Abstract: An improved drum motor, preferably electronically commutated, features a unitary stationary central shaft (18) supporting a stationary inner stator (52), and an external rotor (49), including permanent magnets (54), secured to an inner surface of a generally cylindrical rotatable casing part (18). This permits variable speed operation while avoiding any need for an internal gear linkage. Safety is improved by making sealing plates (76, 78) at respective axial ends of the casing (14) stationary, and providing an annular peripheral seal (90) around each sealing plate. Respective rolling bearings (24, 44) near each end of the casing (14) facilitate rotation of the external rotor (49) relative to the stator (52), and a clamping arrangement (30) minimizes noise from the bearings.

Abstract: A vehicle alternator is disclosed as having a stator having a stator winding, a rotor carried on a rotary shaft and rotatably supported inside an inner periphery of the stator, an electric device involving a rectifier for converting an AC voltage, induced in the stator winding, into a DC voltage, and a protector cover for covering the electric device. The protector cover includes a cover body, placed in a position to cover the electric device involving the rectifier, and a cover convex portion extending outward from the cover body along an axis of the rotary shaft of the rotor. The cover convex portion has an inside formed with an open space in which no electric device is disposed.

Abstract: A fan housing. The fan housing mounted on a frame of a system includes a main body, a first section, a second section and a fixing portion. Both the first and second sections are disposed on the main body. A gap is formed between the first and second sections. The fixing portion is formed in the gap.

Abstract: A brushless electric motor which has a rotor magnet, a coil apparatus for electromagnetically driving the rotor magnet, a rotor shaft for transmitting a rotary movement, which is firmly connected to the rotor magnet and runs through a rotation axis of the rotor magnet, and at least one electromagnetic transducer element for detection of the magnetic field of the rotor magnet, in which the at least one electromagnetic transducer element is arranged outside the axial extent of the rotor magnet with respect to the rotation axis, and is arranged essentially within the maximum radial extent of the rotor magnet. The invention also relates to an instrument for a medical, in particular a dental, apparatus having a brushless electric motor such as this.

Abstract: To reduce the torque ripple of permanent-magnet excited synchronous motors (1) having tooth coils (6), constructive means are proposed for damping or eliminating the fifth and/or seventh harmonic wave of the rotor field which mainly cause torque ripple.

Abstract: A small power generating system includes a turbine driven by a fluid, a small high-speed rotation power generator including a permanent magnet rotor having a permanent magnet and rotated together with the turbine and a plurality of stator coils each of which is comprised of a coreless coil, the rotor being rotated such that voltage is induced on the stator coils, whereby power is generated by the power generator, and a back yoke disposed at one of two opposed sides of the stator coils which is opposed to the other side thereof further confronting the permanent magnet of the rotor, the back yoke being made of a magnetic material with a predetermined electrical resistance.

Abstract: The machine device comprises a motor (2) with a rotor (5) rotating about an axis (A), the superconducting winding of which is coupled with thermal conduction to a central refrigerant cavity (12). The cavity (12) forms a single-tube system, together with the line sections (22) laterally connected thereto and a condenser chamber (18) of a refrigeration unit, located outside the motor (2), in which a refrigerant (k, k?) circulates as result of a thermal siphon effect. According to the invention, the refrigerant supply to the central cavity (12) is maintained, even with inclined positions (d) for the rotor (5), whereby pressurization means are provided, which generate pressure pulses of gaseous refrigerant, acting on the liquid refrigerant (k) in the condenser chamber (18) or the connected line sections (22).

Abstract: An electric motor has a field assembly, such as a stator, for a dynamoelectric machine has field coils that are wound to a net shape. Lead wires are brought out from the ends of each field coil. The field coils are insulated with insulating sleeves or insulating slot liners. The field coils are assembled with stator core pieces, such as pole pieces and return path pieces, into the stator. The stator core pieces are formed prior to being assembled with the field coils. In an aspect of the invention, the pole pieces and return path pieces are separately formed and then assembled together with the field coils, which have also been separately formed.

Abstract: The magnetic flux generated by stator electrical winding can flow inside motor stator structure, so it is unnecessary to put the stator electrical winding and the rotor in the same medium. The stator and rotor can be separated by repositioning the dome of a hermetic (or semi hermetic) refrigeration (or air condition) system inside the motor. The rotor and compressor are sealed inside the dome and the stator electrical winding is outside of the dome or shell. The compressor powered by this induction motor design can be much safer and more reliable to operate even in more critical environment (like pumping and compressing poison, dangerous gas). It will also be easier to fix a motor with a detachable stator design.

Abstract: A fluid dynamic bearing motor features a stationary assembly, a rotating assembly supported on the stationary assembly, a fluid dynamic bearing system in a gap between the stationary and rotating assemblies, a radial capillary seal defined proximate a first end of the journal gap, and at least one re-circulation hole extending from the radial capillary seal to a second end of the journal gap. A single thrust shaft end bearing which pressurizes the shaft end to create an axial thrust bearing and drive bubbles in the fluid (where the fluid is a liquid) to the outer diameter of the shaft and into the recirculation path. The journal may be supported for rotation by dual sets of grooves; the dual groove asymmetry in the journal maintains a positive pressure between the journals.

