초록 ▼

To reduce a unidirectional leakage flux emanating from a two-filament, pulse-energized motor, the stator (21, 22) is constructed at least as a four-pole stator and each filament (40, 41) of the windings (45; 74, 75, 78, 79) associated with respective stator poles is wound on the stator core elements

To reduce a unidirectional leakage flux emanating from a two-filament, pulse-energized motor, the stator (21, 22) is constructed at least as a four-pole stator and each filament (40, 41) of the windings (45; 74, 75, 78, 79) associated with respective stator poles is wound on the stator core elements (21) such that the number of North poles and South poles arising at the circumference of the core elements, upon energization by a current source (48, 49) of the respective filaments, will be identical, and the sum of the magnetic flux due to the energization of the respective filament arising, for example, at the center or shaft of the motor, will be essential zero, so that the effect of unidirectional, pulsating leakage flux upon a galvano-magnetic sensor (16) or other magnetic apparatus, e.g. magnetic tape transducing devices, will be essentially eliminated.

대표청구항 ▼

1. Brushless d-c cylindrical air gap motor (12) having a permanent magnet rotor (13, 14); a stator (22); two-filamant winding means (40, 41) on said stator; core elements (21) for said winding means and having part-circumferentially extending stator pole shoes (23) leaving gaps (24) between th

