Showing papers on "Rotor (electric) published in 1977"

Self-excitation in inverter driven induction machines

Abstract: If the dc supply to a voltage source inverter driving an induction machine is removed, self-excitation as a result of circulating currents in the inverter can occur whenever the inverter switching frequency is below the machine speed. In this mode the inverter-machine system functions as a stable self-excited induction generator capable of supplying dc or ac power to a load. The electrical output of the system is readily governed by slip control; thus the inverter makes practical the development of efficient induction generators capable of operating over wide speed ranges. A theoretical treatment based on a first harmonic approximation of inverter performance is presented. The results indicate that the magnetization characteristic and the stator and rotor resistances of the machine are the important parameters controlling system performance. Experimental results which confirm the validity of the analysis and illustrate the behavior of the self-excited systems are also presented.

Centrifugal blood processing system

Abstract: A centrifugal blood processing system is disclosed having a rotor drive assembly that is rotatably mounted to a stationary base for rotation along a predetermined axis. A rotor assembly, which includes a blood processing chamber, is rotatably mounted with respect to the base for rotation about the axis. A flexible umbilical cable segment is provided for establishing fluid communication with the blood processing chamber. One end of the cable segment is fixed with respect to the base along the axis at one side of the rotor assembly while the other end of the cable segment is attached on the axis in rotationally locked engagement to the rotor assembly. Guide means are provided for causing the umbilical cable to rotate about the axis with the motor drive assembly. Means are provided for rotating the rotor assembly and the rotor drive assembly in the same direction with a speed ratio of 2:1 to prevent the umbilical cable from becoming completely twisted during rotation of the rotor.

Magnetic stirrer apparatus

Abstract: A lightweight magnetic stirrer apparatus which may be positioned for rotation in a fluid containing vessel, having a magnetic rotor assembly including a generally vertical center hub on which is mounted a generally horizontal magnetic impeller. The rotor assembly is rotatably mounted in a positioning cage which generally positions the rotor assembly within the vessel and prevents it from contacting the walls of the vessel to allow the rotor assembly hub to rotate free relative to the vessel in the cage under the influence of an exterior magnetic drive. The magnetic stirrer apparatus is also provided with a cage in which the legs are totally removeable so as to make it any size for different beakers. Furthermore, the magnet may be removed completely from the cage so that it may be dropped into the neck of a bottle and the magnet per se used by itself. High lubricity bearing surfaces of the hub and cage reduce frictional forces and allow rotation of the impeller at very low speeds.

Electrical drive device

Abstract: An electrical drive device comprising a stator arrangement of the claw pole type surrounding a stator chamber or compartment and producing therein at least one magnetic field containing at least one rotary field component. There is provided a permanent magnet-rotor arranged in such rotor chamber in such a manner that it rotates in synchronism with such magnetic field and a hysteresis magnetic coupling, the driving part of which is form-lockingly connected with such rotor and the driven part of which is force-lockingly secured to a shaft constituting the power take-off shaft of the drive device. The stator arrangement, the rotor, the driving part of the hysteresis magnetic coupling and the driven part of such coupling are all housed in a common housing.

Wind turbine apparatus

Abstract: The Specification discloses a segmented wind turbine which can be added to incrementally to increase the driving force and power generation of the machine. By this means the smaller diameter rotors that are more easily handled and that put the minimum of stress on the wind turbine apparatus can be used in series to achieve the power output desired. Each segment has a venturi means incorporated into the elements of the apparatus to enhance the apparent wind speed. Also disclosed are novel means for operatively supporting the moving parts of the apparatus. In a preferred embodiment an exoskeletal frame is made in segments that can be stacked one upon the other. Each segment of frame has arms which converge inwardly toward the axial center of the apparatus. There a hoop connects the ends of the inwardly converging arms and defines an axial aperture. Inside this axial aperture a segment of drive shaft and a concentric collar are supported by thrust bearings which are in turn supported by the concentric hoop attached to the arms of the frame. Each set of arms and the associated bearings support the drive shaft, a rotor on the drive shaft, and a wind shield surrounding the rotor immediately above the arms. The wind shield is of a novel structure, having two spaced side walls which define openings for receiving wind through the rotors and discharging the wind. One of the walls forms a venturi with the rotor.

