Sleeves, sleeves with bearings, and rotating equipment

Abstract

To provide a sleeve that can suppress galvanic corrosion in rolling bearings. [Solution] The sleeve 140 is a cylindrical sleeve in which the bearing 1 is mounted on the inside, and comprises retaining portions 141, 142 that hold the outer circumferential surface of the bearing 1, and outer ring receiving portions 143, 144 that contact the end face of the outer ring 20 of the bearing 1 from the axial inner side. The retaining portions 141, 142 have recesses 141a, 142a that open radially inward toward the outer circumferential surface of the bearing 1. At least a portion of the sleeve 140 is formed of an electrically insulating synthetic resin.

Description

Technical Field

[0003]

[0001] The present invention relates to a sleeve, a sleeve with a bearing, and a rotating device.

Background Art

[0002] A rotating device may be provided with a cylindrical sleeve that rotatably supports a shaft inside. The sleeve holds a rolling bearing inside. There is a known structure provided for preventing electric erosion as a rolling bearing (see, for example, Patent Document 1 and Patent Document 2). Specifically, there are techniques for electrically insulating between the outer ring and the inner ring by making the rolling elements made of ceramics which is an insulator, and techniques for electrically insulating between the sleeve and the outer ring by covering the outer peripheral surface of the outer ring with an insulating film.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

[0006] Thus, the conventional rolling bearings described above may have various problems in their structure for suppressing galvanic corrosion. Therefore, the development of a structure that suppresses galvanic corrosion in the rolling bearing on the sleeve side is desirable.

[0007] Therefore, the present invention provides a sleeve that can suppress the occurrence of electrolytic corrosion in rolling bearings, as well as a bearing-equipped sleeve and rotating equipment equipped with the sleeve. [Means for solving the problem]

[0008] A sleeve according to a first aspect of the present invention is a cylindrical sleeve in which a rolling bearing is mounted on the inside, comprising a retaining portion that holds the outer circumferential surface of the rolling bearing, and an outer ring receiving portion that contacts the end face of the outer ring of the rolling bearing from the inside in the axial direction, wherein the retaining portion has a recess that opens radially inward toward the outer circumferential surface, and at least a portion of it is formed of an electrically insulating synthetic resin.

[0009] According to the first embodiment, it is possible to suppress the flow of current into the rolling bearing through the sleeve. This makes it possible to suppress electrolytic corrosion in the rolling bearing. Here, in order to suppress the slippage of the outer ring of the rolling bearing relative to the sleeve, it is necessary to fix the outer ring to the sleeve. Either press-fitting or bonding can be used as methods for fixing the outer ring to the sleeve. In a configuration where the outer ring is fixed to the sleeve by press-fitting, distortion of the synthetic resin sleeve may propagate to the outer ring. If the distortion of the sleeve propagates to the outer ring, the contact point with the rolling elements on the raceway surface of the outer ring may change, potentially causing malfunction of the rolling bearing. According to the first embodiment, since the retaining portion that holds the outer circumferential surface of the rolling bearing is provided with a recess that opens toward the outer circumferential surface of the rolling bearing, the propagation of distortion of the sleeve to the outer ring via the contact portion between the sleeve and the outer ring can be suppressed. Therefore, it is possible to suppress changes in the contact point with the rolling elements on the raceway surface that cause malfunction of the rolling bearing. When the outer ring is fixed to the sleeve by adhesive, the recess can function as an adhesive reservoir. This prevents the adhesive from leaking through the space between the sleeve and the outer ring into the interior of the rolling bearing, thus preventing the adhesive from adhering to unintended locations and causing malfunctions in the rolling bearing. As a result, it is possible to form a synthetic resin sleeve on which a rolling bearing is mounted while suppressing the occurrence of various malfunctions.

[0010] A sleeve according to a second aspect of the present invention may have a parting line formed during the molding of the sleeve at a position on the inner circumferential surface opposite to the retaining portion relative to the outer ring receiving portion, in the sleeve according to the first aspect.

[0011] According to the second embodiment, it is possible to avoid the formation of a parting line at the contact point between the sleeve and the rolling bearing. This prevents the parting line from reducing the assembly accuracy of the rolling bearing, and also prevents an increase in manufacturing costs by eliminating the need for processing such as grinding off the parting line in order to assemble the rolling bearing into the sleeve.

[0012] A sleeve according to a third aspect of the present invention may have potassium titanate whiskers added to the synthetic resin in the sleeve according to the first or second aspect described above.

[0013] According to the third embodiment, the sleeve can be made into a material with excellent wear resistance and surface smoothness. Furthermore, the synthetic resin containing potassium titanate whiskers has good machinability and is less prone to clogging during grinding, thus offering excellent processability. For this reason, compared to cases where the sleeve contains glass fiber or carbon fiber as a reinforcing material, the processability when forming the sleeve by machining such as cutting and grinding, and the processability when finishing the injection-molded sleeve by secondary processing such as cutting and grinding can be improved.

[0014] A sleeve according to a fourth aspect of the present invention is a sleeve according to any of the first to third aspects described above, wherein the recess may extend continuously over the entire circumferential direction.

[0015] According to the fourth embodiment, the propagation of sleeve distortion to the outer ring can be more reliably suppressed. In addition, the recess can be made to function more reliably as an adhesive reservoir.

[0016] A fifth aspect of the present invention is a sleeve according to any of the first to fourth aspects described above, wherein the recess may have an inclined portion whose inner diameter decreases as it moves outward in the axial direction.

[0017] According to the fifth aspect, when injection molding the sleeve, it is easier to forcibly remove the portion of the mold that forms the recess. Therefore, the sleeve can be easily formed by injection molding.

[0018] A sleeve according to a sixth aspect of the present invention, in which the retaining portion has a press-fit portion whose inner diameter is smaller than the outer diameter of the rolling bearing, is a sleeve according to any of the first to fifth aspects described above.

[0019] According to the sixth embodiment, since the outer ring is fixed to the holding portion of the sleeve by press-fitting, a suitable configuration can be achieved that has the effect of suppressing the propagation of the sleeve's distortion to the outer ring.

[0020] The sleeve according to the seventh aspect of the present invention is the sleeve according to any one of the first to sixth aspects, wherein the recess may be axially spaced from the outer ring receiving portion.

[0021] According to the seventh aspect, compared with the configuration in which the recess is positioned without being axially spaced from the outer ring receiving portion, the distance of the path between the sleeve and the outer ring, which passes from the recess through the space between the end face of the outer ring and the outer ring receiving portion to the inside of the rolling bearing, can be increased. Thereby, in the configuration in which the outer ring is fixed to the sleeve by adhesion, it is possible to suppress the adhesive disposed in the recess from leaking into the rolling bearing through the space between the end face of the outer ring and the outer ring receiving portion. Therefore, it is possible to more reliably suppress the adhesive from adhering to an unintended location and causing a malfunction of the rolling bearing.

[0022] The sleeve according to the eighth aspect of the present invention is the sleeve according to any one of the first to seventh aspects, and the whole may be formed of the synthetic resin.

[0023] According to the eighth aspect, it is possible to more reliably suppress the current from flowing into the rolling bearing through the sleeve. Further, compared with the configuration in which only a part of the sleeve is formed of the synthetic resin, the sleeve can be easily formed, and the manufacturing cost of the sleeve can be reduced.

[0024] The sleeve according to the ninth aspect of the present invention is the sleeve according to any one of the first to eighth aspects, and may further include a protruding portion formed inside the outer ring receiving portion in the axial direction and protruding inside the outer ring receiving portion in the radial direction.

[0025] According to the ninth aspect, when the shaft inserted into the inner ring of the rolling bearing is inclined with respect to the central axis of the sleeve, it is possible to restrict the further inclination of the shaft by contact of the shaft with the protruding portion. Here, when the protruding portion is not provided on the sleeve, the portion of the inner peripheral surface of the sleeve that can contact the inclined shaft is provided at a position radially outside the inner peripheral edge of the outer bearing portion, so that the inclination of the shaft cannot be sufficiently restricted. According to the ninth aspect, since the protruding portion protrudes radially inward of the outer bearing portion, it is possible to effectively restrict the inclination of the shaft. Thereby, it is possible to suppress that the inner ring of the rolling bearing is greatly inclined with respect to the outer ring and indentations of the rolling elements are formed on at least one of the inner ring and the outer ring. Therefore, when assembling the rotating device having the sleeve, it is possible to suppress the formation of indentations on the raceway rings of the rolling bearing and to suppress the generation of abnormal noise during rotation of the rotating device.

[0026] The sleeve according to the tenth aspect of the present invention is the sleeve according to the ninth aspect, wherein the protruding portion may have a restricting portion that can contact the shaft inserted into the inner ring in a state where the inclination between the outer ring and the inner ring of the rolling bearing is less than the angular clearance.

[0027] According to the tenth aspect, it is possible to restrict the inclination of the shaft by the restricting portion to be greater than the angular clearance of the rolling bearing. Therefore, when assembling the rotating device having the sleeve, it is possible to more reliably suppress the formation of indentations on the raceway rings of the rolling bearing.

[0028] The sleeve according to the eleventh aspect of the present invention is the sleeve according to the ninth aspect or the tenth aspect, wherein the outer bearing portion may have an inner diameter larger than the outer diameter of the inner ring of the rolling bearing

[0029] According to the eleventh aspect, it is possible to avoid contact of the outer bearing portion with the inner ring of the rolling bearing. Therefore, it is possible to prevent the sleeve from interfering with the rotation of the shaft.

[0030] In the sleeve according to the twelfth aspect of the present invention, the inner diameter of the protrusion may be less than or equal to the outer diameter of the inner ring, as in the sleeve according to the eleventh aspect.

[0031] According to the twelfth embodiment, the protrusion can be brought closer to the central axis of the sleeve while avoiding contact between the sleeve and the inner ring of the rolling bearing. Therefore, the tilting of the shaft can be more effectively restricted.

[0032] A sleeve according to the 13th aspect of the present invention may have the outer ring receiving portion and the protruding portion integrally in a sleeve according to any of the 9th to 12th aspects described above.

[0033] According to the 13th embodiment, it is possible to form a sleeve from a single component. Therefore, the manufacturing cost of the sleeve can be reduced.

