Electric work machines

Abstract

To provide an electric working machine which enables easy adjustment of a rotation balance of a rotor while reducing a length of a brushless motor in a direction of a motor shaft.SOLUTION: An impact driver, an electric working machine, includes: a brushless motor having a stator and a rotor 61; and a rear motor bearing 64 and a front motor bearing 66 which rotatably support the motor 61. The rotor 61 has: a cylindrical magnet holding part 100; and a cylindrical magnet 102. The magnet holding part 100 has a front recessed part 111 and a rear recessed part 112 which are recessed in an axial direction and holds the magnet 102 exposed in a radial direction. An axial length of the magnet 102 is shorter than an axial length of the magnet holding part 100. Parts C1, C2 of the magnet holding part 100 are exposed in the radial direction. A part of the rear motor bearing 64 enters the rear recessed part 112. A part of the front motor bearing 66 enters the front recessed part 111.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to electric power tools such as impact drivers, gardening tools such as lawn mowers, air compressors for pneumatic tools, and electric power tools such as transport vehicles. [Background technology]

[0002] As described in U.S. Patent Application Publication No. 2021 / 0194319 (Patent Document 1), an impact driver using a brushless motor as a drive source is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent Application Publication No. 2021 / 0194319 Summary of the Invention [Problem to be solved by the invention]

[0004] 2. Description of the Related Art In electric power tools such as impact drivers, there is a demand for technology that can shorten the length of a brushless motor in the direction of the motor shaft while easily adjusting the rotational balance of the rotor. [Means for solving the problem]

[0005] This specification discloses an electric power tool. The electric power tool may include a brushless motor having a stator and a rotor, and a motor bearing that rotatably supports the rotor. The rotor may have a cylindrical or columnar magnet holder and a cylindrical magnet. The magnet holder may have a recess that is recessed in the axial direction, and may hold the magnet in a state where it is exposed in the radial direction. The axial length of the magnet may be shorter than the axial length of the magnet holder. A portion of the magnet holder may be exposed. At least a portion of the motor bearing may be recessed in the recess. [Effects of the Invention]

[0006] According to the electric power tool of the present disclosure, the length of the brushless motor in the direction of the motor shaft can be shortened, and the rotational balance of the rotor can be easily adjusted. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a right side view of an impact driver according to a first embodiment of the present disclosure. FIG. [Figure 2] FIG. 2 is a central vertical cross-sectional view of the upper part of FIG. [Figure 3] FIG. 3 is a perspective view of the rotor and fan, as well as the rear motor bearing and the front motor bearing in FIG. 2. [Figure 4] Fig. 4A is a central vertical cross-sectional view of Fig. 3. Fig. 4B is a view corresponding to the upper half of Fig. 4A according to a modified example. [Figure 5] FIG. 10 is a perspective view of a rotor, a fan, a rear motor bearing, and a front motor bearing according to a second embodiment of the present disclosure. [Figure 6] FIG. 6 is a central longitudinal cross-sectional view of FIG. 5. [Figure 7] FIG. 10 is a perspective view of a rotor, a fan, a rear motor bearing, and a front motor bearing according to a third embodiment of the present disclosure. [Figure 8] FIG. 8 is a central longitudinal cross-sectional view of FIG. 7. [Figure 9] FIG. 10 is a perspective view of a rotor, a fan, a rear motor bearing, and a front motor bearing according to a fourth embodiment of the present disclosure. [Figure 10] FIG. 10 is a central vertical cross-sectional view of FIG. 9. [Figure 11] FIG. 10 is a perspective view of a rotor, a fan, a rear motor bearing, and a front motor bearing according to a fifth embodiment of the present disclosure. [Figure 12] FIG. 12 is a central longitudinal cross-sectional view of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] In one embodiment of the present disclosure, the magnet of the rotor of the impact driver may exhibit polar anisotropy, and the magnet holder may be made of a non-magnetic material, which makes it easier to adjust the rotational balance of the rotor. In one embodiment of the present disclosure, the magnet may exhibit radial anisotropy, and the magnet holder may be made of a magnetic material, which makes it easier to prepare at least one of the magnet and the magnet holder. In one embodiment of the present disclosure, a portion of the radially outer surface of the magnet holder may be exposed, which makes it easier to apply a cutting tool to the magnet holder and to adjust the rotational balance of the rotor. In one embodiment of the present disclosure, an adhesive reservoir may be provided on at least one of the radially inner surface of the magnet and the radially outer surface of the magnet holder, making it easier and stronger to bond the magnet to the magnet holder. In one embodiment of the present disclosure, the magnet holder may have an abutment portion that abuts against the magnet from the axially outer side, which makes it easier to position the magnet relative to the magnet holder. In one embodiment of the present disclosure, the magnet holder may include an inner ring holder that holds the inner ring of the motor bearing. In this case, the magnet holder also serves as the inner ring holder, which enables further shortening of the length in the motor axial direction and reduces the number of parts. In one embodiment of the present disclosure, two motor bearings may be provided on either side of the magnet holder in the axial direction. An inner ring holder may be provided for each motor bearing, and the inner ring holders may have similar shapes. In this case, assembly of the rotor is further facilitated. In one embodiment of the present disclosure, the rotor may have a motor shaft rotatably supported by a motor bearing. The motor shaft may be integral with the magnet holder. In this case, the number of parts is reduced. Also, misalignment between the motor shaft and the magnet holder is suppressed. In one embodiment of the present disclosure, the motor shaft may be separate from the magnet holder, which makes it easier to design and manufacture the motor shaft, which is the motor bearing support portion, and the magnet holder. In one embodiment of the present disclosure, the impact driver may further include a housing that holds a motor bearing. At least a portion of the portion of the housing that holds the motor bearing may be recessed. In this case, the axial length of the motor bearing that fits into the recessed portion can be shortened, thereby more easily supporting the motor bearing with greater strength.

[0009] This specification also discloses an electric power tool. This electric power tool may include a brushless motor having a stator and a rotor, and a motor bearing that rotatably supports the rotor. The rotor may have a cylindrical or columnar core holder, a cylindrical magnet holder, and multiple plate-shaped magnets. The core holder may have a recess that is recessed in the axial direction, and may hold the magnet holder in a state where it is exposed in the radial direction. The magnet holder may hold each magnet in a state where it is not exposed in the radial direction. The axial length of each of the magnet holder and the magnet may be shorter than the axial length of the core holder. A portion of the core holder may be exposed. At least a portion of the motor bearing may be recessed. In one embodiment of the present disclosure, a part of the radial outer surface of the core holding portion may be exposed, which makes it easier to apply a cutting tool to the core holding portion and to adjust the rotational balance of the rotor. In one embodiment of the present disclosure, an adhesive reservoir may be provided on at least one of the radially inner surface of the magnet holder and the radially outer surface of the core holder, which makes it easier and stronger to bond the magnet holder and the core holder to each other. In one embodiment of the present disclosure, the core holding portion may have an abutment portion that abuts against the magnet holding portion from the outside in the axial direction, which makes it easier to position the magnet holding portion relative to the core holding portion. In one embodiment of the present disclosure, the core holder may have an inner ring holder that holds the inner ring of the motor bearing. In this case, the core holder also serves as the inner ring holder, which enables further shortening of the length in the motor axial direction and reduces the number of parts. In one embodiment of the present disclosure, two motor bearings may be provided on either side of the core holder in the axial direction. An inner ring holder may be provided for each motor bearing, and the inner ring holders may have similar shapes. In this case, assembly of the rotor is further facilitated. In one embodiment of the present disclosure, the rotor may have a motor shaft rotatably supported by a motor bearing. The motor shaft may be integral with the core holder. In this case, the number of parts is reduced. Also, misalignment between the motor shaft and the core holder is suppressed. In one embodiment of the present disclosure, the motor shaft may be separate from the core holder, which makes it easier to design and manufacture the motor shaft, which is a motor bearing support portion, and the core holder. In one embodiment of the present disclosure, the impact driver may further include a housing that holds a motor bearing. At least a portion of the portion of the housing that holds the motor bearing may be recessed. In this case, the axial length of the motor bearing that fits into the recessed portion can be shortened, thereby more easily supporting the motor bearing with greater strength.

