Abstract: The present disclosure relates to a transmitter for a Pulsed Eddy Current system, configured to generate a changing electromagnetic field which induces eddy currents in an object of an electrically conductive material arranged within the electromagnetic field. The transmitter includes a switching device and a transmitter coil configured to be connected to a voltage source. The switching device is arranged for switching a current generated by the voltage source through the transmitter coil. The transmitter coil comprises a plurality of parallel electrically conductive coil layers with a respective damping resistor connected across each of the coil layers, each of the coil layers being connected in series with a respective diode.

Abstract: The present disclosure relates to a transmitter for a Pulsed Eddy Current system, configured to generate a changing electromagnetic field which induces eddy currents in an object of an electrically conductive material arranged within the electromagnetic field. The transmitter includes a switching device and a transmitter coil configured to be connected to a voltage source. The switching device is arranged for switching a current generated by the voltage source through the transmitter coil. The transmitter coil comprises a plurality of parallel electrically conductive coil layers with a respective damping resistor connected across each of the coil layers, each of the coil layers being connected in series with a respective diode.

Abstract: A method of non-contact measurement of a thickness (d) of an object of an electrically conductive material by means of a Pulsed Eddy Current, PEC, system including a transmitter coil and a receiver coil. The method includes, after having turned off a current in the transmitter coil, at the receiver coil, measuring a voltage induced by the decaying magnetic field at a first time point, a second time point, and a third time point. The method also includes calculating a total magnetic flux which is generated by the eddy currents in the object at the first time point and picked up by the receiver coil, by comparing the measured flux at the first time point with a predetermined total flux picked up by the receiver coil when no object is present.

Abstract: A method for determining a present thickness of a work item while being processed in a rolling mill, the method including: acquiring a data signal reflecting a time dependence of an eddy current decay in the work item caused by an applied pulsed magnetic field, determining a thickness parameter value based on the acquired signal, the thickness parameter value being determined from samples in the data signal, the thickness parameter value being dependent on a ratio between a thickness of the work item and a resistivity of the work item, computing a ratio between a reference thickness value of the work item and the thickness parameter value to thereby provide an instantaneous resistivity value, determining a mean resistivity value based on the instantaneous resistivity value, and providing an output signal based on the mean resistivity of the work item and the thickness parameter value, the output signal being indicative of the determined present thickness of the work item.

Abstract: A method of non-contact measurement of a thickness (d) of an object of an electrically conductive material by means of a Pulsed Eddy Current, PEC, system including a transmitter coil and a receiver coil. The method includes, after having turned off a current in the transmitter coil, at the receiver coil, measuring a voltage induced by the decaying magnetic field at a first time point, a second time point, and a third time point. The method also includes calculating a total magnetic flux which is generated by the eddy currents in the object at the first time point and picked up by the receiver coil, by comparing the measured flux at the first time point with a predetermined total flux picked up by the receiver coil when no object is present.

Abstract: A method for determining a present thickness of a work item while being processed in a rolling mill, the method including: acquiring a data signal reflecting a time dependence of an eddy current decay in the work item caused by an applied pulsed magnetic field, determining a thickness parameter value based on the acquired signal, the thickness parameter value being determined from samples in the data signal, the thickness parameter value being dependent on a ratio between a thickness of the work item and a resistivity of the work item, computing a ratio between a reference thickness value of the work item and the thickness parameter value to thereby provide an instantaneous resistivity value, determining a mean resistivity value based on the instantaneous resistivity value, and providing an output signal based on the mean resistivity of the work item and the thickness parameter value, the output signal being indicative of the determined present thickness of the work item.

Abstract: A dimension-gauging system to determine at least one dimension of a non-ferrous, electrically conducting object produces a magnetic field inside the object and changes the excitation of the magnetic field. A signal processing unit measures the reaction of the magnetic field to the change in excitation, obtains an actual field transfer function between the excitation and the measured field reaction and determines the at least one dimension of the object by fitting the measured field transfer function to a predetermined field transfer function, where the predetermined field transfer function represents the dynamic behavior between the excitation and the measured field reaction with the one dimension as a parameter.

