Brushless Motor

Abstract

The present invention provides a brushless motor that takes into account both the ease of winding of the winding and the high torque in a small-diameter motor using a split iron core. An inner rotor type brushless motor is provided with a rotor arranged in the center of a cylindrical stator (3), wherein the stator (3) is formed by combining six split iron cores (3A) that are divided at equal intervals in the circumferential direction. Each split iron core (3A) has: a stator iron core portion (30) having an arc portion (30a) constituting a part of the cylindrical portion of the stator (3) and a tooth portion (30b) protruding radially inward from the circumferential center of the arc portion (30a); an insulating member portion (31) mounted on the stator iron core portion (30); and a coil wound around the tooth portion (30b) from the insulating member portion (31). The outer diameter of the brushless motor (1) is greater than 27 mm and less than 36 mm.

Description

Technical Field

[0001] The present invention relates to an inner rotor type brushless motor. Background Art

[0002] In an inner rotor type brushless motor (hereinafter referred to as a "motor"), a rotor having a magnet is arranged radially inside a stator having a coil wound around a tooth portion, and output is taken out from a shaft portion that rotates integrally with the rotor. Conventionally, in a stator of a brushless motor, a structure is known in which a stator core is formed by assembling divided core sheets.

[0003] For example, Patent Document 1 discloses a stator (motor) in which the main pole teeth for winding coils are split cores separate from the core body. In this motor, a coil frame and an insulating member are assembled on the main pole teeth, and the coils are wound on this basis to form a coil unit separately, which is then assembled to the core body. It should be noted that in the stator of Patent Document 1, in addition to the main pole teeth, additional pole teeth on which no coils are wound are also provided integrally with the core body.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6649161 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In addition, the specifications of the motor (torque, size, etc.) are often determined by the device or machine on which the motor is mounted, and the motor needs to be designed to meet its specifications. For example, in an inner rotor type brushless motor with a small diameter of about Φ30mm, when the required torque (output) is relatively high, it is important to increase the space factor of the coil. In this regard, in a motor using a split core, it is easier to wind the winding around the teeth than in a motor using an integrated stator core, so it is easier to increase the space factor of the coil.

[0009] This application is developed in view of such a problem, and one of its purposes is to provide an inner rotor type brushless motor that can take into account both the ease of winding of the winding and the high torque in a small diameter motor using a split iron core. It should be noted that this purpose is not limited to this purpose, and another purpose of this application is to achieve the effects brought about by the various structures shown in the specific embodiments described later, which are effects that cannot be obtained by the previous technology.

[0010] Solutions to Solve Problems

[0011] (1) The brushless motor disclosed herein is an inner rotor type brushless motor in which a rotor is arranged at the center of a cylindrical stator, and the stator is composed of six split cores divided at equal intervals in the circumferential direction. Each of the split cores has: a stator core portion having an arc portion constituting a part of the cylindrical portion of the stator and a tooth portion protruding radially inward from the circumferential center of the arc portion; an insulator portion mounted on the stator core portion; and a coil wound around the tooth portion from above the insulator portion, and the outer diameter of the brushless motor is not less than 27 mm and not more than 36 mm.

[0012] (2) Preferably, the split core is an insert-molded product obtained by molding the stator core portion with a resin that becomes the insulator portion.

[0013] (3) Preferably, the split core has an escape groove, which is recessed on the inner surface of the molded arc portion of the insulating member portion that is molded on the arc portion and faces radially inward, and the escape groove is pressed into a winding start portion of the winding that becomes the coil.

[0014] (4) Preferably, the split core has a planar flat cut portion, the flat cut portion is formed at edges on both sides of the circumferential direction of the inner surface of the molded arc portion of the insulator portion that is molded on the arc portion and faces the radial inner side, and the flat cut portion extends in the axial direction.

[0015] (5) Preferably, the brushless motor includes a bus bar unit, the bus bar unit is arranged on one axial end side of the stator, and the bus bar unit has three bus bars for connecting the three-phase coils provided on the stator in the same phase. In this case, preferably, the split core has a base portion for assembling the bus bar unit.

[0016] (6) Preferably, the bus bar unit is configured such that two of the three bus bars are insert-molded using resin, the remaining bus bar is assembled to the molded bus bar obtained by the insert molding, and a resin bus bar cover is attached to cover the remaining bus bar.

