Rolling bearing

Abstract

This rolling bearing comprises an inner ring (2), an outer ring, a plurality of rolling elements interposed between the inner ring (2) and the outer ring, and a seal member (6) sealing a bearing space between the inner ring (2) and the outer ring. The seal member (6) includes a metal core (10) and a contact-type main lip (15) positioned radially inward of the metal core (10). The main lip (15) has a contact portion (15c) that comes into contact with a seal groove (7) of the inner ring (2) with an interference. The seal member (6) is provided with a radial change reducing means (Rcr) for reducing an amount of radial change of the contact portion (15c) to a predetermined value or less within the range of the interference. The radial change reducing means (Rcr) is constructed such that, at the time of maximum interference, a maximum protruding position (Pk) on an axially outer side of a bent portion (Be) is located axially outside a bottom (Ks) of an axially outer portion of a constricted portion (14), and is located at the same axial position as or axially inside an axial position (Tm) of an end surface of the inner ring (2) or the outer ring.

Description

Rolling bearings Related Applications

[0001] This application claims priority to Japanese Patent Application No. 2024-150127 filed on August 30, 2024, and Japanese Patent Application No. 2024-153457 filed on September 5, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a rolling bearing, and to a technique for stabilizing sealing performance.

[0003] 10 shows a rolling bearing 50 for a servo motor, and some models have an encoder 52 located near the motor 51. For such models, 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.

[0004] Prior art includes Patent Documents 1 and 2. Both of these documents propose rolling bearings that can reduce the amount of dust generated from inside the bearing even when the internal pressure of the bearing increases during rotation. Specifically, they specify the relative positions of the core and the secondary lip, the shape of the tip of the contact seal lip that contacts the seal groove, and the inclined surface of the seal groove.

[0005] JP 2022-72083 A JP 2022-102580 A

[0006] The two prior art documents mentioned above are improvement proposals for preventing dust generation from inside the bearing, and there are no problems with the design proposals in terms of dust generation. Both prior art documents have a structure in which the seal contacts the axially outer surface of the inner ring seal groove, which is effective in preventing dust generation from inside the bearing due to an increase in internal pressure.

[0007] Sealing performance is ensured by the contact between the inner ring seal groove and the tip of the seal inner diameter lip (hereinafter referred to as the contact area), and if this contact state is unstable, it can cause dust to be emitted from inside the bearing, base oil to leak, etc. In particular, because this seal contacts the inner ring seal groove with interference, it is important that the position of the contact area does not fluctuate greatly within the range of interference.

[0008] The inserted seal elastically deforms according to the interference, determining the position of the contact area. In the case of the prior art document, the seal shape on the inner diameter side of the core is prone to elastic deformation in the less rigid portion, resulting in a shape that results in a large radial change in the contact area when the interference is changed within the expected interference range. The seal in the prior art document has a shape that affects sealing performance if the inner ring oscillates in the axial direction due to thermal expansion and contraction of the shaft while the bearing is rotating, or if the interference changes during rotation due to changes in the internal pressure of the bearing, etc.

[0009] This seal contacts the outside of the inner ring seal groove and has a constricted portion where the wall thickness narrows from the core to the inner diameter side, and a bent portion that bends from the constricted portion to the tip of the inner diameter lip. This seal is inserted into the bearing with interference. The position of the contact portion of the inserted seal changes depending on the interference. Normally, the portion of the seal that is less rigid from the core to the inner diameter side elastically deforms, and as shown in Figure 11, this elastically deformed portion becomes the center of rotation Pc, and the seal contact portion moves along a rotational path Ty.

[0010] The interference of the seal while the bearing is rotating changes due to the oscillation of the inner ring or changes in pressure inside the bearing. If the radial contact position of the seal contact area changes due to changes in interference, the contact area changes its radial position as it slides along the slope of the inner ring seal groove, making the seal unstable. In a lip structure with line contact like the conventional example, if the radial change Δa of the contact area is large, this can affect the seal ability.

[0011] As shown in Figure 12, the range of motion of the contact portion varies on an approximate circumference Cf that passes through these three contact portions Ps in the contact state when the set interference is maximum / center / minimum. The center of rotation of this approximate circumference Cf differs depending on the shape of the inner diameter and below of the core bar 10. In order for the contact portion Ps to move on the approximate circumference Cf and to minimize radial positional change, it is desirable that the position of the contact portion Ps at the median value of the interference be directly below the center of rotation in the radial direction. In other words, since the contact position varies on an approximate circumference Cf, the amount of radial change is smallest at the position directly below the center of rotation, and the gradient increases as the position moves away from directly below.

[0012] In the conventional design, the center of rotation is near the constricted portion 14, which is located axially closer to the bearing than the contact point Ps. Therefore, to position the contact point on the approximate circumference, which is the lip tip's range of motion, directly below the center of rotation, a large interference is required, which increases the contact force and makes the seal more susceptible to wear. This can also result in increased rotational torque or the seal protruding from the bearing end face.

[0013] An object of the present invention is to provide a rolling bearing that can stabilize sealing performance.

[0014] A rolling bearing in a first configuration of the present invention comprises an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a seal member sealing the bearing space between the inner ring and the outer ring, the seal member including a core and a contact-type lip located radially inward of the core, the lip having a contact portion that comes into contact with the outside of the seal groove of the inner ring with an interference, and the seal member is provided with radial variation reduction means that reduces the radial variation of the contact portion to a predetermined value or less within the range of the interference. The ``predetermined value'' is a value that is arbitrarily determined by design or the like, and is determined by, for example, obtaining an appropriate value through testing and / or simulation.

