Jade Axle

Abstract

To provide a ball bearing that can achieve both creep suppression and miniaturization. [Solution] In a ball bearing 1 having a fitting surface 2a on the outer diameter surface of the outer ring 2 that fits into a mating member, the housing H, and a plurality of annular grooves 8, in which a resin material 10 is mounted, the annular groove 8 has a groove bottom surface 8a, a first groove side surface 8b located on the raceway surface 3 side of the outer ring 2, and a second groove side surface 8c located on the axially outer side of the outer ring 2, a first connecting surface 8d with an arc cross-section is formed between the groove bottom surface 8a and the first groove side surface 8b, a second connecting surface 8e with an arc cross-section is formed between the groove bottom surface 8a and the second groove side surface 8c, and the radius of curvature of the cross-sectional shape of the first connecting surface 8d is larger than the radius of curvature of the cross-sectional shape of the second connecting surface 8e.

Description

[Technical Field]

[0001] The present invention relates to a ball bearing in which an elastic member is mounted in an annular groove provided on an outer diameter surface of an outer ring. [Background Art]

[0002] In addition to automobile transmissions, bearings that support speed reducers, transmissions, and drive motors using motor drive such as EVs and HEVs are experiencing ongoing progress in the reduction of size and weight of the units. Accordingly, there is a tendency to make the housing of the orbiting ring of a ball bearing or a transmission thinner. Therefore, depending on the specifications and load conditions of the ball bearing, the fixed ring of the ball bearing may creep relative to the housing.

[0003] In order to suppress the occurrence of creep, a rolling bearing has been proposed in which annular grooves are provided in parallel on the outer peripheral surface of an outer ring serving as a fixed ring, and a resin material is injection-molded inside each annular groove (see Patent Document 1). The resin material of the rolling bearing described in Patent Document 1 is injection-molded in a state where a part thereof protrudes radially outward from the outer diameter surface of the outer ring. In addition, the resin material is formed of a polymer material having a large coefficient of linear expansion.

[0004] In the rolling bearing described in Patent Document 1, due to the difference in coefficient of linear expansion, a resin material is interposed on the fitting surface with the housing on the outer diameter surface of the outer ring, whereby the occurrence of creep can be prevented. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Utility Model Laid-Open No. 63-115925 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] In recent years, various devices incorporating ball bearings have become smaller and lighter, and these bearings may be subjected to large loads despite their limited size. In the ball bearing described in Patent Document 1, the corners of the annular groove of the outer ring are formed in an R shape (see Figure 4 in Patent Document 1). In this ball bearing, stress is generated at the corners of the circumferential groove of the outer ring when a load is applied. The smaller the size of the corners of the annular groove of the outer ring (the size of the radius of curvature in the cross-sectional shape of the corner), the more likely stress is to concentrate at the corners of the annular groove of the outer ring, which increases the risk of failure of the rolling bearing.

[0007] To prevent damage to the ball bearing, it is conceivable to increase the size of the corners of the annular groove on the outer ring. However, in this case, the radial cross-sectional area inside the annular groove becomes smaller, which may reduce the amount of resin material that can be filled, or worsen the ease of installing the O-ring, potentially making it difficult to suppress creep.

[0008] Therefore, the objective of this invention is to provide a ball bearing that can achieve both creep suppression and miniaturization. [Means for solving the problem]

[0009] To solve the above problems, the ball bearing of this invention can be adopted having the following configurations 1 to 7. [Configuration 1] The device comprises an outer ring having a raceway surface on its inner diameter surface, an inner ring having a raceway surface on its outer diameter surface, and a ball interposed between the raceway surface of the outer ring and the raceway surface of the inner ring. The outer diameter surface of the outer ring has a mating surface that fits into a mating member and at least one annular groove provided on the mating surface, and an elastic member is fitted into the annular groove. In a ball bearing in which the annular groove has a groove bottom surface, a first groove side surface located axially inward from the groove bottom surface, and a second groove side surface located axially outward from the outer ring relative to the groove bottom surface, a first connecting surface is formed between the groove bottom surface and the first groove side surface, a second connecting surface is formed between the groove bottom surface and the second groove side surface, and the radial cross-sectional shape of the first and second connecting surfaces is an arc, A ball bearing characterized in that the radius of curvature of the cross-sectional shape of the first connecting surface is larger than the radius of curvature of the cross-sectional shape of the second connecting surface.

