Electrolytic corrosion prevention member for rolling bearing and electrolytic corrosion prevention rolling bearing unit

Abstract

To provide an electric corrosion prevention member which inhibits generation of abrasion powder from a conductive member and abrasion powder generated by sliding contact between the conductive member and a mating member, prevents damage of the mating member, and can be used in an existing bearing without forming new processing in the bearing and limiting the type of the bearing, and to provide an electric corrosion prevention rolling bearing unit attached with the electric corrosion prevention member.SOLUTION: An electric corrosion prevention member for a rolling bearing includes: a spring plate comprising an annular part and an elastic part which continuously extends from an inner periphery side end of the annular part to a center of the annular part, the spring plate formed by a thin plate made of a conductive material; and a soft conductive member attached to a surface, which faces the rolling bearing, of the elastic part. The soft conductive member may contact with an end surface of a shaft. An electric corrosion prevention rolling bearing unit includes the electric corrosion prevention member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electrolytic corrosion prevention member for a rolling bearing that is mounted to prevent electrolytic corrosion of the rolling bearing in a rolling bearing unit, and to an electrolytic corrosion prevention rolling bearing unit mounted with the electrolytic corrosion prevention member for a rolling bearing. [Background technology]

[0002] In recent years, electric vehicles that use electric motors as drive sources located inside or near the wheels to drive the wheels have become increasingly common. Such drive motors are generally called in-wheel motors. A typical in-wheel motor has a stator fixed to a motor housing, and a rotor located radially inside the stator with a gap between them, making it a so-called inner rotor motor. Furthermore, in consideration of motor performance and controllability, brushless DC motors driven by inverters are often used as the drive system for in-wheel motors.

[0003] In inverter-driven systems, a potential difference occurs between the stator and rotor due to factors such as parasitic capacitance between them. This potential difference generates what is known as a shaft voltage and current, and when this shaft current passes through the rolling bearing that supports the rotor, it causes damage to the rolling bearing, a phenomenon known as "electrical corrosion." Specifically, current flows locally at the contact points between the rolling surfaces of the outer and inner rings of the rolling bearing and the rolling elements, causing the raceway surface or rolling surface to melt and become uneven. This roughens the rolling surfaces and rolling element surfaces of the bearing, causing noise and vibration, and excessive electrical corrosion can also affect the bearing's lifespan.

[0004] In order to prevent electrolytic corrosion of rolling bearings, it has also been proposed to insert a conductive member. For example, Patent Documents 1 and 2 propose a bearing that is made up of a contact body for electrically connecting the bearing to the motor rotor, an elastic body for pressing the contact body toward the rotor, and a storage section for accommodating the contact body and the elastic body, with the storage section being provided in the motor housing and electrically connecting the bearing to the motor stator via 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 circumferential surface of a rotating shaft.

[0006] Furthermore, Patent Document 4 proposes an electrolytic corrosion prevention device in which the annular seat that contacts the end face of the bearing outer ring is bent into a wave washer shape, and an elastic conductor is used that has a contact piece that extends from the inside of the annular seat and contacts the center of the end face of the rotating shaft, and the annular seat is overlapped with the end face of the bearing outer ring fitted into the bearing housing, and the contact piece is abutted against the center of the end face of the rotating shaft fitted into the bearing inner ring, and the surface of the annular seat is pressed with the lid-like wall of the bearing housing to establish electrical conductivity.

[0007] Furthermore, Patent Document 5 proposes that a rod-shaped conductive brush be housed in a support hole provided in one of the two raceways, and that an elastic member be used to urge the tip of the conductive brush toward the other raceway so that it slides against the other raceway, thereby establishing electrical continuity between the two raceways. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-135720 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-135722 [Patent Document 3] Japanese Patent Publication No. 2020-127257 [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-146568 [Patent Document 5] Japanese Utility Model Application Publication No. 4-8820 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in the techniques described in any of the patent documents, wear particles generated from the conductive member may contaminate the lubricating oil or grease composition sealed in the bearing for lubrication, potentially causing damage to the rolling surfaces or rolling contact surfaces.Furthermore, the mating material of the conductive member may be damaged, resulting in the generation of wear particles.

[0010] Specifically, in Patent Documents 1 and 2, the contact body, elastic body, and housing body are made of metal members, and metal powder is generated when these come into sliding contact with each other as the motor vibrates. In addition, the contact body, elastic body, and housing body must be provided in the motor housing, which requires space for them.

