Rolling bearing, rotating equipment, and method for manufacturing a rolling bearing

Abstract

To provide a rolling bearing excellent in long term durability.SOLUTION: A rolling bearing 1 includes an inner ring 10 and an outer ring 20 arranged coaxially with each other, a rolling element 30 arranged between the inner ring 10 and the outer ring 20, a seal member 50 attached to the outer ring 20 and covering a gap between the inner ring 10 and the outer ring 20 from the outside in the axial direction, and grease 60 arranged between the rolling element 30 and the seal member 50. The grease 60 is in contact with an inner peripheral surface of the outer ring 20 and the seal member 50. The grease 60 has an outer ring contact portion 61 coming into contact with the inner peripheral surface of the outer ring 20, and a seal member contact portion 62 coming into contact with a plane portion 53 of the seal member 50 in the axial outer side of the outer ring contact portion 61 and in the inner ring 10 side. An area of the seal member contact portion 62 is larger than a contact area of the grease 60 with an extended portion 52 and a pedestal portion 51 of the seal member 50. Immiscible penetration of the grease 60 is more than 178 and less than 287.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a rolling bearing, a rotating device, and a method for manufacturing a rolling bearing.

Background Art

[0002] Conventionally, there is a rolling bearing that holds grease between a pair of raceway rings (inner ring and outer ring). In this type of rolling bearing, the resistance of the grease may be a factor that increases the rotational resistance. By the way, in a rolling bearing, it is desired to reduce the rotational resistance for the purpose of power saving of the mounted rotating device. In particular, in a small rolling bearing used in various motors such as a fan motor, there is a strong demand for reducing the rotational resistance.

[0003] In order to reduce the rotational resistance of a rolling bearing, it is effective to reduce the amount of grease that contacts both of the relatively rotating members. Therefore, grease is applied to the axial end portion of the fixed ring (in many cases, the outer ring) of the rolling bearing and the seal member disposed on the end portion side, and the amount of grease that contacts the rolling elements (balls) and the cage that holds the rolling elements is reduced (see, for example, Patent Document 1). In the rolling bearing described in Patent Document 1, the grease is adhered to the inner peripheral surface avoiding the raceway surface that contacts the rolling elements of the outer ring, and is enclosed in an annular shape biased toward the inner peripheral surface side of the outer ring so as not to contact the outer peripheral surface of the inner ring.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, if the amount of grease that contacts the rolling elements and the cage is reduced, the supply of grease to the sliding portion may be insufficient, leading to a possible decrease in the long-term durability of the rolling bearing.

[0006] Therefore, the present invention provides a rolling bearing, a rotating device, and a method for manufacturing a rolling bearing, which are excellent in long-term durability.

Means for Solving the Problems

[0007] The rolling bearing according to the first aspect of the present invention includes an inner ring and an outer ring arranged coaxially with each other, rolling elements arranged between the inner ring and the outer ring, a seal member attached to one of the raceways of the inner ring and the outer ring and covering the space between the inner ring and the outer ring from the outside in the axial direction, and grease arranged between the rolling elements and the seal member. The grease contacts the circumferential surface of the one raceway facing the other raceway of the inner ring and the outer ring, and the seal member. The seal member has an annular pedestal portion that contacts the one raceway from the outside in the axial direction, an extension portion that extends outward in the axial direction from the peripheral edge on the other raceway side of the pedestal portion, and a flat portion that extends along the radial direction from the outer edge in the axial direction of the extension portion toward the other raceway. The grease has a raceway contact portion that contacts the circumferential surface of the one raceway, and a seal member contact portion that is outside the raceway contact portion in the axial direction and contacts the flat portion on the other raceway side. The area of the seal member contact portion is larger than the contact area between the grease and the extension portion and the pedestal portion of the seal member. The non-miscibility consistency of the grease is greater than 178 and less than 287.

[0008] According to the first aspect, the portion of the grease that does not contact the rolling elements and the cage is relatively soft and is in a state where it is likely to separate from the oil to the outside. Therefore, even when the base oil of the portion of the grease that contacts the rolling elements or the cage is likely to be insufficient, the base oil oozes out from the inside of the grease that does not contact the rolling elements and the cage to the outside, and the base oil can be continuously supplied to the sliding portion. Further, even in a state where the grease is applied so as not to contact the rolling elements and the cage, the base oil can be supplied from the surface of the grease to the sliding portion, and the base oil also oozes out from the inside of the grease to the surface of the grease, and the base oil can be supplied to the sliding portion. Therefore, even when the grease is arranged at a position away from the rolling elements and the cage in order to reduce the rotational resistance of the rolling bearing, the base oil can be supplied to the sliding portion over a long period of time, and the durability of the rolling bearing can be improved. Further, by the immiscibility droop being less than 287, excessive deformation due to sagging or entrainment of the grease by gravity can be suppressed, and the shape of the portion of the grease that does not contact the rolling elements and the cage can be maintained in the initial shape. Thereby, it is possible to suppress the occurrence of variations in the rotational resistance due to differences in the shape of the grease for each rolling bearing. Furthermore, when the seal member is attached after applying the grease to a predetermined location, it is possible to provide room for the grease pushed axially inward by the flat portion of the seal member to spread radially toward the extending portion and the pedestal portion. Therefore, it is possible to suppress the grease from spreading greatly toward one raceway ring side and the rolling element side. Thus, it is possible to easily suppress the grease from directly contacting the rolling elements and one raceway ring. Moreover, since the seal member is provided with an extending portion between the flat portion and the pedestal portion, the grease can be arranged at a position farther from the rolling elements compared to a configuration in which the flat portion extends along the radial direction from the pedestal portion. Therefore, the amount of the grease can be increased. As described above, it is possible to provide a rolling bearing that can achieve both ensuring durability and reducing rotational resistance.

[0009] The rolling bearing according to the second aspect of the present invention may have a difference between the consistency of the grease and the non-consistency of less than 50 in the rolling bearing according to the first aspect.

[0010] According to the second aspect, the softness of the portion of the grease that does not contact the rolling elements and the cage becomes closer to the softness of the portion of the grease that contacts the rolling elements and the cage. As a result, the difference in the degree of bleeding of the base oil between the portion of the grease that contacts the rolling elements or the cage and the portion that does not contact the rolling elements and the cage is reduced. Therefore, the rotational resistance of the rolling bearing can be stabilized over a long period of time.

[0011] The rolling bearing according to the third aspect of the present invention may have a ratio of the difference between the consistency and the non-consistency to the consistency of the grease of less than 22.7% in the rolling bearing according to the first aspect or the second aspect.

[0012] According to the third aspect, the softness of the portion of the grease that does not contact the rolling elements and the cage becomes closer to the softness of the portion of the grease that contacts the rolling elements or the cage. As a result, the difference in the degree of bleeding of the base oil between the portion of the grease that contacts the rolling elements or the cage and the portion that does not contact the rolling elements and the cage is reduced. Therefore, the rotational resistance of the rolling bearing can be stabilized over a long period of time.

[0013] The rolling bearing according to the fourth aspect of the present invention may contain urea as the thickener of the grease in the rolling bearing according to any one of the first to third aspects.

[0014] According to the fourth aspect, since a grease with high heat resistance can be obtained, a rolling bearing with a small rotational resistance and high durability can be formed.

[0015] The rolling bearing according to the fifth aspect of the present invention is the rolling bearing according to any one of the first to fourth aspects, and the immiscibility consistency of the grease after being left at 85°C for 18 hours may be greater than 158.

[0016] According to the fifth aspect, even when the grease is exposed to high temperatures or left for a long time, the degree of hardening of the grease can be set so that the base oil can ooze out smoothly. Therefore, a highly durable rolling bearing can be formed.

[0017] The rolling bearing according to the sixth aspect of the present invention is the rolling bearing according to any one of the first to fifth aspects, and the grease may be in contact with at least one of the pedestal portion and the extending portion.

