Rolling bearings

Abstract

To provide a rolling bearing capable of simultaneously suppressing outflow of grease and the like from the inside of the bearing, and intrusion of foreign matters from an atmosphere side even when an internal pressure of the bearing is increased during rotation of the rolling bearing.SOLUTION: In a rolling bearing, a plurality of balls disposed between inner and outer rings, are retained by a retainer, and a seal member 6 for sealing a bearing space between the inner ring and the outer ring is disposed on the outer ring. A seal groove 7 is circumferentially formed on the outer peripheral surface of the inner ring, and the seal member 6 is a contact seal in which a lip 15 is in contact with the seal groove 7. An outer groove wall surface 7c of the seal groove 7 is formed into an inclined surface inclined to an outer diameter side as it goes toward an axial outer side, and the seal member 6 is formed into R shape so that a tip end portion 15c of the lip 15 is in contact with the outer groove wall surface 7c of the seal groove 7 in a normal direction. An inclination angle I of the outer groove wall surface 7c to the axial direction is 53-68°.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rolling bearing, and to a technique capable of simultaneously suppressing the outflow of grease and the like from inside the bearing and the intrusion of foreign matter from the atmosphere side. [Background technology]

[0002] In the rolling bearing 50 for a servo motor shown in FIG. 13, for models in which the encoder 52 is located near the motor 51, low dust generation as the rolling bearing 50 is required using a contact seal to prevent malfunction of the encoder 52 due to dust generation from inside the bearing and seal wear powder adhering to the encoder 52.

[0003] In the seal structure of a rolling bearing according to the prior art, as shown in FIG. 14, in order to achieve low torque and high sealing performance, the main lip 53 is brought into contact with the outer groove wall surface of the seal groove 54, and a labyrinth seal is formed between the tip of the sub-lip 55 and the inner groove wall surface of the seal groove 54. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-170313 Summary of the Invention [Problem to be solved by the invention]

[0005] When the inner ring of a rolling bearing rotates at high speed, the internal pressure of the rolling bearing rises, and if the sealing is insufficient, grease will be expelled to the outside along with the air, causing contamination around the rolling bearing. The applicant of the present invention has therefore discovered that by suppressing changes in the surface pressure distribution due to changes in the seal shape and interference that occur when the seal comes into contact, it is possible to suppress the generation of dust such as grease from inside the rolling bearing and the generation of wear powder due to wear of the rubber seal.

[0006] An object of the present invention is to provide a rolling bearing that can simultaneously prevent the outflow of grease and the like from inside the bearing and the intrusion of foreign matter from the atmosphere side, even when the internal pressure of the bearing rises during rotation of the rolling bearing. [Means for solving the problem]

[0007] A rolling bearing of the present invention comprises a plurality of balls interposed between an inner ring and an outer ring held in a cage, a seal member that seals a bearing space between the inner ring and the outer ring is attached to the outer ring, a seal groove is formed in the circumferential direction on the outer peripheral surface of the inner ring, and the seal member is a contact seal in which a lip contacts the seal groove, The outer groove wall surface of the seal groove is formed as an inclined surface that slopes toward the outer diameter as it extends axially outward, and the seal member is formed in an R-shape such that the tip of the lip contacts the outer groove wall surface of the seal groove in the normal direction, and the inclination angle of the outer groove wall surface with respect to the axial direction is 53 to 68°.

[0008] With this configuration, by setting the inclination angle of the outer groove wall surface relative to the axial direction at 53 to 68 degrees and making the tip of the lip rounded, the lip surface pressure distribution is such that the tip of the lip maintains normal contact with the internal bearing pressure generated when the rolling bearing rotates, i.e., normal contact. Therefore, even if the internal bearing pressure increases when the rolling bearing rotates, it is possible to simultaneously suppress the outflow of grease and other materials from inside the bearing and the intrusion of foreign matter from the atmosphere. If the inclination angle of the outer groove wall surface is less than 53°, the seal member is likely to be turned over by the pressure inside the bearing, which is not appropriate.If the inclination angle of the outer groove wall surface is more than 68°, the tip of the lip will hit the inclined surface too hard when pressure inside the bearing is generated, which is not appropriate because it will increase the torque or generate more heat.

