Ball bearing

Abstract

A ball bearing has: an inner ring having an inner ring raceway surface on an outer periphery; an outer ring having an outer ring raceway surface on an inner periphery; a plurality of balls disposed between the inner ring raceway surface and the outer ring raceway surface in a manner so as to be able to roll freely; and a cage having a plurality of pockets formed at intervals in a circumferential direction, the plurality of pockets having a cylindrical surface that holds the balls in a manner so as to be able to roll freely, the cage having a peripheral surface that is guided by an outer diameter surface of the inner ring. An inclination angle of the cylindrical surface of the pocket is greater than 0° and less than a contact angle of the ball bearing, the ball and the cylindrical surface contact at a position on an inner side in a thickness direction of the cage at which a rotation axis of the ball and the cylindrical surface intersect, thereby forming a space between the peripheral surface of the cage on a side from the contact position to the intersecting position.

Description

Technical Field

[0001] This invention relates to ball bearings. Background Technology

[0002] For example, ball bearings such as angular contact ball bearings have a cage guided by the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, and the balls are held in pockets formed in the cage in a rolling manner (for example, see Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-140870 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] However, in ball bearings, in order to suppress the degradation of bearing performance such as bearing life, it is desirable to ensure sufficient lubrication at the contact portion between the cylindrical surface of the cage pocket and the ball.

[0008] However, as described in Patent Document 1, if the angle of inclination between the axial direction of the cage pocket and the radial direction of the bearing is equal to the contact angle when axial preload is applied to the bearing, sufficient lubricant cannot be ensured at the contact portion between the cylindrical surface of the cage pocket and the ball, which may lead to a reduction in bearing performance.

[0009] Therefore, the object of the present invention is to provide a ball bearing that can ensure sufficient lubrication at the contact portion between the cylindrical surface of the cage pocket and the ball, thereby suppressing the deterioration of bearing performance.

[0010] Technical means for solving problems

[0011] The present invention is composed of the following structure.

[0012] A ball bearing comprising:

[0013] Inner ring, the inner ring having an inner ring raceway surface on its outer periphery;

[0014] The outer ring has an outer ring raceway surface on its inner circumference;

[0015] A plurality of balls, wherein the plurality of balls are arranged in a rollable manner between the inner raceway surface and the outer raceway surface; and

[0016] A cage having a plurality of pockets spaced apart circumferentially, the plurality of pockets having cylindrical surfaces that hold the balls in a rolling manner, the cage having a circumferential surface guided by either the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, wherein...

[0017] The inclination angle β of the cylindrical surface of the pocket is greater than 0. ° And it is smaller than the contact angle α of the ball bearing. The ball contacts the cylindrical surface at a position inside the cage thickness direction than the position where the rotation axis of the ball intersects with the cylindrical surface, thereby forming a space between the contact position and the cage circumferential surface on the side of the intersection position.

[0018] Invention Effects

[0019] According to the present invention, sufficient lubricant can be ensured at the contact portion between the cylindrical surface of the cage pocket and the ball, thereby suppressing the deterioration of bearing performance. Attached Figure Description

[0020] Figure 1 This is a partial axial cross-sectional view of a ball bearing according to an example structure of the present invention.

[0021] Figure 2 The diagram shows the cage; (A) is a perspective view, and (B) is a cross-sectional view along the axial direction.

[0022] Figure 3 The diagram shows the holding state of the balls in the cage. (A) is a perspective view of the cage viewed from the outer periphery, with the pocket portion in axial section. (B) is a view in the X direction of (A).

[0023] Figure 4 This is a schematic cross-sectional view along the axial direction of the cage, showing the holding state of the balls in the pocket of the ball bearing involved in Reference Example 1.

[0024] Figure 5 The diagram shows the holding state of the balls in the cage according to Reference Example 1. (A) is a perspective view of the cage viewed from the outer peripheral side in axial section along the pocket portion. (B) is a Y-direction view in (A).

[0025] Figure 6 This is a schematic cross-sectional view along the axial direction of the cage, showing the holding state of the balls in the pocket of the ball bearing involved in Reference Example 2.

[0026] Figure 7 The figures show other shapes of cages, (A) is a perspective view, and (B) is a cross-sectional view along the axis.

[0027] Figure 8The figures show other shapes of cages, (A) is a perspective view, and (B) is a cross-sectional view along the axis.