[0034] A sleeve according to a 14th aspect of the present invention may include, in a sleeve according to any of the 9th to 13th aspects described above, a sleeve body having the protrusion, and a receiving member disposed inside the sleeve body and overlapping the protrusion from the other side in the axial direction to form the outer ring receiving portion.

[0035] According to the 14th embodiment, the sleeve body can be made into a relatively simple shape with few steps, resulting in a sleeve with excellent productivity. In particular, when the sleeve body is made of metal, complex processing can be avoided when forming the sleeve body, making it a suitable configuration that achieves the above effects.

[0036] A sleeve according to a 15th aspect of the present invention, in the sleeve according to the 10th aspect and each of the aspects relating thereto, holds another rolling bearing at a position opposite to the rolling bearing with respect to the protrusion, the tip of the shaft has a tapered surface that tapers towards the end, and the protrusion may be able to contact the shaft with the tapered surface in contact with the opening edge of the inner ring of the other rolling bearing.

[0037] According to the 15th embodiment, when inserting a shaft from the rolling bearing side into another rolling bearing, even if the shaft is misaligned, such as by being tilted with respect to the central axis of the sleeve, the tapered surface can still be brought into contact with the opening edge of the inner ring of the other rolling bearing. This prevents the tip surface of the shaft from abutting against the inner ring of the other rolling bearing and applying excessive force to the inner ring. Therefore, it is possible to suppress the formation of indentations on the raceway of the other rolling bearing and reduce the generation of abnormal noise when the rotating equipment is in operation.

[0038] A bearing-equipped sleeve according to the sixteenth aspect of the present invention comprises a sleeve according to any of the first to fifteenth aspects described above, and the rolling bearing mounted inside the sleeve.

[0039] According to the 16th embodiment, a bearing-equipped sleeve can be provided that suppresses electrolytic corrosion in the rolling bearing.

[0040] A bearing-equipped sleeve according to the 17th aspect of the present invention is a bearing-equipped sleeve according to the 16th aspect, wherein the rolling bearing is bonded to the sleeve and adhesive is placed in the recess.

[0041] According to the 17th embodiment, the recess functions as an adhesive reservoir. This prevents the adhesive from leaking into the rolling bearing through the space between the sleeve and the outer ring, and prevents the adhesive from adhering to unintended locations, which can cause malfunctions in the rolling bearing.

[0042] A rotating device according to the 18th aspect of the present invention comprises a bearing-equipped sleeve according to the 16th or 17th aspect, and a shaft inserted through the inner ring of the rolling bearing.

[0043] According to the 18th embodiment, the increase in rotational resistance of rolling bearings due to electrolytic corrosion can be suppressed. Therefore, the lifespan of rotating equipment can be extended.

[0044] A rotating device according to the 19th aspect of the present invention comprises a sleeve according to the sixth aspect and each of the aspects relating thereto, a rolling bearing mounted inside the sleeve, a shaft inserted through the inner ring of the rolling bearing, and a biasing member that biases the inner ring inward in the axial direction, wherein the press-fit portion is located outward in the axial direction from the recess.

[0045] According to the 19th embodiment, the rolling elements, under the biasing force of the biasing member, contact a point on the raceway surface of the outer ring that is axially inward from its axial center. Since a recess is provided at a position axially inward from the press-fit portion to avoid contact between the sleeve and the outer ring, it is possible to suppress the propagation of sleeve distortion to the vicinity of the contact point with the rolling elements on the outer ring. Therefore, it is possible to suppress changes in the contact point with the rolling elements on the raceway surface of the outer ring, which can cause malfunctions in the rolling bearing.

[0046] A rotating device according to the 20th aspect of the present invention is a rotating device according to the 18th or 19th aspect described above, wherein the shaft is the rotating shaft of a motor, and the sleeve may be formed integrally with the chassis of the motor from synthetic resin.

[0047] According to the 20th embodiment, the sleeve and chassis are formed integrally, thereby reducing the number of parts and improving the productivity of the motor. [Effects of the Invention]

[0048] According to the present invention, it is possible to provide a sleeve that can suppress the occurrence of electrolytic corrosion in rolling bearings, as well as a bearing-equipped sleeve and rotating equipment equipped with the sleeve. [Brief explanation of the drawing]

[0049] [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 rolling bearing of the embodiment. [Figure 3]This is a longitudinal cross-sectional view of a rolling bearing according to an embodiment, showing the cross-section along line III-III in Figure 2. [Figure 4] This figure shows the inner ring of the bearing shown in Figure 3 tilted relative to the outer ring. [Figure 5] This is a longitudinal cross-sectional view of a fan motor according to the first embodiment, and is an enlarged view showing the area around the sleeve. [Figure 6] This is a longitudinal cross-sectional view of a fan motor according to a second embodiment, and is an enlarged view showing the area around the sleeve. [Figure 7] This is a longitudinal cross-sectional view of a fan motor according to the third embodiment, and is an enlarged view showing the area around the sleeve. [Figure 8] This is a longitudinal cross-sectional view of a fan motor according to the fourth embodiment, and is an enlarged view showing the area around the sleeve. [Figure 9] This is a longitudinal cross-sectional view of a fan motor according to the fifth embodiment, and is an enlarged view showing the area around the sleeve. [Figure 10] This figure shows the shaft shown in Figure 9 tilted and in contact with the restricting portion of the sleeve. [Figure 11] Figure 9 shows the state in which the tapered surface of the shaft is in contact with the upper end opening edge of the inner ring of the second bearing. [Figure 12] This is a longitudinal cross-sectional view of a fan motor according to the sixth embodiment, and is an enlarged view showing the area around the sleeve. [Figure 13] This is a longitudinal cross-sectional view of the fan motor according to the seventh embodiment, and is an enlarged view showing the area around the sleeve. [Figure 14] This is a longitudinal cross-sectional view of the fan motor of the eighth embodiment, and is an enlarged view showing the area around the sleeve. [Figure 15] This is a longitudinal cross-sectional view of a modified embodiment of a fan motor, and is an enlarged view showing the area around the sleeve. [Modes for carrying out the invention]

[0050] 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.

[0051] 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 111, a cylindrical sleeve 140 that supports the shaft 111 of the rotating body 110 so as to be rotatable relative to it, a base 120 that supports the sleeve 140 so as not to be rotatable relative to it, a drive unit 130 that rotates the rotating body 110 relative to the base 120, and a pair of rolling bearings 1 mounted on the sleeve 140 and supporting the shaft 111 so as to be rotatable. 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 sleeve 140 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, and the other is defined as downward.

[0052] The sleeve 140 is externally fitted onto the shaft 111 of the rotating body 110. The sleeve 140 rotatably supports the shaft 111 via a pair of bearings 1. The specific shape of the sleeve 140 will be described later.

[0053] The sleeve 140 is formed from an electrically insulating synthetic resin material. The synthetic resin used to form the sleeve 140 is preferably one or more of the following materials, which have low moisture absorption, allow for easy molding accuracy, and exhibit excellent chemical resistance: polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). Furthermore, the synthetic resin should contain potassium titanate whiskers as a reinforcing agent. The potassium titanate whiskers are preferably added at a concentration of 5% to 50%, and more preferably at 10% to 30%. It is desirable not to add glass fiber or carbon fiber to the synthetic resin as a reinforcing agent. This is because the addition of hard glass fiber or carbon fiber to the synthetic resin makes it difficult to process the sleeve 140 after injection molding using machining methods such as centerless grinding, and can easily damage grinding wheels and cutting tools. Additionally, there is a risk that the hard glass fiber or carbon fiber may detach from the synthetic resin and enter the bearing, causing rotational problems. On the other hand, potassium titanate whiskers are softer than glass fiber or carbon fiber, and are smaller in both thickness and length, making them easy to machine. Synthetic resins to which potassium titanate whiskers are added are easier to machine than synthetic resins alone. Even if potassium titanate whiskers detach from the synthetic resin and enter the inside of the bearing, their small size makes them unlikely to cause bearing rotational problems. Furthermore, by not including carbon fiber as a reinforcing material, the electrical insulation properties of sleeve 140 can be ensured.

[0054] The base portion 120 is coupled to the lower end of the sleeve 140 in a manner that prevents relative rotation. The base portion 120 extends radially outward from the lower end of the sleeve 140. The base portion 120 is integrally formed with the sleeve 140. That is, the base portion 120 is integrally molded from the same material as the sleeve 140. The base portion 120 is, for example, the chassis of the fan motor 100. Note that the base portion 120 may be provided as a separate component from the sleeve 140. In this case, the base portion may be formed from a metal material.

[0055] The rotating body 110 is positioned above the base 120. The rotating body 110 comprises a shaft 111 and a fan 112 connected to the shaft 111 outside the sleeve 140. The shaft 111 is positioned coaxially with the sleeve 140. The shaft 111 penetrates the sleeve 140 in the vertical direction. The lower end of the shaft 111 has an annular tapered surface 111a that tapers downwards. The entire tapered surface 111a is located below the pair of bearings 1. In the illustrated example, the shaft 111 has a tip surface that is perpendicular to the axial direction and surrounded by the tapered surface 111a.

[0056] The fan 112 is fixed to the upper end of the shaft 111. The fan 112 comprises a flange 113 that extends radially outward from the upper end of the shaft 111 and extends along its entire circumference, a circumferential wall 114 that extends downward from the entire outer edge of the flange 113, and a plurality of blades 115 that are spaced apart in the circumference on the radially outer side of the circumferential wall 114. The circumferential wall 114 surrounds the sleeve 140 around its entire circumference, with a radial gap between the sleeve 140 and the sleeve 140.

[0057] The drive unit 130 is the drive source for the fan motor 100. 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 sleeve 140. The rotor 132 is fixed to the peripheral wall 114 of the fan 112 radially outward of the stator 131.

[0058] Each pair of bearings 1 is interposed between the inner circumferential surface of the sleeve 140 and the outer circumferential surface of the shaft 111. Each bearing 1 is a ball bearing. The pair of bearings 1 are arranged coaxially with respect to each other. The pair of bearings 1 are spaced apart in the axial direction.