[0009] The lip tip may be arc-shaped with a radius of 0.03 to 0.09 mm. In this case, it is possible to more reliably suppress changes in the surface pressure distribution of the lip when the rolling bearing rotates, and it is also possible to prevent undesirable increases in torque and undesirable heat generation in the lip. If the radius of the lip tip is less than 0.03 mm, it is thought that normal contact will not occur if the internal bearing pressure changes while the rolling bearing is rotating, causing a slight shift in the lip contact position.If the radius of the lip tip is more than 0.09 mm, when the internal bearing pressure rises while the rolling bearing is rotating and the lip tip comes into strong contact with the inclined surface, the contact area will increase, causing increased torque or heat generation, which is not appropriate.

[0010] The sealing member may have a core metal and a rubber material, the lip may be made of the rubber material, and the surface roughness of a part or all of the inner surface of the lip located on the inner diameter side of the PCD may be Ra=0.4 to 2.5 μm. In this case, the desired dust generation suppression effect can be obtained and resistance to grease can be kept low. If the arithmetic mean roughness Ra is less than 0.4 μm, the effect of suppressing grease movement and dust generation is small. If the arithmetic mean roughness Ra is more than 2.5 μm, that is, if it is too rough, the resistance to grease will be too great, which will be detrimental to rotation and is therefore not appropriate.

[0011] The seal member may be provided with an air outlet for releasing the internal pressure of the rolling bearing. In this case, by releasing the internal bearing pressure through the air outlet when the rolling bearing is rotating, it is possible to suppress excessive changes in the seal interference and the outflow of grease caused by an increase in the internal bearing pressure.

[0012] A plurality of air outlets may be provided on an outer peripheral portion of at least one of the seal members, and these air outlets may include radial air outlets formed along the radial direction and axial air outlets formed along the axial direction, and the radial air outlets and the axial air outlets may be provided at different circumferential positions. By shifting the circumferential positions (circumferential phases) of the radial air outlets and the axial air outlets in this manner, it is possible to more reliably suppress the outflow of grease.

[0013] The lip of the seal member may be provided with an air outlet for releasing the internal pressure of the rolling bearing. In this case, by releasing the internal bearing pressure through the air outlet when the rolling bearing is rotating, it is possible to suppress excessive changes in the seal interference and the outflow of grease caused by an increase in internal bearing pressure.

[0014] The air outlets provided in the seal member may be on one or both axial sides of the seal member.

[0015] The seal member may have a secondary lip protruding axially inward from the base end, and a labyrinth seal may be formed between the tip end of the secondary lip and the inner groove wall surface of the seal groove. In this case, the lip, which is the contact seal, and the secondary lip can further enhance the effect of preventing the outflow of grease and the like and the effect of preventing the intrusion of foreign matter.

[0016] Two sub-lips may be provided at a radial distance from each other, and a grease reservoir may be provided between the two sub-lips. In this case, the grease stored in the grease reservoir prevents the grease that contributes to lubrication from leaking out and also prevents foreign matter from entering from the atmosphere side.

[0017] The cage may be provided with a grease storage portion on the inner diameter side of the cage that can store grease. In this case, when the bearing is in operation, grease that has accumulated in the stationary space is stored in the grease storage portion by centrifugal force and is then supplied to the raceway surfaces. This makes it possible to extend the grease life compared to a rolling bearing equipped with a cage that does not have a grease storage portion. [Effects of the Invention]

