Rolling bearing

Abstract

An outer ring 100 is provided with a raceway groove 101 in which balls 130 roll, a peripheral groove 110 provided axially outside of the raceway groove 101, an outer shoulder part 114 that is provided axially outside of the peripheral groove 110 and protrudes toward an inner-ring 120 side, and an inner shoulder part 117 provided axially inside of the peripheral groove 110. A seal member 140 is provided with a first annular part 141 extending in the radial direction, a second annular part 145 that is disposed radially outside and axially inside of the first annular part 141 and extends in the radial direction, a connection part 144 that connects the first annular part 141 and the second annular part 145 to each other, and a distal-end part 146 extending outward in the axial direction from the radially outer edge part of the second annular part 145. The distal-end part 146 is elastically deformed inward in the radial direction by the outer shoulder part 114, whereby the second annular part 145 is pressed to the inner shoulder part 117.

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 provides a bearing comprising a first raceway ring, a second raceway ring disposed opposite the first raceway ring, a plurality of rolling elements disposed between the first raceway ring and the second raceway ring, and a seal member made of resin attached to the first raceway ring and covering the gap between the first raceway ring and the second raceway ring, wherein the first raceway ring has raceway grooves in which the rolling elements roll, a circumferential groove provided axially outward of the raceway groove, an outer shoulder provided axially outward of the circumferential groove and protruding toward the second raceway ring, and a seal member made of resin attached to the first raceway ring and covering the gap between the first raceway ring and the second raceway ring, and an inner shoulder provided on the sealing member, wherein the sealing member comprises a first annular portion extending radially, a second annular portion positioned radially outward and axially inward from the first annular portion and extending radially, a connecting portion connecting the first annular portion and the second annular portion, and a tip portion extending axially outward from the radially outer edge portion of the second annular portion, wherein the tip portion is elastically deformed radially inward by the outer shoulder, thereby pressing the second annular portion against the inner shoulder.

[0007] According to the present invention, the spring force generated by the elastic deformation of the tip portion applies a moment to the second annular portion in the direction opposite to the direction in which the sealing member warps, thereby preventing the sealing member from warping.

[0008] (A) is a cross-sectional view showing a ball bearing according to a first embodiment of the present invention, and (B) is an enlarged view of the portion indicated by arrow B in (A). (A) is a cross-sectional view of a seal member in the first embodiment, and (B) is a modified example of (A). (B) is a cross-sectional view showing an angle in FIG. 1(B). (C) is a cross-sectional view showing a seal member according to a second embodiment of the present invention. (D) is a cross-sectional view showing a seal member according to a third embodiment of the present invention.

[0009] 1. First Embodiment (1) Ball Bearing Configuration A ball bearing according to a first embodiment of the present invention will be described. Fig. 1 is a cross-sectional view showing a ball bearing 1 according to the first 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 on the axially outer side of the chamfered portion 102, recessed radially outward. The circumferential groove 110 has a circular surface 113 with an arc-shaped cross section from an inner end 111 on the axially and radially inner side to an outer end 112 on the axially and radially outer side. An outer shoulder 114 is formed axially outward of the outer end 112, protruding radially inward. The inner circumferential surface of the outer shoulder 114 is formed with an inclined surface 115 with a linear cross section whose diameter decreases axially outward. A cylindrical surface 116 is formed axially outward of the inclined surface 115. Meanwhile, an inner shoulder 117 is formed in a portion of the circumferential groove 110 extending radially inward from the inner end 111. In this embodiment, the inner shoulder 117 is substantially parallel to the radial direction, but may be inclined relative to the radial direction. The portion from the inner shoulder 117 to the inclined surface 115 constitutes the circumferential groove 110.

[0013] 2A 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 polyester resins such as polybutylene terephthalate, fluorine-based 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 a first annular portion 141 having a uniform thickness along the radial direction. A protrusion 142 protruding axially inward is formed on the radially inner side of the first annular portion 141, and a flange portion 143 is formed on the radially inner side of the protrusion 142.

