DC Motor

Claim 2

A DC motor comprising: a stator; a rotor adapted to rotate about an axis with respect to said stator; at least two windings included in one of said stator and rotor; flux generating means included in the other of said stator and rotors and providing a magnetic field which is of substantially constant strength regardless of the rotational position of said rotor; means for producing first and second drive signals proportional to sin 2 θ and cos 2 θ, respectively, where θ is an angle corresponding to said rotational position of said rotor; and means for energizing said at least two windings in response to said first and second drive signals, respectively, with the direction of current through said at least two windings being alternated in correspondence with the rotational position of said rotor so as to rotate said rotor about said axis.

Claim 3

A DC motor according to claim 1; in which said flux generating means includes at least one pair of permanent magnet poles of opposite polarity and each providing substantially no magnetic flux variation over the respective angular extent, and in which each said winding includes at least one coil.

Claim 4

A DC motor according to claim 2; in which said DC motor is of the commutator type wherein said stator includes said at least one pair of permanent magnet poles and said rotor includes said at least two windings.

Claim 5

A DC motor according to claim 3; in which said means for energizing includes commutator means connected to said at least two windings and brush means adapted to contact said commutator means for supplying said drive signals to said commutator means whereby the direction of current through said at least two windings is alternated in correspondence with the rotational position of said rotor.

Claim 6

A DC motor according to claim 4; in which said commutator means includes a plurality of commutator sections equal in number to the number of windings, each commutator section including a plurality of commutator pieces adapted to rotate about said axis with said rotor, and said brush means includes a plurality of pairs of brush members equal in number to the number of commutator sections, each mounted on said stator in contact with the commutator pieces of a respective one of said commutator sections, whereby each of said pairs of brushes perodically contacts respective ones of said commutator pieces as said commutator pieces rotate about said axis so as to alternate the direction of said current through said at least two windings in correspondence with the rotational position of said rotor.

Claim 7

A DC motor according to claim 5; in which the number of commutator pieces of each commutator section is equal to the number of permanent magnet poles, and one brush member of each pair is connected to said means for producing drive signals and the other brush member of each pair is connected to a reference potential.

Claim 8

A DC motor according to claim 2; in which said means for producing drive signals includes position magnet means mounted on one of said stator and rotor for generating a magnetic flux corresponding to the rotational position of said rotor relative to said stator, and magnetic reluctance means mounted on the other of said stator and rotor for producing a control signal proportional to sin 2 θin response to said generated magnetic flux.

Claim 9

A DC motor according to claim 7; in which said position magnet means is mounted with said at least one pair of permanent magnet poles on one of said stator and rotor, said position magnet means including a plurality of permanent magnet poles of equal number and polarity to that of the poles of said at least one pair of permanent magnet poles, wherein the magnetic flux generated by said position magnet means is of a sinusoidal waveform.

Claim 10

A DC motor according to claim 7; in which said means for producing drive signals includes first amplifier means for producing said drive signal proportional to sin 2 θ in response to said control signal and second amplifier means for producing said drive signal proportional to cos 2 θ in response to said control signal.

Claim 11

A DC motor comprising: a stator; a rotor adapted to rotate about an axis with respect to said stator; at least two windings included in one of said stator and rotor, each said winding including at least one coil; flux generating means included in the other of said stator and rotor and including at least one pair of permanent magnet poles of opposite polarity; means for for producing drive signals proportional to sin 2 θ and cos 2 θ, respectively, where θ is an angle corresponding to the rotational position of said rotor, said means for producing drive signals including position magnet means mounted on one of said stator and rotor for generating a magnetic flux corresponding to the rotational position of said rotor relative to said stator, magnetic reluctance means mounted on the other of said stator and rotor for producing a control signal proportional to sin 2 θ in response to said generated magnetic flux, first amplifier means including a first amplifier for producing said drive signal proportional to sin 2 θ in response to said control signal, and second amplifier means including means for producing a reference signal, means for inverting said control signal and a second amplifier for producing said drive signal proportional to cos 2 θ in response to said inverted control signal and said reference signal; and means for energizing said at least two windings in response to said drive signals with the direction of current through said at least two windings being alternated in correspondence with the rotational position of said rotor so as to rotate said rotor about said axis.

