Electric power tool

Abstract

To reduce the weight and size of a brushless motor used for a power source of an electric work machine.SOLUTION: An electric work machine includes: a brushless motor having a rotor having a rotor core and a permanent magnet fixed to the rotor core, and a stator having a stator core, an insulator fixed to the stator core, and a coil attached to the insulator; a magnetic sensor for detecting magnetic fluxes of the permanent magnet and detecting a position in a rotation direction of the rotor; a controller for controlling the coil energized on the basis of a detection signal of the magnetic sensor; and an output part driven by the rotor. The permanent magnet is a neodymium sinter plate magnet. When the number of poles indicating the number of permanent magnets is represented as N and a stator diameter indicating a diameter of the stator core on a facing surface of the stator core facing the rotor is represented as x (mm), the condition of 0.16x+2.5<N<0.23x+3.6 is satisfied.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The technology disclosed in this specification relates to an electric operating machine. [Background technology]

[0002] 2. Description of the Related Art In the technical field relating to electric working machines, an electric working machine as disclosed in Patent Document 1 is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-093132 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a brushless motor is used as a power source for an electric work machine, it is desired that the brushless motor be made lighter and smaller.

[0005] The technology disclosed in this specification aims to reduce the weight and size of brushless motors used as power sources for electric work machines. [Means for solving the problem]

[0006] This specification discloses an electric working machine. The electric working machine may include a brushless motor having a rotor and a stator, a magnetic sensor, a controller, and an output unit driven by the rotor. The rotor may have a rotor core and a permanent magnet fixed to the rotor core. The stator may have a stator core, an insulator fixed to the stator core, and a coil attached to the insulator. The magnetic sensor may detect the magnetic flux of the permanent magnet to detect the position of the rotor in the rotational direction. The controller may control the coil to be energized based on a detection signal of the magnetic sensor. The permanent magnet may be a neodymium sintered plate magnet. If the number of poles indicating the number of permanent magnets is N and the stator diameter indicating the diameter of the stator core on the opposing surface of the stator core facing the rotor is x [mm], 0.16x+2.5 <N <0.23x+3.6、 The above condition may be satisfied. Effect of the Invention

[0007] According to the technique disclosed in this specification, a brushless motor used as a power source for an electric work machine can be made lighter and smaller. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an electric operating machine according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing the motor according to the embodiment, seen from below. [Diagram 3] FIG. 3 is an exploded perspective view showing the motor according to the embodiment, viewed from below. [Figure 4] FIG. 4 is a perspective view showing the motor according to the embodiment, seen from above. [Diagram 5] FIG. 5 is an exploded perspective view showing the motor according to the embodiment, seen from above. [Figure 6] FIG. 6 is a front view showing the motor according to the embodiment. [Figure 7] FIG. 7 is a vertical cross-sectional view showing the motor according to the embodiment. [Figure 8]FIG. 8 is a cross-sectional view showing the motor according to the embodiment. [Figure 9] FIG. 9 is a view of the rotor and the stator according to the embodiment as viewed from above. [Figure 10] FIG. 10 is a view of the rotor according to the embodiment as viewed from above. [Figure 11] FIG. 11 is a cross-sectional view showing the rotor according to the embodiment. [Figure 12] FIG. 12 is a view of the stator according to the embodiment as viewed from above. [Figure 13] FIG. 13 is a cross-sectional view showing the stator according to the embodiment. [Figure 14] FIG. 14 is a schematic diagram showing an electric operating machine according to an embodiment. [Figure 15] FIG. 15 is a diagram for explaining motors according to an embodiment and a comparative example. [Figure 16] FIG. 16 is a diagram showing the relationship between the stator diameter and the number of poles of the motors according to the example and the comparative example. [Figure 17] FIG. 17 is a diagram for explaining the dimensions of each part of a motor used as a power source for an electric working machine. [Figure 18] FIG. 18 is a diagram showing the relationship between the rotor outer diameter, motor mass, number of poles, and number of slots of the motors according to the example and the comparative example. [Figure 19] FIG. 19 is a diagram showing the relationship between the stator outer diameter, the motor mass, and the rotor outer diameter of the motor according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In one or more embodiments, the electric power tool may include a brushless motor having a rotor and a stator, a magnetic sensor, a controller, and an output unit driven by the rotor. The rotor may have a rotor core and a permanent magnet fixed to the rotor core. The stator may have a stator core, an insulator fixed to the stator core, and a coil attached to the insulator. The magnetic sensor may detect the magnetic flux of the permanent magnet to detect the position of the rotor in the rotational direction. The controller may control the coil to be energized based on the detection signal of the magnetic sensor. The permanent magnet may be a neodymium sintered plate magnet. When the number of poles indicating the number of permanent magnets is N and the stator diameter indicating the diameter of the stator core on the opposing surface of the stator core facing the rotor is x [mm], 0.16x + 2.5 < N < 0.23x + 3.6, may satisfy the condition of.

[0010] In the above configuration, by satisfying the condition of [0.16x + 2.5 < N], the brushless motor is reduced in weight and size. By satisfying the condition of [N < 0.23x + 3.6], a decrease in the detection accuracy of the magnetic sensor 51 is suppressed.

[0011] In one or more embodiments, the electric power tool may include a battery mounting portion. A battery pack that outputs electric power supplied to the coil may be mounted on the battery mounting portion. The brushless motor may be a three-phase motor. When the line resistance between the coils is R [mΩ] and the rated voltage of the battery pack is V [V], R / V 2 ≦ 0.038, may satisfy the condition of.

[0012] In the above configuration, even when electric power is continuously input to the brushless motor, burnout of the coil is suppressed. Therefore, the electric power tool can exhibit the intended performance.

[0013] In one or more embodiments, an electric operating machine may include a brushless motor having a rotor and a stator, and an output section driven by the rotor. The rotor may include a rotor core and a permanent magnet fixed to the rotor core. The stator may include a stator core, an insulator fixed to the stator core, and a coil attached to the insulator. The number of poles, which indicates the number of permanent magnets, may be 28. The number of slots, which indicates the number of coils, may be 24.

[0014] In the above configuration, the number of poles is 28 and the number of slots is 24, so the magnetic flux generated by the coil is dispersed and the permanent magnet is made smaller and thinner, which makes the brushless motor lighter and smaller.

[0015] In one or more embodiments, the brushless motor may be of the outer rotor type.

[0016] The above configuration provides high motor torque.

[0017] In one or more embodiments, the brushless motor is an outer rotor type, and the stator outer diameter may be 105 mm or more and 125 mm or less. The stator outer diameter may be 110 mm or more and 120 mm or less.

[0018] With the above configuration, the brushless motor is made lighter and smaller.

[0019] In one or more embodiments, the stator core may have teeth around which coils are wound via insulators. The teeth width may be 4 mm or more and 8 mm or less.

[0020] With the above configuration, the brushless motor is made lighter and smaller.

[0021] In one or more embodiments, the magnet thickness, which indicates the thickness of the permanent magnet, may be 1.5 mm or more and 3.5 mm or less.

[0022] With the above configuration, the brushless motor is made lighter and smaller.

[0023] In one or more embodiments, the permanent magnets may be fixed to an inner circumferential surface of the rotor core.

[0024] With the above configuration, the brushless motor is made smaller.

[0025] In one or more embodiments, the permanent magnets may be secured to the rotor core with an adhesive.

[0026] In the above configuration, the permanent magnets are fixed to the rotor core with a simple structure.

[0027] In one or more embodiments, the electric power tool may include a rotor shaft fixed to the rotor. The output may be fixed to the rotor shaft.

[0028] In the above configuration, the output section is driven by the motor using a direct drive system.

[0029] Hereinafter, an embodiment according to the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiment. The components of the embodiments described below can be appropriately combined. In addition, some components may not be used.

[0030] In the embodiment, the positional relationship of each part will be described using the terms "left," "right," "front," "rear," "upper," and "lower." These terms indicate relative positions or directions based on the center of the electric operating machine.