[0018] According to the sixth aspect, after applying the grease to a predetermined location, when mounting the seal member on one of the raceway rings, the grease may be pushed axially inward by the pedestal portion and the extending portion located axially inside of the flat portion of the seal member. Since the pedestal portion and the extending portion are closer to the rolling elements and the cage than the flat portion, the grease is likely to be pushed toward the rolling elements and the cage side when the seal member is mounted and come into contact with the rolling elements or the cage. Here, in the case of a grease with a relatively small (hard) immiscibility consistency as in the prior art, although there is a slight deformation when pushed axially inward by the seal member, the entire grease moves axially inward and may contact the rolling elements or the cage in an amount more than desired. According to the sixth aspect, since the immiscibility consistency of the grease is relatively large (soft), the grease is likely to deform radially when pushed axially inward by the seal member, suppressing the movement of the grease axially inward and preventing the grease from contacting the rolling elements or the cage more than necessary. Therefore, the above-described grease can be preferably used.

[0019] The rolling bearing according to the seventh aspect of the present invention is the rolling bearing according to any one of the first to sixth aspects, wherein the seal member contact portion may include the radial center position in the grease when viewed from the axial direction.

[0020] According to the seventh aspect, when the seal member is mounted, the grease is pushed onto the flat portion and spreads radially. As a result, the seal member contact portion includes the radial center position in the grease in plan view, so that it is possible to suppress the grease from spreading greatly inward in the axial direction toward the rolling elements. Therefore, it is possible to easily prevent the grease from directly contacting the rolling elements.

[0021] The rolling bearing according to the eighth aspect of the present invention is the rolling bearing according to any one of the first to seventh aspects, wherein the grease may be non-contact with the extending portion.

[0022] According to the eighth aspect, when the seal member is mounted, it is possible to provide a larger margin for the grease pushed inward in the axial direction by the flat portion of the seal member to spread radially toward the extending portion. For this reason, it is possible to suppress the grease from spreading greatly to one raceway ring side and the rolling element side. Therefore, it is possible to easily prevent the grease from contacting the rolling elements, the cage, and one raceway ring more than necessary.

[0023] The rolling bearing according to the ninth aspect of the present invention is the rolling bearing according to any one of the first to eighth aspects, wherein the raceway ring contact portion may be provided at an interval in the axial direction with respect to the contact portion between the one raceway ring and the pedestal portion.

[0024] According to the ninth aspect, it is possible to avoid the grease from contacting the contact portion between the raceway ring and the pedestal portion. Thereby, it is possible to suppress the grease from leaking to the outside of the seal member due to capillary action through the contact portion between the raceway ring and the pedestal portion.

[0025] The rolling bearing according to the tenth aspect of the present invention is the rolling bearing according to any one of the first to ninth aspects, wherein the grease may be non-contact with the pedestal portion.

[0026] According to the tenth aspect, it is possible to avoid the grease from contacting the contact portion between the raceway ring and the pedestal portion. Thereby, it is possible to suppress the grease from leaking to the outside of the seal member due to capillary action through the contact portion between the raceway ring and the pedestal portion.

[0027] The rolling bearing according to the eleventh aspect of the present invention is the rolling bearing according to any one of the first to tenth aspects, wherein one of the raceway rings has a protruding portion that protrudes toward the other raceway ring and on which a raceway surface is formed, the protruding portion faces the outside in the axial direction and is connected to the peripheral surface at the periphery on the other raceway ring side, and has an end surface that contacts the pedestal portion, and the pedestal portion may be arranged so as not to protrude toward the other raceway ring side more than the end surface when viewed from the axial direction.

[0028] According to the eleventh aspect, even when the grease contact portion of the raceway ring spreads outward in the axial direction and overrides the periphery of the end surface, it is possible to suppress the grease from adhering to the pedestal portion. Therefore, it is possible to avoid the grease from contacting the contact portion between the raceway ring and the pedestal portion. Thereby, it is possible to suppress the grease from leaking to the outside of the seal member due to capillary action through the contact portion between the raceway ring and the pedestal portion.

[0029] The rotating device according to the twelfth aspect of the present invention includes a rotating body rotatably arranged, a support body that rotatably supports the rotating body, and a rolling bearing according to any one of the first to eleventh aspects interposed between the rotating body and the support body.

[0030] According to the twelfth aspect, since it is provided with a rolling bearing having excellent long-term durability, it is possible to achieve a longer life of the rotating device.

[0031] A method for manufacturing a rolling bearing according to a thirteenth aspect of the present invention includes an inner ring and an outer ring arranged coaxially with each other, rolling elements arranged between the inner ring and the outer ring, a seal member attached to one of the raceways of the inner ring and the outer ring and covering between the inner ring and the outer ring from the outer side in the axial direction, and grease arranged between the rolling elements and the seal member. The seal member has an annular pedestal portion that contacts the one raceway from the outer side in the axial direction, an extension portion that extends outward in the axial direction from the peripheral edge on the side of the other raceway of the inner ring and the outer ring in the pedestal portion, and a flat portion that extends along the radial direction from the outer edge in the axial direction of the extension portion toward the other raceway. The method for manufacturing a rolling bearing is as follows: The grease is brought into contact with the peripheral surface of the one raceway that faces the other raceway of the inner ring and the outer ring to form a raceway contact portion where the grease contacts the peripheral surface of the one raceway, and the grease is applied so as to protrude from the contact portion with the one raceway to the outer side in the axial direction and the side of the other raceway; a coating step; the seal member is brought close to the one raceway from the outer side in the axial direction, and the flat portion is brought into contact with the outer edge in the axial direction of the grease to form a seal member contact portion where the grease contacts the flat portion on the outer side in the axial direction of the raceway contact portion and on the side of the other raceway; a contact step; after the contact step, the seal member is brought close to the one raceway and the pedestal portion is brought into contact with the one raceway from the outer side in the axial direction, and the flat portion presses the grease inward in the axial direction; a mounting step. By performing the mounting step, the area of the seal member contact portion is made larger than the contact area between the grease and the extension portion and the pedestal portion of the seal member and the grease, and the non-miscibility consistency of the grease is made greater than 178 and less than 287.

[0032] According to the 13th aspect, since the flat portion of the seal member contacts the axially outer edge of the grease in the contact step, when the flat portion presses inward in the axial direction in the mounting step, room is provided for the grease to spread radially toward the extending portion and the pedestal portion of the seal member. Therefore, it is possible to suppress the grease from spreading greatly toward the other raceway ring side and the rolling element side. Thus, it is possible to easily suppress the grease from directly contacting the rolling element and the other raceway ring. Furthermore, since the immiscibility degree of the grease is relatively small, when the grease is pushed axially inward by the seal member, the grease can be easily deformed radially. Thereby, the movement of the grease inward in the axial direction can be suppressed, and it is possible to suppress the grease from contacting the rolling element or the cage more than necessary. Moreover, since the extending portion is provided between the flat portion and the pedestal portion, compared with the configuration in which the flat portion extends from the pedestal portion toward the other raceway ring side, it is difficult for the grease to be pushed toward the rolling element side. Therefore, it becomes possible to arrange the grease closer to the rolling element in advance, so that the amount of the grease can be increased. As described above, it is possible to manufacture a rolling bearing that can achieve both ensuring durability and reducing rotational resistance.

Advantages of the Invention

[0033] According to the present invention, it is possible to provide a rolling bearing having excellent long-term durability.

Brief Description of the Drawings

[0034]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0035] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to configurations having the same or similar functions. And redundant descriptions of these configurations may be omitted.

[0036] [First Embodiment] The first embodiment according to the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view of a rolling bearing according to the first embodiment. FIG. 2 is a longitudinal sectional view taken along line II-II of FIG. 1. In FIG. 2, the rotating device 2 to which the rolling bearing 1 is attached is shown by a phantom line.

[0037] As shown in FIGS. 1 and 2, the rolling bearing 1 is a radial ball bearing including an inner ring 10 and an outer ring 20 which are raceways, a plurality of rolling elements 30, a cage 40, and a pair of seal members 50. The rolling bearing 1 is provided in a rotating device 2 such as a fan motor. The rotating device 2 includes a shaft 3 (rotating body) formed to be rotatable about a common axis O, and a housing 4 (support body) fixedly installed to rotatably support the shaft 3. The rolling bearing 1 is interposed between the shaft 3 and the housing 4.

