Abstract: A motor includes a stationary portion and a rotating portion. The rotating portion includes a sleeve portion including one communicating hole arranged to extend completely there through from an upper surface to a lower surface thereof, and a cover portion including a hole portion. The axial extension range of the hole portion is arranged to overlap with the axial extension range of the communicating hole in a radial direction. A center of the hole portion is arranged on a plane including a central axis and a center of the communicating hole. The communicating hole and the hole portion are arranged on opposite sides of the central axis. The following inequality is satisfied: V2<(?1/?2)·V1, where ?1 is the density of the sleeve portion, V1 is the volume of the communicating hole, ?2 is the density of the cover portion, and V2 is the volume of the hole portion.

Abstract: Methods for fabricating a balance ring for a vehicular electric machine are provided. In one embodiment, the method includes the steps of providing a first metal layer having a first planar surface, providing a second metal layer having a second planar surface, cladding the second planar surface to the first planar surface to form a composite structure, and removing a portion of the composite structure to form an annular ring.

Abstract: A rotor is provided. The rotor includes a bearing yoke, a supporting member, a rotor substrate, a coil, and a weight coupled to the supporting member. The supporting member is coupled to the bearing yoke. The rotor substrate is supported by the supporting member. The coil is supported by the supporting member and electrically connected to the rotor substrate. The weight is coupled to the supporting member.

Abstract: A magnetic induction data transmission network comprising a master hub, at least one sensor node communicatively coupled to the master hub and a magnetic induction coil preferably adapted to be worn about a body part of a subject such as an individual's waist or neck. In at least one embodiment of the invention, the magnetic induction coil preferably includes a connector which serves as an intermediary between the coil and the hub to allow data communication.

Abstract: A motor for a fuel pump includes a rotor which includes a shaft, a rotor core and a commutator fitted on the shaft. The rotor core is formed by stacking together a plurality of aligned laminations and includes a plurality of salient poles arranged along a circumference thereof. A center line of gravity of the rotor deviates from a rotational axis of the rotor. The rotor core has a first groove in one of the poles close to the center line of gravity of the rotor. The first groove extends from a first axial end of the rotor core to an axial middle portion of the rotor core.

Abstract: A magnetic fan device includes a stator, at least three bearings fixed on the stator, a rotor fixedly connected to the stator, a motor, and at least three magnetic posts. The at least three bearings are permanent magnets. The rotor includes a shaft and a plurality of impellers rotatably connected to the shaft. The at least three magnetic posts with an opening at its lateral surface are configured for respectively receiving the at least three bearings by the opening. A first magnet is adhered to ends of the at least three magnetic posts, and a second magnet is adhered to opposite ends of the at least three magnetic posts. The magnetic pole of the first magnet adjacent to ends of the at least three bearings is opposite to the magnetic pole of the second magnet adjacent opposite ends of the at least three bearings.

Abstract: A motor includes a coming-off preventing portion including an inner circumferential edge defining a through hole, inside which a substantially cylindrical bearing housing is inserted, and being arranged axially above an insulator. The inner circumferential edge has at least two different radial dimensions. A boss portion includes a columnar portion inserted inside the through hole, and a collar portion extending radially outward from a lower end of the columnar portion. The collar portion includes an outside surface having at least two different radial dimensions, and an upper surface arranged axially opposite a bottom portion of the inner circumferential edge. The radial dimensions of the inner circumferential edge and those of the collar portion are arranged to allow the collar portion to be axially inserted through the inner circumferential edge only when the inner circumferential edge and the collar portion are arranged in a predetermined circumferential orientation relative to each other.

Abstract: A method and apparatus for mitigating bearing failure in an AC induction motor includes installing a high frequency mechanical vibration-absorbing material between various components of the motor. With the vibration-absorbing material in place, the number of premature bearing failures caused by the presence of bearing current is greatly reduced.

