External Rotor Brushless Motor

Abstract

The outer-rotor type brushless motor (1) includes a shaft (2), a rotor, a stator (4), a cylindrical bushing (6) fixed to one end side of the stator (4), an oil-impregnated bearing (5) disposed on the other end side of the bushing (6), and a washer (7) that rotates integrally with the shaft (2). The bushing (6) includes: a fixing portion (61) having a first end face (6B) opposed to the bearing end face (5B) and a first inner peripheral face (6A) opposed to the outer peripheral face (2A) with a first gap (CA) therebetween, and being fixed to the inner peripheral face (4C) of the core; and a housing portion (64) having a second inner peripheral face (6D) with a diameter larger than that of the first inner peripheral face (6A) on one end side of the fixing portion (61), and an oil-proof treatment is applied to the surface of the bushing (6). The washer (7) is disposed radially inside the second inner peripheral face (6D). A second gap (CB) larger than the first gap (CA) is provided between the bearing end face (5B) and the first end face (6B).

Description

Technical Field

[0001] The present invention relates to an outer-rotor type brushless motor including an oil-impregnated bearing that rotatably supports a shaft. Background Art

[0002] For an outer-rotor type motor, an oil-impregnated bearing is sometimes used as a bearing that rotatably supports a shaft. An oil-impregnated bearing is a bearing in which oil is impregnated inside, and is also called an oil bearing. In this bearing, a viscous oil film is present between two relatively sliding surfaces (that is, between the inner peripheral surface of the oil-impregnated bearing and the outer peripheral surface of the shaft), and the shaft is supported by the pressure of this oil film.

[0003] For an oil-impregnated bearing, if the oil content decreases, it may hinder the smooth rotation of the shaft or shorten the life of the oil-impregnated bearing. Therefore, various structures for suppressing the decrease in the oil content have been proposed. For example, in the motor disclosed in Patent Document 1, a structure is disclosed in which a concave portion is provided radially inside the end face of the oil-impregnated bearing, and a disk-shaped washer that rotates integrally with the shaft is provided in the concave portion. According to Patent Document 1, the oil flowing out along the shaft is scattered by the washer and contacts the inner peripheral surface of the concave portion, and is attracted to the oil-impregnated bearing, thereby suppressing the decrease in the oil content.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2001-061253 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in the motor disclosed in Patent Document 1, a structure for suppressing the decrease in the oil content is not provided outside the concave portion. Therefore, in the motor disclosed in Patent Document 1, the oil scattered outside the concave portion cannot be recovered, and there is room for improvement in further suppressing the decrease in the oil content. In addition, in a motor including an oil-impregnated bearing, when the oil flowing out from the oil-impregnated bearing is not sufficiently recovered, it is preferable to provide a structure for suppressing the leakage of the unrecovered oil to the outside of the motor, and there is also room for improvement in this regard.

[0009] The outer-rotor type brushless motor of the present invention is proposed in view of such problems, and one of its purposes is to suppress the decrease in the oil content of the oil-impregnated bearing and to suppress the leakage of oil to the outside of the motor even when the oil flowing out from the oil-impregnated bearing is not sufficiently recovered. It should be noted that the present invention is not limited to this purpose, and other purposes of the present invention are also to achieve the effects caused by the respective structures shown in the following specific embodiments and effects that cannot be obtained by conventional techniques.

[0010] Solution for Solving the Problem

[0011] The outer rotor type brushless motor of the present invention can be implemented as the following disclosed solutions (application examples) to solve at least a part of the above problems. Each solution after Solution 2 is an option that can be additionally and appropriately selected and can be omitted. Each solution after Solution 2 does not disclose the essential solutions and structures for the present invention.

[0012] Solution 1. The outer rotor type brushless motor of the present invention includes: a rotor that rotates integrally with a shaft; a stator that is disposed on the radially outer side of the shaft and on the radially inner side of the rotor; a cylindrical bushing that is fixed to one end side of the stator and through which the shaft passes; an oil-impregnated bearing that is disposed on the radially inner side of the stator and on the other end side of the bushing, and rotatably supports the shaft; and a washer that is disposed on the end side closer to the oil-impregnated bearing and rotates integrally with the shaft. The bushing includes: a fixing portion that has a first end face and a first inner peripheral surface and is fixed to the inner peripheral surface of the core of the stator, the first end face being disposed opposite to the bearing end face on one end side of the oil-impregnated bearing, and the first inner peripheral surface being disposed opposite to the outer peripheral surface of the shaft with a first gap therebetween; and a receiving portion that has a second inner peripheral surface with a diameter larger than that of the first inner peripheral surface on one end side of the fixing portion, and the bushing is subjected to an oil-proof treatment at least on the first end face and the first inner peripheral surface. The washer is disposed on the radially inner side of the second inner peripheral surface, and a second gap larger than the first gap is provided between the bearing end face and the first end face.

[0013] Solution 2. On the basis of the above Solution 1, preferably, the outer rotor type brushless motor further includes a second washer that is disposed in the second gap and rotates integrally with the shaft.

[0014] Solution 3. On the basis of the above Solution 1 or 2, preferably, the stator includes: a stator core that includes a cylindrical portion having the inner peripheral surface of the core and a plurality of tooth portions that protrude radially outward from the cylindrical portion; a plurality of coils that are formed by winding a winding around each of the plurality of tooth portions; and an insulating layer that is formed by applying an insulating coating to the tooth portions around which the winding is wound. In this case, preferably, the bushing includes a guiding portion that extends axially further from the fixing portion than the core end face of the stator core and against which a jumper wire that connects between the plurality of coils abuts.

[0015] Solution 4. Based on the above Solution 3, preferably, the bushing has a stepped shape in which the outer surface of the guiding portion facing the radially outer side is located on the radially outer side of the inner peripheral surface of the core. In this case, preferably, the plane of the guiding portion facing the other end side abuts against the end surface of the core.

[0016] Solution 5. Based on the above Solution 3 or 4, preferably, a positioning groove extending in the axial direction is provided on the inner peripheral surface of the core. In this case, preferably, in the guiding portion, a concave portion is provided on the second end surface in the same direction as the end surface of the core.

[0017] Solution 6. Based on any one of the above Solutions 3 to 5, preferably, the stator core has six of the tooth portions.

[0018] Solution 7. Based on any one of the above Solutions 1 to 6, preferably, the fixing portion has: a cylindrical base portion having an outer peripheral surface with an outer diameter that can be embedded in the inner peripheral surface of the core; and a convex portion that protrudes from the outer peripheral surface of the base portion, and the fixing portion is press-fitted and fixed to the inner peripheral surface of the core.