[0018] A rolling bearing of the present invention has a plurality of balls sandwiched between an inner and outer ring held in a cage, a seal member attached to the outer ring that seals the bearing space between the inner and outer rings, a seal groove formed circumferentially in the outer peripheral surface of the inner ring, the seal member being a contact seal with a lip in contact with the seal groove, the outer groove wall surface of the seal groove formed into an inclined surface that slopes outward in the axial direction, the seal member is formed into an R-shape such that the tip of the lip abuts normally on the outer groove wall surface of the seal groove, and the inclination angle of the outer groove wall surface with respect to the axial direction is 53 to 68°. Therefore, even if the internal pressure of the rolling bearing increases when the rolling bearing rotates, it is possible to simultaneously prevent the outflow of grease and the like from inside the bearing and the intrusion of foreign matter from the atmosphere side. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a cross-sectional view of a rolling bearing according to a first embodiment of the present invention. [Figure 2] 3 is an enlarged cross-sectional view of a lip and other components of a seal member of the rolling bearing. FIG. [Figure 3] FIG. [Figure 4A] FIG. 4 is a partially enlarged cross-sectional view of the seal member taken along a radial air outlet. [Figure 4B] FIG. 2 is a partially enlarged cross-sectional view of the seal member taken along an air outlet in the axial direction. [Figure 5A] FIG. 4 is an enlarged cross-sectional view showing a state in which the seal member contacts the seal groove. [Figure 5B] FIG. 10 is a diagram showing the surface pressure distribution when the interference of the seal member is minimum. [Figure 5C] FIG. 10 is a diagram showing the surface pressure distribution when the interference of the seal member is at its maximum. [Figure 6] FIG. 2 is a perspective view of the cage of the rolling bearing. [Figure 7A] FIG. 10 is a cross-sectional view of a rolling bearing according to another embodiment of the present invention, taken along a radial air outlet. [Figure 7B] FIG. 2 is a cross-sectional view of the rolling bearing taken along an air outlet in the axial direction. [Figure 8] 3 is an enlarged cross-sectional view of a lip and other components of a seal member of the rolling bearing. FIG. [Figure 9A] FIG. 4 is an enlarged cross-sectional view showing a state in which the seal member contacts the seal groove. [Figure 9B] FIG. 10 is a diagram showing the surface pressure distribution when the interference of the seal member is minimum. [Figure 9C] FIG. 10 is a diagram showing the surface pressure distribution when the interference of the seal member is at its maximum. [Figure 10] FIG. 10 is an enlarged cross-sectional view of a lip and other parts of a sealing member in a rolling bearing according to still another embodiment of the present invention. [Figure 11] FIG. 10 is a cross-sectional view of a rolling bearing according to still another embodiment of the present invention. [Figure 12] FIG. 10 is a perspective view of a cage of a rolling bearing according to still another embodiment of the present invention. [Figure 13] FIG. 1 is a diagram illustrating a rolling bearing for a servo motor. [Figure 14] FIG. 10 is an enlarged cross-sectional view partially showing a sealing structure of a conventional rolling bearing. [Figure 15A] FIG. 10 is an enlarged cross-sectional view showing a state in which a seal member of a conventional example is in contact with a seal groove. [Figure 15B] FIG. 10 is a diagram showing the surface pressure distribution when the interference of the seal member is minimum. [Figure 15C] FIG. 10 is a diagram showing the surface pressure distribution when the interference of the seal member is at its maximum. DETAILED DESCRIPTION OF THE INVENTION

[0020] [First embodiment] A rolling bearing according to a first embodiment of the present invention will be described with reference to FIGS. <General structure of rolling bearing> As shown in Figure 1, this rolling bearing 1 is a deep groove ball bearing comprising inner and outer rings 2, 3, balls 4, a cage 5, and a seal member 6. A plurality of balls 4 are interposed between raceway surfaces 2a, 3a of the inner and outer rings 2, 3 and are held at regular intervals in the circumferential direction by the cage 5, and a seal member 6 that seals the bearing space between the inner ring 2 and outer ring 3 is attached to the outer ring 3. In this example, seal members 6, 6 are attached to both axial sides of the inner circumferential surface of the outer ring.

