Showing papers on "Magnetic circuit published in 1982"

Magnetic switches and circuits

Abstract: : This report outlines the use of saturable inductors as switches in lumped-element, magnetic-pulse compression circuits The operation of the three basic types of magnetic pulse compression circuits is discussed and the characteristic use of each is defined In addition, the geometric constraints and magnetic pulse compression circuits used in short-pulse, low-inductance systems are considered The scaling of presaturation leakage currents, magnetic energy losses, and switching times with geometrical and material parameters are developed to aid in evaluating magnetic pulse compression systems in a particular application Finally, a scheme for increasing the coupling coefficient in saturable stripline transformers is proposed to enable their use in the short-pulse, high-voltage regime

Low voltage circuit breaker

Abstract: A low voltage circuit breaker with a current sensing unit having a magnetic circuit with three branches, the secondary winding being mounted on the intermediate branch and the primary winding being formed by a conductor selectively passing through one or two of the openings provided between the secondary winding and the outer branches The circuit breaker comprises an instantaneous electromagnetic trip mechanism and a static long time and short time delay trip unit, the latter unit being governed by a signal attenuated by a rating selection device

High-gradient magnetic separator

Abstract: A high-gradient magnetic separator is provided for filtrating weakly magnetic particles from a fluid in which they are suspended. The fluid is caused to flow through a separation chamber arranged in a gap in a magnetic circuit which comprises a pair of separate permanent magnetic devices connected by means of yoke members of a magnetic soft material. Permanent magnet devices generate a strong magnetic field in the gap with very small magnetic losses. Each permanent magnetic device comprises a permanent magnetic member with a substantially linear demagnetization curve. A matrix of magnetic soft material is disposed in the gap between pole surfaces of the permanent magnetic devices to create high local magnetic gradients. To facilitate cleaning of the matrix filter material, the separation chamber is formed as a displaceable box-shaped cannister. A series arrangement of two such canisters with an intermediate dummy load creates a favorable duty cycle, with one cannister operating in filtration mode and the other displaced outside the gap for cleaning the matrix material. Substantially zero magnetic losses occur with each permanent magnetic device of a pole shoe member being formed of a magnetic soft material, one side forming a pole surface engaging the gap, all other sides being in contact with permanent magnetic members to provide a leakage-free enclosure.

Magnetic head incorporating an amorphous magnetic metallic film having a thickness equal to a track width

Abstract: A magnetic head includes at least a core for constituting a magnetic circuit and a magnetic gap formed in the core. The core comprises an amorphous magnetic metallic film formed on a non-magnetic high-resistance substrate so that one of the end faces of the non-magnetic high-resistance substrate and the amorphous magnetic metallic film may be brought into contact with a magnetic recording medium.

Non-destructive detection of the surface properties of ferromagnetic materials

Abstract: A method of and apparatus for non-destructive investigation of the surface properties of a body of ferromagnetic material such as a pipeline in which a non-saturating source of magnetic flux is placed adjacent to said surface to create a magnetic circuit having a substantial proportion in non-ferromagnetic material and a sensor is used to measure the magnetic flux in said circuit, an indication of the surface properties of the body being derived from a plurality of such measurements.

Three-dimensional analysis of magnetodynamic fields in electromagnetic devices taken into account the dynamic hysteresis loops

Abstract: A new magnetic field equation exhibiting dynamic hysteresis loops is proposed. Based on this magnetic field equation, a system of two-dimensional magnetic circuit equations taken into account the dynamic hysteresis loops is derived by the method of magnetic circuits. By means of magnetic power invariant transformation, a system of two-dimensional magnetic circuit equations is transformed into a system of three-dimensional magnetic circuit equations. This system of three-dimensional magnetic circuit equations is discretized in time by a finite difference method. A system of three-dimensional magnetic circuit equations discretized in time is solved by a simple iteration method, using a relaxation parameter. As an example, a system of three-dimensional magnetic circuit equations of a simple saturable reactor is derived. Also, the numerical solutions of dynamic hysteresis loops in a saturable reactor are presented together with those of experimental results.