Abstract: An electric compressor incorporating an electric motor for driving a compression mechanism and containing, in a compressor housing, a joint between an external terminal for supplying power to the electric motor and an end of a wire from a stator of the electric motor. The electric compressor has a vibration proof structure mechanically preventing at least one of disconnection, electrical instantaneous interruption, and damage on an insulating member that are caused by vibration at the joint and/or the vicinity of the joint. The vibration proof structure can adopt various structures. When such a mechanical vibration proof structure is provided in the electric compressor, vibration proof performance can be enhanced at the joint of a motor terminal with good productivity achieved, and occurrence of disconnection and instantaneous interruption of the terminal joint can be prevented.

Abstract: An electric compressor includes a built-in electric motor for driving the compressor and a connection section between an external terminal for power supply to the electric motor and the end of a wire from a stator of the electric motor and is stored in a compressor housing. The connection section is constructed from a housing side coupler engaged with the compressor housing, a power supply-external terminal side coupler engaged with the housing side coupler, and a stator side coupler for holding the end of the wire from the stator, fitted to the power supply-external terminal side coupler, and engaged with the housing side coupler. Vibration resistance of a terminal connection section for the motor is improved and breakage and momentary electrical interruption at the terminal connection section may be prevented, with productivity of the compressor maintained at a good level.

Abstract: A compressor has stator of a motor is installed in a closed container, on two planes normal to the center axis 1a of the container. On each of the planes, the stator is welded to the container at three welding points. This mounting arrangement on two planes with three welding points on each plane minimizes the amount of movement of the stator in the direction of the center axis.

Abstract: An electric motor damping module includes an electric motor, a motor damper continuously interconnected with the electric motor, and an input member continuously interconnected with the motor damper. A transmission includes these elements, plus an output member, first, second, and third planetary gear sets each having first, second and third members, a first interconnecting member continuously interconnecting the third member of the first planetary gear set with the second member of the second planetary gear set, a second interconnecting member continuously interconnecting the second member of the first planetary gear set and the output member with the third member of the third planetary gear set, and a third interconnecting member continuously interconnecting the third member of the second planetary gear set with the second member of the third planetary gear set. The transmission also includes six torque transmitting mechanisms and a hydraulic pump. A sealing assembly is also provided.

Abstract: The invention relates to an arrangement for acoustic decoupling of a stator of an electric motor having two substantially cylindrical decoupling rings disposed on both sides of the stator and concentric to a motor shaft, each fixed to a front side of the stator on one side and each fixed to a housing enclosing the stator on the other side, and comprising recesses on the circumferential surfaces thereof. The decoupling rings hold the stator in a centered position at a distance from the housing. The recesses allow targeted acoustic decoupling. The invention is particularly applicable for electric motors in steering systems for motor vehicles.

Abstract: A support structure is used to mount the stator of a rotating electrical machine (e.g. a motor or generator). The support structure includes a rigid external support frame (6). To minimise the transmission of vibrations caused by stator electromagnetic forces into the external support frame (6), at least one sandwich anti-vibration mount (14a) is secured between the external support frame (6) and a part of the stator (28). The mount (14a) is oriented relative to the stator such that it experiences compression loading in a substantially tangential direction of the stator and radial shear loading in a substantially radial direction of the stator during operation of the rotating electrical machine. The sandwich anti-vibration mount (14a, 14b) is pre-loaded with a pre-determined compression load substantially along its compression axis (Ac).

Abstract: A motor includes a balancing member having a surface, a shaft coupling portion and a magnetically conductive portion. A stator is coupled to the balancing member. A rotor includes a hub, a shaft, and a permanent magnet. The shaft and the permanent magnet are mounted inside the hub. The shaft is rotatably coupled to the shaft coupling portion. The permanent magnet includes a magnetically attracting face aligned with the magnetically conductive portion of the balancing member. The magnetically attracting face and the magnetically conductive portion attract each other to maintain stable rotation of the rotor while providing a simplified structure. The balancing member can be interconnected to a housing, and the hub can include a plurality of blades to form a heat dissipating fan. When the rotor rotates, air currents are drawn by the blades to a heat source for heat dissipating purposes.

