Bearing device for rotary shaft of vehicle driving motor

Abstract

To provide a bearing device for a rotary shaft of a vehicle driving motor having a sliding bearing in which biting hardly occurs when pressed into a bearing holding hole of an integral type bearing housing.SOLUTION: The outer peripheral face of each half-split bearing in a non-mounted state consists of first and second curved faces (81, 82) formed along two types of circular arcs different in curvature radius. A circumferential angle (θ1) of the second curved face, measured from the peripheral end face of the half-split bearing while centering on a center (C1) of the first circular arc, is formed in a range from a minimum value 10° to a maximum value 30°. When extending the second curved face and the first curved face at the peripheral end of the half split bearing to the peripheral end of the half-split bearing, a length (L2) from a virtual outer peripheral face (83) in the radial direction of the half-split bearing is 5-30 μm.. In a mounted state, the peripheral end faces of the pair of half-split bearings contact each other with no space, and the first curved face and the second curved face of the outer peripheral faces of the pair of half-split bearings contact the inner peripheral face of the bearing holding hole with no space.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a bearing device for supporting a rotating shaft of a vehicle drive motor.

Background Art

[0002] In a vehicle drive motor, a stator having a coil is disposed on the outer peripheral side and a rotor having a magnet is disposed on the inner peripheral side inside a motor case, and the rotor rotates by energizing the coil of the stator. The rotor is connected to a rotating shaft for outputting the rotational force of the rotor. The rotating shaft is pivotally supported in a bearing holding hole of the motor case via a rolling bearing (see, for example, Patent Document 1).

[0003] In order to quiet the vehicle drive motor, there is a consideration to replace it with a sliding bearing composed of a pair of half bearings having better quietness than a conventional rolling bearing. Conventionally, when a bearing holding hole for holding a sliding bearing composed of a pair of half bearings is of an integral type, the pair of half bearings constituting the sliding bearing are simultaneously press-fitted from one opening in the axial direction of the bearing holding hole (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a sliding bearing composed of a pair of split bearings is press-fitted simultaneously from one opening of an integral bearing holding hole, first, immediately after the start of press-fitting, a displacement occurs between the circumferential end faces of the pair of split bearings, and the circumferential end portion near the outer peripheral surface of the split bearing strongly interferes with the edge of the opening of the bearing holding hole, resulting in the outer peripheral surface of the split bearing being scraped. Further, as the press-fitting progresses, there is a problem that the outer peripheral surface of the split bearing is likely to be scratched (multiple axial scratches) by the material of the outer peripheral surface of the split bearing adhered to the edge of the opening of the bearing holding hole.

Means for Solving the Problems

[0006] Therefore, an object of the present invention is to provide a bearing device for a rotating shaft of a vehicle drive motor having a sliding bearing in which scratching is less likely to occur when press-fitting into a bearing holding hole of an integral bearing housing.

[0007] To solve the above problems, the present invention is a bearing device for supporting a rotating shaft of a vehicle drive motor, and the bearing device includes a stator of a vehicle drive motor, a rotor of a vehicle drive motor, a rotating shaft connected to the rotor, a motor case having a cylindrical bearing holding hole, a sliding bearing and has The sliding bearing is composed of a pair of split bearings, Each of the pair of split bearings has an inner peripheral surface, an outer peripheral surface, and two circumferential end faces, The pair of split bearings have the same axial length as each other, The pair of split bearings are simultaneously press-fitted from one opening in the axial direction of the bearing holding hole and mounted on the inner peripheral surface of the bearing holding hole. In the bearing device, the inner peripheral surfaces of the pair of split bearings support the rotating shaft. In the non-mounted state, the outer peripheral surface of each half bearing consists of a first and a second curved surface formed along two types of arcs with different curvatures. The first curved surface is a region including the circumferential central portion of the outer peripheral surface. The second curved surface is the remaining two regions of the outer peripheral surface that are continuous with the first curved surface and extend toward the circumferential end face of the half bearing. The relationship between the center of the first arc forming the first curved surface and the center of the second arc forming the second curved surface is such that the center of the second arc is on a perpendicular line to the bearing outer diameter center line passing through the center of the first arc and is offset to the inner side, that is, the side closer to the circumferential central portion of the outer peripheral surface, of the center of the first arc. The second curved surface is formed in a range where the circumferential angle measured from the circumferential end face of the half bearing around the center of the first arc is from a minimum value of 10° to a maximum value of 30°. The radial length of the half bearing between the second curved surface and the virtual outer peripheral surface when the first and second curved surfaces of the outer peripheral surface of the half bearing are extended to the circumferential end of the half bearing at the circumferential end of the half bearing is 5 - 30 μm. Crush reliefs are formed at each circumferential end of the inner peripheral surface of each half bearing. In the mounted state, the present invention provides a bearing device characterized in that the circumferential end faces of a pair of half bearings are in contact with each other without a gap, and the first and second curved surfaces of the outer peripheral surfaces of the pair of half bearings are in contact with the inner peripheral surface of the bearing holding hole without a gap.

