| Patent application number | Description | Published |
|---|
| 20090021090 | Power Tools With Motor Having a Multi-Piece Stator - A power tool has a motor having a stator made by separately forming pole pieces, return path pieces and field coils. The field coils are placed over necks of the pole path pieces and the return path pieces are affixed to the pole pieces. An armature having an outside diameter of at least 0.625 the outside diameter of the stator is placed in the stator. The field coils may be formed so that they extend beyond pole tips of the pole pieces. | 01-22-2009 |
| 20090200891 | Electric Motor Having A Field Assembly With Slot Insulation - An electric motor has a field assembly, such as a stator, for a dynamoelectric machine has field coils that are wound to a net shape. Lead wires are brought out from the ends of each field coil. The field coils are insulated with insulating sleeves or insulating slot liners. The field coils are assembled with stator core pieces, such as pole pieces and return path pieces, into the stator. The stator core pieces are formed prior to being assembled with the field coils. In an aspect of the invention, the pole pieces and return path pieces are separately formed and then assembled together with the field coils, which have also been separately formed. | 08-13-2009 |
| 20090206783 | Soft start for electric motor of a power tool - A power tool has an electric motor with field windings. In an aspect of the invention, each field winding includes two coils wound with the same number of turns of the same gauge magnet wire. When the motor is first energized, the two coils of each field winding are connected in series, reducing in-rush current. Upon expiration of a soft start period, which can be after the motor reaches a predetermined speed or upon expiration of a predetermined time period, the two coils of each field winding are connected in parallel. In another aspect of the invention, an electric motor used in a power tool includes field windings that are connected in series with a separate start winding when the motor is first energized. Upon expiration of the soft start period, the start winding is bypassed. In another aspect of the invention, the separate start winding includes two sub-windings. The two sub-windings are connected in a way that magnetic field created by the two sub-windings is counterbalanced so that the overall magnetic force created by the start winding in the motor armature is minimized or zero. Also, the voltage across the two sub-windings is minimized or zero. In another aspect, the field windings are connected in series with a start impedance when the motor is first energized and a time delay relay having a set of delay contacts coupled across the start impedance energized. Upon expiration of the soft start period, the time delay contacts close, bypassing the start impedance. In an aspect, the motor is a universal motor. | 08-20-2009 |
| 20100033036 | Motor With Permanent Magnets and Method of Manufacturing; Power Tool With Same - An electric motor has a rotor and a stator. The rotor or the stator has arced permanent magnets that have essentially the same inner radius (IR) and outer radius (OR). In an aspect, the stator has a stator housing having a plurality of poles. Each pole includes a plurality of flat magnets affixed to an inner surface of the stator housing. In an aspect, flats on the outside of the stator housing key the stator assembly in a power tool housing. In an aspect, flat magnets are pre-magnetized, pre-assembled with alternating magnetic polarities, inserted into a stator housing, and remagnetized to a final, desired magnetic polarity configuration. In an aspect, pre-magnetized magnets and unmagnetized magnets are pre-assembled with unmagnetized magnets between magnetized magnets, the pre-assembled magnets inserted into a stator housing, and the unmagnetized magnets magnetized to a final, desired magnetic polarity configuration. In an aspect, pre-magnetized magnets are inserted between anchors inwardly extending from an inner surface of a stator housing with the anchors retaining each magnet placed in the stator housing between anchors from being angularly displaced by subsequently inserted magnets. In an aspect, pre-magnetized magnets are inserted in recesses in an inner surface of a stator housing with the recesses retaining each magnet placed in the stator housing between anchors from being angularly displaced by subsequently inserted magnets. In an aspect, each pole has at least three magnets, at least one of the magnets being thinner than the other magnets. In an aspect, the outer most magnets are made of magnetic material that is more resistant to demagnetization than at least one of the other magnets. In an aspect, the magnets of each pole are unevenly spaced over the pole In an aspect, a power tool includes such an electric motor. | 02-11-2010 |
| 20110018370 | METHOD OF FORMING A POWER TOOL - An electric motor has a stator in which an armature is disposed. The armature has a lamination stack having slots in which magnet wires are wound. An armature shaft extends coaxially through the lamination stack and a commutator is disposed on the armature shaft to which ends of the magnet wires are electrically coupled. The magnet wires are at least partially encased in thermally conductive plastic. When the thermally conductive plastic is molded, a balancing feature is formed of the thermally conductive plastic. In aspects, the balancing feature can include a layer of the plastic from which plastic can be removed during balancing; one or more balancing rings adjacent axial sides of the lamination stack from which plastic can be removed to balance the armature; or one or more balancing rings having one or more pockets therein in which one or more weights are disposed to balance the armature. | 01-27-2011 |
| 20110115314 | POWER TOOLS WITH MOTOR HAVING A MULTI-PIECE STATOR - A power tool has a motor having a stator made by separately forming pole pieces, return path pieces and field coils. The field coils are placed over necks of the pole path pieces and the return path pieces are affixed to the pole pieces. An armature having an outside diameter of at least 0.625 the outside diameter of the stator is placed in the stator. The field coils may be formed so that they extend beyond pole tips of the pole pieces. | 05-19-2011 |
| 20110278966 | Motor With Overmolded Permanent Magnets - A permanent magnet electric motor has a stator and a rotor. The stator has a stator housing with at least a North pole and a South pole. Each pole includes at least two permanent magnets arranged on an inner surface of the stator housing near the pole tips and an overmold of magnetic material molded around the permanent magnets and over the inner surface of the stator between the permanent magnets. Alternatively, an overmold of magnetic material may be provided over an inner surface of the stator, where the thickness of the overmold layer is greater near tips of each pole than in the middle portion of each pole. | 11-17-2011 |
| 20110298313 | Motor With Permanent Magnets and Method of Manufacturing Power Tool With Same - A permanent magnet electric motor has a stator and a rotor. The stator has a stator housing with at least a North pole and a South pole, each pole including permanent magnets affixed to an inner surface of the stator housing, where at least two of the magnets within a pole have dissimilar characteristics, e.g., different widths or different grades of demagnetization resistance. | 12-08-2011 |
