Rotating machinery

Abstract

To secure durability and achieve low power consumption in a rotary device including two rolling bearings arranged in an axial direction.SOLUTION: A fan motor 100 includes: a rotating body 110 having a shaft part 111; a base part 120 supporting the rotating body 110; and a first rolling bearing 1 and a second rolling bearing 2 which are attached to the base part 120, rotatably support the shaft part 111, and are arranged in an axial direction of the rotating body 110. The first rolling bearing 1 is disposed closer to a centroid of the rotating body 110 than the second rolling bearing 2. Each of the first rolling bearing 1 and the second rolling bearing 2 has: an inner ring and an outer ring arranged coaxially with each other; rolling elements disposed between the inner ring and the outer ring; and grease disposed between the inner ring and the outer ring. The grease is arranged so that rotational resistance of the second rolling bearing 2 becomes smaller than rotational resistance of the first rolling bearing 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotating device.

Background Art

[0002] Generally, a rolling bearing includes an outer ring and an inner ring arranged coaxially, a plurality of rolling elements disposed between the inner ring and the outer ring, and a cage that holds each rolling element in a state where the plurality of rolling elements are evenly arranged in the circumferential direction and allows each rolling element to roll. This type of rolling bearing includes various types according to the type of load to be supported (radial load, axial load, etc.) and applications, and is incorporated into various rotating devices and used. In particular, a ball bearing that uses balls as rolling elements is suitably used for a rotating device having a shaft portion of a rotating body that rotates at high speed.

[0003] As this type of rotating device, there is a fan motor (see, for example, Patent Document 1). Patent Document 1 discloses a fan motor in which an impeller is provided integrally with a motor yoke on a shaft rotatably supported by a rolling bearing. This fan motor includes two rolling bearings arranged at intervals in the axial direction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in rotating machinery equipped with two rolling bearings aligned axially, the load acting on the two rolling bearings may differ due to the uneven distribution of the center of gravity of the rotating body supported by the rolling bearings. As a result, one of the two rolling bearings may reach the end of its product life earlier than the other, potentially leading to the end of the rotating machinery's lifespan. However, increasing the amount of grease to improve the durability of the rotating machinery can increase the power consumption of the machinery due to the increased rotational resistance of the rolling bearings (the rotational resistance of the rotating wheel relative to the stationary wheel). Therefore, conventional rotating machinery faces the challenge of achieving both durability to withstand high-speed rotation and low power consumption.

[0006] Therefore, the present invention aims to achieve both durability and low power consumption in a rotating device equipped with two rolling bearings arranged in the axial direction. [Means for solving the problem]

[0007] A rotating device according to a first aspect of the present invention comprises a rotating body having a shaft, a base supporting the rotating body, and a first rolling bearing and a second rolling bearing mounted on the base and rotatably supporting the shaft, arranged in the axial direction of the rotating body, wherein the first rolling bearing is positioned closer to the center of gravity of the rotating body than the second rolling bearing, and each of the first and second rolling bearings has an inner ring and an outer ring arranged coaxially with respect to each other, rolling elements arranged between the inner ring and the outer ring, and grease arranged between the inner ring and the outer ring, wherein the grease is arranged such that the rotational resistance of the second rolling bearing is less than the rotational resistance of the first rolling bearing.

[0008] Since the first rolling bearing is positioned closer to the center of gravity of the rotating body than the second rolling bearing, the centrifugal force caused by the slight eccentricity of the rotating body places a greater load on the first rolling bearing than on the second rolling bearing. According to the first embodiment, since the rotational resistance of the second rolling bearing is smaller than that of the first rolling bearing, if the durability of the first rolling bearing is improved to be greater than that of the second rolling bearing in exchange for an increase in the rotational resistance of the first rolling bearing, the increase in the rotational resistance of the first rolling bearing can be offset. Therefore, it is possible to achieve both the durability of the rotating equipment and low power consumption.

[0009] A second aspect of the present invention is a rotating device in the first aspect described above, wherein the second rolling bearing has a sealing member that covers the grease from the side opposite to the rolling elements, and the grease of the second rolling bearing may include a first annular portion that extends circumferentially around the common axis of the inner ring and the outer ring and contacts one of the inner ring and the outer ring, and a second annular portion that extends circumferentially around the common axis, is connected to the first annular portion on the outer side in the axial direction and contacts the sealing member.

[0010] According to the second embodiment, when distributing a desired amount of grease in the second rolling bearing, the volume of the first annular portion can be reduced compared to the case where grease is applied so as to form a single annular portion, because the first annular portion and the second annular portion are formed. Therefore, by forming the first annular portion before the second annular portion when applying grease, it is possible to prevent the first annular portion from collapsing due to its own weight. Furthermore, by providing the second annular portion, the second annular portion is supported by the sealing member, and the first annular portion is supported not only by the inner ring and the outer ring, but also by the sealing member via the second annular portion. Therefore, the grease as a whole is less likely to collapse from its shape immediately after application due to its own weight. Thus, it is possible to suppress the grease from contacting the rolling elements more than necessary. Consequently, the rotational resistance of the second rolling bearing can be reduced.

[0011] A rotating device according to a third aspect of the present invention is a rotating device according to the first aspect described above, wherein the second rolling bearing has a sealing member that covers the grease from the side opposite to the rolling elements, and the grease of the second rolling bearing has a raceway contact portion that is arranged along the circumferential direction centered on the common axis of the inner ring and the outer ring and contacts one of the inner ring and the outer ring, and a sealing member contact portion that is arranged along the circumferential direction, is connected to the raceway contact portion on the outer side in the axial direction and contacts the sealing member, and at least one of the raceway contact portion and the sealing member contact portion may have granular material arranged in a point-like manner over the entire circumference.

[0012] According to the third embodiment, when distributing a desired amount of grease in the second rolling bearing, the volume of the raceway contact portion can be reduced compared to the case where grease is applied only around the circumference, because the raceway contact portion and the seal member contact portion are formed. Therefore, by forming the raceway contact portion before the seal member contact portion when applying grease, it is possible to prevent the raceway contact portion from collapsing due to its own weight. In addition, by providing a seal member contact portion, the seal member contact portion is supported by the seal member, and the raceway contact portion is supported not only by the inner ring and the outer ring, but also by the seal member via the seal member contact portion. Therefore, the grease as a whole is less likely to collapse from its shape immediately after application due to its own weight. Thus, it is possible to suppress the grease from contacting the rolling elements more than necessary. Therefore, the rotational resistance of the second rolling bearing can be reduced.

[0013] A rotating device according to a fourth aspect of the present invention is a rotating device according to the first aspect described above, wherein the second rolling bearing is disposed between the inner ring and the outer ring and has an annular cage that holds the rolling elements so as to be rotatable, the cage has ball pockets that penetrate radially and open in a first axial direction and hold each of the rolling elements so as to be rotatable, and the grease of the second rolling bearing may be disposed only on the end face of the cage that faces the second axial direction.

[0014] According to the fourth aspect, in the second rolling bearing, grease can be applied to any point on the entire circumference of the second end face of the cage. Compared to the case where grease is applied to the first end face of the cage while avoiding the ball pocket opening and the rolling elements, the amount of grease can be increased while suppressing direct contact of the grease with the rolling elements, inner ring, and outer ring. Therefore, the rotational resistance of the second rolling bearing can be reduced.

