Cage for rolling bearing

Abstract

To prevent the occurrence of oil shortage even under severe operating conditions by causing the residence of lubricating oil incorporated into a bearing.SOLUTION: A cage, which is used for a rolling bearing including an outer ring 1 and an inner ring 2, and a plurality of balls 3 arranged between the outer ring 1 and the inner ring 2, includes a circular ring part 21, and a plurality of pillar parts 22 protruded from the circular ring part 21 in the axial direction of the bearing, and further includes pockets 23 formed between the pillar parts 22, 22 neighboring each other in the peripheral direction of the bearing to hold the balls 3. The radius of the circular arc of a radial inner peripheral face D of the pocket 23 in a cross section passing through a pocket center p of the pocket 23 and including a bearing center line o is set smaller than 1 / 2 of a diameter φx of the ball 3 in the whole area of the radial inner peripheral face D.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a cage for use in a rolling bearing, and to a rolling bearing equipped with the cage. [Background technology]

[0002] For example, many rolling bearings are used in motor shafts of transmissions (speed-up / down gears) equipped with drive motors in various vehicles such as automobiles and construction machines, as well as in various industrial machines, etc. The rolling bearings used in these devices are generally used under high-speed conditions compared to bearings used to support shafts in general devices.

[0003] Furthermore, ball bearings that use balls as rolling elements often use plastic crown cages, which generally have a ring portion and multiple columns (protrusions) protruding from the ring portion in the axial direction of the bearing, with the protruding ends of the columns forming claws that hold the balls.

[0004] Incidentally, it is expected that the viscosity of lubricating oil will become lower in the future for rolling bearings used under high-speed conditions, such as electric vehicles. For this reason, it is expected that the oil film formed between the cage and the rolling elements will become more difficult to form than before. Even in such a harsh environment, it is important to provide an oil reservoir on the inner surface of the cage to retain the oil.

[0005] In Patent Document 1, a through groove is provided from the annular portion of the crown type cage to the inner surface of the pocket. This makes it possible for the lubricating oil adhering to the annular portion to flow directly into the inner surface of the pocket, which is said to prevent a lack of oil between the rolling elements and the ring, even in high-speed rotation environments, and to prevent seizure and wear. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2022-164434 A Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1, it is possible to make the lubricating oil adhering to the annular part of the cage flow into the inner surface of the pocket through the through groove. However, the lubricating oil that flows in cannot accumulate around the cage or inside the bearing, and is actively discharged to the outside of the bearing. For this reason, if the ratio of lubricating oil discharged is greater than the ratio of lubricating oil flowing in, the oil film between the cage and the rolling elements may break, leading to seizure and wear. This tendency is considered to be particularly pronounced when the amount of lubricating oil supplied is small, or when the bearing is in a lean lubrication state where less lubricating oil penetrates the bearing due to high-speed rotation.

[0008] Therefore, an object of the present invention is to retain the lubricating oil taken into the bearing and prevent oil shortage even under severe operating conditions. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a retainer that is used in a rolling bearing having an outer ring, an inner ring, and a plurality of balls arranged between the outer ring and the inner ring, and that has a circular ring portion and a plurality of column portions protruding from the circular ring portion in the axial direction of the bearing, and that has pockets for holding the balls formed between adjacent column portions in the circumferential direction of the bearing, wherein the radius of the arc of the radial inner surface of the pocket in a cross section that passes through the center of the pocket and includes the bearing center line is set to be smaller than 1 / 2 the diameter φx of the balls over the entire radial inner surface (configuration 1).

[0010] In an embodiment having configuration 1, a configuration can be adopted in which the radial inner surface coincides with an imaginary line formed by an ellipse having a radial pocket minor axis smaller than the diameter φx of the ball in the radial direction of the bearing and an axial pocket major axis larger than the diameter φx of the ball in the axial direction of the bearing (configuration 2).

[0011] Furthermore, in an embodiment having configuration 1, or an embodiment having configurations 1 and 2, a configuration can be adopted in which the radius of the arc of the circumferential inner surface of the pocket in a cross section passing through the center of the pocket and perpendicular to the bearing center line is set to be smaller than 1 / 2 the diameter φx of the ball over the entire area of ​​the circumferential inner surface (configuration 3).

