Rolling bearing

Abstract

To provide a rolling bearing capable of effectively using grease sealed between inner and outer rings.SOLUTION: A rolling bearing includes: an inner ring 2; an outer ring 3 coaxially provided on a radial outer side of the inner ring 2; a plurality of rolling elements 4 disposed between the inner ring 2 and the outer ring 3; a retainer 5 that holds the plurality of rolling elements 4; and sealing plates 6 provided at both ends of the inner and outer rings 2, 3. Grease is sealed between the inner ring 2 and the outer ring 3. The retainer 5 is a combined retainer obtained by combining a pair of split pieces 11, 12 opposed to each other axially, and the pair of split pieces 11, 12 enable relative displacement in an axial direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rolling bearing. [Background technology]

[0002] In rolling bearings lubricated with grease, sealing plates for retaining grease between the inner and outer rings are provided at both axial ends, as shown in Patent Document 1 below, for example. In a rolling element guided cage, which is guided by the rolling elements, the radial and axial movements are restricted by the rolling elements, so there is always an axial gap of a predetermined size between the sealing plates and the cage (see Figure 1 of Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4636035 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the rotational speed of bearings in automotive applications has been increasing, particularly with the shift to electric vehicles. In the rolling bearing shown in Patent Document 1, some of the grease scattered inside the bearing due to centrifugal force caused by the high-speed rotation of the bearing may adhere to the inner surface of the sealing plate. Because a certain amount of axial gap is always present between the sealing plate and the cage, the grease adhering to the inner surface of the sealing plate remains attached to the inner surface without coming into contact with the cage facing the sealing plate, and there is a risk that it will not be effectively used to lubricate the inside of the bearing.

[0005] An object of the present invention is to provide a rolling bearing that can effectively utilize the grease sealed between the inner and outer rings. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides: the bearing comprises an inner ring, an outer ring provided coaxially on the radially outer side of the inner ring, a plurality of rolling elements arranged between the inner ring and the outer ring, a cage that holds the plurality of rolling elements, and sealing plates provided at both axial ends of the inner and outer rings, Grease is sealed between the inner ring and the outer ring, and the retainer is a mating retainer made up of a pair of split pieces that face each other in the axial direction, and the pair of split pieces are capable of relative movement in the axial direction to form a rolling bearing.

[0007] In this way, the pair of segments, which are axially movable relative to each other, move toward the sealing plate and act to push grease adhering to the inner surface of the sealing plate toward the inner and outer rings, making effective use of the grease sealed between the inner and outer rings. This effective use of grease ensures continuity of grease within the bearing, resulting in good lubrication. It also potentially reduces the initial amount of grease sealed in and extends the life of the grease.

[0008] In the above configuration, a column portion is formed by axially combining a first column piece formed on one side of the pair of split pieces and a second column piece formed on the other side of the pair of split pieces and having an axial length relatively shorter than that of the first column piece, and it is preferable that, in the portion where the first column piece and the second column piece are combined, the second column piece is positioned on the outer diameter side of the first column piece.

[0009] This allows smooth relative axial movement between the first and second pillar pieces. Moreover, since the second pillar piece, which has a relatively short axial length, is positioned on the outer diameter side of the first pillar piece, the second pillar piece, which has a relatively high rigidity, can prevent the first pillar piece from deforming toward the outer diameter side due to centrifugal force.

[0010] In a configuration having the first pillar piece and the second pillar piece, it is preferable that at least one of the first pillar piece or the second pillar piece has a tapered surface formed thereon that acts to separate the two pillar pieces from each other in the axial direction due to the contact force acting from the rolling element to the retainer.

[0011] In this way, the contact force between the rolling elements and the cage when the bearing is rotating allows the two post pieces to be smoothly separated, thereby improving the effect of pushing out grease adhering to the inner surface of the sealing plate.

[0012] In all of the above configurations, it is preferable that a convex portion protruding toward the retainer is formed on the surface of the sealing plate facing the retainer, or that a convex portion protruding toward the sealing plate is formed on the surface of the retainer facing the sealing plate.

