Electric motor for a power tool
AssigneeMilwaukee Electric Tool Corporation
InventorsJeffrey C. Hessenberger, Michael Kolden, Andrew T. Beyerl
Life of this patent
Estimating the term…
Abstract
A power tool includes a housing, a battery connection portion supported by the housing, a drive mechanism configured to operate a working element, and a brushless DC motor positioned within the housing and connected to the drive mechanism. The motor includes a rotor, stator surrounding the motor, and an output shaft fixed to the rotor such that movement of the rotor is transmitted to the output shaft. The motor also includes a fan coupled to the output shaft to rotate with the output shaft and the rotor, and a brass bushing fixed to the output shaft to rotate with the rotor and the output shaft relative to the stator. The bushing includes a balancing feature.
Claims20
A power tool comprising:
- a housing;
- a battery connection portion supported by the housing, the battery connection portion configured to receive a battery pack;
- a drive mechanism configured to operate a working element;
- and
- a brushless DC motor positioned within the housing and connected to the drive mechanism, the brushless DC motor electrically coupled to the battery connection portion and including
- a rotor having a body, a plurality of slots formed in the body and extending between a first face and a second face of the body, and a plurality of interior permanent magnets, each interior permanent magnet positioned in a respective one of the plurality of slots,
- a stator surrounding the rotor, the stator having a plurality of electromagnetic coils and laminations surrounding the plurality of electromagnetic coils,
- an output shaft fixed to the rotor such that movement of the rotor is transmitted to the output shaft,
- a fan coupled to the output shaft to rotate with the output shaft and the rotor, and
- a brass bushing fixed to the output shaft to rotate with the rotor and the output shaft relative to the stator, the brass bushing having at least one hole of removed material on a surface of the brass bushing to help balance the motor,
- wherein the brass bushing has a smaller outer diameter than an outer diameter of the body of the rotor.
A brushless DC motor for use with a power tool, the brushless DC motor comprising:
- a rotor having a body, a plurality of slots formed in the body and extending between a first face and a second face of the body, and a plurality of interior permanent magnets, each interior permanent magnet positioned in a respective one of the plurality of slots;
- a stator surrounding the rotor, the stator having a plurality of electromagnetic coils and laminations surrounding the plurality of electromagnetic coils;
- an output shaft fixed to the rotor such that movement of the rotor is transmitted to the output shaft;
- a fan coupled to the output shaft to rotate with the output shaft and the rotor;
- and
- a brass bushing fixed to the output shaft to rotate with the rotor and the output shaft relative to the stator, the brass bushing having at least one hole of removed material on a surface of the brass bushing to help balance the motor,
- wherein the brass bushing has a smaller outer diameter than an outer diameter of the body of the rotor.
Dependencies are inferred from the claim text.