[0059] The pair of bearings 1 are a first bearing 1A and a second bearing 1B. The first bearing 1A is inserted into the sleeve 140 from the rotating body 110 side. The outer ring 20 of the first bearing 1A is not rotatable relative to the sleeve 140. The outer ring 20 of the first bearing 1A is engaged with the inner circumferential surface of the sleeve 140, restricting its displacement axially inward (downward). The inner ring 10 of the first bearing 1A is in contact with a biasing member 101. The biasing member 101 is a coil spring. The biasing member 101 is located axially outward (upward) of the first bearing 1A. The biasing member 101 is externally fitted onto the shaft 111 of the rotating body 110 and is located coaxially with the central axis O. The biasing member 101 is interposed between the inner ring 10 of the first bearing 1A and the flange 113 of the fan 112. The biasing member 101 biases the inner ring 10 of the first bearing 1A axially inward (downward) relative to the rotating body 110.

[0060] The second bearing 1B is inserted into the sleeve 140 from the opposite side of the rotating body 110. The outer ring 20 of the second bearing 1B is not rotatable relative to the sleeve 140. The outer ring 20 of the second bearing 1B engages with the inner circumferential surface of the sleeve 140, restricting its axial inward (upward) displacement. The inner ring 10 of the second bearing 1B is in contact with a C-ring 103 mounted on the shaft 111. The C-ring 103 is positioned between the second bearing 1B and the tapered surface 111a of the shaft 111. The inner ring 10 of the second bearing 1B is restricted by the C-ring 103 from axial outward (downward) displacement relative to the shaft 111.

[0061] The structure of bearing 1 will be described. Figure 2 is a plan view of the bearing according to the embodiment. Figure 3 is a longitudinal cross-sectional view of the bearing according to the embodiment, showing the cross-section along line III-III in Figure 2. As shown in Figures 2 and 3, each bearing 1 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 are arranged coaxially with each other, except when they are tilted relative to each other (described later). The outer ring 20 and the sleeve 140 share a common central axis O.

[0062] The inner ring 10 is provided as a rotating ring. The inner ring 10 is fitted onto the shaft 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.

[0063] The outer ring 20 is formed in an annular shape from a metallic material such as stainless steel or bearing steel. The outer ring 20 has an inner circumferential surface 22 facing the inner ring 10 and an inner end surface facing inward in the axial direction. The inner circumferential surface 22 has an outer ring raceway surface 23 on which the rolling elements 30 roll and a fitting groove 24 for holding the seal member 50. The outer ring raceway surface 23 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 elements 30, and is also formed in an annular shape that extends circumferentially over the entire circumference of the inner circumferential surface 22. The outer ring raceway surface 23 is formed in the portion of the inner circumferential surface 22 that is located in the axial center. In the longitudinal cross-section of the bearing 1, the outer ring raceway surface 23 has a radius of curvature that is larger than the radius of the rolling elements 30.

[0064] A pair of fitting grooves 24 are formed at the axial ends of the inner circumferential surface 22. The fitting grooves 24 are recessed radially outward. The fitting grooves 24 open across the inner circumferential surface 22 and the axial end face. The fitting grooves 24 are formed in an annular shape that extends circumferentially around the entire circumference of the inner circumferential surface 22.

[0065] The inner ring 10 is formed in an annular shape from a metallic material such as stainless steel or bearing steel. 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 so as to follow the outer surface of the rolling element 30, and is also 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. In the longitudinal cross-section of the bearing 1, the inner ring raceway surface 11 has a radius of curvature that is larger than the radius of the rolling element 30.

[0066] 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.

[0067] As shown in Figure 3, 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 that protrude upward from the annular portion 41 and are 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 proportion 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.

[0068] As shown in Figures 2 and 3, 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 positioned on each axial side of the plurality of rolling elements 30. The sealing member 50 comprises a sealing fitting portion 51 that fits into the fitting groove 24 of the outer ring 20, and a cover portion 53 that protrudes radially inward from the sealing fitting portion 51. In plan view, the sealing member 50 extends radially so as to straddle at least the center of the rolling elements 30. The inner peripheral edge of the cover portion 53 is positioned with a gap between it and the outer peripheral surface of the inner ring 10. The sealing member 50 is fixed to the outer ring 20 by the sealing fitting portion 51 engaging with the wall surface of the fitting groove 24.

[0069] Figure 4 shows the inner ring of the bearing shown in Figure 3 tilted relative to the outer ring. As shown in Figure 4, the inner ring 10 and the outer ring 20 can tilt relative to each other because the radii of curvature of the outer ring raceway surface 23 and the inner ring raceway surface 11 are greater than the radius of the rolling element 30. In Figure 4, axis O' is the central axis of the inner ring 10 tilted relative to the outer ring 20. The bearing 1 has a set square clearance. The square clearance is the angle at which the inner ring 10 can tilt relative to the outer ring 20. The square clearance is defined for each bearing 1.

[0070] [First Embodiment] The sleeve 140 of the first embodiment will be described in detail. Figure 5 is a longitudinal cross-sectional view of the fan motor of the first embodiment, and is an enlarged view showing the area around the sleeve. As shown in Figure 5, the sleeve 140 is a single continuous component. The sleeve 140 integrally comprises a first retaining portion 141, a second retaining portion 142, a first outer ring receiving portion 143, and a second outer ring receiving portion 144. The entire sleeve 140 is formed from the above-mentioned electrically insulating synthetic resin.

[0071] The first retaining portion 141 holds the outer circumferential surface of the first bearing 1A. The first retaining portion 141 surrounds the first bearing 1A from the radially outside. The first retaining portion 141 holds the outer ring 20 of the first bearing 1A so that it cannot be displaced radially by contacting or being in close proximity to the outer circumferential surface of the outer ring 20 of the first bearing 1A in the radial direction. The first retaining portion 141 has a first recess 141a that opens radially inward toward the outer circumferential surface of the outer ring 20 of the first bearing 1A, and a first retaining surface 141b (press-fit portion) adjacent to the first recess 141a and extending along the outer circumferential surface of the outer ring 20 of the first bearing 1A.

[0072] The first recess 141a is formed at the axially inward end of the inner circumferential surface of the first retaining portion 141. The first recess 141a extends continuously over the entire circumferential direction. The opening of the first recess 141a faces the axially inward end of the outer circumferential surface of the outer ring 20 of the first bearing 1A. The first recess 141a faces the outer circumferential surface of the outer ring 20 from a point axially outside the axial center position on the outer ring raceway surface 23 to the axially inward end. As a result, the sleeve 140 is not in contact with the portion of the outer circumferential surface of the outer ring 20 of the first bearing 1A that extends from the axial center position on the outer ring raceway surface 23 to the axially inward end. The axial center position on the outer ring raceway surface 23 is the point on the outer ring raceway surface 23 where the normal direction is parallel to the radial direction. The first recess 141a comprises an outer surface 141c (inclined portion) extending radially outward from the axially outer portion of the opening edge of the first recess 141a, an inner surface extending radially outward from the axially inner portion of the opening edge of the first recess 141a, and a bottom surface connecting the outer surface 141c and the inner surface and facing radially inward. The bottom surface is a cylindrical surface extending in the axial direction. The outer surface 141c is a conical surface facing axially inward and radially inward, with its inner diameter decreasing as it moves axially outward. The inner surface is a flat surface extending in a direction perpendicular to the axial direction. No adhesive or the like is placed in the first recess 141a, and it is filled with a gas such as air.

[0073] The first retaining surface 141b is located axially outward from the first recess 141a. The first retaining surface 141b extends axially outward from the axially outward portion of the opening edge of the first recess 141a. The first retaining surface 141b extends downward from the upper end opening edge of the sleeve 140. The first retaining surface 141b is a cylindrical surface that extends axially. The first retaining surface 141b faces only the portion of the outer circumferential surface of the outer ring 20 that is axially outward from the axial center position of the outer ring raceway surface 23. The first retaining surface 141b faces the axially outward end of the outer circumferential surface of the outer ring 20. Note that the first retaining surface 141b does not have to face the axially outward end of the outer circumferential surface of the outer ring 20. In this case, the first bearing 1A protrudes axially outward from the inside of the first retaining surface 141b. The inner diameter of the first retaining surface 141b is smaller than the outer diameter of the outer ring 20 of the first bearing 1A when the first bearing 1A is not inserted into the first retaining portion 141. As a result, the first bearing 1A is press-fitted into the inside of the first retaining surface 141b.

[0074] The second retaining portion 142 is positioned at an axial distance from the first retaining portion 141. The second retaining portion 142 holds the outer circumferential surface of the second bearing 1B. The second retaining portion 142 surrounds the second bearing 1B from the radial outside. The second retaining portion 142 holds the outer ring 20 of the second bearing 1B so that it cannot be displaced radially by contacting or being in close proximity to the outer circumferential surface of the outer ring 20 of the second bearing 1B in the radial direction. The second retaining portion 142 has a second recess 142a that opens radially inward toward the outer circumferential surface of the outer ring 20 of the second bearing 1B, and a second retaining surface 142b that is adjacent to the second recess 142a and extends along the outer circumferential surface of the outer ring 20 of the second bearing 1B.

[0075] The second recess 142a is formed at the axially inward end of the inner circumferential surface of the second retaining portion 142. The second recess 142a extends continuously over the entire circumferential direction. The opening of the second recess 142a faces the axially inward end of the outer circumferential surface of the outer ring 20. The second recess 142a faces the outer circumferential surface of the outer ring 20 of the second bearing 1B from a point axially outside the axial center position on the outer ring raceway surface 23 to the axially inward end. As a result, the sleeve 140 is not in contact with the portion of the outer circumferential surface of the outer ring 20 of the second bearing 1B that extends from the axial center position on the outer ring raceway surface 23 to the axially inward end. The second recess 142a comprises an outer surface 142c (inclined portion) extending radially outward from the axially outer portion of the opening edge of the second recess 142a, an inner surface extending radially outward from the axially inner portion of the opening edge of the second recess 142a, and a bottom surface connecting the outer surface 142c and the inner surface and facing radially inward. The bottom surface is a cylindrical surface extending in the axial direction. The outer surface 142c is a conical surface facing axially inward and radially inward. The inner surface is a flat surface extending in a direction perpendicular to the axial direction. No adhesive or the like is placed in the second recess 142a, and it is filled with a gas such as air.

