CN107870020B - Three coaxial cable capacitance type water level measuring device - Google Patents
Three coaxial cable capacitance type water level measuring device Download PDFInfo
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- CN107870020B CN107870020B CN201711429070.9A CN201711429070A CN107870020B CN 107870020 B CN107870020 B CN 107870020B CN 201711429070 A CN201711429070 A CN 201711429070A CN 107870020 B CN107870020 B CN 107870020B
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- water level
- level measuring
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- measuring device
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
- G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
- G01F23/266—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors measuring circuits therefor
Abstract
The invention discloses a three-coaxial cable capacitance type water level measuring device, belongs to the technical field of water level measuring equipment, and particularly relates to a capacitance type water level measuring device which adopts three coaxial cables as sensitive elements and adopts a double-circuit C/V conversion chip to carry out capacitance acquisition and processing; the whole set of device consists of a mechanical structure part and a circuit part, wherein the mechanical structure part comprises a sensing probe, a triaxial cable and an aviation connector; the circuit part comprises a power supply, a data acquisition processing circuit and a peripheral circuit; the three-coaxial cable capacitance type water level measuring device has the characteristics of reasonable structural design, small power consumption of the whole device, strong anti-interference capability, good dynamic response, high sensitivity, small nonlinear error, wide measuring range and good stability, and is suitable for long-term use in water, oil and liquid with a large amount of suspended matters.
Description
Technical Field
The invention discloses a three-coaxial cable capacitance type water level measuring device, and belongs to the technical field of water level measuring equipment.
Background
The water level measurement is widely applied to the national production and living fields of chemical industry, petroleum storage, water conservancy, coal mine and the like, and plays an important role.
With the development of science and technology, people put higher demands on water level measuring devices. At present, the technologies adopted in the aspect of measuring water level at home and abroad mainly comprise: float, ultrasonic, capacitive, pressure, inductive, and the like. The float type water level sensor depends on the buoyancy of water, the float is in direct contact with the water surface and goes up and down along with the rise and fall of the water level, the measurement is reliable, the structure is simple, the float type water level sensor is the most common water level sensor, but the float type water level sensor cannot work normally when being frozen in winter, and the measurement error is large when flowing water or strong wind exists; the ultrasonic water level sensor measures the water level according to the acoustic principle, belongs to non-contact measurement, has reliable performance and high precision, but has the characteristics of large influence of factors such as humidity, air pressure and the like on the performance and high price; the pressure type water level sensor acquires a water level signal by utilizing the fact that the pressure of water is in direct proportion to the depth of the water, has high sensitivity and good dynamic response, is easy to integrate, and is easy to cause measurement error due to the fact that a pressure hole is easy to block when sludge or water quality is poor; two coaxial cable capacitive sensor of tradition utilize the electric conductivity of water, constitute a condenser utmost point to water, convert the water level change to the capacitance variation, simple structure, the resolving power is strong, and is not fragile, can work in adverse circumstances, nevertheless easily receives external disturbance, and measuring range is little, and stability is relatively poor.
Disclosure of Invention
The invention discloses a three-coaxial-cable capacitance type water level measuring device, and aims to solve the problems that a traditional two-coaxial-cable capacitance type water level measuring device is easily interfered by the outside, the measuring range is small, and the performance is unstable.
Herein, the C/V conversion means capacitance-voltage conversion, and the AD conversion means analog-digital conversion.
In order to solve the technical problems, the invention adopts the technical scheme that: a three-coaxial cable capacitance type water level measuring device comprises a sensing probe, a three-coaxial cable and a data acquisition and processing circuit, wherein the sensing probe is connected with the data acquisition and processing circuit through the three-coaxial cable; the sensing probe comprises a metal counterweight column, wherein a copper conductor, a foamed polyvinyl chloride insulating layer, an inner copper mesh woven conductor, a low-conductivity material layer, an outer copper mesh woven conductor and a polyvinyl chloride sheath are sequentially arranged on the triaxial cable from inside to outside, the copper conductor is connected with the metal counterweight column, and the copper conductor, the inner copper mesh woven conductor and the outer copper mesh woven conductor are insulated in pairs and are connected with the input end of the data acquisition and processing circuit.
Furthermore, the metal counterweight column is made of stainless steel.
