Showing papers on "Rotor (electric) published in 1973"

Rotating electric machine with reduced cogging

Abstract: A rotating electric machine of the multipole type which has a permanent magnet rotor magnetized in such a way that the number of stator salient poles is less than the number of permanent magnet poles. The machine has a smaller cogging force and is easily manufactured. The cogging force is made smaller by shaping both sides of the periphery of each stator salient pole. The ratio of the number of the stator salient poles to the rotor permanent magnet poles is such as to make the rotation of the rotor smooth in spite of variations in the magnetization of the permanent magnet rotor poles.

Static Exciter Stabilizing Signals on Large Generators - Mechanical Problems

Abstract: Torsionalvibrations have been observed on large thermal units with both static exciters, and stabilizing signals based on shaft speed measurement. Studies of transfer functions of round rotor machines and mechanical modes of torsional oscillation of a 500 MW turbo-generator, have led to a solution based on derivation of the stabilizing signal from a speed measurement close to the node of the first torsional mode. New arrangements have been designed and installed on four units now in service.

Wheel speed sensor

Abstract: A wheel speed sensor including a rotor and a stator with the stator being coaxially disposed within an elastomeric member for incremental axial movement upon engagement with the rotor. The stator includes a pole member, a bobbin and coil assembly, and a magnet which are axially aligned to provide an elongated stator structure which is coaxially disposed in a tubular member which guides the incremental axial movement of the stator. A method for prestressing the elastomeric member for setting the required applied force for axially moving the stator.

Inclusion of Rotor Dynamics in Controller Design for Helicopters

Abstract: State-feedback-controllers and state-estimators (filters) are designed for the roll-pitch-horizontal motions of a helicopter near hover, using a new quadratic synthesis technique. One model (tenth order) uses a dynamic model of the rotor, whereas the other model (sixth order) assumes the rotor can be tilted instantaneously. It is shown that, for tight control, neglecting the rotor dynamics in designing the autopilot can produce unstable closed-loop response on the model that includes rotor dynamics. Two filters are designed to use only fuselage sensors and two are designed to use both fuselage and rotor sensors. It is shown that rotor states can be estimated with sufficient accuracy using only fuselage sensors so that it does not seem worthwhile to use rotor sensors. The mean square response of the vehicle to a gusty, random wind, using several different filter/state-feedback compensators, is shown to be satisfactory.

Rotary slide valve

Abstract: Ceramic disks, rotor and stator, each with two apertures located symmetrically in opposite quadrants and each having one optically flat surface in contact at an interface, are combined with associated elements within a cylindrical cartridge, the stator sealed to the open end of the cartridge, the rotor subject to rotation in the claws of a clutch driven by a control shaft sealed through the opposite closed end of the cylinder and by means of which the rotor may be turned to align the apertures, opening a passageway through the interface, or rotated 90 DEG from that position to close the passageway. Ports in the cylinder wall adjacent to the rotor provide exit passage from the cylinder. A limit washer with two lugs is keyed to the control shaft and limits rotation to one quarter turn, 90 DEG , by interference of the lugs with two stops on the closed end of the cartridge. The keys are 45 DEG removed from the lugs on the limit washer; consequently a "left-hand" valve is convertible to a "right-hand" valve (and vice versa) by turning the limit washer face over face.

Collector-less D-C motor

Abstract: A permanent magnet rotor operates within the air gap of a stator magnetic circuit which has a stator winding. Current through the winding is controlled by a selectively energized semiconductor switch, which is energized over a portion of rotor rotation and in synchronism therewith. The air gap included in the magnetic circuit is non-uniform along its length, increasing to a maximum intermediate the extent of a pole, for example between 10 to 50 electrical degrees, and then decreasing to a minimum over the remainder to 180 electrical degrees over a pole. The winding is energized to cause rotation of the rotor while the permanent magnet is within a predetermined angular range, resulting in storage of magnetic energy which is released as torque upon further rotation of the rotor in another angular range. The timing of energization of the winding by a control circuit can be used to control motor speed.

