced, further suppressing the generation of wear particles and drag losses.

[0088] Furthermore, unlike the second embodiment, the fourth embodiment does not have the shaft contact member 1B in contact with the side surface 51a of the outer ring 51, thus improving the design flexibility of the rolling bearing, such as the installation of a snap ring.

[0089] (Fifth embodiment: Shaft grounding member and bearing unit for inner ring rotation, equipped with a single elastic part) Figure 11 shows an example of a shaft grounding member according to the fifth embodiment of the present invention, where Figure (A) is a plan view thereof, Figure (B) is a cross-sectional view of Figure (A) AA, and Figure (C) is an enlarged view showing the bent portion between the annular portion and the elastic portion in Figure (B). Figure 12 is a cross-sectional view showing how the shaft grounding member shown in Figure 11 is mounted on a bearing unit. Figure 13 is a cross-sectional view showing an example of a bearing unit incorporating the shaft grounding member shown in Figure 11. In the bearing unit according to the fifth embodiment, the same reference numerals are used for the same components as in the first embodiment, and their detailed descriptions are omitted or simplified.

[0090] As shown in Figure 11, the shaft grounding member 1C comprises a spring plate 10C which consists of an annular portion 11C and a single elastic portion 13C that is bent at the inner circumferential end 12C of the annular portion 11C and extends radially toward the center, continuous with the annular portion 11C. The elastic portion 13C is bent starting from an elastic base portion 14C. A soft conductive member 20 containing a lubricant is attached to the bent side surface of the elastic portion 13C with an adhesive or the like, and the spring plate 10C and the soft conductive member 20 constitute the shaft grounding member 1C.

[0091] As shown in Figure 12, the shaft contact member 1C is mounted on the bearing unit 100C with the bent side surface (right side in the figure) of the elastic portion 13C facing the side surface 60a of the shaft 60 which is fitted into the inner ring 52 of the rolling bearing 50. The side surface 60a of the shaft 60 refers to the surface of the shaft 60 that is perpendicular to the axial direction.

[0092] Furthermore, as shown in Figure 13, the bearing unit 100C is used with the annular portion 11C of the shaft grounding member 1C pressed against the side surface of the outer ring 51 by the retaining member 80 with the spacer 30 interposed between them. Therefore, the soft conductive member 20 can come into contact with the side surface 60a of the shaft 60. As a result, the annular portion 11C of the spring plate 10C is electrically connected to the side surface of the outer ring 51 via the conductive spacer 30, and is also electrically connected to the housing 70.

[0093] In the fifth embodiment, current from a motor (not shown) that drives the shaft 60 flows from the soft conductive member 20 to the elastic portion 13C and the annular portion 11C of the spring plate 10C, and then flows to the grounded housing 70 via the outer peripheral end face 15C of the annular portion 11C, the retaining member 80, the spacer 30 and the outer ring 51. By grounding the rotating member, the shaft 60, and the fixed member, the housing 70 in this way, current does not flow inside the bearing, 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 reduced.

[0094] Furthermore, similar to the first embodiment, the biasing force exerted by the spring plate 10C on the side surface of the shaft 60 by the soft conductive member 20 is not very strong, and since the soft conductive member 20 contains a lubricant, wear particles are less likely to be generated. In addition, since the soft conductive member 20 already contains a lubricant, it is possible to suppress the temperature rise caused by sliding between the soft conductive member 20 and the shaft 60.

[0095] Furthermore, in the fifth embodiment, the outer peripheral end face 15C of the annular portion 11C and the spacer 30 are in contact with the housing 70, but they may not be in contact with the housing 70 and may be held between the outer ring 51 and the retaining member 80. In that case, the current flowing through the annular portion 11C flows to the housing 70 via the outer ring 51 and the retaining member 80. Note that since the outer ring 51 has a large contact area with the housing 70, the current flowing through the outer ring 51 does not pass through the rolling elements 53 and flows to the housing 70.

[0096] Furthermore, in the bearing unit 100C, the soft conductive member 20 is in contact with the side surface 60a of the shaft 60, resulting in an even lower peripheral speed compared to the case where the soft conductive member 20 is in contact with the side surface of the inner ring 52. Therefore, compared to other embodiments, it is possible to further suppress the generation of wear particles and drag losses. Note that since the peripheral speed is lowest near the center of the shaft, it is more preferable for the soft conductive member 20 to be in contact near the center of the shaft.