[0015] A fifth aspect of the present invention is a rotating device according to any of the first to fourth aspects described above, wherein the grease of the first rolling bearing may have rolling element contact portions arranged along the circumferential direction centered on the common axis of the inner ring and the outer ring and in contact with the rolling elements over the entire circumference.

[0016] According to the fifth aspect, it becomes easier to supply grease to the rolling elements and the outer ring of the first rolling bearing. Therefore, the durability of the first rolling bearing can be improved at the expense of an increase in the rotational resistance of the first rolling bearing due to grease contact.

[0017] A rotating device according to a sixth aspect of the present invention is a rotating device according to any of the first to fifth aspects described above, wherein the grease of the first rolling bearing may have an annular contact portion that is arranged along the circumferential direction centered on the common axis of the inner ring and the outer ring and contacts the fixed ring of the inner ring and the outer ring over its entire circumference.

[0018] According to the sixth aspect, it is easier to supply grease to the rolling elements and the outer ring in the first rolling bearing. Therefore, the durability of the first rolling bearing can be improved at the expense of an increase in the rotational resistance of the first rolling bearing due to grease contact.

[0019] A rotating device according to a seventh aspect of the present invention is a rotating device according to the fifth or sixth aspect of the present invention, wherein the first rolling bearing has an annular cage disposed between the inner ring and the outer ring and holding the rolling elements so as to be rotatable, and the grease of the first rolling bearing may have a cage coating portion disposed on the end face of the cage facing the second axial direction.

[0020] According to the seventh embodiment, the amount of grease in the first rolling bearing can be increased, thereby improving the durability of the first rolling bearing. Furthermore, since the amount of grease in the second rolling bearing is relatively reduced compared to the amount of grease in the first rolling bearing, the rotational resistance of the second rolling bearing can be made even smaller than that of the first rolling bearing.

[0021] In the eighth aspect of the present invention, the rotating equipment according to any of the first to seventh aspects described above, the amount of grease in the second rolling bearing may be less than the amount of grease in the first rolling bearing.

[0022] According to the eighth aspect, it becomes easier to supply grease to the rolling elements and outer ring in the first rolling bearing. Therefore, the durability of the first rolling bearing can be improved in exchange for an increase in the rotational resistance of the first rolling bearing due to grease contact. Furthermore, the rotational resistance of the second rolling bearing can be easily made smaller than that of the first rolling bearing. This makes it easier to offset the increase in the rotational resistance of the first rolling bearing. Therefore, it is possible to achieve both the durability of the rotating equipment and low power consumption.

[0023] In the rotating equipment according to the ninth aspect of the present invention, in the rotating equipment according to any of the first to eighth aspects described above, the base oil viscosity of the grease in the second rolling bearing may be lower than the base oil viscosity of the grease in the first rolling bearing.

[0024] According to the ninth aspect, it is possible to improve the heat resistance of the grease of the first rolling bearing, and a thick grease oil film can be formed between the rolling elements and the outer ring in the first rolling bearing. Therefore, in exchange for an increase in the rotational resistance of the first rolling bearing, the durability of the first rolling bearing can be improved. Furthermore, the rotational resistance of the second rolling bearing can be made smaller more easily than the rotational resistance of the first rolling bearing. For this reason, it becomes easier to offset the increase in the rotational resistance of the first rolling bearing. Therefore, it is possible to achieve both ensuring the durability of the rotating device and reducing power consumption.

[0025] The rotating device according to the tenth aspect of the present invention is the rotating device according to any one of the first aspect to the ninth aspect, in which the consistency of the grease of the second rolling bearing may be smaller than the consistency of the grease of the first rolling bearing.

[0026] According to the tenth aspect, churning of the grease is more likely to occur in the first rolling bearing than in the second rolling bearing. Thereby, in exchange for an increase in the rotational resistance of the first rolling bearing, the durability of the first rolling bearing can be improved. Also, in the second rolling bearing, channelling of the grease is more likely to occur than in the first rolling bearing. Thereby, the rotational resistance of the second rolling bearing can be made smaller than the rotational resistance of the first rolling bearing. For this reason, the increase in the rotational resistance of the first rolling bearing can be offset. Therefore, it is possible to achieve both ensuring the durability of the rotating device and reducing power consumption.

[0027] The rotating device according to the eleventh aspect of the present invention is the rotating device according to any one of the first aspect to the tenth aspect, in which the thickener of the grease of the first rolling bearing and the thickener of the grease of the second rolling bearing are urea compounds, and the content of aliphatic urea in the thickener in the grease of the second rolling bearing may be larger than the content of aliphatic urea in the thickener in the grease of the first rolling bearing.

[0028] Generally, aliphatic ureas have good affinity with base oils, and a small amount can convert the base oil into a semi-solid grease. Therefore, by using aliphatic ureas as a thickener, a grease of a predetermined consistency can be obtained with a smaller amount of thickener compared to when alicyclic ureas or aromatic ureas are used as the thickener. On the other hand, by using alicyclic ureas and aromatic ureas, a grease with higher heat resistance can be obtained compared to when aliphatic ureas are used. According to the 11th embodiment, the amount of thickener contained in the grease of the second rolling bearing can be reduced compared to the amount of thickener contained in the grease of the first rolling bearing. Therefore, the rotational resistance of the second rolling bearing can be made smaller than the rotational resistance of the first rolling bearing. Therefore, an increase in the rotational resistance of the first rolling bearing can be tolerated. Furthermore, by increasing the content of alicyclic ureas and aromatic ureas in the thickener of the grease for the first rolling bearing compared to that of the grease for the second rolling bearing, the heat resistance of the grease for the first rolling bearing can be improved at the expense of increased rotational resistance. Therefore, the durability of the first rolling bearing can be improved. Consequently, it is possible to achieve both increased durability of the rotating equipment and reduced power consumption.

[0029] In a rotating device according to a twelfth aspect of the present invention, in a rotating device according to any of the first to eleventh aspects described above, the distance between the grease and the rolling element in the second rolling bearing may be wider than the distance between the grease and the rolling element in the first rolling bearing.

[0030] According to the twelfth embodiment, compared to the second rolling bearing, it is easier to supply grease to the rolling elements and outer ring in the first rolling bearing. Therefore, the durability of the first rolling bearing can be improved in exchange for an increase in the rotational resistance of the first rolling bearing due to grease contact. Furthermore, the rotational resistance of the second rolling bearing can be easily made smaller than that of the first rolling bearing. This makes it easier to offset the increase in the rotational resistance of the first rolling bearing. Therefore, it is possible to achieve both the durability of the rotating equipment and low power consumption. [Effects of the Invention]

[0031] According to the present invention, in a rotating device equipped with two rolling bearings aligned in the axial direction, it is possible to achieve both durability and low power consumption. [Brief explanation of the drawing]

[0032] [Figure 1] This is a longitudinal cross-sectional view showing a fan motor of an embodiment. [Figure 2] This is a plan view of the first rolling bearing of the first embodiment. [Figure 3] This is a longitudinal cross-sectional view of the first rolling bearing of the first embodiment. [Figure 4] This is a longitudinal cross-sectional view of the second rolling bearing of the first embodiment. [Figure 5] This is a plan view of the second rolling bearing of the first embodiment. [Figure 6] This is a longitudinal cross-sectional view of the second rolling bearing of the second embodiment. [Figure 7] This is a plan view of the second rolling bearing of the second embodiment. [Figure 8] This is a longitudinal cross-sectional view of the second rolling bearing of the third embodiment. [Modes for carrying out the invention]

[0033] Embodiments of the present invention will be described below with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplication of these components may be omitted.