[0015] With this configuration, the radial change reduction means reduces the radial change of the lip contact area to a specified value or less within the interference range. Therefore, even if the interference changes due to inner ring oscillation or pressure changes inside the bearing while the bearing is rotating, the sealing performance of the inner ring seal groove can be stabilized. This not only reduces the amount of dust generated inside the bearing, but also prevents foreign matter from entering from outside the bearing.

[0016] The sealing member has a constricted portion located radially inward of the inner diameter portion of the core bar and having a thickness that decreases toward the inner diameter side, a bent portion connected to the inner diameter portion of the constricted portion, and the lip connected to the inner diameter portion of the bent portion, and the radial change reduction means may be such that, when the interference is at its maximum, the maximum protruding position Pk on the axial outer side of the bent portion is axially outer than the bottom Ks of the axial outer portion of the constricted portion and is at the same position as or axially inner than the axial position Tm of the end face of the inner or outer ring.

[0017] In this case, the maximum distance of the entire seal member in the axial direction away from the bearing does not change, and the bent portion does not protrude from the bearing end face. By making the seal member this shape, the amount of elastic deformation at the bent portion increases. As a result, the center of rotation of the approximate circumference, which is the movable range of the lip contact portion, moves axially toward the opposite bearing side, making it easier to set the position of the contact portion at the center of interference near directly below the center of rotation. This makes it possible to reduce the radial change of the lip contact portion compared to conventional structures.

[0018] The axial thickness Ta at the bottom of the constricted portion is preferably greater than the radial thickness Tb from the inner diameter portion of the constricted portion to the inner circumferential surface of the bent portion. In this case, the amount of elastic deformation on the inner diameter side of the constricted portion can be increased. As a result, the radial change in the contact area of ​​the lip within the interference range can be further reduced compared to conventional structures.

[0019] The sealing member may be provided on only one axial side of the rolling bearing or on both axial sides. When the sealing member is provided on only one axial side, the number of parts and the number of steps required to process the seal grooves, etc., can be reduced, thereby reducing costs. When the sealing members are provided on both axial sides, it is possible to prevent grease from leaking from inside the bearing and foreign matter from entering from the atmosphere side.

[0020] Patent Documents 1 and 2 do not disclose a method for assembling a seal member into a bearing. The seal member is shaped so that the contact portion of its tip comes into contact with the outer surface of the inner ring seal groove. This means that when assembling the seal member into the bearing, there is a risk of assembly failure, such as the tip not being able to fit completely into the seal groove.

[0021] A rolling bearing according to a second aspect of the present invention comprises a plurality of rolling elements interposed between an inner ring and an outer ring, and a seal member sealing the bearing space between the inner ring and the outer ring, wherein a seal groove is formed circumferentially in the outer peripheral surface of the inner ring, and the seal member is a contact seal attached to the outer ring at its base end and contacting the seal groove at its tip end. The seal member has a main lip at its tip end, which has a radially extending lip body portion and a lip tip portion extending radially inward from the tip of the lip body portion at an inclination axially outward. The radial dimension B of the tip at the axially inner seal back surface of the lip body portion is set larger than the outer diameter dimension A of the end face of the inner ring. The seal member may be provided on both axial sides of the bearing space, or on only one side.

[0022] With this configuration, the radial dimension B of the tip of the seal back surface of the lip main body is set larger than the outer diameter A of the end face of the inner ring (B > A). This makes it easier for the main lip to climb over the end face of the inner ring that forms the inlet of the seal member. As a result, the seal member can be easily assembled to the bearing.

[0023] In the present invention, the axially outer seal surface of the lip main body may be parallel to the radial direction of the bearing or may extend radially outward from the tip at an inclination axially outward. With this configuration, when assembling the seal member to the bearing, the seal surface comes into contact with a jig, which makes it easier for the main lip to bend toward the inside of the bearing. This improves the ease of assembling the seal member to the bearing.

[0024] In the present invention, a radial position P1 of a radial midpoint between the radially inner end and the radially outer end of the axially outer seal surface of the lip main body may be located radially outward of a radial position P2 obtained by adding a thickness dimension C of the lip tip in a natural state to the outer diameter dimension A of the end face of the inner ring. Here, the natural state refers to a state in which the tip does not contact the seal groove, such as a state before the seal member is installed in a bearing. With this configuration, the lip tip of the main lip that has climbed over the end face of the inner ring is less likely to be pinched by a jig that contacts the seal surface. This makes it possible to prevent defects from occurring at the lip tip of the main lip.

[0025] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

[0026] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation, and should not be used to define the scope of the present invention, which is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts.

