Abstract: A motor includes: a stator having teeth protruding radially inward from the inner peripheral surface of a stator core; coils wound on the teeth; a shaft rotating on the inside radially of the stator core; a rotor core affixed to the shaft and radially centered on the rotation axis of the shaft; permanent magnets arranged on the outer peripheral surface of the rotor core; projecting poles which are formed projecting radially outward between the permanent magnets adjacent to each other in the circumferential direction of the outer peripheral surface of the rotor core, and with which the projecting contact surfaces of the permanent magnets are in contact. The stator is formed by stacking electromagnetic steel sheets in the direction of the rotation axis of the shaft. At least one of the axial ends of each of the permanent magnets projects further than an axial end of the rotor core.

Abstract: An engine-and-electric-machine assembly includes an engine and an electric machine, a crankshaft being provided in the engine, the crankshaft including a main body and an extension section that extends out to the exterior of the engine, the extension section forming a rotation shaft of the electric machine, a rotor of the electric machine being mounted on the extension section, and a transition section being provided between the main body of the crankshaft and the extension section, wherein the rotor of the electric machine is connected to the transition section via a flange structure. By connecting the rotor of the electric machine and the crankshaft of the engine by using a flange, instead of using a key connecting structure, the strength of the connection between the rotor and the crankshaft can be improved, and optimize the moment of inertia of the transmission structure between the rotor and the crankshaft.

Abstract: An electric generator comprising a rotor housing; a rotor mounted in the rotor housing, with two opposed main faces; permanent magnets circumferentially arranged in front of one of the main faces of the rotor; coils circumferentially arranged in front of the other one of the main faces of the rotor; the rotor being configured for, upon rotation, vary a magnetic flux through the coils produced by the permanent magnets, so as to generate electromotive forces in said coils; wherein the coils are arranged outside of the rotor housing. Also a valve for gas cylinder, equipped with a corresponding electric generator.

Abstract: A motor includes a stator and a rotor. The rotor is rotatable about an axis. The rotor includes a core including a plurality of pole segments arranged arcuately about the axis. The rotor further includes a plurality of arcuately arranged magnets alternating arcuately with the pole segments, such that each of the magnets is at least in part interposed between a pair of adjacent pole segments. The plurality of pole segments includes a plurality of first-polarity pole segments having a first polarity and a plurality of second-polarity pole segments having a second polarity that is different than the first polarity. The rotor further includes a connecting element connecting at least some of the first-polarity pole segments to one another without connecting the second-polarity pole segments to the first-polarity pole segments.

Abstract: A multiple of communication hole pairs each including two communication holes are formed in a rotor in a rotor rotation direction. A region between the two communication holes of each communication hole pair is a center bridge that connects a core portion of the rotor and an umbrella form portion on an outer side in the rotor radial direction, and each communication hole communicates with an outer periphery of the rotor. A multiple of radiating projections protrude in the rotor radial direction from a central axis of rotation between respective pairs of the communication hole pairs. The radiating projections have side surface projections protruding to the umbrella form portion side neighboring in the rotor rotation direction. The side surface projections cover a whole or one portion of the umbrella form portion from the outer peripheral side of the rotor.

Abstract: A rotor iron core includes: a plurality of first iron cores and arranged in an outer side in a radial direction of each permanent magnet; and a second iron core with mechanical strength higher than mechanical strength of each first iron core and that includes an inner iron core arranged on an inner side in the radial direction of each permanent magnet and a plurality of inter-magnetic pole iron cores formed integrally with the inner iron core and arranged between magnetic poles of each permanent magnet, wherein each inter-magnetic pole iron core is formed from an end part in a circumferential direction of each first iron core to the inner iron core, and a flux barrier is formed between each permanent magnet and each inter-magnetic pole iron core.

Abstract: A stator core and a rotor core are provided. The stator core includes field windings receiving a direct current, and armature windings receiving an alternating current. Permanent magnets, each housed in one of the slots together with ones of the field windings, and in contact with the ones of the field windings, are provided. The field windings are provided on both of inner and outer circumferential sides of the permanent magnets.