[0034] Figure 1 is a longitudinal cross-sectional view showing a fan motor according to an embodiment. The fan motor 100 shown in Figure 1 is an example of a rotating device. The fan motor 100 comprises a rotating body 110 having a shaft portion 111, a base portion 120 that supports the rotating body 110, a drive unit 130 that rotates the rotating body 110 relative to the base portion 120, and a first rolling bearing 1 and a second rolling bearing 2 mounted on the base portion 120 that rotatably support the shaft portion 111. In the following description, rolling bearings may be simply referred to as bearings. In this embodiment, the direction in which the central axis O of the shaft portion 111 of the rotating body 110 extends is called the axial direction, the direction perpendicular to the central axis O and extending radially from the central axis O is called the radial direction, and the direction that revolves around the central axis O is called the circumferential direction. In addition, one of the directions parallel to the axial direction and pointing in opposite directions is defined as upward (first direction), and the other is defined as downward (second direction).

[0035] The base portion 120 has a cylindrical portion 121 that extends in the axial direction. The shaft portion 111 of the rotating body 110 is inserted into the cylindrical portion 121. The rotating body 110 is positioned above the base 120. The rotating body 110 comprises a shaft portion 111 and a fan 112 connected to the shaft portion 111 on the outside of the cylindrical portion 121. The fan 112 is fixed to the upper end of the shaft portion 111. The fan 112 comprises a flange 113 that extends radially outward from the upper end of the shaft portion 111 and extends over its entire circumference, a circumferential wall portion 114 that extends downward from the entire outer edge of the flange 113, and a plurality of blades 115 arranged at circumferential intervals on the radially outward side of the circumferential wall portion 114. The circumferential wall portion 114 surrounds the cylindrical portion 121 over its entire circumference, with a radial gap between it and the cylindrical portion 121.

[0036] The drive unit 130 is a motor. The drive unit 130 comprises a stator 131 having coils and a rotor 132 having magnets. The stator 131 is fixed to the base 120 on the outside of the shaft 111. The rotor 132 is fixed to the peripheral wall 114 of the fan 112 on the radially outer side of the stator 131.

[0037] The first bearing 1 and the second bearing 2 are interposed between the inner circumferential surface of the cylindrical portion 121 and the outer circumferential surface of the shaft portion 111. The first bearing 1 and the second bearing 2 are ball bearings. The first bearing 1 and the second bearing 2 are arranged coaxially with respect to each other. The first bearing 1 and the second bearing 2 are spaced apart in the axial direction. The first bearing 1 is positioned closer to the center of gravity of the rotating body 110 than the second bearing 2. The first bearing 1 is positioned above the second bearing 2.

[0038] The first bearing 1 is inserted into the cylindrical portion 121 from above. The first bearing 1 is in contact with the first biasing member 101 and the second biasing member 102. The first biasing member 101 and the second biasing member 102 are coil springs. The first biasing member 101 and the second biasing member 102 are externally fitted onto the shaft portion 111 of the rotating body 110 and are arranged coaxially with the central axis O. The first biasing member 101 is positioned inside the cylindrical portion 121 in a compressed state. The upper end of the first biasing member 101 is in contact with the outer ring of the first bearing 1 from below. The lower end of the first biasing member 101 is restricted from downward displacement by a step on the inner circumferential surface of the cylindrical portion 121. As a result, the first biasing member 101 biases the first bearing 1 upward relative to the cylindrical portion 121. The second biasing member 102 is interposed in a compressed state between the second bearing 2 and the flange 113 of the fan 112. The upper end of the second biasing member 102 is in contact with the flange 113 from below. The lower end of the second biasing member 102 is in contact with the outer ring of the first bearing 1 from above. As a result, the second biasing member 102 biases the first bearing 1 downward relative to the rotating body 110.

[0039] The second bearing 2 is inserted into the cylindrical portion 121 from below. The outer ring of the second bearing 2 is restricted from upward displacement by the stepped surface on the inner circumferential surface of the cylindrical portion 121. The inner ring of the second bearing 2 is in contact with the C-ring 103 mounted on the lower end of the shaft portion 111 from above. This restricts the downward displacement of the second bearing 2 relative to the shaft portion 111.

[0040] [First Embodiment] Figure 2 is a plan view of the first rolling bearing of the first embodiment. Figure 3 is a longitudinal cross-sectional view of the first rolling bearing of the first embodiment. Figure 4 is a longitudinal cross-sectional view of the second rolling bearing of the first embodiment. As shown in Figures 2 to 4, the first bearing 1 and the second bearing 2 have the same configuration except for the greases 60 and 70 described later. Each of the first bearing 1 and the second bearing 2 comprises an inner ring 10 and an outer ring 20 which are raceway rings, a plurality of rolling elements 30, a cage 40, and a pair of sealing members 50. The inner ring 10 and the outer ring 20 share a common axis O.

[0041] The inner ring 10 is provided as a rotating ring. The inner ring 10 is fitted onto the shaft portion 111. The outer ring 20 is provided as a stationary ring. The outer ring 20 surrounds the inner ring 10 from the radial outside, with an annular space between them. Multiple rolling elements 30 are arranged between the inner ring 10 and the outer ring 20 and are held in a rotatable position by a cage 40. The cage 40 holds each rolling element 30 rotatably, with the multiple rolling elements 30 evenly arranged in the circumferential direction. The sealing member 50 covers the annular space between the inner ring 10 and the outer ring 20 from the axial outside.

[0042] The outer ring 20 is formed in an annular shape from a metallic material such as stainless steel or bearing steel. However, the outer ring 20 is not limited to metal and may be formed from other materials. The outer ring 20 has an outer ring body 21 whose width along the axial direction is equal to the width along the axial direction of the inner ring 10, and a projection 22 that protrudes radially inward from the outer ring body 21 and extends along the entire circumference. The projection 22 is formed in the part of the outer ring body 21 that is located in the axial center. The width of the projection 22 along the axial direction is shorter than the width of the outer ring body 21 along the axial direction and is larger than the outer diameter of the rolling element 30.

[0043] An outer ring raceway surface 23 is formed on the inner circumferential surface of the projection 22, which is recessed radially outward. The outer ring raceway surface 23 is formed in a hemispherical shape in cross-section so as to follow the outer surface of the rolling element 30, and is also formed in an annular shape that extends circumferentially over the entire circumference of the inner circumferential surface of the projection 22. The outer ring raceway surface 23 is formed on the portion of the inner circumferential surface of the projection 22 that is located in the axial center. The portion of the inner circumferential surface of the projection 22 excluding the outer ring raceway surface 23 extends axially with a constant inner diameter. The projection 22 has a pair of end faces 22a facing axially. Each end face 22a extends parallel to the radial and circumferential directions.

