CN114279622A - Differential pressure sensor - Google Patents
Differential pressure sensor Download PDFInfo
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- CN114279622A CN114279622A CN202111440699.XA CN202111440699A CN114279622A CN 114279622 A CN114279622 A CN 114279622A CN 202111440699 A CN202111440699 A CN 202111440699A CN 114279622 A CN114279622 A CN 114279622A
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- 239000003990 capacitor Substances 0.000 claims abstract description 108
- 238000005259 measurement Methods 0.000 claims abstract description 68
- 230000003068 static effect Effects 0.000 claims abstract description 15
- 238000005070 sampling Methods 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 7
- 230000005284 excitation Effects 0.000 claims description 3
- 238000001125 extrusion Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 description 6
- 239000012530 fluid Substances 0.000 description 5
- 238000009530 blood pressure measurement Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 230000007774 longterm Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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Abstract
The invention provides a differential pressure sensor, which comprises a base, a central diaphragm, a measurement capacitor plate and a reference capacitor plate: the central diaphragm divides the cavity into a first measuring chamber and a second measuring chamber, and the first measuring chamber and the second measuring chamber are respectively communicated with the first channel hole and the second channel hole; the first measurement chamber and the second measurement chamber are filled with insulating media; the measuring capacitor plate and the reference capacitor plate are connected in an insulating way; the measuring capacitor plates are arranged on two sides of the central diaphragm and close to the central area of the central diaphragm to form measuring capacitors, wherein the number of the measuring capacitors is not less than two; the reference capacitor plates are arranged on two sides of the central diaphragm and far away from the central area of the central diaphragm to form reference capacitors, wherein the number of the reference capacitors is not less than two. By adding a reference capacitance and locating it away from the central area of the central diaphragm, measurement errors due to temperature and static pressure variations are substantially eliminated.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to a differential pressure sensor.
Background
Referring to fig. 3 of the attached drawings of the specification, a metal capacitive sensor is generally two capacitors formed by two pole plates and a middle isolation diaphragm, and under the condition of pressure change, the pole plates of the two capacitors are deformed correspondingly, so that the output capacitance value changes, and the change and the pressure value form a certain functional relationship.
The reasons for poor measurement accuracy caused by temperature factors are as follows: under different temperatures and the same pressure conditions, the deformation of the plates of the capacitor is affected by the temperature, that is, the capacitance value changes inconsistently.
The reasons for the poor measurement accuracy caused by the static pressure factors are: filling liquid is filled in the metal capacitance sensor, and the filling liquid can expand or compress along with the change of static pressure and temperature, so that the capacitance value changes, and the measurement accuracy is influenced;
in the prior art, a 24-hour temperature compensation test needs to be carried out in a high-low temperature box for solving the problem of poor measurement accuracy caused by temperature factors, and no solution exists for the problem of poor measurement accuracy caused by static pressure.
Disclosure of Invention
In view of the deficiencies in the prior art, it is an object of the present invention to provide a differential pressure sensor.
The invention provides a differential pressure sensor, which comprises a base, a central diaphragm, a measurement capacitor plate and a reference capacitor plate:
a cavity is arranged in the base;
the central diaphragm divides the cavity into a first measuring chamber and a second measuring chamber, and the first measuring chamber and the second measuring chamber are respectively communicated with the first channel hole and the second channel hole;
the first measurement chamber and the second measurement chamber are filled with insulating media;
the measuring capacitor plate and the reference capacitor plate are connected in an insulating way;
the measuring capacitor plates are arranged on two sides of the central diaphragm and close to the central area of the central diaphragm to form measuring capacitors, wherein the number of the measuring capacitors is not less than two;
the reference capacitor plates are arranged on two sides of the central diaphragm and far away from the central area of the central diaphragm to form a positive even number of reference capacitors, wherein the number of the reference capacitors is not less than two;
in the measuring process, the central diaphragm deforms under the extrusion of pressure, the capacitance values of the measuring capacitor and the reference capacitor are changed due to the deformation of the central diaphragm, and the capacitance value change of the reference capacitor is used as a real-time capacitance compensation value of the temperature and static pressure change of the measuring capacitor.