Brittle Materials Design, High Temperature Gas Turbine

Abstract: : The demonstration of uncooled brittle materials in structural applications at 2500 F is the objective of the 'Brittle Materials Design, High Temperature Gas Turbine' program. Ford Motor Company, the contractor, will utilize a small vehicular gas turbine while Westinghouse, the subcontractor, will use a large stationary gas turbine. A significant achievement in the vehicular turbine project was the successful engine test, 175 hours at 1930 F, of a silicon nitride stator. Durability testing on a nose cone was extended to 246 hours, equalling the previously demonstrated durability of 245 hours on 1st and 2nd stage rotor tip shrouds. A 'Refel' silicon carbide combustor previously demonstrated 171 hours durability, crack-free, including 20 hours at 2500F. Two additional combustors of the same material were tested for 10 hours each. Eight hours of testing the stationary ceramic flowpath at 2500 F were accumulated; non-catastrophic cracks occurred in the nosecone and stator after surviving three hours crack-free. Two stator vanes survived 1000 cycles to 2500-2600 F plus 3720 cycles to 2900 F in the thermal shock rig. A concentrated effort on turbine rotor fabrication development was initiated. Improvements in the rotor fabrication processes have been made. Reduction of the MgO content increased the hot strength of the hot-pressed silicon nitride rotor hub material. Over 500 rotor blade rings were fabricated using the injection molding process and some high density rotor blade rings were also fabricated by slip-casting.

Fluid actuated down-hole drilling apparatus

Abstract: A hydraulic drilling motor connectable to a drilling string of drill pipe thereabove and a drill bit therebelow for drilling a bore hole in the earth, the motor having a hollow rotor connected to a hollow drive shaft for attachment to the drill bit, the rotor being rotatable in a stator or housing fixed to the drilling string, the rotor passage being closed automatically by a valve when liquid or other fluid is pumped through the motor to produce rotor and shaft rotation, the valve automatically opening in the absence of pumping fluid through the motor to permit fluid to drain from the drilling string during its elevation with the motor in the bore hole, or to automatically fill with fluid during its lowering with the motor in the bore hole. Drilling weight is transferred from the non-rotating drilling string and housing to the drive shaft through an oil filled bearing section, the oil in such section being maintained at a higher pressure than the pressure externally of the section to retain the oil or other lubricant in a clean state.

A High-Capacity Annular Centrifugal Contactor

Abstract: A centrifugal contactor of unique design has been developed for solvent extraction processing of high-plutonium-content fuels. The unit has a vertically suspended rotor that has a 4-in. inside diam...

Method for producing rotor discs

Abstract: The production of rotor discs by bonding a plurality of fully dense, preformed blades to a hub of compacted alloy powder. The blades are embedded in the uncompacted powder and by the use of hot isostatic compacting the powder is compacted to full density to form the hub and the blades are bonded thereto simultaneously.

Dynamic Models of Turbine Generators Derived From Solid Rotor Equivalent Circuits

Abstract: A method is described for determining the structure and coefficients of dynamic models of turbogenerators from detailed equivalent circuits of the d-and q-axes of a solid rotor generator. These models are intended for analyses of power system dynamics in cases where it is desirable to have a very accurate representation of the synchronous machine. The models have been used to study power system hunting or dynamic stability, first swing or transient stability, load rejection overvoltages, resynchronization of cross-compound turbine-generator sets, field current and voltage during out-of-step operation, voltage dip and other phenomena associated with machine operation on power systems. The paper reviews some of the experience obtained in system studies and in comparisons between test results and computer simulations.

Rotor assembly for permanent magnet generator

Abstract: A permanent magnet generator rotor assembly having a sintered cobalt alloy magnet integral with a ferromagnetic hub or shaft. To assure that the magnet develops maximum magnetic energy, the magnet is separated from the ferromagnetic hub or shaft by a high temperature material such as aluminum oxide (a ceramic).