[0017] Effects of the Invention

[0018] According to the disclosed brushless motor, in a small-diameter motor using a split core, it is possible to achieve both ease of winding of the winding and high torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a perspective view showing a brushless motor according to the embodiment.

[0020] Figure 2 yes Figure 1An exploded perspective view of the brushless motor shown.

[0021] Figure 3 It is along Figure 1 The brushless motor shown is an axial cross-sectional view, and the rotor, shaft, small housing plate and cover are omitted.

[0022] Figure 4 It is formed when viewed from the axial direction. Figure 1 The brushless motor shown in the figure is a stator of six divided cores, and the coil is omitted.

[0023] Figure 5 (a) is Figure 4 A direction view, Figure 5 (b) is Figure 4 View in direction B.

[0024] Figure 6 yes Figure 4 DD section view.

[0025] Figure 7 It is formed when viewed from the axial direction. Figure 4 The figure shows a stator core portion of a divided core.

[0026] Figure 8 It is shown Figure 2 A three-dimensional diagram of a bus bar unit.

[0027] Fig. 9 yes Figure 8 View in direction F.

[0028] Fig.10 yes Fig. 9 A cross-sectional view of a busbar unit is shown.

[0029] Description of Reference Numerals

[0030] 1 Motor (Brushless Motor)

[0031] 2 Rotors

[0032] 3. Stator

[0033] 3A Split Core

[0034] 6 Busbar unit

[0035] 30 Stator core

[0036] 30a Arc part

[0037] 30b Tooth

[0038] 31 Insulation parts

[0039] 31a Molded arc part

[0040] 31d Inner surface

[0041] 31e Retreat slot

[0042] 31f Flat cut

[0043] 31g Base

[0044] 32 Coil

[0045] 60 Busbar

[0046] 61 Molded Busbar

[0047] 62 Busbar cover. DETAILED DESCRIPTION

[0048] Referring to the accompanying drawings, a brushless motor as an embodiment is described. The embodiments shown below are merely illustrative and are not intended to exclude various modifications and technical applications that are not explicitly shown in the following embodiments. The various structures of this embodiment can be implemented with various modifications within the scope of their main purpose. In addition, they can be selected and discarded as needed, or they can be appropriately combined.

[0049] [1. Overall structure]

[0050] Figure 1 is a perspective view of a brushless motor 1 (hereinafter referred to as “motor 1”) according to the present embodiment. Figure 2 It is an exploded perspective view of the motor 1 . Figure 3 It is an axial cross-sectional view of the motor 1 and shows the rotor 2 , the shaft portion 20 , the small housing plate 9 , and the cover 8 which will be described later without being shown. Figure 4 to Figure 7 is a diagram for explaining the stator 3. Figure 8 to Figure 10 It is a diagram for explaining the bus bar unit 6 .

[0051] like Figure 1 to Figure 3 As shown, the motor 1 is an inner rotor type brushless motor in which a rotor 2 is arranged at the center of a cylindrical stator 3. In the present embodiment, a small-diameter motor 1 having an outer diameter (diameter) of 30 mm (Φ30) and 6 slots is exemplified. It should be noted that as long as the outer diameter of the motor 1 is greater than 27 mm and less than 36 mm, it is not limited to Φ30. The motor 1 includes: a cylindrical rotor 2 having a magnet 22; a stator 3 having a coil 32; and a shaft 20 that rotates integrally with the rotor 2, and the motor 1 is configured to accommodate the rotor 2 and the stator 3 in a metal housing 4 that forms the outer contour of the motor 1.

[0052] like Figure 2As shown, the motor 1 of this embodiment includes a bus bar unit 6, a small housing 5, a printed circuit board 7 (hereinafter referred to as "substrate 7"), a cover 8, a rotor 2, and a small housing plate 9, which are assembled in the axial direction with respect to a housing 4 in which a stator 3 is built. The stator 3 is formed by dividing six split cores 3A (see Figure 4 ) are combined and constituted. Hereinafter, each element assembled in the housing 4 will be described in sequence, and then the structure of the stator 3 will be described in detail.

[0053] like Figure 1 as well as Figure 2 As shown, the housing 4 is a bottomed cylindrical type with one end side open in the axial direction, and a small shell plate 9 is fixed to the opening of one end side and a shaft portion 20 is protrudingly provided. It should be noted that the appearance shape of the housing 4 of this embodiment is a cylinder, but the shape of the housing 4 is not limited to this.