Abstract: A generator rotor torsional damper system includes a prime mover for generating rotational force, a generator stator, a generator rotor rotatably supported relative to the generator stator and configured to receive a rotational force input from the prime mover, a flywheel rotationally supported relative to the generator rotor by bearings, and an eddy current coupling operably connected between the flywheel and the generator rotor such that rotation of the generator rotor induces rotation of the flywheel in a common rotational direction through engagement by the eddy current coupling.

Abstract: A spindle motor can include a rotor support piece, which may rotatably support a rotor that is inserted onto one end, and which may include a projecting part that protrudes from the other end and a mounting part that has a flat surface formed along the periphery of the projecting part; a base plate, in which an insertion hole may be formed for inserting the projecting part through, and on which multiple support protrusions may be formed along the periphery of the insertion hole for supporting the mounting part along a periphery of the insertion hole; and a buffer member, which may include a projecting-part hole for inserting the projecting part through and support-protrusion holes for inserting the support protrusions through, and which may be positioned between the rotor support piece and the base plate to absorb vibration. This arrangement can reduce the occurrence and transfer of vibrations.

Abstract: A motor including electrical components laid out to avoid enlargement of the motor. The motor includes a rotor, a cylindrical housing including a closed end and an open end and accommodating the rotor, and an end bracket fixed to the housing to close the open end and including a connector support. Two power supply terminals extend to the connector support. A noise prevention element includes a connection terminal connected to the power supply terminals. A rotation detector detects rotation of the rotor and includes a detector body. The noise prevention element is arranged between the two power supply terminals. The detector body and the noise prevention element are arranged at a portion of the end bracket closer to the connector support and aligned in an axial direction of the motor.

Abstract: A brushless motor system which can suppress adverse influences of electromagnetic noise without increasing the size and enhancing the performance of a filter circuit. In a brushless motor system comprising a brushless motor, an inverter, and a direct current power source, a noise return line for returning a noise current is connected between the brushless motor and the inverter. The noise current is generated in the inverter and reaches the brushless motor. With the provision of the noise return line, a common mode current leaking from the brushless motor to a ground can be reduced.

Abstract: A motor rotor system including: an axis of rotation, a rotor iron core mounted on the axis of rotation, a permanent magnet, a magnetic ring bracket, and a magnetic ring. The permanent magnet, the magnetic ring bracket, and the magnetic ring are mounted on the rotor iron core. The magnetic ring is sheathed on the magnetic ring bracket. The magnetic ring bracket is located at one end of the rotor iron core and connected with an end face of the rotor iron core. The motor rotor system has excellent batch-to-batch consistency, simple structure, and convenient installation. It is suitable for large batch production and can be controlled using sine-wave driving control methods with a position sensor.

Abstract: A bearing assembly for a submersible pump motor has a bearing body, having a hub, an outer portion, and a plurality of wing portions. The wing portions are spaced apart to form a plurality of cavities in the bearing body. A mass damper is mounted to the hub. The mass damper has an upper portion, a lower portion and mass damper prongs connecting the upper and lower portion. The mass damper prongs are disposed in the cavities, and act to reduce the amplitude of the vibrating frequency of the motor shaft.

Abstract: There is provided a rotor of a compressor motor at a low cost in which a balance weight is stably positioned. A rotor includes a rotor laminated steel plate (12), rotor end plates (16, 18) arranged on both end surfaces of the rotor laminated steel plate (12), and balance weights (20, 22) provided on the outer surfaces of the rotor end plates (16, 18), respectively. The rotor laminated steel plate (12) and the rotor end plates (16, 18) are provided with at least three axial through holes (24) that are equally spaced apart in the circumferential direction. The rotor laminated steel plate (12) and the rotor end plates (16, 18) are fixed by three rivets (26a, 26b, 26c) passing through the axial through holes (24), respectively. The balance weight (20) is fixed to the rotor end plate (16) by the two rivets (26a, 26b) of the three rivets. The balance weight (22) is fixed to the rotor end plate (18) by the remaining one rivet (26c), and is positioned by the engagement members (28).