[0044] The outer ring body 21 has a pair of inner circumferential surfaces 21a that extend from the outer peripheral edge of each end face 22a of the protrusion 22 to the opening edge of the outer ring 20. The portion of each inner circumferential surface 21a located axially inward is located radially outward than the portion located axially outward.

[0045] The inner ring 10 is formed in an annular shape from a metallic material such as stainless steel or bearing steel. However, the inner ring 10 is not limited to metal and may be formed from other materials. An inner ring raceway surface 11 is formed on the outer circumferential surface of the inner ring 10, which is recessed radially inward. The inner ring raceway surface 11 is formed in a hemispherical shape in cross-section, following the outer surface of the rolling element 30, and is formed in an annular shape that extends circumferentially around the entire circumference of the outer circumferential surface. The inner ring raceway surface 11 is formed in the portion of the outer circumferential surface of the inner ring 10 that is located in the axial center, and is arranged to face the outer ring raceway surface 23 radially. The portion of the outer circumferential surface of the inner ring 10 excluding the inner ring raceway surface 11 extends axially with a constant outer diameter.

[0046] Multiple rolling elements 30 are formed spherically from a metallic material such as stainless steel or bearing steel. The multiple rolling elements 30 are arranged between the outer ring raceway surface 23 and the inner ring raceway surface 11 and are supported so as to be able to roll by the outer ring raceway surface 23 and the inner ring raceway surface 11. The multiple rolling elements 30 are spaced apart in the circumferential direction by a cage 40.

[0047] As shown in Figures 3 and 4, the retainer 40 is formed as an annular shape from a synthetic resin or metal material. The retainer 40 is arranged coaxially with the central axis O. The retainer 40 comprises an annular portion 41 formed in an annular shape and positioned below the plurality of rolling elements 30, and a plurality of columnar portions 42 projecting upward from the annular portion 41 and spaced apart in the circumferential direction. The columnar portions 42 are evenly arranged in the circumferential direction. A pair of adjacent columnar portions 42 in the circumferential direction form a ball pocket between them. The ball pocket penetrates the retainer 40 radially and opens upward at the upper end surface of the retainer 40. The ball pockets are provided in a number corresponding to the number of rolling elements 30 and hold each rolling element 30 so that it can roll individually. As a result, the retainer 40 arranges the rolling elements 30 evenly spaced apart in the circumferential direction.

[0048] As shown in Figures 2 to 4, the sealing member 50 is formed in the shape of an annular plate. The sealing member 50 is arranged coaxially with the central axis O. The sealing member 50 is mounted on the outer ring 20. One sealing member 50 is arranged on each axial side of the plurality of rolling elements 30. The sealing member 50 comprises a base portion 51 that overlaps the end face 22a of the protruding portion 22 of the outer ring 20 from the axial outside, a stepped portion 52 extending axially outward from the inner peripheral edge of the base portion 51, a cover portion 53 that protrudes radially inward from the axially outward edge of the stepped portion 52, and a locking portion 54 extending radially outward and axially outward from the outer peripheral edge of the base portion 51. In a plan view, the sealing member 50 extends radially so as to straddle at least the center of the rolling elements 30. In this embodiment, the cover portion 53 overlaps the center of the rolling elements 30 in a plan view. However, the stepped portion 52 may extend from the inner circumferential edge of the base portion 51 outward in the axial direction and inward in the radial direction, and may overlap with the center of the rolling element 30 in a plan view. The inner circumferential edge of the cover portion 53 is positioned with a gap on the outer circumferential surface of the inner ring 10. The outer circumferential edge of the locking portion 54 is locked to the inner circumferential surface 21a of the outer ring body 21 from the inside in the axial direction. As a result, the sealing member 50 is fixed to the outer ring 20.

[0049] As shown in Figure 3, the first bearing 1 is equipped with grease 60. The grease 60 contains a base oil and a thickener. As the thickener, a urea compound is preferable due to its excellent heat resistance. The grease 60 is disposed between the rolling elements 30 and the sealing member 50. The grease 60 is disposed only on one side in the axial direction relative to the rolling elements 30 in the annular space between the inner ring 10 and the outer ring 20. In this embodiment, the grease 60 is disposed on the side opposite to the annular portion 41 of the cage 40, with the rolling elements 30 in the axial direction. In other words, the grease 60 is disposed above the rolling elements 30. The grease 60 has an annular contact portion 61 that is arranged circumferentially and contacts the outer ring 20, which is provided as a fixed ring, over its entire circumference. The annular contact portion 61 extends in a circular shape. The annular contact portion 61 is positioned so as to be attached to the inner circumferential surface of the outer ring 20, avoiding the outer ring raceway surface 23, and not in contact with the outer circumferential surface of the inner ring 10. Although the annular contact portion 61 is positioned so as not to contact the cover portion 53 of the sealing member 50, it may be positioned in contact with the cover portion 53.

[0050] Figure 5 is a plan view of the second rolling bearing of the first embodiment. Note that the seal member 50 is not shown in Figure 5. As shown in Figures 4 and 5, the second bearing 2 is equipped with grease 70. The grease 70 is made of the same material and has the same properties as the grease 60 of the first bearing 1. The amount of grease 70 is less than or equal to the amount of grease 60 of the first bearing 1. The grease 70 is located between the rolling elements 30 and the sealing member 50. The grease 70 is located only on one side in the axial direction relative to the rolling elements 30 in the annular space between the inner ring 10 and the outer ring 20. In this embodiment, the grease 70 is located on the side opposite to the annular portion 41 of the cage 40, with the rolling elements 30 in the axial direction. That is, the grease 70 is located above the rolling elements 30. In plan view, the grease 70 is arranged in an annular shape and is coaxial with the central axis O. The grease 70 is in contact with the outer ring 20, which is provided as a stationary ring, and is spaced apart from the inner ring 10, which is provided as a rotating ring. Furthermore, the grease 70 is spaced apart from the rolling elements 30 and the retainer 40. However, the grease 70 may be in contact with at least one of the rolling elements 30 and the retainer 40.

[0051] The grease 70 comprises a first annular portion 71 that contacts the outer ring 20, and a second annular portion 72 that is connected to the first annular portion 71 and contacts the sealing member 50. The first annular portion 71 and the second annular portion 72 are formed by applying the grease 70 in two separate applications. The first annular portion 71 extends circumferentially around the central axis O. The first annular portion 71 contacts the inner circumferential surface of the projection 22 of the outer ring 20 at a location axially outside the outer ring raceway surface 23. The second annular portion 72 extends circumferentially around the central axis O. The second annular portion 72 is spaced apart from the outer ring 20 with which the first annular portion 71 contacts. The second annular portion 72 is positioned radially opposite to the outer ring 20 (i.e., radially inward) relative to the first annular portion 71. Specifically, in a plan view, the outer periphery of the second annular portion 72 is located radially inward from the outer periphery of the first annular portion 71, and the inner periphery of the second annular portion 72 is located radially inward from the inner periphery of the first annular portion 71. The second annular portion 72 is connected to and integrated with the first annular portion 71 on its outer axial side. The second annular portion 72 extends around the entire circumference of the first annular portion 71. The second annular portion 72 is supported by the sealing member 50 by contacting the surface of the sealing member 50 that faces inward in the axial direction. In this embodiment, the second annular portion 72 is in contact with the inner surface of the cover portion 53 of the sealing member 50.