Abstract: An electric motor has a supplementary field magnet including a supplementary magnet, a yoke serving as a magnetic path for magnetic flux produced by the supplementary magnet. The supplementary field magnet is arranged on one axial end side of the rotor with a gap. A rotor core is provided with first projections projecting toward one axial end side of the electric motor from first magnetic pole portions having a first polarity, and second projections projecting toward the one axial end side from second magnetic pole portions having a second polarity, and arranged radially inward of the first projections. The yoke includes a magnetic pole portion axially opposed to the first projections and having the first polarity, and another magnetic pole portion axially opposed to the second projections and having the second polarity such that a gap is formed between the magnetic pole portions.

Abstract: An electric motor has a supplementary field magnet including a magnetization coil, a yoke serving as a magnetic path for magnetic flux produced by the magnetization coil, and a variable magnet. The supplementary field magnet is arranged on one axial end side of the rotor with a gap. A rotor core is provided with first projections projecting toward one axial end side of the electric motor from first magnetic pole portions, and second projections projecting toward the one axial end side from second magnetic pole portions and arranged radially inward of the first projections. The yoke includes an outer magnetic pole portion axially opposed to the first projections, and an inner magnetic pole portion axially opposed to the second projections such that an annular gap is formed between the inner magnetic pole portion and the outer magnetic pole portion.

Abstract: A low-cost controller having a function for effectively displaying information of present motor output regarding the maximum output and the continuous rating output of the motor. The controller includes first and second storing parts which store first and second data, representing a relationship between a rotation frequency and a maximum output of the motor, and a relationship between the rotation frequency and a continuous rating output of the motor, respectively; first and second ratio calculating parts which calculate first and second ratios, corresponding to a ratio of one of the maximum output and the continuous rating output to the other at a present rotation frequency, and a ratio of a present actual output of the motor to the one of the maximum output and the continuous rating output at the present rotation frequency, respectively; and a displaying part which displays the first and second ratios on the same screen.

Abstract: A rotor includes a first rotor core, a second rotor core, a first magnet, a second magnet, and an annular magnet. The first magnet is arranged between first extensions of the first rotor core. The annular magnet, which is arranged between second extensions of the second rotor core, is held between the first core base and the second core base. The first magnet and the second magnet are formed integrally.

Abstract: A rotor core according to an embodiment includes a pair of magnet openings disposed such that a space therebetween widens toward an outer peripheral side and in which a pair of permanent magnets having a magnetic pole direction relative to a radial direction identical to each other are inserted. The magnet openings each have a shape that connects together a first opening portion formed along the profile of the corresponding permanent magnet and a second opening portion that, when the permanent magnet is inserted in the first opening portion, covers, out of corner portions of the permanent magnet, a corner portion closest to the other permanent magnet with an air gap defined therebetween. The second opening portion forms a bridge portion between the second opening portion and the second opening portion of the other magnet opening.

Abstract: A rotor described herein includes a plurality of flux barriers that include at least one magnetic path formed between a plurality of slits. The flux barriers are arranged in a circumferential direction at a predetermined interval. Adjacent flux barriers are concatenated on an inner circumferential side by an annular connector provided on the inner circumferential side, and are separated on an outer circumferential side by openings provided on the outer circumferential side. The rotor also includes a permanent magnet at least partially embedded within the annular connector.

Abstract: In a multi-gap electric rotating machine, a stator core has a radially outer portion, a radially inner portion and a connecting portion. The radially outer portion is located radially outside of a rotor core with a radially outer magnetic gap formed therebetween. The radially inner portion is located radially inside of the rotor core with a radially inner magnetic gap formed therebetween. The connecting portion radially extends to connect the radially outer and inner portions and is located on one axial side of the rotor core with an axial magnetic gap formed therebetween. A stator coil is formed of electric wires mounted on the stator core. Each of the electric wires has radially-outer in-slot portions, radially-inner in-slot portions and radially-intermediate in-slot portions, which are respectively received in slots of the radially outer portion, slots of the radially inner portion and slots of the connecting portion of the stator core.

Abstract: In a motor, an armature includes an annular yoke having an inner surface, and a plurality of teeth radially projecting individually from the inner surface of the annular yoke, and a rotor is rotatably provided inside the armature with a gap between the outer surface thereof and the inner surface of the armature. The armature and rotor is configured to have a first magnetic resistance facilitating reactive magnetic flux to flow through at least one tooth in a plurality of teeth to an adjacent tooth of the at least one tooth therein as compared with the reactive magnetic flux toward the rotor. The armature and rotor is configured to have a second magnetic resistance facilitating main magnetic flux based on the at least one pair of magnetic poles to flow toward a yoke of the armature as compared with the main magnetic flux toward at least one tooth close to the main magnetic flux.

