Rolling bearings

Abstract

To provide a rolling bearing in which the assembly of the sealing member to the bearing is improved. [Solution] The rolling bearing 1 of this disclosure comprises a plurality of rolling elements 4 interposed between inner and outer rings 2 and 3, and a sealing member 6 that closes the bearing space SP between the inner and outer rings 2 and 3. A sealing groove 7 is formed in the circumferential direction on the outer circumferential surface of the inner ring 2. The sealing member 6 is a contact seal attached to the outer ring 3 at its base end, with its tip in contact with the sealing groove 7. The sealing member 6 has a main lip 15 at its tip. The main lip 15 has a lip body portion 15b extending in the radial direction, and a lip tip portion 15c extending from the tip of the lip body portion 15b inclined axially outward toward the radially inward direction. The radial dimension B of the tip 22a on the axially inward side of the seal back surface 22 of the lip body portion 15b is set to be larger than the outer diameter dimension A of the end face 2d of the inner ring 2.

Description

Technical Field

[0005] , , ,

[0001] The present invention relates to a ball bearing incorporated with a sealing member.

Background Art

[0002] In a bearing 100 for a servo motor shown in FIG. 6, there is a model in which an encoder 104 is arranged near a motor 102. For such a model, the encoder 104 may malfunction due to dust generated from inside the bearing 100 or seal wear powder adhering to the encoder 104. In order to prevent such malfunctions, a sealing member is provided in the bearing 100 to reduce dust generation (for example, Patent Documents 1 and 2). <​​​​​​​​​​​​​​​​​​​​​​​​​​​​​The technologies described in Patent Documents 1 and 2 are improvements concerning dust generation from inside bearings. The sealing members in Patent Documents 1 and 2 have a structure that contacts the outer surface of the inner ring seal groove, and are effective against dust generation from inside bearings caused by increased internal pressure. However, Patent Documents 1 and 2 do not disclose a method for assembling the sealing member into the bearing. The sealing member has a shape in which the contact portion at the tip contacts the outer surface of the inner ring seal groove. Therefore, when assembling the sealing member into the bearing, there is a risk of assembly defects occurring, such as the tip not being able to fully enter the seal groove.

[0006] The object of the present invention is to provide a rolling bearing in which the assembly of the sealing member to the bearing is improved. [Means for solving the problem]

[0007] The rolling bearing of the present invention comprises a plurality of rolling elements interposed between an inner and outer ring, and a sealing member that closes the bearing space between the inner ring and the outer ring. A sealing groove is formed circumferentially on the outer circumferential surface of the inner ring, and the sealing member is a contact seal attached to the outer ring at its base end and having a tip that contacts the sealing groove. The sealing member has a main lip at its tip, and the main lip has a lip body portion extending radially and a lip tip portion extending radially inward from the tip of the lip body portion, inclined axially outward. The radial dimension B of the tip on the axially inward back surface of the seal of the lip body portion is set to be larger than the outer diameter dimension A of the end face of the inner ring. The sealing member may be provided on both axial sides of the bearing space, or on only one side.

[0008] In this configuration, the radial dimension B of the tip on the back surface of the lip body is set to be 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 pass over the end face of the inner ring that constitutes the entrance to the seal member. As a result, the ease of assembling the seal member to the bearing is improved.

[0009] In the present invention, the axially outer sealing surface of the lip body may be parallel to the radial direction of the bearing, or it may extend radially outward from the tip and inclined axially outward. With this configuration, when assembling the sealing member to the bearing, the sealing surface comes into contact with the jig, making it easier for the main lip to bend inward towards the bearing. Therefore, the ease of assembling the sealing member to the bearing is improved.

[0010] In the present invention, 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 body may be located radially outward from the radial position P2, which is the sum of the outer diameter dimension A of the end face of the inner ring and the thickness dimension C of the lip tip in its natural state. Here, the natural state refers to the state in which the tip does not contact the seal groove, for example, the state before the seal member is assembled into the bearing. With this configuration, the lip tip of the main lip that has passed over the end face of the inner ring is less likely to be caught in a jig that contacts the sealing surface. This prevents defects from occurring at the lip tip of the main lip. [Effects of the Invention]