[0011] In addition, in Patent Document 3, the tips of the broom-shaped conductive fibers are brought into contact with the outer circumferential surface of the rotating shaft. However, in order to increase the contact area between the tips of the broom-shaped conductive fibers and the rotating shaft compared to when the tips are simply in contact, the broom-shaped conductive fibers are brought into contact with the outer circumferential surface of the rotating shaft in a bent state. In other words, the tips of the broom-shaped conductive fibers are in contact with the outer circumferential surface of the rotating shaft with a fairly strong pressing force, which generates wear powder. At the same time, the outer circumferential surface of the rotating shaft, which is the mating material of the broom-shaped conductive fibers, is also damaged.

[0012] In Patent Document 4, the elastic conductor and the rotating shaft are both made of metal, and metal powder is generated when they slide in contact with each other. At the same time, the end face of the rotating shaft, which is the mating material of the elastic conductor, is damaged.

[0013] In addition, in Patent Document 5, the tip of the rod-shaped conductive brush is biased and in contact with the other raceway, generating wear powder from the conductive brush. At the same time, the other raceway, which is the mating material of the conductive brush, is also damaged. Furthermore, a support hole must be formed in the raceway to accommodate the conductive brush and the elastic member, which places a heavy load on the raceway.

[0014] Therefore, the present invention aims to provide a space-saving, inexpensive electrolytic corrosion prevention member that suppresses the generation of wear powder from conductive members or wear powder caused by sliding contact between the conductive member and the mating material, and also suppresses damage to the mating material, without requiring any new processing on the bearing and without any restrictions on the type of bearing, making it compatible with existing bearings, as well as an electrolytic corrosion prevention rolling bearing unit equipped with the electrolytic corrosion prevention member. [Means for solving the problem]

[0015] The above object of the present invention is achieved by the following configuration [1] relating to an electrolytic corrosion prevention member for a rolling bearing.

[0016] [1] In a rolling bearing unit having an inner ring rotating type rolling bearing in which an outer ring is fixed to a housing and a shaft directly connected to a motor is fitted into the inner ring, an electrolytic corrosion prevention member is attached to the rolling bearing unit to prevent electrolytic corrosion of the rolling bearing, a spring plate made of a thin plate of conductive material, the spring plate including a circular portion and an elastic portion extending continuously from an inner peripheral end of the circular portion to a center of the circular portion; a soft conductive member attached to a surface of the elastic portion facing the rolling bearing; In addition to providing the soft conductive member is capable of abutting against the end surface of the shaft; An electrolytic corrosion prevention member for a rolling bearing, comprising:

[0017] Further, preferred embodiments of the present invention relating to the member for preventing electrolytic corrosion for a rolling bearing relate to the following [2] to [6].

[0018] [2] The electrolytic corrosion prevention member for a rolling bearing according to [1], characterized in that the annular portion is pressed against the side surface of the outer ring via a spacer. [3] The electrolytic corrosion prevention member for a rolling bearing according to [1], characterized in that the soft 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 soft porous body, and a soft porous body. [4] The electrolytic corrosion prevention member for a rolling bearing according to [2], characterized in that the soft 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 soft porous body, and a soft porous body. [5] The electrolytic corrosion prevention member for a rolling bearing according to any one of [1] to [4], wherein the elastic portion of the spring plate is bent midway. [6] The electrolytic corrosion prevention member for a rolling bearing according to any one of [1] to [4], characterized in that the elastic portion of the spring plate is formed flush with the annular portion.

[0019] The above object of the present invention is achieved by the following configuration [7] relating to an electrolytic corrosion prevention rolling bearing unit.

[0020] [7] 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, An electrolytic corrosion prevention rolling bearing unit, characterized in that the electrolytic corrosion prevention member for a rolling bearing according to any one of [1] to [6] is attached.

[0021] In the following description, the "electrolytic corrosion prevention member for a rolling bearing" will be simply referred to as the "electrolytic corrosion prevention member," and the "electrolytic corrosion prevention rolling bearing unit" will be simply referred to as the "bearing unit." [Effects of the Invention]

[0022] The electrolytic corrosion prevention member of the present invention comprises a soft conductive member attached to the elastic portion of a spring plate and abutting the end face of a shaft. The spring plate does not exert a strong biasing force on the end face of the shaft, making it less likely to generate wear powder. Furthermore, because the soft conductive member is made of a soft material, there is little damage to the shaft, which is the mating material.

