Jade Axis

Abstract

To provide a ball bearing which can suppress the lowering of bearing performance by making a contact portion between a pocket of a cage and a cylinder face secure a sufficient quantity of a lubricant.SOLUTION: A ball bearing 100 comprises: an inner ring 11 having an inner ring raceway surface 21 on an external periphery; an outer ring 13 having an outer ring raceway surface 23 on an internal periphery; a plurality of balls 15 rollably arranged between the inner ring raceway surface 21 and the outer ring raceway surface 23; and a cage 17 in which a plurality of pockets 25 having cylinder faces 27 for rollably holding the balls 15 are formed in a peripheral direction with intervals, and which has a peripheral face guided by an outside diameter face 11a of the inner ring 11. In the pocket 25, an inclination angle β of the cylinder face 27 is designed to be larger than 0°, and smaller than a contact angle α of the ball bearing 100, and the ball and the cylinder face contact with each other on an inner side in a cage thickness direction of a position in which a rotating axis of the ball and the cylinder face intersect so as to form a space between the contact position and a cage peripheral face on the intersection position side.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] For example, ball bearings such as angular contact ball bearings have a cage that is 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 so that they can roll freely (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-140870 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a ball bearing, in order to prevent a decrease in bearing performance such as bearing life, it is desirable to ensure that there is a sufficient amount of lubricant at the contact area between the cylindrical surface of the cage pocket and the balls. However, as in the ball bearing described in Patent Document 1, if the inclination angle between the axial direction of the retainer pocket and the radial direction of the bearing is equal to the contact angle when axial preload is applied to the bearing, sufficient lubricant may not be secured at the contact area between the cylindrical surface of the retainer pocket and the balls, which may result in a decrease in bearing performance.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a ball bearing capable of preventing deterioration of bearing performance by ensuring sufficient lubricant at the contact area between the cylindrical surface of the cage pocket and the balls. [Means for solving the problem]

[0006] The present invention comprises the following configurations. an inner ring having an inner ring raceway on an outer periphery thereof; an outer ring having an outer ring raceway on an inner circumference; a plurality of balls rollably disposed between the inner ring raceway surface and the outer ring raceway surface; a cage having a peripheral surface in which a plurality of pockets having cylindrical surfaces for holding the balls in a freely rolling manner are formed at intervals in a circumferential direction and which is guided by an inner diameter surface of the outer ring or an outer diameter surface of the inner ring; A ball bearing comprising: The pocket has an inclination angle β of the cylindrical surface that is greater than 0° and smaller than the contact angle α of the ball bearing, and the ball and the cylindrical surface contact each other further inward in the thickness direction of the retainer 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 peripheral surface of the retainer on the side of the intersecting position. Effect of the Invention

[0007] According to the present invention, a sufficient amount of lubricant can be secured at the contact portion between the cylindrical surface of the pocket of the cage and the balls, thereby suppressing deterioration of bearing performance. [Brief description of the drawings]

[0008] [Figure 1] 1 is a partial cross-sectional view along the axial direction of a ball bearing according to an embodiment of the present invention; [Diagram 2] 1A and 1B are diagrams showing a cage, in which (A) is a perspective view and (B) is a cross-sectional view taken along the axial direction. [Diagram 3] 13A is a perspective view of the pocket portion in cross section along the axial direction as viewed from the outer periphery of the cage, and FIG. 13B is a view viewed from the X arrow in FIG. 13A. [Figure 4] 3 is a schematic cross-sectional view along the axial direction of the cage, showing the state in which balls are held in pockets of the ball bearing according to Reference Example 1. FIG. [Diagram 5] 1A and 1B are diagrams showing the retaining state of balls in a retainer according to Reference Example 1, in which (A) is an oblique view seen from the outer periphery of the retainer in a cross-section along the axial direction at the pocket portion, and (B) is a view seen from the Y arrow direction in (A). [Figure 6] 11 is a schematic cross-sectional view along the axial direction of the cage, showing the state in which balls are held in pockets of a ball bearing according to Reference Example 2. FIG. [Figure 7] 13A and 13B are views showing a retainer of another shape, in which (A) is a perspective view and (B) is a cross-sectional view taken along the axial direction. [Figure 8] 13A and 13B are views showing a retainer of another shape, in which (A) is a perspective view and (B) is a cross-sectional view taken along the axial direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial cross-sectional view along the axial direction of a ball bearing 100 according to an embodiment of the present invention.