[0010] This configuration ensures sufficient wall thickness between the first connecting surface and the raceway surface of the outer ring, eliminating the need to increase the thickness of the outer ring and suppressing a decrease in the strength of the outer ring. Furthermore, during operation, the frictional force acting between the elastic member fitted in the annular groove and the mating member suppresses the occurrence of creep.

[0011] [Configuration 2] The ball bearing according to configuration 1, characterized in that when the radius of curvature of the cross-sectional shape of the first connecting surface is R1 and the radius of curvature of the cross-sectional shape of the second connecting surface is R2, the relationship between R1 and R2 is 1.1 × R2 ≤ R1 ≤ 3.3 × R2.

[0012] This configuration allows for a larger axial width dimension of the groove bottom surface of the annular groove, thereby increasing the radial cross-sectional area of ​​the annular groove. Furthermore, when an elastic member is installed in the annular groove, the elastic member can be positioned on the outer circumference of the groove bottom surface within the annular groove, making installation easier.

[0013] [Configuration 3] The ball bearing according to configuration 1 or configuration 2, characterized in that the ratio of the radius of curvature of the cross-sectional shape of the first connecting surface to the diameter of the ball is 5 to 35%.

[0014] Generally, the load capacity of a ball bearing is affected by the diameter of the balls. With this configuration, the radius of curvature of the cross-sectional shape of the first connecting surface does not become too large relative to the diameter of the balls, which affects the load capacity of the ball bearing. Therefore, it is possible to ensure a sufficient axial width dimension of the groove bottom surface of the annular groove.

[0015] [Structure 4] The ball bearing according to any one of Configurations 1 to 3, wherein a ratio of an axial width dimension of the groove bottom surface to an axial distance from an end surface on one axial side of the outer ring to a center of a full width of the outer ring is 3 to 32%.

[0016] With this configuration, the axial width dimension of the groove bottom surface does not become excessively large, and the machining of the annular groove can be stably performed on the fitting surface of the outer diameter surface of the outer ring.

[0017] [Configuration 5] The ball bearing according to any one of Configurations 1 to 4, wherein the elastic member is formed of a resin material filled into the annular groove, and the resin material protrudes radially outward beyond the fitting surface.

[0018] With this configuration, when the outer ring is fitted to a counterpart member, the resin material is compressed in the radial direction by the counterpart member, whereby creep can be suppressed.

[0019] [Configuration 6] The ball bearing according to any one of Configurations 1 to 4, wherein the elastic member is an annular member that tightens the groove bottom surface of the annular groove, and the annular member protrudes radially outward beyond the fitting surface.

[0020] With this configuration, when the outer ring is fitted to a counterpart member, the annular member is compressed in the radial direction by the counterpart member, whereby creep can be suppressed.

[0021] [Configuration 7] The ball bearing according to any one of Configurations 1 to 6, wherein a material of the elastic member has a larger coefficient of linear expansion than a material of the outer ring.