Furthermore, the sensing probe also comprises a hexagon bolt with a through hole in the middle, and the hexagon bolt is connected with the metal counterweight column through threads.
Further, the metal counterweight column is provided with a bottom thread groove, and the copper conductor is fixed into the bottom thread groove by a screw.
Furthermore, the triaxial cable is connected with the data acquisition and processing circuit through an aviation connector, the aviation connector is provided with three terminals, one terminal is connected with the ground wire after being connected with the copper conductor pole lead, and the other two terminals are respectively connected with the outer copper mesh braided conductor pole lead and the inner copper mesh braided conductor pole lead.
Furthermore, the data acquisition and processing circuit comprises a first C/V conversion module, a second C/V conversion module, a differential amplifier, an AD conversion unit and an MCU central processing unit, wherein the input end of the first C/V conversion module is connected with the outer copper mesh braided conductor pole lead, the input end of the second C/V conversion module is connected with the inner copper mesh braided conductor pole lead, the output ends of the first C/V conversion module and the second C/V conversion module are connected with the input end of the differential amplifier, and the output signal of the differential amplifier is connected with the input end of the MCU central processing unit through the AD conversion unit.
The peripheral circuit comprises a frequency output module, an infrared calibration module, a liquid crystal display module and an audible and visual alarm module, the frequency output module is used for converting a water level signal into a frequency signal and transmitting the frequency signal to other equipment, the infrared calibration module is used for eliminating part of system errors of the sensing probe, and the liquid crystal display module is used for displaying the liquid level height.
Furthermore, the power supply, the data acquisition processing circuit and the peripheral circuit are arranged in a metal box for integral shielding, the metal box is provided with a wiring port and a window for embedding a liquid crystal display module, and the aviation connector is arranged at the wiring port. .
Compared with the prior art, the invention has the beneficial effects that: the device reduces the influence of the distributed capacitance of the cable on the water level measurement precision, and has the advantages of strong anti-interference capability, wide measurement range, high measurement precision, small nonlinear error and good sensitivity and stability.
Drawings
The invention is further described below with reference to the accompanying drawings.
FIG. 1 is a schematic structural diagram of the present invention.
In the figure, 1-copper conductor, 2-foamed polyvinyl chloride insulating layer, 3-inner copper mesh braided conductor, 4-low conductivity material layer, 5-outer copper mesh braided conductor, 6-polyvinyl chloride sheath, 7-through hole, 8-hexagon bolt, 9-screw thread, 10-top screw thread groove, 11-metal counterweight column, 12-bottom screw thread groove, 13-sensing probe, 14-power supply, 15-three coaxial cable, 16-aviation connector, 17-copper conductor pole lead, 18-outer copper mesh braided conductor pole lead, 19-inner copper mesh braided conductor pole lead, 20-data acquisition processing circuit, 21-first C/V conversion module, 22-second C/V conversion module, 23-differential amplifier, 24-AD conversion unit, 25-MCU central processing unit, 26-peripheral circuit, 27-frequency output module, 28-infrared calibration module, 29-liquid crystal display module, 30-acousto-optic alarm module.
Detailed Description
As shown in FIG. 1, the present invention relates to a triaxial cable capacitance type water level measuring device, the whole set of device is composed of a mechanical structure and a circuit part. The mechanical structure part comprises a sensing probe 13, a triaxial cable 15 connected with the sensing probe 13 and an aviation connector 16 for connecting the triaxial cable 15 with the circuit part. The three coaxial cables 15 are respectively a copper conductor 1, a foamed polyvinyl chloride insulating layer 2, an inner copper mesh braided conductor 3, a low-conductivity material layer 4, an outer copper mesh braided conductor 5 and a polyvinyl chloride sheath 6 from inside to outside; the sensing probe 13 is formed by connecting a metal counterweight column 11, a hexagon bolt 8 and a triaxial cable 15, wherein the metal counterweight column 11 is of a cylinder structure, the bottom of the cylinder structure is provided with a bottom thread groove 12, the top of the cylinder structure is provided with a top thread groove 10, the hexagon bolt 8 is internally provided with a through hole 7, the outer surface of the hexagon bolt 8 is provided with a thread 9, and the metal counterweight column 11 and the hexagon bolt 8 are both made of stainless steel materials, so that the anti-corrosion capability is strong, and the anti-deformation is realized.
