Rolling bearing

Abstract

[Problem] To provide a rolling bearing capable of preventing a seal member from warping. [Solution] A ball bearing 1 comprises: an outer ring 100; an inner ring 120 disposed facing the outer ring 100; a plurality of balls 130 disposed between the outer ring 100 and the inner ring 120; and a resin seal member 140 attached to the outer ring 100 and covering a space between the outer ring and the inner ring. The outer ring 100 includes: a raceway groove 101 in which the balls 130 roll; a peripheral groove 110 provided axially outside the raceway groove 101; and a shoulder part 115 provided axially outside the peripheral groove 110 and projecting to the inner ring 120 side. The seal member 140 includes: a head part 146 engaging with the peripheral groove 110; and a step part 150 provided axially outside the head part 146 and closer to the inner ring 120 than the head part 146. The step part 150 includes a step surface 151 abutting on the shoulder part 115 in a radial direction.

Description

Rolling bearings

[0001] The present invention relates to a rolling bearing having an improved resin seal member mounted between an outer ring and an inner ring.

[0002] Generally, rolling bearings are fitted with seals to prevent leakage of grease filled in the raceway grooves and to prevent the intrusion of water and dust from the outside. One example of a seal is a ring-shaped resin seal, with its outer periphery fitted into a circumferential groove formed in the outer ring, for example, and its inner periphery held close to the inner ring. An example of a rolling bearing fitted with such a seal is disclosed in Patent Document 1.

[0003] Japanese Patent Application Publication No. 8-135668

[0004] When a seal member is fitted into the circumferential groove of the outer ring, pressure from the circumferential groove acts on the outer periphery of the seal member, which can cause the inner periphery to warp axially outward. When the rolling bearing rotates and heats up, the seal member thermally expands, causing further warping. Warping of the inner periphery of the seal member not only increases the gap with the inner ring, impairing its function as a seal member, but also risks the seal member protruding from the end face of the rolling bearing and interfering with other components.

[0005] The present invention has been made to solve the problems associated with conventional rolling bearings as described above, and has an object to provide a rolling bearing that can prevent warping of the seal member.

[0006] The present invention is a rolling bearing comprising a first raceway, a second raceway arranged opposite the first raceway, a plurality of rolling elements arranged between the first raceway and the second raceway, and a sealing member made of resin attached to the first raceway and covering the space between the first raceway and the second raceway, wherein the first raceway has a raceway groove in which the rolling elements roll, a circumferential groove provided axially outward from the raceway groove, and a shoulder provided axially outward from the circumferential groove and protruding toward the second raceway, and the sealing member has a head that engages with the circumferential groove and a step provided axially outward from the head and toward the second raceway, and the step has a stepped surface that abuts radially against the shoulder.

[0007] According to the present invention, the stepped surface abuts against the shoulder of the first bearing ring in the radial direction, so that even if the head tries to rotate, it is blocked by the shoulder, and warping of the seal member can be prevented.

[0008] 2A is a cross-sectional view showing a ball bearing according to an embodiment of the present invention, and FIG. 2B is an enlarged view of a portion indicated by an arrow B in FIG. 2A. FIG. 2B is a cross-sectional view showing an enlarged main portion of a seal member in the embodiment.

[0009] 1. Ball Bearing Configuration A ball bearing according to an embodiment of the present invention will be described. Figure 1 is a cross-sectional view showing a ball bearing 1 according to the embodiment. In the following description, the direction of the centerline of the ball bearing 1 will be referred to as the "axial direction," and the direction perpendicular to the axial direction will be referred to as the "radial direction." Furthermore, the direction of rotation around the axial direction will be referred to as the "circumferential direction."

[0010] 1, the ball bearing 1 is generally composed of an outer ring (first raceway) 100, an inner ring 120 (second raceway) disposed opposite the outer ring 100, a plurality of balls (rolling elements) 130 disposed between the outer ring 100 and the inner ring 120, a seal member 140 attached to the outer ring 100 to seal the gap between the outer ring 100 and the inner ring 120, and a cage 160 that holds the balls 130 at equal intervals in the circumferential direction. Each of the components will be described in detail below.

[0011] The outer ring 100 is annular and made of, for example, bearing steel, and has a raceway groove 101 with an arc-shaped cross section formed around the entire circumference on its inner peripheral surface. Axially outward from the raceway groove 101, a chamfered portion 102 is formed which widens outward in the axial direction.

[0012] A circumferential groove 110 is formed in the chamfered portion 102, recessed radially outward from the axially outer end. The circumferential groove 110 has a circular surface 113 with an arc-shaped cross section extending from an inner end 111 on the axial and radial inner side to an outer end 112 on the axial and radial outer side. A tapered surface 114 with a linear cross section whose diameter decreases axially outward is formed axially outward from the outer end 112. An inner surface 116 is formed radially inward from the inner end 111. The portion from the inner surface 116 to the tapered surface 114 constitutes the circumferential groove 110. A shoulder 115 substantially parallel to the axial direction is formed axially outward from the tapered surface 114. In this embodiment, the inner surface 116 is slightly inclined axially inward with respect to the radial direction, but the inner surface 116 may also be substantially parallel to the radial direction.