[0022] With this configuration, when the temperature of the outer ring rises during operation, the elastic member expands more greatly relative to the outer ring. For this reason, in a state where the outer ring is fitted to the counterpart member, the frictional resistance between the elastic member and the counterpart member increases. Effects of the Invention

[0023] According to the present invention, there can be provided a rolling bearing that achieves both creep suppression and size reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] [Figure 1] Cross-sectional view showing a state where the ball bearing according to the first embodiment of the present invention is fitted into a housing [Figure 2] Cross-sectional view showing the outer ring of the same ball bearing [Figure 3] Cross-sectional view showing a first modified example of the annular groove of the same ball bearing [Figure 4] Cross-sectional view showing a second modified example of the annular groove of the same ball bearing [Figure 5] Cross-sectional view showing a third modified example of the annular groove of the same ball bearing [Figure 6] Cross-sectional view showing a state where the ball bearing according to the second embodiment of the present invention is fitted into a housing MODES FOR CARRYING OUT THE INVENTION

[0025] A ball bearing 1 according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. The ball bearing 1 according to the present embodiment includes an outer ring 2, an inner ring 4 disposed radially inward of the outer ring 2, balls 6 that are a plurality of rolling elements interposed between the outer ring 2 and the inner ring 4, and a retainer 7.

[0026] The ball bearing 1 is an inner ring rotation type in which the outer ring 2 is a fixed ring and the inner ring 4 is a rotating ring that rotates relative to the outer ring 2. Note that the ball bearing 1 may be an outer ring rotation type in which the outer ring 2 is a rotating ring.

[0027] In the present embodiment, the direction along the bearing central axis O of the ball bearing 1 is referred to as the "axial direction". In the axial direction, the side closer to the rolling elements is referred to as the axial inner side, and the opposite side is referred to as the axial outer side. The direction orthogonal to the bearing central axis O of the ball bearing 1 is referred to as the "radial direction". In the radial direction, the side closer to the rolling elements is referred to as the radial inner side, and the opposite side is referred to as the radial outer side. The circumferential direction around the bearing central axis O of the ball bearing 1 is referred to as the "circumferential direction".

[0028] The outer ring 2 has a raceway surface 3 on its inner circumference on which the balls 6 roll. The raceway surface 3 can make contact with the balls 6 at a contact angle of 0° around its entire circumference.

[0029] The outer diameter surface of the outer ring 2 has a fitting surface 2a located radially opposite to the raceway surface 3, and at least one (in this case, multiple) annular grooves 8. The fitting surface 2a is provided over almost the entire axial area of ​​the outer diameter surface of the outer ring 2, excluding the axial ends. The fitting surface 2a is a cylindrical surface. A chamfer is provided between the fitting surface 2a and the axial outer end surface 2b of the outer ring 2.

[0030] The mating surface 2a is fitted with the housing H (for example, the housing of an automobile transmission). The outer ring 2 is clearance-fitted with the housing H. During operation, the radial load applied to the ball bearing 1 causes the mating surface 2a of the outer ring 2 to come into contact with the housing H.

[0031] The inner ring 4 has a raceway surface 5 on its outer circumference on which balls 6 roll. The raceway surface 5 can make contact with the balls 6 at a contact angle of 0° around its entire circumference. Multiple balls 6 are held in place by a cage 7 so that they can roll.

[0032] Two annular grooves 8 are provided on the fitting surface 2a of the outer ring 2. The annular grooves 8 are provided axially outward with respect to the axial centerline C of the outer ring 2. Each annular groove 8 has a groove bottom surface 8a, a first groove side surface 8b, and a second groove side surface 8c. The groove bottom surface 8a is a cylindrical surface. The first groove side surface 8b is located on the raceway surface 3 side of the outer ring 2 with respect to the groove bottom surface 8a. The second groove side surface 8c is located on the outer end surface 2b side of the outer ring 2 with respect to the axial centerline C. The first groove side surface 8b and the second groove side surface 8c are formed along the radial direction. Each annular groove 8 may be provided at a position axially symmetrical with respect to the axial centerline C of the outer ring 2, or at a position axially asymmetrical with respect to the centerline C.