Optionally, the base includes an upper shell and a lower shell, the inner walls of both the upper shell and the lower shell are connected with an insulating layer, and the measurement capacitor plate and the reference capacitor plate are connected with the insulating layer.
Optionally, the longitudinal section of the cavity is in a rectangular or elliptical structure.
Optionally, the reference capacitor plate is ring shaped.
Optionally, the insulated connection between the measurement and reference capacitor plates is in a non-contact manner.
Optionally, the ratio of the capacitance values of the reference capacitance and the measurement capacitance is ≦ 1: 10.
Optionally, the method further comprises:
an oscillator: for providing an excitation voltage for the reference capacitance and the measurement capacitance;
a sampling circuit: for sampling the reference capacitance and the measurement capacitance;
a processor: the capacitance value sampled by the sampling circuit is converted into a voltage difference value.
Optionally, the measurement capacitor plates are symmetrically disposed on two sides of the central diaphragm, and the reference capacitor plates are symmetrically disposed on two sides of the central diaphragm.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, by adding the reference capacitor and arranging the reference capacitor at the position far away from the central area of the central diaphragm, when the differential pressure sensor works, as the reference capacitor is far away from the central area, the capacitance value change of the reference capacitor caused in the measuring process can be ignored, the capacitance change value of the reference capacitor is equal to the capacitance value change caused by temperature and static pressure, and the capacitance change value of the reference capacitor is taken as the compensation value of the capacitance value change of the measuring capacitor caused by temperature and static pressure, so that the temperature calibration can be omitted, the capacitance-pressure curve can be directly fitted at normal temperature, the measuring precision requirement can be met, the temperature compensation time can be saved for 24 hours, and when the differential pressure sensor is used for a long time, the dielectric constant of the internal filling liquid can be compensated, and the long-term stability is improved.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a schematic structural view of a differential pressure sensor provided in embodiment 2 of the present invention;
fig. 2 is a measurement schematic diagram of a differential pressure sensor provided in embodiment 2 of the present invention;
fig. 3 is a differential pressure sensor provided in embodiment 1 of the present invention.
In the figure:
1-an upper shell;
2-a central membrane;
3-a lower shell;
4-an insulating medium;
5-measuring the capacitance plate;
6-reference capacitive plate;
7-a first measurement chamber;
8-a second measurement chamber;
9-a base;
10-a first channel hole;
11-second channel hole.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
Example 1
As shown in fig. 3, in the differential pressure sensor, two capacitors are formed by two electrode plates and a central diaphragm, and under the condition of pressure change, the electrode plates of the two capacitors have corresponding deformation, so that the output capacitance value changes, and the change and the pressure value form a certain functional relationship, and a corresponding differential pressure value can be obtained according to the functional relationship, wherein the differential pressure value calculation formula is as follows: Δ P-P1-P2-k (C)H-CL) Wherein P1 is high pressure measurement pressure value, P2 is low pressure side pressure value, CHIs a high side capacitance value, CLAnd k is a parameter, namely a parameter corresponding to the relation between the capacitance and the pressure value.
In the above example 1, there is a problem that when the temperature changes or the static pressure changes, the filling liquid between the metal structure of the capacitance sensor and the electrode plate expands and contracts, which complicates the functional relationship among the capacitance value, the pressure value, the temperature value, and the static pressure value, and deteriorates the measurement accuracy of the pressure.
Example 2
Fig. 1 is a schematic structural diagram of a differential pressure sensor provided in an embodiment of the present invention, and fig. 2 is a schematic measurement diagram of the differential pressure sensor provided in the embodiment of the present invention; referring to fig. 1 and 2, the differential pressure sensor in the present embodiment includes a base 9, a central diaphragm 2, a measurement capacitive plate 5, and a reference capacitive plate 6.
In this embodiment, the measurement and reference capacitor plates 5 and 6 are both conductive coatings.
The inside cavity that is provided with of base 9, wherein, the longitudinal section of cavity is oval structure, and the oval structure is set to the cavity is because processing is convenient on the one hand, and on the other hand because oval structure accords with the mode that central diaphragm 2 warp.