[0038] The inner ring 10 and the outer ring 20 are coaxially arranged with respect to each other such that their respective central axes coincide with the common axis O. In the present embodiment, the direction in which the common axis O extends is referred to as the axial direction, the direction that is orthogonal to the common axis O and extends radially from the common axis O is referred to as the radial direction, and the direction that circulates around the common axis O is referred to as the circumferential direction. Also, one of the directions that are parallel to the axial direction and point in opposite directions to each other is defined as the upper direction, and the other is defined as the lower direction.

[0039] The inner ring 10 is provided as a rotating ring. The inner ring 10 is externally inserted into the shaft 3 and fixed to the shaft 3. The outer ring 20 is provided as a fixed ring. The outer ring 20 is fitted into a recess (or through hole) of the housing 4 and fixed to the housing 4. The outer ring 20 surrounds the inner ring 10 from the outside in the radial direction with an annular space provided between the outer ring 20 and the inner ring 10. The plurality of rolling elements 30 are arranged between the inner ring 10 and the outer ring 20 and are rotatably held by the cage 40. The cage 40 rotatably holds each rolling element 30 in a state where the plurality of rolling elements 30 are evenly arranged in the circumferential direction. The seal member 50 is attached to the outer ring 20 and covers the annular space between the inner ring 10 and the outer ring 20 from the outside in the axial direction.

[0040] The outer ring 20 is formed in an annular shape from a metal material such as stainless steel or bearing steel. However, the outer ring 20 is not limited to being made of metal and may be formed of other materials. The outer ring 20 has an outer ring body 21 whose width along the axial direction is made equal to the width along the axial direction of the inner ring 10, and a protruding portion 22 that protrudes radially inward from the outer ring body 21 and extends over the entire circumferential direction. The protruding portion 22 is formed at a portion located at the axial center of the outer ring body 21. The width of the protruding portion 22 along the axial direction is shorter than the width of the outer ring body 21 along the axial direction and larger than the outer diameter of the rolling element 30.

[0041] The protruding portion 22 includes a pair of end faces 22a facing the outside in the axial direction and an inner circumferential surface 22b connecting the inner circumferences of the pair of end faces 22a. Each end face 22a extends parallel in both the radial and circumferential directions. An outer ring raceway surface 23 that is recessed toward the outside in the radial direction is formed on the inner circumferential surface 22b. The outer ring raceway surface 23 is formed in a hemispherical shape in a cross-sectional view so as to follow the outer surface of the rolling element 30 and is formed in an annular shape that extends in the circumferential direction over the entire circumference of the inner circumferential surface 22b. The outer ring raceway surface 23 is formed at a portion located at the axial center of the inner circumferential surface 22b. The portion of the inner circumferential surface 22b excluding the outer ring raceway surface 23 extends in the axial direction with a constant inner diameter.

[0042] The outer ring body 21 has a pair of inner peripheral surfaces 21a extending from the outer peripheral edge of each end surface 22a of the protruding portion 22 to the opening edge of the outer ring 20. The portion of each inner peripheral surface 21a located axially inward is located radially outward of the portion located axially outward.

[0043] The inner ring 10 is formed in an annular shape from a metal material such as stainless steel or bearing steel. However, the inner ring 10 is not limited to being made of metal and may be formed of other materials. An inner ring raceway surface 11 that is recessed radially inward is formed on the outer peripheral surface of the inner ring 10. The inner ring raceway surface 11 is formed in a hemispherical shape in a cross-sectional view so as to follow the outer surface of the rolling elements 30 and is formed in an annular shape extending in the circumferential direction over the entire circumference of the outer peripheral surface. The inner ring raceway surface 11 is formed in a portion of the outer peripheral surface of the inner ring 10 that is located at the axial center and is arranged to face the outer ring raceway surface 23 radially. The portion of the outer peripheral surface of the inner ring 10 excluding the inner ring raceway surface 11 extends axially with a constant outer diameter.

[0044] As shown in FIG. 2, the plurality of rolling elements 30 are formed in a spherical shape from a metal material such as stainless steel or bearing steel. The plurality of rolling elements 30 are arranged between the outer ring raceway surface 23 and the inner ring raceway surface 11 and are rotatably supported by the outer ring raceway surface 23 and the inner ring raceway surface 11. The plurality of rolling elements 30 are kept at circumferential intervals by the cage 40.

[0045] The retainer 40 is integrally formed in an annular shape from a synthetic resin or a metallic material. The retainer 40 is arranged around a common axis O. The retainer 40 includes an annular portion 41 formed in an annular shape and disposed below the plurality of rolling elements 30, and a plurality of column portions 42 projecting upward from the annular portion 41 and provided at intervals in the circumferential direction. The column portions 42 are evenly arranged in the circumferential direction. A pair of adjacent column portions 42 in the circumferential direction form a ball pocket between them. The ball pocket penetrates the retainer 40 in the radial direction and opens upward at the upper end surface of the retainer 40. The ball pockets are provided corresponding to the number of the rolling elements 30 and hold the rolling elements 30 separately and rotatably. Thereby, the retainer 40 arranges the rolling elements 30 at equal intervals in the circumferential direction. The retainer 40 is arranged with a gap with respect to the inner ring 10 and the outer ring 20 so as not to interfere with the inner ring 10 and the outer ring 20. In the present embodiment, the whole of the retainer 40 is located axially inside a pair of end faces 22a of the protruding portion 22 of the outer ring 20.

[0046] As shown in FIGS. 1 and 2, the seal member 50 is formed in an annular plate shape. The seal member 50 is arranged around a common axis O. The seal member 50 is uniformly formed over the entire circumference. The seal member 50 is fitted into the outer ring 20 from the axially outer side. The seal member 50 is arranged one on each of the axially both sides with respect to the plurality of rolling elements 30. The seal member 50 has an annular pedestal portion 51 that contacts the outer ring 20 from the axially outer side, an extending portion 52 that extends axially outward from the inner peripheral edge of the pedestal portion 51, a flat portion 53 that extends along the radial direction from the axially outer edge of the extending portion 52 toward the inner ring 10, and a locking portion 54 that extends radially outward and axially outward from the outer peripheral edge of the pedestal portion 51.

[0047] As shown in FIG. 2, the pedestal portion 51 overlaps the end face 22a of the protruding portion 22 of the outer ring 20 from the outside in the axial direction. The pedestal portion 51 extends substantially parallel to the end face 22a of the protruding portion 22 of the outer ring 20. The pedestal portion 51 protrudes radially inward of the end face 22a of the protruding portion 22 in a plan view seen from the axial direction. The distance by which the pedestal portion 51 protrudes radially inward from the end face 22a of the protruding portion 22 is 10% or less of the radial interval between the inner ring 10 and the outer ring 20, and desirably 5% or less. The extending portion 52 extends from the inner peripheral edge of the pedestal portion 51 to the outside in the axial direction and radially inward. The flat portion 53 overlaps the center of the rolling element 30 in a plan view. The inner peripheral edge of the flat portion 53 is arranged with a gap from the outer peripheral surface of the inner ring 10. The surface of the flat portion 53 facing the inside in the axial direction is a flat surface extending in the circumferential direction and the radial direction. The outer peripheral edge of the locking portion 54 is locked to the inner peripheral surface 21a of the outer ring body 21 from the inside in the axial direction. Thereby, the seal member 50 is fixed to the outer ring 20 and rotates integrally with the outer ring 20 with respect to the inner ring 10.

[0048] The rolling bearing 1 is filled with grease 60. The grease 60 contains a base oil and a thickener, and the base oil held by the thickener oozes out by being stirred and sheared to impart a lubricating effect to the sliding portion. The grease 60 is disposed between the rolling element 30 and the seal member 50. The grease 60 is disposed only on one axial side with respect to the rolling element 30 in the annular space between the inner ring 10 and the outer ring 20. In the present embodiment, the grease 60 is disposed on the side opposite to the annular portion 41 of the cage 40 with the rolling element 30 interposed therebetween in the axial direction. That is, the grease 60 is disposed above the rolling element 30. The grease 60 is disposed along the circumferential direction. The grease 60 extends in an annular shape or an arc shape and is disposed coaxially with the common axis O.

