Sintered oil-retaining bearing and motor

Abstract

The sintered oil-retaining bearing is provided with a bearing cylinder part and a groove group. The bearing cylinder part is composed of a porous sintered body capable of being impregnated with lubricating oil, and extends along the central axis. The groove group has a plurality of first grooves. The plurality of first grooves extend at least in the axial direction of the central shaft and are arranged in the circumferential direction. A plurality of groove groups are arranged on the radial outer surface of the bearing cylinder and are arranged in the circumferential direction. The circumferential interval between the first grooves adjacent in the circumferential direction in each groove group is smaller than the circumferential interval between the groove groups adjacent in the circumferential direction. The motor is provided with the sintered oil-retaining bearing, a shaft, a rotor and a bearing retainer. The shaft extends along a central axis about which the rotor is rotatable with the shaft. The bearing holder rotatably supports the shaft via the sintered oil-retaining bearing. The bearing cage has a cage cylinder portion and a plurality of ribs. The holder cylinder portion extends in the axial direction and surrounds and holds the sintered oil-retaining bearing. The plurality of ribs protrude radially inward from the radially inner side surface of the cage cylinder section and are arranged in the circumferential direction.

Description

Technical Field

[0001] The invention relates to a sintered oil-containing bearing and a motor. Background Art

[0002] Conventionally, sliding bearings are known that are arranged within the interior space of a bearing retainer and rotatably support a rod-shaped shaft. For example, these sliding bearings have a cylindrical inner member. Long grooves extending in the axial direction are arranged on the outer surface of the inner member at equal intervals in the circumferential direction (see Japanese Patent Application Laid-Open No. 60-237223).

[0003] As one type of sliding bearing, a porous, cylindrical, oil-impregnated sintered bearing formed by sintering metal powder is known. The oil-impregnated sintered bearing is used in a state where lubricating oil is impregnated into the porous body.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 60-237223 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In Japanese Patent Application Laid-Open No. 60-237223, the circumferential ends of the long grooves arranged on the outer surface of the sliding bearing may sometimes collide with the inner circumferential surface of the bearing retainer. In this case, the sliding performance of the sliding bearing may be reduced, and the life of the sliding bearing may be affected by wear and other factors. Therefore, it is preferable to expand the circumferential range of the outer surface of the sliding bearing without long grooves. This tendency is particularly significant when the cylindrical inner member is a porous sintered body. In addition, when the long grooves are arranged at equal intervals in the circumferential direction as in Japanese Patent Application Laid-Open No. 60-237223, it is difficult to expand the circumferential range of the outer surface without long grooves.

[0009] An object of the present invention is to extend the life of a sintered oil-impregnated bearing while improving the sliding properties of the sintered oil-impregnated bearing.

[0010] Solutions to Problems

[0011] An exemplary oil-impregnated sintered bearing according to the present invention comprises a bearing cylinder and a slot group. The bearing cylinder is formed of a porous sintered body capable of being impregnated with lubricating oil and extends along a central axis. The slot group comprises a plurality of first slots. These first slots extend at least in the axial direction of the central axis and are arranged circumferentially. A plurality of slot groups are disposed on the radially outer surface of the bearing cylinder and are arranged circumferentially. The circumferential spacing between circumferentially adjacent first slots in each slot group is smaller than the circumferential spacing between circumferentially adjacent slot groups.

[0012] An exemplary motor according to the present invention includes the aforementioned sintered oil-impregnated bearing, a shaft, a rotor, and a bearing retainer. The shaft extends along the central axis. The rotor is rotatable about the central axis together with the shaft. The bearing retainer rotatably supports the shaft via the sintered oil-impregnated bearing. The bearing retainer includes a retainer barrel and a plurality of ribs. The retainer barrel extends axially and surrounds and retains the sintered oil-impregnated bearing. The plurality of ribs protrude radially inward from the radially inner side of the retainer barrel and are arranged circumferentially.

[0013] Effects of the Invention

[0014] According to the exemplary sintered oil-impregnated bearing and motor of the present invention, the life of the sintered oil-impregnated bearing can be prolonged while improving the sliding properties of the sintered oil-impregnated bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic cross-sectional view showing a structural example of a motor according to an embodiment.

[0016] Figure 2 yes Figure 1 A cross-sectional view of the motor at the double-dashed line II.

[0017] Figure 3 This is an external view showing a structural example of an oil-impregnated sintered bearing according to an embodiment. DETAILED DESCRIPTION

[0018] Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings.

