Showing papers on "Magnetic core published in 1980"

Sink-float separators using permanent magnets and water based magnetic fluid

Abstract: The development of sink-float separators for materials of different densities, which utilize the levitation force of magnetic fluid, have been recently reported. The system usually consists of an electromagnet, separation cell, equipment for recovery of magnetic fluid smeared on the separated products, and controlling system. This paper describes and discusses the construction of sink-float separators using permanent magnets and provides test results for artificial mixtures of nonferrous metals. Ferrite magnet and rare-earth cobalt magnet were used as magnetic field generators in two separators. One for separating aluminum from other nonmagnetic metals, and the other to separate copper, zinc and lead from each other. A series of tests were performed on samples of 6 to 30 mm size, and it was found that the separators operated as expected. The separation of finer metals, however, proved difficult due to the attractive force which acts between nonmagnetic bodies immersed in magnetic fluid in a magnetic field. The chemical process to recover the magnetic fluid from smeared separation products is also proposed.

Self-sustaining solenoid

Abstract: A self-sustaining solenoid which is adapted so that when applying an operating current to a coil, a moving iron core disposed in the coil is attracted into contact with a fixed receiver. A magnetic yoke is provided to extend between the fixed receiver and the end portion of the moving iron core projecting out of the coil, and a permanent magnet is disposed on the magnetic yoke at least at one end in the direction of movement of the moving iron core. When the moving iron core is held in contact with the fixed receiver, magnetic fluxes emanating from the permanent magnet mostly pass through the moving iron core, the fixed receiver and the magnetic yoke, and even if the operating current is cut off, the moving iron core is retained in contact with the fixed receiver. A magnetic gap is provided through which the magnetic fluxes of the permanent magnet mostly pass when the moving iron core is out of contact with the fixed receiver, and magnetic flux resulting from the application of the operating current pass through the magnetic gap.

High current high frequency current transformer

Abstract: In an induction heating apparatus, direct sensing of the high frequency high power current flowing in the tank circuit to load the induction coils, is obtained with a coil current measuring transformer comprising one of the power current busses leading to the induction coil and a secondary winding of many ampere-turns wound around said one bus. The bus is given a half-loop shape to accommodate the secondary winding. The secondary winding is made of a magnetic core wound with many turns of Litz wire. Cooling tubes are cemented outside the wound secondary with conductive cement to form a heat sink with a circulation of cooling medium through the tube. The cement is divided in two parts separated by gaps to prevent circulation of induced currents. A cooling tube is installed between the core and wound wire to provide an internal heat sink.

Permanent magnet motor armature

Abstract: An armature for electric motors having a magnetic core of stacked laminations mounted on a shaft with a plurality of electrically conductive rotor bars disposed in the magnetic core, and also having a number of arch shaped permanent magnets disposed in the core that are circularly spaced from one another and arranged concentrically with the shaft. Each permanent magnet has a pole of one magnetic polarity on its radially outer face and a pole of opposite polarity on its radially inner face, and is surrounded by magnetic core material at its circumferential ends and radially inner side to form flux return paths, whereby there are two magnetic armature poles for each permanent magnet.

Magnetic head and its manufacture

Abstract: PURPOSE: To obtain a narrow-track, low-noise magnetic head which has high mass-productivity and superior recording and reproducing characteristics by forming a magnetic core of a metallic magnetic body with high saturated magnetic flux density and combining it with a nonmagnetic protection material having high wear resistance. CONSTITUTION: A groove 42 for coil winding is formed in a surface 41 as the gap abutting surface of a block 40 made of nonmagnetic ferrite. Then, plural couples of adjacent grooves 43 and 43' are provided in parallel except at a nearly-V-shaped projection part at right angles to the coil winding groove 42. Then, the metallic magnetic body film 44 is deposited by sputtering over the entire surface of the projection part including the groove parts. Nonmagnetic material 45 is provided onto the obtained metallic magnetic body film 44 to fill at least the remaining groove parts. The unnecessary nonmagnetic material and metallic magnetic body film of the obtained block are removed to expose an operating gap formation surface made of the metallic body film with necessary track width (t). Nonmagnetic materials such as SiO 2 and glass are sputtered over gap formation surfaces of an obtained couple of core blocks 47 and 48 to necessary thickness to form gap formation films, and the couple of core blocks are butted against each other so that projection parts of metallic body films of the core blocks have prescribed track width and heated under pressure at the fusion temperature of the filling glass 45 to obtain a joined block 49. COPYRIGHT: (C)1984,JPO&Japio

DC Ground fault detector wherein fault is sensed by noting imbalance of magnetic flux in a magnetic core

Abstract: A dc ground fault detector in which ground fault is sensed by noting an imbalance of magnetic flux due to a pair of windings on a toroidal core.

