Sealed ball bearing

Abstract

To provide a sealed ball bearing that can achieve superior sealing performance and conductivity by ensuring a contact area of a seal lip part against a seal groove.SOLUTION: In a sealed ball bearing, a seal member comprises a core metal and a seal part secured to the core metal, the seal part being provided with a seal lip part that is in sliding contact with a seal groove of an inner ring, wherein the sliding contact surface of the seal lip part includes a straight part extending in a linear shape and a curved part continuous with the straight part, and a tangent of the curved part at a boundary between the straight part and the curved part constitutes the straight part.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a sealed ball bearing. [Background technology]

[0002] Rotating shafts used in home appliance motors such as air conditioner fans, cooling fans, ventilation fans, vacuum cleaners, and washing machines, industrial motors such as general-purpose motors, servo motors, and stepping motors, in-vehicle motors, and spindles and encoders for machine tools are generally rotatably supported by sealed ball bearings equipped with a sealing member.

[0003] In particular, in bearings for servo motors, leakage of grease and grease-derived substances from the seals can contaminate the encoder and brake, causing problems. To avoid such problems, maintenance must be performed at relatively short intervals, which increases running costs.

[0004] Furthermore, the outer and inner rings and rolling elements are generally made of conductive materials. In contrast, the lubricant (grease, lubricating oil) supplied between the rolling elements and raceway is an insulator, so a potential difference occurs between the inner and outer rings due to static electricity, inverter switching, and other factors. When current flows through the contact area between the raceway (inner or outer ring) and the rolling elements, sparks can form through the thin lubricating oil film, causing localized melting and unevenness of the surface—a phenomenon known as electrolytic corrosion. One way to address this is to create electrical continuity between the inner and outer rings, for example, by using a conductive seal to eliminate the potential difference between the two components and prevent sparks from occurring.

[0005] Patent Document 1 discloses a rolling bearing equipped with a contact seal. In this rolling bearing, the surface of a shoulder on the outer diameter surface of the inner ring is formed flat, and the sealing member has a lip formed in a cylindrical shape that bends from the inner ring side end of the disk portion that covers the space between the inner and outer rings and extends along the shoulder of the inner ring.

[0006] The sealing member as described above is conductive, and by distributing the electricity flowing through the raceway surface and balls (i.e., rolling elements) to the sealing member, damage to the raceway surface and balls can be reduced. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-76229 Summary of the Invention [Problem to be solved by the invention]

[0008] In general seal materials, if the lip tip is made V-shaped, the contact area between the lip and shoulder (seal groove) is small, which allows for increased contact pressure without excessively increasing the lip interference, thereby reducing torque loss. On the other hand, in conductive seals, if the contact area between the lip and shoulder (seal groove) is small, the cross-sectional area through which electricity can pass is reduced, resulting in increased resistance. In other words, the conductivity of the seal material described above may be reduced. Furthermore, if an oil film is stably formed between the lip and seal groove, the resistance increases due to the oil film.

[0009] On the other hand, in the rolling bearing described in Patent Document 1, the lip comes into contact with the flat surface of the shoulder, so it cannot be used with a shape in which a seal groove is formed in the inner ring, and there are problems in that the axial dimension of the rolling bearing becomes large because the seal member is bent to come into contact with the surface of the shoulder. Furthermore, there is also the problem that the lip may be turned up when the seal member is attached during assembly of the rolling bearing.

[0010] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a sealed ball bearing that can exhibit excellent conductivity by ensuring the contact area of ​​the seal lip portion with the seal groove. [Means for solving the problem]