[0076] The second retaining surface 142b is located axially outward from the second recess 142a. The second retaining surface 142b extends axially outward from the axially outward portion of the opening edge of the second recess 142a. The second retaining surface 142b is a cylindrical surface extending in the axial direction. The second retaining surface 142b faces only the portion of the outer circumferential surface of the outer ring 20 that is axially outward from the axial center position of the outer ring raceway surface 23. The second retaining surface 142b faces the axially outward end of the outer circumferential surface of the outer ring 20. Note that the second retaining surface 142b does not have to face the axially outward end of the outer circumferential surface of the outer ring 20. In this case, the second bearing 1B protrudes axially outward from the inside of the second retaining surface 142b. The inner diameter of the second retaining surface 142b is smaller than the outer diameter of the outer ring 20 of the second bearing 1B when the second bearing 1B is not inserted into the second retaining portion 142. As a result, the second bearing 1B is press-fitted into the inside of the second retaining surface 142b.

[0077] The first outer ring support portion 143 contacts the inner end face of the outer ring 20 of the first bearing 1A from the axially inward (downward) direction. The first outer ring support portion 143 is part of the inner circumferential surface of the sleeve 140. The first outer ring support portion 143 is located axially inward and radially inward relative to the first retaining portion 141. The first outer ring support portion 143 is provided without any axial gap from the first recess 141a. The first outer ring support portion 143 extends radially inward from the axially inward portion of the opening edge of the first recess 141a. The first outer ring support portion 143 faces axially outward (upward) and extends circumferentially. The first outer ring support portion 143 has a constant width in the radial direction and extends continuously over its entire circumferential surface. The first outer ring support portion 143 is a flat surface that extends in a direction perpendicular to the axial direction. In other words, the first outer ring support portion 143 extends continuously from the inner surface of the first recess 141a. The inner diameter of the first outer ring support portion 143 is larger than the outer diameter of the inner ring 10 and larger than the inner diameter of the outer ring 20. However, the inner diameter of the first outer ring support portion 143 may be smaller than the inner diameter of the outer ring 20. In this case, the inner diameter of the first outer ring support portion 143 is larger than the outer diameter of the inner ring 10 of the first bearing 1A.

[0078] The second outer ring support portion 144 contacts the inner end face of the outer ring 20 of the second bearing 1B from the axially inward (above) direction. The second outer ring support portion 144 is part of the inner circumferential surface of the sleeve 140. The second outer ring support portion 144 is located axially inward and radially inward relative to the second retaining portion 142. The second outer ring support portion 144 is provided without any axial gap from the second recess 142a. The second outer ring support portion 144 extends radially inward from the axially inward portion of the opening edge of the second recess 142a. The second outer ring support portion 144 faces axially outward (downward) and extends circumferentially. The second outer ring support portion 144 has a constant width in the radial direction and extends continuously over its entire circumferential surface. The second outer ring support portion 144 is a flat surface that extends in a direction perpendicular to the axial direction. In other words, the second outer ring support portion 144 extends continuously from the inner surface of the second recess 142a. The inner diameter of the second outer ring support portion 144 is larger than the outer diameter of the inner ring 10 and larger than the inner diameter of the outer ring 20. However, the inner diameter of the second outer ring support portion 144 may be smaller than the inner diameter of the outer ring 20. In this case, the inner diameter of the second outer ring support portion 144 is larger than the outer diameter of the inner ring 10 of the second bearing 1B.

[0079] A parting line P is formed on the inner circumferential surface of the sleeve 140 during injection molding of the sleeve 140. The parting line P extends continuously along the entire circumferential direction. The parting line P is located on the opposite side of the first retaining portion 141 from the first outer ring receiving portion 143, and on the opposite side of the second retaining portion 142 from the second outer ring receiving portion 144. As a result, the parting line P is located axially inward from both the first bearing 1A and the second bearing 1B, and does not come into contact with the first bearing 1A and the second bearing 1B.

[0080] The effects and advantages of this embodiment will be described below. Unless otherwise specified, the effects and advantages of the mounting structure of the first bearing 1A will be described below, but the effects and advantages of the mounting structure of the second bearing 1B will be similar.

[0081] The sleeve 140 is a cylindrical sleeve 140 in which the first bearing 1A is mounted on the inside, and comprises a first retaining portion 141 that holds the outer circumferential surface of the first bearing 1A, and a first outer ring receiving portion 143 that contacts the end face of the outer ring 20 of the first bearing 1A from the axial inner side. The first retaining portion 141 has a first recess 141a that opens radially inward toward the outer circumferential surface of the outer ring 20. The sleeve 140 is made of an electrically insulating synthetic resin. With this configuration, it is possible to suppress the flow of current into the first bearing 1A through the sleeve 140. This makes it possible to suppress the occurrence of electrolytic corrosion in the first bearing 1A.

[0082] Here, in order to suppress the slippage of the outer ring 20 of the first bearing 1A relative to the sleeve 140, it is necessary to fix the outer ring 20 to the sleeve 140. In a configuration in which the outer ring 20 is fixed to the sleeve 140 by press-fitting, there is a possibility that the distortion of the synthetic resin sleeve 140 will spread to the outer ring 20. If the distortion of the sleeve 140 spreads to the outer ring 20, the contact point between the outer ring 20 and the rolling element 30 on the outer ring raceway surface 23 may change, potentially causing malfunction of the first bearing 1A. According to this embodiment, since the first retaining portion 141 that holds the outer circumferential surface of the first bearing 1A is provided with a first recess 141a that opens toward the outer circumferential surface of the first bearing 1A, it is possible to suppress the propagation of the distortion of the sleeve 140 to the outer ring 20 via the contact portion between the sleeve 140 and the outer ring 20. Therefore, it is possible to suppress the change in the contact point between the outer ring 20 and the rolling element 30 on the outer ring raceway surface 23, which can cause malfunction of the first bearing 1A. As a result, it is possible to form a synthetic resin sleeve 140 on which the first bearing 1A is mounted while suppressing the occurrence of various problems.

[0083] The sleeve 140 has a parting line P formed during the molding of the sleeve 140 at a position on its inner circumferential surface opposite the first retaining portion 141 to the first outer ring receiving portion 143. With this configuration, it is possible to avoid the parting line P being formed at the contact portion of the sleeve 140 with the first bearing 1A. This suppresses the parting line P from reducing the assembly accuracy of the first bearing 1A, and also suppresses an increase in manufacturing costs by eliminating the need for processing such as grinding off the parting line P in order to assemble the first bearing 1A into the sleeve 140.

[0084] Potassium titanate whiskers are added to the synthetic resin that forms the sleeve 140. This configuration allows the sleeve 140 to be a component with excellent wear resistance and surface smoothness. Furthermore, synthetic resins containing potassium titanate whiskers have good machinability and are less prone to clogging during grinding, resulting in excellent processability. Therefore, compared to cases where the sleeve 140 contains glass fiber or carbon fiber as a reinforcing material, the processability when forming the sleeve by machining such as cutting and grinding, and the processability when finishing the injection-molded sleeve 140 by secondary processing such as cutting and grinding can be improved.

[0085] The first recess 141a extends continuously over its entire circumferential direction. This configuration makes it possible to more reliably suppress the propagation of strain in the sleeve 140 to the outer ring 20.

[0086] The first recess 141a has an outer surface 141c whose inner diameter decreases as it moves outward in the axial direction. With this configuration, when injection molding the sleeve 140, it is easy to forcibly remove the portion of the mold that forms the first recess 141a outward in the axial direction. Therefore, the sleeve 140 can be easily formed by injection molding.

[0087] The first retaining portion 141 has a first retaining surface 141b located axially outward from the first recess 141a, with an inner diameter smaller than the outer diameter of the first bearing 1A. With this configuration, the outer ring 20 is fixed to the first retaining portion 141 of the sleeve 140 by press-fitting, thus providing a suitable configuration that suppresses the propagation of distortion of the sleeve 140 to the outer ring 20.

[0088] The entire sleeve 140 is made of synthetic resin. This configuration makes it possible to more reliably suppress the flow of current into the first bearing 1A through the sleeve 140. Furthermore, compared to a configuration in which only a part of the sleeve is made of synthetic resin, the sleeve 140 can be easily manufactured, and the manufacturing cost of the sleeve 140 can be reduced.

[0089] The fan motor 100 comprises a sleeve 140, a first bearing 1A mounted inside the sleeve 140, and a shaft 111 inserted through the inner ring 10 of the first bearing 1A. This configuration suppresses the increase in rotational resistance of the first bearing 1A due to electrolytic corrosion. Therefore, a longer lifespan for the fan motor 100 can be achieved.

[0090] The fan motor 100 further includes a biasing member 101 that biases the inner ring 10 inward in the axial direction. With this configuration, the rolling element 30, under the biasing force of the biasing member 101, contacts the outer ring raceway surface 23 at a location axially inward from its axial center. Since a first recess 141a is provided at a position axially inward from the first retaining surface 141b to avoid contact between the sleeve 140 and the outer ring 20, it is possible to suppress the propagation of distortion of the sleeve 140 to the vicinity of the contact point with the rolling element 30 on the outer ring 20. Therefore, it is possible to suppress changes in the contact point with the rolling element 30 on the outer ring raceway surface 23 and the resulting malfunction of the first bearing 1A.

[0091] In particular, in this embodiment, the sleeve 140 does not contact the outer circumferential surface of the outer ring 20 at a position axially inward from the axial center position on the outer ring raceway surface 23. Therefore, even if distortion occurs in the sleeve 140 near the contact point between the outer ring 20 and the rolling element 30, it is possible to prevent that distortion from spreading to the outer ring 20. Consequently, it is possible to suppress changes in the contact point with the rolling element 30 on the outer ring raceway surface 23, which would otherwise cause malfunctions in the first bearing 1A.

[0092] The shaft 111 is the rotation axis of the fan motor 100. The sleeve 140 is formed integrally with the base 120, which is the chassis of the fan motor 100, from synthetic resin. This configuration makes it possible to suppress the flow of current inside the first bearing 1A and the resulting electrolytic corrosion of the first bearing 1A. Furthermore, by forming the sleeve 140 and the chassis integrally, the number of parts can be reduced, thereby improving the productivity of the fan motor 100.