In other embodiments, the longitudinal section of the cavity may be rectangular, which is convenient for processing.
The central membrane 2 divides the cavity into a first measurement chamber 7 and a second measurement chamber 8, the first measurement chamber 7 and the second measurement chamber 8 communicating with a first passage hole 10 and a second passage hole 11, respectively.
In this embodiment, according to the difference of the passages through which the high-pressure fluid and the low-pressure fluid are introduced during measurement, the first measurement chamber 7 and the second measurement chamber 8 can both be used as a high-pressure measurement chamber or a low-pressure measurement chamber, and the first passage hole 10 and the second passage hole 11 are used for introducing the fluid requiring the measurement of the pressure difference, wherein the central diaphragm 2 is made of a metal material, and the central diaphragm 2 can deform along with the pressure change.
The first measuring chamber 7 and the second measuring chamber 8 are filled with insulating 4 medium.
In the present embodiment, the insulating medium 4 is generally a liquid-type insulating medium.
The measurement capacitor plate 5 and the reference capacitor plate 6 are connected in an insulated manner, and the measurement capacitor plate 5 and the reference capacitor plate 6 are not in contact with each other in an insulated manner.
In the present embodiment, providing the reference capacitor plate 6 in a ring shape, providing the reference capacitor plate 6 in the inner ring of the ring shape, and providing the reference capacitor plate 6 in a ring shape can improve the sensitivity of the reference capacitor 6.
The measuring capacitor plates 5 are arranged on two sides of the central diaphragm 2 and close to the central area of the central diaphragm 2 and form measuring capacitors, wherein the number of the measuring capacitors is not less than two.
In the present embodiment, the number of the measurement capacitors is two, and the central area of the central diaphragm 2 can be understood as the area where the central diaphragm 2 deforms greatly when the differential pressure value is measured is the central area.
The reference capacitance plates 6 are arranged on both sides of the central diaphragm 2 and away from the central area of the central diaphragm 2 and form reference capacitances, wherein the number of the reference capacitances is not less than two.
In this embodiment, the number of the reference capacitors is two, and the reference capacitor plate 6 is located in a region where the central diaphragm 2 is less deformed when the differential pressure value is measured.
It can be understood that the reference capacitor plate 6 is far away from the central area of the central diaphragm 2, and when the differential pressure of the fluid is measured, the capacitance value of the reference capacitor changes little after the reference capacitor receives the pressure of the fluid, so that the change amount of the capacitance value of the reference capacitor can be considered as the change caused by temperature and static pressure.
In the measuring process, the central diaphragm 2 deforms under the extrusion of pressure, the central diaphragm 2 deforms to enable the capacitance values of the measuring capacitor and the reference capacitor to change, the capacitance values of the measuring capacitor and the reference capacitor change, the reference capacitor is far away from the central area of the central diaphragm 2, and after the reference capacitor is far away from the central area of the central diaphragm 2, the capacitance value change of the reference capacitor can be ignored in the measuring process, so that the capacitance value change of the reference capacitor can be used as a real-time capacitance compensation value of the temperature and static pressure change of the measuring capacitor.
In this embodiment, the reference capacitors respectively measure capacitance values of the first measurement chamber 7 and the second measurement chamber 8, and respectively calculate corresponding capacitance value variations, wherein the capacitance value variation of the reference capacitor of the first measurement chamber 7 is measured as a real-time capacitance compensation value of the measurement capacitor of the first measurement chamber 7, and the capacitance value variation of the reference capacitor of the second measurement chamber 8 is measured as a real-time capacitance compensation value of the measurement capacitor of the second measurement chamber 8.
In an alternative embodiment, the base 9 comprises an upper housing 1 and a lower housing 3, an insulating layer (not shown) is connected to the inner wall of each of the upper housing 1 and the lower housing 3, and the measuring capacitor plate 5 and the reference capacitor plate 6 are connected to the insulating layer.
In this embodiment, the edge of the central membrane 2 is welded between the upper and lower housings 1, 3, and the insulating layer may be a glass layer.
In an alternative embodiment, the capacitance ratio of the reference capacitance to the measurement capacitance is ≦ 1:10, which can reduce production costs.
