JP7799136B2 - Sliding member and rolling bearing - Google Patents

Description

The present disclosure relates to sliding members and rolling bearings.

Patent Document 1 discloses a rolling bearing with an anti-electrolytic corrosion function. The rolling bearing described in Patent Document 1 is a bearing that supports the rotating shaft of an electric motor installed in an electric vehicle or the like. This rolling bearing comprises an outer ring, an inner ring, multiple balls arranged between the outer and inner rings, and an annular seal (sliding member) that closes the end opening of the bearing's internal space between the outer and inner rings. The seal comprises conductive rubber. The inner and outer circumferential edges of this rubber are in contact with the inner and outer rings, respectively. The rubber contacting the inner and outer rings electrically connects the inner ring to the outer ring through the rubber. The rubber contacting the inner and outer rings prevents current from flowing between the inner ring and the balls, and between the outer ring and the balls, thereby suppressing electrolytic corrosion of the inner ring raceway, outer ring raceway, and balls.

JP 2015-102200 A

The rubber seal (sliding member) in Patent Document 1 has a certain degree of conductivity due to the carbon fiber kneaded into it. However, there is a need to further increase the conductivity of the seal in order to further suppress electrolytic corrosion of the track. Therefore, the present disclosure aims to increase the conductivity of the sliding member.

The slide member of the present disclosure comprises:
A metal ring;
a sheet that is a nonwoven or woven fabric formed of conductive fibers;
rubber,
The sheet is
a fixing portion that is fixed in contact with a first member made of steel on a first side in a radial direction of the metal ring;
a sliding portion that slidably contacts a second member made of steel on a second radial side of the metal ring;
an intermediate portion located between the fixed portion and the sliding portion,
the metal ring has a first surface disposed on a first axial side or on both the first axial side and the first radial side, and a second surface disposed on a second axial side or on both the second axial side and the second radial side;
the intermediate portion is disposed on the first surface;
the fixing portion is disposed on the first side in the radial direction relative to the end portion on the first side in the radial direction of the metal ring,
the sliding portion is disposed on the second radial side of the end portion of the metal ring on the second radial side,
the rubber includes a first portion, a plurality of second portions spaced apart in the circumferential direction, and a plurality of third portions spaced apart in the circumferential direction;
the first portion is disposed on a first axial side of the intermediate portion, the fixed portion, and the sliding portion;
the second portion is disposed on the second surface of the metal ring beyond a first radial end of the metal ring from the first portion;
the third portion is disposed on the second surface of the metal ring beyond a second radial end of the metal ring from the first portion,
the intermediate portion and the fixed portion are continuous between the second portions adjacent in the circumferential direction,
The intermediate portion and the sliding portion are continuous between the third portions adjacent in the circumferential direction.

The rolling bearing of the present disclosure comprises:
an inner ring having an inner ring raceway;
an outer ring having an outer ring raceway disposed radially outward of the inner ring raceway;
a plurality of rolling elements rollably disposed between the inner ring raceway and the outer ring raceway;
The above-mentioned sliding member,
one of the inner ring and the outer ring is the first member,
The other of the inner ring and the outer ring is the second member.

The sliding member of the present disclosure includes a nonwoven or woven fabric sheet formed from conductive fibers. The sheet has lower electrical resistance than rubber made of rubber with carbon fibers kneaded into it, and can electrically connect a first member and a second member. The sliding member of the present disclosure can pass an electric current from one of the first member and the second member to the other via this sheet. The sliding member of the present disclosure can firmly bond the first rubber portion, the sheet, and the metal ring via the second and third rubber portions.

FIG. 1 is a cross-sectional view showing an example of a rolling bearing according to the present disclosure. FIG. 2 is a side view of the sliding member as seen from a second axial side. FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a cross-sectional view taken along line BB in FIG. 5 is an enlarged cross-sectional view of a radially outer portion of the sliding member shown in FIG. 3. FIG. 6 is an enlarged cross-sectional view of a radially inner portion of the sliding member shown in FIG. 3. FIG. 7 is an enlarged cross-sectional view of the radially outer portion of the sliding member shown in FIG. 4. FIG. 8 is an enlarged cross-sectional view of the radially inner portion of the sliding member shown in FIG. 4. FIG. FIG. 9 is a cross-sectional view showing a part of a molding die for the sliding member. FIG. 10 is a cross-sectional view showing a part of a molding die for a sliding member. FIG. 11 is an enlarged photograph showing the radially inner end of the sliding member.

<Summary of the embodiment of the present disclosure>
Below, an outline of the embodiments of the present disclosure will be listed and described.