[0010] 1, a 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 use as a bearing for a shaft that rotates at high speed in, for example, a dental air turbine, a cleaner, a turbocharger, or the like.

[0011] 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. A plurality of balls 15 are arranged between the inner ring raceway surface 21 and the outer ring raceway surface 23. The cage 17 has a plurality of pockets 25, in which the balls 15 are accommodated and held so as to be free to roll. The balls 15 held in the pockets 25 of the cage 17 are free to roll at a contact angle α between the inner ring raceway surface 21 and the outer ring raceway surface 23 when an axial preload is applied. The balls 15, which are free to roll at this contact angle α, revolve around the rotation axis R, which is perpendicular to the contact angle α, while rotating. The contact angle α of the ball bearing 100 is the angle that the normal line at the contact point between the balls 15 and the outer ring 13 (or the inner ring 11) forms with a plane perpendicular to the axis of the ball bearing 100.

[0012] Moreover, the outer diameter surface 11a of the inner ring 11 has the same outer diameter on both sides in the axial direction that sandwich the inner ring raceway surface 21 therebetween.

[0013] As shown in (A) and (B) of FIG. 2, the cage 17 is formed in an annular shape, and a plurality of pockets 25 are formed at intervals in the circumferential direction. The cage 17 is formed of, for example, metal or synthetic resin. The cage 17 is a cage in which cylindrical pockets 25 penetrate from the front to the back, and each pocket 25 has a cylindrical surface 27. The number of pockets 25 does not necessarily have to match the number of balls 15. The cage 17 may be a milling die in which the pockets 25 are formed by machining, a punching die in which a metal plate is punched with a die, or a molding die in which resin is poured into a 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 satisfied.

[0014] 1, the inner diameter of the inner circumferential surface 17a of the cage 17 is the same on one axial side 31 and the other axial side 33. Furthermore, the cage 17 has a radial thickness Ta on one axial side 31 and a radial thickness Tb on the other axial side 33, which are the same.

[0015] The cage 17 of this example may be an inner ring guide type cage in which the inner peripheral surface 17a is guided by the outer diameter surface 11a on both sides in the axial direction with respect to the inner ring raceway surface 21 of the inner ring 11. In this case, the inner peripheral surface 17a of the cage 17 is guided by the outer diameter surface 11a of the inner ring 11, which has the same outer diameter on both sides in the axial direction sandwiching the inner ring raceway surface 21. Furthermore, the inner peripheral 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 in the axial direction and the other side 33 in the axial direction. Therefore, the cage 17 guided by the outer diameter surface 11a of the inner ring 11 is less likely to tilt with respect to the inner ring 11. Furthermore, the cage 17 has the same radial thickness Ta on one side 31 in the axial direction and the same radial thickness Tb on 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 evenly balanced in the axial direction, making it less likely to tilt relative to the inner ring 11.

[0016] The cage 17 may be an outer ring guide cage in which the outer peripheral surface 17b is guided by the inner diameter surface 13a of the shoulder of the outer ring 13. Furthermore, although not shown, the inner peripheral surface of the outer ring may be the same diameter on both axial sides of the outer ring raceway surface, and the cage 17 may be an outer ring guide cage in which the inner peripheral surface of the outer ring is guided by the inner peripheral surface of the outer ring. In such a case, the ball bearing 100 can be easily assembled by using a crown-type cage, reducing the difference between the diameter of the outer ring raceway surface 23 and the diameter of the inner peripheral surface 13a of the shoulder of the outer ring 13, or reducing the difference between the diameter of the inner ring raceway surface 21 and the diameter of one or both sides of the outer peripheral surface 11a of the inner ring 11. This also applies to the cages described below.

