Abstract: A rotor includes a rotor core. The rotor core has an outer shape including a first arc portion provided so as to intersect a d-axis, a straight line portion provided so as to intersect a q-axis, and a curved portion that connects the first arc portion and the straight line portion. The first arc portion has an arc shape centered on an axial center of the rotor core. The curved portion includes an arc-shaped second arc portion that bulges outward in a radial direction of the rotor core. The radius of curvature of the second arc portion being smaller than a radius of curvature of the first arc portion.

Abstract: A rotor includes a rotor core. The rotor core has an outer shape including a first arc portion provided so as to intersect a d-axis, a straight line portion provided so as to intersect a q-axis, and a curved portion that connects the first arc portion and the straight line portion. The first arc portion has an arc shape centered on an axial center of the rotor core. The curved portion includes an arc-shaped second arc portion that bulges outward in a radial direction of the rotor core. The radius of curvature of the second arc portion being smaller than a radius of curvature of the first arc portion.

Abstract: A rotor core formed with a shaft hole at the center thereof is provided. A cylindrical member fitted into the shaft hole of the rotor core along an outer peripheral surface of the cylindrical member is provided. A drive shaft inserted into a hollowed part of the cylindrical member (collar) is provided. The collar is made of the material having a lower Young's modulus than those of the rotor core and the drive shaft, and is formed such that an inner peripheral surface of the collar is a tapered surface. The drive shaft has, at an outer periphery thereof, a tapered surface such that the tapered surface is in surface contact with the tapered surface of the collar in fitting of the drive shaft into the collar.

Abstract: A rotor core formed with a shaft hole at the center thereof is provided. A cylindrical member fitted into the shaft hole of the rotor core along an outer peripheral surface of the cylindrical member is provided. A drive shaft inserted into a hollowed part of the cylindrical member (collar) is provided. The collar is made of the material having a lower Young's modulus than those of the rotor core and the drive shaft, and is formed such that an inner peripheral surface of the collar is a tapered surface. The drive shaft has, at an outer periphery thereof, a tapered surface such that the tapered surface is in surface contact with the tapered surface of the collar in fitting of the drive shaft into the collar.

Abstract: A field element core includes field magnet through holes and coupling part. The field magnet through holes are circularly disposed in a peripheral direction around a predetermined direction and are adjacent to each other in the peripheral direction to form a set. The field magnet through holes forming the same pair both extend along a given direction that is defined for each pair, when viewed from the predetermined direction. The coupling part 11 is provided between the field magnet through holes forming the same set and has ends as lateral surfaces, respectively. The entire lateral surfaces of the coupling part are curved to form a concave shape. Specifically, viewed from the predetermined direction, only at a given position between both ends of the lateral surface, a tangent of the lateral surface extends along an extending direction of the coupling part. The same holds true for the lateral surface.

Abstract: A field element core has field magnet through holes and connecting portions. The field magnet through holes are circumferentially arranged in a circumferential direction around a given direction, and are adjacent each other in the circumferential direction to form pairs. Seen from the given direction, field magnet through holes forming the same pair both extend along a certain one direction determined for each pair. A connecting portion is provided between the field magnet through holes of the same pair, and has the ends as its sides. The sides of the connecting portion are curved in a concave shape as a whole. Specifically, seen from the given direction, a tangent to the side is along the direction of extension of the connecting portion only at a certain one position between both ends of the side. The same holds true for the side.

Abstract: A field element core includes field magnet through holes and coupling part. The field magnet through holes are circularly disposed in a peripheral direction around a predetermined direction and are adjacent to each other in the peripheral direction to form a set. The field magnet through holes forming the same pair both extend along a given direction that is defined for each pair, when viewed from the predetermined direction. The coupling part 11 is provided between the field magnet through holes forming the same set and has ends as lateral surfaces, respectively. The entire lateral surfaces of the coupling part are curved to form a concave shape. Specifically, viewed from the predetermined direction, only at a given position between both ends of the lateral surface, a tangent of the lateral surface extends along an extending direction of the coupling part. The same holds true for the lateral surface.

Abstract: In the present invention, since gaps respectively provided at one ends of a field magnet through-hole respectively extend toward the other ends passing on the side of a periphery with respect to the field magnet through-hole, the radial dimension of the magnetic member in this portion can be made smaller than the center of magnetic poles, so that the difference in thickness of the magnetic member in the radial direction between the border of magnetic poles and the magnetic poles can be reduced. Accordingly, the asymmetry of the configuration of a rotor is not absolutely necessary, and the outer surface does not need to be depressed for reducing the torque ripple.

Abstract: A motor includes a rotor core, permanent magnets and non-magnetic layers. The permanent magnets are embedded in the rotor core with each of the permanent magnets defining a pole of the rotor having a pole center and a peripheral edge section, with the peripheral edge section located in a vicinity between the poles and a vicinity of the rotor surface. The non-magnetic layers are located in a vicinity of the rotor surface at a pole center side position with respect to the peripheral edge section of each of the permanent magnets. The peripheral edge sections and the non-magnetic layers are positioned to cancel 5-th or 7-th order harmonics of an induction voltage. The poles are disposed at every approximately constant interval, varying in a constant angle. The peripheral edge sections and the non-magnetic layers are independent from one another, and the rotor core is interposed between them.

