SU1298513A1 - Device for measuring linear displacements - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to reduce the temperature error of measurements due to the introduction of a matching unit between the measuring winding of the sensor and the secondary transducer, ensuring a ratio of 2 5 R. R D gK is the co-resistance of the matching unit; R active resistance of the measuring sensor winding current; the nominal value of the module of the magnetic resistance of the working gap of the sensor; Mo is the nominal value of the reactive component of the total magnetic resistance of the working gap of the sensor; S is the relative change in the active resistance of the direct current in the measuring winding of the sensor under the action of the ambient temperature, is the relative change in the nominal value of the reactive component of the magnetic resistance of the working gap of the sensor under the action of the ambient temperature. The device consists of a power supply 1, a mutual inductive sensor 2, a matching unit 3 and a secondary converter 4. 2 Il. with S (L

Description

The invention relates to a measurement technique and can be used to measure linear displacements of various objects.

The aim of the invention is to reduce the temperature error of measurements by introducing a special matching unit into the device.

FIG. 1 shows the structure of a device for measuring linear displacements; in fig. 2 - mutual inductive sensor design.

The device for measuring linear displacements consists of the power source 1 of the mutual inductive sensor 12, matching unit 3 and the secondary converter 4. The power source 1 is connected to the power winding of the mutual inductive sensor 2, to the measuring winding of which the matching unit 3 is connected, the secondary converter 4 is connected to the output of matching unit 3. I

The mutual inductive sensor 2 consists (Fig. 2) of the power winding 5, two sections 6 and 7 of the measuring winding, a ferromagnetic movable element 8, compensated for a ferromagnetic element 9, similar to a ferromagnetic mobile element 8, and a ferromagnetic screen 1O. The power winding 5 is evenly distributed along the direction of the measured movement, section 6 of the measuring winding is concentrated at the end of the mutual inductive sensor 2, section 7 of the measuring winding is distributed with a linearly varying number of turns along the direction of the measured movement. Along the axis of the distributed section 7 of the measuring winding, the ferromagnetic movable element 8 is rigidly connected to the object being monitored (not shown), and a compensating ferromagnetic element 9 is located along the axis of the centered section 6.

. The device works in the following way.

The power source t produces an alternating (sinusoidal) current of stabilized amplitude, which flows through the power winding of the mutual inductive sensor 2 (Fig. 1). As a result, in the measuring winding of the mutual inductive sensor 2

(FIG. 1), an emf of E is induced, defining the relationship:

E.

jcoMI,

(one)

In this case, the total mutual inductance between the power winding 5 (Fig. 2) and the measuring winding is defined by the expression:

w; (x) -

m

W.R, Rio

MO

(1 ± 2SJ

(2)

de W.

- the number of turns of the power winding 5 (Fig. 2) located in the working area;

j and Wj (x) - the number of turns, respectively, concentrated 6 and distributed 7 sections of the measuring winding, located in the working areas; measured movement; the nominal value of the active component of the full magnetic resistance of the sensor working gap.

X -MO

Sign

minus

before f .. in the discharge

(2) corresponds to an increase in ambient temperature.

The voltage at the output of the mutual inductive sensor 2 (Fig. 1) is determined by the expression:

Ua rft. E

Rbx go minus

G1 ±) before 8

(3)

R.

In terms of

Sign

(3) corresponds to a decrease in ambient temperature.

The relative temperature error of the mutual inductive sensor 2 (Fig. 1) is determined by the relation:

CC - and

go

and,

20

25 jq

50

45 where and „, .. and and,

it

20

- the output voltage of the mutual inductive sensor 2 (Fig. 1), respectively, with a change in temperature and under normal conditions.

Taking into account (1), (2) and (3), the minimum value of S (equal to zero) will have a place at the input impedance of the matching unit, determined from the expression:

8X JO

 o, 5 () z l. L XMO SM J

3129

Claims (1)

Invention Formula A device for measuring linear displacements, consisting of a mutual inductive sensor, the informative parameter of which is the number of mutually inductively connected power windings and the measuring winding, an alternating-current AC power source connected to the sensor power winding and a secondary transducer connected to the sensor winding , characterized in that, in order to reduce the temperature measurement error, between the measuring winding of the sensor and the secondary transducer The beneficiary included a matching unit that provides the ratio  Z "o p S, L mo ° f j in Cho about. 5 (where R is the input resistance of the matching unit; 1U ABOUT ABOUT „„ Resistance to direct current of measuring sensor winding; the nominal value of the module of the magnetic resistance of the working gap of the sensor; the nominal value of the reactive component of the total magnetic resistance of the sensor working gap; the relative change in active resistance to direct current in the measuring, winding of the sensor under the action of ambient temperature; relative change in the nominal value of the reactive component of the total magnetic resistance of the working gap of the sensor under the action of ambient temperature. Fig.} "0 lO evj