[0021] As shown in FIG. 6, the cage 5 in this example is made of synthetic resin and is a two-piece cage consisting of two identically shaped annular bodies 5a, 5a mated together. This cage 5 holds balls 4 in pockets Pt, which have a cylindrical axial shape. Each annular body 5a has multiple semi-cylindrical pocket walls 5c and multiple connecting plates 5b. The two pocket walls 5c, 5c are mated with each other in the axial direction to form pockets Pt. The pockets Pt are evenly spaced around the circumference. The cage 5 has engaging holes Ka and engaging claws Kb that engage with each other on the connecting plates 5b between the pockets Pt. The cage 5 is assembled by engaging the engaging claws Kb with the engaging holes Ka and mating the two identically shaped annular bodies 5a, 5a. The pockets of the cage 5 may also be spherical. Grease is sealed in the bearing space.

[0022] <Seal structure> Each seal member 6 is a contact seal in which a lip 15 contacts a seal groove 7. Seal grooves 7 are formed in the circumferential direction on the outer peripheral surface of the inner ring 2, and seal member fixing grooves 9 are provided on the inner peripheral surface of the outer ring 3 opposite each seal groove 7. As shown in Figures 1 to 3, seal member 6 is formed by molding a rubber material 11 onto a core metal 10, and the outer peripheral edge of this seal member 6 is fitted into and fixed in seal member fixing groove 9 of the outer ring 3. As shown in Figures 3, 4A and 4B, the outer peripheral portion of seal member 6 is provided with an air outlet 12 for releasing the internal pressure of the rolling bearing.

[0023] 4A and 4B, a portion of the outer peripheral portion of seal member 6 is shown as being embedded in seal member fixing groove 9 of outer ring 3, but this portion is an interference and is actually fitted into seal member fixing groove 9 in an elastically deformed state. Also, a portion of lip 15 of seal member 6 is shown as being embedded in seal groove 7 of inner ring 3, but this portion is an interference and is actually in contact with seal groove 7 in an elastically deformed state. The same is true for the seal structures described below (FIGS. 7A, 7B, 10, and 11).

[0024] A plurality of air outlets 12 are provided in the seal member 6. These air outlets 12 include radial air outlets 12a (FIG. 4A) formed along the radial direction and axial air outlets 12b (FIG. 4B) formed along the axial direction. The air outlets 12a and 12b are each formed by a groove provided in the outer peripheral portion of the seal member 6. The radial air outlets 12a and the axial air outlets 12b are provided at different circumferential positions.

[0025] Specifically, as shown in FIGS. 3, 4A, and 4B, two radial air outlets 12a, 12a are provided circumferentially at a phase difference of 180 degrees on the inner surface of the outer peripheral portion of the seal member 6 that faces the inner groove wall surface 9a of the seal member fixing groove 9. The radial air outlets 12a and the inner groove wall surface 9a form a hole. Furthermore, one axial air outlet 12b is provided on the outer peripheral surface of the outer peripheral portion of the seal member 6 that faces the outer peripheral groove wall surface 9c of the seal member fixing groove 9. The axial air outlet 12b and the outer peripheral groove wall surface 9c form a hole. This axial air outlet 12b is provided at a circumferential position that is 90 degrees out of phase with the radial air outlet 12a. These radial air outlets 12a, 12a and the axial air outlet 12b are in communication with each other via the outer peripheral groove wall surface 9c of the seal member fixing groove 9. Therefore, the internal bearing pressure can be released from the two radial air outlets 12a, 12a via the axial air outlet 12b during rotation of the rolling bearing 1. Note that the circumferential positions of the axial and radial air outlets 12a, 12b are not limited to the phases described above.

[0026] As shown in Figures 1 and 2, the seal groove 7 of the inner ring 2 has, in order axially outward, an inner groove wall surface 7a, a groove bottom surface 7b, and an outer groove wall surface 7c. The inner groove wall surface 7a connects to inner ring shoulders provided on both axial sides of the raceway surface 2a and forms an inclined surface that slopes inward toward the inner diameter as it extends axially outward. The groove bottom surface 7b, which smoothly connects to the inner groove wall surface 7a, extends approximately parallel to the axial direction. The outer groove wall surface 7c smoothly connects to the groove bottom surface 7b and forms an inclined surface that slopes outward toward the outer diameter as it extends axially outward. The inclination angle I of the outer groove wall surface 7c with respect to the axial direction is set to be 53 degrees or more and 68 degrees or less.

