JP7591958B2 - Sealed bearings - Google Patents

Description

This invention relates to a sealed bearing that includes a rolling bearing and a sealing member.

Sealing materials are used to prevent early damage to rolling bearings. For example, the transmissions installed in vehicles such as automobiles and various construction machines contain foreign matter such as gear wear powder, so sealing materials are used to prevent the wear powder and other foreign matter from entering the inside of the bearing.

Generally, the seal member has a seal lip formed in an annular shape from an elastic material such as a rubber-like material. The mating parts, such as raceways and slingers, which rotate circumferentially relative to the seal member as the bearing rotates, are formed with seal sliding surfaces that come into sliding contact with the seal lip.

In typical seal materials, the seal lip and seal sliding surface are in sliding contact all around, and microscopically, there is a solid contact area. The drag resistance (seal torque) of the seal lip leads to an increase in bearing torque. In addition, this sliding contact is one of the causes of temperature rise in rolling bearings. In addition, because the inside of the bearing is sealed off from the outside by the seal material, the pressure difference between the inside and outside of the bearing can cause an adhesion effect in which the seal lip is pressed against the seal sliding surface, increasing the seal torque. For these reasons, typical seal materials have limitations on high-speed operation of bearings.

It is possible to eliminate the sealing torque by forming a labyrinth seal by positioning the sealing lip of the sealing member so that it does not come into contact with the mating part, but it is difficult to control the various errors in the size of the gap between the sealing member and the mating part to prevent the intrusion of foreign matter of a specified particle size.

In response to this, a sealed bearing has been proposed in which the seal lip has multiple protrusions arranged in the circumferential direction, and gaps are created between adjacent protrusions in the circumferential direction that communicate with the inside and outside of the bearing, and a film of lubricating oil is drawn into the gaps between the protrusions and the seal sliding surface as the bearing rotates, creating a fluid lubrication state between the seal lip and the seal sliding surface (Patent Document 1).

The sealed bearing of Patent Document 1 allows lubricating oil to flow between the internal space and the outside of the rolling bearing through a gap that can prevent the intrusion of foreign matter of a specified particle size, making the lubricating oil abundant on the seal sliding surface, and the wedge effect created when the lubricating oil is dragged between the protrusions and the seal sliding surface as the bearing rotates forms a thick oil film that completely separates each protrusion from the seal sliding surface, creating a fluid lubrication state between the seal lip and the seal sliding surface. Therefore, the sealed bearing of Patent Document 1 can significantly reduce seal torque while preventing the intrusion of foreign matter of a specified particle size and allowing the bearing to operate at high speeds.

International Publication No. 2016/143786

In the sealed bearing of Patent Document 1, the lubricating oil used to lubricate the seal lip and the seal sliding surface is machine oil supplied from the outside by splashing or using an oil bath, etc., or base oil seeped out from the grease sealed in the internal space.

In the case of a grease lubrication method that uses only the base oil of the grease as a lubricant, the base oil seeping out of the grease lubricates the gap between the seal lip and the seal sliding surface. Increasing the amount of grease filled makes it easier for the base oil seeping out of the grease to be supplied to the protrusions and seal sliding surfaces, but on the other hand, the agitation resistance of the grease increases. In operating conditions where the bearing rotation speed is high, the amount of grease filled should be small in order to suppress heat generation due to agitation, and is set to 1/3 or less of the volume of the internal space, and in some cases 1/6 or less. In such cases, the grease may not be present stably near the seal lip and seal sliding surface, and therefore the base oil cannot be stably supplied to the protrusions and seal sliding surfaces as a lubricant, and there is a concern that there will be a shortage of base oil to lubricate the sliding parts of each protrusion and seal sliding surface.

On the other hand, when using an oil lubrication method such as splashing, it can take time for the external machine oil to be supplied to the sealed bearing as lubricant. For this reason, grease is sometimes sealed into the internal space of the sealed bearing as an initial lubricant, but even in this case, the same concerns as with grease lubrication arise.

