Brushless motors and power tools

Abstract

The purpose of this disclosure is to provide a brushless motor and power tool that can improve the accuracy of the clearance between the rotor and stator. The rotor (5) has: a rotating shaft (51); a rotor core (6); and a plurality of permanent magnets (52). The stator (2) has: a stator core (20); and a plurality of coils (23). The stator core (20) has a first contact surface (31). The orientation of the normal vector of the first contact surface (31) follows the radially inward direction of the rotating shaft (51). A bearing retainer (first bearing retainer 7) has a second contact surface (720) that contacts the first contact surface (31). The orientation of the normal vector of the second contact surface (720) follows the radially outward direction of the rotating shaft (51). The bearing retainer is positioned by bringing the first contact surface (31) into contact with the second contact surface (720).

Description

Technical Field

[0001] This disclosure generally relates to brushless motors and power tools. More particularly, this disclosure relates to a brushless motor including a bearing for a rotating shaft that rotatably supports a rotor, and a power tool including such a brushless motor. Background Technology

[0002] Patent Document 1 discloses a power tool comprising a housing (power tool body) and a motor unit. The motor unit includes a stator and a rotor. The rotor forms an integral part of the motor shaft. As a component for assembling the motor unit onto the housing itself, the housing includes two motor retaining portions and two bearing retaining portions. The two motor retaining portions are rib members configured to protrude from the inner circumferential surface of the housing and retain the outer periphery of the motor unit. The two bearing retaining portions are rib members configured to protrude from the inner circumferential surface of the housing and retain the respective outer peripheries of a first bearing and a second bearing supporting the motor shaft.

[0003] However, in the power tool of Patent Document 1, the accuracy of the rotor-stator clearance may decrease due to backlash, for example, left when the motor unit, the first bearing, and the second bearing are assembled together with the housing. Therefore, the power tool of Patent Document 1 still has room for improvement in this regard.

[0004] Existing technical documents

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-202500 Summary of the Invention

[0007] Therefore, the purpose of this disclosure is to provide a brushless motor and a power tool, both of which are configured to improve the accuracy of the rotor-stator clearance.

[0008] The brushless motor according to this disclosure includes a rotor, a stator, bearings, and a bearing retainer. The rotor includes a rotating shaft, a rotor core, and a plurality of permanent magnets. The rotor core holds the rotating shaft. The plurality of permanent magnets are held by the rotor core. The stator includes a stator core and a plurality of coils. The stator core is configured to surround the rotor. The plurality of coils are wound around the stator core. The bearing rotatably supports the rotating shaft. The bearing retainer holds the bearing. The stator core has a first contact surface. The normal vector of the first contact surface is aligned with a radially inward direction defined for the rotating shaft. The bearing retainer has a second contact surface that contacts the first contact surface. The normal vector of the second contact surface is aligned with a radially outward direction defined for the rotating shaft. The bearing retainer is positioned by bringing the first contact surface into contact with the second contact surface.

[0009] According to another aspect of this disclosure, a power tool includes the aforementioned brushless motor and a power tool body. The brushless motor is housed within the power tool body. Attached Figure Description

[0010] Figure 1 This is a perspective view of a brushless motor according to an exemplary embodiment, viewed from the rear side at an angle.

[0011] Figure 2 This is a 3D view of the brushless motor as seen from the front side at an angle.

[0012] Figure 3 This is a cross-sectional view of a brushless motor;

[0013] Figure 4 yes Figure 3 Enlarged view of the main parts shown;

[0014] Figure 5 It is an exploded 3D view of the rotor core and stator core of a brushless motor;

[0015] Figure 6 This is an exploded perspective view of the main parts of a brushless motor, viewed from the rear side at an angle.

[0016] Figure 7 This is an exploded perspective view of the main parts of a brushless motor, viewed from the front side at an angle.

[0017] Figure 8 This is a schematic diagram of a power tool that includes a brushless motor;

[0018] Figure 9 It is a cross-sectional view of the brushless motor based on the third variation;

[0019] Figure 10 This is a 3D view of the main components of a brushless motor;

[0020] Figure 11 The attachment process for the main components of the brushless motor is shown;

[0021] Figure 12 The attachment process for the main components of the brushless motor is shown;

[0022] Figure 13 This is a perspective view of the brushless motor according to the fourth modification, viewed from the front side of the brushless motor at an angle.

[0023] Figure 14 It is a cross-sectional view of a brushless motor; and

[0024] Figure 15 This is an exploded view of the main components of a brushless motor. Detailed Implementation

[0025] (Implementation Method)

[0026] The brushless motor 1 and power tool 10 according to embodiments will be described with reference to the accompanying drawings. Note that the embodiments described below are merely exemplary embodiments among the various embodiments of this disclosure and should not be construed as limiting. Rather, the exemplary embodiments can be readily modified in various ways depending on design choices or any other factors without departing from the scope of this disclosure. Furthermore, the drawings referenced in the following description of the embodiments are schematic representations. Therefore, the ratios of the dimensions (including thickness) of the corresponding components shown in the drawings do not always reflect their actual dimensional ratios.

[0027] (1) Overview of brushless motors

[0028] The brushless motor 1 can be configured for, for example, power tools 10, electric bicycles, electric-assisted bicycles, or electric vehicles. In the following description of embodiments, as an example, it is assumed that the power tool 10 is equipped with the brushless motor 1.

[0029] like Figure 1-Figure 5 As shown, a brushless motor 1 according to an exemplary embodiment includes a rotor 5, a stator 2, a bearing (first bearing 53), and a bearing retainer (first bearing retainer 7). The rotor 5 includes a rotating shaft 51, a rotor core 6, and a plurality of permanent magnets 52. The rotor core 6 holds the rotating shaft 51. The plurality of permanent magnets 52 are held by the rotor core 6. The stator 2 includes a stator core 20 and a plurality of coils 23. The stator core 20 is configured to surround the rotor 5. The plurality of coils 23 are wound around the stator core 20. The bearing rotatably supports the rotating shaft 51. The bearing retainer holds the bearing. The stator core 20 has a first contact surface 31. The normal vector of the first contact surface 31 is aligned with a radially inward direction defined for the rotating shaft 51. The bearing retainer has a second contact surface 720 that contacts the first contact surface 31. The normal vector of the second contact surface 720 is aligned with a radially outward direction defined for the rotating shaft 51. The bearing retainer is positioned by bringing the first contact surface 31 into contact with the second contact surface 720.

[0030] According to this configuration, the bearing retainer (first bearing retainer 7) is positioned by bringing the first contact surface 31 into contact with the second contact surface 720. That is, the bearing retainer and the bearing (first bearing 53) held by the bearing retainer are positioned by the stator core 20. The bearing supports the rotation shaft 51 of the rotor 5. Compared to the case where the bearing is not positioned by the stator core 20 (e.g., the bearing is held only by the power tool body 108), this improves the accuracy of the clearance between the rotor 5 and the stator 2. As used herein, good clearance accuracy means minimal variation in the size of the clearance. Furthermore, compared to the case where the bearing is held only by the power tool body 108, this also reduces the possibility that the assembly accuracy between the power tool body 108 and the brushless motor 1 (such as the presence or absence of looseness) could affect the accuracy of the clearance between the rotor 5 and the stator 2.

[0031] Furthermore, according to this configuration, the first contact surface 31 and the second contact surface 720 contact each other along the radius of the rotation axis 51, thereby reducing the possibility of misalignment between the rotor 5 and the stator 2. Therefore, this further improves the accuracy of the gap between the rotor 5 and the stator 2.

