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Magnetostrictive linear displacement transducer having preselected zero crossing detector

TL;DR: In this article, a magnetostrictive wire is used to measure liquid level as a function of the elapsed time between an actuation signal and the first zero crossing of the voltage which is induced as the torsional strain passes through the area of influence of the sliding magnet.
Abstract: A liquid level detector of the type in which a magnetostrictive wire extends through the liquid level measurement range and is captured in a tensioned vertical orientation within a stainless steel tube. Liquid level is measured as a function of the time required for a torsional disturbance imparted the wire near the top to travel along the wire to a magnet which is contained within a liquid level float which slides up and down along the tube. The torsional disturbances imparted to the wire by means of a piezoelectric crystal to which the wire is easily clamped. Accuracy is enhanced by measuring liquid level as a function of the elapsed time between an actuation signal and the first zero crossing of the voltage which is induced as the torsional strain passes through the area of influence of the sliding magnet.
Citations
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Patent
02 Jun 2000
TL;DR: In this article, a position feedback system is used to determine the position of movable elements on a path and control the movable element on the path and the programmable controller using positional information from the sensors.
Abstract: The present invention is directed to a machine with a position feedback system and a method for use thereof. The machine includes at least one movable element mounted for movement on a path and at least one programmable controller. The machine further includes at least two absolute or magnetostrictive sensors or the machine includes an absolute sensor and a non-absolute sensor. The programmable controller uses positional information from the sensors to determine the position of the movable elements on the path and control the movable elements. The method includes determining a known position for the movable elements, linking at least two magnetostrictive sensors into one virtual sensor, and/or performing commutation alignment for the movable elements. Determining the position and commutation alignment can occur when the movable elements are stationary or moving.

379 citations

PatentDOI
TL;DR: In this paper, a magnetostrictive transducer measuring system for precisely measuring the liquid level of fuel in an underground tank is described, where a current pulse is applied to the transducers and sonic pulses are simultaneously produced through the interaction of the magnetic field of transducers with the magnetic fields of the magnets.
Abstract: A magnetostrictive transducer measuring system for precisely measuring the liquid level of fuel in an underground tank. The system provides for the measurement of the position of one or more transducer magnets in a tube that are positioned along a length of the transducer wire therein, with one of the magnets fixed in the tube to provide a reference position. A current pulse is applied to the transducer wire and sonic pulses are simultaneously produced through the interaction of the magnetic field of the transducer wire and the fields of the magnets. The sonic pulses are detected by a sensor and the time interval between the detected sonic pulses is determined to determine the distance between the magnets.

49 citations

Patent
20 Jul 1992
TL;DR: In this article, a position detection probe has a magnetostrictive wire stretched between a head and a reflective foot end termination, and a magnet displaceable along the probe and using the sonic pulse propagation time from the magnet to the foot as a position detector, compensation for thermal expansion and thermal change of propagation velocity is made based on the property of the total propagation time along the wire length being a unique function of temperature.
Abstract: In a position detection probe having a magnetostrictive wire stretched between a head and a reflective foot end termination, and a magnet displaceable along the probe and using the sonic pulse propagation time from the magnet to the foot as a position detection parameter, compensation for thermal expansion and thermal change of propagation velocity is made based on the property of the total propagation time along the wire length being a unique function of temperature and calibrating the probe at different temperatures to yield either equations or look up tables of true positions as functions of the total propagation time and the position detection parameter. By mapping wire characteristics at a plurality of magnet positions and temperatures to construct look up tables, wire nonlinearities as well as thermal effects can be compensated for.

46 citations

Patent
17 Apr 1991
TL;DR: In this paper, a magnetic sight gage sensor comprises a sensor for determining the liquid level in a process vessel utilizing a magnetic float on the interior of a tube or sight glass, which is made of a non-magnetic material in order to allow transmission of the magnetic field from the float to the transducers.
Abstract: A magnetic sight gage sensor comprises a sensor for determining the liquid level in a process vessel utilizing a magnetic float on the interior of a tube. The tube is connected at different levels to a process vessel and contains a liquid that is maintained at the same level as the liquid inside the process vessel. A magnetostrictive displacement transducer is coupled to the tube or sight glass on the exterior of such glass, so it is out of the process fluid. The transducer provides signals indicating the position of the float relative to a reference position on the transducer. The tube or sight glass is made of a non-magnetic material in order to allow transmission of the magnetic field from the float to the transducer.

