Patent ID: 12247620

DESCRIPTION OF EMBODIMENTS

A mode for carrying out the invention will be described in detail with reference to the drawings. The present disclosure is not limited by the content described in the following description. In addition, the components described below include components that can be easily conceived by the one skilled in the art, and substantially equivalent components. Furthermore, the components described below can be appropriately combined.

First Embodiment

FIG.1is a cross-sectional view of a bearing device of the first embodiment that is cut along an axial center.FIG.2is a perspective view obliquely illustrating the retainer of the first embodiment.FIG.3is an arrow cross-sectional view taken along a III-III line inFIG.1.

FIG.4is a view illustrating the retainer of the first embodiment that is viewed from an outer circumferential side.

As illustrated inFIG.1, a bearing device100includes an inner race101forming a circular shape around an axial center O, an outer race102surrounding the outer circumferential side of the inner race101, and a plurality of balls103and a retainer1that are arranged between the inner race101and the outer race102. On the outer circumferential surface of the inner race101, an outer circumferential track surface101ais provided. On the inner circumferential surface of the outer race102, an inner circumferential track surface102ais provided. The balls103are arranged between the outer circumferential track surface101aand the inner circumferential track surface102a. Note that examples of materials forming the inner race101and the outer race102include bearing steel and stainless material, but the inner race101and the outer race102in the present disclosure may be formed of materials other than these. In addition, materials forming the balls103include bearing steel, stainless material, and ceramic material, but the balls103in the present disclosure may be formed of materials other than these.

As illustrated inFIG.2, the retainer1forms a circular shape around the axial center O. The retainer1includes a circular-shaped main body portion2centered on the axial center O, a plurality of pockets (spaces)3in which the balls103are arranged, and retaining surfaces4surrounding the pockets3. Hereinafter, a direction parallel to the axial center O will be referred to as an axial direction.

The main body portion2includes an outer circumferential surface5oriented toward a radial direction outer side, and an inner circumferential surface6oriented toward a radial direction inner side. In addition, a pair of tab portions7and7are provided in the main body portion2. The tab portions7are provided for expanding the retaining surface4in the axial direction.

Hereinafter, out of axial directions, a direction in which the pair of tab portions7and7protrude from the main body portion2will be referred to as a first direction X1, and an opposite direction to the first direction will be referred to as a second direction. In addition, regarding rotational directions around the axial center O, a counterclockwise direction set when the retainer is viewed from a first axial direction will be referred to as a first rotational direction L1, and an opposite direction will be referred to as a second rotational direction.

The pockets3penetrates through the main body portion2in the radial direction. Accordingly, on the outer circumferential surface5of the main body portion2, openings in the first direction X1of the pockets3are provided. In addition, at a rim portion of the opening in the first direction X1of the pocket3, an outer circumferential corner portion8at which the retaining surface4and the outer circumferential surface5intersect with each other is provided. On the other hand, on the inner circumferential surface6of the main body portion2, openings in a second direction X2of the pockets3are provided. At a rim portion of the opening in the second direction X2of the pocket3, an inner circumferential corner portion9at which the retaining surface4and the inner circumferential surface6intersect with each other is provided. When viewed from the radial direction, the outer circumferential corner portion8and the inner circumferential corner portion9form a C shape opening in the first direction X1.

The retaining surface4includes a first retaining surface11arranged in the first rotational direction L1with respect to the pocket3, a second retaining surface12arranged in the second rotational direction with respect to the pocket3, and a central retaining surface13arranged in the second direction X2with respect to the pocket3. Hereinafter, the details of the first retaining surface11and the second retaining surface12will be described.

As illustrated inFIG.3, the first retaining surface11extends along a first spherical surface B1. The second retaining surface12extends along a second spherical surface B2. The first spherical surface B1is a surface obtained by rotating a first virtual circle C1being a true circle centered on a center O1, around a virtual line K1connecting the axial center O (refer toFIGS.1and2) and a center O103of the ball103. In addition, the second spherical surface B2is a surface obtained by rotating a second virtual circle C2being a true circle centered on a center O2, around the virtual line K1. Accordingly, the first retaining surface11and the second retaining surface12have a hemispherical surface shape.