[0014] A connecting portion 144 is formed radially outward from the first annular portion 141, inclined axially inward relative to the first annular portion 141. As shown in FIG. 1B , the connecting portion 144 is disposed radially closer to the inner ring 120 than the inner shoulder portion 117. A second annular portion 145 is formed radially outward from the connecting portion 144, and is generally parallel to the radial direction. The second annular portion 145 is formed so that its thickness decreases from the end on the connecting portion 144 side toward the radially outward side. A tip portion 146 is formed at the radially outer end of the second annular portion 145, and extends generally parallel to the axial direction. The tip portion 146 has a constant thickness throughout its entire length.

[0015] 3, if the angle α is the angle that the inclined surface 115 makes with respect to the radial direction and the angle β is the angle that the contact surface 147 of the tip end portion 146 that contacts the inclined surface 115 makes with respect to the radial direction in an unloaded state, the angle α is smaller than the angle β. Therefore, when the seal member 140 is installed in the circumferential groove 110, the tip end portion 146 elastically deforms by an angle (β-α). This generates a spring force, pressing the second annular portion 145 against the inner shoulder portion 117. The difference between the angle β and the angle α is 1 to 60°, preferably 10 to 60°, and more preferably 20 to 50°.

[0016] 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 at equal intervals between raceway groove 121 and raceway groove 101 of outer ring 100 by a cage 160 made of resin or metal.

[0017] (2) Operation The seal member 140 configured as described above is fitted into the circumferential groove 110 of the outer ring 100. When fitting, the seal member 140 is pushed into the opening of the outer ring 100, causing the connecting portion 144 and the second annular portion 145 to elastically deform so as to bend axially outward and pass through the outer shoulder portion 114 of the outer ring 100. The boundary between the second annular portion 145 and the tip portion 146 is then received in the circumferential groove 110, and the tip portion 146 is pressed against the inclined surface 115 of the outer shoulder 114, remaining elastically deformed, and the resulting spring force presses the second annular portion 145 against the inner shoulder portion 117.

[0018] As a result, seal member 140 lies between outer ring 100 and inner ring 120. In this state, the inner circumferential surface of flange portion 143 of seal member 140 is positioned adjacent to recessed portion 123 of inner ring 120, and ridge 142 of seal member 140 is positioned adjacent to chamfered portion 122 of inner ring 120. A labyrinth structure is formed in this way, which prevents leakage of grease filled between outer ring 100 and inner ring 120 and prevents water and dust from entering from the outside.

[0019] (3) Effect In the ball bearing 1 having the above configuration, the spring force generated when the tip portion 146 is elastically deformed by the outer shoulder portion 114 of the outer ring 100 applies a moment to the second annular portion 145 in the direction opposite to the direction in which the sealing member 140 warps, thereby preventing the sealing member from warping.

[0020] In particular, in the first embodiment, the second annular portion 145 is formed so that its thickness decreases from the end portion on the connecting portion 144 side toward the radially outer side. That is, the thickness of the second annular portion 145 increases from the tip end portion 146 side toward the connecting portion 144 side. As a result, the end portion of the second annular portion 145 on the connecting portion 144 side is thicker and more rigid. This suppresses elastic deformation of the second annular portion 145 and also prevents warping due to centrifugal force generated when the outer ring 100 rotates at high speed. Note that, in the present invention, the second annular portion 145a may have a constant thickness in the radial direction, as shown in FIG. 2(B).

[0021] Here, if the elastic deformation of the tip portion 146 is too small, the moment applied to the second annular portion 145 is insufficient, making it impossible to prevent warping of the seal member 140. Conversely, if the elastic deformation of the tip portion 146 is too large, the spring force may be too strong, causing the tip portion 146 and the second annular portion 145 to jump out of the circumferential groove 110. In this regard, according to the first embodiment, the tip portion 146 is elastically deformed by setting the angle α that the inclined surface 115 makes with respect to the radial direction to be smaller than the angle β that the contact surface 147 of the tip portion 146 makes with respect to the radial direction in an unloaded state. Therefore, by appropriately setting the angles α and β, the elastic deformation of the tip portion 146 can be optimized.