[0052] Each of the first annular portion 71 and the second annular portion 72 is formed by applying grease 70 discharged from a nozzle in a circular pattern of 360° or more. Each of the first annular portion 71 and the second annular portion 72 extends continuously around the entire circumference so as not to form any gaps in a plan view. The first annular portion 71 extends from one circumferential end 71a to the other circumferential end 71b, with a range of 360° or more and less than 720° around the central axis O. The second annular portion 72 extends from one circumferential end 72a to the other circumferential end 72b, with a range of 360° or more and less than 720° around the central axis O.

[0053] The operation of the fan motor 100 equipped with the second bearing 2 of this embodiment will now be described. The grease 60 of the first bearing 1 adheres to the outer ring 20 without adhering to the sealing member 50, so it may gradually break down due to its own weight immediately after application. In this case, the grease 60 in the first bearing 1 comes into contact with the rolling elements 30 and the cage 40, making it easier to supply the grease 60 to the rolling elements 30 and the outer ring raceway surface 23 of the outer ring 20. Therefore, in exchange for an increase in the rotational resistance of the first bearing 1 due to the contact of the grease 60, the durability of the first bearing 1 can be further improved.

[0054] In contrast, when applying the desired amount of grease 70 to the second bearing 2 (for example, the same amount as the grease 60 to the first bearing 1), the volume of the first annular portion 71 can be reduced compared to the case where the grease is applied so that a single annular portion is formed, because the first annular portion 71 and the second annular portion 72 are formed. Therefore, by forming the first annular portion 71 before the second annular portion 72 when applying the grease, it is possible to prevent the first annular portion 71 from collapsing due to its own weight. Furthermore, by providing the second annular portion 72, the second annular portion 72 is supported by the seal member 50, and the first annular portion 71 is supported not only by the outer ring 20 but also by the seal member 50 via the second annular portion 72. Therefore, the grease 70 of the second bearing 2 as a whole is less likely to collapse from its shape immediately after application due to its own weight. Thus, it is possible to suppress the grease 70 of the second bearing 2 from contacting the rolling elements 30 and the cage 40 more than necessary. Consequently, the rotational resistance of the second bearing 2 can be reduced.

[0055] As described above, in this embodiment, by differentiating the forms of the greases 60 and 70 applied to the first bearing 1 and the second bearing 2, the greases 60 and 70 are arranged so that the rotational resistance of the second bearing 2 is smaller than that of the first bearing 1. Here, since the first bearing 1 is positioned closer to the center of gravity of the rotating body 110 than the second bearing 2, the centrifugal force generated by the slight eccentricity of the rotating body 110 places a greater load on the first bearing 1 than on the second bearing 2. According to this embodiment, since the rotational resistance of the second bearing 2 is smaller than that of the first bearing 1, if the durability of the first bearing 1 is improved to be greater than that of the second bearing 2 in exchange for an increase in the rotational resistance of the first bearing 1, the increase in the rotational resistance of the first bearing 1 can be offset. Therefore, it is possible to ensure the durability of the fan motor 100 and reduce power consumption at the same time.

[0056] [Modified version of the first embodiment] The arrangement of the grease in the first bearing 1 is not limited to the above configuration. The grease in the first bearing 1 should be arranged in a different configuration from the grease 70 in the second bearing 2, such that the rotational resistance of the second bearing 2 is less than the rotational resistance of the first bearing 1.

[0057] For example, the grease in the first bearing 1 may have an annular contact portion having granular particles arranged in a dot-like manner around its entire circumference, instead of an annular contact portion 61 extending in a circular direction. Alternatively, the grease in the first bearing 1 may have a rolling element contact portion arranged along the circumferential direction and in contact with the rolling element 30, instead of an annular contact portion 61. The rolling element contact portion may not be in contact with the inner ring 10 and the outer ring 20, or it may be located on at least one of the inner ring 10 and the outer ring 20. This makes it easier to supply grease to the rolling element 30 and the outer ring raceway surface 23 of the outer ring 20 in the first bearing 1. Therefore, the durability of the first bearing 1 can be improved at the expense of increased rotational resistance of the first bearing 1.

[0058] Furthermore, the grease of the first bearing 1 may have a cage coating portion located on the lower end surface of the cage 40, in addition to the annular contact portion 61 or the rolling element contact portion. This allows for an increase in the amount of grease in the first bearing 1, thereby improving the durability of the first bearing 1. Additionally, since the amount of grease 70 in the second bearing 2 is relatively reduced compared to the amount of grease in the first bearing 1, the rotational resistance of the second bearing 2 can be made even smaller than that of the first bearing 1.

[0059] Furthermore, the distance between the grease 70 and the rolling elements 30 in the second bearing 2 may be wider than the distance between the grease 60 and the rolling elements 30 in the first bearing 1. In this case, the grease 60 and the rolling elements 30 may be in contact with each other in the first bearing 1. This makes it easier to supply the grease 60 to the rolling elements 30 and the outer ring raceway surface 23 of the outer ring 20 in the first bearing 1. Therefore, the durability of the first bearing 1 can be improved at the expense of increased rotational resistance of the first bearing 1.

[0060] [Second Embodiment] The second bearing 2 of the second embodiment is equipped with grease 70A instead of grease 70 of the first embodiment. Other than what is described below, the configuration is the same as in the first embodiment.

[0061] Figure 6 is a longitudinal cross-sectional view of the second rolling bearing of the second embodiment. Figure 7 is a plan view of the second rolling bearing of the second embodiment. Note that the seal member 50 is not shown in Figure 7. As shown in Figures 6 and 7, the grease 70A is integrally formed and comprises a raceway contact portion 73 that contacts the outer ring 20 and a seal member contact portion 74 that is connected to the raceway contact portion 73 and contacts the seal member 50. The raceway contact portion 73 is arranged circumferentially at predetermined positions in the radial and axial directions. The raceway contact portion 73 contacts the inner circumferential surface of the projection 22 of the outer ring 20 at a location axially outward from the outer ring raceway surface 23. The seal member contact portion 74 is arranged circumferentially at predetermined positions different from the raceway contact portion 73 in the radial and axial directions. The seal member contact portion 74 is spaced apart from the outer ring 20 that the raceway contact portion 73 contacts. The seal member contact portion 74 is located radially opposite to the outer ring 20 (i.e., radially inward) relative to the raceway contact portion 73. The seal member contact portion 74 is directly connected to and integrated with the raceway contact portion 73 on the axially outward side. The seal member contact portion 74 extends around the entire circumference of the raceway contact portion 73. The seal member contact portion 74 is supported by the seal member 50 by contacting the surface of the seal member 50 that faces inward in the axial direction. The seal member contact portion 74 is in contact with the inner surface of the cover portion 53 of the seal member 50.