[0019] In this specification, the direction parallel to the central axis CA of the motor 100 is referred to as the "axial direction." The direction from the bracket 104 (described later) toward the rotor 102 in the axial direction is referred to as the "one axial direction," and the direction from the rotor 102 toward the bracket 104 is referred to as the "other axial direction." Furthermore, in predetermined components, the direction from the end toward the center in the axial direction is referred to as the "axially inward direction," and the direction from the center toward the end in the axial direction is referred to as the "axially outward direction."

[0020] The direction perpendicular to the central axis CA is referred to as the "radial direction," and the direction of rotation about the central axis CA is referred to as the "circumferential direction." The direction toward the central axis CA in the radial direction is referred to as the "radially inward direction," and the direction away from the central axis CA is referred to as the "radially outward direction."

[0021] In this specification, the term "annular" includes not only shapes that are seamlessly and continuously connected throughout the entire circumference centered on the central axis CA, but also shapes that have one or more gaps in a portion of the entire area centered on the central axis CA. Furthermore, it includes shapes that describe a closed curve centered on the central axis CA on a curved surface intersecting the central axis CA.

[0022] Furthermore, in the positional relationship between any one of an orientation, a line, and a plane and any other, "parallel" includes not only a state in which the two do not intersect at all regardless of their extension, but also a state in which they are substantially parallel. Furthermore, "perpendicular" and "orthogonal" include not only a state in which the two intersect at 90 degrees, but also a state in which they are substantially perpendicular and a state in which they are substantially orthogonal, respectively. That is, "parallel," "perpendicular," and "orthogonal" each include a state in which the positional relationship between the two has an angular deviation to the extent that does not deviate from the gist of the present invention.

[0023] In addition, these are for explanation only and are not intended to limit actual positional relationships, directions, names, etc.

[0024] <1. Motor 100>

[0025] Figure 1 1 is a schematic cross-sectional view showing a configuration example of the motor 100 according to the embodiment. Figure 2 yes Figure 1 This is an enlarged view of the cross section of the motor 100 at the double-dashed line II. Figure 1 A hypothetical cross-sectional structure of the motor 100 cut along a plane including the central axis CA is schematically shown. Figure 2 Is to use include Figure 1 FIG. 1 is an enlarged view of a portion of an imaginary cross-sectional structure of the motor 100 cut along a plane perpendicular to the axial direction and along a two-dot chain line II.

[0026] The motor 100 of this embodiment is mounted on an air blowing device such as a centrifugal fan, for example. However, this example does not limit the use of the motor 100.

[0027] like Figure 1 As shown, the motor 100 includes a shaft 101 , a rotor 102 , a stator 103 , a bracket 104 , a base plate 105 , an oil-impregnated sintered bearing 1 , and a bearing holder 2 .

[0028] <1-1. Axis 101>

[0029] The shaft 101 extends along the central axis CA. As described above, the motor 100 includes the shaft 101. The shaft 101 is rotatably supported relative to the bearing holder 2 via the sintered oil-impregnated bearing 1. Furthermore, the motor 100 includes a structure that prevents the shaft 101 and the sintered oil-impregnated bearing 1 from coming off the bearing holder 2. However, this structure is not in the spirit of the present invention, and therefore its illustration and description will be omitted.

[0030] <1-2. Rotor 102>

[0031] The rotor 102 is rotatable together with the shaft 101 about the central axis CA. As described above, the motor 100 includes the rotor 102. The rotor 102 is in the shape of a cylinder with a cover that surrounds the shaft 101 and is connected to one axial end of the shaft 101. Specifically, the rotor 102 includes a plate portion and a cylinder portion. The plate portion extends radially from one axial end of the shaft 101. The cylinder portion extends axially from the radially outer end of the plate portion to the other end and surrounds the shaft 101. The cylinder portion is provided with magnets with different magnetic poles arranged alternately in the circumferential direction, a yoke, and the like.

[0032] <1-3. Stator 103>

[0033] The stator 103 is supported by a bearing holder 2 extending in the axial direction and is radially opposed to the magnets arranged on the cylindrical portion of the rotor 102. For example, the stator 103 has a stator core and a plurality of coils. The stator core is an annular magnetic body fixed to the radially outer side of the bearing holder 2. The coil is a component in which a conductive wire is arranged on the stator core through an insulator. In addition, the conductive wire is, for example, an enameled copper wire, a metal wire covered by an insulating component, etc., and is formed by being wound around the stator core. When a driving current is supplied to each coil, the stator 103 is excited and drives the rotor 102.

[0034] <1-4. Bracket 104>

[0035] The bracket 104 is in the shape of a plate that expands radially from the central axis CA, and is disposed axially on the other side of the stator 103. The bracket 104 supports the bearing holder 2.

