CN114152541A - Tuning fork type self-oscillation sensor system - Google Patents
Tuning fork type self-oscillation sensor system Download PDFInfo
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- CN114152541A CN114152541A CN202010927555.6A CN202010927555A CN114152541A CN 114152541 A CN114152541 A CN 114152541A CN 202010927555 A CN202010927555 A CN 202010927555A CN 114152541 A CN114152541 A CN 114152541A
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- 239000012530 fluid Substances 0.000 claims abstract description 20
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- 238000001514 detection method Methods 0.000 claims abstract description 15
- 239000003990 capacitor Substances 0.000 claims description 43
- 239000000919 ceramic Substances 0.000 claims description 21
- 230000003321 amplification Effects 0.000 claims description 14
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 14
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- 239000000463 material Substances 0.000 description 4
- 238000001739 density measurement Methods 0.000 description 3
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/002—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis
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- H—ELECTRICITY
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- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
- H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N9/00—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity
- G01N9/002—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis
- G01N2009/006—Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis vibrating tube, tuning fork
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Abstract
The invention discloses a tuning fork type self-oscillation sensor system. When the density of fluid flowing through the tuning fork vibrating body changes, the resonant frequency of the tuning fork vibrating body changes, the changed resonant signal is amplified and modulated through the amplifying branch, the formed driving signal drives the tuning fork vibrating body to vibrate through the signal driving circuit, so that a self-excited oscillation circuit is formed, the linear relation exists between the frequency change of the tuning fork vibrating body and the density of the fluid, the frequency change of the tuning fork vibrating body is detected by the detection circuit to accurately calculate the density of the fluid at the moment, meanwhile, the tuning fork vibrating body adopts a high-temperature type crystal, so that the tuning fork vibrating body can generate stable signals in a high-temperature environment, and the accurate measurement of the density of the fluid in a well is ensured.
Description
Technical Field
The invention relates to the technical field of oil-gas exploration, in particular to a tuning fork type self-oscillation sensor system.
Background
The density is an important physical property of liquid, and the measurement of the density of the liquid is one of important means for realizing the quality control of products in various industries such as medicine, food, petrochemical industry and the like. In a normal temperature environment, a resonant liquid density measurement sensor is usually adopted to detect the liquid density underground, and the resonant liquid density measurement sensor has the advantages of simple structure, small size, light weight, small abrasion, high reliability, high measurement precision, high efficiency and quick response.
However, in oil and gas exploration, due to the influence of factors such as underground high temperature and high pressure, and the complex structure of the vibrating string method of the resonant liquid density measuring sensor, the frequency and amplitude of the resonant liquid density measuring sensor have certain deviation, and a standard reference signal has temperature drift along with the underground temperature, so that the inherent frequency of a tuning fork body cannot be accurately tracked, the measuring precision of an instrument is influenced, and the application in the field of oil and gas exploration cannot be met.
Disclosure of Invention
In view of this, the embodiment of the present invention provides a tuning fork type self-oscillation sensor system, so as to solve the problem that the frequency and amplitude of a resonant liquid density measurement sensor are affected by high temperature and high pressure in a well during oil and gas exploration, so that certain deviation occurs, and the measurement accuracy of an instrument is finally affected.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
a tuning fork self-oscillating sensor system comprising: the tuning fork vibrating body, the self-excited oscillation circuit, the signal driving circuit and the signal detection circuit;
the tuning fork vibrating body comprises a tuning fork body, a transmitting piezoelectric crystal and a receiving piezoelectric crystal;
the self-oscillation circuit includes: an amplifying branch and a modulating branch; the modulation branch is connected with the transmitting piezoelectric crystal; the input end of the amplifying branch circuit is connected with the receiving piezoelectric crystal, the output end of the amplifying branch circuit is connected with the input end of the signal driving circuit, and the output end of the signal driving circuit is connected with the transmitting piezoelectric crystal;
the amplifying branch circuit can form a driving signal according to the signal of the transmitting piezoelectric crystal; the modulation branch circuit can modulate the received piezoelectric crystal signal into direct current voltage and control the amplitude of the driving signal according to the direct current voltage; the signal driving circuit can drive the transmitting piezoelectric crystal according to the driving signal with controlled amplitude;
and the input end of the signal detection circuit is connected with the tuning fork body.
Preferably, the amplifying branch comprises: an amplifier and an amplifying circuit; the input end of the amplifier is connected with the receiving piezoelectric crystal, and the output end of the amplifier is connected with the input end of the amplifying circuit; the output end of the amplifying circuit is connected with the input end of the signal driving circuit;
the modulation branch comprises: a follower circuit and a signal modulation circuit; the input end of the following circuit is connected with the transmitting piezoelectric crystal, and the output end of the following circuit is connected with the signal modulation circuit;
the amplifier and the amplifying circuit can form a driving signal according to the signal of the transmitting piezoelectric crystal; the signal modulation circuit can modulate the received piezoelectric crystal signal followed by the following circuit into direct current voltage, and controls the amplitude of the driving signal according to the direct current voltage.
Preferably, the vibration frequencies of the tuning fork body, the transmitting piezoelectric crystal and the receiving piezoelectric crystal are consistent.
Preferably, the tuning fork, the transmitting piezoelectric crystal and the receiving piezoelectric crystal have a vibration frequency of 900 hz.
Preferably, the tuning fork body is of a circular fork body structure, a fixed bolt column is arranged inside the tuning fork body, and the piezoelectric ceramic crystal is installed on the tuning fork body through the fixed bolt column.
Preferably, the transmitting piezoelectric crystal and/or the receiving piezoelectric crystal are piezoelectric ceramic crystals.
Preferably, the piezoelectric ceramic crystal is a high-temperature type crystal.
Preferably, the number of the piezoelectric ceramic crystals is multiple and parallel.
Preferably, the first amplifier is an AD 620.
Preferably, the signal driving circuit includes: an EL2001 signal driver, a capacitor C1, a capacitor C2A, a capacitor C2B, a capacitor C3, a resistor R3, and a resistor R4;
a feedback end of the EL2001 signal driver and one end of the resistor R3 are connected with one end of the capacitor C3;
one end of the capacitor C1 is connected with the input end of the amplifying branch circuit, and the other end of the capacitor C1 is connected with the other end of the resistor R3, one end of the resistor R4 and the input end of the EL2001 signal driver;
the other end of the resistor R4 is connected with the grounding end of the EL2001 signal driver and is grounded;
the output end of the EL2001 signal driver is respectively connected with the first end of the capacitor C2A and the first end of the capacitor C2B;
the second terminal of the capacitor C2A and the second terminal of the capacitor C2B are connected to the emitting piezoelectric crystal.
From the foregoing, the present invention discloses a tuning fork self-oscillating sensor system. The tuning fork vibrating body comprises a tuning fork body, a transmitting piezoelectric crystal and a receiving piezoelectric crystal; the self-oscillation circuit includes: an amplifying branch and a modulating branch; the modulation branch is connected with the transmitting piezoelectric crystal; the input end of the amplifying branch circuit is connected with the receiving piezoelectric crystal, the output end of the amplifying branch circuit is connected with the input end of the signal driving circuit, and the output end of the signal driving circuit is connected with the transmitting piezoelectric crystal; the amplifying branch circuit can form a driving signal according to the signal of the transmitting piezoelectric crystal; the modulation branch circuit can modulate the received piezoelectric crystal signal into direct current voltage and control the amplitude of the driving signal according to the direct current voltage; the signal driving circuit can drive the transmitting piezoelectric crystal according to the driving signal with controlled amplitude; and the input end of the signal detection circuit is connected with the tuning fork body. Through the tuning fork type self-oscillation sensor disclosed above, when the density of a fluid flowing through the tuning fork vibration body changes, the resonant frequency of the tuning fork vibration body changes, the changed resonant signal is amplified through the amplification branch, the tuning fork vibration body is driven to form a self-oscillation circuit, and a linear relation exists between the frequency change of the tuning fork vibration body and the density of the liquid, so that the density of the fluid at the moment can be accurately calculated by finally detecting the frequency change of the tuning fork vibration body through the detection circuit, and meanwhile, the tuning fork vibration body adopts a high-temperature type crystal, so that the tuning fork vibration body can generate a stable signal in a high-temperature environment, and accurate measurement of the density of the fluid in a well is ensured.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic connection diagram of a tuning fork self-oscillation type sensor system according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a self-oscillation circuit provided by an embodiment of the present invention;
FIG. 3 is an amplifying circuit diagram according to an embodiment of the present invention;
FIG. 4 is a follower circuit diagram according to an embodiment of the present invention;
fig. 5 is a circuit diagram of a signal driving circuit according to an embodiment of the present invention.
