motor

Abstract

To provide a motor capable of suppressing a temperature rise of a bearing.SOLUTION: A motor 1 comprises: a cylinder 12; a shaft 20; an annular space CR formed between an inner peripheral face 13if of the cylinder 12 and an outer peripheral face 20op of the shaft 20; a first bearing 21; a second bearing 22; a stator 30 fixed to the shaft 12; a rotor 40 provided with an inner peripheral part 42a which includes a protrusion 42ap opposed to the second bearing 22 and is fixed to the shaft 20, an outer peripheral part 43 enclosing the stator 30 and a magnet 44 fixed to the outer peripheral part 43; and a substrate 15 fixed to a portion of the cylinder 12 between the stator 30 and the first bearing 21 in a length direction of the shaft 20. The motor 1 further comprises a flow passage FP in which a fluid flows to the outside after successively flowing between an inner ring 21in and a roller 21re of the first bearing 21, in the annular space CR, between an inner ring 22in and a roller 22re of the second bearing 22 and between a face 42apf of the protrusion 42ap and the second bearing 22.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a motor. [Background technology]

[0002] 2. Description of the Related Art Some motors, such as the motor described in Patent Document 1, include a shaft and a bearing that supports the shaft so that the shaft can rotate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-75890 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the temperature of the bearings rises during operation of the motor, there is a risk that the durability of the bearings will be adversely affected, for example, by volatilizing the grease provided in the bearings, etc. Therefore, in motors, there is a demand for suppressing the rise in bearing temperature.

[0005] Therefore, an object of the present invention is to provide a motor capable of suppressing an increase in temperature of the bearings. [Means for solving the problem]

[0006] (1): The motor according to the present invention includes a cylinder, a shaft, an annular space formed between the inner circumferential surface of the cylinder and the outer circumferential surface of the shaft, a first bearing having an inner ring, rolling elements, and an outer ring fixed to the shaft, a second bearing having an inner ring, rolling elements, and an outer ring fixed to the shaft, a stator fixed to the cylinder, a rotor having a protruding portion facing the second bearing and having an inner circumferential portion fixed to the shaft, an outer circumferential portion surrounding the stator, and a magnet fixed to the outer circumferential portion, and a substrate fixed to a portion of the cylinder between the stator and the first bearing in the longitudinal direction of the shaft. The motor according to the present invention further includes a flow path through which a fluid flows in the order of between the inner ring of the first bearing and the rolling elements of the first bearing, the annular space, between the inner ring of the second bearing and the rolling elements of the second bearing, and between the surface of the protruding portion of the rotor and the second bearing, and then flows out to the outside.

[0007] (2): In (1), the first bearing may have an outer diameter larger than that of the second bearing in the radial direction, and the inner surface of the outer ring of the second bearing may be on the shaft side in the radial direction relative to the inner surface of the outer ring of the first bearing.

[0008] (3): In (1) or (2), an inner circumferential surface of the cylinder may be on the shaft side relative to an inner surface of an outer ring of the first bearing in a radial direction.

[0009] (4): In any of (1) to (3), the second bearing may be provided with a cover covering the rolling elements of the second bearing, and a gap through which the fluid passes may be formed between the cover of the second bearing and an inner ring of the second bearing in the radial direction, and the internal space of the second bearing may be open toward a surface of the protruding portion of the rotor through the gap.

[0010] (5): In (4), the gap may be located on the shaft side relative to an inner circumferential surface of the cylinder in the radial direction.

[0011] (6): In any one of (1) to (5), a dimension of an inner surface of an outer ring of the second bearing may be larger than a center dimension of the first bearing.

[0012] (7): In any of (1) to (6), the fluid may flow out to the outside by passing between the outer wall of the stator insulator and the inner surface of the magnet, and between the end of the magnet on the first bearing side and the substrate.

[0013] (8): In any one of (1) to (7), the fluid may flow to the outside through a through hole of the rotor. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view of a motor according to an embodiment of the present invention, as viewed from one side in the longitudinal direction of a shaft. [Diagram 2] 2 is a perspective view of the motor shown in FIG. 1 as viewed from the other side in the longitudinal direction of the shaft. [Diagram 3] 2 is a cross-sectional view of the motor shown in FIG. 1 taken along the longitudinal direction of the shaft. [Figure 4] 4 is an enlarged view of a first bearing and its vicinity shown in FIG. 3. [Diagram 5] 4 is an enlarged view of the second bearing and its vicinity shown in FIG. 3. [Figure 6] 4 is an enlarged view of the magnet and its vicinity shown in FIG. 3. FIG. [Figure 7] 4 is a cross-sectional view showing a modified example of the motor shown in FIG. 3. [Figure 8] 4 is a cross-sectional view showing another modified example of the motor shown in FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, embodiments of the motor according to the present invention will be described with reference to the accompanying drawings. The embodiments exemplified below are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention can be modified or improved from the following embodiments without departing from the spirit of the present invention. In addition, in the above-mentioned accompanying drawings, the dimensions of each component may be exaggerated or reduced, and hatching may be omitted, in order to facilitate understanding.

[0016] Fig. 1 is a perspective view of a motor according to an embodiment, seen from one side in the longitudinal direction of a shaft (hereinafter simply referred to as the "longitudinal direction"). Fig. 2 is a perspective view of the motor shown in Fig. 1, seen from the other side in the longitudinal direction. Fig. 3 is a cross-sectional view of the motor shown in Fig. 1 along the longitudinal direction (which in this embodiment is the same as the direction of the rotation axis).