[0027] If the inclination angle I of the outer groove wall surface 7c is less than 53°, the seal member 6 will be easily turned over by the internal bearing pressure, which is not appropriate. If the inclination angle I of the outer groove wall surface 7c is more than 68°, the tip of the lip 15 will hit the inclined surface too hard when internal bearing pressure is generated, which is not appropriate because it will increase the torque or generate more heat.

[0028] 2, an inner peripheral portion 13 of the seal member 6 that extends radially inward beyond the inner diameter of the core metal 10 is made of the rubber material 11. Nitrile rubber is typically used as the material for the rubber material 11, but other materials such as acrylic rubber, silicone rubber, or fluororubber may also be used depending on the operating temperature.

[0029] The inner peripheral portion 13 of the seal member 6 has a constricted portion 14 whose thickness decreases toward the inner diameter, and a main lip (lip) 15 and a secondary lip 16 connected to the constricted portion 14. The constricted portion 14, main lip 15, and secondary lip 16 are integrally molded. The main lip 15 is connected to the inner diameter end of the constricted portion 14, and the secondary lip 16 protrudes axially inward from the inner surface of the base end 15a of the main lip 15. As shown in FIG. 1, a labyrinth seal Rs is formed between the tip end of the secondary lip 16 and the inner groove wall surface 7a of the seal groove 7.

[0030] As shown in Figure 2, the main lip 15 has a base end 15a that slopes radially inward as it extends axially outward, a lip main body 15b that extends radially inward from the base end 15a, and a tip end 15c that is provided on the outer surface portion of the lip main body 15b at the tip side. The tip end 15c of the main lip 15 is formed in an R-shape that contacts the outer groove wall surface 7c of the seal groove 7 in the normal direction. An outer diameter surface 15ca of the tip end 15c of the main lip 15 slopes radially inward as it extends axially outward and smoothly connects to the R-shape. When the inclination angle I of the outer groove wall surface 7c of the seal groove 7 is 53 degrees or more and 68 degrees or less, the tip end 15c of the main lip 15 has an arc shape with a radius of 0.03 mm or more and 0.09 mm or less.

[0031] If the radius R of the tip 15c of the lip 15 is smaller than 0.03 mm, it is thought that normal contact will not occur if the internal bearing pressure changes while the rolling bearing is rotating, causing a slight shift in the contact position of the lip 15. If the radius R of the tip 15c of the lip 15 is larger than 0.09 mm, when the internal bearing pressure rises while the rolling bearing is rotating and the tip 15c of the lip 15 comes into strong contact with the inclined surface, the contact area will increase, which will result in increased torque or heat generation, making this unsuitable.

[0032] The dimensions of other parts are set as follows: Thickness A of the base end of the main lip, thickness B of the lip body: 80% ± 10% of the core metal thickness t Radial length D of the lip body: 55% ± 10% of the radial length C of the inner circumferential part of the seal member (cross section of the rubber part) Axial dimension E from the inner surface of the lip body to the tip: Less than twice the thickness B of the lip body Radial dimension F from the inner diameter surface of the secondary lip to the inner diameter end of the lip body: 60% ± 10% of the radial length C of the rubber cross section Inclination angle G of the outer diameter surface of the tip relative to the axial direction: 30°±20° Inclination angle H of the base end relative to the lip body: 135°±20°

[0033] As shown in Figure 4A, the surface roughness of the entire seal member 6 (the area indicated by dotted line L1 in Figure 4A)—the inner surface of the primary lip 15, the inner diameter surface, inner surface, and outer diameter surface of the secondary lip 16, the inner surface of the constricted portion 14, and the inner surface of the rubber material 11 connected to the inner surface of the constricted portion—is 0.4 μm or more and 2.5 μm or less in terms of arithmetic mean roughness Ra. If the arithmetic mean roughness Ra is less than 0.4 μm, the effect of suppressing grease migration is reduced, and the effect of suppressing dust generation is also reduced. If the arithmetic mean roughness Ra is greater than 2.5 μm, that is, if the surface is too rough, the resistance to grease becomes too great, which is detrimental to rotation and is therefore not appropriate.