[0049] The grease 60 includes an outer ring contact portion 61 (raceway ring contact portion) that contacts the inner circumferential surface 22b of the protruding portion 22 of the outer ring 20, and a seal member contact portion 62 that contacts the flat portion 53 of the seal member 50 on the axially outer side and radially inner side of the outer ring contact portion 61. These outer ring contact portion 61 and seal member contact portion 62 extend in the circumferential direction over the entire length of the grease 60. The outer ring contact portion 61 has a width in the axial direction over the entire circumferential direction. The outer ring contact portion 61 contacts a portion of the inner circumferential surface 22b of the protruding portion 22 that is axially spaced from the outer ring raceway surface 23. The outer ring contact portion 61 contacts a portion of the inner circumferential surface 22b of the protruding portion 22 that is axially spaced from the inner peripheral edge of the upper end surface 22a. That is, the outer ring contact portion 61 is provided axially spaced from the contact portion between the outer ring 20 and the pedestal portion 51 of the seal member 50. The seal member contact portion 62 has a width in the radial direction over the entire circumferential direction. The seal member contact portion 62 contacts the flat portion 53 at a location radially spaced from the connection portion between the extending portion 52 and the flat portion 53 in the seal member 50.

[0050] The grease 60 extends axially outward and radially inward from the outer ring contact portion 61 toward the seal member contact portion 62. The grease 60 includes an inner surface 63 and an outer surface 64. The inner surface 63 connects the axially inner edge of the outer ring contact portion 61 and the radially inner edge of the seal member contact portion 62. The inner surface 63 faces the outer circumferential surface of the inner ring 10 and the rolling elements 30. The upper half of the inner surface 63 extends axially inward and radially inward from the radially inner edge of the seal member contact portion 62. The lower half of the inner surface 63 extends axially outward and radially inward from the axially inner edge of the outer ring contact portion 61 and connects to the lower end edge of the upper half. The boundary portion between the upper half and the lower half of the inner surface 63 forms the innermost circumferential edge located most radially inward in the grease 60. The inner surface 63 is spaced apart from the inner ring 10, the rolling elements 30, and the cage 40. Thereby, the grease 60 is made non-contact with respect to the inner ring 10, the rolling elements 30, and the cage 40.

[0051] The outer surface 64 connects the axially outer edge in the outer ring contact portion 61 and the radially outer edge in the seal member contact portion 62. The outer surface 64 faces the inner circumferential surface 22b of the protruding portion 22 of the outer ring 20 and the seal member 50. The outer surface 64 extends from the radially outer edge in the seal member contact portion 62 inward in the axial direction and radially outward and connects to the axially outer edge in the outer ring contact portion 61. The outer surface 64 is spaced apart from the pedestal portion 51 and the extending portion 52 of the seal member 50. Thereby, the grease 60 is not in contact with the pedestal portion 51 and the extending portion 52 of the seal member 50 that are located on the outer ring 20 side relative to the flat portion 53 of the seal member 50.

[0052] The grease 60 is formed such that the cross-sectional area of the cross-section along the plane perpendicular to the common axis O gradually increases as it goes from the axially outer end toward the inner side in the axial direction. In the present embodiment, the grease 60 is formed such that the cross-sectional area of the cross-section along the plane perpendicular to the common axis O gradually increases in the portion corresponding to the upper half of the inner surface 63 as it goes from the axially outer end toward the inner side in the axial direction.

[0053] Note that the grease 60 may contact at least one of the rolling elements 30 and the cage 40. For example, the grease 60 may contact at least one of the rolling elements 30 and the cage 40 due to changes over time from an initial state of non-contact with the rolling elements 30 and the cage 40.

[0054] The configuration of the grease 60 will be described. Note that the grease 60 may contain other components other than the base oil and the thickener as necessary.

[0055] The base oil is not particularly limited, and examples include mineral oil and synthetic oil. As the mineral oil, known mineral oils used as base oils can be used, and examples include naphthenic mineral oil, paraffinic mineral oil, hydrogenated mineral oil, solvent-refined mineral oil, highly refined mineral oil, etc. The mineral oil may be used alone or in combination of two or more. For example, a plurality of types of mineral oils may be mixed and adjusted to the desired properties.

[0056] As the synthetic oil, known synthetic oils used as base oils can be used. For example, polyalphaolefin (PAO), aliphatic hydrocarbon oils such as polybutene, aromatic hydrocarbon oils such as alkylbenzene and alkylnaphthalene, ester oils such as polyol ester and phosphate ester, ether oils such as polyphenyl ether, polyalkylene glycol oils, silicone oils, fluorine oils, and the like can be mentioned. These synthetic oils may be used alone or in combination of two or more. For example, a plurality of types of synthetic oils may be mixed and adjusted to the desired properties.

[0057] The thickener plays a role in keeping the grease 60 in a semi-solid state. As the thickener, known thickeners commonly used for grease for rolling bearings can be used without limitation. Examples of the thickener include urea compounds, lithium soaps, calcium soaps, complex lithium soaps, complex calcium soaps, silica gel, polytetrafluoroethylene, organophilic bentonite, and the like. From the viewpoint of excellent heat resistance, urea compounds are preferable as the thickener. The thickener may be used alone or in combination of two or more. For example, a plurality of types of thickeners may be mixed and adjusted to the desired properties.

[0058] The immiscibility degree of the grease 60 of the present embodiment is greater than 178 and less than 287. The difference between the miscibility degree and the immiscibility degree of the grease 60 is preferably less than 50. The ratio of the difference between the miscibility degree and the immiscibility degree to the miscibility degree of the grease 60 is preferably less than 22.7%. The immiscibility degree of the grease 60 after standing at 85°C for 18 hours is preferably greater than 158. In the following description, standing at 85°C for 18 hours is referred to as high-temperature standing.

[0059] Next, a method for manufacturing the rolling bearing 1 of the present embodiment will be described. The method for manufacturing the rolling bearing 1 of the present embodiment includes a coating step and a sealing step.

[0060] FIG. 3 and FIG. 4 are longitudinal sectional views of a rolling bearing for explaining a grease application method according to the first embodiment. As shown in FIG. 3, the application step is performed with the seal member 50 not attached to the outer ring 20. That is, the annular space between the inner ring 10 and the outer ring 20 is axially open, and the grease 60 is applied with the rolling elements 30 and the cage 40 exposed. In the application step, the grease 60 is discharged from the nozzle A while rotating the nozzle A around the common axis O with respect to the outer ring 20. At this time, the orientation of the nozzle A is adjusted so that the grease 60 is discharged radially outward and axially inward from the nozzle A. Further, the discharged grease 60 is brought into contact with a predetermined position on the inner peripheral surface 22b of the protruding portion 22 of the outer ring 20, and the position of the nozzle A is adjusted so that the grease 60 does not contact the rolling elements 30 and the cage 40. Since the grease 60 is discharged while the nozzle A is relatively rotated with respect to the outer ring 20, the grease 60 applied to the outer ring 20 extends circumferentially or arcuately. Also, the grease 60 is applied so as to follow the discharge direction from the nozzle A and protrude axially outward and radially inward from the contact portion with the outer ring 20. The axially outer end face of the applied grease 60 is formed in a convex shape that bulges axially outward.