[0012] In an embodiment equipped with configuration 3, a configuration can be adopted in which the circumferential inner surface of the pocket in a cross section passing through the center of the pocket and perpendicular to the center line of the bearing coincides with an imaginary line formed by an ellipse having a radial pocket minor axis smaller than the diameter φx of the ball in the radial direction of the bearing and a circumferential pocket major axis larger than the diameter φx of the ball in the tangential direction to the circumferential direction of the bearing (configuration 4).

[0013] Here, in an embodiment including configuration 1 and configuration 2, a configuration can be adopted in which the ratio of the radial pocket minor axis to the axial pocket major axis is equal to or greater than 0.83 and less than 0.97 (configuration 5).

[0014] In an embodiment including configuration 4, a configuration can be adopted in which the ratio of the radial pocket minor axis to the circumferential pocket major axis is equal to or greater than 0.83 and less than 0.97 (configuration 6).

[0015] Furthermore, in an embodiment having configuration 1, the radial inner surface coincides with an imaginary line formed by an ellipse having a radial pocket minor axis smaller than the ball diameter φx in the radial direction of the bearing and an axial pocket major axis larger than the ball diameter φx in the axial direction of the bearing, and the circumferential inner surface of the pocket in a cross section passing through the pocket center and perpendicular to the bearing center line coincides with an imaginary line formed by an ellipse having a radial pocket minor axis smaller than the ball diameter φx in the radial direction of the bearing and a circumferential pocket major axis larger than the ball diameter φx in the tangential direction to the circumferential direction of the bearing, and the ellipse of the imaginary line of the radial inner surface and the ellipse of the imaginary line of the circumferential inner surface have their centers coincident with each other (configuration 7).

[0016] In a configuration having configuration 1, or in a configuration in which a single or multiple elements selected from configurations 2 to 7 are added to configuration 1, a configuration can be adopted in which the radius of the arc of the radially inner surface is 0.86 or more and less than 0.98 with respect to 1 / 2 of the diameter φx of the ball over the entire area of ​​the radially inner surface (configuration 8).

[0017] Furthermore, in a configuration having configuration 1, or in a configuration in which a single or multiple elements selected from configurations 2 to 8 are added to configuration 1, a configuration can be adopted in which the outer diameter surfaces of the retainer of the annular portion and the column portion are inclined in the inner diameter direction from the annular portion side toward the protruding end side of the column portion (configuration 9).

[0018] A bearing device can be adopted in which a rolling bearing using a retainer having the above configuration 1, or in which a single or multiple elements selected from configurations 2 to 9 are added to configuration 1, is applied to support a motor shaft or a reducer shaft to which the driving force of an automobile drive motor is transmitted (configuration 10). Effect of the Invention

[0019] According to this invention, the lubricating oil taken into the bearing can be retained, and oil shortage can be prevented even under severe operating conditions. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a front view showing an embodiment of the present invention; [Diagram 2] Cross-sectional view of Fig. 1 along line II-II [Diagram 3] Cross-sectional view showing the main part of the cage [Figure 4] IV-IV cross section of Figure 3 [Diagram 5] Cross-sectional view showing the main part of the cage [Figure 6] FIG. 11 is a cross-sectional view showing a modified example of the retainer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An embodiment of the present invention will be described with reference to the drawings. This embodiment relates to a rolling bearing 10 that supports the rotating shaft of a drive motor equipped in an electric transport device such as an electric vehicle, or the rotating shaft of a reducer or speed increaser equipped in such an electric transport device, a bearing device using the rolling bearing 10 to support a shaft, and a cage 20 used in the rolling bearing 10.