[0097] It should be noted that the present invention is not limited to the embodiments described above, and can be modified and improved as appropriate. In the above embodiment, the elastic portions 13A, 13B, and 13C of the spring plates 10A, 10B, and 10C are configured to bend toward the rotating ring. However, they may also be formed flush with the annular portions 11A, 11B, and 11C without bending at the inner diameter end 12A, the outer diameter end 12B, and the elastic base portion 14C. For example, in the case of the shaft grounding member 1A for inner ring rotation shown in Figure 1, the annular portion 11A and the elastic portion 13A may be linearly continuous in cross-sectional view, as shown in Figure 14. Also, for example, in the case of the shaft grounding member 1B for outer ring rotation shown in Figure 4, the annular portion 11B and the elastic portion 13B may be linearly continuous in cross-sectional view, as shown in Figure 15. Furthermore, in the case of the shaft grounding member 1C shown in Figure 11, the annular portion 11C and the elastic portion 13C may be linearly continuous in cross-sectional view, as shown in Figure 16.

[0098] Therefore, in the bearing units 100A and 100C shown in Figures 17 and 19, when the annular portions 11A and 11C of the shaft grounding members 1A and 1C are sandwiched between the flange portion 71 of the housing 70 and the side surface of the outer ring 51, the elastic portions 13A and 13C of the shaft grounding members 1A and 1C elastically deform by the thickness of the soft conductive member 20, and the bending reaction force of the spring plates 10A and 10C causes the soft conductive member 20 to come into contact with the side surface 52a of the inner ring 52 and the side surface 60a of the shaft 60, respectively. Furthermore, in the bearing unit 100B shown in Figure 18, when the annular portion 11B of the shaft grounding member 1B is sandwiched between the flange portion 76 of the fixing member 75 and the side surface of the inner ring 52, the elastic portion 13B of the shaft grounding member 1B elastically deforms by the thickness of the soft conductive member 20, and the bending reaction force of the spring plate 10B causes the soft conductive member 20 to come into contact with the side surface 51a of the outer ring 51. This allows the same function as in the above embodiment to be achieved.

[0099] In this case, bending of the spring plates 10A, 10B, and 10C becomes unnecessary, allowing the shaft grounding members 1A, 1B, and 1C to be manufactured at a low cost, and also facilitating bonding between the spring plates 10A, 10B, and 10C and the soft conductive member 20.

[0100] In all embodiments, there are no restrictions on the planar shape of the flexible conductive member 20. In addition to the sector shape shown in Figure 1(A), it may also be rectangular. It may also be made up of multiple small pieces.

[0101] 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. [Examples]

[0102] To confirm the effects of the present invention, a rolling bearing unit having a configuration substantially similar to that of the first embodiment was incorporated into a measuring device and tested. Tests were also conducted using the rolling bearing shaft grounding member of the inventive example, in which a lubricant was pre-impregnated into the soft conductive member, and the rolling bearing shaft grounding member of the comparative example, in which the lubricant was not contained in the soft conductive member. In the inventive example, transmission oil was applied to the soft conductive member as a lubricant.

[0103] <Measuring device> Referring to Figure 20, the configuration of the measuring device 200 used for evaluating the conductivity of the axial grounding member and measuring the temperature of the flexible conductive member 20 will be explained. In the measuring device 200, the inner ring (rotating ring) 52 of the rolling bearing 50 is fitted onto the shaft (rotating member) 60 connected to the motor 91. The configuration of the rolling bearing 50 is the same as the inner ring rotation configuration shown in Figure 3 described in the first embodiment, so in Figure 20, the same reference numerals are used for the same parts as those shown in Figure 3. The outer ring (fixed ring) 51 of the rolling bearing 50 is fixed to the inner diameter side of the housing (fixed member) 70.

[0104] The shaft grounding member 1A and the spacer 30 are mounted so as to be sandwiched between the rolling bearing 50 and the retaining member 80. Furthermore, the piston 93 mounted on the cylinder 92 applies a load to the retaining member 80 in the direction of the shaft grounding member 1A, thereby fixing the shaft grounding member 1A and the spacer 30 in place.

[0105] An insulating coupling 94 is fitted to the shaft 60, the piston 93 and part of the housing 70 are made of insulating material, and rolling elements 53 made of an insulator are arranged between the inner ring 52 and the outer ring 51 of the bearing 50. In this way, conductive paths other than the shaft grounding member 1A are blocked in order to evaluate the conductivity of the shaft grounding member 1A. The bearing, which is sealed with a seal material (not shown), is filled with grease as a bearing lubricant, and the soft conductive member 20 is used in a dry environment where no lubricating fluid such as oil is flowing.

