RU134631U1 - MAGNETOSTRICTION CONVERTER OF LINEAR MOVEMENTS - Google Patents

Abstract

1. A magnetostrictive linear displacement transducer comprising a measuring device and an electronic transducer, the measuring device being made in the form of an excitation coil wound on a dielectric tube along which a magnetic positioner (one or several) can move freely, which can be connected to a controlled object, inside the dielectric tube there is a sound duct made of a material with a pronounced magnetostrictive effect, and at one end of the sound duct there is fixed a piezoelectric element, while the electronic transducer contains a number of blocks, including an electric pulse generator, an amplifier and a driver of a receiving signal, a calculator, characterized in that the piezoelectric element of the measuring device is made in the form of an electro-acoustic transducer, and the electronic transducer includes a switch connected to said electro-acoustic a converter and an amplifier input, and an amplitude regulator, one of the inputs of which is connected to an electric pulse generator, and the output to with a switch and an excitation coil, while the driver of the receiving signal is made in the form of an amplitude selector connected between the output of the amplifier and the computer, the output of which is connected to the second input of the amplitude controller. 2. The magnetostrictive linear displacement transducer according to claim 1, characterized in that the amplitude selector is configured to tune out interference when an ultrasonic signal is detected by changing the response threshold according to an algorithm developed by the calculator.

Description

Technical field

The invention relates to a measurement technique designed to measure and control the linear movement of a controlled object using ultrasound. It can be used in various mechanisms and machines requiring control and accurate measurement of linear displacements, as well as for measuring the liquid level in a controlled tank.

State of the art

Known analogues designed to measure and control linear movements.

For example, patent RU No. 2347187 is known, “A method for measuring linear displacements and a device for its implementation,” in which a device that implements the specified method for measuring linear displacements contains a magnetostrictive sound duct, three amplifiers, two filters, a first meter of time intervals, the first and second dampers, located at the ends of the magnetostrictive sound duct. In addition, it contains a pulse signal generator, the output of which is connected to the input of the first amplifier, an electro-acoustic transducer fixedly mounted on the magnetostrictive sound duct, an electro-acoustic receiver mounted on the sound duct with the ability to move, or an electro-acoustic transducer mounted on the sound duct with the possibility of moving, the electro-acoustic receiver, motionless mounted on a magnetostrictive sound pipe, as well as a control device, a computer, Itel time intervals. The outputs of the first and second time interval meters are connected to the input channels of the calculator, on the output channel of which an output code is generated.

In the invention according to patent RU No. 2359222 "A method of measuring linear displacements and a device for its implementation" discloses a device that implements the specified method of measuring linear displacements, which contains a magnetostrictive sound duct, a stationary electro-acoustic transducer, a movable electro-acoustic receiver, rigidly connected to a controlled object, acoustic dampers, first amplifier, programmable digital control unit, time meter. It also contains a pulse signal generator, a stationary electro-acoustic receiver mounted on the sound pipe at a distance from the electro-acoustic transducer, a controlled threshold voltage source, a first driver amplifier, a second driver amplifier, a second amplifier, a rectifier, and an analog-to-digital converter.

The disadvantage of analogues is the lack of regulators of the amplitude of the electric pulse in the winding of the excitation coil, which imposes a limitation on the use of magnetic systems and makes the sensor unstable to changes in external factors.

The closest analogue, taken as a prototype, is the invention according to patent RU No. 2222786 "Method for measuring the liquid level by a magnetostrictive level gauge and magnetostrictive level gauge".

The conversion of ultrasonic vibrations into electrical vibrations is carried out by deforming the piezoelectric receiver ferroelectric crystal under the influence of ultrasonic vibrations (piezoelectric effect), and for the time interval of ultrasound propagation, take the time interval between the instant of supply of the generated pulse of a given duration to the excitation coil winding and the instant of formation of converted electrical oscillations on piezoelectric receiver.