[0017] 1, the cylindrical surface 27 of each pocket 25 of the cage 17 is inclined at an inclination angle β greater than 0 degrees. The balls 15 in this pocket 25 contact the cylindrical surface 27 at a point CA where a plane that passes through the center of the ball 15 and is perpendicular to the inclination angle β intersects with the cylindrical surface 27. The inclination angle β of the cylindrical surface 27 is the same for all the pockets 25.

[0018] Further, the inclination angle β of the cylindrical surface 27 is smaller than the contact angle α of the balls 15 when an axial preload is applied. In other words, the inclination angle β of the cylindrical surface 27 of the pocket 25 is set to an angle that satisfies the following formula (1).

[0019] 0°<β<α …(1)

[0020] As shown in the above equation (1), since the inclination angle β of the cylindrical surface 27 of the pocket 25 is greater than 0°, 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 the ball 15 comes into contact with the pocket 25 at a point where the rotational peripheral speed of the ball 15 is relatively small. Furthermore, it is preferable that 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 balls 15 of the cage 17 is 0.05 or more and 0.4 or less. In other words, it is preferable that 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 balls 15 satisfies the following formula (2). 0.05≦Ct / Db≦0.4 …(2) As shown in the above formula (1), when the ratio Ct / Db of the dimension Ct between the contact point CA and the nearest end E of the pocket 25 to the ball diameter Db is set to be 0.05 or more and 0.4 or less, an area where the distance between the ball 15 and the cylindrical surface 27 of the pocket 25 is narrow can be secured around the contact point CA where the ball 15 and the cylindrical surface 27 of the pocket 25 contact. Therefore, a sufficient amount of lubricant can be secured at the contact point CA where the ball 15 and the cylindrical surface 27 of the pocket 25 contact.

[0021] Furthermore, as shown in the above formula (1), since the inclination angle β of the cylindrical surface 27 of the pocket 25 is 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 near side peripheral surface of the cage 17 is made wider.

[0022] 3A, the cylindrical surface 27 of the pocket 25 of the cage 17 is inclined at an inclination angle β. Therefore, as shown in FIG. 3B, when viewed from the outer circumferential side or the inner circumferential side along the running line L of the ball 15 inclined at a 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.

[0023] Here, the reference example 1 will be described. 4, ball bearing 201 according to Reference Example 1 is a typical ball bearing in which the central axis of pocket 25 of cage 17 is parallel to the central axis along the radial direction of cage 17. In this ball bearing 201, contact point CA between cylindrical surface 27 of pocket 25 and ball 15 is located at a position far away from rotation axis R. In other words, ball 15 comes into contact with cylindrical surface 27 of pocket 25 of cage 17 at a position where the rotational circumferential speed is high.

[0024] As a result, in the ball bearing 201 of Reference Example 1, there is a risk of increased sliding friction between the balls 15 and the retainer 17, a decrease in rotational torque, heat generation between the balls 15 and the retainer 17, a shortened lifespan of the lubricant due to heat generation, wear of the retainer 17, and vibration of the retainer 17.

[0025] In contrast, according to the ball bearing 100 of this configuration example, the inclination angle β of the cylindrical surface 27 of the pocket 25 is greater than 0°, so that the contact point CA between the balls 15 and the cylindrical surface 27 is close to the rotation axis R of the balls 15, and is therefore a location where the rotational peripheral speed of the balls 15 is relatively slow (see FIG. 1). Therefore, it is possible to obtain a greater improvement in bearing performance, such as a reduction in sliding friction between the balls 15 and the cage 17, suppression of a decrease in rotational torque, a reduction in heat generation between the balls 15 and the cage 17, an extension of the lubricant life due to the reduction in heat generation, a reduction in wear of the cage 17, and a reduction in vibration of the cage. In order to obtain a greater improvement in bearing performance, it is preferable that β be 3°<β, and more preferably 5°<β.