[0011] In the rolling bearing of the present invention, the radial dimension B of the tip on the back surface of the lip body is set to be larger than the outer diameter dimension A of the end face of the inner ring (B>A). This makes it easier for the main lip to overcome the end face of the inner ring that constitutes the entrance to the seal member. As a result, the ease of assembling the seal member to the bearing is improved. [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view of a rolling bearing according to the first embodiment of the present invention. [Figure 2] This is an enlarged cross-sectional view of the sealing member of the rolling bearing. [Figure 3A] This diagram illustrates the process of assembling the sealing member onto the inner ring of the rolling bearing. [Figure 3B] This diagram illustrates the process of assembling the sealing member onto the inner ring. [Figure 3C]This is a diagram for explaining the process of assembling the seal member to the inner ring. [Figure 4A] This is a diagram for explaining the process of assembling a conventional seal member to the inner ring of a rolling bearing. [Figure 4B] This is a diagram for explaining the process of assembling the seal member to the inner ring. [Figure 4C] This is a diagram for explaining the process of assembling the seal member to the inner ring. [Figure 5] This is an enlarged view showing the state where the seal member is pressed by a jig. [Figure 6] This is a diagram schematically showing a rolling bearing for a servo motor and the like.

Embodiments for Carrying out the Invention

[0013] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, the "axial direction", "radial direction", and "circumferential direction" are as follows. A rolling bearing includes an outer ring, an inner ring, and balls (rolling elements) interposed between the outer ring and the inner ring. The axial direction is the axial direction of the central axes of the inner ring and the outer ring. The direction orthogonal to the "axial direction" is the "radial direction". The "circumferential direction" refers to the direction along the circumference that makes one full turn around the axis at the center axes of the inner ring and the outer ring. The definitions of these directions are the same in the following description.

[0014] The rolling bearing 1 according to the first embodiment of the present invention will be described together with FIGS. 1 to 3C. <Schematic Configuration of Rolling Bearing> FIG. 1 is a cross-section (vertical cross-section) obtained by cutting the rolling bearing 1 in a plane including the axis of the bearing. As shown in FIG. 1, this rolling bearing 1 is a deep groove ball bearing and includes inner and outer rings 2 and 3, balls 4 which are a kind of rolling elements, a cage 5, and a seal member 6. The rolling bearing 1 of the present embodiment is an inner ring rotation type bearing, in which the inner ring 2 constitutes the rotating ring and the outer ring 3 constitutes the fixed ring.

[0015] An inner raceway surface 2a is formed on the outer peripheral surface of the inner ring 2, and an outer raceway surface 3a is formed on the inner peripheral surface of the outer ring 3. A plurality of balls 4 are interposed between the two raceway surfaces 2a and 3a. The balls 4 are held at regular intervals in the circumferential direction by a cage 5. The cage 5 of the present embodiment is a so-called crown type cage, and a plurality of pockets Pt opened on one side in the axial direction are formed at intervals in the circumferential direction, and the balls 4 are held inside the pockets Pt.

[0016] A bearing space SP is formed between the inner ring 2 and the outer ring 3. The bearing space SP is an annular space outside the inner ring 2 in the radial direction and inside the outer ring 3 in the radial direction. The balls 4 and the cage 5 are arranged in the bearing space SP. Grease, which is a kind of lubricant, is enclosed in the bearing space SP.

[0017] In the following description, regarding the axial direction, the direction toward the center of the bearing space SP is referred to as "axially inner", and the opposite side of the bearing space SP or the direction away from the center of the bearing space SP is referred to as "axially outer".

[0018] <Regarding the seal structure> The axial sides of the bearing space SP are closed by seal members 6. In other words, the bearing space SP is formed by the inner ring 2, the outer ring 3, and the seal members 6. The seal members 6 prevent grease from leaking from the bearing space SP, and also prevent foreign matter from entering the bearing space SP and the release of dust, seal wear powder, etc. from the bearing space SP. In the present embodiment, both axial sides of the bearing space SP are closed by the seal members 6. The seal members 6 are attached to the inner peripheral surface of the outer ring 3, which is a fixed ring.

[0019] Each seal member 6 is a contact seal in which a main lip 15 contacts a seal groove 7. The seal groove 7 is formed on the outer peripheral surface of the inner ring 2. The seal groove 7 is formed at both axial ends on the outer peripheral surface of the inner ring 2 and extends in the circumferential direction.

[0020] Seal member fixing grooves 9 are provided in portions of the inner peripheral surface of the outer ring 3 that face the seal grooves �. The seal member fixing grooves 9 are also formed at both axial ends on the inner peripheral surface of the outer ring 3 and extend in the circumferential direction.