[0019] Solution 8. Based on the above Solution 7, preferably, the fixing portion has three or more of the convex portions. In this case, preferably, the three or more convex portions are provided separately from each other in the circumferential direction.

[0020] Advantages of the Invention

[0021] According to the outer-rotor type brushless motor of the present invention, it is possible to suppress a decrease in the oil content of the oil-impregnated bearing. In addition, even when the oil flowing out of the oil-impregnated bearing is not sufficiently recovered, it is possible to suppress the leakage of the oil to the outside of the motor. Description of the Drawings

[0022] Figure 1 is an axial sectional view of the outer-rotor type brushless motor of the embodiment.

[0023] Figure 2 is Figure 1 an enlarged view of part X of

[0024] Figure 3 is a top view obtained by observing the stator core of the stator included in the outer-rotor type brushless motor of Figure 1 from one end side.

[0025] Figure 4 is Figure 1 an enlarged perspective view obtained by observing part Y of

[0026] Figure 5 from one end side. is a perspective view obtained by observingFigure 1 A side view obtained by observing the bushing of the outer rotor type brushless motor. DETAILED DESCRIPTION

[0027] With reference to the accompanying drawings, an outer rotor type brushless motor as an embodiment will be described. The embodiments shown below are merely examples and are not intended to exclude various modifications and technical applications not explicitly shown in the following embodiments. Each structure of the present embodiment can be variously modified and implemented without departing from its gist. In addition, selection can be made as needed, or appropriate combination can be made.

[0028] The outer rotor type brushless motor (hereinafter, simply referred to as "motor") includes: a rotor that rotates integrally with the shaft, and a stator disposed on the radially outer side of the shaft and on the radially inner side of the rotor. The motor of the embodiment is a motor that axially supports the shaft by an oil-impregnated bearing disposed on the radially inner side of the stator, and is characterized in that it includes a bushing provided on one end side of the oil-impregnated bearing in the axial direction.

[0029] In this bushing, an oil-proof treatment is applied to its surface, and the inner peripheral surface (first inner peripheral surface) on the other end side opposite to the one end side is disposed opposite to the outer peripheral surface of the shaft with a first gap therebetween. In addition, the end surface (first end surface) on the other end side of the bushing is disposed opposite to the end surface (bearing end surface) on one end side of the oil-impregnated bearing with a second gap larger than the first gap therebetween. In the motor of the embodiment, by such a bushing, the oil flowing out from the oil-impregnated bearing (hereinafter, also referred to as "outflow oil") is repelled by the oil-proof treated first inner peripheral surface and the first end surface, so that it is not easily introduced into the first gap and is likely to accumulate in the second gap. Thereby, a decrease in the oil content of the oil-impregnated bearing is suppressed.

[0030] In addition, one of the features of the motor of the embodiment is that it includes a washer provided at a position closer to one end side than the oil-impregnated bearing and rotating integrally with the shaft. This washer is disposed at a position radially inside the inner peripheral surface (second inner peripheral surface) on the one end side of the bushing closer to the first inner peripheral surface. The motor of the embodiment scatters the outflow oil by such a washer, thereby suppressing the outflow of the outflow oil to a position axially closer to one end side than the washer and leaking to the outside of the motor. That is, the motor of the embodiment suppresses the intrusion of the outflow oil into the first gap, and also suppresses the outflow of the outflow oil to the outside of the motor even if the outflow oil intrudes into the first gap.

[0031] In the following description, the directions (axial direction, circumferential direction, radial direction) of the motor are determined based on the axis. The axial direction is the direction along the center line of the axis (the long side direction of the axis). In the axial direction, the side where the bushing is provided with respect to the stator is defined as the "one end side", and the other side is defined as the "other end side". The circumferential direction is the direction around the center line of the axis (circumferential direction), and the radial direction is the direction orthogonal to both the axial direction and the circumferential direction.

[0032] [1. Structure]

[0033] Figure 1 is a cross-sectional view of the motor 1 of the present embodiment along the axial direction. As Figure 1 shown, in the motor 1, a shaft 2, a rotor 3, a stator 4, an oil-impregnated bearing 5, a bushing 6, and a washer 7 are provided. It should be noted that in Figure 1 , the bushing 6 is located at a position above the oil-impregnated bearing 5 (one end side) on the paper surface, but the up-down direction of the actual motor 1 is not limited to this. For example, the up-down direction of the motor 1 can be the same as the up-down direction shown in Figure 1 , or can be the direction in which the up-down direction of the paper surface is reversed. That is, for the motor 1, the bushing 6 can also be arranged below the oil-impregnated bearing 5. In this case, the one end side becomes the lower side (gravity direction), and the other end side becomes the upper side. In addition, the axial direction of the shaft 2 is not necessarily the vertical direction, and the motor 1 can also be used in a manner that extends along the horizontal or inclined direction.

[0034] The shaft 2 is a rotating shaft that supports the rotor 3, and also functions as an output shaft for taking out the output (mechanical energy) of the motor 1 to the outside. It should be noted that in Figure 1 and Figure 2 , the shaft 2 is shown in a way that the hatching indicating the cross-section of the shaft 2 is omitted.

[0035] The rotor 3 is a component that rotates integrally with the shaft 2, and has a bottomed cylindrical rotor yoke 31 and magnets 32 fixed to the inner peripheral surface of the rotor yoke 31. The rotor yoke 31 is formed in a shape with the bottom at one end side and the other end side open. A through hole for fixing the shaft 2 in a penetrating state is provided at the center of the bottom of the rotor yoke 31. Thus, the shaft 2 and the rotor yoke 31 (rotor 3) rotate integrally. The magnets 32 are fixed to the inner peripheral surface at a position separated from the bottom of the rotor yoke 31 and rotate integrally with the rotor yoke 31.

[0036] The stator 4 is a component disposed at a position radially outside the shaft 2 and radially inside the rotor 3, and has an inner peripheral surface 4C (hereinafter referred to as "core inner peripheral surface 4C") through which the shaft 2 passes. The stator 4 is fixed to the mounting plate 9, for example, via a metal holder 8 fixed to the other end side of the core inner peripheral surface 4C. The mounting plate 9 is a plate fixed to the housing of the motor 1 (not shown) or a part of the plate constituting the housing. The metal holder 8 is a bottomed cylindrical member that holds the oil-impregnated bearing 5, and the other end side thereof is fixed to the mounting plate 9.

[0037] It should be noted that a structure for restricting the movement of the shaft 2 toward one end side may be provided on the other end side of the metal holder 8. In addition, a substrate (electronic substrate, control substrate) may be attached to the mounting plate 9 with a heat dissipation tape interposed therebetween, for example. Since the stator 4 is fixed to such a mounting plate 9, it is fixed relative to the shaft 2 so as not to be able to rotate relative to each other.