[0026] 5A, in the ball bearing 201 according to 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 (coincident in the case of FIG. 5). Therefore, as shown in FIG. 5B, when viewed from the outer circumferential side or the inner circumferential side along the running line L of the balls 15 inclined at the contact angle α, the gap G on both sides of the contact portion CB between the pocket 25 and the balls 15 is different. This makes the lubrication by the lubricant between the balls 15 and the cylindrical surface 27 of the pocket 25 of the cage 17 unstable, and there is a risk that the cage 17 will vibrate or the rotational balance of the cage 17 will be lost.

[0027] In contrast, in the ball bearing 100 of this configuration example, the cylindrical surface 27 of the pocket 25 of the retainer 17 is inclined at an inclination angle β, so that a nearly uniform and well-balanced gap G is provided on both sides of the contact portion CB between the pocket 25 and the balls 15 as viewed from the running portion of the balls 15 (see FIGS. 3A and 3B). This enables good lubrication by the lubricant between the balls 15 and the cylindrical surface 27 of the pocket 25 of the retainer 17, suppresses vibration of the retainer 17, and allows the retainer 17 to rotate in a well-balanced manner.

[0028] Next, a second reference example will be described. 6, in a ball bearing 202 according to Reference Example 2, the inclination angle β of pocket 25 of retainer 17 is set equal to the contact angle α when axial preload is applied. In this ball bearing 202, the space S from contact point CA between ball 15 and retainer 17 to the circumferential surface of retainer 17 on the closer side becomes narrow. As a result, sufficient lubricant is not secured at the contact portion between cylindrical surface 27 of pocket 25 of retainer 17 and ball 15, which may lead to a deterioration in bearing performance.

[0029] In contrast, according to the ball bearing 100 of this configuration example, the inclination angle β of the cylindrical surface 27 of the pocket 25 is smaller than the contact angle α, so that the space S from the contact point CA between the cylindrical surface 27 of the pocket 25 of the cage 17 and the balls 15 to the circumferential surface on the near side of the cage 17 is widened (see FIG. 1). This allows a sufficient amount of lubricant to be secured at the contact point CA between the balls 15 and the cage 17, and improves the bearing performance by reducing sliding friction between the balls 15 and the pocket 25 of the cage 17, suppressing the decrease in rotational torque, reducing heat generation between the balls 15 and the cage 17, extending the life of the lubricant due to the reduced heat generation, reducing wear of the cage 17, and reducing vibration of the cage. In order to obtain a greater improvement in the bearing performance due to this lubricant, it is preferable that (α-3°)>β, and more preferably that (α-5°)>β.

[0030] In the above embodiment, a structure including a retainer 17 having a cylindrical pocket 25 penetrating from the front to the back is exemplified, but the shape of the retainer 17 is not limited to one having a cylindrical pocket 25 penetrating from the front to the back.

[0031] For example, the cage may be a crown-shaped cage 17A in which a pocket 25 is open on one circumferential edge as shown in (A) and (B) of Figures 7. Also, a cage 17B shown in (A) and (B) of Figures 8 is a crown-shaped cage in which a cylindrical surface 27 of a pocket 25 is inclined at an inclination angle β toward the outer periphery in a direction away from the open one circumferential edge.

[0032] In these retainers 17A, 17B, the inclination angle β of the cylindrical surface 27 of the pocket 25 is greater than 0° and smaller than the contact angle α of the balls 15 when axial preload is applied, so that the contact point CA between the balls 15 and the cylindrical surface 27 can be made a point where the rotational peripheral speed of the balls 15 is relatively slow, and the space SA from the contact point CA between the balls 15 and the cylindrical surface 27 to the closer peripheral surface of the retainers 17A, 17B can be made wider.

[0033] Furthermore, the ball bearing 100 of this configuration example may be a deep groove ball bearing or an angular contact bearing, and the type, size, and internal specifications are not limited.

[0034] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates mutual combinations of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the descriptions in the specification and well-known technologies, and these are included in the scope of protection sought.