[0093] In this embodiment, the recesses 141a and 142a of each retaining portion 141 and 142 face a portion of the outer circumferential surface of the outer ring 20 that corresponds to the axial center position on the outer ring raceway surface 23, but the configuration is not limited to this. That is, the recesses may face only the portion of the outer circumferential surface of the outer ring that is axially inward from the axial center position on the outer ring raceway surface 23.

[0094] [Second Embodiment] The sleeve 240 of the second embodiment will be described in detail. In the second embodiment, the shapes of the first recess and the second recess of the sleeve differ from those of the first embodiment. Other than what is described below, the configuration is the same as in the first embodiment.

[0095] Figure 6 is a longitudinal cross-sectional view of the fan motor of the second embodiment, and is an enlarged view showing the area around the sleeve. As shown in Figure 6, the sleeve 240 includes a first retaining portion 241 and a second retaining portion 242, instead of the first retaining portion 141 and second retaining portion 142 of the first embodiment.

[0096] The first retaining portion 241 has a first recess 241a instead of the first recess 141a of the first embodiment. The first recess 241a is a curved surface that recesses radially outward on the longitudinal cross-section of the sleeve 240. The first half 241c (inclined portion) of the first recess 241a on the axial outward side extends radially outward from the axially outward portion of the opening edge of the first recess 241a, and its inner diameter decreases as it moves axially outward. The second half of the first recess 241a on the axial inward side extends radially outward from the axially inward portion of the opening edge of the first recess 241a, and its inner diameter decreases as it moves axially inward.

[0097] The second retaining portion 242 has a second recess 242a instead of the second recess 142a of the first embodiment. The second recess 242a is a curved surface that recesses radially outward on the longitudinal cross-section of the sleeve 240. The first axially outward half 242c of the second recess 242a extends radially outward from the axially outward portion of the opening edge of the second recess 242a, and its inner diameter decreases as it moves axially outward. The second axially inward half of the second recess 242a extends radially outward from the axially inward portion of the opening edge of the second recess 242a, and its inner diameter decreases as it moves axially inward.

[0098] In this embodiment, the sleeve 240 is made of an electrically insulating synthetic resin, and the holding portions 241 and 242 have recesses 241a and 242a that open radially inward, thus achieving the same effects as in the first embodiment.

[0099] [Third Embodiment] The sleeve 340 of the third embodiment will be described in detail. In the first embodiment, the bearings 1A and 1B are fixed to the sleeve 140 by press-fitting. In contrast, the third embodiment differs from the first embodiment in that the bearings 1A and 1B are fixed to the sleeve 340 by adhesive. Other than what is described below, the configuration is the same as in the first embodiment.

[0100] Figure 7 is a longitudinal cross-sectional view of the fan motor of the third embodiment, and is an enlarged view showing the area around the sleeve. As shown in Figure 7, the sleeve 340 includes a first retaining portion 341 and a second retaining portion 342, instead of the first retaining portion 141 and second retaining portion 142 of the first embodiment.

[0101] The first retaining portion 341 has a first recess 341a and a first retaining surface 341b, instead of the first recess 141a and first retaining surface 141b of the first embodiment.

[0102] The first recess 341a is formed at an axial distance from the first outer ring support portion 143. The first recess 341a extends continuously over its entire circumferential surface. The entire opening of the first recess 341a faces the portion of the outer circumferential surface of the outer ring 20 of the first bearing 1A that is axially outward from the axially inward end. Furthermore, in this embodiment, the entire opening of the first recess 341a faces the portion of the outer circumferential surface of the outer ring 20 that is axially inward from the axially outward end.

[0103] The first recess 341a comprises an outer surface 341c (inclined portion) extending radially outward from the axially outer portion of the opening edge of the first recess 341a, and an inner surface extending radially outward from the axially inner portion of the opening edge of the first recess 341a. The outer surface 341c is a conical surface facing axially inward and radially inward, with its inner diameter decreasing as it moves axially outward. The inner surface is connected to the radially inner edge of the outer surface 341c and is a flat surface extending in a direction perpendicular to the axial direction.

[0104] An adhesive (not shown) is placed in the first recess 341a, and the first recess 341a functions as an adhesive reservoir. The adhesive fixes the sleeve 340 and the outer ring 20 to each other.

[0105] The first retaining surface 341b is located axially inward of the first recess 341a. The first retaining surface 341b extends axially inward from the axially inward portion of the opening edge of the first recess 341a. The axially inward edge of the first retaining surface 341b is connected to the first outer ring support portion 143. The first retaining surface 341b is an axially extending cylindrical surface. The first retaining surface 341b faces the axially inward end of the outer circumferential surface of the outer ring 20.

[0106] Furthermore, in this embodiment, the first retaining surface 341b is also located axially outward from the first recess 341a. The first retaining surface 341b extends axially outward from the axially outward portion of the opening edge of the first recess 341a. The first retaining surface 341b extends downward from the upper end opening edge of the sleeve 340. The first retaining surface 341b faces the axially outward end of the outer circumferential surface of the outer ring 20. Note that the first retaining surface 341b does not have to face the axially outward end of the outer circumferential surface of the outer ring 20. In this case, the first bearing 1A protrudes axially outward from the inside of the first retaining surface 341b.

[0107] The inner diameter of the first retaining surface 341b is greater than or equal to the outer diameter of the outer ring 20 of the first bearing 1A when the first bearing 1A is not inserted into the first retaining portion 341. Therefore, even when the first bearing 1A is inserted into the first retaining portion 341, the inner diameter of the first retaining surface 341b is greater than or equal to the outer diameter of the outer ring 20 of the first bearing 1A. If the inner diameter of the first retaining surface 341b is greater than the outer diameter of the outer ring 20, an adhesive may be interposed between the first retaining surface 341b and the outer circumferential surface of the outer ring 20.

[0108] The second retaining portion 342 has a second recess 342a and a second retaining surface 342b, instead of the second recess 142a and second retaining surface 142b of the first embodiment.

[0109] The second recess 342a is formed at an axial distance from the second outer ring support portion 144. The second recess 342a extends continuously over its entire circumferential surface. The entire opening of the second recess 342a faces the portion of the outer circumferential surface of the second bearing 1B's outer ring 20 that is axially outer than the axially inner end. Furthermore, in this embodiment, the entire opening of the second recess 342a faces the portion of the outer circumferential surface of the outer ring 20 that is axially inner than the axially outer end.

[0110] The second recess 342a comprises an outer surface 342c (inclined portion) extending radially outward from the axially outer portion of the opening edge of the second recess 342a, and an inner surface extending radially outward from the axially inner portion of the opening edge of the second recess 342a. The outer surface 342c is a conical surface facing axially inward and radially inward, with its inner diameter decreasing as it moves axially outward. The inner surface is connected to the radially inner edge of the outer surface 342c and is a flat surface extending in a direction perpendicular to the axial direction.

[0111] Adhesive (not shown) is placed in the second recess 342a, and the second recess 342a functions as an adhesive reservoir. The adhesive fixes the sleeve 340 and the outer ring 20 to each other.

[0112] The second retaining surface 342b is located axially inward of the second recess 342a. The second retaining surface 342b extends axially inward from the axially inward portion of the opening edge of the second recess 342a. The axially inward edge of the second retaining surface 342b is connected to the second outer ring support portion 144. The second retaining surface 342b is an axially extending cylindrical surface. The second retaining surface 342b faces the axially inward end of the outer circumferential surface of the outer ring 20.

[0113] Furthermore, in this embodiment, the second retaining surface 342b is also located axially outward from the second recess 342a. The second retaining surface 342b extends axially outward from the axially outward portion of the opening edge of the second recess 342a. The second retaining surface 342b faces the axially outward end of the outer circumferential surface of the outer ring 20. Note that the second retaining surface 342b does not have to face the axially outward end of the outer circumferential surface of the outer ring 20. In this case, the second bearing 1B protrudes axially outward from the inside of the second retaining surface 342b.

[0114] The inner diameter of the second retaining surface 342b is greater than or equal to the outer diameter of the outer ring 20 of the second bearing 1B when the second bearing 1B is not inserted into the second retaining portion 342. Therefore, even when the second bearing 1B is inserted into the second retaining portion 342, the inner diameter of the second retaining surface 342b is greater than or equal to the outer diameter of the outer ring 20 of the second bearing 1B. If the inner diameter of the second retaining surface 342b is greater than the outer diameter of the outer ring 20, an adhesive may be interposed between the second retaining surface 342b and the outer circumferential surface of the outer ring 20.

[0115] This embodiment provides the same effects as the first embodiment. In addition, this embodiment provides the following effects. Unless otherwise specified below, the effects relating to the mounting structure of the first bearing 1A will be described, but the effects relating to the mounting structure of the second bearing 1B are also similar.

[0116] In this embodiment, the sleeve 340 is fixed to the outer ring 20 by adhesive. When the outer ring 20 is fixed to the sleeve 340 by adhesive, the first recess 341a can function as an adhesive reservoir. This prevents the adhesive from leaking into the first bearing 1A through the space between the sleeve 340 and the outer ring 20, and prevents the adhesive from adhering to unintended locations, thus preventing malfunction of the first bearing 1A. As a result, a synthetic resin sleeve 340 on which the first bearing 1A is mounted can be formed while suppressing the occurrence of various problems.

[0117] The first recess 341a extends continuously over its entire circumferential direction. This configuration allows the first recess 341a to function more reliably as an adhesive reservoir.

[0118] The first recess 341a is positioned at an axial distance from the first outer ring support portion 143. This configuration allows for a longer path distance between the sleeve 340 and the outer ring 20, from the first recess 341a through the space between the end face of the outer ring 20 and the first outer ring support portion 143 to the interior of the first bearing 1A, compared to a configuration in which the first recess is positioned without an axial distance from the first outer ring support portion. This prevents the adhesive placed in the first recess 341a from leaking into the interior of the first bearing 1A through the space between the end face of the outer ring 20 and the first outer ring support portion 143 in a configuration in which the outer ring 20 is fixed to the sleeve 340 by adhesive. Therefore, it is possible to more reliably prevent the adhesive from adhering to unintended locations and causing malfunctions of the first bearing 1A.

[0119] [Fourth Embodiment] The sleeve 440 of the fourth embodiment will now be described. In the third embodiment, the retaining surface of each retaining portion of the sleeve is located axially outward from the recess. In contrast, the fourth embodiment differs from the third embodiment in that the retaining surface is not located axially outward from the recess. Other than what is described below, the configuration is the same as in the third embodiment.

