Patent ID: 12249875

DETAILED DESCRIPTION

Although one or more embodiments will now be described with reference to the drawings, the present disclosure is not limited to the embodiments described below. The components in the embodiments described below may be combined as appropriate. One or more components may be eliminated.

In the embodiments, the positional relationships between the components will be described using the directional terms such as right and left (or lateral), front and rear, and up and down (or vertical). The terms indicate relative positions or directions with respect to the center of an electric work machine.

The electric work machine includes a motor. In the embodiments, a direction radial from a rotation axis AX of the motor is referred to as a radial direction or radially for convenience. A direction parallel to the rotation axis AX of the motor is referred to as an axial direction for convenience. A direction about the rotation axis AX of the motor is referred to as a circumferential direction, circumferentially, or a rotation direction for convenience.

A position nearer the rotation axis AX of the motor in the radial direction, or a radial direction toward the rotation axis AX, is referred to as being radially inward for convenience. A position farther from the rotation axis AX of the motor in the radial direction, or a radial direction away from the rotation axis AX, is referred to as being radially outward for convenience.

A position in one axial direction, or one axial direction, is referred to as a first axial direction for convenience. A position in the other axial direction, or the other axial direction, is referred to as a second axial direction for convenience. In the embodiments, the axial direction is the vertical direction. When the first axial direction is an upward direction, the second axial direction is a downward direction. When the first axial direction is a downward direction, the second axial direction is an upper direction.

A position in one circumferential direction, or one circumferential direction, is referred to as a first circumferential direction for convenience. A position in the other circumferential direction, or the other circumferential direction, is referred to as a second circumferential direction for convenience.

Electric Work Machine

FIG.1is a diagram of an electric work machine1according to an embodiment. The electric work machine1according to the present embodiment is a lawn mower, which is an example of outdoor power equipment.

As shown inFIG.1, the electric work machine1includes a housing2, wheels3, a motor4, a cutting blade5, a grass box6, a handle7, and a battery mount8.

The housing2accommodates the motor4and the cutting blade5. The housing2supports the wheels3, the motor4, and the cutting blade5.

The wheels3rotate on the ground. Thus, the electric work machine1moves on the ground. The electric work machine1includes four wheels3.

The motor4is a power source for the electric work machine1. The motor4generates a rotational force for rotating the cutting blade5. The motor4is located above the cutting blade5.

The cutting blade5is connected to the motor4. The cutting blade5is an output unit in the electric work machine1that is drivable by the motor4. The cutting blade5is rotatable about the rotation axis AX of the motor4under the rotational force generated by the motor4. The cutting blade5faces the ground. The cutting blade5, with the wheels3in contact with the ground, rotates while mowing grass on the ground. The grass mown by the cutting blade5is collected in the grass box6.

A user holds the handle7of the electric work machine1with his or her hand. The user holding the handle7can move the electric work machine1.

The battery mount8receives a battery pack9. The battery pack9supplies power to the electric work machine1. The battery pack9is detachable from the battery mount8. The battery pack9includes a secondary battery. The battery pack9in the present embodiment includes a rechargeable lithium-ion battery. The battery pack9is attached to the battery mount8to power the electric work machine1. The battery pack9provides a driving current to drive the motor4.

Motor

FIG.2is a perspective view of the motor4in the embodiment as viewed from below.FIG.3is an exploded perspective view of the motor4in the embodiment as viewed from below.FIG.4is a perspective view of the motor4in the embodiment as viewed from above.FIG.5is an exploded perspective view of the motor4in the embodiment as viewed from above.FIG.6is a front view of the motor4in the embodiment.FIG.7is a longitudinal cross-sectional view of the motor4in the embodiment.FIG.7is a cross-sectional view taken along line A-A inFIG.4as viewed in the direction indicated by arrows.FIG.8is a longitudinal cross-sectional view of the motor4in the embodiment.FIG.8is a cross-sectional view taken along line B-B inFIG.4as viewed in the direction indicated by arrows.FIG.9is a cross-sectional view of the motor4in the embodiment.FIG.9is a cross-sectional view taken along line C-C inFIG.6as viewed in the direction indicated by arrows. The motor4in the embodiment is an outer-rotor brushless motor.

As shown inFIGS.2to9, the motor4includes a rotor10, a rotor shaft20, a stator30, a stator base40, a sensor board50, and a motor housing60. The rotor10rotates relative to the stator30. The rotor10at least partially surrounds the stator30. The rotor10is located outside the periphery of the stator30. The rotor shaft20is fixed to the rotor10. The rotor10and the rotor shaft20rotate about the rotation axis AX. The stator base40supports the stator30. The cutting blade5is connected to the rotor shaft20. The cutting blade5is drivable by the rotor10. The sensor board50supports magnetic sensors for detecting rotation of the rotor10.

The motor4in the embodiment has the rotation axis AX extending vertically. The axial direction and the vertical direction are parallel to each other.

The rotor10includes a rotor cup11, a rotor core12, and magnets13.

The rotor cup11is formed from an aluminum-based metal. The rotor cup11includes a plate11A and a yoke11B.

The plate11A is substantially annular. The plate11A surrounds the rotation axis AX. The plate11A has the central axis aligned with the rotation axis AX. The plate11A has an opening11C in its center. The rotor shaft20is at least partially located in the opening11C. In the embodiment, a bush14is located between the outer surface of the rotor shaft20and the inner surface of the opening11C.

The yoke11B is substantially cylindrical. The yoke11B has a lower end connected to the periphery of the plate11A. The plate11A is integral with the yoke11B. The yoke11B extends upward from the periphery of the plate11A. The yoke11B surrounds the stator30. The yoke11B surrounds the rotation axis AX. The yoke11B has the central axis aligned with the rotation axis AX.

The rotor core12includes multiple steel plates stacked in the axial direction. The rotor core12is substantially cylindrical. The rotor core12is supported by the rotor cup11. The rotor cup11at least partially surrounds the rotor core12. The rotor core12is located radially inside the yoke11B. The rotor core12is surrounded by the yoke11B. The rotor core12is supported on the inner circumferential surface of the yoke11B.

The magnets13are permanent magnet plates. The magnets13are sintered plate magnets. The magnets13are fixed to the rotor core12. The magnets13are located radially inside the rotor core12. The magnets13are fixed to the inner circumferential surface of the rotor core12. The magnets13in the embodiment are fixed to the inner circumferential surface of the rotor core12with an adhesive. The multiple (28in the embodiment) magnets13are arranged at circumferentially equal intervals with their N poles and S poles located alternately in the circumferential direction.

The rotor shaft20extends in the axial direction. The rotor shaft20is fixed to the rotor10. The rotor10includes a lower portion received inside the opening11C in the plate11A. The rotor shaft20is fastened to the plate11A with the bush14. The upper end of the rotor shaft20is located above the upper surface of the plate11A. The lower end of the rotor shaft20is located below the lower surface of the plate11A.

The rotor shaft20has the central axis aligned with the rotation axis AX. The rotor shaft is fixed to the rotor10to align the central axis of the rotor shaft20with the central axis of the yoke11B.

The stator30includes a stator core31, an insulator32, and coils33.

