SU834626A1 - Device for measuring magnetic field intensity - Google Patents

Description

(54) DEVICE FOR MEASURING THE TENSION OF MAGNETIC FIELD

one

The invention relates to magnetic particle inspection and can also be used in other areas of technology for measuring the strength of magnetic fields, in solenoids, electromagnets, fields around conductors with currents, etc.

A device for measuring magnetic fields is known, comprising a magnetic core, an arrow, a frame with current, the principle of operation of which is based on the interaction of the field in the gap of the magnetic circuit magnetized by the field being measured and the field of the moving element 1

A disadvantage of the known device is low measurement accuracy.

Closest to the present invention is a device comprising a housing, a magnetic needle mounted in the housing rotatably around its axis, a spring associated with the magnetic arrow, and a measuring scale 2.

However, this device is characterized by low measurement accuracy and, moreover, by the nonlinearity of the scale, the maximum value of the intensity of the measured field cannot exceed the coercive force of the arrow material. The device can be used for. measure only the intensity of constant fields.

The purpose of the invention is to improve the measurement accuracy ..

The goal is achieved by the fact that in a device for measuring the intensity of a magnetic field, comprising a housing, a magnetic needle mounted in the housing rotatably around its axis, a spring associated with the magnetic arrow and a measuring scale, the measuring scale is rotatably mounted around the axis of the magnetic needle and is connected to the spring.

The drawing shows the structure of the proposed device for measuring the magnetic field strength and the circuit of forces acting on the magnetic needle.

The device contains a magnetic needle 1 of a magnetically soft material worn on axis 2 and fixed to it fixedly, axis 2 is mounted on support 3 in device case 4, a measuring scale 5 made in the form of a circle, which can fit in device case 4, and its rotation coincides with the axis of rotation of the magnetic needle 1 spring 6, one

the end of which is connected to the axis 2, and the second through the lead 7 to the measuring scale 5, the driven arrow 8, which is fortified coaxially with the magnetic arrow 1.

The device works as follows.

The device is placed in a magnetic field so that the magnetic arrow 1 is directed along the vector H and stands on the zero division of the measuring scale 5, which is along the arrow 10, increasing the spring moment and removing the zero division of the scale from the end of the magnetic arrow, while the magnetic arrow 1 rotates to form an angle. Together with the magnetic arrow on the measuring scale 5, the driven arrow 8 is stirred, freely seated on the same axis as the magnetic arrow. When the angle C is slightly greater than 45 °, the magnetic moment decreases, where Mj is the spring moment. Under the action of a negative moment increment - DM -Mda ,. The magnetic arrow 1 returns abruptly to the zero division of the measuring scale 5 (the magnetic arrow will catch up with the zero division of the scale). Referral arrow B indicates the intensity of the measured field (maximum displacement of the small arrow on the measuring scale). The jump-like return of the magnetic needle 1 to the zero position always occurs when “. 45 ° regardless of the intensity of the variable field. The angle of rotation of the measuring scale 5 relative to the magnetic needle 1 depends only on the strength of the measured field. This is explained next1, it,

The magnetic needle 1 with the spring 6 in the absence of the floor is held on the zero division of the scale. When the field is turned on, for example, between the poles N and S of an electromagnet, the magnetic needle tends to be set along the magnetic field lines of force (along the vector AND under the action of the magnetic moment M aoc generated by the forces F acting on the shoulder av.

I Fae F.2t.sinJ ,, 0)

M

nag

magnetic needle length;

 the angle between the longitudinal axis of the magnetic needle, and the vector N.

The forces F acting on the magnetic needle are variable depending on the angle.

C2)

F mHcos X f

where w is the magnetic charges of the magnetic needle;

H - magnetic field strength.

The magnetic moment with regard to formulas 1 and 2 has the form

 2Psin "-mH cos" t fmH sin2c, (3)

M,

rMfN

From formula 3 it can be seen that the magnetic moment is proportional to H (w and t are constant values; w const, since the magnet is a soft material of a magnetic needle with small H enters the state of magnetic saturation) and has a maximum value at aC of 45 °, and sin2 x 1.

Since the magnetic moment is a 4et field-field function, the proposed device can also be used to measure the strength of variable fields.

The application of the proposed device makes it possible to improve the quality of the magnetic particle monitoring, to exclude the cases of the commissioning of defective parts of machines of a responsible purpose (aircraft, power machines, etc.).

Claims (2)

Invention Formula A device for measuring the magnetic field strength, comprising a housing, a magnetic arrow mounted in the housing rotatably around its axis, a spring associated with a magnetic arrow, and a measuring scale, characterized in that, in order to increase the accuracy of measurement, the measuring scale installed with a return around the axis of the magnetic needle and connected to the spring. Sources of information taken into account during the examination 1. “Aviation and Cosmonautics, 1964, No. 9, p. 76. 2. Elementary physics course. Ed. G.S. Landsberg, Vol. II, M., “Science, 1973.. 313.