Showing papers on "Electromagnetic coil published in 1972"

Force on a Rectangular Coil Moving above a Conducting Slab

Abstract: The force on a rectangular current‐carrying coil moving above and parallel to a conducting plate of arbitrary thickness is investigated. Expressions are developed for the lift and drag forces on the coil as a function of speed. Numerical calculations are made for a very thick plate and for plates with thickness of the order of the skin depth. Thick‐plate results are compared with experimental measurements of lift and drag on a superconducting coil suspended above a rotating aluminum wheel.

Electrical apparatus generating a low frequency, alternating magnetic field for promoting the growth of bone and other body tissues

Abstract: The growth or repair of fractured bones or the growth of other body tissues is promoted by means of a coil which is applied to produce a magnetic field at the site in which growth is to be encouraged. The coil is supplied with a low frequency alternating voltage below 50 Hz. A device is applied to the body or implanted in the body in order to concentrate the magnetic field produced by the coil.

Computation of type curves for electromagnetic depth sounding with a horizontal transmitting coil by means of a digital linear filter

Abstract: The computation method described in this paper is based on the existence of a linear relationship between the mutual coupling ratio and the kernel function in the integral expression for it. Accordingly, the mutual coupling ratio can be determined by first computing sample values of the kernel function and then subjecting these to a digital linear filter. In the present paper the appropriate sampling distance is determined and the values of the digital filter coefficients are computed, both for electromagnetic sounding with horizontal coils and for electromagnetic sounding with perpendicular coils.

Metal detector system having identical balanced field coil system on opposite sides of a detection zone

Abstract: A balanced field metal detector apparatus comprising a coil assembly including planar, generally rectangular loop configured multi-turn field and sensor coils disposed in partially overlapping minimum mutual inductive coupling relation and oriented so that the long dimension of the loops is skewed relative to the vertical in use of the apparatus. Employment of a pair of the detectors, one on each side of a pathway, with the respective coil assemblies skewed relative to the vertical oppositely to one another, enables detection of a metal object in the pathway by one or both of the detectors irrespective of the shape and orientation of the object, and by suitable processing of the sensor coil signals further enables determination of whether the object is located at the left, center or right side of the pathway.

Supercooled rotor coil type electric machine

Abstract: An electric rotary machine having an armature coil at ambient temperature disposed on the stator and a supercooled field coil disposed on the rotor and enclosed in a container which is integral with said rotor, a major part of the outer surface of said container being coated with a thermal insulation layer, the supercooling liquid being introduced into the container through a tube inserted into the rotor along the rotational axis of the rotor, and the evaporated gas of the supercooling medium being discharged through a labyrinthine path or a series of partitioned compartments provided at each axial end of the container to establishing a uniform temperature gradient along the shaft of the rotor between the inside of the supercooled rotor and the axial ends thereof which are at ambient temperature.

Insulated coil for arrangement in a slot in the stator or rotor of an electric machine

Abstract: A coil positioned in the slot of a stator or rotor in an electric machine is formed of a bundle of conductors arranged close together and insulated from each other and from the slot. The conductor insulation consists of a layer of polymer and a tape of corona resistant insulating material running longitudinally of the conductor is adhered to the polymer layer. The tape surrounds the parts of the conductor facing the main insulation which surrounds the bundle of conductors and furthermore overlies at least those parts of the sides of the conductors which face the adjacent conductors which parts are situated nearest the sides facing the main insulation.

Bistable electromagnetic actuator

Abstract: An actuator having an armature plate urged to a stable position by a spring and which may be held in another stable position by a permanent magnet. Application of an appropriate current pulse to a coil within the actuator reduces the flux flow through and the magnetic force on the armature sufficiently to release the armature to the former stable position under the influence of the spring. Two magnetic circuits, one of which includes a non-working air gap, are employed, the non-working air gap serving to maintain a flux path, of a predetermined maximum reluctance, for the permanent magnet when the armature plate is in the former stable position.

High-speed fuel injection system

Abstract: Construction of high speed injectors, a special type switch mechanism for synchronizing the operation of the injectors to the angular position of a motor shaft, a unijunction transistor time delay circuit whose base and emitter voltages are varied in response to variations in different parameters, rapid switching bistable control circuits, which control the injection period in one state, damping circuits for the injector, circuits for transferring the electromagnetic energy liberated by current interruption in one injector coil to the next injector coil to be activated, and circuits for regulating a motor driving a generator to correspond to the voltage, current or power output of the latter.