[0038] The stator 4 has a metal stator core 41 and a plurality of coils 45 formed by winding windings W around the stator core 41. The stator 4 of the present embodiment further has an insulating layer 46 (see Figure 2 ). The insulating layer 46 is a film formed by applying an insulating coating to the surface of the stator core 41. In the stator 4 of the present embodiment, the insulation between the stator core 41 and the plurality of coils 45 is achieved by this insulating layer 46.

[0039] That is, for the stator 4 of the embodiment, the insulation between the stator core 41 and the plurality of coils 45 is achieved by forming the insulating layer 46 by applying an insulating coating to the stator core 41 instead of the existing insulating member provided in the stator. By setting the insulation method between the stator core 41 and the coil 45 to coating, the core film thickness of the stator core 41 can be minimized. Therefore, the space between the plurality of tooth portions 43 described later can be ensured to be relatively large. Therefore, the duty factor can be increased and the performance of the motor 1 can be improved.

[0040] The stator core 41 is a laminated core formed by laminating a plurality of steel plates having the same shape, and the shaft 2 passes through the center thereof in a state where the axial direction is aligned with the lamination direction of the steel plates. That is, the above-mentioned core inner peripheral surface 4C is formed on the stator core 41.

[0041] As Figure 3 shown, the stator core 41 has a cylindrical portion 42, a plurality of tooth portions 43, and a plurality of blade portions 44. It should be noted that Figure 3 is a top view obtained by observing the stator core 41 from one end side, and the cross section of the shaft 2 in the case where the shaft 2 passes through the stator core 41 is shown by a dotted line.

[0042] The cylindrical portion 42 is a cylindrical part having the above-mentioned inner core peripheral surface 4C. The inner core peripheral surface 4C is, for example, a cylindrical surface, and its inner diameter is set to be larger than the outer diameter of the shaft 2. The outer peripheral surface of the cylindrical portion 42 can be either a cylindrical surface or a square cylindrical surface. The stator 4 is arranged in such a way that the inner core peripheral surface 4C does not interfere with the shaft 2. It should be noted that a positioning groove 4G may be provided in the cylindrical portion 42, which is formed by recessing a part of the inner core peripheral surface 4C along the axial direction. The positioning groove 4G is provided to easily confirm the reference position of the stator 4 in the circumferential direction during the assembly of the motor 1.

[0043] The tooth portion 43 is a part that protrudes outward in the radial direction from the cylindrical portion 42 and connects the cylindrical portion 42 and the blade portion 44. The tooth portion 43 is, for example, rectangular when viewed from the axial direction. The stator 4 of the present embodiment has six tooth portions 43 arranged at equal intervals in the circumferential direction.

[0044] The blade portion 44 is a part that extends in the circumferential direction at the outer end of the tooth portion 43 and is circular arc-shaped when viewed from the axial direction. The surface of the blade portion 44 facing the radial outside faces the radially inner surface of the magnet 32 of the rotor 3. A plurality of blade portions 44 are respectively provided for each of the plurality of tooth portions 43. That is, the stator 4 of the present embodiment has six blade portions 44.

[0045] The plurality of coils 45 are composed of windings W wound around each of the plurality of tooth portions 43. In other words, the member formed by winding the winding W around the tooth portion 43 is called a coil 45. In the stator 4 of the present embodiment, as Figure 4 shown, six coils 45 are provided corresponding to the number of the above-mentioned tooth portions 43.

[0046] Hereinafter, two coils 45 that are arranged opposite to each other across the shaft 2 among the six coils 45 are also called U-phase coils 45U. In addition, two coils 45 that are different from the U-phase coils 45U and are arranged opposite to each other across the shaft 2 are also called V-phase coils 45V. The remaining two coils 45 are also called W-phase coils 45W. In addition, the tooth portions 43 that are the core materials of the U-phase coils 45U, V-phase coils 45V, and W-phase coils 45W are also called U-phase tooth portions 43U, V-phase tooth portions 43V, and W-phase tooth portions 43W respectively (refer to Figure 3 ).

[0047] A U-phase current is supplied to the U-phase coil 45U, a V-phase current is supplied to the V-phase coil 45V, and a W-phase current is supplied to the W-phase coil 45W. As Figure 4 shown, the coils 45U, 45V, 45W of the same phase are connected to each other by jumper wires Wc provided on the end face 4F (hereinafter, also referred to as "core end face 4F") provided on one end side of the stator core 41. In this way, by continuously winding the coils 45U, 45V, 45W of the same phase via the jumper wires Wc, the wiring operation can be performed efficiently.

[0048] The insulating layer 46 is provided on the tooth portion 43 around which the winding W is wound. The insulating layer 46 is provided, for example, over the entire area of the tooth portion 43. Further, the insulating layer 46 is preferably provided not only on the tooth portion 43 but also on the outer peripheral surface of the cylindrical portion 42 and the core end surface 4F so that the insulation between the winding W and the stator core 41 is more reliable. In the present embodiment, as Figure 2 shown, the insulating layer 46 is provided on the portion of the core end surface 4F other than the radially inner portion of the cylindrical portion 42. Hereinafter, this radially inner portion will also be referred to as the non-coated portion 47. The non-coated portion 47 is utilized as a portion for holding the stator core 41 when insulating coating is performed.

[0049] The oil-impregnated bearing 5 is a cylindrical sintered body impregnated with lubricating oil. As Figure 1 shown, the oil-impregnated bearing 5 is disposed on the other end side of the bushing 6 and rotatably supports the shaft 2. The oil-impregnated bearing 5 of the present embodiment is fixed to the metal holder 8 by press-fitting and is fixed relative to the shaft 2 so as not to be relatively rotatable. In other words, the shaft 2 is supported by passing through and rotatably supporting the oil-impregnated bearing 5, and is supported so as to be relatively rotatable with respect to the metal holder 8, the stator 4, and the mounting plate 9.

[0050] The oil-impregnated bearing 5 is formed, for example, in a cylindrical shape, and at least a part thereof (the part on one end side) is disposed radially inside the stator 4. It should be noted that the inner peripheral surface of the oil-impregnated bearing 5 is a cylindrical surface coaxial with the shaft 2, but its outer shape (outer peripheral surface) may be any shape that is fixed relative to the shaft 2 so as not to be relatively rotatable, and may not be a cylindrical surface. Further, the outer peripheral surface of the oil-impregnated bearing 5 may not be uniform in the axial direction. A plurality of grooves for improving the absorption efficiency of the outflow oil may be provided on the axial end surfaces of the oil-impregnated bearing 5.