The center O1of the first virtual circle C1and the center O2of the second virtual circle C2exist in a range overlapping the ball103. The center O1of the first virtual circle C1is arranged at a position closer to the second retaining surface12than the virtual line K1. That is, a radius r1of the first virtual circle C1is larger than a radius of the ball103. Accordingly, the first retaining surface11is a gentler curved surface as compared with the ball103. Then, a clearance amount between the first retaining surface11and the ball103becomes larger as getting closer to the radial direction outer side (the outer circumferential corner portion8) and the radial direction inner side (the inner circumferential corner portion9) from a central portion in the radial direction.

Note that a virtual plane K2illustrated inFIG.3is a plane that has the virtual line K1as a perpendicular, and includes the center O103of the ball103. Accordingly, the center O103of the ball103serves as a foot of the perpendicular (the virtual line K1) of the virtual plane K2.

In addition, the center O1of the first virtual circle C1is arranged at a position closer to the radial direction outer side than the virtual plane K2, and closer to the outer circumferential corner portion8than to the inner circumferential corner portion9. Thus, a clearance amount between the first retaining surface11and the ball103on the radial direction outer side (the outer circumferential corner portion8) is larger than that on the radial direction inner side (the inner circumferential corner portion9).

Similarly, the center O2of the second virtual circle C2is arranged at a position closer to the first retaining surface11than the virtual line K1. Accordingly, a radius r2of the second virtual circle C2is larger than the radius of the ball103. Accordingly, the second retaining surface12is a gentler curved surface as compared with the ball103. Then, a clearance amount between the second retaining surface12and the ball103becomes larger as getting closer to the radial direction outer side (the outer circumferential corner portion8) and the radial direction inner side (the inner circumferential corner portion9) from a central portion in the radial direction. Note that the radius r1of the first virtual circle C1and the radius r2of the second virtual circle C2are the same.

In addition, the center O2of the second virtual circle C2is arranged at a position closer to the radial direction outer side than the virtual plane K2, and closer to the outer circumferential corner portion8than to the inner circumferential corner portion9. Thus, a clearance amount between the second retaining surface12and the ball103on the radial direction outer side (the outer circumferential corner portion8) is larger than that on the radial direction inner side (the inner circumferential corner portion9). Note that a distance between the center O2of the second virtual circle C2and the virtual plane K2is the same as a distance N (refer toFIG.3) between the center O1of the first virtual circle C1and the virtual plane K2.

In view of the foregoing, in the present embodiment, a dimension M1of the outer circumferential corner portion8is larger than a dimension M2of the inner circumferential corner portion9. Accordingly, as illustrated inFIG.4, when the pocket3is viewed from the outer circumferential side of the retainer1, the inner circumferential corner portion9arranged on the inner side of the outer circumferential corner portion8can be visually recognized. On the other hand, when the pocket3is viewed from the inner circumferential side of the retainer1, the outer circumferential corner portion8overlaps the inner circumferential surface6of the main body portion2and cannot be visually recognized, which is not specifically illustrated.

In addition, as illustrated inFIG.3, the dimension M1of the outer circumferential corner portion8and the dimension M2of the inner circumferential corner portion9are smaller than a diameter of the ball103. Accordingly, the ball103is less likely pass through the outer circumferential corner portion8and the inner circumferential corner portion9to get out.

In addition, the first retaining surface11and the second retaining surface12each include an outer circumferential side contact point14that contacts the ball103in a case where the retainer1moves toward the radial direction inner side, and an inner circumferential side contact point15that contacts the ball103in a case where the retainer1moves toward the radial direction outer side. The outer circumferential corner portion8is separated from the outer circumferential side contact point14toward the radial direction outer side. In addition, the inner circumferential corner portion9is separated from the inner circumferential side contact point15toward the radial direction inner side. Accordingly, the situation where the outer circumferential corner portion8and the inner circumferential corner portion9contact the ball103, and grease adhering to the ball103is scraped off is not caused. In addition, the ball103makes surface contact with the first retaining surface11and the second retaining surface12without contacting (without making point contact with) the outer circumferential corner portion8nor the inner circumferential corner portion9, and rolling motion of the ball103is stabilized.