Abstract: A dimension-gauging system to determine at least one dimension of a non-ferrous, electrically conducting object produces a magnetic field inside the object and changes the excitation of the magnetic field. A signal processing unit measures the reaction of the magnetic field to the change in excitation, obtains an actual field transfer function between the excitation and the measured field reaction and determines the at least one dimension of the object by fitting the measured field transfer function to a predetermined field transfer function, where the predetermined field transfer function represents the dynamic behaviour between the excitation and the measured field reaction with the one dimension as a parameter.

Abstract: A torque transducer for measuring torque transmitted in a rotating as well as a stationary shaft. The torque transducer comprises a transducer shaft 1 arranged with a cylinder-shaped magnetoelastic region 2 fixed to the cylindrical periphery of the transducer shaft, which cylinder-shaped magnetoelastic region is permanently magnetized in the azimuthal direction. The transducer shaft with the cylinder-shaped magnetoelastic region is surrounded by a winding 4 which is supplied by an alternating current. Further, the winding is connected to a phase-sensitive detector 5. According to the present invention, a magnetic and non-linear ferromagnetic material 3′ is arranged in physical contact with the cylinder-shaped magnetoelastic region 2. The advantages are that the transducer shaft is manufactured independently of the magnetic properties of the shaft material and may substantially consist of a ferromagnetic material.

Abstract: A torque transducer for measuring torque transmitted in a rotating as well as a stationary shaft. The torque transducer comprises a transducer shaft 1 arranged with a cylinder-shaped magnetoelastic region 2 fixed to the cylindrical periphery of the transducer shaft, which cylinder-shaped magnetoelastic region is permanently magnetized in the azimuthal direction. The transducer shaft with the cylinder-shaped magnetoelastic region is surrounded by a winding 4 which is supplied by an alternating current. Further, the winding is connected to a phase-sensitive detector 5. According to the present invention, a magnetic and non-linear ferromagnetic material 3′ is arranged in physical contact with the cylinder-shaped magnetoelastic region 2. The advantages are that the transducer shaft is manufactured independently of the magnetic properties of the shaft material and may substantially consist of a ferromagnetic material.

Abstract: An angular acceleration transducer measures angular acceleration of a torque-transmitting shaft of a drive device, and includes a measuring shaft having a torque transducer and a transducer flywheel, and which is connected to the torque-transmitting shaft in such a way that it follows rotational movement of the torque-transmitting shaft with a known ratio.

Abstract: A method and a system for phase sensitive rectification of signals from transducers driven by an AC excitation signal will be disclosed. The method and system demand a very moderate calculation capacity, thereby to facilitate the use of low cost microprocessors of ordinary speed. The present method and system utilize a sampling being synchronized with the transducer excitation frequency f. Sampling of the sensor signal is performed by an A/D-converter at a high sampling frequency, nf. The sampled signal then is averaged over half a period of the excitation signal frequency, whereby the starting point of the averaging is decided by the time of commutation. This is equal to filtering the sampled signal by a decimating filter. The rectification may then may be preformed with a number sequence sampled by the optimal sampling frequency 2f (twice the excitation frequency only) instead of the sampling frequency nf used for obtaining high resolution.

Abstract: A method for detection of misfiring of an internal combustion engine, wherein the torque of the internal combustion engine is measured with the aid of a torque sensor mounted on the crankshaft of the internal combustion engine and wherein a torque signal is sampled speed-synchronously with the aid of a sensor. A digital filtering of the torque signal is carried out with a digital filter with a finite impulse response which blocks or damps a selection of integer or half-integer multiples of the speed of the internal combustion engine. The selection of speed multiples is substantially dependent on the number of cylinders of the internal combustion engine.