In view of the above background, the problem that this invention aims to solve is to prevent a shortage of oil between the protrusions and the seal sliding surface of a sealed bearing in which the seal sliding surface and the seal lip of the seal member can be fluid-lubricated by the multiple protrusions of the seal lip, even when there is no external oil supply.

In order to achieve the above object, the present invention provides a sealed bearing comprising a seal member that seals the internal space of a rolling bearing from the outside and a seal sliding surface that slides circumferentially against the seal member, the seal member having a seal lip formed in an annular shape, the seal lip having a number of protrusions arranged in a circumferential direction, the protrusions being formed in such a manner that gaps are generated between the protrusions adjacent to each other in the circumferential direction, and the seal lip and the seal sliding surface can be brought into a fluid lubricated state by an oil film of lubricating oil that is drawn between the protrusions and the seal sliding surface from the gaps as the bearing rotates. The seal lip has a grease reservoir formed in a concave shape to hold grease, and the grease reservoir is formed in at least one of the areas between the protrusions adjacent to each other in the circumferential direction and on the protrusions.

According to the above configuration, grease is retained in grease reservoirs on the protrusions of the seal lip near the sliding portion between the protrusions and the seal sliding surface, and base oil seeps out from the grease and is supplied to the protrusions and the seal sliding surface. This prevents a shortage of oil between the protrusions and the seal sliding surface even in the absence of external oil supply.

The grease reservoir may be located between the circumferentially adjacent protrusions. When forming a grease reservoir on a protrusion, it is difficult to form a long, large-capacity grease reservoir on the protrusion in order to prevent the edge of the grease reservoir from adversely affecting oil film formation. In contrast, if the grease reservoir is formed between circumferentially adjacent protrusions, it is easy to form a relatively long grease reservoir and increase its capacity, and the base oil that seeps out from the grease held in the grease reservoir can be dragged between the protrusion and the seal sliding surface as the bearing rotates, contributing to lubrication.

It is preferable that the grease reservoir is continuous with the protrusions. In this way, the base oil is supplied directly to the protrusions from the grease held in the grease reservoir between the protrusions, so that oil shortages can be prevented more effectively.

The grease reservoir is preferably positioned at the same position as the protrusion and the sliding portion of the seal sliding surface in a direction perpendicular to and along the seal sliding surface. In this way, the base oil that seeps out from the grease held in the grease reservoir is quickly drawn into the gap between the protrusion and the seal sliding surface when the bearing rotates, making it possible to more effectively prevent oil shortages.

The sealed bearing of this invention is suitable for use in supporting any one of the rotating parts of a vehicle transmission, differential, propeller shaft, turbocharger, machine tool, wind power generator, and wheel bearing.

By adopting the above configuration, this invention can prevent oil shortages when lubricating the area between the seal sliding surface and the seal lip of the seal member using grease in a sealed bearing in which multiple protrusions on the seal lip can create a fluid lubrication state between the seal sliding surface and the seal lip of the seal member.

FIG. 1 is a cross-sectional view showing a sealed bearing according to a first embodiment of the present invention. An enlarged view of the seal lip protrusion in FIG. 1 FIG. 2 is a perspective view showing the vicinity of a protrusion of a seal lip according to the first embodiment; FIG. 4 is a partially enlarged cross-sectional view of a sealed bearing according to a second embodiment of the present invention taken along the line IV-IV in FIG. FIG. 11 is a perspective view showing the vicinity of a protrusion of a seal lip according to a second embodiment of the present invention; FIG. 13 is a perspective view showing the vicinity of a protrusion of a seal lip according to a third embodiment of the present invention; FIG. 13 is a perspective view showing the vicinity of a protrusion of a seal lip according to a fourth embodiment of the present invention;

As an example of this invention, a sealed bearing according to the first embodiment will be described with reference to the attached drawings, FIGS. 1 to 6.

