RU2298155C1 - Magnetostrictive level meter-indicator - Google Patents

Abstract

FIELD: the invention refers to measuring and transformational technique and is designed for using in quality of a mobile measuring device for measuring and control of liquid highly explosive medium.

SUBSTANCE: the level meter has a body 1, a directional tube 2 out of non-magnetic material, a magnetostrictive acoustic line 3 with a wave reflector 4 and a stabilizer 5 of tension and twisting placed in a discrete filler 6 with small surface friction, an input and output signal electroacoustic transformers 7,8, a float-level element 9 with a constant magnet 10, a limiter 11 of transferring, a working medium 12, a recording generator 13, a reading amplifier 14, a calculation block 15, an indication block 16 and a control bus-bar 17. The changing of the level of liquid 12 in a working cavity of the bode 1 of the arrangement call transferring of the float-level element 9 with a magnet 10 relatively to the acoustic line 3. This reflects dimension of a time interval of the level formed along the acoustic section of the primary transformer with the aid of the recording generator 13 and the reading amplifier 14 which transforms with the aid of the calculation block 15 into a binary code and is reflected by the indication block 16. The technical result is increasing of reliability of the measuring transformation of the level and expansion of technical application.

EFFECT: increases noise immunity and explosion safety of the measuring transformation of the level.

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Description

The invention relates to measuring and conversion equipment and is intended for use as a mobile device for measuring and monitoring the level of liquid media in explosive conditions.

A known level gauge [1], containing a rectilinear sound guide made of magnetostrictive material with a winding distributed along its entire working length and a radiating element (piezoelectric element) mounted on the end surface, along which a float element with a magnet moves, separating the boundary of the liquid medium, as well as a series-connected generator electrical signals, amplifier and solver.

A known level gauge [2], consisting of a rectilinear magnetostrictive sound pipe with a piezoelectric element and a distributed measuring winding, enclosed in a sealed tube along which the float element with a permanent magnet moves, as well as two amplifiers and a pulse shaper, a pulse generator and a deciding unit.

A known level gauge [3], selected as a prototype, contains a straight-line sound duct made of magnetostrictive material with a reflective load and a stationary electro-acoustic transducer, along which a float element with a magnet moves, which fixes the interface level of the controlled medium, as well as a readout amplifier, a coding and calculation unit and recording amplifier.

The marked devices [1-3] have common disadvantages associated with the insufficient reliability of the measurement level conversion and explosion safety, limiting the scope of their technical application. This can be explained by the low signal / noise level, which usually does not exceed the values S / N = 2/1 for [1, 2] and S / N = 5/1 for [3]. Devices [1, 2] have a technologically sophisticated primary transducer with a distributed reading coil, which limits the level measurement range, and device [3] has insufficient explosion safety due to the accepted method of excitation of ultrasonic torsion waves in the waveguide path. These circumstances limit the field of technical application of known devices in technological systems.

The technical result of the invention is to increase the reliability of the measurement conversion when working in explosive conditions and expanding the field of technical use.

This goal is achieved by the fact that in the magnetostrictive level gauge indicator, comprising a housing with a rectilinear magnetostrictive sound conductor fixed along the axis, having a wave reflector at one end and an output electro-acoustic transducer fixed at a reference distance from its other end, and immersed in a working medium where of the section is fixed by a float element with a magnet, mounted on the sound duct with the possibility of longitudinal movement, and the output of the output electro-acoustic transducer the driver through a readout amplifier is connected to the signal input of the computing unit, a guide tube with a discrete filler with low surface friction is installed coaxially with its body, along the axis of which a sound duct is fixed, having a kinematic connection with a tension and twist stabilizer, at the same reference distance from the free end of the sound duct fixed input electro-acoustic transducer connected through a recording generator to another signal input of a computing unit connected to formation inputs of the display unit, and the control input of the recording generator is connected to the control bus.

The device is illustrated by drawings. Figure 1 shows a block diagram of a magnetostrictive level gauge indicator.

Magnetostrictive level indicator (Fig. 1) contains a housing 1, a guide tube 2 of non-magnetic material, a magnetostrictive sound guide 3 with a wave reflector 4 and a tension and twist stabilizer 5 (SNA), placed in a discrete filler 6, input and output signal electroacoustic transducers ( EAP) 7, 8, a float element 9 with a permanent magnet 10, a limiter 11 of displacements, a working medium 12 (liquid G), a write generator 13, a read amplifier 14, a computing unit 15, an indication unit 16, and a control bus 17.

A guide tube 2 is rigidly fixed coaxially with the body of the level gauge 2, along the axis of which a straight sound guide 3 loaded with SNA 5 is installed with a wave reflector 4 at the end, immersed in a discrete filler 6 with low surface friction. On the other hand, the sound duct 3 at a reference distance α from its free end, the output and input EAA 8, 7 are connected, connected to the read amplifier 14 and the recording generator 13, respectively. In the working cavity between the walls of the housing 1 and the guide tube 2 there is a float element 9 with a polarizing magnet 10, which can move into the cavity within the limiter 11, fixing the level of the section of the controlled working medium 12. The outputs of the reading amplifier 14 and the recording generator 13 are connected to the inputs the computing unit 15, and its outputs are connected to the inputs of the display unit 16. The control input of the recording generator 13 is connected to the control bus 17.