(1) The slide member of the present disclosure is
A metal ring;
a sheet that is a nonwoven or woven fabric formed of conductive fibers;
rubber,
The sheet is
a fixing portion that is fixed in contact with a first member made of steel on a first side in a radial direction of the metal ring;
a sliding portion that slidably contacts a second member made of steel on a second radial side of the metal ring;
an intermediate portion located between the fixed portion and the sliding portion,
the metal ring has a first surface disposed on a first axial side or on both the first axial side and the first radial side, and a second surface disposed on a second axial side or on both the second axial side and the second radial side;
the intermediate portion is disposed on the first surface;
the fixing portion is disposed on the first side in the radial direction relative to the end portion on the first side in the radial direction of the metal ring,
the sliding portion is disposed on the second radial side of the end portion of the metal ring on the second radial side,
the rubber includes a first portion, a plurality of second portions spaced apart in the circumferential direction, and a plurality of third portions spaced apart in the circumferential direction;
the first portion is disposed on a first axial side of the intermediate portion, the fixed portion, and the sliding portion;
the second portion is disposed on the second surface of the metal ring beyond a first radial end of the metal ring from the first portion;
the third portion is disposed on the second surface of the metal ring beyond a second radial end of the metal ring from the first portion,
the intermediate portion and the fixed portion are continuous between the second portions adjacent in the circumferential direction,
The intermediate portion and the sliding portion are continuous between the third portions adjacent in the circumferential direction.

According to this configuration, the sliding member includes a sheet that is a nonwoven or woven fabric made of conductive fibers. The sheet has lower electrical resistance than rubber made of rubber with carbon fibers kneaded into it, and the sliding member can electrically connect the first member and the second member. The sliding member can pass an electric current from one of the first member and the second member to the other via the sheet. The sliding member can firmly bond the first rubber portion, the sheet, and the metal ring by the second and third rubber portions.

(2) In the sliding member of (1) of the present disclosure, the sheet has holes that pass through the second portion and the third portion, respectively.
According to this configuration, the sliding member can be arranged such that the second and third portions pass from the first portion of the rubber through the holes in the sheet and are respectively disposed on the second surface of the metal ring.

(3) The rolling bearing of the present disclosure has
an inner ring having an inner ring raceway;
an outer ring having an outer ring raceway disposed radially outward of the inner ring raceway;
a plurality of rolling elements rollably disposed between the inner ring raceway and the outer ring raceway;
The sliding member according to (1) or (2) above,
one of the inner ring and the outer ring is the first member,
The other of the inner ring and the outer ring is the second member.

With this configuration, the rolling bearing can electrically connect the outer ring and inner ring with a sheet, and current can be passed from one of the outer ring and inner ring to the other via this sheet, suppressing electrolytic corrosion of the outer ring raceway and inner ring raceway.

<Details of the embodiment of the present disclosure>
Hereinafter, embodiments of the present disclosure will be described.
FIG. 1 is a cross-sectional view showing an example of a rolling bearing according to the present disclosure.
1 supports a rotating shaft S of a motor mounted on, for example, an electric vehicle or a hybrid vehicle. In Fig. 1, the rotating shaft S is indicated by a virtual line (two-dot chain line).

The rolling bearing 10 comprises an outer ring 11, an inner ring 12, multiple rolling elements 13, a cage 14, and a sliding member 15. In this embodiment, the rolling elements 13 are balls. The rolling bearing 10 is a deep groove ball bearing. The outer ring 11 is attached to a housing H of the motor. The inner ring 12 is fitted onto and fixed to the outer surface of the rotating shaft S. In FIG. 1, the housing H is indicated by a virtual line (two-dot chain line). In this embodiment, the outer ring 11 is a fixed ring, and the inner ring 12 is a rotating ring. The outer ring 11 and the inner ring 12 are formed from a steel material such as bearing steel. High-carbon chromium bearing steel (e.g., SUJ2 or SUJ3 as specified in the JIS standard) can be used as the bearing steel. However, the outer ring 11 and the inner ring 12 may also be made from other steel materials such as carburized bearing steel, carbon steel, chromium steel, or stainless steel.

The outer ring 11 and the inner ring 12 are arranged concentrically. In this embodiment, the central axes of the outer ring 11 and the inner ring 12 coincide with the central axis C of the rolling bearing 10. Furthermore, in this embodiment, the direction along the central axis C and the direction parallel to the central axis C are defined as the "axial direction." Similarly, the direction perpendicular to the central axis C is defined as the "radial direction." Similarly, the direction along a circle centered on the central axis C is defined as the "circumferential direction." In this embodiment, the left side of FIG. 1 is referred to as the first axial side, and the right side of FIG. 1 is referred to as the second axial side. Furthermore, in this specification, one of the radially outer and inner sides may be referred to as the radially first side, and the other may be referred to as the radially second side. Specifically, in this embodiment, the radially outer side is referred to as the radially first side, and the radially inner side is referred to as the radially second side.

The outer ring raceway 21 is provided on the inner peripheral surface of the outer ring 11. The balls 13 roll on this outer ring raceway 21. Two shoulders 22 are provided on both axial sides of the outer ring raceway 21. Two annular grooves 23 are provided between the shoulders 22 and the side surfaces of the outer ring 11. The annular grooves 23 have a circumferentially continuous annular groove shape. The sliding member 15 is attached to the annular groove 23 located on the first axial side of the outer ring 11. The sliding member 15 is not attached to the annular groove 23 located on the second axial side of the outer ring 11. However, the sliding member 15 may be attached to the annular groove 23 located on the second axial side of the outer ring 11. If the sliding member 15 is not attached to the annular groove 23, the annular groove 23 located on the second axial side of the outer ring 11 may be omitted.