[0011] The above object of the present invention is achieved by the following configuration of a sealed ball bearing. [1] an outer ring having an outer ring raceway groove on an inner diameter surface; an inner ring having an inner ring raceway groove on an outer diameter surface; a plurality of rolling elements disposed between the inner ring raceway groove and the outer ring raceway groove; sealing members that are electrically conductive and are attached to the outer ring on both axial sides of the rolling elements, and extend toward the inner ring; A sealed ball bearing comprising: the seal member includes an annular core and an annular seal portion fixed to the core, the seal portion has a seal lip portion that is in sliding contact with the seal groove of the inner ring, The sliding contact surface of the seal lip portion has a linear portion extending linearly and a curved portion continuing from the linear portion, and a tangent to the curved portion at a boundary between the linear portion and the curved portion forms the linear portion. Sealed ball bearing. [2] an outer ring having an outer ring raceway groove on an inner diameter surface; an inner ring having an inner ring raceway groove on an outer diameter surface; a plurality of rolling elements disposed between the inner ring raceway groove and the outer ring raceway groove; sealing members that are electrically conductive and are attached to the outer ring on both axial sides of the rolling elements, and extend toward the inner ring; A sealed ball bearing comprising: the seal member includes an annular core and an annular seal portion fixed to the core, the seal portion has a seal lip portion that is in sliding contact with the seal groove of the inner ring, The sliding surface of the seal lip portion has a first curved portion extending in a curved shape and a second curved portion that is continuous with the first curved portion and has a curvature different from that of the first curved portion, and is arranged so that tangents to the first curved portion and the second curved portion coincide with each other at a boundary between the first curved portion and the second curved portion. Sealed ball bearing. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a sealed ball bearing that can exhibit excellent electrical conductivity by ensuring the contact area of ​​the seal lip portion with the seal groove. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of a sealed ball bearing according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of a main part near the seal lip portion in FIG. [Figure 3] FIG. 3 is an enlarged schematic view showing the sliding contact surface of the seal lip portion shown in FIG. [Figure 4] FIG. 4 is an enlarged schematic view showing a modified example of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of a sealed ball bearing 10 according to the present invention will be described with reference to the drawings.

[0015] Here, "axial direction" refers to the axial direction of sealed ball bearing 10, "axially inward" refers to the direction from seal member 15 toward ball 13, and "axially outward" refers to the direction from ball 13 toward seal member 15. In the ball bearing of this embodiment, the outer ring is attached to a fixed member such as a housing, and the inner ring is attached to a rotating shaft for use with inner ring rotation.

[0016] Sealed ball bearing 10, which is a deep groove ball bearing, includes outer ring 11 having outer ring raceway groove 11a on its inner diameter surface, inner ring 12 having inner ring raceway groove 12a on its outer diameter surface, a plurality of balls 13 as rolling elements arranged to roll freely between outer ring raceway groove 11a and inner ring raceway groove 12a, resin cage 14 that holds balls 13 at predetermined intervals in the circumferential direction, and a pair of seal members 15 fixed to both axial sides of the inner diameter surface of outer ring 11 to seal the inside of the bearing. Grease is pre-filled inside the bearing.

[0017] In this embodiment, the outer ring raceway groove 11a and the inner ring raceway groove 12a are formed in the outer ring 11 and the inner ring 12 so that the axial center position of the balls 13 is the axial center position of the sealed ball bearing 10.

[0018] The outer ring 11 has seal mounting grooves 11b on both sides of the outer ring raceway groove 11a, and the inner ring 12 has seal grooves 12b on both sides of the inner ring raceway groove 12a.

[0019] The seal member 15 has a core 16 formed in a substantially circular ring shape from a metal plate such as a steel plate, and a seal portion 17 made of an elastic material such as rubber and fixed to the core 16. The core 16 is made up of a main body portion 16a arranged along a plane perpendicular to the axis of the sealed ball bearing 10, and a bent portion 16b connected to the radially outer end of the main body portion 16a and bent axially inward.

[0020] Each seal portion 17 has an outer portion 17a that adheres closely to and covers the axial outer surface (the surface opposite the ball 13) of the main body portion 16a of the core wire 16, an outer edge portion 17b that is connected to the outer portion 17a and is formed to wrap around the outer peripheral edge of the bent portion 16b of the core wire 16, and a seal lip portion 17c that is connected to the outer portion 17a and extends radially inward from the core wire 16.