[0051] When the shaft 2 rotates, a so-called pumping action is generated, and the oil in the pores of the oil-impregnated bearing 5 is sucked out to the outside. As a result, an oil film is formed between the oil-impregnated bearing 5 and the shaft 2 and functions as lubricating oil and cooling oil, and a part of it flows out of the oil-impregnated bearing 5 as outflow oil. Further, the outflow oil around the oil-impregnated bearing 5 in the outflow oil is absorbed into the pores. On the other hand, when the rotation of the shaft 2 stops, the oil in contact with the surface of the oil-impregnated bearing 5 is absorbed into the pores due to capillary action.

[0052] The bushing 6 is a cylindrical member fixed to one end side of the stator 4 and through which the shaft 2 passes. The center line of the bushing 6 coincides with the center line of the shaft 2.

[0053] The bushing 6 has at least two functions. The first function is to suppress the inflow of the outflow oil between the bushing 6 and the shaft 2 and accumulate the outflow oil between the bushing 6 and the oil-impregnated bearing 5. The second function is to suppress the leakage of the outflow oil from the motor 1 in the case where the outflow oil infiltrates between the bushing 6 and the shaft 2. As Figure 2 shown, the bushing 6 includes a fixing portion 61 and a housing portion 64 as the portions for exerting these functions. The fixing portion 61 is the portion for exerting the first function, and the housing portion 64 is the portion for exerting the second function together with the washer 7.

[0054] The bushing 6 of the present embodiment further has a third function of preventing interference between the jumper wire Wc and the shaft 2. A guiding portion 65 is provided in the bushing 6 as the portion for exerting this function. In the bushing 6 of the embodiment, the fixing portion 61 and the housing portion 64 are continuously provided in the axial direction, and the housing portion 64 and the guiding portion 65 are continuously provided in the radial direction. In addition, for the bushing 6, the above-described fixing portion 61, housing portion 64, and guiding portion 65 are integrally formed of an insulating resin, and an oil-proof treatment (for example, fluorine coating) is applied to its surface.

[0055] The fixing portion 61 is the portion for fixing the bushing 6 to the stator 4, and as described above, is the portion for exerting the first function. The fixing portion 61 has a first end face 6B disposed opposite to the bearing end face 5B on one end side of the oil-impregnated bearing 5 and a first inner peripheral face 6A disposed opposite to the outer peripheral face 2A of the shaft 2, and is fixed to the inner peripheral face 4C of the core. As Figure 5 shown, the fixing portion 61 of the present embodiment has a cylindrical base portion 62 and a convex portion 63 protruding radially outward from the base portion 62, and the fixing portion 61 is press-fitted and fixed to the stator 4 by pressing the convex portion 63 against the inner peripheral face 4C of the core. Figure 2 shown, the first end face 6B and the first inner peripheral face 6A are formed on the base portion 62.

[0056] The base portion 62 is formed in a cylindrical shape having an outer diameter and an inner diameter that are consistent in the axial direction. The outer diameter of the outer peripheral face 62C of the base portion 62 (refer to Figure 5 ) is set to a length that can be embedded in the inner peripheral face 4C of the core (a length slightly smaller than the outer diameter of the inner peripheral face 4C of the core).

[0057] As Figure 2 shown, the inner diameter of the base portion 62 (that is, the inner diameter of the first inner peripheral face 6A) is set to a size that can form a minute gap between the outer peripheral face 2A of the shaft 2. Hereinafter, this gap is referred to as the first gap CA. The first gap CA is preferably set narrowly to at least less than the size of the oil droplets of the outflow oil and to such an extent that the rotating shaft 2 does not interfere with the first inner peripheral face 6A. The size of the first gap CA is set to, for example, 0.1 mm to 0.5 mm.

[0058] The first end face 6B, which is the end face on the other end side of the base portion 62, is disposed opposite to the bearing end face 5B with a second gap CB that is larger than the first gap CA therebetween. In other words, a second gap CB that is larger than the first gap CA is provided between the first end face 6B and the bearing end face 5B. By setting the two gaps CA and CB to such a size relationship and performing an oil-proof treatment on the bushing 6 as described above, the outflow oil is repelled by the oil-proof treated first inner peripheral surface 6A and the first end face 6B, thereby suppressing the situation of infiltrating into the first gap CA and easily accumulating in the second gap CB. Thereby, the first function of the bushing 6 is exerted. It should be noted that the outflow oil accumulated in the second gap CB is recovered by the oil-impregnated bearing 5 when it contacts the oil-impregnated bearing 5.

[0059] As Figure 5 shown, the convex portion 63 is provided to project radially outward from the outer peripheral surface 62C of the base portion 62. The protruding amount of the convex portion 63 relative to the outer peripheral surface 62C is set such that the outer diameter of the fixing portion 61 including the convex portion 63 is slightly larger than the inner peripheral surface 4C of the core. It should be noted that, in the present embodiment, the convex portion 63 is provided within the entire range in the axial direction of the base portion 62, but the convex portion 63 may also be provided in a part in the axial direction of the base portion 62.

[0060] In addition, a plurality of convex portions 63 may be provided on the fixing portion 61. In the present embodiment, three convex portions 63 are provided on the fixing portion 61. The three convex portions 63 have the same shape and are arranged separately from each other in the circumferential direction (at different phases in the circumferential direction). From the viewpoint of improving the stability during press-fitting and fixing of the bushing 6, it is preferable that the adjacent convex portions 63 are arranged at equal intervals in the circumferential direction.

[0061] The accommodating portion 64 is a portion for accommodating the washer 7. As Figure 2 shown, the accommodating portion 64 is a portion having a second inner peripheral surface 6D with a diameter larger than the first inner peripheral surface 6A on one end side of the fixing portion 61. In the present embodiment, the second inner peripheral surface 6D is formed from the second end face 6E on one end side of the bushing 6 toward the other end side.

[0062] The second inner peripheral surface 6D is set to have an inner diameter slightly larger than the outer diameter of the washer 7 so that the washer 7 can be disposed on its radial inner side. It should be noted that, in the present embodiment, the second inner peripheral surface 6D is located at a position closer to one end side than the core end face 4F (i.e., the stator core 41), but as long as the washer 7 can be disposed on its radial inner side, the second inner peripheral surface 6D may also extend to a position closer to the other end side than the core end face 4F.

[0063] The guiding portion 65 is a portion that extends axially from the fixing portion 61 further than the core end face 4F and against which the jumper wire Wc abuts, and functions as the third function as described above by guiding the jumper wire Wc. In the present embodiment, the guiding portion 65 is provided on the radially outer side of the accommodating portion 64. That is, the portion of the bushing 6 of the present embodiment on the one end side relative to the fixing portion 61 serves as both the accommodating portion 64 and the guiding portion 65.

[0064] Here, the third function will be described in detail. As described above, in the stator 4 of the present embodiment, two coils 45U, 45V, and 45W of the same phase are respectively connected by the jumper wire Wc. In addition, the two coils 45U, 45V, and 45W of the same phase are respectively arranged opposite to each other with the shaft 2 interposed therebetween.

[0065] Therefore, in the state without the bushing 6, as Figure 3 shown by the double-dashed line in, for example, the jumper wire Wc of the U-phase coil 45U can be arranged along a locus (winding orbit) of a cross-section passing through the shaft 2. As a result, the shaft 2 comes into contact (interferes) with the jumper wire Wc, and the jumper wire Wc may be broken. In contrast, in the motor 1 of the present embodiment, as Figure 2 and Figure 4 shown, by the guiding portion 65 protruding at a position on the one end side relative to the core end face 4F, the jumper wire Wc is guided, thereby suppressing the entry of the jumper wire Wc into the radial inner side. In other words, by the guiding portion 65 provided on the bushing 6 functioning as the third function, such interference between the jumper wire Wc and the shaft 2 is prevented.

[0066] For example, as Figure 4 shown, when viewed axially, the outer shape of the guiding portion 65 is circular. As Figure 2 shown, the guiding portion 65 is set such that its outer diameter is constant in the axial direction and larger than the inner diameter of the core inner peripheral surface 4C. That is, the guiding portion 65 has a stepped shape in which its outer surface 65C facing the radial outer side is located on the radially outer side relative to the core inner peripheral surface 4C. If attention is paid to the surface of the bushing 6 facing the radial outer side, among the outer peripheral surface of the fixing portion 61 and the outer surface 65C of the guiding portion 65, the radial dimension of the outer surface 65C of the guiding portion 65 is larger than the radial dimension of the outer peripheral surface of the fixing portion 61, and thus a stepped surface 6F (flat surface) is formed at the boundary portion between the fixing portion 61 and the guiding portion 65. This stepped surface 6F is a circular planar surface of the guiding portion 65 facing the other end side, and can abut against the core end face 4F. Thereby, positioning of the bushing 6 relative to the stator core 41 can be performed. And by the stepped surface 6F abutting against the core end face 4F, the bushing 6 and the stator core 41 are sealed. Therefore, the situation where the outflow oil flows from the radially outer side of the bushing 6 to the one end side of the stator core 41 is suppressed.

[0067] The outer diameter of the guiding portion 65 is more preferably set such that even if it is the size of the entire non-coated portion 47 covering the core end face 4F or the size covering a part of the non-coated portion 47, the gap formed between the outer surface 65C and the insulating layer 46 is smaller than the outer diameter of the winding W (jumper wire Wc). By setting the outer diameter of the guiding portion 65 in this way, the jumper wire Wc can be arranged on the insulating layer 46. In other words, contact between the jumper wire Wc and the core end face 4F can be prevented, and thus insulation between the winding W and the stator core 41 can be further achieved.

[0068] However, when the outer surface 65C of the guiding portion 65 is located radially outside the core inner peripheral surface 4C, as Figure 4 shown, the positioning groove 4G on the core inner peripheral surface 4C cannot be visually recognized from one end side. Therefore, in the guiding member 65 of the present embodiment, a concave portion 6G is provided on its second end face 6E. When the bushing 6 is inserted into the stator core 41, the bushing 6 is inserted into the stator core 41 in a state where the phase of the concave portion 6G is aligned with the positioning groove 4G, so that the position of the positioning groove 4G can be indirectly confirmed via the concave portion 6G. It should be noted that in the present embodiment, the concave portion 6G is provided in such a way that the outer shape of the second end face 6E is C-shaped, but as long as the concave portion 6G can be visually recognized from at least one end side, the shape of the concave portion 6G is not limited to this.

[0069] The protruding amount of the guiding portion 65 protruding from the core end face 4F is set to be at least greater than the outer diameter of the jumper wire Wc. As Figure 2 and Figure 4 shown, in the guiding portion 65, a plurality of jumper wires Wc can abut against the outer surface 65C overlapping each other in the axial direction. Therefore, the protruding amount of the guiding portion 65 is preferably set to be greater than the sum of the outer diameters of the maximum number of jumper wires Wc (here three) arranged overlappingly.

[0070] The washer 7 is a component that functions together with the accommodating portion 64 to perform the above-described second function as described above. It is provided at a position closer to one end side than the oil-impregnated bearing 5 and is disposed radially inside the second inner peripheral surface 6D of the accommodating portion 64. The washer 7 is, for example, annular when viewed axially, and is integrally rotated with the shaft 2 by press-fitting and fixing the shaft 2 into the through hole in the center. It should be noted that the material of the washer 7 is, for example, metal or resin.

[0071] Since the washer 7 is disposed radially inside the second inner peripheral surface 6D of the accommodating portion 64, its outer diameter is set to be at least smaller than the inner diameter of the second inner peripheral surface 6D. The outer diameter of the washer 7 is more preferably set to be greater than the inner diameter of the first inner peripheral surface 6A and the gap with the second inner peripheral surface 6D is made as small as possible (for example, about 0.1 mm). It should be noted that the axial thickness of the washer 7 is set to be at least smaller than the axial length of the second inner peripheral surface 6D of the bushing 6.

[0072] In the motor 1, the second function is exerted by such a washer 7 and the housing portion 64. Specifically, when the vertical direction of the actual motor 1 corresponds to Figure 1 the vertical direction of the paper surface shown, the outflow oil that has immersed between the bushing 6 and the shaft 2 scatters due to the washer 7 that rotates integrally with the shaft 2 and contacts the second inner peripheral surface 6D, and thus accumulates on the radially inner side of the housing portion 64. Thereby, the situation where the outflow oil flows to a position closer to one end side than the bushing 6 is suppressed, and thus the situation where the outflow oil leaks from the motor 1 is suppressed. In addition, the outflow oil accumulated on the radially inner side of the housing portion 64 can be returned to the other end side (that is, the side of the oil-impregnated bearing 5) by gravity. Therefore, a decrease in the oil content of the oil-impregnated bearing 5 can also be suppressed.