[0022] As shown in Figures 1 and 2, the rolling bearing 10 includes an outer ring 1, an inner ring 2, a plurality of rolling elements 3 arranged between the outer ring 1 and the inner ring 2, and a cage 20 having pockets 23 that hold the rolling elements 3 in the circumferential direction. Since spheres (steel balls) are used as the rolling elements 3, they will be referred to as balls 3 below. In addition, this rolling bearing 10 will be referred to simply as bearing 10 below. The direction along the bearing center line o of the bearing 10 will be referred to as the "axial direction of the bearing" or simply as the "axial direction", the direction perpendicular to the axial direction will be referred to as the "radial direction of the bearing" or simply as the "radial direction", and the circumferential direction around the bearing center line o will be referred to as the "circumferential direction of the bearing" or simply as the "circumferential direction".

[0023] The cage 20 is a crown-type cage molded from engineering plastic. The cage 20 includes an annular portion 21 and a plurality of column portions 22 protruding from the annular portion 21 in the axial direction. The column portions 22 are provided at regular intervals along the circumferential direction. A concave pocket 23 for holding the balls 3 is formed between each pair of column portions 22 adjacent to each other in the circumferential direction. The outer diameter surface of the cage 20 (cage outer diameter surface 25) is preferably a curved surface (cylindrical surface or conical surface) without steps. The outer diameter surface and the inner diameter surface of the cage 20 are connected at the pocket 23. The material of the cage 20 is preferably, for example, polyamide resin (PA46, PA66, PA9T, etc.) or polyphenylene sulfide resin (PPS).

[0024] The protruding end of the pillar portion 22 is a retaining claw 22a. The retaining claws 22a, 22a on both sides of the pocket 23 are curved in a direction approaching each other. Adjacent pillar portions 22, 22 may be connected to each other between adjacent pockets 23 in the circumferential direction. The balls 3 held by the pocket 23 revolve between the raceway surface 1a of the outer ring 1 and the raceway surface 2a of the inner ring 2 while being held by the pocket 23.

[0025] The inner ring 2 has an unillustrated shaft fixed to its inner diameter portion 2b, and rotates in the circumferential direction together with the shaft. The outer ring 1 is attached to a fixed member, such as a housing or gear, also unillustrated, that bears the load from the shaft. In this way, the bearing 10 supports the shaft rotatably relative to the fixed member. Examples of the shaft include the rotating shaft of a drive motor equipped in an electric transport device such as an electric vehicle, or the rotating shaft of a reducer or speed increaser equipped in such an electric transport device. The bearing center axis of the bearing 1 and the rotating center axis of the rotating shaft are set coaxially.

[0026] Here, as shown in FIG. 3, the radius of the circular arc of the radial inner peripheral surface D of the pocket 23 in a vertical section (radial section) passing through the pocket center p of the pocket 23 and including the bearing center line o is set to be smaller than 1 / 2 the diameter φx of the ball 3 over the entire area of ​​the radial inner peripheral surface D. Therefore, a gap is generated between the inner diameter side end d1 and the outer diameter side end d2 of the radial inner peripheral surface D where the pocket 23 and the ball 3 do not come into contact, and the gap can hold (store) the lubricating oil, and the gap can also discharge the lubricating oil along the circumferential direction. This makes it possible to prevent oil shortage even under lean lubrication. The method of measuring the pocket center p can use a three-dimensional measuring machine as a measuring device. Measurement method: In the present invention, the target pocket curved surface is measured by a three-dimensional measuring machine. As the measurement points, multiple points (four or more) are measured near the inner circumference side and near the outer circumference side of the cage (imagine the vicinity where the perfect circles are in contact in FIGS. 3 and 4), and the center point of the imaginary sphere derived from the results is set as p.

[0027] In addition, in order to facilitate understanding, in Figs. 3 to 5, the differences in diameter (radius) of each circular arc and the positional relationship between the centers of the circular arcs are exaggerated.

[0028] In this embodiment, the radial inner circumferential surface D coincides with an imaginary line R configured as an ellipse having a radial pocket minor diameter a in the radial direction of the bearing that is smaller than the diameter φx of the balls 3, and an axial pocket major diameter c in the axial direction of the bearing that is larger than the diameter φx of the balls 3. Since the ellipse has the largest curvature (smallest curve radius) near the intersection with the major diameter, the vicinity of the intersection with the major diameter where this curvature is large faces the perfect circle of the balls 3, thereby ensuring a larger gap between the inner diameter end d1 and the outer diameter end d2 of the radial inner circumferential surface D.