[0013] In this way, by forming a convex portion on the surface of the sealing plate facing the retainer, or on the surface of the retainer facing the sealing plate, it is possible to more effectively prevent grease from adhering to the inner surface of the sealing plate while suppressing the sliding resistance between the retainer and the sealing plate.

[0014] In a configuration having the first pillar piece and the second pillar piece, it is preferable that a grease flow passage extending in the axial direction is formed on at least one of the inner diameter surface or the outer diameter surface of the retainer, or that a grease flow passage extending in the radial direction is formed on the pocket surface of the pillar portion.

[0015] In this way, the grease pushed out from the inner surface of the sealing plate toward the inner and outer rings, and the grease in the pocket surface of the retainer, can be moved near the raceway groove, and the movement of grease near the retainer can be promoted, thereby further improving the lubrication provided by the grease.

[0016] In all of the above configurations, the cage may be made of any one of polyamide resin, polyether ether ketone resin, and polyphenylene sulfide resin. Also, in all of the above configurations, balls are used as the rolling elements, and the configuration may be adopted in any one of a motor, a transmission, and a reducer. [Effects of the Invention]

[0017] In the rolling bearing according to the present invention, the cage is a laminated cage made up of a pair of axially opposed segments, which are configured to be movable relative to one another in the axial direction. Therefore, the pair of segments, which are movable relative to one another in the axial direction, move toward the sealing plate, pushing grease adhering to the inner surface of the sealing plate toward the inner and outer rings. This allows for effective use of the grease sealed between the inner and outer rings. This effective use of grease ensures grease continuity within the bearing, resulting in a good lubrication state. It also potentially reduces the initial amount of grease sealed in and extends the life of the grease. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view showing a first embodiment of a rolling bearing according to the present invention; [Figure 2] Cross-sectional view along line II-II in Figure 1 [Figure 3] FIG. 2 is a perspective view showing a divided piece of the cage of the rolling bearing shown in FIG. 1; [Figure 4] FIG. 10 is a perspective view showing a state in which a pair of split pieces of a cage are opposed to each other in the axial direction. [Figure 5] A cross-sectional view of the rolling bearing shown in Figure 1, with each divided piece of the cage approaching the sealing plate. [Figure 6] Cross-sectional view along line VI-VI in Figure 5 [Figure 7] FIG. 10 is a cross-sectional view showing a second embodiment of a rolling bearing according to the present invention. [Figure 8] Cross-sectional view taken along line VIII-VIII in Figure 7 [Figure 9] 8 is a cross-sectional view of the main part of the rolling bearing shown in FIG. 7, showing the state in which the divided pieces of the cage are close to the sealing plate. [Figure 10] FIG. 10 is a cross-sectional view showing a third embodiment of a rolling bearing according to the present invention. [Figure 11] Cross-sectional view along line XI-XI in Figure 10 [Figure 12] 11 is a cross-sectional view of the main part of the rolling bearing shown in FIG. 10, showing the state in which the divided pieces of the cage are close to the sealing plate. DETAILED DESCRIPTION OF THE INVENTION

[0019] A first embodiment of a rolling bearing 1 according to the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2 , the rolling bearing 1 according to the first embodiment comprises an inner ring 2, an outer ring 3 disposed coaxially radially outward of the inner ring 2, a plurality of rolling elements 4 arranged between the inner ring 2 and the outer ring 3, a cage 5 for holding the plurality of rolling elements 4, and sealing plates 6 disposed at both axial ends of the inner and outer rings 2, 3. This rolling bearing 1 is a ball bearing that employs balls (hereinafter, designated by the same reference numerals as the rolling elements) as the rolling elements 4, and these balls 4 roll in inner ring raceway grooves 7 formed on the outer diameter surface of the inner ring 2 and outer ring raceway grooves 8 formed on the inner diameter surface of the outer ring 3. A motor shaft 9 is inserted into the axial center of the inner ring 2, and the outer ring 3 is fitted into a housing 10. In the following, the direction along the rotation axis of the rolling bearing 1 will be referred to as the axial direction, the direction perpendicular to the rotation axis as the radial direction, and the direction along the circumference going around the rotation axis as the circumferential direction.