The stator core31includes multiple steel plates stacked in the axial direction. The stator core31includes a yoke31A and teeth31B. The yoke31A is cylindrical. The yoke31A surrounds the rotation axis AX. The yoke31A has an outer circumferential surface with the central axis aligned with the rotation axis AX. Each tooth31B protrudes radially outward from the outer circumferential surface of the yoke31A. Multiple (24in the embodiment) teeth31B are located circumferentially at intervals. The teeth31B adjacent to each other have a slot between them.

The insulator32is formed from a synthetic resin. The insulator32is fixed to the stator core31. The insulator32at least partially covers the surface of the stator core31. The insulator32at least partially covers end faces of the yoke31A facing in the axial direction. The end faces of the yoke31A include an upper end face facing upward and a lower end face facing downward. The insulator32at least partially covers the outer surface of the yoke31A facing radially outward. The insulator32at least partially covers the surfaces of the teeth31B.

The stator core31and the insulator32in the embodiment are integral with each other. The insulator32is fixed to the stator core31by insert molding. The stator core31accommodated in a die receives injection of a heat-melted synthetic resin. The synthetic resin then solidifies to form the insulator32fixed to the stator core31.

The coils33are attached to the insulator32. Each coil33is wound around each of the teeth31B with the insulator32in between. The insulator32covers the surfaces of the teeth31B around which the coils33are wound. The insulator32does not cover the outer surface of each tooth31B that faces radially outward. The stator core31and the coil33are insulated from each other by the insulator32. The stator30includes multiple (24in the embodiment) coils33arranged circumferentially.

The stator base40supports the stator core31. The stator base40is fixed to the stator core31. The stator base40is formed from aluminum. The stator base40includes a plate41, a peripheral wall42, and a pipe43.

The plate41is substantially annular. The plate41surrounds the rotation axis AX. The plate41is located above the stator30.

The peripheral wall42is substantially cylindrical. The peripheral wall42includes the upper end connected to the periphery of the plate41. The plate41and the peripheral wall42are integral with each other. The peripheral wall42extends downward from the periphery of the plate41. The peripheral wall42surrounds the yoke11B in the rotor cup11.

The pipe43is substantially cylindrical. The pipe43protrudes downward from a center portion of the lower surface of the plate41. The pipe43surrounds the rotation axis AX. The pipe43has the central axis aligned with the rotation axis AX.

The pipe43is located at least partially inside the stator core31. The pipe43has the central axis aligned with the central axis of the yoke31A.

The pipe43in the embodiment includes a smaller-diameter portion43A and a larger-diameter portion43B. The larger-diameter portion43B is located upward from the smaller-diameter portion43A. The smaller-diameter portion43A and the larger-diameter portion43B are both cylindrical. The larger-diameter portion43B has a larger outer diameter than the smaller-diameter portion43A.

The stator core31surrounds the smaller-diameter portion43A. The larger-diameter portion43B is located outside the stator core31. The larger-diameter portion43B is located above the stator core31. The stator core31is fixed to the pipe43. The stator base40is fixed to the stator30with the central axis of the pipe43aligned with the central axis of the yoke31A.

The motor4includes a motor positioner70for positioning the stator base40and the stator30. The stator base40and the stator core31are positioned with the motor positioner70.

The smaller-diameter portion43A in the embodiment has the outer surface including at least two positions located circumferentially each including a base flat area71. In the embodiment, one base flat area71is located in front of the rotation axis AX, and the other base flat area71is located behind the rotation axis AX. The two base flat areas71are substantially parallel to each other. The smaller-diameter portion43A has the outer surface including base curved areas72. One base curved area72is located on the left of the rotation axis AX, and the other base curved area72is located on the right of the rotation axis AX.

The yoke31A in the stator core31has an inner surface including stator flat areas73and stator curved areas74. The stator flat areas73are in contact with the base flat areas71. The stator curved areas74are in contact with the base curved areas72.

The motor positioner70includes the base flat areas71and the stator flat areas73. The stator flat areas73are in contact with the base flat areas71. The motor positioner70includes the base curved areas72and the stator curved areas74. The stator curved areas74are in contact with the base curved areas72.

The base flat areas71in contact with the stator flat areas73allow the stator base40and the stator core31to be positioned relative to each other both circumferentially and radially. The base curved areas72in contact with the stator curved areas74allow the stator base40and the stator core31to be positioned relative to each other both circumferentially and radially.

The pipe43has a base support surface43C including the boundary between the smaller-diameter portion43A and the larger-diameter portion43B. The base support surface43C faces downward. The base support surface43C surrounds the smaller-diameter portion43A.

The base support surface43C is in contact with the upper end face of the yoke31A in the stator core31.

The motor positioner70has the base support surface43C. The base support surface43C on the pipe43in contact with the upper end face of the yoke31A allows the stator base40and the stator core31to be positioned relative to each other in the axial direction.

The stator core31and the stator base40in the embodiment are fastened together with screws75. The yoke31A in the stator core31has core threaded openings31C. Each core threaded opening31C has a through-hole extending from the upper end face to the lower end face of the yoke31A. Multiple core threaded openings31C surround the rotation axis AX at intervals.

Screw bosses44surround the pipe43. The screw bosses44surround the larger-diameter portion43B. Each screw boss44has a base threaded hole44A. Multiple screw bosses44surround the larger-diameter portion43B at intervals. In other words, multiple base threaded holes44A surround the rotation axis AX at intervals.

At least six (six in the embodiment) core threaded openings31C and at least six (six in the embodiment) base threaded holes44A are located. The multiple core threaded openings31C and the multiple base threaded holes44A surround the rotation axis AX at equal intervals.

The stator core31and the stator base40in the embodiment are fastened together with six screws75. The screws75are placed into the corresponding core threaded openings31C from below the stator core31. Each screw75placed through the corresponding core threaded opening31C has the distal end to be received in the corresponding base threaded hole44A in the screw boss44. Threads on the screws75are engaged with threaded grooves on the base threaded holes44A to fasten the stator core31and the stator base40together.

The motor positioner70includes the screws75. Each screw75placed through the corresponding core threaded opening31C located in the stator core31is further placed into the corresponding base threaded hole44A in the stator base40. The stator base40and the stator core31are fastened together with the screws75.

The pipe43supports the rotor shaft20with a bearing21between them. The bearing21is received in the pipe43. The rotor shaft20includes an upper portion located in the pipe43. The bearing21rotatably supports the upper portion of the rotor shaft20. The rotor shaft20is supported by the pipe43with the bearing21between them.

The stator base40in the embodiment includes an annular plate45located on the upper end of the pipe43. The bearing21has its upper surface located below the lower surface of the annular plate45. A wave washer22is located between the upper surface of the bearing21and the lower surface of the annular plate45. The bearing21has its outer circumferential surface supported on the inner surface of the pipe43. The bearing21has the upper surface supported by the annular plate45with the wave washer22between them.

The sensor board50is supported by the stator base40. The sensor board50is in contact with the stator base40. The sensor board50is fixed to the stator base40. The sensor board50includes magnetic sensors51. The magnetic sensors51detect the magnetic flux of the magnets13in the rotor10. The magnetic sensors51detect changes of the magnetic flux resulting from rotation of the rotor10to detect the position of the rotor10in the rotation direction. The sensor board50is supported by the stator base40with the magnetic sensors51facing the magnets13. The sensor board50is radially outward from the coils33.