[0035] As described above, the present specification discloses the following: (1) an inner ring having an inner ring raceway on its outer periphery; an outer ring having an outer ring raceway on an inner circumference; a plurality of balls rollably disposed between the inner ring raceway surface and the outer ring raceway surface; a cage having a peripheral surface in which a plurality of pockets having cylindrical surfaces for holding the balls in a freely rolling manner are formed at intervals in a circumferential direction and which is guided by an inner diameter surface of the outer ring or an outer diameter surface of the inner ring; A ball bearing comprising: The pocket has an inclination angle β of the cylindrical surface that is greater than 0° and smaller than the contact angle α of the ball bearing, and the ball and the cylindrical surface contact each other further inward in the thickness direction of the retainer 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 peripheral surface of the retainer on the side of the intersecting position. In this ball bearing, the inclination angle β of the cylindrical surface of the pocket is greater than 0°, so that the balls come into contact with the pocket at locations where the rotational peripheral speed of the balls is relatively slow. Furthermore, since the inclination angle β of the cylindrical surface of the pocket is smaller than the contact angle α of the ball when axial preload is applied, the space from the contact point between the ball and the cage to the nearest circumferential surface of the cage is wider, ensuring sufficient lubricant at the contact point between the ball and the cage. This results in improved bearing performance, including reduced sliding friction between the balls and the cage, suppressed reduction in rotational torque, reduced heat generation between the balls and the cage, extended lubricant life due to reduced heat generation, reduced cage wear, and reduced cage vibration.

[0036] (2) The inner diameter surface of the outer ring or the outer diameter surface of the inner ring, which guides the cage, has the same diameter on both sides of the outer ring raceway surface or the inner ring raceway surface, The ball bearing according to (1), wherein the retainer has an outer peripheral surface that is guided by the inner diameter surface of the outer ring or an inner peripheral surface that is guided by the outer diameter surface of the inner ring, the outer peripheral surface having the same diameter on one axial side and the other axial side. According to this ball bearing, the cage, which is guided by the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, is less likely to tilt relative to the outer ring or the inner ring.

[0037] (3) The ball bearing according to (2), wherein the cage has a radial thickness on one axial side that is the same as a radial thickness on the other axial side. According to this ball bearing, the axial balance of the cage, which is guided by the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, is even, making it less likely to tilt relative to the outer ring or inner ring. [Explanation of symbols]

[0038] 11. Inner Circle 11a Outer diameter surface 13 Outer ring 13a Inner diameter surface 15 balls 17,17A,17B retainer 17a Inner surface 17b Outer surface 21 Inner ring raceway surface 23 Outer ring raceway surface 25 Pocket 27 Cylindrical Surface 31 One side 33 Other side 100 ball bearings Ta,Tb thickness α contact angle β Tilt angle

Claims

1. an inner ring having an inner ring raceway on an outer periphery thereof; an outer ring having an outer ring raceway on an inner circumference; a plurality of balls rollably disposed between the inner ring raceway surface and the outer ring raceway surface; a cage having a peripheral surface guided by an inner diameter surface of the outer ring or an outer diameter surface of the inner ring, the cage including a plurality of pockets formed at intervals in a circumferential direction and each having a cylindrical surface for holding the balls in a rollable manner, the cage comprising: the pocket has an inclination angle β of the cylindrical surface that is greater than 0° and smaller than a contact angle α of the ball bearing, and the ball comes into contact with the cylindrical surface on the inner side in the thickness direction of the cage than a 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 intersecting position side, the inner diameter surface of the outer ring or the outer diameter surface of the inner ring, which guides the cage, has the same diameter on both sides of the outer ring raceway surface or the inner ring raceway surface, A ball bearing in which the retainer has an outer peripheral surface guided by the inner diameter surface of the outer ring or an inner peripheral surface guided by the outer diameter surface of the inner ring, the outer peripheral surface having the same diameter on one axial side and the other axial side.

2. The cage has a radial thickness on one side in the axial direction that is equal to a radial thickness on the other side in the axial direction.

2. A ball bearing according to claim 1.

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