SU1286915A1 - Pressure transducer - Google Patents

Abstract

The invention relates to converters of mechanical quantities into electrical ones and allows increasing the device's efficiency and linearity of the output characteristic. Differential-displacement transducer converter 2 contains magnetic cores 3 and 4 with primary 5, 6 and secondary 7, 8 windings. Anchor 9, fixed on the rod 10, is offset from the middle of the gap between the magnetic circuits. The pressure acting on the sensing element 1 moves the measles 9, changing the gaps between it and the magnetic cores. The voltage at the output of the sensor is proportional to the applied pressure. Completion of gaps 5 (0.3-0.5) H, ((1.3-1.5) H provides a virtually linear output response at increased sensitivity. 2 W1.

Description

W

go

00 od

about ate

112

The invention relates to instrument making, namely to converters of mechanical quantities into electrical ones.

The purpose of the invention is to increase the sensitivity and linearity of the output characteristic.

FIG. 1 shows the structural scheme of the proposed sensor; in fig. 2 - output characteristics of the sensors.

The device contains an elastic sensing element 1, a differential-transforming transducer 2 displacement containing two magneto wires 3 and 4, on which primary 5 and 6 and secondary 7 and 8 windings are located, measles 9 fixed on the rod 10, which is rigidly associated with the rod 11, and the other with the sensing element 1, the cup 12, on which magnetic conduits 3 and 4 and the bracket 13 with the displacement transducer 2 mounted on it, gaskets 14 and 15 are designed to be installed

the required clearances “Y and 6 between the core 9 and the magnetic cores 3 and 4 in the process of assembling the sensor. The gaps are set so that at a pressure equal to zero, the measles 9 is displaced relative to the middle of the air.

a gap (line 0-0) by 0.5N, where H is the maximum stroke (displacement range) of the sensitive element, and so that (, (0.3-0.5) N; (1.3-1.5) N The primary windings 5 and 6 are interconnected according to each other, the secondary windings 7 and 8 are opposite.

The secondary windings are made with the following winding data: the number of turns of the winding 7 (Wj) is less than the number of turns of the winding 8 (W); Wj -f w

The sensor works as follows

zom.

When the supply voltage is applied to the primary windings of the transformer converter 2, a current I flows in them, which excites the magnetic flux F l in the magnetic core 3, and magnetic flux j in the magnetic core 4. In this case, in the secondary winding 7 induced emf

E o w f

(one)

where to - voltage frequency j

W - the number of turns in the winding 7

and in the secondary winding 8

Ea 2%.

(2)

where W is the number of turns in the winding 8. Since the secondary windings 7 and 8 are turned on counter, the voltage at the output of the sensor

AE E - E

(3)

Substituting expressions (1) and (2) into (3), we obtain

DE u5 (-), (4)

When fed to the pressure sensor P, the center of the sensing element 1 moves in proportion to the pressure and moves the bark 9 up (toward the magnet 4). In this case, the air gaps between the core and the magnetic cores change and a voltage appears at the output of the sensor that increases with increasing pressure.

Determine the dependence of the output voltage of the sensor on the displacement of the core (h).

The magnetic flux is associated with the movement of the core as follows:

(5) (6)

- the magnetic resistance of the air gap, respectively, between the core and the magnetic core 3, the core and the magnetic core 4,

five

W.

Zor respectively between the core and the magnetic core 3, the core and the magnetic core 4 at the zero position of the core (figure 1); the number of turns in the windings 5 and 6;

h - movement of the sensing element; S is the area of the ends of the inner and outer poles of the magnetic conductor;

fio - magnetic permeability of air.

Substituting expressions (5) and (6) c), we obtain

one

DE K (

P

 f-7

S, - h h

Sh

de

„OW / Wg I Sro

to

h .. W,

constant J5 coefficient determined by the design parameters of the sensor;

(eight)

25

Determine the value of n, necessary to obtain LR O at h 0. From expression (7) we find that this condition is fulfilled with n. By substituting expressions (8) into (7), we obtain

 K (

one

five,

5, - h

 / -Q

6 (5, + h))

The sensitivity and linearity of the output characteristics of the proposed sensor is higher compared with the known.

In the known sensors, the number of turns in the secondary windings is the same (Wj Wg) and the measles is in the middle position between the magnetic cores at a pressure equal to zero, i.e. , 5j Op. In this case, equation (9) takes the form:

(ten)

Analysis of equation (10) shows that the sensitivity of a known sensor decreases proportionally to S} and the nonlinearity of its characteristics

H depends on the ratio ---. For

Ohr

higher linearity characteristics.,

it is necessary to reduce the ratio of th „

According to the research

five

50

0

five

. ,,

H

attitude should be no more

  H 0.4. The specified ratio when

Ooh

a given value of H can be obtained by increasing 6, however, this decreases the sensitivity of the sensor.

To compare the output characteristics of the known and proposed sensors, we construct, using equations (9) and (10), the dependences

AE / - / 14

--- fCh) for both sensors.

TO

dE

Dependencies --- f (h) for dia

The movement of the core. H 0.8 mm is shown in FIG. 2, where curve 1 is the characteristic of the proposed sensor with 5i 0.4 mm, §2 t, 2 mm (5 0.5N, 52 1.5H), curve 2 is the characteristic of a known sensor with

mr

 0.8 (5 about 1 mm); curve 3 - 5 characteristic of a known sensor at

- | - 0.4 (b- „2 mm).

The analysis shown in FIG. 2 output characteristics of the proposed and known sensors shows that with greater sensitivity, the proposed sensor has a virtually linear code response, the known is substantially nonlinear (curves 1 and 2), and with approximately the same linearity of the output characteristic, the sensitivity of the proposed sensor is 4 times higher than the known (curves 1 and 3).

. ,,

five

0

five

Claims (1)

Invention Formula A pressure sensor containing an elastic sensing element and a differential transformer displacement transducer, implemented in the form of two transformers, between which magnetic cores are located measles in the form of a disk, rigidly connected with the sensitive element, characterized in that, in order to increase the sensitivity and linearity of the output characteristic, in it, the measles are displaced relative to the middle of the gap between the magnetic cores and, with the end of the first magnetic conductor installed from the side of the sensory element, nta, the gap Sj (0.3-, 0.5) H, and with the end of the second magnetic circuit - the gap S (1.3-1.5) H, where H is the maximum stroke of the sensitive element, and the number of turns of the secondary winding of the first transform i torus W - gk- WP, where W is the number of turns of the secondary winding of the second transformer. 2 Г 0, 1 0.2 0.3 Ot {/ 7.5 / D, i 0.9 W uz. 2 I