Cage and rolling bearing

Abstract

To provide a cage capable of suppressing the deformation during high speed rotation, and a rolling bearing having the cage.SOLUTION: A cage 5 includes an annular base part 51, pillar parts 52 protruded from the base part 51 in the axial direction, and pocket parts 53 formed between two pillar parts 52 neighboring each other in the peripheral direction to store at least part of rolling elements 4. The pocket parts 53 are constructed so that the radial and axial movement is restricted by the rolling elements 4. A radial width W5 of each pocket part 53 is more than 0.6 times an axial width W4 of the pocket part 53.SELECTED DRAWING: Figure 9

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses a ball bearing having a so-called crown-type cage. This cage has an annular portion and multiple pillar portions formed on one axial end face of the annular portion. Pockets for accommodating balls, which are rolling elements, are formed between two circumferentially adjacent pillar portions. Within the ball bearing, the cage holds multiple balls at predetermined intervals. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5012499 Summary of the Invention [Problem to be solved by the invention]

[0004] When the outer and inner rings rotate at relatively high speeds, the balls and cage rotate together. Centrifugal force acts radially outward on the cage. The bar portions deform radially outward. If the tip of the bar portion, which deforms radially outward the most, comes into contact with, for example, the inner circumferential surface of the outer ring, the bar portion will wear and may cause abnormal heat generation.

[0005] Therefore, an object of the present invention is to provide a cage that can suppress deformation during high-speed rotation, and a rolling bearing having such a cage. [Means for solving the problem]

[0006] A cage according to one embodiment of the present invention comprises an annular base, pillar portions protruding axially from the base, and a pocket portion formed between two circumferentially adjacent pillar portions and accommodating at least a portion of a rolling element, wherein the pocket portion is configured so that radial and axial movement is restricted by the rolling element, and the radial width of the pocket portion is 0.6 times or more the axial width of the pocket portion.

[0007] A rolling bearing according to one embodiment of the present invention comprises an inner ring, an outer ring, a plurality of rolling elements arranged between the inner ring and the outer ring, and the above-mentioned retainer that holds the plurality of rolling elements, wherein the outer diameter of the column portion of the retainer is smaller than the inner diameter of the outer ring. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a cage that can suppress deformation during high-speed rotation, and a rolling bearing having the cage. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view schematically showing the structure of a rolling bearing 1 according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. [Figure 3] 1 is a perspective view schematically showing the structure of a cage 5 according to a first embodiment of the present invention. [Figure 4] 1 is a perspective view schematically showing the structure of a cage 5 according to a first embodiment of the present invention. [Figure 5] 1 is a perspective view schematically showing the structure of a cage 5 according to a first embodiment of the present invention. [Figure 6] 1 is a plan view schematically showing the structure of a cage 5 according to a first embodiment of the present invention. [Figure 7] 7 is an enlarged cross-sectional view of a portion of the cross section taken along line 7-7 in FIG. 2. [Figure 8] FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 7. [Figure 9] FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 5. [Figure 10] 3 is a partially enlarged cross-sectional view of a portion of the rolling bearing 1 for explaining the dimensional design of the cage 5. FIG. [Figure 11] FIG. 10 is a perspective view schematically showing the structure of a cage 5A according to a second embodiment of the present invention. [Figure 12] FIG. 12 is a cross-sectional view taken along line 12-12 in FIG. [Figure 13] FIG. 10 is a perspective view schematically showing the structure of a cage 5B according to a third embodiment of the present invention. [Figure 14] FIG. 14 is a cross-sectional view taken along line 14-14 in FIG. [Figure 15] FIG. 10 is a perspective view schematically showing the structure of a cage 5C according to a fourth embodiment of the present invention. [Figure 16] FIG. 10 is a perspective view schematically showing the structure of a cage 5C according to a fourth embodiment of the present invention. [Figure 17] FIG. 17 is a cross-sectional view taken along line 17-17 in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing the structure of a rolling bearing 1 according to an embodiment of the present invention. The rolling bearing 1 is applied, for example, to high-speed spindle motors incorporated in machine tools and the like, and drive motors incorporated in electric vehicles. The rolling bearing 1 comprises an inner ring 2, an outer ring 3, a plurality of rolling elements 4, and a cage 5. The inner ring 2, the outer ring 3, and the cage 5 are annular members with an axis x as their central axis. The axis x serves as the axis of both the rolling bearing 1 and the cage 5. In one example, the outer ring 3 of the rolling bearing 1 is fixed to a housing of a motor, while the inner ring 2 is fixed to the shaft of the motor.