[0008] In another embodiment of the present invention, the motor case has two or more bearing holding holes, and the bearing device has two or more sliding bearings.

[0009] In another embodiment of the present invention, when a plane where the circumferential end faces of a pair of half bearings are in contact with each other is defined as a dividing plane, in the non-mounted state, the circumferential end faces of the half bearings are parallel to the dividing plane.

[0010] In another embodiment of the present invention, when a plane where the circumferential end faces of a pair of half bearings are in contact with each other is defined as a dividing plane, in the non-mounted state, the circumferential end faces of the half bearings are in contact with the dividing plane at the radially outer end and are inclined so as to be separated from the dividing plane as they approach the radially inner end. The inclination angle between each circumferential end face of the half bearing and the dividing plane is 3×10 when viewed from the axial direction.-2 ° to 15×10 -2 is °.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0013] (First Embodiment) FIG. 1 schematically shows an axial cross-section of a bearing device 1 for a rotating shaft of a vehicle drive motor. FIG. 6 shows a view of the bearing holding hole as seen in the axial direction. FIG. 7 shows a cross-sectional view taken along line A-A of the bearing holding hole shown in FIG. 6. This bearing device 1 has a stator 4 and a rotor 5 of a vehicle drive motor in a motor case 2. The stator 4 has a coil 41 and is arranged on the outer peripheral side. The rotor 5 has a magnet and is arranged on the inner peripheral side. The rotor 5 rotates by energizing the coil 41 of the stator 4. The rotor 5 is connected to a rotating shaft 6 for outputting the rotational force of the rotor. One end of the rotating shaft in the axial direction is connected to a speed reducer (not shown) for amplifying the rotational torque of the rotating shaft 6. Also, the motor case 2 is provided with an oil passage (not shown) for supplying lubricating oil between the sliding bearing 3 and the rotating shaft 6.

[0014] The rotating shaft 6 is pivotally supported in a bearing holding hole 23 of the motor case 2 via a sliding bearing 3 composed of a pair of split bearings 31 and 32. As shown in FIGS. 6 and 7, the bearing holding hole 23 is of an integral type and has a cylindrical shape. The fact that the bearing holding hole 23 is of an integral type means that the inner peripheral surface 24 of the bearing holding hole 23 is not divided into a plurality of parts. The pair of split bearings 31 and 32 are simultaneously press-fitted into one opening 25 in the axial direction of the bearing holding hole 23 of the motor case 2 with their circumferential end faces 76 facing each other. The outer peripheral length of the pair of split bearings 31 and 32 before press-fitting is slightly larger than the inner peripheral length of the bearing holding hole 23. After press-fitting, a pressure is generated that presses the outer peripheral surfaces 8 of the pair of split bearings 31 and 32 against the inner peripheral surface 24 of the bearing holding hole 23, whereby the pair of split bearings 31 and 32 are mounted (fixed) in the bearing holding hole 23 of the motor case 2. Note that the bearing device 1 of this embodiment is configured such that the motor case 2 has two bearing holding holes 23, but is not limited thereto, and the motor case 2 may have one bearing holding hole 23 or may have three or more bearing holding holes 23. Also, the bearing device 1 of this embodiment is configured to have an integral motor case 2, but is not limited thereto, and the motor case 2 can be changed to be composed of a plurality of members.

[0015] In a conventional sliding bearing having a pair of split bearings whose outer peripheral surfaces are formed by a curved surface along a single arc (which may be an elliptical arc), there were the following problems. When press-fitting the pair of split bearings simultaneously from one opening of the integral bearing holding hole, first, a displacement occurs between the circumferential end faces of the pair of split bearings immediately after the start of press-fitting. Then, the vicinity of the circumferential end of the outer peripheral surface of the split bearing strongly interferes with the edge of the opening of the bearing holding hole, and the outer peripheral surface of the split bearing is scraped. As the press-fitting further progresses, the outer peripheral surface of the split bearing is likely to be scratched (multiple axial scratches) by the material of the outer peripheral surface of the split bearing adhered to the edge of the opening of the bearing holding hole.

