CN210036880U - Sectional capacitor liquid level converter and liquid level measurement system under low-temperature medium - Google Patents
Sectional capacitor liquid level converter and liquid level measurement system under low-temperature medium Download PDFInfo
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- CN210036880U CN210036880U CN201822223514.XU CN201822223514U CN210036880U CN 210036880 U CN210036880 U CN 210036880U CN 201822223514 U CN201822223514 U CN 201822223514U CN 210036880 U CN210036880 U CN 210036880U
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Abstract
The utility model discloses a sectional electric capacity liquid level converter and liquid level measurement system under low temperature medium belongs to the relevant technical field of converter, sectional electric capacity liquid level converter under low temperature medium include casing circuit printing board, casing, shield cover, apron, punching electric capacity, connector and sealing washer, still include capacitanc level sensor, casing circuit printing board is provided with signal detection circuit, signal detection circuit includes wen's oscillating circuit, transformer bridge measuring circuit, exchanges two-stage amplifier circuit, AC/DC rectification filter circuit and voltage follower circuit; the utility model discloses mainly use with the supporting use of sectional type electric capacity low temperature level sensor and carry out continuous measurement to low temperature insulation liquid medium like liquid oxygen, liquid hydrogen, liquid methane, kerosene what LNG liquid level, sectional type electric capacity liquid level converter has characteristics such as measurement accuracy height, circuit are simple, response speed is fast, interference immunity is good under this kind of low temperature medium.
Description
Technical Field
The utility model relates to a relevant technical field of converter specifically is a sectional electric capacity liquid level converter and level measurement system under low temperature medium.
Background
In the rocket flying process, accurate measurement of the propellant liquid site is very important for ensuring the reasonable utilization of the propellant in the storage tank. The liquid propellant commonly used in the rocket system at present is liquid oxygen, liquid hydrogen, kerosene and methane, which all belong to insulating media, wherein: liquid hydrogen, liquid oxygen and methane are low-temperature media, and kerosene is a normal-temperature medium. Because the relative dielectric constants of the liquid hydrogen, the liquid oxygen and the methane are relatively small (2.2 kerosene, 1.485 liquid hydrogen, 1.22 methane and 1.675 methane under standard atmospheric pressure), and the working temperatures of the liquid hydrogen, the liquid oxygen and the methane are lower than-150 ℃, the converter cannot work in the propellant box body, and only the sensor signals can be led out to the converter through the connector and the cable. The following aspects can seriously affect the measurement of the sensor capacitance:
1. the length of the signal lead-out cable is long, and the measurement precision of the sensor capacitor is seriously influenced by the distributed capacitance on the signal lead-out cable;
2. because the working environment of the converter is severe, the detected capacitor and the input and output signals are easily influenced by the interference of the external electromagnetic environment, and the measurement precision and the working stability of the circuit are influenced;
3. in a low-temperature medium, the temperature difference is large, the change of the temperature inevitably causes the change of the relative dielectric constant, the change of the measured capacitance is directly caused, the reference capacitance cannot be changed, and the measurement precision is directly reduced.
To sum up, the utility model provides a sectional electric capacity liquid level converter and level measurement system under low temperature medium has measurement accuracy height, the circuit is simple, response speed is fast and interference immunity is good advantage.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a sectional electric capacity liquid level converter and liquid level measurement system under low temperature medium to solve the problem that provides among the above-mentioned background art.
In order to achieve the above object, the utility model provides a following technical scheme:
a segmented capacitor liquid level converter under a low-temperature medium comprises a shell circuit printed board, a shell, a shielding cover, a cover plate, a feedthrough capacitor, a connector and a sealing ring, wherein the shell circuit printed board and the feedthrough capacitor are arranged in the shell, and the feedthrough capacitor is divided into two groups; the shell body circuit printed board comprises a first circuit printed board and a second circuit printed board, the connector comprises an input connector and an output connector, and the sealing ring comprises an output connector sealing ring, an input connector sealing ring and a cover plate sealing ring; the shielding cover is arranged on the outer surface of the shell, and the cover plate covers the outer surface of the shielding cover; the shield mainly functions to shield electromagnetic interference.