[0011] FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1. Referring to both FIGS. 1 and 2, the inner ring 2 and the outer ring 3 are formed in a cylindrical shape centered on the axis x. The outer ring 3 is disposed outside the inner ring 2 in a radial direction perpendicular to the direction along the axis x (hereinafter referred to as the "axial direction"). The outer peripheral surface 21 of the inner ring 2 faces the inner peripheral surface 31 of the outer ring 3. The outer peripheral surface 21 of the inner ring 2 is formed with an annular raceway groove 22 recessed radially inward from the outer peripheral surface 21. Similarly, the inner peripheral surface 31 of the outer ring 3 is formed with an annular raceway groove 32 recessed radially outward from the inner peripheral surface 31. A plurality of rolling elements 4 are arranged between these raceway grooves 22 and raceway grooves 32 in the circumferential direction around the axis x. In this example, seven rolling elements 4 are arranged circumferentially between the inner ring 2 and the outer ring 3.

[0012] The rolling elements 4 are spheres (balls), and therefore the rolling bearing 1 is a rolling ball bearing. The rolling elements 4 are held between the inner ring 2 and the outer ring 3 at a predetermined interval in the circumferential direction by a cage 5. The inner ring 2 and the outer ring 3 are made of a metal material, such as stainless steel. The rolling elements 4 are made of stainless steel or ceramic, for example. The cage 5 is made of a resin material, such as polyamide. The space between the inner ring 2 and the outer ring 3 is filled with a lubricant (not shown), such as grease. The lubricant reduces friction between the rolling elements 4 and the inner ring 2 and the outer ring 3. A pair of shields (not shown) may be provided to seal the space between the inner ring 2 and the outer ring 3. The shields prevent the lubricant from leaking out of the space and prevent foreign matter from entering the space.

[0013] FIG. 3 is a perspective view of the cage 5 as viewed from one axial side. FIG. 4 is a perspective view of the cage 5 as viewed from the other axial side. For ease of explanation, one axial side is defined as the upper side, and the other axial side is defined as the lower side. Note that "upper" and "lower" do not necessarily correspond to upper and lower in the direction of gravity. FIGS. 3 and 4 show a state in which rolling elements 4 are held in the cage 5. The cage 5 has a base 51, multiple pillars 52, and multiple pockets 53. The base 51 is formed in an annular shape with the axis x as its central axis. The multiple pillars 52 protrude upward in the axial direction from the base 51. As shown in FIG. 4, a lower surface 51a of the base 51 is defined along a plane perpendicular to the axis x.

[0014] The multiple pillar portions 52 are arranged at predetermined intervals in the circumferential direction. In this example, seven pillar portions 52 are formed in the circumferential direction. Each pocket portion 53 is formed between two circumferentially adjacent pillar portions 52, 52. In this example, seven pocket portions 53 are formed in the circumferential direction. One rolling element 4 is held in each pocket portion 53. Each pocket portion 53 accommodates at least a portion of the rolling element 4. Each pillar portion 52 is formed with a grease pocket 54 that is recessed axially downward from the upper end surface 52a of the pillar portion 52. In this example, the grease pocket 54 extends from the radial inner end to the radial outer end of each pillar portion 52. The grease pocket 54 can hold the aforementioned lubricant. In this example, the upper end surface 52a of the pillar portion 52 extends along a plane perpendicular to the axis x.