Next, an effect of the retainer of the first embodiment will be described. According to the above-described bearing device100, the outer circumferential corner portion8is opened widely. Thus, lubricant oil provided on the inner circumferential track surface102aeasily passes through a space between the outer circumferential corner portion8and the ball103, and flows into the pocket3. Accordingly, a large amount of lubricant oil is interposed between the ball103and the retaining surface4. Thus, if the retainer1vibrates in the radial direction, contact between the ball103and the retaining surface4is suppressed by the lubricant oil provided between the ball103and the retaining surface4. Accordingly, retainer sound is less likely to be produced.

As described above, the retainer1of the first embodiment includes the main body portion2that is arranged between the inner race101and the outer race102of the bearing device100, and forms a circular shape around the axial center O of the inner race101, the plurality of pockets3that is provided in the circumferential direction, and penetrates through the main body portion2in the radial direction, and the retaining surface4that faces the ball103arranged in the pocket3, and forms a C shape when viewed from the radial direction. The retaining surface4includes the C-shaped outer circumferential corner portion8at which the retaining surface4and the outer circumferential surface5of the main body portion2intersect with each other, the C-shaped inner circumferential corner portion9at which the retaining surface4and the inner circumferential surface6of the main body portion2intersect with each other, the first retaining surface11arranged in the first rotational direction L1around the axial center O, with respect to the ball103, and the second retaining surface12arranged in a second rotational direction L2being an opposite direction to the first rotational direction L1, with respect to the ball103. The first retaining surface11extends along the first spherical surface B1obtained by rotating the first virtual circle C1around the virtual line K1passing through the axial center O and the center O103of the ball103. The second retaining surface12extends along the second spherical surface B2obtained by rotating the second virtual circle C2around the virtual line K1. The radii of the first virtual circle C1and the second virtual circle C2are larger than the radius of the ball103. The center O1of the first virtual circle C1and the center O2of the second virtual circle C2are arranged at positions closer to the radial direction outer side than the virtual plane K2that has the virtual line K1as a perpendicular, and includes the center O103of the ball103.

According to the retainer1of the first embodiment, a large amount of lubricant oil is interposed between the ball103and the retaining surface4, contact between the ball103and the retaining surface4is suppressed, and retainer sound is less likely to be produced.

In addition, the outer circumferential corner portion8of the first embodiment is arranged at a position closer to the radial direction outer side than the outer circumferential side contact point14that contacts the retaining surface4in a case where the ball103relatively moves toward the radial direction outer side. The inner circumferential corner portion9is arranged at a position closer to the radial direction inner side than the inner circumferential side contact point15that contacts the retaining surface4in a case where the ball103relatively moves toward the radial direction inner side.

According to the above-described configuration, the situation where grease adhering to the ball103is scraped off from the outer circumferential corner portion8and the inner circumferential corner portion9is not caused. In addition, the ball103makes surface contact with the first retaining surface11and the second retaining surface12, and rolling motion of the ball103is stabilized.

In addition, in the first embodiment, the center O1of the first virtual circle C1is arranged at a position closer to the second retaining surface12than the virtual line K1. In addition, the center O2of the second virtual circle C2is arranged at a position closer to the first retaining surface11than the virtual line K1.

According to the above-described configuration, as compared with a case where the center O1of the first virtual circle C1and the center O2of the second virtual circle C2are arranged on the virtual line K1, curvature radii of the first retaining surface11and the second retaining surface12become larger. Accordingly, clearance amounts between the first retaining surface11and the second retaining surface12, and the ball103become larger as getting closer to the radial direction outer side or inner side from the central portion in the radial direction. Consequently, the dimension of the outer circumferential corner portion8becomes larger.

Second Embodiment

Next, a retainer1A of the second embodiment will be described.FIG.5is a cross-sectional view of a retainer of the second embodiment. The retainer1A of the second embodiment differs from that in the first embodiment in that a center O1of a first virtual circle C1and a center O2of a second virtual circle C2coincide with each other. That is, in the second embodiment, as illustrated inFIG.5, a first retaining surface11and a second retaining surface12extend along a single spherical surface B3. Hereinafter, only a difference will be described.

The spherical surface B3is obtained by rotating a virtual circle C3around a virtual line K1. A center O3of the spherical surface B3is arranged on the virtual line K1. In addition, the center O3of the virtual circle C3is arranged at a position closer to the radial direction outer side than a virtual plane K2.