[0032] Furthermore, the brushless motor 1 according to this embodiment is housed in the power tool body 108 of the power tool 10 (see...). Figure 8 The brushless motor 1 includes a rotor 5, a stator 2, a first bearing 53, and a second bearing 54. The rotor 5 includes a rotating shaft 51, a rotor core 6, and a plurality of permanent magnets 52. The rotor core 6 holds the rotating shaft 51. The plurality of permanent magnets 52 are held by the rotor core 6. The stator 2 includes a stator core 20 and a plurality of coils 23. The stator core 20 is configured to surround the rotor 5. The plurality of coils 23 are wound around the stator core 20. The first bearing 53 and the second bearing 54 rotatably support the rotating shaft 51. The rotor core 6 is interposed between the first bearing 53 and the second bearing 54. The first bearing 53 and the second bearing 54 are held by the stator 2.

[0033] According to this configuration, both the first bearing 53 and the second bearing 54 supporting the rotating shaft 51 of the rotor 5 are held by the stator 2. Compared to the case where at least one of the first bearing 53 or the second bearing 54 is held by the power tool body 108, this reduces the possibility that the assembly precision between the power tool body 108 and the brushless motor 1 (such as the presence or absence of looseness) might affect the precision of the gap between the rotor 5 and the stator 2. In other words, this improves the precision of the gap between the rotor 5 and the stator 2.

[0034] (2) Power tools

[0035] like Figure 8 As shown, the power tool 10 includes a brushless motor 1 and a power tool body 108. The power tool 10 also includes a power supply unit 101, a drive force transmission unit 102, an output shaft 103, a chuck 104, an end tool 105, a trigger 106, and a control unit 107.

[0036] The power tool body 108 (housing) houses a brushless motor 1. The power tool body 108 also houses a drive force transmission unit 102, an output shaft 103, and a control unit 107.

[0037] The end tool 105 is attached to the chuck 104. The brushless motor 1 is the drive source for driving the end tool 105.

[0038] Power supply unit 101 is a power source (DC power supply) for supplying current to drive brushless motor 1. Power supply unit 101 may be, for example, a battery pack. The battery pack includes one or more secondary batteries. Rotor 5 includes a rotating shaft 51. The driving force of brushless motor 1 (i.e., the rotational power of rotor 5) is transmitted via rotating shaft 51 to drive force transmission unit 102. Drive force transmission unit 102 limits the driving force of brushless motor 1 and supplies the limited driving force to output shaft 103. The output shaft 103 is driven (e.g., rotated) by the driving force supplied by drive force transmission unit 102. Chuck 104 is fixed to output shaft 103. Chuck 104 allows end tool 105 to be removably attached to chuck 104. Examples of end tool 105 (also referred to as "drill") include screwdrivers, sockets, and drill bits. One of these various types of end tool 105 is selected according to the intended use and attached to chuck 104 for use.

[0039] Control unit 107 is used to control the plurality of coils 23 (see power supply unit 101) supplied to brushless motor 1. Figure 1 The circuit provides current to the brushless motor 1. This allows the control unit 107 to control the rotational speed of the rotor 5 of the brushless motor 1.

[0040] Trigger 106 is an operating unit for receiving operating commands to control the rotation of the rotor 5 of the brushless motor 1. Executing the operation of trigger 106 allows selective starting or stopping of rotor 5 rotation. Furthermore, adjusting the manipulation variable of the operation of trigger 106 allows control of the rotational speed of rotor 5. That is, adjusting the manipulation variable of the operation of trigger 106 allows control of the rotational speed of the output shaft 103, which rotates synchronously with rotor 5. The larger the manipulation variable, the higher the rotational speed of rotor 5 and output shaft 103. Based on the operating command input through trigger 106, control unit 107 starts or stops the rotation of rotor 5 and output shaft 103, and also controls the rotational speed of rotor 5 and output shaft 103. In this power tool 10, end tool 105 is coupled to output shaft 103 via chuck 104. Then, by operating trigger 106 to control the rotational speed of rotor 5 and output shaft 103, the rotational speed of end tool 105 is controlled.

[0041] Note that the power tool 10 according to this embodiment includes a chuck 104, thereby allowing the end tool 105 to be replaced according to its intended use. However, the end tool 105 need not be replaceable. Alternatively, the power tool 10 may also be designed to allow the user to use only a specific type of end tool 105.

[0042] (3) Overall structure of brushless motor

[0043] Next, the construction of the brushless motor 1 will be described. In the following description, the rotor 5 and the fan 9, which will be described later (see...) Figure 3 The direction of the parallel configuration will be defined as front / rear, and the fan 9 should be located in front of the rotor 5, with the rotor 5 located behind the fan 9. However, these definitions should not be interpreted as restricting the direction of use of the brushless motor 1 and the power tool 10.

[0044] like Figure 3 and Figure 5 As shown, the brushless motor 1 includes a rotor 5, a stator 2, a first bearing 53, a second bearing 54, and a fan 9. The rotor 5 includes a rotating shaft 51, a rotor core 6, and multiple (e.g., ...) Figure 5 The stator 2 includes six permanent magnets 52. These permanent magnets 52 are held by the rotor core 6. The stator 2 includes a stator core 20 and multiple (e.g., 6 permanent magnets 52). Figure 1 9 of them) coils 23, multiple (for example, Figure 6 The rotor core 6 consists of two coil holders 81 and 82 and a first bearing retainer 7. The stator core 20 is arranged around the rotor core 6. That is, the stator core 20 surrounds the rotor core 6. Multiple coils 23 are wound around the stator core 20.

[0045] The rotor 5 rotates relative to the stator 2. Specifically, magnetic flux generated from multiple coils 23 is applied to multiple permanent magnets 52, thereby causing the rotor 5 to rotate. The rotational power (driving force) of the rotor 5 is transmitted from the rotation shaft 51 to the driving force transmission unit 102 (see...). Figure 8 ).

[0046] like Figure 3 As shown, the rotor core 6 comprises multiple steel plates 600. The multiple steel plates 600 are stacked one on top of another in the thickness direction. All the multiple steel plates 600 have the same shape.

[0047] The stator core 20 includes multiple steel plates 210 and multiple steel plates 220.

[0048] Multiple steel plates 210 are stacked one on top of another in the thickness direction. All the steel plates 210 have the same shape. The multiple steel plates 210 form the central core 21 of the stator core 20 (described later).

[0049] Multiple steel plates 220 are stacked one on top of another in the thickness direction. All the steel plates 220 have the same shape. The multiple steel plates 220 form the outer cylinder portion 22 of the stator core 20 (described later).

[0050] As can be seen, both the stator core 20 and the rotor core 6 comprise multiple steel plates. Each of the stator core 20 and the rotor core 6 is formed by stacking multiple steel plates one on top of the other in the thickness direction. In other words, each of the stator core 20 and the rotor core 6 is a so-called "stacked core". The surface of each of the multiple steel plates is covered with an insulating coating. The multiple steel plates are connected to each other by welding each pair of steel plates adjacent to each other in the thickness direction. The direction in which the multiple steel plates are stacked one on top of the other is aligned with the axis of rotation 51 of the rotor 5 (that is, the longitudinal axis of rotation 51, i.e., the front / back direction). More specifically, each steel plate is an electrical steel plate. Each steel plate is made of a magnetic material. Each steel plate can be, for example, a silicon steel plate.

[0051] The stator core 20 is thicker than the rotor core 6. The inner circumferential surface of the stator core 20 faces the outer circumferential surface of the rotor core 6, with a predetermined gap between these circumferential surfaces. For example, the gap can be between 0.2 mm and 0.6 mm.