[0034] In this example, the surface roughness is specified not only on the inner surface of the main lip 15, but also on the inner surfaces of the secondary lip 16 and the constricted portion 14, etc. However, it may also be specified that the surface roughness of at least a portion or all of the inner surface of the main lip 15 located on the inner diameter side of the pitch circle diameter (PCD) is 0.4 μm or more and 2.5 μm or less in terms of arithmetic mean roughness Ra.

[0035] <Results of FEM analysis of contact state and surface pressure change of seal member 6> FIG. 5A is an enlarged cross-sectional view showing the state of contact of the seal member 6 with the seal groove 7. FIG. 5B is a diagram showing the surface pressure distribution when the interference of the seal member is minimum, and FIG. 5C is a diagram showing the surface pressure distribution when the interference of the seal member is maximum. The vertical axes of both FIGS. 5B and 5C represent the surface pressure (unit: kgf / mm 2 ) and each horizontal axis indicates the coordinate (unit: mm) in the inclined direction on the outer diameter side of the contact portion, with the position of contact of the lip tip 15c with the seal groove 7c on the inner diameter side being the reference position (zero).

[0036] 5B and 5C, there is little change in the surface pressure of lip 15 between the minimum and maximum interference of seal member 6. In contrast, in the analysis results of conventional seal member 56 shown in Figures 15A, 15B, and 15C, there is a relatively large change in the surface pressure of lip 57 between the minimum (Figure 15B) and maximum (Figure 15C) interference of seal member 56, which is inappropriate because it is concentrated at one point.

[0037] <Action and effect> According to the rolling bearing 1 described above, by setting the inclination angle I of the outer groove wall surface 7c to 53 to 68° and making the tip end 15c of the lip 15 round, the surface pressure distribution of the lip 15 is such that the tip end 15c of the lip 15 is able to maintain normal contact, that is, a state in which the tip end 15c of the lip 15 is in normal contact with the internal bearing pressure generated when the rolling bearing 1 rotates. Therefore, even if the internal bearing pressure increases when the rolling bearing 1 rotates, it is possible to simultaneously prevent the outflow of grease and the like from inside the bearing and the intrusion of foreign matter from the atmosphere side.

[0038] The tip 15c of the lip 15 is arc-shaped with a radius of 0.03 to 0.09 mm. This makes it possible to more reliably suppress changes in the surface pressure distribution of the lip 15 when the rolling bearing 1 rotates, and also to prevent undesirable increases in torque and undesirable heat generation by the lip 15. Since the surface roughness of the inner surface of the main lip 15 is Ra=0.4 to 2.5 μm, the desired dust generation suppression effect can be obtained, and the resistance to grease can be kept low.

[0039] An air outlet 12 for releasing the internal pressure of the rolling bearing 1 is provided on the outer peripheral portion of the seal member 6. Therefore, by releasing the internal bearing pressure through the air outlet 12 when the rolling bearing 1 is rotating, it is possible to suppress grease leakage caused by excessive changes in seal interference and increases in internal bearing pressure. The radial air outlets 12a and the axial air outlets 12b are provided at different circumferential positions. By shifting the circumferential positions of the radial air outlets 12a and the axial air outlets 12b in this way, i.e., by shifting their circumferential phases, it is possible to more reliably suppress grease leakage.

[0040] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as the previously described embodiment unless otherwise specified. The same functions and effects are achieved from the same configuration. It is possible to combine not only the parts specifically described in each embodiment, but also parts of the embodiments together, provided that there is no particular problem with the combination.

[0041] As shown in Figures 7A and 7B, the seal member 6A may have two parallel secondary lips 16a, 16b spaced apart in the radial direction, with a grease reservoir 17 provided between the two secondary lips 16a, 16b. Grease is stored in the grease reservoir 17. One secondary lip 16a protrudes axially inward from the inner surface of the base end 15a of the main lip 15. The other secondary lip 16b protrudes axially inward from the inner surface of the lip main body 15b of the main lip 15. In this example, the lip main body 15b is connected to the inner diameter end of the base end 15a and extends axially outward, thus inclining toward the inner diameter.