[0031] The electric operating machine has a motor. In the embodiments, the radial direction of the rotation axis AX of the motor is appropriately referred to as the radial direction. The direction parallel to the rotation axis AX of the motor is appropriately referred to as the axial direction. The direction going around the rotation axis AX of the motor is appropriately referred to as the circumferential direction or the rotation direction.

[0032] A position closer to the rotation shaft AX of the motor in the radial direction or a direction approaching the rotation shaft AX of the motor in the radial direction is appropriately referred to as the radially inner side. A position farther from the rotation shaft AX of the motor in the radial direction or a direction away from the rotation shaft AX of the motor in the radial direction is appropriately referred to as the radially outer side.

[0033] A position on one side in the axial direction or a direction on one side is appropriately referred to as "one axial side." A position on the other side in the axial direction or a direction on the other side is appropriately referred to as "the other axial side." In the embodiment, the axial direction is the up-down direction. When one axial side is regarded as the upper side, the other axial side is the lower side. When one axial side is regarded as the lower side, the other axial side is the upper side.

[0034] A position or direction on one side in the circumferential direction will be referred to as "one circumferential side" as appropriate, and a position or direction on the other side in the circumferential direction will be referred to as "the other circumferential side" as appropriate.

[0035] [Electric work equipment] 1 is a diagram showing an electric working machine 1 according to an embodiment. In the embodiment, the electric working machine 1 is a lawnmower, which is a type of gardening tool (outdoor power equipment).

[0036] As shown in FIG. 1, the electric work machine 1 includes a housing 2, wheels 3, a motor 4, a cutting blade 5, a cutting box 6, a handle 7, and a battery mounting portion 8.

[0037] The housing 2 accommodates a motor 4 and a cutting blade 5. The wheels 3, the motor 4, and the cutting blade 5 are each supported by the housing 2.

[0038] The wheels 3 rotate while in contact with the ground. The rotation of the wheels 3 enables the electric work machine 1 to move on the ground. Four wheels 3 are provided.

[0039] The motor 4 is a power source for the electric work machine 1. The motor 4 generates a torque that rotates the cutting blade 5. The motor 4 is disposed above the cutting blade 5.

[0040] The cutting blade 5 is connected to the motor 4. The cutting blade 5 is an output part of the electric work machine 1 driven by the motor 4. The cutting blade 5 rotates about the rotation axis AX of the motor 4 by the rotational force generated by the motor 4. The cutting blade 5 faces the ground. With the wheels 3 in contact with the ground, the cutting blade 5 rotates to cut grass growing on the ground. The grass cut by the cutting blade 5 is stored in the cutting box 6.

[0041] The handle 7 is held by the hand of a user of the electric working machine 1. The user can move the electric working machine 1 while holding the handle 7 in his / her hand.

[0042] A battery pack 9 is attached to the battery attachment section 8. The battery pack 9 is a power source for the electric work machine 1. The battery pack 9 is detachable from the battery attachment section 8. The battery pack 9 includes a secondary battery. In this embodiment, the battery pack 9 includes a rechargeable lithium-ion battery. When attached to the battery attachment section 8, the battery pack 9 is capable of supplying power to the electric work machine 1. The battery pack 9 outputs power to be supplied to the motor 4. The motor 4 is driven based on the drive current supplied from the battery pack 9.

[0043] [Motor] FIG. 2 is a perspective view of the motor 4 according to the embodiment, seen from below. FIG. 3 is an exploded perspective view of the motor 4 according to the embodiment, seen from below. FIG. 4 is a perspective view of the motor 4 according to the embodiment, seen from above. FIG. 5 is an exploded perspective view of the motor 4 according to the embodiment, seen from above. FIG. 6 is a front view of the motor 4 according to the embodiment. FIG. 7 is a vertical cross-sectional view of the motor 4 according to the embodiment. FIG. 7 corresponds to the cross-sectional view taken along line AA in FIG. 4. FIG. 8 is a horizontal cross-sectional view of the motor 4 according to the embodiment. FIG. 8 corresponds to the cross-sectional view taken along line BB in FIG. 6. In the embodiment, the motor 4 is an outer rotor type brushless motor.

[0044] As shown in Figures 2, 3, 4, 5, 6, 7, and 8, the motor 4 includes a rotor 10, a rotor shaft 20, a stator 30, a stator base 40, a sensor board 50, and a motor housing 60.

[0045] The rotor 10 rotates relative to the stator 30. At least a portion of the rotor 10 is disposed around the stator 30. The rotor 10 is disposed on the outer circumferential side of the stator 30.

[0046] The rotor shaft 20 is fixed to the rotor 10. The rotor 10 and the rotor shaft 20 rotate about a rotation axis AX. The cutting blade 5 is supported by the rotor shaft 20. The cutting blade 5 is driven by the rotor 10. In the embodiment, the cutting blade 5 is fixed to the rotor shaft 20. The cutting blade 5 is driven by the rotor 10 by a direct drive system.

[0047] In this embodiment, the rotor 10 rotates at a rotation speed of 1000 rpm or more and 4000 rpm or less.

[0048] In this embodiment, the rotation axis AX of the motor 4 extends in the vertical direction. The axial direction and the vertical direction are parallel to each other.

[0049] The rotor 10 has a rotor cup 11, a rotor core 12, and a permanent magnet 13.

[0050] Rotor cup 11 is made of a metal whose main component is aluminum and has a plate portion 11A and a yoke portion 11B.

[0051] The plate portion 11A is substantially annular. The plate portion 11A is disposed around a rotation axis AX. The central axis of the plate portion 11A and the rotation axis AX coincide with each other. An opening 11C is provided in the center of the plate portion 11A. At least a portion of the rotor shaft 20 is disposed inside the opening 11C. In the embodiment, a bush 14 is disposed between an outer surface of the rotor shaft 20 and an inner surface of the opening 11C.

[0052] The yoke portion 11B is substantially cylindrical. A lower end of the yoke portion 11B is connected to the peripheral edge of the plate portion 11A. The plate portion 11A and the yoke portion 11B are integral with each other. The yoke portion 11B is arranged to extend upward from the peripheral edge of the plate portion 11A. The yoke portion 11B is arranged to surround the stator 30. The yoke portion 11B is arranged around the rotation axis AX. The central axis of the yoke portion 11B and the rotation axis AX coincide with each other.

[0053] Rotor core 12 includes a plurality of steel plates stacked in the axial direction. Rotor core 12 is substantially cylindrical. Rotor core 12 is arranged on the outer circumferential side of stator 30. Rotor core 12 is supported by rotor cup 11. At least a portion of rotor cup 11 is arranged around rotor core 12. Rotor core 12 is arranged radially inward of yoke portion 11B. Yoke portion 11B is arranged around rotor core 12. Rotor core 12 is supported by the inner circumferential surface of yoke portion 11B.

[0054] The permanent magnet 13 is plate-shaped. The permanent magnet 13 is a neodymium sintered plate magnet. The permanent magnet 13 is fixed to the rotor core 12. The permanent magnet 13 is arranged radially inward from the rotor core 12. The permanent magnet 13 is fixed to the inner peripheral surface of the rotor core 12. In the embodiment, the permanent magnet 13 is fixed to the inner peripheral surface of the rotor core 12 by an adhesive. A plurality of the permanent magnets 13 are provided at intervals in the circumferential direction. In the embodiment, 28 permanent magnets 13 are provided at intervals in the circumferential direction. The plurality of permanent magnets 13 are provided at equal intervals in the circumferential direction. The N-pole permanent magnets 13 and the S-pole permanent magnets 13 are alternately arranged in the circumferential direction.

[0055] The rotor shaft 20 extends in the axial direction. The rotor shaft 20 is fixed to the rotor 10. A lower portion of the rotor is disposed inside the opening 11C of the plate portion 11A. The rotor shaft 20 is fixed to the plate portion 11A via a bush 14. An upper end portion of the rotor shaft 20 is disposed above an upper surface of the plate portion 11A. A lower end portion of the rotor shaft 20 is disposed below a lower surface of the plate portion 11A.