The motor housing60accommodates the rotor10and the stator30. The motor housing60is connected to the stator base40. An internal space between the motor housing60and the stator base40accommodates the rotor10and the stator30.

The motor housing60includes a plate61, a peripheral wall62, and a flange63.

The plate61is substantially annular. The plate61is located below the rotor cup11. The plate61includes a pipe64in its center. A lower portion of the rotor shaft20is located in the pipe64.

The motor housing60supports a bearing23. The bearing23rotatably supports the lower portion of the rotor shaft20. The motor housing60in the embodiment includes an annular plate65located at the lower end of the pipe64. The bearing23has the lower surface located above the upper surface of the annular plate65. The bearing23has the outer circumferential surface supported on the inner surface of the pipe64. The bearing23has the lower surface supported on the upper surface of the annular plate65.

The peripheral wall62is substantially cylindrical. The peripheral wall62has its lower end connected to the periphery of the plate61. The peripheral wall62protrudes upward from the periphery of the plate61. The peripheral wall62at least partially surrounds the rotor cup11.

The flange63is connected to the upper end of the peripheral wall62. The flange63extends radially outward from the upper end of the peripheral wall62. The flange63has multiple (four in the embodiment) through-holes66located circumferentially at intervals.

The peripheral wall42in the stator base40includes multiple (four in the embodiment) screw bosses46located circumferentially at intervals. Each of the four screw bosses46has a threaded hole.

The stator base40and the motor housing60are fastened together with four screws67. The screws67are placed into the corresponding through-holes66from below the flange63. Each screw67placed through the corresponding through-hole66has the distal end to be received in the corresponding threaded hole in the screw boss46. Threads on the screw67are engaged with threaded grooves on the threaded holes in the screw bosses46to fasten the stator base40and the motor housing60together.

The peripheral wall42in the stator base40has multiple openings47. One of the openings47receives a shock absorber48. The shock absorber48is formed from, for example, rubber. The shock absorber48received in the opening47supports at least a part of a power line91, which is described later. The shock absorber48prevents wear of the power line91.

The plate61has an air passage68. The air passage68includes a flow channel with a labyrinth structure. For the rotor shaft20receiving a cooling fan fixed to its lower end, the cooling fan rotates as the rotor shaft20rotates. The cooling fan draws air through the air passage68from the internal space between the stator base40and the motor housing60. Air drawn through the air passage68causes air around the motor4to flow into the internal space through the openings47. This cools the motor4.

The rotor cup11includes outlets15. The outlets15discharge foreign matter inside the rotor cup11. Two outlets15are located in the plate11A. For example, water entering the rotor cup11is discharged out of the rotor cup11through the outlets15.

As shown inFIG.2, the motor housing60includes screw bosses600. The screw bosses600are fastened to decks200on the housing2. Each deck200has a through-hole201. Each screw boss600has a threaded hole601. The decks200on the housing2and the motor housing60are fastened together with screws202. Each screw202is placed into the corresponding through-hole201from below the corresponding deck200. Each screw202placed through the corresponding through-hole201has the distal end to be received in the corresponding threaded hole601in the screw boss600. Threads on the screws202are engaged with threaded grooves on the threaded holes601to fasten the decks200on the housing2and the motor housing60together.

The motor housing60includes screw bosses602. The screw bosses602are fixed to a baffle203. The baffle203changes airflow inside the motor housing60. The baffle203faces the lower surface of the motor housing60. The baffle203has an opening203A in its center. The rotor shaft20is placed in the opening203A.

The baffle203has through-holes204. Each screw boss602has a threaded hole603. The baffle203and the motor housing60are fastened together with screws205. The screws205are placed into the corresponding through-holes204from below the baffle203. Each screw205placed through the corresponding through-hole204has the distal end to be received in the corresponding threaded hole603in the screw boss602. Threads on the screws205are engaged with threaded grooves on the threaded holes603to fasten the baffle203and the motor housing60together.

Sensor Board

FIG.10is a bottom view of the stator base40and the sensor board50in the embodiment.FIG.11is an exploded perspective view of the stator base40and the sensor board50in the embodiment as viewed from below.

The sensor board50is substantially arc-shaped. The sensor board50includes a circuit board52and a resin layer53. The resin layer53at least partially covers a surface of the circuit board52. The circuit board52includes a printed circuit board (PCB). The circuit board52has an upper surface and a lower surface. The magnetic sensors51are located on the lower surface of the circuit board52.

In the embodiment, the resin layer53at least partially covers the magnetic sensors51and the surface of the circuit board52. The resin layer53at least partially covers the upper surface of the circuit board52. The resin layer53at least partially covers the lower surface of the circuit board52. The surfaces of the circuit board52receive multiple electronic components in addition to the magnetic sensors51. Examples of the electronic components mountable on the surfaces of the circuit board52include capacitors, resistors, and thermistors. The resin layer53also covers these electronic components.

The sensor board50is supported by the stator base40. The sensor board50is fixed to the stator base40. The stator base40includes bases49. The base49is located inside the peripheral wall42. The base49protrudes downward from the plate41.

The stator base40includes multiple (three in the embodiment) bases49. Each base49includes a base49A, a base49B, and a base49C.

The sensor board50is supported by the bases49. The sensor board50in contact with the bases49is fastened to the bases49.

Each of the bases49has a support surface49S facing the upper surface of the sensor board50. Each support surface49S faces downward. The sensor board50includes support areas54each supported by the corresponding base49. Each of the support areas54is defined on the surface of the circuit board52. No resin layer53is located on the support areas54. The sensor board50is fastened to the bases49with the upper surface of each support area54in contact with the corresponding support surface49S of the base49.

The support areas54include a support area54A, a support area54B, and a support area54C. The support area54A is supported by the base49A. The support area54B is supported by the base49B. The support area54C is supported by the base49C.

The motor4includes a board positioner80for positioning the stator base40and the sensor board50. The board positioner80includes pins81and screws82.

The bases49in the stator base40each have a base pin hole83. The support areas54in the sensor board50each have a board pin hole84. The pin81is placed into both the base pin hole83and the board pin hole84.

The board positioner80includes at least two (two in the embodiment) pins81located circumferentially at intervals.

The base49A and the base49B each have one base pin hole83. The support area54A and the support area54B each have one board pin hole84.

The pins81are press-fitted into the corresponding base pin holes83. Thus, the pins81are fixed to the bases49. The pins81press-fitted into the corresponding base pin holes83are subsequently received in the corresponding board pin holes84.

The bases49in the stator base40each have a base threaded hole85. The support areas54in the sensor board50each have a board threaded opening86. Each screw82is placed through the corresponding board threaded opening86and is received in the corresponding base threaded hole85in the stator base40. Thus, the bases49and the sensor board50are fastened together with the screws82.

The board positioner80includes at least three (three in the embodiment) screws82located circumferentially at intervals.