[0015] FIG. 5 is a perspective view of the cage 5, schematically illustrating the structure of the cage 5. FIG. 6 is a plan view of the cage 5, schematically illustrating the structure of the cage 5. Referring to FIGS. 5 and 6 together, each pocket 53 opens at an inner opening 55 formed radially inward, an outer opening 56 formed radially outward, and an upper opening 57 formed axially upward. The inner opening 55 and the outer opening 56 face each other radially. The upper opening 57 connects the inner opening 55 and the outer opening 56. In this example, the inner opening 55, the outer opening 56, and the upper opening 57 are formed in a generally arcuate shape. Each pocket 53 defines a spherical surface 58 facing the spherical surface of the rolling element 4. The spherical surface 58 is defined, for example, by a spherical surface that partially faces the spherical surface of the rolling element 4 around the center of the rolling element 4.

[0016] Each column portion 52 has a pair of claw portions 59, 59 that protrude radially outward from the base portion 51. The claw portions 59, 59 extend radially outward along the upper end surface 52a of the column portion 52. The pair of claw portions 59, 59 are circumferentially separated by a radially extending grease pocket 54. In each column portion 52, the pair of claw portions 59, 59 have peripheral edges 59a that move away from each other in the circumferential direction as they move radially outward. That is, in two circumferentially adjacent column portions 52, 52, the claw portion 59 of one column portion 52 and the claw portion 59 of the other column portion 52 circumferentially adjacent to the claw portion 59 have peripheral edges 59a that move closer to each other in the circumferential direction as they move radially outward. As shown in FIG. 6 , the outer diameter OD1 of the outer edge 59b of the claw portion 59 is larger than the outer diameter OD2 of the outer peripheral surface of the base portion 51.

[0017] FIG. 7 is an enlarged cross-sectional view of a portion of a cross section taken along line 7-7 in FIG. 2. The cross section shown in FIG. 7 is defined along a plane perpendicular to the axis x and including the center C of the rolling element 4. As shown in FIG. 7, the inner opening 55 is defined with a circumferential width W1 along the circumferential direction within this cross section. Here, the circumferential width W1 is the maximum linear distance between both edges of the inner opening 55 along the circumferential direction. The circumferential width W1 of the inner opening 55 is defined to be smaller than the diameter D of the rolling element 4. Furthermore, the outer opening 56 is defined with a circumferential width W2 along the circumferential direction within this cross section. Here, the circumferential width W2 is the maximum linear distance between both edges of the outer opening 56 along the circumferential direction. The circumferential width W2 of the outer opening 56 is defined to be smaller than the diameter D of the rolling element 4. In this way, each pocket portion 53 holds the rolling element 4 radially.

[0018] As described above, a plurality of rolling elements 4 are arranged between the inner ring 2 and the outer ring 3. The rolling elements 4 roll while sliding within the raceway grooves 22 of the inner ring 2 and the raceway grooves 32 of the outer ring 3. Radial movement of the rolling elements 4 is restricted. Because the circumferential width W1 of the inner opening 55 of the pocket portion 53 and the circumferential width W2 of the outer opening 56 are smaller than the diameter D of the rolling elements 4, the rolling elements 4 restrict radial movement of the pocket portion 53, i.e., the column portion 52. As is clear from FIG. 7 , a portion of the rolling elements 4 is exposed radially outward from the inner opening 55 of the pocket portion 53 of the cage 5 and radially inward from the outer opening 56. In this example, the sum of the radial length L1 of the rolling element 4 exposed radially outward and the radial length L2 of the rolling element 4 exposed radially inward is preferably 10% or more and 50% or less of the diameter D of the rolling element 4, and more preferably 10% or more and 30% or less of the diameter D.