[0054] like Figure 3 As shown, the stator 3 is a substantially cylindrical member having a space for arranging the rotor 2 on the inner diameter side, and the stator 3 includes: an annular stator core portion 30 fixed in the housing 4; and a coil 32 wound around the stator core portion 30 via an insulator portion 31. In the motor 1 of this embodiment, six coils 32 are provided. U-phase current is supplied to two coils 32, V-phase current is supplied to the other two coils 32, and W-phase current is supplied to the remaining two coils 32.

[0055] like Figure 2 , Figure 3 as well as Figure 8 As shown, the bus bar unit 6 is an annular component arranged on one axial end side of the stator 3, and includes three bus bars 60. The bus bar 60 is a conductive flat member that connects the three-phase coils 32 provided on the stator 3 in the same phase. The bus bar unit 6 is provided as an insert molded product obtained by molding at least one of the three bus bars 60 that are arc-shaped when viewed from the axial direction with resin. The end 60a of each bus bar 60 is provided to be exposed from the resin. It should be noted that a circular hole portion 6d concentric with the central axis C of the motor 1 is provided in the center of the bus bar unit 6.

[0056] Fig. 9 is from Figure 8 A diagram obtained by observing the bus bar unit 6 in the direction of arrow F in FIG. Fig.10 2 is a cross-sectional view obtained by cutting the bus bar unit 6 in a direction perpendicular to the axial direction. In the bus bar unit 6 of the present embodiment, two of the three bus bars 60 (for example, the bus bars 60 of the U phase and the V phase) are insert-molded by resin and are provided as molded bus bars 61. The bus bar unit 6 is configured such that the remaining bus bar 60 (for example, the bus bar 60 of the W phase) is Fig.10As shown, it is assembled on the molded bus bar 61, and as Fig. 9 As shown, a resin bus bar cover 62 is installed to cover the bus bar 60 to be installed later. As described above, the bus bar unit 6 of the present embodiment is a partially assembled insert molded product.

[0057] like Figure 1 to Figure 3 As shown, the small housing 5 is a component formed of an insulating material (such as resin), and integrally comprises: a bottomed cylindrical connector portion 51, which is arranged adjacent to the housing 4; a cylindrical portion 52, which is arranged on one axial end side of the stator 3; and a connecting portion 53, which connects the connector portion 51 and the cylindrical portion 52. The outer shape of the connector portion 51 is roughly square cylindrical, and the connector portion 51 is arranged so that the length direction (central axial direction) is parallel to the central axis C of the motor 1. It should be noted that the bottom 51a of the connector portion 51 of the present embodiment is located on the side opposite to the bottom of the housing 4 (one end side). That is, the housing 4 is open toward one end side, and the connector portion 51 is open toward the other end side.

[0058] like Figure 3 As shown, at the bottom 51a of the connector part 51, a plurality of connector terminals 50 penetrate the bottom 51a and are fixed. The connector terminals 50 are configured to be exposed in the internal space surrounded by the four side parts 51b of the connector part 51. The connector terminals 50 include terminals for power supply and terminals for working signals, and can input power and working signals from the outside. In this embodiment, each connector terminal 50 is fixed relative to the fixing hole provided through the bottom 51a of the connector part 51 by chiseling (Japanese: kaikikashime). As a result, the plurality of connector terminals 50 can be easily fixed to the connector part 51 in a close state.

[0059] like Figure 2 As shown in FIG. 1 , the barrel 52 of the connector 51 is in the shape of a bottomed cylindrical cylinder, and the barrel 52 is received near the opening of one end of the housing 4 with its bottom facing the stator 3. A circular hole 52d is provided at the center of the bottom of the barrel 52 and is concentric with the central axis C of the motor 1. Figure 3 As shown, the bus bar unit 6 described above is arranged between the cylindrical portion 52 and the stator 3 in the axial direction.

[0060] like Figure 2 As shown, the connecting portion 53 of the connector portion 51 is a portion having a substantially U-shaped cross section extending radially outward from the cylindrical portion 52 and connected to the connector portion 51. The side surface of the cylindrical portion 52 is formed as a notch at the portion of the connecting portion 53, so that the space surrounded by the side surface of the cylindrical portion 52 is connected to the space surrounded by the U-shaped connecting portion 53. The substrate 7 is arranged in these spaces.