Anomalous eddy current loss in amorphous magnetic thin sheets and its improvement

Abstract: Soft magnetic properties of amorphous metals are interesting for application in transformers and other devices. So far, annealing in a field applied parallel to the amorphous ribbon axis was necessary to obtain the desirable magnetic properties. However, the amorphous cores made by this annealing method exhibit large eddy current losses. In order to reduce such large anomalous losses, we have improved the field annealing method, by applying the field oblique to the ribbon axis. In Fe-rich amorphous alloys, the core losses have been reduced by about 30-40 % by this method. Relation between the core losses and the magnetic domain structure has been investigated by comparing with the theory of Pry and Bean.

Reducing magnetic hysteresis losses in cores of thin tapes of soft magnetic amorphous metal alloys

Abstract: A technique for processing thin tapes of soft magnetic amorphous metal alloys to reduce their magnetic hysteresis losses. The technique involves preliminarily forming such a tape into a core, heating the core, and then controllably cooling the core, the heating and cooling being conducted in an oxidizing atmosphere. Maintaining the core during processing in a suitable longitudinal or transverse (relative to the tape) magnetic field can also produce improved properties. Certain tape cores so processed have particular magnetic hysteresis loss characteristics never heretofore known.

Method and means for controlling the flux density in the core of an inductor

Abstract: In a method for the enhancement of the A.C. performance of an inductor such as a transformer or choke, the tendency of the core of the inductor to become saturated by flux arising from low frequency A.C. or D.C. currents flowing in the inductor winding is reduced by detecting the magnitude of such currents and applying to a control winding wound on the core of the inductor a compensating current in order to generate a magnetic flux in the core of the inductor which opposes the component of flux tending to cause saturation. An inductor to which the method may be applied may accordingly comprise a main winding, a magnetic core, a control winding, means for sensing the presence in said main winding of a current having a frequency below a predetermined limit, and means for applying to said control winding a control circuit tending to balance the flux generated by the sensed current.

Loss Calculation in Laminated Steel Utilizing Antisotropic Magnetic Permeability

Abstract: The prediction of fields and stray loss levels in laminated magnetic steel parts poses a difficult problem for the field analyst. A method is proposed by which the effect of the laminations on the flux paths is simulated by a solid block with anisotropic magnetic permeability. This method is validated by a comparison of calculated flux patterns for the two cases and is applied to the prediction of stray loss in the laminated clamping rings of a power transformer by a high-order, anisotropic, finite element field computation. An example is cited to show that the reaction field due to the eddy currents in the laminated ring need not be calculated.

Manufacture of dust magnetic core and dust magnetic core coil

Abstract: PURPOSE:To reduce manufacturing cost, by a method wherein, after a mold or a container furnished with required winding is filled with slice-shaped magnetic powder or while being filled therewith, the winding is turned on a DC interminttently and further an insultaing resin is injected to impregnate and solidify said magnetic powder for molding. CONSTITUTION:For instance, the outer periphery of a bottomed cylindrical mold 1 consisting of paramagnetic material is furnished with windings 2 of the required number of turns, said winding 2 is connected with a DC power source 4, and the inside of the mold 1 is filled with slice-shaped magnetic powder 5 to highten filling density by turning the switch 3 on-off several times. Subsequently the fluid insulating resin 6 is injected to impregnate the magnetic powder 5 to be heated and solidified so that the magnetic dust 5 is solidified in the state of being oriented and treated. Thereafter the rod-shaped powder magnetic core 7 can be obtained by taking out from the mold 1. Thereby the automation of each process is simplified thus to reduce manufacturing cost.

Electrodeless lamp operating circuit and method

Abstract: An operating circuit and method for efficiently operating and starting an electrodeless lamp having a magnetic core operated at radio frequencies. The circuit generates a current which flows through the winding of an electric field inducing means in the lamp in a reverse-bias direction, with respect to a drive current, to operate the core of the inducing means in all quadrants of the B-H curve, with the time average of all current through the lamp winding equaling approximately zero in order to avoid or minimize heat energy losses and sharp current peaks caused by saturation. This also allows use of lower current-capacity less-expensive components. The circuit repetitively applies constant-current DC drive pulses to the lamp winding for a small percentage of an interval during which energy is stored, which is used to generate the reverse-bias current. Additionally, energy of flyback associated with turning-off of current in the lamp-winding-and-core is maximally limited to the winding itself for facilitating faster starts.

