Showing papers on "Magnetic circuit published in 1976"

Method of manufacturing a curved component of a magnetic circuit

Abstract: Identical strips of magnetic metal having alternating slots and pole teethlong one edge are cut from sheet material in a pattern minimizing waste of metal, stacked, and bent into a cylinder or sector of a cylinder. The ends of the stacks are then fastened together to form a rotor or stator.

Eddy-current test probe utilizing a combination of high and low reluctance materials to optimize probe sensitivity

Abstract: A coil of insulated wire surrounds a low reluctance core A combination of low reluctance and high reluctance materials positioned adjacent said coil: (1) control the spatial extent of the magnetic flux and, (2) concentrate the total reluctance of the magnetic circuit of the exciting coil into a volume of controlled size and shape within the material being tested The magnetic flux is controlled, and the reluctance is concentrated, in such a manner as to optimize the sensitivity of the eddy-current generator to variations in the material being tested; at the same time, the coil impedance is maintained at a value which is optimum for the performance of any selected precision electrical impedance measuring device

An analytical design theory for field-access bubble domain devices

Abstract: This paper describes the derivation and applications of an analytical model for magnetic bubble domain propagation. A fleld-access bubble device is treated as a magnetic circuit, emphasizing fluxes rather than fields as in most previous treatments. The energy changes are calculated within the bubble domain rather than in the propagation pattern, making possible a simple analytical-graphical process for predicting device operating margins. Agreement with a large number of device experiments is shown to be good. Closed-form expressions are derived which relate the essential features of the operating margin to device geometry and bubble material magnetic properties. The application of this model to device diagnosis, optimization, and scale down is discussed.

Some experiments and considerations on the behavior of a new magnetic frequency tripler with bridge-connected reactor circuit

Abstract: Some magnetic frequency triplers using the saturation characteristics of an iron core have been reported. In this paper a new frequency tripler which is based on the bridge-connected reactor circuit is proposed. The features of this tripler are that an applied source is single phase and ferro-resonance circuits are formed in both the output and input side. Consequently, the circuit becomes very simple, the power factor is greatly improved and the triple frequency output voltage holds constant. This paper presents some experiments and considerations on a new tripler. Moreover, various circuits which have equivalent operating characteristics are proposed.

Moving magnet meter having a closed magnetic circuit rotor

Abstract: There is disclosed a moving magnet meter of inexpensive construction which has the greater sensitivity, linearity and immunity from extraneous fields of moving coil meters. The rotor consists of a closed magnetic circuit through which a permanent magnet flux flows. The flux intersects the turns of a stationary coil through which the current to be measured flows, part of the closed magnetic circuit rotating within the coil. The strength and area of the permanent magnet flux which intersects the coil is substantially constant throughout an operating angle for the rotor of at least 90°. The return torque for the rotor is derived from a stationary permanent magnet which interacts with the rotor flux and provides a return torque which varies linearly with the rotor angle.

A method for inductive measurement of magnetic flux density with high geometrical resolution

Abstract: A method is described to measure magnetic flux density in small regions, for example the stray flux density on the surface of a ferromagnetic sample. A long rectangular loop of conducting material vibrates in the magnetic field, producing a voltage at its terminals which is proportional to the flux density at the 'bow' of the loop. The results of checking measurements for the calibration factors are compared with the calculated values and are found to be in good agreement. Examples are given for the application of the instrument.

Magnetic suspension system for railway vehicle with lifting force control

Abstract: A tracked vehicle system comprises a track having a downwardly facing surface of magnetic material, and a vehicle movable along the track, the vehicle comprising a magnetic suspension system including a permanent magnet, the suspension system being arranged to be magnetically attracted upwardly towards the surface of the track by the flux of the magnet whereby the weight of the vehicle is at least partially balanced by the magnetic force between the magnet and the track, and a magnetic circuit for controlling the magnetic flux, without permanently reducing the magnetic strength of the magnet, whereby to control the lifting force.