[0106] For temperature measurement, the shaft grounding member 1A shown in Figure 21 was used. A temperature-indicating tape 90 was attached to the shaft grounding member 1A on the side opposite to the side where the soft conductive member 20 of the elastic part 13A was attached. The temperature-indicating tape 90 used was one that irreversibly changes color in response to temperature changes on the surface to which it is attached. This allowed the temperature of the shaft grounding member to be measured by visual inspection alone.

[0107] (Evaluation of conductivity) The following describes a method for evaluating conductivity using a commercially available LCR meter 95. One conductive cable 98a of the LCR meter 95 was connected to a commercially available conductive brush 96 positioned in contact with the shaft 60. The other conductive cable 98b of the LCR meter 95 was connected to a terminal 97 in contact with the housing 70. As a result, a conductive path CP was constructed, as shown by the dashed line in Figure 20, extending from the conductive brush 96 (the inlet) through the shaft 60, inner ring 52, flexible conductive member 20 made of porous material, spring plate 10A, and housing 70 to the terminal 97 (the outlet). The resistance value between the conductive brush 96 and the terminal 97 was measured using the LCR meter to evaluate whether sufficient conductivity could be maintained for the shaft grounding member 1A.

[0108] Furthermore, in this measurement, the shaft 60 had a diameter of 30 mm, a rotational speed of 3500 rpm, the inner diameter of the housing 70 was 62 mm, and the LCR meter was an AC constant current power supply with a current value of 30 mA.

[0109] The measurement results for temperature and resistance values ​​in the shaft grounding member 1A are shown in Table 1 below. In Table 1, the resistance value of the comparative example is set to 1.0, and the resistance value of the inventive example is shown as a relative value.

[0110] [Table 1]

[0111] As shown in Table 1 above, in the inventive example, by containing a lubricant in the porous soft conductive member 20, a lubricating film is formed on the side surface of the inner ring (rotating ring) 52 that contacts the soft conductive member 20, and the temperature rise during sliding is suppressed, resulting in a temperature of 80°C. Furthermore, the resistance value in the inventive example was 2.4 when the resistance value of the comparative example was set to 1.0.

[0112] (Evaluation of measurement results) As an evaluation criterion for the measurement results, samples with a resistance value of less than 10.0 and a temperature of less than 100°C (with the resistance value of the comparative example set to 1.0) were judged to have good mechanical properties.

[0113] If the resistance value of the shaft grounding member is significantly lower than the resistance value of the rolling bearing, the current flowing from the motor 91 flows from the inner ring (rotating ring) 52 of the rolling bearing 50 to the shaft grounding member 1A, thereby preventing electrolytic corrosion of the rolling bearing 50 and suppressing the generation of electromagnetic noise. The resistance value of the rolling bearing is approximately 1000 when the comparative example is set to 1.0, so if the resistance value of the shaft grounding member is less than 10.0, it can be judged to be a significantly low value.

[0114] Since the flexible conductive member 20 used in this invention may contain some organic material, thermal degradation is an important factor when determining its durability. The relationship between durability (lifespan) and temperature can often be expressed by Arrhenius's law, shown in equation (1) below. ln[lifetime] = [constant] + [activation energy] / [gas constant] / [temperature] ... Equation (1)

[0115] The activation energy for thermal degradation reactions of organic materials at around 100°C is approximately 10-30 kcal. Therefore, assuming an activation energy of 10 kcal, and using the Arrhenius equation mentioned above to calculate the lifespan of a soft porous material, the lifespan at 80°C is 5.9 times longer than that at 130°C. Therefore, if the temperature of the soft conductive member is below 100°C, it can be determined that the lifespan of the shaft grounding member is sufficient, and a bearing unit with excellent durability has been obtained.

[0116] From the above, the measurement results for temperature and resistance in the example invention all meet the evaluation criteria, demonstrating that it is possible to suppress electromagnetic noise while maintaining sufficient conductivity as a shaft grounding member, and to reduce the rise in sliding temperature, thereby improving durability. [Explanation of symbols]

[0117] 1A, 1B, 1C Axle grounding member 10A, 10B, 10C Spring Plate 11A, 11B, 11C Annular section 13A, 13B, 13C Elastic part 14B Inner circumferential end face 15A,15C Outer edge 16A, 16B Notches 20 Flexible conductive material 30 Spacers 50 Rolling bearings 51 Outer ring 51a, 52a, 60a, 65a Side view 52 Inner Ring 53 Rolling element 55 Sealants 60 shaft 60b,65b mating surface 60c,65c step surface 62, 67, 71, 76 Flange section 65 Rotating member 70 Housing 75 Fixing member 80 Retaining member 100A, 100B, 100C Bearing Unit 200 measuring devices CP conductive path

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 and at least one elastic portion that extends radially continuously from the annular portion, In the elastic portion, a soft conductive member is mounted on the surface facing the rotating wheel or the rotating member into which the rotating wheel is fitted, Equipped with, The soft conductive member contains a lubricant in advance and is capable of contacting at least a portion of the surface of the rotating wheel or at least a portion of the surface of the rotating member. The flexible conductive member is composed of at least one selected from a resin-impregnated nonwoven fabric, a resin-impregnated woven fabric, and a resin-impregnated flexible porous body. A shaft grounding member for rolling bearings, characterized by the above.