The inner ring raceway 31 is provided on the outer peripheral surface of the inner ring 12. The balls 13 roll on this inner ring raceway 31. Two shoulders 32 are provided on both axial sides of the inner ring raceway 31. Two sliding member contact surfaces 33 are provided between the shoulders 32 and the side surfaces of the inner ring 12. The sliding member contact surface 33 is provided in an annular shape around the entire circumference of the inner ring 12. The sliding member contact surface 33 is groove-shaped in a cross section including the central axis of the inner ring 12. The radially inner end of the sliding member 15 contacts the sliding member contact surface 33.

The balls 13 are arranged between the outer ring 11 and the inner ring 12. The balls 13 are in rolling contact with the outer ring raceway 21 and the inner ring raceway 31. The multiple balls 13 are held at circumferential intervals by an annular cage 14.

The cage 14 has an annular body 16 and a plurality of horns (pillars) 17. The annular body 16 is provided on the second axial side of the balls 13. The plurality of horns (pillars) 17 extend from the annular body 16 to the first axial side. The pocket 18 is the space between two circumferentially adjacent horns 17 on the first axial side of the annular body 16. The balls 13 are accommodated in the pocket 18. The pocket 18 is open on the first axial side.

The sliding member 15 is formed in an annular shape. The sliding member 15 is fixed to the outer ring (first member) 11 and slides against the inner ring (second member) 12. Specifically, the sliding member 15 is fixed to the outer ring 11 by having its radially outer end (end on the first radial side) fitted into an annular groove 23 on the first axial side of the outer ring 11. The radially inner end (end on the second radial side) of the sliding member 15 contacts the sliding member contact surface 33 of the inner ring 12. The sliding member 15 is provided only on the first axial side of the rolling bearing 10, and is not provided on the second axial side of the rolling bearing 10. Therefore, the bearing internal space K1, which is the annular space between the outer ring 11 and the inner ring 12 and in which the balls 13 reside, opens to the second axial side. The sliding member 15 separates the bearing internal space K1 where the balls 13 are present from the bearing external space K2, which is a space on the first axial side of the rolling bearing 10.

The sliding member 15 is electrically conductive between its radially outer end and its radially inner end. Specifically, the sliding member 15 includes an electrically conductive sheet 43, the fixed portion 45 of which is exposed on the surface at the radially outer end of the sliding member 15, and the sliding portion 46 of which is exposed on the surface at the radially inner end of the sliding member 15. Therefore, the sliding member 15 forms an electrical path that prevents current generated by a motor or the like from flowing between the outer ring 11 and the inner ring 12 via the rolling elements 13.

An oil film made of lubricating oil or grease is formed between the balls 13 and the inner ring raceway 31, and between the balls 13 and the outer ring raceway 21. The oil film has insulating properties. The insulating properties of the oil film insulate the balls 13 and the inner ring raceway 31, and between the balls 13 and the outer ring raceway 21. When an oil film is formed between the balls 13 and the inner ring raceway 31 and a potential difference of less than a predetermined value occurs between the balls 13 and the inner ring raceway 31, no current flows between the inner ring raceway 31 and the balls 13. When an oil film is formed between the balls 13 and the outer ring raceway 21 and a potential difference of less than a predetermined value occurs between the balls 13 and the outer ring raceway 21, no current flows between the balls 13 and the outer ring raceway 21. However, when the oil film between the balls 13 and the inner ring raceway 31 is partially broken down, or when a potential difference exceeding a predetermined value occurs between the balls 13 and the inner ring raceway 31, current flows between the balls 13 and the inner ring raceway 31, and the current may cause electrolytic corrosion in the balls 13 and/or the inner ring raceway 31. When the oil film between the balls 13 and the outer ring raceway 21 is partially broken down, or when a potential difference exceeding a predetermined value occurs between the balls 13 and the outer ring raceway 21, current flows between the balls 13 and the outer ring raceway 21, and the current may cause electrolytic corrosion in the balls 13 and/or the outer ring raceway 21. The rolling bearing 10 of this embodiment is provided with a sliding member 15 that forms a current path, so that the potential difference between the outer ring 11 and the inner ring 12 is reduced by passing a current between the outer ring 11 and the inner ring 12 via the sliding member 15, before the potential difference between the balls 13 and the inner ring raceway 31 or the potential difference between the balls 13 and the outer ring raceway 21 becomes large. By reducing the potential difference between the outer ring 11 and the inner ring 12, the occurrence of electrolytic corrosion of the balls 13, the inner ring raceway 31 and the outer ring raceway 21 is suppressed.

