Showing papers on "Inductive sensor published in 1987"

Inductive sensor for detecting displacement of adjacent surfaces

Abstract: An inductive displacement sensor includes an oscillator circuit that is characterized by primary and secondary pairs of coils disposed on opposing surfaces of adjacent optical segments. Each coil in both coil pairs is alternately positioned along a respective axes perpendicular to a segment displacement axis. The secondary coils are respectively tuned to frequencies above and below the oscillator circuit resonant frequency. Any motion between segments along the displacement axis induces a detectable change in phase between the current and voltage of the oscillator signal.

Electrical sensing system for measuring ferrous particles within a fluid with temperature compensation circuit

Abstract: A magnetic sensor for the collection and measurement of ferrous particles through the use of an electronic tuned circuit is disclosed. The sensor contains an electrical inductance along with an integral magnet to attract ferrous particles suspended in the fluid. The ferrous particles collecting on the magnetic surface of the sensor causes a change in the inductance of the integral coil which is measured by an electronic circuit. The electronic circuit operating in conjunction with the sensor utilizes a parallel tuned resonant circuit and time variant frequency multiplying to eliminate undesired response changes of the tuned circuit due to the temperature change of the sensor. The sensor may be located in environmental conditions which include a large variation in ambient temperature. The disclosed invention provides for compensation of such undesired changes caused by temperature change so that the actual change of the inductance in the sensor can be monitored without interference. The signal output from the circuit disclosed is representative of the amount of ferrous debris accumulated on said sensor.

Inductance divider sensor

Abstract: A method and apparatus for sensing the proximity of a target object includes a sensor inductor (Ls, 38) connected in series with an identical reference inductor (LR, 36) between an input and ground to form an inductive divider network. The sensor inductor is positioned so that its inductance can be varied in response to the proximity of a target object (14, 40) while the inductance of the reference inductor remains constant. Voltage pulses are periodically applied to the divider network from a source (32, 34) and divide across the reference and sensor inductors in accordance with the ratio of the inductances, as varied or not by the presence of the target object. A detector (30) monitors the output of the divider network and provides a target status signal indicative of the proximity of the target object. For low-power operation, the detector circuit and conductive divider network are periodically and momentarily energized in synchronism. This enables configuration of a self-contained, leadless proximity sensor having a battery power source and an optical output.

Design of inductive sensors for magnetic testing of steel ropes

Abstract: The design and operating principles of four inductive sensors for magnetic testing of steel ropes are presented. The magnetic concentrators can maintain the same shape as in Hall-effect leakage flux sensors, but the output signals of the inductive sensors are quite different and depend on the speed of testing. Although the inductive sensors are not as versatile as Hall-effect sensors, they are simpler in operation and can still find applications, especially in the initial and middle stages of the deterioration of the rope.

Inductive proximity sensor

Abstract: An inductive proximity detector has an L.C. oscillating circuit which is damped by the approach of an electrically conducting object (damping member) and an evaluation circuit which determines the damping of the oscillation. To permit particularly easy and reliable determination of the latter, the evaluation circuit is a counting circuit which counts the number of oscillations whose amplitude exceeds a predetermined value (4, 5).

Liquid/solid interface monitoring during direct chill casting

Abstract: An apparatus and method for monitoring the liquid/solid interface position of an alloy ingot being formed by either direct chill or electromagnetically enhanced direct chill casting systems comprising an inductive sensor wire disposed about the mold wall of the casting system, driving the sensor wire to cause a magnetic flux to penetrate into the ingot, and sensing the change in the impedance or components of the impedance of the system. Monitoring the liquid/solid interface position allows ready adjustment to operating controls, such as, containment/stirring inductors, cooling systems and casting parameters, thereby producing a desirable ingot.