Abstract: A motor includes: a rotor comprising: a rotary shaft; a magnetic body rotatable together with the rotary shaft; and first and second permanent magnets fixed on an outer circumference or an inner circumference of the magnetic body, and a stator comprising: an iron core arranged around the rotor; and a coil for exciting the iron core.

Abstract: A motor includes a rotor including a rotor core provided with a plurality of permanent magnets in the circumferential direction and a stator including a stator core on which multi-phase stator coils are wound. The rotor has a structure in which the change pattern of magnetic properties of the rotor core or the permanent magnets changes in the circumferential direction, and the stator has a structure in which first and second stator coils of the stator coils are wound on the stator core for each phase in such a manner that passage of current is optionally switched, and when the passage of current is switched to the second stator coil, the distribution pattern of a magnetic field formed on the inner circumferential side by the stator has uniqueness over the whole circumference.

Abstract: In a rotor for a rotary electric machine, a plurality of magnetic poles are provided in a radially outer portion of the rotor iron core, at intervals in the circumferential direction. Each magnetic pole includes a pair of permanent magnets disposed apart from each other in the circumferential direction, and a magnetic flux-restraining hole that is formed and extended radially inwardly between radially inner end portions of the permanent magnets and that restrains flow of magnetic flux. The magnetic flux-restraining hole is extended so as to project beyond a position of the radially inner end portions to a radially outer side, between the pair of permanent magnets.

Abstract: An electric motor disposed in an electric vehicle includes a stator, a first rotor located at an outer side of the stator, and a second rotor located at an inner side of the stator, wherein each of the first rotor and the second rotor includes a plurality of first permanent magnets and a plurality of second permanent magnets, made of different materials from each other, whereby a material cost can be reduced and an output can be enhanced.

Abstract: A rotor for a permanent magnet electrical machine includes a ferromagnetic core structure having cavities which divide the ferromagnetic core structure into pole regions (103), a yoke region (104), and bridges (105, 106) between them. The rotor includes permanent magnets (107, 108) located in the cavities and arranged to produce magnetic fluxes penetrating the pole regions so as to form magnetic poles of the rotor. The cavities have portions which extend towards the quadrature-axis (Q) and are free from the permanent magnets. Thus, non-ferromagnetic regions for reducing leakage fluxes of the permanent magnets are being formed. Furthermore, the portions of the cavities have a shape curving towards the geometrical rotation axis of the rotor. As the portions of the cavities have the shape curving towards the rotation axis, the cavities can be made longer and the routes of the leakage.

Abstract: To provide a permanent magnet synchronous machine capable of expanding a high-speed operation range without reducing torque, and a pressing machine or an extrusion machine using the permanent magnet synchronous machine. In order to achieve the object described above, the present invention provides a permanent magnet synchronous electric machine having at least one permanent magnet on a radial surface of a rotor core, the permanent magnet having a rotor constituting a field pole, wherein a plurality of slits constituted by nonmagnetic material is provided on a core part between adjacent permanent magnets with opposite magnetic polarities of the rotor. According to the present invention, expansion of a high-speed operation range can be achieved without reducing torque.

Abstract: In some embodiments, an electromagnetic machine includes a rotor element configured for movement relative to a stator. The rotor element includes a support member, a backing member, and a magnetic pole assembly. The support member includes a first coupling portion. The backing member is formed, at least in part, from a ferromagnetic material and the magnetic pole assembly is configured to be coupled to the backing member. The magnetic pole assembly and/or the backing member include a second coupling portion configured to removably couple the backing member and the magnetic pole assembly collectively to the first coupling portion of the support member.

Abstract: A permanently excited synchronous machine includes a stator; a winding system arranged in grooves of a laminated core of the stator and forming winding overhangs on end faces of the laminated core, and a rotor connected in fixed rotative engagement to the shaft and having ferrite magnets which extend axially beyond the end faces of the laminated core. The rotor electromagnetically interacts with the stator across an air gap there between during operation of the permanently excited synchronous machine to cause a rotation about an axis of rotation. A flux concentration element is provided radially across each of the ferrite magnets of a magnetic pole and bundles magnetic field lines of the ferrite magnet onto an axial length of the laminated core of the stator. The flux concentration elements and held by a fixing element on the ferrite magnets of a magnetic pole.