[0023] Furthermore, since the spring plate does not require any processing on the rolling bearing and there is no restriction on the type of rolling bearing, it can be applied to existing rolling bearings, making it extremely versatile. Furthermore, the spring plate is a thin plate, which minimizes the increase in space required for the bearing unit to be installed.

[0024] The bearing unit of the present invention is fitted with the electrolytic corrosion prevention member of the present invention, which reduces the generation of wear powder and damage to the mating material, and is also highly versatile and does not require additional space. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 shows an example of an electrolytic corrosion prevention member of the present invention, in which (A) is a plan view thereof, (B) is a cross-sectional view taken along line AA in (A), and (C) is an enlarged view showing the bending portion of the elastic part in (B). [Figure 2] FIG. 2 is a cross-sectional view showing an example of a bearing unit to which the electrolytic corrosion prevention member shown in FIG. 1 is attached. [Figure 3] FIG. 3 is a diagram showing a state in which the electrolytic corrosion prevention member is pressed against the outer ring by a pressing member in FIG. [Figure 4] FIG. 4 is a cross-sectional view of a modified example of an electrolytic corrosion prevention member according to the present invention, corresponding to FIG. 1(B). [Figure 5] FIG. 5 is a cross-sectional view showing an example of a bearing unit to which the electrolytic corrosion prevention member shown in FIG. 4 is attached. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and can be implemented with any modifications within the scope of the gist of the present invention.

[0027] Fig. 1 shows an example of an electrolytic corrosion prevention member of the present invention, in which Fig. 1(A) is a plan view thereof, Fig. 1(B) is a cross-sectional view taken along line AA of Fig. 1(A), and Fig. 1(C) is an enlarged view showing the bending portion between the annular portion and the elastic portion in Fig. 1(B). Fig. 2 is a cross-sectional view showing an example of a bearing unit of the present invention, to which the electrolytic corrosion prevention member shown in Fig. 1 is attached.

[0028] In the bearing unit 100 shown in Fig. 2, the rolling bearing 50 is not limited, and a plurality of rolling elements (balls) 53 are held between an outer ring 51 and an inner ring 52 by a cage 54 so that they can roll freely, and are lubricated with a lubricating oil or grease composition. In this case, the rotating ring is the inner ring 52, and a shaft 60 that is directly connected to a motor (not shown) is fitted into the inner ring 52. The shaft 60 is fitted so that an end face 60a is flush with an end face 52a of the inner ring 52. The outer ring 51 is a fixed ring, and is fixed to a housing 70.

[0029] 1, the electrolytic corrosion prevention member 1 includes a spring plate 10 composed of an annular portion 11 and a single elastic portion 13 extending from an inner peripheral end portion 12 of the annular portion 11 toward the center of the annular portion 11. As shown in FIG. 2, when the elastic portion 13 is attached to the bearing unit 100, the elastic portion 13 is bent toward the right side in the drawing, starting from the elastic base portion 14, so as to face the end face 60a of the shaft 60 fitted into the inner ring 52 of the rolling bearing 50.

[0030] The spring plate 10 is made entirely of a thin plate made of a conductive material such as metal, and when the conductive material is metal, stainless steel is preferred because it is easy to process and is less prone to rust.

[0031] A soft conductive member 20 is attached to the tip portion of the elastic portion 13, i.e., the central portion of the annular portion 11, on the surface facing the end face 60a of the shaft 60 fitted in the rolling bearing 50, and the spring plate 10 and the soft conductive member 20 constitute the electrolytic corrosion prevention member 1. The soft conductive member 20 is attached to the elastic portion 13 using an adhesive.

[0032] The soft conductive member 20 is a soft base material that has a conductive material mixed in or supported thereon. Examples of the soft base material include porous materials such as paper, cloth, and nonwoven fabric, and resin sheets. Examples of the conductive material include metal fibers, crushed materials, and powders of metals such as silver, copper, gold, aluminum, and stainless steel, or conductive carbon fibers, crushed materials, and powders. Commercially available soft conductive members, such as those labeled "conductive sheets," can also be used. Among these, the soft conductive member is preferably composed of at least one selected from the group consisting of resin-impregnated nonwoven fabrics, resin-impregnated nonwoven fabrics and woven fabrics, resin-impregnated soft porous materials such as woven fabrics and sponges, and soft porous materials such as sponges.