[Specific structure of sliding member 15]
Fig. 2 is a side view of the sliding member as seen from the second axial side. Fig. 3 is a cross-sectional view taken along line A-A in Fig. 2. Fig. 4 is a cross-sectional view taken along line B-B in Fig. 2. Fig. 5 is an enlarged cross-sectional view of a radially outer portion of the sliding member shown in Fig. 3. Fig. 6 is an enlarged cross-sectional view of a radially inner portion of the sliding member shown in Fig. 3. Fig. 7 is an enlarged cross-sectional view of a radially outer portion of the sliding member shown in Fig. 4. Fig. 8 is an enlarged cross-sectional view of a radially inner portion of the sliding member shown in Fig. 4.

As shown in Figures 3 and 4, the sliding member 15 has a metal ring 41, rubber 42, and a sheet 43. The metal ring 41, rubber 42, and sheet 43 are all annular. The metal ring 41, rubber 42, and sheet 43 are bonded together to form a single unit.

The metal ring 41 is formed from a metal such as galvanized steel plate or stainless steel. The metal ring 41 is formed by processing a plate material. The metal ring 41 includes an annular portion 41a formed in an annular ring shape and a cylindrical portion 41b formed in a cylindrical shape. The annular portion 41a is arranged perpendicular to the axial direction. The cylindrical portion 41b is arranged parallel to the axial direction. The cylindrical portion 41b is arranged at the radial outer end of the annular portion 41a. The cylindrical portion 41b extends from the radial outer end of the annular portion 41a to the second axial side (the bearing internal space K1 side). The annular portion 41a and the cylindrical portion 41b of the metal ring 41 are formed by plastically processing the plate material into a substantially L-shaped shape.

5 and 7, in this embodiment, the side surface 41a1 on the first axial side of the annular portion 41a of the metal ring 41 and the peripheral surface 41b1 on the radially outer side (first radial side) of the cylindrical portion 41b are referred to as the "first surfaces 41a1, 41b1." The side surface 41a2 on the second axial side of the annular portion 41a of the metal ring 41 and the peripheral surface 41b2 on the radially inner side (second radial side) of the cylindrical portion 41b are referred to as the "second surfaces 41a2, 41b2." Therefore, the first surfaces 41a1, 41b1 and the second surfaces 41a2, 41b2 face in opposite directions in the axial and radial directions.

The rubber 42 is electrically conductive. The rubber 42 is manufactured by blending, for example, synthetic rubber with an electrically conductive material. The electrically conductive material may be carbon black, metal powder, or the like. The specific structure of the rubber 42 will be described later, along with the structure of the sheet 43.

The sheet 43 is made of a nonwoven or woven fabric made of conductive fibers. In this embodiment, the sheet 43 uses carbon fibers as the conductive fibers. However, the conductive fibers may be made of other materials, such as fibers made of conductive metals such as copper or nickel. The electrical resistance of the sheet 43 is lower than the electrical resistance of the rubber 42.

In this embodiment, the sheet 43 further contains a synthetic resin as a binder. The binder is fixed to the surface of a portion of the conductive fibers contained in the sheet 43. The sheet 43 in this embodiment is a nonwoven or woven fabric made of conductive fibers with the binder fixed thereto. In this embodiment, the sliding member 15 can use, for example, DonaCarbo (registered trademark) paper manufactured by Osaka Gas Chemicals Co., Ltd. as the sheet 43.

As shown in Figures 3 and 4, the sheet 43 integrally includes an intermediate portion 44, a fixed portion 45, and a sliding portion 46. The intermediate portion 44 is primarily bonded to the metal ring 41. The binder fixed to the surface of the conductive fibers contained in the sheet 43 is easily bonded to the metal ring 41 with an adhesive. As also shown in Figures 5 and 7, the intermediate portion 44 has a first portion 44a and a second portion 44b. The first portion 44a extends radially. The first portion 44a is bonded to the side surface 41a1 (first surface) on the first axial side (the bearing external space K2 side) of the annular portion 41a of the metal ring 41. The second portion 44b of the sheet 43 is bonded to the outer peripheral surface 41b1 (first surface) of the cylindrical portion 41b of the metal ring 41. The shape of the intermediate portion 44 of the sheet 43 is maintained primarily by the metal ring 41 and the rubber 42.

The fixed portion 45 of the seat 43 is formed at least partially continuous with the second portion 44b, which is the intermediate portion 44. As shown in Figures 5 and 7, the fixed portion 45 has a third portion 45a and a fourth portion 45b. The third portion 45a curves from the end of the second portion 44b of the intermediate portion 44 on the second axial side (the side facing the bearing internal space K1) and extends further radially outward. The fourth portion 45b curves from the radially outer end of the third portion 45a toward the first axial side. The tip of the fourth portion 45b forms the radially outer end of the seat 43. The tips of the third portion 45a and the fourth portion 45b are in direct contact with the annular groove 23 of the outer ring 11.

As shown in Figures 3 and 4, the sliding portion 46 of the seat 43 is formed at least partially continuous with the radially inner side of the first portion 44a, which is the intermediate portion 44. The sliding portion 46 has a fifth portion 46a at its radially inner end that directly contacts the sliding member contact surface 33 of the inner ring 12.

