Simple brushless DC fan motor with reversing field

A DC motor comprising:

• a rotor with an annular permanent magnet defining magnetic segments oppositely polarized in the radial outward direction, wherein said segments are arranged circumferentially to comprise the magnet;
• a stator having an electromagnet structure outside said annular magnet, proximate the periphery thereof, said electromagnet structure including two electrically independent coil windings and electromagnetic flux conducting means in flux conducting relation to the coil windings and located for establishing magnetic fields of opposite polarities to attract the oppositely polarized segments of, and for applying rotational torque to, the annular magnet when the coil windings are energized;
• position detecting means located outside said annular magnet for detecting the position of the rotor relative to the stator and for commutating electrical current to a different coil winding to repeatedly produce said opposite polarity fields and attract said segments in dependence on said relative positioning;
• and
• wherein the means for commutating current includes at least a first transistor means connected in current conducting relation to a first of said windings, and at least a second transistor means in current conducting relation to the second of said windings, resistance means for establishing biases to the first and second transistor means and said position detecting means comprising a Hall device responsive to a magnetic field of the magnetic segments of one polarity for providing bias from the resistance means to the first transistor means to cause conduction therein while depriving the second transistor means of bias to prevent conduction therein, and responsive to the absence of said field for providing bias from the resistance means to the second transistor means to cause conduction therein while depriving the first transistor means of bias to prevent conduction thereof.

A DC motor comprising:

• a rotor with an annular permanent magnet defining magnetic segments oppositely polarized in the radial outward direction, wherein said segments are arranged circumferentially to comprise the magnet;
• a stator having an electromagnet structure outside said annular magnet, proximate the periphery thereof, said electromagnet structure including two electrically independent and concentrically wound coil windings, and wherein the electromagnetic structure defines at least one pole piece and wherein the coil windings are wound on a core in electromagnetic flux conducting relationship to the pole piece and located for establishing magnetic fields of opposite polarities to attract the oppositely polarized segments of, and for applying rotational torque to, the annular magnet;
• and
• position detecting means located outside said annular magnet for detecting the position of the rotor relative to the stator and for commutating electrical current to the coil means to repeatedly produce said opposite polarity fields and attract said segments in dependence on said relative positioning.

A DC motor comprising:

• a rotor with an annular permanent magnet defining magnetic segments oppositely polarized in the radial outward direction, wherein said segments are arranged circumferentially to comprise the magnet;
• a stator having an electromagnet structure outside said annular magnet, proximate the periphery thereof, said electromagnet structure including coil means comprising a core having two electrically independent coil windings wound thereon, said electromagnetic structure further including electromagnetic flux conducting means in flux conducting relation to the coils and core and located for establishing magnetic fields of opposite polarities to attract the oppositely polarized segments of, and for applying rotational torque to, the annular magnet, wherein the stator includes a housing defining a compartment at one location on the periphery of the path of rotation of the annular magnet, and wherein said coil means is located in said compartment;
• and
• position detecting means located outside said annular magnet for detecting the position of the rotor relative to the stator and for commutating electrical current to the coil means to repeatedly produce said opposite polarity fields and attract said segments in dependence on said relative positioning.

A DC motor comprising:

• a rotor with an annular permanent magnet defining magnetic segments oppositely polarized in the radial outward direction, wherein said segments are arranged circumferentially to comprise the magnet;
• a stator having an electromagnet structure outside said annular magnet and proximate the periphery thereof, and wherein the stator electromagnet structure is located in a location to one side of the annular magnet and extends less than 180.degree. around the magnet, said electromagnet structure including coil means comprising a core having two electrically independent coil windings wound thereon, said electromagnetic structure further including electromagnetic flux conducting means in flux conducting relation to the coils and core and located for establishing magnetic fields of opposite polarities to attract the oppositely polarized segments of, and for applying rotational torque to, the annular magnet;
• and
• position detecting means located outside said annular magnet for detecting the position of the rotor relative to the stator and for commutating electrical current to the coil means to repeatedly produce said opposite polarity fields and attract said segments in dependence on said relative positioning.