A device that implements this method — a magnetostrictive level gauge — contains a sensing element with a sound duct made of magnetostrictive material placed in a dielectric tube, a winding wound on a dielectric tube, at least one float with a magnetic block of n permanent magnets, where n = 1, 2 ... i placed evenly around the sound duct on the insulating shell with the possibility of movement along it, as well as an electric pulse generator, a level determination unit, the first input of which is connected to the master with orosti sound in acoustic line, wherein the electric pulse generator connected to the coil. A piezoelectric receiver and a digital pulse generator from transformed electric oscillations from the piezoelectric receiver connected to the piezoelectric receiver through an converted electric oscillation amplifier from the piezoelectric receiver, a unit for determining the time interval between the time of the generated pulse of a given duration to the excitation coil winding and the time of the formation of electric oscillations on the piezoelectric receiver, the inputs of which are connected respectively to the electric pulse generator and irovatelem digital pulses from the transformed electric oscillations with the piezoelectric, and the output - to the second input of the level determining unit.

The technical result of the prototype is determined by the fact that the generation and supply of an alternating electric signal is carried out in the excitation coil, its conversion to ultrasonic vibrations is carried out in a sound pipe from a magnetostrictive material by means of a magnetoelastic effect at the position of the permanent magnet, the subsequent conversion of ultrasonic vibrations into electric vibrations is carried out on a piezoelectric receiver, by piezoelectric effect.

In this case, it is believed that the time interval between the moment of supply of the generated pulse of a given duration to the excitation coil winding and the time of formation of converted electric oscillations on the piezoelectric receiver (the time of transformation of ultrasonic vibrations into electric oscillations) is equal to the time interval between the time of the formation of the magnetoelastic effect and the time the formation of the piezoelectric effect.

The disadvantage of the prototype is the low accuracy in the measuring ranges of more than 10 meters, due to the attenuation of the ultrasonic wave in the sound pipe when determining the propagation velocity of the sound wave. The absence of regulators of the amplitude of the electric pulse in the winding of the excitation coil imposes a limitation on the types of magnetic systems used and makes the sensor unstable to changes in external factors.

The present invention allows to ensure the specified measurement accuracy to expand the functionality of the device (increase the measurement range, increase resistance to changes in external factors, expand the range of magnetic systems used, avoid the effects of aging elements, etc.).

Utility Model Disclosure

The magnetostrictive linear displacement transducer comprises a measuring device and an electronic transducer.

The measuring device is made in the form of an excitation coil wound on a dielectric tube, along which a magnetic positioner (one or several) can freely move, with the possibility of mechanical communication with the controlled object. Inside the dielectric tube there is a sound duct made of material with a pronounced magnetostrictive effect, which appears when the fields interact — the electromagnetic field of the excitation coil and the magnetic field of the positioner. An electro-acoustic transducer is fixed at one end of the sound duct, which, on the one hand, converts the ultrasonic signal of the magnetostrictive pulse into an electrical signal for further processing in the electronic transducer, and on the other hand, when calculating the speed of propagation of ultrasound in this sound duct, it converts probing electric signal in the ultrasound, which, propagating through the sound duct, is reflected from its opposite end and It is reversed by the same electro-acoustic transducer. The received ultrasonic signal is also converted into an electrical signal and processed by an electronic transducer.

At the input of the electronic transducer there is a switch that controls the operation mode of the electro-acoustic transducer: supplying a probing signal to the measuring device or receiving a magnetostrictive signal from the measuring device. Further, the electronic converter includes the following blocks: a receiving signal amplifier, an amplitude selector, a computer connected in series, and an electric pulse generator connected to an amplitude regulator, the second input of which is connected to the computer, and the output is through a switch with an excitation coil.

The essence of the utility model consists in the use of an amplitude selector and amplitude regulator, which allow maintaining the amplitude and, accordingly, the slope of the front of the receiving signal constant and independent of the attenuation of the ultrasonic wave in the sound duct, i.e. the dependence on the remoteness of the control object, on the characteristics of the magnetic system, on the aging of elements during operation, on external climatic factors is eliminated. In addition, the amplitude selector can be configured to tune out interference when an ultrasonic signal is detected by changing the response threshold according to a special algorithm developed by the calculator. The use of automatic control of the amplitude of the output electric pulse by the input amplitude of the ultrasonic wave allows one to significantly expand the range of applied magnetic systems (both in direction and magnetic field strength), to automate the process of determining the applicability of magnetic systems, and also to expand the scope due to resistance to changing the parameters of the converter taking into account the time and operating conditions.