[0061] Subsequently, a sealing step is performed. As shown in FIG. 4, in the sealing step, the seal member 50 is brought close to the outer ring 20 from the axially outer side, and the seal member 50 is attached to the outer ring 20. In the process of displacing the seal member 50 axially inward, before the pedestal portion 51 contacts the end face 22a of the protruding portion 22 of the outer ring 20, first, the flat portion 53 of the seal member 50 is brought into contact with the axially outer edge of the entire grease 60 (contact step). At this time, the grease 60 is brought into contact with the radially intermediate portion of the flat portion 53. The radially intermediate portion only needs to be located radially inward of the outer peripheral edge of the flat portion 53 and radially outward of the inner peripheral edge. Thereafter, the seal member 50 is further brought close to the outer ring 20, and the pedestal portion 51 is brought into contact with the end face 22a of the protruding portion 22 of the outer ring 20 from the axially outer side (mounting step). At this time, the grease 60 is pushed axially inward by the flat portion 53 of the seal member 50. As a result, the grease 60 spreads radially by being pushed by the flat portion 53, and the seal member contact portion 62 of the grease 60 is formed.

[0062] As described above, the rolling bearing 1 is formed. In the coating process of the present embodiment, the grease 60 is applied while rotating the nozzle A with respect to the outer ring 20. However, the grease may be discharged from a nozzle having discharge holes extending in the circumferential direction, and the grease may be applied in a circumferential or arc shape all at once.

[0063] The operation of the present embodiment will be described. The grease 60 is disposed between the rolling elements 30 and the seal member 50, and most (or all) of it is not in contact with the rolling elements 30 and the cage 40. That is, only a small portion of the grease 60 that comes into contact with the rolling elements 30 or the cage 40 and is sheared during the operation of the rolling bearing 1 is small, and there may be cases where the grease 60 does not contact the rolling elements 30 and the cage 40.

[0064] Here, the hardness of the grease is different between the state where it is not being sheared (not being mixed) and the state where it is being sheared (being mixed). Generally, the grease becomes softer when it is sheared. For this reason, the portion of the grease 60 that contacts the inner ring 10, the rolling elements 30, or the cage 40 continues to be sheared by the rolling elements 30 or the cage 40 and becomes softer, promoting the bleeding of the base oil. On the other hand, the portion of the grease 60 that does not contact the rolling elements 30 and the cage 40 remains in a hard state. When the portion of the grease 60 that contacts the rolling elements 30 or the cage 40 is small, if there is insufficient base oil bleeding from the portion that is sheared by the rolling elements 30 or the cage 40, most of the grease 60 is not agitated and remains hard, resulting in insufficient supply of the base oil and leading to the shortening of the life of the rolling bearing 1. The same applies when the entire grease 60 does not contact the rolling elements 30 and the cage 40.

[0065] By the way, as indices indicating the properties related to the hardness of grease, there are the consistency of blending and the consistency of non-blending. The consistency of blending is an index of the hardness of grease immediately after being sheared. Therefore, the state of the grease at the time of measuring the consistency of blending is close to the state of the portion of the grease in the rolling bearing that contacts the rolling elements or the cage and is sheared. On the other hand, the consistency of non-blending is an index of the hardness of grease in a state where it is not being sheared. Therefore, the state of the grease at the time of measuring the consistency of non-blending is close to the state of the portion of the grease in the rolling bearing that does not contact the rolling elements and the cage.

[0066] The rolling bearing 1 of the present embodiment has grease 60 that contacts the inner peripheral surface of the outer ring 20 and the seal member 50. The consistency of non-blending of the grease 60 is greater than 178 and less than 287. According to this configuration, the portion of the grease 60 that does not contact the rolling elements 30 and the cage 40 is relatively soft, and it becomes a state where it is easy to separate oil to the outside. For this reason, even when the base oil of the portion of the grease 60 that contacts the rolling element 30 or the cage 40 is likely to be insufficient, the base oil oozes out from the inside of the grease 60 that does not contact the rolling elements 30 and the cage 40 to the outside, and the base oil can be continuously supplied to the sliding portion. Further, even in a state where the grease 60 is applied so as not to contact the rolling elements 30 and the cage 40, the base oil can be supplied from the surface of the grease 60 to the sliding portion, and the base oil also oozes out from the inside of the grease 60 to the surface of the grease 60, and the base oil can be supplied to the sliding portion. For this reason, even when the grease 60 is arranged at a position away from the rolling elements 30 and the cage 40 in order to reduce the rotational resistance of the rolling bearing 1, the base oil can be supplied to the sliding portion over a long period of time, and the durability of the rolling bearing 1 can be improved.

[0067] Further, since the consistency of non-blending is less than 287, excessive deformation due to sagging or rotation of the grease 60 due to gravity can be suppressed, and the shape of the portion of the grease 60 that does not contact the rolling elements 30 and the cage 40 can be maintained in the initial shape. Thereby, it is possible to suppress the occurrence of variations in the rotational resistance due to differences in the shape of the grease 60 for each rolling bearing 1.

[0068] In addition, since the grease 60 is in contact with the inner peripheral surface of the outer ring 20, it is easy to supply the grease 60 to the outer ring raceway surface 23. Therefore, the base oil can be supplied to the sliding portion between the outer ring 20 and the rolling elements 30 over a long period of time, and the durability of the rolling bearing 1 can be improved.

[0069] Furthermore, in the present embodiment, the grease 60 is in contact with both the inner peripheral surface of the outer ring 20 and the seal member 50. In this configuration, when the grease 60 is enclosed between the outer ring 20 and the inner ring 10, after the grease 60 is applied to the outer ring 20, the grease 60 is pushed axially inward by the seal member 50 when the seal member 50 is attached to the outer ring 20. Here, in the case of a grease with a relatively small (hard) non-conformability as in the prior art, although there is a slight deformation when it is pushed axially inward by the seal member, the entire grease may move axially inward and contact the rolling elements 30 or the cage 40 more than the desired amount. In the present embodiment, since the non-conformability of the grease 60 is relatively large (soft), the grease 60 is easily deformed radially when it is pushed axially inward by the seal member 50, suppressing the movement of the grease 60 axially inward and preventing the grease 60 from contacting the rolling elements 30 or the cage 40 more than necessary. Therefore, an increase in the rotational resistance of the rolling bearing 1 can be suppressed.

[0070] In addition, since the difference between the conformability and the non-conformability of the grease 60 is less than 50, the softness of the portion of the grease 60 that is not in contact with the rolling elements 30 and the cage 40 becomes close to the softness of the portion of the grease 60 that is in contact with the rolling elements 30 and the cage 40. As a result, the difference in the bleeding condition of the base oil between the portion of the grease 60 that contacts the rolling elements 30 or the cage 40 and the portion that does not contact the rolling elements 30 and the cage 40 becomes smaller. Therefore, the rotational resistance of the rolling bearing 1 can be stabilized over a long period of time.

[0071] In addition, since the ratio of the difference between the consistency and the non-consistency of the consistency of the grease 60 with respect to the consistency of the grease 60 is less than 22.7%, the softness of the portion of the grease 60 that does not contact the rolling elements 30 and the cage 40 becomes close to the softness of the portion of the grease 60 that contacts the rolling elements 30 or the cage 40. As a result, the difference in the degree of bleeding of the base oil between the portion of the grease 60 that contacts the rolling elements 30 or the cage 40 and the portion that does not contact the rolling elements 30 and the cage 40 becomes small. Therefore, the rotational resistance of the rolling bearing 1 can be stabilized over a long period of time.

[0072] The thickener of the grease 60 contains urea. According to this configuration, since a grease having high heat resistance can be obtained, a rolling bearing 1 having a small rotational resistance and high durability can be formed. Generally, in a grease using urea as a thickener, the difference between the consistency and the non-consistency tends to be large. However, by selecting the type of urea, mixing multiple types of urea, adjusting the production conditions of urea, additives, etc., a grease that satisfies the above-described consistency conditions can be obtained.

[0073] Since the non-consistency of the grease 60 after being left at 85°C for 18 hours is greater than 158, the degree of hardening of the grease 60 can be set such that bleeding of the base oil occurs smoothly even when the grease 60 is exposed to high temperatures or left for a long time. Therefore, a rolling bearing 1 with high durability can be formed.