Non-linear alternating current transducer

Abstract: The non-linear alternating current transducer includes a current transformer core (14, 50 or 80) comprising a yoke (14, 50 or 80) for receiving a line conductor (20 or 110) and a secondary winding (22 or 86). The yoke (14, 50 or 80) has an air gap (19, 56 or 101-105) configured to provide a non-linear magnetic circuit response for changes in current through the line conductor (20 or 110). The non-linear magnetic circuit response provides a logarithmic voltage output across the secondary winding (22 or 86). The current transformer (12) is used in a control circuit (10) for sensing, monitoring and interrupting current in the line conductor (20 or 110) such that a trip coil is energized to open the circuit whenever current is sensed above a predetermined current. Also, the logarithmic response provides for high gain at low currents and low gain at high currents to that a very uniform percentage-of-reading accuracy is obtained with a meter operating off of the secondary winding.

Detecting element of magnetic field for extremely low temperature

Abstract: PURPOSE:To make possible a highly accurate and highly reliable measurement of an extrememly low temperature magnetic field, by utilizing magnetic flux current resistance phenomena of an amorphous super conductive alloy. CONSTITUTION:The variation of electric resistance value at the time of applying 0.06-110A/cm electric current value and 0-70KOe magnetic field at 4.26 deg.K by using a sample of an amorphous super conductive alloy consisting of Mo77.5Si10 B12.5 which is manufactured by a liquid quenching method, is shown by the figure. A super conductive transition temperature of the alloy is 7.66 deg.K by a result of measurement and the electric resistance is changed suddenly at about 50KOe in the case where an electric current density JT is small (7, 8 in the figure) shown as the figure and the variation of its electric resistance for the magnetic field is increased nearly linear at about (2, 3 in the figure) in opposition to the fact that the electric resistance is zero under the super conductive condition below the 50KOe and then, a magnetic flux current resistance is generated. Accordingly, the intensity of the magnetic field is measured by measuring the value of the electric resistance of the amorphous super conductive alloy.

Method and apparatus for measuring gaseous oxygen

Abstract: An oxygen detection system including two equal and symmetrically constructed major DC magnetic circuits each having an air gap which is alternatively filled with a sample and a reference gas. A magnetic bridge arm connects the major magnetic circuits in series opposition to derive a null response when the flux carried in the magnetic circuits is equal and a component of varying flux when the sample and reference gases are interchanged to cause an unequal flux to be developed in the circuits caused by a change in the reluctance across the gaps. An encircling inductance coil senses the flux in the null bridge arm which is electronically sampled in sychronism with the sample and reference gas interchange to develop a difference signal directly derived and proportional to the difference in magnetic susceptibility of the sample and reference gases. An active magnetic shield cancels stray fields from affecting the sensor.

Flux-line instability in a pin-free superconducting cylinder with longitudinal current

Abstract: The flux-line lattice in a long cylindrical type-II superconductor carrying an electric current parallel to an applied axial magnetic field is always unstable if there is no volume pinning.

Electric apparatus and its magnetic core of (100)[011] silicon-iron sheet made by rapid quenching method

Abstract: High-silicon steel sheets or ribbons having the crystal texture described by (100)[011] are used for the fabrication of magnetic cores of electrical machinery in such a way that the easy axes of magnetization coincide with the directions of magnetic circuits or lines of magnetic flux. Magnetic cores of, for instance, electric motors or transformers can be remarkably improved in efficiency.

Vertical magnetization recording head

Abstract: PURPOSE:To enhance the writing/reading efficiency of a vertical magnetization recording head, by forming a closed magnetic circuit between a main magnetic pole and an auxiliary magnetic pole to eliminate a leakage of the magnetic flux to the outside CONSTITUTION:A main magnetic pole 13 is provided in the vertical direction to a vertical recording medium having the anisotropy in the vertical direction to the film surface, and a permalloy film 14 is mounted on the pole 13 to carry out a writing along with a magnetic line (a) provided around the film 14 An auxiliary magnetic pole 16 wound by a conductor having the line (a) around it is provided oppositely to the pole 13 and holding a vertical recording medium 12 between them Thus a vertical magnetization recording head is obtained The writing/reading is carried out only with the surface where the tip of the film 14 of the main magnetic pole touches the medium 12, and a closed magnetic circuit is formed by the line (a) provided around the poles 13 and 16 As a result, the leakage of magnetic flux is extremely reduced to the outside to enhance the writing/reading efficiency

Thermal compensators for magnetic circuits

Abstract: Thermal compensators comprising at least one metallic alloy in amorphous form which are especially useful in stabilizing magnetic devices under conditions of changing ambient operating temperature are provided.