The sealed bearing shown in Figure 1 comprises a rolling bearing 1 and two seal members 2 arranged on either side of the rolling bearing 1.

The rolling bearing 1 is composed of an inner ring 3, an outer ring 4, a predetermined number of rolling elements 5 interposed between the inner ring 3 and the outer ring 4, and a cage 6 that holds the predetermined number of rolling elements 5. The seal member 2 seals the internal space 7 of the rolling bearing 1 from the outside. The purpose of this sealing is to prevent premature damage to the rolling bearing 1 by preventing external foreign matter from entering the internal space 7 between the inner and outer rings 3 and 4 around the sealed bearing, and is not to seal the internal space 7 liquid-tight.

The inner ring 3 and outer ring 4 have raceway surfaces that correspond to the rolling elements 5. The inner ring 3 is attached to the rotating shaft S and rotates integrally with the rotating shaft S. The outer ring 4 is attached to a member that bears the load from the rotating shaft, such as a housing or gear. The rolling elements 5 revolve while being interposed between the inner ring 3 and outer ring 4.

Balls are used as the rolling elements 5. This sealed bearing is a deep groove ball bearing.

The lubrication method for the sealed bearing may be either an oil lubrication method using lubricating oil supplied from the outside (not shown, same below) or a grease lubrication method using only grease sealed in the internal space 7 (not shown, same below). When using oil lubrication, examples include a splash method in which lubricating oil is sprayed onto the sealed bearing, and an oil bath method in which the lower part of the sealed bearing is immersed in an oil bath. When using oil lubrication, an appropriate amount of grease may be sealed in the internal space 7 as an initial lubricant.

The rotating shaft S is provided as a rotating part in, for example, any one of a vehicle transmission, a differential, a constant velocity joint, a propeller shaft, a turbocharger, a machine tool, a wind power generator, and a wheel bearing.

In the following, the direction along the bearing center axis of the sealed bearing (not shown, same below) is referred to as the "axial direction". The direction perpendicular to the axial direction is referred to as the "radial direction". The direction along the circumference around the bearing center axis is referred to as the "circumferential direction". In Figure 1, the bearing center axis is the center axis of the inner ring 3, which serves as the rotating ring, and corresponds to the left-right direction in the figure.

A seal groove 8 that holds the seal member 2 is formed at the end of the inner circumference of the outer ring 4. The seal member 2 is attached to the outer ring 4 by pressing its outer periphery into the seal groove 8.

The exterior surrounding this sealed bearing contains foreign matter, such as wear powder from gears and clutches, and tiny crushed stones, depending on the device in which the sealed bearing is installed. Such powdery foreign matter can reach the vicinity of the seal member 2 due to the flow of fluid around the seal member 2. The seal member 2 is intended to prevent foreign matter from entering the internal space 7 from the outside.

The seal member 2 has a metal core 9 and a ring-shaped seal lip 10. The core 9 is a pressed part formed into a ring shape that is continuous in the circumferential direction.

The seal lip 10 is formed from an elastic material. Examples of elastic materials include vulcanized rubber materials and elastomers equivalent to rubber materials. Examples of rubber materials include nitrile rubber (NBR), acrylic rubber (ACM), and fluororubber (FKM).

A seal sliding surface 11 that slides circumferentially against the seal lip 10 is formed on the outer periphery of the inner ring 3. The seal sliding surface 11 is a cylindrical surface that is continuous around the entire circumference. The seal lip 10 is a radial lip. Here, the radial lip refers to a seal lip that provides a sealing effect with a seal sliding surface along the axial direction or a seal sliding surface that has an acute angle gradient of 45° or less with respect to the axial direction, and has a radial interference between the seal sliding surface.

The seal lip 10 has a waist portion formed in a radially continuous circular ring shape with a constant width in the axial direction, and a head portion formed in a protruding piece shape that bends outward from the waist portion.