[0074] The grease 60 has an outer ring contact portion 61 that contacts the inner peripheral surface 22b of the protruding portion 22 of the outer ring 20, and a seal member contact portion 62 that contacts the flat portion 53 of the seal member 50 on the outer side in the axial direction and the inner side in the radial direction with respect to the outer ring contact portion 61. The area of the seal member contact portion 62 is larger than the contact area between the grease 60 and the seal member 50 with the extending portion 52 and the pedestal portion 51. According to this configuration, after applying the grease 60 to a predetermined location, when the seal member 50 is mounted, the grease 60 pushed inward in the axial direction by the flat portion 53 of the seal member 50 can be provided with room to spread radially toward the extending portion 52 and the pedestal portion 51. Therefore, it is possible to suppress the grease 60 from spreading greatly toward the inner ring 10 side and the rolling element 30 side. Thus, it is possible to easily suppress the grease 60 from directly contacting the rolling element 30 and the cage 40. Moreover, since the seal member 50 is provided with the extending portion 52 between the flat portion 53 and the pedestal portion 51, the grease 60 can be arranged at a position farther from the rolling element 30 as compared with a configuration in which the flat portion extends radially inward from the pedestal portion. Therefore, an increase in the amount of the grease 60 can be achieved. As described above, it is possible to provide the rolling bearing 1 that can achieve both ensuring durability and reducing rotational resistance.

[0075] Also, the seal member contact portion 62 includes the radial center position of the grease 60 in plan view. According to this configuration, when the seal member 50 is mounted, as a result of the grease 60 spreading radially by being pushed by the flat portion 53, since the seal member contact portion 62 includes the radial center position of the grease 60 in plan view, it is possible to suppress the grease 60 from spreading greatly inward in the axial direction toward the rolling element 30. Thus, it is possible to easily suppress the grease 60 from directly contacting the rolling element 30.

[0076] The grease 60 is non-contact with the extending portion 52. According to this configuration, when the seal member 50 is attached, a larger margin can be provided for the grease 60, which is pushed axially inward by the flat portion 53 of the seal member 50, to spread radially toward the extending portion 52. Therefore, it is possible to suppress the grease 60 from spreading greatly toward the inner ring 10 side and the rolling element 30 side. Thus, it is easily possible to suppress the grease 60 from contacting the rolling element 30, the cage 40, and the inner ring 10 more than necessary.

[0077] The outer ring contact portion 61 is provided at an axial interval with respect to the contact portion between the outer ring 20 and the pedestal portion 51. According to this configuration, it is possible to avoid the grease 60 from contacting the contact portion between the outer ring 20 and the pedestal portion 51. Thereby, it is possible to suppress the grease 60 from leaking to the outside of the seal member 50 due to capillary action through the contact portion between the outer ring 20 and the pedestal portion 51.

[0078] The grease 60 is non-contact with the pedestal portion 51. According to this configuration, it is possible to avoid the grease 60 from contacting the contact portion between the outer ring 20 and the pedestal portion 51. Thereby, it is possible to suppress the grease 60 from leaking to the outside of the seal member 50 due to capillary action through the contact portion between the outer ring 20 and the pedestal portion 51.

[0079] And according to the rotating device 2 of the present embodiment, since the rolling bearing 1 having excellent long-term durability is provided, it is possible to achieve a longer life of the rotating device 2.

[0080] In the first embodiment, the pedestal portion 51 of the seal member 50 protrudes radially inward from the end face 22a of the protruding portion 22 of the outer ring 20 in a plan view. However, it is desirable that the pedestal portion be arranged so as not to protrude radially inward from the end face 22a of the protruding portion 22 in a plan view. According to this configuration, even when the outer ring contact portion 61 of the grease 60 spreads axially outward and crosses the inner peripheral edge of the end face 22a, it is possible to suppress the adhesion of the grease 60 to the pedestal portion. Therefore, it is possible to avoid the grease 60 from contacting the contact portion between the outer ring 20 and the pedestal portion. As a result, it is possible to suppress the grease 60 from leaking to the outside of the seal member due to capillary action through the contact portion between the outer ring 20 and the pedestal portion.

[0081] Also, in the first embodiment, the grease 60 is non-contact with the pedestal portion 51 and the extending portion 52 of the seal member 50, but is not limited to this configuration. The grease may be in contact with at least one of the pedestal portion 51 and the extending portion 52 of the seal member 50. Here, the pedestal portion 51 and the extending portion 52 are located axially inside the flat portion 53 and are closer to the rolling elements 30 and the cage 40 than the flat portion 53. Therefore, when the seal member 50 is mounted, the grease 60 is pushed toward the rolling elements 30 and the cage 40 side and is likely to contact the rolling elements 30 or the cage 40. In this embodiment, the movement of the grease 60 axially inward can be suppressed, and it is possible to suppress the grease 60 from contacting the rolling elements 30 or the cage 40 more than necessary. Therefore, the grease 60 of this embodiment can be suitably used. However, when the grease 60 is in contact with at least one of the pedestal portion 51 and the extending portion 52 of the seal member 50, it is desirable that the area of the seal member contact portion be larger than the contact area between the grease and the extending portion 52 and the pedestal portion 51.

[0082] [Reference Embodiment] Next, with reference to FIG. 5, a reference embodiment will be described. The reference embodiment is different from the first embodiment in that the rolling bearing 1A includes a grease 160 instead of the grease 60 of the first embodiment. The configuration other than that described below is the same as that of the first embodiment.

[0083] The grease 160 is arranged along the circumferential direction. The grease 160 extends in an annular shape and is arranged coaxially with the common axis O. The grease 160 includes an outer ring contact portion 161 that contacts the inner circumferential surface 22b of the protrusion 22 of the outer ring 20, and is non-contact with respect to the inner ring 10, the seal member 50, the rolling elements 30, and the cage 40. The outer ring contact portion 161 extends in the circumferential direction over the entire length of the grease 160. The outer ring contact portion 161 has a width in the axial direction over the entire circumferential direction. The outer ring contact portion 161 contacts a portion of the inner circumferential surface 22b of the protrusion 22 that is axially spaced from the outer ring raceway surface 23. The outer ring contact portion 161 contacts a portion of the inner circumferential surface 22b of the protrusion 22 that is axially spaced from the inner peripheral edge of the upper end face 22a. That is, the outer ring contact portion 161 is provided axially spaced from the contact portion between the outer ring 20 and the pedestal portion 51 of the seal member 50.

[0084] The properties of the grease 160 are the same as those of the grease 60 in the first embodiment. That is, the immiscibility consistency of the grease 160 is greater than 178 and less than 287. The difference between the miscibility consistency and the immiscibility consistency of the grease 160 is preferably less than 50. The ratio of the difference between the miscibility consistency and the immiscibility consistency to the miscibility consistency of the grease 160 is preferably less than 22.7%.

[0085] In this embodiment, the same effects as those of the first embodiment are achieved. In addition, in this embodiment, since the grease 160 is non-contact with the seal member 50, the grease 160 is not pushed by the seal member 50 when the seal member 50 is attached to the outer ring 20. Thereby, the movement of the grease 160 inward in the axial direction can be suppressed, and the grease 160 can be prevented from contacting the rolling elements 30 or the cage 40 more than necessary. Therefore, an increase in the rotational resistance of the rolling bearing 1A can be suppressed.

[0086] In the reference embodiment, the grease 160 extends in an annular shape, but is not limited to this configuration. The grease may extend in an arc shape such that an intermittent portion is formed, or may include a plurality of granular bodies arranged in a dot pattern over the entire circumference. When the grease has a plurality of granular bodies, the plurality of granular bodies aligned in the circumferential direction may be integrated or may be spaced apart from each other.

[0087] [Second Embodiment] Next, with reference to FIG. 6, a second reference embodiment will be described. The rolling bearing 1B of the second reference embodiment is different from the rolling bearing 1A of the reference embodiment in that the grease 160A contacts the seal member 50 and the rolling elements 30. Note that the configuration other than that described below is the same as that of the reference embodiment.