In an optional embodiment, further comprising:
an oscillator: for providing an excitation voltage for the reference capacitance and the measurement capacitance;
a sampling circuit: for sampling the reference capacitance and the measurement capacitance;
a processor: the capacitance value sampled by the sampling circuit is converted into a voltage difference value.
In this embodiment, the oscillator converts the direct current of the power supply into alternating current, the oscillator is connected with the reference capacitor plate, the measurement capacitor plate and the central diaphragm 2 through leads, the sampling circuit samples the capacitance values of the reference capacitor and the measurement capacitor, and the processor calculates the differential pressure value through the capacitance value, the temperature compensation and the static pressure compensation, wherein the calculation formula of the differential pressure value is as follows:
ΔP＝P1-P2＝k*{CH/[(Ch compensation 1+CL Compensation 1)/(CH compensation 2+CL Compensation 2)]-CL/[(CH compensation 1+CL Compensation 1)/(CH compensation 2+CL Compensation 2)]}
＝k/[(CH compensation 1+CL Compensation 1)/CH compensation 2+CL Compensation 2)]*(CH-CL)
＝k2*(CH-CL)；
Wherein, in the above formula:
Ch compensation 1A compensation capacitance value factory calibrated for the first measurement chamber 7;
Cl Compensation 1A compensation capacitance value factory-calibrated for the second measurement chamber 8;
Ch compensation 2Real-time compensation for pressure measurement of the first measurement chamber 7The compensated capacitance value can be understood as the capacitance value variation of the reference capacitor when the first measurement chamber 7 is measured;
Cl Compensation 2Measuring the real-time compensation capacitance value for the pressure of the second measurement chamber 8, that is, the capacitance value variation of the reference capacitor when the second measurement chamber 8 is measured;
CHthe capacitance value of a measuring capacitor corresponding to the first measuring chamber is measured when the differential pressure is measured;
CLthe capacitance value of the measuring capacitor corresponding to the second measuring chamber is measured when the differential pressure is measured;
Δ P is a differential pressure value, P1 is a pressure value of the first measurement chamber, P2 is a pressure value of the second measurement chamber, and k is a parameter, i.e., a parameter corresponding to a relationship between capacitance and pressure value.
In an alternative embodiment, the measuring capacitor plates 5 are symmetrically arranged on two sides of the central diaphragm 5, and the reference capacitor plates 6 are symmetrically arranged on two sides of the central diaphragm 2, so that the calculation amount in the differential pressure value calculation can be well reduced.
In comparison with embodiment 1, embodiment 2 described above is advantageous in that, by adding a reference capacitance, and disposing the reference capacitance at a position distant from the central area of the central diaphragm 2, when the differential pressure sensor works, because the reference capacitor is far away from the central area, the capacitance value change of the reference capacitor caused in the measuring process can be ignored, the capacitance change value of the reference capacitor is equal to the capacitance value change caused by temperature and static pressure, the capacitance change value of the reference capacitor is used as the compensation value of the capacitance value change of the measuring capacitor caused by temperature and static pressure, therefore, the capacitance-pressure curve can be directly fitted at normal temperature without temperature calibration, the measurement precision requirement can be met, the temperature compensation time of 24 hours is saved, and when the filling liquid is used for a long time, the change of the dielectric constant of the filling liquid can be compensated, and the long-term stability is improved.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (8)
1. A differential pressure sensor, comprising a base, a central diaphragm, a measurement capacitive plate and a reference capacitive plate:
a cavity is arranged in the base;
the central diaphragm divides the cavity into a first measuring chamber and a second measuring chamber, and the first measuring chamber and the second measuring chamber are respectively communicated with the first channel hole and the second channel hole;
the first measurement chamber and the second measurement chamber are filled with insulating media;
the measurement capacitor plate and the reference capacitor plate are connected in an insulating way;
the measuring capacitor plates are arranged on two sides of the central diaphragm and close to the central area of the central diaphragm to form measuring capacitors, wherein the number of the measuring capacitors is not less than two;
the reference capacitor plates are arranged on two sides of the central diaphragm and far away from the central area of the central diaphragm to form reference capacitors, wherein the number of the reference capacitors is not less than two;
in the measuring process, the central diaphragm deforms under the extrusion of pressure, the capacitance values of the measuring capacitor and the reference capacitor are changed due to the deformation of the central diaphragm, and the capacitance value change of the reference capacitor is used as a real-time capacitance compensation value of the temperature and static pressure change of the measuring capacitor.