[0061] like Figure 2 as well as Figure 3 As shown, the substrate 7 is a component that electrically connects the end 60a of each bus bar 60 to the connector terminal 50 that passes through the bottom 51a. The substrate 7 is arranged in the range of the axial end side of the stator 3 and the bottom 51a side of the connector part 51. In addition to the output lines including the U phase, V phase, and W phase, the substrate 7 is provided with a pattern including a sensor line for extracting the Hall signal, a power line, a ground line, etc. The substrate 7 of this embodiment is a flat plate with a flush surface, and is arranged on one end side of the small housing 5.

[0062] The substrate 7 of this embodiment has a substantially rectangular terminal connection portion 7a to which the connector terminal 50 is connected, a circular ring portion 7b having a hole portion 7d at the center, and a straight connection portion 7c connecting the terminal connection portion 7a and the ring portion 7b when viewed from the axial direction. The terminal connection portion 7a is accommodated in the connector portion 51, the ring portion 7b is accommodated in the cylinder portion 52, and the connection portion 7c is accommodated in the connecting portion 53. It should be noted that a Hall sensor 10 for detecting the rotational position of the rotor 2 is mounted on the ring portion 7b of the substrate 7.

[0063] like Figure 1 as well as Figure 2 As shown, the cover 8 is an insulating component mounted on the small housing 5 from one end side in the axial direction, and blocks the opening of the small housing 5. The shape of the cover 8 as viewed from the axial direction is substantially the same as the outer shape (outer edge portion) of one end side of the small housing 5. That is, the cover 8 has a connector cover portion 8a covering the connector portion 51, an annular portion 8b covering the cylindrical portion 52 and having a hole portion 8d in the center, and a connecting portion 8c covering the connecting portion 53.

[0064] like Figure 2 As shown, the rotor 2 includes: a rotor core (not shown), which rotates integrally with the shaft 20; a cylindrical magnet 22, which is fixed to the outer peripheral surface of the rotor core; a bushing 23, which is fixed to the shaft 20 at one end of the magnet 22; and a sensor magnet 24, which is fixed to the bushing 23 and rotates integrally with the shaft 20. The shaft 20 is a rotating shaft that supports the rotor 2, and also functions as an output shaft that takes out the output (mechanical energy) of the motor 1 to the outside. The shaft 20 of this embodiment is rotatably supported by the bottom of the housing 4 and the small housing plate 9 via bearings provided at two positions sandwiching the rotor core 21.

[0065] like Figure 2As shown, in the motor 1 of the present embodiment, when the bus bar unit 6, the small housing 5, the substrate 7 and the cover 8 are sequentially mounted on the stator 3 accommodated in the housing 4, the hole 6d of the bus bar unit 6, the hole 52d of the small housing 5, the hole 7d of the substrate 7 and the hole 8d of the cover 8 all overlap. The shaft 20 passes through these holes 6d, 52d, 7d, 8d. In the motor 1 of the present embodiment, the diameters of these holes 6d, 52d, 7d, 8d are larger than the outer diameter of the rotor 2. Thus, after the four elements 6, 5, 7, 8 are assembled in the housing 4, the rotor 2 integrated with the shaft 20 can be inserted into the housing 4 (stator 3).

[0066] like Figure 1 as well as Figure 2 As shown, the small housing plate 9 is a metal component mounted on one end side of the cover 8 and fixed to the housing 4. The small housing plate 9 of this embodiment has a flat surface 9a placed on the surface of one end side of the cover 8, and a bulging portion 9b formed in a bottomed cylindrical shape centered on the central axis C from the flat surface 9a. The bulging portion 9b is a portion for accommodating a bearing not shown in the figure.

[0067] [2. Main structure]

[0068] Figure 4 This is a diagram of the stator 3 including six split cores 3A as viewed from the axial direction, in which the coil 32 is omitted and the inner peripheral surface of the housing 4 is shown by a two-dot chain line. Figure 5 (a) and (b) are respectively obtained from Figure 4 A three-dimensional view of the split core 3A obtained by observing the split core 3A with arrows A and B, Figure 6 yes Figure 4 The cross-sectional view as viewed along the arrow DD is shown with the coil 32 omitted. Figure 7 This is a diagram of a core piece 30P constituting the stator core portion 30 of the split core 3A as viewed from the axial direction.