[0016] The present invention addresses such problems of the prior art. Hereinafter, an embodiment of the bearing device 1 of the present invention will be described.

[0017] FIG. 2 shows a view of the sliding bearing 3 composed of the split bearings 31 and 32 of the present invention with the circumferential end faces 76 aligned in the non-mounted state (before press-fitting), as viewed from the axial direction. FIG. 3 is a view of the split bearing 31 (32) shown in FIG. 2 as viewed from the axial direction. FIG. 4 is a plan view of the split bearing 31 (32) shown in FIG. 2 as viewed from the inner peripheral surface side. FIG. 5 is a plan view of the split bearing 31 (32) shown in FIG. 2 as viewed from the outer peripheral surface side.

[0018] As shown in FIGS. 2 to 4, the sliding bearing 3 of the present embodiment is formed by butting the circumferential end faces 76 of a pair of split bearings 31 and 32 and combining them into a cylindrical shape as a whole. The split bearings 31 and 32 can have a sliding layer made of a Cu bearing alloy or an Al bearing alloy. Alternatively, they can have a sliding layer of a Cu bearing alloy or an Al bearing alloy on a backing layer made of an Fe alloy. Further, the cylindrical inner peripheral surface 7 and outer peripheral surface 8 may have a surface portion made of any one of Bi, Sn, and Pb, which is softer than the bearing alloy, or a surface portion made of an alloy mainly composed of these metals or a surface portion made of a resin composition mainly composed of a synthetic resin.

[0019] The half bearings 31 and 32 have an inner peripheral surface 7, an outer peripheral surface 8, two circumferential end surfaces 76, 76, and two axial end surfaces 7E, 7E. The pair of half bearings 31 and 32 have the same inner diameter dimension, outer diameter dimension, and axial length L1. The outer peripheral surfaces 8 of the respective half bearings 31 and 32 in the non-mounted state are composed of a first curved surface 81 and a second curved surface 82 formed along two types of arcs (which may be elliptical arcs) with different curvatures. The first curved surface 81 is a region including the circumferential central portion CP of the outer peripheral surface 8. The second curved surface 82 is the remaining two regions of the outer peripheral surface 8 that are continuous with the first curved surface 81 and extend toward the circumferential end surfaces 76 of the half bearings 31 and 32. The relationship between the center C1 of the first arc forming the first curved surface 81 and the center C2 of the second arc forming the second curved surface 82 is such that the center C2 of the second arc is on the perpendicular line CL with respect to the bearing outer diameter center line passing through the center C1 of the first arc, and is offset to the inner side of the center C1 of the first arc, that is, to the side closer to the circumferential central portion CP of the outer peripheral surface 8.

[0020] The second curved surface 82 is formed in a range where the circumferential angle θ1 measured from the circumferential end surfaces 76 of the half bearings 31 and 32 around the center C1 of the first arc is from a minimum value of 10° to a maximum value of 30°. In the case of a bearing device for a vehicle drive motor for a passenger car or the like (for example, a vehicle drive motor with a shaft diameter of the rotating shaft being 30 to 100 mm), the radial length L2 of the half bearings 31 and 32 between the second curved surface 82 and the virtual outer peripheral surface 83 when the second curved surface 82 and the first curved surface 81 at each circumferential end surface 76 of the half bearings 31 and 32 are extended to the circumferential end surfaces 76 of the half bearings is 5 to 30 μm. Further, the relationship between the circumferential angle θ1 and the length L2 (L2 / θ1) is preferably 0.5 to 1.2 (μm / °).

[0021] In the present embodiment, the wall thickness of the half bearings 31 and 32 in the region of the first curved surface 81 is constant in the circumferential direction. However, the wall thickness in the region of the first curved surface 81 may be maximum at the circumferential central portion CP and continuously decrease toward both circumferential end surface 76 sides.

[0022] In a region adjacent to the circumferential end face 76 of the inner circumferential surface 7 of the half bearings 31 and 32, a crush relief 70 is formed. The crush relief 70 is a wall thickness reduction region formed by cutting (removing the sliding layer) so that the wall thickness is thinner than the original inner circumferential surface 7 (major arc). The crush relief 70 is provided with the intention of forming a gap for absorbing displacement and deformation of the circumferential end face 76 in a state where the pair of half bearings 31 and 32 are assembled in the bearing holding hole (see, for example, SAE J506 (Items 3.26 and 6.4), DIN1497 (Section 3.2), JIS D3102). Generally, in the case of a bearing for a small internal combustion engine for a passenger car, the depth of the crush relief at the circumferential end face of the half bearing (the distance from the original inner circumferential surface to the actual inner circumferential surface) is about 0.01 to 0.075 mm, and the length (the vertical length from the circumferential end face of the half bearing to the upper edge of the crush relief 70 with respect to the end face) is about 3 to 7 mm.

