CN112050898B - Capacitance type oil level gauge - Google Patents
Capacitance type oil level gauge Download PDFInfo
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- CN112050898B CN112050898B CN201910488238.6A CN201910488238A CN112050898B CN 112050898 B CN112050898 B CN 112050898B CN 201910488238 A CN201910488238 A CN 201910488238A CN 112050898 B CN112050898 B CN 112050898B
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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
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Electromagnetism (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
Abstract
The invention discloses a capacitance type oil level gauge, which comprises a gauge outfit, a process connecting piece and a capacitance sensor, wherein the capacitance sensor is fixed with the gauge outfit through the process connecting piece, the gauge outfit comprises a shell and a measurement and control module which is internally arranged in the shell, the measurement and control module comprises a capacitance digital conversion chip, the capacitance sensor comprises a measuring cylinder and two measuring rods which are internally arranged in the measuring cylinder, the relative positions of the measuring rods and the measuring cylinder are fixed, the measuring cylinder and the two measuring rods form two paths of measuring capacitors respectively, the two paths of measuring capacitors are respectively connected with different measuring foot tubes of the capacitance digital conversion chip, the bottom end of the side wall of the measuring cylinder is provided with a liquid inlet, and the top end of the side wall of the measuring cylinder is provided with an exhaust hole.
Description
Technical Field
The invention relates to the technical field of liquid level measurement, in particular to a capacitive oil level gauge.
Background
The capacitive oil level gauge in the current market generally comprises a gauge head and a capacitive sensor fixed with the gauge head, wherein a measurement and control module is arranged in the gauge head and generally comprises a power supply, a measurement circuit, an MCU, a signal output circuit and the like. The power supply provides electric energy for the whole machine, and the measuring circuit is connected with the measuring electrode through signals. The signal generating part in the measuring circuit generates a capacitance measurement excitation signal, and converts the capacitance change into a level signal which can be recognized by the MCU through different electronic devices such as bridge measurement, sample hold, signal filtering and the like in the measuring circuit. The MCU monitors the change of the level signal, converts the capacitance value into a liquid level height value of oil through calculation, and the signal output circuit converts the liquid level height value into a standard communication signal and outputs the standard communication signal to the upper computer.
The functional control of the prior art products requires the provision of a measurement circuit and a separate MCU, and the measurement circuit is composed of discrete devices, resulting in products having limitations that are difficult to overcome: on one hand, the complicated circuit structure causes the hardware interstage matching design difficulty to be high, the software design is complicated, on the other hand, the device performance is easily influenced by the external environment, the anti-interference capability of the measuring circuit is poor, and the measuring precision is not beneficial to improvement.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide the capacitance oil level gauge, wherein the measurement and control module adopts the integrally packaged capacitance digital conversion chip, so that discrete devices of a traditional measurement circuit are omitted, the circuit structure is greatly simplified, the anti-interference capability is improved, the design difficulty of hardware and software is reduced, and the measurement accuracy of products is improved.
The invention adopts the following technical scheme:
the utility model provides a capacitive oil level gauge, includes gauge outfit, process connection spare and capacitive sensor, capacitive sensor passes through the process connection spare with the gauge outfit is fixed, the gauge outfit includes the shell and the built-in measurement and control module of shell, measurement and control module includes electric capacity digital conversion chip, capacitive sensor includes the measuring cylinder and embeds two measuring sticks of measuring cylinder, just the measuring stick with the relative position of measuring cylinder is fixed, the measuring cylinder constitutes two way measurement capacitance with two measuring sticks respectively, two way measurement capacitance connect respectively in the different measurement foot pipes of electric capacity digital conversion chip, the bottom of measuring cylinder lateral wall is provided with the feed liquor hole, the top of measuring cylinder lateral wall is provided with the exhaust hole.
Further, the measurement capacitor is connected with a measurement pin of the capacitance-to-digital conversion chip through a cable.
Further, the measuring cylinder is cylindrical, and the measuring rod comprises a cylindrical metal inner core and an insulating layer sleeved outside the metal inner core.
Further, the measurement and control module further comprises a power supply circuit, a temperature sensor, a signal output circuit, a key input circuit and a display output circuit, wherein the power supply circuit is respectively connected with the capacitance digital conversion chip, the signal output circuit, the key input circuit and the display output circuit, and the capacitance digital conversion chip is respectively connected with the temperature sensor, the signal output circuit, the key input circuit and the display output circuit.