Abstract: A wind turbine having an electric machine, in turn having a stator, and a rotor which rotates about an axis of rotation with respect to the stator; the rotor having a plurality of magnetized modules, and a rotor cylinder which extends circumferentially, rotates about an axis of rotation, and is configured to support the plurality of magnetized modules; and wherein the rotor cylinder is made of nonmagnetic material.

Abstract: A hybrid excitation machine comprising a rotor having first and second rotor cores with an axial gap between; a stator placed radially outward of the rotor; and an exciting coil fixed to the stator placed in an air gap between the stator and rotor to protrude radially inward from the stator. In an axial direction, an axial end of a radially outer end of the first rotor core located on the second rotor core side and the second rotor core are positioned on opposite sides of an axial end of the exciting coil located on the first rotor core side, and an axial end of a radially outer end of the second rotor core located on the first rotor core side and the first rotor core are positioned on opposite sides of the axial end of the exciting coil located on the second rotor core side.

Abstract: A rotor is and a motor including the rotor and a stator are provided. The rotor includes a rotor core and rotor poles. The rotor poles are arranged circumferentially around the rotor core, and each of the rotor poles is formed in an asymmetric shape. The stator is spaced apart from the rotor and includes slots configured for a coil to be wound therearound.

Abstract: A permanent magnet type rotary electric machine has a rotor having a rotor core and permanent magnets buried into the rotor core by being incorporated into respective permanent magnet slots. The permanent magnet slot per one pole is divided at least into four slots along an outer circumferential direction in the rotor core, and in respective rest core-portions between adjacent divided permanent magnet slots in the rotor core, a width of a first rest core-portion at the middle of each pole and a width of a second rest core-portion between adjacent poles of different polarities are formed larger than that of the others.

Abstract: An apparatus includes a rotor and a magnet disposed on the rotor. The apparatus also includes a pole cap proximate to the at least one magnet disposed on the rotor. The pole cap is magnetically coupled to the magnet and has a laterally asymmetric profile.

Abstract: A yoke for a permanent magnet machine shows a surface with an accommodation area for accommodating a permanent magnet, wherein two recesses are provided adjacent to the accommodation area to increase reluctance.

Abstract: A current-energized synchronous motor (1) suitable in particular for vehicle drives. It includes a stator (2) and a rotor (3) carrying the energizer winding (7). The rotor (3) has at least two rotor poles (4) with one energizer winding (7) each. The rotor includes at least one selective magnetic flux barrier, in particular in the form of a radial slot (8) along the main axis (4A) of the rotor pole (4). This flux barrier is provided in each rotor pole (4) for increasing the reluctance moment of the current-energized synchronous motor (1).

Abstract: A magnet for a generator is provided. The magnet includes a base magnet with a main surface having a length and a width and a skewed magnet module arranged at the main surface. A rotor of a generator including the magnet is provided as well as a generator with a stator and rotor including the magnet.

Abstract: A synchronous rotating electrical machine is disclosed, of the type including a stator (10) and a rotor (11). The rotor is of the flux concentration type and includes a plurality of alternate North and South poles formed from permanent magnets (PM). The magnets are housed in slots (E1) arranged in the magnetic body of the rotor. Each pole comprises a second slot (E3) roughly radial and arranged in the magnetic body of the pole, between two consecutive magnets delimiting the pole. In accordance with the invention, each pole includes a portion forming a bridge (BR) between the magnetic bodies of the rotor, on either side of the second slot, this part forming a bridge including a magnetic body height not greater than approximately one times the dimensional value of the width of the permanent magnets.

Abstract: Embodiments of the invention provide for conical magnets for rotors in electrodynamic machines, methods to design the same, and rotor-stator structures for electrodynamic machines. In various embodiments, a rotor-stator structure for electrodynamic machine can include field pole members and conical magnets. According to at least some embodiments, one or more of the conical magnets can include a magnetic region configured to confront one or more air gaps. The magnetic region can be substantially coextensive with one or more acute angles to the axis of rotation. The magnetic region can also include a surface positioned at multiple radial distances from the axis of rotation in a plane perpendicular to the axis of rotation.