Abstract: A method and apparatus for reducing or eliminating the effects of torque ripple and cogging torque and otherwise improving performance in an electromechanical machine such as a motor or generator. The rotor and/or stator is conceptually sectionalized and the sections spaced apart by amount sufficient to alleviate deleterious aspects of cogging torque and torque ripple. Positioning of the stator teeth or rotor magnets is determined based on the calculated spacing. Conceptual sections may be formed as physically individual segments. Unwound teeth may be disposed in end spaces between sections occupying less than the entire area of the end space.

Abstract: The invention relates to a protection device for a motor spindle (1) arranged in a housing (2), particularly of a machine tool, having an inner ring (6) fixedly joined to the motor spindle (1) and an outer ring joined to the housing (2). The inner ring (6) is arranged in the outer ring (7) in a way permitting axial motion and a tilting motion, and is placed under elastically resilient preload against the outer ring (7) by means of preloading members (8).

Abstract: A reciprocating vibration generator of a structure enabling force of a reciprocating vibrating body striking a coil to be absorbed by magnetic fluid even if an external impact force is applied, that is, a reciprocating vibration generator provided in a case body 100 with an upper plate spring 40 and a lower plate spring 50 for supporting a ring-shaped weight 20 having a ring-shaped permanent magnet 30 comprised of a combination of semi-ring-shaped permanent magnets 30R, 30L at its inner circumference side so as to be able to reciprocally vibrate in a vertical direction and a cylindrical excitation coil 60 passing through the inside of the ring-shaped permanent magnet 30 in the vertical direction and generating a reciprocating vibrating magnetic field, wherein the semi-ring-shaped permanent magnets 30R, 30L are magnetized in a direction spanning the inner circumferential surface and outer circumferential surface, the inner circumferential surface and top and bottom end faces of the semi-ring-shaped permanent m

Abstract: An electro-mechanical energy conversion device is provided having an armature with a central cavity. The armature is rotatably mounted in a frame. A torsion bar is positioned within the armature with one end connected to the armature and the other end connected with an energy source or consuming device.

Abstract: A spindle motor is provided. The spindle motor includes a base, a bearing housing, a bearing, a rotation shaft, a stator, a bushing, and a rotor. The bearing housing is installed on the base. The bearing is fixed inside the bearing housing. The rotation shaft is installed to be supported by and rotate on the bearing. The stator is disposed around the bearing housing. The bushing is coupled to the rotation shaft. The rotor is coupled to the bushing to rotate through interaction with the stator.

Abstract: A motor assembly to minimize deformation of a vibration-proof member and to achieve stable motor mounting configuration, as well as an image forming apparatus employing the motor assembly, are disclosed. The motor assembly includes a motor, a fixing member to which the motor is fixed, a vibration-proof member provided between the motor and the fixing member to prevent vibration of the motor from being transmitted to the fixing member, and a reinforcing piece having a predetermined strength to prevent relative movement between the motor and the fixing member.

Abstract: An end plate for a generator includes an end plate generally cylindrical and having a central bore to receive a rotor shaft. The end plate has a radially inner boss and a radially outer boss. The radially outer boss is positioned radially outwardly of windings in a generator. The radially inner boss is positioned radially inwardly of the windings in a generator. A main core assembly, a rotor, and a generator incorporating the end plates are all disclosed and claimed.