The circuit part consists of a power supply 14, a data acquisition processing circuit 20 and a peripheral circuit 26, wherein the data acquisition processing circuit 20 consists of a first C/V conversion module 21, a second C/V conversion module 22, a differential amplifier 23, an AD conversion unit 24 and an MCU central processing unit 25; the peripheral circuit 26 consists of a frequency output module 27, an infrared calibration module 28, a liquid crystal display module 29 and an acousto-optic alarm module 30; the power supply 14 provides power to the data acquisition processing circuitry 20 and peripheral circuitry 26, respectively. And a three-pole conductor lead led out from the aviation connector 16 is connected with a circuit part, wherein a copper conductor pole lead 17 is connected with a ground wire, an outer copper mesh braided conductor pole lead 18 is connected with the input end of a first C/V conversion module 21, and an inner copper mesh braided conductor pole lead 19 is connected with the input end of a second C/V conversion module 22. In order to prevent the interference of external electromagnetic field and the influence of external object, the circuit part is put into a metal box for integral shielding, the metal box is provided with a wiring port and a window for embedding a liquid crystal display module 29, and the aviation connector 16 is screwed at the wiring port.
During processing, one end of a triaxial cable 15 penetrates through a through hole 7 of a hexagon bolt 8, one end of the triaxial cable 15 is pulled out by a tool in a layered manner, a copper conductor 1 is fixed into a bottom thread groove 12 by a screw, the copper conductor 1 and a metal counterweight column 11 are connected into a whole, exposed parts of the copper conductor 1, an outer copper mesh braided conductor 5 and an inner copper mesh braided conductor 3 of the triaxial cable 15 are respectively wound with insulating tapes to be insulated from each other, in order to prevent a sensing probe 13 from being placed in liquid, the liquid flows into the metal counterweight column 11, a mixed liquid of epoxy resin and a curing agent which are mixed according to a certain proportion is injected into a cylinder of the metal counterweight column 11, the hexagon bolt 8 is combined with a top thread groove 10 of the metal counterweight column 11 into a whole through a thread 9 of the hexagon bolt, and then sealant is filled into the through hole 7 of the hexagon bolt 8 to ensure that a first pole, a second pole and a third pole which are formed by the metal counterweight column 11 and the, One pole formed by the outer copper mesh braided conductor 5 and one pole formed by the inner copper mesh braided conductor 3 are insulated from each other; the other end of the triaxial cable 15 is stripped, and then the copper conductor 1, the inner copper mesh braided conductor 3 and the outer copper mesh braided conductor 5 are separately connected to one end of the aviation connector 16, the exposed parts of the three are insulated from each other, the lead of the tripolar conductor is led out through the other end of the aviation connector 16, namely, a copper conductor pole lead 17 connected with the copper conductor 1, an outer copper mesh braided conductor pole lead 18 connected with the outer copper mesh braided conductor 5, an inner copper mesh braided conductor pole lead 19 connected with the inner copper mesh braided conductor 3, and the three leads are insulated from each other.
The calibration process and the measurement process of the present invention are specifically described below.