Dynamo electric machine permanent magnet flux test apparatus which simulates actual flux conditions of the motor

Abstract: To test the flux of circular segmental permanent magnets for assembly in permanent magnet dynamo electric machines, typically electric motors, a gauge is made of soft iron having an inner segmentally circular soft iron core, on it a layer of non-magnetic material to simulate the air gap of the motor, space for the permanent magnet to be inserted, and a return soft iron yoke in magnetic circuit with the core. A measuring coil which is chorded is located on the gauge to sense the magnetic flux, and so placed on the core that it conforms, at least approximately, to the pitch angle of the armature winding of the dynamo electric machine with which the magnet is to be used. To simulate cross fields, a demagnetization widing can be placed in the space adjacent the layer of nonmagnetic material adjacent the ends of the space for the permanent magnets to be tested, or the core can be cut with grooves similar to the coil slots of the armature, with current being passed therethrough in a direction to simulate the armature cross field. The test apparatus can be combined with a magnetizing yoke carrying magnetization coils to magnetize the segments, test them, and then demagnetize the segments, and reversely magnetize them for test of uniformity. Magnetic sensors can be placed on the core to sense the localized flux distribution of the magnetized magnet elements.

Magnetic field probe which measures switching current of magnetic element at moment the element switches as measure of external field

Abstract: A probe for sensing the strength of the magnetic field that surrounds a current-carrying conductor has a square-loop magnetic material wrapped about a conductor which is placed in the magnetic field to be sensed. An alternating signal is applied to the conductor, of sufficient intensity to cause successive reversals of the polarity of the magnetic material. A sense winding around the magnetic material issues a switch signal every time the magnetic material reverses polarity. The switch signal is used to sample the alternating drive signal current in order to store the amplitude of the drive signal at the instant at which the magnetic material reverses polarity. The sampled signal amplitude is averaged over a period of time, and the resultant amplitude is a linear function of the strength of the magnetic field. A second conductor, magnetic material and sense winding are arranged in a position remote from the magnetic field in order to sense the effect of the Earth's magnetic field. The averaged output signal resulting from the measurement of the Earth's magnetic field is then subtracted from the averaged output signal derived from the measurement of the magnetic field that surrounds the current-carrying conductor. The difference signal is displayed as an indication of the current-produced magnetic intensity or the magnitude of the electric current which produces it.

Induction heating core structure and method of heating

Abstract: An induction heating coil and core structure which provides two distinct magnetic circuits, with the materials to be heated also forming a part of the circuits so that juxtaposed workpieces can be joined together with a layer of heat activatable adhesive by a unitary core structure. A pair of nested U-shaped cores have a differing number of exciter coil turns with at least one common turn wrapped about each of the members to produce a greater amount of flux density in one core than the other to effect a different heat rate between the workpieces which complete each magnetic circuit.

Direct-current motor-generator

Abstract: A direct-current motor-generator comprises at least one stationary magnetic circuit including a permanent magnet and forming an air gap of substantially cylindrical shape, and a generally cup shaped rotor bearing a motor winding and a generator winding. The arrangement of the at least one magnetic circuit and the windings is such that the magnetic flux passing through the one of the said windings is separated in space from the flux passing through the other of the said windings.

Marine auto pilot

Abstract: A marine auto pilot employing a compass with a Hall-effect sensing element in conjunction with a magnetic circuit designed to provide a high intensity magnetic field; electrical circuitry designed to produce high servo-loop gain at frequencies lower than the normal sea wave frequencies, and lower gain at the normal sea wave frequencies; a D.C. Linear Motor drive system in conjunction with a rudder position feedback signal; and a linear ball-screw and nut gearing system for converting the high-speed output of the direct current drive motor to a low-speed high-torque drive at the rudder, having the nut and ball-screw connected through rolling contact balls.

Hover vehicle dynamic uncoupling control - with magnetic flux or temporary change introduced as additional quantitive dimension

Abstract: The control system is for the dynamic uncoupling, from its rails, of a rail-bound vehicle guided at an interval relative to the rails with magnets, the interval being regulated by magnetic circuits in accordance with a prescribed ideal value, with a signal embodying an imaginary beam interval for comparison with the actual value. An additional dimension is provided by the introduction into the guiding beam configuration of the magnetic flux or its temporary alteration. The signals embodying the temporary changes in the magnetic flux may be extractable on auxiliary coils allotted to the magnets. This is effective under rough operating conditions, and applicable both to vehicle-mounted and track-fixed magnets.