The tuning fork vibrating body comprises a tuning fork vibrating body 1, a self-oscillation circuit 2, a signal driving circuit 3, a signal detection circuit 4, a transmitting piezoelectric crystal 5 and a receiving piezoelectric crystal 6.
The amplifier 201, the amplifying circuit 202, the follower circuit 203, the signal modulation circuit 204, the EL2001 signal driver 205, the capacitor C1, the capacitor C2A, the capacitor C2B, the resistor R3, and the resistor R4.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this application, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
An embodiment of the present invention provides a tuning fork self-oscillation type sensor system, referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of the tuning fork self-oscillation type sensor system of the present application, where the tuning fork self-oscillation type sensor system includes: a tuning fork vibrating body 1, a self-oscillation circuit 2, a signal driving circuit 3 and a signal detection circuit 4;
the tuning fork vibrating body 1 comprises a tuning fork body, a transmitting piezoelectric crystal 5 and a receiving piezoelectric crystal 6;
the self-oscillation circuit 2 includes: an amplifying branch and a modulating branch; the modulation branch is connected with the transmitting piezoelectric crystal 5; the input end of the amplification branch is connected with the receiving piezoelectric crystal 6, the output end of the amplification branch is connected with the input end of the signal driving circuit 3, and the output end of the signal driving circuit 3 is connected with the transmitting piezoelectric crystal 5;
the amplifying branch circuit can form a driving signal according to the signal of the transmitting piezoelectric crystal 5; the modulation branch circuit can modulate the signal of the receiving piezoelectric crystal 6 into direct current voltage and control the amplitude of the driving signal according to the direct current voltage; the signal driving circuit 3 can drive the emitting piezoelectric crystal 5 according to the driving signal with controlled amplitude;
the input end of the signal detection circuit 4 is connected with the tuning fork body.
The self-excited oscillation circuit 2 amplifies a signal received by the tuning fork vibrating body 1 through the amplifying branch circuit to form a driving signal of the oscillation circuit, the signal transmitted by the tuning fork vibrating body 1 is modulated into direct current voltage through the self-excited oscillation circuit 2, and the amplitude of the driving signal can be controlled through the direct current voltage signal, so that the driving closed system is driven to vibrate stably.
It should be noted that, when the density of the fluid flowing through the tuning fork vibrating body 1 changes, the resonant frequency of the tuning fork vibrating body 1 changes, the changed resonant signal is amplified by the amplifying branch, and finally the tuning fork vibrating body 1 is driven by the signal driving circuit 3 to form a self-excited oscillation circuit, and the frequency change of the tuning fork vibrating body 1 has a linear relation with the density of the liquid, so that the density of the fluid at that time can be accurately calculated by detecting the frequency change of the tuning fork vibrating body 1 by the detecting circuit.