Two dimensional actuator for moving optical medium of scanning device

Abstract: An optical scanning device for subjecting a light spot to a focussing operation and for causing the light spot to perform a tracking operation to reproduce information stored in a video or audio disc is disclosed in which a coil controlling a focussing optical system for forming the light spot and another coil causing the light spot to track the above-mentioned information are both placed in a magnetic gap included in a magnetic circuit formed by a permanent magnet and a magnetic member, and the magnetic circuit is arranged in a direction perpendicular to the direction of the tracking operation.

Disc drive electromagnetic actuator with enhanced flux density

Abstract: An electromagnetic actuator for a data disc drive having a carriage on which is mounted one or more read/write heads for cooperation with a data disc. The carriage is supported in the housing for movement on an axis that is oriented radially of the disc. The end of the carriage remote from the read/write head is of hollow rectangular cross-sectional shape; there is a voice coil mounted on the end of the carriage. A magnetic housing defines a cavity in alignment with the carriage and the coil so that the carriage and coil can move within the cavity. The housing is constructed of magnetic material, and in magnetic circuit with the housing is at least one permanent magnet. The permanent magnet has a surface that confronts the path along which the coil moves. Between the permanent magnet surface and the coil is a flux focussing pole piece of generally trapezoidal shape so that the flux density at the inner surface of the pole piece that confronts the path of coil movement is greater than the flux density at the inner surface of the permanent magnet. Consequently, for a given current flow within the coil, a great force is applied to the carriage so that faster radial movement of the carriage and the read/write head can be achieved.

Method and device for the induction heating of a ferromagnetic component having axial symmetry and irregular contour.

Abstract: The invention relates to a method and a device for the induction heating of a ferromagnetic component having axial symmetry and irregular contour, of the type comprising regularly alternating peaks and troughs, such as toothing. By making the toothed component 1 rotate in the continuous magnetic field generated by a laminated inductor magnetic circuit 4 provided with coils 8, 9 traversed by a direct current, alternating currents generated by the variation in the magnetic flux owing to that in the reluctance are induced in its periphery. Application to the induction heating of toothed crowns, pinions, rotors, with a view to heat treatment.

Application of the finite element method to the design of permanent magnets

Abstract: A new method of determining the lengths of magnets in a magnetic circuit by using the finite element method has been developed. This method has the advantage that the lengths of magnets which produce the prescribed flux distribution can be directly calculated. In this paper, the error of this method is discussed at first, and then an example of application determining the shape of a magnet is shown. This method is effective for the design of magnetic circuits consisting of several permanent magnets and the determination of the shapes of magnets.

Regulation and drive system for high rep-rate magnetic-pulse compressors

Abstract: The essentially unlimited rep-rate capability of non-linear magnetic systems has imposed strict requirements on the drive system which initiates the pulse compression. An order of magnitude increase in the rep-rates achieved by the Advanced Test Accelerator (ATA) gas blown system is not difficult to achieve in the magnetic compressor. The added requirement of having a high degree of regulation at the higher rep-rates places strict requirements on the triggerable switch for charging and de-Queing. A novel feedback technique which applies the proper bias to a magnetic core by comparing a reference voltage to the charging voltage eases considerably the regulation required to achieve low jitter in magnetic compression. The performance of the high rep-rate charging and regulation systems will be described in the following pages.

Self-regulating saturating core television receiver power supply

Abstract: A self-regulating, saturating core power supply for a television receiver includes a magnetizable core having first, second and third core sections. A primary winding is wound around the first core section and an output secondary winding is wound around the second core section. The third core section provides a magnetic circuit path for magnetic flux lines that link both windings. The primary winding is coupled to a source of alternating input voltage for developing an alternating polarity output voltage across the secondary winding. A resonating capacitor is coupled to the secondary winding for generating a current therein that aids in producing substantial magnetic saturation of the third core section twice during each cycle of the alternating polarity output voltage to thereby regulate the output voltage. The second core section remains substantially unsaturated during the entirety of each cycle. The regulated output voltage may be used to develop direct supply voltages for the television receiver such as the B+ scan supply voltage and the ultor high voltage.

Current sensing relay

Abstract: A current sensing relay assembly is disclosed wherein current sensing devices are integrated with relay outputs on a single printed circuit assembly. By integrating the output and sensor, all additional external equipment and wiring are eliminated. The current sensors achieve a maximum current to minimum current sensing ratio exceeding 100 by sensing current flow magnetically using Hall-effect devices and appropriate amplifier circuitry. Multiple channels of current sensing are achieved without requiring individual sensitivity adjustments by utilizing common threshold references for all channels. The electronic portion of the sensor achieves immunity from power line noise and a stable sensing threshold by a combination of circuit design and layout. In the illustrated embodiment, the magnetic portion of the sensor is contained entirely in a single module that incorporates the sensing coil, magnetic circuit, Hall-effect sensor, and magnetic shield.