1. Brushless d-c cylindrical air gap motor (12) having a permanent magnet rotor (13, 14); a stator (22); two-filamant winding means (40, 41) on said stator; core elements (21) for said winding means and having part-circumferentially extending stator pole shoes (23) leaving gaps (24) between the ends of adjacent pole shoes, said winding means being adapted to be selectively energized by a controllable current source (48, 49, 47, 54); a galvano-magnetic sensor (16) responsive to the magnetic field from the rotor and providing output signals representative of the position thereof to control said controllable current source to energize the respective winding means of the core elements; wherein, in accordance with the invention, the stator (22) is at least a four-pole stator; each filament (40, 41) of the winding means (45; 74, 75; 78, 79) associated with respective stator poles being so wound on the stator core elements and so energized that the number of North poles and South poles arising at the circumference of the core elements upon simultaneous energization of the respective filament is identical and the sum of magnetic flux at the circumference of said core elements--as it faces said air-gap--due to said energization of the respective filament is essentially zero, whereby unidirectional leakage flux from the motor and acting on the galvano-magnetic sensor is substantially reduced or eliminated, further including a flux concentrating flux guide element (60) in flux linkage relation to the galvano-magnetic sensor, said flux concentration element having an extension portion (63) extending in the direction of rotation (26) of the motor for preferred capture of stray magnetic flux (B S1 ) of the stator pole (23 II ) subsequent--in the direction of rotation--to the sensor (16). 2. In a brushless d.c. cylindrical-air-gap motor, in combination, a permanent-magnet rotor having at least four rotor poles; a stator having at least four stator poles and including a winding system; the winding system comprising at least one phase winding which comprises a plurality of stator coils located at said stator poles electrically connected together for simultaneous energization and simultaneous deenergization, all the stator coils of the motor being so located that the angular spacing between the midpoints of any two angularly spaced stator coils is substantially equal to 180 electrical degrees times an integer, an integer being any whole number including one, the respective stator coils of each such phase winding being so located that, upon energization of the phase winding, the stray flux emanating from half of the stator coils of the phase winding cancels to a substantial degree the stray flux emanating from the other half of the stator coils of the phase winding at a generally radially extending region of reduced total stray stator flux located approximately midway between two adjoining stator poles; and a magnetic-flux-sensitive semiconductor element which is located at a sensing location close to the path of movement of the rotor poles, whereby to sense the passage of successive rotor poles and produce a rotor-position signal useful for commutating the winding system, said sensing position of said magnetic-flux-sensitive element furthermore being located within said generally radially extending region, whereby said magnetic-flux-sensitive element is to a reduced degree influenced by the stray flux emanating from the various stator poles during operation of the motor. 3. A motor as defined in claim 2, all the stator coils of the winding system being so arranged that no stator coil overlaps an adjoining stator coil, the spacing from the midpoint of one stator coil to the midpoint of the adjoining stator coil being always 180 electrical degrees. 4. A motor as defined in claim 3, the winding system comprising a total of two such phase windings, the number of stator coils in one of the two phase windings being equal to the number of stator coils in the other of the two phase windings, each stator coil of one phase winding being located spatially coincident with one respective stator coil of the other phase winding. 5. A motor as defined in claim 4, the stator coils of one phase winding being connected together in series, and the stator coils of the other phase winding being connected together in series. 6. A motor as defined in claim 5, each pair of spatially coincident stator coils being constituted by a bifilar-wound pair of conductors. 7. A motor as defined in claim 4, each pair of spatially coincident stator coils being constituted by a bifilar-wound pair of conductors. 8. A motor as defined in claim 4, the number of pairs of spatially coincident stator coils being equal to the number of stator poles, the respective stator coils of each phase winding being of alternate successive polarity, such that when one phase winding is in energized condition its constituent stator coils are, in spatial succession, of north magnetic orientation, the next one of south magnetic orientation, the third one of north magnetic orientation, and so forth. 9. A motor as defined in claim 2, the magnetic-flux-sensitive element being so located within said generally radially extending region that during energization of said winding system the sum of the stator fluxes emanating from the energized stator poles and incident upon said element is essentially zero. 10. A motor as defined in claim 2, said stator being of the type designed to present to said rotor poles a magnetic reluctance which varies in dependence upon the angular position of the rotor, whereby the motor produces during rotor rotation a reluctance torque whose magnitude and direction are such a function of the angular position of the rotor as to supplement the electromagnetically generated torque produced when the stator coils are energized. 11. A motor as defined in claim 10, said stator having a peripheral surface facing the rotor which is of varying radius. 12. A motor as defined in claim 11, said stator having a peripheral surface facing the rotor which is of continuously varying radius. 13. A motor as defined in claim 10, the rotor poles having surfaces which face the peripheral surface of the stator and which are of constant radius. 14. A motor as defined in claim 10, each rotor pole exhibiting a trapezoidal magnetization pattern. 15. A motor as defined in claim 2, the rotor being an external rotor and the stator being an internal stator. 16. In a brushless d.c. cylindrical-air-gap motor, in combination, a permanent-magnet external rotor having a total of four rotor poles; an internal stator having a total of four salient poles consisting in succession of a first, a second, a third and a fourth stator pole, each stator pole being of generally T-shaped outline and comprising a radially outer pole shoe portion facing towards the rotor poles and extending in the circumferential direction for an angular span approximately the same as the angular span of a rotor pole and also comprising a radially inward stem portion around which a stator coil can be wound, the stator being of the type designed to present to the rotor poles a magnetic reluctance which varies in dependence upon the angular position of the rotor, producing during rotor rotation a reluctance torque whose magnitude and direction are a function of the angular position of the rotor such as to supplement the electromagnetically generated torque that can be produced upon energization of the stator poles; a winding system on the stator consisting of a first phase winding and a second phase winding, each phase winding consisting of four stator coils electrically connected together for simultaneous energization and simultaneous deenergization, the four stator coils of each phase winding being each wound around the stem portion of a respective one of the four stator poles, each of the two phase windings having a respective first terminal and a respective second terminal, the first terminals of the two phase windings being connected together to form a common terminal, so that if current flows through said common terminal in a predetermined direction and also through said first phase winding the latter will assume its energized state, and if current flows through said common terminal in said predetermined direction and also through said second phase winding the latter will assume its energized state, the four stator coils of the first phase winding having alternate winding directions, such that if the first phase winding assumes said energized state thereof the coils of this phase winding magnetize the first and third stator poles with north polarity and the second and fourth stator poles with south polarity, the four stator coils of the second phase winding having alternate winding directions, such that if the second phase winding assumes said energized state thereof the coils of this phase winding magnetize the first and third stator poles with south polarity and the second and fourth stator poles with north polarity, the two stator coils on each stator pole, one belonging to the first and the other to the second phase winding, being constituted by a bifilar-wound pair of conductors, the four stator coils of each phase winding, because located and of the winding directions defined above, having the effect that, when the respective phase winding assumes said energized state thereof, the stray flux attributable to the stator coils of this phase winding on the first and second stator poles cancels to a substantial degree the stray flux emanating from the stator coils of the same phase winding on the third and fourth stator poles at a generally radially extending region of reduced total stray stator flux located approximately midway between the first and fourth stator poles; and a magnetic-flux-sensitive semiconductor element which is located at a sensing position close to the path of movement of the rotor poles, whereby to sense the passage of successive rotor poles and produce a rotor-position signal useful for commutating the winding system, said sensing position of said magnetic-flux-sensitive element furthermore being located within said generally radially extending region, whereby said magnetic-flux-sensitive element is to a reduced degree influenced by the stray flux attributable to the various stator coils during operation of the motor. 17. A motor as defined in claim 16, the stator coils of one phase winding being connected together in series, the stator coils of the other phase winding being connected together in series. 18. A motor as defined in claim 16, the magnetic-flux-sensitive element being so located within said generally radially extending region that during energization of said winding system the sum of the fluxes emanating from the stator and incident upon said element is essentially zero. 19. A motor as defined in claim 16, the stator having a peripheral surface facing the rotor which is of varying radius. 20. A motor as defined in claim 16, the peripheral surface of the stator being of continuously varying radius. 21. A motor as defined in claim 16, the rotor poles having surfaces which face the peripheral surface of the stator and which are of constant radius. 22. A motor as defined in claim 16, wherein the rotor poles each exhibit trapezoidal magnetization pattern.