Abstract: A rotating electric motor includes a stator core, a rotational shaft capable of rotation, a field yoke allowing a flow of magnetic flux in an axial direction, first and second rotor cores fixedly installed on the rotational shaft, a first magnet fixedly installed between the first rotor core and the second rotor core, a first rotor teeth formed at the first rotor core, a second magnet provided alongside of the first rotor teeth in the circumferential direction of the first rotor core, a second rotor teeth formed at the outer surface of the second rotor core, protruding outwardly in the radial direction, a third magnet provided alongside of the second rotor core in the axial direction, and windings that can control the density of magnetic flux between at least one of the first rotor core and second rotor core and the stator core.

Abstract: The invention relates to a salient-pole machine comprising at least one field coil that extends in an axial direction of the salient-pole machine and is located below a pole shoe on a rotor body. Said machine is characterized in that the field coil is pressed against the pole shoe by means of at least one spring that is provided between the field coil and the rotor body and that an axial cooling channel is created in the gap between the field coil and the rotor body that is formed by the spring. The spring is configured in particular as a bent plate spring.

Abstract: A dynamoelectric machine comprising a stator having a plurality of slots and teeth, armature windings wound around the teeth, and a rotor disposed inside the stator, wherein an alloy member is disposed in the inner periphery of the stator and the magnetic compensator has its surface or inside thereof a high resistance layer.

Abstract: A motor-generator system with a current control feedback loop for generating electrical energy in stationary, portable, and automotive applications. The generator includes a housing defining an interior space and including a first portion and a second portion; an electric motor assembly positioned within the first portion of the housing, and operationally coupled to a shaft member for selectively rotating the shaft member; an electric generator assembly positioned within the second portion of the housing and operationally coupled to the shaft member for converting mechanical rotation into electrical energy, the electric generator assembly including a current output for supplying electrical current; and a control assembly operationally coupled between the electric generator assembly and the electric motor assembly the control assembly providing a control current to the electric motor assembly for controlling a speed of rotation induced into the shaft member by the electric motor assembly.

Abstract: A stepping motor has a stator and a rotor disposed to surround the stator. The rotor has an annular magnet which has a plurality of magnetic poles formed along a circumference thereof, and a comb-teeth-shaped back yoke which is disposed to surround the magnet and has a plurality of comb teeth, the comb teeth facing boundary positions of adjacent magnetic poles.

Abstract: The invention relates to a continuously controllable gear comprising a driving rotor rotatably driven by a power source which is provided with magnets uniformly distributed on the periphery thereof and produces, during the rotation thereof, a magnetic multipolar field in an ambient space rotating therewith. Said driving rotor is surrounded in the radial direction outwards with the primary air gap of a coaxial field concentrator which forms magnetoconductive pole shoes and is separated from a coaxial stator by means of a secondary air gap. The grooves of the stator are provided with sequentially short-circuitable windings.

Abstract: A method of balancing an embedded permanent magnet motor rotor includes the steps of: a) providing a non-magnetic cylindrical shaft having an axis of rotation and a generally cylindrical surface with an even number of recessed slots defining an even number of ribs therebetween; b) machining an axial slot having a cross-section with a top opening, a bottom and two sides in a center portion of each of the recessed slots; c) sliding at least one balance weight into at least one of the axial slots; and d) inserting locating rods into the axial slot on each side of the at least one balance weight.

Abstract: A motor magnetic pre-stressing apparatus includes a stator and a rotor. The rotor is pivoted with the stator. The stator includes a lower insulating frame and a magnetic-guiding ring, and the magnetic-guiding ring is installed on the lower insulating frame. The rotor has a magnetic element, and the magnetic element has even radial magnetic poles. Thereby, by utilizing the attraction between magnetic-guiding ring and the magnetic element, a magnetic pre-stressing force is generated to absorb the rotor downwards so that the rotor rotates stably and smoothly.

Abstract: A brushless electric machine includes a rotor and a stator. Each of the twin poles of the stator electromagnetic members corresponds to one of the two magnetic poles of the rotor magnetic assembles. Two radial component air-gaps are arranged between the stator and the rotor to separate the stator and the rotor. Axial component air-gaps axially corresponding are arranged between the stator poles and the corresponding rotor poles to separate the stator poles and the rotor poles. The stator wheel-shaped ring is partly surrounded by the rotor wheel-shaped ring.