[0029] 4, the radius of the arc of the circumferential inner surface E of pocket 23 in a cross section passing through pocket center p and perpendicular to the bearing center line o is set to be smaller than 1 / 2 the diameter φx of ball 3 over the entire area of ​​the circumferential inner surface E. For this reason, just like the case of the radial inner surface D, a gap is created between the inner diameter end and the outer diameter end of the circumferential inner surface E, where pocket 23 and ball 3 do not come into contact, and lubricating oil can be held (stored) in that gap.

[0030] Furthermore, in this embodiment, the circumferential inner surface E coincides with an imaginary line R configured as an ellipse having a radial pocket minor axis a in the radial direction of the bearing that is smaller than the diameter φx of the balls 3, and a circumferential pocket major axis b in the tangential direction to the circumferential direction of the bearing that is larger than the diameter φx of the balls 3. Similarly, the vicinity of the intersection with the major axis, which has a large curvature, faces the perfect circle of the balls 3, ensuring a larger gap between the inner diameter end and the outer diameter end of the circumferential inner surface E.

[0031] Here, the pocket center p and the center of the ball 3 are designed to coincide. Also, the centers of the ellipse of the virtual line R of the radial inner peripheral surface D and the ellipse of the virtual line R of the circumferential inner peripheral surface E coincide with each other. However, it is also possible to make the center of the ellipse of the virtual line R of the radial inner peripheral surface D and the center of the ellipse of the virtual line R of the circumferential inner peripheral surface E different from each other. Also, in this embodiment, the radial pocket minor diameter a of the radial inner peripheral surface D and the radial pocket minor diameter a of the circumferential inner peripheral surface E are made to coincide, but they may be made to differ from each other. Furthermore, in this embodiment, the axial pocket major diameter c of the radial inner peripheral surface D and the circumferential pocket major diameter b of the circumferential inner peripheral surface E are made to coincide, but they may be made to differ from each other.

[0032] Here, it is desirable that the ratio of the radial pocket minor diameter a to the axial pocket major diameter c on the radial inner peripheral surface D be 0.83 or more and less than 0.97.

[0033] Similarly, the ratio of the radial pocket minor diameter a to the circumferential pocket major diameter b on the circumferential inner surface E is preferably equal to or greater than 0.83 and less than 0.97.

[0034] Because the axial pocket major diameter c and the circumferential pocket major diameter b are larger than the diameter φx of the balls 3, a gap exists between the balls 3 and the cage 20 that creates a circumferential gap (see the left and right direction in FIG. 5). This circumferential direction is the direction in which the balls 3 rotate, so the lubricating oil can be taken into the oil pool through the gap and discharged from the oil pool. In other words, by temporarily retaining the lubricating oil in the oil pool, it is possible to prevent oil shortage, and also to prevent an increase in stirring resistance due to excessive accumulation of lubricating oil and the resulting heat generation. For this reason, the circumferential direction needs to be the long side of the ellipse.

[0035] As shown in Fig. 4, the inner peripheral surface of pocket 23 in a cross section perpendicular to the radial line of the bearing passing through pocket center p at pocket center p (referred to as planar inner peripheral surface) is configured as a perfect circle with a diameter equal to circumferential pocket major axis b. However, this planar inner peripheral surface is not limited to a perfect circle, and may be, for example, set to the major axis of an ellipse (left-right direction in Fig. 4) with the minor axis of the ellipse being shorter than the circumferential pocket major axis b in a direction perpendicular thereto (up-down direction in Fig. 4). The planar inner peripheral surface continues from tip G of retaining claw 22a through bottom F of pocket 23 to tip G of retaining claw 22a on the opposite side.

[0036] In addition, in Fig. 3, the radial inner circumferential surface D continues from the outer diameter side end d2 to the inner diameter side end d1 at the bottom F of the pocket 23. Although Fig. 3 shows the radial inner circumferential surface D in one cross section passing through the center line of the bearing, the radial inner circumferential surface D is set not only in this cross section but also in any cross section including the radial line of the bearing connecting the pocket center p and the axis of the bearing. However, if a recess H such as an oil reservoir is provided in the pocket 23, the location of the recess H is excluded.

