US 12,081,067 B2
Electric motor
Andrew T. Beyerl, Pewaukee, WI (US); Keith Boulanger, Kenosha, WI (US); Ryan B. Jipp, Brookfield, WI (US); Timothy R. Obermann, Waukesha, WI (US); and Matthew R. Bailey, Racine, WI (US)
Assigned to MILWAUKEE ELECTRIC TOOL CORPORATION, Brookfield, WI (US)
Appl. No. 17/052,456
Filed by MILWAUKEE ELECTRIC TOOL CORPORATION, Brookfield, WI (US)
PCT Filed Jun. 2, 2020, PCT No. PCT/US2020/035633
§ 371(c)(1), (2) Date Nov. 2, 2020,
PCT Pub. No. WO2020/247326, PCT Pub. Date Dec. 10, 2020.
Claims priority of provisional application 62/870,125, filed on Jul. 3, 2019.
Claims priority of provisional application 62/857,337, filed on Jun. 5, 2019.
Prior Publication US 2023/0155430 A1, May 18, 2023
Int. Cl. H02K 1/14 (2006.01); H02K 3/34 (2006.01); H02K 3/52 (2006.01)
CPC H02K 1/148 (2013.01) [H02K 3/345 (2013.01); H02K 3/522 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A power tool comprising:
an output member,
a brushless, direct current electric motor having a rotor configured to provide torque to the output member, the brushless, direct current electric motor including a stator, the stator including
a first stator segment including
a first annular back portion,
a first tooth extending radially inward from the first annular back portion,
a first flange extending away from the first tooth,
a first insulation portion including
a first back insulation portion covering the first annular back portion,
a first tooth portion covering the first tooth, and
a first flange portion covering the first flange, the first flange portion having a first face that is in facing relationship with the first back insulation portion, and
a first coil wound around the first tooth,
a second stator segment separate from the first stator segment and axially coupled to the first stator segment, the second stator segment including
a second annular back portion,
a second tooth extending radially inward from the second annular back portion,
a second flange extending away from the second tooth and toward the first flange,
a second insulation portion including
a second back insulation portion covering the second annular back portion,
a second tooth portion covering the second tooth, and
a second flange portion covering the second flange, the second flange portion having a second face that is in facing relationship with the second back insulation portion, and
a second coil wound around the second tooth;
a battery configured to provide power to the brushless, direct current electric motor; and
a motor drive circuit configured to control operation of the brushless, direct current electric motor;
wherein the first face and the second face together substantially define a boundary plane, such that a cross-sectional slot area is defined between the first back insulation portion, the second back insulation portion, the first tooth portion, the second tooth portion, and the boundary plane;
wherein the first coil and the second coil comprise a plurality of conductive wires arranged between the first and second teeth, the plurality of conductive wires defining a cross-sectional winding area within the cross-sectional slot area;
wherein a ratio of the cross-sectional winding area to the cross-sectional slot area is greater than or equal to 0.45; and
wherein when the brushless, direct current electric motor continuously draws 40 Amps of current from the battery, a time to one of the brushless, direct current electric motor and the motor drive circuit reaching a critical temperature is greater than or equal to 511 seconds.