[0056] The central axis of the rotor shaft 20 coincides with the rotation axis AX. The rotor shaft 20 is fixed to the rotor 10 so that the central axis of the rotor shaft 20 coincides with the central axis of the yoke portion 11B.

[0057] The stator 30 includes a stator core 31 , an insulator 32 , and a coil 33 .

[0058] The stator core 31 includes a plurality of steel plates stacked in the axial direction. The stator core 31 has a yoke 31A and teeth 31B. The yoke 31A is cylindrical. The yoke 31A is arranged around the rotation axis AX. The central axis of the outer peripheral surface of the yoke 31A coincides with the rotation axis AX. The teeth 31B protrude radially outward from the outer peripheral surface of the yoke 31A. A plurality of teeth 31B are provided at intervals in the circumferential direction. In the embodiment, 24 teeth 31B are provided. A slot is formed between adjacent teeth 31B.

[0059] The insulator 32 is made of synthetic resin. The insulator 32 is fixed to the stator core 31. The insulator 32 covers at least a portion of the surface of the stator core 31. The insulator 32 covers at least a portion of the end face of the yoke 31A facing in the axial direction. The end face of the yoke 31A includes an upper end face facing upward and a lower end face facing downward. The insulator 32 also covers at least a portion of the outer surface of the yoke 31A facing radially outward. The insulator 32 also covers at least a portion of the surface of the teeth 31B.

[0060] In the embodiment, the stator core 31 and the insulator 32 are integrally molded. The insulator 32 is fixed to the stator core 31 by insert molding. After heated and molten synthetic resin is injected into a mold containing the stator core 31, the synthetic resin is solidified to form the insulator 32 fixed to the stator core 31.

[0061] The coils 33 are attached to the insulators 32. The coils 33 are wound around each of the multiple teeth 31B via the insulators 32. The attachment surfaces of the teeth 31B around which the coils 33 are wound are covered by the insulators 32. The outer surfaces of the teeth 31B facing radially outward are not covered by the insulators 32. The stator core 31 and the coils 33 are insulated by the insulators 32. A plurality of coils 33 are provided. In this embodiment, 24 coils 33 are arranged in the circumferential direction.

[0062] The stator base 40 supports the stator 30. The stator base 40 supports the stator core 31. The stator base 40 is fixed to the stator core 31. The stator base 40 is made of aluminum. The stator base 40 has a plate portion 41, a peripheral wall portion 42, and a pipe portion 43.

[0063] The plate portion 41 is substantially annular. The plate portion 41 is disposed around the rotation axis AX. The plate portion 41 is disposed above the stator 30.

[0064] The peripheral wall portion 42 is substantially cylindrical. An upper end of the peripheral wall portion 42 is connected to the peripheral edge portion of the plate portion 41. The plate portion 41 and the peripheral wall portion 42 are integral with each other. The peripheral wall portion 42 is disposed so as to extend downward from the peripheral edge portion of the plate portion 41. The peripheral wall portion 42 is disposed so as to surround the yoke portion 11B of the rotor cup 11.

[0065] The pipe portion 43 is substantially cylindrical. The pipe portion 43 protrudes downward from the center of the lower surface of the plate portion 41. The pipe portion 43 is disposed around the rotation axis AX. The central axis of the pipe portion 43 and the rotation axis AX coincide with each other.

[0066] At least a portion of the pipe portion 43 is disposed inside the stator core 31. The central axis of the pipe portion 43 and the central axis of the yoke 31A coincide with each other.

[0067] In the embodiment, the pipe portion 43 includes a small diameter portion 43A and a large diameter portion 43B disposed above the small diameter portion 43A. Each of the small diameter portion 43A and the large diameter portion 43B is cylindrical. The outer diameter of the large diameter portion 43B is larger than the outer diameter of the small diameter portion 43A. The stator core 31 is disposed around the small diameter portion 43A. The small diameter portion 43A is disposed inside the stator core 31. The large diameter portion 43B is disposed outside the stator core 31. The large diameter portion 43B is disposed above the stator core 31. The stator core 31 is fixed to the pipe portion 43. The stator base 40 is fixed to the stator 30 so that the central axis of the pipe portion 43 and the central axis of the yoke 31A coincide with each other.

[0068] The motor 4 has a motor positioning mechanism 70 that positions the stator base 40 and the stator 30. The motor positioning mechanism 70 positions the stator base 40 and the stator core 31.

[0069] In the embodiment, the outer surface of the small diameter portion 43A of the pipe portion 43 includes a base flat surface region 71. The base flat surface regions 71 are provided at least in two locations in the circumferential direction. In the embodiment, one base flat surface region 71 is provided on each of the front and rear sides of the rotation axis AX. The two base flat surface regions 71 are substantially parallel. In addition, the outer surface of the small diameter portion 43A of the pipe portion 43 includes a base curved surface region 72. One base curved surface region 72 is provided on each of the left and right sides of the rotation axis AX.

[0070] The inner surface of the yoke 31A of the stator core 31 includes a stator flat region 73 in contact with the base flat region 71 and a stator curved region 74 in contact with the base curved region 72.

[0071] The motor positioning mechanism 70 includes a base planar region 71 and a stator planar region 73 in contact with the base planar region 71. The motor positioning mechanism 70 also includes a base curved region 72 and a stator curved region 74 in contact with the base curved region 72.

[0072] The stator base 40 and the stator core 31 are positioned in the circumferential direction and the radial direction by the contact between the base flat surface region 71 and the stator flat surface region 73. The stator base 40 and the stator core 31 are positioned in the circumferential direction and the radial direction by the contact between the base curved surface region 72 and the stator curved surface region 74.

[0073] The pipe portion 43 has a base support surface 43C provided at the boundary between the small diameter portion 43A and the large diameter portion 43B. The base support surface 43C faces downward. The base support surface 43C is disposed around the small diameter portion 43A.

[0074] The base support surface 43C contacts the upper end surface of the stator core 31. The base support surface 43C contacts the upper end surface of the yoke 31A of the stator core 31.

[0075] The motor positioning mechanism 70 includes a base support surface 43C. The base support surface 43C provided on the pipe portion 43 comes into contact with the upper end surface of the yoke 31A, whereby the stator base 40 and the stator core 31 are positioned in the axial direction.

[0076] In the embodiment, the stator core 31 and the stator base 40 are fixed by a screw 75. A core screw opening 31C is provided in the yoke 31A of the stator core 31. The core screw opening 31C includes a through hole formed so as to penetrate the upper end surface and the lower end surface of the yoke 31A. A plurality of the core screw openings 31C are provided at intervals around the rotation axis AX. A screw boss 44 is arranged around the pipe portion 43. The screw boss 44 is arranged around the large diameter portion 43B. A base screw hole 44A is provided in the screw boss 44. A plurality of the screw bosses 44 are provided at intervals around the large diameter portion 43B. That is, a plurality of the base screw holes 44A are provided at intervals around the rotation axis AX.

[0077] At least six core screw openings 31C and six base screw holes 44A are provided. In the embodiment, six core screw openings 31C and six base screw holes 44A are provided at equal intervals around the rotation axis AX.

[0078] In the embodiment, the stator core 31 and the stator base 40 are fixed together by six screws 75. The screws 75 are inserted into the core screw openings 31C from below the stator core 31. The tips of the screws 75 inserted into the core screw openings 31C are inserted into the base screw holes 44A of the screw bosses 44. The threads of the screws 75 and the thread grooves of the base screw holes 44A are coupled together, thereby fixing the stator core 31 and the stator base 40 together by the screws 75.

[0079] The motor positioning mechanism 70 includes a screw 75 that is inserted into a base screw hole 44A provided in the stator base 40 through a core screw opening 31C provided in the stator core 31. The screw 75 fixes the stator base 40 and the stator core 31 together.

