Abstract: An annular magnet includes a hollow magnet body having an outer circumferential surface that defines a cylindrical shape and an inner circumferential surface that defines an inlet hole. The inlet hole is adapted for receiving a back iron and has a cross-section substantially shaped in an equiangular polygon. The magnet body further has a plurality of magnetic sectors that surround a central axis of the inlet hole where the magnetic sectors correspond respectively to the sides of the equiangular polygon. Each of the magnetic sectors has a magnetic polarity opposite to that of an adjacent one of the magnetic sectors.

Abstract: A rotor includes an axle, a back iron unit, a magnet unit and an adhesive layer. The back iron unit includes annular inner and outer components, and a plurality of plastic components. The inner component is made from a non-metal material and is sleeved on the axle. The outer component is made from a magnetically permeable metal material and surrounds the inner component. The plastic components protrude from an outer surface of the outer component. The magnet unit has a cavity for receiving the back iron unit. The plastic components abut against a cavity-defining surface of the magnet unit that defines the cavity. The adhesive layer is formed in a space between the back iron unit and the magnet unit.

Abstract: A multi-phase outer-rotor-type variable frequency induction motor for a ceiling fan includes: an outer rotor disposed in a housing that includes a plurality of blade-mounting parts, and including a stator-mounting part that is surrounded by an outer rotor body which is combined with the housing, the outer rotor body being formed with a plurality of slots in which conductive elements are respectively disposed; a stator disposed in the stator-mounting part, and including a central shaft pivotally connected to the housing, a stator core extending in radial directions from the central shaft, and a winding set that is disposed to wind in winding slots formed in the stator core, and that is configured into a multi-phase winding arrangement; and a control unit operable to control frequency of a power signal fed by the control unit to the winding set.

Abstract: A rotor assembly of a brushless motor is provided herein, which contains an axle, a rotor encircling the axle coaxially, and a layered structure therebetween tightly joining the rotor and the axle together. The layered structure contains an inner cladding, a plastic member, and an outer cladding, arranged coaxially in this order around the axle. The plastic member, due to its flexibility, functions as a cushion between the rotor and the axle to absorb both the noise and the vibration of the rotor. As such, the present invention achieves a silent brushless motor without imposing any constraint on the motor's rotational speed.