As shown in Figures 3 and 4, the rubber 42 is adhered to the sheet 43. The rubber 42 has first portions 42a, 42b, and 42c provided over substantially the entire side surface of the sheet 43 on the first axial side. As shown in Figures 5 and 7, a portion 42a of the first portion of the rubber 42 is provided in an area surrounded by the second portion 44b, the third portion 45a, and the fourth portion 45b of the sheet 43.

As shown in Figures 5 to 8, the other part 42b of the first part of the rubber 42 is provided with a substantially constant thickness along the side surface on the first axial direction side of the first part 44a of the intermediate portion 44 of the sheet 43. The other part 42c of the first part of the rubber 42 is provided with a substantially constant thickness along the side surface on the first axial direction side of the sliding portion 46 of the sheet 43.

As shown in Figures 2 and 3, the rubber 42 further has a second portion 42d and a third portion 42e. The second portions 42d and the third portions 42e are each provided in plurality at intervals in the circumferential direction. In this embodiment, the rubber 42 has four second portions 42d and four third portions 42e. The four second portions 42d and the four third portions 42e are arranged in the same phase in the circumferential direction.

3 and 5, the second portion 42d of the rubber 42 extends from the first portion 42a of the rubber 42 beyond the radially outer end of the metal ring 41 (the end on the second axial side of the cylindrical portion 41b) and is disposed on the second surface 41b2 of the metal ring 41. More specifically, the second portion 42d is disposed so as to cover the end face on the second axial side of the cylindrical portion 41b of the metal ring 41 and the inner circumferential surface 41b2 of the cylindrical portion 41b. The second portion 42d extends from the first portion 42a through a hole 43a formed in the sheet 43 to the second surface 41b2 of the metal ring 41.

As shown in Figures 3 and 6, the third portion 42e of the rubber 42 extends from the first portions 42b and 42c of the rubber 42 beyond the radially inner end of the annular portion 41a of the metal ring 41 and is disposed on the second surface 41a2 of the metal ring 41. More specifically, the third portion 42e covers the end face on the second radial side of the annular portion 41a and the side surface 41a2 on the second axial side. The third portion 42e is bonded to the side surface 41a2 of the annular portion 41a. The third portion 42e extends from the first portions 42b and 42c through a hole 43b formed in the sheet 43 to the second surface 41a2 of the metal ring 41.

The second portion 42d and the third portion 42e of the rubber 42 firmly bond the first portions 42a, 42b, and 42c of the rubber 42 to the sheet 43 and the metal ring 41. Therefore, the second portion 42d and the third portion 42e of the rubber 42 prevent the sheet 43 from peeling off from the metal ring 41, and prevent the rubber 42 from peeling off from the sheet 43.

Because the rubber 42 has higher rigidity than the sheet 43, the shape of the sheet 43 is maintained not only by the metal ring 41 but also by the rubber 42. As shown in Figures 5 and 7, a portion 42a of the first portion of the rubber 42 elastically supports the fourth portion 45b of the sheet 43 from the radially inner side. The cylindrical portion 41b of the metal ring 41 supports the portion 42a of the rubber 42 from the radially inner side. Therefore, the fixed portion (radial outer end) 45 of the sheet 43 is pressed against the annular groove 23 of the outer ring 11 by the elasticity of the portion 42a of the rubber 42 supported by the cylindrical portion 41b of the metal ring 41, ensuring reliable contact with the annular groove 23.

The sheet 43 includes a nonwoven or woven fabric made of conductive fibers. The sheet 43 contains voids within the material prior to the manufacture of the sliding member 15. After the manufacture of the sliding member 15, the rubber 42 is also present in the voids in the sheet 43. As described below, the sliding member 15 is manufactured by inserting the metal ring 41 and the sheet 43 into a mold, vulcanizing the rubber material that constitutes the rubber 42 to form it into a predetermined shape, and then bonding the rubber material to the metal ring 41 and the sheet 43. Hereinafter, this manufacturing process is also referred to as "vulcanization bonding." During this vulcanization bonding, the rubber 42 penetrates into the voids in the sheet 43. During vulcanization bonding, the rubber 42 is easily bonded to the binder.

At least a portion of the fixed portion 45 of the seat 43 contacts the annular groove 23 of the outer ring 11. Furthermore, at least a portion of the sliding portion 46 of the seat 43 (particularly the radial inner end portion 46a of the seat 43) contacts the sliding member contact surface 33 of the inner ring 12.

As shown in Figure 2, the second portions 42d of the rubber 42 are spaced apart in the circumferential direction. Therefore, the intermediate portion 44 and the fixed portion 45 of the sheet 43 are continuous between adjacent second portions 42d in the circumferential direction. This continuous portion is designated by the symbol 43c and is referred to as the first continuous portion 43c. The first continuous portion 43c is provided at four locations spaced apart in the circumferential direction.