[0080] Pipe portion 43 supports rotor shaft 20 via bearing 21. Bearing 21 is disposed inside pipe portion 43. An upper portion of rotor shaft 20 is disposed inside pipe portion 43. Bearing 21 rotatably supports an upper portion of rotor shaft 20. Rotor shaft 20 is supported by pipe portion 43 via bearing 21.

[0081] In the embodiment, the stator base 40 has an annular plate portion 45 disposed at an upper end of the pipe portion 43. The upper surface of the bearing 21 is disposed lower than the lower surface of the annular plate portion 45. A wave washer 22 is disposed between the upper surface of the bearing 21 and the lower surface of the annular plate portion 45. The outer circumferential surface of the bearing 21 is supported by the inner surface of the pipe portion 43. The upper surface of the bearing 21 is supported by the annular plate portion 45 via the wave washer 22.

[0082] The sensor substrate 50 supports a magnetic sensor 51 that detects rotation of the rotor 10. The sensor substrate 50 is supported by the stator base 40. The sensor substrate 50 contacts the stator base 40. The sensor substrate 50 is fixed to the stator base 40.

[0083] The magnetic sensor 51 detects the permanent magnets 13 of the rotor 10. The magnetic sensor 51 is supported by a sensor board 50. The magnetic sensor 51 detects the magnetic flux of the permanent magnets 13 to detect the position of the rotor 10 in the rotational direction. That is, the magnetic sensor 51 detects the position of the rotor 10 in the rotational direction by detecting a change in the magnetic field that accompanies the rotation of the rotor 10. The sensor board 50 is supported by the stator base 40 so that the permanent magnets 13 and the magnetic sensor 51 face each other. The sensor board 50 is disposed radially outward of the coils 33.

[0084] The motor housing 60 accommodates the rotor 10 and the stator 30. The motor housing 60 is connected to the stator base 40. The rotor 10 and the stator 30 are disposed in an internal space formed between the motor housing 60 and the stator base 40.

[0085] The motor housing 60 has a plate portion 61 , a peripheral wall portion 62 , and a flange portion 63 .

[0086] The plate portion 61 is substantially annular. The plate portion 61 is disposed below the rotor cup 11. The pipe portion 64 is provided in the center of the plate portion 61. The lower portion of the rotor shaft 20 is disposed inside the pipe portion 64.

[0087] The motor housing 60 supports the bearing 23. The bearing 23 rotatably supports the lower part of the rotor shaft 20. In the embodiment, the motor housing 60 has an annular plate part 65 arranged at the lower end part of the pipe part 64. The lower surface of the bearing 23 is arranged above the upper surface of the annular plate part 65. The outer peripheral surface of the bearing 23 is supported by the inner surface of the pipe part 64. The lower surface of the bearing 23 is supported by the upper surface of the annular plate part 65.

[0088] The peripheral wall portion 62 is substantially cylindrical. A lower end of the peripheral wall portion 62 is connected to the peripheral edge portion of the plate portion 61. The peripheral wall portion 62 protrudes upward from the peripheral edge portion of the plate portion 61. The peripheral wall portion 62 is disposed so as to surround at least a portion of the rotor cup 11.

[0089] The flange portion 63 is connected to the upper end of the peripheral wall portion 62. The flange portion 63 is provided so as to extend radially outward from the upper end of the peripheral wall portion 62. A plurality of through holes 66 are provided in the flange portion 63. In the embodiment, four through holes 66 are provided at intervals in the circumferential direction. A plurality of screw bosses 46 are provided in the peripheral wall portion 42 of the stator base 40. Four screw bosses 46 are provided at intervals in the circumferential direction. Each of the four screw bosses 46 is provided with a screw hole. The stator base 40 and the motor housing 60 are fixed by four screws 67. The screws 67 are inserted into the through holes 66 from below the flange portion 63. The tip of the screw 67 inserted into the through hole 66 is inserted into the screw hole of the screw boss 46. The thread of the screw 67 and the thread groove of the screw hole of the screw boss 46 are coupled to each other, so that the stator base 40 and the motor housing 60 are fixed by the screws 67.

[0090] A plurality of openings 47 are provided in the peripheral wall portion 42 of the stator base 40. A buffer member 48 is disposed in one of the plurality of openings 47. An example of a material for forming the buffer member 48 is rubber. At least a portion of a power line 91, which will be described later, is supported by the buffer member 48 disposed in the opening 47. The buffer member 48 suppresses wear of the power line 91.

[0091] An air passage 68 is provided in a part of the plate portion 61. The air passage 68 includes a flow path with a labyrinth structure. When a cooling fan is fixed to the lower end of the rotor shaft 20, the cooling fan rotates with the rotation of the rotor shaft 20. As the cooling fan rotates, it sucks air in the internal space between the stator base 40 and the motor housing 60 through the air passage 68. As air is sucked through the air passage 68, the air around the motor 4 flows into the internal space through the opening 47. This cools the motor 4.

[0092] At least a part of rotor cup 11 is provided with drainage outlet 15 for draining foreign matter inside rotor cup 11. Two drainage outlets 15 are provided in plate portion 11A. For example, even if water seeps into the inside of rotor cup 11, the water inside rotor cup 11 is drained from drainage outlet 15 to the outside of rotor cup 11.

[0093] As shown in FIG. 2 , the motor housing 60 has a screw boss 600 fixed to the deck 200 of the housing 2. A through hole 201 is provided in the deck 200. A screw hole 601 is provided in the screw boss 600. The deck 200 of the housing 2 and the motor housing 60 are fixed together by a screw 202. The screw 202 is inserted into the through hole 201 from below the deck 200. The tip of the screw 202 inserted into the through hole 201 is inserted into the screw hole 601 of the screw boss 600. The thread of the screw 202 and the thread groove of the screw hole 601 are engaged with each other, thereby fixing the deck 200 of the housing 2 and the motor housing 60 by the screw 202.

[0094] The motor housing 60 also has a screw boss 602 fixed to the baffle 203. The baffle 203 changes the air flow inside the motor housing 60. The baffle 203 is disposed so as to face the lower surface of the motor housing 60. An opening 203A is formed in the center of the baffle 203. The rotor shaft 20 is inserted into the opening 203A. A through hole 204 is provided in the baffle 203. A screw hole 603 is provided in the screw boss 602. The baffle 203 and the motor housing 60 are fixed together by a screw 205. The screw 205 is inserted into the through hole 204 from below the baffle 203. The tip of the screw 205 inserted into the through hole 204 is inserted into the screw hole 603 of the screw boss 602. The thread of the screw 205 and the thread groove of the screw hole 603 are coupled together, thereby fixing the baffle 203 and the motor housing 60 by the screw 205.

[0095] [Rotor and stator] Fig. 9 is a view of the rotor 10 and the stator 30 according to the embodiment, as viewed from above. Fig. 10 is a view of the rotor 10 according to the embodiment, as viewed from above. Fig. 11 is a cross-sectional view of the rotor 10 according to the embodiment. Fig. 12 is a view of the stator 30 according to the embodiment, as viewed from above. Fig. 13 is a cross-sectional view of the stator 30 according to the embodiment.

[0096] The rotor 10 has a rotor cup 11 , a rotor core 12 supported by the rotor cup 11 , and a permanent magnet 13 fixed to the inner circumferential surface of the rotor core 12 .

[0097] The rotor cup 11 has a plate portion 11A and a yoke portion 11B.

[0098] The rotor core 12 has a ring portion 12E and an inner protrusion 12F protruding radially inward from an inner circumferential surface of the ring portion 12E. The inner protrusion 12F is disposed between the permanent magnets 13 adjacent to each other in the circumferential direction.

[0099] Outer protrusions 12G that contact the inner peripheral surface of yoke portion 11B of rotor cup 11 are provided on the outer peripheral surface of ring portion 12E of rotor core 12. A plurality of outer protrusions 12G are provided at intervals in the circumferential direction. Recesses 11F in which the outer protrusions 12G are arranged are provided on the inner peripheral surface of rotor cup 11. Three outer protrusions 12G are arranged in one recess 11F.