[0027] 1 is a longitudinal sectional view of a rolling bearing according to a first embodiment of the present invention. FIG. 2 is a perspective view of a cage of the rolling bearing. FIG. 3 is an enlarged sectional view showing a seal member of the rolling bearing. FIG. 4 is an enlarged sectional view of the lip etc. of the seal member. FIG. 5 is a diagram showing the amount of radial change in the contact portion of the lip within the interference range. FIG. 6 is a perspective view of the seal member. FIG. 7 is a longitudinal sectional view of a rolling bearing according to a second embodiment of the present invention. FIG. 8 is a longitudinal sectional view of a rolling bearing according to a third embodiment of the present invention. FIG. 9 is a longitudinal sectional view of a rolling bearing according to a fourth embodiment of the present invention. FIG. 10 is a schematic diagram of a rolling bearing for a servo motor etc. FIG. 11 is a diagram showing the positional relationship between the center of rotation of the seal and the contact portion when the interference is from minimum to maximum. FIG. 12 is a diagram showing change in the seal as the interference changes. FIG. 13 is a sectional view of a rolling bearing according to a fifth embodiment of the present invention. FIG. 14 is an enlarged sectional view of the seal member of the rolling bearing. FIG. 15 is a diagram explaining a process of assembling the seal member to the inner ring of a rolling bearing. FIG. 16 is a diagram explaining a process of assembling the seal member to the inner ring. FIG. 17 is a diagram explaining a process of assembling the seal member to the inner ring. 1 is a view illustrating a process of assembling the seal member to the inner ring; FIG. 2 is a view illustrating a process of assembling the seal member to the inner ring; FIG. 3 is an enlarged view showing a state in which the seal member is pressed by a jig; and FIG. 4 is a view schematically showing a rolling bearing for a servo motor, etc.

[0028] [First embodiment] A rolling bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 6. This rolling bearing is applied to, for example, industrial machinery such as servo motors, vehicles, etc. However, the rolling bearing is not limited to these uses and can be applied to various types of machinery, devices, etc.

[0029] <Schematic Configuration of Rolling Bearing> Fig. 1 is a cross section (longitudinal cross section) of a rolling bearing 1 cut along a plane including the axial direction. The same applies to cross sections of other embodiments. The rolling bearing 1 is a deep groove ball bearing comprising an inner ring 2, an outer ring 3, balls (rolling elements) 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. The seal member 6 is attached to the outer ring 3 and closes the bearing space, which is the annular space between the inner ring 2 and 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. Grease, a lubricant, is sealed in the bearing space between the inner and outer rings 2, 3.

[0030] In this specification, a rolling bearing may be simply referred to as a "bearing." In the following description, the direction of the bearing center axis AX, which is the bearing shaft center, is referred to as the "axial direction," the direction perpendicular to the bearing center axis AX is referred to as the "radial direction," and the direction around the bearing center axis AX is referred to as the "circumferential direction." In addition, the side facing the bearing center axis AX is referred to as the "inner diameter side," and the side away from the bearing center axis AX is referred to as the "outer diameter side."

[0031] <Cage> As shown in FIG. 2, 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 (FIG. 1) in pockets Pt, which have a cylindrical axial pocket 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 have a spherical shape.

[0032] <Regarding seal structure, etc.> As shown in Fig. 1 , each seal member 6 is a contact seal in which a main lip 15, which is the primary lip, contacts a seal groove 7 in the inner ring 2. Seal grooves 7 are formed in the circumferential direction on the outer peripheral surface of the inner ring 2, and seal grooves 9 for fixing the seal member are provided on the inner peripheral surface of the outer ring 3 opposite each seal groove 7. As shown in Fig. 3 , the seal member 6 is formed by molding a rubber material 11 onto a core metal 10, and an outer peripheral portion 8 of the seal member 6 is fitted into and fixed in the seal groove 9 of the outer ring 3. The main lip 15 is located radially inward of the core metal 10.

[0033] <Outer ring seal groove> The seal groove 9 of the outer ring 3 has, in order axially outward, an inner surface 9a, a groove bottom surface 9c, and an outer surface 9b. The inner surface 9a connects to outer ring shoulders provided on both axial sides of the raceway surface 3a (Fig. 1).

[0034] The groove bottom surface 9c, which smoothly connects to the inner surface 9a, is recessed radially outward. The outer surface 9b is smoothly connected to the groove bottom surface 9c and forms an inclined surface that slopes inward in the axially outward direction. In Figures 1 and 3, a portion of the outer peripheral portion of the seal member 6 is shown as being embedded in the seal groove 9 of the outer ring 3, but this portion is an interference, and in reality, the seal member 6 is fitted into the seal groove 9 in an elastically deformed state. The same applies to the seal structures in Figures 7 to 9 and 13, which will be described later.

[0035] As shown in Figure 4, an inner peripheral portion 13 of the seal member 6 is provided with a main lip (contact-type lip) 15 that contacts the outer surface 7c of the seal groove 7 of the inner ring 2. The main lip 15 has a contact portion 15c that contacts the seal groove 7 of the inner ring 2 in an elastically deformed state with interference. In Figures 1 and 3, a portion of the main lip 15 of the seal member 6 is shown as being embedded in the seal groove 7 of the inner ring 3, but this portion is interference and actually contacts the seal groove 7 in an elastically deformed state. The same applies to the seal structures in Figures 7 to 9 and 13, which will be described later.

[0036] <Air holes> As shown in Figure 6, a plurality of air holes 12 are provided in the outer peripheral portion 8 (Figure 3) of the seal member 6 to release the internal pressure of the rolling bearing. These air holes 12 include radial air holes 12a, 12a formed along the radial direction and axial air holes 12b formed along the axial direction. The air holes 12a, 12b are each formed by grooves provided in the outer peripheral portion 8 (Figure 3) of the seal member 6. The radial air holes 12a, 12a and the axial air hole 12b are provided at different circumferential positions. The number and circumferential positions of the air holes 12a, 12b are not limited to those shown in Figure 6.