Noise Produced by Turbulent Flow into a Propeller or Helicopter Rotor

Abstract: than can be applied to calculate the instantaneous sound spectrum produced by the rotor at each azimuthal rotor position, and this instantaneous spectrum can be averaged over the azimuthal rotor position to find an averaged far-field sound spectrum. In taking this average, account must be taken of the different amount of retarded time that the rotor spends at each azimuthal rotor position. Further discussion of this point is given in another paper.4 A further factor taken into account in the analysis is the existence of blade-to-blad e correlation. If a given turbulent eddy is chopped by more than one rotor blade, the blade-toblade correlation leads to narrow-band noise peaked around the rotor harmonics. The far-field sound for an airfoil moving in rectilinear motion through a turbulent flow can be expressed in terms of a single wavevector component of the turbulence. The presence of blade-to-blade correlations requires that the single wavevector component be replaced by a summation over several wavevector components. This summation generally is carried out numerically for the calculations presented herein, but, if the frequency of interest is high enough, the summation can be replaced by an integral that can be evaluated in closed form; i.e., the blade-to-blade correlation becomes unimportant, and the result reduces to that for a single blade in rectilinear motion. The preceding description of the procedure for calculating the far-field sound applies to the sound produced by a spanwise segment of the rotor. This segment must have a spanwise dimension small enough so that the velocity does not vary significantly over the segment but large enough so that the loading correlation from segment to segment is not significant. This latter assumption is consistent with the highfrequency assumption mentioned previously, since high frequency corresponds to small correlation length. Thus, to find the noise contributed by the entire rotor, an integral over span must be performed.

Brushless d-c motor system

Abstract: To provide for efficient operation and recuperation of stored inductive energy in a pulse-operated motor, a preferably bifilar winding (20, 21; 20', 21') has its respective strands or filaments energized by complementary transistors (57, 58; 69, 75; 80, 81) which have reversely polarized free-wheeling diodes (59, 60; 80", 81") connected thereacross. A coupling capacity (47) is connected between the junctions of the respective transistors and the associated winding so that, upon turn-off of a transistor, as controlled by a rotor position sensor, such as a Hall generator (25), stored electromagnetic energy is coupled to flow through the free-wheeling diode of the transistor then to be connected, to be returned to a d-c source, such as a battery (34) or stored in a storage capacitor (45). The output signal from the rotor position sensor is in binary, high-low form, which can control the complementary transistors.

Synchronous machine with inner rotor, excited by permanent magnets

Abstract: A synchronous machine including a rotor having at least two lamination substacks, between which are arranged support disks of nonmagnetic material which are firmly mounted on the ferromagnetic rotor shaft. Each substack includes in the circumferential direction lamination stack parts whose number corresponds to the number of poles of the machine. Each substack further includes a ferrite magnet arranged between its lamination stack parts, and the ferromagnetic rotor shaft. The lamination stack parts and the support disks are held together in a frictionally connected and tight fitting manner by means of axial bolts.

Hall effect shaft angle position encoder

Abstract: A Hall effect shaft angle position encoder is constructed using a plurality of magnetic elements independent of any magnetic rotor of the electrical device which may be a brushless motor or brushless tachometer. The plurality of magnetic elements has serially alternating polarities of magnetic north and south with at least one Hall effect sensor mounted in spaced and confronting relation with the magnetic elements for sensing the alternating polarities and producing output signals representative of the magnetic polarities where the signals include a ramp voltage passing through zero value. The magnetic elements are secured to the rotor outside the normal rotor elements of the device. The output signals from at least one Hall effect sensor are applied to amplifying means which may be an operational amplifier and through the use of a variable reference voltage varying in magnitude and polarity, the output voltage is shiftable to provide signals differing in phase from the Hall effect sensor output signals in accordance with the variable reference voltage polarity and magnitude.

Gas turbine engine having bleed apparatus with dynamic pressure recovery

Abstract: A gas turbine engine has conduits leading from the compressor to the turbine for bleeding a portion of compressor air through the turbine blades for cooling or other purposes. A radial pump in the conduits formed by a tangential accelerator and a rotating diffuser transmits the air from the non-rotating environment in the engine to the rotating environment of the turbine rotor. The tangential accelerator accelerates the bleed air to a tangential speed higher than that of the rotor, and the radial diffuser is designed to recover the dynamic pressure or relative velocity of the air over the rotor.

Self-supporting amortisseur cage for high-speed synchronous machine solid rotor

Abstract: A self-supporting amortisseur winding in the form of a thin copper cage is situated about the solid rotor of a high-speed, permanent magnet synchronous machine in order to keep commutating reactance low. A high-strength wire is wound, with high tension, circumferentially about the cage to counteract the effects of centrifugal force on the cage when the machine is operating.

Ultrasonic transducer probe

Abstract: An ultrasonic transducer probe having a sealed rotor housing, a plurality of transducers mounted on a rotor disposed in said housing. A rotor shaft mounts the rotor and extends through the housing. A drive assembly including commutating and position indicating means receives said housing and rotor shaft and serves to drive the rotor, commutate electrical energy to and from said transducers and indicate the angular position of said rotor. A handle including means for driving said drive assembly is attached to said drive assembly to position the rotor housing and drive assembly against the body the rotate said rotor to cause the transducers to scan a sector of the body.