[0020] As shown in Figure 3, the cage 5 is a rolling-element guided laminated cage made of a resin such as polyamide resin, polyether ether ketone resin, or polyphenylene sulfide resin, and is made by combining a pair of axially opposing segments 11 and 12. Each segment 11 and 12 has an annular body 13 and multiple pairs of first and second post segments 14 and 15 that extend from the body 13 in one axial direction and face each other in the circumferential direction. The inner surfaces of the paired first and second post segments 14 and 15 and the axial side surface of the annular body 13 sandwiched between the post segments 14 and 15 form part of a pocket surface having a spherical inner surface.

[0021] Grease passages 16, 17 extending in the axial direction are formed on the inner and outer diameter surfaces of the annular body 13 in the middle of the pair of adjacent first and second post segments 14, 15. In this embodiment, the grease passages 16, 17 are formed between the pair of adjacent first and second post segments 14, 15, but the grease passages 16, 17 can also be formed between the first and second post segments 14, 15 (at positions corresponding to the pockets) as long as the predetermined rigidity of the cage 5 can be ensured.

[0022] The axial length of the second post piece 15 is shorter than the axial length of the first post piece 14. A radially extending grease flow path 18 is formed on the inner surface (pocket surface) of the first post piece 14. This grease flow path 18 is located within a plane including an imaginary circle (pitch circle) connecting the centers of the balls 4. A tapered surface 19 is formed on the outer surface of the first post piece 14, sloping inward toward its tip. A radial piece 20 and a circumferential piece 21 are formed at the tip of the second post piece 15 so as to form an L-shape when viewed in the axial direction. A tapered surface 22 is formed on the inner surface of the circumferential piece 21, sloping outward toward its tip.

[0023] As shown in Figure 4, the pair of split pieces 11, 12 are combined by inserting the first post piece 14 formed on one side into the second post piece 15 formed on the other side in the axial direction, and the first post piece 14 formed on the other side into the second post piece 15 formed on the first side in the axial direction (insertion depth w (see Figure 1)), so that the pair of split pieces 11, 12 are configured to be able to move relative to each other in the axial direction. The combined first post piece 14 and second post piece 15 form a column section.

[0024] The combined first column piece 14 and second column piece 15 are such that while the relative movement in the radial direction and circumferential direction is mutually restricted by the action of the radial piece 20 and circumferential piece 21, the relative movement in the axial direction is possible. At the portion where the first column piece 14 and the second column piece 15 are combined, the second column piece 15 with a relatively short axial length is arranged on the outer diameter side of the first column piece 14 with a relatively long axial length.

[0025] The sealing plate 6 is a rubber member with a mandrel embedded inside. As shown in FIG. 1, the outer peripheral edge of the sealing plate 6 is fitted into the circumferential grooves 23 formed at both axial ends of the inner diameter surface of the outer ring 3. Also, the inner peripheral edge (lip) of the sealing plate 6 is in sliding contact with the outer diameter surface of the inner ring 2. In the state where the first column piece 14 and the second column piece 15 are assembled until they abut axially, axial gaps w1, w2 are formed between the cage 5 and the sealing plate 6. The axial lengths of both column pieces 14, 15 are designed such that the sum of these axial gaps w1, w2 is smaller than the insertion depth w of the first column piece 14 into the second column piece 15 (w1 + w2 < w).

[0026] The operation of the rolling bearing 1 shown in FIG. 1 will be described. In the assembled state of this rolling bearing 1, the pair of split pieces 11, 12 constituting the cage 5 are in the state closest to each other in the axial direction. Here, when the rolling bearing 1 rotates, as shown in FIGS. 5 and 6, due to the contact force between the ball 4 and the pocket surface of the cage 5, and the contact force between the tapered surfaces 19, 22 formed on the first column piece 14 and the second column piece 15 constituting the column portion respectively, the pair of split pieces 11, 12 that are axially relatively movable move toward the sealing plate 6 side respectively, and the grease attached to the inner surface of the sealing plate 6 is extruded toward the inner and outer rings 2, 3 (refer to the arrows in FIG. 5).