A tightening margin is set between the head of the seal lip 10 and the seal sliding surface 11. When the seal member 2 is attached in the specified position shown in Figure 1, the seal lip 10 is pressed against the seal sliding surface 11 by the tightening margin, causing a rubber-like elastic deformation bent outward as shown in Figure 2, generating tension in the seal lip 10. Installation errors and manufacturing errors of the seal member 2 are absorbed by changes in the degree of flexure of the seal lip 10.

As shown in FIG. 3, the seal lip 10 has multiple protrusions 12 arranged in the circumferential direction. The protrusions 12 extend in a direction perpendicular to the circumferential direction over their entire length. The height of the protrusions 12 is constant over their entire length. The protrusions 12 are arranged at a constant pitch in the circumferential direction. The entire length of the protrusions 12 extends over the entire range that has a radial interference with the seal sliding surface 11. The overall shape of the seal lip 10 is rotationally symmetrical corresponding to the pitch of the protrusions 12.

The projection 12 becomes lower from the center of its circumferential width toward both sides in the circumferential direction. When the projection 12 in the illustrated example is cut in a direction transverse to the circumferential direction, the cross section is semicircular.

When the seal member 2 is attached to the rolling bearing 1 as shown in FIG. 1, the multiple protrusions 12 come into contact with the seal sliding surface 11. As shown in FIG. 2, the protrusions 12 have a height in a direction perpendicular to the seal sliding surface 11 on an imaginary plane including the bearing center axis, and therefore push against the tension of the seal lip 10. As a result, gaps 13 that communicate with the internal space 7 and the outside are generated between the protrusions 12 adjacent to each other in the circumferential direction and between the seal sliding surface 11 and the seal lip 10. The protrusions 12 form a wedge-shaped gap between the seal sliding surface 11, which is larger on the gap 13 side and smaller on the protrusion 12 side.

As shown in Figures 2 and 3, the area between adjacent protrusions 12 in the circumferential direction is a connecting portion 14 that extends between the bases of these protrusions 12. Here, the base of the protrusion 12 refers to the area where the height of the protrusion 12 required to form the above-mentioned wedge-shaped gap is essentially eliminated. The flow passage cross-sectional height of the gap 13 corresponds to the radial distance between the connecting portion 14 and the seal sliding surface 11. The connecting portion 14 is kept out of contact with the seal sliding surface 11. The seal lip 10 slides against the seal sliding surface 11 only on the multiple protrusions 12.

2, the protrusion 12 has an area that is generally along the seal sliding surface 11 on a virtual plane including the bearing center axis. This area exists with a width in the direction along the seal sliding surface 11 (corresponding to the axial direction in the illustrated example). For this reason, the sliding portion between the protrusion 12 and the seal sliding surface 11 accompanying the rotation of the bearing, that is, the wedge effect when the protrusion 12 drags the lubricating oil in the gap 13 between the seal sliding surface 11 in the circumferential direction, promotes the formation of an oil film, and the area where the oil film is interposed between the protrusion 12 and the seal sliding surface 11 occurs with a finite length L of a predetermined length or more in the direction along the seal sliding surface 11 on the aforementioned virtual plane. Such a sliding portion between the protrusion 12 and the seal sliding surface 11 is considered to occur in the shape of a contact ellipse based on Hertz's elastic contact theory, and the major axis of the contact ellipse corresponds to the finite length L.

When the circumferential speed of the relative rotation between the seal lip 10 and the seal sliding surface 11 is less than a certain value, microscopically, a boundary lubrication state or a mixed lubrication state including a solid contact region is formed. When the bearing rotation speed increases and the circumferential speed of the relative rotation between the protrusions 12 and the seal sliding surface 11 exceeds a certain value, the oil film thickness between the protrusions 12 and the seal sliding surface 11 exceeds the composite roughness σ between the protrusions 12 and the seal sliding surface 11 by a large margin, and each protrusion 12 and the seal sliding surface 11 are completely separated by an oil film, resulting in a fluid lubrication state. This allows the seal lip 10 and the seal sliding surface 11 to be completely separated by an oil film, resulting in a fluid lubrication state. When such a fluid lubrication state is formed, the seal torque by the seal member 2 can be reduced to the same level as a non-contact seal, which in turn suppresses the temperature rise of the sealed bearing and prevents the adsorption of the seal lip 10.

