Rolling bearings

Abstract

To provide a rolling bearing with stable sealing properties. [Solution] The rolling bearing comprises an inner ring 2, an outer ring 3, a plurality of rolling elements interposed between the inner ring 2 and the outer ring 3, and a seal member 6 that seals the bearing space between the inner ring 2 and the outer ring 3. An outer peripheral portion 8 of the seal member 6 is fixed to a seal groove 9 in the outer ring 3, and an inner peripheral portion 13 of the seal member 6 is provided with a lip 15 that contacts the outer surface 7c of the seal groove 7 in the inner ring 2. The seal member 6 is equipped with a seal collapse prevention means St that prevents the inner peripheral portion 13 from collapsing axially inward. The seal collapse prevention means St has an inner surface 8a of the outer peripheral portion 8 of the seal member 6 that contacts the seal groove 9 in the outer ring 3, which has an inclined surface 8aa that slopes inward in the axial direction.

Description

[Technical Field]

[0001] The present invention relates to a rolling bearing, and to a technique for stabilizing sealing performance. [Background technology]

[0002] 12, there is a model of rolling bearing 50 for a servo motor in which encoder 52 is located near motor 51. For such models, low dust generation as the rolling bearing 50 is required using a contact seal to prevent malfunction of encoder 52 due to dust generation from inside the bearing and seal wear powder adhering to encoder 52.

[0003] 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 comes into contact with the seal groove, and the inclined surface of the seal groove. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-72083 [Patent Document 2] Japanese Patent Publication No. 2022-102580 Summary of the Invention [Problem to be solved by the invention]

[0005] 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 shape proposals in terms of dust generation. Both prior art documents have a structure in which the axial outer surface of the inner ring seal groove makes contact (hereinafter referred to as the inner ring contact portion), which is effective in preventing dust generation from inside the bearing due to increases in internal pressure, and sealability is ensured when the inner ring contact portion is in contact.

[0006] Meanwhile, the axial position of this seal after insertion into the bearing is determined by the location where the outer ring seal groove and the bearing side of the seal outer diameter lip come into axial contact (hereinafter referred to as the outer ring contact area). The axial end face of the outer ring seal groove may be angled to take into account factors such as machinability when cutting the seal groove. In this case, if the outer diameter lip follows this angle at the outer ring contact area when the seal is inserted into the bearing, the seal will be positioned at an angle.

[0007] If the seal is positioned in an inclined position, the inner ring contact area will move away from the seal groove, creating a gap. If a gap is created at the inner ring contact area, the seal will not perform adequately. In particular, in conventional seals that contact the outside of the seal groove, the inner ring contact area is inserted with interference. This makes it easy for the seal to fall along the outer ring contact surface due to the reaction force of the interference, making it difficult to ensure stable sealing. Prior literature does not address this issue.

[0008] As mentioned above, the relative axial position of the seal inserted into the bearing and the bearing is determined by the state of contact with the outer ring seal groove. As shown in Figure 13, outer ring contact surface 30 may be inclined, and if seal member 31 is inserted so that it follows the inclination of outer ring contact surface 30, the entire seal member 31 will tilt.

[0009] In particular, in the case of the seal element 31 that contacts the axially outer side of the inner ring seal groove 32, the inner ring seal groove 32 and the inner diameter lip 33 are inserted with interference. As a result, the reaction force tends to generate a force F1 that causes the seal element 31 to tilt along the outer ring contact surface 30. This tilting reduces the interference and makes the seal unstable. If preload is applied to the bearing in this tilted state, the relative position of the outer ring 34 and inner ring 35 changes by the amount of the clearance inside the bearing, and in some cases a clearance may even occur. This can lead to base oil leakage and a lack of robustness.