[0120] Figure 8 is a longitudinal cross-sectional view of the fan motor according to the fourth embodiment, and is an enlarged view showing the area around the sleeve. As shown in Figure 8, the sleeve 440 includes a first retaining portion 441 and a second retaining portion 442, instead of the first retaining portion 341 and second retaining portion 342 of the third embodiment.

[0121] The first retaining portion 441 has a first recess 441a and a first retaining surface 441b, instead of the first recess 341a and first retaining surface 341b of the third embodiment.

[0122] The first recess 441a is formed at an axial distance from the first outer ring support portion 143. The first recess 441a extends continuously over its entire circumferential surface. The opening of the first recess 441a faces the axially outer end of the outer circumferential surface of the outer ring 20. As a result, the sleeve 440 does not contact the axially outer end of the outer circumferential surface of the outer ring 20 of the first bearing 1A. The first recess 441a opens axially outward at the axial end face of the sleeve 440.

[0123] The first recess 441a comprises an inner surface extending radially outward from the axially inward portion of the opening edge of the first recess 441a, and a bottom surface extending axially outward from the radially outward edge of the inner surface. The inner surface is a flat surface extending in a direction perpendicular to the axial direction. The bottom surface is a cylindrical surface extending in the axial direction. Thus, the entire wall surface of the first recess 441a is oriented radially inward, or inclined radially outward with respect to the radially inward, such that its normal vector does not contain an axially inward component.

[0124] An adhesive (not shown) is placed in the first recess 441a, and the first recess 441a functions as an adhesive reservoir. The adhesive fixes the sleeve 440 and the outer ring 20 to each other.

[0125] The first retaining surface 441b is located axially inward of the first recess 441a. The first retaining surface 441b extends axially inward from the axially inward portion of the opening edge of the first recess 441a. The axially inward end of the first retaining surface 441b is connected to the first outer ring support portion 143. The first retaining surface 441b is an axially extending cylindrical surface. The first retaining surface 441b faces the axially inward end of the outer circumferential surface of the outer ring 20.

[0126] The inner diameter of the first retaining surface 441b is greater than or equal to the outer diameter of the outer ring 20 of the first bearing 1A when the first bearing 1A is not inserted into the first retaining portion 441. Therefore, even when the first bearing 1A is inserted into the first retaining portion 441, the inner diameter of the first retaining surface 441b is greater than or equal to the outer diameter of the outer ring 20 of the first bearing 1A. If the inner diameter of the first retaining surface 441b is greater than the outer diameter of the outer ring 20, an adhesive may be interposed between the first retaining surface 441b and the outer circumferential surface of the outer ring 20.

[0127] The second retaining portion 442 has a second recess 442a and a second retaining surface 442b instead of the second recess 342a and second retaining surface 342b of the first embodiment.

[0128] The second recess 442a is formed at an axial distance from the second outer ring support portion 144. The second recess 442a extends continuously over its entire circumferential surface. The opening of the second recess 442a faces the axially outer end of the outer circumferential surface of the outer ring 20. As a result, the sleeve 440 does not contact the axially outer end of the outer circumferential surface of the outer ring 20 of the second bearing 1B. The second recess 442a opens axially outward at the axial end face of the sleeve 440.

[0129] The second recess 442a comprises an inner surface extending radially outward from the axially inward portion of the opening edge of the second recess 442a, and a bottom surface extending axially outward from the radially outward edge of the inner surface. The inner surface is a flat surface extending in a direction perpendicular to the axial direction. The bottom surface is a cylindrical surface extending in the axial direction. Thus, the entire wall surface of the second recess 442a is oriented radially inward, or inclined radially outward with respect to the radially inward direction, such that its normal vector does not contain an axially inward component.

[0130] Adhesive (not shown) is placed in the second recess 442a, and the second recess 442a functions as an adhesive reservoir. The adhesive fixes the sleeve 440 and the outer ring 20 to each other.

[0131] The second retaining surface 442b is located axially inward of the second recess 442a. The second retaining surface 442b extends axially inward from the axially inward portion of the opening edge of the second recess 442a. The axially inward edge of the second retaining surface 442b is connected to the second outer ring support portion 144. The second retaining surface 442b is an axially extending cylindrical surface. The second retaining surface 442b faces the axially inward end of the outer circumferential surface of the outer ring 20.

[0132] The inner diameter of the second retaining surface 442b is greater than or equal to the outer diameter of the outer ring 20 of the second bearing 1B when the second bearing 1B is not inserted into the second retaining portion 442. Therefore, even when the second bearing 1B is inserted into the second retaining portion 442, the inner diameter of the second retaining surface 442b is greater than or equal to the outer diameter of the outer ring 20 of the second bearing 1B. If the inner diameter of the second retaining surface 442b is greater than the outer diameter of the outer ring 20, an adhesive may be interposed between the second retaining surface 442b and the outer circumferential surface of the outer ring 20.

[0133] This embodiment provides the same effects as the third embodiment. In addition, this embodiment provides the following effects. Unless otherwise specified below, the effects relating to the mounting structure of the first bearing 1A will be described, but the effects relating to the mounting structure of the second bearing 1B are also similar.

[0134] The first recess 441a opens outward in the axial direction at the axial end face of the sleeve 440. With this configuration, when injection molding the sleeve 440, the portion of the mold that forms the first recess 441a can be easily removed outward in the axial direction. Therefore, the sleeve 440 can be easily formed by injection molding.

[0135] [Fifth Embodiment] The sleeve 140A of the fifth embodiment will now be described. The fifth embodiment differs from the first embodiment in that a protrusion is provided on the inner circumferential surface of the sleeve. Other than what is described below, the configuration is the same as that of the first embodiment.

[0136] Figure 9 is a longitudinal cross-sectional view of the fan motor according to the fifth embodiment, and is an enlarged view showing the area around the sleeve. As shown in Figure 9, the sleeve 140A is a single continuous member. In addition to the first retaining portion 141, the second retaining portion 142, the first outer ring receiving portion 143, and the second outer ring receiving portion 144, the sleeve 140A further comprises a protruding portion 145.

[0137] The projection 145 is provided on the inner circumferential surface of the sleeve 140A. The projection 145 is provided between the first retaining portion 141 and the second retaining portion 142. That is, the projection 145 is formed below the first outer ring bearing portion 143. The axial range of the projection 145 includes the center positions of the first bearing 1A and the second bearing 1B. The projection 145 protrudes radially inward from the first outer ring bearing portion 143. The projection 145 extends continuously over its entire circumferential direction. The projection 145 comprises an inner circumferential surface 146 extending axially at a position radially inward from the inner circumferential edge of the first outer ring bearing portion 143, an upper end surface 147 extending radially outward from the upper end edge of the inner circumferential surface 146, and a lower end surface 148 extending radially outward from the lower end edge of the inner circumferential surface 146.

[0138] The inner circumferential surface 146 is a cylindrical surface centered on the central axis O, extending axially with a constant inner diameter. The upper edge of the inner circumferential surface 146 is positioned axially apart from the first outer ring support portion 143. The inner diameter of the projection 145 is less than or equal to the outer diameter of the inner ring 10 of the first bearing 1A. The inner diameter of the projection 145 is the same as the inner diameter of the inner circumferential surface 146. The projection 145 has an inner diameter larger than the inner ring 10 of the first bearing 1A, forming a radial gap between it and the outer circumferential surface of the shaft 111. The upper edge of the inner circumferential surface 146 is located below the inner ring 10 of the first bearing 1A. The lower edge of the inner circumferential surface 146 is located above the second bearing 1B.

[0139] The inner circumferential surface 146 of the protrusion 145 is provided with a restricting portion 146a. The restricting portion 146a is at least a part of the protrusion 145. The extent of the restricting portion 146a is defined by the function described later.

[0140] The upper end surface 147 faces upward and extends in the circumferential direction. The upper end surface 147 has a constant width in the radial direction and extends continuously over its entire circumferential direction. The upper end surface 147 is a flat surface perpendicular to the axial direction. The upper end surface 147 may be able to contact the inner ring 10, which is inclined with respect to the outer ring 20 of the first bearing 1A at an angle of less than or equal to the angular clearance, from below, or it may not be able to contact the inner ring 10, which is inclined with respect to the outer ring 20 of the first bearing 1A. The lower end surface 148 faces downward and extends in the circumferential direction. The lower end surface 148 has a constant width in the radial direction and extends continuously over its entire circumferential direction. The lower end surface 148 is a flat surface perpendicular to the axial direction.

[0141] When assembling the shaft 111 into the sleeve 140A, the shaft 111 is inserted into the inside of the sleeve 140A from above. There are two methods for assembling the shaft 111 into the sleeve 140A: one in which the shaft 111 is inserted into the sleeve 140 while the first bearing 1A and the second bearing 1B are held in the retaining parts 141 and 142 (hereinafter referred to as the first method); and the other in which the shaft 111, with the first bearing 1A externally fitted, is inserted into the sleeve 140A while the second bearing 1B is held in the second retaining part 142 (hereinafter referred to as the second method).

[0142] The first method will be described. After the shaft 111 passes through the first bearing 1A, it passes inside the projection 145 of the sleeve 140A. The shaft 111 can come into contact with the inner circumferential surface 146 of the projection 145 during the process of being inserted into the first bearing 1A. Note that if the shaft 111 is not inclined with respect to the central axis O, the shaft 111 will not come into contact with the projection 145.

[0143] As shown in Figure 10, when the shaft 111 tilts with respect to the central axis O, accompanied by the tilting of the inner ring 10 relative to the outer ring 20 of the first bearing 1A, the shaft 111 can contact the inner circumferential surface 146 of the projection 145. When the shaft 111 is in contact with the restricting portion 146a of the inner circumferential surface 146 of the projection 145, the inclination between the outer ring 20 and the inner ring 10 of the first bearing 1A is less than or equal to the angular clearance. That is, the restricting portion 146a of the projection 145 contacts the shaft 111 during the process of being inserted into the first bearing 1A, thereby restricting the inner ring 10 of the first bearing 1A from tilting more than the angular clearance relative to the outer ring 20. In this embodiment, the restricting portion 146a extends continuously upward from the lower end of the inner circumferential surface 146 of the projection 145. Furthermore, the shaft 111 may not be able to contact the upper end of the inner circumferential surface 146 of the protruding portion 145 if the inclination between the outer ring 20 and the inner ring 10 is less than or equal to the square clearance. In this case, the upper end of the inner circumferential surface 146 of the protruding portion 145 is not included in the restricting portion 146a. However, the restricting portion 146a may include the upper end of the inner circumferential surface 146 of the protruding portion 145.