The tuning fork vibrating body of the embodiment of the application comprises a tuning fork body, a transmitting piezoelectric crystal and a receiving piezoelectric crystal; the self-oscillation circuit includes: an amplifying branch and a modulating branch; the modulation branch is connected with the transmitting piezoelectric crystal; the input end of the amplifying branch circuit is connected with the receiving piezoelectric crystal, the output end of the amplifying branch circuit is connected with the input end of the signal driving circuit, and the output end of the signal driving circuit is connected with the transmitting piezoelectric crystal; the amplifying branch circuit can form a driving signal according to the signal of the transmitting piezoelectric crystal; the modulation branch circuit can modulate the received piezoelectric crystal signal into direct current voltage and control the amplitude of the driving signal according to the direct current voltage; the signal driving circuit can drive the transmitting piezoelectric crystal according to the driving signal with controlled amplitude; and the input end of the signal detection circuit is connected with the tuning fork body. According to the tuning fork type self-oscillation sensor system disclosed by the above, when the density of a fluid flowing through the tuning fork vibration body changes, the resonance frequency of the tuning fork vibration body changes, the changed resonance signal is amplified and modulated by the amplifying branch, the formed driving signal drives the tuning fork vibration body to vibrate through the signal driving circuit, so that a self-oscillation circuit is formed, and the detection circuit detects the frequency change of the tuning fork vibration body through the linear relation between the frequency change of the tuning fork vibration body and the density of the liquid so as to calculate the density of the fluid at the moment.
Further, the amplifying branch comprises: an amplifier 201 and an amplifying circuit 202; the input end of the amplifier 201 is connected with the receiving piezoelectric crystal 6, and the output end is connected with the input end of the amplifying circuit 202; the output end of the amplifying circuit 202 is connected with the input end of the signal driving circuit 3;
the modulation branch comprises: a follower circuit 203 and a signal modulation circuit 204; the input end of the following circuit 203 is connected with the emitting piezoelectric crystal 5, and the output end is connected with the signal modulation circuit 204;
the amplifier 201 and the amplifying circuit 202 can form a driving signal according to the signal of the transmitting piezoelectric crystal 5; the signal modulation circuit 204 can modulate the signal of the receiving piezoelectric crystal 6, which is followed by the following circuit 203, into a direct current voltage, and control the amplitude of the driving signal according to the direct current voltage.
It should be noted that the amplifier 201 performs differential amplification on the signal, the amplifying circuit 202 can further amplify the signal amplified by the amplifier 201, so that the signal amplitude can meet the requirement, and the amplified signal is modulated by the signal modulating circuit 204 to realize automatic adjustment of the signal amplitude and is finally sent to the signal driving circuit 3.
It should be noted that the amplifier 201 is mainly used for receiving signals and performing high-gain low-noise processing on the signals.
The signal modulation circuit 204 may modulate the signal amplified by the amplification circuit 202 into a dc voltage signal based on the magnitude of the signal, and perform automatic amplitude adjustment on the received signal based on the amplitude of the modulated signal, so as to stabilize the amplitude of the driving signal through the adjustment of the signal amplitude.
Further, the vibration frequencies of the tuning fork body, the transmitting piezoelectric crystal 5 and the receiving piezoelectric crystal 6 are consistent to improve the action effect.
Specifically, the vibration frequency of the tuning fork body, the transmitting piezoelectric crystal 5, and the receiving piezoelectric crystal 6 is 900 hz.
It should be noted that, in the present application, the vibration frequencies of the tuning fork, the transmitting piezoelectric crystal 5 and the receiving piezoelectric crystal 6 may all be 900hz, but are not limited to 900 hz.
Further, the tuning fork body is circular fork body structure, and inside is equipped with the fixed bolt post, piezoceramics crystal passes through the fixed bolt post install in the tuning fork body.
It should be noted that the material of the tuning fork body may be stainless steel, but is not limited to stainless steel.