Electrical Current Effects on E. coil Growth Rates

Abstract: SummaryThe results show that alternating current had little or no effect upon the growth rate of microorganisms in the current and frequency ranges investigated. The general effect of direct curren...

Burglar alarm actuated by cut telephone wire

Abstract: A burglar alarm which is actuateable by the cutting of a telephone set wire such as located outside of a residence home, the alarm relay switch-actuating circuit being connected to either battery or DC-rectified AC-power source, the detector and actuating circuitry of a preferred embodiment including positive and negative leads connectable to telephone wire contacts of corresponding polarity, each lead including adjacent to the respective contacts, in series, a resistor, the respective resistors being connected to different terminals of each of a third resistor, a capacitor, a zener diode, and a field effect transistor (FET), the negative lead being connected to the FET gate terminal and to the diode such that electrons are flowable solely from said negative lead to said positive lead, and said postive lead being connected to each of the FET source and to a base of typically an NPN transistor, the FET drain being connected in series through a fourth resistor and a relay switch coil to the NPN collector, the relay switch being actuateably closeable of an alarm power circuit, the NPN emitter being connected to one terminal of a second capacitor and to a DC power source terminal of the relay alarm switch-actuating circuit, and the remaining relay switch being connected to each of the remaining terminal of the second capacitor and the remaining coil lead to the relay switch, the relay alarm switch-actuating circuit preferably including, in series, the relay actuating coil, the NPN transistor, a step-down transformer coil, and a rectifier diode permitting DC current to flow toward each of said collector and said drain.

Combustion engine driven generator including spring structure for oscillating the inductor at the mechanical resonant frequency between power strokes

Abstract: A generator in which the inductor is operatively connected to spring structure to be periodically oscillated relative to an induced current coil, at frequencies of mechanical resonance and responsive to irregular power strokes of an engine piston.

Novelty electric motor

Abstract: A permanent magnet armature is arranged to be moved initially in spaced proximity to an induction coil connected in an electric circuit including a source of electric potential and an electronic switch such that when the moving magnetic field of the magnet cuts the coil turns the resulting induced current operates the switch momentarily to connect the source of electric potential across the coil. The resulting current flow through the coil produces a magnetic field which is imposed upon the moving magnet such as to accelerate its movement. The magnet may take many forms, such as a spinning top, a motor rotor, a pendulum or other reciprocating member, and others.

Flywheel magneto ignition device with capacitor-thyristor ignition combined with generator

Abstract: A flywheel magneto ignition device with capacitor-thyristor ignition combined with generator comprises a first component group for producing an ignition effect and a second component group for generating current for lighting and/or battery charging purposes, the first component group comprising a rotor having mounted therein permanent magnets the pole of which are arranged to coact with coils containing at least one coil core and intended for the capacitor-thyristor-ignition circuit, and the second component group comprising a system of coils provided with iron cores and fixedly mounted in a rotating magnetic field from a body corotating with the rotor in the first component group, the rotor and the corotating body being mechanically connected together but with the respective magnetic fields shielded from each other.

Electromagnetic high energy impact apparatus

Abstract: An apparatus utilizing electromagnetic energy for producing high impact forces by means of a ram propelled against a work piece. A specific utilization of the apparatus is in the installation of fasteners such as rivets in structural assemblies. The apparatus described herein is the work center of an electromagnetic impact tool and comprises the following components: electromagnetic high energy pulse coil, ram means, aerostatic bearing means and connector means.

The Prediction of Current Distribution in Induction Heating Installations

Abstract: This paper describes a coupled equivalent circuit approach for predicting the current distribution in three-dimensional geometries having axial symmetry. Specimens of arbitrary cross section can be handled by this numerical method so long as they have circular symmetry about the coil axis. Several self-inductance and mutual inductance formulas are investigated, and the merits of these formulas for calculating the parameters for the equivalent circuit are compared. Experimental and theoretical results are compared for a variety of geometries. Current density probes were used to obtain the experimental results.