[0022] (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 that case, the connecting portion 144, the second annular portion 145, and the tip portion 146 are formed on the inner ring 120 side of the seal member 140.

[0023] ii) The present invention is not limited to the ball bearing 1 of the above embodiment, but can be applied to all rolling bearings such as roller bearings.

[0024] 2. Second Embodiment FIG. 4A shows a seal member 140a according to a second embodiment of the present invention. In this seal member 140a, the angle β of the tip end 146a relative to the radial direction is set to an obtuse angle. In this case, the angle α of the inclined surface 115 of the circumferential groove 110, which contacts the tip end 146a, relative to the radial direction is set to be larger than the angle α shown in FIG. 3. For example, the angle α is set to an obtuse angle of 90° or greater. This second embodiment also achieves the same functions and effects as the first embodiment. As shown in FIG. 4B, the thickness of the second annular portion 145a of the seal member 140b can also be constant in the radial direction.

[0025] 3. Third Embodiment FIG. 5A shows a seal member 140c according to a third embodiment of the present invention. In this seal member 140c, the angle β of the tip end 146b relative to the radial direction is set to an acute angle. In this case, the angle α of the inclined surface 115 of the circumferential groove 110, which contacts the tip end 146a, relative to the radial direction is set to be smaller than the angle α shown in FIG. 3. This third embodiment also achieves the same functions and effects as the first embodiment. Note that, as shown in FIG. 5B, the thickness of the second annular portion 145a of the seal member 140d can also be constant in the radial direction.

[0026] 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...outer shoulder portion, 115...inclined surface, 116...cylindrical surface, 117...inner shoulder portion, 120...inner ring (second raceway ring), 121...raceway groove, 122...chamfered portion, 123...recess, 130...ball (rolling element), 140, 140a, 140b, 140c, 140d...sealing member, 141...first annular portion, 142...ridge, 143...flange portion, 144...connecting portion, 145, 145a...second annular portion, 146, 146a, 146b...tip portion, 147...contact surface, 160...retainer.

Claims

1. A bearing comprising: a first raceway ring; a second raceway ring disposed opposite the first raceway ring; a plurality of rolling elements disposed 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 disposed axially outward from the raceway groove; an outer shoulder disposed axially outward from the circumferential groove and protruding toward the second raceway ring; and an inner shoulder disposed axially inward from the circumferential groove, and the sealing member comprises: a first annular portion extending radially; a second annular portion disposed radially outward and axially inward from the first annular portion and extending radially; a connecting portion connecting the first annular portion and the second annular portion; and a tip portion extending axially outward from the radially outer edge portion of the second annular portion, The tip end portion is elastically deformed radially inward by the outer shoulder portion, thereby pressing the second annular portion against the inner shoulder portion.

2. A rolling bearing as set forth in claim 1, wherein the outer shoulder portion has an inclined surface whose diameter decreases as it extends axially outward, the tip portion is elastically deformed by the inclined surface, and the angle α that the inclined surface makes with the radial direction is smaller than the angle β that the contact surface of the tip portion that comes into contact with the inclined surface makes with the radial direction in an unloaded state.

3. A rolling bearing according to claim 2, wherein the difference between the angle α and the angle β is 1 to 60°.

4. A rolling bearing according to claim 3, wherein the difference between the angle α and the angle β is 10 to 60°.

5. A rolling bearing according to claim 4, wherein the difference between the angles α and β is 20 to 50°.

6. A rolling bearing according to claim 1 or 2, wherein the thickness of the second annular portion increases from the tip end portion side toward the connecting portion side.

7. A rolling bearing according to claim 1 or 2, wherein the connecting portion is positioned radially closer to the second bearing ring than the inner shoulder portion.

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