[0069] like Figure 4 As shown in FIG. 1 , the six split cores 3A are all of the same shape and are combined to form a cylindrical stator 3 centered on the central axis C of the motor 1. Each split core 3A includes a metal stator core portion 30, a resin insulator portion 31, and the above-mentioned coil 32 (see FIG. 1 ). Figure 3 ). The insulator portion 31 is attached to the stator core portion 30. The coil 32 is wound around the teeth portion 30b from above the insulator portion 31 before the split cores 3A are assembled (in a split state).

[0070] The stator core portion 30 comprises: an arc portion 30a constituting a part of the cylindrical portion of the stator 3; a tooth portion 30b protruding radially inward from the circumferential center of the arc portion 30a; and a wall portion 30c extending in a blade-like manner from the radially inner end of the tooth portion 30b to both circumferential sides. Figure 7 The arc portion 30a is equivalent to a sector-shaped arc with a central angle of 60 degrees, and its two circumferential end faces are in surface contact with the circumferential end faces of the arc portions 30a of the two adjacent split cores 3A. The tooth portion 30b and the wall portion 30c are T-shaped when viewed from the axial direction.

[0071] The split core 3A of this embodiment is an insert molded product obtained by molding the stator core portion 30 with a resin that becomes the insulator portion 31. That is, the insulator portion 31 is a member formed integrally with the stator core portion 30, rather than a post-installed component. As a result, the insulator portion 31, which is an insulator, can be made thinner than a post-installed insulator, which contributes to an improvement in the space factor of the winding.

[0072] like Figures 4 to 6 As shown, the insulating part 31 of the present embodiment has: a molded arc portion 31a, which molds the arc portion 30a; a molded tooth portion 31b, which molds the tooth portion 30b; and a molded wall portion 31c, which surrounds the periphery of the wall portion 30c. The molded arc portion 31a covers at least the entire surface of the arc portion 30a facing the radial inner side, and is formed to protrude toward one end side and the other end side respectively than the two end surfaces of the axial one end side and the other end side of the arc portion 30a. In other words, the axial dimension of the molded arc portion 31a is larger than the axial dimension of the arc portion 30a. The molded arc portion 31a is formed in the shape of a rounded quadrilateral that is longer in the axial direction when viewed from the radial inner side.

[0073] like Figure 4 As shown, two circumferentially adjacent split cores 3A are accommodated (fixed) along the inner circumferential surface of the housing 4 in a state where both circumferential end surfaces of the arc portion 30a and the molded arc portion 31a are in surface contact with each other. That is, a portion of the arc portion 30a is not molded by the insulator portion 31 and is exposed.

[0074] like Figures 4 to 6 As shown, the molded tooth portion 31b molds the entire tooth portion 30b, whereas the molded wall portion 31c molds the wall portion 30c except for the surface of the wall portion 30c facing the radial inner side. In other words, the wall portion 30c is not molded by the insulating member portion 31, but is exposed. The molded wall portion 31c prevents the coil 32 wound on the molded tooth portion 31b from shifting radially inward. The molded wall portion 31c is formed in the shape of an axially long oblong or rounded quadrilateral when viewed from the radial inner side.

[0075] The split core 3A of this embodiment has a relief groove 31e recessed in the inner surface 31d of the molded circular arc portion 31a toward the radial inner side. The relief groove 31e is a groove into which the winding start portion of the winding to become the coil 32 is pressed. In the split core 3A of this embodiment, the relief groove 31e extends from the position on the axial end side of the molded tooth portion 31b to the inner surface 31d of the molded circular arc portion 31a. Figure 6 The winding is wound in the direction indicated by the arrow E, but as the winding is wound, the winding start portion (the first turn of the winding) is pressed into the escape groove 31e. This can reduce the stress acting on the winding start portion during winding, so that a winding of thick wire (for example, Φ0.6 wire) can be wound, which helps to increase the torque.

[0076] The escape groove 31e is provided at the location where the winding start portion of the winding is located, that is, at one axial end side of the molded tooth portion 31b in this embodiment. The escape groove 31e is formed in a direction from the position of the winding start portion toward the winding direction ( Figure 6 The slot width (the circumferential dimension of the stator core 30) is shown in the arrow E. Figure 6 Thus, as the amount of winding increases, the winding start portion becomes easier to enter the escape groove 31e, thereby reducing the stress acting on the winding start portion.