The device operates as follows.

Initially, the device (figure 1) is in its original state. Its transfer to the measurement mode is carried out when the signal "Control" is supplied via the control bus 17. The record generator 13 is started. By its signals supplied to the input of the transducer-type electronic transducer 7, ultrasonic torsion waves are excited in the stressed sound duct 3 by means of the SNA 5 under the magnet 10 of the float element 9. They propagate in both directions through sound duct 3 with a phase velocity of V _cr .

By the inverse signal of the recording generator 13, the pulse counter 23 and the trigger 21 of the error of the computing unit 15 are set to the initial state. So, in the counter 23 pulses will be entered binary code N _n correction of the measurement, which takes into account the component of the temperature error at the current time. According to this signal of the generator 13, a single-shot 18 is launched, which generates a negative pulse of a given duration T _mv , which keeps the T-trigger 20 in the zero state at the moment of receipt of the first read pulse from the output of the read amplifier 14.

At the following time instants, the incident torsion wave propagates to the sound guide 3 in the direction of the output EAA 8 and is read with doubled amplitude due to its location at a distance α half-wave from the end of the sound guide 3, is converted into a rectangular video pulse, which charges the T-trigger 20 of computing unit 15 By its signal, the measuring generator 22 of the block 15 is started, generating a series of high-frequency pulses, which are counted by a binary counter 23 pulses.

Another incident torsion wave propagates in the direction of the wave reflector 4, located at the desired distance h _x from the magnet 10 of the float element 9, fixing the current value of the level of the working medium 12 (liquid G) in the housing 1 of the level gauge. Reaches it, reflected without significant loss of wave energy, and propagates through the sound pipe 3 towards the output EAP 8. As a result, after the required time T _x = 2 · h _x / V _{cr, the} reflected wave is read by the output EAP 8, amplified and converted into a rectangular video pulse by the amplifier 14 reads. According to the read signal, the T-trigger 20 of the computing unit 15 is translated into the initial (zero) state.

The operation of the measuring generator 22 of the computing unit 15 is suspended and at the next moment on the n-bit outputs of the counter 23 pulses generated binary code of the desired level h _x working environment:

N _x = N _x.i + N _n.i ,

here N _х.i = Т _х.i · f _o = 2 · h _х.i / V _cr · f _o , f _о is the sampling frequency of the measuring generator 22 of the computing unit 15, the i-th level measurement conversion.

In the event of an overflow of the discharge grid of the counter 23 pulses of the computing unit 15 (an emergency situation), a pulse signal is generated at its transfer output, which triggers the error trigger 21, which generates the Error signal.

Further, the information signals of the computing unit 15 are fed to the inputs of the display unit 16, forming light (sound) information about the current value of the level h _{x of the} working environment. When the signal "Control" is removed on the control bus 17, the generation of information messages (N _х.i ) stops and the device goes into standby mode.

The incident and reflected elastic torsion waves, reaching the free end of the sound duct 3, are repeatedly reflected and, as they pass through the wave guide, they lose their energies until they collapse. Through this time interval, it is possible to re-conduct the measurement conversion, which is the criterion for establishing the polling period T _{OPR of the} primary device converter.

The creation of forced tensile-torsional stresses in the sound pipe 3 by means of SNA 5 and its placement in a discrete filler 6 increase the resistance to mechanical interference of the acoustic path of the level gauge. At the same time, the placement of the output EAA 8 at a reference distance α from the end of the sound duct 3 equal to the acoustic torsion half-wave allows using reflection to double the amplitude of the read signal without additional energy costs along the “write-read” path. This helps to improve the reliability of the conversion and expand the field of technical use of the proposed device.

The limiter 11 displacements sets the stroke of the float element 9 along the sound duct 3, preventing it from mechanical damage.

Using the corrective code N _n allows you to more flexibly correct the component of the temperature error of the measurement conversion during operation of the device with different media and measurement conditions, and helps to expand its functionality.

Noted distinguishes the proposed device from known devices and ensures the achievement of a positive effect, expressed in increasing the reliability of the measurement level conversion and expanding the field of technical use.

Information sources

1. A.S. No. 838381, G 01 F 23/28. BI No. 22-81.

2. RF patent No. 2060472, G 01 F 23/28. BI No. 14-96.

3. RF patent No. 2213940, G 01 F 23/28. BI No. 28-03, prototype.

Claims (1)

A magnetostrictive level indicator, comprising a housing with a rectilinear magnetostrictive sound conductor fixed along the axis, having a wave reflector at one end and an electro-acoustic output transducer fixed at a reference distance from its other end, and immersed in a working medium, where the interface level fixes the float element with a magnet, mounted on the sound pipe with the possibility of longitudinal movement, the outputs of the output electro-acoustic transducer are connected via a reading amplifier the signal input of the computing unit, characterized in that a guide tube with a discrete filler with low surface friction is installed coaxially with its body, along the axis of which a sound duct is fixed, having a kinematic connection with a tension and twist stabilizer, the input distance is fixed at the same reference distance from the free end of the sound duct electro-acoustic transducer connected through a recording generator to another signal input of a computing unit connected to information inputs b display indicator, and the control input of the recording generator is connected to the control bus.

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