Abstract: A motor has a rotor core with a plurality of first non-magnetic layers and a plurality of second non-magnetic layers. The rotor core has a plurality of magnets. The first and second non-magnetic layers are positioned to cancel n-th order harmonics. Therefore, a specific order, for example 5-th order and 7-th order, harmonics component of a magnetic flux distribution waveform (induction voltage waveform) is reduced and unnecessary radial force and thrust force is prevented from occurrence, while sufficient magnetic flux is maintained.

Abstract: A motor includes a rotor core, permanent magnets and non-magnetic layers. The permanent magnets are embedded in the rotor core with each of the permanent magnets defining a pole of the rotor having a pole center and a peripheral edge section, with the peripheral edge section located in a vicinity between the poles and a vicinity of the rotor surface. The non-magnetic layers are located in a vicinity of the rotor surface at a pole center side position with respect to the peripheral edge section of each of the permanent magnets. The peripheral edge sections and the non-magnetic layers are positioned to cancel 5-th or 7-th order harmonics of an induction voltage. The poles are disposed at every approximately constant interval, varying in a constant angle. The peripheral edge sections and the non-magnetic layers are independent from one another, and the rotor core is interposed between them.

Abstract: In the present invention, since gaps respectively provided at one ends of a field magnet through-hole respectively extend toward the other ends passing on the side of a periphery with respect to the field magnet through-hole, the radial dimension of the magnetic member in this portion can be made smaller than the center of magnetic poles, so that the difference in thickness of the magnetic member in the radial direction between the border of magnetic poles and the magnetic poles can be reduced. Accordingly, the asymmetry of the configuration of a rotor is not absolutely necessary, and the outer surface does not need to be depressed for reducing the torque ripple.

Abstract: A field element core has field magnet through holes and connecting portions. The field magnet through holes are circumferentially arranged in a circumferential direction around a given direction, and are adjacent each other in the circumferential direction to form pairs. Seen from the given direction, field magnet through holes forming the same pair both extend along a certain one direction determined for each pair. A connecting portion is provided between the field magnet through holes of the same pair, and has the ends as its sides. The sides of the connecting portion are curved in a concave shape as a whole. Specifically, seen from the given direction, a tangent to the side is along the direction of extension of the connecting portion only at a certain one position between both ends of the side. The same holds true for the side.

Abstract: A brushless DC motor has a stator and a rotor. An angle ?0 between an edge section of the flux barrier on a magnetic pole center side and an edge section on a side for coming in contact with the rib of adjacent flux barrier, with respect to the rotor center, is determined to be equal to or greater than an angle satisfying a following relationship ?0=180°*m/(Pn*f/f0) (provided 2?0??r<90°) wherein, a frequency of vibration which is to be reduced is represented with f, a pole pair number is represented with Pn, an electrical frequency is represented with f0=Pn*N, a motor revolution is represented with N, m=1, 3, 5, . . . , an angle of the rib with respect to the rotor center is represented with ?r, therefore making of motor highly effective and decreasing of the motor acoustic noise are coped with.

Abstract: A motor has a rotor core with a plurality of first non-magnetic layers and a plurality of second non-magnetic layers. The rotor core has a plurality of magnets. The first and second non-magnetic layers are positioned to cancel n-th order harmonics. Therefore, a specific order, for example 5-th order and 7-th order, harmonics component of a magnetic flux distribution waveform (induction voltage waveform) is reduced and unnecessary radial force and thrust force is prevented from occurrence, while sufficient magnetic flux is maintained.

Abstract: A brushless DC motor has a stator and a rotor. An angle ?0 between an edge section of the flux barrier on a magnetic pole center side and an edge section on a side for coming in contact with the rib of adjacent flux barrier, with respect to the rotor center, is determined to be equal to or greater than an angle satisfying a following relationship ?0=180°*m/(Pn*f/f0) (provided 2?0??r<90°) wherein, a frequency of vibration which is to be reduced is represented with f, a pole pair number is represented with Pn, an electrical frequency is represented with f0=Pn*N, a motor revolution is represented with N, m=1, 3, 5, . . . , an angle of the rib with respect to the rotor center is represented with ?r, therefore making of motor highly effective and decreasing of the motor acoustic noise are coped with.

Abstract: In a brushless DC motor system, an RMS value of an input current of a voltage-fed inverter (702) is detected by a current transformer (705) and an RMS value detector circuit (706). A rotation speed of a brushless DC motor (703) is detected based on a cycle of a position signal outputted by a position sensor circuit (704). Then, in response to the RMS value of the input current and the rotation speed, the phase of the inverter output voltage relative to the phase of the motor counter-electromotive voltage is set to a phase at which the motor efficiency comes generally to a peak, and a switching command to the voltage-fed inverter (702) is generated. With this constitution, when the applied voltage waveform is controlled only by the voltage-fed inverter in response to the rotor-position detection signal, the motor attains high-efficiency operation without involving any increase in cost and yet regardless of load conditions.