Abstract: The spindle motor includes a rotating shaft, a rotor cover which is secured to the rotating shaft and rotates the rotating shaft, a bearing for rotatably supporting the rotating shaft, a holder for holding the bearing, and a holding magnet which is directly mounted to an inner wall of the rotor cover. In this case, the holding magnet is positioned above the bearing to prevent oil from being discharged from the bearing to the outside.

Abstract: An electro-motor drive, in particular for a fan drive of a motor vehicle, includes a commutator motor, a motor shaft of which is rotatably mounted on axially opposite sides in shaft bearings facing away from the bearing shield in order to substantially dampen the sound of at least bearing play-related contact noise and vibration or humming noise.

Abstract: The present invention provides a rotor of a brushless (BL) motor, including: a high-strength engineering plastic member formed by injection-molding high-strength engineering plastic around a concavo-convex portion 12a formed on the outer circumferential surface of a rotary shaft; a sound-absorbing resin element formed by injection-molding a sound-absorbing resin around the high-strength engineering plastic member; a cylindrical ring magnet assembly including a plurality of axially aligned ring-shaped magnets, each of which has a plurality of indented grooves 20a and 20b formed on both end edges of the inner circumferential surface thereof; and a high-strength plastic member formed by injection-molding a high-strength plastic between the sound-absorbing resin element and the ring magnet assembly, the high-strength plastic member having a plurality of protrusions formed on the outer circumferential surface thereof in such a fashion that each protrusion corresponds to an associated one of the indented grooves of

Abstract: The present invention relates to a dryer motor assembly support that limits or eliminates cabinet vibration and noise. The dryer comprises a cabinet comprising a floor having an outside peripheral portion, and a central portion with four openings. The dryer further comprises a motor assembly, having a motor and motor mount comprising a base, spaced above the openings. A support assembly for supporting the motor assembly comprises two parallel spaced apart support portions each spaced below and spanning across the central portion, passing beneath the openings. Each support portion has oppositely disposed end portions secured with the peripheral portion. Each support portion comprises two projections extending therefrom toward the base. Each projection passes through a corresponding one of the openings with clearance to secure the support portion with the base, isolating the motor. The motor and support assembly, and the openings are co-located away from the central portion.

Abstract: According to one embodiment, a rotating electrical machine has a vibrating-element. The vibrating-element has spring bars and circular members which cover spring bars while a part is connected to spring bars. The spring bars are connected to first stator core connection portions, which are formed so as to be spaced out in a circumferential direction from each other at two locations on a side surface of the stator core. The stator frame is connected by the second stator core connection portions, which are formed by two locations which are different from the first stator core connection portions, of the stator core. The second stator core connection portions contain a position adjacent to a node portion of a circular mode of vibration of the stator core, in which antinodes and nodes of vibration alternately appear in the circumferential direction as the vibrating-element is attached to the stator core.

Abstract: A mounting arrangement for locating a stator (10) within a casing (16) of a rotating machine comprises at least one mounting plate (12) adapted to engage with the stator (10) and the casing (16). The mounting plate (12) has a series of discrete apertures (20) therein. The apertures (20) extend through the plate (12) and are arranged in an array to provide a convoluted path which impedes the transmission of the dynamic forces through the plate (12) and into the casing (16). The apertures (20) render the plate (12) more resilient to the dynamic forces that the stator (10) experiences in operation. Each aperture (20) divides the plate (12) into portions which provide anisotropic stiffness in the radial and tangential directions.

Abstract: A motor may include a rotor having a rotation shaft, a stator disposed on an outer peripheral side of the rotor, a frame fixed to the stator, and an urging member made of metal for urging an end part on an output side of the rotation shaft to an opposite-to-output side. The frame includes a bottom face part, a stator fixing part which is formed to be bent from the bottom face part and which is fixed to the stator, and a shaft support part which is formed to be bent from the bottom face part so as to face the stator fixing part and which supports the end part on the output side of the rotation shaft, and the urging member is fixed by welding to an output side face which is a face on an output side of the shaft support part. The urging member is preferably a flat spring.