[0010] This specification also discloses an electric power tool. This electric power tool may include a brushless motor having a stator and a rotor, and a motor bearing that rotatably supports the rotor. The electric power tool may include a fan that generates airflow. The rotor may include a cylindrical balance correction member. The balance correction member may have a recess that is recessed in the axial direction. A portion of the balance correction member may be exposed. At least a portion of the motor bearing may be recessed in the recess. The fan may be fixed to the balance correction member. In this case, the balance correction member used to adjust the rotational balance of the rotor also serves as a fan fixing function, reducing the number of parts. In one embodiment of the present disclosure, a portion of the radial outer surface of the balance correction member may be exposed, which makes it easier to apply a cutting tool to the balance correction member and to adjust the rotational balance of the rotor. In one embodiment of the present disclosure, the rotor may have a cylindrical or columnar core holder, a cylindrical magnet holder, and a plurality of plate-shaped magnets. The core holder may hold the magnet holder in a state where it is exposed in the radial direction. The magnet holder may hold each magnet in a state where it is not exposed in the radial direction. The balance correction member may be provided axially outward of the magnet holder. In this case, in an IPM type, the balance correction member also serves as a fan fixing function, reducing the number of parts. In one embodiment of the present disclosure, two balance correction members may be provided on either side of the magnet holder in the axial direction, making it easier to adjust the rotational balance of the rotor. In one embodiment of the present disclosure, the impact driver may further include a housing that holds a motor bearing. At least a portion of the portion of the housing that holds the motor bearing may be recessed. In this case, the axial length of the motor bearing that fits into the recessed portion can be shortened, thereby more easily supporting the motor bearing with greater strength. [Example]

[0011] Hereinafter, embodiments of the present disclosure (including modified examples) will be described with reference to the accompanying drawings. The present disclosure is not limited to the embodiments and modified examples. The front, back, top, bottom, left and right directions in the embodiments and modified examples are defined for the convenience of explanation, and may change depending on at least one of the work situation and the movement of parts.

[0012] [First form] Fig. 1 is a right side view of an impact driver 1, which is an example of an impact tool and a handheld screw driver among power tools belonging to the electric power equipment according to a first embodiment of the present disclosure. Fig. 2 is a central vertical cross-sectional view of the upper part of Fig. 1. The impact driver 1 has a head portion 4 and a grip portion 6. The head portion 4 is cylindrical with its central axis extending in the front-rear direction. The grip portion 6 is cylindrical. The grip portion 6 protrudes downward from the bottom of the head portion 4. The grip portion 6 is the portion that the user holds. The grip portion 6 is connected to the head portion 4 at the lower rear of the head portion 4. The portion from the upper end of the grip portion 6 to the lower end of the head portion 4 forms a connecting portion 8 between the head portion 4 and the grip portion 6. In Figures 1 and 2, the right is the front.

[0013] The outer shell of the head portion 4 and the outer shell of the grip portion 6 form a housing 10 . The housing 10 directly or indirectly holds various members. The housing 10 includes a motor housing 12 , a hammer case 13 , a rear cover 14 , a hammer case cover 15 , a bumper 16 , and a gear case 17 .

[0014] The motor housing 12 is made of plastic and is split into two halves, a left motor housing 12L and a right motor housing 12R. The left motor housing 12L has a plurality of screw boss portions 18. The right motor housing 12R has screw hole portions 19 with screw holes corresponding to the screw boss portions 18. The left motor housing 12L and the right motor housing 12R are joined together by screws 20 that enter the screw hole portions 19 and the screw boss portions 18. The motor housing 12 extends from the rear of the head portion 4 to the grip portion 6. The motor housing 12 has openings at the lower end of the grip portion 6 and at the front and rear ends of the rear of the head portion 4. A plurality of first air intake ports 24 are provided on both sides of the rear of the outer shell of the head unit 4 in the motor housing 12. Each of the first air intake ports 24 extends in the front-to-rear direction. There are four first air intake ports 24 on the right side, two at the top and bottom and two at the bottom and top. There are four first air intake ports 24 on the left side, two at the top and bottom and two at the bottom and top. Further, second air intake ports 25 are provided on both sides of the front lower portion of the outer shell portion of the head section 4 in the motor housing 12. Each second air intake port 25 extends in the front-rear direction.

[0015] The hammer case 13 is made of metal and has a cylindrical shape. The hammer case 13 is open at the front and rear. The hammer case 13 is a bell-shaped member whose front portion is smaller in diameter than its rear portion, and forms the outer shell of the front portion of the head part 4. The rear portion of the hammer case 13 is placed inside the opening at the top of the motor housing 12. The outer wall of the hammer case 13 is disposed inside each of the second intake ports 25 of the motor housing 12 .

[0016] The rear cover 14 is made of plastic. The rear cover 14 is dish-shaped. The rear cover 14 extends vertically and horizontally. The front end of the rear cover 14 is open forward. The rear cover 14 covers the opening of the motor housing 12 at the rear end of the head unit 4. The rear cover 14 is disposed at the rear end of the head unit 4. A plurality (two) of exhaust ports 26 (four in total) are provided in each of the upper right and upper left sections of the rear cover 14. A plurality (four) of exhaust ports 26 (eight in total) are provided in each of the lower right and lower left sections of the rear cover 14. Each of the exhaust ports 26 (12 in total) extends vertically. Each of the exhaust ports 26 extends circumferentially.

[0017] The hammer case cover 15 is made of plastic and is cylindrical. The hammer case cover 15 is disposed outside the center of the hammer case 13 in the front-rear direction.

[0018] The bumper 16 is made of an elastic material and has a ring shape. The bumper 16 is disposed on the outside of the front end of the hammer case 13 .