[0021] The sealing member 6 has a core metal 10 and a rubber material 11 molded onto it. The outer edge of this sealing member 6 is fitted into the sealing member fixing groove 9 of the outer ring 3 and fixed in place. In Figure 1, a portion of the outer circumference of the sealing member 6 is shown as being embedded in the outer ring 3, but this portion is an overlap and is actually fitted into the sealing member fixing groove 9 in an elastically deformed state. Also, a portion of the main lip 15 of the sealing member 6 is shown as being embedded in the inner ring 3, but this portion is an overlap and is actually in contact with the sealing groove 7 in an elastically deformed state.

[0022] The seal groove 7 of the inner ring 2 has, in order from 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 is connected to the outer circumferential surface 2b of the inner ring 2, which is the inner ring shoulder provided on both axial sides of the raceway surface 2a, and is inclined toward the inner diameter when moving axially outward.

[0023] The groove bottom surface 7b smoothly connects to the inner groove wall surface 7a and extends substantially parallel to the axial direction. The outer groove wall surface 7c smoothly connects to the groove bottom surface 7b and inclined toward the outer diameter side toward the axial outward direction. The outer groove wall surface 7c is connected to the outer diameter surface 2c of the axial end of the inner ring 2. In this embodiment, the outer diameter surface 2c of the axial end of the inner ring 2 is connected 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 of the axial end of the inner ring 2 coincides with the radial dimension of the axial end surface 2d of the inner ring 2.

[0024] As shown in Figure 2, the inner circumferential portion 13 of the sealing member 6 that extends radially inward beyond the inner diameter of the core metal 10 is made of the rubber material 11 described above. The material of the rubber material 11 is, for example, nitrile rubber, but other materials such as acrylic rubber, silicone rubber, or fluororubber may be used depending on the operating temperature.

[0025] The inner circumferential portion 13 of the sealing 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 molded by die molding. The wall thickness of the constricted portion 14 gradually decreases from the outer diameter end of the inner circumferential portion 13 toward the inner diameter.

[0026] The main lip 15 and the sub-lip 16 are connected to the constricted portion 14. The main lip 15 is connected to the inner diameter end of the constricted portion 14, and the sub-lip 16 protrudes axially inward from the inner surface portion of the base end 15a of the main lip 15. As shown in Figure 1, a labyrinth seal Rs is formed between the tip of the sub-lip 16 and the inner groove wall surface 7a of the seal groove 7.

[0027] As shown in Figure 2, the main lip 15 has a base portion 15a, a lip body portion 15b, and a lip tip portion 15c. The base portion 15a extends radially inward from the constricted portion 14, inclined axially outward. The lip body portion 15b extends radially inward from the base portion 15a. The lip tip portion 15c is provided on the outer surface portion of the tip side of the lip body portion 15b. More specifically, the lip tip portion 15c extends radially inward from the tip of the lip body portion 15b, inclined axially outward.

[0028] The tip of the main lip 15, specifically the tip portion 15c, is formed in an R shape and contacts the outer groove wall surface 7c of the seal groove 7 in a direction normal to it. The outer diameter surface 15ca of the tip portion 15c of the main lip 15 is inclined radially inward toward the axially outward direction and smoothly connects to the aforementioned R shape.

[0029] The lip body portion 15b has a sealing surface 20 facing axially outward (opposite to the bearing space SP) and a sealing back surface 22 facing axially inward (towards the bearing space SP). The radial dimension B of the tip 22a of the sealing back surface 22 of the lip body portion 15b, i.e., the radial inner end 22a, is set to be larger than the outer diameter dimension A of the end face 2d of the inner ring 2 (B>A).

[0030] 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 to be larger than the outer diameter dimension A of the outer diameter surface 2c at the axial end of the inner ring 2.

[0031] When the seal member 6 is fitted into the seal groove 7 of the inner ring 2, the tip 15c of the main lip 15 needs to overcome 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 constitutes the inner diameter surface 24 of the seal inlet when the seal member 6 is fitted. Therefore, in other words, the radial dimension B of the tip 22a of the back surface 22 of the seal is set to be larger than the diameter A of the inner diameter surface 24 of the seal inlet.

[0032] In this embodiment, the sealing surface 20 of the lip body portion 15b is parallel to the radial direction of the bearing (the radial axis AX shown by the dashed line in Figure 2). However, the sealing surface 20 may extend radially outward from the tip 20a with respect to the radial axis AX, inclined axially outward.