[0017] As shown in Fig. 1 to Fig. 3, the motor 1 according to the embodiment has a tubular (cylindrical in the present embodiment) outer shape, and includes a shaft 20, a bearing holder 12, a first bearing 21, a second bearing 22, a stator 30, and a rotor 40 as main components. The shaft 20 passes through the center of the motor 1, and includes one end 20a and the other end 20b. That is, Fig. 1 is a view of the shaft 20 as seen from the side of the one end 20a, and Fig. 2 is a view of the shaft 20 as seen from the side of the other end 20b. In the longitudinal direction, the first bearing 21 is on the side of the other end 20b, and the second bearing 22 is on the side of the one end 20a.

[0018] The bearing holder 12 is a tubular member located at the center of the motor 1, and in this embodiment, is a cylindrical member. Therefore, the bearing holder 12 can also be referred to as a tube 12. As shown in FIG. 3, the bearing holder 12 includes a first portion 16, a second portion 14, and a third portion 13. In the longitudinal direction, the first portion 16, the second portion 14, and the third portion 13 are arranged in this order from the other end 20b side toward the one end 20a side. The shaft 20 is located in the center of the internal space of the bearing holder 12.

[0019] The first portion 16 of the bearing holder 12 has the largest outer shape among the first portion 16, the second portion 14, and the third portion 13 in the radial direction perpendicular to the longitudinal direction, and specifically has a cylindrical shape with the largest inner and outer diameters. In the radial direction, the side relatively closer to the shaft 20 may be referred to as the "inner" side, and the side relatively farther from the shaft 20 may be referred to as the "outer" side. In this embodiment, the first portion 16 has a length of approximately 1 / 4 of the total length in the longitudinal direction of the bearing holder 12, but is not limited to this. The upper end surface 16uf of the first portion 16 (the surface on the side of one end 20a in the longitudinal direction) is flat in the radial direction and is connected to the outer circumferential surface 13of of the third portion 13 approximately perpendicularly.

[0020] The third portion 13 of the bearing holder 12 has an outer shape smaller than that of the first portion 16 in the radial direction, and has a cylindrical outer shape. Specifically, the outer diameter of the third portion 13 is smaller than that of the first portion 16, and the inner diameter of the third portion 13 is smaller than that of the first portion 16. In this embodiment, the third portion 13 has a length of about 1 / 2 of the total length in the longitudinal direction of the bearing holder 12, but is not limited to this. The portion of the outer peripheral surface 13of of the third portion 13 on the side of one end 20a in the longitudinal direction is located inside (toward the shaft 20) more than the portion on the side of the other end 20b. That is, the boundary between the portion of the outer peripheral surface 13of of the third portion 13 on the side of one end 20a and the portion on the side of the other end 20b is a step surface 13sf that is flat in the radial direction. An outer circumferential surface 20op of the shaft 20 passing through the internal space of the bearing holder 12 and an inner circumferential surface 13if of the third portion 13 are separated in the radial direction. That is, an annular space CR is formed between the inner circumferential surface 13if of the cylinder 12 and the outer circumferential surface 20op of the shaft 20.

[0021] Fig. 4 is an enlarged view of the first bearing 21 and its vicinity. As shown in Fig. 4, a lower end surface 13df (surface on the other end 20b side in the longitudinal direction) of the third portion 13 of the bearing holder 12 is formed flat in the radial direction. The lower end surface 13df of the third portion 13 is connected to an inner peripheral surface 16if of the first portion 16 substantially perpendicularly.

[0022] 3, the second portion 14 of the bearing holder 12 has an outer diameter that is the same as the outer diameter of the portion of the third portion 13 on the one end 20a side relative to the step surface 13sf, and an inner diameter that is greater than the inner diameter of the third portion 13. Therefore, in this embodiment, the outer peripheral surface of the second portion 14 is formed flush with the portion of the outer peripheral surface 13of of the third portion 13 on the one end 20a side relative to the step surface 13sf. In the embodiment, the second portion 14 has a length of approximately ¼ of the entire length of the bearing holder 12 in the longitudinal direction, but is not limited to this.

[0023] Fig. 5 is an enlarged view of the second bearing 22 and its vicinity. As shown in Fig. 5, the inner circumferential surface 14if of the second portion 14 of the bearing holder 12 is connected approximately perpendicularly to the upper end surface 13uf (the surface on the side of one end portion 20a in the longitudinal direction) of the third portion 13, which is flat in the radial direction.

[0024] As shown in FIG. 3 and FIG. 4, the first bearing 21 is a ball bearing including one inner ring 21in, a plurality of rolling elements 21re, and one outer ring 21ou. The plurality of rolling elements 21re are located between the inner ring 21in and the outer ring 21ou in the radial direction. In the radial direction, the first bearing 21 has a larger outer shape than the second bearing 22. Most of the first bearing 21 is accommodated inside the first part 16 of the bearing holder 12. Specifically, most of the first bearing 21 is located in a space surrounded by the inner circumferential surface 16if of the first part 16 of the bearing holder 12, the lower end surface 13df of the third part 13 of the bearing holder 12, and the outer circumferential surface 20op of the shaft 20. In the radial direction, the outer surface of the outer ring 21ou faces and is close to the inner circumferential surface 16if of the first part 16 of the bearing holder 12. In the longitudinal direction, there is a gap between the first bearing 21 and the lower end surface 13df of the third portion 13 of the bearing holder 12, and a ring-shaped spring member 17 is disposed in this gap. The outer ring 21ou is supported by the lower end surface 13df of the third portion 13 of the bearing holder 12 via this spring member 17. In the radial direction, the inner circumferential surface 13if of the third portion 13 of the bearing holder 12 (cylinder 12) is located inside (on the shaft 20 side) with respect to the inner surface 21ouf of the outer ring 21ou.