[0062] The raceway contact area 73 has first granules 75 arranged in a point-like manner around its entire circumference. The first granules 75 are formed to be the same shape as each other. The first granules 75 have a shape in which a part of a spherical, ellipsoidal, or teardrop-shaped grease comes into contact with the surrounding member and is crushed. As a result, the exposed portion of the outer surface of the first granules 75 is formed in a convex curved shape. The first granules 75 are aligned in the circumferential direction. A pair of adjacent first granules 75 in the circumferential direction are in contact with each other and are integrated. In the illustrated example, adjacent pairs of first granules 75 are in point contact with each other, but they may also be in contact with each other and crushed. However, a pair of adjacent first granules 75 in the circumferential direction may be spaced apart from each other. Each first granule 75 is in contact with the outer ring 20. The contact areas between the first granules 75 and the outer ring 20 are spaced apart in the circumferential direction.

[0063] The seal member contact portion 74 has second granules 76 arranged in a point-like manner around its entire circumference. The same number of second granules 76 as the first granules 75 are provided. The second granules 76 are formed to be the same shape as each other. The second granules 76 have a shape in which a part of the spherical, ellipsoidal, or teardrop-shaped grease is crushed upon contact with the surrounding member. As a result, the exposed portion of the outer surface of the second granules 76 is formed in a convex curved shape. Each second granule 76 is aligned in the circumferential direction. Each second granule 76 is positioned offset in the circumferential direction from the first granules 75. Specifically, each second granule 76 is positioned such that, when viewed from the axial direction, a straight line passing between the center of the second granule 76 and the central axis O passes through the midpoint between the centers of each of the adjacent pair of first granules 75. Each second granule 76 is in contact with and integrated with the raceway ring contact portion 73. Each second granule 76 is in contact with the pair of first granules 75. Each second granule 76 is in contact with the sealing member 50. A pair of adjacent second granules 76 in the circumferential direction are in contact with each other and are integrated. However, a pair of adjacent second granules 76 in the circumferential direction may be spaced apart from each other. The second granules 76 are formed to be larger in the radial direction than the first granules 75. As a result, the volume of the second granules 76 is greater than the volume of the first granules 75.

[0064] The operation of the fan motor 100 equipped with the second bearing 2 of this embodiment will now be described. When applying the desired amount of grease 70A to the second bearing 2 (for example, the same amount as the grease 60 in the first bearing 1), the volume of the raceway contact portion 73 can be reduced compared to applying grease only around the circumference. This is because the raceway contact portion 73 and the seal member contact portion 74 are formed in this way. Therefore, by forming the raceway contact portion 73 before the seal member contact portion 74 when applying the grease, it is possible to prevent the raceway contact portion 73 from collapsing due to its own weight. Furthermore, by providing the seal member contact portion 74, the seal member contact portion 74 is supported by the seal member 50, and the raceway contact portion 73 is supported not only by the outer ring 20 but also by the seal member 50 via the seal member contact portion 74. As a result, the grease 70A as a whole is less likely to collapse from its shape immediately after application due to its own weight. Thus, it is possible to suppress the grease 70A from contacting the rolling elements 30 and the cage 40 more than necessary. Consequently, the rotational resistance of the second bearing 2 can be reduced. As described above, this embodiment can achieve the same effects and advantages as the first embodiment.

[0065] [Modified version of the second embodiment] In the second embodiment, the arrangement of the grease in the first bearing 1 can be appropriately changed in the same manner as the modified example in the first embodiment. That is, the grease in the first bearing 1 may have an annular contact portion having granular particles arranged in a point-like manner around its entire circumference instead of the annular contact portion 61 that extends circumferentially. Alternatively, the grease in the first bearing 1 may have a rolling element contact portion instead of the annular contact portion 61, or it may have a cage coating portion in addition to the annular contact portion 61 or the rolling element contact portion. Furthermore, the distance between the grease 70A and the rolling element 30 in the second bearing 2 may be wider than the distance between the grease 60 and the rolling element 30 in the first bearing 1.

[0066] Furthermore, the grease 70A of the second bearing 2 has a raceway contact portion 73 and a seal member contact portion 74 having granular material, but one of the raceway contact portion and the seal member contact portion may extend in a circumferential manner.

[0067] [Third Embodiment] In the third embodiment, the second bearing 2 is equipped with grease 70B instead of grease 70 in the first embodiment. Other than what is described below, the configuration is the same as in the first embodiment.

[0068] Figure 8 is a longitudinal cross-sectional view of the second rolling bearing of the third embodiment. As shown in Figure 8, the grease 70B is located on the annular portion 41 side of the retainer 40 relative to the rolling element 30. That is, the grease 70B is located below the rolling element 30. The grease 70B is located only on the lower end surface 40l of the retainer 40. The grease 70B is spaced apart in the circumferential direction. The grease 70B is evenly distributed in the circumferential direction. However, the grease 70B may be applied in an arc shape. The grease 70B is spaced apart from the inner ring 10, the outer ring 20, and the sealing member 50. Furthermore, the grease 70B is spaced apart from the rolling element 30.

[0069] The operation of the fan motor 100 equipped with the second bearing 2 of this embodiment will now be described. The grease 70B in the second bearing 2 can suppress direct contact of the grease 70B with the rolling elements 30, the inner ring 10, and the outer ring 20. Therefore, the rotational resistance of the second bearing 2 can be reduced. As described above, this embodiment can achieve the same effects and advantages as the first embodiment.

[0070] [Modified version of the third embodiment] In the third embodiment, the arrangement of the grease in the first bearing 1 can be appropriately changed in the same manner as the modified example in the first embodiment. That is, the grease in the first bearing 1 may have an annular contact portion 61 having granular particles arranged in a point-like manner around its entire circumference, instead of an annular contact portion 61 extending in a circular direction. Alternatively, the grease in the first bearing 1 may have a rolling element contact portion instead of the annular contact portion 61, or it may have a cage coating portion in addition to the annular contact portion 61 or the rolling element contact portion. Furthermore, the distance between the grease 70B and the rolling element 30 in the second bearing 2 may be wider than the distance between the grease 60 and the rolling element 30 in the first bearing 1.

[0071] [Fourth Embodiment] In the first to third embodiments described above, the morphology of the first bearing 1 and the second bearing 2 after grease application differs. In contrast, in the fourth embodiment, the morphology of the first bearing 1 and the second bearing 2 after grease application is similar to that of the first bearing 1 and the second bearing 2, but the amount of grease differs. That is, the grease in both the first bearing 1 and the second bearing 2 is arranged in the same manner as one of the grease morphologies in the above embodiments and their modified examples, but the amount of grease in the first bearing 1 and the second bearing 2 differs.

[0072] In this case, it is desirable that the amount of grease in the second bearing 2 is less than the amount of grease in the first bearing 1. With this configuration, it becomes easier to supply grease to the rolling elements 30 and the outer ring raceway surface 23 of the outer ring 20 in the first bearing 1. Therefore, in exchange for an increase in the rotational resistance of the first bearing 1 due to grease contact, the durability of the first bearing 1 can be improved. Furthermore, the rotational resistance of the second bearing 2 can be made smaller than the rotational resistance of the first bearing 1. Therefore, the increase in the rotational resistance of the first bearing 1 can be offset. Thus, it is possible to ensure the durability of the fan motor 100 and reduce power consumption at the same time.