[0033] In other words, if L1 is the virtual extension of the sealing surface 20 that is inclined with respect to the radial axis AX, then in this disclosure, the angle θ of the sealing surface 20 with respect to the radial axis AX is set to 0° or greater. Here, when the angle θ is 0°, the sealing surface 20 is parallel to the radial axis AX. When the angle θ is greater than 0°, i.e., a positive value, the sealing surface 20 is inclined axially outward with respect to the radial axis AX. When the angle θ is less than 0°, i.e., a negative value, the sealing surface 20 is inclined axially inward with respect to the radial axis AX.

[0034] As will be described later in Figures 3A to 3C, the sealing surface 20 of the lip body portion 15b is the surface that comes into contact with the insertion jig T when the sealing member 6 is assembled into the sealing groove 7 of the inner ring 2. In other words, in this disclosure, the angle θ of the sealing surface 20 of the lip body portion 15b that comes into contact with the insertion jig T with respect to the radial axis AX is set to 0° or more.

[0035] Let P1 be the radial position of the radial midpoint on the sealing surface 20 of the lip body portion 15b. Specifically, "radial position P1" is the radial midpoint between the radial inner end and the radial outer end on the sealing surface 20 of the lip body portion 15b. Also, let C be the thickness dimension of the lip tip portion 15c in its natural state. Here, the natural state refers to the state in which the seal tip portion 15c does not contact the seal groove 7, for example, the state before the seal member 6 shown in Figure 3A is assembled into the bearing 1. Furthermore, let P2 be the radial position obtained by adding the 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. In this embodiment, the radial position P1 is located radially outward from the radial position P2.

[0036] However, the positional relationship between the sealing surface 20 and the radial position P2 is not limited to this. Specifically, as shown in Figure 3C, when the sealing member 6 is assembled into the sealing groove 7 of the inner ring 2, the innermost radial position P3 of the portion of the sealing surface 20 that contacts the insertion jig T should be located radially outward from the radial position P2, which is the sum of the outer diameter dimension A of the end face 2d of the inner ring 2 plus the thickness dimension C of the lip tip 15c. In other words, the jig T should contact the sealing surface 20 at a position where there is a radial gap of the thickness dimension C of the lip tip 15c from the outer edge of the end face 2d of the inner ring 2.

[0037] <Regarding the assembly of sealing components> The assembly process of the sealing member 6 of this embodiment will be explained below using Figures 3A, 3B, and 3C. First, the assembly process of the conventional sealing member 106 will be explained using Figures 4A, 4B, and 4C. The arrows F in Figures 3A-3C and 4A-4C represent the force acting on the sealing surfaces 20 and 120 of the sealing members 6 and 106 when they are pressed into the sealing grooves 7 of the inner ring 2.

[0038] As shown in FIG. 4A, in the conventional seal member 106, the radial dimension B1 of the tip 122a of the seal back surface 122 in the lip body portion 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). Therefore, when inserting the seal member 106 into the bearing 1, as shown in FIG. 4B, the back surface 122 side of the lip body portion 115b contacts the end face 2d of the inner ring 2. When the seal member 106 is pushed in this state, as shown in FIG. 4C, it is pushed in while rotating so that the lip tip portion 115c faces the outer ring 2 side.

[0039] Since the main lip 115 is in a shape that axially contacts the seal groove 7 of the inner ring 2 on the outer side, simply pushing in the outer diameter side of the seal member 106 does not cause the main lip 115 to enter the seal groove 7. Therefore, it is necessary to push in the vicinity of the main lip 115 with the jig T. At this time, if the pushing amount is inappropriate, the main lip 115 will not enter the seal groove 7, resulting in a poor assembly.

[0040] On the other hand, if it is pushed in too much, as shown in FIG. 5, the main lip 115 may buckle. In FIG. 5, the region where the main lip 115 may buckle is indicated by R1. Also, depending on the contact position between the insertion jig T and the seal surface 120, the lip tip portion 115c may contact the jig T, and defects may occur in the lip tip portion 115c. In FIG. 5, the region where defects may occur in the lip tip portion 115c is indicated by R2.

[0041] In the present embodiment, as shown in FIG. 3A, the radial dimension B of the tip 22a of the seal back surface 22 of the lip body portion 15b is set larger than the outer diameter dimension A of the end face 2d of the inner ring 2 (B > A). Further, as shown in FIG. 2, the seal surface 20 of the lip body portion 15b is parallel to the radial axis AX or inclined axially outward with respect to the radial axis AX.

[0042] As a result, as shown in Figure 3B, the main lip 15 can more easily overcome the end face 2d of the inner ring 2. Also, as shown in Figure 3C, the contact between the sealing surface 20 and the jig T makes it easier for the main lip 15 to bend inward in the axial direction, thus improving the insertability of the main lip 15. As a result, the main lip 15 can be inserted without problems such as buckling.