39 citations

Patent
19 Jun 1990
TL;DR: In this paper, a combined magnetostrictive linear displacement detector and a plural location temperature detector are used to produce a composite signal for transmission on a 2 wire transmission line, where the resistances of the temperature sensitive resistors as well as two reference resistors are measured in a predetermined sequence.
Abstract: The present invention is a combined magnetostrictive linear displacement detector and plural location temperature detector. The combined apparatus produces a composite signal for transmission on a 2 wire transmission line. The resistances of the temperature sensitive resistors as well as two reference resistors are measured in a predetermined sequence. The linear displacement is measured by the length of time required for a torsional strain to travel along the magnetostrictive wire to the position of the magnet. A pulse generator generates a predetermined number of pulses for each resistance measurement having pulse period corresponding to the measured resistance, with the minimum such pulse period preferably being greater than twice the maximum time required for a torsional strain to propagate the length of the magnetostrictive wire. An electrical signal is supplied to the transmission line when either said pulse generator generates a pulse or the induced electrical signal is detected. The time between the pairs of pulses indicates the linear displacement fixed by the magnet. The time between pulse pairs is a measure of one of the resistances. The combined apparatus of the present invention also periodically degausses the magneteostrictive wire at a time when no displacement measurement is taking place.

35 citations

References
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Patent
19 Dec 1973
TL;DR: In this paper, a linear distance measuring device is disclosed in which the time it takes a torsion pulse to traverse a sonic waveguide from a movable magnet to a pulse responsive element is determined and converted to a measurement of the distance from the movable magnets to the pulse responsive elements.
Abstract: A linear distance measuring device is disclosed in which the time it takes a torsion pulse to traverse a sonic waveguide from a movable magnet to a pulse responsive element is determined and converted to a measurement of the distance from the movable magnet to the pulse responsive element The position of the magnet, which is moved by an external means such as a machine tool element, can thus be determined precisely

153 citations

Patent
29 Jan 1968

53 citations

Patent
20 Nov 1984
TL;DR: In this article, an ultrasonic distance measuring device for linear distance measurement comprising a tube of magnetostrictive material, a magnet displaceable relative to the tube for generating torsional ultrasonic pulses as a function of electrical pulses produced by a pulse generator and travelling along the tube.
Abstract: The invention relates to an ultrasonic distance measuring device for linear distance measurement comprising a tube of magnetostrictive material, a magnet displaceable relative to the tube for generating torsional ultrasonic pulses as a function of electrical pulses produced by a pulse generator and travelling along the tube, these torsional ultrasonic pulses serving as position signals, and also comprising an ultrasonic receiver coupled to the tube for converting ultrasonic pulses generated in the tube into electrical signals and a measuring circuit for ascertaining the position of the movable magent as a function of the time interval between the signals obtained from the position signals and at least one respective reference signal generated by the presence of an electrical pulse. In accordance with the invention, the ultrasonic receiver for direct detection of torsional pulses is provided as a section of the tube which is circumferentially magnetized on the basis of remanence and a coil surrounding this section in axial direction.

37 citations

Patent
29 Aug 1979
TL;DR: In this paper, a position determining apparatus consisting of a taut electrically-conductive member, a pulse generator to feed a pulse of electric current along the member, and a magnet located at a variable first point along a member, for example on a float on the surface of a liquid the level of which is to be determined, to apply a magnetic field to the member at that point.
Abstract: A position determining apparatus comprising a taut electrically-conductive member; a pulse generator to feed a pulse of electric current along the member; a magnet located at a variable first point along the member, for example on a float on the surface of a liquid the level of which is to be determined, to apply a magnetic field to the member at that point; and a transducer positioned at a second point along the member to sense the arrival at the second point of a mechanical impulse induced in the member by interaction between the current pulse and the magnetic field as the current pulse passes the magnet. A time measuring circuit responsive to the time interval between the feeding of the current pulse and the arrival of the mechanical impulse at the second point is used to determine the position of the first point.

28 citations

PatentDOI
TL;DR: In this paper, the displacement path and time oscillator pulses are counted by two counter groups, and there is computed from the counter state the velocity-corrected position of a measuring head.
Abstract: The method and arrangement contemplates transmitting externally triggered trigger pulses by means of a magnetostrictive line or conductor and such produces echo pulses. Displacement path and time oscillator pulses are counted by two counter groups, and there is computed from the counter state the velocity-corrected position of a measuring head. Consequently, with a higher measuring rate there can be appreciably increased the accuracy of the evaluation of the pulses delivered by the ultrasonic measuring system, there can be obtained further measuring data (velocity and acceleration) by means of the moving measuring head, and there is possible an absolute measurement. Additionally, the resolution of the measured displacement path or distance can be randomly selected by means of the frequency of the displacement path or distance oscillator.

21 citations