Here, if the oil film parameter Λ≧3, the lubrication mode of the sliding part is considered to be in a hydrodynamic lubrication state. The oil film parameter Λ is the ratio of the composite roughness σ to the minimum oil film thickness h in the sliding part, and Λ=h/σ. The minimum oil film thickness h is calculated based on the elastic hydrodynamic lubrication theory. The composite roughness σ=√((Rq ₁ ² +Rq ₂ ² )/2). Rq ₁ is the root-mean-square roughness of the seal sliding surface 11 that constitutes the above-mentioned sliding part. If Rq ₂ is the root-mean-square roughness on the surface of the protrusion 12, the root-mean-square roughness is the value (μm) of the root-mean-square roughness Rq specified in JIS (B0601:2013).

The oil film parameter Λ depends on the composite roughness σ, and the smaller the composite roughness σ, the thicker the oil film can be. In order to make the sliding part between the protrusion 12 and the seal sliding surface 11 in a fluid lubrication state even when the circumferential speed is extremely low as described above, it is preferable to make the composite roughness σ at the sliding part 0.9 μm or less. For example, when the oil lubrication mode was determined using the Johnson chart under the calculation conditions of a composite roughness σ of 0.9 μm, a transmission oil (30 cst, 40°C) lubricant, an ambient temperature of 20°C, and a circumferential speed of 0.2 m/s, the minimum oil film thickness h was 2.8 μm, the oil film parameter Λ was 3 or more, and the lubrication mode was E-I mode. Therefore, if the composite roughness σ of the protrusion 12 and the seal sliding surface 11 is 0.9 μm or less, it is expected that the bearing will be reliably in a fluid lubrication state in the actual use range.

For example, in applications that support rotating parts in a vehicle transmission, transmission oil is generally supplied as lubricant to sealed bearings using an appropriate method such as splashing or oil bath. The lubricant is circulated by an oil pump and filtered by an oil filter installed in the circulation path. If large foreign objects with a particle size exceeding 0.05 mm enter the internal space 7, it is believed that this will have a negative effect on the life of the bearing. Setting the height of the protrusion 12 to 0.07 mm or less will create a gap 13 that such large foreign objects cannot easily pass through.

When the height of the protrusions 12 is 0.07 mm or less, for example, the interval between adjacent protrusions 12 in the circumferential direction can be set to 0.3 mm or more and 2.6 mm or less, the circumferential width of the protrusions 12 can be set to 0.2 mm or more and 1.0 mm or less, and the radius of curvature of the surface of the protrusions 12 can be set to 0.15 mm or more and less than 2.0 mm. In this example, when the oil temperature is 30 to 120°C and the relative circumferential speed of the seal lip 10 and the seal sliding surface 11 is 0.2 m/s or more, it is calculated that the lubrication mode will be either the isoviscosity-rigid body region (R-I mode) or the isoviscosity-elastic body region (E-I mode, soft EHL) in the lubrication region diagram (Johnson chart) based on the viscosity parameter gv and the elastic parameter ge, which are dimensionless numbers determined by Greenwood-Johnson, that is, the above-mentioned fluid lubrication state. If the aforementioned distance is 2.6 mm, a calculated oil film of about 3 μm is formed between the protrusion 12 and the seal sliding surface 11, and if the distance is less than 2.6 mm, the oil film tends to become thicker. If the aforementioned distance is 2.6 mm or less, the bearing rotation torque tends to decrease (i.e., the seal torque tends to decrease). If the aforementioned distance is less than 0.3 mm, it becomes difficult to form the transfer surface for molding the protrusion 12 in the mold by end milling.