Each of the base49A, the base49B, and the base49C has one base threaded hole85. Each of the support area54A, the support area54B, and the support area54C has one board threaded opening86.

Rotor

FIG.12is a top view of the rotor10in the embodiment.FIG.13is a cross-sectional view of the rotor10in the embodiment.FIG.14is a perspective cross-sectional view of the rotor10in the embodiment.FIG.15is a partially enlarged perspective cross-sectional view of the rotor10in the embodiment.FIG.16is a partially enlarged longitudinal cross-sectional view of the rotor10in the embodiment.

The rotor10includes the rotor cup11, the rotor core12, and the magnets13. The rotor core12is supported by the rotor cup11. The magnets13are fixed to the rotor core12.

The magnets13are located radially inside the rotor core12. Each magnet13has an upper end face13A, a lower end face13B, an inner end face13C, and an outer end face13D. The upper end face13A faces upward. The lower end face13B faces downward. The inner end face13C faces radially inward. The outer end face13D faces radially outward.

The rotor core12has an upper end face12A, a lower end face12B, an inner circumferential surface12C, and an outer circumferential surface12D. The upper end face12A faces upward. The lower end face12B faces downward. The inner circumferential surface12C faces radially inward. The outer circumferential surface12D faces radially outward. The inner circumferential surface12C of the rotor core12faces the outer end faces13D of the magnets13.

The rotor cup11includes the plate11A and the yoke11B. The yoke11B includes a larger-diameter portion16, a smaller-diameter portion17, and ribs18.

The larger-diameter portion16is located upward from the smaller-diameter portion17. The larger-diameter portion16and the smaller-diameter portion17each surround the rotation axis AX. The inner circumferential surfaces of the larger-diameter portion16and the smaller-diameter portion17each face radially inward. The inner circumferential surface of the larger-diameter portion16is radially outward from the inner circumferential surface of the smaller-diameter portion17.

A core support surface11D is located at the boundary between the larger-diameter portion16and the smaller-diameter portion17. The core support surface11D is annular and surrounds the rotation axis AX. The core support surface11D faces upward. The core support surface11D supports the lower end face12B of the rotor core12.

The core support surface11D also supports at least parts of the lower end faces13B of the magnets13.

The ribs18are located in the first axial direction or downward from the core support surface11D. The ribs18are located on the inner circumferential surface of the smaller-diameter portion17. The ribs18protrude radially inward from the inner circumferential surface of the smaller-diameter portion17.

Each rib18has an upper end face18A and an inner end face18C. The upper end face18A is located in the second (upper) axial direction. The inner end face18C faces radially inward.

The upper end face18A of the rib18is a magnet support surface11E supporting at least a part of the lower end face13B of the corresponding magnet13. The magnet support surface11E in the embodiment supports a part of the lower end face13B of each magnet13.

The ribs18are circumferentially smaller than the magnets13. Each rib18is circumferentially aligned to the middle of the corresponding magnet13. In other words, the magnet support surface11E circumferentially supports the middle of the lower end face13B of each magnet13.

The inner end face18C of each rib18is located radially outward from the inner end face13C of the corresponding magnet13. In other words, the magnet support surface11E has an inner edge located radially outward from the inner edge of the lower end face13B of the magnet13.

The number of ribs18is the same as the number of magnets13. The rotor10in the embodiment includes the28magnets13. The yoke11B in the embodiment includes 28 ribs18.

The upper end faces13A of the magnets13protrude upward from the upper end face12A of the rotor core12.

The rotor core12includes a ring12E and inner protrusions12F. The ring12E has the inner circumferential surface12C. The inner protrusions12F protrude radially inward from the inner circumferential surface12C of the ring12E. The inner protrusions12F are located between the magnets13circumferentially adjacent to each other.

The ring12E in the rotor core12has the outer circumferential surface12D including outer protrusions12G. The outer protrusions12G are in contact with the inner circumferential surface of the yoke11B of the rotor cup11. Multiple outer protrusions12G are located circumferentially at intervals. The rotor cup11has the inner circumferential surface having recesses11F to receive the outer protrusions12G. One recess11F receives three outer protrusions12G.

The multiple (three) outer protrusions12G in the recess11F receive an adhesive, which is filled between the outer protrusions12G adjacent to each other. Thus, an adhesive layer19is located between the outer protrusions12G adjacent to each other. The adhesive layer19fixes the rotor core12and the rotor cup11together.

Insulator

FIG.17is a perspective view of the stator30in the embodiment as viewed from above.FIG.18is a perspective view of the stator30in the embodiment as viewed from below.FIG.19is an exploded perspective view of the stator30in the embodiment as viewed from above.FIG.20is a partial cross-sectional view of the stator30in the embodiment.FIG.20is a cross-sectional view taken along line D-D inFIG.18as viewed in the direction indicated by arrows.FIG.21is a partial cross-sectional view of the stator30in the embodiment.FIG.21is a cross-sectional view taken along line E-E inFIG.18as viewed in the direction indicated by arrows.

The insulator32includes an upper end cover32A, a lower end cover32B, an outer circumference cover32C, and a tooth cover32D.

The upper end cover32A covers a peripheral edge of the upper end face of the yoke31A. The lower end cover32B covers a peripheral edge of the lower end face of the yoke31A. The outer circumference cover32C covers an outer circumferential surface of the yoke31A facing radially outward. The tooth cover32D covers surfaces of the teeth31B around which the coils33are wound.

The insulator32includes an upper peripheral wall34, a lower peripheral wall35, ribs36, protrusions37, retainers38, and receptacles39.

The upper peripheral wall34surrounds the rotation axis AX. The upper peripheral wall34protrudes upward from the upper end cover32A. The upper peripheral wall34is located radially inward from the coils33.

The lower peripheral wall35surrounds the rotation axis AX. The lower peripheral wall35protrudes downward from the lower end cover32B. The lower peripheral wall35is located radially inward from the coils33.

The ribs36are located on the lower end cover32B. The ribs36protrude downward from the lower end cover32B. Multiple ribs36are located circumferentially at intervals. The multiple ribs36have the same height. The ribs36are fewer than the coils33.

The protrusions37are located on the lower end cover32B. The protrusions37are shorter than the ribs36. The number of protrusions37is less than the number of ribs36. The protrusions37are fewer than the coils33.

The retainers38are located on the upper peripheral wall34. Each retainer38includes a hook located on the outer circumferential surface of the upper peripheral wall34.

The receptacles39are located on the upper peripheral wall34.

The insulator32includes multiple ribs32E. Each rib32E protrudes upward from the upper end cover32A.

The multiple coils33include a wound single wire90. The single wire90is sequentially wound around each of the teeth31B with the tooth cover32D between them. The wire90connects a first coil33and a second coil33wound after the first coil33.

Each rib36supports the wire90connecting the multiple coils33. The wire90is placed on each rib36. The wire90extends from radially inside the rib36and is placed on the corresponding rib36. Each rib36supports the wire90. The wire90thus extends from the lower end cover32B and is placed into a space between the teeth31B adjacent to each other. As described above, the teeth31B adjacent to each other define a slot between them. Each rib36thus supports the wire90to allow the wire90extending from the lower end cover32B to be placed into the slot. Each rib36guides the wire90from the lower end cover32B to the lower end of the slot.

