Black Decker Inc.

Richard H Walter

Earl M Ortt

Brandon L Verbrugge

Hung T Du

Michael Jeffrey Agnes

Ren H Wang

Allyn Boyce

Jiaqi Zhang

A cylinder/magnet assembly for a field of an electric machine, such as a stator of a brush type motor or a rotor of a brushless motor, alternator or generator, is formed by stamping a blank to form anchors extending upwardly from a surface of the blank and stamping holes in the blank where first and second portions of the anchors meet an inner surface of the cylinder to facilitate rolling of the cylinder from the blank. After a cylinder is rolled from the blank, pre-formed magnets are placed around an inner surface of the cylinder and plastic molded around the magnets and anchors to secure the magnets to the cylinder. In an aspect of the invention, the holes act as magnetic chokes. In another aspect of the invention, the anchors are formed as flux spreaders. In another aspect of the invention, the north and south poles of a cylinder and magnet assembly have unequal distribution angles. In another aspect of the invention, the north and south poles of a cylinder and magnet assembly have unequal numbers of magnets. In another aspect of the invention, flux spreaders are disposed on inner surfaces of the magnets of each pole of a cylinder and magnet assembly. In another aspect of the invention, the foregoing aspects are used in a stator of a motor. In another aspect of the invention, such a stator is used in a power tool.

Field assembly for a motor and method of making same

A stator of an electric motor is formed by inserting pre-formed magnets on a cylinder having anchors and plastic is molded around the magnets and anchors to secure the magnets to a surface of the cylinder, forming a cylinder/magnet assembly. A pilot feature is formed in at least one endwall of the plastic molding when it is molded. An end plate is located with respect to the cylinder/magnet assembly by mating a corresponding pilot feature of the end plate with the pilot feature in the endwall of the plastic molding. In another aspect of the invention, magnets are inserted into magnet receiving pockets of a cylinder and plastic molded therearound with the magnet pockets holding the magnets in place during molding of the plastic. In another aspect of the invention, the north and south poles of a cylinder and magnet assembly have unequal distribution angles. In another aspect of the invention, the north and south poles of a cylinder and magnet assembly have unequal numbers of magnets. In another aspect of the invention, the anchors are also formed as flux spreaders. In another aspect of the invention, the stator is used in a power tool.

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Baldwin, MD, United States of America

Richard H Walter