Further, the shell is provided with a key module and a display module which are respectively connected with the key input circuit and the display output circuit.
Further, the capacitance-to-digital conversion chip is a chip PCap02 or a chip PCap04.
Compared with the prior art, the invention has the beneficial effects that:
according to the capacitive oil level gauge, on one hand, the measurement and control module adopts the integrally packaged capacitance-digital conversion chip element, so that discrete devices of a traditional measurement circuit are omitted, the circuit structure is greatly simplified, the anti-interference capability can be improved, the design difficulty of hardware and software is reduced, and the measurement accuracy of a product is improved;
on the other hand, the capacitive sensor comprises a measuring cylinder and two measuring rods arranged in the measuring cylinder, the measuring cylinder and the two measuring rods form two paths of measuring capacitors, the two paths of measuring capacitors are respectively connected with different foot tubes of the capacitance digital conversion chip, liquid level measurement is carried out through the two paths of measuring capacitors, different measuring modes can be adopted for the two paths of measuring capacitors, the capacitance change interval can be rapidly locked to improve the response speed, and the cross test of the measuring results can be carried out, so that the measuring precision, the response speed and the reliability of the product are improved.
Drawings
Fig. 1 is a schematic structural view of a capacitance type oil level gauge according to a preferred embodiment of the present invention;
FIG. 2 is a cross-sectional side view of the capacitive sensor of the capacitive oil level gauge of FIG. 1;
FIG. 3 is a cross-sectional view of the capacitive sensor of the capacitive oil level gauge of FIG. 1 in a bottom view;
fig. 4 is a schematic diagram of the operation of the measurement and control module of the capacitance type oil level gauge shown in fig. 1.
In the figure: 1. a gauge head; 2. a process connection; 3. a capacitive sensor; 31. a measuring cylinder; 32. a measuring rod; 321. a metal inner core; 322. an insulating layer; 311. a liquid inlet hole; 312. and an exhaust hole.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and detailed description, wherein it is to be understood that, on the premise of no conflict, the following embodiments or technical features may be arbitrarily combined to form new embodiments.
Referring to fig. 1, 2, 3 and 4, fig. 1 is a schematic structural diagram of a capacitive oil level gauge according to a preferred embodiment of the present invention, where the capacitive oil level gauge includes a gauge outfit 1, a process connector 2 and a capacitive sensor 3, the capacitive sensor 3 is fixed to the gauge outfit 1 by the process connector 2, and the gauge outfit 1 includes a housing and a measurement and control module embedded in the housing;
fig. 2 shows a sectional view of the capacitive sensor 3 in a side view, and fig. 3 shows a sectional view of the capacitive sensor 3 in a bottom view, the capacitive sensor 3 including a measuring cylinder 31 and two measuring rods 32 built in the measuring cylinder 31, and each measuring rod 32 being fixed in relative position to the measuring cylinder 31; specifically, the measuring cylinder 31 is cylindrical, the measuring rod 32 includes a cylindrical metal inner core 321 and an insulating layer 322 sleeved outside the metal inner core 321, the insulating layer 322 may be a PTFE tube, the bottom end of the sidewall of the measuring cylinder 31 is provided with a liquid inlet 311, and the top end of the sidewall of the measuring cylinder 31 is provided with an exhaust hole 312;
the liquid inlet hole 311 and the air outlet hole 312 form a fluid passage, when the measured medium flows in from the liquid inlet hole 311, the air in the measuring cylinder 31 is discharged from the air outlet hole 312, so that the measured medium forms a stable liquid level height, and the liquid level heights inside and outside the measuring cylinder 31 are kept consistent;
fig. 4 is a schematic diagram of a measurement and control module of the capacitive oil level gauge according to the embodiment, where the measurement and control module includes a capacitive digital conversion chip, a power supply circuit, a temperature sensor, a signal output circuit, a key input circuit, and a display output circuit, where the capacitive digital conversion chip may be specifically a chip PCap02 or a chip PCap04; the power supply circuit is respectively and electrically connected with the capacitance digital conversion chip, the signal output circuit, the key input circuit and the display output circuit, and the capacitance digital conversion chip is respectively and signally connected with the temperature sensor, the signal output circuit, the key input circuit and the display output circuit; specifically, the shell of the gauge outfit 1 is provided with a key module and a display module, which are respectively connected with a key input circuit and a display output circuit, wherein the key module refers to hardware such as a keyboard, and the display module refers to hardware such as a display;