[0027] In the above-described rolling bearing 1, the pair of segments 11, 12, which are movable relative to each other in the axial direction, each move toward the sealing plate 6, pushing out grease adhering to the inner surface of the sealing plate 6 toward the inner and outer rings 2, 3, thereby making effective use of the grease sealed between the inner and outer rings 2, 3. This effective use of grease ensures continuity of the grease inside the bearing, resulting in good lubrication. It also makes it possible to reduce the initial amount of grease sealed in and potentially extend the life of the grease.

[0028] In addition, the rolling bearing 1 has a column portion formed by axially combining a first column piece 14 formed on one side of the pair of segments 11, 12 with a second column piece 15 formed on the other side of the pair of segments 11, 12 and having a relatively shorter axial length than the first column piece 14, and in the combined portion of the first column piece 14 and the second column piece 15, the second column piece 15 is arranged on the outer diameter side of the first column piece 14, so that the first column piece 14 and the second column piece 15 can smoothly move relative to each other in the axial direction. Moreover, because the second column piece 15, which has a relatively short axial length, is arranged on the outer diameter side of the first column piece 14, the second column piece 15, which has a relatively high rigidity, can suppress deformation of the first column piece 14 toward the outer diameter side due to centrifugal force.

[0029] Furthermore, in the above-described rolling bearing 1, the first post piece 14 and the second post piece 15 are formed with tapered surfaces 19, 22 that act to separate the post pieces 14, 15 from each other in the axial direction by the contact force acting from the balls 4 to the cage 5. Therefore, the post pieces 14, 15 can be smoothly separated from each other by the contact force between the balls 4 and the cage 5 during bearing rotation, thereby improving the effect of pushing out grease adhering to the inner surface of the sealing plate 6. Note that the tapered surfaces 19, 22 may also be formed on only one of the first post piece 14 or the second post piece 15. Furthermore, if the post pieces 14, 15 can be separated from each other in the axial direction only by the contact force acting on the balls 4 and the cage 5, it may be possible to configure the bearing without forming the tapered surfaces 19, 22.

[0030] Further, in the above-described rolling bearing 1, grease flow paths 16 and 17 extending axially are formed on the inner diameter surface and the outer diameter surface of the cage 5, and a grease flow path 18 extending radially is formed on the pocket surface of the column portion (first column piece 14). Therefore, the grease extruded from the inner surface of the sealing plate 6 toward the inner and outer rings 2 and 3, and the grease in the pocket surface of the cage 5 can be moved to the vicinity of the inner ring raceway groove 7 and the outer ring raceway groove 8, and the movement of the grease in the vicinity of the cage 5 can be promoted. Thus, the lubricity by the grease can be further enhanced.

[0031] Also, in the above-described rolling bearing 1, the axial lengths of the both column pieces 14 and 15 are designed such that the sum of the axial gaps w1 and w2 between the cage 5 and the sealing plate 6 is smaller than the insertion depth w of the first column piece 14 into the second column piece 15 (w1 + w2 < w). Therefore, even when the pair of split pieces 11 and 12 are closest to the sealing plate 6 respectively, it is possible to prevent the first column piece 14 from coming out of the second column piece 15 and the both split pieces 11 and 12 from separating.

[0032] A second embodiment of the rolling bearing 1 according to the present invention is shown in FIGS. 7 to 9, and a third embodiment is shown in FIGS. 10 to 12 respectively. These rolling bearings 1 have a basic configuration common to the rolling bearing 1 according to the first embodiment, but are different in that a convex portion 24 protruding toward the cage 5 is formed on the surface of the sealing plate 6 facing the cage 5 (see FIGS. 7 to 9), or a convex portion 24 protruding toward the sealing plate 6 is formed on the surface of the cage 5 facing the sealing plate 6. A plurality of the convex portions 24 are formed along the circumferential direction of the sealing plate 6 or the cage 5. In these embodiments, the convex portions 24 are formed at regular intervals in the circumferential direction, but they can also be formed at different intervals in the circumferential direction. Also, in these embodiments, the convex portions 24 have a three-dimensional shape obtained by cutting a part of a cylinder with a plane, but they can also have a three-dimensional shape obtained by cutting a part of an elliptic cylinder with a plane, or a three-dimensional shape (spherical segment, elliptic spherical segment) obtained by cutting a part of a sphere or an ellipsoid with a plane.

