Electric corrosion prevention member for rolling bearing and electric 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 a rolling bearing in a rolling bearing unit, and to an electrolytic corrosion prevention rolling bearing unit equipped with the electrolytic corrosion prevention member for a rolling bearing. [Background technology]

[0002] In recent years, electric vehicles in which an electric motor serving as a drive source is disposed inside or near the wheel to drive the wheel are becoming more and more practical. Such drive motors are generally called in-wheel motors. A typical in-wheel motor has a structure in which a stator is fixed to a motor housing, and a rotor is disposed on the inner diameter side of the stator with a radial gap therebetween, making it a so-called inner rotor type motor. In addition, in consideration of the motor's performance and control performance, a brushless DC motor driven by an inverter is often used as the drive method for in-wheel motors.

[0003] In inverter drive systems, a potential difference occurs between the stator and rotor due to parasitic capacitance between them. This potential difference generates a so-called shaft voltage and shaft current, and when this shaft current passes through the rolling bearing that supports the rotor, it causes a phenomenon known as "electrical corrosion," which damages the rolling bearing. 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, which roughens the rolling surfaces and rolling element surfaces of the bearing, causing noise and vibration, and if excessive electrical corrosion occurs, it can also affect the life of the bearing.

[0004] One approach to prevent electrolytic corrosion in rolling bearings is to use conductive materials. For example, Patent Documents 1 and 2 propose a bearing consisting of a contact body for electrical conductivity with the motor rotor, an elastic body for pressing the contact body towards 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 conductive with the motor stator via the motor housing.

[0005] Moreover, Patent Document 3 proposes an earthing device in which the tips of broom-shaped conductive fibers are brought into contact with the outer circumferential surface of a rotating shaft.

[0006] Furthermore, Patent Document 4 proposes an electrical corrosion prevention device in which the annular seat that contacts the end face of the outer ring of the bearing 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 outer ring of the bearing fitted into a bearing housing, and the contact piece is abutted against the center of the end face of the rotating shaft fitted into the inner ring of the bearing, 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 accommodating a rod-shaped conductive brush in a support hole provided in one of the two raceways, and using an elastic member to urge the tip of the conductive brush toward the other raceway so that it slides against the other raceway, thereby establishing electrical conductivity between the two raceways. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2011-135720 A [Patent Document 2] JP 2011-135722 A [Patent Document 3] JP 2020-127257 A [Patent Document 4] JP 2002-146568 A [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 any of the techniques described in the patent documents, wear powder generated from the conductive member may cause contamination of the lubricating oil or grease composition sealed for lubrication, which may cause damage to the rolling surfaces or rolling contact surfaces.In addition, the wear powder may damage the mating material of the conductive member.

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

[0011] In addition, in Patent Document 3, the tip of the broom-shaped conductive fiber is brought into contact with the outer circumferential surface of the rotating shaft, but in order to increase the contact area between the tip of the broom-shaped conductive fiber and the rotating shaft compared to when the tip is simply brought into contact with the rotating shaft, the broom-shaped conductive fiber is brought into contact with the outer circumferential surface of the rotating shaft in a bent state. In other words, the tip of the broom-shaped conductive fiber is in contact with the outer circumferential surface of the rotating shaft with a relatively strong pressing force, so that wear powder is generated. At the same time, the outer circumferential surface of the rotating shaft, which is the mating material of the broom-shaped conductive fiber, 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 in a biased state in contact with the other raceway, which generates 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, it is necessary to form a support hole in the raceway to accommodate the conductive brush and the elastic member, which places a large load on the raceway.

[0014] Therefore, the present invention aims to provide an electrolytic corrosion prevention member that is space-saving and inexpensive, which not only suppresses the generation of wear powder from a conductive member or wear powder caused by sliding contact between a conductive member and a mating material, but also suppresses damage to the mating material, does not require new processing on the bearing, and is not limited to the type of bearing, making it compatible with existing bearings, and also provides 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 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 a conductive material, the spring plate including an annular portion and an elastic portion extending continuously from an inner peripheral end of the annular portion to a center of the annular 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 an 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 electrolytic corrosion prevention member 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], characterized in that 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 electrolytic corrosion prevention rolling bearing unit having the following configuration [7].

[0020] [7] An inner ring rotating type rolling bearing having an outer ring fixed to a housing and an inner ring fitted with a shaft directly connected to a motor; An electrolytic corrosion prevention rolling bearing unit, comprising an electrolytic corrosion prevention member for a rolling bearing according to any one of [1] to [6], attached thereto.

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

[0022] The electrolytic corrosion prevention member of the present invention is a soft conductive member attached to the elastic portion of a spring plate and abutted against the end face of a shaft. The urging force of the spring plate against the end face of the shaft of the soft conductive member is not very strong, so wear powder is unlikely to be generated. Moreover, because the soft conductive member is made of a soft material, damage to the shaft, which is the mating material, is minimal.

[0023] In addition, the spring plate does not require any processing on the rolling bearing, and there is no restriction on the type of rolling bearing, so it can be applied to existing rolling bearings, making it highly versatile. Furthermore, the spring plate is a thin plate, so it can minimize the increase in space required for the bearing unit to be mounted.