[0073] It should be noted that even when the vertical direction of the actual motor 1 is the direction in which Figure 1 the vertical direction of the paper surface shown is reversed, the second function is also exerted by the washer 7 and the housing portion 64. In this case, the outflow oil cannot be accumulated inside the housing portion 64. However, by scattering the outflow oil using the washer 7, the situation where the outflow oil directly flows along the shaft 2 and enters between the shaft 2 and the rotor 3 can be suppressed. In other words, by the washer 7, the situation where the outflow oil accumulates near the fixed portion of the rotor 3 relative to the shaft 2 is suppressed, and thus the situation where the outflow oil leaks from the motor 1 can be suppressed.

[0074] Hereinafter, an example of the process of assembling the motor 1 will be described. First, the oil-impregnated bearing 5 is inserted from one end side of the metal holder 8, and the oil-impregnated bearing 5 is press-fitted and fixed to the metal holder 8. Then, the stator core 41 in a state where insulation coating has been performed and no winding W has been wound (that is, Figure 3 the stator core 41 in the state shown) is adhesively fixed to the metal holder 8.

[0075] Then, the oil-proof treated bushing 6 is inserted into the inner peripheral surface 4C of the core from one end side. As a result, the convex portion 63 of the fixing portion 61 is press-contacted with the inner peripheral surface 4C of the core, and the bushing 6 is press-fitted and fixed to the stator core 41. In addition, as Figure 2 shown, the bearing end face 5B of the oil-impregnated bearing 5 and the first end face 6B of the bushing 6 are disposed opposite to each other with a second gap CB therebetween, so as to ensure a space for accumulating the outflow oil between the oil-impregnated bearing 5 and the bushing 6.

[0076] Note that at this time, the convex portion 63 is pressed radially inward by the inner peripheral surface 4C of the core, but this force is absorbed due to the expansion deformation of the convex portion 63 in the circumferential direction. In this way, in the present embodiment, the plurality of convex portions 63 are arranged separately from each other in the circumferential direction, thereby allowing the expansion deformation of each convex portion 63 in the circumferential direction, and thus the deformation of the first inner peripheral surface 6A of the bushing 6 caused by press-fitting and fixing can be suppressed. Therefore, a space capable of inserting the shaft 2 can be maintained radially inside the bushing 6. In addition, by arranging the convex portions 63 at equal intervals in the circumferential direction, the fixing of the bushing 6 to the stator core 41 becomes more stable.

[0077] The bushing 6 inserted from one end side abuts against the core end surface 4F through the stepped surface 6F to prevent the guide portion 65 from entering the inner peripheral surface 4C of the core, so that the bushing 6 is positioned. And since the bushing 6 is airtight with the stator core 41, the situation where the oil flowing out flows from the radially outer side of the bushing 6 to one end side of the stator core 41 is suppressed. In addition, the non-coated portion 47 is partially covered by the guide portion 65 from one end side, thereby realizing the insulation between the winding W wound around the stator core 41 in the subsequent process and the stator core 41.

[0078] In addition, when the bushing 6 is inserted into the stator core 41 so that the positioning groove 4G and the recess 6G are in the same phase, as Figure 4 shown, even when the bushing 6 is inserted, the reference position in the circumferential direction of the stator 4 can be confirmed from one end side. Therefore, in the subsequent process, smooth assembly of the motor 1 can be achieved.

[0079] Next, each coil 45 is formed by winding the winding W around the stator core 41 in a state where the bushing 6 is fixed. In the present embodiment, each coil 45 is formed through the following process: a single winding W is sequentially wound around the tooth portions 43U, 43V, 43W of each phase to form six coils 45, and then the winding W connecting the coils 45U, 45V, 45W of different phases is cut off. In this way, by winding a single winding W without cutting (in a continuous manner), the operation efficiency can be improved.

[0080] Specifically, the winding W is wound around each tooth portion 43 in the order of (a) to (f) shown in Figure 3 . That is, first, the winding W is wound around one of the two U-phase tooth portions 43U to form the first U-phase coil 45U [ (a) in Figure 3 . Then, as shown in Figure 4 , the end line of this winding is used as the jumper wire Wc and is arranged along the outer surface 65C, and the winding W is wound around the other U-phase tooth portion 43U to form the second U-phase coil 45U [ (b) in Figure 3 .

[0081] Next, the winding end line of the second U-phase coil 45U is arranged along the outer surface 65C, and the winding wire W is wound around one V-phase tooth portion 43V adjacent to one U-phase tooth portion 43U, thereby forming the first V-phase coil 45V [as shown in (c) of Figure 3 . Then, this winding end line is arranged along the outer surface 65C as the jumper wire Wc, and the winding wire W is wound around the other V-phase tooth portion 43V, thereby forming the second V-phase coil 45V [as shown in (d) of Figure 3 . Then, the first W-phase coil 45W and the second W-phase coil 45W are formed in the same manner [as shown in (e) and (f) of this figure]. Finally, the winding wire W that connects the second U-phase coil 45U and the first V-phase coil 45V to the second V-phase coil 45V and the first W-phase coil 45W respectively is cut.

[0082] Then, one ends of the coils 45U, 45V, and 45W of each phase are bundled as the COM wire, the other ends are wound around a winding pin (not shown) and connected to the substrate, and the metal holder 8 is fixed to the mounting plate 9. Then, the shaft 2 with the rotor 3 and the washer 7 fixed thereto is inserted into the inner hole of the bushing 6 from one end side of the bushing 6, thereby completing the assembly of the motor 1. Thus, as shown in Figure 2 , a first gap CA narrower than the second gap CB is formed between the outer peripheral surface 2A of the shaft 2 and the first inner peripheral surface 6A of the bushing 6. In addition, the washer 7 is disposed in the housing portion 64 of the bushing 6 (radially inside the second inner peripheral surface 6D).

[0083] It should be noted that the assembly steps of the motor 1 are not limited thereto as long as the bushing 6 is fixed to the stator core 41 at least before the winding of the winding wire W. For example, the fixing of the oil-impregnated bearing 5 and the metal holder 8 to the stator 4 may also be performed after the formation of each coil 45 (i.e., after the winding of the winding wire W).

[0084] [2. Function and Effect]

[0085] (1) According to the above-described motor 1, the first function can be exerted by the fixing portion 61 of the bushing 6 that has been subjected to an oil-proof treatment at least on the first inner peripheral surface 6A and the first end surface 6B. That is, it is possible to suppress the infiltration of the leaked oil between the shaft 2 and the bushing 6 (i.e., the first gap CA), and accumulate the leaked oil between the oil-impregnated bearing 5 and the bushing 6 (i.e., the second gap CB). Therefore, it is possible to suppress a decrease in the oil content of the oil-impregnated bearing 5.

