SU758032A1 - Vibration transducer - Google Patents

Description

The invention relates to instrumentation technology and is intended to study seismic wave fields in seismic prospecting by the method of three-component observations, control of amp-5 liters and phases of oscillations excited by seismic sources, such as vibrators, the formation of disturbing influences on their primary spool. distributors.

The known vibration transducer of a seismic receiver contains a permanent magnet with an annular gap, a moving coil suspended on springs in the magnet gap, and channels for converting and amplifying information [1].

A disadvantage of the known transducer is the impossibility of obtaining additional information about the orientation of the transducer axis relative to the vertical, zero correction and the law of motion of its moving part along feedback circuits with information about the instantaneous position of the coil and the effect on the frequency characteristics of the moving system.

The closest in technical essence to the present invention is a vibration transducer containing a permanent magnet

2

a coil with a control unit for its movement in the magnet gap, an amplification channel and information signal conversion, an electric bridge consisting of coil windings and resistances, one of the bridge diagonals connected to the high frequency generator and the other to the winding of the input transformer of the amplifying device [2 ].

The drawback of the device is the complexity, determined by the inclusion of an additional galvanometric amplifier (F-117), which complicates the operating conditions because of the need to align its axis vertically and initial balancing. The second drawback is the impossibility of expanding the frequency 20 characteristic of an electrodynamic seismic receiver to zero frequency and restructuring in it its own resonant frequency of oscillations necessary to improve the frequency properties of 25 seismic receivers.

The inability to expand the frequency

The characteristics of vibration transducers with an electrodynamic system in the low-frequency region are due to the fact that at frequencies of about 3

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cue to zero, the emf induced in their windings is so small that no corrections of the frequency characteristics of external transducers with electronic amplifiers make it possible to obtain information about the processes occurring in the region of these frequencies or to get 5 judgments about the constant displacements of the moving system necessary for analyzing the orientation seismic receiver relative to the vertical.

The aim of the invention is to expand the frequency range.

This goal is achieved by the fact that in the converter into the bridge the windings of the moving coil are made in a differential circuit and are symmetrically located along the coil, the device contains a current regulator in the coil windings connected by differential connection to the input of the coil moving control unit .

FIG. 1 shows the constructive scheme of the converter; in fig. 2 is a schematic diagram of its activation in sensor mode using an external 25 generator; in fig. 3 - the same, but with an internal controlled generator; in fig. 4 - in the mode of the causative agent of harmonic oscillations in the scanner of the optical-electronic tracking system.

In case 1 a magnet 2c 30 is installed by a magnetic core 3 and pole pieces 4 and 5. In the annular magnetic gap between the pole pieces on the iris springs 6 and 7 a moving coil 8 is fixed with windings 9 and 35

10. Both windings are located along the coil length symmetrically with respect to the axis of symmetry OX of the magnetic flux - in the gap. The connection of the windings is made opposite. 40

In the electrical circuit (see FIG. 2), windings 9 and 10 with two external complex resistances (capacitors) 11 and 12 are combined into an electrical AC bridge. One 45 diagonal bridge 13, 14 is connected to an external high-frequency voltage generator through the winding 15 of the transformer 16. The connection point 13 of the windings is connected to the zero lead 59 of the 17 bipolar power supply system 18 and 19. The second diagonal 20, 21 of the bridge is connected to the DC controllers current strengths of windings 9 and 10, performed on transistors 22 and 23. $$

according to the scheme of emitter followers with limiting resistors 24, 25 and a dual variable resistor 26.

The axis of the variable resistor is equipped with a pointer and a scale 27 "natural frequency". The base circuits contain resistors 28, 29, which are symmetrically differentially connected via stabilizers 30, 31 to point 32 of the input signal for controlling the movement of the coil. In addition, the diagonal 20, 21 65

connected to the channel of conversion and amplification of information, consisting of a matching transformer 33 with windings 34, 35 and a coupling capacitor 36, a balanced rectifier (BV) 37 and an amplifier 38 with an output 39.

A DC amplifier is additionally connected to the output of the BV 37

40 with an additional input 41 and an exit point 42. A jumper 42-32 connects the output of the DCIF 40 to the input of a control signal for moving the coil. If the converter is intended for its use as an oscillatory displacement sensor, then the UFT 40 is supplied with a constant-component filter,

On the contrary, if the converter is designed to excite mechanical oscillations with a given law of motion and strict zero position of the moving system, the DCF 40 is performed with a wide frequency bandwidth, and the auxiliary input 41 is connected to a reference voltage source with a given amplitude and waveform.

BV 37 is made according to the standard scheme.

It contains a transformer 16 with a winding 43, to the terminals 44 and 45 of which an external high-frequency generator is connected, symmetrical windings 46, 47 of diodes 48, 49 and two KS filters 50, 51 and 52, 53 connected to output 54.