[0010] An object of the present invention is to provide a rolling bearing with stable sealing performance. [Means for solving the problem]

[0011] The rolling bearing 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 that closes a bearing space between the inner ring and the outer ring, wherein an outer peripheral portion of the seal member is fixed to a seal groove of the outer ring, and an inner peripheral portion of the seal member is provided with a lip that comes into contact with an outer surface of the seal groove of the inner ring, The seal member includes a seal collapse prevention means for preventing the inner peripheral portion from collapsing inward in the axial direction.

[0012] With this configuration, the seal tilt prevention means prevents the inner peripheral portion of the seal member from tilting axially inward, i.e., toward the inside of the bearing. This seal tilt prevention means reduces the range of rotational movement of the seal member compared to conventional structures. This stabilizes the seal position after the seal member is inserted into the bearing, and the seal member is less likely to shift position even when subjected to a reaction force caused by contact between the outer surface of the seal groove in the inner ring and the lip. In this way, the sealing performance of the rolling bearing can be stabilized.

[0013] The seal collapse prevention means may have an inclined surface that slopes inward in the axial direction of the inner surface of the outer peripheral portion of the seal member, the inner surface that contacts the seal groove of the outer ring. In this case, the position of the seal member inserted into the bearing is more likely to be stable, thereby more reliably stabilizing sealing performance. Furthermore, robustness is improved because changes in interference due to the bearing are reduced.

[0014] The angle of the inclined surface may be set to satisfy the following relationship with respect to a plane perpendicular to the axial direction: 0°<angle of the inclined surface≦angle of the inner surface of the seal groove of the outer ring In this case, the inclined surface of the seal member is arranged substantially along the inner surface of the seal groove of the outer ring, so the position of the seal member inserted into the bearing is more likely to be stabilized.

[0015] The seal member may be provided with an air hole on its outer circumferential side for releasing the internal pressure of the rolling bearing. In this case, by releasing the internal bearing pressure through the air hole when the rolling bearing rotates, it is possible to suppress excessive changes in the interference of the seal member and the outflow of grease caused by an increase in the internal bearing pressure.

[0016] 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. [Effects of the Invention]

[0017] The rolling bearing 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 that seals the bearing space between the inner ring and the outer ring, the outer peripheral portion of the seal member being fixed in a seal groove in the outer ring, the inner peripheral portion of the seal member being provided with a lip that contacts the outer surface of the seal groove in the inner ring, and the seal member being provided with seal collapse prevention means that prevents the inner peripheral portion from collapsing axially inward, thereby stabilizing the sealing performance of the rolling bearing. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a vertical cross-sectional view of a rolling bearing according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the cage of the rolling bearing. [Figure 3] FIG. 2 is an enlarged cross-sectional view showing a seal member of the rolling bearing. [Figure 4] FIG. 2 is an enlarged cross-sectional view of the lip and other parts of the seal member. [Figure 5] 10 is an enlarged cross-sectional view showing a comparison of the outer peripheral side portions of the seal member and a conventional seal member. FIG. [Figure 6]10 is an enlarged cross-sectional view showing the outer peripheral side portions of the seal member and a conventional seal member together with a seal groove in an outer ring. FIG. [Figure 7] FIG. 2 is a perspective view of a seal member of the rolling bearing. [Figure 8A] FIG. 6 is an enlarged cross-sectional view showing an outer peripheral portion of a seal member in a rolling bearing according to a second embodiment of the present invention. [Figure 8B] FIG. 10 is an enlarged cross-sectional view showing a modified example of the seal member. [Figure 9] FIG. 10 is a vertical cross-sectional view of a rolling bearing according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a vertical cross-sectional view of a rolling bearing according to a fourth embodiment of the present invention. [Figure 11] FIG. 10 is a vertical cross-sectional view of a rolling bearing according to a fifth embodiment of the present invention. [Figure 12] FIG. 1 is a diagram illustrating a rolling bearing for a servo motor. [Figure 13] 10A and 10B are diagrams for explaining problems with a conventional rolling bearing; DETAILED DESCRIPTION OF THE INVENTION

[0019] [First embodiment] A rolling bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 7. 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.