Bipolar magnetic sensors

Abstract: Lateral bipolar magnetic sensors have been developed whose output signal is measured as a differential voltage between two collectors. Devices can be designed either to respond to magnetic fields applied perpendicular to the surface or to parallel fields. The experiments have resulted in an understanding of the basic operating principles and have led to the design of optimum magnetic sensors. Whereas previous investigations of dual-collector lateral bipolar transistor structures have attributed the unequal collector currents (resulting from the application of a magnetic field) to "carrier deflection" in the base, our experiments clearly demonstrate that it is due to nonuniform injection from the emitter. The applied magnetic field leads to a voltage variation along the emitter-base junction and this, in turn, results in nonuniform carrier injection into the base and subsequent unequal currents to the two collectors.

Magnetic bubble storage device

Abstract: PURPOSE:To arrange a magnetic bubble element in a magnetic circuit and a driving coil easily and with high accuracy, by fitting an inside winding frame for holding a substrate on which the magnetic bubble element has been mounted, into an outside winding frame, and also installing a yoke plate and a permanent magnet to the outside winding frame CONSTITUTION:A magnetic bubble element 11 is mounted on a printing substrate 12a, and a cover body 12b is provided thereon This substrate 12 is fitted into through-windows 13b, 13b' of an inside winding frame 13, and an inside coil 14 is wound so as to bridge side plate 13, 13c' This inside coil frame 13 is inserted and held in through-windows 16c, 16c' of an outside winding frame 16 from the direction indicated by an arrow A Side plates 16a, 16a' are bridged, and an outside coil 15 is wound so as to cross at right angles to the inside coil 14 Also, yoke plates 17a, 17b and permanent magnets 18a, 18b are provided on a flat part of flange bases 16b, 16b', and a magnetic shielding frame 19 is provided to its outside circumference In this way, the magnetic bubble element 11 can be arranged in a magnetic circuit and a driving coil easily and with high accuracy

Electric transformer with annular coil forms

Abstract: The transformer comprises a magnetic circuit (8) as well as, in the case of each phase, a high-voltage electric circuit (17) and a low-voltage electric circuit (18) both wound around at least one section of the magnetic circuit (8) The electric circuits (17, 18) are arranged in at least one electrically insulating annular coil form (11) which, under service conditions, is interposed between the electric circuits (17, 18) and the aforementioned section of the magnetic circuit (8) Utilization in particular for improving the occupation of electric windows by the magnetic circuit and of magnetic windows by the electric circuit

Formation of bipolar radial anisotropic magnet

Abstract: PURPOSE:To reduce a magnetic leakage and increase the number of the magnets obtainable without the interference from a forming magnetic field by a method wherein a magnetic circuit is formed with the press mold having an N pole and a S pole in the upper and lower portion thereof respectively and a mold portion for pressing the magnetic powder is formed in non-magnetic substance. CONSTITUTION:An N pole is generated by an annular coil 1 in dices 4, 5 and a S pole is generated by a coil 2 in dices 7, 8. The major of the magnetic force lines induced by the coil 1 is absorbed to the core 3, the minor of the magnetic force lines is transmitted through the dices 4, 5 to the dices 7, 8 and couples with the S pole generated by the coil 2. The S pole generated by the coil 1 and the N pole generated by the coil 2 are coupled with each other through the support of the machine to constitute a great electric circuit. The magnetic powder oriented along the radial direction is pressformed by the upper punches 10, 11 of the non-magnetic substance and the lower punches 12, 13 of the non- magnetic substance in the cavity. Thereafter, the magnetic pole of the coils 1, 2 is reversed and the demagnetization is established. As a result, the radial anisotropic magnet can be formed.

Transformer mfg. method for line scan circuit of TV receiver - has gap of magnetic core adjusted by use of predetermined amount of hardening glue and coil impedance measurement

Abstract: The process concerns the adjustment of the transformer ferrite magnetic circuit gap. The transformer comprises several coils wound on insulating tubes and a magnetic core traversing these coils. The magnetic core is formed by two opposite ferrite parts. Before being assembled, one of the two ferrite parts receives a predetermined amount of hardening glue on its gap face. After assembling of the two ferrite parts, the core gap is adjusted as follows: the inductance of one transformer coil is measured while one ferrite part is moved in relation to the other until the measured inductance is equal to a choosen value. The relative position of the two ferrite parts is then maintained until the glue has completely hardened.

