Abstract: The flux densities formed by plural electromagnet poles M1 to M12 which are arranged at a predetermined interval in a circumferential direction of a rotary body 1 at the same position in an axial direction of the rotary body 1 are gradually changed in the circumferential direction of the rotary body. Even if there is a difference between the maximum value of the flux density and the minimum value, the change of the flux densities between the adjacent electromagnet poles is small and smooth. Accordingly satisfactory detective sensitivity and detection results can be obtained.

Abstract: A permanent magnet embedded motor including a rotor which is provided with a plurality of slits and a plurality of permanent magnets embedded into the slits and a stator which is provided with an iron core having a plurality of slots to which a coil is wound and is arranged to face the rotor via a gap. The slit includes a permanent magnet embedded part into which the permanent magnet is embedded in a direction perpendicular to the radial direction of the rotor and an “L”-shaped air gap part integrally provided on both ends of the permanent magnet embedded part. An angle “&thgr;1” for one pole of the rotor and an angle “&thgr;2” of the “L”-shaped air gap part are set to be 0.1≦&thgr;2/&thgr;1≦0.3. Further, a radius “R” of a circumscribed circle of the rotor and a radius “R1” for forming an outer peripheral face of the rotor at a portion of the “L”-shaped air gap part are preferably set to be 0.1≦(R−R1)/R≦0.3.

Abstract: The flux densities formed by plural electromagnet poles M1 to M12 which are arranged at a predetermined interval in a circumferential direction of a rotary body 1 at the same position in an axial direction of the rotary body 1 are gradually changed in the circumferential direction of the rotary body. Even if there is a difference between the maximum value of the flux density and the minimum value, the change of the flux densities between the adjacent electromagnet poles is small and smooth. Accordingly satisfactory detective sensitivity and detection results can be obtained.

Abstract: A magnetic levitation motor which rotates a rotor in a levitated state with respect to a stator by a direct-current magnetic field and stator windings. The magnetic levitation motor comprises: a direct-current magnetic field generating device (4) which forms a magnetic flux having a radial pattern with an axis at the center in a stator (2) and a rotor (3); a first stator winding (6) for generating a levitation control magnetic flux (5) to control levitation of the rotor (3) in a radial direction; and a second stator winding (7) for generating a rotating magnetic field to rotate the rotor (3). The rotor (3) is provided with a yoke portion (9) and a motor magnet (10) which are opposed to a stator core (8) of the stator (2). A part of a bias magnetic flux (11) and a part of a levitation control magnetic flux (5) form a magnetic circuit directly reaching the stator core from the yoke, thereby increasing a levitation force of the rotor.

Abstract: A magnetic levitation motor has a rotor with a rotor magnet magnetized in multiple poles, and a stator with rotor driving coils disposed confronting to the rotor magnet for generating a rotational torque on the rotor, and bearing coils for generating a bearing force in a direction perpendicular to a rotational axis of the rotor. The rotor driving coils and the bearing coils are shifted with respect to one another in a circumferential direction to avoid overlapping with one another. A displacement sensor is provided for detecting displacement of the rotor with respect to a plane that is perpendicular to the rotational axis of the rotor, wherein the rotor is rotated by the rotor driving coils, and the currents flowing in the bearing coils are controlled in accordance with output of the displacement sensor to keep the rotational axis of the rotor at a predetermined position.

Abstract: A magnetic levitation motor has a rotator body formed from a magnetic member and having segmented permanent magnets attached to a peripheral surface thereof. Two magnetic levitation motor sections are disposed in an axial direction of the rotator body. Each of the magnetic levitation motor sections having a first stator winding that generates a levitation control magnetic flux for levitating the rotator body and a second stator winding that generates a rotation magnetic flux for rotating the rotator body. The segmented permanent magnets are affixed to the rotator body at the two magnetic levitation motor sections with magnetic polarities thereof mutually opposite to each other. The segmented permanent magnets function as bias magnets that generate a direct-current magnetic flux that radially spreads from within the rotor.