[0043] Furthermore, the innermost radial position P3 of the portion of the sealing surface 20 that contacts the insertion jig T is located radially outward from 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 15c. This makes it difficult for the lip tip 15c that has passed over the end face 2d of the inner ring 2 to be pinched by the jig T. In this way, the lip tip 15c of the main lip 15 and the insertion jig T do not interfere with each other, so the sealing member 6 can be inserted without the lip tip 15c wearing down. As a result, the sealing performance of the sealing member 6 after installation is ensured.

[0044] As described above, in this embodiment, even if the seal member 6 has a seal shape that contacts the axially outer side of the seal groove 7 of the inner ring 2, the seal member 6 can be mounted on the bearing 1 without problems such as improper assembly, buckling of the main lip 115, or defects in the lip tip portion 15c.

[0045] With the above configuration, as shown in Figure 2, the radial dimension B of the tip 22a on the seal back surface 22 of the lip body 15b is set to be larger than the outer diameter dimension A of the end face 2d of the inner ring 2 (B>A). As a result, as shown in Figure 3B, the main lip 15 can easily overcome the end face 2d of the inner ring 2 which constitutes the entrance to the seal member 6. Consequently, the ease of assembling the seal member 6 to the bearing 1 is improved.

[0046] In this embodiment, as shown in Figure 2, the sealing surface 20 of the lip body 15b is either parallel to the radial direction (radial axis AX) of the bearing 1, or it extends radially outward from the tip 20a, inclined toward the opposite side of the bearing space (axially outward). With this configuration, as shown in Figure 3B, when assembling the sealing member 6 to the bearing 1, the sealing surface comes into contact with the jig, making it easier for the main lip to bend axially inward (towards the inside of the bearing). Therefore, the ease of assembling the sealing member 6 to the bearing 1 is improved.

[0047] In this embodiment, as shown in Figure 2, the radial position P1 of the radial midpoint of the sealing surface 20 of the lip body portion 15b is located radially outward from 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. With this configuration, as shown in Figure 3C, the lip tip portion 15c of the main lip 15 that has passed over the end face 2d of the inner ring 2 is less likely to be caught in the jig T that contacts the sealing surface 20. This prevents defects from occurring in the lip tip portion 15c of the main lip 15.

[0048] The present invention is not limited to the embodiments described above, and various additions, modifications, or deletions are possible without departing from the spirit of the invention. For example, in the above embodiments, balls 4 were used as rolling elements, but the invention is not limited to this. Also, in the above embodiments, sealing members 6 were provided on both axial sides of the bearing space SP, but they may be provided on only one side. Therefore, such configurations are also included within the scope of the present invention. [Explanation of symbols]

[0049] 1 Rolling bearing 2 Inner ring 3 Outer ring 4 Balls (rolling elements) 6. Sealing component (contact seal) 7. Seal groove 15 Main Lip 15b Lip body 15c Lip tip 20 sealing surface 22 Sticker back A. Outer diameter dimension of the end face of the inner ring (outer diameter of the seal groove inlet) B Radial dimension of the tip of the back of the seal C. Thickness dimension of the lip tip P1 Radial position of the midpoint of the radial direction of the sealing 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

Claims

1. It comprises an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a sealing member. The inner ring, the outer ring, and the sealing member form a bearing space. A sealing groove is formed in the circumferential direction on the outer surface of the inner ring. The sealing member is a contact seal in a rolling bearing, attached to the outer ring at its base end, which is the outer edge, and having its tip end, which is the inner edge, in contact with the seal groove. The sealing member has a main lip at its tip, The main lip has a lip body portion extending in the radial direction and a lip tip portion extending from the tip of the lip body portion, inclined axially outward toward the radially inward direction. The tip of the lip contacts the seal groove, A rolling bearing in which the radial dimension B of the tip on the axially inward back surface of the seal of the lip body is greater than the outer diameter A of the end face of the inner ring.

2. A rolling bearing according to claim 1, wherein the axially outer sealing surface of the lip body portion is parallel to the radial direction of the bearing, or extends radially outward from the tip and is inclined axially outward.

3. A rolling bearing according to claim 1 or 2, wherein the radial position P1 of the radial midpoint between the radial inner end and the radial outer end of the axially outer sealing surface of the lip body is located radially outward from the radial position P2 obtained by adding the thickness dimension C of the lip tip in its natural state to the outer diameter dimension A of the end face of the inner ring.

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