Showing papers on "Inductive sensor published in 1985"

Web caliper measurement

Abstract: The thickness of a material, such as a web 10 of paperboard, particularly formed and undried paperboard, is measured as the web passes over a roll 14 by positioning measuring apparatus 12 adjacent the web 10 spaced from the roll 14 and independently and simultaneously measuring the separation A between a measuring sensor 24 and the roll 14 and the separation B between the measuring sensor 24 and the web surface and subtracting such latter measurement from said former whereby the difference therebetween indicates the web thickness. In a preferred embodiment, the sensor to roll measurement A is sensed by means of an inductive sensor 24 while the gap between the sensor 24 and the web surface is determined by means of a scanning optical sensor 26.

Differential pressure transducer with measures for compensating the influences of variable noise quantities

Abstract: The output signal of a differential pressure transducer which transforms a pressure difference into an electrical quantity depends not only on the pressure difference, but also on the static pressure to which the differential pressure transducer is exposed, and on the temperature of the differential pressure transducer. In order to compensate the influence of the static pressure and the temperature, the two measuring chamber halves of the differential pressure transducer have sensors which vary in opposite directions. The difference in the sensor values is a function of the differential pressure, the static pressure and the temperature. The sum of the sensor values is a function of the static pressure and the temperature. In an inductive sensor, the ohmic resistance of the sensor serves as a measure of the temperature; in a capacitive sensor, a temperature sensor thermally connected to the outer wall of the measuring chamber measures the temperature. A computing device combines the temperature signal with the sum of the sensor values and the difference of the sensor values in such a way that the output signal of the differential pressure transducer is a function merely of the differential pressure.

Remote sensor with compensation for lead resistance

Abstract: An apparatus (10) increases the accuracy of a signal delivered from a remote analog sensor (22) to an analog to digital converter (58). The output of the sensor (22) is derived from a ratio between the power applied and the sensed parameter; thus, any changes to the power applied affects the accuracy of the sensor (22) output. It is, therefore, advantageous to closely control the voltage applied to the sensor (22). The apparatus (10) monitors the voltage drop across the lead lines (12, 14) which extend between the sensor (22) and a power supply and increases the voltage applied to the sensor (22) by a magnitude corresponding to the lead line voltage drop. The accuracy of the sensor (22) is preserved independent of the lead line (12, 14) length and resistance.

Multiple-phase two-pole inductive sensor with non-wound rotor

Abstract: Multiple-phase two-pole inductive sensor, with non-wound rotor recessed over a half-circumference. The stator 11 includes a primary 5 wound in four poles and a series of secondaries 4, 6, 7. The voltages of the secondaries are combined in order to ensure operation of the sensor as a resolver, as a linear inductive sensor, and as an absolute angular position sensor.

A hydraulic cylinder comprising at least one electric position indicator

Abstract: A hydraulic cylinder (1) with a piston (5) made completely or partially of electrically conductive material comprises at least one opening (19, 20) for the mounting of an electric position indicator (21, 22). The openings (19, 20) are closed in a liquid and pressure-proof manner towards the interior of the cylinder (1) by means of circular plate-shaped bodies (17, 18) glued to the inner surface of the cylinder (1). As the plate-shaped bodies (17, 18) are made of a ceramic material, preferably steatite, they may allow passage of the magnetic field transmitted from the electric position indicators (21, 22). The openings (19, 20) are adapted in the end covers (2, 3) of the cylinder (1) for the determination of the end positions of the piston (5). Furthermore the cylinder may be provided with piston-braking means in the form of seal rings (12, 13). As the piston (5) penetrates the magnetic field, an altered signal indicating the position of the piston (5) will be transmitted from the electric position indicator, which is preferably an inductive sensor. Very narrow inductive sensors being used it is now possible to built these into even very small hydraulic cylinders, so that these inductive sensors can be built into hydraulic cylinders of all sizes without being influenced by the high pressure of the cylinders. The hydraulic cylinder (1) according to the invention may even be manufactured in a very inexpensive and simple manner, and by building in the inductive sensors a previously unknown exact and reliable determination of the positions of the piston may furthermore be obtained.