[0042] As shown in FIG. 8, the tip 15c of the main lip 15, which comes into contact with the seal groove, is formed so that the axial dimension L2 of this R-shape is 50%±10% of the radial dimension L3. The thickness of part A1 at the base end 15a of the main lip 15 and the length of part B1 of the lip main body, which are related to the surface pressure, are set as follows. A1 part thickness: 80%±10% of core thickness t Length of B1: Radial length of the inner periphery of the seal (cross section of rubber) 50% ± 10% of the thickness of C1

[0043] The dimensions of other parts are set as follows: The thickness of the D1 portion of the secondary lip located on the inner diameter side, the axial length of the E1 portion, and the setting position F1 are set as follows: D1 thickness: 15% ± 5% of the radial length C1 of the rubber cross section Axial length of E1 part: 180% ±10% of core thickness t Setting position F1: 70% ± 5% of the radial length C of the rubber cross section from the inner diameter of the core

[0044] <Results of FEM analysis of contact state and surface pressure change of seal member 6A> FIG. 9A is an enlarged cross-sectional view showing the state of contact of the seal member 6A with the seal groove 7. FIG. 9B is a diagram showing the surface pressure distribution when the interference of the seal member is minimum, and FIG. 9C is a diagram showing the surface pressure distribution when the interference of the seal member is maximum. The vertical axes of FIGS. 9B and 9C represent the surface pressure (unit: kgf / mm 2 ) and each horizontal axis indicates the coordinate (unit: mm) of the inclination direction of the outer diameter side of the contact portion, with the position of contact of the lip tip 15c with the seal groove 7c on the inner diameter side as the reference position (zero).

[0045] 9B and 9C, the change in surface pressure of lip 15 is small when the interference of seal member 6A is at its minimum and maximum. In contrast, the analysis results of conventional seal member 56 shown in Figures 15A, 15B, and 15C show that the change in surface pressure of lip 57 is relatively large when the interference of seal member 56 is at its minimum (Figure 15B) and maximum (Figure 15C), and this is not appropriate because it is concentrated at one point.

[0046] With this configuration, the grease stored in the grease reservoir 17 prevents the grease that contributes to lubrication from leaking out and also prevents foreign matter from entering from the atmosphere side. Other effects are similar to those of the previous embodiment. Furthermore, the main lip 15 and the two sub-lips 16a, 16b, which are contact seals, further enhance the effect of preventing grease from leaking out and the effect of preventing foreign matter from entering.

[0047] As shown in Figure 10, the main lip 15 may be provided with an air outlet 18 for releasing the internal pressure of the rolling bearing. For example, a plurality of radial air outlets 18 are provided at an evenly spaced interval around the circumference at the tip end 15c of the main lip 15. Each air outlet 18 is formed by a groove. A hole is formed by the air outlet 18 and the outer groove wall surface 7c facing the air outlet 18. Note that the number of radial air outlets 18 at the tip end 15c of the main lip 15 may be one. Alternatively, a plurality of radial air outlets 18 may be provided at unevenly spaced intervals around the circumference. According to the configuration of FIG. 10, by releasing the internal bearing pressure through the air outlet 18 when the rolling bearing is rotating, it is possible to suppress excessive changes in the seal interference and the outflow of grease caused by an increase in the internal bearing pressure.

[0048] As shown in Figure 11, the seal member 6 may be attached to only one axial side of the inner peripheral surface of the outer ring. In this case, an excessive increase in bearing internal pressure during rotation of the rolling bearing can be prevented, and the number of parts can be reduced, resulting in cost savings. Note that a seal groove and a seal member fixing groove may be provided in either or both of the inner and outer rings 2, 3.