[0073] [Fifth Embodiment] In the first to third embodiments described above, the morphology of the grease applied to the first bearing 1 and the second bearing 2 differs. In contrast, in the fifth embodiment, the morphology of the grease applied to the first bearing 1 and the second bearing 2 is similar to that of the first bearing 1 and the second bearing 2, but the base oil viscosity differs. That is, the grease for both the first bearing 1 and the second bearing 2 is arranged in the same manner as any one of the greases in the above embodiments and their modified forms, but the base oil viscosity of the grease for the first bearing 1 and the second bearing 2 is different.

[0074] In this case, the base oil viscosity of the grease in the second bearing 2 is lower than that of the grease in the first bearing 1. This configuration improves the heat resistance of the grease in the first bearing 1 and allows for the formation of a thick grease film between the rolling elements 30 and the outer ring 20 in the first bearing 1. Therefore, the durability of the first bearing 1 can be improved at the expense of increased rotational resistance. Furthermore, the rotational resistance of the second bearing 2 can be made smaller than that of the first bearing 1. This offsets the increase in rotational resistance of the first bearing 1. Thus, it is possible to ensure the durability of the fan motor 100 and reduce power consumption at the same time.

[0075] [Sixth Embodiment] In the first to third embodiments described above, the morphology of the grease applied to the first bearing 1 and the second bearing 2 differs. In contrast, in the sixth embodiment, the morphology of the grease applied to the first bearing 1 and the second bearing 2 is similar to that of the first bearing 1 and the second bearing 2, but the consistency of the grease is different. That is, the grease for both the first bearing 1 and the second bearing 2 is arranged in the same manner as any one of the greases in the above embodiments and their modified forms, but the consistency of the grease for the first bearing 1 and the second bearing 2 is different.

[0076] In this case, the consistency of the grease in the second bearing 2 is lower than that of the grease in the first bearing 1. Generally, the higher the consistency of the grease, the more likely churning is to occur. Also, the lower the consistency of the grease, the more likely channeling is to occur. According to this embodiment, grease churning is more likely to occur in the first bearing 1 than in the second bearing 2. This improves the durability of the first bearing 1 at the expense of an increase in its rotational resistance. Furthermore, grease channeling is more likely to occur in the second bearing 2 than in the first bearing 1. This makes the rotational resistance of the second bearing 2 lower than that of the first bearing 1. Therefore, the increase in the rotational resistance of the first bearing 1 can be offset. Thus, it is possible to ensure the durability of the fan motor 100 and reduce power consumption at the same time.

[0077] [Seventh Embodiment] In the first to third embodiments described above, the morphology of the grease applied to the first bearing 1 and the second bearing 2 differs. In contrast, in the seventh embodiment, the morphology of the grease applied to the first bearing 1 and the second bearing 2 is similar to that of the first bearing 1 and the second bearing 2, but the composition of the thickener differs from that of the first bearing 1 and the second bearing 2. That is, the grease for both the first bearing 1 and the second bearing 2 is arranged in the same manner as any one of the greases in the above embodiments and their modified forms, but the composition of the thickener in the grease for the first bearing 1 and the second bearing 2 differs.

[0078] In this case, the aliphatic urea content in the thickener of the grease for the second bearing 2 is greater than the aliphatic urea content in the thickener of the grease for the first bearing 1. Consequently, the alicyclic urea content in the thickener of the grease for the first bearing 1 may be greater than the alicyclic urea content in the thickener of the grease for the second bearing 2. Furthermore, the greases for the first bearing 1 and the second bearing 2 may contain aromatic urea instead of some or all of the alicyclic urea. The aliphatic urea content in the thickener of the grease for the first bearing 1 may be 0%. Furthermore, the alicyclic urea content in the thickener of the grease for the first bearing 1 may be 100%. Also, the alicyclic urea content in the thickener of the grease for the second bearing 2 may be 0%.

[0079] Generally, aliphatic ureas have excellent affinity for base oils, and a small amount can convert the base oil into a semi-solid grease. Therefore, by using aliphatic ureas as a thickener, a grease of a desired consistency can be obtained with a smaller amount of thickener compared to when using alicyclic ureas or aromatic ureas. On the other hand, by using alicyclic ureas and aromatic ureas, a grease with higher heat resistance can be obtained compared to when using aliphatic ureas.

[0080] According to this embodiment, the amount of thickener contained in the grease of the second bearing 2 can be reduced compared to the amount of thickener contained in the grease of the first bearing 1. This makes the rotational resistance of the second bearing 2 lower than that of the first bearing 1. Therefore, an increase in the rotational resistance of the first bearing 1 can be tolerated. Furthermore, by making the content of alicyclic urea and aromatic urea in the thickener of the grease of the first bearing 1 higher than the content of alicyclic urea and aromatic urea in the thickener of the grease of the second bearing 2, the heat resistance of the grease of the first bearing 1 can be improved at the expense of an increase in the rotational resistance of the first bearing 1. Therefore, the durability of the first bearing 1 can be improved. Consequently, it is possible to ensure the durability of the fan motor 100 and reduce power consumption at the same time.

[0081] Furthermore, when aromatic ureas are used as a thickening agent, a larger amount of thickening agent is required to obtain grease of a predetermined consistency compared to when alicyclic ureas are used as a thickening agent. For this reason, in the grease of this embodiment, alicyclic ureas are preferred as thickening agents other than aliphatic ureas.

[0082] [Eighth Embodiment] In the first to third embodiments described above, the morphology of the grease applied to the first bearing 1 and the second bearing 2 differs. In contrast, in the eighth embodiment, the morphology of the grease applied to the first bearing 1 and the second bearing 2 is similar to that of the first bearing 1, but the spacing between the grease and the rolling elements 30 in the first bearing 1 and the spacing between the grease and the rolling elements 30 in the second bearing 2 differ. That is, the grease in both the first bearing 1 and the second bearing 2 is arranged in the same manner as one of the grease morphologies in the above embodiments and their modified examples, but the spacing between the grease and the rolling elements 30 in the first bearing 1 and the spacing between the grease and the rolling elements 30 in the second bearing 2 are different.

[0083] In this case, the distance between the grease and the rolling elements 30 in the second bearing 2 is wider than the distance between the grease and the rolling elements 30 in the first bearing 1. With this configuration, it is easier to supply grease to the rolling elements 30 and the outer ring raceway surface 23 of the outer ring 20 in the first bearing 1 compared to the second bearing 2. Therefore, the durability of the first bearing 1 can be improved in exchange for an increase in the rotational resistance of the first bearing 1 due to grease contact. Furthermore, the rotational resistance of the second bearing 2 can be made smaller than the rotational resistance of the first bearing 1. Therefore, the increase in the rotational resistance of the first bearing 1 can be offset. Thus, it is possible to ensure the durability of the fan motor 100 and reduce power consumption at the same time.