[0033] 1(C), the bending angle θ between the annular portion 11 and the elastic portion 13 is set appropriately so that the soft conductive member 20 abuts against the end surface 60a of the shaft 60 when attached to the bearing unit 100. The bending angle θ can also be used to adjust the biasing force of the soft conductive member 20 on the end surface 60a of the shaft 60; the biasing force can be increased by reducing the bending angle θ, and conversely, the biasing force can be decreased by increasing the bending angle θ.

[0034] There is no limitation on the planar shape of the soft conductive member 20, and it may be a rectangle other than the circle shown in Fig. 1(A) or may be a plurality of small pieces.

[0035] 3, in this embodiment, the annular portion 11 of the electrolytic corrosion prevention member 1 is pressed against the side surface of the outer ring 51 by the conductive pressing member 80 via the conductive spacer 30. The thickness of the spacer 30 may be determined taking into consideration the amount of pressure applied by the spring plate 10A and the thickness of the soft conductive member 20. The annular portion 11 of the electrolytic corrosion prevention member 1 may also be in direct contact with the side surface of the outer ring 51 without providing the spacer 30.

[0036] In this type of inner ring rotating bearing unit 100, current from the motor normally flows through the shaft 60 to the inner ring 52, conducting current through the interior of the bearing to the rolling elements 53 and outer ring 51, causing electrolytic corrosion in the rolling bearing 50. Therefore, in the present invention, the electrolytic corrosion prevention member 1 is mounted in the housing 70 so that the soft conductive member 20 abuts against the end face 60a of the shaft 60. The annular portion 11 is in electrical contact with the side surface of the outer ring 51 via the conductive spacer 30, and is also in electrical contact with the conductive pressing member 80.

[0037] As a result, the current from the shaft 60 flows from the soft conductive member 20 to the elastic portion 13 and the annular portion 11 of the spring plate 10, and then flows to the housing 70 via the outer peripheral end surface 15 of the annular portion 11, the pressing member 80, the spacer 30 and the outer ring 51, so that no current flows inside the bearing and the rolling bearing 50 does not suffer from electrolytic corrosion. 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 but flows to the housing 70. In addition, in this embodiment, the outer peripheral end surface 15 of the annular portion 11 and the spacer 30 abut against the housing 70, but they may be configured not to abut against the housing 70 but to be sandwiched between the outer ring 51 and the pressing member 80. In this case, the current flowing through the annular portion 11 flows to the housing 70 via the outer ring 51 and the pressing member 80.

[0038] Furthermore, since the end surface 60a of the shaft 60 is in contact with the soft conductive member 20, it is not damaged, and a decrease in the rotation torque of the shaft 60 can be suppressed. Moreover, the base material of the soft conductive member 20 is porous and has oil absorption and oil retention properties, making it difficult for an oil film to form and providing good conductivity even when used in oil. Furthermore, by using a porous base material for the soft conductive member 20, the coefficient of friction is reduced even when the soft conductive member 20 is used in an environment other than oil, and a decrease in the rotational torque of the inner ring 52 can be prevented. Furthermore, it is preferable that the soft conductive member 20 abuts on the end face 60a of the shaft 60 near the center of the shaft, and since the peripheral speed is low near the center of the shaft, wear powder is less likely to be generated.

[0039] Furthermore, the spring plate 10 of the electrolytic corrosion prevention member 1 is a thin plate, which minimizes the increase in space required for the bearing unit 100. In addition, there are no restrictions on the rolling bearing 50 and no processing is required, so it can be applied to existing rolling bearings and is extremely versatile.

[0040] By increasing the contact area between the soft conductive member 20 of the electrolytic corrosion prevention member 1 and the end face 60a of the shaft 60 of the rolling bearing 50, electrolytic corrosion of the rolling bearing 50 can be more effectively prevented. Because the spring plate 10 is an elastic member made of a curved thin plate as a whole, when the annular portion 11 of the electrolytic corrosion prevention member 1 is pressed against the outer ring 51, the elastic force caused by the pressing acts on the elastic portion 13, which is pushed out so that the bending angle θ shown in FIG. 1(C) increases, and the entire elastic portion 13 moves toward the rolling bearing 50. Accordingly, the portion of the soft conductive member 20 that was away from the end face 60a of the shaft 60 in FIG. 2 also moves toward the rolling bearing 50, and almost the entire soft conductive member 20 comes into contact with the end face 60a of the shaft 60.