[0019] The gear case 17 is made of metal. The gear case 17 is dish-shaped. The gear case 17 extends vertically and horizontally. The gear case 17 is open to the front. A hole is provided in the vertical and horizontal center of the gear case 17 in the front-rear direction. The front portion of the gear case 17 is housed within the rear end portion of the hammer case 13. The rear portion of the gear case 17 is held by the motor housing 12. The housing 10 can be modified in various ways. For example, in the motor housing 12, the outer casing of the head portion 4 and the outer casing of the grip portion 6 may be separate components that can be combined with each other. Furthermore, in a split motor housing 12, the left motor housing 12L and the right motor housing 12R may be significantly different in at least one of size and shape. Furthermore, the left motor housing 12L and the right motor housing 12R may be combined using a method other than the screws 20 (such as a locking portion such as a pawl and a locked portion such as a pawl hole). The hammer case 13 may be split in half, and at least one of the hammer case cover 15 and the bumper 16 may be omitted. The materials of various components of the housing 10 may be changed. At least one of the number and arrangement of the first air intake ports 24 may be changed as needed. At least one of the number and arrangement of the second air intake ports 25 may be changed as needed. At least one of the number and arrangement of the exhaust ports 26 may be changed as needed.

[0020] The head unit 4 has an upper part of the housing 10, a motor 30, a fan 31, a power transmission unit 32, an anvil 34 as an output unit, an upper operation unit 36, and a plurality of (two) light units 38. In the head unit 4, a fan 31, a motor 30, a power transmission unit 32, and an anvil 34 are arranged in this order from the rear.

[0021] The grip portion 6 has a lower portion of the housing 10, a battery mounting portion 40, a controller 42, a main switch 44, and a forward / reverse switching lever 46. The forward / reverse switching lever 46 may be attached to the head unit 4.

[0022] The battery mounting section 40 is disposed at the lower end of the grip section 6. The battery mounting section 40 extends forward, backward, left and right relative to the upper portion. A battery 50 is attached to the battery attachment section 40. The battery 50 is mounted below the battery mounting section 40. The battery 50 is mounted by sliding it from the front to the rear of the battery mounting section 40. The sliding mounting direction of the battery 50 may be a direction other than from the front to the rear. The battery 50 may also be mounted in a manner other than sliding mounting. The battery 50 is an 18V (volt) lithium-ion battery. The battery 50 includes eight cells (not shown) housed in a plastic battery case. The cells are cylindrical and elongated in the axial direction, facing left and right when the battery 50 is installed. The battery 50 holds power to drive the motor 30. Any lithium-ion battery with a voltage of 10.8V, 14.4V, 25.2V, 28V, 36V, etc. may be used as the battery 50. A lithium-ion battery with a voltage less than 10.8V or more than 36V may also be used as the battery 50. Other types of batteries may also be used. Multiple batteries 50 may also be used.

[0023] The controller 42 is held inside the battery mounting section 40 . The controller 42 controls the motor 30 . In addition, a plurality of buttons (not shown) and a display (not shown) are electrically connected to the controller 42. The buttons and display are arranged on the top of the battery attachment section 40. The controller 42 controls the buttons and display. Operating one button sets at least one of the impact mode and the impact intensity, which are related to the type of impact. The display can display various settings and the remaining charge of the battery 50, etc.

[0024] The main switch 44 is disposed at the upper end of the grip portion 6 . The main switch 44 includes a switch body 54 and a trigger 56 . The main switch 44 is positioned with the front part of the trigger 56 exposed. The trigger 56 is disposed on the front side of the switch body 54 . When the user operates the trigger 56 rearward, after a predetermined amount of play, the switch main body 54 turns on, turning on the main switch 44. Furthermore, when the trigger 56 is further operated rearward from that state, the state of the signal issued by the switch main body 54 changes depending on the amount of rearward operation. Alternatively, the play may be omitted and the main switch 44 may be turned on immediately when the trigger 56 starts to be operated rearward.

[0025] The forward / reverse switching lever 46 is disposed between the trigger 56 and the hammer case 13 . The forward / reverse switching lever 46 passes through the connecting portion 8 between the head portion 4 and the grip portion 6 from side to side. The forward / reverse switching lever 46 can be pushed left or right to switch the rotation direction of the motor 30 (forward rotation direction or the opposite reverse direction).

[0026] The motor 30 of the head unit 4 is a brushless motor and a DC motor. The motor 30 has a stator 60 and a rotor 61. The rear cover 14 is fixed to the stator 60 by screws (not shown) in the front-rear direction. The stator 60 is cylindrical. The stator 60 has a stator core (not shown), an insulator (not shown), and a plurality of coils (not shown). The stator core is cylindrical. The stator core has a plurality of teeth on its inner surface. Each tooth extends in the radial direction. Coils, the number of which is equal to the number of teeth, are wound around the corresponding teeth via insulators. The center portion of the rotor 61 is disposed radially inward of the stator 60. The motor 30 is an inner rotor type. The rotor 61 has a motor shaft 62. The motor shaft 62 is cylindrical and extends in the front-to-rear direction. The rotor 61 rotates around an imaginary central axis of the motor shaft 62. A toothed portion having a plurality of teeth is formed at the tip of the motor shaft 62. The motor 30 is the driving portion of the impact driver 1. The toothed portion of the motor shaft 62 may be separate from the other portions. The motor shaft 62 is rotatably supported by a rear motor bearing 64 and a front motor bearing 66 . The rear motor bearing 64 rotatably supports the rear end of the motor shaft 62. The rear motor bearing 64 is held by the rear cover 14. The rear motor bearing 64 is disposed on the rear side of the fan 31. The front motor bearing 66 rotatably supports the front end of the motor shaft 62. The front motor bearing 66 is held by the gear case 17.

[0027] The fan 31 is fixed integrally to the motor shaft 62 . The fan 31 is a centrifugal fan. However, other types of fan, such as an axial flow fan, may also be used as the fan 31. The exhaust port 26 of the rear cover 14 is disposed radially outward of the fan 31 .

[0028] The power transmission unit 32 has a planetary gear mechanism 70 which is a speed reduction mechanism, a spindle 72 , a spring 74 which is an elastic member, a hammer 76 , a hammer ball 77 , a plurality of spring balls 78 , and a hammer washer 79 . The rotation of the rotor 61 is transmitted to the spindle 72. The rotational force of the spindle 72 is then converted into a rotational impact force by the power transmission unit 32 and transmitted to the anvil 34. The anvil 34 is a member that receives the rotational impact force and can rotate around an imaginary axis in the front-to-rear direction. The anvil 34 holds a bit (a tool bit) (not shown) (tool bit holding unit). A screwdriver can be used as the bit, and the impact driver 1 can be used to tighten screws.

[0029] The planetary gear mechanism 70 is interposed between the tip of the motor shaft 62 and a spindle 72 . The planetary gear mechanism 70 reduces the speed of the rotation of the motor shaft 62 and transmits it to the spindle 72 . The outer shell of the planetary gear mechanism 70 is a gear case 17 .

[0030] The spindle 72 is cylindrical and extends in the front-to-rear direction. The spindle 72 is supported by a spindle bearing 80 so as to be rotatable around its imaginary central axis. The spindle bearing 80 is disposed on the rear side of the planetary gear mechanism 70. The spindle bearing 80 is held by the gear case 17. In the radial direction, the outer ring of the front motor bearing 66 is disposed radially inward from the inner ring of the spindle bearing 80. The tip of the motor shaft 62 is inserted into the bore of the spindle 72 .

[0031] The spring 74 is made of metal and has a coil shape.