[0077] like Figures 4 to 6 As shown, the split core 3A of this embodiment has flat cut portions 31f formed on the edges (edges) of the inner surface 31d of the molded arc portion 31a on both sides of the circumferential direction. The flat cut portions 31f are planar portions extending axially in each edge portion, and have the function of preventing the winding from getting stuck when winding the winding. That is, the portion formed by chamfering the edge on the inner surface 31d side of the molded arc portion 31a is the flat cut portion 31f. In the split core 3A of this embodiment, the normal directions of the two flat cut portions 31f are parallel to each other, and the plane that virtually connects the two flat cut portions 31f is flush.

[0078] The split core 3A of this embodiment has a base portion 31g to which the bus bar unit 6 is assembled. The base portion 31g is provided to protrude from the end surface of the molded arc portion 31a at one end in the axial direction and is engaged with the base fitting portion 63 (see FIG. 1 ) of the bus bar unit 6. Figure 8 to Figure 10 In the motor 1 of the present embodiment, the outer shape of the base portion 31g is a substantially rectangular parallelepiped shape, and each of the six base fitting portions 63 is provided as a recess into which each base portion 31g is fitted.

[0079] [3. Effect]

[0080] (1) According to the above-mentioned motor 1, the winding can be wound before the split core 3A is combined, so the winding can be easily wound using a flywheel winding machine or a spindle winding machine. In addition, the stator 3 is composed of a split core 3A with 6 slots and 6 divisions, so the balance of the stator 3 during assembly is excellent, and the space factor is also easily improved. For example, in the case of a split core divided into 3, the arc portion is equivalent to a fan-shaped arc portion with a center angle of 120 degrees, so the circumferential length of the arc portion becomes longer. Therefore, the space (invalid space) where the winding cannot be wound becomes larger, and it is difficult to increase the space factor. In contrast, according to the motor 1 having the stator 3 including the split core 3A divided into 6 as described above, the winding can be easily wound and the space factor can be improved.

[0081] In addition, in the motor 1 using the stator 3 of 6 slots, if its outer diameter is less than 27 mm, it is impossible to ensure a sufficient amount of winding, and there is a possibility that the torque is insufficient, but by making its outer diameter greater than 27 mm, it is possible to output a higher torque than an existing brushed motor of the same type. In addition, in the motor 1 using the stator 3 including the split core 3A of 6 divisions, by making its outer diameter less than 36 mm, it is possible to output a higher torque than an existing brushed motor of the same type. For example, in a motor having an outer diameter greater than 36 mm, a scheme in which the number of divisions of the stator is set to 9 divisions or 12 divisions can achieve a higher torque output than a scheme in which the number of divisions is set to 6. In other words, the maximum value of the outer diameter of the motor 1 that can effectively utilize the stator 3 of 6 divisions is 36 mm.

[0082] (2) In the above-mentioned motor 1, the split core 3A is provided as an insert molded product obtained by molding the stator core portion 30 with a resin that becomes the insulator portion 31, so that the insulator portion 31 can be thinned. As a result, the space factor of the coil 32 can be further increased compared to a structure in which the insulator and the stator core are provided separately and installed later, so that a high torque can be achieved.

[0083] (3) In the above-mentioned motor 1, a retreat groove 31e is provided in the molded arc portion 31a of the split core 3A. As a result, when the winding is gradually wound on the tooth portion 30b, the winding start portion (first turn) of the winding is pressed into the retreat groove 31e. Therefore, the space factor of the coil 32 can be further increased, and higher torque can be achieved. In addition, although a large stress may be applied to the first turn during winding, the stress can be relieved by pressing the winding start portion into the retreat groove 31e, and the worry of disconnection of the first turn can be eliminated.

[0084] (4) In the above-mentioned motor 1, a flat cut portion 31f is provided on the molded arc portion 31a of the split core 3A. The above-mentioned motor 1 is a small-diameter motor of not less than Φ27 and not more than Φ36, so the curvature radius of the split core 3A is small. Therefore, although the winding is wound on the split core 3A, it is sometimes difficult to insert it into the mouth of the winding machine. In contrast, by providing the flat cut portion 31f on the split core 3A, the two edges of the molded arc portion 31a are chamfered, so that the winding does not get stuck when the winding is wound, and the winding of the winding can be further improved.