[0037] 3 and 6, the radial air holes 12a, 12a and the axial air hole 12b communicate with each other via the groove bottom surface 9c of the seal groove 9. Therefore, when the rolling bearing 1 (FIG. 1) is rotating, the internal bearing pressure can be released to the outside from the two radial air holes 12a, 12a via the axial air hole 12b.

[0038] <Inner ring seal groove> As shown in Figure 1, the seal groove 7 of the inner ring 2 has, in order axially outward, an inner surface (inner groove wall surface) 7a, a groove bottom surface 7b, and an outer surface (outer groove wall surface) 7c. The inner surface 7a connects to inner ring shoulders provided on both axial sides of the raceway surface 2a and forms an inclined surface that slopes toward the inner diameter as it extends axially outward. The groove bottom surface 7b, which smoothly connects to this inner surface 7a, has a shape that is recessed toward the inner diameter. The outer surface 7c connects smoothly to the groove bottom surface 7b and forms an inclined surface that slopes toward the outer diameter as it extends axially outward.

[0039] As shown in FIG. 3, nitrile rubber is typically used as the material for the rubber material 11 in the seal member 6, but other materials such as acrylic rubber, silicone rubber, or fluororubber may also be used depending on the operating temperature.

[0040] <Lip, etc.> As shown in Figure 4, the inner peripheral portion 13 of the seal member 6, which extends radially inward from the inner diameter portion of the core bar 10, is made of the rubber material 11. The inner peripheral portion 13 has a constricted portion 14, a bent portion Be, a main lip 15, and a sub-lip 16. The constricted portion 14 is located radially inward from the inner diameter portion of the core bar 10, and its thickness decreases toward the inner diameter. The bent portion Be is connected to the inner diameter portion of the constricted portion 14 and extends axially outward, bending, i.e., elastically deforming, the inner peripheral portion 13, including the main lip 15.

[0041] The main lip 15 is connected to the inner diameter portion of the bent portion Be. The secondary lip 16 is connected to the axially inner surface of the bent portion Be. The secondary lip 16 protrudes axially inward from the axially inner surface of the bent portion Be and, as shown in FIG. 1 , does not contact the seal groove 7 of the inner ring 2. A labyrinth seal Rs is formed between the tip of the secondary lip 16 and the inner surface 7a of the seal groove 7. As shown in FIG. 4 , the constricted portion 14, bent portion Be, main lip 15, and secondary lip 16 are integrally molded. "Integral molding" means that the constricted portion 14, bent portion Be, main lip 15, and secondary lip 16 are molded as part or the whole of a single object from a single material, for example, by injection molding, rather than being composed of multiple elements joined together.

[0042] The outer peripheral surface of the bent portion Be facing the axially outer portion of the constricted portion 14 is formed as an inclined surface Bea that slopes inward as it extends axially outward. The angle α1 formed by the inclined surface Bea of ​​the bent portion Be and the axially outer portion of the constricted portion 14 is set to an acute angle within the range of interference where the main lip 15 contacts the seal groove 7.

[0043] The main lip 15 has a lip main body 15b that slopes axially inward as it extends toward the inner diameter side, and a contact portion 15c provided on the outer surface portion of the lip main body 15b at the tip side. This contact portion 15c is also referred to as the inner diameter side tip portion or lip tip portion. The contact portion (lip tip portion) 15c contacts the seal groove 7 of the inner ring 2. Specifically, the contact portion 15c is formed in an R-shape that abuts the outer surface 7c of the seal groove 7 in the normal direction. The outer diameter surface 15ca of the contact portion 15c slopes axially inward as it extends axially outward and smoothly connects to the R-shape.

[0044] <Radial Variation Reduction Means> In Figure 5, the solid line indicates the position of the contact portion 15c when the set interference is minimum, the dashed line indicates the center of the interference, and the dashed two-dot line indicates the position of the contact portion 15c when the interference is maximum. As shown in Figures 4 and 5, the seal member 6 includes a radial variation reduction means Rcr that reduces the radial variation Δa of the contact portion 15c to a predetermined value or less within the range of the interference. The radial variation reduction means Rcr reduces the radial variation Δa within the range of the interference by changing the seal shape of the inner peripheral portion 13 located radially inward from the core 10. Specifically, the bent portion Be, which is bent radially inward from the constricted portion 14, protrudes axially away from the bearing, i.e., axially outward. By protruding this bent portion Be axially outward, the angle α1 formed between the inclined surface Bea of ​​the bent portion Be and the axially outer portion of the constricted portion 14 becomes an acute angle within the range of the interference.

[0045] The axial protrusion of the bent portion Be, under maximum interference conditions, satisfies the relationship: bottom Ks of the constricted portion 14 < maximum protrusion position Pk of the bent portion Be ≤ end face (also referred to as "width face") of the inner or outer ring. In other words, the radial change reduction device Rcr ensures that, under maximum interference, the axially outer maximum protrusion position Pk of the bent portion Be is axially outer than the bottom Ks of the axially outer part of the constricted portion 14 and is the same as or axially inner than the axial position Tm of the end face of the inner or outer ring. Here, "axially inner" refers to the direction toward the interior of the bearing. The axial thickness Ta of the bottom Ks of the constricted portion 14 is greater than the radial thickness Tb (thickness at the base of the constricted portion) from the inner diameter portion of the constricted portion 14 to the inner circumferential surface Beb of the bent portion Be.