[0033] A first connecting surface 8d is formed between the groove bottom surface 8a and the first groove side surface 8b. The radial cross-sectional shape of the first connecting surface 8d is an arc. The first connecting surface 8d is a curved surface that connects the groove bottom surface 8a and the first groove side surface 8b. A second connecting surface 8e is formed between the groove bottom surface 8a and the second groove side surface 8c. The radial cross-sectional shape of the second connecting surface 8e is an arc. The second connecting surface 8e is a curved surface that connects the groove bottom surface 8a and the second groove side surface 8c.

[0034] When R1 is the radius of curvature of the radial cross-sectional shape of the first connecting surface 8d and R2 is the radius of curvature of the radial cross-sectional shape of the second connecting surface 8e, R1 is larger than R2. Specifically, the relationship between R1 and R2 is 1.1 × R2 ≤ R1 ≤ 3.3 × R2. This relationship between R1 and R2 allows for securing the axial width dimension W1 of the groove bottom surface 8a of the annular groove 8 shown in Figure 2, and thus securing the radial cross-sectional area inside the annular groove 8. In addition, the wall thickness between the first connecting surface 8d and the raceway surface 3 of the outer ring 2 is increased, which helps to suppress a decrease in the strength of the outer ring 2.

[0035] If R1 is less than 1.1 × R2, the wall thickness between the first connecting surface 8d and the raceway surface 3 of the outer ring 2 becomes smaller, making it easier for stress to concentrate on the first connecting surface 8d during operation, which may lead to bearing failure. On the other hand, if R1 is greater than 3.3 × R2, the axial width dimension W1 of the groove bottom surface 8a of the annular groove 8 shown in Figure 2 becomes smaller, and the radial cross-sectional area inside the annular groove 8 becomes smaller. As a result, the amount of resin material 10 to be filled into the annular groove 8, which will be described later, becomes smaller.

[0036] Here, the diameter of the ball 6 affects the load capacity of the ball bearing 1. The ratio of R1 to the diameter of the ball 6, which affects the load capacity of the ball bearing 1, is 5 to 35%. According to this relationship between the diameter of the ball 6 and R1, R1 does not become too large relative to the diameter of the ball 6, and the axial width dimension W1 of the groove bottom surface of the annular groove 8 can be secured. If the ratio of R1 to the diameter of the ball 6 is less than 5%, in this case as well, the wall thickness between the first connecting surface 8d and the raceway surface 3 of the outer ring 2 becomes small, and stress concentration on the first connecting surface 8d is more likely during operation, which may lead to bearing failure. On the other hand, if the ratio of R1 to the diameter of the ball 6 is greater than 35%, the axial width dimension W1 of the groove bottom surface 8a of the annular groove 8 shown in Figure 2 becomes small, and the radial cross-sectional area inside the annular groove 8 becomes small.

[0037] As shown in Figure 1, the ratio of the axial width dimension W1 of the groove bottom surface 8a to the axial distance W0 from the axial outer end surface 2b of the outer ring 2 to the center C of the overall width of the outer ring is 3 to 32%. This relationship between the axial distance W0 and the axial width dimension W1 of the groove bottom surface 8a ensures that the axial width dimension W1 of the groove bottom surface 8a does not become too large, allowing for stable machining of the annular groove 8 on the mating surface 2a of the outer diameter surface of the outer ring 2. If the ratio of the axial width dimension W1 of the groove bottom surface 8a to the axial distance W0 is less than 3%, the radial cross-sectional area inside the annular groove 8 becomes smaller, reducing the amount of resin material 10 to be filled, as described later. On the other hand, if the ratio of the axial width dimension W1 of the groove bottom surface 8a to the axial distance W0 is greater than 32%, it becomes difficult to stably machine the annular groove 8 on the mating surface 2a of the outer diameter surface of the outer ring 2.