[0028] Symbol Explanation

[0029] 11 Inner Circle

[0030] 11a Outer Diameter Surface

[0031] 13 Outer ring

[0032] 13a inner diameter surface

[0033] 15 ball bearings

[0034] 17, 17A, 17B cages

[0035] 17a Inner circumferential surface

[0036] 17b Outer Peripheral Surface

[0037] 21 Inner ring raceway surface

[0038] 23 Outer ring raceway surface

[0039] 25 pockets

[0040] 27 Cylindrical surface

[0041] 31 One side

[0042] 33 The other side

[0043] 100 ball bearings

[0044] Ta, Tb thickness

[0045] α contact angle

[0046] β tilt angle Detailed Implementation

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0048] Figure 1 This is a partial axial cross-sectional view of the ball bearing 100 of the present invention, which is a structural example.

[0049] like Figure 1 As shown, the ball bearing 100 according to this embodiment includes an inner ring 11, an outer ring 13, balls 15, and a cage 17. This ball bearing 100 is suitable, for example, for use as a bearing for a high-speed rotating shaft in dental air turbines, cleaners, turbochargers, etc.

[0050] The inner ring 11 has an inner ring raceway surface 21 on its outer circumference, and the outer ring 13 has an outer ring raceway surface 23 on its inner circumference. Multiple balls 15 are disposed between the inner ring raceway surface 21 and the outer ring raceway surface 23. The cage 17 has multiple pockets 25. The balls 15 are housed in these pockets 25 and are held in a rolling manner within the pockets 25. When an axial preload is applied, the balls 15 held in the pockets 25 of the cage 17 roll freely between the inner ring raceway surface 21 and the outer ring raceway surface 23 at a contact angle α. The balls 15 rolling freely at the contact angle α rotate around a rotation axis R orthogonal to the contact angle α while revolving around it. It should be noted that the contact angle α of the ball bearing 100 is the angle formed by the normal at the contact point between the ball 15 and the outer ring 13 (or inner ring 11) and a plane perpendicular to the axis of the ball bearing 100.

[0051] In addition, the outer diameter surface 11a of the inner ring 11 has the same outer diameter on both sides of the axial direction that sandwiches the inner ring raceway surface 21, that is, on one side and the other side.

[0052] like Figure 2 As shown in (A) and (B), the cage 17 is formed in an annular shape, with a plurality of pockets 25 spaced apart circumferentially. The cage 17 is made of, for example, metal or synthetic resin. The cage 17 is a cage with cylindrical pockets 25 extending through the front and back, each pocket 25 having a cylindrical surface 27. Furthermore, the number of pockets 25 may not necessarily be the same as the number of balls 15. Additionally, the cage 17 can be any of the following: a cutting die that forms the pockets 25 through machining, a stamping die that punches a metal sheet using a die, or a molding die that forms the shape by flowing resin into the die. If the inner diameter of the pockets 25 of the cage 17 is 1.03 to 1.2 times the outer diameter of the balls 15, high-speed rotation performance can be achieved.

[0053] In addition, such as Figure 1 As shown, the inner circumferential surface 17a of the retainer 17 has the same inner diameter on both one axial side 31 and the other axial side 33. Furthermore, the radial thickness Ta on one axial side 31 of the retainer 17 and the radial thickness Tb on the other axial side 33 have the same dimensions.

[0054] In this example, the cage 17 can be an inner ring guided cage in which its inner circumferential surface 17a is guided by the outer diameter surfaces 11a on both sides of the inner ring raceway surface 21 in the axial direction. In this case, the inner circumferential surface 17a of the cage 17 is guided by the outer diameter surfaces 11a of the inner ring 11, which have the same outer diameter on both sides of the inner ring raceway surface 21 in the axial direction. In addition, the inner circumferential surface 17a of the cage 17 guided by the outer diameter surface 11a of the inner ring 11 has the same inner diameter on one side 31 and the other side 33 in the axial direction. As a result, the cage 17 guided by the outer diameter surface 11a of the inner ring 11 is less likely to tilt relative to the inner ring 11. Furthermore, the radial thickness Ta on one side 31 and the radial thickness Tb on the other side 33 of the axial direction of the cage 17 are the same size. As a result, the axial balance of the cage 17 guided by the outer diameter surface 11a of the inner ring 11 becomes equal, making it more difficult to tilt relative to the inner ring 11.

[0055] Alternatively, the cage 17 can be an outer ring guided cage, where the outer circumferential surface 17b is guided by the inner diameter surface 13a of the shoulder of the outer ring 13. Furthermore, although not shown in the figure, the inner circumferential surface of the outer ring can also have the same diameter on both axial sides of the outer ring raceway surface, with the cage 17 being an outer ring guided cage guided by the inner circumferential surface of the outer ring. However, in such cases, by using a crown-shaped cage, or by reducing the difference between the diameter of the outer ring raceway surface 23 and the diameter of the inner diameter surface 13a of the shoulder of the outer ring 13, or by reducing the difference between the diameter of the inner ring raceway surface 21 and the diameter of one or both sides of the outer diameter surface 11a of the inner ring 11, the ball bearing 100 can be easily assembled. The same applies to the cages described later.