[0085] (5) According to the above-described motor 1 , since the base portion 31 g is provided in the split core 3A, the bus bar unit 6 can be easily fixed in the case 4 , and the assemblability can be improved.

[0086] (6) In particular, in the motor 1 described above, two of the three bus bars 60 are insert-molded and the remaining one is assembled, so that the bus bar unit 6 can be manufactured with the best balance among assemblability, component availability, and cost.

[0087] [4. Others]

[0088] The structure of the motor 1 described in the above embodiment is an example and is not limited to the above structure. For example, the bus bar unit 6 may be formed by molding all three bus bars 60 with resin, or the bus bar unit 6 and the stator 3 may not be fixed by the base portion 31g and the base fitting portion 63.

[0089] The position and shape of the escape groove 31e of the split core 3A are not limited to the above positions and shapes, and can be set according to the direction of winding the winding and the position of the winding start. It should be noted that the escape groove 31e is not necessary and can be omitted. The flat cut portion 31f of the split core 3A is also not necessary and can be omitted.

[0090] The split core 3A is an insert molded product obtained by molding the stator core portion 30 with resin, but the insulator portion 31 may be separately molded and then attached to the stator core portion 30. As long as the outer diameter of at least the motor 1 is 27 mm or more and 36 mm or less (within 10 mm) and the six-slot inner rotor brushless motor includes six split cores 3A, it is possible to achieve both easy winding of the winding and high torque.

[0091] In addition, the connector part 51 may be open at one end side in the axial direction or may be open in the radial direction. It should be noted that the fixing method of the plurality of connector terminals 50 is not limited to caulking, and other fixing methods such as bonding may also be used. The small housing 5 (connector part 51) and the cover 8 may also be omitted.

[0092] The shape and material of the small housing plate 9 are not limited to the above-mentioned shapes and materials. In the above-mentioned motor 1, the structure in which the rotor 2 is inserted after the bus bar unit 6, the small housing 5, the substrate 7 and the cover 8 are mounted on the housing 4 is exemplified, but the rotor 2 may be inserted first and then these elements may be assembled. In this case, the diameter of each hole portion 6d, 52d, 7d, 8d may be less than the outer diameter of the rotor 2.

[0093] The installation position and orientation of the Hall sensor 10 are not limited to the above-mentioned installation position and orientation. For example, the Hall sensor 10 may be installed on the substrate 7 in a manner to detect the rotation from the axial direction of the rotor 2, or the Hall sensor 10 itself may be omitted. In addition, the bus bar 60 may not be a member molded with resin, and the substrate 7 may not be a flat plate with a flat surface. It should be noted that the connector terminal 50 may be connected to the end 60a of the bus bar 60 instead of using the substrate 7.

Claims

1. A brushless motor, which is an inner rotor type brushless motor in which a rotor is arranged at the center of a cylindrical stator, The brushless motor is characterized in that The stator is formed by combining six split cores that are divided at equal intervals in the circumferential direction. Each of the split cores has: a stator core portion having an arc portion constituting a part of a cylindrical portion of the stator and a tooth portion protruding radially inward from a circumferential center of the arc portion; an insulator part mounted on the stator core part; and a coil wound around the teeth from above the insulating member, Each of the split cores is an insert molded product obtained by molding the stator core portion with a resin that becomes the insulator portion. The brushless motor includes a bus bar unit, the bus bar unit is arranged on one axial end side of the stator, and the bus bar unit has three bus bars for connecting the three-phase coils provided on the stator in the same phase. The bus bar unit is configured such that two of the three bus bars are insert-molded using resin, the remaining bus bar is assembled to a molded bus bar obtained by the insert molding, and a bus bar cover made of resin covering the bus bar is installed. The brushless motor has an outer diameter of 27 mm or more and 36 mm or less.

2. The brushless motor according to claim 1, characterized in that: The split core has an escape groove which is recessed on an inner surface of a molded arc portion of the insulator portion that molds the arc portion and faces radially inward, and into which a winding start portion of a winding that becomes the coil is pressed.

3. The brushless motor according to claim 1 or 2, characterized in that: The split core has planar flat cut portions formed at edges on both sides of the circumferential inner surface of a molded arc portion of the insulator portion that molds the arc portion and faces radially inward, and the flat cut portions extend in the axial direction.

4. The brushless motor according to claim 1, characterized in that: The split core includes a base portion to which the bus bar unit is assembled.

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