Also in the retainer1A of the second embodiment, a dimension M1of an outer circumferential corner portion8is larger than a dimension M2of an inner circumferential corner portion9. Accordingly, lubricant oil easily passes through a space between the outer circumferential corner portion8and a ball103, and flows into a pocket3. Thus, a large amount of lubricant oil is interposed between the ball103and a retaining surface4. Accordingly, production of retainer sound can be suppressed.

Third Embodiment

Next, a retainer1B of the third embodiment will be described.FIG.6is a cross-sectional view of a retainer of the third embodiment. The retainer1B of the third embodiment differs from that in the first embodiment in that a first virtual circle C4and a second virtual circle C5are not true circles but ellipses. Note that the first virtual circle C4and the second virtual circle C5are line symmetric with respect to a virtual line K1. Accordingly, the first virtual circle C4will be described, and the description of the second virtual circle C5will be omitted.

As illustrated inFIG.6, the ellipse (the first virtual circle C4) is a curved line generated from an aggregate of points of which a sum of distances from two foci D1and D2becomes constant. A center O4of the ellipse (the first virtual circle C4) is an intermediate point of the two foci D1and D2. The foci D1and D2are arranged on the virtual line K1. Accordingly, a major axis of the ellipse (the first virtual circle C4) extends in a direction parallel to the virtual line K1, and a minor axis of the ellipse (the first virtual circle C4) extends in a direction orthogonal to the virtual line K1.

A radius of the ellipse (the first virtual circle C4) becomes shortest at a point overlapping the minor axis. A length (radius) r4of the minor axis of the ellipse (the first virtual circle C4) is larger than a radius of a ball103. Accordingly, the first retaining surface11is a gentler curved surface as compared with the ball103. In addition, a clearance amount between the first retaining surface11and the ball103becomes larger as getting closer to the radial direction outer side (an outer circumferential corner portion8) and the radial direction inner side (an inner circumferential corner portion9) from a central portion in the radial direction.

The center O4of the ellipse (the first virtual circle C4) is arranged at a position closer to the radial direction outer side than a virtual plane K2, and closer to the outer circumferential corner portion8than to the inner circumferential corner portion9. Thus, a clearance amount between the first retaining surface11and the ball103on the radial direction outer side (the outer circumferential corner portion8) is larger than that on the radial direction inner side (the inner circumferential corner portion9). That is, in the third embodiment, a dimension M1of the outer circumferential corner portion8is larger than a dimension M2of the inner circumferential corner portion9. Accordingly, also in the retainer1B of the third embodiment, similarly to the first embodiment, contact between the ball103and the retaining surface4is suppressed, and retainer sound is less likely to be produced.

Note that, in the third embodiment, major axes of the first virtual circle C4and the second virtual circle C5extend in a direction parallel to the virtual line K1, but in the present disclosure, major axes of the first virtual circle C4and the second virtual circle C5may extend in a direction orthogonal to the virtual line K1.

Heretofore, each embodiment has been described, but the present disclosure is not limited to the example described in the embodiment. For example, in the first embodiment, the center O1of the first virtual circle C1and the center O2of the second virtual circle C2have the same distance to the virtual plane K2, but the present disclosure is not limited to this. For example, the center O1of the first virtual circle C1and the center O2of the second virtual circle C2may have different distances to the virtual plane K2.

Note that, according to the present disclosure, as a distance between a center of a virtual circle and the virtual plane K2becomes larger, the outer circumferential corner portion8becomes larger. On the other hand, if the dimension M1of the outer circumferential corner portion8is larger than the diameter of the ball103, the ball103gets out from the pocket3. Accordingly, a distance between a center of a virtual circle and the virtual plane K2needs to be shorter than a limit distance between a center of a virtual circle and the virtual plane K2(distance obtained in a case where the dimension M1of the outer circumferential corner portion8becomes the same as the diameter of the ball103).

FIG.7is a cross-sectional view of a bearing device of Modified Example 1 that is cut along an axial center. In addition, bearing devices to which the retainers1,1A, and1B of the present disclosure are applied are not limited to the bearing device100illustrated inFIG.1. For example, as illustrated inFIG.7, a bearing device100C may include two seal materials110aside from an inner race101, an outer race102, a ball103, and the retainer1,1A, or1B. The seal material110includes a core bar111that fits with a stepped surface102bof the outer race102. In addition, the two seal materials110are arranged in a first direction X1and a second direction X2with respect to the ball103. According to the two seal materials110, a foreign substance is less likely to enter a space between the inner race101and the outer race102. Note that the seal material110in the present disclosure may be a seal material110in which a rubber portion slidably contacting the inner race101is provided at an end portion on the radial direction inner side of the core bar111.