[0025] The lower end of the first bearing 21 (the end on the other end 20b side in the longitudinal direction) and the nearby portion thereof protrude from the bearing holder 12 toward the other end 20b side, and are exposed to the external space of the motor 1. The shaft 20 is provided with a protrusion 18 that protrudes from the outer circumferential surface 20op of the shaft 20 toward the outside in the radial direction (the side opposite to the shaft 20 side). The protrusion 18 is not particularly limited, and may be, for example, a C-ring or an O-ring. The lower end of the inner ring 21in of the first bearing 21 is supported by contacting the protrusion 18 in the rotation axis direction (longitudinal direction), thereby positioning the inner ring 21in in the longitudinal direction. The inner ring 21in is attached to the shaft 20 by, for example, a clearance fit.

[0026] In this embodiment, the first bearing 21 is supported by the bearing holder 12 in the above manner. Specifically, the outer ring 21ou is supported so as not to rotate relative to the bearing holder 12, and the inner ring 21in is supported so as to be rotatable relative to the bearing holder 12 and the outer ring 21ou as the shaft 20 rotates. Note that the means for supporting the first bearing 21 on the bearing holder 12 is not limited to the above. For example, the protruding portion 18 may not be provided, and the inner ring 21in may be attached to the shaft 20 by an interference fit.

[0027] At the lower end of the first bearing 21 (the end on the other end 20b side of the first bearing 21 in the longitudinal direction), a ring-shaped cover 21dc extends radially from the inner surface 21ouf of the outer ring 21ou toward the inside (the shaft 20 side). This cover 21dc covers the rolling element 21re on the other end 20b side in the longitudinal direction. In the radial direction, the end of the cover 21dc faces the outer surface 21inf of the inner ring 21in, and a gap 21dcg through which air, which is a fluid, can pass is formed between the inner ring 21in of the first bearing 21 and the cover 21dc. The external space of the motor 1 and the internal space of the first bearing 21 communicate with each other through the gap 21dcg. The internal space of the first bearing 21 includes a gap between the inner ring 21in and the multiple rolling elements 21re and a gap between the outer ring 21ou and the multiple rolling elements 21re.

[0028] In addition, at the upper end of the first bearing 21 (the end on the side of one end 20a of the first bearing 21 in the longitudinal direction), a ring-shaped cover 21uc extends radially inward from the inner surface 21ouf of the outer ring 21ou. This cover 21uc covers the rolling element 21re on the side of one end 20a in the longitudinal direction. In the radial direction, the end of the cover 21uc faces the outer surface 21inf of the inner ring 21in, and a gap 21ucg through which air, which is a fluid, can pass is formed between the inner ring 21in of the first bearing 21 and the cover 21uc. The internal space of the first bearing 21 and the above-mentioned annular space CR are communicated through the gap 21ucg. In this embodiment, in the radial direction, the outer surface 21inf of the inner ring 21in of the first bearing 21 is located inside (on the side of the shaft 20) with respect to the inner circumferential surface 13if of the third portion 13 of the bearing holder 12. Therefore, the area directly above the gap 21ucg is not covered by the lower end surface 13df of the third portion 13 of the bearing holder 12, and the gap 21ucg directly communicates with the annular space CR.

[0029] As shown in FIG. 3 and FIG. 5, the second bearing 22 is a ball bearing including one inner ring 22in, multiple rolling elements 22re, and one outer ring 22ou. The multiple rolling elements 22re are located between the inner ring 22in and the outer ring 22ou in the radial direction. In the radial direction, the second bearing 22 has a smaller outer diameter than the first bearing 21. The inner surface 22ouf of the outer ring 22ou of the second bearing 22 is located inside (on the shaft 20 side) with respect to the inner surface 21ouf of the outer ring 21ou of the first bearing 21. Here, the dimension obtained by adding the inner diameter dimension and the outer diameter dimension of the bearing and dividing the sum by 2 is defined as the "center dimension". In FIG. 3, a line CD extending in the rotation axis direction (longitudinal direction) of the portion corresponding to the center dimension of the first bearing 21 is shown by a dashed line. As shown in FIG. 3, in this embodiment, the dimension of the inner surface 22ouf of the outer ring 22ou of the second bearing 22 is larger than the center dimension of the first bearing 21.

[0030] The second bearing 22 is accommodated inside the second part 14 of the bearing holder 12. Specifically, the second bearing 22 is in a space surrounded by the inner circumferential surface 14if of the second part 14 of the bearing holder 12, the upper end surface 13uf of the third part 13 of the bearing holder 12, and the outer circumferential surface 20op of the shaft 20. In the radial direction, the outer surface of the outer ring 22ou faces and is close to the inner circumferential surface 14if of the second part 14 of the bearing holder 12. The lower end surface of the outer ring 22ou (the surface on the side of the other end 20b in the longitudinal direction) is placed on the upper end surface 13uf of the third part 13 of the bearing holder 12. The outer ring 22ou may be fixed to the bearing holder 12 by, for example, bonding the outer surface to the inner circumferential surface 14if of the second part 14 of the bearing holder 12 and bonding the lower end surface to the upper end surface 13uf of the third part 13 of the bearing holder 12. On the other hand, the inner ring 22in is attached to the shaft 20 by, for example, a clearance fit.