1. Calibration procedure
After the water level measuring device is assembled, the sensing probe 13 is vertically placed into the reservoir, and the triaxial cable 15 is straightened. Because the sensing probe 13 is not in linear relation with the capacitance generated by the liquid level and the capacitance generated by the triaxial cable 15, calibration is carried out before measurement to eliminate the influence, the input end of the MCU central processing unit 25 is connected with the infrared calibration module 28 for calibration, the infrared calibration module 28 receives a control signal of an infrared transmitting remote controller outside a metal box, the infrared transmitting remote controller is provided with three keys, namely an entering key K1, an adding key K2 and an exiting key K3, and the height of the sensing probe 13 is 10cm, so the liquid crystal display module 29 displays 10cm when the sensing probe 13 is just completely immersed in water during programming, and displays the water level when the sensing probe is not immersed or is not completely immersed in water. Aiming at the problems of poor precision and poor linearity in the measuring process caused by different water qualities, the measuring range is divided into three sections by adopting a linear interpolation method, when in calibration, the sensing probe 13 is just immersed into water completely, the infrared transmitting remote controller is aligned to a metal box of a triaxial cable capacitance type water level measuring device, a K1 key is pressed down, a liquid crystal display module 29 displays 0000, a K2 key is pressed down, the liquid crystal display module 29 displays 0001, and the device is started to interrupt the acquisition of a starting scale reference value and stores the starting scale reference value to the MCU central processing unit 25; the sensing probe 13 and the triaxial cable 15 are immersed to the middle position of the maximum measurement value, the K2 key is pressed again, the liquid crystal display module 29 displays 0002, and the device is started to interrupt the acquisition of the reference value of the middle scale and stores the reference value in the MCU central processing unit 25; the sensing probe 13 and the triaxial cable 15 are immersed to the position of the maximum measurement value, the K2 key is pressed again, the liquid crystal display module 29 displays 0003, and the device is started to interrupt acquisition of the full scale reference value and stores the full scale reference value in the MCU 25; pressing the key K3 exits the calibration. When the water level measuring device works, when the immersion depth of the sensing probe 13 and the triaxial cable 15 is between the reference value of the initial scale and the reference value of the middle scale, the MCU central processing unit calculates according to the reference values of the initial scale and the middle scale, and when the immersion depth of the sensing probe 13 and the triaxial cable 15 is between the reference value of the middle scale and the reference value of the full scale, the MCU central processing unit calculates according to the reference values of the middle scale and the full scale. The linear interpolation method is adopted to divide the measuring range into three sections for measurement and calibration, so that the linearity is improved, the influence of different water qualities on the measuring precision can be eliminated, and the measuring precision is improved.
2. Measuring process
In a water level measuring site, according to actual conditions on the site, a measurer adjusts a proper height to vertically suspend a metal box of a three-coaxial cable capacitance type water level measuring device on a hook, the three-coaxial cable 15 is straightened, a sensing probe 13 is vertically placed at the bottom of a reservoir, a copper conductor 1 is connected with water through a metal counterweight column 11, an inner copper mesh braided conductor 3 and the water form two poles of a capacitor C1, an outer copper mesh braided conductor 5 and the water form two poles of a capacitor C2, the water forms a common pole of two capacitors C1 and C2, when the water level changes, the area of polar plates of the two capacitors changes, the size of the capacitors changes along with the change of the polar plates and is approximately in linear relation with the depth of the three-coaxial cable 15 immersed in the water, and therefore the current water level value is converted into two paths of capacitance values corresponding. After the power is supplied to a triaxial cable capacitance type water level measuring device, the MCU central processing unit 25 firstly executes program initialization configuration and is in a starting state, the input end of the first C/V conversion module 21 collects the value of a capacitor C1 through an inner copper mesh braided conductor level lead 19, the input end of the second C/V conversion module 22 collects the value of a capacitor C2 through an outer copper mesh braided conductor level lead 18, the first C/V conversion module 21 and the second C/V conversion module 22 convert the two measured capacitors into two different linear voltage outputs and send the two different linear voltage outputs to the input end of the differential amplifier 23, after the signals are subjected to differential processing, the influence of cable distributed capacitance on the measurement accuracy can be reduced, the anti-interference capability, the sensitivity and the stability of the sensor are greatly improved, the measurement range is widened, the voltage signals subjected to differential amplification are converted into digital signals through the AD conversion unit 24 and sent to the MCU central processing unit 25 for processing, the MCU central processing unit 25 obtains the current water level value through relevant calculation and sends the current water level value to the liquid crystal display module 29 for real-time display so as to be convenient for field personnel to observe, and meanwhile, the MCU central processing unit 25 converts the water level information into a frequency signal through the frequency output module 27 and transmits the frequency signal to other equipment so as to realize remote monitoring of the field water situation. When the water level is abnormal, the sound and light alarm module 30 can give out sound and light alarm to remind the field personnel.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Claims (8)
1. The utility model provides a three coaxial cable capacitanc water level measurement device which characterized in that: the device comprises a sensing probe (13), a triaxial cable (15) and a data acquisition and processing circuit (20), wherein the sensing probe (13) is connected with the data acquisition and processing circuit (20) through the triaxial cable (15); sensing probe (13) include metal counter weight post (11), triaxial cable (15) are copper conductor (1), foaming polyvinyl chloride insulating layer (2), conductor (3) are woven to interior copper mesh, low conductivity material layer (4), conductor (5) and polyvinyl chloride sheath (6) are woven to outer copper mesh by interior to outer in proper order, copper conductor (1) links to each other with metal counter weight post (11), copper conductor (1), interior copper mesh weave conductor (3) and outer copper mesh weave conductor (5) two liang of insulation and all link to each other with the input of data acquisition processing circuit (20).