The piezoelectric ceramic crystal is arranged on the tuning fork body through the fixing bolt column, and the connection strength of the piezoelectric ceramic crystal and the tuning fork body can be ensured.
Further, the transmitting piezoelectric crystal 5 and/or the receiving piezoelectric crystal 6 are piezoelectric ceramic crystals.
Specifically, the piezoelectric ceramic crystal is a high-temperature type crystal.
The piezoelectric ceramic crystal is a high-temperature type crystal, can resist a high temperature of more than 200 ℃, and ensures that a piezoelectric ceramic crystal signal is stable in a high-temperature environment.
Further, the number of the piezoelectric ceramic crystals is multiple and parallel.
In addition, the plurality of piezoelectric ceramic crystals adopt a parallel structure, so that the transmitting piezoelectric crystal 5 and the tuning fork form resonance, and a natural oscillation frequency can be generated.
Further, the amplifier 201 comprises an AD 620.
It should be noted that the AD620 belongs to a high-gain low-noise amplifier, and is suitable for small-signal amplification.
Referring to fig. 3, the specific circuit diagram of the amplifier 201 mainly includes an AD620, and the AD620 may perform a signal amplification function.
Preferably, referring to fig. 4, the follower circuit 203 includes: resistor R28 and circuit sample AD822 AR.
It should be noted that the circuit sample AD822AR acts as an amplifier, has a high input impedance and a low output impedance, and mainly acts as an input buffer stage and an output buffer stage of the circuit.
Specifically, referring to fig. 5, the signal driving circuit 3 includes: EL2001 signal driver 205, capacitor C1, capacitor C2A, capacitor C2B, capacitor C3, resistor R3, and resistor R4;
a feedback terminal of the EL2001 signal driver 205 and one terminal of the resistor R3 are connected to one terminal of the capacitor C3;
one end of the capacitor C1 is connected to the input end of the amplifying branch, and the other end is connected to the other end of the resistor R3, one end of the resistor R4 and the input end of the EL2001 signal driver 205;
the other end of the resistor R4 is connected to the ground terminal of the EL2001 signal driver 205 and grounded;
the output terminal of the EL2001 signal driver 205 is connected to the first terminal of the capacitor C2A and the first terminal of the capacitor C2B, respectively;
the second terminal of the capacitor C2A and the second terminal of the capacitor C2B are connected to the emitting piezoelectric crystal 5.
It should be noted that the resistor R3 and the resistor R4 are clamp signal levels, the capacitor C3 is a power filter, the EL2001 signal driver is a driver, and is configured to discharge a signal, and the amplified signal is sent to the transmitting piezoelectric crystal 5 through the capacitor C2A and the capacitor C2B, so as to provide transmitting energy to the transmitting piezoelectric crystal 5, so that the tuning fork vibrating body 1 is in a vibrating state.
To facilitate understanding of the above solution, the present solution is further described with reference to fig. 1 to 5.
A tuning fork self-oscillating sensor system comprising: the tuning fork vibrating body, the self-excited oscillation circuit, the signal driving circuit and the signal detection circuit are formed. The tuning fork vibrating body forms a natural vibration frequency which is related to the shape and the material of the fork body; the self-excited oscillation circuit and the tuning fork vibrating body are resonance elements, have a self-excited oscillation function and an automatic gain function, are adjusted through monitoring signals corresponding to the vibration frequencies of the self-excited oscillation circuit and the tuning fork vibrating body, generate driving signals, and provide the driving signals for the tuning fork vibrating body, so that the tuning fork vibrating body achieves the purposes of constant vibration amplitude and automatic tracking and adjustment of the vibration frequency along with the change of fluid.
The self-oscillation circuit 2 has an automatic gain control function and functions as a self-oscillation circuit using a tuning fork vibrating body as a resonance element. The self-oscillation circuit 2 is composed of a signal following circuit 203, a signal modulation circuit 204 and a feedback signal amplifying circuit. The signal following circuit 203 collects oscillation signals of the tuning fork vibrating body, amplitude of the feedback signals is modulated and controlled through the signal modulation circuit 204, amplitude of the oscillation signals is stabilized, automatic gain control is completed, and the influence of high temperature and high pressure is avoided.