For example, in a vehicle transmission, when the vehicle is first started in cold regions, the fluidity of lubricating oil such as transmission oil is low, and it may take time for an abundant supply of lubricating oil to be supplied to the sealed bearing shown in FIG. 1. At this time, there may not be enough lubricating oil between the seal lip 10 and the seal sliding surface 11 to achieve the above-mentioned fluid lubrication state, resulting in a shortage of oil.

When using a grease lubrication method, it is preferable to reduce the amount of grease enclosed in the internal space 7 in order to suppress bearing rotation torque and heat generation, but the grease stirred in the internal space 7 does not necessarily exist stably near the seal lip 10 and the seal sliding surface 11, and is relatively difficult to penetrate into the narrow gap 13 described above (see Figure 2). For this reason, there is a possibility that there will not be enough lubricating oil (base oil) between the seal lip 10 and the seal sliding surface 11 to achieve the aforementioned fluid lubrication state, resulting in an oil shortage.

As shown in Figures 2 and 3, the seal lip 10 has a grease reservoir 15 to prevent the above-mentioned oil shortage. The grease reservoir 15 is formed in a concave shape to hold grease G (shown by a dotted pattern in Figure 2).

The grease reservoir 15 consists of a groove that extends along its entire length in a direction perpendicular to the circumferential direction.

The grease reservoir 15 is positioned at the same position as the protrusion 12 and the sliding portion of the seal sliding surface 11 (the area of finite length L shown in Figure 2) in a direction perpendicular to and along the seal sliding surface 11.

The outer end of the grease reservoir 15 is open toward the outside, and the inner end of the grease reservoir 15 facing the internal space 7 is closed.

The circumferential width of the grease reservoir 15 is smaller than the circumferential width of the connecting portion 14, and occupies the center of the circumferential width of the connecting portion 14.

For example, if the height of the protrusion 12 is 0.04 mm, the depth of the grease reservoir 15 relative to the base of the protrusion 12 is set to 0.2 to 0.3 mm, and the thickness of the elastic material at the bottom of the grease reservoir 15 is ensured to be 1 mm or more. This prevents the connecting portion 14 near the grease reservoir 15 from bending due to the tension of the seal lip 10 and coming into contact with the seal sliding surface 11.

The grease reservoir 15 is disposed only at each connecting portion 14 of the seal lip 10. Note that there may be a connecting portion that does not include a grease reservoir 15, and multiple grease reservoirs may be formed at each connecting portion 14.

Before the seal member 2 is attached, the grease reservoir 15 can be filled with grease G as an initial lubricant. Also, when grease is sealed in the internal space 7 to use the initial lubricant in an oil lubrication system or to use a grease lubrication system, the sealed grease is pushed out into the gap 13 by stirring and enters the grease reservoir 15, which has free space, and the grease G is stored in the grease reservoir 15.

The capacity and arrangement of the grease reservoirs 15 in the seal lip 10 may be appropriately determined so that the above-mentioned fluid lubrication state can be achieved by the base oil seeping out from the grease G held in each grease reservoir 15.

As described above, the sealed bearing shown in Figures 1 to 3 comprises a seal member 2 that seals the internal space 7 of the rolling bearing 1 from the outside, and a seal sliding surface 11 that slides circumferentially against the seal member 2. The seal member 2 has a seal lip 10 formed in an annular shape, and the seal lip 10 has a number of protrusions 12 arranged in the circumferential direction, and the multiple protrusions 12 generate gaps 13 between adjacent protrusions 12 in the circumferential direction, and a film of lubricating oil is drawn into the gaps 13 between the protrusions 12 and the seal sliding surface 11 as the bearing rotates, creating a fluid lubrication state between the seal lip 10 and the seal sliding surface 11. The seal lip 10 has a grease reservoir 15 formed in a concave shape to hold grease G, and the grease reservoir 15 is formed in the connecting portion 14, which is the portion between the circumferentially adjacent protrusions 12. This allows the grease G to be held in the grease reservoir 15 in the connecting portion 14 near the sliding portion between the protrusions 12 and the seal sliding surface 11, and base oil seeps out from the grease G and is supplied to the protrusions 12 and the seal sliding surface 11. This makes it possible to prevent a shortage of oil between the protrusions 12 and the seal sliding surface 11 even when there is no oil supply from the outside.