[0036] <1-5.Substrate 105>

[0037] The substrate 105 is arranged axially between the stator 103 and the bracket 104 and is supported by the bracket 104. The substrate 105 carries the drive circuit of the stator 103 and is electrically connected to the coils of the stator 103. The substrate 105 is also electrically connected to external connection lines extending outside the motor 100, and can be connected to a power supply, control devices, and equipment arranged outside the motor 100 via the external connection lines.

[0038] <1-6. Sintered oil-impregnated bearing 1>

[0039] Next, refer to Figures 1 to 3 The oil-impregnated sintered bearing 1 will be described. Figure 3 1 is an external view showing a structural example of a sintered oil-impregnated bearing 1 according to an embodiment. Figure 3 In order to make the drawings easier to see, the lubricating oil F is omitted from the drawings. As described above, the motor 100 includes the oil-impregnated sintered bearing 1 .

[0040] The sintered oil-impregnated bearing 1 is a sliding bearing constructed by impregnating a cylindrical, porous metal body made by sintering powdered copper, iron, or other metal alloys with lubricating oil F. To improve wear resistance, the sintered oil-impregnated bearing 1 is preferably made of a relatively soft metal or alloy. The lubricating oil F impregnated within the sintered oil-impregnated bearing 1 circulates inside and outside the bearing, lubricating its surfaces. The sintered oil-impregnated bearing 1 is positioned within the bearing retainer 2. A shaft 101 is inserted into the cylindrical sintered oil-impregnated bearing 1. The sintered oil-impregnated bearing 1 contacts the radially outer surface of the shaft 101 and the radially inner surface of the bearing retainer 2 via the lubricating oil F that leaks from the bearing. The circulating lubricating oil F allows the sintered oil-impregnated bearing 1 to slide smoothly relative to the shaft 101 and the bearing retainer 2.

[0041] The oil-impregnated sintered bearing 1 includes a bearing cylindrical portion 11 , a groove group 12 including first grooves 121 , second grooves 13 , and a chamfered portion 14 .

[0042] The bearing cylindrical portion 11 is composed of a porous sintered body that can be impregnated with lubricating oil F and has a cylindrical shape extending along the central axis CA. As described above, the oil-impregnated sintered bearing 1 includes a bearing cylindrical portion 11. In this embodiment, the bearing cylindrical portion 11 has an annular tapered surface 111 along the axial end of its radially inner side surface. The tapered surface 111 is arranged between the axial end surface and the radially inner side surface of the bearing cylindrical portion 11, tilting radially inward as it moves axially inward, and extends circumferentially. The arrangement of the tapered surface 111 allows lubricating oil F that leaks onto the axial end surface and tapered surface 111 of the bearing cylindrical portion 11 to efficiently flow between the radially inner side surface of the bearing cylindrical portion 11 and the shaft 101. Furthermore, in this embodiment, the tapered surface 111 is arranged at both axial ends of the bearing cylindrical portion 11. However, the above example does not preclude configurations in which the tapered surface 111 is arranged only at one axial end of the bearing cylindrical portion 11, nor does it preclude configurations in which the tapered surface 111 is omitted (i.e., not arranged at both axial ends of the bearing cylindrical portion 11).

[0043] In addition, the slot group 12 has a plurality of first slots. Each first slot 121 extends at least in the axial direction of the central axis CA and is arranged in the circumferential direction. As described above, the sintered oil-impregnated bearing 1 also has a slot group 12. In addition, the first slots 121 are arranged in the circumferential direction. Figure 3The first groove 121 extends straight in the axial direction. However, this is not limiting. The first groove 121 may extend circumferentially with an inclination as it moves from one axial direction to the other, or may extend in a curved shape. Furthermore, the cross-sectional shape of the first groove 121 as viewed from the direction in which the first groove 121 extends (e.g., the axial direction) is semicircular in this embodiment. However, this is not limiting and may be a shape other than a semicircular shape, such as an m-sided shape (m is an integer greater than or equal to 3).

[0044] By disposing a plurality of first grooves 121 extending at least in the axial direction on the radially outer surface of the bearing cylindrical portion 11, the lubricating oil F that axially squeezes out from between the radially outer surface of the bearing cylindrical portion 11 and the radially inner surface of the bearing retainer 2 can be reduced when the sintered oil-impregnated bearing 1 is inserted into the bearing retainer 2. Furthermore, the lubricating oil F can be accumulated within the first grooves 121. This lubricating oil F can, for example, leak from the porous interior of the bearing cylindrical portion 11 to surfaces (e.g., the radially outer and inner surfaces, and axial end faces), flow between the bearing cylindrical portion 11 and the shaft 101, and between the bearing cylindrical portion 11 and the bearing retainer 2, and penetrate into the interior of the bearing cylindrical portion 11. The sintered oil-impregnated bearing 1 can retain a large amount of lubricating oil F circulated in this manner. Consequently, wear of the bearing cylindrical portion 11 can be suppressed when the sintered oil-impregnated bearing 1 slides.