Abstract: A rotor includes four magnetic poles provided in a rotational direction at intervals of 90 degrees. A stator includes a winding group for rotation and a winding group for levitation. Each of the winding groups has concentrated windings spaced at intervals of 30 degrees in a rotational direction to provide induction conductive winding sections at twelve locations. Each two of the induction conductive winding sections spaced at an interval of 90 degrees among the twelve induction conductive winding sections are connected to form one winding set such that six winding sets are formed in total in each of the winding groups. Current for rotation and current for levitation are conducted through the six winding sets in the windings for rotation and levitation to perform rotation and levitation controls of the rotor.

Abstract: A magnetically levitating motor includes a rotor that is formed from a magnetic material and has a permanent magnet attached along a circumference thereof, and a stator core section having a first stator coil that generates a levitation control magnetic flux that controls levitation of the rotor in a radial direction and a second coil that generates rotational magnetic flux against the rotor. In one aspect of the present invention, a rotor side thrust bearing magnetic path section is formed on the rotor, and a stator side thrust bearing magnetic path section that is disposed opposite in the radial direction to the rotor side thrust bearing magnetic path section is provided on the stator. A bias magnetic flux that forms the radial levitation control magnetic flux is formed to pass a gap in the radial direction between the rotor side thrust bearing magnetic path section and the stator side thrust bearing magnetic path section.

Abstract: A bearing apparatus includes a rotator body, a non-rotation body rotatably supporting the rotator body, and a lubrication fluid provided between the rotator body and the non-rotation body in which the rotator body is supported in a thrust direction by a thrust dynamic pressure bearing formed between the rotator body and the non-rotation body. The bearing apparatus includes an active magnetic bearing formed by a driving coil disposed on one of the rotator body and the non-rotation body and a magnet disposed on the other thereof, and a gap sensor that detects an axial direction gap between the rotator body and the non-rotation body. The thrust dynamic pressure bearing and the active magnetic bearing are combined such that the static rigidity of the bearing apparatus is born by the active magnetic bearing and the dynamic rigidity is born by the dynamic pressure bearing.

Abstract: A magnetic levitation motor has a rotor with a rotor magnet magnetized in multiple poles, and a stator with rotor driving coils disposed confronting to the rotor magnet for generating a rotational torque on the rotor, and bearing coils for generating a bearing force in a direction perpendicular to a rotational axis of the rotor. The rotor driving coils and the bearing coils are shifted with respect to one another in a circumferential direction to avoid overlapping with one another. A displacement sensor is provided for detecting displacement of the rotor with respect to a plane that is perpendicular to the rotational axis of the rotor, wherein the rotor is rotated by the rotor driving coils, and the currents flowing in the bearing coils are controlled in accordance with output of the displacement sensor to keep the rotational axis of the rotor at a predetermined position.

Abstract: A rotor includes four magnetic poles provided in a rotational direction at intervals of 90 degrees. A stator includes a winding group for rotation and a winding group for levitation. Each of the winding groups has concentrated windings spaced at intervals of 30 degrees in a rotational direction to provide induction conductive winding sections at twelve locations. Each two of the induction conductive winding sections spaced at an interval of 90 degrees among the twelve induction conductive winding sections are connected to form one winding set such that six winding sets are formed in total in each of the winding groups. Current for rotation and current for levitation are conducted through the six winding sets in the windings for rotation and levitation to perform rotation and levitation controls of the rotor.

Abstract: A bearing apparatus includes a rotator body, a non-rotation body rotatably supporting the rotator body, and a lubrication fluid provided between the rotator body and the non-rotation body in which the rotator body is supported in a thrust direction by a thrust dynamic pressure bearing formed between the rotator body and the non-rotation body. The bearing apparatus includes an active magnetic bearing formed by a driving coil disposed on one of the rotator body and the non-rotation body and a magnet disposed on the other thereof, and a gap sensor that detects an axial direction gap between the rotator body and the non-rotation body. The thrust dynamic pressure bearing and the active magnetic bearing are combined such that the static rigidity of the bearing apparatus is born by the active magnetic bearing and the dynamic rigidity is born by the dynamic pressure bearing.

Abstract: A rotor includes a rotor magnet magnetized to have a multiple of magnetic poles. A stator, while confronting with the rotor, includes a rotor driving coil set for generating a rotational torque in the rotor, and a bearing coil set for generating a bearing force having a direction perpendicular to the rotational axis direction of the rotor. The number of magnetic poles of the rotor magnet is eight. The number of coils of the bearing coil set of the stator is six. Displacement sensor is provided for detecting a displacement of the rotor, in a direction perpendicular to the rotational axis of the rotor. The rotor is rotated by the rotor driving coil set. Currents flowing in the bearing coils are controlled in accordance with output of the displacement sensor to hold the rotational axis of the rotor at a predetermined position.