In addition, in this sealed bearing, the grease reservoir 15 is disposed at the connecting portion 14 between circumferentially adjacent protrusions, so that the edge of the grease reservoir 15 does not adversely affect the formation of an oil film at the sliding portion between the protrusion 12 and the seal sliding surface 11, while the grease reservoir 15 can be formed relatively long to increase its capacity, and the base oil that seeps out from the grease G held in the grease reservoir 15 can be dragged between the protrusion 12 and the seal sliding surface 11 when the bearing rotates, thereby contributing to lubrication.

In addition, this sealed bearing has a grease reservoir 15 that is perpendicular to the seal sliding surface 11 and is positioned at the same position as the protrusion 12 and the sliding part of the seal sliding surface 11 in terms of the position along the seal sliding surface 11. This means that the base oil that seeps out from the grease G held in the grease reservoir 15 of the connecting part 14 is quickly drawn into the gap between the protrusion 12 and the seal sliding surface 11 when the bearing rotates, making it possible to more effectively prevent oil shortages.

The second embodiment of the present invention is shown in Figures 4 and 5. In the following, we will only discuss the differences from the first embodiment.

The seal lip 20 according to the second embodiment has a grease reservoir 22 that spans the entire circumferential width of the connecting portion 21. The grease reservoir 22 is continuous with both of the protrusions 12 that are adjacent to each other in the circumferential direction.

The boundary between the surface of the protrusion 12 that forms the wedge-shaped gap and the inner surface of the grease reservoir 22 is an inflection point. The inner surface of the grease reservoir 22 is shaped in such a way that it is relatively difficult for the grease G to slide up, compared to the surface of the protrusion 12.

The overall length of the grease reservoir 22 is longer than the projection 12 and the connecting portion 21 to increase the capacity for holding grease G and to make it easier for the grease stirred in the internal space to enter.

In the sealed bearing according to the second embodiment, the grease reservoir 22 is continuous with the protrusion 12 in the circumferential direction, so that the base oil is supplied directly to the protrusion 12 from the grease G held in the grease reservoir 22, making it possible to more effectively prevent oil shortages.

Two or more grease reservoirs may be formed in the connecting portion, one of which may be connected to the protrusion on one circumferential side, and another of which may be connected to the protrusion on the other circumferential side.

The third embodiment of the present invention is shown in FIG. 6. The connecting portion 31 of the seal lip 30 shown in the figure has a grease reservoir 32 consisting of a groove portion with both ends closed. Since the outer end of the grease reservoir 32 is closed, the cross-sectional height of the flow passage between the protrusions 12 can be made smaller at the outer end compared to the first embodiment. Therefore, the sealed bearing according to the third embodiment is better at preventing the intrusion of foreign matter than the first embodiment. The grease reservoir 32 may be continuous with the protrusions 12, or may be changed to one that is longer than the protrusions 12.

A fourth embodiment of the present invention is shown in Figure 7. The seal lip 40 shown in the figure has grease reservoirs 43 only on the protrusions 41 among the protrusions 41 and the connecting portions 42.

The height and circumferential width of the protrusion 41 become smaller in the longitudinal direction of the protrusion 41 toward the internal space. The grease reservoir 43 is formed in a groove shape that extends in the longitudinal direction of the protrusion 41 from a position closer to the internal space in the longitudinal direction of the protrusion 41 than the aforementioned sliding portion (see FIG. 2) between the protrusion 41 and the seal sliding surface 11. The grease sealed in the internal space can pass over a relatively low portion of the protrusion 41 and enter the grease reservoir 43.