On the other hand, an automatic gain adjustment circuit is provided at the subsequent stage of the feedback signal amplification circuit, the signal demodulation circuit 204 modulates the signal of the amplification circuit into a direct current voltage signal based on the magnitude of the tuning fork emitting piezoelectric crystal 5 signal, the signal demodulation circuit 204 performs automatic amplitude adjustment on the signal of the receiving piezoelectric crystal probe 6 based on the amplitude of the modulated signal, and the amplitude of the drive signal is stabilized by the adjustment of the signal amplitude.
The self-oscillation circuit further comprises a signal following circuit 203 and a feedback signal amplifying circuit, wherein one end of the signal following circuit 203 is connected with the transmitting piezoelectric crystal 5 of the tuning fork vibrating body 1, and the other end of the signal following circuit is connected with the signal modulation circuit 204. One end of the amplifier 201 is connected to the receiving piezoelectric crystal 6, and the amplified signal is modulated by the signal modulation circuit 204 and transmitted to the signal driving circuit 3. The self-excited oscillation circuit 2 is added to the tuning fork vibrating body 1 through the signal driving circuit 3 after signal adjustment to form a resonance signal.
The resonance frequency generated by the self-oscillation circuit 2 is changed by the density change of the fluid in the well, and the resonance frequency and the density of the fluid generate a linear change relation.
The tuning fork vibrating body adopts a circular fork structure, and a fixed bolt column is arranged inside the tuning fork vibrating body and used for mounting the piezoelectric ceramic crystal. The fork body is made of stainless steel materials, and the fork body and the body are of an integrated structure, so that the sealing performance of the fork body and the connection strength of the fork body and the piezoelectric ceramic crystal are guaranteed.
The vibration frequency of the piezoelectric ceramic crystal is consistent with the natural frequency of the fork body and is about 900HZ, the piezoelectric ceramic crystal adopts a high-temperature type crystal, the temperature resistance is over 200 ℃, and the signal stability of the piezoelectric ceramic crystal is ensured in a high-temperature environment.
The piezoelectric ceramic crystal adopts a multi-group parallel structure and is fixedly connected with the tuning fork body-checking body through the fixing frame, so that the transmitting piezoelectric ceramic crystal and the tuning fork body-checking body form resonance to generate inherent oscillation frequency.
The working principle is as follows:
the signal of the tuning fork vibrating body 1, which receives the piezoelectric crystal 6, is amplified by an amplifier to form a driving signal of an oscillating circuit; the signal of the emitting piezoelectric crystal 5 is followed by the following circuit 203 and then sent to the signal modulation circuit 204, the emitting piezoelectric crystal 5 is modulated into direct current voltage, and the direct current voltage signal controls the amplitude of the signal driving circuit 3, so that the driving closed loop system vibrates stably. When the density of the fluid flowing through the tuning fork vibrating body 1 changes, the resonant frequency of the tuning fork vibrating body 1 also changes, the changed resonant signal is amplified by the amplifying circuit, the tuning fork body is driven to emit the piezoelectric crystal 5, a self-excited oscillation circuit is formed, and the frequency change of the tuning fork vibrating body 1 is detected through the signal detection circuit 4 due to the fact that the frequency change of the tuning fork vibrating body 1 has a linear relation with the density of the fluid, so that the density of the fluid can be accurately calculated.
The tuning fork type self-oscillation sensor system has the function of automatically tracking the frequency, the frequency of a driving signal and the frequency of a tuning fork resonant body are the same frequency and constantly change along with the difference of fluid density, the tracking adjustment is always kept, the purpose of tuning fork type self-oscillation is realized, the detected fluid density is not easily influenced by the variation of environments such as individual deviation of tuning fork body checking, materials, ambient temperature and pressure, and the like, and the production logging instrument field in the oil and gas exploration field is met.