[0088] The grease 160A further includes a seal member contact portion 162 that contacts the flat portion 53 of the seal member 50 on the outer side in the axial direction and the inner side in the radial direction rather than the outer ring contact portion 161, and is non-contact with respect to the inner ring 10. The seal member contact portion 162 contacts only the flat portion 53 of the seal member 50. Thereby, the grease 160A is non-contact with respect to the pedestal portion 51 and the extending portion 52 located on the outer ring 20 side rather than the flat portion 53 of the seal member 50. The grease 160A contacts the rolling elements 30. The volume of the portion of the grease 160A that contacts the rolling elements 30 is less than or equal to half of the total volume of the grease 160A. Note that the grease 160A may contact the cage 40.

[0089] The properties of the grease 160A are the same as those of the grease 60 of the first embodiment. That is, the immiscibility consistency of the grease 160A is greater than 178 and less than 287. The difference between the miscibility consistency and the immiscibility consistency of the grease 160A is preferably less than 50. The ratio of the difference between the miscibility consistency and the immiscibility consistency to the miscibility consistency of the grease 160A is preferably less than 22.7%.

[0090] In this embodiment, the same effects as those of the reference embodiment are achieved. In addition, in this embodiment, since the grease 160A is in contact with the rolling elements 30, the base oil of the grease 160A can be directly supplied to the rolling elements 30. Therefore, an increase in the rotational resistance of the rolling bearing 1B can be suppressed.

[0091] In the second embodiment, the grease 160A extends in an annular shape, but the present invention is not limited to this configuration. The grease may extend in an arc shape such that an intermittent portion is formed, or may include a plurality of granular bodies arranged in a dot pattern over the entire circumference. When the grease has a plurality of granular bodies, the plurality of granular bodies aligned in the circumferential direction may be integrated or may be spaced apart from each other.

Example

[0092] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to the following description.

[0093] The viscosity of the grease in this example was measured at 40 °C in accordance with JIS K2283. The consistency of the grease in this example was measured by the method defined in JIS K2220.

[0094] The greases of Examples 1 to 5 and Comparative Examples 1 to 4 were prepared as follows.

[0095] <Example 1> An ester oil and PAO were mixed at a mass ratio (ester oil / PAO) > 1 to obtain a base oil having a kinematic viscosity of 44 mm 2 / s. In this base oil, an alicyclic urea was synthesized as a thickener to obtain a grease having a work consistency of 228, a non-work consistency of 227, and a non-work consistency of 188 after high-temperature storage.

[0096] <Example 2> Using the same base oil and thickener as in Example 1, the ratio of the thickener to the base oil was adjusted to obtain a grease having a work consistency of 261, a non-work consistency of 255, and a non-work consistency of 210 after high-temperature storage.

[0097] <Example 3> An ether oil and an ester oil were mixed at a mass ratio (ether oil / ester oil) > 1 to obtain a base oil with a kinematic viscosity of 80 mm 2 / s. In this base oil, an alicyclic urea was synthesized to obtain a grease with a blending consistency of 290, a non-blending consistency of 274, and a non-blending consistency of 282 after high-temperature storage.

[0098] <Example 4> PAO alone was used as a base oil with a kinematic viscosity of 48 mm 2 / s. In this base oil, an alicyclic urea and an aliphatic urea were synthesized to obtain a grease with a blending consistency of 199, a non-blending consistency of 197, and a non-blending consistency of 200 after high-temperature storage.

[0099] <Example 5> Ester oil alone was used as a base oil with a kinematic viscosity of 100 mm 2 / s. In this base oil, an alicyclic urea and an aliphatic urea were synthesized to obtain a grease with a blending consistency of 265, a non-blending consistency of 245, and a non-blending consistency of 244 after high-temperature storage.

[0100] <Comparative Example 1> PAO alone was used as a base oil with a kinematic viscosity of 48 mm 2 / s. In this base oil, an alicyclic urea and an aliphatic urea were synthesized as thickeners to obtain a grease with a blending consistency of 220, a non-blending consistency of 170, and a non-blending consistency of 158 after high-temperature storage.

[0101] <Comparative Example 2> PAO and an ester oil were mixed at a mass ratio (PAO / ester oil) > 1 to obtain a base oil with a kinematic viscosity of 22 mm 2 / s. In this base oil, an alicyclic urea and an aliphatic urea were synthesized as thickeners to obtain a grease with a blending consistency of 232, a non-blending consistency of 178, and a non-blending consistency of 149 after high-temperature storage.

[0102] <Comparative Example 3> Using the same base oil and thickener as in Example 1, the ratio of the thickener to the base oil was adjusted to obtain a grease with a blending consistency of 295, a non-blending consistency of 287, and a non-blending consistency of 236 after high-temperature storage.

[0103] <Comparative Example 4> Mineral oil and PAO were mixed at a mass ratio (mineral oil / PAO) ≈ 1 to obtain a base oil with a kinematic viscosity of 52 mm 2 / s. In this base oil, alicyclic urea and aliphatic urea were synthesized as thickeners to obtain a grease with a blending consistency of 248, a non-blending consistency of 164, and a non-blending consistency of 155 after high-temperature storage.

[0104] For each of the greases of the above Examples 1 to 5 and Comparative Examples 1, 2, and 4, a durability test of the rolling bearing was conducted under the following conditions. Note that when the grease of Comparative Example 3 was used in the following rolling bearing, the variation in the individual rotational resistance of the rolling bearing became larger than the predetermined required value, and the variation in the rotational resistance with respect to the operating time occurred. Therefore, it was determined to be unsuitable as a grease for the rolling bearing and was excluded from the object of the durability test.

[0105] (Shape of the rolling bearing) A rolling bearing with an outer ring outer diameter of 8 mm, an inner ring inner diameter of 3 mm, and a height (axial thickness) of 4 mm was used.

[0106] (Arrangement of the grease) 12 mg of the grease was applied in the shape of the grease 60 of the first embodiment.

[0107] (Method for evaluating durability) Two rolling bearings using the same grease were incorporated into one fan motor (rated rotational speed 25000 rpm). Five fan motors were prepared for each of the greases of Examples 1 to 3 and Comparative Examples 1 and 2, and they were continuously operated in a high-temperature bath at 85°C. The operating status and the presence or absence of abnormal noise were confirmed every 500 hours. The evaluation results are shown in Table 1.

[0108]

Table 1

[0109] When using the grease of Comparative Example 1, abnormal noise was confirmed in 3 out of 5 fan motors after 3000 hours of operation. When using the grease of Comparative Example 2, 1 out of 5 fan motors stopped after 2000 hours of operation, and another 2 stopped after 2500 hours of operation. On the other hand, when using the greases of Examples 1 to 3 respectively, the 5 fan motors operated stably without generating abnormal noise even after 5000 hours of operation. From the above, it is clear that if the immiscibility degree of the grease is greater than 178 and less than 287, it is possible to suppress variations in the rotational resistance of each rolling bearing while improving the durability of the rolling bearing. Further, it is clear that if the difference between the miscibility degree and the immiscibility degree is less than 50 while the immiscibility degree of the grease satisfies the above conditions, the durability of the rolling bearing can be surely improved. Also, it is clear that if the ratio of the difference between the miscibility degree and the immiscibility degree to the miscibility degree is less than 22.7% while the immiscibility degree of the grease satisfies the above conditions, the durability of the rolling bearing can be surely improved.

[0110] Note that the present invention is not limited to the above-described embodiments described with reference to the drawings, and various modifications can be considered within its technical scope. For example, in the above embodiment, the inner ring 10 is provided as a rotating ring, and the outer ring 20 is provided as a fixed ring. And the greases 60, 160A are in contact with the outer ring 20 which is a fixed ring. However, the raceway ring with which the grease contacts does not have to be a fixed ring. That is, the inner ring may be provided as a fixed ring, the outer ring may be provided as a rotating ring, and the grease may be in contact with the inner ring which is a fixed ring. Also, the inner ring may be provided as a fixed ring, the outer ring may be provided as a rotating ring, and the grease may be in contact with the outer ring which is a rotating ring. Further, in the above embodiment, the rolling elements 30 are held by the cage 40, but the present invention may also be applied to a rolling bearing without a cage.