[0052] (4) Rotor

[0053] like Figure 3 and Figure 5 As shown, rotor 5 includes a cylindrical rotor core 6 and multiple (e.g., Figure 5 (6 permanent magnets 52 and rotating shaft 51)

[0054] When viewed along the axis of rotation 51, the rotor core 6 is concentric with the rotation shaft 51. The rotation shaft 51 is held inside the rotor core 6. More specifically, the rotor core 6 has a shaft hole 611 as its central hole, through which the rotation shaft 51 passes. The rotor core 6 and the rotation shaft 51 rotate together.

[0055] Multiple permanent magnets 52 are housed in the rotor core 6. In other words, the brushless motor 1 has a so-called "internal permanent magnet (IPM)" structure in which multiple permanent magnets 52 are embedded in the rotor core 6.

[0056] Each of the plurality of permanent magnets 52 may be embedded in the rotor core 6, for example, using an adhesive applied thereto, and thus held by the rotor core 6. Alternatively, each of the plurality of permanent magnets 52 may also be held by magnetic attraction generated between the magnets 52 and the rotor core 6 without applying an adhesive between the magnets 52 and the rotor core 6.

[0057] Each permanent magnet 52 is cuboid in shape. When viewed along the axis of rotation 51, each permanent magnet 52 is rectangular in shape. Multiple permanent magnets 52 are arranged around and circumferentially around the axis of rotation 51. More specifically, multiple permanent magnets 52 are arranged around the axis of rotation 51 to form a polygonal (e.g., regular hexagonal) pattern. When viewed along the axis of rotation 51, the latitudinal axis of each permanent magnet 52 is aligned with the radius of the axis of rotation 51. Each permanent magnet 52 is magnetized along its latitudinal axis. Each pair of adjacent permanent magnets 52 is arranged with opposite magnetic poles facing outwards relative to the rotor core 6.

[0058] For example, each permanent magnet 52 can be, for example, a neodymium magnet, a ferrite magnet, or a plastic magnet.

[0059] (5) Stator

[0060] like Figure 5 As shown, the stator core 20 of the stator 2 includes a central core 21 and an outer cylinder 22. The stator core 20 is formed by connecting the central core 21 and the outer cylinder 22 to each other.

[0061] The central core 21 includes a cylindrical inner cylinder portion 3 and multiple (e.g., Figure 5 The inner cylinder 3 and the multiple teeth 4 are integrally formed together.

[0062] When viewed along the axis of rotation 51, the inner cylinder 3 is concentric with the rotation axis 51. The rotor core 6 is arranged inside the inner cylinder 3. The inner cylinder 3 has a first contact surface 31. The first contact surface 31 is the inner circumferential surface of the inner cylinder 3. Therefore, the normal vector of the first contact surface 31 is aligned with the radially inward direction defined with respect to the rotation axis 51. The first contact surface 31 exists along the entire circumference of the inner cylinder 3. The first contact surface 31 has a second contact surface 720 with the first bearing retaining part 7 (see...). Figure 4 )touch.

[0063] Each of the plurality of teeth 4 includes a body portion 41 and two end pieces 42. The body portion 41 protrudes from the inner cylinder portion 3 in a radially outward direction. The corresponding body portions 41 of the plurality of teeth 4 are arranged at equal intervals along the circumference of the inner cylinder portion 3. The two end pieces 42 extend from the end portion of the body portion 41 in a direction intersecting the direction in which the body portion 41 protrudes.

[0064] As used herein, if two or more components are arranged “equally spaced”, these components can naturally be arranged at strictly equal intervals, but their intervals can also differ from each other within tolerances.

[0065] The two end pieces 42 are configured as stops to reduce the possibility of the coil 23 detaching from the body portion 41. Specifically, the possibility of the coil 23 detaching is reduced by engaging the two end pieces 42 while the coil 23 moves toward the end portion of the body portion 41.

[0066] The outer cylinder portion 22 is cylindrical. More specifically, the outer cylinder portion 22 is cylindrical. When viewed along the axis of the rotation shaft 51, the outer cylinder portion 22 is concentric with the rotation shaft 51. The outer cylinder portion 22 surrounds the central core 21. The outer cylinder portion 22 is attached to the corresponding ends of the plurality of teeth 4 of the central core 21. That is, the plurality of teeth 4 are arranged to protrude from the outer cylinder portion 22 toward the rotor core 6.

[0067] The outer cylinder 22 includes multiple (e.g., Figure 5 The outer cylinder 22 comprises nine (9) fitting portions 221. In other words, the outer cylinder 22 includes as many fitting portions 221 as the teeth 4. Each of the multiple fitting portions 221 is a recess provided on the inner circumferential surface of the outer cylinder 22. The multiple fitting portions 221 are arranged at equal intervals along the circumference of the outer cylinder 22. The multiple fitting portions 221 correspond one-to-one with the multiple teeth 4. Each fitting portion 221 and its corresponding tooth 4 engages with each other. This allows the outer cylinder 22 to be connected to the central core 21. More specifically, the portion of each tooth 4 including two end pieces 42 engages with its corresponding fitting portion 221.

[0068] like Figure 3 , Figure 6 and Figure 7 As shown, stator 2 includes multiple (e.g., Figure 6 The coil holders 81 and 82 and the first bearing retainer 7 are attached to the coil holder 81.

[0069] The coil frames 81 and 82 can be made of, for example, synthetic resin. The coil frames 81 and 82 have electrical insulating properties. The coil frames 81 and 82 are attached to the stator core 20. The coil frames 81 and 82 are integrally formed with the stator core 20, for example, by insert molding. The coil frames 81 and 82 cover the area including the body portion 41 of each of the plurality of teeth 4. More specifically, the coil frame 81 covers the area including the body portion 41 of each of the plurality of teeth 4 from the front side of the teeth 4, while the coil frame 82 covers the area including the body portion 41 of each of the plurality of teeth 4 from the rear side of the teeth 4. Coils 23 are wound around each body portion 41 from above the coil frames 81 and 82. That is, the plurality of (9) coils 23 correspond one-to-one with the plurality of (9) teeth 4, and each coil 23 is wound around the corresponding tooth 4 from above the coil frames 81 and 82. In other words, the corresponding coil 23 is wound around the tooth 4 of the stator core 20 via the coil frames 81 and 82. Multiple coils 23 can be wound together, for example, by concentrated winding.

[0070] The coil frames 81 and 82 do not contact each other in the front / back direction. Therefore, in the portion near the middle of the thickness of the central core 21 (i.e., in the front / back direction), each tooth 4 is not covered by the coil frames 81 and 82, but is exposed. If the number of steel plates 210 forming the central core 21 (including the multiple teeth 4 and the inner cylinder 3) changes, for example due to a modification in the design of the brushless motor 1, the thickness of the central core 21 changes. As the thickness of the central core 21 changes, the distance between the coil frames 81 and 82 also changes.

[0071] The coil frame 81 includes: a cylindrical body 811 overlapping the inner cylinder portion 3; and multiple (e.g., Figure 6 Nine tooth covering portions 812, each tooth covering portion 812 covering the area of ​​the body portion 41 of a corresponding tooth among the plurality of teeth 4; and a plurality of (3, Figure 6 (Only one of them is shown) Hook portion 813. The cylinder body 811 is formed as a cylinder concentric with the inner cylinder portion 3. Each tooth cover portion 812 protrudes from the cylinder body 811 in a radially outward direction. Each tooth cover portion 812 covers its corresponding tooth 4 from the front side of the tooth 4 and from both sides in the circumferential direction along the rotation axis 51. The end of each tooth 4 located opposite to the end adjacent to the inner cylinder portion 3 (i.e., the portion including the two end pieces 42) is not covered by the coil frame 81, but contacts the outer cylinder portion 22.

[0072] Multiple hooks 813 protrude from the inner circumferential surface of the cylinder 811. The multiple hooks 813 are arranged at equal intervals along the circumference of the cylinder 811. Each of the multiple hooks 813 has a hook shape.

[0073] The coil holder 81 has an opening 8110 inside the cylinder 811. The rotating shaft 51 passes through the opening 8110. A first bearing retainer 7 is attached to the coil holder 81. The first bearing retainer 7 closes the opening 8110. This reduces the possibility of foreign objects entering the space where the rotor core 6 is arranged. Examples of foreign objects include those encountered with the use of an end tool 105 (see...). Figure 8 The completed work involves iron powder. The first bearing retainer 7 airtightly seals the internal space of the opening 8110.

[0074] The first bearing retainer 7 can be made of, for example, synthetic resin. The first bearing retainer 7 has electrical insulation properties. The first bearing retainer 7 includes a base 71 and a plurality of (e.g., Figure 6 (3) ribs 72 and multiple (e.g., 3, Figure 6 The image shows only two of the hook parts 73.

[0075] The base 71 is cylindrical. The base 71 has a shaft hole 701 as its central hole. More specifically, the base 71 has a recess 702 on one of its surfaces (rear surface) and a shaft hole 701 disposed through the bottom surface of the recess 702. The rotating shaft 51 passes through the shaft hole 701.

[0076] The first bearing retainer 7 holds the first bearing 53. More specifically, the first bearing 53 is inserted into the recess 702. The portion of the cylindrical first bearing 53 located near its outer edge contacts the inner surface (bottom surface) of the recess 702. On the other hand, the portion of the first bearing 53 located near its inner edge exists in the area opened by the shaft hole 701, and therefore does not contact the inner surface (bottom surface) of the recess 702.

[0077] Multiple ribs 72 are disposed on one surface (rear surface) of the base 71. Each of the multiple ribs 72 is arc-shaped when viewed in the front / rear direction. The multiple ribs 72 project from the outer edge of the base 71 along the axis of rotation 51 (i.e., in the front / rear direction). The multiple ribs 72 are arranged at equal intervals along the outer edge of the base 71. When cut along a plane passing through the center of the base 71 and aligned with the axis of the base 71, each of the multiple ribs 72 has a generally right-angled triangular cross-sectional shape (see...). Figure 3 ).

[0078] Each of the plurality of ribs 72 has a second contact surface 720. The second contact surface 720 is the outer peripheral surface of the rib 72. Therefore, the normal vector of the second contact surface 720 is aligned with the radially outward direction defined with respect to the rotation axis 51. The first contact surface 31 of the stator core 20 (the inner cylinder portion 3) contacts the second contact surface 720. The first bearing retainer 7 is positioned by bringing the first contact surface 31 into contact with the second contact surface 720. That is, the first bearing retainer 7 is positioned relative to the stator core 20. More specifically, the movement of the first bearing retainer 7 perpendicular to the axis of rotation 51 is restricted.

[0079] In this configuration, since each of the plurality of (three in this example) ribs 72 has a second contact surface 720, the first bearing retainer 7 has a plurality of (i.e., three) second contact surfaces 720. The first bearing retainer 7 contacts the stator core 20 (first contact surface 31) at a plurality of points (i.e., on the plurality of second contact surfaces 720).

[0080] Comparing the corresponding ends (front ends) of the stator core 20 and the rotor core 6 along the axis of rotation 51, it can be seen that one end (front end) of the stator core 20 is located in front of one end (front end) of the rotor core 6 (see...). Figure 3 This ensures sufficient contact area between the first contact surface 31 of the stator core 20 and each of the second contact surfaces 720 of the first bearing retaining portion 7.

[0081] The coil holder 81 also has a third contact surface 8111 (see...) Figure 4 The third contact surface 8111 is the inner surface of the opening 8110. The third contact surface 8111 is flush with the first contact surface 31. The base 71 has a fourth contact surface 711 (see...). Figure 4 The fourth contact surface 711 is the outer peripheral surface of the base 71. The third contact surface 8111 is in contact with the fourth contact surface 711.

[0082] Note that the second contact surface 720 of each rib 72 can contact not only the first contact surface 31, but also the third contact surface 8111.

[0083] The thickness of each rib 72 is less than the gap between the stator core 20 and the rotor core 6. Although each rib 72 is provided on the front side of the rotor core 6 in this embodiment, each rib 72 can also be inserted into the gap between the stator core 20 and the rotor core 6.

[0084] Multiple hooks 73 protrude from the outer peripheral surface of the base 71. When viewed in the front / rear direction, each hook 73 is disposed between an associated pair of ribs 72. The multiple hooks 73 are arranged at equal intervals along the circumference of the base 71. Each of the multiple hooks 73 has a hook shape.

[0085] The plurality of hook portions 73 of the first bearing retainer 7 correspond one-to-one with the plurality of hook portions 813 of the coil holder 81. By moving at least one of the first bearing retainer 7 or the coil holder 81 along the axis of rotation 51, the first bearing retainer 7 is engaged into the coil holder 81. More specifically, by moving at least one of the first bearing retainer 7 or the coil holder 81 along the axis of rotation 51, each hook portion 73 hooks onto its corresponding hook portion 813 (see...). Figure 3 For example, the first bearing retainer 7 can be inserted into the opening 8110 from the front side of the coil holder 81, so that each hook 73 passes over and hooks onto its corresponding hook 813. Alternatively, the first bearing retainer 7 can be inserted into the opening 8110 from the rear side of the coil holder 81, so that each hook 73 hooks onto its corresponding hook 813. It can be seen that at least one component of the first bearing retainer 7 and the coil holder 81 (e.g., both in this example) includes a hook 73 (or 813) that hooks onto the other component.

[0086] The hook portion 73 (or 813) restricts the movement of the first bearing retaining portion 7 relative to the coil frame 81 along the axis of rotation 51 (i.e., in the forward / backward direction) to a range where the second contact surface 720 does not disengage from the first contact surface 31. In other words, the range of forward or backward movement of the first bearing retaining portion 7 relative to the coil frame 81 is limited by causing the corresponding hook portion 73 to hook onto its corresponding hook portion 813.

[0087] The coil frame 82 includes: a cylindrical body 821 overlapping the inner cylinder portion 3; and multiple (e.g., Figure 6 The outer cylinder 821 has nine tooth covering portions 822, each covering a corresponding tooth of the plurality of teeth 4, including the area of ​​the body portion 41; and a second bearing retaining portion 823. The cylinder 821 is formed as a cylinder concentric with the inner cylinder portion 3. Each tooth covering portion 822 protrudes from the cylinder 821 in a radially outward direction. Each tooth covering portion 822 covers its corresponding tooth 4 from the rear side of the tooth 4 and from both sides in the circumferential direction along the rotation axis 51. The end of each tooth 4 located opposite to the end adjacent to the inner cylinder portion 3 (i.e., the portion including the two end pieces 42) is not covered by the coil frame 82, but contacts the outer cylinder portion 22.

[0088] At least some of the nine-toothed covering portions 822 (e.g., in Figure 6 The example shown has three bosses (8220 each). Each boss is cylindrical. Screw 109 (see...) Figure 1 The coil holder 82 is inserted into each boss portion 8220. The coil holder 82 is attached to the power tool body 108 via screws 109 (see...). Figure 8 ).

[0089] The second bearing retainer 823 is cylindrical. The second bearing retainer 823 has a through hole 8231 as its central hole. More specifically, the second bearing retainer 823 has a recess 8232 on one of its surfaces (front surface) and a through hole 8231 provided through the bottom surface of the recess 8232.