[0041] The present invention is not limited to the above-described embodiment, and can be modified and improved as appropriate. For example, in the above embodiment, the elastic portion 13 of the spring plate 10 is bent midway, but it may be formed flush with the annular portion 11 without being bent at the elastic base portion 14. That is, as shown in Fig. 4, the annular portion 11A and the elastic portion 13A are continuous in a straight line in a side view.

[0042] 5, when the annular portion 11 of the electrolytic corrosion prevention member 1 is sandwiched between the flange portion 71 of the housing 70 and the side surface of the outer ring 51, the elastic portion 13 of the electrolytic corrosion prevention member 1 elastically deforms by an amount corresponding to the thickness of the soft conductive member 20, and the bending reaction force of the spring plate 10 causes the soft conductive member 20 to abut against the end face 60a of the shaft 60. This allows the bearing unit 100 to achieve the same function as the above embodiment.

[0043] In this case, bending of the spring plate 10 is not necessary, so the electrolytic corrosion prevention member 1 can be manufactured inexpensively, and the spring plate 10 and the soft conductive member 20 can be easily bonded together.

[0044] In addition, in this embodiment, the spring plate is configured to have one elastic portion extending toward the center of the annular portion, but it may also be configured to have multiple elastic portions extending radially toward the center of the annular portion. [Explanation of symbols]

[0045] 1. Electrolytic corrosion prevention materials 10 spring plate 11 Annular part 12 Inner circumference end 13,14 Elastic part 15 Outer edge 20 Soft conductive material 30 spacer 50 bearings 51 outer ring 52 Inner circle 52a,60a end face 53 Rolling elements 54 Cage 60 shaft 70 Housing 80 Retaining member 100 bearing unit

Claims

1. In a rolling bearing unit including an inner ring rotating type rolling bearing in which an outer ring is fixed to a housing and a shaft directly connected to a motor is fitted into an inner ring, an electrolytic corrosion prevention member is attached to the rolling bearing unit to prevent electrolytic corrosion of the rolling bearing, a spring plate made of a thin plate of conductive material, the spring plate including a circular portion and an elastic portion extending continuously from an inner peripheral end of the circular portion to a center of the circular portion; a soft conductive member attached to a surface of the elastic portion facing the rolling bearing; In addition to providing the soft conductive member is capable of contacting an end surface of the shaft, the soft conductive member is composed of at least one selected from a resin-impregnated nonwoven fabric, a resin-impregnated woven fabric, and a resin-impregnated soft porous body; An electrolytic corrosion prevention member for a rolling bearing, comprising:

2. 2. The electrolytic corrosion prevention member for a rolling bearing according to claim 1, wherein the annular portion is pressed against the side surface of the outer ring via a spacer.

3. 2. The electrolytic corrosion prevention member for a rolling bearing according to claim 1, wherein the elastic portion of the spring plate is bent midway.

4. 2. The electrolytic corrosion prevention member for a rolling bearing according to claim 1, wherein the elastic portion of the spring plate is formed flush with the annular portion.

5. In a rolling bearing unit having an inner ring rotating type rolling bearing in which an outer ring is fixed to a housing and a shaft directly connected to a motor is fitted into the inner ring, an electrolytic corrosion prevention member attached to the rolling bearing unit to prevent electrolytic corrosion of the rolling bearing, a spring plate made of a thin plate of conductive material, the spring plate including a circular portion and an elastic portion extending continuously from an inner peripheral end of the circular portion to a center of the circular portion; a soft conductive member attached to a surface of the elastic portion facing the rolling bearing; In addition to providing the soft conductive member is capable of contacting an end surface of the shaft, The elastic portion of the spring plate is formed flush with the annular portion. An electrolytic corrosion prevention member for a rolling bearing, comprising:

6. The bearing has an outer ring fixed to a housing and an inner ring rotating type in which a shaft directly connected to a motor is fitted into the inner ring, An electrolytic corrosion prevention rolling bearing unit, comprising the electrolytic corrosion prevention member for a rolling bearing according to any one of claims 1 to 5 attached thereto.

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