DC Brushless motor
First Claim
1. In a DC brushless motor including a permanent magnet rotor assembly, a stator assembly having stator coils arranged in the magnetic field generated by said permanent magnet rotor assembly, and means for controlling energization of said stator coils so as to impart a rotational torque to said rotor assembly;
- said rotor assembly comprising a plurality of flat permanent magnets each having a flat side facing said stator coils across an air gap free of magnetic material and rotor yoke means having a substantially polygonal cross-section and a plurality of flat side walls to which said flat permanent magnets are attached and providing a path for magnetic flux emanating from the side of said magnets remote from said stator coils whereby said plurality of magnets forms an array thereof which is substantially a regular polygon in cross-section.
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Accused Products
Abstract
In a DC brushless motor including a rotor assembly having permanent magnets and a stator assembly having coils arranged in the magnetic field generated by the permanent magnets of the rotor assembly, with the energization of the coils being controlled so as to impart a rotational torque to the rotor assembly; the permanent magnets of the rotor assembly are flat and are attached to a rotor yoke, which can be constructed as an octagonal prism, to provide a path for the magnetic flux emanating from the magnets and to support the flat magnets so that the latter form substantially a regular polygon in cross section. The magnets can be arranged with their poles in a north-south-north-south sequence against flat side walls of the rotor yoke to provide a flux density pattern that is substantially sinusoidal. Alternatively, the flat magnets can be arranged so that magnets of like polarization are disposed on either side of selected corners of a polygonal rotor yoke, thereby providing a flux density pattern that is substantially trapezoidal or rectangular.
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Citations
20 Claims
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1. In a DC brushless motor including a permanent magnet rotor assembly, a stator assembly having stator coils arranged in the magnetic field generated by said permanent magnet rotor assembly, and means for controlling energization of said stator coils so as to impart a rotational torque to said rotor assembly;
- said rotor assembly comprising a plurality of flat permanent magnets each having a flat side facing said stator coils across an air gap free of magnetic material and rotor yoke means having a substantially polygonal cross-section and a plurality of flat side walls to which said flat permanent magnets are attached and providing a path for magnetic flux emanating from the side of said magnets remote from said stator coils whereby said plurality of magnets forms an array thereof which is substantially a regular polygon in cross-section.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
Specification