Sensor device for use with cooking appliances

Abstract: A sensor device capable of accurately sensor humidity using a pair of sensing elements in which the sensor device contains a pair of sensor elements and are negligibly variable against variations in the physical volume of humidity in comparison to variations in the temperature of these sensor elements. The sensor device is comprised of a pair of sensor elements connected in series, in which one of these generates an output corresponding to the physical volume of humidity while sensing is still underway, whereas the other preserves the output so that it cannot be affected by variations in the physical volume, of humidity while sensor characteristics employed to sense the physical volume of humidity are variable depending on temperature; a current control circuit capable of supplying a large amount of current to a serial circuit comprised of a pair of heaters when the temperature of the sensor elements decreases and conversely supplying a small amount of current to the same circuit when the temperature of the heaters rises; and a sensor detecting any variation in signal output from one of the sensor elements.

Pig for continuous measurement and recording of the internal geometry of a pipeline

Abstract: A pig for continuous measurement and recording of the internal geometry, for example the inside diameter, of a pipeline, has measuring sensors and guide and sealing elements which hold and guide the pig centrally in the pipeline. The measuring sensors for the inside diameter are constructed as inductive sensors. The sensors are accommodated in a head arranged on the end face. Each sensor can be constructed as a measuring coil or as a measuring coil with core.

Eddy current brake for motor vehicles

Abstract: The housing hub (5) of an eddy current brake, designed for installation in the drive shaft of a motor vehicle, contains a brake shaft (9) on which is fixed a rotor (6) and which can be coupled to the drive shaft. The housing hub (5) contains the part of an anti-locking device which detects the rotation speed of the brake shaft (9) and controls the excitation voltage of the exciting coils (3) of the eddy current brake. The part which detects the rotation speed is formed preferably of an inductive sensor (51) co-operating with a gearwheel (52) located on the brake shaft (9).

Measurement-bridge circuit for inductive sensors

Abstract: Inductive sensors (L1, L2) are connected in two arms of a half-bridge in a measurement-bridge circuit. A summing point (A), which is connected to a measurement line (1), is connected to the centre tap (1') of the half-bridge and to a wiper of a potentiometer (P2) of a voltage divider, in each case via a displacement resistor (R1 or R2 respectively). A temperature-dependent compensation resistor (R7), which is held at the temperature level of the inductive sensors (L1, L2), is arranged in one arm of the voltage divider. A compensation potentiometer (P3) is connected in parallel with the compensation resistor (R7). A zero-shift caused by a temperature change of the sensors (L1, L2) is compensated for by the temperature-dependent resistance change of the compensation resistor (R7).

Device for detecting a magnetic target in a defined proximity zone

Abstract: Device for detecting a magnetic target in a defined proximity zone, by means of an inductive sensor extended by a line of an electronic card Only the inductive coil L is housed in the sensor 3, the capacitance C being moved to the electronic card The alternating signal at the middle point of the LC circuit is compared with a reference voltage 23 in order to monitor correct operation of the device Application to monitoring the closure of aeroplane doors

Effective-pressure inductive sensor

Abstract: The present invention relates to an effective-pressure inductive sensor. This sensor comprises, inside a chamber 5 of a test body 1, partially delimited by a membrane 6 which is elastically flexible under the action of an external fluid pressure, means 40 for measuring the bending assumed by this membrane 6 along a reference direction 2 perpendicular to a mid-plane 7 of the latter; these means 40 comprise two magnetic sleeves 54 and 55 juxtaposed along a column 43 parallel to the reference direction 2 and solidly attached by one end to a central zone 31 of the membrane 6, and two simple inductors 76 and 77 placed around one respectively of the sleeves 54 and 55 and solidly attached to a support plate 64 with respect to which they are symmetrical to each other and which is itself carried by the body 1; for this purpose, means 70, 71 join the plate 64 to a zone 26 in the wall 8 of the body immediately next to the membrane 6; these means 70, 71 have characteristics of thermal expansion, along the reference direction 2, which are substantially identical to those of the column 43 in order to ensure coincidence of the mid-plane of the plate 64, and of the inductors 76 and 77, and with that of the column 43, which is also that of the sleeves 54 and 55, when the membrane 6 is balanced in pressure, and thus to ensure a compensation of the thermal drifts of the zero of the sensor.

Contactlessly operating electronic device

Abstract: The invention relates to a contactlessly operating device having a sensor, in particular an inductive, capactive, optical or ultrasonic sensor switch, having a defined response range inside which a control lug which approaches the sensor effects a sensor output voltage which varies within wide limits in a manner proportional to their separation from one another. In order to be able to connect such an analog device directly - without interposition of an analog-to-digital converter - to programmable controls or microprocessor controls in conjunction with improved interference immunity, the sensor output voltage is fed to an internal 2 -stage threshold-value generator having "n" digital outputs at which a digital output voltage can be tapped which corresponds to a subdivision of the response range into 2 subranges.