[0100] In the multiple (three) outer protrusions 12G arranged in the recess 11F, an adhesive is filled between adjacent outer protrusions 12G. By filling the adhesive, an adhesive layer 19 is disposed between adjacent outer protrusions 12G. The adhesive layer 19 fixes the rotor core 12 and the rotor cup 11 together.

[0101] 13, insulator 32 has outer periphery covering portion 32C and tooth covering portion 32D. Outer periphery covering portion 32C is disposed so as to cover the outer periphery surface of yoke 31A facing radially outward. Tooth covering portion 32D is disposed so as to cover the mounting surface of tooth 31B around which coil 33 is wound.

[0102] The multiple coils 33 are formed by winding a single wire 90. The single wire 90 is wound sequentially around each of the multiple teeth 31B via the tooth covering portion 32D. The first coil 33 and the second coil 33 wound next to the first coil 33 are connected by the wire 90.

[0103] The power output from the battery pack 9 is supplied to the coil 33. A driving current is supplied to the coil 33. The driving current from the battery pack 9 is supplied to the coil 33 via a power supply line 91 and a fusing terminal 92. The driving current supplied to the coil 33 flows through the power supply line 91 and the fusing terminal 92.

[0104] The power supply line 91 and the fusing terminal 92 are each supported by the insulator 32. The power supply line 91 and the fusing terminal 92 are each disposed above the upper end surface of the stator core 31.

[0105] The motor 4 is a three-phase motor. Each of the 24 coils 33 is assigned to one of the U (UV) phase, V (VW) phase, and W (WU) phase. The power supply lines 91 include a power supply line 91U through which a U-phase driving current flows, a power supply line 91V through which a V-phase driving current flows, and a power supply line 91W through which a W-phase driving current flows.

[0106] The fusing terminals 92 connect the multiple wires 90 protruding from each of the multiple coils 33. The fusing terminals 92 include a fusing terminal 92U through which a U-phase driving current flows, a fusing terminal 92V through which a V-phase driving current flows, and a fusing terminal 92W through which a W-phase driving current flows.

[0107] The power supply line 91U is connected to a fusing terminal 92U. The power supply line 91V is connected to a fusing terminal 92V. The power supply line 91W is connected to a fusing terminal 92W.

[0108] [controller] FIG. 14 is a schematic diagram showing an electric operating machine 1 according to an embodiment. As described above, in the embodiment, 24 coils 33 are provided. In FIG. 14, the 24 coils 33 are numbered C1 to C24. The 24 coils 33 are formed by winding one wire 90. As shown in FIG. 14, the winding of the wire 90 starts from a winding start portion S. The wire 90 is wound sequentially around each of the multiple teeth 31B so that the multiple coils 33 are formed sequentially. After the 24 coils 33 are formed, the winding of the wire 90 ends at a winding end portion E.

[0109] The coils 33 are delta-connected. The coils C1, C2, C8, C7, C13, C14, C20, and C19 are assigned to the U (UV) phase. The coils C9, C10, C16, C15, C21, C22, C4, and C3 are assigned to the V (VW) phase. The coils C5, C6, C12, C11, C17, C18, C24, and C23 are assigned to the W (WU) phase.

[0110] The coils C1, C2, C8, and C7 are connected in series, and the coils C13, C14, C20, and C19 are connected in series. In addition, the coils C1, C2, C8, and C7 are connected in parallel with the coils C13, C14, C20, and C19.

[0111] The coils C9, C10, C16, and C15 are connected in series, and the coils C21, C22, C4, and C3 are connected in series. In addition, the coils C9, C10, C16, and C15 are connected in parallel with the coils C21, C22, C4, and C3.

[0112] The coils C5, C6, C12, and C11 are connected in series, and the coils C17, C18, C24, and C23 are connected in series. In addition, the coils C5, C6, C12, and C11 and the coils C17, C18, C24, and C23 are connected in parallel.

[0113] That is, in this embodiment, the 24 coils 33 are delta-connected with 2 in parallel and 4 in series.

[0114] The electric operating machine 1 includes a controller 100 , a gate circuit 101 , an inverter 102 , and a current detection circuit 103 .

[0115] The controller 100 includes a circuit board on which a plurality of electronic components are mounted. Examples of the electronic components mounted on the circuit board include a processor such as a CPU (Central Processing Unit), a non-volatile memory such as a ROM (Read Only Memory) or storage, and a volatile memory such as a RAM (Random Access Memory).

[0116] The inverter 102 supplies a driving current to the coil 33 based on the power supplied from the battery pack 9. The inverter 102 has six switching elements QHu, QHv, QHw, QLu, QLv, and QLw. Each of the switching elements QHu, QHv, QHw, QLu, QLv, and QLw includes a field effect transistor (FET).

[0117] The switching element QHu is disposed between the fusing terminal 92U and a power supply line connected to the positive electrode of the battery pack 9. The switching element QHv is disposed between the fusing terminal 92V and a power supply line connected to the positive electrode of the battery pack 9. The switching element QHw is disposed between the fusing terminal 92W and a power supply line connected to the positive electrode of the battery pack 9. When the switching element QHu is turned on, the fusing terminal 92U and the power supply line are electrically connected. When the switching element QHv is turned on, the fusing terminal 92V and the power supply line are electrically connected. When the switching element QHw is turned on, the fusing terminal 92W and the power supply line are electrically connected.

[0118] The switching element QLu is disposed between the fusing terminal 92U and a ground line connected to the negative electrode of the battery pack 9. The switching element QLv is disposed between the fusing terminal 92V and a ground line connected to the negative electrode of the battery pack 9. The switching element QLw is disposed between the fusing terminal 92W and a ground line connected to the negative electrode of the battery pack 9. When the switching element QLu is turned on, the fusing terminal 92U and the ground line are electrically connected. When the switching element QHv is turned on, the fusing terminal 92V and the ground line are electrically connected. When the switching element QHw is turned on, the fusing terminal 92W and the ground line are electrically connected.

[0119] The gate circuit 101 is a drive circuit that drives the switching elements QHu, QHv, QHw, QLu, QLv, and QLw. The controller 100 outputs a control signal to the gate circuit 101 to drive the switching elements QHu, QHv, QHw, QLu, QLv, and QLw of the inverter 102.

[0120] The current detection circuit 103 is disposed in a current path from the inverter 102 to the negative electrode of the battery pack 9. The current detection circuit 103 outputs a voltage signal corresponding to a current flowing through the current path. The controller 100 can detect the drive current flowing through the coil 33 based on the output signal of the current detection circuit 103.

[0121] Three magnetic sensors 51 are provided. The magnetic sensors 51 include a magnetic sensor 51U corresponding to the U (UV) phase, a magnetic sensor 51V corresponding to the V (VW) phase, and a magnetic sensor 51W corresponding to the W (WU) phase. The detection signals output from the magnetic sensors 51U, 51V, and 51W are switched between a high level detection signal and a low level detection signal every 180° in electrical angle based on a change in the magnetic field received from the rotating rotor 10. The detection signals output from the magnetic sensors 51 are input to the controller 100.

[0122] The controller 100 controls the power supplied to the coil 33 based on the detection signal of the magnetic sensor 51. The controller 100 controls the gate circuit 101 based on the detection signals of the magnetic sensors 51U, 51V, and 51W, to drive the switching elements QHu, QHv, QHw, QLu, QLv, and QLw of the inverter 102. By controlling the switching elements QHu, QHv, QHw, QLu, QLv, and QLw of the inverter 102, the drive currents supplied to the U (UV)-phase coil 33, the V (VW)-phase coil 33, and the W (WU)-phase coil are controlled.

[0123] In the first drive pattern in which the switching elements QHv and QLu are turned on, a drive current flows from the fusing terminal 92V to the fusing terminal 92U in each of the multiple coils 33 assigned to the UV phases.