[0033] 9 and 12, when the rolling bearing 1 rotates, the pair of split pieces 11, 12, which are movable relative to each other in the axial direction, move toward the sealing plate 6 due to the contact force between the balls 4 and the pocket surfaces of the cage 5 and the contact force between the tapered surfaces 19, 22 formed on the first post piece 14 and the second post piece 15 that make up the cage 5. Then, the action of the protrusions 24 formed on the sealing plate 6 or the cage 5 pushes out the grease adhering to the inner surface of the sealing plate 6 toward the inner and outer rings 2, 3.

[0034] By forming the convex portion 24, the rolling bearing 1 according to the second and third embodiments can more effectively prevent grease from adhering to the inner surface of the sealing plate 6 while suppressing the sliding resistance between the cage 5 and the sealing plate 6.

[0035] The height of the protrusions 24 formed on the sealing plate 6 or the cage 5 can be determined as appropriate, but is preferably within the range of 10 μm to 500 μm, more preferably 20 μm to 200 μm, and even more preferably 30 μm to 100 μm. If the height is less than 10 μm, the effect of preventing grease adhesion by the protrusions 24 will not be fully exhibited, while if the height is greater than 500 μm, grease will likely remain trapped between adjacent protrusions 24, so it is preferable to keep the height within the above range.

[0036] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0037] 2. Inner circle 3 outer ring 4 Rolling elements (balls) 5 Cage 6 Sealing plate 11, 12 divided pieces 14 First pillar piece 15 Second pillar piece 16, 17, 18 Grease passages 19, 22 Tapered surface 24 Convex part

Claims

1. The bearing comprises an inner ring (2), an outer ring (3) provided coaxially on the radially outer side of the inner ring (2), a plurality of rolling elements (4) arranged between the inner ring (2) and the outer ring (3), a cage (5) for holding the plurality of rolling elements (4), and sealing plates (6) provided at both axial ends of the inner and outer rings (2, 3), Grease is sealed between the inner ring (2) and the outer ring (3), the retainer (5) is a mating retainer made up of a pair of axially opposed divided pieces (11, 12), and the pair of divided pieces (11, 12) are configured to be movable relative to each other in the axial direction.

2. 2. The rolling bearing according to claim 1, wherein a column portion is formed by combining in the axial direction a first column piece (14) formed on one side of the pair of split pieces (11, 12) and a second column piece (15) formed on the other side of the pair of split pieces (11, 12) and having an axial length relatively shorter than that of the first column piece (14), and wherein, in the portion where the first column piece (14) and the second column piece (15) are combined, the second column piece (15) is positioned on the outer diameter side of the first column piece (14).

3. 3. A rolling bearing according to claim 2, wherein at least one of the first post piece (14) and the second post piece (15) is formed with a tapered surface (19, 22) that acts to separate the two post pieces (14, 15) from each other in the axial direction by a contact force acting from the rolling element (4) to the cage (5).

4. 3. The rolling bearing according to claim 1, wherein a convex portion (24) protruding toward the cage (5) is formed on a surface of the sealing plate (6) facing the cage (5).

5. 3. The rolling bearing according to claim 1, wherein a convex portion (24) protruding toward the sealing plate (6) is formed on a surface of the cage (5) facing the sealing plate (6).

6. 3. The rolling bearing according to claim 1, wherein grease flow passages (16, 17) extending in the axial direction are formed on at least one of the inner diameter surface and the outer diameter surface of the cage (5).

7. 3. The rolling bearing according to claim 2, wherein a grease flow path (18) extending in the radial direction is formed on the pocket surface of the pillar portion.

8. 3. The rolling bearing according to claim 1, wherein the cage (5) is made of one of polyamide resin, polyether ether ketone resin, and polyphenylene sulfide resin.

9. 3. The rolling bearing according to claim 1 or 2, wherein balls are used as the rolling elements, and the rolling bearing is used in a motor, a transmission, or a reducer.

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