The wire90includes multiple portions located on the lower end cover32B. The wire90includes overlapping portions. For example, the wire90includes a first portion connecting the first coil33and the second coil33on the lower end cover32B. The wire90includes a second portion connecting a third coil33and a fourth coil33also on the lower end cover32B. The second portion of the wire90at least partially overlaps the first portion of the wire90. The protrusion37supports the second portion of the wire90, and the first portion of the wire90is less likely to come in contact with the second portion of the wire90.

When the second portion of the wire90is located partially covering the first portion of the wire90, the protrusion37supports the second portion of the wire90. The protrusion37has a support surface37A for supporting the second portion of the wire90. The support surface37A has the lower surface of the protrusion37. The support surface37A faces downward. The second portion of the wire90is at least partially located on the support surface37A of the protrusion37.

A driving current is supplied to the coils33. The driving current is supplied to the coils33through the power lines91and fusing terminals92. The driving current supplied to the coils33flows through the power lines91and the fusing terminals92.

Each of the24coils33is assigned to one of a U- (UV-) phase, a V- (VW-) phase, and a W- (WU-) phase. The power lines91include a power line91U, a power line91V, and a power line91W. The U-phase driving current flows through the power line91U. The V-phase driving current flows through the power line91V. The W-phase driving current flows through the power line91W.

The retainers38hold the power lines91. Each retainer38includes a hook for receiving the corresponding power line91. The insulator32in the embodiment includes two retainers38. The power line91V is placed on one retainer38. The power line91W is placed on the other retainer38.

The retainer38at least partially protrudes radially outward from the outer circumferential surface of the upper peripheral wall34. At least apart of the power line91surrounds the outer circumferential surface of the upper peripheral wall34. At least a part of the power line91is located between the upper peripheral wall34and the retainers38. At least a part of the power line91is supported on the outer circumferential surface of the upper peripheral wall34.

The fusing terminals92connect different portions of the wire90protruding from the multiple coils33. The fusing terminals92include a fusing terminal92U, a fusing terminal92V, and a fusing terminal92W. A U-phase driving current flows through the fusing terminal92U. A V-phase driving current flows through the fusing terminal92V. A W-phase driving current flows through the fusing terminal92W.

The power line91U is connected to the fusing terminal92U. The power line91V is connected to the fusing terminal92V. The power line91W is connected to the fusing terminal92W.

The fusing terminal92is placed into the corresponding receptacle39located in the upper peripheral wall34. The receptacles39include a receptacle39U, a receptacle39V, and a receptacle39W. The receptacle39U receives the fusing terminal92U. The receptacle39V receives the fusing terminal92V. The receptacle39W receives the fusing terminal92W.

FIG.22is a perspective view of the fusing terminal92and the receptacle39in the embodiment.FIG.23is a side view of the fusing terminal92in the embodiment.FIG.24is a cross-sectional view of the fusing terminal92received in the receptacle39in the embodiment. As shown inFIG.22, the fusing terminal92is placed in the receptacle39, which receives multiple portions of the wire90. In other words, the wire90is placed in the receptacle39before the fusing terminal92is received in the receptacle39.

The fusing terminal92includes a base plate92A, a holder plate92B, a ring92C, and a fastener92D. The holder plate92B and the base plate92A hold the wire90between them. The ring92C holds the power line91. The fastener92D connects the base plate92A and the holder plate92B. An opening92E is defined between the lower end of the base plate92A and the lower end of the holder plate92B.

The fusing terminal92includes lower anchors92F and upper anchors92G on the base plate92A. The lower anchors92F are located downward from the upper anchors92G. The fusing terminal92includes two lower anchors92F. The fusing terminal92includes two upper anchors92G. InFIG.24, one lower anchor92F protrudes frontward from the front of the base plate92A. The other lower anchor92F protrudes rearward from the rear of the base plate92A. InFIG.24, one upper anchor92G protrudes frontward from the front of the base plate92A. The other upper anchor92G protrudes rearward from the rear of the base plate92A.

Each receptacle39includes a pair of compartments39A and a pair of hooks39B. The pair of compartments39A are circumferentially adjacent to each other. The pair of hooks39B are located radially outward from the compartments39A. Each compartment39A includes a recess39C to receive the corresponding base plate92A. The wire90is placed between the compartments39A and the hooks39B.

As shown inFIG.24, each recess39C includes a pair of lower portions39D and a pair of upper portions39E on its inner surface. The pair of lower portions39D are located in the front-rear direction. The pair of upper portions39E are located in the front-rear direction. The distance between one lower portion39D and the other lower portion39D (width of the recess39C in the lower portions39D) is shorter than the distance between one upper portion39E and the other upper portion39E (width of the recess39C in the upper portions39E). When the base plate92A is placed into the recesses39C, the pairs of upper portions39E receive the pair of lower anchors92F between them. The base plate92A thus stands in the recesses39C. Subsequently, the base plate92A is pushed further downward in the recesses39C, and the lower anchors92F and the upper anchors92G are engaged with the inner surfaces of the recesses39C. This fastens the fusing terminal92to the upper peripheral wall34.

Coil Structure

The structure of the coils33will now be described.FIG.25is a bottom view of the stator30in the embodiment.FIG.26is a schematic diagram of the coils33in the embodiment.

As described above, the stator30in the embodiment includes the24coils33. The24coils33are numbered C1to C24and will be described below. The coil C1is adjacent to the coil C2in the first circumferential direction. The coil C2is adjacent to the coil C3in the first circumferential direction. Similarly, the coils C4through C24are each adjacent to the coils C3through C23in the first circumferential direction. The coil C24is adjacent to the coil C1in the first circumferential direction.

The24coils33are formed by winding the single wire90. As shown inFIG.26, the wire90starts being wound at a winding start S. The wire90is wound sequentially around each of the teeth31B to form the multiple coils33sequentially. The24coils33are formed by winding the wire90, which is wound finally at a winding end E.

In the embodiment, some of the coils33are formed by winding the wire90in the forward direction (counterclockwise). Other coils33are formed by winding the wire90in the reversed direction (clockwise). The arrows inFIG.26indicate the winding direction of the wire90. The coils C1, C4, C5, C8, C9, C12, C13, C16, C17, C20, C21, and C24are formed by winding the wire90in the forward direction. The coils C2, C3, C6, C7, C10, C11, C14, C15, C18, C19, C22, and C23are formed by winding the wire90in the reversed direction.

The coils C1, C2, C7, C8, C13, C14, C19, and C20are assigned to the U- (UV-) phase. The coils C3, C4, C9, C10, C15, C16, C21, and C22are assigned to the V- (VW-) phase. The coils C5, C6, C11, C12, C17, C18, C23, and C24are assigned to the W- (WU-) phase.

InFIG.26, the coils33with letters UV are assigned to the UV-phase and are formed by winding the wire90in the forward direction. The letters UV are underlined for the coils33formed by winding the wire90in the reversed direction.

The coils33with letters VW are assigned to the VW-phase and are formed by winding the wire90in the forward direction. The letters VW are underlined for the coils33formed by winding the wire90in the reversed direction.