Automatic water-level-controlling instrument for boiler

Abstract: The utility model provides an automatic water-level-controlling instrument for a boiler used for automatically controlling the water level of the boiler The instrument comprises two parts: a sensor and a control system The sensor adopts a floating ball inductive sensor with the advantages of continuous and adjustable water level control, high precision, long service life and safety, compared with the common electrode sensor The control system also has the functions of displaying water level in a distant range and acoustic-optic alarming in a situation of excessively high, excessively low and dangerously low water level The utility model is suitable for a variety of steam boilers with an evaporation capacity under 10 tons per hour

Device for extracting the pulse signal from among parasitic signals in a receiver of a railway line circuit

Abstract: The invention relates to a device for extracting the pulse signal from among parasitic signals in a receiver of a pulsed railway line circuit According to the invention, it comprises first and second inductive sensors arranged in proximity to a length of rail and a third inductive sensor arranged in proximity to the other length of rail, the first sensor 9 being linked, on the one hand, to a first input of a first comparator 11 at the output of which the extracted pulse signal is picked off and, on the other hand, to a first input of a second comparator 12 by means of a rectifier circuit 14, while the second and third sensors 10, connected in series, are linked, on the one hand to the first input of an analog multiplier-divider circuit 16 and, on the other hand, to the first input of a third comparator 13 whose second input is connected to the output of the analog multiplier-divider circuit 16 and whose output terminal is linked, on the one hand, by means of a rectifier circuit 15, to the second input of the second comparator 12 whose output terminal is linked to the second input of the analog multiplier-divider circuit 16 and, on the other hand, to the second input of the first comparator 11 by means of a divider circuit 17

Device for eddy-current testing of metal surfaces

Abstract: The invention relates to a device for eddy-current testing of metal surfaces, involving a probe (8) in which an inductive sensor (1) is connected to an analysis element (3) which is additionally connected to a reference part. The output of the analysis element (3) is connected to a display instrument (5). According to the design, a resistor (6) can be connected to the inductive sensor (1) via a switch (7), the resistor changing the impedance by a fixed value. Further according to the design, the reference part is a network (4) without a coil, which is arranged in the probe (8).

Inductive Sensor Arrays for NDE and Robotics

Abstract: The objectives of this research program are to develop and evaluate electromagnetic sensor arrays for use in NDE and robotics. The work at SRI has focused on the use of inductive sensors; parallel work at Stanford University [1] has emphasized capacitive sensors. The previously reported wire-wound coil sensor [2], consisting of a drive coil and several smaller pickup coils, uses a technology that is not well suited for constructing an array. Furthermore, the spatial resolution of such a sensor is limited by the practical size of the pickup coils. In this paper we describe the development of a sensor array that uses printed-circuit technology to overcome these limitations. We expect that printed-circuit technology will simplify the fabrication of an array, permit precise replication of the array elements, reduce the minimum achievable size of individual array elements to improve spatial resolution, and allow the construction of two-dimensional arrays.

Inductive sensor and device for detecting displacements comprising such a sensor

Abstract: The invention relates to an induction sensor detecting displacements. This sensor comprises a body 1 with ferromagnetic properties, having a base 13 with a tubular shape around a central core 15 to which it is connected via a bottom and a detection part 14 extending in an annular sector in the extension of a sector of the said base and limited by two longitudinal segments 17, 18 parallel to the said central core, an electrical coil 16 being placed coaxially in the base around the central core 15.

Inductive signal emitter sensor to trigger an ignition device of an internal combustion engine and ignition device including such an inductive sensor

Abstract: The inductive sensor (1) emits a signal intended to trigger the ignition device of an internal combustion engine. The sensor consists of a stator (8) incorporating tooth-like pole pieces (9) distributed around its edge, and a rotor (10) concentric with the stator also incorporating tooth-like pole pieces (11) which move past those of the stator when the rotor is driven in rotation. The rotor and stator belong to a magnetic circuit and the rotation of the rotor causes a variation of the flux in a coil which, by induction, creates signals at the terminals of the coil. The sensor (1) includes means (C), preferably in the form of teeth (9, 11), for compensating the variation in the reluctance of the substantially circumferential air gap (16) between the teeth (9, 11) resulting from the relative movement of these teeth along a direction ( DELTA ) substantially parallel to the axis of rotation.