[0031] In this embodiment, the second bearing 22 is supported by the bearing holder 12 in the above manner. Specifically, the outer ring 22ou is supported so as not to rotate relative to the bearing holder 12, and the inner ring 22in is supported so as to be rotatable relative to the bearing holder 12 and the outer ring 22ou in conjunction with the rotation of the shaft 20. Note that the means for supporting the second bearing 22 by the bearing holder 12 is not limited to the above.

[0032] At the lower end of the second bearing 22 (the end on the other end 20b side of the second bearing 22 in the longitudinal direction), a ring-shaped cover 22dc extends radially from the inner surface 22ouf of the outer ring 22ou toward the inside (the shaft 20 side). This cover 22dc covers the rolling elements 22re on the other end 20b side in the longitudinal direction. In the radial direction, the end of the cover 22dc faces the outer surface 22inf of the inner ring 22in, and a gap 22dcg through which air, which is a fluid, can pass is formed between the inner ring 22in of the second bearing 22 and the cover 22dc. The annular space CR and the internal space of the second bearing 22 communicate with each other through the gap 22dcg. The internal space of the second bearing 22 includes a gap between the inner ring 22in and the multiple rolling elements 22re and a gap between the outer ring 22ou and the multiple rolling elements 22re.

[0033] In addition, at the upper end of the second bearing 22 (the end on the side of one end 20a of the second bearing 22 in the longitudinal direction), a ring-shaped cover 22uc extends radially inward from the inner surface 22ouf of the outer ring 22ou. This cover 22uc covers the rolling elements 22re on the side of one end 20a in the longitudinal direction. In the radial direction, the end of the cover 22uc faces the outer surface 22inf of the inner ring 22in, and a gap 22ucg through which air, which is a fluid, can pass is formed between the inner ring 22in of the second bearing 22 and the cover 22uc.

[0034] In the radial direction, the above-mentioned gaps 22dcg, 22ucg are located on the inner side (shaft 20 side) of the inner circumferential surface 13if of the third portion 13 of the bearing holder 12 (cylinder 12).

[0035] As shown in FIG. 3, the rotor 40 has a holder 41 and a magnet 44. The holder 41 is formed of a magnetic material and includes a tubular (cylindrical in this embodiment) tubular portion 43 and an annular portion 42 formed integrally with the tubular portion 43. The tubular portion 43 is a portion on the outer periphery of the rotor 40, and is the outer periphery of the rotor 40. In the radial direction, the tubular portion 43 (outer periphery portion 43) surrounds the stator 30. The annular portion 42 is annular when viewed in the longitudinal direction, and extends radially from an end portion on the side of one end portion 20a in the longitudinal direction of the tubular portion 43 toward the inside (shaft 20 side). One end portion 20a of the shaft 20 is fixed to the inner periphery portion 42a of the annular portion 42 by, for example, press-fitting. Therefore, the holder 41 and the shaft 20 rotate integrally. In the longitudinal direction, the annular portion 42 is located on the side of one end 20a relative to the second bearing 22, the bearing holder 12, the magnet 44, and the stator 30. In the longitudinal direction, a space G1 extending in the radial direction is formed between the second bearing 22, the bearing holder 12, the magnet 44, the stator 30, and the annular portion 42.

[0036] The inner circumferential portion 42a of the annular portion 42 has a protruding portion 42ap that protrudes toward the second bearing 22 (the other end portion 20b side) in the longitudinal direction. In the longitudinal direction, the protruding portion 42ap is on the side of one end portion 20a with respect to the second bearing 22 and faces the second bearing 22. The shaft 20 is fixed to the inner circumferential surface of the protruding portion 42ap.

[0037] As shown in Fig. 5, the protruding portion 42ap of the inner circumferential portion 42a of the rotor 40 includes a surface (opposing surface 42apf) that faces the upper end surface of the second bearing 22. More specifically, the opposing surface 42apf faces the cover 22uc of the second bearing 22 at a predetermined distance in the longitudinal direction to form a space G12, and the space G12 and the gap 22ucg are in communication with each other. That is, the internal space of the second bearing 22 is opened toward the opposing surface 42apf of the protruding portion 42ap of the rotor 40 through the gap 22ucg of the second bearing 22. The above-mentioned space G1 is in communication with the space G12 between the opposing surface 42apf and the second bearing 22.

[0038] FIG. 6 is an enlarged view of the magnet and its vicinity. As shown in FIG. 3 and FIG. 6, the cylindrical portion 43 (outer peripheral portion 43) extends from the outer end of the annular portion 42 toward the other end 20b in the longitudinal direction. The magnet 44 has an annular shape and is fixed to the inner peripheral surface of the cylindrical portion 43 (outer peripheral portion 43). In addition, in this magnet 44, a plurality of different magnetic poles (N poles and S poles) are alternately formed along the circumferential direction. In the radial direction, the inner peripheral surface 44if of the magnet 44 faces the stator 30 via the air gap G2. The magnet 44 is disposed at a distance from the annular portion 42 in the longitudinal direction. In addition, in the longitudinal direction, the end 44de of the magnet 44 (the end on the side of the other end 20b in the longitudinal direction) is on the other end 20b side with respect to the lower end surface of the cylindrical portion 43.

[0039] As shown in Fig. 3, the stator 30 is formed in a cylindrical shape and is formed in a ring shape when viewed in the longitudinal direction. An inner peripheral portion 30ip of the stator 30 is close to an outer peripheral surface 13of of the third portion 13 of the bearing holder 12, and a lower end portion 30ipd of the inner peripheral portion 30ip of the stator 30 is placed on a step surface 13sf of the outer peripheral surface 13of and supported by the step surface 13sf. The stator 30 is fixed to the bearing holder 12 by, for example, bonding the inner peripheral portion 30ip to the outer peripheral surface 13of of the third portion 13 of the bearing holder 12 and the step surface 13sf of the outer peripheral surface 13of.