[0049] As shown in FIG. 12, a resin wave-shaped cage may be provided with a grease accommodating portion 19 capable of accommodating grease on the inner diameter side of the cage. This cage 5A has the grease accommodating portion 19, which is a cutout portion, provided on the inner diameter surface of the pocket wall portion 5c. The grease accommodating portion 19 has a curved shape, a concave curve, formed by cutting out a portion of the inner diameter surface of the pocket wall portion 5c. This grease accommodating portion 19 is formed during the injection molding of the annular body 5a, but can also be formed by additional processing after injection molding. In a rolling bearing having a cage 5A with such a grease accommodating portion 19, grease accumulated in the stationary space is accommodated in the grease accommodating portion 19 by centrifugal force during bearing operation and is then supplied to the raceway surfaces. This allows for a longer grease life than a rolling bearing having a cage without a grease accommodating portion.

[0050] In each embodiment, a resin wave-shaped cage is used as the cage, but a general so-called steel plate wave-shaped cage may also be used. The cage has pockets for holding the balls inside at multiple locations around the circumference of the annular body, and may be a so-called crown-type cage with one axial side of the pocket open.

[0051] Although the embodiments of the present invention have been described above, the disclosed embodiments are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0052] 1... rolling bearing, 2... inner ring, 3... outer ring, 4... ball, 5, 5A... cage, 6, 6A... seal member, 7... seal groove, 7c... outer groove wall surface, 12... air outlet, 12a... radial air outlet, 12b... axial air outlet, 15... lip, 15c... tip portion, 16a, 16b... secondary lip, 17... grease reservoir, 18... air outlet, 19... grease storage portion

Claims

1. A rolling bearing comprising: a plurality of balls interposed between an inner ring and an outer ring held in a cage; a seal member that seals a bearing space between the inner ring and the outer ring is attached to the outer ring; a seal groove is formed in the circumferential direction on the outer peripheral surface of the inner ring; and the seal member is a contact seal in which a lip contacts the seal groove, an outer groove wall surface of the seal groove is formed as an inclined surface that inclines toward the outer diameter side as it goes outward in the axial direction, an inner peripheral portion of the seal member has a constricted portion whose thickness decreases toward the inner diameter side, and the lip is connected to the inner diameter side end of the constricted portion, the lip has a base end that inclines toward the inner diameter side as it goes outward in the axial direction, a lip main body portion that extends in the inner diameter direction from this base end, and a tip end portion provided on an outer surface portion on the tip side of the lip main body, the tip end portion of the lip is formed in an R-shape that abuts the outer groove wall surface of the seal groove in a direction normal to it, and the inclination angle of the outer groove wall surface with respect to the axial direction is 53 to 68 degrees.

2. 2. The rolling bearing according to claim 1, wherein the lip has a tip end that is arc-shaped with a radius of 0.03 to 0.09 mm.

3. 3. A rolling bearing according to claim 1 or claim 2, wherein the sealing member has a core metal and a rubber material, the lip is made of the rubber material, and the surface roughness of a part or all of the inner surface of the lip that is located on the inner diameter side of the PCD is Ra = 0.4 to 2.5 μm.

4. 4. A rolling bearing according to claim 1, wherein the seal member is provided with an air outlet for releasing internal pressure of the rolling bearing.

5. 5. A rolling bearing according to claim 4, wherein a plurality of the air outlets are provided on an outer peripheral portion of at least one of the seal members, the air outlets including radial air outlets formed along the radial direction and axial air outlets formed along the axial direction, and the radial air outlets and the axial air outlets are provided at different circumferential positions.

6. 6. A rolling bearing according to claim 1, wherein the lip of the seal member is provided with an air outlet for releasing internal pressure of the rolling bearing.

7. 7. The rolling bearing according to claim 4, wherein the air outlets provided in the seal members are located on one or both axial sides of the seal members.

8. 8. A rolling bearing according to claim 1, wherein the seal member has a secondary lip that protrudes axially inward from a base end, and a labyrinth seal is formed between a tip end of the secondary lip and an inner groove wall surface of the seal groove.

9. 9. The rolling bearing according to claim 1, wherein the cage is provided with a grease receiving portion capable of receiving grease on an inner diameter side of the cage.

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