Description of Graphic Illustrations

The figure shows a structural diagram of a magnetostrictive linear displacement transducer, where the positions are indicated:

1 - measuring device

2 - electronic converter

3 - excitation coil

4 - dielectric tube

5 - sound duct

6 - electro-acoustic transducer

7 - positioner (with a permanent magnet)

8 - switch

9 - amplifier

10 - amplitude selector

11 - calculator

12 - generator

13 - amplitude control

The implementation of the invention

The utility model includes a measuring device 1 and an electronic transducer 2.

The measuring device consists of an excitation coil 3, wound on a dielectric tube 4, inside which is located a sound pipe 5 made of a material with a pronounced magnetostrictive effect. An electro-acoustic transducer 6 is fixed at the end of this sound duct. Along the dielectric tube with the sound duct and the excitation coil, the path of the positioner 7 passes, which must be fixed on the controlled object, the movement of which is controlled and measured by the described utility model.

The measuring device 1 is electrically connected to the electronic transducer 2, namely, the electro-acoustic transducer 6 is connected to the switch 8, the output of which is connected to the input of the amplifier 9 of the receiving signal, the output of which is connected to the input of the amplitude selector 10, which, in turn, is connected to the calculator 11 This is the connection of the processing elements of the receiving signal.

On the other hand, the electronic converter 2 includes an electric pulse generator 12 and an amplitude controller 13 connected to it, the output of which is connected both to the input of the switch 8 and to the excitation coil 3. The electric pulse generator 12 provides the excitation of the electromagnetic field in the excitation coil, and also generates an electric pulse for the electro-acoustic transducer 6, which converts it into a probe ultrasonic pulse, which is necessary to determine the propagation speed of the ultrasound sound in a particular sound duct under specific environmental conditions.

The use of an amplitude selector 10 in the path of processing the receiving signal and amplitude regulator 13 when generating a probe pulse provides an adaptive control method in which the amplitude of the ultrasonic signal at the output of amplifier 9 is kept constant by changing the amplitude of the current in the excitation coil, thereby compensating for the effect of destabilizing factors (temperature, aging of components), and also opens up the possibility of working with magnetic systems with different ary induction magnetic field. This ensures long-term measurement accuracy and reduces the requirements for the applied magnetic systems.

In addition, the amplitude selector 10 can be configured to tune out interference when an ultrasonic signal is detected by changing the response threshold according to a special algorithm developed by the calculator 11.

Magnetostrictive linear transducer operates as follows.

First, the propagation time of the ultrasonic signal through the sound duct from the controlled object to the stationary transducer is measured. The sound pipe 5 has magnetostrictive properties, and has an excitation coil 3 wound over a dielectric tube 4, into which a signal is supplied from an electric pulse generator 12 through an amplitude regulator 13 and a switch 8, which creates a magnetic field in the excitation coil 3. An ultrasonic signal in the sound pipe 5 occurs at the place of interaction of the magnetic fields of the excitation coil 3 and the permanent magnet of the positioner 7, which is located near the sound pipe 5 and is mechanically connected with the controlled object. Ultrasound propagates from the location of the positioner 7 to the ends of the sound pipe 5, is detected by a stationary electro-acoustic transducer 6, is converted into an electrical signal, which, through a switch 8, an amplifier 9 and an amplitude selector 10, is transmitted to a calculator 11. Using the calculator 11, the time interval from the moment of supply of electric pulse into the excitation coil until the detection of an ultrasonic signal, which is directly proportional to the distance between the controlled object (positioner 7) 6 electroacoustic transducer.