As a further aspect of the present invention: the first circuit printed board and the second circuit printed board are arranged between the two sets of the through capacitors, the first circuit printed board is arranged below the second circuit printed board, the input connector is arranged at the left end of the shell through an input connector sealing ring, and the output connector is arranged at the right end of the shell through an output connector sealing ring. The output connector sealing ring and the input connector sealing ring are used for sealing and buffering with the shell.
As a further aspect of the present invention: the sealing ring is made of conductive rubber, and the cover plate sealing ring is arranged between the cover plate and the shielding cover; the input connector, the output connector, the feedthrough capacitor, the first circuit printed board and the second circuit printed board are electrically connected.
As a further aspect of the present invention: and the first circuit printed board and the second circuit printed board are respectively provided with a signal detection circuit, and the signal detection circuit comprises a Venturi oscillation circuit, a transformer bridge measurement circuit, an alternating current two-stage amplification circuit, an AC/DC rectification filter circuit and a voltage following circuit.
As a further aspect of the present invention: the odd-numbered capacitor bank and the even-numbered capacitor bank of the capacitive liquid level sensor are connected to two bridge arms of a transformer bridge of the signal detection circuit through a connector and a coaxial shielding cable; the shielding layer of the coaxial shielding cable is grounded, and on one hand, the balance condition of the transformer bridge circuit is equal to that of the transformer bridge circuitThe distributed capacitance generated by the shaft shielding cable is irrelevant, and the center tap G of the secondary side of the transformer is grounded, so that all the capacitance to ground can be excluded from measurement, and the measurement accuracy is improved; on the other hand, the bridge arms of the transformer bridge introduce different segmented capacitors on the same capacitive liquid level sensor, and the capacitors have the temperature compensation function mutually, so that the influence of temperature on the measurement precision is reduced; H. the L end is the position where the capacitance signal of the capacitance type liquid level sensor is introduced into the measuring circuit and is connected with the distributed capacitance C on the coaxial shielding cable01、C02、C03And C04All become the capacitance to ground, are excluded from the circuit measurement, and ensure the test precision of the circuit.
As a further aspect of the present invention: the Venturi oscillation circuit comprises an operational amplifier, a field effect transistor, a precise capacitor, a resistor, a diode and a triode, wherein the precise capacitor and the resistor form an RC frequency selection part and are used for generating a sine signal with a certain frequency, and the frequency stability of an output signal reaches 0.5%; the field effect tube is a voltage-controlled resistor, the alternating voltage is rectified and stabilized by using a diode, then the amplitude stabilization of the output signal of the Venturi oscillation circuit is realized by the voltage division of the field effect tube and the precision resistor, and the amplitude stabilization performance of the signal reaches 1%; the triode amplifies the power of the signal, and ensures that the driving transformer can work normally.
As a further aspect of the present invention: the transformer bridge measuring circuit comprises a transformer, an odd capacitor bank and an even capacitor bank, when the odd capacitor bank and the even capacitor bank are equal, the bridge is balanced, the output is 0, when one partial capacitor begins to change, the bridge is unbalanced, a voltage output signal exists, and the voltage output signal is in direct proportion to the capacitance change amount; the alternating-current two-stage amplifying circuit comprises two single-circuit operational amplifiers, a precision resistor and a tantalum capacitor, the two single-circuit operational amplifiers and the precision resistor form a same-phase amplifying circuit, and the tantalum capacitor isolates a direct-current signal and ensures that the amplified signal is reliable and stable.
As a further aspect of the present invention: the AC/DC rectification filter circuit comprises an operational amplifier, a diode and a resistor and is used for rectifying the two-stage alternating current amplified signal into a direct current voltage signal and outputting a stable direct current signal after pi filtering; the voltage following circuit comprises an operational amplifier, a limiting diode, a resistor and a capacitor, is used for carrying out impedance transformation on the rectified direct-current voltage signal, has the characteristics of high input impedance and low output impedance, and is output after diode limiting and RC low-pass filtering.
The liquid propellant liquid level measuring system comprises the segmented capacitance liquid level converter under the low-temperature medium.