[0020] <General structure of rolling bearing> 1 is a cross section (longitudinal cross section) of the rolling bearing 1 cut along a plane including the axial direction. The same applies to cross sections of the 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 the 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. A lubricant such as grease is sealed in the bearing space between the inner and outer rings 2, 3.

[0021] 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 axis, 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."

[0022] <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 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.

[0023] <Seal structure, etc.> As shown in Figure 1, each seal member 6 is a contact seal in which a lip 15 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 securing the seal member are provided on the inner peripheral surface of the outer ring 3 opposite each seal groove 7. As shown in Figure 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 secured in the seal groove 9 of the outer ring 3.

[0024] <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. As shown in Figure 1, the inner surface 9a connects to outer ring shoulders located on both axial sides of the raceway surface 3a. The inner surface 9a is formed as an inclined surface that slopes outward in the axial direction, taking into account factors such as machinability when cutting the seal groove 9. As shown in Figure 3, the groove bottom surface 9c, which smoothly connects to the inner surface 9a, is recessed radially outward. The outer surface 9b is formed as an inclined surface that smoothly connects to the groove bottom surface 9c and slopes inward in the axial direction. The outer peripheral portion 8 of the seal member 6 has an interference (not shown) and is fitted and fixed in the seal groove 9 in an elastically deformed state.

[0025] An inner peripheral portion 13 of the seal member 6 is provided with a lip 15 that comes into contact with the outer surface 7 c of the seal groove 7 of the inner ring 2 . 1 and 3, a portion of the lip 15 of the seal member 6 is shown as being embedded in the seal groove 7 of the inner ring 2, but this portion is an interference and is actually in contact with the seal groove 7 in an elastically deformed state. The same applies to the seal structures shown in Figures 9 to 11, which will be described later.

[0026] <Air vent> As shown in Figure 7, a plurality of air holes 12 for releasing the internal pressure of the rolling bearing are provided in the outer peripheral portion 8 (Figure 3) of the seal member 6. 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 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 7.

[0027] 3 and 7, 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.

[0028] <Inner ring seal groove> 1, the seal groove 7 of the inner ring 2 has, in that order axially outward, an inner side surface 7a, a groove bottom surface 7b, and an outer side surface 7c. Here, in the seal groove 7, the side surface facing the inside of the bearing is called the inner side surface 7a, and the side surface facing the outside of the bearing is called the outer side surface 7c. The inner surface 7a is connected 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 moves axially outward. The groove bottom surface 7b, which smoothly connects to this inner surface 7a, is shaped to be concave toward the inner diameter. The outer surface 7c is smoothly connected to the groove bottom surface 7b and forms an inclined surface that slopes outward toward the outer diameter as it moves axially outward.

[0029] 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, and fluororubber may also be used depending on the operating temperature.

[0030] <Lip> As shown in Figure 4, the inner peripheral portion 13 of the seal member 6, which extends radially inward beyond the inner diameter of the core metal 10, is made of the rubber material 11. The inner peripheral portion 13 has a constricted portion 14 whose thickness decreases toward the inner diameter, and a main lip (lip) 15 and a sub-lip 16 that are connected to the constricted portion 14. The constricted portion 14, main lip 15, and sub-lip 16 are molded as a single unit. "Molded as a single unit" means that the constricted portion 14, main lip 15, and sub-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.

[0031] A main lip 15 is connected to the inner diameter end of the constricted portion 14, and a secondary lip 16 protrudes axially inward from the inner surface of a base end 15a of this main lip 15. As shown in Figure 1, a labyrinth seal Rs is formed between the tip end of the secondary lip 16 and the inner surface 7a of the seal groove 7.

[0032] 4, 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 on the tip side. The tip end 15c of the main lip 15 is formed in an R-shape that contacts the outer surface 7c of the seal groove 7 in the normal direction. The 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.