[0032] The hammer 76 is made of metal and has a cylindrical shape with its axial direction extending in the front-to-rear direction. The front part of the spindle 72 is inserted into a hole in the center of the hammer 76. Hammer balls 77 are interposed between the hammer 76 and the spindle 72. Each hammer ball 77 guides the hammer 76 mainly in the front-to-rear direction during impact. The hammer 76 also has a cylindrical recess 76P recessed forward from the rear surface. The recess 76P accommodates the front portion of the spring 74. The ring-shaped front end portion of the spring 74 is disposed at the bottom (front end) of the recess 76P via a plurality of spring balls 78 and a hammer washer 79.

[0033] The anvil 34 at the front of the hammer 76 is cylindrical and extends in the front-to-rear direction. The anvil 34 is supported by a plurality of (two) anvil bearings 90 so as to be rotatable about its own imaginary central axis. Each anvil bearing 90 is held in an opening at the front end of the hammer case 13. The anvil bearings 90 are lined up in the front-to-rear direction. A plurality of (pair of) extending portions 34E each extending in a radial direction are formed on the rear portion of the anvil 34. The extending portions 34E are arranged on the rear side of the anvil bearing 90. The front end of the spindle 72 is inserted into the center of the rear end of the anvil 34. The rotation of the spindle 72 is transmitted to the anvil 34 via the hammer 76. The hammer 76 transmits the rotation of the spindle 72 to the anvil while being appropriately cushioned by a spring 74 that is stretched between the spindle 72 and the hammer 76. The hammer 76 strikes the anvil 34 by repeatedly colliding with the extension portion 34E according to the set impact mode and impact intensity. The main direction of power transmission in the power transmission unit 32 is the direction of rotation around the longitudinal axis. The anvil 34 receives a bit (not shown) at its front portion. The bit is removably attached to the anvil 34.

[0034] The upper operating unit 36 ​​is disposed in the lower part of the head unit 4, above the trigger 8, and in front of the forward / reverse switching lever 28. The upper operating unit 36 ​​has an operating unit 92 and a transmitting unit 94 . The operation unit 92 is a button that can be operated backward by the user. Note that the operation unit 92 may be a switch in a form other than a button. The transmitting unit 94 transmits signals for switching various states etc. in response to the operation of the operating unit 92 . The upper operating portion 36 is placed in a mounting portion formed below the front end portion of the head portion 4 in the motor housing 12, with the front portion of the operating portion 92 exposed. The operating portion 92 is disposed on the outside (below) of the hammer case 13. The upper operation unit 36 ​​is electrically connected to the controller 42 by a lead wire (not shown). The controller 42 receives a signal from the transmitter 94.

[0035] Furthermore, light units 38 are disposed on the left and right sides of the front of the head unit 4 (FIG. 1). Each light unit 38 has an LED (not shown) as a light and a light case 38C as a case for the LED. Each light portion 38 is held by the motor housing 12 . Each light unit 38 is electrically connected to the controller 42 by a lead wire (not shown). The controller 42 controls each light unit 38. When each light section 38 is turned on, light is projected forward, illuminating the front side of the anvil 34. The light may be other than an LED. The light unit 38 may be provided on only one of the left and right sides, or may be provided on the upper part of the head unit 4 instead of or together with the left and right sides. One light unit 38 may be provided, or three or more light units 38 may be provided.

[0036] 3 is a perspective view of the rotor 61, the fan 31, the rear motor bearing 64, and the front motor bearing 66 as seen from the upper right front side. FIG. 4A is a central vertical cross-sectional view of FIG. The rotor 61 includes a motor shaft 62, a magnet holder 100, and a magnet 102.

[0037] The magnet holder 100 is cylindrical. The magnet holder 100 is made of a non-magnetic material, such as stainless steel, brass, a brass alloy, aluminum, or an aluminum alloy. The magnet holder 100 may also be in the shape of a regular polygonal column. The magnet holder 100 is fixed to the motor shaft 62. The magnet holder 100 is disposed radially outward of the motor shaft 62. The magnet holder 100 extends from the center to the rear end of the motor shaft 62 in the front-to-rear direction. While the magnet holder 100 is part of the rotor 61, it is a separate member from the motor shaft 62 before being fixed, and therefore can also be considered a magnet holder member. The fan 31 is fixed to the rear end of the magnet holding portion 100 via a fan bushing 104. The fan bushing 104 may be a component of the fan 31 or may be a component of the rotor 61. The magnet holder 100 has a magnet holder main body 110 , a front recess 111 , and a rear recess 112 . The rear motor bearing 64 and the front motor bearing 66 are arranged on either side of the magnet holder 100 in the axial direction (front-rear direction).

[0038] The magnet holder main body 110 is cylindrical. The magnet holder main body 110 may be in the shape of a regular polygonal column or the like.

[0039] The front recess 111 is provided at the front end of the magnet holder 100. The front recess 111 is arranged around the inner hole on the front surface of the magnet holder main body 110, and is recessed in a ring shape rearward relative to the radially outer portion. The radially inner edge of the front recess 111 reaches the inner hole (the portion adjacent to the motor shaft 62) of the magnet holder main body 110. The imaginary central axis of the front recess 111 extends in the front-to-rear direction and overlaps with the imaginary central axis of the motor shaft 62. The outer diameter of the front recess 111 is larger than the outer diameter of the front motor bearing 66. The outer ring of the front motor bearing 66 does not contact the magnet holder 100 but contacts the gear case 17. At least a portion of the front motor bearing 66 is housed within the front recess 111. The front motor bearing 66 overlaps with the front recess 111 when viewed from the outside in the circumferential direction. The rear end of the front motor bearing 66 is located rearward of the front end of the front recess 111. This reduces the longitudinal length of the rotor 61 and its peripheral components. As shown in FIG. 4A, the outer ring of the front motor bearing 66 is held by a rearward protrusion 17C formed on the gear case 17. The protrusion 17C is ring-shaped or arc-shaped. At least a portion of the protrusion 17C is within the front recess 111. The protrusion 17C overlaps with the front recess 111 when viewed from the outside in the circumferential direction. The rear end (tip) of the protrusion 17C is located rearward of the front end (opening) of the front recess 111. This reduces the longitudinal length of the rotor 61 and its peripheral components. The inner ring (rear end portion) of the front motor bearing 66 is held by a front step formed on the outer curved surface of the motor shaft 62. The outer diameter of the front portion of the front step on the motor shaft 62 is smaller than the outer diameter of the rear portion of the front step.

[0040] The rear recess 112 is provided at the rear end of the magnet holder 100. The rear recess 112 is arranged around the inner hole on the rear surface of the magnet holder main body 110, and is recessed in a ring shape toward the front relative to the radially outer portion. The radially inner edge of the rear recess 112 reaches the inner hole (the portion adjacent to the motor shaft 62) of the magnet holder main body 110. The imaginary central axis of the rear recess 112 extends in the front-to-rear direction and overlaps with the imaginary central axis of the motor shaft 62. The outer diameter of the rear recess 112 is larger than the outer diameter of the rear motor bearing 64. The outer ring of the rear motor bearing 64 does not contact the magnet holder 100 but contacts the rear cover 14. At least a portion of the rear motor bearing 64 is housed within the rear recess 112. The rear motor bearing 64 overlaps with the rear recess 112 when viewed from the outside in the circumferential direction. The front end of the rear motor bearing 64 is located rearward of the rear end of the front recess 111. This reduces the longitudinal length of the rotor 61 and its peripheral components. As shown in FIG. 4A, the outer ring of the rear motor bearing 64 is held by a forward protrusion 14C formed on the rear cover 14. The protrusion 14C is ring-shaped or arc-shaped. At least a portion of the protrusion 14C is within the rear recess 112. The protrusion 14C overlaps with the rear recess 112 when viewed from the outside in the circumferential direction. The front end (tip) of the protrusion 14C is located forward of the rear end (opening) of the rear recess 112. This reduces the longitudinal length of the rotor 61 and its peripheral components. The inner ring (front end portion) of the rear motor bearing 64 is held by a rear step formed on the outer curved surface of the motor shaft 62. The outer diameter of the front portion of the rear step on the motor shaft 62 is larger than the outer diameter of the rear portion of the rear step.