[0111] In addition, in each of the above-described embodiments and their modifications, although the grease is disposed along the circumferential direction for approximately one turn, the present invention is not limited to this configuration. The grease may include a first annular portion that contacts the outer ring 20 and a second annular portion that is continuous with the first annular portion and contacts the seal member 50. In this case, the first annular portion and the second annular portion each extend annularly about the common axis O. However, at least one of the first annular portion and the second annular portion may extend less than 360° about the common axis O. Further, at least one of the first annular portion and the second annular portion may include a plurality of granular bodies disposed in a dot pattern over the entire circumference.

[0112] In addition to or instead of the greases 60 and 160A, grease may be disposed in the grease pockets of the cage, on the lower end surface, or the like of the rolling bearing. In this case, it is desirable that the grease disposed in the cage does not contact the rolling elements. An example of disposing the grease 60 in the cage 40 is shown in FIG. 7. As shown in FIG. 7, the cage 40 includes the annular portion 41 and the plurality of column portions 42 described above. Further, a grease pocket 47 that is recessed downward is formed in the upper end surface 40u of the cage 40. The grease pocket 47 is formed between a pair of adjacent ball pockets B in the circumferential direction. That is, the grease pocket 47 is formed in each column portion 42. The grease 60 is disposed in the grease pocket 47. Note that the grease may be disposed on the lower end surface of the cage 40 in addition to or instead of the grease pocket 47. However, when grease is disposed in the cage 40, the grease disposed in the cage 40 is disposed separately from the grease applied so as to contact the raceway ring and the seal member. That is, the grease disposed in the cage 40 does not contact the raceway ring and the seal member.

[0113] Further, in each of the above embodiments, the grease 60, 160A is in contact with the inner peripheral surface of the outer ring 20, but the present invention is not limited to this configuration. The grease may not be in contact with the raceway ring and may be in contact with only the seal member 50. That is, the grease may be in contact with at least one of the circumferential surface (inner peripheral surface or outer peripheral surface) of one of the raceway rings facing the other raceway ring and the seal member 50.

[0114] In the above embodiment, a fan motor is exemplified as the rotating device, but the rotating device is not limited to this. For example, the present invention may be applied to a dental handpiece, a spindle motor of a hard disk drive, or the like as the rotating device. Particularly in the case of a rolling bearing applied to a spindle motor of a hard disk drive, low torque is required and the rotation angle is less than 360°. Since a configuration in which grease is disposed in a cage is suitable, the grease of the present invention in which the base oil easily oozes out without being sheared is useful.

[0115] Further, the present invention does not limit the size of the rolling bearing. The size of the rolling bearing used in the endurance test of the above example is an example of a small bearing (outer diameter of 30 mm or less) used for a small motor in which the torque of the motor is small and the bearing is easily affected by the bearing torque due to grease. The present invention particularly has great advantages in rolling bearings with an outer diameter of 16 mm or less.

[0116] In addition, without departing from the spirit of the present invention, it is possible to appropriately replace the components in the above-described embodiments with well-known components, and the above-described embodiments and each modification may be appropriately combined.

Explanation of Reference Numerals

[0117] 1, 1B... bearing 2... rotating device 10... inner ring (the other raceway ring) 20... outer ring (one raceway ring) 22... protrusion 22a... end face 30... rolling element 40... cage 50... seal member 51... pedestal portion 52... extending portion 53... flat portion 60, 160A... grease 61, 161... outer ring contact portion (raceway ring contact portion) 62, 162... seal member contact portion

Claims

1. An inner ring and an outer ring arranged coaxially with each other, rolling elements arranged between the inner ring and the outer ring, a seal member attached to one of the raceways of the inner ring and the outer ring, covering the space between the inner ring and the outer ring from the outside in the axial direction, grease arranged between the rolling elements and the seal member, characterized in that the grease contacts the circumferential surface of the one raceway ring facing the other raceway ring of the inner ring and the outer ring, and also contacts the seal member, the seal member has an annular pedestal portion contacting the one raceway ring from the outside in the axial direction, an extension portion extending outward in the axial direction from the peripheral edge of the pedestal portion on the side of the other raceway ring, and a flat portion extending along the radial direction from the outer edge in the axial direction of the extension portion toward the other raceway ring, and the grease has a raceway ring contact portion contacting the circumferential surface of the one raceway ring, and a seal member contact portion contacting the flat portion on the side of the other raceway ring and outside the raceway ring contact portion in the axial direction, and the grease is non-contact with the extension portion, the area of the seal member contact portion is larger than the contact area of the grease with the extension portion and the pedestal portion among the grease and the seal member, the unworkability of the grease is greater than 178 and less than 287, a rolling bearing.

2. The difference between the workability and the unworkability of the grease is less than 50, the rolling bearing according to Claim 1.

3. The ratio of the difference between the workability and the unworkability of the grease to the workability of the grease is less than 22.7%, the rolling bearing according to Claim 1.

4. The thickener of the grease contains urea, the rolling bearing according to any one of Claims 1 to 3.

5. The unworkability of the grease after being left for 18 hours at 85°C is greater than 158, the rolling bearing according to any one of Claims 1 to 3.

6. The grease contacts at least one of the pedestal portion and the extension portion, the rolling bearing according to any one of Claims 1 to 3.

7. The seal member contact portion includes the radial center position of the grease when viewed from the axial direction, the rolling bearing according to any one of Claims 1 to 3.

8. The raceway wheel contact portion is provided at an interval in the axial direction with respect to the contact portion between the one raceway wheel and the pedestal portion. The rolling bearing according to any one of claims 1 to 3.

9. The grease is non-contact with the pedestal portion. The rolling bearing according to any one of claims 1 to 3.

10. The one raceway wheel has a protruding portion that protrudes toward the other raceway wheel side and on which a raceway surface is formed. The protruding portion faces the outside in the axial direction and is connected to the peripheral surface at the periphery on the other raceway wheel side, and has an end surface that contacts the pedestal portion. The pedestal portion is arranged so as not to protrude toward the other raceway wheel side beyond the end surface when viewed from the axial direction. The rolling bearing according to any one of claims 1 to 3.

11. A rotating body rotatably arranged; A support body that rotatably supports the rotating body; The rolling bearing according to claim 1 interposed between the rotating body and the support body; A rotating device comprising the same.

12. An inner ring and an outer ring arranged coaxially with each other; Rolling elements arranged between the inner ring and the outer ring; A seal member attached to one of the raceway wheels of the inner ring and the outer ring and covering between the inner ring and the outer ring from the outside in the axial direction; Grease arranged between the rolling elements and the seal member; Comprising, The seal member, An annular pedestal portion that contacts the one raceway wheel from the outside in the axial direction; An extending portion that extends outward in the axial direction from the periphery on the other raceway wheel side of the inner ring and the outer ring in the pedestal portion; A flat portion that extends along the radial direction from the outer edge in the axial direction of the extending portion toward the other raceway wheel; A method for manufacturing a rolling bearing having the same, A coating step of bringing the grease into contact with the peripheral surface of the one raceway wheel facing the other raceway wheel of the inner ring and the outer ring to form a raceway wheel contact portion where the grease contacts the peripheral surface of the one raceway wheel, and coating the grease so as to protrude outward in the axial direction and toward the other raceway wheel side from the contact portion with the one raceway wheel. A contacting step of bringing the seal member closer to the one raceway ring from the outer side in the axial direction, bringing the flat portion into contact with the outer edge in the axial direction of the grease, and forming a seal member contact portion that is located on the outer side in the axial direction of the raceway ring contact portion in the grease and that contacts the flat portion on the other raceway ring side; After the contacting step, a mounting step of bringing the seal member closer to the one raceway ring and bringing the pedestal portion into contact with the one raceway ring from the outer side in the axial direction, and pushing the grease inward in the axial direction with the flat portion so that the grease does not contact the extending portion; comprising: By performing the mounting step, the area of the seal member contact portion is made larger than the contact area between the grease and the seal member with respect to the extending portion and the pedestal portion; the immiscibility degree of the grease is made greater than 178 and less than 287; A method for manufacturing a rolling bearing.

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