[0144] The lower end of the shaft 111 moves downward inside the projection 145 and is inserted into the second bearing 1B. As shown in Figure 11, when the shaft 111 approaches the second bearing 1B with the tapered surface 111a of the lower end of the shaft 111 tilted with respect to the central axis O, the tapered surface 111a of the lower end of the shaft 111 slides against the upper opening edge of the inner ring 10 of the second bearing 1B. The shaft 111 moves downward and slides the tapered surface 111a against the upper opening edge of the inner ring 10 of the second bearing 1B, thereby eliminating the tilt with respect to the central axis O and penetrating the second bearing 1B. This prevents the shaft 111 from excessively pressing the inner ring 10 of the second bearing 1B downward. Note that when the tapered surface 111a of the shaft 111 contacts the upper opening edge of the inner ring 10 of the second bearing 1B, the shaft 111 can contact the projection 145. This prevents the shaft 111 from tilting with respect to the central axis O to an angle where the tapered surface 111a of the shaft 111 does not contact the upper end opening edge of the inner ring 10 of the second bearing 1B. When the tapered surface 111a of the shaft 111 contacts the upper end opening edge of the inner ring 10 of the second bearing 1B, it is desirable that the restricting portion 146a of the inner circumferential surface 146 of the protrusion 145 contacts the shaft 111.

[0145] In the first method, the second bearing 1B may be attached to the sleeve 140A after the shaft 111 has been inserted through the sleeve 140A. Even in this case, the upper opening edge of the inner ring 10 of the upward-moving second bearing 1B slides against the tapered surface 111a of the shaft 111, thereby eliminating the inclination of the shaft 111 with respect to the central axis O as it passes through the second bearing 1B. This prevents the inner ring 10 of the second bearing 1B from being excessively pressed downward by the shaft 111.

[0146] A second method will be described. When the shaft 111 is inserted into the sleeve 140A, it passes inside the projection 145. The lower end of the shaft 111 moves downward inside the projection 145 toward the second bearing 1B. If the first bearing 1A is mounted in the sleeve 140A before the shaft 111 is inserted into the second bearing 1B, the projection 145, the shaft 111, and the first bearing 1A act in the same manner as in the first method. That is, when the first bearing 1A is mounted in the sleeve 140A, the restricting portion 146a of the projection 145 contacts the shaft 111, thereby restricting the inner ring 10 of the first bearing 1A from tilting more than the angular clearance relative to the outer ring 20. Furthermore, when the shaft 111 moves downward toward the second bearing 1B after the first bearing 1A is mounted on the sleeve 140A, the restricting portion 146a of the protruding portion 145 contacts the shaft 111, thereby restricting the inner ring 10 of the first bearing 1A from tilting more than the angular clearance relative to the outer ring 20.

[0147] On the other hand, if the shaft 111 is inserted into the second bearing 1B before the first bearing 1A is mounted on the sleeve 140A, the lower end of the shaft 111 may approach the second bearing 1B with the axis of the shaft 111 misaligned with the central axis O. Even if the axis of the shaft 111 is misaligned with the central axis O, the shaft 111 penetrates the second bearing 1B while eliminating the misalignment with the central axis O by sliding the tapered surface 111a of its lower end against the upper opening edge of the inner ring 10 of the second bearing 1B. This prevents the shaft 111 from excessively pressing the inner ring 10 of the second bearing 1B downwards. Furthermore, when the tapered surface 111a of the shaft 111 contacts the upper opening edge of the inner ring 10 of the second bearing 1B, the shaft 111 can contact the protrusion 145. This prevents the tip surface of the shaft 111 from contacting the inner ring 10 of the second bearing 1B and pressing it downwards.

[0148] As described above, the sleeve 140A includes a first outer ring support portion 143 that contacts the end face of the outer ring 20 of the first bearing 1A from below, and a projection portion 145 formed below the first outer ring support portion 143 and projecting radially inward from the first outer ring support portion 143. With this configuration, if the shaft 111 inserted through the inner ring 10 of the first bearing 1A is tilted with respect to the central axis O of the sleeve 140A, the shaft 111 can contact the projection portion 145, thereby preventing the shaft 111 from tilting further. Here, if the projection portion 145 is not provided on the sleeve 140A, the portion of the inner circumferential surface of the sleeve 140A that can contact the tilted shaft 111 is located radially outward from the inner circumferential edge of the first outer ring support portion 143, so the tilting of the shaft 111 cannot be sufficiently prevented. According to this embodiment, since the protrusion 145 protrudes radially inward from the first outer ring support portion 143, the tilting of the shaft 111 can be effectively restricted. This prevents the inner ring 10 of the first bearing 1A from tilting significantly relative to the outer ring 20, thereby preventing the formation of indentations from the rolling elements 30 on at least one of the inner ring 10 and the outer ring 20. Therefore, when assembling the fan motor 100 having the sleeve 140A, the formation of indentations on the raceway of the first bearing 1A can be suppressed, thereby preventing the generation of abnormal noise when the fan motor 100 rotates.

[0149] The protruding portion 145 has a restricting portion 146a that can contact the shaft 111 inserted through the inner ring 10 when the inclination between the outer ring 20 and inner ring 10 of the first bearing 1A is less than or equal to the corner clearance. With this configuration, the restricting portion 146a can restrict the shaft 111 from inclining beyond the corner clearance of the first bearing 1A. Therefore, when assembling the fan motor 100 having the sleeve 140A, it is possible to more reliably suppress the formation of indentations on at least one of the inner ring 10 and outer ring 20 of the first bearing 1A.

[0150] The first outer ring support portion 143 has an inner diameter larger than the outer diameter of the inner ring 10 of the first bearing 1A. With this configuration, it is possible to avoid the first outer ring support portion 143 contacting the inner ring 10 of the first bearing 1A. Therefore, it is possible to prevent the sleeve 140A from interfering with the rotation of the shaft 111.

[0151] The inner diameter of the projection 145 is less than or equal to the outer diameter of the inner ring 10. This configuration allows the projection 145 to be brought closer to the central axis O of the sleeve 140A while avoiding contact between the sleeve 140A and the inner ring 10 of the first bearing 1A. Therefore, the tilting of the shaft 111 can be more effectively restricted.

[0152] The sleeve 140A integrally includes the first outer ring receiving portion 143 and the protruding portion 145. This configuration makes it possible to form the sleeve 140A from a single component. Therefore, the manufacturing cost of the sleeve 140A can be reduced.

[0153] The lower end of the shaft 111 has a tapered surface 111a that narrows downwards. The protrusion 145 can contact the shaft 111 with the tapered surface 111a in contact with the opening edge of the inner ring 10 of the second bearing 1B. With this configuration, even if the shaft 111 is misaligned, such as tilting with respect to the central axis O of the sleeve 140A, when the shaft 111 is inserted into the second bearing 1B from above from the first bearing 1A side, the tapered surface 111a can still be brought into contact with the opening edge of the inner ring 10 of the second bearing 1B. This prevents the tip surface of the shaft 111 from abutting against the inner ring 10 of the second bearing 1B and applying excessive force to the inner ring 10. Therefore, it is possible to suppress the formation of indentations on at least one of the inner ring 10 and outer ring 20 of the second bearing 1B, thereby suppressing the generation of abnormal noise when the fan motor 100 rotates.

[0154] The fan motor 100 comprises the sleeve 140A described above and a shaft 111 inserted through the inner ring 10 of the first bearing 1A. This configuration makes it possible to suppress the generation of abnormal noise during rotation.

[0155] [Sixth Embodiment] Next, the sixth embodiment will be described with reference to Figure 12. The sixth embodiment differs from the fifth embodiment in that the first outer ring support portion 143 and the protruding portion 145 are formed from different materials. Other than what is described below, the configuration is the same as that of the first embodiment.

[0156] Figure 12 is a longitudinal cross-sectional view of the fan motor according to the sixth embodiment, and is an enlarged view showing the area around the sleeve. As shown in Figure 12, the sleeve 140B comprises a cylindrical sleeve body 140a and a receiving member 140b positioned inside the sleeve body 140a, and by combining the sleeve body 140a and the receiving member 140b, it exhibits a shape similar to the sleeve 140 of the fifth embodiment. The sleeve body 140a forms at least the outer circumferential surface, both end faces, and protrusions 145 of the sleeve 140B. The sleeve body 140a has a first retaining portion 141. The receiving member 140b extends in an annular or arc shape coaxial with the sleeve body 140a. A pair of receiving members 140b are provided, one above the other. For example, the receiving member 140b is a washer or a C-ring. The upper receiving member 140b is inserted from above into the first holding portion 141 of the sleeve body 140a and overlaps the upper end surface 147 of the protruding portion 145 from above, thereby forming the first outer ring receiving portion 143 of the sleeve 140B. The lower receiving member 140b is inserted from below into the second holding portion 142 of the sleeve body 140a and overlaps the lower end surface 148 of the protruding portion 145 from below, thereby forming the second outer ring receiving portion 144 of the sleeve 140B. The sleeve body 140a is made of the above-mentioned synthetic resin or metal material. The receiving member 140b is made of a hard material such as the above-mentioned synthetic resin or metal material.

[0157] This embodiment provides the same effects as the fifth embodiment. In addition, this embodiment provides the following effects. The sleeve 140B comprises a sleeve body 140a having a protrusion 145, and a receiving member 140b disposed inside the sleeve body 140a, overlapping the protrusion 145 from above, and forming a first outer ring receiving portion 143. With this configuration, the sleeve body 140a can be made into a relatively simple shape with few steps, resulting in a sleeve 140B with excellent productivity. In particular, when the sleeve body 140a is made of metal, complex processing can be avoided when forming the sleeve body 140a, making it a suitable configuration that provides the above effects.