Abstract: An electric machine comprises: a casing (2); a stator (3) and a rotor (4) supported by the casing (2), the rotor (4) having at least one rotor winding (7); a commutator (9) connected permanently to the rotor (4) and electrically connected to the rotor winding (7); a pair of brushes (12), each having a first end (12a) maintained in a sliding position with the commutator (9) and electrically connected to respective terminals which may be connected to an electricity mains supply; a pair of brush holder elements (11) supported by the casing (2), each brush holder element (11) being associated with a respective brush (12) to keep it pressed on the commutator (9). Each brush holder element (11) has at least one lateral surface (18) to face a respective butting position (17) of the casing (2), and which may be joined to the butting portion (17) to transmit a thermal power to the butting portion.

Abstract: A permanent magnet motor having an axially magnetized pull magnet consisting of a baseplate on which a stator lamination stack having stator windings is disposed, wherein a hub is disposed opposite the baseplate, the hub being connected to a shaft that is supported with respect to a bearing bush via one or more fluid bearings wherein the hub carries at least one annular rotor magnet that lies radially opposite the stator lamination stack, wherein a pulling device acting in an axial direction and operating under the influence of magnetic tensile forces is disposed in the region between the hub and the stationary part of the motor, wherein the pulling device consists of a permanent magnetic pull magnet on the side of the rotor that interacts magnetically with surfaces on the side of the stator.

Abstract: A motor may include a rotor having a rotation shaft, a stator disposed on an outer peripheral side of the rotor, an output side bearing which supports an end part on an output side of the rotation shaft in a radial direction and an axial direction, a frame which is provided with a bearing holding part for holding the output side bearing and which is fixed to the stator, and an urging member which is attached to the bearing holding part for urging the output side bearing to an opposite-to-output side. The bearing holding part is formed with a bearing hole which penetrates through the bearing holding part and on which the output side bearing is disposed, and the output side bearing is disposed on the bearing hole in a movable state in the axial direction of the rotation shaft.

Abstract: A solution is provided for tuning the frequency of a torsional mode of interest of a rotating body (such as a generator rotor torsional mode) by adding a detuner to act as an undamped torsional vibration absorber. The detuner may be coupled to an overhung shaft extending from the rotating body. The detuner may be modular, therefore weight can be added or subtracted easily from the detuner in order to adjust the stiffness and/or inertia of the overhung shaft. This change in stiffness and/or inertia yields a torsional frequency of oscillation in the overhung shaft substantially similar to the natural frequency of the torsional mode of interest of the rotating body, therefore forcing the frequency of the torsional mode of interest of the rotating body above or below its torsional natural frequency.

Abstract: A motor pulley minimizes an influence of a resonance phenomenon, thereby reducing noise and vibrations and preventing lowering of durability.

Abstract: The present invention pertains to vibration devices that do not require a rotating mass. In accordance with aspects of the invention, a coil causes a plunger to move linearly. A spring device is coupled to one end of the plunger. Activation of the coil causes the plunger to move in a first direction relative to a body and coil deactivation enables the spring device to move the plunger in an opposite direction relative to the body. Activating the coil at a predetermined frequency causes vibration of the plunger. Vibratory forces are transferred via the spring device and coil onto the body at predetermined locations. Opposing spring devices may be affixed to either end of the plunger. Spring devices may be linear or non-linear. Such spring devices may be used in conjunction with magnetic spring devices. A controller and a driver circuit may be used to control system operation.

Abstract: Damping mechanisms and motor assemblies are provided. In an embodiment, by way of example only, a damping mechanism includes an end cap, a bearing retainer plate, a bearing damper ring, a bearing assembly, and first and second lateral dampers. The bearing damper ring is disposed in an annular cavity inwardly from an inner diameter surface of the end cap and has a radially inwardly-extending flange. The bearing assembly is disposed in the annular cavity radially inwardly relative to the bearing damper ring. The first lateral damper is disposed between a radially inwardly-extending wall of the end cap and the bearing damper ring. The second lateral damper is disposed between the bearing damper ring and the bearing retainer plate.

