Showing papers on "Inductive sensor published in 1983"

Inductive proximity switch having an oscillator magnetic core and a permanent magnet forming a saturation-sensitive magnetization area

Abstract: An inductive proximity switch including an oscillator a circuit of which has an oscillator magnetic core adapted to be influenced by a trip device for the purpose of actuating an electronic switch. The proximity switch is adapted to detect an approach of the trip device, of a permeable material, through a nonferromagnetic wall so as to enable a triggering of the switching process. A sensor field formed of a magnetic field of a permanent magnet or an electromagnetic, with the proximity switch having a saturation-sensitive magnetization area or region in which the magnetic fluxes of the permanent magnet or electromagnet and oscillator core heterodyne. The inductive proximity switch is adapted to be operated in saturation by a reduction in a magnetic resistance produced by introducing the permeable trip device into the sensor field, damping the oscillator circuit and causing a switching of the electronic switch.

Apparatus for measuring the grain-size composition of powders

Abstract: An improved apparatus for measuring the grain-size composition of powders in which a device for transforming a powder into a gaseous flow of individual particles, a charging chamber in which each particle acquires a charge which is proportional to its surface area, a precipitating capacitor in which the flow of charged particles is separated into various fractions in accordance with the charge on the particles, an electrometric device for measuring the total charge of individual fractions are provided, the electrometric device having inductive sensors of charged particles, the number of inductive sensors being equal to the number of fractions, and an amplifier to which are connected all inductive sensors of charged particles. The improvement comprises a plurality of switching devices, one switching device being provided for each sensor. Each switching device has an input and an output, includes a sealed contact means for avoiding charge leakage from the respective sensors, and is positioned between an inductive sensor and the amplifier.

Monitoring and evaluation device for fault and multiple-sheet monitoring and measurement of thickness

Abstract: The invention relates to a monitoring and evaluation device for fault and multiple-sheet monitoring and measurement of the thickness of sheet-like or web-like materials in processing and manufacturing machines. The object of the invention is to produce a vibration-compensating device which requires fairly small sensors and carries out evaluation in such a way that only comparative values for one side of the transporting line are required. The object is achieved by having at least three sensors on the basic body, arranging the latter to the side of the material transporting line, having the object of the measurement which is to be monitored in one of the two outside sensors at the time of measurement and having downstream of this arrangement an evaluation device, serving for the evaluation and determination of the measured values with regard to changes in measured values due to mechanical vibration and changes due to the presence of the object of the measurement in the sensor. As a result of the invention, the outlay or material and assembly time are reduced and the dimensions of such devices are reduced. Sensitivity can also be increased by the possible use of inductive sensors.

Inductive sensor arrangement and measuring arrangement for its use

Abstract: The invention includes a measuring arrangement and an inductive sensor arrangement with a transmitter coil which is fed by an RF oscillator, and a receiver coil in which an alternating field is induced by the transmitter coil. Transmitter coil and/or receiver coil are subdivided into at least two part-windings which are connected in opposition to one another in such a manner that the induced part-voltages at least partially cancel. The part-windings are arranged with respect to a metallic object in such a manner that when the position changes in at least one direction, the relative position of each individual part-winding with respect to the object changes differently. This results in a different influence on the inductances of the two part-windings with corresponding change in phase angle and output voltage. The relative distance of each part-winding from the object is monitored by means of auxiliary sensors. If the respective distances deviate, the auxiliary sensors produce a compensation signal by means of which errors due to an inclined position of the object or offset object edges can be avoided.

Short-circuit direction indicators

Abstract: The invention relates to short-circuit direction indicators for high-voltage lines fed from two ends in three-phase systems. In such devices, it is usual to use a capacitive sensor for the voltage and an inductive sensor for the current and to transfer the sinusoidal quantities via Zener diodes in trapezoidal form. It is the object of the invention to improve known devices by simple means in such a manner that they still reliably indicate even with a collapse of the voltage in the short-circuit case. This is achieved by the fact that the star or delta voltage triggers a synchronous oscillator (2) which continues to run with the correct phase in the short-circuit case and is used as phase frequency, that the signals (U20, U21) of the sensors (1, 3) are supplied to a drive logic (4) and that the drive logic (4) output is connected to a phase measuring unit (6) consisting of logic gates, the output of which feeds direction indicating elements (LED1, LED2).

Inductive displacement sensor (position pick-up, and coder)

Abstract: The invention relates to an inductive displacement sensor having two magnetic circuits, which are largely decoupled from one another and of which, at least in one, a core controlling the respective electromagnetically active path length determines the inductance ratio of the magnetic circuits and the inductance ratio is preferably determined by measuring the frequency ratio of two oscillator frequencies. The inductances of the magnetic circuits, in a manner largely decoupled from one another, are respectively switched into an oscillator in a frequency-determining manner. The sensor according to the invention scans in a directly integrating fashion, and the core to be scanned need not be tightly surrounded by the coil. The sensor is therefore particularly suitable for directly scanning floats.

Inductive displacement sensor (position encoder, pickup)

Abstract: An inductive displacement sensor (so-called short-circuiting ring sensor) is proposed, by means of which a mechanical displacement can be converted into an analog electric output variable. The sensor consists of an open core on which there is mounted a fixed coil, and the mechanical displacement to be detected is transferred to a single or double short-circuiting ring which is supported displaceably without contact on the core. In order to achieve high flexibility, in particular in the shaping and the characteristic of the sensor, use is made in this case of a core made from packed (stacked) metal glaze (enamel). It is possible in this way to implement displacement sensors, phase-angle sensors and the like.

Detecting the rotational speed of a shaft

Abstract: A device for detecting the rotational speed of a shaft is disclosed, comprising a generator wheel which is in the form of an annular magnet or a toothed wheel, and an inductive sensor e.g. a Hall effect device, which is located opposite the generator wheel and whose output supplies an alternating voltage which is fed through a high- pass filter which filters out any low- frequency super-impositions from the alternating voltage, the high-pass filter having at least two low cut-off frequencies, that is to say, a lower low cut-off frequency and a higher low cut-off frequency.

presence detector for enclosed cases containing aerosol sprays - uses epoxy board sliding under case and detecting self inductance on printed spiral patterns matching base section of cans

Abstract: The device uses inductive sensors, which are each coupled to a self inductance detection circuit. One or more printed circuit boards are in sliding contact with the box. Each PCB comprises several printed spiral circuits which are designed as a function of the shape and dimensions of the metallic part of the objects. The central ends of these spiral circuits are connected by bridges to external connecting strips in order to form the inductive sensors. The output from the spiral circuit is fed to a logic unit, which also receives information on the speed of the aerosol conveyor.

Inductive proximity sensor

Abstract: An inductive proximity sensor has an RF oscillator (6) with saturation-sensitive oscillator magnetic core (7), the state of saturation of which, and thus the state of oscillation of the oscillator (6), can be varied by the approach or removal of an additional magnetic field (N-S), there also being provided an evaluating circuit (18) for the state of oscillation. An inductive proximity sensor is to be created by means of which distances travelled can be continuously detected. For this purpose, it is provided that the oscillator magnetic core (7) is premagnetised to the or up to closely before the transition region from linear magnetisation characteristic to flattened saturation line, that the oscillator magnetic core (7) is located, at least with its saturation-sensitive area, between two magnetic flux conducting pieces (10) for the additional magnetic field (N-S), which extend over the approach path to be detected, and that a magnetic flux bridge (11), which can be moved along the conducting pieces, is provided between the two conducting pieces (10).