[0013] 2 is a cross-sectional view showing details of the seal member 140. The seal member 140 is formed in an annular shape from a resin selected from the group consisting of aliphatic polyamides such as nylon 66 and nylon 46, semi-aromatic polyamides such as PA4T, PA6T, PA9T, and PA10T, polyimide resins such as polyamideimide and polyimide, polyarylether resins such as polyether ether ketone, aromatic-containing polyester resins such as polybutylene terephthalate, fluorine-containing resins such as polytetrafluoroethylene, sulfur-containing novolac resins such as polyphenylene sulfide, and polyolefin resins such as polyethylene and polypropylene. The seal member 140 includes an annular portion 141 having a uniform thickness in the radial direction. As shown in FIG. 1A , a first ridge 142 projecting axially inward is formed on the radially inner side of the annular portion 141, and a flange portion 143 is formed on the radially inner side of the first ridge 142.

[0014] Meanwhile, a second ridge (ridge) 144 that protrudes axially inward is formed on the radially outer side of the annular portion 141, and an annular groove 145 that has a generally V-shaped cross section and is recessed axially outward is formed on the radially outer side of the second ridge 144. A head 146 is formed radially outward of the annular groove 145. The seal member 140 is made of an elastic resin, and the head 146 can be elastically deformed radially inward at the portion of the annular groove 145. A flat end surface 147 that is generally parallel to the radial direction is formed on the head 146 at a location adjacent to the annular groove 145. The flat end surface 147 has a small gap with respect to the inner surface 116.

[0015] The head 146 has a circular surface 148 with an arc-shaped cross section extending from an inner end 146a located at the end of the flat end surface 147 to an outer end 146b on the axial and radial outer side. This circular surface 148 matches the shape of the circular surface 113 of the circumferential groove 110 and is in close contact with the circular surface 113. An inclined surface 149 with a linear cross section whose diameter decreases as it extends axially outward is formed on the axially outer side of the outer end 146b. A step 150 recessed radially inward is formed on the axially outer side of the inclined surface 149.

[0016] The step portion 150 is formed by a step surface 151, which is an outer peripheral surface substantially parallel to the axial direction, and a tapered surface 151a that faces axially outward and whose diameter decreases as it approaches axially inward. The step portion 150 is provided axially outward of the head 146 and on the side of the inner ring 120, which is the second raceway ring. The step surface 151 of the step portion 150 abuts against the shoulder portion 115 of the outer ring 100 in the radial direction.

[0017] Next, inner ring 120 is annular and made of, for example, bearing steel, and has raceway grooves 121 with an arc-shaped cross section formed around its entire circumference on its outer surface. A chamfered portion 122 that widens axially outward is formed axially outward from raceway groove 121. A recessed portion 123 that is recessed radially inward is formed axially outward from chamfered portion 122. A plurality of balls 130 are held between raceway groove 121 and raceway groove 101 of outer ring 100 at equal intervals in the circumferential direction by a cage 160 made of resin or metal.

[0018] 2. Operation The seal member 140 configured as described above is installed in the circumferential groove 110 of the outer ring 100. When installing, the head 146 of the seal member 140 is elastically deformed radially inward at the annular groove 145, and the seal member 140 is fitted into the circumferential groove 110. As a result, the seal member 140 is held and fixed to the outer ring 100 and lies between the outer ring 100 and the inner ring 120. In this state, the inner circumferential surface of the flange portion 143 of the seal member 140 is positioned adjacent to the recess 123 of the inner ring 120, and the first ridge 142 of the seal member 140 is positioned adjacent to the chamfered portion 122 of the inner ring 120. A labyrinth structure is formed in this way, which prevents leakage of grease filled between the outer ring 100 and the inner ring 120 and prevents the intrusion of water and dust from the outside.

[0019] 3. Effects When the seal member 140 is attached to the circumferential groove 110 of the outer ring 100, as shown in FIG. 1(B), the relationship between the various parts around the head 146 of the seal member 140 and the various parts around the circumferential groove 110 is as follows.

[0020] (1) The inner end 146a of the head 146 abuts against the inner end 111 of the circumferential groove 110. (2) The circular surface 148 of the head 146 is in close contact with the circular surface 113 of the circumferential groove 110. (3) The outer end 146b of the head 146 abuts against the outer end 112 of the circumferential groove 110. (4) The inclined surface 149 of the head 146 abuts against the tapered surface 114 of the circumferential groove 110. (5) The stepped surface 151 adjacent to the head 146 abuts against the shoulder 115 adjacent to the circumferential groove 110.