Similarly, the third portions 42e of the rubber 42 are spaced apart in the circumferential direction. Therefore, the intermediate portion 44 and the sliding portion 46 of the sheet 43 are continuous between adjacent third portions 42e in the circumferential direction. This continuous portion is designated by the symbol 43d and is referred to as the second continuous portion 43d. The second continuous portion 43d is provided in four locations spaced apart in the circumferential direction. The first continuous portion 43c and the second continuous portion 43d are arranged in the same phase in the circumferential direction. In other words, the first continuous portion 43c and the second continuous portion 43d are located on a common radial line passing through the central axis C.

The circumferential length of each second portion 42d is greater than the circumferential length of each first continuous portion 43c. The circumferential length of each third portion 42e is greater than the circumferential length of each second continuous portion 43d. Therefore, the rubber 42, sheet 43, and metal ring 41 are firmly bonded over a wide circumferential range by the second portion 42d and the third portion 42e.

The sheet 43 includes a nonwoven or woven fabric in which multiple conductive fibers are in contact with each other. The conductive fibers in contact with each other are electrically conductive. The fixed portion 45, intermediate portion 44, and sliding portion 46 of the sheet 43 are continuous in the radial direction via the first and second continuous portions 43c, 43d. Therefore, the sheet 43 is conductive throughout the entire radial direction from the fixed portion 45 to the sliding portion 46 due to the contact between the conductive fibers. Because the sheet 43 is in contact with the outer ring 11 and the inner ring 12, the outer ring 11 and the inner ring 12 are electrically connected via the sheet 43. The conductive metal ring 41 and rubber 42 also contact the sheet 43. The outer ring 11 and the inner ring 12 are electrically connected via the conductive metal ring 41 and rubber 42 in addition to the sheet 43.

Therefore, the sliding member 15 of this embodiment can dissipate electric charge from one of the fixed portion 45 and the sliding portion 46 to the other. Furthermore, the sliding member 15 of this embodiment can dissipate electric charge from one of the member fixed to the fixed portion 45 and the member sliding on the sliding portion 46 to the other. The rolling bearing 10 of this embodiment can dissipate electric charge from one of the outer ring 11 and the inner ring 12 to the other of the outer ring 11 and the inner ring 12 via the sliding member 15, making it possible to suppress electrolytic corrosion of the balls 13 and the outer ring raceway 21 and inner ring raceway 31 on which the balls 13 roll.

The first and second continuous portions 43c and 43d, which serve as the electrical charge path, are arranged in the same circumferential phase, minimizing the distance between them. This further enhances the conductivity between the fixed portion 45 and the sliding portion 46.

The relationship between the circumferential length of each second portion 42d and the circumferential length of each first continuous portion 43c can be changed as appropriate. For example, the circumferential length of each second portion 42d may be the same as or smaller than the circumferential length of each first continuous portion 43c. The relationship between the circumferential length of each third portion 42e and the circumferential length of each second continuous portion 43d can also be changed as appropriate. For example, the circumferential length of each third portion 42e may be the same as or smaller than the circumferential length of each second continuous portion 43d.

The second portion 42d and the third portion 42e may be out of phase with each other in the circumferential direction. At least one of the second portion 42d and the third portion 42e can be present at any circumferential phase, which can further enhance the bond between the rubber 42, the sheet 43, and the metal ring 41. Furthermore, if the second portion 42d and the third portion 42e are out of phase with each other in the circumferential direction, during the manufacturing process of the sliding member 15 described below with reference to Figure 9, the second cavity 52b that molds the second portion 42d and the third cavity 52c that molds the third portion 42e are positioned at different phases in the circumferential direction, which makes it less likely that the rubber material G will be insufficiently filled into each of the cavities 52b and 52c, thereby reducing manufacturing defects.

The number of second portions 42d and first continuous portions 43c may differ from the number of third portions 42e and second continuous portions 43d. The multiple second portions 42d may have different circumferential lengths, and the multiple first continuous portions 43c may have different circumferential lengths. The multiple third portions 42e may have different circumferential lengths, and the multiple second continuous portions 43d may have different circumferential lengths.

FIG. 11 is an enlarged photograph showing the radially inner end of the sliding member.
As described above, rubber 42 is present inside most of sheet 43. However, the conductive fibers of sheet 43 (the linear portions in FIG. 5 (e.g., the portions designated by reference symbol F)) are exposed on the surface of the portion of sliding portion 46 of sheet 43 that contacts the inner ring 12 and the surface of the portion of fixed portion 45 of sheet 43 that contacts the outer ring 11. Therefore, sliding member 15 has excellent conductivity (low electrical resistance and/or impedance) between the surface of the portion of sliding portion 46 of sheet 43 that contacts the inner ring 12 and the surface of the portion of fixed portion 45 of sheet 43 that contacts the outer ring 11.