FIG.8is a cross-sectional view of a bearing device of Modified Example 2 that is cut along an axial center. In addition, as illustrated inFIG.8, in a bearing device100D of Modified Example 2, a circumferential groove102dextending in the circumferential direction is provided on an outer circumferential surface102cof an outer race102. Then, an O ring115is fitted into the circumferential groove102d. According to the O ring115, a space between a surface with which the outer race102fits, and the outer circumferential surface of the outer race102is sealed. The retainers1,1A, and1B of the present disclosure may be applied to the bearing device100D. A cross-sectional shape of the O ring115is not limited to a circular shape as illustrated inFIG.8, and may be a rectangular shape. In addition, an O ring115in which a groove is formed may be used. In addition, the retainers1,1A, and1B of the present disclosure may be applied to a bearing device in which a retaining ring or the like is fitted into the circumferential groove102din place of the O ring115. In this manner, bearing devices to which the retainers1,1A, and1B of the present disclosure are applied are not specifically limited.

Example

Next, Example will be described. As Example, the retainer1of the first embodiment was manufactured. Then, Example was tested, and whether the production of retainer sound is suppressed was checked. In addition, Comparative Example was prepared to confirm the effect of the retainer1. As a first retaining surface11and a second retaining surface12of a retainer of Comparative Example, a first retaining surface11and a second retaining surface12extending along a single virtual circle, the center of which overlaps the center of a ball, were used.

As a test method, a bearing including a retainer of Example and a bearing including a retainer of Comparative Example were prepared, and cooled under a stationary condition for one hour in the environment of 0° C. After that, outer races of the respective bearings were fixed, inner races were rotated using motors, and images of behaviors of the retainers were captured using a high-speed camera. Note that the number of revolutions of the motors was set to 11, 500 min−1. In addition, as load acting on the bearings, axial load was 4 N and radial load was 0 N. Then, a frequency of sound produced from each bearing was analyzed based on captured image data. Note that, as relationship between frequency and retainer sound, if the number of times the retainer1and the ball103contact is large, high-pitched retainer sound (sound with high frequency) is produced. That is, a result indicating a lower frequency indicates a preferable result indicating that the number of times the retainer1and the ball103contact is suppressed to a small number, and retainer sound is suppressed to small sound.

FIG.9is a diagram illustrating test results of bearings including retainers of Example and Comparative Example. As illustrated inFIG.9, a frequency of sound produced from the retainer of Example was 122 Hz, and a frequency of sound produced from the retainer of Comparative Example was 4041 Hz. In view of the foregoing, it has been seen that, according to Example, the production of retainer sound is drastically suppressed. In this manner, according to Example, lubrication in the pocket3is improved. Thus, excited vibration of the retainer1is drastically suppressed, and the production of retainer sound is eventually suppressed.

REFERENCE SIGNS LIST

100,100C,100D BEARING DEVICE101INNER RACE102OUTER RACE103BALL1,1A,1B RETAINER2MAIN BODY PORTION3POCKET4RETAINING SURFACE5OUTER CIRCUMFERENTIAL SURFACE6INNER CIRCUMFERENTIAL SURFACE7TAB PORTION8OUTER CIRCUMFERENTIAL CORNER PORTION9INNER CIRCUMFERENTIAL CORNER PORTION11FIRST RETAINING SURFACE12SECOND RETAINING SURFACE14OUTER CIRCUMFERENTIAL SIDE CONTACT POINT15INNER CIRCUMFERENTIAL SIDE CONTACT POINTB1FIRST SPHERICAL SURFACEB2SECOND SPHERICAL SURFACEB3SPHERICAL SURFACEC1FIRST VIRTUAL CIRCLEC2SECOND VIRTUAL CIRCLEC3VIRTUAL CIRCLEC4FIRST VIRTUAL CIRCLEC5SECOND VIRTUAL CIRCLEK1VIRTUAL LINEK2VIRTUAL PLANE