In the sealed bearing according to the fourth embodiment, grease G is held in a grease reservoir 43 on a protrusion 42 near the sliding portion between the protrusion 41 and the seal sliding surface 11, and base oil seeps out from the grease G and is supplied to the protrusion 41 and the seal sliding surface 11, so that a shortage of oil between the protrusion 41 and the seal sliding surface 11 can be prevented even in the absence of oil supply from outside.

In addition, in the sealed bearing according to the fourth embodiment, the grease reservoirs 43 are formed on the protrusions 41, so the capacity of each grease reservoir 43 is smaller than in the first embodiment, but the cross-sectional height of the flow passage between the protrusions 41 can be made smaller at the outer end.

Although not shown in the drawings, it is also possible to configure a sealed bearing that employs both grease reservoirs 15, 22, and 32 located between the protrusions 12 as shown in Figures 1 to 6, and grease reservoir 43 located on the protrusion 41 as shown in Figure 7.

In addition, in each of the above-described embodiments, the grease reservoir is exemplified as a groove-shaped reservoir with a specific length direction and closed at one or both ends in the length direction, but it is also possible to change it to another recessed shape, such as a round hole.

In addition, in each of the above-described embodiments, the sealing member is illustrated as being made of a core metal and a vulcanized rubber material, but the present invention can also be applied to a sealing member made of a single elastic material.

In addition, while a radial lip is exemplified in each of the above-mentioned embodiments, this invention can also be applied to a seal sliding surface with a gradient of more than 45° relative to the axial direction and a seal lip (axial lip) that provides a sealing effect.

In addition, in each of the above-mentioned embodiments, a radial ball bearing with a rotating inner ring is exemplified, but this invention can also be applied to other suitable types of bearings, such as a rotating outer ring bearing, thrust bearing, or roller bearing. Also, while an example has been shown in which the seal sliding surface is formed on the rotating ring, this invention can also be applied when it is formed on the fixed ring.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. Therefore, the scope of the present invention is indicated by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims.

REFERENCE SIGNS LIST 1 rolling bearing 2 seal member 7 internal space 10, 20, 30, 40 seal lip 11 seal sliding surface 12, 41 protrusion 13 gap 14, 21, 31, 42 connecting portion 15, 22, 32, 43 grease reservoir

Claims (5)

The bearing comprises a seal member that seals an internal space of the rolling bearing against the outside, and a seal sliding surface that slides in a circumferential direction relative to the seal member,
a seal member having a seal lip formed in an annular shape, the seal lip having a plurality of protrusions arranged in a circumferential direction, the plurality of protrusions being formed in such a manner that gaps are generated between adjacent protrusions in the circumferential direction, and a film of lubricating oil is drawn into between the protrusions and the seal sliding surface from the gaps as the bearing rotates, thereby enabling a fluid lubrication state between the seal lip and the seal sliding surface;
The seal lip has a grease reservoir formed in a concave shape to hold grease, and the grease reservoir is formed in at least one of the areas between circumferentially adjacent protrusions and areas on the protrusions. The sealed bearing according to claim 1, wherein the grease reservoir is disposed between adjacent protrusions in the circumferential direction. The sealed bearing according to claim 2, wherein the grease reservoir is continuous with the protrusion. The sealed bearing according to claim 2 or 3, wherein the grease reservoir is disposed at the same position as the protrusion and the sliding portion of the seal sliding surface with respect to a position in a direction perpendicular to the seal sliding surface and along the seal sliding surface. The sealed bearing according to any one of claims 1 to 4 supports one of the rotating parts of a vehicle transmission, differential, constant velocity joint, propeller shaft, turbocharger, machine tool, wind power generator, and wheel bearing.

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