Electric work machine

Patent metadata

Field	Value
Publication number	US-10862376-B2
Application number	US-201916460149-A
Country	US
Kind code	B2
Filing date	Jul 2, 2019
Priority date	Aug 7, 2018
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

An electric work machine includes a brushless motor including a stator including a stator core, an electrical insulator located on the stator core, and at least one coil wound around the stator core with the electrical insulator in between, and a rotor rotatable with respect to the stator, and an output unit drivable by the brushless motor. The stator core has a through-hole and/or a recess to lock rotation of the stator with a screw.

First claim

What is claimed is:

1. An electric work machine, comprising:
a brushless motor including
a stator including a stator core having a through-hole, an electrical insulator located on the stator core, and at least one coil wound around the stator core with the electrical insulator in between, and
a rotor rotatable with respect to the stator;

an output unit drivable by the brushless motor;
an upper case and a lower case located at each axial end of the stator; and
a screw passing through the through-hole
to lock rotation of the stator, the upper case and the lower case.

2. An electric work machine, comprising:
a brushless motor including
a stator including a stator core, an electrical insulator located on the stator core, and at least one coil wound around the stator core with the electrical insulator in between, and
a rotor rotatable with respect to the stator;

an upper case and a lower case located at each axial end of the stator; and
an output unit drivable by the brushless motor,
wherein the stator core includes a cylindrical outer surface and a ridge (a) that extends (1) outwardly from the cylindrical outer surface and (2) in an axial direction and (b) engages the upper case and the lower case to prevent rotation of the stator core relative to the upper case and the lower case.

3. The electric work machine according to claim 2 , wherein
the ridge has a tapered cross section with a circumferential width gradually decreasing radially outward from the stator core.

4. The electric work machine according to claim 2 , wherein the upper case includes a screw boss that corresponds to the ridge.

5. The electric work machine according to claim 4 , wherein
the lower case includes a boss part with the same shape as the screw boss.

6. The electric work machine according to claim 5 , further comprising:
a screw that extends from the boss part through the ridge and is placed received in the screw boss.

7. The electric work machine according to claim 2 , wherein
the lower case further includes a boss to be screwed to a base in the electric work machine.

8. The electric work machine according to claim 2 , wherein
the upper case includes a fin to dissipate heat.

9. The electric work machine according to claim 2 , wherein
the upper case has a slit to allow passage of a lead wire connected to the at least one coil.

10. An electric work machine, comprising:
a brushless motor including
a stator including a stator core, an electrical insulator fixed to the stator core, and a first coil and a second coil wound around the stator core with the electrical insulator in between, and
a rotor rotatable with respect to the stator;

an output unit drivable by the brushless motor; and
a plurality of metal sheets attached to the electrical insulator, wherein:
the stator core is cylindrical and includes a plurality of teeth protruding inwardly;
the plurality of teeth include:
a first tooth around which the first coil is wound; and
a second tooth adjacent to the first tooth around which the second coil is wound;
an end of the first coil and an end of the second coil extend in the same direction to be electrically connected to the metal sheets; and
the plurality of metal sheets are configured to short-circuit connection wires between the first and second coils wound around the teeth adjacent to one another in a circumferential direction of the stator core to form a delta connection.

11. The electric work machine according to claim 10 , further comprising:
a lid located at an axial end of the stator, wherein:
the stator core includes, on an outer circumference, a projection that engages the lid to lock rotation of the stator, and
the projection includes a ridge extending parallel to an axis of the stator core, and the ridge has a tapered cross section with a circumferential width gradually decreasing radially outward from the stator core.

12. The electric work machine according to claim 10 , further comprising:
a plurality of coils that includes the first coil and the second coil, wherein:
the plurality of coils includes coils in three phases wound around the stator with the delta connection in which each phase includes four or more coils connected in parallel.

13. The electric work machine according to claim 12 , wherein
plurality of coils includes twelve coils in the three phases,
the twelve coils in the three phases include three continuous wires, and
each of the three continuous wires is wound into four coils adjacent to one another in the circumferential direction of the stator core, and a starting end of a first wire of the three wires and a terminal end of a second wire adjacent to each other in the circumferential direction are electrically connected to the plurality of metal sheets in the same direction.

14. The electric work machine according to claim 12 , wherein
the stator core has a groove, and
a short-circuiting member including the plurality of metal sheets includes a rib that engages the groove.

15. The electric work machine according to claim 12 , further comprising:
a sensor circuit board configured to detect rotation of the rotor,
wherein a short-circuiting member including the plurality of metal sheets holds the sensor circuit board.

16. The electric work machine according to claim 15 , wherein
the sensor circuit board is located inside the short-circuiting member.

Assignees

• Makita Corp

Inventors

• Kouda Kei
• Naito Akira
• Abe Hideki

Classifications

• H02K3/522

  for generally annular cores with salient poles · CPC title

• H02K11/33 Primary

  Drive circuits, e.g. power electronics (H02K11/38 takes precedence) · CPC title

• A01D2101/00

  Lawn-mowers · CPC title

• A01D69/02 Primary

  electric · CPC title

• A01D34/78 Primary

  electric · CPC title