[0019] FIG. 8 is a cross-sectional view taken along line 8-8 in FIG. 7. The cross section shown in FIG. 8 is defined along a plane including the center C of the rolling element 4. As shown in FIG. 8, the upper opening 57 is defined with a circumferential width W3 in the circumferential direction in this cross section. Here, the circumferential width W3 is the maximum linear distance between both edges of the upper opening 57 along the circumferential direction. The circumferential width W3 of the upper opening 57 is defined to be smaller than the diameter D of the rolling element 4. In this way, each pocket 53 holds the rolling element 4 in the axial direction. The rolling element 4 rolls while sliding within the raceway grooves 22 of the inner ring 2 and the raceway grooves 32 of the outer ring 3, thereby restricting axial movement of the rolling element 4. As a result, the rolling element 4 restricts axial movement of the pocket 53, i.e., the column portion 52. As is clear from FIG. 8, a portion of the rolling element 4 is exposed axially upward from the upper opening 57 of the pocket 53 of the cage 5. In this example, the axial length L3 of the rolling element 4 exposed in the axial direction is preferably 30% or more and less than 50% of the diameter D of the rolling element 4, and more preferably 40% or more and less than 50% of the diameter D.

[0020] FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 5. As shown in FIG. 9, each pocket 53 defines an axial width W4, which is the width in the axial direction from the upper end surface 52a of the column portion 52 to the deepest part of the spherical surface 58. Meanwhile, each pocket 53 defines a radial width W5, which is the width from the inner circumferential surface 52b to the outer circumferential surface 52c of the column portion 52. The inner circumferential surface 52b of the column portion 52 is defined by a cylindrical surface with the axis x as its central axis. The outer circumferential surface 52c of the column portion 52 coincides with the outer edge 59b of the claw portion 59. In each pocket 53, the radial width W5 is defined to be at least 0.6 times the axial width W4. However, the radial width W5 may be at least 0.7 times, at least 0.8 times, at least 0.9 times, at least 1.0 times, or at least 1.1 times the axial width W4. The radial width W5 is set smaller than the distance between the outer peripheral surface 21 of the inner ring 2 and the inner peripheral surface 31 of the outer ring 3. In this example, the radial width W5 is set larger than the axial width W4. In other words, each pocket 53 has a flattened shape that is larger in the radial direction than in the axial direction.

[0021] Returning to FIG. 2 , in the rolling bearing 1, as described above, the cage 5 is disposed between the inner ring 2 and the outer ring 3. The column portions 52 of the cage 5 face the raceway groove 22 of the inner ring 2 and the raceway groove 32 of the outer ring 3 in the radial direction. The outer diameter OD2 of the column portions 52 (outer edges 59 b of the claw portions 59) described above is, in principle, set to be smaller than the inner diameter ID defined by the inner circumferential surface 31 of the outer ring 3. However, as long as the claw portions 58 of the column portions 52 face the raceway groove 32 of the outer ring 3 in the radial direction, the outer diameter OD1 of the column portions 52 may be set to be the same as the inner diameter ID of the outer ring 3. It is preferable that the outer edges 59 b of the claw portions 59 of the column portions 52 face at least partially to the deepest part of the raceway groove 32 that is deepest from the inner circumferential surface 31 of the outer ring 3.

[0022] In the rolling bearing 1 described above, the cage 5, which is disposed radially between the inner ring 2 and the outer ring 3, has multiple pockets 53 that each hold a rolling element 4. When the rolling elements 4 and cage 5 rotate together around the axis x during high-speed rotation, the rolling elements 4 slide along the raceway grooves 22 of the inner ring 2 and the raceway grooves 32 of the outer ring 3, thereby restricting axial and radial movement of the rolling elements 4. In this way, the rolling elements 4 restrict the axial and radial movement of the pockets 53, i.e., the column portions 52. Furthermore, the radial width W5 of the pockets 53 is 0.6 times or more its axial width W4. With this configuration, even if centrifugal force acts on the cage 5 during high-speed rotation, radially outward deformation of the column portions 52 can be suppressed.