in this example, the capacitance-to-digital conversion chip of the measurement and control module is in signal connection with the capacitance sensor 3, in the capacitance sensor 3, the measuring tube 31 and the two measuring rods 32 respectively form two paths of different measuring capacitances, namely, the measuring tube 31 and one measuring rod 32 form one path of measuring capacitance, the measuring tube 31 and the other measuring rod 32 form the other path of measuring capacitance, the two paths of measuring capacitances are both in signal connection with the capacitance-to-digital conversion chip, and specifically, the two paths of measuring capacitances can be respectively connected with different measuring foot tubes of the capacitance-to-digital conversion chip through cables;
specifically, the metal inner cores 321 of each measuring rod 32 can form a cylindrical capacitor model (namely the measuring capacitance) with the measuring cylinder 31, namely, two cylindrical capacitor models are respectively formed by the two metal inner cores 321 and the measuring cylinder 31, and according to the related theoretical knowledge of the cylindrical capacitor models, the liquid level change of the measured medium is converted into the capacitance value change of the measuring capacitance;
in this embodiment, the power supply circuit is configured to convert a voltage input from an external power grid into a voltage required by each circuit module of the capacitive oil level gauge; the capacitance-to-digital conversion chip is used for controlling the whole circuit of the liquid level meter and converting the capacitance value acquired by the capacitance sensor into a standard digital value and calculating the liquid level value; the signal output circuit is used for converting the liquid level value into a standard communication signal and outputting the standard communication signal to the upper computer; the temperature sensor is used for converting temperature information into corresponding electric signals; the key input circuit is used for transmitting the input information of the key module to the capacitance-digital conversion chip; the display output circuit is used for transmitting the output information of the capacitance-to-digital conversion chip to the display module.
The main working process of the capacitive oil level gauge of the embodiment is as follows:
(1) The capacitance type oil level gauge is arranged at a proper position of a medium container, and a measured medium enters the measuring cylinder 31 from the liquid inlet 311, so that capacitance values of two paths of measuring capacitors are changed, and the capacitance values of the two paths of measuring capacitors are named as Ca and Cb respectively for the purpose of description;
(2) The capacitance digital conversion chip respectively collects the variable quantity of Ca and Cb, performs primary data comparison, filters out data of an over comparison range and the over liquid level change speed, and simultaneously adopts different measurement modes for Ca and Cb to rapidly lock a capacitance change interval so as to improve the response speed; at the moment, according to effective Ca and Cb values, collected temperature variation, a set value stored in a chip and a temperature compensation algorithm, calculating the height of a measured medium relative to the capacitance sensor 3 by utilizing theoretical knowledge of a cylindrical capacitance model, namely a liquid level value of the measured medium;
(3) The capacitance digital conversion chip converts the liquid level value into a standard communication signal through the signal output circuit and outputs the standard communication signal to the upper computer, and the liquid level value is output to a local display module through the display output circuit and displayed.
Advantages of the capacitive oil level gauge of this embodiment over the prior art include:
(1) The measurement and control module adopts an integrally packaged capacitance digital conversion chip element, so that discrete devices of a traditional measurement circuit are omitted, the circuit structure is greatly simplified, the anti-interference capability can be improved, the design difficulty of hardware and software is reduced, and the measurement accuracy of products is improved;
(2) The high integration can improve the consistency of products, reduce the factory calibration time, even the products in the same batch do not need to be calibrated, thereby improving the production efficiency;
(3) The product adopts a double-path capacitance measurement mode, wherein the two paths of measurement capacitances can adopt different measurement modes, the capacitance change interval is rapidly locked to improve the response speed, and the cross test of the measurement result can be carried out, so that the measurement precision, the response speed and the reliability of the product are improved;
(4) The intelligent chip is provided with a temperature sensing interface and an automatic resistance-capacitance compensation mechanism, so that the ambient temperature can be automatically acquired, and the temperature compensation and the resistance-capacitance compensation are realized;
(5) The circuit is highly integrated, low-power consumption measurement can be realized, and the cost performance of the product is improved.