The coils33with letters WU are assigned to the WU-phase and are formed by winding the wire90in the forward direction. The letters WU are underlined for the coils33formed by winding the wire90in the reversed direction.

In the embodiment, the coil C1is formed first. The wire90wound in the forward direction to form the coil C1is then pulled toward a non-connection position below the teeth31B (near the lower end cover32B). The wire90pulled to the non-connection position is placed on the corresponding rib36and wound to form the coil C2.

The wire90wound in the reversed direction to form the coil C2is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C8. The wire90wound in the forward direction to form the coil C8is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C7. The wire90wound in the reversed direction to form the coil C7is then pulled toward a connection position above the teeth31B (near the upper end cover32A).

The wire90pulled to the connection position is wound to form the coil C21. The wire90wound in the forward direction to form the coil C21is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C22.

The wire90wound in the reversed direction to form the coil C22is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C4. The wire90wound in the forward direction to form the coil C4is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C3. The wire90wound in the reversed direction to form the coil C3is then pulled toward the connection position.

The wire90pulled to the connection position is wound to form the coil C17. The wire90wound in the forward direction to form the coil C17is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C18.

The wire90wound in the reversed direction to form the coil C18is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C24. The wire90wound in the forward direction to form the coil C24is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C23. The wire90wound in the reversed direction to form the coil C23is then pulled toward the connection position.

The wire90pulled to the connection position is wound to form the coil C13. The wire90wound in the forward direction to form the coil C13is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C14.

The wire90wound in the reversed direction to form the coil C14is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C20. The wire90wound in the forward direction to form the coil C20is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C19. The wire90wound in the reversed direction to form the coil C19is then pulled toward the connection position.

The wire90pulled to the connection position is wound to form the coil C9. The wire90wound in the forward direction to form the coil C9is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C10.

The wire90wound in the reversed direction to form the coil C10is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C16. The wire90wound in the forward direction to form the coil C16is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C15. The wire90wound in the reversed direction to form the coil C15is then pulled toward the connection position.

The wire90pulled to the connection position is wound to form the coil C5. The wire90wound in the forward direction to form the coil C5is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C6.

The wire90wound in the reversed direction to form the coil C6is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C12. The wire90wound in the forward direction to form the coil C12is then pulled toward the non-connection position, placed on the corresponding rib36, and wound to form the coil C11. The wire90wound in the reversed direction to form the coil C11is then pulled toward the connection position.

This completes the24coils33.

The wire90located on the connection position includes a portion between the winding start S and the coil C1and a portion between the coil C11and the winding end E. These portions of the wire90are each connected to the fusing terminal92U.

The wire90located on the connection position includes a portion between the coil C7and the coil C21and a portion between the coil C19and the coil C9. These portions of the wire90are each connected to the fusing terminal92V.

The wire90located on the connection position includes a portion between the coil C3and the coil C17and a portion between the coil C15and the coil C5. These portions of the wire90are each connected to the fusing terminal92W.

As shown inFIGS.25and26, the wire90includes multiple portions located on the non-connection position or the lower end cover32B. The portions of the wire90located on the non-connection position include a wire901connecting the coil C2to the coil C8, a wire902connecting the coil C6to the coil C12, a wire903connecting the coil C9to the coil C10, a wire904connecting the coil C10to the coil C16, a wire905connecting the coil C14to the coil C20, a wire906connecting the coil C18to the coil C24, and a wire907connecting the coil C22to the coil C4.

The wire90includes overlapping portions on the lower end cover32B at the non-connection position. With the protrusions37, a pair of overlapping portions of the wire90are less likely to come in contact with each other. The protrusions37in the embodiment include a protrusion371, a protrusion372, a protrusion373, a protrusion374, a protrusion375, a protrusion376, and a protrusion377.

As shown inFIGS.25and26, the wire902overlaps at least a part of the wire901. The protrusion371supports the wire902. Thus, the wire901is less likely to come in contact with the wire902. The wire902on the protrusion371is lifted above the wire901. Thus, the wire901is less likely to come in contact with the wire902.

The wire902overlaps at least a part of the wire903. The protrusion372supports the wire902. Thus, the wire903is less likely to come in contact with the wire902. The wire902on the protrusion372is lifted above the wire903. Thus, the wire903is less likely to come in contact with the wire902.

The wire902overlaps at least a part of the wire904. The protrusion373supports the wire902. Thus, the wire904is less likely to come in contact with the wire902. The wire902on the protrusion373is lifted above the wire904. Thus, the wire904is less likely to come in contact with the wire902.

The wire904overlaps at least a part of the wire905. The protrusion374supports the wire904. Thus, the wire905is less likely to come in contact with the wire904. The wire904on the protrusion374is lifted above the wire905. Thus, the wire905is less likely to come in contact with the wire904.

The wire905overlaps at least a part of the wire906. The protrusion375supports the wire905. Thus, the wire906is less likely to come in contact with the wire905. The wire905on the protrusion375is lifted above the wire906. Thus, the wire906is less likely to come in contact with the wire905.

The wire906overlaps at least a part of the wire907. The protrusion376supports the wire906. Thus, the wire907is less likely to come in contact with the wire906. The wire906on the protrusion376is lifted above the wire907. Thus, the wire907is less likely to come in contact with the wire906.

The wire907overlaps at least a part of the wire901. The protrusion377supports the wire907. Thus, the wire901is less likely to come in contact with the wire907. The wire907on the protrusion377is lifted above the wire901. Thus, the wire901is less likely to come in contact with the wire907.

Controller

FIG.27is a schematic diagram of the electric work machine1according to the embodiment. As shown inFIG.27, the coils33are delta-connected. The coils C1, C2, C8, C7, C13, C14, C20, and C19are assigned to the U- (UV-) phase. The coils C9, C10, C16, C15, C21, C22, C4, and C3are assigned to the V- (VW-) phase. The coils C5, C6, C12, C11, C17, C18, C24, and C23are assigned to the W- (WU-) phase.

The coils C1, C2, C8, and C7are connected in series. The coils C13, C14, C20, and C19are connected in series. The coils C1, C2, C8, and C7are connected to the coils C13, C14, C20, and C19in parallel.

The coils C9, C10, C16, and C15are connected in series. The coils C21, C22, C4, and C3are connected in series. The coils C9, C10, C16, and C15are connected to the coils C21, C22, C4, and C3in parallel.

The coils C5, C6, C12, and C11are connected in series. The coils C17, C18, C24, and C23are connected in series. The coils C5, C6, C12, and C11are connected to the coils C17, C18, C24, and C23in parallel.

In other words, the24coils33are arranged with two strings of coils33connected in parallel, each string including four coils33connected in series. The strings are delta-connected.

The sensor board50includes three magnetic sensors51. The magnetic sensors51include a magnetic sensor51U corresponding to the U- (UV-) phase, a magnetic sensor51V corresponding to the V- (VW-) phase, and a magnetic sensor51W corresponding to the W- (WU-) phase.

The electric work machine1includes a controller100, a gate circuit101, an inverter102, and a current detector103.