Inductor with plurality of magnet pieces in air gap

Abstract: There is provided a gap in a magnetic circuit of an iron core inductor, and a plurality of small size permanent magnet pieces are placed in the aforesaid gap, with the magnetizing directions thereof being provided in side-by-side relation. If the magnetizing direction of the permanent magnet pieces is opposed to that of a D.C. magnetic field which is produced in a magnetic circuit, yet in case D.C. and A.C. overlapping currents flow through the inductor, then the D.C. magnetic field produced in the magnetic circuit will be off-set thereby, providing a high inductance value, while eddy currents produced within the permanent magnet pieces due to the A.C. magnetic field will be reduced to a considerable amount, because the permanent magnet pieces are small in size, thus minimizing the heat to be produced in the permanent magnet pieces.

Variable reluctance A.C. electrical generator and method of making same

Abstract: A variable reluctance electrical generator is disclosed having a unique structure which, for any given design parameters, tends to maximize air gap areas and thus minimize mmf drops thereacross. The mean magnetic flux paths all generally include a constant reluctance parasitic air gap and a variable reluctance active air gap. The portion of the magnetic circuit defining the active air gap is adapted to magnetically saturate before the portion of the magnetic circuit defining the parasitic air gap areas thus eliminating the parasitic air gap as a design limitation. In the exemplary embodiment the parasitic air gap is located radially outwardly of the active air gap areas such that the parasitic gap reluctance is much less than the minimum active gap reluctance. The design of the alternator is also such as to simplify its assembly during fabrication and to thereafter permit ready disassembly of its major components from one another for repair or other purposes.

Contactless distance measuring device - between hovering vehicle and fixed armature rail uses magnet on vehicle energised with AC

Abstract: The core of the electromagnet on the vehicle consists of several magnetic circuits so shaped and arranged, that the effect of distance change in at least one dimension is not equivalent in individual circuits; at least one of the circuits is closed through the core itself, and the others through the rail; magnetic flux is measured in at least one of the magnetic circuits. The electromagnet core (39) has two excitation windings (35, 36) carrying current half-waves of opposite polarities with such winding sense, that the armature (rail)(11) carries a pulsating constant field, while an alternating flux is generated in the core central limb (44); the alternating flux is measured.

Magnetic transducer with single turn winding structure

Abstract: The transducer device for reading or writing information on a magnetic support comprises an insulating plate on one surface of which is deposited in thin layer form a magnetic circuit having an air gap and a conducting metal forming a turn. The turn is short circuited and the transducer device comprises a discrete magnetic circuit whereon is wound a winding and the turn is a primary or secondary winding of the circuit. It can be used as a reading or writing head for a magnetic disc.

Magnetic deflector for a magnetic ink jet printer

Abstract: A magnetic deflector for a magnetic ink jet printer has compensating pole pieces which alter the gradient field produced by deflection pole pieces so as to counterbalance centering forces acting on magnetic ink drops moving through the magnetic field in off center locations. The compensating pole pieces are preferably passive and extend from the zero potential region of the magnetic circuit of the deflection pole pieces.

Calculation and measurement of magnetic fields in turbogenerator end-regions

Abstract: Comparisons have been made between measurements and calculations of magnetic-flux in turbogenerator end-regions. The results of measurements on two 500 MW generators are presented. Two methods of calculation are reviewed. A method is given for relating the results derived from measurements and calculations to the load conditions. It is concluded that the use of a nonmagnetic rotor end-bell on these large generators willreduce eddy-current heat of the core-end.

Electromagnetic driving device

Abstract: PURPOSE:Electromagnetic driving device, little flux leakage, employing magnetic circuit with large air gap flux density

New improvements in the computation of the polyphase induction-motor magnetic circuit

Abstract: The present paper introduces a method of determining the airgap-flux-density waveshape in a polyphase induction motor operating under saturation conditions. It proposes to characterise the magnetic-circuit saturation by means of two independent factors, considering both the tooth and core saturation - and it produces new computative curves required to determine the magnetising current. The paper also proposes a new method of determining the field distribution in magnetic cores, considering the variable permeability, as well as curves for the computation of the core m.m.f. Comparison with other computative curves cited in the literature, as well as experimental results, has shown good correlation.