[0038] The groove depth of the annular groove 8 (the radial distance between the fitting surface 2a of the outer diameter surface of the outer ring 2 and the groove bottom surface 8a) should be such that sufficient wall thickness is secured between the first connecting surface 8d and the raceway surface 3 of the outer ring 2. For example, R1 and R2 may be set to less than 2 / 3 of the groove depth of the annular groove 8. In this way, when the annular groove 8 is formed by machining, the removal of cutting chips is improved and the generation of burrs can be suppressed.

[0039] An elastic member is fitted inside the annular groove 8. This elastic member is made of a resin material 10 that is filled inside the annular groove 8. As shown in Figure 1, the resin material 10, while filled inside the annular groove 8, partially protrudes radially from the mating surface 2a. When the mating surface 2a of the outer ring 2 is fitted into the housing H, the resin material 10 is compressed radially by the housing H. The frictional force acting between the resin material 10, which is compressed by the housing H, and the housing H suppresses the occurrence of creep. The resin material 10 can be made of a material with a higher coefficient of linear expansion than the material of the outer ring 2, such as nitrile rubber, acrylic rubber, fluororubber, or silicone rubber.

[0040] The ball bearing 1 of the first embodiment of this invention is configured as described above. In this ball bearing 1, the R1 of the first connecting surface 8d of the annular groove 8 is greater than the R2 of the second connecting surface 8e. Specifically, the relationship between R1 and R2 of the annular groove 8 is 1.1 × R2 ≤ R1 ≤ 3.3 × R2. According to this relationship, the wall thickness between the first connecting surface 8d and the raceway surface 3 of the outer ring 2 can be secured. Therefore, it is not necessary to increase the wall thickness of the outer ring 2. In addition, during operation, the frictional force acting between the resin material 10 filled in the annular groove 8 and the housing H suppresses the occurrence of creep. Thus, it is possible to achieve both creep suppression and miniaturization of the ball bearing 1.

[0041] Furthermore, the ratio of the radius R1 of the first connecting surface 8d to the diameter of the ball 6 is 5-35%. Therefore, the radius R1 of the first connecting surface 8d does not become too large relative to the diameter of the ball 6, and the axial width dimension W1 of the groove bottom surface 8a of the annular groove 8 can be secured. Thus, the amount of resin material to be filled into the annular groove 8 can be secured, and the occurrence of creep can be suppressed.

[0042] Furthermore, the ratio of the axial width dimension W1 of the groove bottom surface 8a to the axial distance W0 from the end face 2b on one axial side of the outer ring 2 to the center C of the overall width of the outer ring 2 is 3 to 32%. As a result, the axial width dimension W1 of the groove bottom surface 8a does not become too large, and the annular groove 8 can be machined stably against the fitting surface 2a of the outer diameter surface of the outer ring 2.

[0043] In the first embodiment described above, as shown in Figure 3, as a first modification of the annular groove 8, a recessed portion that is axially outward is formed in the annular groove 8 by the second connecting surface 8e of the annular groove 8. In this case, the resin material 10 enters the interior of the second connecting surface 8e, and the contact area between the second connecting surface 8e and the resin material 10 increases. As a result, the resin material 10 is less likely to rotate inside the annular groove 8 during operation.

[0044] Furthermore, in the first embodiment described above, as shown in Figure 4, as a second modification of the annular groove 8, the first connecting surface 8d of the annular groove 8 may form a recessed portion in the annular groove 8 that is axially recessed toward the axial central axis C of the outer ring 2, and the second connecting surface 8e of the annular groove 8 may also form a recessed portion in the annular groove 8 that is axially recessed outward. In this case, the resin material 10 penetrates into the interior of the first connecting surface 8d and the second connecting surface 8e, and the contact area between the first connecting surface 8d and the second connecting surface 8e and the resin material 10 becomes larger.

[0045] Furthermore, in the first embodiment described above, as shown in Figure 5, as a third modification of the annular groove 8, the first groove side surface 8b may be formed to widen radially outward toward the axial central axis C of the outer ring 2, and the second groove side surface 8c may be formed to widen radially outward toward the axial end face 2b of the outer ring 2. In this case, the contact area between the resin material 10 and the housing H increases during operation, and creep can be suppressed more effectively.