[0023] Also, in the present embodiment, when a plane where the circumferential end faces of the pair of half bearings are in contact with each other is defined as a dividing plane HP, in the non-mounted state, the circumferential end faces of the half bearings are parallel to the dividing plane HP.

[0024] As described above, the outer circumferential surface 8 of the half bearing used in the bearing device of the present invention is composed of first and second curved surfaces 81 and 82 formed along two types of arcs with different curvatures in the non-mounted state. The reason why bearing damage is reduced by this half bearing will be described below.

[0025] As described above, in the present invention, the first curved surface 81 is a region including the circumferential center portion CP of the outer peripheral surface 8, and the second curved surface 82 is the remaining two regions of the outer peripheral surface 8 that are continuous with the first curved surface 81 and extend toward both circumferential ends of the half bearing. The relationship between the center C1 of the first arc forming the first curved surface 81 and the center C2 of the second arc forming the second curved surface 82 is that the center C2 of the second arc is on the perpendicular line CL with respect to the bearing outer diameter center line passing through the center C1 of the first arc, and is offset to a position closer to the center C1 of the first arc, that is, closer to the circumferential center portion CP of the outer peripheral surface 8. The second curved surface 82 is formed in a range where the circumferential angle θ1 measured from the circumferential end faces 76 of the half bearings 31 and 32 is from a minimum value of 10° to a maximum value of 30°. The radial length L2 of the half bearing between the second curved surface 82 and the virtual outer peripheral surface 83 when the first curved surface 81 and the second curved surface 82 of the outer peripheral surface 8 of the half bearings 31 and 32 are extended to the circumferential ends of the half bearings 31 and 32 is 5 to 30 μm.

[0026] With this configuration, a gap is formed between the second curved surface 82 and the virtual outer peripheral surface 83 when the first curved surface 81 and the second curved surface 82 of the outer peripheral surface 8 of the half bearings 31 and 32 are extended to the circumferential end faces 76 of the half bearings 31 and 32 (see FIGS. 2 and 3). Therefore, when the pair of half bearings 31 and 32 are simultaneously press-fitted from one opening 25 of the integral bearing holding hole 23, even if a displacement occurs between the circumferential end faces 76 of the pair of half bearings 31 and 32 immediately after the start of press-fitting, the second curved surface 82 of the outer peripheral surface 8 of the half bearings 31 and 32 is less likely to strongly interfere with the edge of the opening 25 of the bearing holding hole 23, and no gouging (scratches in a plurality of axial directions) occurs on the second curved surface 82 of the outer peripheral surface 8.

[0027] FIG. 8 is a view of the sliding bearing and the bearing holding hole according to the first embodiment of the present invention as viewed in the axial direction. FIG. 9 is an enlarged view of a portion B of the sliding bearing and the bearing holding hole shown in FIG. 8. As shown in FIGS. 8 and 9, after press-fitting (mounted state) into the integral bearing holding hole 23, circumferential compressive stress is generated in the pair of split bearings 31, 32, and the circumferential end faces 76 come into contact with each other without a gap. Further, the dotted line shown in FIG. 9 indicates a virtual second curved surface 82A when it does not displace due to press-fitting (mounting). After press-fitting (mounted state), due to the circumferential compressive stress, the circumferential end faces 76 of the pair of split bearings 31, 32 are pressed against each other, and the second curved surface 82 is displaced in the radially outer direction (the direction of the white arrow in FIG. 9). The second curved surface 82 of the outer peripheral surface 8 of the pair of split bearings 31, 32 comes into contact with the inner peripheral surface 24 of the bearing holding hole 23 without a gap, similar to the first curved surface 81. Therefore, it becomes difficult for the oil supplied to the bearing device during operation of the vehicle drive motor to enter between the outer peripheral surface 8 of the pair of split bearings 31, 32 and the inner peripheral surface 24 of the bearing holding hole 23.

[0028] In addition, when the formation range of the second curved surface 82 is less than 10° or the radial length L2 of the split bearings 31, 32 between the second curved surface 82 and the virtual outer peripheral surface 83 on each circumferential end face 76 of the split bearings 31, 32 is less than 5 μm, when simultaneously press-fitting the pair of split bearings from one opening 25 side of the integral bearing holding hole 23, the second curved surface 82 of the outer peripheral surface of the split bearing strongly interferes with the edge of the opening of the bearing holding hole 23, and the outer peripheral surface of the split bearing may be scraped and nicked (a plurality of axial scratches) may occur.

[0029] Further, when the formation range of the second curved surface 82 exceeds 30°, or when the radial length L2 of the split bearings 31 and 32 between the second curved surface 82 and the virtual outer peripheral surface 83 at each circumferential end surface 76 of the split bearings 31 and 32 exceeds 30 μm, a (partial) gap may be formed between the second curved surface 82 of the outer peripheral surface 8 of the pair of split bearings 31 and 32 and the inner peripheral surface 24 of the bearing holding hole 23 after press-fitting. When such a gap is formed, the oil supplied to the bearing device during the operation of the vehicle drive motor easily enters this gap. When oil enters between the second curved surface 82 of the outer peripheral surface 8 of the split bearings 31 and 32 and the inner peripheral surface 24 of the bearing holding hole 23, the force for holding the sliding bearing 3 by the bearing holding hole 23 becomes small, and the sliding bearing 3 may rotate together with the rotating shaft 6, and the rotating shaft 6 may not be supported.

[0030] (Second Embodiment) Hereinafter, other non-limiting embodiments of the present invention will be described.

[0031] FIG. 10 shows a view of the sliding bearing 3 composed of the split bearings 31 and 32 of the second embodiment of the present invention with the circumferential end surfaces 76 facing each other in the non-mounted state (before press-fitting) as viewed from the axial direction. FIG. 11 shows a view of the split bearing 31 (32) shown in FIG. 10 as viewed from the axial direction. FIG. 12 is an enlarged view of part C of the split bearing 31 (32) shown in FIG. 11.

[0032] The bearing device of the second embodiment is different only in the configuration of the circumferential end surfaces 76 and 76 of the split bearings 31 and 32 that constitute the sliding bearing 3, and other configurations are the same as those of the bearing device of the first embodiment. The description of the configurations common to the first embodiment will be omitted.

[0033] As shown in the enlarged view of FIG. 12, when a plane where the circumferential end surfaces of the pair of split bearings are in contact with each other is defined as a dividing plane HP, the circumferential end surfaces 76 and 76 of the split bearings 31 and 32 in the non-mounted state are in contact with the dividing plane HP at the radially outer end portion 76O, and are inclined so as to be separated from the dividing plane HP as they approach the radially inner end portion 76I. The inclination angle θ2 between the circumferential end surfaces 76 and 76 of the split bearings 31 and 32 and the dividing plane HP is 3×10 as viewed from the axial direction -2° to 15×10 -2 It is °. When each circumferential end face 76, 76 of the half bearings 31, 32 has an inclination angle θ2, the formation range of the second curved surface 82 is defined as a circumferential angle θ1 measured from the radially outer end 76O of the circumferential end face 76 of the half bearings 31, 32 around the center C1 of the first arc.

[0034] When each circumferential end face 76, 76 of the half bearings 31, 32 has an inclination angle θ2, in the mounted state (after press-fitting), the circumferential end faces 76 come into contact with each other without a gap. Also, the second curved surface 82 becomes more likely to be displaced in the radially outer direction, and the pressure (pushing pressure) between the second curved surface 82 and the inner peripheral surface 24 of the bearing holding hole 23 becomes larger. For this reason, the oil supplied to the bearing device during the operation of the vehicle drive motor becomes less likely to enter between the outer peripheral surfaces 8 of the pair of half bearings 31, 32 and the inner peripheral surface 24 of the bearing holding hole 23.

[0035] When the inclination angle θ2 between each circumferential end face 76, 76 of the half bearings 31, 32 and the split plane HP is less than 3×10 -2 °, it becomes difficult to obtain the effect of increasing the pressure between the second curved surface 82 and the inner peripheral surface 24 of the bearing holding hole 23 in the mounted state. Also, when the inclination angle θ2 exceeds 15×10 -2 °, displacement may occur between the circumferential end faces 76, 76 of the half bearings 31, 32 immediately after the start of press-fitting, and the second curved surface 82 of the outer peripheral surface 8 of the half bearings 31, 32 may strongly interfere with the edge of the opening 25 of the bearing holding hole 23, resulting in gouging (scratches in a plurality of axial directions).