[0045] Preferably, if Figure 3 As shown, one axial end of the first groove 121 reaches one axial end of the radially outer surface of the bearing cylindrical portion 11 and opens on one axial side. Furthermore, the other axial end of the first groove 121 reaches the other axial end of the radially outer surface of the bearing cylindrical portion 11 and opens on the other axial side. This facilitates the flow of lubricating oil F into the first groove 121. However, this example does not exclude a configuration in which at least one axial end of at least one of the first grooves 121 does not reach the axial end of the radially outer surface of the bearing cylindrical portion 11.

[0046] Furthermore, it is preferred that both circumferential ends of the first groove 121 be C-chamfered or R-chamfered. That is, no pin corners (sharp corners) are provided at either circumferential end of the first groove 121. This prevents or inhibits the circumferential ends of the first groove 121 from colliding with the radially inner surface of the bearing retainer 2, even when the sintered oil-impregnated bearing 1 rotates circumferentially. Consequently, the sliding properties of the sintered oil-impregnated bearing 1 relative to the radially inner surface of the bearing retainer 2 can be improved. However, this example does not exclude the possibility that at least one circumferential end of at least one first groove 121 is not C-chamfered or R-chamfered.

[0047] In addition, a plurality of groove groups 12 are arranged on the radially outer side of the bearing cylinder portion 11 and arranged in the circumferential direction. Figure 2As shown, the circumferential spacing R1a between circumferentially adjacent first grooves 121 in each groove group 12 is smaller than the circumferential spacing R1b between circumferentially adjacent groove groups 12. This further increases the area of ​​the radially outer surface of the bearing cylindrical portion 11 where no groove groups 12 are arranged. Consequently, the circumferential range of contact between this area and, for example, the bearing retainer 2 can be further expanded, enabling the bearing cylindrical portion 11 to slide stably and smoothly relative to the bearing retainer 2.

[0048] Therefore, the life of the oil-impregnated sintered bearing 1 can be prolonged while improving the sliding properties of the oil-impregnated sintered bearing 1 .

[0049] Preferably, the plurality of slot groups 12 include a pair of slot groups 12a and 12b disposed opposite each other across the central axis CA when viewed axially. This facilitates further increasing the circumferential spacing between circumferentially adjacent slot groups 12. Consequently, the bearing cylinder 11 can slide stably and smoothly relative to the bearing retainer 2. Furthermore, this example does not exclude configurations in which the plurality of slot groups 12 do not include the pair of slot groups 12a and 12b described above.

[0050] Next, the second groove 13 is arranged on the axial end surface of the bearing cylinder 11, and is recessed in the axial direction and extends at least in the radial direction. As described above, the sintered oil-impregnated bearing 1 also has the second groove 13. In addition, the second groove 13 is Figure 3 The second groove 13 extends straight in the radial direction. However, this is not limiting. The second groove 13 may extend circumferentially with an inclination as it moves from the radially inner side toward the radially outer side, or may extend in a curved shape. Furthermore, the cross-sectional shape of the second groove 13 as viewed in the direction in which the second groove 13 extends (e.g., the radial direction) is triangular in this embodiment. However, this is not limiting. Shapes other than triangular are also possible, such as a semicircular shape or an M-sided shape (M being an integer greater than or equal to 4).

[0051] In this embodiment, the second grooves 13 are arranged on both axial end surfaces of the bearing cylindrical portion 11. Furthermore, four second grooves 13 are arranged circumferentially on each axial end surface. However, this is not limiting; the second grooves 13 may be arranged on only one axial end surface of the bearing cylindrical portion 11. Furthermore, the number of second grooves 13 arranged on the axial end surface may be single or multiple, other than four.

[0052] Preferably, the circumferential range R2 where at least one second groove 13 is arranged overlaps with the circumferential range R1c where any one first groove 121 is arranged. Figure 3 In the example shown in FIG, the circumferential range R1c overlaps with the entire circumferential range R2. However, the present invention is not limited to this example, and the circumferential range R1c may overlap with a portion of the circumferential range R2.

[0053] In addition, Figure 3In the example, only a portion (two of four) of the second grooves 13 have their circumferential range R2 overlapped with the circumferential range R1c of the first groove 121. This example is not limiting, and the circumferential range R2 of all the second grooves 13 may overlap with the circumferential range R1c of the first groove 121.