Claim 12

A DC motor comprising: a stator; a rotor adapted to rotate about an axis with respect to said stator; at least two windings included in one of said stator and rotor, each said winding including at least one coil; flux generating means included in the other of said stator and rotor and including at least one pair of permanent magnet poles of opposite polarity; means for for producing drive signals proportional to sin 2 θ and cos 2 θ, respectively, where θ is an angle corresponding to the rotational position of said rotor, said means for producing drive signals including position magnet means mounted on one of said stator and rotor for generating a magnetic flux corresponding to the rotational position of said rotor relative to said stator, magnetic reluctance means mounted on the other of said stator and rotor for producing a control signal proportional to sin 2 θ in response to said generated magnetic flux, first amplifier means including a first amplifier for producing said drive signal proportional to sin 2 θ in response to said control signal, and second amplifier means including means for producing a reference signal, means for inverting said control signal and a second amplifier for producing said drive signal proportional to cos 2 θ in response to said inverted control signal and said reference signal; and means for energizing said at least two windings in response to said drive signals with the direction of current through said at least two windings being alternated in correspondence with the rotational position of said rotor so as to rotate said rotor about said axis.

Claim 13

A DC motor according to claim 2; in which said means for energizing includes switch means for alternating the direction of current through said at least two windings and switch control means for controlling said switch means to alternate the direction of current through said at least two windings in correspondence with the rotational position of said rotor.

Claim 14

A DC motor according to claim 11; in which said switch means includes first and second switches, each having first and second output terminals and an input terminal alternately connected with said output terminals, the input terminal of said first switch being supplied with said drive signal proportional to sin 2 θ and the input terminal of said second switch being supplied with said drive signal proportional to cos 2 θ, and first and second control paths for supplying an energizing current in one direction to first and second windings of said at least two windings, respectively, in response to said drive signals proportional to sin 2 θ and cos 2 θ, respectively, and third and fourth control paths for supplying an energizing current in the opposite direction to said first and second windings, respectively, in response to said drive signals proportional to sin 2 θ and cos 2 θ, respectively.

Claim 15

A DC motor according to claim 12; in which each of said control paths includes a pair of transistors each having a collector-emitter path, the collector-emitter path of one transistor of each pair being connected between one end of one of said at least two windings and a first reference potential and the collector-emitter path of the other transistor of each pair being connected between the other end of said one of said at least two windings and a second reference potential, the collector-emitter path of said one transistor of each pair of transistors included in said first and third control paths being connected to opposite ends of said first winding and the collector-emitter path of said one transistor of each pair of transistors included in said second and fourth control paths being connected to opposite ends of said second winding.

Claim 16

A DC motor according to claim 12; in which both transistors of the pairs thereof included in said first and third control paths, respectively, are adapted to be turned ON in response to said drive signal proportional to sin 2 θ from said first and second output terminals of said first switch, respectively, and both transistors of the pairs thereof included in said second and fourth control paths, respectively, are adapted to be turned ON in response to said drive current proportional to cos 2 θ from said first and second output terminals of said second switch, respectively.

Claim 17

A DC motor according to claim 12; in which said switch means further includes switch control means for alternately connecting said input terminal of each of said switches to said respective output terminals in correspondence with the rotational position of said rotor.

Claim 18

A DC motor according to claim 15; in which said switch control means includes at least two Hall-effect elements mounted on one of said stator and rotor and separated thereon by an electrical angle corresponding to the electrical angle separation of said at least two windings for producing switch control signals corresponding to the rotational position of the rotor relative to the stator, and wherein said switch control signals actuate said first and second switches to alternate the direction of current flow through said first and second windings.

Claim 19

A DC motor according to claim 2; in which said DC motor is of the brushless type with said stator including said at least two windings and said rotor including said at least one permanent magnet.

Claim 20

A DC motor according to claim 2; in which the direction of current through said windings is alternated at rotational positions of said rotor when said drive signals are substantially equal to zero.

Claim 21

A DC motor according to claim 2; in which said at least two windings are comprised of first and second windings separated by an electrical angle of 90° with said first winding being energized in response to said drive signal proportional to sin 2 θ and said second winding being energized in response to said drive signal proportional to cos 2 θ.