[0084] [Other embodiments] In the first to third embodiments described above, the amount of grease in the second bearing 2 is set to be less than or equal to the amount of grease in the first bearing 1. However, as in the fourth embodiment, it is desirable that the amount of grease in the second bearing 2 be less than the amount of grease in the first bearing 1. This configuration can achieve the same effects as in the fourth embodiment. It is also possible that the amount of grease in the second bearing 2 be greater than the amount of grease in the first bearing 1. In this case, the rotational resistance of the second bearing 2 can be made smaller than that of the first bearing 1 by differentiating the grease application characteristics of the first bearing 1 and the second bearing 2, as in the first to third embodiments described above.

[0085] Furthermore, the grease of the second bearing may be arranged in a shape similar to the annular contact portion of the grease of the first bearing 1 in the first embodiment and its modified form. In this case, it is desirable that the grease of the first bearing has the rolling element contact portion of the grease of the first bearing 1 in the modified form of the first embodiment. This makes it easier to supply grease to the rolling elements and outer ring in the first bearing, and makes the rotational resistance of the second bearing smaller than that of the first bearing.

[0086] Furthermore, in the first to third embodiments described above, the greases for the first bearing 1 and the second bearing 2 have the same properties, but the configuration is not limited to this. Similar to the fifth embodiment, the base oil viscosity of the grease for the second bearing 2 may be lower than that of the grease for the first bearing 1. This configuration can produce the same effects as in the fifth embodiment. Also, similar to the sixth embodiment, the consistency of the grease for the second bearing 2 may be lower than that of the grease for the first bearing 1. This configuration can produce the same effects as in the sixth embodiment. Also, similar to the seventh embodiment, the aliphatic urea content in the thickener of the grease for the second bearing 2 may be higher than the aliphatic urea content in the thickener of the grease for the first bearing 1. This configuration can produce the same effects as in the seventh embodiment.

[0087] Furthermore, by combining multiple embodiments from the fifth to seventh embodiments, the characteristics of the grease for the first bearing 1 and the grease for the second bearing 2 may be made different. This makes it possible to obtain the above-mentioned effects more effectively.

[0088] It should be noted that the present invention is not limited to the embodiments described above with reference to the drawings, and various modifications are conceivable 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 stationary ring. The grease is in contact with the stationary outer ring 20. However, the raceway ring that the grease contacts does not have to be a stationary ring. That is, the inner ring may be provided as a stationary ring, the outer ring as a rotating ring, and the grease may be in contact with the stationary inner ring. Alternatively, the inner ring may be provided as a stationary ring, the outer ring as a rotating ring, and the grease may be in contact with the rotating outer ring.

[0089] Furthermore, although a fan motor was used as an example of a rotating device in the above embodiment, the rotating device is not limited to this. For example, the present invention may be applied to dental handpieces, spindle motors of hard disk drives, and the like as rotating devices.

[0090] Furthermore, without departing from the spirit of the present invention, it is possible to replace the components in the above-described embodiments with well-known components as appropriate. For example, the fourth to eighth embodiments may be combined. [Explanation of Symbols]

[0091] 1…First rolling bearing 2…Second rolling bearing 10…Inner ring 20…Outer ring 30…Rolling element 40…Cage 50…Seal member 60,70,70A,70B…Grease 61…Annular contact part 71…First annular part 72…Second annular part 73…Raceway ring contact part 74…Seal member contact part 100…Fan motor (rotating equipment) 110…Rotating body 111…Shaft part 120…Base part

Claims

1. A rotating body having a shaft, The base that supports the rotating body, Mounted on the base and rotatably supporting the shaft, the first rolling bearing and the second rolling bearing are arranged in the axial direction of the rotating body, Equipped with, The first rolling bearing is positioned closer to the center of gravity of the rotating body than the second rolling bearing. Each of the first rolling bearing and the second rolling bearing is, The inner and outer rings are arranged coaxially with each other, A rolling element disposed between the inner ring and the outer ring, Grease disposed between the inner ring and the outer ring, It has, The grease is arranged such that the rotational resistance of the second rolling bearing is less than the rotational resistance of the first rolling bearing. Rotating machinery.

2. The second rolling bearing has a sealing member that covers the grease from the side opposite to the rolling elements. The grease of the second rolling bearing is A first annular portion extends circumferentially around the common axis of the inner ring and the outer ring, and contacts one of the inner ring and the outer ring, A second annular portion extends circumferentially around the common axis, is connected to the first annular portion on the outer side in the axial direction, and is in contact with the sealing member, The rotating device according to claim 1, comprising:

3. The second rolling bearing has a sealing member that covers the grease from the side opposite to the rolling elements. The grease of the second rolling bearing is A raceway contact portion is arranged along the circumferential direction centered on the common axis of the inner ring and the outer ring, and contacts one of the inner ring and the outer ring. A seal member contact portion is arranged along the circumferential direction, is connected to the raceway contact portion on the outer side in the axial direction, and contacts the seal member, It has, At least one of the raceway contact portion and the seal member contact portion has granular material arranged in a point-like manner around its entire circumference. The rotating apparatus according to claim 1.

4. The second rolling bearing is positioned between the inner ring and the outer ring and has an annular cage that holds the rolling elements in a rotatable manner. The retainer has ball pockets that penetrate radially and open in the first axial direction, and each of the rolling elements is individually held so as to be able to roll. The grease of the second rolling bearing is provided only on the end face of the cage facing the second axial direction. The rotating apparatus according to claim 1.

5. The grease of the first rolling bearing has rolling element contact portions arranged along the circumferential direction centered on the common axis of the inner ring and the outer ring, and in contact with the rolling elements over their entire circumference. The rotating apparatus according to claim 1.

6. The grease of the first rolling bearing is arranged along the circumferential direction centered on the common axis of the inner ring and the outer ring, and has an annular contact portion that contacts the fixed ring of the inner ring and the outer ring over its entire circumference. The rotating apparatus according to claim 1.

7. The first rolling bearing has an annular cage positioned between the inner ring and the outer ring, which holds the rolling elements so that they can roll. The grease of the first rolling bearing has a cage coating portion located on the end face of the cage facing the second axial direction. The rotating apparatus according to claim 5.

8. The first rolling bearing has an annular cage positioned between the inner ring and the outer ring, which holds the rolling elements in a rotatable manner. The grease of the first rolling bearing has a cage coating portion located on the end face of the cage facing the second axial direction. The rotating apparatus according to claim 6.

9. The amount of grease in the second rolling bearing is less than the amount of grease in the first rolling bearing. The rotating apparatus according to any one of claims 1 to 8.

10. The viscosity of the base oil of the grease in the second rolling bearing is lower than the viscosity of the base oil of the grease in the first rolling bearing. The rotating apparatus according to any one of claims 1 to 8.

11. The consistency of the grease in the second rolling bearing is less than that of the grease in the first rolling bearing. The rotating apparatus according to any one of claims 1 to 8.

12. The grease of the first rolling bearing and the thickener of the grease of the second rolling bearing are urea compounds. The aliphatic urea content in the thickener of the grease for the second rolling bearing is greater than the aliphatic urea content in the thickener of the grease for the first rolling bearing. The rotating apparatus according to any one of claims 1 to 8.

13. The distance between the grease and the rolling element in the second rolling bearing is wider than the distance between the grease and the rolling element in the first rolling bearing. The rotating apparatus according to any one of claims 1 to 8.

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