[0054] Since the circumferential range R2 of the second groove 13 overlaps the circumferential range R1c of the first groove 121, the lubricating oil F flowing out from the radially inner side of the bearing cylindrical portion 11 toward the axial end surface can easily flow toward the first groove 121, where the circumferential range R1c overlaps with the second groove 13, and is easily accumulated in the first groove 121. As a result, the lubricating oil F is easily circulated, further improving the sliding performance and extending the service life of the oil-impregnated sintered bearing 1.

[0055] It is further preferred that the circumferential width R2 of at least one second groove 13 be less than the circumferential width R1c of any of the aforementioned first grooves 121. This increases the amount of lubricating oil F flowing from the second grooves 13 into the first grooves 121. In other words, the amount of lubricating oil F that does not flow from the second grooves 13 to the first grooves 121 can be reduced. Consequently, the lubricating oil F can efficiently flow from the second grooves 13 to the first grooves 121.

[0056] However, the above example does not exclude a configuration in which the circumferential extents R2 of all second grooves 13 do not overlap with the circumferential extent R1c of any first groove 121, nor does it exclude a configuration in which R2>R1c in at least one second groove 13. Alternatively, the above example does not exclude a configuration in which all second grooves 13 are omitted.

[0057] Next, the chamfered portion 14 is arranged between the radially outer side surface and the axial end surface of the bearing cylindrical portion 11, extending circumferentially in a direction obliquely intersecting the axial and radial directions. As described above, the sintered oil-impregnated bearing 1 further includes the chamfered portion 14. In other words, the chamfered portion 14 is arranged so as to tilt radially outward as it moves axially inward. Furthermore, in this embodiment, the chamfered portion 14 tilts straight radially outward as it moves axially inward. However, this is not limiting; the chamfered portion 14 may also be a curved surface that protrudes axially and radially outward, or a curved surface that is recessed axially and radially inward.

[0058] The arrangement of the chamfered portions 14 allows lubricating oil F that leaks out of the axial end surface of the bearing cylindrical portion 11 and the chamfered portions 14 to efficiently flow between the radially inner surface of the bearing cylindrical portion 11 and the radially inner surface of the bearing retainer 2. Furthermore, in this embodiment, the chamfered portions 14 are arranged at both axial end portions of the bearing cylindrical portion 11.

[0059] Preferably, at least one of the axial widths L1 and L2 and the radial widths W1 and W2 of the chamfered portion 14 is equal to or greater than half the inner diameter W0 of the bearing cylindrical portion 11 (see Figure 3). That is, at least one of the axial width L1 and the radial width W1 of the chamfered portion 14 on one axial side is equal to or greater than half the inner diameter W0 of the bearing cylindrical portion 11. Furthermore, at least one of the axial width L2 and the radial width W2 of the chamfered portion 14 on the other axial side is equal to or greater than half the inner diameter W0 of the bearing cylindrical portion 11.

[0060] By setting L1>(W0 / 2) and L2>(W0 / 2), the axial length of the chamfered portion 14 can be increased. Therefore, the lubricating oil F flowing radially outward from the axial end surface of the bearing cylinder portion 11 along the chamfered portion 14 can be easily directed axially inward.

[0061] Furthermore, by setting W1>(W0 / 2) and W2>(W0 / 2), the radial width of the axial end surface of the bearing cylindrical portion 11 can be further reduced. Consequently, the distance over which the lubricating oil F flows radially outward on the axial end surface of the bearing cylindrical portion 11 can be further shortened. Consequently, the lubricating oil F flowing from the radially inner surface of the bearing cylindrical portion 11 toward the axial end surface and the lubricating oil F leaking from the interior of the bearing cylindrical portion 11 toward the axial end surface can be more quickly directed to the chamfered portion 14. In other words, this lubricating oil F is more easily directed toward the radially outer surface of the bearing cylindrical portion 11 and toward the axial end surface.

[0062] Therefore, the oil-impregnated sintered bearing 1 can easily retain the lubricating oil F.

[0063] Furthermore, when conventional sintered metals are used as sliding bearings, for example, when operating the motor 100 in a low-temperature environment of approximately -40°C, the metal sintered metal may deform, potentially preventing the shaft 101 from rotating. In contrast, in the sintered oil-impregnated bearing 1 of this embodiment, by setting at least one of the axial widths L1, L2 and radial widths W1, W2 of the chamfered portion 14 to be at least half the inner diameter W0 of the bearing cylindrical portion 11, the dimensions of the chamfered portion 14 (e.g., the axial widths L1, L2, and the radial widths W1, W2) can be increased. This effectively prevents deformation of the bearing cylindrical portion 11 in low-temperature environments. Consequently, the shaft 101 can rotate satisfactorily even in low-temperature environments.

