Brushless direct current motor

Claim 2

A direct current brushless motor comprising a rotor shaft, a pair of spaced substantially radially extending yokes mounted on said shaft for rotation therewith; a plurality of pairs of permanent magnets circumferentially arranged about said shaft between said yokes, one of each of said pairs of permanent magnets being mounted on each of said yokes with a gap therebetween; a plurality of air core driving coils disposed in nonoverlapping relation in the gap between said pairs of permanent magnets; driving circuit means coupled to said driving coils for applying a driving current thereto when actuated; and a detecting means responsive to the position of said rotor shaft and having at least one detecting coil means associated with each driving coil and coupled to said driving circuit means for the activation thereof to apply a driving current to the respective driving coil to rotate said rotor shaft, said detecting means including a shield ring formed from a conducting material, said detecting coil means being juxtaposed to said shield ring, said shield ring having cutaway portions in the path of said detecting coil means to permit the operation of each detecting coil means when said cutaway portions are aligned therewith for the application of driving current to the driving coil associated with said detecting coil means.

Claim 3

A direct current brushless motor as recited in claim 1, wherein two of said pairs of permanent magnets and one detecting coil are provided for each of said driving coils.

Claim 4

A direct current brushless motor comprising a rotor shaft, a pair of spaced substantially radially extending yokes mounted on said shaft for rotation therewith, a plurality of pairs of permanent magnets circumferentially arranged about said shaft between said yokes, one of each of said pairs of permanent magnets being mounted on each of said yokes with a gap therebetween; a plurality of air core driving coils disposed in nonoverlapping relation in the gap between said pairs of permanent magnets; driving circuit means coupled to said driving coils for application of drivIng current thereto when actuated; and a detecting means responsive to the position of said rotor shaft and having at least one detecting coil associated with each driving coil and coupled to said driving circuit means for the activation thereof to apply a driving current to the respective driving coil to rotate said rotor shaft, the driving coils activated at each position of said rotor shaft being disposed in the gap defined by selected pairs of permanent magnets, the position and polarity of said pairs of permanent magnets being selected to produce a force on said rotor shaft in a predetermined direction when portions of an activated driving coil are disposed in the respective gaps therebetween, the poles of adjacent permanent magnets on each of said yokes being of different polarity, said driving coils having at least two sides, one of said sides being disposed in the gap defined by each of two adjacent pairs of permanent magnets selected to produce a force on said rotor shaft in a predetermined direction, at least when said driving coils are activated in response to said detecting coils.

Claim 5

A direct current brushless motor comprising a rotor shaft, a pair of spaced substantially radially extending yokes mounted on said shaft for rotation therewith, a plurality of pairs of permanent magnets circumferentially arranged about said shaft between said yokes, one of each of said pairs of permanent magnets being mounted on each of said yokes with a gap therebetween; a plurality of air core driving coils disposed in nonoverlapping relation in the gap between said pairs of permanent magnets; driving circuit means coupled to said driving coils for application of drivIng current thereto when actuated; and a detecting means responsive to the position of said rotor shaft and having at least one detecting coil associated with each driving coil and coupled to said driving circuit means for the activation thereof to apply a driving current to the respective driving coil to rotate said rotor shaft, the driving coils activated at each position of said rotor shaft being disposed in the gap defined by selected pairs of permanent magnets, the position and polarity of said pairs of permanent magnets being selected to produce a force on said rotor shaft in a predetermined direction when portions of an activated driving coil are disposed in the respective gaps therebetween, the poles of adjacent permanent magnets on each of said yokes being of different polarity, said driving coils having at least two sides, one of said sides being disposed in the gap defined by each of two adjacent pairs of permanent magnets selected to produce a force on said rotor shaft in a predetermined direction, at least when said driving coils are activated in response to said detecting coils.

Claim 6

A direct current brushless motor as recited in claim 3, wherein said detecting means includes a shield ring formed from a conducting material, said detecting coil means being juxtaposed to said shield ring, said shield ring having cutaway portions in the path of said detecting coils to permit the operation of each detecting coil when said cutaway portions are aligned therewith for the application of driving current to the driving coil associated with said detecting coil, said cutaway portions and detector coils being positioned for the selective application of driving current to said driving coils whereby said motor is self starting in a predetermined direction.