[0090] The second bearing retainer 823 holds the second bearing 54. More specifically, the second bearing 54 is inserted into the recess 8232. The portion of the cylindrical second bearing 54 located near its outer edge contacts the inner surface (bottom surface) of the recess 8232. On the other hand, the portion of the second bearing 54 located near its inner edge exists in the area opened by the through hole 8231 and does not contact the inner surface (bottom surface) of the recess 8232.

[0091] (6) First bearing and second bearing

[0092] Each of the first bearing 53 and the second bearing 54 can be, for example, a ball bearing. Each of the first bearing 53 and the second bearing 54 rotatably supports the rotating shaft 51. Figure 3 As shown, the rotor core 6 is mounted between the first bearing 53 and the second bearing 54. More specifically, the first bearing 53 is arranged on the front side of the rotor core 6, and the second bearing 54 is arranged on the rear side of the rotor core 6.

[0093] In this configuration, the first bearing retainer 7 for holding the first bearing 53 and the second bearing retainer 823 for holding the second bearing 54 are held by the stator core 20. More specifically, the first bearing retainer 7 is attached to the coil frame 81, and the second bearing retainer 823 forms part of the coil frame 82. The coil frames 81 and 82 are integrally formed with the stator core 20, for example, by insert molding.

[0094] Furthermore, the first bearing 53 and the second bearing 54 are held by the stator 2. More specifically, the first bearing 53 is held by the coil frame 81 of the stator 2. That is, the first bearing 53 is held by the coil frame 81 via the first bearing holding part 7. On the other hand, the second bearing 54 is directly held by the coil frame 82 of the stator 2. That is, the second bearing 54 is held by the second bearing holding part 823 of the coil frame 82.

[0095] (7) Fan

[0096] like Figure 3 and Figure 8 As shown, fan 9 is mounted between rotor core 6 and drive force transmission unit 102. Additionally, first bearing 53 is mounted between fan 9 and rotor core 6. Fan 9 is held by rotating shaft 51. More specifically, brushless motor 1 includes a cover 55 attached to rotating shaft 51. Fan 9 is held by rotating shaft 51 via cover 55. As rotating shaft 51 rotates, fan 9 rotates accordingly. Fan 9 then generates airflow (air stream) toward output shaft 103 (i.e., forward). In this way, fan 9 cools the internal space of power tool body 108 with air.

[0097] like Figure 1 and Figure 2 As shown, the fan 9 is circular when viewed in a front / back direction. The fan 9 includes a disk 91 and a plurality of blades 92. The disk 91 has a shaft hole 910 as its central hole. A rotating shaft 51 passes through the shaft hole 910. The plurality of blades 92 are disposed on one surface (rear surface) of the disk 91 and are arranged near the outer edge of the disk 91. The longitudinal axis of each of the plurality of blades 92 is aligned with the radius of the disk 91.

[0098] (8) board

[0099] like Figure 3As shown, the brushless motor 1 includes a plate 56 and a plurality of mounting components mounted on the plate 56. The plate 56 is held by a second bearing retainer 823. The plate 56 is interposed between the second bearing retainer 823 and the rotor core 6. The plate 56 is a sensor plate for detecting the rotation angle of the rotor 5. The brushless motor 1 according to this embodiment includes a plurality of (e.g., 3) rotation sensors as a plurality of mounting components, and a plurality of (e.g., ... Figure 1 The three first terminal members 57 and second terminal members 58 are respectively. For example, the rotation sensor may be a Hall element or a giant magnetoresistive (GMR) element. The multiple first terminal members 57 are electrically connected to multiple coils 23. The second terminal members 58 are electrically connected to the power supply unit 101 (see...). Figure 8 Each of the first terminal member 57 and the second terminal member 58 is, for example, at least partially embedded in the second bearing retainer 823 by insert molding.

[0100] (9) Advantages

[0101] As can be seen from the foregoing description, in the brushless motor 1 according to this embodiment, the first bearing retainer 7 is positioned by contacting the first contact surface 31 with the second contact surface 720. That is, the first bearing retainer 7 and the first bearing 53 held by the first bearing retainer 7 are positioned by the stator core 20. The first bearing 53 supports the rotation shaft 51 of the rotor 5. Compared with the case where the first bearing 53 is not positioned by the stator core 20 (for example, the first bearing 53 is held only by the power tool body 108), this improves the accuracy of the gap between the rotor 5 and the stator 2.

[0102] Furthermore, the second contact surface 720 of the first bearing retaining portion 7 contacts the inner cylinder portion 3 of the central core 21. For example, compared to the case where the second contact surface 720 contacts the outer cylinder portion 22 attached to the central core 21, this improves the accuracy of the gap between the inner cylinder portion 3 and the rotor core 6. In addition, the inner cylinder portion 3 is cylindrical, so that the inner cylinder portion 3 is almost not deformed due to the contact pressure between the first contact surface 31 and the second contact surface 720. This further improves the accuracy of the gap between the rotor 5 and the stator 2.

[0103] Furthermore, in the brushless motor 1 according to this embodiment, both the first bearing 53 and the second bearing 54 supporting the rotating shaft 51 of the rotor 5 are held by the stator 2. Compared to the case where at least one of the first bearing 53 or the second bearing 54 is held by the power tool body 108, this reduces the possibility that the assembly precision between the power tool body 108 and the brushless motor 1 (such as the presence or absence of looseness) might affect the precision of the gap between the rotor 5 and the stator 2. In other words, this improves the precision of the gap between the rotor 5 and the stator 2.

[0104] (First variation)

[0105] Next, the brushless motor 1 according to the first modification will be described. In the following description, any constituent element of this first modification having the same function as the corresponding part of the above embodiment will be indicated by the same reference numerals as the corresponding part, and its description will be omitted here.

[0106] In the exemplary embodiment described above, the coil holder 82 includes a second bearing retainer 823. In this case, the coil holders 81 and 82 may include at least one of a first bearing retainer 7 for retaining a first bearing 53 or a second bearing retainer 823 for retaining a second bearing 54.

[0107] In other words, the first bearing retaining portion 7 can be formed as part of the coil frame 81, which has electrical insulation properties. In other words, the first bearing retaining portion 7 and the coil frame 81 can be integrally formed with each other. More specifically, the first bearing retaining portion 7 and the coil frame 81 can be formed as a single component with electrical insulation properties.

[0108] (Second variation)

[0109] Next, the brushless motor 1 according to the second variation will be described. In the following description, any constituent element of this second variation having the same function as the corresponding part of the above embodiment will be indicated by the same reference numerals as the corresponding part, and its description will be omitted here.

[0110] In the above exemplary embodiment, the first bearing retaining portion 7 is attached to the coil holder 81. In this case, at least one of the first bearing retaining portion 7 or the second bearing retaining portion 823 can be attached to the coil holders 81 and 82. That is, the coil holder 82 may not include the second bearing retaining portion 823. In other words, the second bearing retaining portion 823 can be provided separately from the coil holder 82. In this case, the second bearing retaining portion 823 can be attached to the coil holder 82.

[0111] (Third variation)

[0112] Next, we will refer to Figures 9 to 12 The brushless motor 1A according to the third modification is described below. In the following description, any constituent element of this third modification that has the same function as the corresponding part of the above embodiment will be indicated by the same reference numerals as the corresponding part, and its description will be omitted here.

[0113] In this third variation, the first bearing retainer 7A has a different shape than the first bearing retainer 7 according to the exemplary embodiment described above. Furthermore, the coil holder 81A has a different shape than the coil holder 81 according to the exemplary embodiment described above.