Magnetic filtration apparatus

Abstract: An improved method of and apparatus for magnetically filtering a magnetically susceptible component in a fluid (F) with a matrix (5) of magnetizable material which, when magnetized, provides a multiplicity of regions of high magnetic field gradient. A sequence of time-spaced impulsive magnetic fluxes is produced in an electromagnetic coil (24) by periodically charging and discharging a capacitor (13) connected to the coil (24), said fluxes being concentrated across the magnetic matrix (5) to magnetically entrap the magnetically susceptible component in the regions of high field gradient therein. A static magnetic flux may also be provided in said matrix (5) by permanent magnet means (22,23) included in a magnetic circuit with said matrix (5).

Measuring of magnetic property of steel material

Abstract: PURPOSE:To achieve simultaneous measurement of magnetic characteristic value in a contactless manner and online by determining characteristic of variations in the penetration of magnetic flux with respect to changes in an exciting current of an electromagnet employing a magnetic detector provided on one side of a steel material to be measrued while the electromagnet on the other side thereof sandwitching it to measure a magnetic characteristic value of the steel material from the resultant characteristic curve. CONSTITUTION:Magnetic flux 5 generated from a magnetic core 2 comprising magnetic flux 51 passing through a steel material 1 and magnetic flux 52 penetrating through the back thereof. An apparatus 7 receives the current proportional output E1 of an exciting power source 4 and the output E2 of a magnetic detector 6 and computes the magnetic characteristic of the steel material 1 being measured from a characteristic curve representing a relationship of both the outputs. The characteristic curve between the exciting current proportional output E1 and the output E2 of the magnetic detector varies in the sequence 0' 2' 3' 4' 5' 2' as shown by the arrow, where the penetrating magnetic flux 52 decreases as the magnetic flux 51 passing through the steel material 1 being measured while it increases as the magnetic flux 51 decreases. Since the magnetic flux 51 in the steel material being measured is proportional to a magnetization factor thereof, the curve (E1-E2) is determined by the magnetization characteristic of the steel material to be measured, dimensional distances l1 and l2 thereof and the magnetization characteristic of a magnetic core 2.

Objective lens driver

Abstract: PURPOSE:To obtain a small-sized, lightweight and simplified structure and to improve efficiency by forming a magnetic gap between a fixed coil and a movable part which includes an annular magnet and an objective lens, and supporting the movable part by a coil spring. CONSTITUTION:For example, when a magnet 1 is magnetized to have an N pole at the upper part and an S pole at the lower part, a flow 1a of magnetic flux crosses a bobbin 6 and an electromagnetic coil 7 through the magnet 1 and a yoke 2, reaches a yoke 9, and then return to the S pole through an electromagnetic coil 8, the bobbin 6, and a yoke 3. When currents flow through the electromagnetic coils 7 and 8 wound in said magnetic circuit in such a way that the current flow in the opposite directions, those two coils generate equal forces in the axis direction 4a. Since the coils 7 and 8 are fixed, an objective lens 4 moves in the axial direction by reaction to perform stable driving by a coil spring 10, and the size and weight are reduced; and the efficiency is improved and the structure is simplified.

Magnetic circuit and print hammer

Abstract: A high-speed print hammer and magnetic actuator is provided which operates with a minimum of power dissipation, can achieve high speed, and has very little flux leakage beyond the mechanical structure. The magnetic actuator is made up of two pole pieces having a high magnetic permeability, with a permanent magnet therebetween. A print hammer, also having a portion constructed of a material with a high magnetic susceptiblity, is pulled away from its unsprung position by the permanent magnet and contacts the faces of the pole pieces, providing a very low reluctance magnetic path between them. The print hammer is released from this cocked position by a pulsed electromagnetic field applied in a direction opposite that of the permanent magnet, the pulse pattern corresponding to the desired impact pattern of the print hammer. Lower drive power to the electromagnet is achieved by providing an alternate magnetic path having a reluctance intermediate between that provided by the print hammer when it is in contact with the pole faces, and the reluctance between the pole faces (i.e., through the air) when the print hammer is not in contact with the pole faces.