[0041] At least one of the front recess 111 and the rear recess 112 may be omitted. Furthermore, instead of or in addition to the front and rear stepped portions on the motor shaft 62, the magnet holder 100 may have at least one of a front inner wheel holder 100F and a rear inner wheel holder 100B. In particular, as shown in Fig. 4B as a rotor 61A that is a modified example of the rotor 61, the magnet holder 100 may have both a front inner wheel holder 100F and a rear inner wheel holder 100B. The front inner ring holder 100F is disposed in a front recess 111 on the front surface of the magnet holder main body 110. The front inner ring holder 100F protrudes forward in a ring shape from the rear surface (bottom surface) of the front recess 111. The front inner ring holder 100F holds the inner ring of the front motor bearing 66 by contacting it from the rear side. The front inner ring holder 100F more appropriately holds the front motor bearing 66. The front inner ring holder 100F may also hold the entire inner ring of the front motor bearing 66. The rear inner ring holder 100B is disposed in a rear recess 112 on the rear surface of the magnet holder main body 110. The rear inner ring holder 100B protrudes rearward in a ring shape from the front surface (bottom surface) of the rear recess 112. The rear inner ring holder 100B holds the inner ring of the rear motor bearing 64 by contacting it from the front side. The rear inner ring holder 100B more appropriately holds the rear motor bearing 64. The rear inner ring holder 100B may also hold the entire inner ring of the rear motor bearing 64. The front inner wheel holding portion 100F and the rear inner wheel holding portion 100B may have the same shape as each other, or may have different shapes as each other. When the front inner wheel holding portion 100F and the rear inner wheel holding portion 100B have the same shape as each other, the assembly of the rotor 61 is improved.

[0042] The magnet 102 is ring-shaped. The magnet 102 is a permanent magnet. The magnet 102 exhibits polar anisotropy. The magnet 102 has a total of four poles that alternate in the circumferential direction (north pole, south pole, north pole, south pole). Adjacent poles are different from each other. The magnetic flux between adjacent poles passes through the magnet 102 in an arc shape. Therefore, the magnet holding part 100 does not need to be a material that allows magnetic flux to pass easily, and may be a non-magnetic material. The number of poles of the magnet 102 may be two, or six or more. The magnet holding unit 100 may be a magnetic material. Furthermore, the magnet 102 may exhibit radial anisotropy. If the magnet 102 exhibits radial anisotropy, the magnet 102 can be combined with the magnet holding unit 100 (rotor core) that is a magnetic material in order to properly guide the magnetic flux.

[0043] The magnet 102 is held by the magnet holding portion 100. The magnet 102 is arranged radially outward of the magnet holding portion 100. The imaginary center line of the magnet 102 overlaps with the imaginary center axis of the motor shaft 62. The magnet holding portion 100 holds the magnet 102 in a state where the magnet 102 is exposed to the magnet holding portion 100 in the radial direction. The rotor 61 is an SPM (Surface Permanent Magnet) type. The magnet 102 may be held by being press-fitted into the magnet holder 100 or by being glued to the magnet holder 100. In the case of glueing, one or more adhesive reservoirs for storing adhesive may be provided on the outer surface of the magnet holder 100. The adhesive reservoirs may be ring-shaped or arc-shaped grooves 100G extending in the circumferential direction, as shown in FIG. 4B, for example. The adhesive reservoirs may be provided on the inner surface of the magnet 102 instead of or in addition to the outer surface of the magnet holder 100. In addition to the magnet 102, a sensor magnet may be provided to allow a sensor to detect the rotation state of the rotor 61. In this case, the sensor magnet may be held at the front end of the magnet holder 100.

[0044] The magnet 102 is shorter than the magnet holder 100 in the front-rear direction. The front end of the magnet 102 is positioned rearward of the rear end of the front recess 111. The portion of the magnet holding part 100 forward of the front end of the magnet 102 is exposed from the magnet 102 and forms the first cuttable part C1. The first cuttable part C1 is ring-shaped. The rear end of the magnet 102 is positioned forward of the front end of the rear recess 112. The portion of the magnet holding part 100 rearward of the rear end of the magnet 102 and forward of the fan bushing 104 is exposed from the magnet 102 and forms the second cuttable part C2. The second cuttable part C2 is ring-shaped. A predetermined portion of at least one of the first cuttable portion C1 and the second cuttable portion C2 is cut by applying a blade from the radially outward direction (see arrow C in FIG. 4A), thereby adjusting the rotational balance of the magnet holding portion 100 and the rotor 61. Note that the manner of cutting the first cuttable portion C1 etc. may be changed to one other than that described above, such as applying a blade to the first cuttable portion C1 from the front. If more emphasis is placed on making such balance adjustments more efficient, a material with a greater specific gravity can be selected for magnet holding part 100. Furthermore, if more emphasis is placed on reducing the effects of heat, a material with a thermal expansion coefficient closer to that of magnet 102 can be selected for magnet holding part 100. At least one of the first cuttable portion C1 and the second cuttable portion C2 may be omitted. The magnet holder 100 may have a contact portion that contacts at least one of the front and rear surfaces of the magnet 102 from the axial (front-rear) side. For example, as shown in FIG. 4B , the contact portion is a protrusion 100C that protrudes circumferentially outward from the front portion of the peripheral surface of the rear end of the magnet holder main body 110 in a ring shape. In this case, the protrusion 100C contacts the magnet 102 from the rear, i.e., the rear surface of the magnet 102 contacts the front surface of the protrusion 100C, thereby positioning the magnet 102. The protrusion 100C can be cut from the radially outward side, and the balance of the rotor 61 is adjusted by cutting a predetermined portion of the peripheral surface of the protrusion 100C. The protruding height of the protruding portion 100C may be less than the thickness of the magnet 102, may be the same as the thickness of the magnet 102, or may be greater than the thickness of the magnet 102. The protruding portion 100C and the second cuttable portion C2 may be formed together. The protruding portion 100C may be separate from the other portions. The protruding portion 100C may be provided at the front end of the magnet holder main body 110 instead of or together with the rear end of the magnet holder main body 110.

[0045] An example of the operation of such an impact driver 1 will now be described. When the user holds the grip 6 and presses the button or upper operation unit 36 ​​and forward / reverse switch lever 46 of the battery mounting unit 40 to set the desired impact mode and rotation direction, and then operates the trigger 56, the main switch 44 turns on. The controller 42 then controls and supplies power from the battery 50 to the motor 30 (to at least one of the coils of the stator 60) so that the motor shaft 62 rotates at a speed corresponding to the state of the signal from the switch main body 54. As a result, the motor 30 is driven at a speed corresponding to the amount of operation of the trigger 56. The rotation direction of the motor shaft 62 depends on the state of the forward / reverse switch lever 46.