[0064] More preferably, the axial widths L1 and L2 of the chamfered portion 14 are greater than the radial widths W1 and W2 of the chamfered portion 14 . Specifically, the axial width L1 of the chamfered portion 14 on one axial side is greater than the radial width W1 of the chamfered portion 14 . The axial width L2 of the chamfered portion 14 on the other axial side is greater than the radial width W2 of the chamfered portion 14 . This further facilitates the flow of lubricating oil F flowing radially outward along the chamfered portion 14 toward the axial inward. Consequently, the oil-impregnated sintered bearing 1 further facilitates the retention of lubricating oil F. However, this example does not exclude configurations where L1 ≤ W1 or L2 ≤ W2.

[0065] The above examples do not exclude a configuration in which the chamfered portion 14 is disposed only at one axial end of the bearing tube portion 11 , nor do they exclude a configuration in which the chamfered portion 14 is omitted (i.e., not disposed at both axial ends of the bearing tube portion 11 ).

[0066] <1-7. Bearing retainer 2>

[0067] Next, refer to Figure 1 and Figure 2 The bearing holder 2 will be described. As described above, the motor 100 includes the bearing holder 2. The bearing holder 2 rotatably supports the shaft 101 via the oil-impregnated sintered bearing 1.

[0068] The bearing retainer 2 includes a retainer tube 21 and multiple ribs 22. The retainer tube 21 extends axially, surrounding and retaining the sintered oil-impregnated bearing 1. Multiple ribs 22 project radially inward from the radially inner side of the retainer tube 21 and are arranged circumferentially. Each rib 22 extends circumferentially and at least in the axial direction. In this embodiment, the ribs 22 extend straight in the axial direction. However, this is not limiting; the ribs 22 may extend circumferentially with an inclination as they move axially toward the other direction, or may extend in a curved pattern. Furthermore, the multiple ribs 22 may be arranged at equal or varying intervals circumferentially. This allows lubricating oil F to be stored between adjacent ribs 22 along the circumferential direction between the sintered oil-impregnated bearing 1 and the bearing retainer 2. This facilitates the retention of the lubricating oil F, further improving the sliding properties and life of the sintered oil-impregnated bearing 1.

[0069] Preferably, at least a portion of the ribs 22 are arranged circumferentially with n-fold symmetry (n is an integer greater than or equal to 3) about the central axis CA. This allows the sintered oil-impregnated bearing 1 to contact a portion of the ribs 22 via the lubricating oil F within at least three locations arranged at equal intervals. This effectively suppresses or prevents displacement between the central axis CA of the sintered oil-impregnated bearing 1 and the bearing retainer 2. Consequently, the bearing retainer 2 can stably retain the sintered oil-impregnated bearing 1. However, this example does not preclude the possibility that at least a portion of the ribs 22 are not arranged in this n-fold symmetry. For example, all ribs 22 may be arranged circumferentially at varying intervals.

[0070] Furthermore, it is preferred that both circumferential ends of the radially inner end of the rib 22 be C-chamfered or R-chamfered. That is, no pin corners (sharp corners) are provided at either circumferential end of the rib 22. This prevents or inhibits contact between the pin corners of the rib 22 and the radially inner surface of the sintered oil-impregnated bearing 1, even when the sintered oil-impregnated bearing 1 rotates circumferentially. Consequently, the sliding properties of the sintered oil-impregnated bearing 1 relative to the radially inner surface of the bearing retainer 2 can be improved. However, this example does not preclude the possibility that at least one circumferential end of at least one rib 22 is not C-chamfered or R-chamfered.

[0071] Furthermore, it is preferred that the circumferential width R3 of at least one rib 22 be greater than the circumferential width R1c of the first groove 121. More preferably, R3 > R1c for all ribs 22. This allows the ribs 22 to contact the radially outer surface of the oil-impregnated sintered bearing 1 (or the bearing cylindrical portion 11) via the lubricating oil F without being trapped in the first groove 121. Consequently, the ribs 22 can slide smoothly on the radially outer surface of the oil-impregnated sintered bearing 1 (or the bearing cylindrical portion 11) without becoming lodged in the first groove 121.

[0072] Furthermore, the sintered oil-impregnated bearing 1 preferably contacts the ribs 22 via the lubricating oil F within the circumferential range R1b between circumferentially adjacent slot groups 12. This allows at least a portion of each rib 22 to contact the circumferential range R1b of the radially outer surface of the sintered oil-impregnated bearing 1 (of its bearing cylindrical portion 11) where the slot groups 12 are not located, via the lubricating oil F. Consequently, the sintered oil-impregnated bearing 1 (of its bearing cylindrical portion 11) can be easily inserted into the bearing holder 2 without radial displacement. Furthermore, during insertion, the sintered oil-impregnated bearing 1 (of its bearing cylindrical portion 11) can be positioned relative to the bearing holder 2 without any need for alignment. This improves the ease of assembly of the motor 100.