[0114] The first bearing retainer 7A has no rib 72 (see...) Figure 6 The second contact surface 712 of the first bearing retaining portion 7A, which is designed to contact the first contact surface 31 of the stator core 20 (inner cylinder portion 3), is the outer peripheral surface of the base 71. That is, the portion of the outer peripheral surface of the base 71 located near the rear end contacts the first contact surface 31. Furthermore, the second contact surface 712 contacts not only the first contact surface 31 of the coil frame 81A, but also the third contact surface 8111 of the coil frame 81A.

[0115] like Figure 10 As shown, the first bearing retaining portion 7A includes a plurality of (e.g., nine) hook portions 74 instead of a plurality of hook portions 73. The plurality of hook portions 74 protrude from the outer peripheral surface of the base 71. The plurality of hook portions 74 are arranged at equal intervals along the circumference of the base 71. Each of the plurality of hook portions 74 is cuboid in shape.

[0116] The coil holder 81A has a slot 814 instead of multiple hooks 813 (see...) Figure 6 The slot 814 is a groove provided on the rear surface of the coil holder 81A. When viewed in the front / back direction, the slot 814 is annular. The slot 814 is provided along the inner edge of the opening 8110. Multiple slots (e.g., nine) are available. Figure 10 Only three of them are shown in the diagram. The cutouts 815 are configured to pass through the bottom surface of the slot 814 to penetrate the coil holder 81A in the front / back direction. Additionally, as... Figure 11 As shown, the area of ​​the cylinder 811 located in front of each cut 815 is the cavity 816.

[0117] The first bearing retainer 7A is attached to the coil frame 81A by rotating at least one of the components of the first bearing retainer 7A and the coil frame 81A relative to the other component in the direction of rotation of the rotation shaft 51 or in the opposite direction of rotation of the rotation shaft 51. An exemplary process for attaching the first bearing retainer 7A to the coil frame 81A will now be described.

[0118] First, such as Figure 11 As shown, the first bearing retainer 7A is placed in front of the coil holder 81A. The plurality of hooks 74 of the first bearing retainer 7A correspond one-to-one with the plurality of cuts 815 of the coil holder 81A. Next, the first bearing retainer 7A is moved rearward so that each hook 74 is inserted into its corresponding cut 815 via a cavity 816 on the front side of the cut 815.

[0119] Next, the first bearing retaining part 7A is rotated in the direction of rotation of the rotating shaft 51 (or the opposite direction). As a result, the position of each hook part 74 changes relative to its corresponding cutout 815, such as... Figure 12 and Figure 10As shown. That is, each hook 74 moves to the position where the hook 74 contacts the bottom surface of the slot 814. Therefore, as Figure 9 As shown, the first bearing retaining part 7A is attached to the coil frame 81A, and each hook part 74 is sandwiched between the bottom surface of the slot 814 and the front end of the inner cylinder part 3.

[0120] As can be seen, according to this third variation, the first bearing retainer 7A is attached to the coil holder 81A through a process involving rotation. This reduces the possibility of the first bearing retainer 7A detaching from the coil holder 81A.

[0121] Alternatively, the first bearing retainer 7A may also be attached to the coil frame 81A from the rear.

[0122] (Reference example: Fourth variation)

[0123] Next, we will refer to Figures 13 to 15 The brushless motor 1B according to the fourth modification is described as a reference example. In the following description, any constituent element of this fourth modification having the same function as the corresponding part of the above-described embodiment will be indicated by the same reference numerals as the corresponding part, and its description will be omitted here.

[0124] In this fourth variation, the fan 9B has a different shape than the fan 9 according to the exemplary embodiment described above. Furthermore, in the brushless motor 1B, the first bearing retainer 7B has a different shape than the first bearing retainer 7 according to the exemplary embodiment described above.

[0125] Furthermore, in this fourth variation, the rotating shaft 51 also has a different shape than the corresponding portion in the exemplary embodiment described above. However, the rotating shaft 51 does not necessarily have a different shape. Additionally, although the brushless motor 1B according to this fourth variation does not include the cover 55 (see...), Figure 2 However, the brushless motor 1B may include a cover 55.

[0126] When viewed in a front-to-back direction, fan 9B is circular. Fan 9B includes a disk 91B and multiple blades 92B.

[0127] The disk portion 91B has a recess 911 on one of its surfaces (front surface). The interior space of the recess 911 is truncated conical in shape, with its opening area decreasing towards the bottom. The disk portion 91B has a shaft hole 910 provided through the bottom surface of the recess 911. The rotating shaft 51 passes through the shaft hole 910.

[0128] Multiple blades 92B are disposed on one surface (rear surface) of the disk portion 91B and located near the outer edge of the disk portion 91B. The longitudinal axis of each blade of the multiple blades 92B is aligned with the radius of the disk portion 91B.

[0129] Stator 2 includes a first bearing retainer 7B. The first bearing retainer 7B includes a core 75 and a plurality of (e.g., Figure 13 (9 of them) blades 76 and seat 77.

[0130] The core 75 is disc-shaped. The core 75 has a recess 702 on one of its surfaces (the rear surface). A first bearing 53 is inserted into the recess 702. That is, the first bearing 53 is held by a first bearing retainer 7B. The core 75 has a shaft hole 701 that passes through the bottom surface of the recess 702. A rotating shaft 51 passes through the shaft hole 701.

[0131] The seat 77 is annular. The seat 77 is located behind the core 75. The seat 77 is attached to the outer cylindrical portion 22 of the stator core 20. The seat 77 can be integrally formed with the stator core 20, for example, by insert molding. The first bearing 53 is held by the stator core 20 via the first bearing retainer 7B. Alternatively, the seat 77 can be held by the coil holder 81.

[0132] Multiple blades 76 extend radially from the core 75. Each blade 76 is L-shaped. The multiple blades 76 connect the core 75 and the seat 77 to each other. The multiple blades 76 cover the fan 9B. Air generated by the fan 9B passes through the gaps between the multiple blades 76. In addition, the multiple blades 76 (partially) cover the opening 8110 of the coil frame 81, thereby reducing the possibility of foreign objects entering the space where the rotor core 6 is arranged.

[0133] The fan 9B is mounted between the first bearing 53 and the rotor core 6. The first bearing 53 is arranged in the space surrounded by the first bearing retainer 7B and the fan 9B.

[0134] Compared to the case where at least one of the first bearing 53 or the second bearing 54 is held by the power tool body 108, this fourth variation and the above exemplary embodiments also improve the accuracy of the gap between the rotor 5 and the stator 2.

[0135] Alternatively, in the exemplary embodiments and the first to third modifications, the fan 9 may also be disposed between the first bearing 53 and the rotor core 6 as in the fourth modification.

[0136] (Other variations of the implementation method)

[0137] Next, other variations of the exemplary embodiments will be listed one by one. Optionally, two or more variations described below may be suitably combined. Alternatively, any variation to be described below may also be suitably combined with any of the variations described above.

[0138] The first bearing retainer 7 and the second bearing retainer 823 are preferably held by at least the stator core 20. The first bearing retainer 7 and the second bearing retainer 823 may be held by the power tool body 108 or may not be held by the power tool body 108.

[0139] Additionally, the first bearing 53 may be held by the power tool body 108 via the first bearing holding part 7, or it may not be held. The second bearing 54 may be held by the power tool body 108 via the second bearing holding part 823, or it may not be held.

[0140] The second bearing 54 need not be held by the stator 2. Alternatively, the second bearing 54 may be held solely by the power tool body 108, in addition to the power tool body 108 and the stator 2.

[0141] The first contact surface 31 of the stator core 20 need not be the inner circumferential surface of the inner cylinder portion 3. Alternatively, the stator core 20 may include a protrusion that protrudes from the central core 21 along the axis of rotation 51 (i.e., in the front / back direction) and may have the first contact surface 31. Alternatively, the two end pieces 42 of each of the plurality of teeth 4 or the outer cylinder portion 22 may have the first contact surface 31.