[0124] In the second drive pattern in which the switching elements QHw and QLu are turned on, a drive current flows from the fusing terminal 92W to the fusing terminal 92U in each of the multiple coils 33 assigned to the WU phase.

[0125] In the third drive pattern in which the switching elements QHw and QLv are turned on, a drive current flows from the fusing terminal 92W to the fusing terminal 92V through each of the multiple coils 33 assigned to the VW phase.

[0126] In the fourth drive pattern in which the switching elements QHu and QLv are turned on, a drive current flows from the fusing terminal 92U to the fusing terminal 92V in each of the multiple coils 33 assigned to the UV phases.

[0127] In the fifth drive pattern in which the switching elements QHu and QLw are turned on, a drive current flows from the fusing terminal 92U to the fusing terminal 92W in each of the multiple coils 33 assigned to the WU phase.

[0128] In the sixth drive pattern in which the switching elements QHv and QLw are turned on, a drive current flows from the fusing terminal 92V to the fusing terminal 92W in each of the coils 33 assigned to the VW phase.

[0129] By sequentially supplying drive current to each of the multiple coils 33 assigned to the UV phase, the multiple coils 33 assigned to the VW phase, and the multiple coils 33 assigned to the WU phase, a rotating magnetic field is generated in the motor 4, and the rotor 10 rotates.

[0130] [Number of poles and slots] As described above, in the embodiment, the motor 4 has 28 permanent magnets 13 and 24 coils 33. That is, the number of poles indicating the number of permanent magnets 13 is 28. The number of slots indicating the number of coils 33 is 24. With 28 poles and 24 slots, the motor 4 used as the power source of the electric work machine 1 can be made lighter and smaller.

[0131] Fig. 15 is a diagram for explaining motors according to examples and comparative examples. Fig. 15 shows the stator outer diameter, the number of poles, the number of slots, the rotor type indicating the outer rotor type or the inner rotor type, and the stator inner diameter of the motors according to example K and comparative examples M1 to M9.

[0132] In the outer rotor type, the stator outer diameter refers to the diameter of the stator core at the facing surface of the stator core that faces the rotor. In the outer rotor type, the facing surface of the stator core refers to the outer end surfaces of the teeth that face radially outward. In other words, in the outer rotor type, the stator outer diameter refers to the maximum value of the dimension of the stator core in the radial direction.

[0133] In the inner rotor type, the stator inner diameter refers to the diameter of the stator core at the facing surface of the stator core that faces the rotor. In the inner rotor type, the facing surface of the stator core refers to the inner end surfaces of the teeth that face radially inward. In other words, in the inner rotor type, the stator inner diameter refers to the minimum dimension of the stator core in the radial direction.

[0134] In the following description, the outer diameter of the stator in the outer rotor type and the inner diameter of the stator in the inner rotor type are collectively referred to as the stator diameter, where appropriate. The stator diameter refers to the diameter of the stator core on the surface facing the rotor.

[0135] The motor 4 according to Example K is a 28-pole, 24-slot outer rotor type with 28 poles and 24 slots. The outer diameter of the stator is 117.3 mm.

[0136] The motor according to the comparative example M1 is a 20-pole, 18-slot outer rotor type with 20 poles and 18 slots. The outer diameter of the stator is 117.3 mm.

[0137] The motor according to the comparative example M2 is a 4-pole, 6-slot inner rotor type, with the number of poles being 4 and the number of slots being 6. The stator outer diameter is 44 [mm], and the stator inner diameter is 21 [mm].

[0138] The motor according to the comparative example M3 is a 4-pole, 6-slot inner rotor type, with the number of poles being 4 and the number of slots being 6. The stator outer diameter is 52 [mm], and the stator inner diameter is 27 [mm].

[0139] The motor according to the comparative example M4 is an 8-pole, 12-slot inner rotor type with 8 poles and 12 slots. The stator outer diameter is 80 [mm], and the stator inner diameter is 53 [mm].

[0140] The motor according to the comparative example M5 is an 8-pole, 12-slot inner rotor type with 8 poles and 12 slots. The stator outer diameter is 122 mm, and the stator inner diameter is 69 mm.

[0141] The motor according to the comparative example M6 is an 8-pole, 12-slot inner rotor type with 8 poles and 12 slots. The stator outer diameter is 99 [mm], and the stator inner diameter is 53.5 [mm].

[0142] The motor according to the comparative example M7 is an 8-pole, 12-slot inner rotor type with 8 poles and 12 slots. The stator outer diameter is 99 [mm], and the stator inner diameter is 52 [mm].

[0143] The motor according to the comparative example M8 is a 6-pole, 9-slot outer rotor type with 6 poles and 9 slots. The outer diameter of the stator is 51 mm.

[0144] The motor according to the comparative example M9 is a 10-pole, 12-slot outer rotor type with 10 poles and 12 slots. The outer diameter of the stator is 113 mm.

[0145] Fig. 16 is a diagram showing the relationship between the stator diameter and the number of poles of the motors according to the examples and the comparative examples. That is, Fig. 16 is a graph plotting the number of poles N and the stator diameter x of the example K and the comparative examples M1 to M9 shown in Fig. 15. In Fig. 16, the horizontal axis is the stator diameter x, and the vertical axis is the number of poles N. As described above, the stator diameter x of the outer rotor type indicates the outer diameter of the stator, and the stator diameter x of the inner rotor type indicates the inner diameter of the stator.

[0146] The motor according to Example K satisfies the condition of the following formula (1). The motors according to Comparative Examples M1 to M9 do not satisfy the condition of the following formula (1).

[0147] 0.16x+2.5 <N < 0.23x+3.6 …(1)

[0148] In FIG. 16, line L1 indicates the lower threshold value [N = 0.16x + 2.5], and line L2 indicates the upper threshold value [N = 0.23x + 3.6].

[0149] The line L1 indicating the lower threshold value is a line indicating the allowable value of the motor mass. The motor mass refers to the sum of the mass of the rotor core, the mass of the permanent magnet, the mass of the stator core, and the mass of the coil. As a result of measuring the respective motor masses of Example K and Comparative Examples M1 to M9, the motor mass of Example K is smaller than the motor masses of Comparative Examples M1 to M9. That is, the more the number of poles and slots, the more the motor is lightweight or miniaturized. For example, when Example K and Comparative Example M1 are compared, the motor mass of Example K with a larger number of slots is smaller than the motor mass of Comparative Example M1. This is considered to be because when generating a specified motor torque, the more the number of coils, the smaller one coil can be made. Also, when Example K is compared with Comparative Examples M2 to M9, the motor mass of Example K with a larger number of poles and slots is smaller than the motor masses of Comparative Examples M2 to M9. This is considered to be because when generating a specified motor torque, the more the number of coils, the smaller one coil can be made, and the more the number of permanent magnets, the smaller and thinner one permanent magnet can be made. Therefore, for the purpose of lightweighting or miniaturizing the motor, it is preferable for the motor to satisfy the condition of [0.16x + 2.5 < N], which is in the range above line L1.

[0150] The line L2 indicating the upper threshold value is a line indicating the allowable value of the detection accuracy of the magnetic sensor 51. Specifically, the line L2 is a line where the detection accuracy of the rotor 10 by the magnetic sensor 51 has an error of ±7.5 degrees of electrical angle. As described above, the switching elements QHu, QHv, QHw, QLu, QLv, and QLw of the inverter 102 are switched on and off in the first to sixth drive patterns. That is, the switching elements QHu, QHv, QHw, QLu, QLv, and QLw of the inverter 102 are switched at intervals of 60 degrees of electrical angle. If the number of poles is too large, it may be difficult for the magnetic sensor 51 to detect the magnetic flux of the permanent magnet with high accuracy. For example, if an error of ±7.5 degrees or more of electrical angle occurs in the detection accuracy, the controllability of the motor 4 is reduced. Therefore, in order to reduce the detection accuracy of the magnetic sensor 51, it is preferable that the motor satisfies the condition [N < 0.23x + 3.6], which is in the range below the line L2.