The controller100includes a circuit board on which multiple electronic components are mounted. Examples of the electronic components mountable on the circuit board include a processor such as a central processing unit (CPU), a nonvolatile memory such as a read-only memory (ROM) or a storage device, and a volatile memory such as a random-access memory (RAM).

The inverter102supplies a driving current to the coils33in accordance with the power supplied from the battery pack9. The inverter102includes 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).

The switching element QHu is located between the fusing terminal92U and the power line connected to the positive terminal of the battery pack9. The switching element QHv is located between the fusing terminal92V and the power line connected to the positive terminal of the battery pack9. The switching element QHw is located between the fusing terminal92W and the power line connected to the positive terminal of the battery pack9. Turning on the switching element QHu electrically connects the fusing terminal92U and the power line. Turning on the switching element QHv electrically connects the fusing terminal92V and the power line. Turning on the switching element QHw electrically connects the fusing terminal92W and the power line.

The switching element QLu is located between the fusing terminal92U and the ground line connected to the negative terminal of the battery pack9. The switching element QLv is located between the fusing terminal92V and the ground line connected to the negative terminal of the battery pack9. The switching element QLw is located between the fusing terminal92W and the ground line connected to the negative terminal of the battery pack9.

Turning on the switching element QLu electrically connects the fusing terminal92U and the ground line. Turning on the switching element QLv electrically connects the fusing terminal92V and the ground line. Turning on the switching element QLw electrically connects the fusing terminal92W and the ground line.

The gate circuit101drives the switching elements QHu, QHv, QHw, QLu, QLv, and QLw. The controller100outputs control signals to the gate circuit101to drive the switching elements QHu, QHv, QHw, QLu, QLv, and QLw in the inverter102.

The current detector103is located on a current path from the inverter102to the negative terminal of the battery pack9. The current detector103outputs a signal with a voltage corresponding to the current flowing through the current path. The controller100detects the driving current flowing through the coils33in response to output signals from the current detector103.

FIG.28is a table showing driving patterns for the switching elements QHu, QHv, QHw, QLu, QLv, and QLw in the embodiment. As shown inFIG.28, the switching elements QHu, QHv, QHw, QLu, QLv, and QLw are driven in six driving patterns Dp1, Dp2, Dp3, Dp4, Dp5, and Dp6.

In the driving pattern Dp1, the switching elements QHv and QLu are turned on. Thus, the driving current flows through each of the coils33assigned to the UV-phase from the fusing terminal92V to the fusing terminal92U.

In the driving pattern Dp2, the switching elements QHw and QLu are turned on. Thus, the driving current flows through each of the coils33assigned to the WU-phase from the fusing terminal92W to the fusing terminal92U.

In the driving pattern Dp3, the switching elements QHw and QLv are turned on. Thus, the driving current flows through each of the coils33assigned to the VW-phase from the fusing terminal92W to the fusing terminal92V.

In the driving pattern Dp4, the switching elements QHu and QLv are turned on. Thus, the driving current flows through each of the coils33assigned to the UV-phase from the fusing terminal92U to the fusing terminal92V.

In the driving pattern Dp5, the switching elements QHu and QLw are turned on. Thus, the driving current flows through each of the coils33assigned to the WU-phase from the fusing terminal92U to the fusing terminal92W.

In the driving pattern Dp6, the switching elements QHv and QLw are turned on. Thus, the driving current flows through each of the coils33assigned to the VW-phase from the fusing terminal92V to the fusing terminal92W.

The six driving patterns Dp1to Dp6are repeated sequentially to generate a rotating magnetic field in the motor4, thus rotating the rotor10.

Method for Assembling Motor

FIG.29is a diagram describing a method for assembling the motor4in the embodiment. As shown inFIG.29, the stator30and the stator base40are fastened together with the screws75. The rotor10and the rotor shaft20are fixed together.

The stator30and the stator base40are fastened together with the six screws75. Five or fewer screws75may be used to fasten the stator30and the stator base40together. The stator30has a resonant frequency adjustable in accordance with the number of screws75. This reduces noise (electromagnetic noise) from the motor4.

The stator30and the stator base40are fastened together, and the rotor10and the rotor shaft20are fixed together. Subsequently, the pipe43receives the upper portion of the rotor shaft20. The rotor shaft20is placed into the pipe43from below the stator30. The rotor shaft20includes the bearing21attached on its upper end. The bearing21is guided along the pipe43as the rotor shaft20is placed into the pipe43.

With the upper end of the rotor shaft20vertically aligned with the lower end of the pipe43, the magnets13are located below the stator core31. In other words, the magnets13do not face the stator core31before the rotor shaft20is placed into the pipe43. The magnets13at least partially face the stator core31when the rotor shaft20is at least partially placed into the pipe43. Magnets13facing the stator core31before the rotor shaft20is placed into the pipe43may cause the magnets13and the stator core31to stick together with a magnetic force. This may disable smooth placement of the rotor shaft20into the pipe43.

In the embodiment, the pipe43, the stator core31, the rotor shaft20, and the magnets13are located at predetermined positions relative to one another to prevent the magnets13from facing the stator core31before the rotor shaft20is placed into the pipe43. The magnets13at least partially face the stator core31when the rotor shaft20is at least partially placed into the pipe43. This prevents the magnets13and the stator core31from sticking together. Thus, the rotor shaft20can be smoothly placed into the pipe43.

As described above, the electric work machine1according to the embodiment includes the stator30including the stator core31, the insulator32fixed to the stator core31, and the coils33attached to the insulator32, the rotor10rotatable about the rotation axis AX and including the rotor core12and the magnets13fixed to the rotor core12, the stator base40supporting the stator30, the sensor board50supported by the stator base40and including the magnetic sensors51to detect the magnets13, and the cutting blade5as an output unit drivable by the rotor10.

In the above structure, the stator base40supports each of the stator30and the sensor board50. Thus, the relative position between the stator30and the sensor board50is less likely to change. The relative position between the stator30and the rotor10is controlled with high accuracy. Thus, the relative position between the stator30and the sensor board50is less likely to change. The relative position between the sensor board50and the rotor10is controlled appropriately. Thus, the magnetic sensors51on the sensor board50can detect rotation of the rotor10appropriately.

In the embodiment, the rotor10at least partially surrounds the stator30.

This allows appropriate detection of rotation of the rotor10in the motor4that is an outer-rotor motor.

The sensor board50in the embodiment is in contact with the stator base40.

The relative position between the stator base40and the sensor board50is sufficiently less likely to change.

The electric work machine1according to the embodiment includes the board positioner80to position the stator base40and the sensor board50relative to each other.

The sensor board50is appropriately positioned relative to the stator base40with the board positioner80.

The stator base40in the embodiment has the base pin holes83. The sensor board50has the board pin holes84. The board positioner80includes the pins81placed into both the base pin holes83and the board pin holes84.

In this manner, the sensor board50is positioned relative to the stator base40with a simple structure.

The board positioner80in the embodiment includes at least two pins81.

Thus, the sensor board50is positioned relative to the stator base40, for example, in both the radial and rotation directions.

The pins81in the embodiment are press-fitted into the corresponding base pin holes83.

In this manner, the sensor board50is positioned relative to the stator base40with a simple structure.