[0023] 10 is a partially enlarged cross-sectional view of a portion of the rolling bearing 1 for explaining the dimensional design of the cage 5. As shown in FIG. 10, the following dimensions are set for the rolling bearing 1: diameter L of the outer peripheral surface 21 of the inner ring 2; i ; Diameter L of the inner peripheral surface 31 of the outer ring 3 o the axial width B of the inner ring 2 and the outer ring 3 (in this example, the inner ring 2 and the outer ring 3 are the same); the diameter D of the rolling element 4; the radial width W of the cage 5 R (width from the inner peripheral surface 52b to the outer peripheral surface 52c of the column portion 52); and the axial height h of the cage 5 R (The height from the lower surface 51a of the base 51 to the upper end surface 52a of the pillar portion 52). Here, the aspect ratio of the cage 5 is defined by the following formula (1).

number

[0024] Next, the radial width W of the cage 5 R is defined as follows: Specifically, the radial width W R is the gap between the inner ring 2 and the outer ring 3 (L o -L i ) and the radial width W of the cage 5 R This gap (L o -L i ) and the occupation rate α, which indicates the percentage of the total occupied by the

number

[0025] On the other hand, the axial height h of the cage 5 R is defined as follows: Specifically, the axial height h R is expressed as the following equation (3) based on a coverage ratio β, which indicates what proportion of the diameter D of the rolling element 4 is covered by the cage 5 in the axial direction, and an occupation coefficient γ, which indicates what proportion of the axial width B of the inner ring 2 or outer ring 3 is occupied by the cage 5 in the axial direction, excluding the part that covers the rolling element 4.

number

[0026] According to the above formulas (1) to (3), the aspect ratio of the cage 5 can be defined by the following formula (4).

number

number

number

[0027] FIG. 11 is a perspective view schematically illustrating the structure of a cage 5A according to a second embodiment of the present invention. FIG. 12 is a cross-sectional view taken along line 12-12 in FIG. 11. As shown in FIGS. 11 and 12, the cage 5A has a smaller radial width W6 (see FIG. 12) of the base portion 51 than the cage 5. That is, the base portion 51 is thinner in the radial direction than the base portion 51 of the cage 5. Meanwhile, the outer diameter OD2 of the outer peripheral surface 52c of the bar portion 52 is set to be the same as that of the cage 5. As described above, the axial and radial movement of the pocket portion 53 is restricted by the rolling elements 4. Other components similar to those of the cage 5 are denoted by the same reference numerals, and redundant description will be omitted. This configuration allows for a reduction in the weight of the cage 5 by thinning the base portion 51. This configuration also prevents the bar portions 52 from deforming radially outward.

[0028] FIG. 13 is a perspective view schematically illustrating the structure of a cage 5B according to a third embodiment of the present invention. FIG. 14 is a cross-sectional view taken along line 14-14 in FIG. 13. As shown in FIGS. 13 and 14, the radial width W6 of the base portion 51 of this cage 5B is larger than that of the cage 5. However, the outer diameter OD2 of the base portion 51 is smaller than the outer diameter OD1 of the column portions 52, as described above. This cage 5B also includes a recessed portion 51b recessed upward from the lower surface 51a of the base portion 51. In this example, the recessed portion 51b is formed in an annular shape in the circumferential direction around the axis x. The recessed portion 51b prevents an increase in the weight of the cage 5B, regardless of an increase in the radial width W6 of the base portion 51. Other components similar to those of the cage 5 are designated by the same reference numerals, and redundant description will be omitted here. This configuration also prevents the column portions 52 from deforming radially outward. The hollowed-out portions 51b may be interrupted in the circumferential direction. Also, as long as other conditions are met, the formation of the claw portions 59 that protrude radially outward beyond the base portion 51 may be omitted. In other words, the outer peripheral surface of the base portion 51 and the outer peripheral surface of the column portion 52 may coincide with each other.