Abstract: A magnetic levitation motor includes a rotor and a stator disposed opposite to the rotor. The rotor has a main body formed from a magnetic member and a permanent magnet attached to a peripheral surface of the main body. The stator has a first stator winding that generates a levitation control magnetic flux for controllably levitating the rotator body, a second stator winding that generates a rotation magnetic flux for rotating the rotator body and a stator core having the first stator winding and the second stator winding. A direct current magnetic field generation device is provided to generate a magnetic flux radially spreading from the rotor to the stator. The stator core is formed from a plurality of individual stator core sections. Each of the individual stator core sections has a base section and a salient pole section extending from a central section of the base section. The first winding and the second winding are wound around the salient pole section of each of the individual stator core sections.

Abstract: A hydrodynamic bearing apparatus comprises two hydrodynamic bearing sections which have a shaft member, a bearing member fit to the shaft member with a predetermined space therein, lubricants filling the space between the shaft member and the bearing member, and which are separately placed in the axial direction of the shaft member. The lubricants of the two hydrodynamic bearing sections are separated from each other by an air layer. The lubricants are pressured by hydrodynamic generating grooves formed on the hydrodynamic bearing sections such that the shaft member and the bearing member are rotatably supported in relation to each other. The hydrodynamic generating grooves separately formed on the two hydrodynamic bearing sections are formed into an unbalanced shape such that the lubricants are moved in a predetermined direction to correct the slope of the shaft member and the bearing member when rotation is suspended.

Abstract: A magnetic levitation motor has a rotator body formed from a magnetic member and having segmented permanent magnets attached to a peripheral surface thereof. Two magnetic levitation motor sections are disposed in an axial direction of the rotator body. Each of the magnetic levitation motor sections having a first stator winding that generates a levitation control magnetic flux for levitating the rotator body and a second stator winding that generates a rotation magnetic flux for rotating the rotator body. The segmented permanent magnets are affixed to the rotator body at the two magnetic levitation motor sections with magnetic polarities thereof mutually opposite to each other. The segmented permanent magnets function as bias magnets that generate a direct-current magnetic flux that radially spreads from within the rotor.

Abstract: A gas dynamic pressure bearing apparatus comprises a fixed shaft, a bearing member which is positioned opposite from the fixed shaft and at least a radial gas dynamic pressure bearing portion and a thrust gas dynamic pressure bearing portion which are positioned in a space between the fixed shaft and the bearing member. Dynamic pressure generating means are included for pressurizing gas in the radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion such that dynamic pressure action is generated. The bearing member is rotatably supported in relation to the fixed shaft by means of the pressurizing action such that rotational driving is performed by a predetermined motor. The radial gas dynamic pressure bearing portion and the thrust gas dynamic pressure bearing portion are structured such that gas is sealed from the space around the motor by a space sealing means and that gas flows from one side to other.

Abstract: A hydrodynamic bearing apparatus which includes at least two hydrodynamic bearing sections for rotatably supporting a shaft member and a cylindrical member, where the bearing sections constitute a continuous bearing clearance. A hydrodynamic pressure generating portion is provided for generating a hydrodynamic pressure in a lubricant which is filled in the bearing clearance. One hydrodynamic generating portion is shaped asymmetrically to move the lubricant in one direction. Two capillary sealing sections are also provided. One capillary sealing section is positioned downstream in a moving direction of the lubricant and is configured such that the lubricant moves by a predetermined amount to cancel a differential pressure which is generated at the hydrodynamic bearing sections.

Abstract: A dynamic pressure bearing device for use in a motor including a shaft and a frame. Two bearings interconnect the shaft and the frame of the motor. The two bearings contain a noncompressible fluid. A mechanism for minimizing axial vibrational movement of the shaft is part of the bearing device. In one arrangement, the mechanism is a device connected to the shaft, such that a narrow gap is defined between an end of the device and the frame to provide a flow resistance to the noncompressible fluid. The device connected to the shaft maintains a decreasing width to minimize a loss of torque in the motor.