Abstract: A generator housing includes a top portion, a plurality of side portions, and a base portion. The top, sides, and base portions are connected to form an enclosure, such that a generator can be housed inside the enclosure. The top and side portions include an air and exhaust flow structure that facilitates cooling of a generator maintained inside the housing, that provides a sound attenuation function, and that releases exhaust created by a generator. At least one of the side portions and the top portion may be opened and closed to provide access inside the housing. The base portion includes a structure that facilitates installation and transport.

Abstract: An automotive dynamoelectric machine that achieves disposing of permanent magnets and thickening of field coil wire by ensuring outlet space for field coil lead wires. In the dynamoelectric machine, trough portions are formed on portions of yoke portions between respective circumferentially adjacent claw-shaped magnetic pole portions. Magnet holders are disposed so as to span over all of the trough portions on a pole core body at a rear end excluding a predetermined trough portion, and permanent magnets are held in each of the magnet holders. A field coil lead wire is led out from the rotor so as to pass through the trough portion over which a magnet holder is not disposed.

Abstract: Motors having a magnetic force attenuator are described. In some embodiments, the motors comprise a stationary member having a base and a stator, a rotating assembly having a magnet and a magnetic force attenuator to attenuate the magnetic attraction force between the magnet and the base; and a fluid bearing to support rotation of the rotating assembly relative to the stationary member. The magnetic force attenuator typically comprises a material of high magnetic permeability, and modulates the magnetic attraction force between the magnet and the base of the motor.

Abstract: A motor damping structure for an actuator device includes a motor housing and a casing. The motor housing includes a drive motor therein. The casing includes an upper actuator case and a lower actuator case to accommodate the motor housing therebetween, the casing including a motor support section formed integrally in at least one of the upper actuator case and the lower actuator case to support the drive motor by contacting an outside surface of the motor housing. The motor support section has an elastic contacting member protruding from the at least one of the upper actuator case and the lower actuator case to contact one of an upper slanted surface and a lower slanted surface of the motor housing.

Abstract: A rotor for rotating an electric machine having permanent magnets and flux concentration, including a shaft extending along the rotational axis of the rotor, a rotor body placed on the shaft, the rotor body having a central opening for the mounting thereof on the shaft; radially oriented recesses wherein the permanent magnets are placed; and in at least one angular space separating two consecutive recesses, at least one cavity leading neither to the central opening nor to the two consecutive recesses, the cavity or cavities located in the space occupying an angular area around the rotational axis of the rotor greater than or equal to half of the angular area of the space.

Abstract: The invention relates to a rotary electric machine with an eccentric rotor that comprises a stator and an eccentric rotor, the stator including a plurality of magnetic poles circumferentially distributed in order to define a closed cylindrical space, the rotor having a generally cylindrical shape with a diameter lower than that of said closed space and including a plurality of magnetic poles circumferentially distributed, the rotor rotating inside the closed space, wherein the machine further includes a shaft depending on the rotational component of the rotor, said machine being characterised in that, at the area of electromagnetic interaction between the stator and the rotor, the evolute of a stator pole and the evolute of a rotor pole have substantially equal lengths.

Abstract: An electric motor includes a stator, at least one rotor, an output shaft engaged with the at least one rotor, and a contact area changing device configured to change an area of contact between the at least one rotor and the output shaft, wherein the area of contact between the at least one rotor and the output shaft affects a characteristic resonant frequency of the at least one rotor. A method to reduce vibrations in an electric motor includes engaging an output shaft into at least one rotor, rotating the output shaft and the at least one rotor with respect to a stator, changing an area of contact between the at least one rotor and a radial protrusion of the output shaft, and shifting the resonant frequency of the at least one rotor with the changed area of contact.