[0046] <Operation and Effect> In the rolling bearing described above, the radial change reduction means Rcr reduces the radial change Δa of the contact portion 15c of the main lip 15 to a specified value or less within the range of the interference. Therefore, even if the interference changes due to oscillation of the inner ring or a change in pressure inside the bearing while the bearing is rotating, the sealing performance of the seal groove 7 of the inner ring 2 can be stabilized. This makes it possible to reduce the amount of dust generated from inside the bearing and also to prevent foreign matter from entering from outside the bearing.

[0047] The axial protrusion of the bent portion Be is such that, under maximum interference, the bottom Ks of the constricted portion 14 is less than the maximum protruding position Pk of the bent portion Be and less than the end face of the inner or outer ring. In this case, the maximum distance of the entire seal member in the axial direction away from the bearing remains unchanged, and the bent portion Be does not protrude from the bearing end face. By forming the seal member 6 in this shape, the amount of elastic deformation at the bent portion Be increases. Therefore, the center of rotation of the approximate circumference, which is the movable range of the contact portion 15c of the main lip 15, moves axially away from the bearing, making it easier to position the contact portion 15c at the center of interference near directly below the center of rotation. This allows the radial change Δa of the contact portion 15c of the main lip 15 to be smaller than in conventional structures.

[0048] Furthermore, when Ta>Tb, the amount of elastic deformation can be increased on the inner diameter side of the constricted portion 14. Therefore, the radial change Δa of the contact portion 15c of the main lip 15 within the interference range can be made even smaller than in the conventional structure.

[0049] In addition to the seal member 6 being equipped with radial change reduction means Rcr, the contact portion 15c connected to the lip main body portion 15b is formed in an R-shape that contacts the outer surface 7c of the seal groove 7 in the normal direction. As a result, even if the internal bearing pressure rises during rotation of the rolling bearing 1 (FIG. 1), the main lip 15 can suppress the intrusion of foreign matter from the atmosphere and can suppress changes in the surface pressure distribution of the main lip 15. This makes it possible to prevent undesirable increases in torque and undesirable heat generation by the main lip 15.

[0050] As shown in Figure 6, an air hole 12 for releasing the internal pressure of the rolling bearing 1 (Figure 1) is provided in the outer peripheral portion 8 (Figure 3) of the seal member 6. Therefore, by releasing the internal bearing pressure through the air hole 12 when the rolling bearing 1 (Figure 1) is rotating, it is possible to suppress excessive changes in the interference of the seal member 6 and the outflow of grease caused by an increase in internal bearing pressure.

[0051] <Regarding Other Embodiments> In the following description, parts corresponding to matters previously described in each embodiment are assigned the same reference numerals, and duplicated description will be omitted. When only part of the configuration is described, the other parts of the configuration are the same as those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. 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.

[0052] [Second embodiment: Fig. 7, one-sided seal] As shown in Fig. 7, the seal member 6 may be provided on only one axial side of the rolling bearing 1. In this case, it is possible to reduce the number of parts and the number of steps required to process the seal grooves, etc., compared to a rolling bearing provided with seal members on both axial sides, thereby reducing costs.

[0053] [Third embodiment: Fig. 8, crown-shaped cage] As shown in Fig. 8, the cage 5 may be a so-called crown-shaped cage having a shape in which one axial side of the pocket Pt is open. In this case, the number of parts of the cage 5 can be reduced compared to the above-mentioned two-piece cage, thereby reducing the number of assembly steps.

[0054] [Fourth embodiment: FIG. 9, one-sided seal] In a rolling bearing 1 having a crown-shaped cage 5 as shown in FIG. 9, a seal member 6 may be provided on only one axial side of the rolling bearing 1.

[0055] A rolling bearing 1 according to a fifth embodiment of the present invention is shown in Figures 13 to 15C. The rolling bearing 1 according to the fifth embodiment shown in Figure 13 has the same general configuration as the rolling bearing according to the first embodiment described above. In the fifth embodiment, components similar to those in the first embodiment are given the same reference numerals, and detailed descriptions will be omitted. The rolling bearing 1 of this embodiment is an inner ring rotating type bearing, in which the inner ring 2 constitutes the rotating ring and the outer ring 3 constitutes the fixed ring.

[0056] The cage 5 in this embodiment is a so-called crown-type cage, in which multiple pockets Pt, which open to one axial side, are formed at intervals in the circumferential direction, and balls 4 are held inside the pockets Pt.

[0057] A bearing space SP is formed between the inner ring 2 and the outer ring 3. The bearing space SP is an annular space located radially outside the inner ring 2 and radially inside the outer ring 3. The balls 4 and the cage 5 are disposed in the bearing space SP. Grease, a type of lubricant, is sealed in the bearing space SP.

[0058] In the following description, the direction toward the center of the bearing space SP in the axial direction is referred to as the "axially inner" direction, and the direction opposite to the bearing space SP or away from the center of the bearing space SP is referred to as the "axially outer" direction.