[0073] In the sintered oil-impregnated bearing 1, the circumferential spacing R1b between circumferentially adjacent groove groups 12 is preferably greater than the circumferential spacing R4 between one circumferential end of the first groove 121 located closest to one circumferential side of the groove group 12 and the other circumferential end of the first groove 121 located closest to the other circumferential side of the groove group 12. More preferably, the minimum circumferential spacing R1b is greater than the maximum circumferential spacing R4. This allows the circumferential range R1b of the radially outer surface of the sintered oil-impregnated bearing 1 (of the bearing cylindrical portion 11) where groove groups 12 are not located to be greater than the circumferential range R4 where groove groups 12 are located. Consequently, the contact area between the sintered oil-impregnated bearing 1 (of the bearing cylindrical portion 11) and the rib 22 via the lubricating oil F can be further increased. Consequently, the bearing retainer 2 can stably retain the sintered oil-impregnated bearing 1. However, this example does not exclude configurations where R1b ≤ R4.

[0074] <2. Others>

[0075] The above describes the embodiments of the present invention. In addition, the scope of the present invention is not limited to the above-mentioned embodiments. The present invention can be implemented by adding various changes to the above-mentioned embodiments within the scope of the main purpose of the invention. In addition, the matters described in the above-mentioned embodiments can be appropriately combined in any manner within the scope that does not cause contradictions.

[0076] <3. Summary>

[0077] Hereinafter, the embodiments described so far will be summarized.

[0078] For example, the sintered oil-impregnated bearing disclosed in this specification is constructed as follows: a bearing cylinder portion, which is composed of a porous sintered body that can be impregnated with lubricating oil and extends along the central axis; and a groove group, which has a plurality of first grooves extending at least in the axial direction of the above-mentioned central axis and arranged circumferentially, and the above-mentioned groove group is arranged in plurality on the radial outer side surface of the above-mentioned bearing cylinder portion and arranged circumferentially, and the circumferential spacing between the circumferentially adjacent first grooves in each of the above-mentioned groove groups is smaller than the circumferential spacing between the circumferentially adjacent groove groups (first structure).

[0079] Furthermore, the oil-impregnated sintered bearing of the first structure may be configured such that the plurality of groove groups include a pair of groove groups disposed opposite to each other with the center axis interposed therebetween when viewed in the axial direction (second structure).

[0080] In addition, the sintered oil-impregnated bearing of the first or second structure can also be constructed as follows: the above-mentioned sintered oil-impregnated bearing also has a second groove, which is arranged on the axial end face of the above-mentioned bearing cylinder, is recessed in the axial direction and extends at least in the radial direction, and the circumferential range in which at least one of the above-mentioned second grooves is arranged overlaps with the circumferential range in which any of the above-mentioned first grooves is arranged (third structure).

[0081] Furthermore, the oil-impregnated sintered bearing of the third structure may be configured such that the circumferential width of the at least one second groove is less than or equal to the circumferential width of any one of the first grooves (fourth structure).

[0082] In addition, the sintered oil-impregnated bearing of any one of the first to fourth structures can also be constructed as follows: the above-mentioned sintered oil-impregnated bearing also has a chamfered portion, which is arranged between the radial outer side surface and the axial end face of the above-mentioned bearing cylinder portion, and extends circumferentially in a direction obliquely intersecting the axial and radial directions, and at least either one of the axial width and radial width of the above-mentioned chamfered portion is more than half of the inner diameter of the above-mentioned bearing cylinder portion (fifth structure).

[0083] Furthermore, the oil-impregnated sintered bearing of the fifth configuration may be configured such that the axial width of the chamfered portion is larger than the radial width of the chamfered portion (sixth configuration).

[0084] In addition, the motor disclosed in this specification can also be constructed to include: a sintered oil-impregnated bearing of any one of the first to sixth structures; a shaft extending along the above-mentioned center axis; a rotor capable of rotating around the above-mentioned center axis together with the above-mentioned shaft; and a bearing retainer that rotatably supports the above-mentioned shaft via the above-mentioned sintered oil-impregnated bearing, the above-mentioned bearing retainer having: a retainer cylinder portion extending in the axial direction and surrounding and retaining the above-mentioned sintered oil-impregnated bearing; and a plurality of ribs protruding radially inward from the radially inner side surface of the above-mentioned retainer cylinder portion and arranged circumferentially (seventh structure).