[0021] In this manner, in the ball bearing 1 configured as described above, the head 146 of the seal member 140 is engaged with and supported in the circumferential groove 110 due to the above-described (1) to (4). Here, even if a moment acts on the head 146 due to stress from the circumferential groove 110, causing the head 146 to rotate, the shoulder 115 presses the stepped surface 151, preventing the head 146 from rotating. Therefore, warping of the seal member 140 is prevented. The stepped surface 151 is located closer to the inner ring 120, which is a raceway ring without the circumferential groove 110 (inward in the radial direction), than the radially outer end (upper end in FIG. 1 ) of the head 146. This effectively prevents the head 146 from rotating. That is, the flange 143 of the seal member 140 is prevented from displacing axially outward. The stepped surface 151 and the shoulder 115 may be in substantial point contact in cross-sectional view. In this case, the same effect of preventing the seal member 140 from warping as described above can be obtained.

[0022] In addition, in the above embodiment, the contour of the circular surface portion 148 of the head portion 146 matches the circular surface portion 113 of the circumferential groove 110, so the two are in close contact with each other, and the sealing member 140 can be firmly held in the circumferential groove 110.

[0023] Furthermore, since the inclined surface 149 of the head 146 is in contact with the tapered surface 114 of the circumferential groove 110, even if the head 146 tries to rotate, the inclined surface 149 is pressed against the tapered surface 114, and the rotation of the head 146 is more effectively prevented.

[0024] 4. Modifications The present invention is not limited to the above embodiment, and various modifications are possible as follows: i) In the above embodiment, the circumferential groove 110 is formed in the outer ring 100, but it may be formed in the inner ring 120. In this case, the head 146 is formed on the inner ring 120 side of the seal member 140.

[0025] ii) In the above embodiment, the head 146 is formed with a circular surface 148 that has the same contour as the circular surface 113 of the circumferential groove 110, but this configuration is not limited thereto. For example, as shown in FIG. 3 , instead of the circular surface 148, an inclined surface 148a can be formed extending from the inner end 146a to the outer end 146b. Even with this configuration, the head 146 is firmly supported by the circumferential groove 110, the tapered surface 114, and the shoulder 115 at three points: the inner end 146a, the inclined surface 149, and the stepped surface 151. In other words, it is sufficient that the head 146 is supported at three points, including the stepped surface 151. The stepped surface 151 does not have to be parallel to the axial direction. Even if the stepped surface 151 is not parallel to the axial direction, a structure in which the head 146 is firmly held to the outer ring 100 can be obtained.

[0026] iii) The present invention is not limited to ball bearings as in the above embodiment, but can be applied to all rolling bearings such as roller bearings.

[0027] DESCRIPTION OF SYMBOLS 1...ball bearing, 100...outer ring (first raceway ring), 101...raceway groove, 102...chamfered portion, 110...circumferential groove, 111...inner end portion, 112...outer end portion, 113...circular surface portion, 114...tapered surface, 115...shoulder portion, 116...inner surface, 120...inner ring (second raceway ring), 121...raceway groove, 122...chamfered portion, 123...recess, 130...ball (rolling element), 140... Sealing member, 141...annular portion, 142...first ridge, 143...flange portion, 144...second ridge (ridge), 145...annular groove, 146...head, 147...flat end surface, 146a...inner end, 146b...outer end, 148...circular surface portion, 149...inclined surface, 150...step portion, 151...step surface, 151a...tapered surface, 152...inclined surface, 160...retainer.

Claims

1. A rolling bearing comprising: a first raceway ring; a second raceway ring arranged opposite the first raceway ring; a plurality of rolling elements arranged between the first raceway ring and the second raceway ring; and a sealing member made of resin attached to the first raceway ring and covering the space between the first raceway ring and the second raceway ring, wherein the first raceway ring comprises: raceway grooves in which the rolling elements roll; a circumferential groove provided axially outward from the raceway groove; and a shoulder provided axially outward from the circumferential groove and protruding towards the second raceway ring, and the sealing member comprises: a head portion that engages with the circumferential groove; and a step portion provided axially outward from the head portion and on the second raceway ring side, and the step portion has a stepped surface that abuts the shoulder portion in the radial direction.

2. A rolling bearing according to claim 1, wherein at least the outer end and inner end of said head in the axial direction are in contact with said circumferential groove.

3. A rolling bearing according to claim 2, wherein the cross-sectional contour from said outer end to said inner end coincides with the cross-sectional contour of said circumferential groove.

4. A rolling bearing according to claim 2, wherein a cross-sectionally linearly inclined surface is formed between the outer end and the inner end, the diameter of which decreases axially inward.

5. A rolling bearing as set forth in claim 2 or 3, wherein a cross-sectionally linear inclined surface whose diameter decreases as it extends axially outward is formed on the axially outer side of the outer end, and the circumferential groove is formed with a tapered surface against which the inclined surface abuts.

6. A rolling bearing according to claim 2 or 3, wherein a flat end surface facing the axial direction is formed on the radially inner side of said inner end portion, said flat end surface being spaced apart from said circumferential groove.

7. A rolling bearing according to claim 1 or 2, wherein a ridge protruding axially inward is provided on the radially inner side of the head, and an annular groove recessed axially outward is provided between the ridge and the head.

8. A rolling bearing according to claim 7, wherein the head of the sealing member is capable of elastic deformation in a radially inward direction at the portion of the annular groove.

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