Furthermore, the electrical resistance of the sheet 43 is lower than the electrical resistance of the rubber 42. Therefore, the sliding member 15 of this embodiment has superior conductivity compared to conventional sliding members that have the same shape as the sliding member 15 but do not include the sheet 43, and in which the space where the sheet 43 exists is replaced with rubber 42. The rolling bearing 10 of this embodiment has the sliding member 15 of this embodiment interposed between the outer ring 11 and the inner ring 12, and therefore can suppress the occurrence of electrolytic corrosion in the balls 13, outer ring raceway 21, and inner ring raceway 31 compared to conventional sliding members.

The rubber 42 is a conductive rubber with a higher volume resistivity than the conductive fibers of the sheet 43. The rubber 42 has a higher electrical resistance than the sheet 43. Although only a small portion of the rubber 42, together with the sheet 43, can electrically connect the outer ring 11 and the inner ring 12. The surface of the metal ring 41 is covered with an adhesive coating. The rubber 42 and the sheet 43 are adhered to the metal ring 41 via the adhesive coating. The volume resistivity of the metal ring 41 without the adhesive coating is lower than the volume resistivity of the sheet 43. On the other hand, the electrical resistance of the metal ring 41 through the adhesive coating may be higher than the electrical resistance of the sheet 43. Even if the electrical resistance of the metal ring 41 through the adhesive coating is higher, the sliding member 15 electrically connects the outer ring 11 and the inner ring 12 via the sheet 43.

[Method of manufacturing slide member]
9 and 10 are cross-sectional views showing parts of a molding die for the slide member. Fig. 9 shows a molding die for molding the part of slide member 15 shown in cross section along line A-A in Fig. 2. Fig. 10 shows a molding die for molding the part of slide member 15 shown in cross section along line B-B in Fig. 2.

As shown in Figures 9 and 10, the molding die 50 for the sliding member 15 has an upper die 51 and a lower die 52. The upper die 51 has a cavity 51a. The lower die 52 has a first cavity 52a, a second cavity 52b, and a third cavity 52c.

The sliding member 15 is manufactured by compression molding. An adhesive is applied to the surface of the metal ring 41. The metal ring 41 is immersed in the adhesive.
With the upper mold 51 and the lower mold 52 separated and the mold open, the metal ring 41, the sheet 43, and the unvulcanized rubber material G are placed in these cavities 51a, 52a, 52b, and 52c.

The cavity 51a of the upper mold 51 molds the first portions 42a, 42b, and 42c of the rubber 42 shown in Figures 3 and 4, which are located on the first axial side (the bearing external space K2 side) of the sheet 43. The first cavity 52a of the lower mold 52 molds a portion 42a of the first portions 42a, 42b, and 42c. The first cavity 52a of the lower mold 52 is formed in the lower mold 52 so as to correspond to the entire circumference of the sliding member 15.

As shown in FIG. 9, the second cavity 52b of the lower mold 52 molds the second portion 42d of the rubber 42. The second cavities 52b are formed at multiple locations spaced apart circumferentially to correspond to the multiple (four) second portions 42d shown in FIG. 2. The second cavities 52b are connected to the first cavity 52a. As shown in FIG. 10, the second cavities 52b are not provided at positions where the second portions 42d of the rubber 42 are not provided, i.e., positions corresponding to positions between circumferentially adjacent second portions 42d (positions corresponding to the first continuous portions 43c).

As shown in Figure 9, the third cavity 52c of the lower mold molds the third portion 42e of the rubber 42. The third cavities 52c are formed at multiple locations spaced apart circumferentially to correspond to the multiple (four) third portions 42e shown in Figure 2. As shown in Figure 10, these third cavities 52c are not provided at positions where the third portions 42e of the rubber 42 are not provided, i.e., positions corresponding to the spaces between circumferentially adjacent third portions 42e (positions corresponding to the second continuous portions 43d).

The sliding member 15 is manufactured by placing the metal ring 41, sheet 43, and unvulcanized rubber material G in cavities 51a, 52a, 52b, and 52c, closing the upper and lower dies 51, and applying pressure and heat. The pressurized unvulcanized rubber material G flows within the mold. The unvulcanized rubber material G fills cavity 51a of the upper die 51 and the first to third cavities 52a to 52c of the lower die 52. The unvulcanized rubber material G also fills the voids in the sheet 43.

When the rubber material G is filled into the first cavity 52a, the sheet 43 deforms to conform to the inner surface of the first cavity 52a. When the rubber material G is filled into the second cavity 52b, the sheet 43 is not flexible enough or extensible enough to penetrate into the second cavity 52b, so the rubber material G breaks through the sheet 43 and fills the second cavity 52b. This forms the aforementioned hole 43a (see Figure 5) in the sheet 43. Similarly, when the rubber material G is filled into the third cavity 52c, the sheet 43 is not flexible enough or extensible enough to penetrate into the third cavity 52c, so the rubber material G breaks through the sheet 43 and fills the third cavity 52c. This forms the aforementioned hole 43b (see Figure 6) in the sheet 43.

