RU1832177C - Transformer-type displacement transducer - Google Patents

Abstract

A transformer sensor belongs to the field of instrumentation and can be used to measure displacements. The aim of the present invention is to provide monitoring of the functioning and increase the accuracy of measurements. This goal is achieved by introducing into the transformer sensor the first and second electronic switching units, the first and second nodes for generating control signals of the remote control unit, the source of control signals, the first and second matching devices, the measuring channel and new communications between the nodes and sensor blocks . 2 ill.

Description

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The present invention relates to the field of instrumentation and can be used to measure parameters (linear displacement, acceleration, pressure) of movement.

The purpose of the invention is to provide the ability to control the functioning and increase the accuracy of the sensor measurements.

In FIG. 1 is an electrical block diagram of a transformer sensor for measuring motion parameters; in FIG. 2 - output characteristics.

The transformer sensor contains an alternating voltage source 1, a sensing element 2, which includes two sections 3 of the field winding electrically connected in series according to, the working section 4 and the compensation section 5 of the measuring winding, core 8. symmetrical plate 7, working core (membrane) b movably mounted, first 9 and second 10 electronic switching nodes; the first 11 and second 12 control signal generating units performed on emitter repeaters AI and Aa, respectively; the remote control unit 13 is configured. in the form of a switching element S1; control signal source 14 made in the form of a voltage divider on resistors RI, R2: the first 15 and second 16 matching devices made in the form of voltage dividers on resistors Pz, R-i and Rs, Rfi, respectively; measuring channel 17. comprising an AC amplifier 00

Gj

Yu

N |

wife 18, a half-wave rectifier 19, a low-pass filter 20.

The nodes 11 and 12 of the formation of control signals are made according to the emitter follower circuit and provide the formation of signals of the required level for controlling the electronic switching nodes 9 and 10, respectively, and also perform the matching function between the output of the source of control signals 14 and the control inputs electronic switching nodes.

The matching nodes 15 and 16 are made in the form of voltage dividers on the resistors RS, R4 and Rs, Re, respectively, and ensure matching of the output of the sensing element 2 with the input of the measuring channel 17,

Transformer sensor operates as follows.

| The alternating voltage Unum from the output of the alternating voltage source 1 is supplied to the excitation winding sections 3, in which magnetic fluxes are induced, which induce the EMF in the working section 4 and the compensation section 5 of the measuring winding. When moving the movable ferromagnetic working core (membrane) 6, in the directions indicated in FIG. 1 by arrows, the gap value dr changes, as a result of which the output voltage in the working section 4 of the measuring winding changes as a function of moving the working core due to a change in mutual inductive coupling between the sections of the exciting winding 3 and the working 4 of the measuring winding.

When measuring motion parameters in the operating mode, the remote control unit 13 is in the operating mode (the contacts of the switching element Si are closed), in which the output signal of the control signal source 14 appears in the form of a low DC voltage, which which through the nodes 11 and 12 of the formation of control signals is supplied to the control inputs of the first and second electronic switching nodes.

In this case, the lower keys (N.K.) of the electronic switching nodes 9 and 10 are opened and the signal paths through the upper keys (B, K.) of the electronic switching nodes 9 and 10 are broken, and the working section 4 and the compensation section 5 of the measuring winding are turned on each other in series (the end of the working section 4 and the end of the compensation

sections 5 of the measuring winding are interconnected via a lower key (N.K.) of the electronic switching unit 10). Stress Up

sections 4 and UK with compensation output

sections of the measuring winding are geometrically subtracted on the sections of these windings and the difference resulting voltage U Ep MUic -Up | , which changes in the function of movement of the working core 6, through the open lower key (N.K.) of the switching unit 9 is fed to the input of the first matching device 15.

From the output of the matching device 15, the voltage U Ep enters the input of the measuring channel 17 and then through the amplifier 18 of an alternating voltage, a half-wave rectifier 19 and

low-pass filter 20 is fed to its output, the output of which is U8bix. recorded by standard measuring instruments (voltmeters, recorders and

DR).

The operation of the measuring channel 17 is based on the amplification of the alternating voltage U Ep by the voltage amplifier 18 with its subsequent conversion to a pulsating voltage using

of a half-wave rectifier 19 and then to a direct current voltage using a low-pass filter 20.

Monitoring the functioning of the transformer sensor, for example, before or after installation on the product or during operation, when the measured parameter (for example, the movement of the test object relative to the working end of the sensor) is unknown, is performed as follows.