[0024] Since the bearing unit of the present invention is fitted with the electrolytic corrosion prevention member of the present invention, the generation of wear powder and damage to the mating material are suppressed, and furthermore, the bearing unit is highly versatile and does not require an increase in space. [Brief description 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 of (A), and (C) is an enlarged view showing the bent portion of the elastic part in (B). [Diagram 2] FIG. 2 is a cross-sectional view showing an example of a bearing unit equipped with the electrolytic corrosion prevention member shown in FIG. [Diagram 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 corresponding to FIG. 1(B) of an electrolytic corrosion prevention member according to a modified example of the present invention. [Diagram 5] FIG. 5 is a cross-sectional view showing an example of a bearing unit equipped with the electrolytic corrosion prevention member shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the 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 modified and implemented as desired without departing from the gist of the present invention.

[0027] 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 a bent portion between the annular portion and the elastic portion in (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 by a cage 54 between an outer ring 51 and an inner ring 52 so that they can roll freely, and are lubricated by a lubricating oil or a grease composition. Here, the rotating ring is the inner ring 52, and a shaft 60 directly connected to a motor (not shown) is fitted into it. 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, the elastic portion 13 is bent toward the right side in the figure, starting from an elastic base portion 14, so as to face an end face 60a of a shaft 60 fitted into an inner ring 52 of a rolling bearing 50 when the elastic portion 13 is attached to a bearing unit 100.

[0030] The spring plate 10 is made entirely of a thin plate made of a conductive material such as metal. When the conductive material is a 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 having a conductive material mixed therein or supported thereon. The soft base material may be a porous body such as paper, cloth, or nonwoven fabric, or a resin sheet, and the conductive material may be metal fibers, crushed materials, or powders such as silver, copper, gold, aluminum, or stainless steel, or conductive carbon fibers, crushed materials, or powders. The soft conductive member may be a commercially available product called a "conductive sheet." Among these, it is preferable that the soft conductive member is composed of at least one selected from resin-impregnated nonwoven fabric, resin-impregnated nonwoven fabric, resin-impregnated woven fabric, resin-impregnated soft porous body such as woven fabric or sponge, and soft porous body such as sponge.

[0033] 1(C), the bending angle θ between the annular portion 11 and the elastic portion 13 is appropriately set 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 biasing force of the soft conductive member 20 on the end surface 60a of the shaft 60 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.

[0034] There is no limitation to 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 number 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 a conductive pressing member 80 via a conductive spacer 30. The thickness of the spacer 30 may be determined taking into consideration the pressing amount of 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 directly abut against the side surface of the outer ring 51 without providing the spacer 30.

[0036] In such an inner ring rotating type bearing unit 100, current from the motor normally flows through the shaft 60 to the inner ring 52, and current flows inside the bearing to the rolling elements 53 and the outer ring 51, causing electrolytic corrosion in the rolling bearing 50. Therefore, in the present invention, the electrolytic corrosion prevention member 1 is attached to 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, 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 face 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 electrical corrosion. Since the outer ring 51 has a large contact area with the housing 70 , the current that flows through the outer ring 51 does not pass through the rolling elements 53 but flows to the housing 70 . 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 to be sandwiched between the outer ring 51 and the pressing member 80 without abutting against the housing 70. In that 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 face 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, since the base material of the soft conductive member 20 is a porous body and has oil absorption and oil retention properties, it is difficult for an oil film to form and has good conductivity even when used in oil. Furthermore, by making the base material of the soft conductive member 20 a porous body, the friction coefficient is reduced even when used in environments other than oil, and a decrease in the rotational torque of the inner ring 52 can be suppressed. 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 can minimize an 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 the member can be applied to existing rolling bearings and is highly 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. Since the spring plate 10 is an elastic member made of a curved thin plate as a whole, by pressing the annular portion 11 of the electrolytic corrosion prevention member 1 against the outer ring 51, the elastic force caused by the pressing acts on the elastic portion 13, which is pushed and spread 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 clamped 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 equivalent 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, since bending of the spring plate 10 is not necessary, the electrolytic corrosion prevention member 1 can be manufactured at low cost, and the spring plate 10 and the soft conductive member 20 can be bonded easily.

[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. Materials for preventing electrolytic corrosion 10 Spring plate 11 Circular Ring 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 Holding member 100 Bearing unit

Claims

1. 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, the rolling bearing unit being provided with an electrolytic corrosion prevention member for preventing electrolytic corrosion of the rolling bearing, the electrolytic corrosion prevention member comprising: a spring plate made of a thin plate of a conductive material, the spring plate including an annular portion and an elastic portion extending continuously from an inner peripheral end of the annular portion to a center of the annular 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 an end surface of the shaft. 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 a side surface of the outer ring via a spacer.

3. 2. The electrolytic corrosion prevention member for a rolling bearing as described in claim 1, characterized in that the soft conductive member is composed of at least one selected from the group consisting of resin-impregnated nonwoven fabric, nonwoven fabric, resin-impregnated woven fabric, woven fabric, resin-impregnated soft porous body, and soft porous body.

4. 3. The electrolytic corrosion prevention member for a rolling bearing as described in claim 2, characterized in that the soft conductive member is composed of at least one selected from the group consisting of 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. 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.

6. 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.

7. The bearing has an outer ring fixed to a housing and an inner ring fitted with a shaft directly connected to a motor, 7. A rolling bearing unit having electrolytic corrosion prevention member for a rolling bearing according to claim 1 attached thereto.

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