Force on a Coil Moving over a Conducting Surface Including Edge and Channel Effects

Abstract: The lift force FL and the drag force FD on small conducting coils placed near a large rotating conducting cylinder have been measured as functions of velocity, height, and coil geometry These data are compared with exact calculations based upon Fourier transforms for coils moving over infinitely wide flat plates By placing the coil near the edge of the cylinder, the effect of the edge on FL and FD and the transverse force FT were studied A channel was then cut in the cylinder, and the properties of a U‐shaped guideway were examined Both the edge effects and channel effects were compared with approximate calculations Agreement was generally good, substantiating a variety of predictions for the large magnets proposed for the suspension of high‐speed ground vehicles

Thermodynamic parameters of helix-coil transitions in polypeptide chains

Abstract: The aim of this paper is to outline new possibilities of more detailed thermodynamic analysis of helix-coil transition parameters, particularly with respect to their splitting into energy and entropy terms. Because of difticulties with the ternary systems, water--organic solvent-polypeptide, or, two organic solventspolypeptide, caused particularly by the phenomenon of specific sorption of one solvent component, the discussion is restricted to water soluble synthetic polypeptides whose limited range can fairly be extended by copolymerization. lt is shown how the combination of data from dillerent experimental sources (optical rotatory dispersion, potentiometric titration curves, intrinsic viscosity. calorimetry) can yield an average number of monomer units in the helical region in the middle of the transition. The parameters characterizing the initiation and elongation ofhelical regions determined for a number of polypeptides dillering only in their side groups give us valuable information about the intramolecular interactions in polypeptide chains. There is also a significant correspondence between the helix coil equilibrium constants of natural amino-acids in aqueous media and the distribution of these amino-acids among helical and non-helical regions in globular proteins. This correspondence, tagether with a treatment of intramolecular interactions, can serve to predict the secondary structure of globular proteins from the primary one.

Implantable, non-contacting nerve stimulating transducer

Abstract: An implantable transducer for stimulating a nerve without contacting it includes a subcutaneous receiver coil having a low number of turns, of the order of six, which is implantable in an accessible location. A magnetic core including first and second separable sections is placed to form a complete magnetic path around the nerve desired to be stimulated, and an excitation coil having about three turns is wound around one section of the core. A pair of conducting wires connect the excitation coil with the receiver coil. The nerve is stimulated by placing an external coil of like dimensions adjacent the receiver coil and pulsing it electrically.

Position sensor utilizing a primary and secondary shielded from one another by a ferromagnetic shield and a magnet whose position relative to the shield changes the shielding

Abstract: A position sensitive system including an exciting winding, a sensing winding, a ferromagnetic shield therebetween, and a magnet, the shield and the magnet being relatively movable. The magnetic skin depth is a function of the distance between the shield and the magnet, whereby voltage induced in the sensing coil by the exciting coil is a function of that distance. For any given set of parameters there will be a range wherein the depth of the magnetic skin of the shield is increased as the distance between the shield and the magnet is reduced, whereby voltage induced in the sensing coil increases as said distance decreases, and vice versa. This provides transducer capability which may be applied to proximity detection, mechanical excursion detection, and other uses. Examples of specific adaptations are as a position detector and, when coupled to either an elastic diaphragm or piston, as a pressure transducer.

Article roll over device

Abstract: A coil of metal or paper strip to be upended or downended is placed on one bed of a cradle which is constructed of semicircular vertical parallel plates and which is mounted in rolling engagement on a track beneath the cradle. The cradle is then rolled along the track one-quarter turn or 90* by a drive system to axially reorient and laterally transfer the coil. As the cradle reaches its end point, the upended or downended coil then rests on a second bed of the cradle perpendicular to the initial bed. A loading conveyor chain extends into the bed which initially receives the coil to carry the coil to the bed and an unloading conveyor chain extends from the bed onto which the coil is transferred for carrying the coil from the bed.

Detection coil systems for vibrating sample magnetometers

Abstract: The design of detection coil systems for use in vibrating sample magnetometers is discussed with particular reference to those magnetometers which are mounted on conventional iron cored magnets. Experimental results are presented for two distinct types of coil arrangements which can be fitted into a 2 in (5.1 cm) air gap. It is found that one of these coil arrangements possesses an extremely broad saddle point. For example, the equilibrium position of the vibrating sample can be displaced by +or-2.6 mm, +or-6.4 mm or 4.8 mm in the x, y or z directions without causing a change of more than 1% in the output voltage from the detection coils.