The remote control unit 13 is set to the Functional test state (the contacts of the switching element S1 are open), therefore

from the output of the source 14 of control signals, a signal appears in the form of a high voltage level, which through the nodes 11 and 12 of the formation of control signals is supplied to the control inputs of the first 9

and the second 10 electronic switching nodes. In this case, the upper keys (V.K.) are opened and the chain of passage through the lower keys (N.K.) of the switching nodes 9, 10, and the Working Section 4 and

compensation 5 measuring windings are turned on among themselves in series according to (the beginning of the working measuring section 4 and the end of the compensation 5 measuring sections are connected to each other through the upper key of the electronic switching unit 9).

The voltages Up from the output of section 4 and UK from the output of section 5 of the measuring winding are summed up on the sections of the measuring winding and the total resulting voltage UrЈip lUic + Up l from the end of section 4 of the measuring winding is fed to the input of the second matching device through the open top switch of the switching unit 10 , the output of which the voltage U Ei p enters the input of the measuring channel 17. At the output of the measuring channel, a calibration voltage and an aliber are generated. the value of which during the manufacturing process (during adjustment) of the sensor is set equal to the value of the output voltage of the output voltage at the end point of the measuring range in the operating mode, i.e., calibrated output voltage. and the sensor form (passport) is recorded.

Thus, if during the operation of the sensor in the Functional control mode, the calibration voltage and calibration are recorded at the output of the measuring channel 17 with a standard measuring device, which corresponds to the previously known calibration voltage (with established maximum permissible deviations from the nominal value) recorded in the formula (passport ) to the sensor, then this indicates that the sensor is in good condition.

The foregoing is explained by the output characteristics of the sensor (shown in solid lines in Fig. 2).

Improving the accuracy of the measurement is achieved due to the fact that the change in the scale of the transformation of the measuring channel 17, due to the departure of its characteristics from time and other destabilizing factors, as well as the temporary departure of the characteristics of the sensitive element, can be taken into account by determining the real scale of the conversion as follows.

Before starting measurements, the sensor is set to the Functional Test mode using the remote control unit 13. At the same time, the voltage of the exciter appears at the output of the measuring channel of the sensor. which is measured with a standard instrument and compared with the calibration voltage recorded in the sensor formula taking into account the permissible deviations from the nominal value (shown in solid lines in Fig. 2).

If the measured calibration voltage is a gauge. (Fig. 2) coincides (or is within the permissible deviations) with the calibration voltage written in the formula (passport) to the sensor, then the displacement measurement results are decrypted according to the calibration (output) characteristic of the sensor given in the formula (with conversion scale m equal to cal. where Q is the range of the measured motion parameter).

If the measured calibration voltage deviates (exceeding permissible norms) from the calibration voltage recorded in the formula

sensor, then it is necessary to determine the real scale of the gmm of the sensor conversion (taking into account the departure of the sensor’s own characteristics) using the formula

C | salibr. 1

miD

n D 1)

where alibr. 1 is the calibration voltage measured by a standard device that differs from the calibration voltage (written in the formula) by an amount

exceeding permissible norms (for example, due to a change in the transfer characteristic of the measuring channel 17). The interpretation of the results of the measurement of displacements in this case is carried out according to

the calibration (output) characteristic of the sensor of 5p (dashed line in FIG. 2), which has a conversion scale mi corresponding to the calibration voltage Unann6p.i.

Claims (1)

Thus, by introducing additional nodes into the sensor, its functioning is monitored and measurement accuracy is improved (by determining the actual scale of the conversion before or during the measurement process (as compared with the prototype. Formula of the invention) Transformer displacement transducer containing a housing located in a ferromagnetic core with a two-section field winding, measuring and compensating working windings, a balancing plate, a movable core, an alternating voltage source, sections of the excitation winding are connected in series according to and connected to the output of the alternating voltage source, characterized in that, in order to improve the accuracy and providing control of functioning, it is equipped with two switching nodes, two nodes for generating control signals, connected in series with the remote node management and source control signals, two matching units and a voltage conversion unit, the inputs of the control signal generating units are connected to the output of the control signal source, and the outputs are connected to the control inputs of the switching units, the output from the beginning of the measuring working winding is connected to the input of the first switching unit, the output from the end of the measuring working winding is connected to the input of the second switching unit, the output from the end of the compensation measuring r, I (Lg Uhishbr. 0 the coils are connected to the first and second outputs, respectively, of the first and second switching nodes, the terminals from the beginning of the compensation winding and the end of the field winding are connected to the ground bus, the second output of the first switching unit is connected to the input of the first matching unit, the first output of the second switching unit is connected to the input of the second the matching unit, and the outputs of the matching units are connected to the input of the voltage conversion unit. I / and alibo. 1 s .: