Rotating body

Abstract

To provide a rotating body that can suppress deformation of the bearing in the radial direction. [Solution] The rotating body 6 comprises a bearing 7 rotatably supported on a shaft 5 and a rotor 8 fixed to the bearing 7. The outer circumferential surface 71a of the bearing 7 is provided with a plurality of ribs 72 along the direction in which the shaft 5 extends, and the rotor 8 has a cylinder 83 that houses the bearing 7, the cylinder 83 is provided with grooves 87 corresponding to the ribs 72, and the ribs 72 are press-fitted into the grooves 87.

Description

Technical Field

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

Background Art

[0002] For example, Patent Document 1 discloses a rotor for an electric water pump. This rotor has a main body portion that supports an impeller and a sliding bearing supported by the main body portion. The sliding bearing is coupled into the main body portion, for example, by press-fitting.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Due to press-fitting, stress acts on the sliding bearing from the main body portion toward the inner peripheral side in the radial direction. This stress may cause the inner diameter of the bearing hole of the sliding bearing to decrease, making it difficult to manage the clearance between the outer peripheral surface of the shaft supported in the bearing hole and the inner peripheral surface of the bearing hole.

[0005] The present invention has been made in view of the above problems, and one of the problems is to provide a rotating body capable of suppressing deformation of the bearing in the radial direction.

Means for Solving the Problems

[0006] A rotating body according to an aspect of the present invention includes a bearing rotatably supported with respect to a shaft and a rotor fixed to the bearing. An outer peripheral surface of the bearing includes a plurality of ribs along a direction in which the shaft extends. The rotor has a cylinder that houses the bearing, and the cylinder includes a groove corresponding to the rib, and the rib is press-fitted into the groove.

Brief Description of the Drawings

[0007] [Figure 1] This is a perspective view showing a schematic structure of a pump device 1 relating to one specific example. [Figure 2] This is a cross-sectional view along line 2-2 in Figure 1. [Figure 3] This is a cross-sectional view along line 3-3 in Figure 2. [Figure 4] This is a schematic perspective view showing the structure of a rotating body 6 according to one embodiment of the present invention. [Figure 5] This is a perspective cross-sectional view along line 5-5 in Figure 4. [Figure 6] This is a cross-sectional view along line 6-6 in Figure 4. [Figure 7] This is a perspective view showing a schematic structure of bearing 7 in one specific example. [Figure 8] This is a schematic side view showing the structure of a bearing 7 in one specific example. [Figure 9] This is a partially enlarged cross-sectional view schematically showing the structure of a rotor 8 in one specific example. [Figure 10] This is a schematic side view showing the structure of bearing 7A in another specific example. [Figure 11] This is a partially enlarged cross-sectional view schematically showing the structure of rotor 8A in another specific example. [Modes for carrying out the invention]

[0008] An embodiment of the present invention will be described below with reference to the attached drawings. Figure 1 is a schematic perspective view showing the structure of a pump device 1 according to one specific example. Figure 2 is a cross-sectional view along line 2-2 in Figure 1. This pump device 1 is, for example, a water pump. A water pump is a centrifugal pump for transferring (pressurizing) a fluid, i.e., a coolant. The pump device 1 is installed, for example, in the engine room or motor room of a vehicle. The pump device 1 is used, for example, to cool a drive source such as the engine or motor of a vehicle by transferring coolant to the drive source.

[0009] In pump device 1, the direction along axis x is defined as the axial direction. In this axial direction, one side is defined as the upper side and the other side as the lower side. The upper and lower sides do not necessarily coincide with the upper and lower sides in the direction of gravity. Furthermore, the direction perpendicular to axis x is defined as the radial direction. In the radial direction, the direction approaching axis x is defined as the inner circumference side and the direction moving away from axis x is defined as the outer circumference side. In addition, a circumferential direction is defined around axis x. The clockwise and counterclockwise directions in the circumferential direction are defined as the direction when viewed from the upper side in the axial direction.

[0010] Referring together to Figures 1 and 2, the pump device 1, in this example, comprises a casing 2 formed in a cylindrical shape with axis x as its central axis. The casing 2 has a lower casing 3 positioned below and an upper casing 4 attached to the lower casing 3 from above. The lower casing 3 and the upper casing 4 are formed, for example, from a resin material by injection molding. The internal space S of the casing 2 is defined by the lower casing 3 and the upper casing 4.

[0011] The upper casing 4 has a main body portion 41 and an inlet portion 42 and an outlet portion 43 integrally formed with the main body portion 41. The main body portion 41 is formed in a cylindrical shape, for example, with axis x as the center. The main body portion 41 has an upper portion with a smaller diameter (hereinafter referred to as the "small diameter portion") 41a and a lower portion with a larger diameter (hereinafter referred to as the "large diameter portion") 41b. Both the small diameter portion 41a and the large diameter portion 41b are formed in a cylindrical shape. In the radial direction, the diameter of the small diameter portion 41a is smaller than the diameter of the large diameter portion 41b.

[0012] The inlet portion 42 protrudes upward from the upper surface of the small-diameter portion 41a of the main body portion 41 along the axis x. The inlet portion 42 is formed, for example, in a cylindrical shape centered on the axis x. The inlet portion 42 allows fluid to flow into the internal space S of the casing 2. The outlet portion 43 protrudes outward from the small-diameter portion 41a of the main body portion 41 along the tangent to a virtual circle centered on the axis x. The outlet portion 43 is formed, for example, in a cylindrical shape centered on the tangent. The outlet portion 43 allows fluid to flow out from the internal space S of the casing 2.

[0013] As shown in Figure 2, the lower casing 3 has a bottom wall 31, an inner wall 32, a top wall 33, and an outer wall 34. The bottom wall 31 is formed, for example, in the shape of a flat disc perpendicular to the axis x. The inner wall 32 extends upward from the outer peripheral edge of the bottom wall 31. The inner wall 32 is formed in the shape of a cylinder centered on the axis x. The top wall 33 extends outward from the upper edge of the inner wall 32. The top wall 33 is formed in the shape of an annular ring centered on the axis x. The outer wall 34 extends downward from the outer peripheral edge of the top wall 33. The outer wall 34 is formed in the shape of a cylinder centered on the axis x. In this example, the large diameter portion 41b of the upper casing 4 covers the outer peripheral surface of the outer wall 34.

[0014] The internal space S of the casing 2 comprises a first space S1 defined within the small-diameter portion 41a of the upper casing 4, and a second space S2 defined within the inner wall 32 of the lower casing 3. In this example, both the first space S1 and the second space S2 are generally cylindrical spaces centered on axis x. The first space S1 and the second space S2 are in communication with each other. In the radial direction, the diameter of the first space S1 is larger than the diameter of the second space S2. On the other hand, in the axial direction, the height of the first space S1 is smaller than the height of the second space S2.

[0015] This internal space S is sealed by the lower casing 3 and the upper casing 4. The fluid flows from the inlet 42 through the internal space S of the casing 2 and out through the outlet 43. This fluid is a liquid, such as a coolant. The liquid may include, for example, water. This water may contain other liquids. The other liquids may include, for example, antifreeze such as propylene glycol or ethylene glycol, or rust inhibitors.

[0016] The upper casing 4 has a cover 44 disposed below the base end of the inflow portion 42 within the main body portion 41 and a plurality of spokes 45 that support the cover 44. In this example, the cover 44 is disposed at a position that enters the first space S1 of the main body portion 41 from the inflow portion 42 along the axis x. The cover 44 is formed in a cylindrical shape centered on the axis x as a whole. The plurality of spokes 45 connect the outer surface of the cover 44 and the inner surface of the inflow portion 42 to each other. In this example, three spokes 45 are arranged at predetermined intervals in the circumferential direction. Each spoke 45 is formed in a flat plate shape that extends along a virtual plane including the axis x, for example.

[0017] The pump device 1 includes a shaft 5 fixed to the casing 2. The shaft 5 is formed in a cylindrical shape centered on the axis x in this example. A part of the upper end of the shaft 5 is accommodated and fixed in a recess 44a formed on the lower surface of the cover 44. The lower end of the shaft 5 is fixed to a mounting hole 31a formed in the bottom wall 31. In this example, the recess 44a is recessed upward from the lower surface of the cover 44. Thus, the cover 44 covers the end portion, that is, the upper end of the shaft 5. Further, the mounting hole 31a penetrates the bottom wall 31 in the axial direction, but is not limited thereto, and may be fixed to a recess (not shown) formed in the bottom wall 31. In this case, the shaft 5 is fixed in contact with the recess in the axial direction. Note that the axial direction is the direction in which the shaft 5 extends.

[0018] The pump device 1 includes a rotating body 6 rotatably supported by the shaft 5 around the axis x. The rotating body 6 has a bearing 7 supported by the shaft 5 and a rotor 8 fixed to the bearing 7. The bearing 7 is formed in a cylindrical shape along the axis x. The inner peripheral surface of the bearing 7 faces the outer peripheral surface of the shaft 5 with a predetermined gap therebetween. Thus, the bearing 7 is configured to be rotatable around the axis x and movable in the vertical direction along the axis x. The bearing 7 is a so-called sliding bearing. The rotor 8 has an impeller main body portion 81 fixed to the bearing 7 and a magnet 82 fixed to the impeller main body portion 81. Details of the rotating body 6 will be described later.

[0019] Figure 3 is a cross-sectional view along line 3-3 in Figure 2. Referring to both Figures 2 and 3, the pump device 1 includes a stator 9 incorporated into the lower casing 3. The stator 9 comprises a stator core 91, a plurality of coils 92, and an insulator 93. The stator core 91 is formed from a laminate of a plurality of thin plates stacked in the axial direction. The laminate is made of a magnetic material. The coils 92 have windings, for example, made of copper wire. The insulator 93 electrically insulates the stator core 91 from the plurality of coils 92. The insulator 93 is made of an insulating material, for example, a resin material.

[0020] The stator core 91 comprises an annular portion 94 and a plurality of teeth 95. The annular portion 94 is fixed to the inner circumferential surface of the outer wall 34 of the lower casing 3. The annular portion 94 is defined in an annular shape around the axis x. Each tooth 95 protrudes inward from the inner circumferential surface of the annular portion 94. Each tooth 95 faces the outer circumferential surface of the magnet 82 of the rotor 8 with a predetermined magnetic gap, with the inner wall 32 of the lower casing 3 in between. The windings of the coil 92 are wound around the insulator 93 that covers each tooth 95. In this example, there are 12 teeth 95, but the number of teeth 95 can be any number, such as 6 or 18. The number of poles of the rotor 8 can also be changed in accordance with the change in the number of teeth 95.

[0021] Figure 4 is a schematic perspective view showing the structure of a rotating body 6 according to one embodiment of the present invention. Figure 5 is a perspective cross-sectional view along line 5-5 in Figure 4. The cross-section shown in Figure 5 is a cross-section along a plane containing axis x. Referring together to Figures 4 and 5, the impeller body portion 81 of the rotor 8 has a cylinder 83, a base 84, a plurality of blades 85, and a flange 86. The impeller body portion 81 is integrally formed by injection molding from a thermoplastic resin material, such as PPS (polyphenylene sulfide).

[0022] The cylinder 83 is formed in a cylindrical shape with axis x as the center. The upper and lower ends of the cylinder 83 in the axial direction are open. The cylinder 83 defines a cylindrical first inner surface 83a about axis x, a similarly cylindrical second inner surface 83b about axis x, and a stepped surface 83c connecting the first inner surface 83a and the second inner surface 83b to each other. The first inner surface 83a is formed on the upper side of the cylinder 83 and has a larger diameter than the second inner surface 83b. The second inner surface 83b is formed on the lower side of the cylinder 83 than the first inner surface 83a. In this example, the stepped surface 83c extends along a plane perpendicular to axis x and has a surface facing upward in the axial direction.

[0023] A base 84 extends radially in an annular shape from the upper end of the cylinder 83 in the axial direction. That is, the base 84 is formed in a disc shape centered on axis x. In this example, the base 84 defines an annular upper and lower surface perpendicular to axis x. On the other hand, a flange 86 extends radially in an annular shape from the cylinder 83 between the upper and lower ends of the cylinder 83 in the axial direction. In this example, the flange 86 defines an annular upper and lower surface perpendicular to axis x. In the axial direction, the lower surface of the base 84 faces the upper surface of the flange 86.

[0024] Multiple (seven in this example) blades 85 rise upward from the top surface of the base 84. The multiple blades 85 are arranged circumferentially. In this example, all blades 85 have the same shape and dimensions. Each blade 85 extends in a curved manner from the inner circumferential end of the base 84 to the outer circumferential end of the base 84. In this example, when viewed from above, each blade 85 extends diagonally in a clockwise direction with respect to the radial direction from the inner circumferential end to the outer circumferential end. The height of each blade 85 from the top surface of the base 84 is the same from the inner circumferential end to the outer circumferential end of the blade 85.

[0025] The magnet 82 is fixed to the cylinder 83 below the flange 86. In this example, the magnet 82 is formed in a cylindrical shape centered on axis x. In this example, the upper surface of the magnet 82 is in contact with the lower surface of the flange 86. Also, the lower surface of the magnet 82 coincides with the lower end of the cylinder 83. This magnet 82 is, for example, a permanent magnet. The magnet 82 has alternating regions magnetized as south poles and regions magnetized as north poles in the circumferential direction. In this example, the diameter defined by the outer surface of the magnet 82 is set to be the same as the diameter defined by the outer surface of the flange 86.

[0026] Figure 6 is a cross-sectional view along line 6-6 in Figure 4. Figure 7 is a schematic perspective view showing the structure of a bearing 7 according to one specific example. Referring together to Figures 5 to 7, the bearing 7 has a body 71, ribs 72, and grooves 73. The body 71 is formed in a cylindrical shape with axis x as the center. Each rib 72 protrudes radially outward from the outer circumferential surface 71a of the body 71. In this example, four ribs 72 are arranged at equal intervals in the circumferential direction. Also, each rib 72 is positioned between the upper and lower ends of the body 71. The grooves 73 are formed on the inner circumferential surface 71b of the body 71. In this example, three grooves 73 are arranged at equal intervals in the circumferential direction.

[0027] Figure 8 is a schematic side view showing the structure of a bearing 7 according to one specific example. As shown in Figure 8, each rib 72 in this example has a pair of side surfaces 72a, 72a that move closer to each other from its upper end to its lower end. Each side surface 72a is inclined with respect to the axial direction. In addition, each rib 72 defines an outer end surface 72b that extends along a plane parallel to the axis x, for example. This side surface 72a constitutes a tapered surface according to the present invention. The width D1 of each rib 72 defined in the circumferential direction decreases from the upper end to the lower end of the rib 72. On the other hand, the height H of the outer end surface 72b of the rib 72 from the outer peripheral surface 71a of the main body 71 is the same from the upper end to the lower end of the rib 72.

[0028] Figure 9 is a partially enlarged cross-sectional view schematically showing the structure of a rotor 8 according to one specific example. The cross-section in Figure 9 corresponds to the cross-section in Figure 5. Referring together to Figures 5, 6, and 9, one or more grooves 87 extending parallel to the axial direction are formed on the second inner circumferential surface 83b of the cylinder 83 of the rotor 8. In this example, four grooves 87 are arranged in the circumferential direction corresponding to the ribs 72 of the bearing 7. Each groove 87 is recessed radially outward from the second inner circumferential surface 83b. The upper end of each groove 87 coincides with the stepped surface 83c. At the lower end of each groove 87, a stepped portion 87a is formed, for example, extending along a plane perpendicular to the axis x, and has a surface facing axially, i.e., in the direction in which the shaft 5 extends.

[0029] The groove 87 defines an inner circumferential surface 87b that is radially opposed to it. In this example, the inner circumferential surface 87b is defined along a plane perpendicular to the radial direction. The groove 87 also defines a pair of opposing side surfaces 87c, 87c. Each side surface 87c is opposed to the other in the circumferential direction. That is, each side surface 87c is defined along a plane perpendicular to the circumferential direction. In this example, the pair of side surfaces 87c, 87c are defined parallel to each other. That is, the width D2 of each groove 87 in the circumferential direction is the same from the top end to the bottom end of the groove 87. The width D2 is defined by the distance between the pair of side surfaces 87c, 87c.

[0030] The width D2 of the groove 87 is preferably set to be at least the width D1 defined by the lower end of each rib 72, and less than or equal to the width D1 defined by the upper end of each rib 72. Returning to Figures 5 and 6, the bearing 7 is housed inside the cylinder 83 of the rotor 8. According to the above settings for the width D1 of the rib 72 and the width D2 of the groove 87, the ribs 72 on the outer circumferential surface 71a of the main body 71 are press-fitted into the corresponding grooves 87 on the second inner circumferential surface 83b of the cylinder 83. In this way, the bearing 7 is fixed to the cylinder 83, i.e., the rotor 8. Note that adhesive may be applied between the rib 72 and the groove 87.

[0031] As shown in Figure 5, in this example, the lower end of the rib 72 is received by the lower end of the groove 87. That is, the lower end of the rib 72 contacts the stepped portion 87a. On the other hand, as shown in Figure 6, the outer end surface 72b of the rib 72 faces the inner circumferential surface 87b of the groove 87 with a predetermined gap between them. Also, the outer circumferential surface 71a of the body 71 of the bearing 7 faces the second inner circumferential surface 83b of the cylinder 83 of the rotor 8 with a predetermined gap between them. In this example, a gap is formed between the outer circumferential surface 71a and the second inner circumferential surface 83b, but the outer circumferential surface 71a may contact the second inner circumferential surface 83b. Specifically, the diameter of the outer circumferential surface 71a of the body 71 may be set to be equal to the diameter of the second inner circumferential surface 83b of the cylinder 83. The gap extends in the radial and axial directions.

[0032] Returning to Figure 2, when the rotating body 6 is supported by the shaft 5, predetermined gaps are secured in the axial direction between the upper end of the rotor 8 and the lower surface of the cover 44, and between the lower end of the rotor 8 and the upper surface of the bottom wall 31. The blades 85 of the rotor 8 are housed in the first space S1, while the magnet 82 is housed in the second space S2. In the axial and radial directions, the blades 85 face the inner surface of the main body portion 41 of the upper casing 4 with a predetermined gap between them. In the radial direction, the outer circumferential surface of the magnet 82 faces the inner circumferential surface of the inner wall 32 with a predetermined gap between them. Also, in the axial direction, the lower surface of the magnet 82 faces the upper surface of the bottom wall 31 of the lower casing 3 with a predetermined gap between them.

[0033] In the pump device 1, when current is supplied to the coil 92 of the stator 9, the magnetic interaction between the coil 92 and the magnet 82 causes the blades 85 of the rotor 8, or rotating body 6, to rotate clockwise around the axis x. This rotation of the blades 85 causes the coolant to flow into the first space S1 from the inlet 42. The incoming coolant flows outwards through the multiple blades 85 on the upper surface of the base 84, and then flows out from the outlet 43. In this way, the coolant is pumped from the pump device 1 to, for example, a drive source. At this time, the rotor 8 moves smoothly in the axial direction while rotating around the axis x due to the action of the bearing 7.

[0034] In the pump device 1 described above, when fixing the bearing 7 into the cylinder 83 of the rotor 8, the four ribs 72 on the outer circumferential surface 71a of the bearing 7 are each press-fitted into the four grooves 87 on the second inner circumferential surface 83b of the cylinder 83. Specifically, a pair of circumferentially opposing side surfaces 72a, 72a of each rib 72 slide along a pair of circumferentially opposing side surfaces 87c, 87c of each groove 87, and the rib 72 is press-fitted into the groove 87. In this way, the lower end of the rib 72 is received by the stepped portion 87a at the lower end of the groove 87, and the four ribs 72 are each fixed into the four grooves 87. In this way, the bearing 7 is fixed into the cylinder 83 of the rotor 8.

[0035] The press-fitting of the ribs 72 of the bearing 7 causes circumferential stress to act on each rib 72 from the cylinder 83 via the circumferentially opposing sides 72a and 87c. On the other hand, the outer end surface 72b of the rib 72 faces the inner circumferential surface 87b of the groove 87 via a predetermined gap. Similarly, the outer circumferential surface 71a of the main body 71 faces the second inner circumferential surface 83b via a predetermined gap. No radial stress acts on the bearing 7 from the cylinder 83 toward the inner circumferential side. As a result, deformation of the cylinder 83, i.e., the rotor 8, can be suppressed in the radial direction. At the same time, deformation of the bearing 7 can be suppressed in the radial direction. The clearance with the shaft 5 supported within the bearing 7 can be easily controlled. In addition, the ribs 72 can function as an anti-rotation device for the bearing 7 relative to the cylinder 83. The gap extends in the radial and axial directions.

[0036] Figure 10 is a schematic side view showing the structure of bearing 7A according to another specific example. Figure 11 is a partially enlarged cross-sectional view showing the structure of rotor 8A according to another specific example. As shown in Figure 10, in this bearing 7A, a pair of side surfaces 72a, 72a of each rib 72 are defined to be parallel to each other. That is, the width D1 of each rib 72 in the circumferential direction is the same from the upper end to the lower end of the rib 72. On the other hand, as shown in Figure 11, in this rotor 8A, a pair of side surfaces 87c, 87c of each groove 87 approach each other as they move from their upper end to their lower end. Each side surface 87c is inclined with respect to the axial direction. These side surfaces 87c constitute a tapered surface according to the present invention. The width D2 of each groove 87 decreases as it moves from the upper end to the lower end of the groove 87.