2. The capacitance type water level measuring device with three coaxial cables as claimed in claim 1, wherein the metal counterweight column (11) is made of stainless steel.
3. The capacitance type water level measuring device with the three coaxial cables as claimed in claim 2, wherein the sensing probe (13) further comprises a hexagon bolt (8) with a through hole (7) in the middle, and the hexagon bolt (8) is connected with the metal counterweight column (11) through a thread (9).
4. A triaxial cable capacitive water level measuring device according to claim 3, wherein the metal counterweight column (11) is provided with a bottom threaded groove (12), and the copper conductor (1) is screwed into the bottom threaded groove (12).
5. The capacitance type water level measuring device with the three coaxial cables as claimed in claim 4, wherein the three coaxial cables (15) are connected with the data acquisition and processing circuit (20) through an aviation connector (16), the aviation connector (16) is provided with three terminals, one terminal is connected with a copper conductor pole lead (17) and then is connected with a ground wire, and the other two terminals are respectively connected with an outer copper mesh braided conductor pole lead (18) and an inner copper mesh braided conductor pole lead (19).
6. The triaxial cable capacitive water level measuring device according to claim 5, wherein: the data acquisition and processing circuit (20) comprises a first C/V conversion module (21), a second C/V conversion module (22), a differential amplifier (23), an AD conversion unit (24) and an MCU central processing unit (25), wherein the input end of the first C/V conversion module (21) is connected with the outer copper mesh braided conductor pole lead (18), the input end of the second C/V conversion module (22) is connected with the inner copper mesh braided conductor pole lead (19), the output ends of the first C/V conversion module (21) and the second C/V conversion module (22) are connected with the input end of the differential amplifier (23), and the output signal of the differential amplifier (23) is connected with the input end of the MCU central processing unit (25) through the AD conversion unit (24).
7. The triaxial cable capacitance type water level measuring device according to claim 6, further comprising a peripheral circuit (26) and a power supply (14), wherein the power supply (14) is connected with the data acquisition processing circuit (20) and the power supply input end of the peripheral circuit (26), the peripheral circuit (26) comprises a frequency output module (27), an infrared calibration module (28), a liquid crystal display module (29) and an acousto-optic alarm module (30), the frequency output module (27) is used for converting a water level signal into a frequency signal and transmitting the frequency signal to other equipment, the infrared calibration module (28) is used for eliminating part of system errors of the sensing probe (13), and the liquid crystal display module (29) is used for displaying the liquid level height.
8. The triaxial cable capacitive water level measuring device according to claim 7, wherein: the power supply (14), the data acquisition processing circuit (20) and the peripheral circuit (26) are arranged in a metal box for integral shielding, a wiring port and a window used for embedding a liquid crystal display module (29) are formed in the metal box, and the aviation connector (16) is arranged at the wiring port.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711429070.9A CN107870020B (en) | 2017-12-26 | 2017-12-26 | Three coaxial cable capacitance type water level measuring device |
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| CN201711429070.9A CN107870020B (en) | 2017-12-26 | 2017-12-26 | Three coaxial cable capacitance type water level measuring device |
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| CN107870020A CN107870020A (en) | 2018-04-03 |
| CN107870020B true CN107870020B (en) | 2019-12-17 |
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| CN106768172A (en) * | 2015-11-23 | 2017-05-31 | 北京航天试验技术研究所 | Extremely low relative dielectric constant medium level gauging implementation method |
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| US8590375B2 (en) * | 2011-03-22 | 2013-11-26 | Rochester Gauges, Inc. | Self-calibrating capacitive liquid level sensor assembly and method |
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| CN2542612Y (en) * | 2002-03-29 | 2003-04-02 | 威海海和科技有限责任公司 | Multi-phase level sensor |
| CN202562563U (en) * | 2012-05-10 | 2012-11-28 | 山西晋城无烟煤矿业集团有限责任公司 | Sewage level measurement sensor for mine |
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