[0046] A second embodiment of the ball bearing 1 of this invention will be described with reference to Figure 6. The ball bearing 1 according to this second embodiment differs from the ball bearing 1 according to the first embodiment described above in that the elastic member is an annular member 11, and the annular member 11 is fitted into an annular groove 8. For this reason, only the differences will be described, and other components that are considered to be the same as those in the first embodiment will be given the same reference numerals and their descriptions will be omitted.

[0047] As shown in Figure 6, the annular member 11 of the ball bearing 1 is, for example, an O-ring, and is fitted into the annular groove 8 in a state where it tightens against the groove bottom surface 8a of the annular groove 8. The annular member 11 partially protrudes radially from the mating surface 2a. When the mating surface 2a of the outer ring 2 is fitted into the housing H, the annular member 11 is compressed radially by the housing H. At this time, a frictional force acts between the annular member 11, which is compressed by the housing H, and the housing H. Furthermore, the annular member 11 is in a state where it tightens against the groove bottom surface 8a of the annular groove 8. Therefore, a tightening force also acts on the annular member 11 against the groove bottom surface 8a. This frictional force and tightening force effectively suppress the occurrence of creep. [Explanation of Symbols]

[0048] 1 ball bearing 2 Outer ring 2a Fitting surface 2b End face 3, 5 Raceway surface 4. Inner Ring 6 balls 7 Cage 8. Annular groove 8a Groove bottom surface 8b First groove side 8c Second groove side 8d First connection surface 8e Second connection surface 10 Resin materials 11 Annular member H Housing

Claims

1. The device comprises an outer ring having a raceway surface on its inner diameter surface, an inner ring having a raceway surface on its outer diameter surface, and a ball interposed between the raceway surface of the outer ring and the raceway surface of the inner ring. The outer diameter surface of the outer ring has a mating surface that fits into a mating member and at least one annular groove provided on the mating surface, and an elastic member is fitted into the annular groove. In a ball bearing in which the annular groove has a groove bottom surface, a first groove side surface located on the raceway surface side of the outer ring relative to the groove bottom surface, and a second groove side surface located on the axial outer end surface side of the outer ring relative to the groove bottom surface, a first connecting surface is formed between the groove bottom surface and the first groove side surface, a second connecting surface is formed between the groove bottom surface and the second groove side surface, and the radial cross-sectional shape of the first and second connecting surfaces is an arc, A ball bearing characterized in that the radius of curvature of the cross-sectional shape of the first connecting surface is larger than the radius of curvature of the cross-sectional shape of the second connecting surface.

2. The ball bearing according to claim 1, characterized in that when R1 is the size of the radius of curvature of the cross-sectional shape of the first connecting surface and R2 is the size of the radius of curvature of the cross-sectional shape of the second connecting surface, the relationship between R1 and R2 is 1.1 × R2 ≤ R1 ≤ 3.3 × R2.

3. The ball bearing according to claim 1 or 2, characterized in that the ratio of the radius of curvature of the cross-sectional shape of the first connecting surface to the diameter of the ball is 5 to 35%.

4. The ball bearing according to claim 1 or 2, characterized in that the ratio of the axial width dimension of the groove bottom surface to the axial distance from the end face on one axial side of the outer ring to the center of the overall width of the outer ring is 3 to 32%.

5. The ball bearing according to claim 1, characterized in that the elastic member is formed from a resin material that fills the inside of the annular groove, and the resin material protrudes radially outward from the mating surface.

6. The ball bearing according to claim 1, characterized in that the elastic member is an annular member that tightens the groove bottom surface of the annular groove, and the annular member protrudes radially outward from the mating surface.

7. The ball bearing according to claim 1, characterized in that the material of the elastic member has a higher coefficient of linear expansion than the material of the outer ring.

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