Compared with the prior art, the beneficial effects of the utility model are that:
the measurement precision is high, the circuit is simple, the response speed is high, and the anti-interference performance is good; the above advantages are also present for other capacitive sensing applications.
The utility model discloses well economize on electricity capacitanc level sensor signal and introduce used cable for coaxial shielded cable, its shielding layer all ground connection, H, L end are sensor capacitance signal and introduce measuring circuit department, the last distributed capacitance C of connecting cable01、C02、C03And C04All become the capacitance to ground, are excluded from the circuit measurement, and ensure the test precision of the circuit.
The utility model discloses different segmental capacitors on the same segmental capacitance type level sensor that the well transformer bridge arm introduced have the temperature compensation effect mutually, have reduced the influence of temperature to measurement accuracy.
The utility model discloses in prevent external electromagnetic interference and taken two aspects measures: and through capacitors are designed between the input connector and the circuit connection and between the output connector and the circuit connection from the electrical connection to filter external electromagnetic waves, so that the stability and reliability of incoming signals and output signals of the converter are ensured. Structurally, the sealing rings among the connector, the cover plate and the shell are made of conductive rubber materials which are magnetic conductive and conductive; in addition, a layer of metal shielding cover is added before the cover plate is sealed, so that electromagnetic interference is well shielded.
Drawings
Fig. 1 is a schematic view of the structural assembly of the present invention.
Fig. 2 is a schematic block diagram of a signal detection circuit in the present invention.
Fig. 3 is a schematic diagram of the elimination of the distributed capacitance in the present invention.
Fig. 4 is a schematic structural diagram of the middle-dividing capacitor type liquid level sensor of the present invention.
Fig. 5 is an output characteristic diagram of the present invention.
In the figure: 1-a first circuit printed board, 2-a second circuit printed board, 3-a housing, 4-a cover plate, 5-a shielding case, 6-a feedthrough capacitor, 7-an output connector sealing ring, 8-an input connector sealing ring, 9-a cover plate sealing ring, 10-an input connector, 11-an output connector, 12-an odd capacitor bank, 13-a common terminal, 14-an even capacitor bank.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Example one
Referring to fig. 1 to 5, in an embodiment of the present invention, a segmented capacitor liquid level converter under a low temperature medium includes a casing circuit printed board, a casing 3, a shielding cover 5, a cover plate 4, a feedthrough capacitor 6, a connector, and a sealing ring, where the casing circuit printed board and the feedthrough capacitor 6 are disposed inside the casing, and there are two sets of feedthrough capacitors 6; the liquid level sensor further comprises a capacitance type liquid level sensor, the shell circuit printed board comprises a first circuit printed board 1 and a second circuit printed board 2, the connector comprises an input connector 10 and an output connector 11, and the sealing rings comprise an output connector sealing ring 7, an input connector sealing ring 8 and a cover plate sealing ring 9; the shielding case 5 is arranged on the outer surface of the shell 3, and the cover plate 4 covers the outer surface of the shielding case 5; the shield 5 mainly functions to shield electromagnetic interference.
In the embodiment of the utility model provides an in, first circuit printing board 1 and second circuit printing board 2 set up between two sets of punching electric capacity 6, and first circuit printing board 1 sets up in second circuit printing board 2 below, input connector 10 sets up the left end at casing 3 through input connector sealing washer 8, output connector 11 sets up the right-hand member at casing 3 through output connector sealing washer 7. The output connector seal ring 7 and the input connector seal ring 8 function to provide a sealing cushion with the housing 3.
In the embodiment of the present invention, the sealing ring is made of conductive rubber, and the cover sealing ring 9 is disposed between the cover plate 4 and the shielding case 5; the input connector 10, the output connector 11, the feedthrough capacitor 6, the first circuit printed board 1 and the second circuit printed board 2 are electrically connected.
In the embodiment of the utility model provides an in, all be provided with signal detection circuit on first circuit printing board 1 and the second circuit printing board 2, signal detection circuit includes venturi oscillation circuit, transformer bridge measuring circuit, exchanges two-stage amplification circuit, AC/DC rectification filter circuit and voltage follower circuit.
In the embodiment of the present invention, the odd number capacitor bank 12 and the even number capacitor bank 14 of the capacitive liquid level sensor are connected to two bridge arms of a transformer bridge of the signal detection circuit through a connector and a coaxial shielding cable; the shielding layer of the coaxial shielding cable is grounded, on one hand, the balance condition of the transformer bridge circuit is irrelevant to the distributed capacitance generated by the coaxial shielding cable, and the center tap G of the secondary side of the transformer is grounded, so that all the capacitance to ground can be excluded from measurement, and the measurement accuracy is improved; on the other hand, the bridge arms of the transformer bridge introduce different segmented capacitors on the same capacitive liquid level sensor, and the capacitors have the temperature compensation function mutually, so that the influence of temperature on the measurement precision is reduced; H. the L end is the position where the capacitance signal of the capacitance type liquid level sensor is introduced into the measuring circuit and is connected with the distributed capacitance C on the coaxial shielding cable01、C02、C03And C04All become the capacitance to ground, are excluded from the circuit measurement, and ensure the test precision of the circuit.
In the embodiment of the utility model, venturi oscillation circuit includes operational amplifier, field effect transistor, accurate electric capacity, resistance, diode and triode, accurate electric capacity and resistance constitute RC frequency-selecting part for produce the sinusoidal signal of certain frequency, output signal's frequency stability reaches 0.5%; the field effect tube is a voltage-controlled resistor, the alternating voltage is rectified and stabilized by using a diode, then the amplitude stabilization of the output signal of the Venturi oscillation circuit is realized by the voltage division of the field effect tube and the precision resistor, and the amplitude stabilization performance of the signal reaches 1%; the triode amplifies the power of the signal, and ensures that the driving transformer can work normally.
In the embodiment of the present invention, the transformer bridge measuring circuit includes a transformer, an odd number capacitor bank 12 and an even number capacitor bank 14, when the odd number capacitor bank 12 is equal to the even number capacitor bank 14, the bridge is balanced, the output is 0, when one of the dividing capacitors begins to change, the bridge is unbalanced, there is a voltage output signal, and the voltage output signal is proportional to the capacitance change amount; the alternating-current two-stage amplifying circuit comprises two single-circuit operational amplifiers, a precision resistor and a tantalum capacitor, the two single-circuit operational amplifiers and the precision resistor form a same-phase amplifying circuit, and the tantalum capacitor isolates a direct-current signal and ensures that the amplified signal is reliable and stable.
In the embodiment of the present invention, the AC/DC rectifying and filtering circuit includes an operational amplifier, a diode and a resistor, and is configured to rectify a two-stage AC amplified signal into a DC voltage signal, and output a stable DC signal after pi filtering; the voltage following circuit comprises an operational amplifier, a limiting diode, a resistor and a capacitor, is used for carrying out impedance transformation on the rectified direct-current voltage signal, has the characteristics of high input impedance and low output impedance, and is output after diode limiting and RC low-pass filtering.
Example two
The embodiment of the utility model provides an in, provide a liquid propellant liquid level measurement system including sectional electric capacity liquid level converter under the low temperature medium, the low temperature medium under sectional electric capacity liquid level converter's structure and embodiment one the structure the same.
It is obvious to a person skilled in the art that the invention is not restricted to details of the above-described exemplary embodiments, but that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (9)
1. A segmented capacitor liquid level converter under a low-temperature medium comprises a shell circuit printed board, a shell (3), a shielding cover (5), a cover plate (4), a feedthrough capacitor (6), a connector and a sealing ring, wherein the shell circuit printed board and the feedthrough capacitor (6) are arranged inside the shell, and the feedthrough capacitor (6) is divided into two groups; the liquid level sensor is characterized by further comprising a capacitive liquid level sensor, the shell circuit printed board comprises a first circuit printed board (1) and a second circuit printed board (2), the connector comprises an input connector (10) and an output connector (11), and the sealing rings comprise an output connector sealing ring (7), an input connector sealing ring (8) and a cover plate sealing ring (9); the shielding case (5) is arranged on the outer surface of the shell (3), and the cover plate (4) covers the outer surface of the shielding case (5).
2. The segmented capacitor liquid level converter under low-temperature medium according to claim 1, wherein the first circuit printed board (1) and the second circuit printed board (2) are arranged between two sets of through capacitors (6), the first circuit printed board (1) is arranged below the second circuit printed board (2), the input connector (10) is arranged at the left end of the shell (3) through an input connector sealing ring (8), and the output connector (11) is arranged at the right end of the shell (3) through an output connector sealing ring (7).
3. The segmented capacitance liquid level converter under the low-temperature medium according to claim 2, wherein the material of the sealing ring is conductive rubber, and the cover sealing ring (9) is arranged between the cover plate (4) and the shielding cover (5); the input connector (10), the output connector (11), the feedthrough capacitor (6), the first circuit printed board (1) and the second circuit printed board (2) are electrically connected.
4. The sectional capacitor liquid level converter under the low-temperature medium according to claim 3, wherein the first circuit printed board (1) and the second circuit printed board (2) are respectively provided with a signal detection circuit, and the signal detection circuit comprises a Venturi oscillation circuit, a transformer bridge measuring circuit, an alternating current two-stage amplifying circuit, an AC/DC rectifying and filtering circuit and a voltage following circuit.
5. The sectional capacitance liquid level converter under the low-temperature medium according to claim 1, wherein the odd number capacitor bank (12) and the even number capacitor bank (14) of the capacitance liquid level sensor are connected to two bridge arms of a transformer bridge of a signal detection circuit through a connector and a coaxial shielded cable; the shielding layer of the coaxial shielding cable is grounded.
6. The sectional capacitor liquid level converter under the low-temperature medium according to claim 4, wherein the Venturi oscillation circuit comprises an operational amplifier, a field effect transistor, a precision capacitor, a resistor, a diode and a triode, and the precision capacitor and the resistor form an RC frequency-selecting part; the field effect transistor is a voltage-controlled resistor.
7. The sectional capacitor liquid level converter under the low-temperature medium according to claim 4, wherein the transformer bridge measuring circuit comprises a transformer, an odd capacitor bank (12) and an even capacitor bank (14), the alternating current two-stage amplifying circuit comprises two one-way operational amplifiers, a precision resistor and a tantalum capacitor, the two one-way operational amplifiers and the precision resistor form an in-phase amplifying circuit, and the tantalum capacitor isolates a direct current signal.
8. The sectional capacitor liquid level converter under low temperature medium of claim 4, wherein the AC/DC rectifying and filtering circuit comprises an operational amplifier, a diode and a resistor, and the voltage following circuit comprises an operational amplifier, a limiting diode, a resistor and a capacitor.
9. A liquid propellant level measurement system comprising the low temperature medium segmented capacitance level transducer of any one of claims 1 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201822223514.XU CN210036880U (en) | 2018-12-27 | 2018-12-27 | Sectional capacitor liquid level converter and liquid level measurement system under low-temperature medium |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201822223514.XU CN210036880U (en) | 2018-12-27 | 2018-12-27 | Sectional capacitor liquid level converter and liquid level measurement system under low-temperature medium |
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| CN210036880U true CN210036880U (en) | 2020-02-07 |
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| CN201822223514.XU Active CN210036880U (en) | 2018-12-27 | 2018-12-27 | Sectional capacitor liquid level converter and liquid level measurement system under low-temperature medium |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115683275A (en) * | 2022-11-02 | 2023-02-03 | 河源市嘉辰科技有限公司 | Cross-buckling interdigital electrode structure, capacitive water level sensor and precise water level detection device |
-
2018
- 2018-12-27 CN CN201822223514.XU patent/CN210036880U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115683275A (en) * | 2022-11-02 | 2023-02-03 | 河源市嘉辰科技有限公司 | Cross-buckling interdigital electrode structure, capacitive water level sensor and precise water level detection device |
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Address after: 100000 building 7, courtyard 29, Kechuang 7th Street, Beijing Economic and Technological Development Zone, Daxing District, Beijing Patentee after: Beijing Jinmaijie Technology Co.,Ltd. Address before: 8th Floor, Building 7, Yard 29, Jinghai 2nd Road, Beijing Economic and Technological Development Zone, Daxing District, Beijing 100000 Patentee before: BEIJING JINMAIJIE TECHNOLOGY Co.,Ltd. |