SU1099292A2 - Device for measuring magnetic field - Google Patents

Abstract

DEVICE FOR MEASURING A MAGNETIC FIELD on auth.St. No. 5311 TO, characterized in that, in order to increase the sensitivity of the element and the accuracy of measurements, the holder is made of three series-connected parts, two of which are identical and made of a material that does not have magnetostrictive properties, and between them a third part is rigidly fixed, magnetostrictive material with the sign of the longitudinal magnetostriction opposite to the sign of the longitudinal magneto, nitrostriction of the ferromagnetic rods .. CO: C CO 0 CO f fO

Description

The invention relates to magnetic measurements and can be used to measure weak constant and alternating magnetic fields.

According to the main author. St. No. 531110, a device for measuring a magnetic field is known, which contains a sensitive element in the form of a piezo-quartz plate with electrodes, at the ends of which ferromagnetic magnetostrictive rods are fixed, in turn, fixed in a holder, and an autogenerator connected to the electrodes of the plate L.

However, the device is not very sensitive, since the steepness of the characteristic of changing the frequency of the oscillator from the intensity of the magnetic field is of little importance. It is desirable to increase the sensitivity of the device, i.e. increase the steepness of the indicated characteristic, which in turn will lead to a measurement accuracy.

The aim of the invention is to increase the sensitivity of the element and the strength of the measurements.

The goal is achieved by the fact that in a device for measuring a magnetic field, there is a sensory element in the form of a piezoquartz plate with electrodes, at the ends of which magnetostrictive rods are fixed, in turn fixed to the holder, and the autogenerator connected to the plate electrodes is made of three in series connected parts, two of which are identical and made of a material that does not have magnetostrictive properties, and between them a third part is rigidly fixed, made and s magnetostrictive material with the sign of the longitudinal magnetostriction opposite to the sign of the longitudinal magnetostriction of ferromagnetic rods.

The drawing shows the functional diagram of the device. The piezoquartz plate 1 with the exciting electrodes 2 and 3 sprayed onto the main surfaces is slightly clamped between two ferromagnetic magnetostrictive rods 4 and 5 The rods are held by means of a holder i consisting of three series-connected parts 6-8, Parts 6 and 8 are identical and made of a material that does not have a magnetostrictive effect & m, and part 7 is rigidly fixed between parts 6 and 8 and is made of a magnetostrictive material with a longitudinal sign minutes magnetostriction opposite sign longitudinal magnetostrictive ferromagnetic rods 4 and 5. Stimulating electrodes are connected to the circuit of the quartz oscillator 9 which provides the self-excitation at the natural frequency of piezoelectric quartz plate. An AT-cut plate of a lenticular shape with thickness-shear vibrations can be used as a piezo-quartz plate. The ferromagnetic rods can be made of an iron-cobalt alloy, and the magnetostrictive part 7 can be made of nickel.

The device works as follows.

When a piezoquartz plate is turned on in a quartz oscillator circuit, oscillations occur at a frequency close to the natural frequency of the piezoquartz plate.

In the presence of a magnetic field with a strength H, the ferromagnetic rods 4 and 5 change their geometrical dimensions, including their length, due to the magnetostriction effect. Suppose that ferromagnetic rods 4 and 5 have positive longitudinal magnetostriction. In this case, due to the elongation of the ferromagnetic rods, the pressure force acting on the piezoquartz plate increases.

At the same time, under the action of the same magnetic field, the middle part 7 of the holder, since it is made of a material having a negative longitudinal magnetostriction, is compressed. Parts 6 and 8 move in parallel to themselves towards each other. This leads to a further increase in the pressure force on the piezoquartz plate.

Under the action of pressure, the natural frequency of the piezoquartz plate changes, which leads to a change in the generated frequency. The points of contact between the ferrite rods and the piezoquartz plate must be chosen in the direction of the maximum power frequency factor. For round

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At the cutoff plates, these points should occur. Additional davits should be located along the X axis of the curve on the piezoquartz plate behind

talla. In this case, the change in the often-account of the use of negative pressure under the action of pressure has a maximal magnitude of the max-magnitude of the max-magnet magnitude. Thus, the 5 holder makes the sensitivity of the quartz oscillator because of the element, and therefore

varies in proportion to the magnitude of the on-accuracy measurement of the acting on

magnetic field strength. magnetic field devices.

Claims (1)

DEVICE FOR MEASURING MAGNETIC FIELD by ed. No. 531110, characterized in that, in order to increase the sensitivity of the element and the accuracy of measurements, the holder is made of three series-connected parts, two of which are identical and made of material that does not have magnetostrictive properties, and the third part made rigidly fixed between them from a magnetostrictive material with a longitudinal magnetostriction sign opposite to the longitudinal magnetostriction sign of the ferromagnetic rods.