[0056] like Figure 1 As shown, the cylindrical surface 27 of each pocket 25 of the retainer 17 is inclined at an angle β greater than 0 degrees. Furthermore, the point where the ball 15 within the pocket 25 intersects the cylindrical surface 27 with the surface passing through the center of the ball 15 and perpendicular to the angle β is the contact point CA. Additionally, the angle β of the cylindrical surface 27 is the same in all pockets 25.

[0057] In addition, the inclination angle β of the cylindrical surface 27 is smaller than the contact angle α of the ball 15 when axial preload is applied. That is, the inclination angle β of the cylindrical surface 27 of the pocket 25 is set to satisfy the following equation (1).

[0058] 0°<β<α (1)

[0059] As shown in equation (1) above, the inclination angle β of the cylindrical surface 27 of the pocket 25 (the angle between the radial direction of the cage 17 in the axial section of the bearing and the central axis of the cylindrical surface 27) is greater than 0°. Therefore, the contact point CA between the ball 15 and the cylindrical surface 27 is close to the rotation axis R of the ball 15, and thus the ball 15 contacts the pocket 25 at a relatively low rotational speed. Furthermore, the ratio Ct / Db of the dimension Ct between the contact point CA and the nearest end E of the pocket 25 to the diameter Db of the ball 15 is preferably 0.05 or more and 0.4 or less. Here, dimension Ct represents the length along the central axis of the cylindrical surface 27. That is, preferably, the ratio Ct / Db of the dimension Ct between the contact point CA and the nearest end E of the pocket 25 to the diameter Db of the ball 15 satisfies the following equation (2).

[0060] 0.05≤Ct / Db≤0.4 (2)

[0061] As shown in equation (2) above, when the ratio of the dimension Ct between the contact point CA and the nearest end E of the pocket 25 to the diameter Db of the ball, Ct / Db, is 0.05 or more and 0.4 or less, the area around the contact point CA where the ball 15 contacts the cylindrical surface 27 of the pocket 25 can be ensured to have a narrow gap between the ball 15 and the cylindrical surface 27 of the pocket 25. Therefore, sufficient lubricant can be ensured at the contact point CA where the ball 15 contacts the cylindrical surface 27 of the pocket 25.

[0062] Furthermore, as shown in equation (1) above, by making the inclination angle β of the cylindrical surface 27 of the pocket 25 smaller than the contact angle α, the space S from the contact point CA between the ball 15 and the cylindrical surface 27 to the circumferential surface on one side close to the cage 17 is expanded.

[0063] In addition, such as Figure 3 As shown in (A), the cylindrical surface 27 of the pocket 25 of the retainer 17 is inclined at an angle β relative to the radial direction of the retainer 17. Therefore, as Figure 3 As shown in (B), when viewed from the outer or inner periphery of the travel line L of the ball 15 inclined at the contact angle α, a balanced gap G is provided on both sides of the contact portion CB between the pocket 25 and the ball 15.

[0064] Here, we will explain Example 1.

[0065] Figure 4The ball bearing 201 shown in Reference Example 1 is a typical ball bearing in which the central axis of the pocket 25 of the cage 17 is parallel to the central axis along the radial direction of the cage 17. In this ball bearing 201, the contact point CA between the cylindrical surface 27 of the pocket 25 and the ball 15 is located relatively far from the rotation axis R. That is, the ball 15 contacts the cylindrical surface 27 of the pocket 25 of the cage 17 at a position with a high rotational speed.

[0066] Therefore, in the ball bearing 201 described in Reference Example 1, the following situations may occur: increased sliding friction between the ball 15 and the cage 17, reduced rotational torque, heat generation between the ball 15 and the cage 17, shortened lubricant life due to heat generation, wear of the cage 17, and vibration of the cage 17.

[0067] In contrast, according to the ball bearing 100 of this structural example, the inclination angle β of the cylindrical surface 27 of the pocket 25 is greater than 0. ° Thus, the contact point CA between the ball 15 and the cylindrical surface 27 is close to the rotation axis R of the ball 15. Therefore, the contact point CA becomes the part where the circumferential speed of the ball 15 is relatively small (refer to...). Figure 1 Therefore, it is possible to achieve improved bearing performance, including reduced sliding friction between the balls 15 and the cage 17, suppressed reduction in rotational torque, reduced heat generation between the balls 15 and the cage 17, extended lubricant life due to reduced heat generation, reduced wear of the cage 17, and reduced cage vibration. Furthermore, to achieve even greater improvements in bearing performance, 3 is preferred. ° <β, more preferably 5 ° <β.