[0085] Furthermore, the motor of the seventh configuration may be configured such that the oil-impregnated sintered bearing contacts the rib via the lubricating oil within a circumferential range between the circumferentially adjacent groove groups (eighth configuration).

[0086] In addition, the motor of the seventh or eighth structure can also be constructed so that the circumferential spacing between the above-mentioned slot groups adjacent in the circumferential direction is larger than the circumferential spacing between the circumferential end portion of the above-mentioned first slot arranged on one circumferential side in the above-mentioned slot group and the circumferential end portion of the above-mentioned first slot arranged on the other circumferential side in the above-mentioned slot group (ninth structure).

[0087] Furthermore, the motor of any one of the seventh to ninth structures may be configured such that a circumferential width of at least one of the ribs is larger than a circumferential width of the first groove (tenth structure).

[0088] Furthermore, the motor of any one of the seventh to tenth structures may be configured such that at least a portion of the ribs are arranged in n-fold symmetry in the circumferential direction with respect to the central axis, where n is an integer greater than or equal to 3 (eleventh structure).

[0089] Availability in production

[0090] The present invention can be used for a bearing composed of a porous sintered body and a device equipped with the bearing.

[0091] Explanation of symbols

[0092] 100—motor, 101—shaft, 102—rotor, 103—stator, 104—bracket, 105—base plate, 1—sintered oil-impregnated bearing, 11—bearing cylinder, 111—conical surface, 12, 12a, 12b—slot group, 121—first slot, 13—second slot, 14—chamfered portion, 2—bearing retainer, 21—retainer cylinder, 22—rib, CA—center axis, F—lubricating oil.

Claims

1. A sintered oil-containing bearing, characterized in that: have: a bearing cylinder portion formed of a porous sintered body capable of being impregnated with lubricating oil and extending along the central axis; and a groove group having a plurality of first grooves extending at least in the axial direction of the central axis and arranged in the circumferential direction, The groove group is arranged in plurality on the radially outer side of the bearing cylinder and arranged in the circumferential direction. The circumferential interval between the first grooves adjacent to each other in the circumferential direction in each of the groove groups is smaller than the circumferential interval between the groove groups adjacent to each other in the circumferential direction.

2. The sintered oil-impregnated bearing according to claim 1, characterized in that: The plurality of groove groups include a pair of groove groups that are arranged to face each other across the center axis when viewed in the axial direction.

3. The oil-impregnated sintered bearing according to claim 1, characterized in that: The oil-impregnated sintered bearing further comprises a second groove, which is arranged on the axial end surface of the bearing cylinder, is recessed in the axial direction and extends at least in the radial direction. The circumferential range where at least one of the second grooves is arranged overlaps with the circumferential range where any one of the first grooves is arranged.

4. The oil-impregnated sintered bearing according to claim 3, characterized in that: The circumferential width of the at least one second groove is less than the circumferential width of any one of the first grooves.

5. The oil-impregnated sintered bearing according to claim 1, characterized in that: The sintered oil-impregnated bearing further includes a chamfered portion, which is arranged between the radially outer side surface and the axial end surface of the bearing cylinder portion and extends in the circumferential direction in a direction obliquely intersecting the axial direction and the radial direction. At least one of an axial width and a radial width of the chamfered portion is equal to or greater than half of an inner diameter of the bearing cylindrical portion.

6. The oil-impregnated sintered bearing according to claim 5, characterized in that: The axial width of the chamfered portion is greater than the radial width of the chamfered portion.

7. A motor, characterized in that: have: The sintered oil-impregnated bearing according to any one of claims 1 to 6; an axis extending along the central axis; a rotor rotatable together with the shaft about the central axis; and a bearing holder that rotatably supports the shaft via the sintered oil-impregnated bearing, The bearing retainer has: a retainer cylindrical portion extending in the axial direction and surrounding and retaining the sintered oil-impregnated bearing; and A plurality of ribs protrude radially inward from a radially inner side surface of the retainer tube portion and are arranged in the circumferential direction.

8. The motor according to claim 7, characterized in that The oil-impregnated sintered bearing contacts the rib via the lubricating oil within a circumferential range between the circumferentially adjacent groove groups.

9. The motor according to claim 7, characterized in that The circumferential spacing between the circumferentially adjacent groove groups is larger than the circumferential spacing between one circumferential end portion of the first groove disposed most circumferentially on one side in the groove group and the other circumferential end portion of the first groove disposed most circumferentially on the other side in the groove group.

10. The motor according to claim 7, wherein A circumferential width of at least one of the ribs is greater than a circumferential width of the first groove.

11. The motor according to claim 7, wherein At least a portion of the ribs are arranged in n-fold symmetry with respect to the central axis in the circumferential direction, where n is an integer greater than or equal to 3.

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