[0021] Outer portion 17a, together with main body portion 16a, is disposed along a plane perpendicular to the axis of sealed ball bearing 10. In contrast, seal lip portion 17c is inclined axially inward with respect to the plane perpendicular to the axis of sealed ball bearing 10, and extends in a cantilever shape in the cross section of FIG.

[0022] Each seal portion 17 is attached to the outer ring 11 by engaging the outer edge portion 17b with the seal attachment groove 11b of the outer ring 11. At this time, each core metal 16 is arranged on the ball 13 side.

[0023] The seal lip portion 17c is in sliding contact with the inner side surface 12d of the seal groove 12b, and as shown in Fig. 3, a sliding surface 17ca facing inward in the axial direction so as to face the inner side surface 12d has a linear portion 17d that extends substantially linearly and a curved portion 17e that is continuous with the linear portion 17d. The curved portion 17e is located radially inward of the linear portion 17d.

[0024] The straight line portion 17d and the curved line portion 17e are continuous with each other such that a tangent to the curved line portion 17e at a boundary 17f (that is, a so-called joint portion between the straight line portion 17d and the curved line portion 17e) forms the straight line portion 17d.

[0025] In this example, the straight line portion 17d extends in a direction intersecting with the inner side surface 12d, and the curved line portion 17e curves radially inwardly so as to move away from the inner side surface 12d.

[0026] In Fig. 2, the seal groove 12b includes a bottom surface 12c that is a substantially cylindrical surface and an inner side surface 12d that is a tapered surface. The inner side surface 12d is inclined with respect to a plane perpendicular to the axis of the sealed ball bearing 10. More specifically, in the cross section of Fig. 2, the bottom surface 12c extends from the inner side surface 12d at a gentle incline axially outward, tapering so that its diameter increases as it extends axially outward from the inner side surface 12d. Furthermore, the inner side surface 12d extends from the bottom surface 12c at a somewhat steep incline axially inward, tapering so that its diameter increases as it extends axially inward from the bottom surface 12c.

[0027] The seal lip portion 17c is elastically deformed when its sliding surface 17ca slides against the inner side surface 12d, and both the straight portion 17d including the boundary portion 17f and the curved portion 17e come into contact with the inner side surface 12d, thereby functioning as a contact seal. Note that Fig. 3 shows the seal lip portion 17c in a state where it is not elastically deformed.

[0028] As explained above, in the sealed ball bearing 10 of this embodiment, the tangent to the curved portion 17e at the boundary 17f between the straight portion 17d and the curved portion 17e forms the straight portion 17d, so that both the straight portion 17d and the curved portion 17e come into contact with the inner side surface 12d, thereby increasing the contact area of ​​the seal lip portion 17c with the inner side surface 12d. In addition, an appropriate contact surface pressure distribution of the seal lip portion 17c is also ensured. This allows the sealed ball bearing 10 of this embodiment to exhibit excellent sealing properties and electrical conductivity.

[0029] Furthermore, according to the sealed ball bearing 10 of this embodiment, by increasing the contact area of ​​the seal lip portion 17c with the inner side surface 12d, it becomes difficult for an oil film to be uniformly formed between the seal lip portion 17c and the inner side surface 12d, and an increase in resistance due to the oil film can be prevented.

[0030] The present invention is not limited to the above-described embodiments, and can be appropriately modified, improved, etc. Furthermore, the material, shape, size, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention.

[0031] As a modification of the above embodiment, for example, seal lip portion 17c is in sliding contact with inner side surface 12d of seal groove 12b, and as shown in Fig. 4, sliding surface 17ca facing axially inward to face inner side surface 12d has a first curved portion 117d that is substantially curved, and a second curved portion 117e that is continuous with first curved portion 117d and has a curvature different from that of first curved portion 117d. Second curved portion 117e is located radially inward of first curved portion 117d.

[0032] The first curved portion 117d and the second curved portion 117e are arranged so that the tangents of the first curved portion 117d and the second curved portion 117e coincide with each other at a boundary portion 117f (that is, a so-called joint portion between the straight portion 17d and the curved portion 17e).