Helicopter antitorque system using circulation control

Abstract: An antitorque system for use in a helicopter produces antitorque moments with efficiency comparable to that of the tail rotor it is designed to replace. The antitorque forces are generated mainly from the main rotor downwash by the circulation control effect. The downwash is deflected laterally as it passes around the tail boom by a sheet of air continuously discharged tangentially to the surface of the tail boom on one side of it at velocities in the range 30 to 120 meters per second from slots extending longitudinally along the tail boom and having a width in the range 4 to 20 millimeters. The discharged air is supplied by a relatively low-pressure-ratio fan within the fuselage which directs a stream of air rearwardly into the tail boom. The tail boom is provided at its rear end with a laterally disposed aperture through which some of the fan-supplied air is discharged to create a direct jet thrust. The flow through the aperture is throttled to vary the antitorque moment for trim and maneuvering.

Composite seal for turbomachinery

Abstract: A gas path seal suitable for use with a turbine engine or compressor is provided. A shroud wearable or abradable by the abrasion of the rotor blades of the turbine or compressor shrouds the rotor blades. A compliant backing surrounds the shroud. The backing may be made of corrugated sheets or the like with adjacent layers having off-set corrugations, with axes of the folds parallel to the rotor axis. The sheets may be bonded together at points of contact by brazing, welding or the like. In another embodiment a compliant material is covered with a thin ductile layer. A mounting fixture surrounds the backing.

High torque stepping motor

Abstract: The invention provides a high torque bidirectional stepping motor. Toothed rotor and stator assemblies having pole pieces sandwiching annular permanent magnets and solenoid coils, respectively, are disclosed. Pulsing means for activating the motor are also disclosed. Adjacent rotor assemblies are misaligned in disclosed fashion to provide fractional notch stepping in response to sequential control pulses from the pulsing means.

Turbine rotor and blade configuration

Abstract: A rotor for compressors, turbines or the like and having a plurality of circumferentially-spaced blades in which every other blade is modified so that the average natural frequency of said modified blades differs from that of the other blades by at least 4% but by no more than 15% so as to reduce the maximum amplitude of turbine blade vibration

Lift augmenting device for aircraft

Abstract: A lift augmenting device to provide a vertical take-off capability in aircraft which includes a pair of rotor assemblies with independently individually pivoted rotor vanes so that the attitude of the vanes can be changed at different positions along the circumferential rotational path of the vanes as they rotate with the rotor assemblies to pump air therethrough and selectively generate lift on the aircraft.

Vertical-axis windmill

Abstract: A vertical-axis windmill of the Darrieus type, having much improved power output for a given rotor diameter. The rotor is surrounded by fixed upper and lower contours separated by radial stator vanes. These fixed elements cause an increase in speed of the wind as it impinges on the rotor, with a consequent power increase. The stator vanes and the airfoils of the rotor are easy to manufacture, being straight and untwisted, with constant symmetrical cross sections. The base of the rotor provides a large diameter surface of high peripheral speed for mounting magnets or coils to generate electricity efficiently.

Quantitative Density Visualization in a Transonic Compressor Rotor

Abstract: The flow in a 59-cm-diameter high-work transonic compressor rotor has been visualized using a fluorescent gas, 2,3, butanedione, as a tracer. The technique allows the three-dimensional flow to be imaged as a set of distinct planes. Quantitative static density maps were obtained by correcting the images for distortion and nonlinearities introduced by the illumination and imaging systems. These images and maps were used to analyze the three-dimensional nature of the blade's boundary layer and shock system.

Rotor-shaft assembly

Abstract: A rotor-shaft assembly comprising a ceramic turbine rotor, a metal shaft and a metal connector disposed between the rotor and the shaft. The metal connector is fixed to the rotor by some suitable means and coupled with the metal shaft by mutual engagement of teeth provided at the ends of the connector and the shaft.

Multistage Axial-Flow Turbomachine Wake Production, Transport, and Interaction

Abstract: To aid in the understanding of rotor and stator viscous wake interaction, slowand fast-response instrumentation has been employed to obtain time-average and instantaneous periodic-average flowfield measurements between the blade rows in a low-speed multistage axial-flow compressor. Quantitative measurements indicate that the rotor blade wake pattern can vary significantly when influenced by an upstream stationary blade row, and that relative circumferential positioning of the stationary blade rows can have considerable influence on downstream rotor and stator flowfields. Differences in aerodynamic and acoustic characteristics resulting from changes in unsteady wake interaction patterns were observed.