Rotary electric machine

Abstract: PURPOSE:To improve the efficiency of a rotary electric machine by employing a directional silicon steel plate having high magnetic flux density and low iron core loss as iron core material and laminating so that the directivity of the steel plate, namely, the rolling direction is uniformly dispersed as the entire iron core. CONSTITUTION:A number sheets of pressed iron cores 1 are laminated in a manner aligning marks 2 are displaced at every several sheets. When the cores are thus laminated and fixed, their directivity becomes uniform as the entire core. This iron core material exhibits high magnetic flux density and low iron core loss of directional silicon steel plate as compared with the amorphous silicon steel plate to thus improve the using efficiency of a motor.

Current- and voltage-measurement transducer

Abstract: A transducer for measuring a current, includes a magnetic core which has a gap substantially impeding passage of any magnetic flux, a coil arranged to pass a premagnetizing current for producing a first magnetic field, a loop for carrying the current to be measured, so as to produce a second magnetic field, and a magnetic field comparision device exposed to the magnetic fields. The magnetic field comparison device includes a magnetic film bridging the flux gap. The film is alternately controllable in respective opposite directions of saturation substantially by the first magnetic field, and evaluates the measuring current in dependence of the magnetic fields. The magnetic core, the coil, the loop, and the magnetic film are substantially disposed concentrically.

Variable inductance transducers

Abstract: A linear variable inductance transducer of the kind in which a spring-loaded plunger containing a magnetic core is axially movable in a stationary housing containing a coil assembly has the external surface of the plunger made of ceramic material, guided linearly solely by sliding in a ceramic bearing sleeve in the housing. The bearing sleeve may itself be flanged to form a bobbin for the coil assembly.

Amorphous cobalt alloy with very low magnetostriction and high permeability

Abstract: PURPOSE: To obtain an amorphous Co alloy with low magnetostriction and high permeability by adding Zr and one or more among Cr, Mo and W to Co in a specified atomic ratio, and subjecting to specified heat treatment. CONSTITUTION: This amorphous alloy consists or 7W15 atomic% Zr, 4W16 atomic% one or more among Cr, Mo and W and the balance practically Co. It is obtd. as follows: for example, a molten alloy having such a specified composition is rapidly cooled and solidified as an alloy thin strip by continuous spouting onto the outside of a disc rotating at a high speed. This alloy is annealed at a temp. below the crystallization temp. in a magnetic field under stress. This alloy has high wear resistance as well as superior soft magnetic characteristics such as small coercive force and high permeability. When it is formed into a thin strip, cutting, punching and other working are easily carried out, and it is suitably used as a magnetic core material for a magnetic head, a high frequency transformer, etc. COPYRIGHT: (C)1981,JPO&Japio

Low ripple D.C. power supply

Abstract: A high voltage power supply used to transfer three-phase a.c. energy to d.c. at full rated power over a large range of output voltages. The electric and magnetic circuits are arranged according to the core type of construction wherein three legs of the iron core extend axially and have the primary coil wound along their full length. The core legs are joined for magnetic circuit continuity at the extremities. A plurality of high voltage decks each having three secondary winding modules mounted and interconnected are stacked axially over the axially extending iron core pieces. The secondary coils on each high voltage deck are interconnected in several three-phase connections, to produce a phase shift in the ripple of the d.c. output voltage of the various decks. A high voltage bridge rectification circuit mounted on each deck produces full wave rectification of the ouptut. Each high voltage deck provides a contact which is engaged selectively by contacts mounted on an axially extending rotary switch whose angular position varies the interconnections of the high voltage decks to produce a range of output voltages at the full rated power of the transformer. A counterbalance circuit to reduce any residual voltage ripple component at multiples of the input frequency includes the application of an a.c. voltage of proper phase and amplitude supplied at the ground return lead of the series-parallel connected high voltage decks. The counterbalance voltage is applied by way of an additional secondary winding of a few turns coiled over the three legs of the transformer core, but is completely independent of the primary and secondary windings. The number of turns of the additional winding and the leg from which the voltage is taken are determined empirically.

Materials characterization for high temperature transformers

Abstract: Various transformer core materials have been characterized in order to evaluate their potentialities for fabrication of electronic transformers capable of operating at elevated temperatures. Temperature and annealing time dependence of pertinent magnetic parameters such as saturation flux density, B s , permeability, μ, and hysteresis loss, W h , are reported here. Based on these investigations transformers employing Deltamax and 2V Permendur core materials have been built and they perform well at high temperatures. The maximum operating temperature for 2V Permendur transformers is about 500°C whereas for Deltamax transformers it is about 360°C.

Drive circuit for field effect transistor

Abstract: PURPOSE:To break the high speed of an FET and to reduce the power consumption of a drive circuit by forming the third coil in a transformer, and abruptly discharging the charge of a gate capacity at the time of interrupting the FET. CONSTITUTION:A parallel circuit of the tertiary coil 33 of a transformer 3, a resistor 7 and a capacitor 8, and a switching element 6 are connected in series with a power source 1, the starting end of the coil 33 is connected to the collector of the element 6, and when the element 6 is conducted, a current which reversely excites a magnetic core is flowed. The element 3 is conducted simultaneously upon breaking of the switch element 2, a negative voltage is induced at the secondary coil 32, charge which is stored in the gate capacity of an FET 5 is abruptly discharged through the coil 33, and the FET5 is interrupted at a high speed. The resistor 4 can be sufficiently large or removed, the power consumption can be ingored, and power consumption of the resistor 7 may be sufficiently low, the power consumption of the drive circuit is reduced, the configuration is made simple and the operating characteristics can be preferably adapted for a practical use.

Oscillator/driver circuit for fluxgate magnetometer

Abstract: A low power expenditure oscillator/driver circuit including a transistor drive and control windings connected thereto and being operatively wound on a magnetic core suitable for use in a fluxgate magnetometer is disclosed. Its low power expenditure feature is provided, inter alia, by including an additional resistor in the base circuit of the transistor portion thereof so as to lengthen the base current pulses which permits their termination to be controlled by saturation of the magnetic core.

Solid state noncontacting keyboard employing a differential transformer element

Abstract: A solid state noncontacting mechanically actuated keyboard switch and interconnecting network for switch arrays. The switch provides a high degree of transformer balance and when implementing a N-Key rollover circuit employing the differential transformer type switch, diodes for isolation purposes are not required. The basic switch is a balanced or differential transformer element with a movable magnetic core (14), or shorted turn, actuator which is inserted through one-half of the transformer element, one primary-secondary pair (2, 6) causing the transformer to change from a balanced or "off" state to an unbalanced or "on" state. The single turn coils that make up the differential transformer element lie in a plane, and in one embodiment of this invention the primary coils (22) and their interconnecting network are printed on one side of a double printed circuit board (25), and the secondary coils (23) and their interconnecting network are printed in proper alignment on the opposite side. A hole is provided through the printed circuit board for each transformer element for insertion of a magnetic actuator (28). Included is a two dimensional X-Y switch matrix for facilitating electronic scanning of the keyboard for implementing encoding multikey rollover, etc. techniques.

Magnetic suspension vehicle support, drive and current transmission - has support magnetic core of several core sections with groove-free pole surfaces and linear generator core between two core sections

Abstract: The combined system of a magnetic suspension vehicle has a longitudinal stator (rail) along the travel path. The stator magnetic core has a great number of grooves arranged one behind the other in the travel direction. The grooves contain a three- phase a.c. coil. Along the vehicle is mounted a support magnetic core with a number of magnetic poles of alternating polarity, mounted one behind the other in the travel direction. Each pole has a d.c. coil, and the vehicle comprises a linear generator with a magnetisable core and a current pick-up coil. Between the support magnet and the generator cores on one side and the stator core in an air gap. The support magnetic core (32) consists of several partial cores (32A-C) with plain pole surfaces (31). Between two partial cores in travelling direction is fitted a linear generator core (45) with its associated current pick-up coil (41).

Method of making a magnetic head

Abstract: In a method of making a magnetic gap by depositing a glass layer on a surface of magnetic head core materials by cathodic sputtering of a glass target and cementing a pair of the resulting glass-coated magnetic head core materials, the improvements constituted by monitoring the thickness of the sputtered glass layer by an interference of a light beam guided onto a surface of the magnetic head core materials during the deposition and using a sputtering apparatus having a sample holder beside the target for securing the magnetic core materials and a mask plate for achieving uniform thickness of the sputtered glass layer. The method makes possible production of magnetic heads having excellent electromagnetic conversion characteristics with high accuracy.