2. The shaft grounding member for a rolling bearing according to claim 1, wherein the shaft grounding member is used in a dry environment and the lubricant is non-volatile.

3. A shaft grounding member to be 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 a ring-shaped portion and a plurality of elastic portions extending radially and continuously from the ring-shaped portion, A soft conductive member is mounted on the surface of the elastic portion facing the rotating wheel, Equipped with, The aforementioned soft conductive member contains a lubricant in advance and is capable of contacting the side surface of the rotating wheel. A shaft grounding member for rolling bearings, characterized by the above.

4. A shaft grounding member to be 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 a ring-shaped portion and a plurality of elastic portions extending radially and continuously from the ring-shaped portion, A soft conductive member is mounted on the surface of the elastic portion facing the rotating member into which the rotating ring is fitted, Equipped with, The aforementioned soft conductive member contains a lubricant in advance and is capable of contacting the side surface of the rotating member. A shaft grounding member for rolling bearings, characterized by the above.

5. A shaft grounding member to be 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 and at least one elastic portion that extends radially and continuously from the annular portion, In the elastic portion, a soft conductive member is mounted on the surface facing the rotating wheel or the rotating member into which the rotating wheel is fitted, Equipped with, The soft conductive member contains a lubricant in advance and is capable of contacting at least a portion of the surface of the rotating wheel or at least a portion of the surface of the rotating member. A shaft grounding member for a rolling bearing, characterized in that the annular portion is pressed against the side surface of the fixed ring with a spacer interposed therebetween.

6. A shaft grounding member to be 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 a ring-shaped portion and a plurality of elastic portions extending radially and continuously from the ring-shaped portion, In the elastic portion, a soft conductive member is mounted on the surface facing the rotating wheel or the rotating member into which the rotating wheel is fitted, Equipped with, The soft conductive member contains a lubricant in advance and is capable of contacting at least a portion of the surface of the rotating wheel or at least a portion of the surface of the rotating member. A shaft grounding member for a rolling bearing, characterized in that the plurality of elastic parts are bent toward the rotating ring.

7. A shaft grounding member to be 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 a ring-shaped portion and a plurality of elastic portions extending radially and continuously from the ring-shaped portion, In the elastic portion, a soft conductive member is mounted on the surface facing the rotating wheel or the rotating member into which the rotating wheel is fitted, Equipped with, The soft conductive member contains a lubricant in advance and is capable of contacting at least a portion of the surface of the rotating wheel or at least a portion of the surface of the rotating member. A shaft grounding member for a rolling bearing, characterized in that the plurality of elastic portions are formed flush with the annular portion.

8. 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 7.

9. A shaft grounding member to be 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, The aforementioned rolling bearing is an inner-ring rotating type, in which the fixed ring is an outer ring fixed to the housing, and the rotating ring is an inner ring into which a shaft directly connected to the motor is fitted. A spring plate made of a thin sheet of conductive material is composed of an annular portion and an elastic portion that extends radially from the inner circumferential end of the annular portion toward the center of the annular portion, A soft conductive member is mounted on the surface of the elastic portion facing the rolling bearing, Equipped with, The aforementioned soft conductive member contains a lubricant in advance and is capable of contacting the side surface of the shaft. A shaft grounding member for rolling bearings, characterized by the above.

10. The shaft grounding member for a rolling bearing according to claim 9, characterized in that the annular portion is pressed against the side surface of the outer ring with a spacer interposed therebetween.

11. The shaft grounding member for a rolling bearing according to claim 9, characterized in that the elastic portion of the spring plate is bent toward the side of the shaft.

12. The shaft grounding member for a rolling bearing according to claim 9, characterized in that the elastic portion of the spring plate is formed flush with the annular portion.

13. It features an inner ring rotating type rolling bearing in which the outer ring is fixed to the housing and the shaft directly connected to the motor is fitted into the inner ring, A rolling bearing unit characterized by being fitted with a rolling bearing shaft grounding member according to any one of claims 9 to 12.

Images