[0142] In the above exemplary embodiments, although the first bearing retaining portion 7 has a second contact surface 720 that contacts the first contact surface 31, the second bearing retaining portion 823 may also have a second contact surface that contacts the first contact surface 31. Furthermore, the first contact surface 31 contacted by the second contact surface 720 of the first bearing retaining portion 7 and the first contact surface contacted by the second contact surface of the second bearing retaining portion 823 may be different surfaces.

[0143] The coil frame 81 and the coil frame 82 can be integrally formed with each other. More specifically, the coil frame 81 and the coil frame 82 can be formed as a single component with electrical insulation properties.

[0144] The first bearing retaining part 7 does not need to be part of the stator 2. That is, the first bearing retaining part 7 can be provided separately from the stator core 20, the coil frame 81, 82 and other components forming the stator 2.

[0145] At least one of the first bearing retainer 7 or the second bearing retainer 823 may not have electrical insulation properties. At least one of the first bearing retainer 7 or the second bearing retainer 823 may be made of a metal such as aluminum.

[0146] In the above exemplary embodiment, the first bearing retaining portion 7 is arranged in front of the rotor core 6, and the second bearing retaining portion 823 is arranged behind the rotor core 6. Conversely, the first bearing retaining portion 7 may be arranged behind the rotor core 6, and the second bearing retaining portion 823 may be arranged in front of the rotor core 6.

[0147] Each of the first bearing 53 and the second bearing 54 need not be a ball bearing, but may be, for example, a bushing.

[0148] The first bearing 53 may be integrally formed with the first bearing retaining part 7. The second bearing 54 may be integrally formed with the second bearing retaining part 823.

[0149] In the exemplary embodiment described above, the first contact surface 31 and the second contact surface 720 contact each other at multiple points. Alternatively, the first bearing retainer 7 can also be positioned by bringing the first contact surface 31 and the second contact surface 720 into contact with each other over a specific length. This specific length may be, for example, at least one-quarter of the circumference of the inner circumferential surface of the inner cylinder portion 3 (i.e., the first contact surface 31).

[0150] (Summary)

[0151] The above-described embodiments and their variations may be specific implementations of the following aspects of this disclosure.

[0152] The brushless motor (1, 1A) according to the first aspect includes a rotor (5), a stator (2), a bearing (first bearing 53), and a bearing retainer (first bearing retainer 7, 7A). The rotor (5) includes a rotating shaft (51), a rotor core (6), and a plurality of permanent magnets (52). The rotor core 6 holds the rotating shaft (51). The plurality of permanent magnets (52) are held by the rotor core (6). The stator (2) includes a stator core (20) and a plurality of coils (23). The stator core (20) is configured to surround the rotor (5). The plurality of coils (23) are wound around the stator core (20). The bearing rotatably supports the rotating shaft (51). The bearing retainer holds the bearing. The stator core (20) has a first contact surface (31). The normal vector of the first contact surface (31) is aligned with a radially inward direction defined for the rotating shaft (51). The bearing retainer has a second contact surface (720, 712) that contacts the first contact surface (31). The normal vectors of the second contact surfaces (720, 712) are aligned with the radially outward direction defined for the rotation axis (51). The bearing retainer is positioned by bringing the first contact surface (31) into contact with the second contact surfaces (720, 712).

[0153] According to this configuration, the bearing retainer (first bearing retainer 7, 7A) is positioned by bringing the first contact surface (31) into contact with the second contact surfaces (720, 712). That is, the bearing retainer and the bearing (first bearing 53) held by the bearing retainer are positioned by the stator core (20). The bearing supports the rotation axis (51) of the rotor (5). Compared with the case where the bearing is not positioned by the stator core (20) (for example, the case where the bearing is only held by the power tool body 108), this improves the accuracy of the clearance between the rotor (5) and the stator (2).

[0154] In the brushless motor (1, 1A) according to the second aspect, which can be implemented in conjunction with the first aspect, the stator core (20) includes: a cylindrical inner cylinder portion (3); and a plurality of teeth (4). The plurality of teeth (4) protrude from the inner cylinder portion (3) in a radially outward direction defined with respect to the inner cylinder portion (3). A first contact surface (31) is the inner circumferential surface of the inner cylinder portion (3).

[0155] According to this structure, the second contact surface (720, 712) contacts the inner cylinder (3), which improves the accuracy of the gap between the inner cylinder (3) and the rotor core (6) compared to the case where the second contact surface (720, 712) contacts other constituent elements (i.e., constituent elements further away from the rotor core 6) besides the inner cylinder (3).

[0156] The brushless motor (1, 1A) according to the third aspect, which can be implemented in conjunction with the first or second aspect, also includes a second bearing (54) separate from the first bearing (53) used as a bearing. The second bearing (54) rotatably supports the rotating shaft (51). The stator (2) includes: a first bearing retainer (7, 7A) used as a bearing retainer; and a second bearing retainer (823) disposed separately from the first bearing retainer (7, 7A). The second bearing retainer (823) retains the second bearing (54). The rotor core (6) is interposed between the first bearing (53) and the second bearing (54). The first bearing retainer (7, 7A) and the second bearing retainer (823) are held by the stator core (20).

[0157] According to this configuration, both the first bearing (53) and the second bearing (54) of the rotating shaft (51) supporting the rotor (5) are held by the stator (2). Compared to the case where at least one of the first bearing (53) or the second bearing (54) is held by the power tool body (108), this reduces the possibility that the assembly precision between the power tool body (108) and the brushless motor (1, 1A) (such as the presence or absence of looseness between them) may affect the precision of the gap between the rotor (5) and the stator (2). In other words, this improves the precision of the gap between the rotor (5) and the stator (2).

[0158] In the brushless motor (1, 1A) according to the fourth aspect, which can be implemented in conjunction with any of the first to third aspects, the stator (2) includes a coil frame (81, 81A). The coil frame (81, 81A) has electrical insulation properties and is attached to the stator core (20). A plurality of coils (23) are wound around the stator core (20) via the coil frame (81, 81A). Bearing retainers (first bearing retainers 7, 7A) form part of the coil frame (81, 81A).

[0159] Compared to the case where the bearing holding part (first bearing holding part 7, 7A) and the coil frame (81, 81A) are set separately, this structure can reduce the number of components forming the brushless motor (1, 1A).

[0160] In the brushless motor (1, 1A) according to the fifth aspect, which can be implemented in conjunction with any of the first to third aspects, the stator (2) includes a coil frame (81, 81A). The coil frame (81, 81A) has electrical insulation properties and is attached to the stator core (20). A plurality of coils (23) are wound around the stator core (20) via the coil frame (81, 81A). Bearing retainers (first bearing retainers 7, 7A) are attached to the coil frame (81, 81A).

[0161] According to this construction, the bearing retainer (first bearing retainer 7, 7A) is attached to the coil frame (81, 81A) whose shape can be designed relatively freely, thereby making it easier to provide the attachment structure.

[0162] In the brushless motor (1, 1A) according to the sixth aspect, which can be implemented in conjunction with the fifth aspect, the coil holder (81, 81A) has an opening (8110) for the rotating shaft (51) to pass through. The bearing retainer (first bearing retainer 7, 7A) has a shaft hole (701) for the rotating shaft (51) to pass through. The bearing retainer closes the opening (8110).

[0163] This design can reduce the possibility of foreign objects entering the space where the rotor core (6) is arranged.