Sensor noise in low-level flux-gate magnetometers

Abstract: The noise mechanism in a well-designed magnetometer is shown to be due to small-scale magnetic moments which are probably small volumes of the core material that are not oriented by the drive field. Design developments include the sense coil radius and the development of a drive waveform which yields considerably improved performance over the commonly used sine wave drive.

Electrical connecting device

Abstract: An electrical connecting device, which is immersible remote controlled and able to transmit also remote control or telemetry signals. A primary coil (15) connected to the primary circuit is arranged upon a support or rod (1) in order to be displaceable, together with the magnetic core component integral with it, relatively to the secondary coil (16) with its magnetic core portion, all this in such a fashion as to create inductive coupling for the transmission of alternating (three-phase) electrical power, and to enable said two parts to be arbitrarily interpenetrated and parted from one another, in a single operation and whatever the orientation.

Deviation detecting apparatus

Abstract: A deviation detecting apparatus having a primary coil for generating an alternating magnetic field, and a secondary voltage inducing device disposed to oppose said primary coil with a space therebetween and producing a secondary voltage in accordance with the alternating magnetic field caused by said primary coil. In this case, said secondary voltage inducing device consists of four secondary coils, said four secondary coils being arranged in square and made up by winding two electrically insulated wires in parallel, the two first wires of the adjacent two secondary coils being connected to deliver as an output a sum or difference of induced voltages therein and to form two pairs of winding groups each of said two pairs of winding groups being connected to deliver as an output a sum or difference of induced voltages therein, the two adjacent second wires being connected to deliver as an output a sum or difference of induced voltages therein and to form two pairs of winding groups in a different manner to that in said first wires, said pairs of winding groups being connected in such a manner that a sum or difference of induced voltages therein is delivered as an output.

Metal base cookware induction heating apparatus having improved control circuit using infra-red temperature sensor

Abstract: A metal based cookware induction heating apparatus having an improved power supply and control circuit comprised of a chopper inverter including a gate controlled power thyristor coupled to and supplying an induction heating coil with periodic energization currents The gating circuit controlling operation of the chopper inverter is controlled by a temperature sensing arrangement that includes an infra-red heat sensor device arranged to view the metal-based cookware or other object whose temperature is to be controlled A constant current amplifier is connected in series circuit relationship with the infra-red heat sensor device across a source of low voltage direct current excitation potential and means are provided for periodically interrupting the view of the infra-red heat sensor device to produce an output alternating current signal component whose amplitude is indicative of the temperature of the metal-based cookware or other object being heated An alternating current amplifier including an adjustable temperature set resistor is coupled to the output from the infrared heat sensor device with the setting of the adjustable temperature set resistor serving to control the gain and establish the temperature level at which the output from the alternating current amplifier attains an operative level of magnitude An output on-off control amplifier either in the form of a Schmitt trigger type of circuit or reed relay is coupled to and controlled by the output from the alternating current amplifier for producing an amplified output on-off control signal representative of the temperature of the metal-based cookware or other object whose temperture is being controlled in accordance with the temperature setting of the adjustable temperature set resistor The on-off output from the temperature sensing arrangement control an inhibit circuit connected to and controlling a zero point sensing and control circuit that in turn controls the operation of a soft starting zero point switching device connected intermediate the rectified ac supply terminals and the thyristor switching device employed in the chopper inverter whereby both radio frequency interference effects and audible noise production by the inductive heating coil during energization periods from the chopper inverter is substantially reduced due to the fact that energization of the coil under the control of the temperature sensing arrangement is inhibited until only the beginning or near the beginning of each half cycle of the rectified full wave potential appearing at the output from the high voltage rectifier To further reduce RFI effects, a smoothing inductor having an inductance L3 and a smoothing capacitor having a capacitance C3 is connected in series circuit relationship across at least one of the commutating components of the chopper inverter power supply circuit The combined impedance of the commutating capacitor, the smoothing inductor L3 and the smoOthing capacitor C3 is capactive in nature and is series resonant with the communtating inductor L1 to establish the commutating period t1 The smoothing inductor and the capacitor serve to shape the output current flowing through the smoothing inductor which is used as the inductive heating coil to substantially a sinusoidal waveshape having little or no radio frequency interference emission effects Additionally, a capacitor switching arrangement is provided for the commutating capacitor C1 which is formed from a plurality of parallel connected capacitors and power rate controlling switching means for switching selected ones of the parallel connected capacitors into effective circuit relationship in the chopper inverter circuit in accordance with a desired rate of power production Where the improved induction heating apparatus is employed in connection with metal-based cookware, the inductive heating coil preferably is in the form of a helically-shaped planar inductive heating coil and is disposed under a heat transparent member such as an infra red transmissive pyroceramic that can form a smooth continuous tabletop over the induction heating unit and itself does not become heated except by conduction and convection from the metal-based cookware The inductive heating coil excites and heats the metal-based cookware directly so that all heat is generated only by the metal-based cookware and no excess waste heat is produced in the manner of known resistance heating units Since the temperature sensing units directly views the bottom of the metal-based cookware through the heat transparent member and controls the application of power to the induction heating coil, temperature control is directly related to the actual temperature of the pan or other object being heated by the induction heating apparatus As a consequence, a considerable improvement in efficiency and reduction of waste heat results Temperature control is accurate, rapid in response and there is no overshout in temperature such as is characteristic of temperature control systems which control the temperature of a heat source which is external to the object being heated Improved arrangements for the heat transparent member, infra-red heat detector, chopper device, and cooling fan together with preferred designs for the inductive heating coil with ferrite core of without to maximize coupling to the metal-base cookware or other object being heated, are described whereby further improvements in efficiency of operation, economy of components and minimum size are achieved