[0040] The stator 30 includes a stator core 37 formed by stacking a plurality of magnetic bodies such as electromagnetic steel sheets in the longitudinal direction, an insulator 34 surrounding the stator core 37, and a plurality of coils 33 wound around the insulator 34. The stator core 37 includes an annular portion (core) 31 concentric with the shaft 20, and a plurality of teeth (magnetic pole portions) 32 formed to extend radially outward from the annular portion 31. At least a portion of the annular portion 31 and the teeth 32 are covered by the insulator 34. The plurality of coils 33 are wound around the insulator 34 that covers each of the plurality of teeth 32. In this way, the stator core 37 and the plurality of coils 33 are insulated from each other.

[0041] In this embodiment, the insulator 34 includes a main body portion 34a extending radially and around which the coil 33 is wound, a first convex portion 34b protruding from the outer periphery of the main body portion 34a toward one end 20a in the longitudinal direction, a second convex portion 34c protruding from the inner periphery of the main body portion 34a toward one end 20a in the longitudinal direction, a third convex portion 34d protruding from the outer periphery of the main body portion 34a toward the other end 20b in the longitudinal direction, and a fourth convex portion 34e protruding from the inner periphery of the main body portion 34a toward the other end 20b in the longitudinal direction.

[0042] The insulator 34 does not necessarily have to be provided with the first convex portion 34b, the second convex portion 34c, the third convex portion 34d, and the fourth convex portion 34e. Alternatively, the insulator 34 may be provided with one, two, or three of the first convex portion 34b, the second convex portion 34c, the third convex portion 34d, and the fourth convex portion 34e. However, for reasons described below, it is preferable to provide at least one of the first convex portion 34b and the third convex portion 34d.

[0043] As shown in FIG. 6, the outer peripheral wall 34ow of the insulator 34 is located on the inner side (shaft 20 side) of the magnet 44 in the radial direction, and faces the inner peripheral surface 44if of the magnet 44 via the air gap G2. The outer peripheral wall 34ow includes the outer peripheral wall of the first convex portion 34b and the outer peripheral wall of the third convex portion 34d. An opening is formed in the outer peripheral wall 34ow, and the outer peripheral portions of the teeth 32 of the stator core 37 are exposed from the opening. That is, the outer peripheral portions of the teeth 32 face the inner peripheral surface 44if of the magnet 44 via the air gap G2. In this embodiment, the outer peripheral wall 34ow of the insulator 34 and the outer peripheral portions of the teeth 32 exposed from the outer peripheral wall 34ow of the insulator 34 are generally flush with each other, but this is not limited thereto.

[0044] As shown in Figs. 2 and 3, the substrate 15 is formed in a disk shape. An inner peripheral portion 15ip ​​of the substrate 15 is placed on an upper end surface 16uf of the first portion 16 of the bearing holder 12, and is close to an outer peripheral surface 13of of the third portion 13 of the bearing holder 12, and is fixed to the bearing holder 12. As shown in Fig. 6, the substrate 15 extends in the radial direction to a position outside the cylindrical portion 43 of the holder 41. The substrate 15 and the holder 41 roughly define the internal space of the motor 1, and the entire stator 30 is accommodated in the internal space of the motor 1. In the longitudinal direction, the substrate 15 and the end 44de of the magnet 44 face each other in the rotation axis direction (longitudinal direction), forming a gap G3, and the internal space of the motor 1 communicates with the external space of the motor 1 through the gap G3. For example, a connector (not shown) is connected to a lower surface (surface on the other end 20b side in the longitudinal direction) 15df (see FIG. 2) of the substrate 15. Electric power may be supplied to the substrate 15 and the multiple coils 33 via this connector.

[0045] As shown in FIGS. 1 and 2, the shaft 20 passes through the substrate 15 and the first portion 16 of the bearing holder 12, and the other end 20b of the shaft 20 is exposed to the external space of the motor 1.

[0046] When a current is supplied to the coil 33 of the motor 1 having such a configuration, a magnetic interaction occurs between the coil 33 and the magnet 44, and a force is generated that tries to rotate the rotor 40 relative to the stator 30 and the bearing holder 12. Here, the rotor 40 is fixed to the shaft 20. In addition, the shaft 20 is rotatably supported by the bearings 21 and 22. Therefore, the rotor 40 and the shaft 20 rotate relative to the stator 30 and the bearing holder 12 due to the force that tries to rotate the rotor 40 relative to the stator 30 and the bearing holder 12. In this manner, the motor 1 of this embodiment is configured as an outer rotor type motor.

[0047] When the shaft 20, rotor 40, etc. (which may be collectively referred to as the "rotating body") rotate relative to the stator 30, bearing holder 12, etc. (which may be collectively referred to as the "stationary body") as described above, a fluid flow (in this embodiment, an air flow that is a flow of air) is generated by the centrifugal force caused by the rotation of the rotating body. This fluid flow (air flow) tends to be stronger on the side closer to the rotating body. Note that in this embodiment, the rotating body includes the shaft 20, rotor 40, inner ring 21in of the first bearing 21, and inner ring 22in of the second bearing 22, and the stationary body includes the stator 30, bearing holder 12, outer ring 21ou of the first bearing 21, and outer ring 22ou of the second bearing 22.