[0033] <Means to prevent stickers from falling over> As shown in Figure 3, the seal member 6 is equipped with a seal collapse suppression means St that suppresses the inner peripheral portion 13 from collapsing axially inward. Specifically, the seal collapse suppression means St is provided by an inner surface 8a of the outer peripheral portion 8 of the seal member 6, which comes into contact with the seal groove 9 of the outer ring 3, and which has an inclined surface 8aa that slopes inward in the axial direction. Here, the side surface of the outer peripheral portion 8 of the seal member 6 facing the inside of the bearing is referred to as the inner surface 8a. The axially inner side refers to the direction toward the inside of the bearing.

[0034] FIG. 5 is an enlarged cross-sectional view showing a comparison between the outer peripheral portions 8, 80 of the seal member 6 of this embodiment (FIG. 5(b)) and the seal member 60 of the conventional example (FIG. 5(a)). In the conventional example shown in Fig. 5(a), the inner surface 80a of the outer peripheral portion 80 of the seal member 60 is provided on a plane perpendicular to the axial direction. In this case, when the seal member 60 is inserted so as to follow the slope of the inner surface 9a, as shown in Fig. 6(a), the range of rotational movement of the entire seal member 60 is large, and the entire seal member 60 falls axially inward.

[0035] In contrast, the seal member 6 shown in Fig. 5(b) has the aforementioned inclined surface 8aa on the inner surface 8a of the outer peripheral portion 8. The angle α of this inclined surface 8aa is set to have the following relationship with respect to a plane perpendicular to the axial direction, as shown in Fig. 6(b). 0°<angle of inclined surface α≦inclination angle of the inner surface 9a of the seal groove 9 of the outer ring 3 It is more preferable that the angle α of the inclined surface be set to satisfy the following relationship with respect to a plane perpendicular to the axial direction: Inclination angle of the inner surface 9a of the seal groove 9 of the outer ring 3 -1° ≦ Inclination angle of the inclined surface α ≦ Inclination angle of the inner surface 9a of the seal groove 9 of the outer ring 3

[0036] <Action and effect> 1 described above, the seal collapse suppression means St suppresses the entire seal member 6, including the inner peripheral portion 13 (FIG. 3), from collapsing axially inward. As shown in FIG. 6(b), the seal collapse suppression means St has an inclined surface 8aa on the inner surface 8a of the outer peripheral portion 8 of the seal member 6, which contacts the seal groove 9 of the outer ring 3, that slopes inward in the axial direction. This inclined surface 8aa reduces the range of rotational movement of the seal member 6 compared to conventional structures.

[0037] This stabilizes the seal position of the seal member 6 when it is inserted into the bearing, and the position of the seal member 6 is less likely to shift even when subjected to a reaction force caused by contact between the lip 15 and the outer surface 7c of the seal groove 7 of the inner ring 2 shown in Figure 3. This stabilizes the sealing performance of the rolling bearing. Furthermore, robustness is improved because there is less change in interference due to the bearing.

[0038] As shown in Figure 7, air holes 12 that release the internal pressure of the rolling bearing 1 (Figure 1) are provided on the outer circumferential side of the sealing member 6. Therefore, by releasing the internal bearing pressure through the air holes 12 when the rolling bearing 1 (Figure 1) is rotating, it is possible to suppress excessive changes in the interference of the sealing member 6 and the outflow of grease caused by an increase in internal bearing pressure.

[0039] <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 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 partially combine embodiments as long as there is no particular problem with the combination.

[0040] [Second embodiment: FIG. 8A, inclined surface + flat surface] As shown in FIG. 8A, the inner surface 8a of the outer peripheral portion 8 of the seal member 6 may have an inclined surface 8aa and a flat surface 8ab that connects to the inner diameter edge of the inclined surface 8aa. The flat surface 8ab is, for example, provided parallel to a plane perpendicular to the axial direction. In this case, the flat surface 8ab can be used as a reference surface when determining the angle α of the inclined surface 8aa. This allows for more accurate determination of the angle α of the inclined surface 8aa, making it easier to stabilize the sealing position when the seal member 6 is inserted into the bearing. Other advantages similar to those of the above-described embodiment are also achieved.