Unvulcanized rubber material G is impregnated into the voids in sheet 43 and filled into each of cavities 51a, 52a-52c, and then heated, causing the adhesive to harden and turning the unvulcanized rubber material G into rubber 42. As the adhesive hardens and the unvulcanized rubber material G turns into vulcanized rubber, the metal ring 41, sheet 43, and rubber 42 become one unit. Unnecessary portions of this unit are removed to form the sliding member 15.

By impregnating the sheet 43 with unvulcanized rubber material G and vulcanizing it in this manner, the rigidity of the sheet 43 is increased and the sheet 43 and rubber 42 become one unit.

In addition, during the manufacturing process of the sliding member 15, in order to make it easier to fill the rubber material G into the second cavity 52b and the third cavity 52c, holes 43a, 43b may be formed in advance in the sheet 43, or cuts or the like that serve as the base for the holes 43a, 43b may be formed.

[Other embodiments]
In the rolling bearing 10 of the above embodiment, the outer ring 11 is a fixed ring and the inner ring 12 is a rotating ring. However, the present invention may also be applicable to a case where the outer ring 11 is a rotating ring and the inner ring 12 is a fixed ring.

In the above embodiment, the sliding member 15 is fixed to the outer ring 11, which is the first member, and is in slidable contact with the inner ring 12, which is the second member. However, in the present invention, the sliding member 15 may be fixed to the inner ring 12, which is the first member, and in slidable contact with the outer ring 11, which is the second member.

In the sliding member 15 of the above embodiment, a synthetic resin was fixed as a binder to the conductive fibers that make up the sheet 43. On the other hand, the sheet of the present invention does not require a synthetic resin as a binder to the conductive fibers that make up the sheet.

The metal ring 41 of the sliding member 15 has an annular portion 41a and a cylindrical portion 41b, but it does not have to have a cylindrical portion 41b. In this case, the first surface and the second surface are formed by a side surface 41a1 on the first axial side of the annular portion 41a and a side surface 41a2 on the second axial side.

The sliding member 15 in the above embodiment was used in a rolling bearing 10. On the other hand, the sliding member 15 of the present invention may also be used in a device in which it is fixed to one of two members that move relative to one another and is in sliding contact with the other member.

The sliding members 15 may be provided at both axial ends of the rolling bearing 10 .
In the above embodiment, the rolling bearing 10 is a deep groove ball bearing. However, in the present invention, the rolling bearing 10 may be an angular contact ball bearing, a roller bearing in which the rolling elements are rollers, or the like.

The above-described embodiments are illustrative in all respects and are not limiting. The scope of the present invention is indicated by the claims, not by the above-described embodiments, and includes all modifications within the scope of equivalents to the configurations described in the claims.

10: Rolling bearing 11: Outer ring 12: Inner ring 13: Rolling element 15: Sliding member 21: Outer ring raceway 31: Inner ring raceway 41: Metal ring 41a: Annular portion 41a1: First surface 41a2: Second surface 41b1: First surface 41b2: Second surface 42: Rubber 42a: First portion 42b: First portion 42c: First portion 42d: Second portion 42e: Third portion 43: Sheet 43a: Hole 43b: Hole 44: Intermediate portion 45: Fixed portion 46: Sliding portion

Claims (3)

It is circular,
A metal ring;
a sheet that is a nonwoven or woven fabric formed of conductive fibers;
rubber,
The sheet is
a fixing portion that is fixed in contact with a first member made of steel on a first side in a radial direction of the metal ring;
a sliding portion that slidably contacts a second member made of steel on a second radial side of the metal ring;
an intermediate portion located between the fixed portion and the sliding portion,
the metal ring has a first surface disposed on a first axial side or on both the first axial side and the first radial side, and a second surface disposed on a second axial side or on both the second axial side and the second radial side;
the intermediate portion is disposed on the first surface;
the fixing portion is disposed on the first side in the radial direction relative to the end portion on the first side in the radial direction of the metal ring,
the sliding portion is disposed on the second radial side of the end portion of the metal ring on the second radial side,
the rubber includes a first portion, a plurality of second portions spaced apart in the circumferential direction, and a plurality of third portions spaced apart in the circumferential direction;
the first portion is disposed on a first axial side of the intermediate portion, the fixed portion, and the sliding portion;
the second portion is disposed on the second surface of the metal ring beyond a first radial end of the metal ring from the first portion;
the third portion is disposed on the second surface of the metal ring beyond a second radial end of the metal ring from the first portion,
the intermediate portion and the fixed portion are continuous between the second portions adjacent in the circumferential direction,
The intermediate portion and the sliding portion are continuous between the third portions adjacent in the circumferential direction. The sliding member according to claim 1, wherein the sheet has holes that pass through the second portion and the third portion, respectively. an inner ring having an inner ring raceway;
an outer ring having an outer ring raceway disposed radially outward of the inner ring raceway;
a plurality of rolling elements rollably disposed between the inner ring raceway and the outer ring raceway;
The sliding member according to claim 1 or 2,
one of the inner ring and the outer ring is the first member,
the other of the inner ring and the outer ring is the second member.