[0048] When the shaft 20, which is a rotating body, rotates, the centrifugal force of the shaft 20 generates an air flow (fluid flow) that flows along the longitudinal direction around the other end 20b side of the shaft 20 that is exposed to the external space of the motor 1. That is, air outside the motor 1 flows along the longitudinal direction near the shaft 20 toward the first bearing 21. This air flow is shown by dashed lines in Figures 3 to 6. Note that the dashed lines in Figures 3 to 6 are intended to diagrammatically represent the flow rate of the air flow in the internal space of the motor 1, and are not intended to limit the area through which the air flow flows.

[0049] As described above and as shown in FIG. 4, a gap 21dcg is formed between the inner ring 21in of the first bearing 21 and the cover 21dc. That is, in this embodiment, the gap 21dcg, which is an inlet to the internal space of the first bearing 21, is formed near the shaft 20 and the inner ring 21in, which are rotating bodies. Therefore, the air flow of the air outside the motor 1 can flow into the internal space of the first bearing 21 from this gap 21dcg. Furthermore, since the gap 21dcg is formed near the rotating body, this air flow is more likely to flow into the internal space of the first bearing 21 than when, for example, the gap is formed between the outer ring 21ou of the first bearing 21 and the cover 21dc (i.e., the side farther from the rotating body or the side closer to the stationary body). The air flow that flows into the internal space of the first bearing 21 flows mainly in the vicinity of the inner ring 21in, which is a rotating body, where the centrifugal force of the inner ring 21in is likely to affect, i.e., between the inner ring 21in and the multiple rolling bodies 21re, toward the cover 21uc.

[0050] As described above and as shown in FIG. 4, a gap 21ucg is formed between the inner ring 21in of the first bearing 21 and the cover 21uc. That is, in this embodiment, the gap 21ucg, which is an outlet from the first bearing 21, is formed near the inner ring 21in, which is a rotating body. Therefore, the air flow that flows through the internal space of the first bearing 21 can flow into this gap 21ucg. Furthermore, since the gap 21ucg is formed near the rotating body, this air flow is more likely to flow out of the internal space of the first bearing 21 than when a gap is formed, for example, between the outer ring 21ou of the first bearing 21 and the cover 21dc (i.e., on the side farther from the rotating body or closer to the stationary body). As described above, in this embodiment, the area directly above the gap 21ucg is not covered by the lower end surface 13df of the third portion 13 of the bearing holder 12, that is, the inner circumferential surface 13if and the gap 21ucg are disposed apart in the radial direction, so that the gap 21ucg directly communicates with the annular space CR in the rotation axis direction (longitudinal direction). Therefore, the air flow that has flowed through the internal space of the first bearing 21 can easily flow out from the gap 21ucg into the annular space CR.

[0051] As shown in FIG. 3, the airflow that has flowed into the annular space CR from the gap 21ucg flows mainly in the longitudinal direction toward the second bearing 22 near the shaft 20, which is a rotating body and is easily affected by the centrifugal force of the shaft 20.

[0052] As described above and as shown in FIG. 5, a gap 22dcg is formed between the inner ring 22in and the cover 22dc of the second bearing 22. That is, in this embodiment, the gap 22dcg, which is an inlet to the internal space of the second bearing 22, is formed near the shaft 20 and the inner ring 22in, which are the rotating bodies. Therefore, the air flow that has flowed through the annular space CR can flow into the internal space of the second bearing 22 from this gap 22dcg. Furthermore, since the gap 22dcg is formed near the rotating body, this air flow is more likely to flow into the internal space of the second bearing 22 than when, for example, the gap is formed between the outer ring 22ou and the cover 22dc of the second bearing 22 (i.e., the side farther from the rotating body or the side closer to the stationary body). The air flow that flows into the internal space of the second bearing 22 flows mainly in the vicinity of the inner ring 22in, which is a rotating body, where the centrifugal force of the inner ring 22in is likely to affect, i.e., between the inner ring 22in and the multiple rolling bodies 22re, toward the cover 22uc.

[0053] As described above and as shown in FIG. 5, a gap 22ucg is formed between the inner ring 22in and the cover 22uc of the second bearing 22. That is, in this embodiment, the gap 22ucg, which is an outlet from the second bearing 22, is formed near the inner ring 22in, which is a rotating body. Therefore, the air flow that flows through the internal space of the second bearing 22 can flow into this gap 22ucg. Furthermore, since the gap 22ucg is formed near the rotating body, this air flow is more likely to flow out of the internal space of the second bearing 22 than when a gap is formed, for example, between the outer ring 22ou and the cover 22dc of the second bearing 22 (i.e., the side farther from the rotating body or the side closer to the stationary body). Also, as described above, in this embodiment, the internal space of the second bearing 22 is opened toward the surface (opposing surface 42apf) of the protruding portion 42ap of the rotor 40 through the gap 22ucg. Therefore, the air flow that has flowed through the internal space of the second bearing 22 can flow out from the gap 22ucg through the space G12 between the opposing surface 42apf and the second bearing 22 into the space G1.

[0054] 3 and 5, the airflow flowing out into the space G1 mainly flows through an area of ​​the space G1 where the centrifugal force of the rotor 40, which is a rotating body, is likely to act (i.e., near the rotating body). Specifically, the airflow flows radially outward between the opposing surface 42apf of the protruding portion 42ap of the rotor 40 and the second bearing 22, then flows approximately longitudinally toward one end 20a near the side surface 42aps of the protruding portion 42ap of the rotor 40, then flows radially outward near the inner surface 41if of the holder 41 of the rotor 40, and then flows approximately longitudinally toward the other end 20b near the inner surface 41if of the holder 41 and near the inner surface 44if of the magnet 44 of the rotor 40.

[0055] As described above, the insulator 34 includes the first protrusion 34b protruding from the outer periphery of the main body 34a toward the one end 20a in the longitudinal direction. Therefore, the air flow that flows in the vicinity of the inner periphery 44if of the magnet 44 along the longitudinal direction toward the other end 20b is guided by the first protrusion 34b and led to the air gap G2 between the insulator 34 and the inner periphery 44if of the magnet 44, as shown in FIG. 6. In this way, the air flow that flows in the space G1 flows through the air gap G2 along the longitudinal direction toward the other end 20b. Also, as described above, the insulator 34 includes the third protrusion 34d protruding from the outer periphery of the main body 34a toward the other end 20b in the longitudinal direction. Therefore, the air flow that has flowed through the air gap G2 is guided by the third protrusion 34d, flows out of the air gap G2, and then flows along the inner circumferential surface 44if of the magnet 44 toward the side of the substrate 15. Here, as described above and as shown in FIG. 6, a gap G3 is formed between the end 44de of the magnet 44 and the substrate 15, and this gap G3 connects the internal space of the motor 1 to the external space of the motor 1. Therefore, the air flow that has flowed out of the air gap G2 and along the inner circumferential surface 44if of the magnet 44 flows radially outward in the gap G3 due to the centrifugal force generated by the rotation of the magnet 44, which is a rotating body, and flows out to the outside of the motor 1.

[0056] As shown in Fig. 3, the motor 1 further includes a flow path FP through which the fluid flows in the order of between the inner ring 21in of the first bearing 21 and the rolling element 21re of the first bearing 21 (gap 21dcg, gap 21ucg), the annular space CR, between the inner ring 22in of the second bearing 22 and the rolling element 22re of the second bearing 22 (gap 22dcg, gap 22ucg), and between the opposing surface 42apf of the protruding portion 42ap of the rotor 40 and the second bearing 22, and then flows out to the outside. More specifically, the flow path FP includes an air gap G2 and a gap G3. Therefore, the air flow (fluid) flowing in the motor 1 flows out to the outside through the gap between the outer peripheral wall 34ow of the insulator 34 of the stator 30 and the inner peripheral surface 44if of the magnet 44, and between the end 44de of the magnet 44 on the first bearing 21 side and the substrate 15. 6, the radially outer surface of the stator 30 is exposed and not covered by the insulator 34. Therefore, air flows between the radially outer surface of the stator 30 and the inner circumferential surface 44if of the magnet 44, so that the temperature rise of the stator 30 can be suppressed.

[0057] As described above, the motor 1 of this embodiment includes the cylinder 12 (bearing holder), the shaft 20, an annular space CR formed between the inner surface 13if of the cylinder 12 and the outer surface 20op of the shaft 20, a first bearing 21 having an inner ring 21in, rolling elements 21re, and an outer ring 21ou fixed to the shaft 20, a second bearing 22 having an inner ring 22in, rolling elements 22re, and an outer ring 22ou fixed to the shaft 20, a stator 30 fixed to the cylinder 12, a rotor 40 having a protrusion 42ap facing the second bearing 22 and an inner peripheral portion 42a fixed to the shaft 20, an outer peripheral portion 43 surrounding the stator 30, and a magnet 44 fixed to the outer peripheral portion 43, and a substrate 15 fixed to a portion of the cylinder 12 between the stator 30 and the first bearing 21 in the longitudinal direction of the shaft 20. In addition, the motor 1 further includes a flow path FP through which a fluid (air) flows in the following order: between the inner ring 21in of the first bearing 21 and the rolling element 21re of the first bearing 21 (gap 21dcg, gap 21ucg), the annular space CR, between the inner ring 22in of the second bearing 22 and the rolling element 22re of the second bearing 22 (gap 22dcg, gap 22ucg), and between the opposing surface 42apf of the protrusion 42ap of the rotor 40 and the second bearing 22, and then flows out to the outside.

[0058] According to the motor 1 having the above configuration, since it is provided with the above-mentioned fluid flow path FP, when the rotor rotates, the fluid (air) outside the motor 1 flows through the internal space of the first bearing 21 and then the internal space of the second bearing 22, and then flows out to the outside. Therefore, according to the motor 1, the first bearing 21 and the second bearing 22 can be cooled by the fluid (air), and it is possible to suppress the temperature rise of the bearings. As a result, in the motor 1, the volatilization of grease in the bearings is suppressed, and the life of the bearings and therefore the life of the motor can be extended.

[0059] Furthermore, in the motor 1, the first bearing 21 outside the holder 41 of the rotor 40 has a larger outer diameter in the radial direction than the second bearing 22 inside the holder 41. This makes it possible to ensure a wide coil winding area while ensuring rotational stability.

[0060] Although the present invention has been described above by taking the above embodiment as an example, the present invention is not limited to this.

[0061] For example, a motor 1A as shown in FIG. 7 may be configured as a modified example of the motor 1 according to the embodiment. In the motor 1A according to this modified example, instead of the insulator 34 of the motor 1 according to the embodiment, a resin film 134 having insulating properties is provided on the surface of the stator core 37, thereby insulating the stator core 37 from the coils 33. The other configurations of the motor 1A are the same as those of the motor 1. According to such a motor 1A, the number of members constituting the motor can be reduced. On the other hand, when the insulator 34 according to the embodiment is used, the air flow is guided to the air gap G2 by the first convex portion 34b as described above, so that the air flow is more likely to be guided to the air gap G2. In addition, the air flow is guided to the side of the substrate 15 by the third convex portion 34d, so that the air flow is more likely to be guided to the gap G3, which is the outlet from the motor 1.

[0062] As another modification of the motor 1 according to the embodiment, a motor 1B as shown in FIG. 8 may be configured. In the motor 1B according to this modification, a through hole 42Bh is formed in the holder 41 of the rotor 40. This through hole 42Bh penetrates the annular portion 42B of the holder 41 in the longitudinal direction. In other words, in the motor 1B, the holder 41 of the rotor 40 includes the annular portion 42B in which the through hole 42Bh is formed. The other configurations of the motor 1B are similar to those of the motor 1. Inside the motor 1B, as shown by the dashed line in FIG. 8, a flow path FPB is formed, which includes a flow path through which the airflow (fluid) passes through the gap G3 and flows out to the outside of the motor 1B, and a flow path through which the airflow (fluid) passes through the through hole 42Bh of the rotor 40 and flows out to the outside of the motor 1B. Note that the dashed line in FIG. 8 is a schematic representation of the flow rate of the airflow in the internal space of the motor 1, and is not intended to limit the area through which the airflow flows.

[0063] In the above-mentioned embodiment and each modified example, the first bearing 21 is provided with the cover 21dc and the cover 21uc, but at least one of the cover 21dc and the cover 21uc may be omitted. Even in this case, the centrifugal force caused by the rotation of the motor allows the outside air to flow into the annular space CR through the inside of the first bearing 21, mainly through the gap between the inner ring 21in and the rolling element 21re.

[0064] In the above-mentioned embodiment and each modified example, the second bearing 22 is provided with the cover 22dc and the cover 22uc, but at least one of the cover 22dc and the cover 22uc may not be provided. Even in this case, the air flowing in the annular space CR due to the centrifugal force caused by the rotation of the motor can flow into the second bearing 22, mainly through the space between the inner ring 22in and the rolling element 22re, and out to the space between the opposing surface 42apf of the protruding portion 42ap of the rotor 40 and the second bearing 22.

[0065] Furthermore, in the above-described embodiment and each modified example, an outer rotor type motor has been described as an example, but the present invention can also be applied to an inner rotor type motor.

[0066] In addition, those skilled in the art can appropriately modify the motor of the present invention in accordance with conventionally known knowledge. As long as the motor of the present invention is still provided with the configuration of the present invention even after such modification, it is of course included in the scope of the present invention. [Explanation of symbols]

[0067] Reference Signs List 1, 1A, 1B...motor, 12...bearing holder (cylinder), 13if...inner circumferential surface, 15...substrate, 20...shaft, 20op...outer circumferential surface, 21...first bearing, 21in...inner ring, 21ou...outer ring, 21ouf...inner surface, 21re...rolling element, 22...second bearing, 22dc...cover, 22in...inner ring, 22ou...outer ring, 22ouf...inner surface, 22re...rolling element, 22uc...cover, 30...stator, 34...insulator, 34ow...outer circumferential wall, 40...rotor, 42a...inner circumferential portion, 42ap...projection portion, 42apf...opposing surface (surface), 42Bh...through hole, 43...outer circumferential portion, 44...magnet, 44de...end portion, 44if...inner circumferential surface, CR...annular space, FP, FPB...flow path

Claims

1. A cylinder and A shaft, an annular space formed between an inner peripheral surface of the cylinder and an outer peripheral surface of the shaft; a first bearing having an inner ring fixed to the shaft, a rolling element, and an outer ring; a second bearing having an inner ring fixed to the shaft, a rolling element, and an outer ring; A stator fixed to the cylinder; a rotor including an inner periphery having a protruding portion facing the second bearing and fixed to the shaft, an outer periphery surrounding the stator, and a magnet fixed to the outer periphery; a substrate fixed to a portion of the cylinder between the stator and the first bearing in a longitudinal direction of the shaft; Equipped with the motor further comprising a flow path through which a fluid flows in the following order, between an inner ring of the first bearing and the rolling elements of the first bearing, in the annular space, between an inner ring of the second bearing and the rolling elements of the second bearing, and between a surface of the protruding portion of the rotor and the second bearing, before flowing out to the outside.

2. In a radial direction, the first bearing has a larger outer diameter than the second bearing; The motor according to claim 1 , wherein an inner surface of an outer ring of the second bearing is located closer to the shaft in a radial direction than an inner surface of an outer ring of the first bearing.

3. The motor according to claim 2 , wherein an inner circumferential surface of the cylinder is located on the shaft side relative to an inner surface of an outer ring of the first bearing in a radial direction.

4. The second bearing includes a cover that covers a rolling element of the second bearing, a gap through which the fluid passes is formed between a cover of the second bearing and an inner ring of the second bearing in a radial direction, The motor according to claim 3 , wherein an internal space of the second bearing is open toward a surface of the protruding portion of the rotor through the gap.

5. The motor according to claim 4 , wherein the gap is located on the shaft side relative to an inner circumferential surface of the cylinder in a radial direction.

6. The motor according to any one of claims 1 to 5, wherein a dimension of an inner surface of an outer ring of the second bearing is larger than a center dimension of the first bearing.

7. 2. The motor according to claim 1, wherein the fluid passes between an outer peripheral wall of an insulator of the stator and an inner peripheral surface of the magnet, and between an end of the magnet on the first bearing side and the substrate, and flows out to the outside.

8. The motor according to claim 1 , wherein the fluid passes through a through hole of the rotor and flows out to the outside.

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