Abstract: A stepper motor includes a rotor having equally spaced rotor teeth defining a full step angle, and a stator with stator poles wound with coils that can be driven in a series of phases so as to magnetically interact with the rotor to produce stepping motion. The stator poles have teeth organized into two groups when there is an even number of stator teeth per pole, or into three groups for an odd number of stator teeth per pole. The stator teeth have an average pitch different from the rotor's tooth pitch, but the groups of stator teeth are also displaced relative to other groups by a specified offset angle of one-half or one-quarter step to double the number of detent positions, and to displace such detent positions from full one-phase ON or two-phase ON positions.

Abstract: A spindle motor in one inventive implementation includes a rotor hub (10) for retaining a rotor magnet (70) and a stator (80) which is faced to the radial inner side of the rotor magnet (70) with a gap interposed therebetween. A shield sheet (90) is placed between the upper side of the winding (82) of the stator (80) and the disk mounting portion (13) of the rotor hub (10) and the outer peripheral edge of the shield sheet (90) is placed radially inside of the outer peripheral edge of the core back (83) of the stator (80).

Abstract: A permanent magnet type three-phase ac generator includes a stator having 3n (n is an integer) teeth and a tree-phase armature winding and a rotor having 4n magnetic poles each of which has a permanent magnet. The three-phase winding includes 3n coils each of which is wound around one of the teeth and connected to form three phase windings, and each coil wound around a first tooth is connected to another coil wound around another tooth that is fourth from the one of the teeth so that vectors of voltage induced in the connected coils can direct in the same direction.

Abstract: A self-cooled rotor for an electrical machine being internally provided with a cooling channel to carrying cooling fluid. The machine includes a further channel for carrying cooling fluid in proximity to a magnetic field generating means for cooling it, the two passages being connected to each other within the machine.

Abstract: A transfer apparatus includes at least four fine actuators each having a coil assembly with a wound coil, and a pair of movable magnets having different polarities and spaced from each other to interpose the coil assembly therebetween, a coil supporter to support the at least four coil assemblies so that the fine actuators are arranged in a pair of groups thereof symmetrically with respect to a predetermined straight line, a magnet supporter to support the at least four movable magnets corresponding to the respective coil assemblies, and a controller to control the fine actuator to move one of the coil supporter and the magnet supporter with respect to the other one. With this configuration, a transfer apparatus can perform a super-precision positioning control by decreasing a positioning control error.

Abstract: A commutator motor includes a stator and a rotor, and the stator includes a stator yoke and a field magnet. The field magnet is fixed onto the inner peripheral surface of the substantially cylindrical stator yoke. The stator yoke is configured by coaxially stacking a plurality of plate-like annular bodies, and the annular bodies are fixedly connected to each other by caulking at a caulking portion disposed on the annular body. In manufacture, the length of the stator yoke in the axial direction can be arbitrarily changed with the thickness of the annular body in the axial direction as a minimum unit. In case of manufacturing various stator yokes that are different in the axial length, the necessity of replacing a manufacturing machine is eliminated, thereby providing a commutator motor having the stator yoke which is low in the manufacturing costs.

Abstract: According to the disclosed motor, since the motor includes a rotor in which a plurality of core pieces and magnets are alternately arranged in the circumferential direction, magnetic flux of the magnets is prevented from flowing between the core pieces neighbored with each other in the circumferential direction and the leakage of the magnetic flux can be minimized. Since identical polarities of the magnets neighbored with each other in the circumferential direction face each other, the magnetic flux can be concentrated to the respective core pieces. Moreover, since the axial direction of the circumference of the core facing the stator in the circumferential direction is longer than the axial direction of other portions thereof, torque is increased and manufacturing costs are reduced.

Abstract: A movable assembly used in a cylinder type linear motor is provided which can be manufactured at low cost without requiring a cutting process while preventing its magnetic characteristics from deteriorating. The movable core is constructed of a laminated yoke which is formed of a plurality of electromagnetic steel plates laminated in an axial direction of the first and second direct drive shafts. A plurality of permanent magnets 31 fixed to the laminated yoke 29 are arranged in such a manner that the polarity appearing on the outer surface of the two permanent magnet 31 opposing each other through the laminated yoke 29. The first and second direct drive shafts each have a yoke mounting portion and paired supported portions at both axial ends of the yoke mounting portion. The first and second direct drive shafts are so shaped that the cross section of the yoke mounting portion orthogonal to the axial direction is smaller than that of the supported portions.

Abstract: A micro-electro-mechanical system (MEMS) power generator employing a plurality of magnetic masses disposed to oscillate on spring elements in a manner that produces an unusually steep flux gradient at one or more conductive coils, thereby harvesting a substantial portion of the available mechanical energy. The energy from ambient mechanical vibration is harvested to produce electrical power sufficient to power individual electronic elements for a variety of low-cost and high-performance distributed sensor systems for medical, automotive, manufacturing, robotics, and household applications.

Abstract: An improvement in high-speed and response performances is achieved with simple structure. A bed faces a movable table on which permanent magnets divided from each other in a stroke direction of the movable table are provided. One or more armature coils are provided on the bed facing the permanent magnets. Upon passage of an electric-current through the armature coils, an electromagnetic interaction between the armature coil current and magnetic fluxes of the permanent magnets produces a thrust force for relative movement between the two mobile units. A magnetic member is provided on the movable table in a position corresponding to a maximum point or a vicinity thereof of a magnetic force of the permanent magnets when the movable table is in a neutral position in the stroke direction. When the mobile units relatively move from the neutral position, the magnetic force of the permanent magnets acts on the magnetic member.