[0158] [Seventh Embodiment] Next, the seventh embodiment will be described with reference to Figure 13. In the seventh embodiment, the position of the lower edge of the inner circumferential surface 146C of the protruding portion 145C is different from that of the fifth embodiment. Other than what is described below, the configuration is the same as that of the fifth embodiment.

[0159] Figure 13 is a longitudinal cross-sectional view of the fan motor according to the seventh embodiment, and is an enlarged view showing the area around the sleeve. As shown in Figure 13, the lower end edge of the inner circumferential surface 146C of the projection 145C is located higher compared to the fifth embodiment. For example, the axial formation range of the projection 145C does not include the center positions of the first bearing 1A and the second bearing 1B. In this embodiment, the lower end edge of the inner circumferential surface 146C of the projection 145C is separated from the second bearing 1B so that the projection 145C and the shaft 111 do not come into contact with each other when the tapered surface 111a of the shaft 111 contacts the upper end opening edge of the inner ring 10 of the second bearing 1B. Even with this configuration, the same effects as in the fifth embodiment are achieved by including the restricting portion 146a on the inner circumferential surface 146C of the projection 145C.

[0160] [Eighth Embodiment] Next, an eighth embodiment will be described with reference to Figure 14. In the eighth embodiment, the configuration of the upper end surface 147D of the protruding portion 145D differs from that of the fifth embodiment. Other configurations are the same as those described below in the fifth embodiment.

[0161] Figure 14 is a longitudinal cross-sectional view of the fan motor according to the eighth embodiment, and is an enlarged view showing the area around the sleeve. As shown in Figure 14, the upper end surface 147D of the projection 145D connects the upper edge of the inner circumferential surface 146 of the projection 145D to the inner circumferential surface of the first outer ring support portion 143. The upper end surface 147D extends continuously between the upper edge of the inner circumferential surface 146 of the projection 145D and the inner circumferential surface of the first outer ring support portion 143 on the longitudinal cross-section of the sleeve 140D. In the illustrated example, the upper end surface 147D is a conical surface that extends linearly between the upper edge of the inner circumferential surface 146 of the projection 145D and the inner circumferential surface of the first outer ring support portion 143 on the longitudinal cross-section of the sleeve 140D. However, the upper end surface 147D may be curved on the longitudinal cross-section of the sleeve 140D. The upper end surface 147D may be able to contact the inner ring 10, which is inclined at an angle of less than or equal to the angular clearance with respect to the outer ring 20 of the first bearing 1A, from below, or it may not be able to contact the inner ring 10, which is inclined at an angle of less than or equal to the outer ring 20 of the first bearing 1A. Even with such a configuration, the protrusion 145D of the sleeve 140D includes the restricting portion 146a, thereby achieving the same effect as in the fifth embodiment.

[0162] 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, the above embodiment illustrates a sleeve provided on a fan motor as a rotating device, but the present invention is applicable to sleeves provided on rotating devices in general.

[0163] In the embodiments described above, the entire sleeve is formed from an electrically insulating synthetic resin, but the configuration is not limited to this. It is sufficient that the member supporting the sleeve in the rotating equipment and the bearing are electrically insulated. For example, only a part of the sleeve may be made of synthetic resin, such as forming only the contact portion with the bearing from synthetic resin.

[0164] In the embodiments described above, the recesses in each holding portion of the sleeve extend continuously over the entire circumferential direction, but the configuration is not limited to this. That is, the recesses may be provided only in a portion of the circumferential direction.

[0165] In the embodiments described above, the method of fixing the pair of bearings to the sleeve is press-fitting or adhesive bonding, but is not limited to these. One bearing may be fixed to the sleeve by press-fitting, and the other bearing by adhesive bonding.

[0166] In each of the above embodiments, the outer ring 20 of the second bearing 1B is not pre-pressurized. However, as shown in Figure 15, a biasing member 150, such as a coil spring, may be placed inside the second retaining portion 142, interposed between the outer ring 20 and the protruding portion 145 to press the outer ring 20 downward. In this case, the lower end surface of the biasing member 150 may be the second outer ring receiving portion 144.

[0167] In the above embodiment, the protrusion 145 extends continuously over its entire circumferential direction, but the configuration is not limited to this. For example, the restricting portion of the protrusion may be provided intermittently in the circumferential direction.

[0168] In the above embodiment, the restricting portion 146a of the protrusion 145 is provided on the cylindrical inner circumferential surface 146, but the configuration is not limited to this. For example, the restricting portion may be formed in the shape of a cone. Alternatively, the protrusion may have a shape that tapers radially inward on the longitudinal cross-section of the sleeve, and the restricting portion may be provided at the radially inward end of the protrusion and may not have substantially any size in the axial direction.

[0169] In the above embodiment, the dimensions of each part of the bearing mounted in the sleeve are not particularly limited, but the bearing mounted in the sleeve may be limited to radial bearings described in ISO or JIS standards. In this case, the main dimensions of the radial bearing are specified in ISO 15 or JIS B 1512-1. The angular clearance of the bearing may also be derived from the dimensions of each part of the bearing, for example, by referring to "Introduction to Ball Bearing Design Calculation" (Nikkan Kogyo Shimbun, September 2011, pp. 22-32).

[0170] Furthermore, without departing from the spirit of the present invention, the components in the above embodiments may be replaced with well-known components as appropriate, and the above embodiments may be combined as appropriate. For example, in the above embodiments, the configuration in which the sleeve fixes the bearing by press-fitting may be changed to a configuration in which the bearing is fixed by adhesive. Also, in the above embodiments, the configuration in which the sleeve fixes the bearing by adhesive may be changed to a configuration in which the bearing is fixed by press-fitting. In addition, the shape and position of the recess of the holding part in each of the above embodiments may be combined with other embodiments as appropriate. Also, in the above embodiments, the shape and position of the recess of the holding part may be changed as appropriate in the embodiment in which the sleeve has a protruding part. [Explanation of symbols]

[0171] 1…Rolling bearings 1A...First bearing (rolling bearing) 1B...Second bearing (rolling bearing, other rolling bearings) 10…Inner circle 20…Outer ring 100... Fan motor (rotating equipment) 101... Biasing member 111... Shaft 111a... Tapered surface 140, 140A, 140B, 140C, 140D, 140E, 240, 340, 440… Sleeves 140a... Sleeve body 140b...Support member 141,241,341,441...First holding part (holding part) 141a, 241a, 341a, 441a... First recess (recess) 141c, 341c…Outer surface (slanted part) 142,242,342,442...Second holding part (holding part) 142a, 242a, 342a, 442a... Second recess (recess) 143...First outer ring support (outer ring support) 144...Second outer ring support section (outer ring support section) 145,145C,145D…Protrusion 146a…Regulatory Department 241c, 242c...first half (slanted part) P...Parting line

Claims

1. A cylindrical sleeve on which a rolling bearing is mounted, A retaining portion that holds the outer surface of the rolling bearing, The outer ring support portion contacts the end face of the outer ring of the rolling bearing from the axial inner side, Equipped with, The retaining portion has a recess that opens radially inward toward the outer circumferential surface, A sleeve formed of a synthetic resin that has electrical insulating properties in at least part of it.

2. In the sleeve according to claim 1, On the inner circumferential surface, at a position opposite the retaining portion to the outer ring receiving portion, there is a parting line formed during the molding of the sleeve. sleeve.

3. In the sleeve according to claim 1, Potassium titanate whiskers are added to the aforementioned synthetic resin. sleeve.

4. In the sleeve according to claim 1, The recess extends continuously over the entire circumferential direction. sleeve.

5. In the sleeve according to claim 1, The recess has an inclined portion whose inner diameter decreases as it moves outward in the axial direction. sleeve.

6. In the sleeve according to claim 1, The retaining portion has a press-fit portion whose inner diameter is smaller than the outer diameter of the rolling bearing. sleeve.

7. In the sleeve according to claim 1, The recess is positioned at an axial distance from the outer ring support portion. sleeve.

8. In the sleeve according to claim 1, The entire structure is formed from the aforementioned synthetic resin. sleeve.

9. In the sleeve according to claim 1, A sleeve further comprising a projection formed axially inward from the outer ring support portion and projecting radially inward from the outer ring support portion.

10. In the sleeve according to claim 9, The aforementioned protrusion has a restricting portion that can contact the shaft inserted through the inner ring when the inclination between the outer ring and inner ring of the rolling bearing is less than or equal to the angular clearance. sleeve.

11. In the sleeve according to claim 9, The outer ring support portion has an inner diameter larger than the outer diameter of the inner ring of the rolling bearing. sleeve.

12. In the sleeve according to claim 11, The inner diameter of the protrusion is less than or equal to the outer diameter of the inner ring. sleeve.

13. In the sleeve according to claim 9, The outer ring receiving portion and the protruding portion are integrally formed, sleeve.

14. In the sleeve according to claim 9, The sleeve body having the aforementioned protrusion, A receiving member is positioned inside the sleeve body and overlaps the protruding portion from the other side in the axial direction, forming the outer ring receiving portion. A sleeve equipped with [a specific feature / feature].

15. In the sleeve according to claim 10, Another rolling bearing is held at a position opposite to the rolling bearing relative to the protrusion, The tip of the aforementioned shaft has a tapered surface that narrows towards the end. The aforementioned protrusion is capable of contacting the shaft while the tapered surface is in contact with the opening edge of the inner ring of the other rolling bearing. sleeve.

16. The sleeve according to claim 1, The rolling bearing mounted inside the sleeve, A sleeve with a bearing equipped with the following features.

17. In the bearing-equipped sleeve according to claim 16, The rolling bearing is bonded to the sleeve, Adhesive is placed in the recess. Sleeve with bearing.

18. A sleeve with a bearing according to claim 16, A shaft inserted through the inner ring of the aforementioned rolling bearing, A rotating device equipped with the following features.

19. The sleeve according to claim 6, The rolling bearing mounted inside the sleeve, A shaft inserted through the inner ring of the aforementioned rolling bearing, A biasing member that biases the inner ring inward in the axial direction, Equipped with, The press-fit portion is located outward in the axial direction from the recess. Rotating machinery.

20. In the rotating apparatus according to claim 18 or claim 19, The aforementioned shaft is the rotation axis of the motor, The sleeve is formed integrally with the motor chassis from synthetic resin. Rotating machinery.

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