In the embodiment, the sensor board50has the board threaded openings86. The stator base40has the base threaded holes85, or first base threaded holes. The board positioner80includes the screws82, or first screws, each placed into the corresponding base threaded hole85through the corresponding board threaded opening86.

In this manner, the sensor board50is fastened to the stator base40with a simple structure.

The electric work machine1according to the embodiment includes the motor positioner70to position the stator base40and the stator30relative to each other.

The stator30is appropriately positioned relative to the stator base40with the motor positioner70.

In the embodiment, the stator base40includes the pipe43located inside the stator core31. The pipe43has the outer surface including the base flat areas71. The stator core31has the inner surface including the stator flat areas73in contact with the base flat areas71. The motor positioner70includes the base flat areas71and the stator flat areas73.

Thus, the stator30is appropriately positioned relative to the stator base40, for example, in the rotation direction.

The pipe43in the embodiment has the outer surface including at least two positions each including the base flat area71located circumferentially about the rotation axis AX.

Thus, the stator30is appropriately positioned relative to the stator base40.

The pipe43in the embodiment has the outer surface including the base curved areas72. The stator core31has the inner surface including the stator curved areas74in contact with the base curved areas72. The motor positioner70includes the base curved areas72and the stator curved areas74.

Thus, the stator30is appropriately positioned relative to the stator base40, for example, in the radial direction.

The stator base40in the embodiment has the base support surface43C in contact with the stator core31on the upper end face, or an end face in the first axial direction. The motor positioner70has the base support surface43C.

Thus, the stator30is appropriately positioned in the stator base40, for example, in the axial direction.

The pipe43has the base support surface43C in the embodiment.

Thus, the stator30is positioned relative to the stator base40with a simple structure.

In the embodiment, the stator core31has the core threaded openings31C. The stator base40has the base threaded holes44A, or second base threaded holes. The motor positioner70includes the screws75, or second screws, each placed into the corresponding base threaded hole44A through the corresponding core threaded opening31C.

Thus, the stator30is fastened to the stator base40with a simple structure.

In the embodiment, the stator core31has the multiple core threaded openings31C surrounding the rotation axis AX at intervals. The stator base40has the multiple base threaded holes44A surrounding the rotation axis AX at intervals.

Thus, the stator30and the stator base40are fastened tightly together with the multiple screws75.

In the embodiment, the stator core31has six core threaded openings31C. The stator base40has six base threaded holes44A. The stator30has a resonant frequency adjustable in accordance with the number of screws75.

Thus, the stator30and the stator base40are fastened tightly together with at least six screws75. The stator30also has a resonant frequency adjustable in accordance with the number of screws75. This reduces noise (electromagnetic noise) from the motor4.

The base threaded holes44A in the embodiment are located in the screw bosses44surrounding the pipe43.

Thus, the stator core31and the pipe43are fastened tightly together.

The electric work machine1according to the embodiment includes the rotor shaft20fixed to the rotor10. The pipe43supports the rotor shaft20with the bearing21between them.

This prevents the electric work machine1from being upsized.

The magnets13in the embodiment are fixed to the inner circumferential surface of the rotor core12.

This prevents the motor4from being upsized.

OTHER EMBODIMENTS

FIG.30is a partial schematic diagram of a rotor10in another embodiment. In the above embodiments, the magnet support surface11E supports the middle of the lower end face13B of each magnet13. As shown inFIG.30, the magnet support surface11E may support a part of the lower end face13B of a first magnet13, and a part of the lower end face13B of a second magnet13adjacent to the first magnet13. In other words, each rib18with the magnet support surface11E may be located circumferentially aligned with the boundary between two magnets13adjacent to each other. As shown inFIG.30, one magnet13is supported by two ribs18.

FIG.31is a top view of the rotor10in the other embodiment.FIG.32is a cross-sectional view of the rotor10in the other embodiment. In the above embodiment, the rotor core12and the rotor cup11are fixed together with the adhesive layers19between the outer protrusions12G adjacent to each other. As shown inFIGS.31and32, the rotor core12and the rotor cup11may be fixed together with anaerobic adhesive layers190. Each anaerobic adhesive layer190is located on the boundary between the inner surface of a protrusion11G on the rotor cup11and the outer surface of the rotor core12. The protrusion11G is located between the recesses11F that are circumferentially adjacent to each other. Each anaerobic adhesive layer190is formed with an anaerobic adhesive applied on either the inner surface of the protrusion11G or the outer surface of the rotor core12, or both.

In the above embodiments, the multiple ribs36have the same height. The ribs36may have different heights.

In the above embodiments, the electric work machine1is a lawn mower, which is an example of outdoor power equipment. Examples of the outdoor power equipment are not limited to lawn mowers. Examples of the outdoor power equipment include a hedge trimmer, a chain saw, a mower, and a blower. The electric work machine1may be a power tool. Examples of the power tool 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.

In the above embodiments, the electric work machine is powered by the battery pack attached to the battery mount. In some embodiments, the electric work machine may use utility power (alternating-current power supply).

REFERENCE SIGNS LIST

1electric work machine2housing3wheel4motor5cutting blade6grass box7handle8battery mount9battery pack10rotor11rotor cup11A plate11B yoke11C opening11D core support surface11E magnet support surface11F recess11G protrusion12rotor core12A upper end face12B lower end face12C inner circumferential surface12D outer circumferential surface12E ring12F inner protrusion12G outer protrusion13magnet13A upper end face13B lower end face13C inner end face13D outer end face14bush15outlet16larger-diameter portion17smaller-diameter portion18rib18A upper end face18C inner end face19adhesive layer20rotor shaft21bearing22wave washer23bearing30stator31stator core31A yoke31B tooth31C core threaded opening32insulator32A upper end cover32B lower end cover32C outer circumference cover32D tooth cover32E rib33coil34upper peripheral wall35lower peripheral wall36rib37protrusion37A support surface38retainer39receptacle39A compartment39B hook39C recess39D lower portion39E upper portion39U receptacle39V receptacle39W receptacle40stator base41plate42peripheral wall43pipe43A smaller-diameter portion43B larger-diameter portion43C base support surface44screw boss44A base threaded hole45annular plate46screw boss47opening48shock absorber49base49A base49B base49C base49S support surface50sensor board51magnetic sensor51U magnetic sensor51V magnetic sensor51W magnetic sensor52circuit board53resin layer54support area54A support area54B support area54C support area60motor housing61plate62peripheral wall63flange64pipe65annular plate66through-hole67screw68air passage70motor positioner71base flat area72base curved area73stator flat area74stator curved area75screw80board positioner81pin82screw83base pin hole84board pin hole85base threaded hole86board threaded opening90wire91power line91U power line91V power line91W power line92fusing terminal92A base plate92B holder plate92C ring92D fastener92E opening92F lower anchor92G upper anchor92U fusing terminal92V fusing terminal92W fusing terminal100controller101gate circuit102inverter103current detector190anaerobic adhesive layer200deck201through-hole202screw203baffle203A opening204through-hole205screw371protrusion372protrusion373protrusion374protrusion375protrusion376protrusion377protrusion600screw boss601threaded hole602screw boss603threaded hole901wire902wire903wire904wire905wire906wire907wireAX rotation axis