Abstract: A hybrid-excited rotating machine comprising: a stator winding of a multi-phase Y-connection; a plurality of rotor magnetic poles fixed on a rotor shaft 3 at a predetermined spacing in the circumferential direction and confronting the inner circumference of said stator through a air gap; a plurality of permanent magnets fixed at substantially central portions of said circumferential direction of said individual rotor magnetic poles and magnetized in the radial direction of said rotor shaft; and a plurality of field windings wound individually on said rotor magnetic poles.

Abstract: A synchronous electric motor including a rotor having a rotation axis, and a stator surrounding the rotor through a gap. The rotor includes a rotor core having an outer circumferential surface extending about the rotation axis and a plurality of permanent magnets attached to the rotor core to form plural poles along the outer circumferential surface of the rotor core. The outer circumferential surface of the rotor core is provided, at each pole, with a contour deviating from a circular arc and bulging out in a radial outward direction, as seen in a cross-section perpendicular to the rotation axis. The permanent magnets include a plurality of magnet sets individually assigned to the plural poles, each set including two or more permanent magnets. The contour of the outer circumferential surface of the rotor core, at each pole, has at least partially a shape represented by a hyperbolic cosine function or a secant function.

Abstract: An electrical machine, in particular a brushless synchronous motor has a stator (14) and a rotor (12) with salient poles (18) disposed distributed over its circumference, each of which poles has an enclosed permanent magnet (11) and a pole shoe (19) that extends radially outward from the permanent magnet and defines an air gap (13) between the stator (14) and rotor (12). In order to achieve a low cogging torque and a low torque undulation, the pole shoes (19) are embodied as magnetically anisotropic, with a preferred direction of the greater magnetic conductivity extending parallel to the radial salient pole axis.

Abstract: An electric motor including a stator with a plurality of coils wound around a ring-shaped iron core, and a rotor rotatably disposed inside the stator is provided. The rotor includes a rotor shaft and a yoke. The yoke is provided near its periphery with a plurality of plate-like permanent magnets arranged at equal pitches. Heat generated from the rotor is released through a plurality of air holes formed in the yoke between the rotor shaft and the permanent magnets.

Abstract: A polyphasie multi-coil generator includes a drive shaft, at least first and second rotors rigidly mounted on the drive shaft so as to simultaneously synchronously rotate with rotation of the drive shaft, and at least one stator sandwiched between the first and second rotors. A stator array on the stator has an array of coils mounted to the stator in a first angular orientation about the drive shaft. The rotors each have an array of magnets which are equally circumferentially spaced around the rotor and located at the same radial spacing with respect to the center of the rotor and the drive shaft. The arrays of magnets on adjacent rotors are off-set by an angular off-set relative to one another.

Abstract: A method of determining magnet pole geometry for controlling cogging in an electric motor includes defining the magnet pole geometry in terms of at least one design parameter, predicting cogging as a function of the design parameter, and from the predicted cogging, selecting a value for the design parameter which corresponds to a desired level of cogging in the electric motor.

Abstract: In a rotating electric machine using permanent magnets and a field control coil, to allow the properties of the rotating electric machine to be readily changed and the rotating electric machine to be adapted to various applications even when it is made of common component parts, the field control coil is adapted to superimpose magnetic flux components of different intensities onto magnetic flux components that are supplied by the magnet poles and iron poles to the teeth, respectively. The magnetic flux components may be differentiated by placing each permanent magnet in a recess defined in an inner circumferential surface of the yoke, and defining each iron pole by a part of the yoke located between an adjacent pair of the permanent magnets in such a manner that the inner circumferential surface of each permanent magnet is lower than the said part of the yoke.

Abstract: In a rotor 20 including a plurality of permanent magnet pieces 60 fixed in a plurality of magnet insertion slots 43 provided on the outer periphery of a rotor yoke 40, respectively, and the rotor yoke 40 having concaves 44 each provided between the permanent magnet pieces 60 adjacent to each other and protrusions 46 each provided in each the concaves 44 to protrude outwardly in the radial direction of the rotor yoke 40, between the sandwiching angle ? formed by two sides connecting both outer ends A and A? of each the concaves 44 to the center axis O of the rotor yoke 40 and the sandwiching angle ? formed by two sides connecting both outer ends B and B? of each the protrusions 46 to the center axis O of the rotor yoke 40, the following relationship is satisfied: 0.3<?/?<0.5.