Abstract: A torque transducer comprising a shaft (1) with a circularly polarized ring (2) which, when loading the shaft with a torque, generates an axial static magnetic field in the shaft and wherein the ring is concentrically surrounded by a stationary tubular shell (3) which is freely arranged in relation to the shaft and which is provided with at least one winding (4, 8, 9) for magnetization of the shaft with a given frequency. A phase-sensitive detector (5) connected to the winding supplies a signal corresponding to the content of those voltages with even harmonics which are induced in the winding to the frequency of a controller (6). The controller generates a direct current which is proportional to the signal and is connected to the winding with such a polarity that it counteracts the static magnetic field generated in the shaft. This direct current constitutes a measure of the torque with which the shaft is loaded.

Abstract: The present invention relates to a method and a device for two-shaft force measurement and its application to the determination of tensile force in a continuous web. The device comprises a force-introducing part (4) with two force-measuring parts A and B for determining the forces F.sub.A and F.sub.B, and the force is applied in a torque-free manner around a center of force via a device (3), for example in the form of a deflector roll journalled in bearing brackets (3) placed on the force-introducing part, and wherein the force-measuring parts, due to their built-in design, measure forces F.sub.A and F.sub.B in directions directed through angles .+-..phi.

Abstract: A magnetoelastic torque transducer for measuring, in a non-contacting manner, the torque in a stationary or a rotating shaft. The transducer comprises a shaft (1) with surrounding excitation windings (2, 3) and measuring windings (10, 11). Concentrically with the windings, anisotropic measuring zones are created by applying layers (8, 9), for example in the form of copper strips, on the surface of the shaft. The angle between the strips and a generatrix to the cylinder surface of the transducer shaft is in a preferred embodiment chosen to be .+-.45.degree. (FIG. 5).

Abstract: The content of even harmonics is used in both a method and apparatus for the detection of the disturbing static and quasi-static magnetic fields effects in measurement systems using force and torque transducers operating with magnetoelastic effect. The even harmonic content corresponds to the degree of static and/or quasi-static magnetization and is an input signal to a regulator the aid of the direct current in, for example, a separate winding, reduces the static and/or quasi-static magnetization to zero.

Abstract: A magnetoelastic force transducer according to the invention comprises two closed magnetic circuits. The transducer is constructed in such a way that the reluctance in one of the magnetic circuits will be changed when the transducer is subjected to a force as a result of changes in the magnetic permeability caused by magnetostriction. The second magnetic circuit is formed so as to have an essentially unchanged reluctance when the transducer is loaded and is used to compensate for those changes in the permeability of the material arising for reasons other than magnetostriction.

Abstract: A magnetoelastic force transducer which is compensated for sensitivity drift is provided with a measuring transducer and a reference transducer (1) of the same material. In its simplest form the reference transducer may consist of a toroid. The two transducers are arranged in good thermal contact with one another. The reference transducer is arranged with a winding (2) for excitation with a current which at each moment is proportional to the supply current of the measuring transducer, and with a winding (3) for delivering a reference signal (U.sub.r) proportional to its magnetic flux. The output signal of the reference transducer is rectified in a phase-sensitive rectifier, the output signal of which is compared with a constant reference voltage. The deviation controls the phase position of the control voltage of the rectifier in such a way that the output signal of the rectifier is caused to correspond to the reference voltage.

Abstract: A magnetoelastic torque transducer comprises a shaft, three stationary coils connected in series to magnetize the shaft and three coils to sense moment transmitted in the shaft, and a magnetic casing surrounding the coils. The shaft has three parallel annular zones provided with such anisotropy that the magnetic field in the shaft is deflected by an angle .alpha. relative to a generatrix to the shaft in the outer zones and is deflected by an angle .alpha. to a generatrix to the shaft in the middle zone, the axial extension of both outer zones being substantially half that of the intermediate zone. The angle .alpha. should be at least 45.degree. in order to obtain good sensitivity in the transducer. The excitation coils are arranged concentrically to the shaft, each being located outside an annular zone and the outer excitation coils being wound with substantially half as many turns as the central excitation coil.