[0037] 4 also shows the circumferential inner surface E of one cross section that passes through the pocket center p and is perpendicular to the radial line of the bearing connecting the pocket center p and the axis of the bearing, but this circumferential inner surface E is set not only in this cross section but also in any cross section that passes through the pocket center p and intersects with the radial line of the bearing that passes through the pocket center p (however, if a recess H such as an oil reservoir is provided in the pocket 23, the location of the recess H is excluded). The radial inner surface D and the circumferential inner surface E are connected somewhere between the bottom F and the side center point J (see FIG. 5), for example, at the midpoint between the bottom F and the side center point J.

[0038] Additionally, it is desirable that the radius of the arc of the radial inner circumferential surface D is 0.86 or more and less than 0.98 with respect to 1 / 2 the diameter φx of the balls 3 over the entire area of ​​the radial inner circumferential surface D. Furthermore, it is desirable that the radius of the arc of the circumferential inner circumferential surface E is 0.86 or more and less than 0.98 with respect to 1 / 2 the diameter φx of the balls 3 over the entire area of ​​the circumferential inner circumferential surface E. This ensures a gap between the balls 3 and the bottom F of the pocket 23 that can become a pool of oil.

[0039] If the arc of the radial inner circumferential surface D has a portion with a radius of less than 0.86 with respect to 1 / 2 of the diameter φx of the ball 3, the rake angle between the ball 3 and the cage 20, that is, the acute angle between the tangent direction of the arc of the radial inner circumferential surface D at the inner diameter side end d1 and the outer diameter side end d2 and the tangent direction of the surface of the ball 3 at that position, increases. Therefore, the possibility that the lubricating oil will not be able to dynamically enter into the gap increases. Also, if the radius of the arc of the radial inner circumferential surface D is 0.98 or more with respect to 1 / 2 of the diameter φx of the ball 3, an oil pool will not be formed sufficiently between the radial inner circumferential surface D and the ball 3, and if the ratio exceeds 1.00, the oil pool will completely disappear. These matters are also the same for the circumferential inner circumferential surface E. For this reason, it is desirable to set the above-mentioned ratio to be 0.86 or more and less than 0.98.

[0040] 6, a cage 20 may be employed in which the cage outer diameter surface 25, which is the outer diameter surface of the annular portion 21 and the columnar portion 22, is inclined inward from the annular portion 21 side toward the protruding end side of the columnar portion 22. This configuration prevents strong contact between the balls 3 and the cage 20 that accompanies centrifugal deformation during high-speed rotation of the bearing 10, and can prevent heat generation due to such strong contact. In particular, in a cage 20 having cantilevered protrusions (columnar portions 22) such as a crown-type cage, the centrifugal deformation of the protrusions (columnar portions 22) during high-speed rotation is large, so such an inclination of the cage outer diameter surface 25 is effective.

[0041] According to the above configuration, for example, dmn={(D+d) / 2}×n D: Bearing outer diameter (mm) d: bearing inner diameter (mm) n: Rotation speed (min -1 ) The bearing 10 can be used under high speed conditions where the dmn value defined by is 700,000 or more at its maximum rotational speed, for example, for supporting a motor shaft or a reducer shaft to which the driving force of an automobile drive motor is transmitted.

[0042] In the above embodiment, the rotating shaft is exemplified as the rotating shaft of a drive motor equipped in an electric transport device such as an electric vehicle, or the rotating shaft of a reducer or speed increaser equipped in such electric transport device, but the bearing 10 of the present invention and a bearing device using the bearing 10 can also be applied to supporting parts of rotating shafts in various other transport devices, industrial machines, etc. For example, the present invention can be applied to rotating parts of shafts, constant velocity joints, propeller shafts, turbochargers, transmissions, and wheel bearings in power transmission paths in various transport devices, or supporting parts of rotating shafts in various machine tools, generators, etc.