[0041] [Modification: Figure 8B, Inclined surface + Flat surface + Convex portion] As shown in Figure 8B, multiple protrusions 17 may be provided in the circumferential and radial directions on flat surface 8ab. When this seal member 6 is inserted into the bearing, the protruding tip of each protrusion 17 comes into contact with the inner surface of the seal groove in the outer ring while being elastically deformed. In this case, the pressing force of each protrusion 17 makes it easier to stabilize the sealing position when seal member 6 is inserted into the bearing than with the seal structure of Figure 8A.

[0042] [Third embodiment: Figure 9, one-sided seal] 9, the seal member 6 may be provided on only one axial side of the rolling bearing 1. In this case, the number of parts can be reduced and the number of steps required to process the seal grooves, etc. can be reduced, resulting in cost savings, compared to a rolling bearing provided with seal members on both axial sides.

[0043] [Fourth embodiment: FIG. 10, crown cage] 10, the cage 5 may be a so-called crown cage having an opening on one axial side of the pocket Pt. In this case, the number of parts of the cage 5 can be reduced compared to the two-piece cage described above, thereby reducing the number of assembly steps.

[0044] [Fifth embodiment: FIG. 11, one-sided seal] As shown in FIG. 11, in a rolling bearing 1 having a crown-shaped cage 5, a seal member 6 may be provided on only one axial side of the rolling bearing 1.

[0045] In each embodiment, it is possible to omit or increase the number of air holes in the outer peripheral portion of the seal member. That is, the seal member may be configured to have no air holes or to have multiple air holes. In deep groove ball bearings, a steel plate wave cage may be used. The rolling bearing equipped with the seal tilt suppression means is not limited to deep groove ball bearings, but can be applied to various types of bearings such as angular contact ball bearings, tapered roller bearings, and cylindrical roller bearings.

[0046] Although the embodiments of the present invention have been described above, the disclosed embodiments are illustrative in all respects and are not limiting. 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 meaning and scope of the claims. [Explanation of symbols]

[0047] 1... rolling bearing, 2... inner ring, 3... outer ring, 4... ball (rolling element), 6... seal member, 8... outer peripheral portion, 8a... inner surface, 8aa... inclined surface, 9... seal groove, 9b... outer surface, 12a, 12b... air hole, 13... inner peripheral portion, 15... lip, St... seal collapse prevention means

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 seal member that closes a bearing space between the inner ring and the outer ring, wherein an outer peripheral portion of the seal member is fixed to a seal groove of the outer ring, and an inner peripheral portion of the seal member is provided with a lip that contacts an outer surface of the seal groove of the inner ring, The rolling bearing includes a seal collapse prevention means for preventing the inner peripheral portion of the seal member from collapsing axially inward.

2. 2. The rolling bearing according to claim 1, wherein the seal collapse prevention means is a rolling bearing in which the inner surface of the outer peripheral portion of the seal member that comes into contact with the seal groove of the outer ring has an inclined surface that slopes toward the inner diameter as it extends axially inward.

3. 3. The rolling bearing according to claim 2, wherein the angle of the inclined surface is set to satisfy the following relationship with respect to a plane perpendicular to the axial direction: 0°<angle of the inclined surface≦inclination angle of the inner surface of the seal groove of the outer ring

4. 4. A rolling bearing according to claim 2 or 3, wherein an air hole for releasing internal pressure of the rolling bearing is provided on the outer peripheral portion of the seal member.

5. 4. The rolling bearing according to claim 2, wherein the seal member is provided on only one axial side of the rolling bearing or on both axial sides of the rolling bearing.

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