[0033] In this example, the first curved portion 117d is gently curved in a direction intersecting with the inner side surface 12d, and the second curved portion 117e is curved radially inward so as to move away from the inner side surface 12d. The second curved portion 117e has a larger curvature than the first curved portion 117d.

[0034] The seal lip portion 17c is elastically deformed when in contact (sliding contact) with the inner side surface 12d by its sliding contact surface 17ca, and both the first curved portion 117d and the second curved portion 117e including the boundary portion 117f come into contact with the inner side surface 12d, thereby functioning as a contact seal. Note that Fig. 4 shows the seal lip portion 17c in a state where it is not elastically deformed.

[0035] As explained above, in sealed ball bearing 10 of this example, first curved portion 117d and second curved portion 117e are arranged so that their tangents coincide at boundary 117f between them, so that first curved portion 117d and second curved portion 117e both come into contact with inner side surface 12d, thereby increasing the contact area of ​​seal lip portion 17c with inner side surface 12d. This allows sealed ball bearing 10 of this example to also exhibit excellent sealing properties and conductivity.

[0036] Furthermore, in the sealed ball bearing 10 of this example, by increasing the contact area of ​​the seal lip portion 17c with the inner side surface 12d, it becomes difficult for an oil film to be uniformly formed between the seal lip portion 17c and the inner side surface 12d, and an increase in resistance due to the oil film can be prevented.

[0037] Furthermore, in general, when a ball bearing is subjected to a load, the outer ring and inner ring tilt or displace relative to each other, causing a change in the positional relationship between the seal lip portion and seal groove 12b. On the other hand, with sealed ball bearing 10 according to the modified example, by bringing first curved portion 117d and second curved portion 117e into contact with inner side surface 12d (seal groove 12b), seal lip portion 17c can be brought into stable contact with inner side surface 12d even if the positional relationship between seal lip portion 17c and seal groove 12b changes. [Explanation of symbols]

[0038] 10 Sealed ball bearings 11 Outer ring 11a Outer ring raceway groove 11b Seal mounting groove 12 Inner Circle 12a Inner ring raceway groove 12b Seal groove 12d medial side 13 Ball (rolling element) 15 Sealing material 16 Core 17 Seal part 17c Seal lip 17ca Sliding surface 17d Straight section 17e Curved section 17f Boundary 117d 1st curve section 117e 2nd curve section 117f Boundary

Claims

1. an outer ring having an outer ring raceway groove on an inner diameter surface; an inner ring having an inner ring raceway groove on an outer diameter surface; a plurality of rolling elements disposed between the inner ring raceway groove and the outer ring raceway groove; sealing members that are electrically conductive and are attached to the outer ring on both axial sides of the rolling elements, and extend toward the inner ring; A sealed ball bearing comprising: the seal member includes an annular core and an annular seal portion fixed to the core, the seal portion has a seal lip portion that is in sliding contact with the seal groove of the inner ring, The sliding contact surface of the seal lip portion has a linear portion extending linearly and a curved portion continuing from the linear portion, and a tangent to the curved portion at a boundary between the linear portion and the curved portion forms the linear portion. Sealed ball bearing.

2. an outer ring having an outer ring raceway groove on an inner diameter surface; an inner ring having an inner ring raceway groove on an outer diameter surface; a plurality of rolling elements disposed between the inner ring raceway groove and the outer ring raceway groove; sealing members that are electrically conductive and are attached to the outer ring on both axial sides of the rolling elements, and extend toward the inner ring; A sealed ball bearing comprising: the seal member includes an annular core and an annular seal portion fixed to the core, the seal portion has a seal lip portion that is in sliding contact with the seal groove of the inner ring, The sliding surface of the seal lip portion has a first curved portion extending in a curved shape and a second curved portion that is continuous with the first curved portion and has a curvature different from that of the first curved portion, and is arranged so that tangents to the first curved portion and the second curved portion coincide with each other at a boundary between the first curved portion and the second curved portion. Sealed ball bearing.

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