[0151] Fig. 17 is a diagram for explaining the dimensions of each part of a motor used as a power source for an electric work machine 1. Fig. 17 shows each part of an outer rotor type motor. In an outer rotor type motor, the rotor outer diameter A, teeth width B, teeth tip thickness C, magnet thickness D, yoke thickness E, opening width F, and distance G between magnets are specified.

[0152] Rotor outer diameter A refers to the outer diameter of rotor core 12. Teeth width refers to the circumferential dimension of teeth 31B. Teeth tip thickness C refers to the radial dimension of the protruding portion provided at the radially outer tip of teeth 31B. Magnet thickness D refers to the thickness of permanent magnet 13 indicating the radial dimension of permanent magnet 13. Yoke thickness E refers to the thickness of ring portion 12E indicating the radial dimension of ring portion 12E of rotor core 12. Opening width F refers to the distance between the protruding portions of two teeth 31B adjacent to each other in the circumferential direction. Magnet distance G refers to the distance between two permanent magnets 13 adjacent to each other in the circumferential direction.

[0153] In the motor 4 used as the power source of the electric working machine 1, the dimensions of the above-mentioned components are set approximately within the following ranges.

[0154] Rotor outer diameter A: 100mm or more and 150mm or less. Teeth width B: 3mm or more and 12mm or less. Teeth tip thickness C: 2mm or more and 4mm or less. ·Magnet thickness D: 1 [mm] or more and 4 [mm] or less. - Yoke thickness E: 1.5mm or more, 6.0mm or less. ·Opening width F: 2.5 [mm] or more and 5.0 [mm] or less. ·Distance between magnets G: 0.5 [mm] or more and 5.0 [mm] or less.

[0155] FIG. 18 is a diagram showing the relationship between the rotor outer diameter, motor mass, number of poles, and number of slots of the motors according to the examples and comparative examples. All of the motors according to the examples and comparative examples in FIG. 18 are outer rotor types. The motor according to the examples is 28 poles and 24 slots (28P24S). The motor according to the first comparative example is 26 poles and 24 slots (26P24S). The motor according to the second comparative example is 24 poles and 18 slots (24P18S). The motor according to the third comparative example is 22 poles and 24 slots (22P24S). The motor according to the fourth comparative example is 20 poles and 18 slots (20P18S). The motor according to the fifth comparative example is 16 poles and 18 slots (16P18S).

[0156] For each of the motors according to the embodiment and the first to fifth comparative examples, the dimensions of each of the above-mentioned parts (rotor outer diameter A, teeth width B, teeth tip thickness C, magnet thickness D, yoke thickness E, opening width F, and distance between magnets G) were changed within the above-mentioned ranges under the constraint conditions that allowed a specified motor torque to be obtained, and the motor mass for each dimension was calculated. Fig. 18 is a graph plotting the calculation results of the motor mass. In Fig. 18, the horizontal axis is rotor outer diameter A, and the vertical axis is motor mass.

[0157] As shown in Fig. 18, it was found that when a specified motor torque is generated, the motor mass according to the embodiment is smaller than the motor mass according to the first to sixth comparative examples. That is, it was found that when a specified motor torque is generated in an outer rotor type motor, the motor is made lighter by using 28 poles and 24 slots. Also, as shown in Fig. 18, it was found that in a 28 pole, 24 slot motor, in order to reduce the motor mass, it is preferable to set the rotor outer diameter A to 105 mm or more and 125 mm or less, and more preferably to set it to 100 mm or more and 120 mm or less.

[0158] It was also found that in a 28-pole, 24-slot motor, in order to reduce the motor mass, it is preferable to set the teeth width B to 4 mm or more and 8 mm or less.

[0159] It was also found that in a 28-pole, 24-slot motor, in order to reduce the motor mass, it is preferable to set the magnet thickness D to 1.5 mm or more and 3.5 mm or less.

[0160] Fig. 19 is a diagram showing the relationship between the stator outer diameter, motor mass, and rotor outer diameter of motor 4 according to an embodiment. All of the motors according to the embodiment in Fig. 19 are of the outer rotor type with 28 poles and 24 slots. Under the constraint conditions under which a specified motor torque is obtained, the dimensions of each of the above-mentioned parts (rotor outer diameter A, teeth width B, teeth tip thickness C, magnet thickness D, yoke thickness E, opening width F, distance between magnets G) were changed within the above-mentioned ranges, and the stator outer diameter was also changed, and the motor mass for each dimension was calculated.

[0161] As shown in FIG. 19, when the rotor outer diameter A is changed to 120 [mm], 125 [mm], 130 [mm], 135 [mm], and 140 [mm], the larger the rotor outer diameter A, the larger the stator outer diameter becomes, and the smaller the rotor outer diameter A, the smaller the stator outer diameter becomes.

[0162] In addition, in a 28-pole, 24-slot outer rotor motor, when the line resistance of the coil 33 is R [mΩ] and the rated voltage of the battery pack 9 is V [V], it is preferable to satisfy the condition of the following formula (2).

[0163] R / V 2 ≦ 0.038 …(2)

[0164] The line resistance R refers to the resistance between the U and V phases, the resistance between the V and W phases, and the line resistance between the W and U phases in the three-phase motor 4. In the embodiment, the line resistance R between the U and V phases, the line resistance R between the V and W phases, and the line resistance R between the W and U phases have the same value.

[0165] As shown in FIG. 1, when the electric work machine 1 is a lawnmower, it is necessary to continuously input at least 720 [W] of power to the motor 4 in order to perform the required work. It has been empirically found that when 720 [W] (36V 20A) of power is continuously input to the coil 33 of the motor 4, the line resistance R of the motor 4 at which the coil 33 does not burn out is 49 [mΩ] or less. As described above, the battery pack 9 includes a lithium-ion battery. The current that one cell of a lithium-ion battery can continuously discharge is about 15 [A] to 20 [A]. In addition, even in electric work machines other than lawnmowers, whether or not 720 [W] of power can be continuously input is an important indicator. Lithium-ion batteries come in various voltage ranges, and when the same 720 [W] is input to the motor 4, there are various forms such as 18V 40A, 36V 20A, and 72V 10A. Since the resistance value is proportional to the square of the voltage, [R / V 2 By defining the value represented by the formula: [0.038 [mΩ / V], the line resistance R of the motor 4 that will not burn out when 720 [W] is input, regardless of the voltage, can be standardized. 2 ] was the goal for the optimal design of Motor 4, and it was found that 28 poles and 24 slots were the best.

[0166] [effect] As described above, in the embodiment, the electric working machine 1 includes a motor 4 which is a brushless motor having a rotor 10 and a stator 30, a magnetic sensor 51, a controller 100, and a cutting blade 5 which is an output unit driven by the rotor 10. The rotor 10 has a rotor core 12 and a permanent magnet 13 fixed to the rotor core 12. The stator 30 has a stator core 31, an insulator 32 fixed to the stator core 31, and a coil 33 attached to the insulator 32. The magnetic sensor 51 detects the magnetic flux of the permanent magnet 13 to detect the position of the rotor 10 in the rotational direction. The controller 100 controls the coil 33 to be energized based on the detection signal of the magnetic sensor 51. The permanent magnet 13 is a neodymium sintered plate magnet. When the number of poles indicating the number of the permanent magnets 13 is N and the stator diameter indicating the diameter of the stator core on the opposing surface of the stator core 31 opposing the rotor 10 is x [mm], 0.16x + 2.5 < N < 0.23x + 3.6, satisfies the condition.

[0167] In the above configuration, by satisfying the condition of [0.16x + 2.5 < N], the motor 4 is reduced in weight and size. By satisfying the condition of [N < 0.23x + 3.6], a decrease in the detection accuracy of the magnetic sensor 51 is suppressed.

[0168] In the embodiment, the electric working machine 1 includes a battery mounting portion 8. A battery pack 9 that outputs electric power supplied to the coil 33 is mounted on the battery mounting portion 8. The motor 4 is a three-phase motor. When the line resistance of the coil 33 is R [mΩ] and the rated voltage of the battery pack 9 is V [V], R / V 2 ≤ 0.038, satisfies the condition.