Rotor blade inspection fixture

Abstract: An apparatus for measuring the contour of rotor blades is provided. The apparatus or fixture of the present invention will measure airfoil shape and twist at any spanwise station along a rotor blade as well as measuring the chordwise and flapwise bow of the rotor blade. The fixture includes a base to which the blade is secured. A plate or templet like device is placed about the blade. The plate is secured to a carriage which is movable along the base so that it may traverse the blade along its span. Transducers connected to the plate measure the airfoil contour at particular spanwise stations. The plate is mounted to the carriage in such a manner that its rotation, vertical, and horizontal displacement may be measured and hence the twist, chordwise and flapwise bow may be determined.

Line flow electric power generator

Abstract: An electrical power generator employing a helically-vaned in-line rotor in a flow line as a prime mover means and as an integral part of the generator by effecting a cyclic variation in the density of permanent magnet generated flux fields which pass through fixed coil windings. Output voltage magnitude varies with rotor rotation rate which, in turn, varies as the flow rate of gas and/or fluid in the line.

Limited rotation motor

Abstract: A limited rotation motor has a stator and a rotor mounted for limited rotation relative to the stator. The stator is constructed to conduct bias flux through magnetic circuits that extend across air gaps between the stator and the rotor and a drive system produces drive flux which is conducted through magnetic circuits that extend across air gaps between the stator and rotor to drive the rotor. The stability of radial rotor position in its support bearings is enhanced by an imbalance in the bias flux magnetic circuits which continually produces a resultant radial force on the rotor so that a well defined radial position of the rotor is maintained over the range of limited rotation that the rotor moves in response to the drive system.

Alternating current power generating system

Abstract: A system for generating alternating current of selected voltage at a target frequency includes a plurality of A.C. generators, at least one of which has a rotatably mounted stator. A prime mover drives a power input shaft at speeds extending through a wide range and the shaft is connected to the first rotor. As speed increases, the generator reaches the desired frequency and a sensing device releases the stator to rotate and maintain a relative speed between itself and the rotor corresponding to the target frequency. The stator drives the second rotor at its own absolute speed which is the difference between the power input shaft speed and the relative speed between the first stator and rotor. A field control maintains the desired voltage and a load control transmits the current output to a load and varies the load to maintain the generator at proper operating condition.

Stress protection for permanent magnet type synchronous motor

Abstract: A rotor of a permanent magnet type synchronous motor comprises a rotary shaft, a rotary supported by the rotary shaft and including an alternate disposition of a core section in the form of a lamination of a magnetic material which is stacked in the axial direction and a reinforcement section of a non-magnetic material and cavities axially formed in the core and reinforcement sections by passing therethrough, permanent magnets received in the cavities, and a strap interposed at least between the radial outer surface of respective permanent magnets and the opposing inner wall of the cavity, whereby distribution of pressures resulting from a centrifugal force due to the rotation of the rotor, which pressures are imparted on the inner wall of the cavity by the outer surface of the permanent magnet, is uniformed or shared by the strap, thereby preventing the permanent magnet from being fractured

Hand cranked electrical power source

Abstract: A hand-cranked power source intended for use in emergency situations to grate electrical energy. The power source features a lightweight construction as well as the ability to generate a reasonable amount of power. The preferred embodiment couples an input drive shaft to a harmonic drive system having a high speed output shaft. Upon the output shaft are preferably mounted samarium cobalt magnets forming the rotor of a three phase alternator. The output of the alternator may be utilized to power a field device, such as a radio, or the like, or may be used to charge fast-charging batteries.

Impeller mower-conditioner rotor

Abstract: A tractor drawn and powered impeller mower-conditioner includes a transverse cutter bar comprising a series of pairs of side-by-side contra-rotating cutting disks. An impeller rotor with free swinging flails is mounted above and slightly to the rear of the cutter bar with its axis of rotation parallel to the cutter bar. A hood over the rotor includes a confining forward conditioning plate conforming fairly closely to the rotor periphery to form a conditioning zone and a rearwardly extending deflecting and windrow forming portion. The rotor is disposed and rotated so that the flails intercept cut material delivered rearwardly by the cutter bar and carry it, inside the hood, up and over the rotor through the conditioning zone to be discharged rearwardly into a windrow. The flow of cut material from each pair of disks tends to be concentrated into a rearwardly directed stream by the bite or convergence of the contra-rotating disks. The distribution of flails on the rotor is locally concentrated so that a center of flail concentration is longitudinally aligned with each concentration of material flow so that all material received by the rotor gets approximately uniform treatment.