Read/write and tunnel erase magnetic head assemblies

Abstract: A magnetic head assembly for reading and/or writing a track of magnetic information on a moving magnetic medium and for tunnel erasing adge portions of the track comprises a central data transfer magnetic core including a pair of core portions (20, 22) providing a data transfer gap (30) on an active face (26) of the head assembly with a read/write coil (32) on one of the core portions. An erase core includes a pair of erase core portions (36, 42).extending along and in contact with one of the write core portions, another pair of erase core portions (34, 40) respectively in alignment with the erase core portions (36, 42) and providing therewith erase gaps (38, 44) on the active face of the head assembly that extend transversely of the direction of movement of the magnetic medium on the active face and a bridging core portion (46) between the erase core portions (38, 44) on which an erase coil (48) is disposed. The two erase gaps are in series with each other in a magnetic circuit which shares a segment in common with the magnetic circuit of the data transfer gap at 22, but the two natural flux flows in the common segment are substantially mutually perpenducular.

Hybrid circuit with integral inductor - wound with turns partly on substrate and partly on flexible insulation ribbon

Abstract: A typical application for the proposed hybrid circuit with an inductor is in telephone exchange circuits. The magnetic core (MK) is mounted on a substrate (Su) upon which a part of the winding (F) is arranged as a printed circuit. The remainder of the winding, to complete the turns around the core, is carried on a flexible ribbon (T). On this conductors (A) are arranged, equally spaced in parallel lines, e.g. printed on. The ribbon is placed over the core (MK) so that the conductor ends (A) coincide with the corresp. ends on the substrate. At jointing surfaces (KF1, KF2) the two are then connected, typically by soldering. The precise definition and spacing of conductors gives freedom from short circuits. There is lower space requirement compared with wire winding. This allows the use of larger cross-section cores. The winding can be made of copper rather than gold. The substrate need not be ceramic, and could, if necessary be flexible.

Power supply device

Abstract: PURPOSE:To control the operating point of a core by a method wherein a magnetic core having a nonlinear region is provided with No.1 and No.2 coil and further No.3 coil which is arranged perpendicular to these coils, and when power is supplied to No.1 coil, and the output voltage of No.2 coil is supplied to No.3 coil. CONSTITUTION:A transformer 10 consists of a pair of magntic cores 11, 12 made of ferrite. These cores 11, 12 consist of a square plate-shaped core base 10E and magnetic legs 10A-10D, which extend from the four corners of the base at right angles to it and have the same cross section. Magnetic legs 10A-10D are placed opposite one another so that they come in contact with one another with their ends. As a whole, they from a cube or a rectangular parallepiped. Next, extending over to the respective magnetic legs, excitation coil N1 is wound on 10B and 10C, parametric oscillation coil N2 on 10A and 10D, and control coil NC on 10A and 10B. By this, the output voltage of coil N2 produced when power is supplied to coil N1 is applied to coil NC, and thereby the maximum magnetic flux density of transformer 10 is controlled and the output voltage is stabilized.

Wound iron core

Abstract: PURPOSE:To obtain a wound iron core having an excellent space factor as well as a small interlayer eddy-current loss by effecting insulation by placing an insulating layer every between a plurality of layers of amorphous magnetic thin ribbons having no surface insulating films. CONSTITUTION:One or a plurality of layers of amorphous magnetic thin ribbons 3 each coated with surface insulating films 4 of glass, phosphate or the like as insulating layers are placed every between a plurality of amorphous magnetic thin ribbons 2 having no surface insulating films so as to divide them into blocks electrically insulated from each other, to constitute a wound iron core 1. Thereby, the characteristics of the amorphous magnetic thin ribbon, a high magnetic permeability and a small loss, are made use of, and the interlayer eddy-current loss can be reduced without a bad influence on the space factor.

Three-dimensional computation of the field of magnetic recording heads

Abstract: A new numerical technique for computing the three-dimensional magnetic field of a recording head is presented: the "magnetic-field surface-integral equation method". It is based on a vector Green-type integral relation for the magnetic-field strength. The present implementation applies to a recording head configuration consisting of infinitely permeable magnetic materials, perfectly conducting electric shields and a coil, all of arbitrary size and shape. The method is applied to a cubical head with and without magnetic or electric side shields. It is concluded that near the head's sides the harmonic response shows higher long wavelength amplitude oscillations than near the center of the head. The presence of a magnetic side shield is found to decrease considerably the side field, whereas an electric shield, even when perfectly conducting, is much less effective.

Core for electromagnetic induction device

Abstract: A magnetic core for an electromagnetic induction device has a plurality of magnetic core elements (14). Each of the core elements is formed by winding a plurality of layers of uninsulated strip (18) of magnetically permeable material. The core elements are juxtaposed together to form a core stack, the height of which is large relative to the strip width of each element. The core elements are electrically isolated from each other by insulating material (22) interposed between the elements at the region of juxtaposition.