[0046] Rotation of the motor shaft 62 rotates the fan 31, and air is exhausted to each exhaust port 26, creating an air flow (wind). The wind mainly flows from each of the first air intake ports 24 to each of the exhaust ports 26, and also from each of the second air intake ports 25 to each of the exhaust ports 26. Such wind cools the internal mechanisms of the impact driver 1, including the motor 30.

[0047] Furthermore, the rotational force of the motor shaft 62 is transmitted to the spindle 72 after being reduced in speed by the planetary gear mechanism 70. The rotational force of the spindle 72 is also transmitted to the anvil 34 via the hammer 76. Furthermore, when the anvil 34 receives torque exceeding a predetermined threshold, the spindle 72 guides the hammer 76 to swing back and forth (strike) by an amount corresponding to the impact mode setting. During impact, the spring 74 returns the hammer 76 to its original position after each impact due to its elastic force.

[0048] The first embodiment is not limited to the above and the modified examples, and further modifications such as those described below can be made as appropriate. The speed reduction mechanism from the motor shaft 62 to the anvil 34 in the impact driver 1 may be replaced with a speed reduction mechanism other than the planetary gear speed reduction mechanism. The impact driver 1 may be powered by a commercial power source (AC) by having a power cord instead of the battery mounting portion 40. At least one of the materials of the various cases and housings may be changed to resin, metal, a composite of these, etc. The classification of the housing 3 may be changed from that described above. In addition, at least one of the various members, number of parts, whether or not they are installed, material, arrangement, structure, and type may be changed as appropriate. Furthermore, the first aspect or its modifications may be applied to screwdrivers that do not have a striking mechanism, screwdrivers that are not handheld, other power tools, other power-driven work equipment, etc. For example, the first aspect or its modifications are applied to power tools such as angle drills, hammers, hammer drills, reciprocating saws, or grinders, or gardening tools such as chainsaws, hedge trimmers, blowers, lawn mowers, grass cutters, hedge trimmers, or cleaners, or air compressors for air-powered pneumatic tools. Power-driven equipment for operating work machines that perform work, such as air compressors for pneumatic tools, is included in power-driven work equipment.

[0049] [Second form] 5 is a perspective view of the rotor and fan 31, the rear motor bearing 64, and the front motor bearing 66 according to a second embodiment of the present disclosure, as viewed from the upper right front side. FIG. 6 is a central vertical cross-sectional view of FIG. The second embodiment is similar to the first embodiment except for the rotor. The same members and parts as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof will be omitted as appropriate. The rotor 261 of the second embodiment has a motor shaft 262 and a magnet 102.

[0050] The motor shaft 262 is formed by integrating the magnet holder 100 of the first embodiment with the motor shaft 62. That is, the motor shaft 262 has the magnet holder 200 from the center to the rear in the front-rear direction. The magnet holder 200 is cylindrical. The motor shaft 262 including the magnet holder 200 may be made of a non-magnetic material or a magnetic material. The magnet holder 200 can also be considered to be cylindrical because it is integrated with the motor shaft 262. The magnet holder 200 may also be in the shape of a regular polygonal column, etc. Since the magnet holder 200 is integral with the other parts of the motor shaft 262, it is prevented from slipping or coming off from the other parts.

[0051] The fan 31 is fixed to the rear end of the magnet holding portion 200 via a fan bushing 104 . The magnet holder 200 has a front recess 111 and a rear recess 112. At least a portion of the front motor bearing 66 is housed in the front recess 111. At least a portion of the rear motor bearing 64 is housed in the rear recess 112. This reduces the front-to-rear length of the rotor 261 and its peripheral members.

[0052] The magnet 102 is held by the magnet holder 200 in the same manner as in the first embodiment. The magnet holder 200 has a first cuttable portion C1 and a second cuttable portion C2. The rotational balance of the rotor 261 is adjusted by at least one of the first cuttable portion C1 and the second cuttable portion C2.

[0053] The second embodiment has the same modifications as the first embodiment, as appropriate.

[0054] [Third form] 7 is a perspective view of the rotor and fan 31, the rear motor bearing 64, and the front motor bearing 66 according to a third embodiment of the present disclosure, as viewed from the upper right front side. FIG. 8 is a central vertical cross-sectional view of FIG. The third embodiment is similar to the second embodiment except for the rotor. The same members and parts as those in the second embodiment are denoted by the same reference numerals as those in the second embodiment, and the description thereof will be omitted as appropriate. The rotor 361 of the third embodiment has a motor shaft 362, a magnet holder 301, and a plurality of magnets 302 (eight magnets).

[0055] The motor shaft 362 has a core holding portion 300. The core holding portion 300 is integral with the motor shaft 362. The core holding portion 300 has the same shape as the magnet holding portion 200 of the second embodiment. The magnet holding portion 301 is held by the core holding portion 300. While the magnet holding portion 301 is part of the rotor 61, it is a separate member from the motor shaft 362 before being fixed, and therefore can also be regarded as a magnet holding member. The shape, size, and arrangement of the magnet holding portion 301 are similar to the shape, size, and arrangement of the magnet 102 of the first embodiment. Therefore, the core holding part 300 of the third embodiment also has a front recess 111 and a rear recess 112. At least a portion of the front motor bearing 66 is housed in the front recess 111. At least a portion of the rear motor bearing 64 is housed in the rear recess 112. Therefore, the front-to-rear length of the rotor 361 and its peripheral members is shortened. Furthermore, the core holding portion 300 also has a first cuttable portion C1 and a second cuttable portion C2, so that the rotational balance of the rotor 361 can be adjusted. As in the first embodiment, the core holding part 300 may be separate from the motor shaft 362. That is, in the third embodiment, instead of the motor shaft 362 having the core holding part 300, the motor shaft 62 and the core holding part 300 having a shape similar to that of the magnet holding part 100 in the first embodiment may be employed.

[0056] The magnet holder 301 has a plurality of (eight) magnet holes 301H. Each magnet hole 301H extends in the front-rear direction. Each magnet hole 301H has a shape in which two or more slits are added to a flat plate-shaped portion. The two slits are formed by extending the outer circumferential surface of the flat plate-shaped portion on both sides. The magnet holes 301H are arranged at equal intervals in the circumferential direction, and form part of corresponding sides of a roughly regular octagon. The magnet holder 301 is formed by stacking multiple steel plates (laminated steel plates). Each steel plate extends vertically and horizontally. The stacking direction of each steel plate is the front-to-back direction. Each steel plate has a part of each magnet hole 301H. Each steel plate is joined to the adjacent steel plate by caulking.

[0057] Each magnet 302 is a flat permanent magnet, and the shape of each magnet 302 corresponds to the flat portion of the corresponding magnet hole 301H. Each magnet 302 is inserted into a corresponding magnet hole 301H. The magnet holder 301 holds each magnet 302 in a state where it is not exposed in the radial direction. The core holder 300 holds the magnet 302 indirectly via the magnet holder 301. Each magnet 302 is embedded in the magnet holder 301 in the radial direction. Therefore, the rotor 361 is an IPM (Interior Permanent Magnet) type. In order to properly guide the magnetic flux of each magnet 302, the magnet holder 301 made of a magnetic material can be used. Each slit portion of each magnet hole 301H remains hollow even after each magnet 302 is installed, and serves as a flux barrier 301B that prevents magnetic flux from passing through. At least one of the magnet holder 301 and each magnet 302 may be of a different shape. For example, the magnet holder 301 may be a continuous, integral cylindrical member. At least one of some or all of the magnets 302 and the flat portion of the magnet hole 301H may be curved, bent, barrel-shaped, or other shapes other than flat. Some or all of the flux barriers 301B may be omitted. Some or all of the flux barriers 301B may have other shapes, such as a semi-cylindrical shape, instead of, or in addition to, a slit shape. Some or all of the flux barriers 301B may be positioned in areas other than those adjacent to the radially outer corners of each magnet hole 301H. The number of magnet holders 301 and each magnet 302 may be seven or fewer, or nine or more.

[0058] The third embodiment has the same modifications as the first and second embodiments as appropriate.

[0059] [Fourth form] 9 is a perspective view of the rotor and fan 31, the rear motor bearing 64, and the front motor bearing 66 according to a fourth embodiment of the present disclosure, as viewed from the front upper right. FIG. 10 is a central vertical cross-sectional view of FIG. The fourth embodiment is similar to the third embodiment except for the rotor and the fan bushing. The same members and parts as those in the third embodiment are denoted by the same reference numerals as those in the third embodiment, and the description thereof will be omitted as appropriate. The rotor 461 of the fourth embodiment has the motor shaft 62 of the first embodiment, a magnet holder 301, a plurality of (eight) magnets 302, a front balance correction member 401, and a rear balance correction member 404.

[0060] The magnet holder 301 is held in the center of the motor shaft 62 in the front-to-rear direction. Therefore, in the fourth embodiment, the shape of the magnet holder 301 is such that, compared to the third embodiment, the portion radially inward from each magnet hole 301H extends radially inward. Except for this, the magnet holder 301 of the fourth embodiment is similar to the magnet holder 301 of the third embodiment.

[0061] The front balance correction member 401 is made of metal (brass). The front balance correction member 401 is cylindrical. At least one of the material and the shape of the front balance correction member 401 may be different, similar to the magnet holder 100 of the first embodiment. The front balance correction member 401 is held in the center of the motor shaft 62 in the front-to-rear direction. The front balance correction member 401 is disposed in front of the magnet holder 301. The front balance correction member 401 is disposed radially outward of the motor shaft 62. The imaginary central axis of the front balance correction member 401 overlaps with the imaginary central axis of the motor shaft 62.

[0062] The shape of the front balance correction member 401 corresponds to the portion of the magnet holder 100 in the first embodiment that is forward of the magnet 102. Therefore, the front balance correction member 401 has a front recess 111. Therefore, by disposing at least a portion of the front motor bearing 66 in the front recess 111, the front-to-rear length of the rotor 461 and its peripheral members is shortened. Furthermore, the magnet holding portion 301 and the like are not disposed radially outward of the front balance correction member 401, and the front balance correction member 401 is exposed radially outward. Therefore, the front balance correction member 401 has a first cuttable portion C1. Therefore, the rotational balance of the rotor 461 can be adjusted by cutting the first cuttable portion C1.

[0063] The rear balance correction member 404 is made of metal (brass). The rear balance correction member 404 is cylindrical. At least one of the material and shape of the rear balance correction member 404 may be different, as with the magnet holder 100 of the first embodiment. At least one of the material and shape of the front balance correction member 401 and at least one of the material and shape of the rear balance correction member 404 may be different from each other. The rear balance correction member 404 is held at the rear of the motor shaft 62 in the front-to-rear direction. The rear balance correction member 404 is disposed on the rear side of the magnet holder 301. The rear balance correction member 404 is disposed radially outward of the motor shaft 62. The imaginary central axis of the rear balance correction member 404 overlaps with the imaginary central axis of the motor shaft 62. The fan 31 is fixed to the rear portion of the rear balance correction member 404. In other words, the rear balance correction member 404 also serves as the fan bush 104 of the first embodiment.

[0064] The shape of the rear balance correction member 404 corresponds to the shape of the portion of the magnet holder 100 in the first embodiment that is rearward of the magnet 102 combined with the fan bushing 104. Therefore, the rear balance correction member 404 has a rear recess 112. Therefore, by arranging at least a portion of the rear motor bearing 64 within the rear recess 112, the front-to-rear length of the rotor 461 and its peripheral members is shortened. Furthermore, the magnet holder 301, fan 31, etc. are not disposed radially outward from the front portion of the rear balance correction member 404, and the front portion of the rear balance correction member 404 is exposed radially outward. Therefore, the rear balance correction member 404 has a second cuttable portion C2 in its front portion. Therefore, the rotational balance of the rotor 461 can also be adjusted by cutting the second cuttable portion C2. At least one of the front balance correction member 401 and the rear balance correction member 404 may be omitted by being integrated with the magnet holder 301 or the motor shaft 62, for example.

[0065] The fourth embodiment has the same modifications as any of the first to third embodiments, as appropriate.

[0066] [Fifth form] 11 is a perspective view of the rotor and fan 31, the rear motor bearing 64, and the front motor bearing 66 according to a fifth embodiment of the present disclosure, as viewed from the front upper right. FIG. 12 is a central vertical cross-sectional view of FIG. The fifth embodiment is similar to the fourth embodiment except for the arrangement of the rotor, the fan, and its fixing portion. The same members and parts as those in the fourth embodiment are denoted by the same reference numerals as those in the fourth embodiment, and the description thereof will be omitted as appropriate. The rotor 561 of the fifth embodiment has the motor shaft 62 of the first embodiment, the magnet holder 301 of the fourth embodiment, a plurality of (eight) magnets 302, a front balance correction member 501, and a rear balance correction member 504.

[0067] The shape of the front balancing member 501 is the same as that of the front balancing member 401 of the fourth embodiment, except that a shape corresponding to the fan bush 104 is added to the front outer side in a front-to-back inverted manner. The fan 31 is fixed to the front of the front balancing member 501 in a front-to-back inverted state from that of the first embodiment. The front balancing member 501 also serves the role of the fan bush 104 of the first embodiment. The front balance correction member 501 has a front recess 111. Therefore, by arranging at least a portion of the front motor bearing 66 in the front recess 111, the front-to-rear length of the rotor 561 and its peripheral members is shortened. Furthermore, the magnet holder 301, fan 31, etc. are not disposed radially outward from the rear portion of the front balance correction member 501, and the rear portion of the front balance correction member 501 is exposed radially outward. Therefore, the front balance correction member 501 has a first cuttable portion C1 at its rear portion. Therefore, the rotational balance of the rotor 561 can be adjusted by cutting the first cuttable portion C1.

[0068] The shape of the rear balance correction member 504 is the same as the shape of the rear balance correction member 404 of the fourth embodiment, except that the shape corresponding to the fan bush 104 is removed. The fan 31 is not fixed to the rear balance correction member 504. The rear balance correction member 504 has a rear recess 112. Therefore, by arranging at least a portion of the rear motor bearing 64 in the rear recess 112, the front-to-rear length of the rotor 561 and its peripheral members is shortened. Furthermore, the magnet holding portion 301 and the like are not disposed radially outward of the rear balance correction member 504, and the rear balance correction member 504 is exposed radially outward. Therefore, the rear balance correction member 504 has a second cuttable portion C2. Therefore, the rotational balance of the rotor 561 can also be adjusted by cutting the second cuttable portion C2. The front balance correction member 501 and the rear balance correction member 504 are arranged on both sides in the axial direction (front-rear direction) of the magnet holder 301 of the fourth embodiment, sandwiching it therebetween.

[0069] The fifth embodiment has the same modifications as any of the first to fourth embodiments, as appropriate. [Explanation of symbols]

[0070] 1·· Impact driver (electric power tool), 14·· Cover (housing), 14C, 17C·· Convex portion (portion of housing that holds motor bearing), 17·· Gear case (housing), 31·· Fan, 61, 261, 361, 461, 561·· Rotor, 62·· Motor shaft, 64·· Rear motor bearing, 66·· Front motor bearing, 100·· Magnet holding portion, 100B·· Rear inner ring holding portion, 1 00C··Protrusion (contact portion), 100F··Front inner wheel holding portion, 100G··Groove (adhesive reservoir), 102··Magnet (ring-shaped), 111··Front recess (recess), 112··Rear recess (recess), 200, 301··Magnet holding portion, 300··Core holding portion, 302··Magnet (plate-shaped), 501··Front balance correction member (balance correction member), 504··Rear balance correction member (balance correction member).

Claims

1. a brushless motor having a stator and a rotor; a motor bearing that rotatably supports the rotor; It is equipped with the rotor has a cylindrical or columnar magnet holding portion and a cylindrical magnet, the magnet holding portion has a recess recessed in the axial direction and holds the magnet in a state where the magnet is exposed in the radial direction, the axial length of the magnet is shorter than the axial length of the magnet holder; A portion of the magnet holding portion is exposed, At least a portion of the motor bearing is in the recess; The magnet holding portion has a contact portion that contacts the magnet from the axially outer side. An electric work device characterized by:

2. a brushless motor having a stator and a rotor; a motor bearing that rotatably supports the rotor; It is equipped with the rotor has a cylindrical or columnar magnet holding portion and a cylindrical magnet, the magnet holding portion has a recess recessed in the axial direction and holds the magnet in a state where the magnet is exposed in the radial direction, the axial length of the magnet is shorter than the axial length of the magnet holder; A portion of the magnet holding portion is exposed, At least a portion of the motor bearing is in the recess; the magnet holder has an inner ring holder that holds an inner ring of the motor bearing, two motor bearings are provided on both axial sides of the magnet holding portion, The inner ring holding portion is provided for each of the motor bearings and has a similar shape. An electric work device characterized by:

3. the magnet exhibits polar anisotropy; The magnet holder is made of a non-magnetic material.

3. The electric power tool according to claim 1 or 2.

4. the magnet exhibits radial anisotropy; The magnet holder is made of a magnetic material.

3. The electric power tool according to claim 1 or 2.

5. A part of the radial outer surface of the magnet holding portion is exposed 5. The electric power tool according to claim 1, wherein the electric power tool is a power tool.

6. An adhesive reservoir is provided on at least one of the radially inner surface of the magnet and the radially outer surface of the magnet holding portion.

6. The electric power tool according to claim 1, wherein the electric power tool is a power tool.

7. the rotor has a motor shaft rotatably supported by the motor bearing, The motor shaft is integral with the magnet holder.

7. The electric power tool according to claim 1, wherein the electric power tool is a power tool.

8. the rotor has a motor shaft rotatably supported by the motor bearing, The motor shaft is separate from the magnet holder.

7. The electric power tool according to claim 1, wherein the electric power tool is a power tool.

9. a housing for holding the motor bearing It is equipped with At least a part of the portion of the housing that holds the motor bearing is in the recess.

9. The electric power tool according to claim 1, wherein the electric power tool is a power tool.

10. a brushless motor having a stator and a rotor; a motor bearing that rotatably supports the rotor; It is equipped with the rotor has a cylindrical or columnar core holding portion, a cylindrical magnet holding portion, and a plurality of plate-shaped magnets, the core holding portion has a recess recessed in the axial direction, and holds the magnet holding portion in a state where the magnet holding portion is exposed in the radial direction, the magnet holding portion holds each of the magnets in a state where the magnets are not exposed in the radial direction, the axial length of each of the magnet holding portion and the magnet is shorter than the axial length of the core holding portion, A portion of the core holding portion is exposed, At least a portion of the motor bearing is in the recess. An electric work device characterized by:

11. A part of the radial outer surface of the core holding portion is exposed 11. The electric power tool according to claim 10.

12. An adhesive reservoir is provided on at least one of the radially inner surface of the magnet holding portion and the radially outer surface of the core holding portion.

12. The electric power tool according to claim 10 or 11.

13. The core holding portion has a contact portion that contacts the magnet holding portion from the axially outer side.

13. The electric power tool according to any one of claims 10 to 12.

14. The core holding portion has an inner ring holding portion that holds the inner ring of the motor bearing. The electric power tool according to any one of claims 10 to 13.

15. Two motor bearings are provided on both axial sides of the core holding portion, The inner ring holding portion is provided for each of the motor bearings and has a similar shape.

15. The electric power tool according to claim 14.

16. the rotor has a motor shaft rotatably supported by the motor bearing, The motor shaft is integral with the core holding portion.

16. The electric power tool according to any one of claims 10 to 15.

17. the rotor has a motor shaft rotatably supported by the motor bearing, The motor shaft is separate from the core holding portion.

16. The electric power tool according to any one of claims 10 to 15.

18. a housing for holding the motor bearing It is equipped with At least a part of the portion of the housing that holds the motor bearing is in the recess.

18. The electric power tool according to claim 10, wherein the electric power tool is a power tool.

19. a brushless motor having a stator and a rotor; a motor bearing that rotatably supports the rotor; A fan to create wind, It is equipped with the rotor has a cylindrical balance correction member, the balance correction member has a recess recessed in the axial direction, A portion of the balance correcting member is exposed, At least a portion of the motor bearing is in the recess; The fan is fixed to the balance correction member. An electric work device characterized by:

20. A part of the radial outer surface of the balance correction member is exposed 20. The electric power tool according to claim 19.

21. the rotor has a cylindrical or columnar core holding portion, a cylindrical magnet holding portion, and a plurality of plate-shaped magnets, the core holding portion holds the magnet holding portion in a state where the magnet holding portion is exposed in a radial direction, the magnet holding portion holds each of the magnets in a state where the magnets are not exposed in the radial direction, The balance correction member is provided axially outside the magnet holding portion.

21. The electric power tool according to claim 19 or 20.

22. The balance correction members are provided in pairs on both axial sides of the magnet holding portion.

22. The electric power tool according to claim 21.

23. a housing for holding the motor bearing It is equipped with At least a part of the portion of the housing that holds the motor bearing is in the recess.

23. The electric power tool according to any one of claims 19 to 22.

Images