SU915028A1 - Magnetic modulation pickup - Google Patents

Description

The invention relates to magnetic measurements and can be used to measure constant and variable magnetic fields in geophysics, geology, radio electronics, biophysics, and other fields of science and technology.

Known magnetic modulation ferrite sensor with local excitation, containing a ferrite ring modulator with an excitation winding and ferrite hub rods with measuring windings Γΐ).

The disadvantage of this sensor is a high level of self-radiation, due to the modulation of the magnetic flux passing through the sensor when periodically changing the effective magnetic permeability of ferrite rods as a result of the magnetization of the modulator ring.

- The closest in technical essence to the proposed device is a ferrite magnet modulo2

A single sensor containing a magnetic modulator with an excitation winding, two coaxial hub rods that are magnetically coupled to each other through a magnetic modulator and a non-magnetized magnetic jumper with output windings wound around them, loading windings with resistors and capacitors [2].

The disadvantage of the device is low sensitivity, since the magnetic flux of the measured signal branches out through the magnetic jumpers and modulator, and through the turns of the output windings passes only part of the total magnetic flux of the measured signal. In this case, it is impossible to increase the conversion coefficient, since when the cross-section of the jumpers is reduced, the measured magnetic flux decreases, and an increase in the cross-section leads to a decrease in the modulation degree of the received signal.

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The aim of the invention is to increase the sensitivity and reduce the level of self-radiation device.

This goal is achieved by the fact that in a magnetic modulation sensor containing a ferrite magnetic modulator, an excitation winding and a measuring winding, the ferrite magnetic modulator is made in the form of a ferrite rod with two identical slots arranged parallel to each other and symmetrically relative to the longitudinal and transverse axis of the rod and with four identical holes, the longitudinal axis of which is parallel to the transverse axis of the rod, arranged in pairs between the slits on the longitudinal axis of the rod symmetrically from About its center, the excitation winding is made in the form of two identical windings, each of which connects a pair of adjacent holes, with the axis of the windings perpendicular to the longitudinal axis of the rod, and the measuring winding, the axis of which coincides with the longitudinal axis of the rod, is located between the pairs of holes in the middle part of the rod bounded by slots.

FIG. 1 shows a sensor design with excitation windings and a measuring winding; FIG. 2 - the direction of the magnetic field lines of the exciting field) in FIG. 3 ~ section of ferrite rod in the central section) in FIG. 4 distribution of the effective magnetic permeability along the length of the rod for two values of the exciting field (the upper curve is for a field value equal to zero ·, the lower curve is when the maximum value of the field is reached).

The device includes (figure 1) ferrite rod 1 with slots 2 and holes 3, the excitation winding 4, consisting of two parts, measuring winding 5 ·

The device works as follows.

When magnetization reversal of the local areas of the ferrite rod by the current flowing through the winding 4, the effective magnetic permeability of the middle part of the rod 1 varies within the limits shown in figure 4. In the presence of an external magnetic field whose direction coincides with the longitudinal axis of the rod, the magnetic flux

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penetrating coils of the measuring winding 5 is modulated in amplitude with the frequency of measurement of magnetic permeability. The induced emf in the measuring winding 5 is proportional to the change in the product of the strength of the external magnetic field and the effective magnetic permeability MD (t). The minimum value of MD (1) corresponds to the case of saturation of the rod sections between the holes by the exciting field (Fig. 2), since turning off the end sections of the rod leads to a significant decrease in the permeability of its shape.

In order to reduce the level of magnetic radiation without a noticeable decrease in the sensitivity of the sensor, the cross-sectional area of the magnetic jumpers was chosen to be much smaller than the central part of the rod (FIG. 3).

The use of the proposed device allows to increase the conversion factor by 1.5 “2 times while reducing the level of radiation by 3-4 times compared with the known.

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Claims (1)

Claim A magnetic modulation sensor containing a ferrite magnetic modulator, an excitation winding and a measuring winding, characterized in that, in order to increase the sensitivity and reduce the device's own radiation, the ferrite magnetic modulator is made in the form of a rod with two identical slots parallel to each other and symmetrically relative to the longitudinal and transverse axes of the rod, and with four holes, the longitudinal axes of which are parallel to the transverse axis of the rod, arranged in pairs between the The axes on the longitudinal axis of the rod are symmetrical about its center, the excitation winding is made in the form of two identical 'windings, each of which connects a pair of adjacent holes, while the axes of the windings are perpendicular to the longitudinal axis of the rod, and the measuring winding, the axis of which coincides with the longitudinal 6 915028 the axis of the rod is located between the pairs of holes in the middle part of the rod bounded by the slits.