[0086] In addition, according to the above-described motor 1, the second function can be achieved by the housing portion 64 of the bushing 6 and the washer 7. That is, even when the leaked oil infiltrates between the bushing 6 and the shaft 2, the leakage of the leaked oil to the outside of the motor 1 can be suppressed. Therefore, it is possible to suppress a decrease in the oil content of the oil-impregnated bearing 5 and to suppress the leakage of oil to the outside of the motor 1 even when the leaked oil is not fully recovered.

[0087] (2) In the above-described motor 1, the stator core 41 and the coil 45 are insulated by the insulating layer 46 formed by insulation coating. In this way, by setting the insulation method between the stator core 41 and the coil 45 to insulation coating instead of the existing structure of providing an insulating member, the space between adjacent tooth portions 43 can be ensured to be relatively large. Therefore, the duty ratio can be increased, and thus the performance of the motor 1 can be improved. In addition, since no insulating member is required, the number of components can be reduced, and thus the structure of the motor 1 can be simplified.

[0088] Furthermore, according to the above-described motor 1, the third function can be achieved by the guiding portion 65 provided on the bushing 6. That is, the jumper wire Wc that may interfere with the shaft 2 can be brought into contact with the guiding portion 65 of the bushing 6 and arranged, thereby preventing the contact (interference) between the shaft 2 and the jumper wire Wc. Therefore, the disconnection of the jumper wire Wc can be prevented, and thus the performance of the motor 1 can be improved.

[0089] (3) In the above-described motor 1, the bushing 6 has a stepped shape in which the outer surface 65C of the guiding portion 65 is located radially outside the core inner peripheral surface 4C. Thereby, it is possible to prevent the guiding portion 65 from entering the core inner peripheral surface 4C. Therefore, the contact between the shaft 2 and the jumper wire Wc can be further prevented, and the positioning of the bushing 6 can be performed. In addition, even if there is a non-coated portion 47 where insulation coating is not performed, the contact between the non-coated portion 47 and the jumper wire Wc can be suppressed by the guiding portion 65, so that the insulation performance can be ensured. And by the step surface 6F abutting against the core end surface 4F, the bushing 6 and the stator core 41 are sealed, so that the leakage of the leaked oil from the radially outer side of the bushing 6 can be suppressed. Furthermore, a decrease in the oil content of the oil-impregnated bearing 5 can be suppressed.

[0090] (4) In the above-described motor 1, a positioning groove 4G is provided on the core inner peripheral surface 4C of the stator core 41, and a recess 6G is provided on the second end surface 6E of the bushing 6. Thus, when assembling the motor 1, the bushing 6 is assembled to the stator core 41 with the phases of the positioning groove 4G and the recess 6G being aligned, so that the position of the positioning groove 4G can be indirectly confirmed via the recess 6G. Therefore, the workability of the assembly operation of the motor 1 can be improved.

[0091] (5) In the above-described motor 1, the stator 4 has six tooth portions 43. When the number of tooth portions 43 is six, as described above, the coils 45U, 45V, and 45W of the same phase are arranged opposite to each other across the shaft 2. Therefore, in a state without the bushing 6, the jumper wire Wc easily enters the radially inner side of the stator core 41. However, in the above-described motor 1, such entry of the jumper wire Wc into the radially inner side is blocked by the guiding portion 65, so that interference between the jumper wire Wc and the shaft 2 can be prevented.

[0092] (6) In the above-described motor 1, the fixing portion 61 having the base portion 62 and the convex portion 63 is press-fitted and fixed to the inner peripheral surface 4C of the core, so that the bushing 6 is fixed to the stator core 41. By setting the fixing of the bushing 6 to the stator core 41 as a press-fit in this way, the man-hours for this fixing can be reduced. In addition, by providing the convex portion 63 instead of press-fitting the base portion 62 itself, deformation of the base portion 62 during press-fitting can be suppressed. Therefore, a space into which the shaft 2 can be inserted can be maintained inside the bushing 6 fixed to the stator core 41 in the radial direction.

[0093] (7) In the above-described motor 1, the three convex portions 63 are provided so as to be separated from each other in the circumferential direction. Thereby, when the bushing 6 is inserted into the stator core 41, the shaft center can be easily ensured. In addition, by providing the three convex portions 63 so as to be separated from each other in the circumferential direction, expansion deformation of each convex portion 63 in the circumferential direction during press-fitting can be allowed. Therefore, a space into which the shaft 2 can be inserted can be maintained inside the bushing 6 fixed to the stator core 41 in the radial direction.

[0094] [3. Others]

[0095] The above-described motor 1 is merely an example and is not limited to the above structure. In the motor 1, in addition to the washer 7, a second washer that rotates integrally with the shaft 2 may be provided in the second gap CB. By providing such a second washer, it is possible to suppress the case where the outflow oil directly flows into the first gap CA along the shaft 2. Therefore, intrusion of the outflow oil into the first gap CA can be further suppressed. In addition, the outflow oil accumulated in the second gap CB can be scattered by the second washer and returned to the oil-impregnated bearing 5, so that the oil circulation function can be further improved.

[0096] It is sufficient that the bushing 6 is provided with at least the fixing portion 61 and the accommodating portion 64, and the guiding portion 65 can be omitted. Even when the guiding portion 65 is provided, the guiding portion 65 may be continuously provided on one end side in the axial direction of the accommodating portion 64 instead of the radially outer side of the accommodating portion 64. When the guiding portion 65 is not provided, the accommodating portion 64 may be arranged on the radially inner side of the stator core 41. That is, the bushing 6 may be entirely arranged on the radially inner side of the stator core 41. In addition, the oil-proof treatment applied to the bushing 6 may be applied at least to the first inner peripheral surface 6A and the first end surface 6B, and may not be applied to the entire bushing 6.

[0097] The fixing portion 61 only needs to have at least a first inner peripheral surface 6A and a first end surface 6B and be in a shape fixed to the inner peripheral surface 4C of the core. In addition, the housing portion 64 only needs to be in a shape having at least a second inner peripheral surface 6D on one end side of the fixing portion 61. The first inner peripheral surface 6A only needs to be able to form a first gap CA between the first inner peripheral surface 6A and the outer peripheral surface 2A of the shaft 2 at least on the other end side thereof (near the connection portion with the first end surface 6B). In addition, the second inner peripheral surface 6D only needs to be in a shape having a diameter larger than that of the first inner peripheral surface 6A at least and be able to dispose the washer 7 on the radially inner side thereof. Therefore, the diameters of the first inner peripheral surface 6A and the second inner peripheral surface 6D may not be consistent in the axial direction. The first inner peripheral surface 6A and the second inner peripheral surface 6D may also be, for example, in a tapered shape that expands in diameter toward one end side. In this case, the outflow oil accumulated in the bushing 6 can be returned to the other end side (i.e., the oil-impregnated bearing 5 side) again by the actual motor 1.