Valve control means and refrigeration systems therefor

Abstract: A control valve device for refrigeration systems in which a solenoid includes an electromagnetic coil about a plunger and a plug, the plunger and plug having opposed surfaces with a magnetic gap therebetween, and the opposed surfaces having compatible substantially conical shapes. An electrical amplifier circuit is connected to the coil and includes a temperature sensing element positioned to respond to temperature at a selected location in the refrigeration system and thereby correspondingly regulates D.C. voltage applied to the coil and the resultant magnetic field acting on the plunger, the plunger moving a valve member to control flow through a valve located in the system. The substantially conical opposed surfaces of the plunger and plug providing a magnetic gap have an included angle of about 30* to about 60*, and preferably of about 45*. A spring device urges the plunger in one direction, the spring device having force characteristics that approximate the force characteristics of the magnetic field so that the plunger movement is substantially linearly proportional to the change in D.C. voltage.

System for detecting an object within a magnetic field

Abstract: The specification discloses a system for detecting a marker secured to an object when the object is positioned within an interrogation zone having a magentic field periodically varying at a predetermined fundamental frequency. The magnetic field is generated by a coil unit including a plurality of loops of rigid hollow metal pipe which is electrically resonated by capacitors and energized by an electrical signal having a frequency equal to the resonant frequency of the electrical circuit. Phase-lock loop circuitry is provided to maintain the drive to the pipe loops at a frequency equal to the resonant frequency of the pipes, irregardless of variance in the load imposed in the magnetic field generated by the pipes. The transmitting pipe loops are also driven by electrical signals of less than full wave, such that the generated magentic field has improved distortion characteristics. The marker of the invention generates detectable signals containing harmonics of the fundamental frequency of the alternating magnetic field. Detection circuitry is provided to detect the harmonic signals generated by the marker. The detection circuit is gated in synchronism with the less than full wave driving signal applied to the transmitting coil. A dropout circuit is provided to disconnect the transmitting circuitry in case a heavy load is imposed upon the magnetic field.

Ground fault detector circuit

Abstract: A ground fault detector providing protection from leakage current to ground by sensing unbalance in supply and neutral conductor currents to actuate a circuit breaker. A solid state circuit including amplifier and detector and having the unbalance signal of a current transformer as an input for energizing a trip coil of the breaker when the unbalance current exceeds a predetermined level. Improved circuitry providing temperature compensation, insensitivity to turn on and other transients and noise, and protection against overheating due to breaker hangup.

Adjustable proximity sensor

Abstract: An oscillatory proximity sensor which detects the presence of a conductor or metal adjacent the coil of an oscillator by virtue of the change in amplitude of the oscillations. The coil, oscillator and detector circuit are located within a probe housing mounted at the sensing location and the oscillator and detector utilize printed, integrated or hybrid circuitry. An adjustable core for the coil provides a sensitivity adjustment.