Then measure the speed of propagation and the amplitude of the ultrasonic signal over the entire length of the sound path by emitting a sounding ultrasonic signal triggered by an electric signal from an electric pulse generator 12, which was supplied to the electro-acoustic transducer 6 through an amplitude regulator 13 and a switch 8.

The time interval for which the probing ultrasonic signal passes along the entire length of the sound duct and is reflected from its end is recorded and returned to the electro-acoustic transducer 6. The propagation velocity of the ultrasonic signal in this sound duct is calculated from the known length of the sound duct and the time it takes to travel by ultrasound.

The distance between the electro-acoustic transducer 6 and the positioner 7 is calculated by the formula:

where T _PS - the time of reception of the useful signal of the ultrasonic wave (the time interval between the excitation pulse and the pulse allocated by the electro-acoustic transducer),

V _ЗВ is the speed of sound propagation in the sound duct.

The speed of sound in the duct Vst depends on environmental parameters, such as temperature, density, etc., therefore, to increase the accuracy of measurement, it is necessary to calculate the current speed of sound. To this end, the following method for determining the speed of sound is implemented in a magnetostrictive linear displacement transducer: an electric pulse of a certain shape is supplied not to the winding of the field coil, but to the electro-acoustic transducer, while the ultrasonic wave propagates through the sound duct, is reflected from the end, and returns back to the electro-acoustic transducer, and the speed of sound propagation is determined by the formula:

where T _PSO is the time of reception of the useful signal of the ultrasonic wave (the time interval between the probe pulse supplied to the electro-acoustic transducer and the signal of the elastic deformation pulse highlighted by the electro-acoustic transducer),

L _IE - the exact length (nameplate value) of the measuring element of the magnetostrictive linear displacement transducer.

The technical result of the utility model is achieved by self-calibration of the magnetostrictive transducer of linear displacements with respect to the propagation velocity of the ultrasonic wave in the sound pipe, by using the current amplitude amplitude of the output electric pulse from the amplitude of the electrical signal of the input acoustic wave converted by the electro-acoustic transducer, and thanks to the interference selection provided by the amplitude selector.

The main elements of the circuit can be performed, for example, as follows.

The excitation coil 3 is made of a winding wire brand PET-155, wound in a single layer round to round on a fluoropolymer tube 4.

The sound pipe 5 is made in the form of a bar of mild steel grade 10.

The positioner 7 is made on the basis of an annular permanent magnet with axial or radial magnetization.

The switch 8 is made on field-effect transistors according to the electronic key circuit.

The amplifier 9 is made according to the scheme of an inverting amplifier on operational amplifiers.

The amplitude selector 10 is made according to the scheme of a two-threshold comparator, one of the thresholds of which is controlled from a digital-to-analog converter.

The calculator 11 is implemented on the microcontroller type i8051. The electric pulse generator 12 is made programmatically inside the microcontroller of the calculator 11.

The amplitude controller 13 is made according to the scheme of the current generator, voltage-controlled.

Claims (2)

1. A magnetostrictive linear displacement transducer comprising a measuring device and an electronic transducer, the measuring device being made in the form of an excitation coil wound on a dielectric tube along which a magnetic positioner (one or several) can move freely, which can be connected to a controlled object, inside the dielectric tube there is a sound duct made of a material with a pronounced magnetostrictive effect, and at one end of the sound duct there is fixed a piezoelectric element, while the electronic transducer contains a number of blocks, including an electric pulse generator, an amplifier and a driver of a receiving signal, a calculator, characterized in that the piezoelectric element of the measuring device is made in the form of an electro-acoustic transducer, and the electronic transducer includes a switch connected to said electro-acoustic a converter and an amplifier input, and an amplitude regulator, one of the inputs of which is connected to an electric pulse generator, and the output to a switch and an excitation coil, while the driver of the receiving signal is made in the form of an amplitude selector connected between the output of the amplifier and the computer, the output of which is connected to the second input of the amplitude regulator. 2. The magnetostrictive linear displacement transducer according to claim 1, characterized in that the amplitude selector is configured to tune out interference upon detection of an ultrasonic signal by changing the response threshold according to an algorithm developed by the calculator.

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