[0068] In addition, such as Figure 5 As shown in (A), in the ball bearing 201 of Reference Example 1, the central axis P of the pocket 25 of the cage 17 is parallel to the central axis Q along the radial direction of the cage 17 (in Figure 5 (Under the same circumstances). Therefore, as Figure 5 As shown in (B), when viewed from the outer or inner circumferential side along the travel line L of the ball 15 inclined at contact angle α, the gap G on both sides of the contact portion CB between the pocket 25 and the ball 15 is different. Therefore, the lubrication of the lubricant between the ball 15 and the cylindrical surface 27 of the pocket 25 of the cage 17 becomes unstable, potentially causing vibration in the cage 17 or disrupting the rotational balance of the cage 17.

[0069] In contrast, in the ball bearing 100 of this structural example, the cylindrical surface 27 of the pocket 25 of the cage 17 is inclined at an angle β. Therefore, when viewed from the traveling portion of the ball 15, a nearly uniform gap G that achieves balance is provided on both sides of the contact portion CB between the pocket 25 and the ball 15 (see reference). Figure 3(A) and (B)). Thus, good lubrication can be achieved by using the lubricant between the ball 15 and the cylindrical surface 27 of the pocket 25 of the cage 17, suppressing vibration of the cage 17 and enabling the cage 17 to rotate in a balanced and good manner.

[0070] Next, we will explain reference example 2.

[0071] like Figure 6 As shown, in the ball bearing 202 described in Reference Example 2, the tilt angle β of the pocket 25 of the cage 17 is equal to the contact angle α when axial preload is applied. In this ball bearing 202, the space S from the contact point CA between the ball 15 and the cage 17 to the circumferential surface near one side of the cage 17 becomes narrower. Therefore, insufficient lubrication is not ensured at the contact portion between the cylindrical surface 27 of the pocket 25 of the cage 17 and the ball 15, which may lead to a decrease in bearing performance.

[0072] In contrast, according to the ball bearing 100 of this structural example, by making the inclination angle β of the cylindrical surface 27 of the pocket 25 smaller than the contact angle α, the space S from the contact point CA between the cylindrical surface 27 of the pocket 25 of the cage 17 and the ball 15 to the circumferential surface near one side of the cage 17 is widened (see reference). Figure 1 Therefore, by ensuring sufficient lubricant at the contact point CA between the ball 15 and the cage 17, improved bearing performance can be achieved, including reduced sliding friction between the ball 15 and the pocket 25 of the cage 17, reduced rotational torque, reduced heat generation between the ball 15 and the cage 17, extended lubricant life due to reduced heat generation, reduced wear of the cage 17, and reduced cage vibration. It should be noted that, to achieve an even greater improvement in bearing performance from this lubricant, it is preferable that (α-3°) > β, and more preferably (α-5°) > β.

[0073] Furthermore, in the above embodiment, a structure of a retainer 17 having a cylindrical pocket 25 extending through the back of the watch is illustrated, but the shape of the retainer 17 is not limited to having a cylindrical pocket 25 extending through the back of the watch.

[0074] For example, as a cage, such as Figure 7 As shown in (A) and (B), it can also be a crown-shaped retainer 17A with a pocket 25 open at one periphery. Additionally, Figure 8 The cage 17B shown in (A) and (B) is a crown-shaped cage, wherein the cylindrical surface 27 of the pocket 25 faces the outer periphery and is inclined at an angle β away from the open periphery.

[0075] Furthermore, in these cages 17A and 17B, since the inclination angle β of the cylindrical surface 27 of the pocket 25 is larger than 0° and smaller than the contact angle α of the ball 15 when axial preload is applied, the contact point CA between the ball 15 and the cylindrical surface 27 can be arranged in a part where the rotational speed of the ball 15 is relatively small. In addition, the space SA from the contact point CA between the ball 15 and the cylindrical surface 27 to the circumferential surface of the cage 17A and 17B that is closer to it can be expanded.

[0076] Furthermore, the ball bearing 100 in this structural example is not limited to the form, size, or internal specifications of deep groove ball bearings, angular contact bearings, etc.

[0077] Thus, the present invention is not limited to the above-described embodiments. Combining the various structures of the embodiments with each other, making changes and applications based on the description in the specification and known technologies, and being included in the scope of protection by those skilled in the art are also within the intended scope of the present invention.

[0078] As stated above, the following matters are disclosed in this specification.

[0079] (1) A ball bearing comprising:

[0080] Inner ring, the inner ring having an inner ring raceway surface on its outer periphery;

[0081] The outer ring has an outer ring raceway surface on its inner circumference;

[0082] A plurality of balls, wherein the plurality of balls are arranged in a rollable manner between the inner raceway surface and the outer raceway surface; and

[0083] A cage having a plurality of pockets spaced apart circumferentially, the plurality of pockets having cylindrical surfaces that hold the balls in a rolling manner, the cage having a circumferential surface guided by either the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, wherein...

[0084] The inclination angle β of the cylindrical surface of the pocket is greater than 0° and less than the contact angle α of the ball bearing, and the ball contacts the cylindrical surface at a position inside the cage thickness direction than the position where the rotation axis of the ball intersects with the cylindrical surface, thereby forming a space between the contact position and the cage circumferential surface on the side of the intersection.

[0085] According to this ball bearing, by making the inclination angle β of the cylindrical surface of the pocket greater than 0°, the ball contacts the pocket at a location where the ball's rotational speed is relatively low.

[0086] Furthermore, by making the inclination angle β of the cylindrical surface of the pocket smaller than the contact angle α of the ball when axial preload is applied, the space from the contact portion of the ball and the cage to the nearest circumferential surface of the cage is widened, which ensures sufficient lubrication at the contact portion of the ball and the cage.

[0087] As a result, the bearing performance can be improved by reducing sliding friction between the balls and the cage, suppressing rotational torque, reducing heat generation between the balls and the cage, extending the life of the lubricant due to reduced heat generation, reducing cage wear, and reducing cage vibration.

[0088] (2) The ball bearing according to (1), wherein the inner diameter surface of the outer ring or the outer diameter surface of the inner ring that guides the cage has the same diameter on both axial sides that sandwich the raceway surface of the outer ring or the raceway surface of the inner ring.

[0089] The outer circumferential surface of the cage guided by the inner diameter surface of the outer ring or the inner circumferential surface guided by the outer diameter surface of the inner ring has the same diameter on one side and the other side of the axial direction.

[0090] According to this ball bearing, the cage, guided by the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, is not easily tilted relative to the outer ring or the inner ring.

[0091] (3) The ball bearing according to (2), wherein the radial thickness of one side of the cage in the axial direction is the same as the radial thickness of the other side in the axial direction.

[0092] According to this ball bearing, the axial balance of the cage, guided by the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, is equal, making it less prone to tilting relative to the outer or inner ring.

[0093] Furthermore, this application is based on Japanese Patent Application No. 2021-62335, filed on March 31, 2021, the contents of which are incorporated herein by reference.

Claims

1. A ball bearing, characterized in that, have: Inner ring, the inner ring having an inner ring raceway surface on its outer periphery; The outer ring has an outer ring raceway surface on its inner circumference; Multiple balls are arranged between the inner raceway surface and the outer raceway surface in a manner that allows them to roll freely. as well as A cage having a plurality of pockets spaced apart circumferentially, the plurality of pockets having cylindrical surfaces that hold the balls in a rolling manner, the cage having a circumferential surface guided by either the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, wherein... The inclination angle β of the cylindrical surface of the pocket is greater than 0° and less than the contact angle α of the ball bearing. The ball contacts the cylindrical surface at a position inside the cage thickness direction, where the ball's rotation axis intersects the cylindrical surface, thereby forming a space between the contact position and the cage circumferential surface on the side of the intersection. The rotation axis of the ball intersects the cylindrical surface. The ratio of the dimension Ct between the contact point of the ball and the cylindrical surface and the nearest end of the pocket to the diameter Db of the ball, Ct / Db, is greater than 0.05 and less than 0.

4.

2. The ball bearing according to claim 1, characterized in that, The inner diameter surface of the outer ring or the outer diameter surface of the inner ring that guides the cage has the same diameter on both sides of the axial direction sandwiching the raceway surface of the outer ring or the raceway surface of the inner ring. The outer circumferential surface of the cage guided by the inner diameter surface of the outer ring or the inner circumferential surface guided by the outer diameter surface of the inner ring has the same diameter on one side and the other side of the axial direction.

3. The ball bearing according to claim 2, characterized in that, The radial thickness on one side of the cage along the axial direction is the same as the radial thickness on the other side along the axial direction.

Images