FIG. 3 electric bridge converter is formed by its windings 9, 10, the complex resistance of capacitors 11, 12 and windings 55,

56 matching transformer 57.

Its winding 58 with a capacitor 59 is connected to the input of a controlled generator (UG) 60. The winding 61 of the output transformer 62 is connected to the supply diagonal 13, 14 of the bridge, and the winding 63, 64 to the output of the UG 60 and the input of the normalizing converter (NP) 65, which has output from block 66. The internal feedback circuit (OS) 67 NP 65 is connected to UG 60. ·

Similar to the diagram in FIG. 2, if the converter is intended to excite mechanical oscillations with the same conditions, the TFT 40 is also performed with a wide frequency bandwidth, and the reference voltage source 68 (master oscillator) is connected to the input 41.

In the diagram of FIG. 4 of the optoelectronic tracking system used in the scanner, the electrical bridge is made similarly to the circuit of FIG. 1, 2. Additionally, the circuit is equipped with voltage regulators, made on transistors 69, 70 with resistors in the base circuits 71, 72. The regulators are connected in series with the current regulators and are connected to the inputs with DC 63 with a constant constant filter

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ten

15

20

25

put away. The UPT input is connected via a phase-sensitive rectifier (FCV)

74 with the output of the amplifier 38. The master oscillator 68 of the harmonic oscillations of the scanning frequency is connected to the input 41 of UPT 40 and at the same time to the input of the reference voltage FCV 74.

The converter operates in the constant excitation mode in the moving coil of high-frequency oscillations with a frequency much higher than the conversion frequency with small amplitudes in all of its switching schemes. In the case of excitation of oscillations from an external generator (see Fig. 1, 2), they are created by the current of the winding 15 of the transformer 16 entering the diagonal 13, 14 and flowing along the windings 9, 10 and the complex resistances of the capacitors 11, 12. When the condition of symmetrical arrangement the windings 9, 10 along the length of the coil 8 relative to the axis OX of the magnetic flux in the magnet gap 2 currents in parallel branches 9,

12 and 10, 11 are equal. EMF induction and reactive components of the voltage drop across the windings 9, 10

mutually balanced and, therefore, the voltage signal taken from the diagonal 20, 21 is zero. By applying an external electrical and mechanical perturbing action, shifting the coil 8 from the initial zero position, the equality of the electromotive force in the windings 9, 10 is violated, since the magnetic fluxes that cover them will no longer be equal to each other. As a result, a signal arises in the diagonal 20, 21, which through the capacitor 36 and the windings 34, 35 of the transformer 33 enters the BS 37, fed by the same transformer 16 from the winding 43 and an external source connected to terminals 44, 45.

After straightening and eliminating quadrature interference, the signal goes to node 54, amplifier 38 and external output 39. Therefore, the voltage on node

54 and output 39 is proportional to the moving parameter of the moving coil of the transducer in the direction of the op-amp axis relative to the housing.

In addition, through the windings 9, 10 from the point 17 of the zero potential of the circuit, direct currents flow to the poles 18 and 19 of the source of stabilized power. The magnitudes of the currents are set by regulators consisting, for example, of transistors 22, 23. Control voltages at the bases of the transistors are set through resistors 28, 29 and zener diodes 30, 31 having a symmetrical differential connection with input 32 of a control signal for moving the coil. The magnetic fluxes of the windings have an opposite direction and, interacting with the field of the magnet 2, create counter-directed

35

40

45

50'

55

60

65

strength The resultant of these forces is proportional to the magnitude of the displacement of the coil from the initial zero position and, depending on the direction of the currents, can be directed either in one direction or in opposite directions of the elastic force of the springs 6, 7 of the suspension. In the first case, an increase is achieved, and in the second, a reduction in the own resonant frequency of the moving system, i.e. it is possible to correct the frequency characteristics of the mobile system. In the converter of FIG. 2 correction is carried out by changing the value of the dual resistor 26 on a scale of 27, which leads to a symmetrical change in the currents in both windings. By changing the ratio of currents by changing the voltage at point 32 of the input, it is possible to set the offset of the coil 8 in either direction from its zero position or to apply an additional force to it compensating the effect on the coil of the axial component of its gravity.

By connecting the points 32, 42, the circuit of the internal system of automatic regulation of the balance of currents is achieved. From the output 54 of the BV 37, the feedback signal on the coil position is fed to the input of the UFD 40, where the error signal between the actual average position of the oscillatory motion of the coil and the zero position specified for it is selected by the DC filter. The error signal is generated by the amplifier into the control action, which from the output 42 is fed to the input 32. regulators and restores the specified zero coil position in its oscillatory motion. This achieves the automation of zero correction in accordance with the intended purpose. In addition, by measuring the voltage between points 17 and 42, information on the orientation of the transducer axis relative to the vertical is obtained, since the magnitude of this voltage is proportional to the force that compensates the effect of the axial component of its gravity on the coil - this meets another condition of the invention.