[0098] Instead of the fixing portion 61 having the base portion 62 and the convex portion 63, the fixing portion may also be, for example, a cylindrical shape (square cylindrical shape) having a polygonal outer shape when viewed from the axial direction. In this case, when the fixing bushing 6 is press-fitted into the stator core 41, the corners of the fixing portion are press-connected to the inner peripheral surface 4C of the core and deformed, thereby being able to suppress the deformation of the first inner peripheral surface 6A. In addition, the fixing method of the bushing 6 to the stator 4 may not be press-fitting fixation, and may be, for example, adhesive fixation.

[0099] The number of the convex portions 63 is not limited to three, and may be set to more than three, for example. When it is not necessary to ensure the shaft center when fixing the bushing 6 to the stator core 41, the number of the convex portions 63 may also be less than three. In addition, the shape of the convex portion 63 is not limited to the above shape. The convex portion may, for example, extend along the circumferential direction of the base portion 62. In this case, a plurality of convex portions may also be provided. In this case, if a plurality of convex portions are provided separately from each other in the axial direction, deformation of the convex portion in the axial direction is allowed during press-fitting fixation, and thus deformation of the inner hole of the bushing can be suppressed.

[0100] The guiding portion 65 only needs to extend at least further in the axial direction from the fixing portion 61 than the core end surface 4F and abut against the jumper wire Wc, and the outer shape viewed from the axial direction may not be circular. The outer shape of the guiding portion 65 may be, for example, a polygonal shape. In addition, the outer surface 65C of the guiding portion 65 may not be located at a position radially outside the inner peripheral surface 4C of the core. That is, the bushing 6 may not be in a stepped shape. In this case, outflow of the outflow oil from the radially outer side of the bushing 6 can be suppressed, and therefore the fixing portion 61 is preferably fixed in such a manner that the entire circumferential region of its outer peripheral surface abuts against the inner peripheral surface 4C of the core. In addition, in this case, the concave portion 6G may be omitted.

[0101] The number of teeth 43 of the stator 4 may not be six either. The insulating layer 46 provided on the stator 4 may also cover the entire area of the core end face 4C. When the space between adjacent teeth 43 is relatively large, an insulating member provided in an existing stator may be provided on the stator 4. In this case, the insulating layer 46 may be omitted. The positioning groove 4G may not be provided on the inner peripheral surface 4C of the core either.

[0102] Description of Reference Numerals

[0103] 1 Motor (outer-rotor type brushless motor); 2 Shaft; 2A Outer peripheral surface; 3 Rotor; 4 Stator; 4C Inner peripheral surface of core; 4F Core end face; 4G Positioning groove; 5 Oil-impregnated bearing; 5B Bearing end face; 6 Bushing; 6A First inner peripheral surface; 6B First end face; 6D Second inner peripheral surface; 6E Second end face; 6F Step surface (flat surface); 6G Recess; 7 Washer; 41 Stator core; 42 Cylindrical portion; 43 Tooth portion; 45 Coil; 46 Insulating layer; 61 Fixing portion; 62 Base portion; 62C Outer peripheral surface; 63 Protrusion; 64 Receiving portion; 65 Guide portion; 65C Outer surface; CA First gap; CB Second gap; W Winding; Wc Jumper wire.

Claims

1. An outer-rotor type brushless motor, characterized in that: The outer-rotor type brushless motor includes: A rotor that rotates integrally with a shaft; A stator disposed at a position radially outside the shaft and radially inside the rotor; A cylindrical bushing fixed to one end side of the stator and through which the shaft passes; An oil-impregnated bearing disposed radially inside the stator and at a position away from the side where the bushing is located in the axial direction, axially supporting the shaft to rotate freely; and A washer disposed at a position closer to the side where the bushing is located in the axial direction than the oil-impregnated bearing and rotating integrally with the shaft, The bushing includes: A fixing portion having a first end face and a first inner peripheral surface, and fixed to the inner peripheral surface of the core of the stator. The first end face is disposed opposite to the bearing end face on one end side of the oil-impregnated bearing, and the first inner peripheral surface is disposed opposite to the outer peripheral surface of the shaft with a first gap formed therebetween; And A receiving portion having a second inner peripheral surface with a diameter larger than that of the first inner peripheral surface on one end side of the fixing portion, The bushing is subjected to an oil-proof treatment at least on the first end face and the first inner peripheral surface, The washer is disposed radially inside the second inner peripheral surface, A second gap larger than the first gap is provided between the bearing end face and the first end face.

2. The outer-rotor type brushless motor according to claim 1, characterized in that: The outer-rotor type brushless motor further includes a second washer disposed in the second gap and rotating integrally with the shaft.

3. The outer-rotor type brushless motor according to claim 1 or 2, characterized in that: The stator includes: a stator core including a cylindrical portion having the inner peripheral surface of the core and a plurality of tooth portions protruding radially outward from the cylindrical portion; a plurality of coils wound by winding wires around each of the plurality of tooth portions; and an insulating layer formed by insulating coating on the tooth portions around which the wires are wound, The bushing includes a guiding portion that extends further in the axial direction from the fixing portion than the core end face of the stator core and against which a jumper wire connecting between the plurality of coils abuts.

4. The outer-rotor type brushless motor according to claim 3, characterized in that: The bushing has a stepped shape in which the outer surface of the guiding portion facing radially outward is located radially outside the inner peripheral surface of the core, The plane of the guiding portion facing the side where the oil-impregnated bearing is located abuts against the core end face.

5. The outer-rotor type brushless motor according to claim 4, characterized in that: A positioning groove extending in the axial direction is provided on the inner peripheral surface of the core, In the guiding portion, a concave portion is provided on a second end face in the same direction as the core end face.

6. The outer-rotor type brushless motor according to claim 5, characterized in that: The stator core has six of the tooth portions.

7. The outer-rotor type brushless motor according to claim 1 or 2, characterized in that: The fixing portion has: a cylindrical base portion having an outer peripheral surface with an outer diameter that can be fitted into the inner peripheral surface of the core; and a convex portion that protrudes from the outer peripheral surface of the base portion, and the fixing portion is press-fitted and fixed to the inner peripheral surface of the core.

8. The outer-rotor type brushless motor according to claim 7, wherein the fixing portion has three or more of the convex portions, and the three or more convex portions are arranged separately from each other in the circumferential direction.

Images