Permanent magnet motor

Abstract: The invention is directed to the method of utilizing the unpaired electron spins in ferro magnetic and other materials as a source of magnetic fields for producing power without any electron flow as occurs in normal conductors, and to permanent magnet motors for utilizing this method to produce a power source. In the practice of the invention the unpaired electron spins occurring within permanent magnets are utilized to produce a motive power source solely through the superconducting characteristics of a permanent magnet and the magnetic flux created by the magnets are controlled and concentrated to orient the magnetic forces generated in such a manner to do useful continuous work, such as the displacement of a rotor with respect to a stator. The timing and orientation of magnetic forces at the rotor and stator components produced by permanent magnets to produce a motor is accomplished with the proper geometrical relationship of these components.

Electric pulse motor

Abstract: The disclosure relates to an improved electric pulse motor having an arrangement wherein, with respect to a rotor element having a number of rotor-teeth, a stator assembly including a number of geometrically and electrically paired laminated U-shape stator elements is assembled based upon the conventional arrangement, but, the rotor element is provided with a specific construction for strengthening the rotor-teeth, so that radially extended rotor-teeth are reduced in axial thicknesses so as not to increase moment of inertia, making it possible to obtain a large magnetic attractice force from the stator elements so as to provide a large output torque.

Control means for electrically powered transportation means

Abstract: A steering control for an electrically powered vehicle having a pair of traction wheels on each side of the vehicle's frame, each of said wheels being driven by a synchronous type motor. The rotor field producing coils of each motor being separately controlled by the accelerator control of the vehicle and a frequency changing circuit which selectively changes the rotational speed of individual motors. The frequency changing circuit includes frequency divider switches and frequency counters connected to the rotor field producing coils; the wipers of said frequency divider switches are connected to the steering control in such manner as the output of each frequency dividing counter is varied independently. A battery included in such vehicle for producing electric power needed for the motors can be charged by a generator or alternator. Current from the battery to each motor is pulsed, and energy charging the battery from the generator or alternator is also pulsed, the latter pulses being interposed in time between the pulses from the battery to the motors. Steering sensitivity may be changed with an increase in speed by linkage between the accelerator and the frequency divider switches, so that as the speed of the vehicle increases, its turning radius is also changed in response to a given arc of turn of the control steering.

Rotary forming unit for fine mineral fibers

Abstract: An improved apparatus for the formation of fine fibers from mineral materials, especially glass, in which molten material feeds continuously into a rotor turning at high speed, and discharges by centrifugal force thru multiple orifices in the outer peripheral rotor wall as fine filaments, and with hot gaseous means to control the temperature of the zone immediately beyond the rotor outer wall. This invention specifically concerns improvement in the rotor unit itself. The rotor is preferably built with a main structure of base metal, and an outer peripheral wall of precious metal with filament forming orifices therein. Means are provided to reduce centrifugal forces on the outer wall to permit using relatively weak platinum alloys, and larger diameters than presently used, and attaining the additional advantages of longer life and more uniform filaments. A closely spaced inner wall with platinum metering orifices insures uniform feed, permits using larger orifices for longer wear. Insulating means provided to shield the rotor parts from heat loss to cool rotor shaft, and uniform temperature of inner rotor parts is assured. Alternately outer wall may be base metal clad with platinum. The invention applies to and is continuationin-part of my Ser. No. 231,347. In former application the rotary apparatus had improved outer attenuation blast, the elements of the annular blast having directional control, each element having a component of velocity tangential to and in the same direction as the rotor outer wall. Subject invention applies to this system, and as well to those systems well known in the art in which the filaments leaving the rotor outer wall are further attenuated by an annular gaseous blast, the gases being air, steam, or products of combustion.

Leading edge serrations which reduce the noise of low-speed rotors

Abstract: Acoustic effects of serrated brass strips attached near the leading edges of two different size rotors were investigated. The two bladed rotors were tested in hover. Rotor rotational speed, blade angle, serration shape, and serration position were varied. The serrations were more effective as noise suppressors at rotor tip speeds less than 135 m/sec (444 ft/sec) than at higher speeds. high frequency noise was reduced but the low frequency rotational noise was little affected. Noise reductions from 4 to 8 db overall sound pressure level and 3 to 17 db in the upper octave bands were achieved on the 1.52 m (5.0 ft) diameter rotor. Noise reductions up to 4 db overall sound pressure level were measured for the 2.59 m (8.5 ft) diameter rotor at some conditions.

Shroud structure for turbine rotor blades and the like

Abstract: An improved honeycomb shroud for rotor blades for turbines and similar devices, wherein the rub-tolerance of the shroud is increased by making the honeycomb less rigid and more resilient and yieldable at the potential rubbing surface, with added strength at the region of attachment to the support member.

Magnetically mounted rotor

Abstract: A rotational magnetic device, such as those used in flywheels, includes a stator and a rotor. A plurality of permanent magnets are mounted on the rotor, arranged around the circumference of the rotor and alternating in polarity along the circumferential direction. A plurality of windings are arranged on the stator within the magnetic field produced by the permanent magnets. Current which is supplied to these windings produces forces on the rotor which control the positioning and movement of the rotor. This arrangement provides for a rotational magnetic device in which the drive mechanism and the bearing are combined into a single unit and the rotor can be freely suspended in any desired position so that it is in effect magnetically mounted.

Hydrostatic transmission control system

Abstract: An improved straight tracking control system equalizes the output speeds of a pair of hydrostatic transmissions during straight forward movement of a vehicle. The control system includes a pump assembly having a housing which is rotated at a speed which varies as a function of variations in the speed of one of the tracks of the vehicle. This housing defines a pumping chamber in which a rotor is rotated at a speed which varies as a function of variations in the speed of the other track of the vehicle. When the vehicle is moving straight forward and the two tracks are being driven at the same speed, there is no relative rotation between the rotor and housing so that the pump assembly is ineffective to pump fluid. Upon acceleration of one of the tracks relative to the other and a resulting relative rotation between the housing and rotor, the pump assembly is effective to discharge fluid under pressure to a piston and cylinder assembly. This fluid actuates the piston and cylinder assembly to operate a valve. Operation of the valve ports fluid to an actuator assembly to vary the output speed of one of the hydrostatic transmissions in a manner so as to equalize the output speeds of the two hydrostatic transmissions. In one embodiment of the invention, a second piston and cylinder assembly is actuated to vary the output speed of a second hydrostatic transmission after the first piston and cylinder assembly has been actuated to vary the output speed of the first hydrostatic transmission.

Identification of principal factors causing unbalanced magnetic pull in cage induction motors

Abstract: The precise effect of the static eccentricity of the rotor of an induction machine on the magnetic field in the airgap is demonstrated and explained. The relation between the unbalanced pull and the eccentricity of a cage rotor is determined through measurements of the electromagnetic field at the rotor surface, and the significance of the tangential-flux component in the machine airgap is assessed.

Electromagnetic bearing means

Abstract: A contact-free bearing system for radially supporting a rotor, rotatable at high speed, with respect to a stationary member comprises a magnetic system including electromagnetic bearings. The electromagnetic bearings includes an endless ferromagnetic core carrying a spiral or toroidal winding which includes or acts as at least three separate coils. Electrical signals, dependent upon the radial deviation in the position of the rotor from a predetermined position are applied to said winding such that the coils produce magnetic fields which are applied to the rotor and are of different magnitude or direction.

Centrifuge rotor cover

Abstract: There is disclosed a cover for a centrifuge rotor which is affixed thereto by being screwed onto the hub of the rotor. The cover is constructed in a manner to provide a depending skirt which seats against an upstanding rim of a rotor of a centrifuge. This cover is constructed to seat tighter under the centrifugal forces encountered whereby a portion of the skirt is urged outwardly and down against the seat on the rim. The cover is also designed to have an annular well for collecting small quantities of overflow fluid. The cover is also consructed with a means to preliminarily provide communication between the outside and inside the rotor of the centrifuge in order to establish equilibrium therebetween prior to removal of the cover.

Instrument hub for the measurement of forces and/or moments

Abstract: An apparatus and method for measuring forces and/or moments acting on a rotor whereby a hub having a plurality of beams forming right angles with each other and resiliently deformable is attached to a rotor. A strain gauge is preferably attached to each beam and the strain gauges in turn connected in a Wheatstone bridge circuit. The beams preferably connect inner and outer cylindrical members and form a cross, rectangle or square.

Electrostatic rate gyroscope

Abstract: A two-axis rate gyroscope of the captured type is provided having a "Saturn-shaped" rotor disposed within a sealed housing. The interior of the housing is evacuated to a "hard" vacuum and an electrostatic suspension system is provided for the rotor, so that the rotor has a virtually frictionless spin bearing. An electrostatic capture system is provided to null rotor rotation with respect to the housing about the two precession axes of the gyroscope. The capture electrodes of this system are mounted on a cup-shaped support member which is mounted for limited rotational movement about two perpendicular axes which are parallel to the gyroscope precession axes and vibrating beam force transducers are connected between the support member and the housing to sense the reaction torque exerted by the capture system during capture, so that the output signals from the transducers provide two-axis rate information. The capture system also includes an axis coupling circuit which is responsive to rotor spin speed and which causes the capture system to act as a direct-coupled positional servomechanism at low rotor speeds to erect the rotor during gyroscope start-up. When the rotor reaches full speed, the capture system acts as a quadrature coupled servomechanism to null the rotor and produce a rate output.

Watch movement driven by a spring and regulated by an electronic circuit

Abstract: An electronically regulated watch movement comprising a time-wheel mechanism driven by a drive, a generator being coupled to the drive via at least a portion of the time-wheel mechanism and with substantial gear reduction. The generator includes a rotor with magnets and coils for producing a.c. voltage at a frequency of operation FG. An electronic regulating circuit is connected to the generator and includes an oscillator for producing a precise reference frequency FR and a comparator having inputs receiving frequencies FR and FG to compare the same. A power source is connected to the comparator and the generator to supply current to the generator when FG > FR to brake the generator until FG = FR and thereby provide a regulated operation of the time-wheel mechanism.

Rotational angle transducer

Abstract: A contactless rotational angle transducer for developing an output signal indicative of the angular position of a rotatable object comprising a fixed stator plate having a plurality of electrically isolated sector members, a parallel spaced-apart confronting plate, and a sector rotor plate situated between the stator and confronting plates and rotatably coupled to the rotatable object. An AC excitation voltage is impressed at a fixed phase relationship on each sector member such that the voltage induced in the confronting plate is a function of the angular position of the rotor plate. A pulse generator circuit responsive to the relative phase difference between the voltage induced on the confronting plate and the applied excitation signal develops a pulse-width modulated or pulse-positionmodulated output signal indicative of the angular position of the rotatable object, wherein the number of complete or partial turns of the rotatable object can be measured.

Process for making a rotor assembly

Abstract: A process for making a rotor assembly for a permanent magnet generator. The rotor assembly comprises a ferromagnetic hub and a ring-shaped cobalt and rare earth alloy magnet which is mounted on the hub. The process for making a rotor assembly includes applying to a hub a coating of inert material having a melting point above the sintering temperature of the cobalt alloy magnet before pressing and sintering the cobalt alloy onto the ferromagnetic hub.

Lubricating and sealing system for a rotary power plant

Abstract: In a power system including a shaft driven by expanding a working fluid in a turboexpander and a housing surrounding the shaft and the rotor of the turboexpander, a seal is provided between a process zone containing the rotor and a lubricant zone by injecting a seal fluid into the housing between the two zones at a relatively high pressure. The seal fluid is preferably comprised of the lightest constituent of the working fluid, and the system includes means for recovering the seal fluid from the lubricant and from the working fluid and recycling it.

DC brushless motor

Abstract: A DC Brushless motor comprising a rotor comprising a permanent magnet, a field coil for producing torque for rotation of said rotor, and Hall generators for detecting a rotational position of said rotor. Two Hall generators are arranged in the periphery of the rotor in a spaced relation of 90*. The field coil comprises two coils connected in parallel with a power source. To produce a torque by means of said respective coils to successively rotate the rotor in the same direction, a driving means is provided to serve to flow an exciting current in a reverse direction by displacement of phase by 180* in the same coil. This driving means is adapted to control a direction of current flowing in the coil by an output of said Hall generators. To maintain a rotational speed of rotor at a constant rate, there are provided means for detecting number of revolution of rotor and speed control means which produces a signal for a constant speed control comparing output from said detector with a reference signal.