[0037] Preferably, the width D1 of the rib 73 is set to be greater than or equal to the width D2 defined at the lower end of each groove 87, and less than or equal to the width D2 defined at the upper end of each groove 87. In this rotating body 6, when fixing the bearing 7A into the cylinder 83 of the rotor 8A, the four ribs 72 on the outer circumferential surface 71a of the bearing 7 are press-fitted into the four grooves 87 on the second inner circumferential surface 83b of the cylinder 83. Specifically, a pair of circumferentially opposing side surfaces 72a, 72a of each rib 72 slide along a pair of circumferentially opposing side surfaces 87c, 87c of each groove 87, and the rib 72 is press-fitted into the groove 87. In this way, the lower end of the rib 72 is received by the stepped portion 87a at the lower end of the groove 87, and the four ribs 72 are fixed into the four grooves 87. In this way, the bearing 7A is fixed into the cylinder 83 of the rotor 8A.

[0038] In the above-described embodiment, tapered surfaces may be formed on at least a portion of the ribs 72 and grooves 87, as long as the tapered surfaces on the sides 72a, 72a and sides 87c, 87c approach each other as they move from the upper end to the lower end of the ribs 72 and grooves 87. Alternatively, tapered surfaces may be formed on only one of the circumferentially oriented sides 72a or 87c of the ribs 72 and grooves 87. In this case, the other circumferentially oriented side 72a or 87c, which is not a tapered surface, may extend along a plane parallel to the axis x. Furthermore, in the bearing 7, it is preferable that, for example, at least three ribs 72 are arranged at predetermined intervals in the circumferential direction.

[0039] Although the present invention has been described above through the embodiments described above, the technical scope of the present invention is not limited to the scope described in the embodiments above. It will be obvious to those skilled in the art that various modifications or improvements can be made to the embodiments described above. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0040] The embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit its interpretation. Furthermore, the embodiments described above do not limit the scope of application of the present invention, and the present invention may encompass anything as its target application. The components of the above embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified and can be modified as appropriate.

[0041] For example, the present invention includes differences that arise in the implementation of manufacturing tolerances, etc. Furthermore, components shown in different embodiments can be partially substituted or combined to the extent that they do not conflict with the technical requirements. In addition, each component can be selectively combined as appropriate to achieve at least some of the above-mentioned problems and effects. [Explanation of Symbols]

[0042] 1 Pump device, 2 Casing, 3 Lower casing, 31 Bottom wall, 31a Mounting hole, 32 Inner wall, 33 Top wall, 34 Outer wall, 4 Upper casing, 41 Main body, 41a Small diameter section, 41b Large diameter section, 42 Inlet, 43 Outlet, 44 Cover, 44a Recess, 45 Spoke, 5 Shaft, 6 Rotating body, 7, 7A Bearing, 71 Body, 71a Outer circumference, 71b Inner circumference, 72 Rib, 72a Side, 72b Outer end face, 73 Groove, 8, 8A Rotor, 81 Impeller body, 82 Magnet, 83 Cylinder, 83a First inner circumference, 83b Second inner circumference, 83c Stepped surface, 84 Base, 85 Blades, 86 Flange, 87 Groove, 87a Step, 87b Inner surface, 87c Side, 9 Stator, 91 Stator core, 92 Coil, 93 Insulator, 94 Annular section, 95 Teeth, D1 Width, D2 Width, S Internal space, S1 First space, S2 Second space, x-axis

Claims

1. A bearing that is rotatably supported on the shaft, A rotor fixed to the aforementioned bearing, Equipped with, The outer circumferential surface of the bearing is provided with a plurality of ribs along the direction in which the shaft extends, The rotor has a cylinder that houses the bearing, The cylinder is provided with grooves corresponding to the ribs, The rib is press-fitted into the groove. A rotating body.

2. The outer circumferential surface of the bearing faces the inner circumferential surface of the cylinder with a gap in between. The rotating body according to claim 1.

3. The outer circumferential surface of the rib faces the inner circumferential surface of the groove, with a gap in between. The rotating body according to claim 1.

4. The groove has a stepped portion facing the direction in which the shaft extends, The rib contacts the stepped portion, The rotating body according to any one of claims 1 to 3.

5. The rib has a tapered surface that is inclined with respect to the direction in which the shaft extends. The rotating body according to any one of claims 1 to 3.

6. The groove has a tapered surface that is inclined with respect to the direction in which the shaft extends. The rotating body according to any one of claims 1 to 3.

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