[0169] In the above configuration, even when electric power is continuously input to the motor 4, burnout of the coil 33 is suppressed. Therefore, the electric working machine 1 can exhibit the intended performance.

[0170] In the embodiment, the electric work machine 1 includes a motor 4 which is a brushless motor having a rotor 10 and a stator 30, and a cutting blade 5 which is an output part driven by the rotor 10. The rotor 10 includes a rotor core 12 and a permanent magnet 13 fixed to the rotor core 12. The stator 30 includes a stator core 31, an insulator 32 fixed to the stator core 31, and a coil 33 attached to the insulator 32. The number of poles indicating the number of permanent magnets 13 is 28. The number of slots indicating the number of coils 33 is 24.

[0171] In the above configuration, the number of poles is 28 and the number of slots is 24, so that the magnetic flux generated by the coil 33 is dispersed, and the permanent magnet 13 is made smaller and thinner. This allows the motor 4 to be made lighter and smaller.

[0172] In the embodiment, the motor 4 is of an outer rotor type.

[0173] The above configuration provides high motor torque.

[0174] In this embodiment, the motor 4 is an outer rotor type, and the rotor outer diameter A is 105 mm or more and 125 mm or less. Preferably, the rotor outer diameter A is 110 mm or more and 120 mm or less.

[0175] In the above configuration, the motor 4 is made lighter and smaller.

[0176] In the embodiment, the stator core 31 has teeth 31B around which coils 33 are wound via insulators 32. The teeth width B is equal to or greater than 4 mm and equal to or less than 8 mm.

[0177] In the above configuration, the motor 4 is made lighter and smaller.

[0178] In the embodiment, the magnet thickness D indicating the thickness of the permanent magnet 13 is not less than 1.5 [mm] and not more than 3.5 [mm].

[0179] In the above configuration, the motor 4 is made lighter and smaller.

[0180] In the embodiment, the permanent magnets 13 are fixed to the inner circumferential surface of the rotor core 12 .

[0181] In the above configuration, the motor 4 is made smaller.

[0182] In the embodiment, the permanent magnets 13 are fixed to the rotor core 12 by an adhesive.

[0183] In the above configuration, permanent magnets 13 are fixed to rotor core 12 with a simple structure.

[0184] In the embodiment, the electric work machine 1 includes a rotor shaft 20 fixed to the rotor 10. The cutting blade 5, which is an output portion, is fixed to the rotor shaft 20.

[0185] In the above configuration, the cutting blade 5, which is the output portion, is driven by the motor 4 by a direct drive system.

[0186] [Other embodiments] In the above embodiment, the motor 4 is an outer rotor type. The motor 4 may be an inner rotor type.

[0187] In the above embodiment, the electric working machine 1 is a lawnmower, which is a type of gardening tool. The gardening tool is not limited to a lawnmower. Examples of gardening tools include a hedge trimmer, a chainsaw, a grass cutter, and a blower. The electric working machine 1 may also be an electric tool. Examples of electric tools include a driver drill, a vibration driver drill, an angle drill, an impact driver, a grinder, a hammer, a hammer drill, a circular saw, and a reciprocating saw.

[0188] In the above-described embodiment, the battery pack attached to the battery attachment portion is used as the power source for the electric operating machine. A commercial power source (AC power source) may also be used as the power source for the electric operating machine. [Explanation of symbols]

[0189] 1...electrical work machine, 2...housing, 3...wheel, 4...motor, 5...cutting blade, 6...cutting box, 7...handle, 8...battery mounting section, 9...battery pack, 10...rotor, 11...rotor cup, 11A...plate section, 11B...yoke section, 11C...opening, 11F...recess, 12...rotor core, 12E...ring section, 12F...inner convex section, 12G...outer convex section, 13...permanent magnet, 14...bush, 15...discharge port, 19...adhesive layer, 20...rotor shaft, 21...bearing, 22...wave Washer, 23... bearing, 30... stator, 31... stator core, 31A... yoke, 31B... teeth, 31C... core screw opening, 32... insulator, 32C... outer periphery coating portion, 32D... teeth coating portion, 33... coil, 40... stator base, 41... plate portion, 42... peripheral wall portion, 43... pipe portion, 43A... small diameter portion, 43B... large diameter portion, 43C... base support surface, 44... screw boss, 44A... base screw hole, 45... annular plate portion, 46... screw boss, 47... opening, 48... cushioning member , 50...sensor board, 51...magnetic sensor, 51U...magnetic sensor, 51V...magnetic sensor, 51W...magnetic sensor, 60...motor housing, 61...plate portion, 62...circumferential wall portion, 63...flange portion, 64...pipe portion, 65...annular plate portion, 66...through hole, 67...screw, 68...air passage, 70...motor positioning mechanism, 71...base flat area, 72...base curved area, 73...stator flat area, 74...stator curved area, 75...screw, 90...wire, 91...power line, 91U...power supply line, 91V...power line, 91W...power line, 92...fusing terminal, 92U...fusing terminal, 92V...fusing terminal, 92W...fusing terminal, 100...controller, 101...gate circuit, 102...inverter, 103...current detection circuit, 200...deck, 201...through hole, 202...screw, 203...baffle, 203A...opening, 204...through hole, 205...screw, 600...screw boss, 601...screw hole, 602...screw boss, 603...screw hole, AX...rotating shaft.

Claims

1. a rotor having a rotor core and a permanent magnet fixed to the rotor core, a stator having a stator core, an insulator fixed to the stator core, and a coil attached to the insulator, the stator being an outer rotor type brushless motor; a magnetic sensor that detects the magnetic flux of the permanent magnet to detect the position of the rotor in the rotational direction; a controller that controls the coil to be energized based on a detection signal from the magnetic sensor; an output section driven by the rotor, The permanent magnet is a neodymium sintered plate magnet, When the number of poles, which indicates the number of the permanent magnets, is N, and the stator diameter, which indicates the diameter of the stator core on the opposing surface of the stator core that faces the rotor, is x [mm], The motor mass, which is the sum of the mass of the rotor core, the mass of the permanent magnets, the mass of the stator core, and the mass of the coils, is smaller than a permissible value, and the detection accuracy of the rotor by the magnetic sensor is within an error of an electrical angle of ±7.5 degrees. 0.16x+2.5 <N <0.23x+3.6, Satisfy the condition of Electric work equipment.

2. A battery mounting section is provided, a battery pack that outputs power to be supplied to the coil is attached to the battery attachment section; the brushless motor is a three-phase motor, When a power of at least 720 [W] is continuously input to the coil, the line resistance of the coil is R [mΩ] of 49 [mΩ] or less, and the rated voltage of the battery pack is V [V], R / V ２ ≦ 0.038、 Satisfy the condition of The electric operating machine according to claim 1 .

3. The number of poles indicating the number of the permanent magnets is 28, and the number of slots indicating the number of the coils is 24, The rotor outer diameter is 105 mm or more and 125 mm or less. The electric operating machine according to claim 1 or 2.

4. The rotor outer diameter is 110 mm or more and 120 mm or less. The electric operating machine according to claim 3.

5. the stator core has teeth around which the coil is wound via the insulator, The teeth width is 4 mm or more and 8 mm or less. The electric operating machine according to claim 3 or 4.

6. The magnet thickness indicating the thickness of the permanent magnet is 1.5 mm or more and 3.5 mm or less. The electric operating machine according to any one of claims 3 to 5.

7. The permanent magnet is fixed to an inner circumferential surface of the rotor core. The electric operating machine according to any one of claims 3 to 5.

8. The permanent magnet is fixed to the rotor core by an adhesive. The electric operating machine according to claim 7.

9. a rotor shaft fixed to the rotor, The output portion is fixed to the rotor shaft. The electric operating machine according to any one of claims 3 to 8.

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