[0029] 15 and 16 are perspective views schematically illustrating the structure of a cage 5C according to a fourth embodiment of the present invention. FIG. 17 is a cross-sectional view taken along line 17-17 in FIG. 15. FIG. 15 is a perspective view of the cage 5C viewed from above, and FIG. 16 is a perspective view of the cage 5C viewed from below. This cage 5C is a modified version of the cage 5B. Referring to FIGS. 15 to 17, the depth of the recessed portions 51b in this cage 5C is greater than that in the cage 5B. As a result, the recessed portions 51b communicate with each of the pockets 53. That is, openings 60 communicating with the recessed portions 51b are formed in the spherical surfaces 58 of each of the pockets 53. By forming the recessed portions 51b larger in this way, the weight of the cage 5C can be further suppressed. Other components similar to those in the cage 5B are designated by the same reference numerals, and redundant description will be omitted here. This configuration also suppresses radially outward deformation of the column portions 52.

[0030] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the present invention. Furthermore, the above-described embodiments do not limit the scope of the present invention, and the present invention may include any and all applications. The components of the above-described embodiments, as well as their arrangement, materials, conditions, shape, size, etc., are not limited to those illustrated and may be modified as appropriate. For example, the present invention includes differences that arise during implementation due to manufacturing tolerances, etc. Furthermore, components illustrated in different embodiments may be partially substituted or combined within the scope of technical inconsistency. Furthermore, the various configurations may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. [Explanation of symbols]

[0031] 1 rolling bearing, 2 inner ring, 21 outer peripheral surface, 22 raceway groove, 3 outer ring, 31 inner peripheral surface, 32 raceway groove, 4 rolling element, 5, 5A, 5B, 5C cage, 51 base, 51a lower surface, 51b lightening portion, 52 column portion, 52a upper end surface, 52b inner peripheral surface, 52c outer peripheral surface, 53 pocket portion, 54 grease pocket, 55 inner opening, 56 outer opening, 57 upper opening, 58 spherical surface, 59 claw portion, 59a periphery, 59b outer edge, 60 opening, x axis

Claims

1. an annular base; a post portion protruding axially from the base portion; a pocket portion formed between two of the column portions adjacent in the circumferential direction and accommodating at least a part of the rolling element, The pocket portion is configured so that radial and axial movement thereof is restricted by the rolling elements, A cage, wherein the radial width of the pocket is 0.6 times or more the axial width of the pocket.

2. The cage of claim 1 , wherein the post portion has an outer diameter greater than an outer diameter of the base portion.

3. An inner opening is formed on the radially inner side of the pocket portion, An outer opening is formed on the radially outer side of the pocket portion, The cage according to claim 1 , wherein the circumferential width of the inner opening and the outer opening is smaller than the diameter of the rolling elements.

4. An upper opening is formed on the axially upper side of the pocket portion, The cage according to claim 1 , wherein the circumferential width of the upper opening is smaller than the diameter of the rolling elements.

5. With inner circle, The outer ring and a plurality of rolling elements disposed between the inner ring and the outer ring; and the cage according to claim 1 which holds the plurality of rolling elements, a rolling bearing, wherein the outer diameter of the column portion of the retainer is smaller than the inner diameter of the outer ring.

6. the rolling elements are exposed in the axial direction from the cage, 6. The rolling bearing according to claim 5, wherein the axial length of the exposed rolling element is equal to or greater than 30% and less than 50% of the diameter of the rolling element.

7. The diameter defined by the outer peripheral surface of the inner ring is L ｉ , the diameter defined by the inner peripheral surface of the outer ring is L ｏ , the axial width of the inner ring and the outer ring is B, the diameter of the rolling element is D, and the diameter L ｏ and the diameter L ｉ where α is the occupancy rate of the cage relative to the difference between the diameter D and the rolling elements, β is the coverage rate of the cage relative to the diameter D in the axial direction, and γ is the occupancy coefficient of the cage relative to the axial width B in the region other than the rolling elements in the axial direction, then the aspect ratio of the axial height to the radial width of the cage is given by: [Equation 1] The occupancy rate α, the cover rate β, and the occupancy coefficient γ are defined as follows: [Equation 2] 6. The rolling bearing according to claim 5, wherein the above formula is satisfied.

8. The occupancy rate α, the cover rate β, and the occupancy coefficient γ are [Equation 3] 8. The rolling bearing according to claim 7, wherein the above formula is satisfied.

Images