The above embodiments are only preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, but any insubstantial changes and substitutions made by those skilled in the art on the basis of the present invention are intended to be within the scope of the present invention as claimed.
Claims (1)
1. The utility model provides a capacitanc oil level gauge, includes gauge outfit, process connection spare and capacitive sensor, capacitive sensor passes through the process connection spare with gauge outfit is fixed, its characterized in that: the gauge outfit comprises a shell and a measurement and control module arranged in the shell, the measurement and control module comprises a capacitance digital conversion chip, the capacitance sensor comprises a measuring cylinder and two measuring rods arranged in the measuring cylinder, the relative positions of the measuring rods and the measuring cylinder are fixed, the measuring cylinder and the two measuring rods form two paths of measurement capacitors respectively, the two paths of measurement capacitors are connected to different measurement foot pipes of the capacitance digital conversion chip respectively, the bottom end of the side wall of the measuring cylinder is provided with a liquid inlet hole, and the top end of the side wall of the measuring cylinder is provided with an exhaust hole; the measuring capacitor is connected with a measuring pin tube of the capacitor digital conversion chip through a cable; the measuring cylinder is cylindrical, and the measuring rod comprises a cylindrical metal inner core and an insulating layer sleeved outside the metal inner core; the measurement and control module further comprises a power supply circuit, a temperature sensor, a signal output circuit, a key input circuit and a display output circuit, wherein the power supply circuit is respectively connected with the capacitance digital conversion chip, the signal output circuit, the key input circuit and the display output circuit, and the capacitance digital conversion chip is respectively connected with the temperature sensor, the signal output circuit, the key input circuit and the display output circuit; the shell is provided with a key module and a display module which are respectively connected with the key input circuit and the display output circuit; the capacitance digital conversion chip is a chip PCap02 or a chip PCap04;
the working process of the capacitance type oil level gauge is as follows:
(1) The capacitance type oil level gauge is arranged at a proper position of a medium container, and a measured medium enters the measuring cylinder from the liquid inlet, so that capacitance values of two paths of measuring capacitors are changed, and the capacitance values of the two paths of measuring capacitors are named as Ca and Cb respectively for the purpose of description;
(2) The capacitance digital conversion chip respectively collects the variable quantity of Ca and Cb, performs primary data comparison, filters out data of an over comparison range and the over liquid level change speed, and simultaneously adopts different measurement modes for Ca and Cb to rapidly lock a capacitance change interval so as to improve the response speed; at the moment, according to effective Ca and Cb values, collected temperature variation, a set value stored in a chip and a temperature compensation algorithm, calculating the height of a measured medium relative to a capacitance sensor by utilizing theoretical knowledge of a cylindrical capacitance model, namely a liquid level value of the measured medium;
(3) The capacitance digital conversion chip converts the liquid level value into a standard communication signal through the signal output circuit and outputs the standard communication signal to the upper computer, and the liquid level value is output to a local display module through the display output circuit and displayed.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910488238.6A CN112050898B (en) | 2019-06-05 | 2019-06-05 | Capacitance type oil level gauge |
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| CN201910488238.6A CN112050898B (en) | 2019-06-05 | 2019-06-05 | Capacitance type oil level gauge |
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| CN112050898A CN112050898A (en) | 2020-12-08 |
| CN112050898B true CN112050898B (en) | 2023-05-02 |
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| CN113108864A (en) * | 2021-03-31 | 2021-07-13 | 宝力马（苏州）传感技术有限公司 | Liquid level meter based on transmission and reflection characteristics of signal in variable impedance medium |
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| CN2622681Y (en) * | 2003-06-06 | 2004-06-30 | 金湖县红光仪表厂 | Self-calibration and capacitor type level gage |
| CN203148521U (en) * | 2012-07-20 | 2013-08-21 | 四川农业大学 | Feed amount detection apparatus |
| JP5597789B2 (en) * | 2013-06-06 | 2014-10-01 | 亀岡電子株式会社 | Capacitive liquid level sensor |
| CH712764A2 (en) * | 2016-07-22 | 2018-01-31 | Tecan Trading Ag | Pipette tip comprising a volume measuring electrode and method for their preparation and pipetting device. |
| CN109297563B (en) * | 2018-11-15 | 2024-02-23 | 河南菲普斯特仪器仪表有限公司 | Method and device for measuring hydraulic oil in narrow space |
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