The tuning fork self-oscillating sensor system shown in fig. 1 comprises: a tuning fork vibrating body 1; a self-oscillation circuit 2; a signal driving circuit 3 and a signal detection circuit 4. Wherein, a transmitting piezoelectric crystal 5 and a receiving piezoelectric crystal 6 are fixed inside the tuning fork vibrating body. The transmitting piezoelectric crystal 5 receives a driving signal of the driving circuit 3, and an oscillation signal generated by the receiving piezoelectric crystal 6 is sent to the self-oscillation circuit 2 to provide an oscillation source for the self-oscillation circuit 2.
As shown in fig. 2, the self-oscillation circuit 2 is composed of four parts, namely an amplifier 201, an amplifying circuit 202, a follower circuit 203 and a signal modulation circuit 204, the amplifier 201 adopts an instrumentation amplifier AD620, which is used for differential amplification of a primary original signal of a receiving crystal, the amplifying circuit 202 amplifies the signal of the amplifier 201 again to meet the requirement of signal amplitude, meanwhile, automatic adjustment of signal amplitude is realized under the control of the signal modulation circuit 204, the signal of the amplifier 202 is increased through the signal modulation circuit 204 when the signal amplitude of a transmitting probe becomes low, so as to achieve the purpose of automatic adjustment of signal amplitude, the modulated signal is sent to the signal driving circuit 3, and F1 and F2 in fig. 2 represent the input and output of the signal respectively and correspond to F1 and F2 in fig. 1.
As shown in fig. 3, the circuit diagram of the amplifying circuit 202 is mainly used for receiving the signal of the piezoelectric ceramic crystal 6 in fig. 1, and an instrumentation amplifier AD620 is used, which has high gain and low noise and is suitable for small signal amplification. The capacitor C8 and the capacitor C10 play a role in separating values, the resistor R9 adjusts the gain of the signal, the signal amplitude of the signal amplifying circuit 3 is determined by the signal size of the signal amplifying circuit, meanwhile, the signal is adjusted by carrying out scale comparison in air and water, and the signal gain is adjusted to enable the signal amplitude in the air and the water to be about 5V, so that the next-stage signal modulation requirement is met.
As shown in fig. 4, the circuit diagram of the signal follower circuit 203, the signal follower circuit 203 mainly functions to improve the matching capability of the signal front and rear stages, and the circuit sample AD822AR functions as an amplifier having a high input impedance and a low output impedance, and also functions as an impedance conversion and matching circuit, thereby functioning as an input buffer stage and an output buffer stage of the circuit.
As shown in fig. 5, the resistor R3 and the resistor R4 of the signal driving circuit 3 are at a clamp signal level, the capacitor C3 is at a power filter, the driver adopts the EL2001 signal driver 205 to amplify the signal of the control circuit, and the amplified signal is sent to the emitting piezoelectric crystal 5 through the capacitor C2A and the capacitor C2B to provide the emitting piezoelectric crystal 5 with emitting energy, so that the emitting piezoelectric crystal 5 is in a vibration state.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments are substantially similar to the method embodiments and therefore are described in a relatively simple manner, and reference may be made to some of the descriptions of the method embodiments for related points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A tuning fork self-oscillating sensor system adapted for fluid density sensing, comprising: the tuning fork vibrating body (1), the self-excited oscillation circuit (2), the signal driving circuit (3) and the signal detection circuit (4);
the tuning fork vibrating body (1) comprises a tuning fork body, a transmitting piezoelectric crystal (5) and a receiving piezoelectric crystal (6);
the self-oscillation circuit (2) includes: an amplifying branch and a modulating branch; the modulation branch is connected with the transmitting piezoelectric crystal (5); the input end of the amplification branch is connected with the receiving piezoelectric crystal (6), the output end of the amplification branch is connected with the input end of the signal driving circuit (3), and the output end of the signal driving circuit (3) is connected with the transmitting piezoelectric crystal (5);
the amplifying branch can form a driving signal according to the signal of the transmitting piezoelectric crystal (5); the modulation branch circuit can modulate the signal of the receiving piezoelectric crystal (6) into direct current voltage and control the amplitude of the driving signal according to the direct current voltage; the signal driving circuit (3) can drive the emitting piezoelectric crystal (5) according to the driving signal with controlled amplitude;
and the input end of the signal detection circuit (4) is connected with the tuning fork body.
2. The tuning fork self-oscillating sensor system according to claim 1, wherein the amplifying branch comprises: an amplifier (201) and an amplification circuit (202); the input end of the amplifier (201) is connected with the receiving piezoelectric crystal (6), and the output end of the amplifier is connected with the input end of the amplifying circuit (202); the output end of the amplifying circuit (202) is connected with the input end of the signal driving circuit (3);
the modulation branch comprises: a follower circuit (203) and a signal modulation circuit (204); the input end of the following circuit (203) is connected with the emitting piezoelectric crystal (5), and the output end of the following circuit is connected with the signal modulation circuit (204);
the amplifier (201) and the amplifying circuit (202) are capable of forming a drive signal from the signal of the emitting piezoelectric crystal (5); the signal modulation circuit (204) can modulate the signal of the receiving piezoelectric crystal (6) followed by the following circuit (203) into direct current voltage, and control the amplitude of the driving signal according to the direct current voltage.
3. A tuning fork self-oscillating sensor system according to claim 1, wherein the tuning fork tines, the transmitting piezoelectric crystal (5) and the receiving piezoelectric crystal (6) have a uniform vibration frequency.
4. A tuning fork self-oscillating sensor system according to claim 3, wherein the tuning fork body, the transmitting piezoelectric crystal (5) and the receiving piezoelectric crystal (6) have a vibration frequency of 900 hz.
5. The tuning fork self-oscillating sensor system of claim 1,
the tuning fork body is circular fork body structure, and inside is equipped with the fixed bolt post, piezoceramics crystal passes through the fixed bolt post install in the tuning fork body.
6. A tuning fork self-oscillating sensor system according to claim 1, wherein the transmitting piezoelectric crystal (5) and/or the receiving piezoelectric crystal (6) are piezoceramic crystals.
7. The tuning fork self-oscillating sensor system of claim 6, wherein the piezoceramic crystal is a high temperature type crystal.
8. The tuning fork self-oscillating sensor system according to claim 6, wherein the piezoelectric ceramic crystals are plural in number and connected in parallel.
9. A tuning fork self-oscillating sensor system according to claim 2, wherein the amplifier (201) comprises an AD 620.
10. A tuning fork self-oscillating sensor system according to claim 1, wherein the signal driving circuit (3) comprises: an EL2001 signal driver (205), a capacitor C1, a capacitor C2A, a capacitor C2B, a capacitor C3, a resistor R3 and a resistor R4;
a feedback end of the EL2001 signal driver (205) and one end of the resistor R3 are connected with one end of the capacitor C3;
one end of the capacitor C1 is connected with the input end of the amplifying branch circuit, and the other end of the capacitor C1 is connected with the other end of the resistor R3, one end of the resistor R4 and the input end of the EL2001 signal driver (205);
the other end of the resistor R4 is connected with the grounding end of the EL2001 signal driver (205) and is grounded;
an output terminal of the EL2001 signal driver (205) is connected to a first terminal of the capacitor C2A and a first terminal of the capacitor C2B, respectively;
the second end of the capacitor C2A and the second end of the capacitor C2B are connected to the emitting piezoelectric crystal (5).
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| CN202010927555.6A CN114152541A (en) | 2020-09-07 | 2020-09-07 | Tuning fork type self-oscillation sensor system |
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