[0059] <Regarding the sealing structure> The axial side of the bearing space SP is sealed with a sealing member 6. In other words, the bearing space SP is formed by the inner ring 2, the outer ring 3, and the sealing member 6. The sealing member 6 prevents grease from leaking from the bearing space SP, as well as preventing foreign matter from entering the bearing space SP and preventing dust, seal wear powder, and the like from being released from the bearing space SP. In this embodiment, both axial sides of the bearing space SP are sealed with the sealing member 6. The sealing member 6 is attached to the inner circumferential surface of the outer ring 3, which is the fixed ring.

[0060] 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 surfaces 7a are connected to the outer peripheral surface 2b of the inner ring 2, which are inner ring shoulders provided on both axial sides of the raceway surface 2a, and are inclined axially outward toward the inner diameter side.

[0061] The groove bottom surface 7b smoothly connects to the inner groove wall surface 7a and extends approximately parallel to the axial direction. The outer groove wall surface 7c smoothly connects to the groove bottom surface 7b and is inclined toward the outer diameter side as it extends axially outward. The outer groove wall surface 7c connects to the outer diameter surface 2c at the axial end of the inner ring 2. In this embodiment, the outer diameter surface 2c at the axial end of the inner ring 2 connects to the outer edge of the axial end surface 2d of the inner ring 2, and the radial dimension of the outer diameter surface 2c at the axial end of the inner ring 2 and the radial dimension of the axial end surface 2d of the inner ring 2 are the same.

[0062] 14, the inner peripheral portion 13 of the seal member 6 has a constricted portion 14, a main lip 15, and a sub-lip 16. The constricted portion 14, the main lip 15, and the sub-lip 16 are integrally formed by molding. The thickness of the constricted portion 14 gradually decreases from the outer diameter end of the inner peripheral portion 13 toward the inner diameter.

[0063] The main lip 15 and the secondary lip 16 are connected to the constricted portion 14. The main lip 15 is connected to the inner diameter side 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.

[0064] The main lip 15 has a base end 15a, a lip main body 15b, and a lip tip end 15c. The base end 15a extends from the constricted portion 14 radially inward at an inclination axially outward. The lip main body 15b extends radially inward from the base end 15a. The lip tip end 15c is provided on the outer surface portion on the tip side of the lip main body 15b. Specifically, the lip tip end 15c extends radially inward from the tip of the lip main body 15b at an inclination axially outward.

[0065] The lip main body 15b has a seal surface 20 facing outward in the axial direction (opposite the bearing space SP) and a seal back surface 22 facing inward in the axial direction (the bearing space SP). A radial dimension B of a tip 22a of the seal back surface 22 of the lip main body 15b, i.e., a radial inner end 22a, is set to be larger than an outer diameter dimension A of the end face 2d of the inner ring 2 (B>A).

[0066] As described above, the radial dimension of the outer diameter surface 2c at the axial end of the inner ring 2 is the same as the radial dimension of the axial end surface 2d of the inner ring 2. Therefore, the radial dimension B of the tip 22a of the seal back surface 22 is set larger than the outer diameter dimension A of the outer diameter surface 2c at the axial end of the inner ring 2.

[0067] When the seal member 6 is fitted into the seal groove 7 of the inner ring 2, the tip end 15c of the main lip 15 must climb over the outer diameter surface 2c of the axial end of the inner ring 2. In other words, the outer diameter surface 2c of the axial end of the inner ring 2 forms the inner diameter surface 24 of the seal inlet when fitting the seal member 6. In other words, the radial dimension B of the tip end 22a of the seal back surface 22 is set larger than the diameter A of the inner diameter surface 24 of the seal inlet.

[0068] [Correction based on Rule 91, 28.08.2025] In this embodiment, the sealing surface 20 of the lip body 15b is parallel to the radial direction of the bearing (the radial axis AX shown by the dashed line in Figure 14). However, the sealing surface 20 may extend radially outward from the tip 20a with an inclination in the axial direction relative to the radial axis AX.

[0069] In other words, if an imaginary extension line of the seal surface 20 inclined relative to the radial axis AX is denoted by L1, in the present disclosure, the angle θ of the seal surface 20 relative to the radial axis AX is set to be equal to or greater than 0°. Here, when the angle θ is 0°, the seal surface 20 is parallel to the radial axis AX. When the angle θ is greater than 0°, i.e., a positive value, the seal surface 20 is inclined axially outward relative to the radial axis AX. When the angle θ is less than 0°, i.e., a negative value, the seal surface 20 is inclined axially inward relative to the radial axis AX.

[0070] 15A to 15C, the seal surface 20 of the lip main body 15b is the surface that comes into contact with the insertion jig T when the seal member 6 is fitted into the seal groove 7 of the inner ring 2. In other words, in the present disclosure, the angle θ of the seal surface 20 of the lip main body 15b that comes into contact with the insertion jig T with respect to the radial axis AX is set to be 0° or greater.

[0071] [Correction based on Rule 91, August 28, 2025] The radial position of the radial midpoint on the seal surface 20 of the lip main body 15b is defined as P1. Specifically, "radial position P1" refers to the radial midpoint between the radial inner end and the radial outer end of the seal surface 20 of the lip main body 15b. Furthermore, the thickness dimension of the lip tip 15c in its natural state is defined as C. Here, the natural state refers to a state in which the seal tip 15c is not in contact with the seal groove 7, such as the state before the seal member 6 shown in FIG. 15A is installed in the bearing 1. Furthermore, the radial position P2 is defined as the sum of the outer diameter dimension A of the end face 2d of the inner ring 2 and the thickness dimension C of the lip tip 15c. In this embodiment, the radial position P1 is located radially outward of the radial position P2.

[0072] [Correction based on Rule 91, 28.08.2025] However, the positional relationship between the seal surface 20 and the radial position P2 is not limited to this. Specifically, as shown in Figure 15C , when the seal member 6 is assembled into the seal groove 7 of the inner ring 2, the innermost radial position P3 of the portion of the seal surface 20 that comes into contact with the insertion jig T needs to be located radially outward from the radial position P2, which is the sum of the outer diameter A of the end face 2d of the inner ring 2 and the thickness C of the lip tip 15c. In other words, the jig T needs to come into contact with the seal surface 20 at a position spaced radially from the outer edge of the end face 2d of the inner ring 2 by the thickness C of the lip tip 15c.

[0073] <Assembly of Seal Member> The assembly process for the seal member 6 of this embodiment will be described below using Figures 15A, 15B, and 15C. First, the assembly process for the conventional seal member 106 will be described using Figures 16A, 16B, and 16C. Note that arrows F in Figures 15A to 15C and 16A to 16C indicate the force acting on the seal surfaces 20, 120 of the seal members 6, 106 when the seal members 6, 106 are pressed into the seal groove 7 of the inner ring 2.

[0074] As shown in Figure 16A, in a conventional seal member 106, the radial dimension B1 of the tip 122a of the seal back surface 122 in the lip main body 115b of the main lip 115 is smaller than the outer diameter dimension A of the end face 2d of the inner ring 2 (B1 < A). For this reason, when the seal member 106 is inserted into the bearing 1, the back surface 122 side of the lip main body 115b comes into contact with the end face 2d of the inner ring 2, as shown in Figure 16B. When the seal member 106 is pushed in in this state, it is pushed in while rotating so that the lip tip portion 115c faces the outer ring 2, as shown in Figure 16C.

[0075] Because the main lip 115 is shaped so that it contacts the seal groove 7 of the inner ring 2 on the outside in the axial direction, the main lip 115 will not enter the seal groove 7 simply by pushing in the outer diameter side of the seal member 106. Therefore, it is necessary to push in the vicinity of the main lip 115 using a jig T. If the pushing amount is inappropriate at this time, the main lip 115 will not enter the seal groove 7, resulting in an assembly failure.

[0076] On the other hand, if the insertion jig T is pushed in too far, the main lip 115 may buckle, as shown in Fig. 17. In Fig. 17, the area in the main lip 115 where buckling may occur is indicated by R1. Furthermore, depending on the contact position between the insertion jig T and the seal surface 120, the lip tip 115c may come into contact with the jig T, which may cause a defect in the lip tip 115c. In Fig. 17, the area in the lip tip 115c where a defect may occur is indicated by R2.

[0077] 15A, in this embodiment, the radial dimension B of the tip 22a of the seal back surface 22 of the lip main body 15b is set larger than the outer diameter dimension A of the end face 2d of the inner ring 2 (B>A). Furthermore, as shown in Fig. 14, the seal surface 20 of the lip main body 15b is either parallel to the radial axis AX or inclined axially outward with respect to the radial axis AX.

[0078] This makes it easier for the main lip 15 to climb over the end face 2d of the inner ring 2, as shown in Fig. 15B. Furthermore, as shown in Fig. 15C, contact between the seal surface 20 and the jig T makes it easier for the main lip 15 to bend axially inward, improving the ease of insertion of the main lip 15. As a result, the main lip 15 can be inserted without problems such as buckling.

[0079] Furthermore, the innermost radial position P3 of the portion of the seal surface 20 that comes into contact with the insertion jig T is located radially outward of the radial position P2, which is the sum of the outer diameter dimension A of the end face 2d of the inner ring 2 and the thickness dimension C of the lip tip portion 15c. This makes it difficult for the lip tip portion 15c that has climbed over the end face 2d of the inner ring 2 to be pinched by the jig T. In this way, the lip tip portion 15c of the main lip 15 does not interfere with the insertion jig T, so the seal member 6 can be inserted without wearing down the lip tip portion 15c. As a result, the sealing performance of the seal member 6 after installation is ensured.

[0080] As described above, in this embodiment, even if the seal member 6 has a seal shape that contacts the seal groove 7 of the inner ring 2 on the axial outside, the seal member 6 can be attached to the bearing 1 without problems such as poor assembly, buckling of the main lip 115, or defects in the lip tip portion 15 c.

[0081] 14, the radial dimension B of the tip 22a of the seal back surface 22 of the lip main body 15b is set larger than the outer diameter A of the end face 2d of the inner ring 2 (B>A). This makes it easier for the main lip 15 to climb over the end face 2d of the inner ring 2, which forms the inlet of the seal member 6, as shown in FIG. 15B. As a result, the seal member 6 can be easily assembled to the bearing 1.

[0082] In this embodiment, as shown in Fig. 14 , the seal surface 20 of the lip main body 15b is parallel to the radial direction (radial axis AX) of the bearing 1, or extends radially outward from the tip 20a at an angle opposite to the bearing space (axially outward). With this configuration, as shown in Fig. 15B , when the seal member 6 is assembled to the bearing 1, the seal surface comes into contact with a jig, which makes it easy for the main lip to bend axially inward (toward the interior of the bearing). This improves assembly of the seal member 6 to the bearing 1.

[0083] 14, in this embodiment, a radial position P1 of the radial midpoint of the seal surface 20 of the lip main body 15b is located radially outward of a radial position P2 obtained by adding a thickness dimension C of the lip tip portion 15c to the outer diameter dimension A of the end face 2d of the inner ring 2. With this configuration, as shown in Fig. 15C, the lip tip portion 15c of the main lip 15 that has climbed over the end face 2d of the inner ring 2 is less likely to be pinched by a jig T that comes into contact with the seal surface 20. This makes it possible to prevent defects from occurring in the lip tip portion 15c of the main lip 15.

[0084] The present invention is not limited to the above-described embodiment, and various additions, modifications, or deletions are possible without departing from the spirit and scope of the present invention. For example, in the above-described embodiment, balls 4 are used as rolling elements, but this is not limiting. Also, in the above-described embodiment, seal members 6 are provided on both axial sides of the bearing space SP, but they may be provided on only one side. Therefore, such arrangements are also included within the scope of the present invention.

[0085] In each embodiment, the air holes in the outer peripheral portion of the seal member may be omitted. In other words, the seal member may not be provided with any air holes. A steel plate wave cage may be used in a deep groove ball bearing. A rolling bearing equipped with a radial change reduction means or a rolling bearing in which the radial dimension B of the tip of the seal back surface of the lip main body is set larger than the outer diameter dimension A of the end face of the inner ring is not limited to deep groove ball bearings, but can be applied to various bearings such as angular contact ball bearings, tapered roller bearings, and cylindrical roller bearings.

[0086] As described above, the preferred embodiment has been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present invention. Therefore, such additions, modifications, and deletions are also included in the scope of the present invention.

[0087] DESCRIPTION OF SYMBOLS 1...Rolling bearing 2...Inner ring 3...Outer ring 4...Ball (rolling element) 6...Seal member (contact seal) 7...Seal groove 10...Core metal 14...Neck portion 15...Main lip (contact type lip) 15b...Lip main body 15c...Contact portion (lip tip) 20...Seal surface 22...Seal back surface A...Outer diameter dimension of end face of inner ring (outer diameter of seal groove entrance) B...Radial dimension of tip of seal back surface C...Thickness dimension of lip tip P1...Radial position of radial midpoint of seal surface P2...Radial position obtained by adding the thickness dimension of the lip tip to the outer diameter of the end face of the inner ring SP...Bearing space Be...Bend portion Ks...Bottom Pk...Maximum protruding position Δa...Radial change amount Rcr...Radial change amount reduction means Tm...Axial position of end face

Claims

1. A rolling bearing comprising an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a sealing member that seals the bearing space between the inner ring and the outer ring, wherein the sealing member includes a core and a contact-type lip located radially inward from the core, the lip having a contact portion that contacts the seal groove of the inner ring with an interference, and wherein the sealing member is equipped with radial variation reduction means that reduces the radial variation of the contact portion to a specified value or less within the range of the interference.

2. A rolling bearing as claimed in claim 1, wherein the sealing member has a constricted portion located radially inward of the inner diameter portion of the core bar and having a thickness that decreases towards the inner diameter side, a bent portion connected to the inner diameter portion of this constricted portion, and the lip connected to the inner diameter portion of this bent portion, and the radial change reduction means is such that, when the interference is at its maximum, the maximum axially outer protruding position Pk of the bent portion is axially outer than the bottom Ks of the axially outer portion of the constricted portion and is at the same position as or axially inner than the axial position Tm of the end face of the inner or outer ring.

3. A rolling bearing as set forth in claim 2, wherein the axial thickness Ta at the bottom of the constricted portion is greater than the radial thickness Tb from the inner diameter portion of the constricted portion to the inner circumferential surface of the bent portion.

4. A rolling bearing according to claim 1 or 2, wherein the sealing member is provided on only one axial side of the rolling bearing or on both axial sides thereof.

5. A rolling bearing comprising an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a seal member, wherein a bearing space is formed by the inner ring, the outer ring, and the seal member, a seal groove is formed circumferentially on the outer peripheral surface of the inner ring, the seal member is attached to the outer ring at its base end which is its outer edge, and its tip end which is its inner edge is in contact with the seal groove, the seal member having a main lip at its tip end, the main lip having a lip main body portion extending radially and a lip tip end which extends axially outward at an inclination from the tip of the lip main body toward the radially inward, the lip tip end being in contact with the seal groove, and the radial dimension B of the tip at the seal back surface on the axially inner side of the lip main body portion is greater than the outer diameter dimension A of the end face of the inner ring.

6. A rolling bearing according to claim 5, wherein the sealing surface on the axially outer side of the lip body is parallel to the radial direction of the bearing, or extends from the tip radially outward at an incline axially outward.

7. A rolling bearing as claimed in claim 5 or 6, wherein the radial position P1 of the radial midpoint between the radial inner end and radial outer end of the axially outer sealing surface of the lip main body is located radially outward of the radial position P2 obtained by adding the outer diameter dimension A of the end face of the inner ring to the thickness dimension C of the lip tip end in its natural state.

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