In the considered mode of operation, the transducer is used as an oscillatory displacement sensor with a frequency lying above the corrected own resonant frequency of oscillations of the transducer moving system.

If it is necessary to use a converter as a causative agent of mechanical oscillations, a voltage of a given shape and frequency of oscillations is applied to the additional input 41 of UPT 40. In this case, a dynamic error signal is generated at the input of the UFT.

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between the instantaneous position of the coil and the reference voltage at a given time. UPT 40 generates a control action necessary to move the coil with minimal error relative to the reference voltage and transmits it from output 42 to input 32 of current regulators in windings 9 and 10. Thus, the target condition is fulfilled in automation of the correction of the motion law of the moving system.

In converters according to the scheme in FIG. 3 does not use an external source of high-frequency oscillations, but an internal controlled generator, UG 60. Here, the signal from measuring diagonal 20, 21 of the bridge is taken through a differential transformer 57 with windings 55 ", 56 connected to the bridge. Winding 58 with capacitor 59 forms an oscillating circuit, which the oscillation frequency of the generator is set to UG 60. The voltage is removed to drive the converter from the winding 61 of the output transformer 62. The signal is proportional to the displacement of the coil, comes from the winding 64 to NP 65 and to the output of the device 66. Through a parallel circuit, this signal is fed to the input of UFT 40 and to the OC circuit of a controlled oscillator 67. OC 67 stabilizes and linearizes the characteristics of the converter. The mechanical oscillations of coil 8 cause changes in the feedback coefficient of the high-frequency oscillation excitation circuit and change their amplitude, which NP 65 is converted to an output signal.

If it is necessary to use the transducer as a causative agent of mechanical oscillations in it, it is similar to the device of FIG. 2, to the additional input 41 of the UFT 40 is supplied. the voltage from the source 68 of a given shape and frequency of oscillation. The principle of automating the correction of the position of zero and the law of motion of the mobile system remains unchanged.

In the case of the use of vibration transducers in electromechanical scanners of optoelectronic tracking systems, they are placed on particularly high demands on the stability of the zero position, phase and amplitude of oscillations relative to the reference (reference) voltage. The electro-dynamic vibration transducer included according to the scheme of FIG. 4, meets these requirements in the mode of excitation of harmonic oscillations.

The principle of operation of current regulators in the windings 9, 10 is similar to that considered in FIG. 2 and 3, but here the dual resistor 26 regulates the balance of the position of the moving system in the initial state, and on the power supply circuits, current regulators receive an adjustable voltage taken from the emitters of transistors 69, 70. Symmetrical voltage variation on the bases of transistors leads to corresponding changes in the supply voltage of current regulators and the increments of currents in the windings 9, 10, i.e. to the regulation of the natural frequency of the oscillating system.

The oscillation parameters are set by a sinusoidal reference voltage source 68 applied to the auxiliary input 41 of the UFT 40 and to the FWC 74 input. Automation of the regulation of the natural · frequency and phase of oscillations is carried out in a closed loop of the control system, in which BV 37 operates as a coil 8 oscillation detector, US 38 - as a matching element, FWC 74 - an element comparing the oscillation phase of a system with a voltage reference phase, UFT 73 - an amplifier and a correction element, voltage regulators 69, 70 with current regulators 22, 23 - executive devices, and a vibration converter as an object of regulation. In this circuit, the adjustable parameter is represented by the phase of oscillations, which is a function of the own resonant frequency of the system. Phase angle monitoring at 90® provides the most accurate automatic control of the frequency response of the vibrating system of a vibration transducer.

Automation of the correction of the law of motion here is provided by automatic regulation of the zero position of the coil 8 and the amplitude of its oscillations. This regulatory process proceeds as shown in FIG. 2. In this case, UFT 40 has a channel with filtering the constant component of the signal and a channel with a passband in the frequency range of the excited oscillations. In the first channel, a control signal is generated to correct the position of zero, and in the second channel - to correct the law of motion. However, since the phase of the law of motion is regulated with increased accuracy by the frequency and phase oscillation control loop, a control signal is generated in this circuit that is proportional to the amplitude component of the control error signal. This separation of signal generation in the system of multiply connected regulation provides increased accuracy in achieving a common goal - automating zero correction, the law of motion, and frequency characteristics of the mobile system (meaning amplitude and phase frequency characteristics).

Claims (1)

Claim Vibrating transducer containing permanent magnet 758032 ten a coil with a control unit for moving it in the magnet gap, a channel for amplifying and transforming information signals, an electric bridge consisting of the coil and resistance windings, one of the bridge diagonals connected to the high-frequency generator and the other to the winding of the input transformer of the amplifying device, characterized in that, in order to expand the frequency range, the bridge includes windings of the moving coil, made according to the differential scheme and symmetrically located on the coil, and the device contains a current regulator in the windings of the coil, connected by differential connection with the input of the control unit for moving the coil.