Electric acutating device

Abstract: An electric actuating device for producing limited angular displacements comprising an ironless cylindrical coil mounted for rotation in an air gap of a magnetic circuit, the magnetic circuit being formed by a permanent magnet placed inside the coil and an outer part of magnetically permeable material surrounding the coil. The coil is connected through spiral springs to a source of electric control pulses. The spiral springs provide a return force for bringing the coil back to a rest position in the absence of a control pulse. Means are provided for limiting the angle of rotation of the coil.

Magnetic circuit studies for an axial-gap reluctance motor

Abstract: The analysis of the magnetic circuit of an axial air-gap, battery-excited reluctance motor is presented. Permeance coefficients from which machine inductance can be calculated are derived. Inductance values calculated from these permeance coefficients are compared with values determined by magnetic analogs and by studies of air gap magnetic potential distribution using relaxation techniques and the Finite Element technique.

Magnetic detector for object with reciprocal rotating action - uses magnetic flux to affect inductance in AC circuit (BR140976)

Abstract: A position sensor for a part submitted to reciprocal action due to rotation uses magnetic circuits to eliminate need for direct contact This over comes difficulties of discontinuities obtained when potentiometer detectors are employed A permanent magnet (6) is fixed to an operating handle (7) through an arm (8) connected to a shaft (9) The magnet and shaft have the same axis of rotation (10) perpendicular to the plane of a magnetic frame comprising two magnetic plates (1, 2) attached (3, 4) to a magnetic circuit (5) A winding on this circuit is connected to an alternating current supply (13) and transformer winding (15) Variations of magnetic flux strength due to position of the permanent magnet affect inductance of the magnetic circuit winding (12) to affect rectified (19) current in a resistor (18) at the transformer output

Thermomagnetic characteristics of cores composed of temperature-sensitive magnetic materials

Abstract: Analytical and experimental results of thermomagnetic characteristics of cores composed of temperature-sensitive magnetic materials, such as flux density, coercive force and permeability, are discussed in this paper. The hysteresis loops of the composed cores were analyzed according to a graphical method based on a simple assumption. The theoretical values and experimental ones show a good agreement. A useful magnetic characteristic, which would not be achieved by any of the components alone, was obtained.

Effect of Radius of Yoke Curvature on Leakage Flux outside the Yoke in Permanent Magnet Assemblies

Abstract: The amount of the leakage flux outside the yoke was measured for five kinds of barrel type magnet assemblies with various curvature radii at yoke corners in order to find a suitable yoke shape which provides a stable magnetic field between pole pieces. The path length of the leakage flux which was expressed as the product of the magnetic circuit length of yoke and the ratio of the magnetic fields in and outside the yoke, was exponentially increased with increasing curvature radius of an intermediate plane of the yoke. The leakage flux was calculated for various shapes of the yoke using the experimental results.

Track pulse generator for length speed and acceleration - has resistance capacity generator coupled to pulse unit wheel and source

Abstract: The track pulse generator is for a path length, speed, or acceleration indicator and particularly for railway vehicles. The oscillator has its part coupled to the wheel of the vehicle formed as a resistance - capacity generator. The part coupled to the vehicle wheel (1) varies the value of the capacity of the frequency determining condenser (C1) between predetermined limits. The frequency determining resistances may be magnetic field dependent semi-conductor resistances (R1, R2). The coupling part with the vehicle wheel (1) may be a magnetic circuit (3, 4, 5, 6) of which the flux through the part (1) is variable within predetermined limits.

Saturable magnetic device for regulating commutating or converting an electric current from AC to DC or vice versa

Abstract: An electric current regulation, commutation and conversion device, which is particularly adapted for current regulation and commutation in rotating direct current electrical machines and for converting alternating current into direct current or vice versa. At least one conductor is disposed in at least one slot in a ferromagnetic lamination pack, the shape of the conductor cross-section and its arrangement in the slot being such as to intensify the additional resistance caused by the dispersion flow due to the current running therethrough. The magnetic circuit constituted by the lamination pack and linked to the current in the conductor is such as to minimize the inductance of the conductor, and the walls of the conductor containing slot are of such a form and arrangement as to be able to be saturated by an external magnetic control field superimposed on the magnetic field due to the current in the conductor.