[0164] In the brushless motor (1) according to the seventh aspect, which can be implemented in conjunction with the fifth or sixth aspect, at least one of the bearing retainer (first bearing retainer 7) and the coil holder (81) includes a hook (73, 813) to hook onto the other component, which is either the bearing retainer (first bearing retainer 7) or the coil holder (81). By moving one or both of the bearing retainer and the coil holder (81) along the axis of rotation (51), the hook (73, 813) of the at least one component hooks onto the other component.

[0165] Even without using screws or any other components, this construction enables the bearing retainer (first bearing retainer 7) to be attached to the coil frame (81).

[0166] In the brushless motor (1, 1A) according to the eighth aspect, which can be implemented in conjunction with any of the fifth to seventh aspects, at least one of the bearing retainer (first bearing retainer 7, 7A) and the coil carrier (81, 81A) includes a hook (73, 74, 813) to hook onto another component, which is either the bearing retainer (first bearing retainer 7, 7A) or the coil carrier (81, 81A). The hook (73, 74, 813) restricts the movement of the bearing retainer relative to the coil carrier (81) along the axis of rotation (51) to the extent that the second contact surface (720, 712) remains in contact with the first contact surface (31).

[0167] This configuration allows the first contact surface (31) and the second contact surface (720, 712) to remain in contact with each other.

[0168] In the brushless motor (1A) according to the ninth aspect, which can be implemented in conjunction with any of the fifth to eighth aspects, the bearing retainer (first bearing retainer 7A) is attached to the coil frame (81A) by rotating at least one of the bearing retainer and the coil frame (81A) relative to the other of the bearing retainer and the coil frame (81A) in the direction of rotation of the rotating shaft (51) or in the opposite direction of rotation of the rotating shaft (51).

[0169] According to this structure, the bearing retainer (first bearing retainer 7A) is attached to the coil frame (81A) through a process involving rotation, thereby reducing the possibility of the bearing retainer detaching from the coil frame (81A).

[0170] The brushless motor (1, 1A) according to the tenth aspect, which can be implemented in conjunction with any of the first to ninth aspects, includes a fan (9, 9A). The fan (9, 9A) is held by a rotating shaft (51).

[0171] This design can reduce the temperature rise of the rotor (5) and stator (2).

[0172] In the brushless motor (1, 1A) according to the eleventh aspect, which can be implemented in conjunction with the tenth aspect, the fan (9, 9A) is mounted between the bearing (first bearing 53) and the rotor core (6).

[0173] This configuration allows the fans (9, 9A) to be positioned near the rotor core (6).

[0174] In the brushless motor (1) according to the twelfth aspect, which can be implemented in combination with any of the first to eleventh aspects, the bearing retainer (first bearing retainer 7) includes a base (71) and a rib (72). The rib (72) protrudes from the base (71) along the axis of the rotation shaft (51). The rib (72) has a second contact surface (720).

[0175] Compared to the case where the base (71) has a second contact surface (720) without ribs (72), this configuration can reduce the possibility of interference between the rotor core (6) and the bearing retainer (first bearing retainer 7).

[0176] Note that the components according to aspects two through twelfth are not essential components for the brushless motor (1, 1A), but can be appropriately omitted.

[0177] The power tool (10) according to the thirteenth aspect includes a brushless motor (1, 1A) according to any one of the first to twelfth aspects and a power tool body (108). The brushless motor (1, 1A) is housed in the power tool body (108).

[0178] This design improves the accuracy of the gap between the rotor (5) and the stator (2).

[0179] List of reference numerals

[0180] 1. 1A brushless motor

[0181] 2. Stator

[0182] 20 stator cores

[0183] 23 coils

[0184] 3 inner cylinder

[0185] 4 teeth

[0186] 31 First contact surface

[0187] 5 rotors

[0188] 51 Rotation axis

[0189] 52 permanent magnet

[0190] 53 First Bearing (Bearing)

[0191] 54 Second Bearing

[0192] 6 Rotor core

[0193] 7.7A First bearing retaining part (bearing retaining part)

[0194] 701 shaft hole

[0195] 71 Base

[0196] 72 ribs

[0197] 720, 712 Second contact surfaces

[0198] Hook and hook section 73, 74, 813

[0199] 81, 81A Coil Frame

[0200] 8110 Opening

[0201] 823 Second bearing retaining part

[0202] 9. 9A Fan

[0203] 10 Power tools

[0204] 108 Power Tool Body

Claims

1. A brushless motor, comprising: A rotor includes: a rotating shaft; a rotor core that holds the rotating shaft; and a plurality of permanent magnets held by the rotor core. A stator includes: a stator core configured to surround the rotor; and a plurality of coils wound around the stator core; A bearing that rotatably supports the rotating shaft; and The bearing retainer holds the bearing. The stator core has a first contact surface, the normal vector of which is aligned with a radially inward direction defined with respect to the rotation axis. The bearing retaining portion has a second contact surface that contacts the first contact surface, and the normal vector of the second contact surface is aligned with a radially outward direction defined for the rotation axis. The bearing retaining portion is positioned by bringing the first contact surface into contact with the second contact surface. The stator includes a coil frame that has electrical insulation properties and is attached to the stator core. The plurality of coils are wound around the stator core via the coil frame, and The bearing retainer forms part of the coil frame.

2. The brushless motor according to claim 1, wherein, The stator core includes: a cylindrical inner cylinder portion; and a plurality of teeth, each tooth protruding from the inner cylinder portion in a radially outward direction defined with respect to the inner cylinder portion, and The first contact surface is the inner circumferential surface of the inner cylinder.

3. The brushless motor according to claim 1 or 2 further includes a second bearing separate from the first bearing used as the bearing, the second bearing being rotatably capable of holding the rotating shaft, wherein, The stator includes: The first bearing retainer serving as the bearing retainer; and A second bearing retaining portion is provided to hold the second bearing, and the second bearing retaining portion is separately disposed from the first bearing retaining portion. The rotor core is mounted between the first bearing and the second bearing, and The first bearing retainer and the second bearing retainer are held by the stator core.

4. The brushless motor according to claim 1 or 2, wherein, The stator includes a coil frame that has electrical insulation properties and is attached to the stator core. The plurality of coils are wound around the stator core via the coil frame, and The bearing retainer is attached to the coil frame.

5. The brushless motor according to claim 4, wherein, The coil frame has an opening through which the rotating shaft passes, and The bearing retainer has a shaft hole through which the rotating shaft passes and closes the opening.

6. The brushless motor according to claim 4, wherein, At least one of the bearing retainer and the coil frame includes a hook portion for hooking onto another component of the bearing retainer and the coil frame, and By moving one or both of the bearing retainer and the coil holder along the axis of the rotation shaft, the hook portion of at least one component hooks onto the other component.

7. The brushless motor according to claim 4, wherein, At least one of the bearing retainer and the coil frame includes a hook portion for hooking onto another component of the bearing retainer and the coil frame, and The hook portion is configured to limit the movement of the bearing retainer relative to the coil frame along the axis of the rotation to the extent that the second contact surface remains in contact with the first contact surface.

8. The brushless motor according to claim 4, wherein, The bearing retainer is attached to the coil frame by rotating at least one of the bearing retainer and the coil frame relative to another member of the bearing retainer and the coil frame in the direction of rotation of the rotating shaft or in the opposite direction of rotation of the rotating shaft.

9. The brushless motor according to claim 1 or 2, comprising a fan held by the rotating shaft.

10. The brushless motor according to claim 9, wherein, The fan is mounted between the bearing and the rotor core.

11. The brushless motor according to claim 1 or 2, wherein, The bearing retaining portion includes: Base; and A rib that protrudes from the base along the axis of the rotation and has the second contact surface.

12. An electric tool, comprising: The brushless motor according to any one of claims 1 to 11; as well as The power tool body, which houses the brushless motor.

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