[0036] The half bearing may further have, for example, an oil hole, an oil groove, or a notch for positioning. Also, the half bearing may have chamfers at positions where the outer peripheral surface and the axial end faces are adjacent, or at positions where the inner peripheral surface and the axial end faces are adjacent. Also, the half bearing may have a chamfer at a position where the inner peripheral surface and the circumferential end faces are adjacent.

Explanation of symbols

[0037] 1 Bearing device 2 Motor case 23 Bearing holding hole 24 Inner peripheral surface 25 Opening 3 Plain bearing 31, 32 Split bearing 4 Stator 5 Rotor 6 Rotating shaft 7 Inner peripheral surface 7E Axial direction end face 70 Crash relief 76 Circumferential direction end face 76I Inner end 76O Outer end 8 Outer peripheral surface 81 First curved surface 82 Second curved surface 82A Virtual second curved surface when not displaced 83 Virtual outer peripheral surface C1 Center of the first arc C2 Center of the second arc CL Perpendicular line to the bearing outer diameter center line CP Circumferential direction central part HP Split plane L1 Axial direction length of the split bearing L2 Length θ1 Circumferential angle θ2 Inclination angle

Claims

1. A bearing device (1) for supporting a rotating shaft of a vehicle drive motor, wherein the bearing device (1) comprises: A stator (4) of the vehicle drive motor; A rotor (5) of the vehicle drive motor; A rotating shaft (6) connected to the rotor (5); A motor case (2) having a cylindrical bearing holding hole (23); A sliding bearing (3); and having: The sliding bearing is composed of a pair of split bearings (31, 32); Each of the pair of split bearings has an inner peripheral surface (7), an outer peripheral surface (8), and two circumferential end surfaces (76, 76); The pair of split bearings have the same axial length (L1); The pair of split bearings are simultaneously press-fitted from one opening (25) in the axial direction of the bearing holding hole and mounted on the inner peripheral surface (24) of the bearing holding hole, and the inner peripheral surfaces of the pair of split bearings support the rotating shaft (6). In the bearing device (1), The outer peripheral surface of each split bearing in the non-mounted state is composed of a first curved surface (81) and a second curved surface (82) formed along two arcs with different curvatures. The first curved surface is a region including the circumferential central portion (CP) of the outer peripheral surface, and the second curved surface is the remaining two regions of the outer peripheral surface that are continuous with the first curved surface and extend toward the circumferential end surface of the split bearing. The relationship between the center (C1) of the first arc forming the first curved surface and the center (C2) of the second arc forming the second curved surface is that the center (C2) of the second arc is on a perpendicular line (CL) to the bearing outer diameter center line passing through the center (C1) of the first arc, and is offset to a position closer to the circumferential central portion of the outer peripheral surface, that is, inside the center (C1) of the first arc. The second curved surface is formed in a range where the circumferential angle (θ1) measured from the circumferential end surface of the split bearing around the center (C1) of the first arc is from a minimum value of 10° to a maximum value of 30°. The radial length (L2) of the half bearing between the second curved surface and the virtual outer peripheral surface (83) when the second curved surface and the first curved surface at the circumferential end of the half bearing are extended to the circumferential end of the half bearing is 5 to 30 μm, Crush reliefs (70) are formed at the circumferential ends of the inner peripheral surfaces of the respective half bearings, In the mounted state, the circumferential end faces of the pair of half bearings are in contact with each other without a gap, and the first curved surface and the second curved surface of the outer peripheral surfaces of the pair of half bearings are in contact with the inner peripheral surface of the bearing holding hole without a gap. The bearing device (1) is characterized by this.

2. The motor case has two or more bearing holding holes, and the bearing device (1) has two or more sliding bearings (3). The bearing device (1) according to claim 1.

3. When a plane in which the circumferential end faces of the pair of half bearings are in contact with each other is defined as a dividing plane (HP), in the non-mounted state, the circumferential end faces of the half bearings are parallel to the dividing plane (HP). The bearing device (1) according to claim 1.

4. When a plane in which the circumferential end faces of the pair of half bearings are in contact with each other is defined as a dividing plane (HP), in the non-mounted state, the circumferential end faces of the half bearings are in contact with the dividing plane at the radially outer end (76O), and are inclined so as to be separated from the dividing plane (HP) closer to the radially inner end (76I). The inclination angle θ2 between the circumferential end face of the half bearing and the dividing plane is 3×10 －２ ° to 15×10 －２ °. The bearing device (1) according to claim 1.

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