[0043] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0044] 1 Outer ring 2. Inner Circle 3 Balls (rolling elements) 10. Rolling bearings (ball bearings) 20 Retainer 21 Circular Ring 21a Cage end face 22 Pillar part (protruding part) 22a Claw part 23 Pocket 24 Cage inner diameter surface 25 Cage outer diameter surface a Radial pocket minor diameter b Circumferential pocket major diameter c Axial pocket length D Radial inner surface E Circumferential inner surface F Bottom G tip H recess J Side center point o Bearing centerline p Pocket center R Virtual line

Claims

1. A cage is used in a rolling bearing having an outer ring (1), an inner ring (2), and a plurality of balls (3) arranged between the outer ring (1) and the inner ring (2), the cage comprising an annular portion (21) and a plurality of pillar portions (22) protruding from the annular portion (21) in the axial direction of the bearing, and a pocket (23) formed between adjacent pillar portions (22, 22) in the circumferential direction of the bearing for holding the balls (3), A retainer in which the radius of the arc of the radial inner surface (D) of the pocket (23) in a cross section passing through the pocket center (p) of the pocket (23) and including the bearing center line (o) is set to be smaller than 1 / 2 the diameter φx of the ball (3) over the entire area of ​​the radial inner surface (D).

2. 2. The cage according to claim 1, wherein the radial inner surface (D) coincides with an imaginary line (R) formed by an ellipse having a radial pocket minor diameter (a) smaller than the diameter φx of the ball (3) in the radial direction of the bearing and an axial pocket major diameter (c) larger than the diameter φx of the ball (3) in the axial direction of the bearing.

3. A retainer as described in claim 1, wherein the radius of the arc of the circumferential inner surface (E) of the pocket (23) in a cross section passing through the pocket center (p) and perpendicular to the bearing center line (o) is set to be smaller than 1 / 2 the diameter φx of the ball (3) over the entire area of ​​the circumferential inner surface (E).

4. 4. The retainer according to claim 3, wherein the circumferential inner surface (E) coincides with an imaginary line (R) formed by an ellipse having a radial pocket minor diameter (a) smaller than the diameter φx of the ball (3) in the radial direction of the bearing and a circumferential pocket major diameter (b) larger than the diameter φx of the ball (3) in the tangential direction to the circumferential direction of the bearing.

5. The ratio of the radial pocket minor diameter (a) to the axial pocket major diameter (c) is 3. The cage according to claim 2, wherein the ratio is 0.83 or more and less than 0.

97.

6. The ratio of the radial pocket minor diameter (a) to the circumferential pocket major diameter (b) is The cage according to claim 4 , wherein the ratio is 0.83 or more and less than 0.

97.

7. The radial inner peripheral surface (D) coincides with an imaginary line (R) formed by an ellipse having a radial pocket minor diameter (a) smaller than the diameter φx of the ball (3) in the radial direction of the bearing and an axial pocket major diameter (c) larger than the diameter φx of the ball (3) in the axial direction of the bearing, a circumferential inner surface (E) of the pocket (23) in a cross section passing through the pocket center (p) and perpendicular to the bearing center line (o) coincides with an imaginary line (R) formed by an ellipse having a radial pocket minor axis (a) smaller than the diameter φx of the ball (3) in the radial direction of the bearing and a circumferential pocket major axis (b) larger than the diameter φx of the ball (3) in the tangential direction to the circumferential direction of the bearing, The cage according to claim 1, wherein the centers of the ellipse of the imaginary line (R) of the radial inner surface (D) and the ellipse of the imaginary line (R) of the circumferential inner surface (E) are coincident with each other.

8. A cage as described in claim 1, wherein the radius of the arc of the radial inner surface (D) is greater than or equal to 0.86 and less than 0.98 with respect to 1 / 2 of the diameter φx of the ball (3) over the entire radial inner surface (D).

9. 2. The retainer according to claim 1, wherein the retainer outer diameter surfaces (25) of the annular portion (21) and the column portion (22) are inclined inwardly from the annular portion (21) side toward the protruding end side of the column portion (22).

10. 10. A bearing device in which a rolling bearing using a cage according to any one of claims 1 to 9 is applied to support a motor shaft or a reduction gear shaft to which driving force of a drive motor for an automobile is transmitted.

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