2. The differential pressure sensor of claim 1, wherein the base comprises an upper shell and a lower shell, an insulating layer is connected to the inner wall of each of the upper shell and the lower shell, and the measurement capacitor plate and the reference capacitor plate are connected to the insulating layer.
3. The differential pressure sensor of claim 1, wherein a longitudinal cross-section of the chamber is rectangular or oval in configuration.
4. The differential pressure sensor of claim 1, wherein the reference capacitive plate is ring shaped.
5. The differential pressure sensor of claim 1, wherein the measurement and reference capacitive plates are connected in an insulated manner without contact.
6. The differential pressure sensor of claim 1, wherein the reference capacitance and the measurement capacitance have a capacitance ratio ≦ 1: 10.
7. The differential pressure sensor of claim 1, further comprising:
an oscillator: the reference capacitor and the measurement capacitor are used for providing excitation voltage;
a sampling circuit: for sampling the reference and measurement capacitances;
a processor: the capacitance value sampled by the sampling circuit is converted into a voltage difference value.
8. The differential pressure sensor of claim 1, wherein the measurement capacitive plates are symmetrically disposed on both sides of the central diaphragm and the reference capacitive plates are symmetrically disposed on both sides of the central diaphragm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111440699.XA CN114279622A (en) | 2021-11-30 | 2021-11-30 | Differential pressure sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111440699.XA CN114279622A (en) | 2021-11-30 | 2021-11-30 | Differential pressure sensor |
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| CN114279622A true CN114279622A (en) | 2022-04-05 |
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1350636A (en) * | 1999-05-14 | 2002-05-22 | 罗斯蒙德公司 | Course pressure measuring device with improved error compensation |
| CN1672023A (en) * | 2002-07-31 | 2005-09-21 | 恩德莱斯和豪瑟尔两合公司 | Capacitive pressure sensor |
| US20060243053A1 (en) * | 2000-10-19 | 2006-11-02 | Karl-Heinz Banholzer | Pressure measuring cell |
| CN101184978A (en) * | 2005-05-27 | 2008-05-21 | 罗斯蒙德公司 | Line pressure measurement using differential pressure sensor |
| CN103748447A (en) * | 2011-07-01 | 2014-04-23 | 恩德莱斯和豪瑟尔两合公司 | Method for operating an absolute pressure or relative pressure sensor with a capacitive transducer |
| CN105841875A (en) * | 2014-09-30 | 2016-08-10 | 罗斯蒙特公司 | Differential pressure sensor with high pressure capabilities |
| CN109900415A (en) * | 2019-03-26 | 2019-06-18 | 大庆市镁华仪仪表衡器有限公司 | A kind of pressure pressure difference transmitter |
| CN111982383A (en) * | 2020-07-06 | 2020-11-24 | 厦门大学 | Differential pressure contact type MEMS capacitance film vacuum gauge |
-
2021
- 2021-11-30 CN CN202111440699.XA patent/CN114279622A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1350636A (en) * | 1999-05-14 | 2002-05-22 | 罗斯蒙德公司 | Course pressure measuring device with improved error compensation |
| US20060243053A1 (en) * | 2000-10-19 | 2006-11-02 | Karl-Heinz Banholzer | Pressure measuring cell |
| CN1672023A (en) * | 2002-07-31 | 2005-09-21 | 恩德莱斯和豪瑟尔两合公司 | Capacitive pressure sensor |
| CN101184978A (en) * | 2005-05-27 | 2008-05-21 | 罗斯蒙德公司 | Line pressure measurement using differential pressure sensor |
| CN103748447A (en) * | 2011-07-01 | 2014-04-23 | 恩德莱斯和豪瑟尔两合公司 | Method for operating an absolute pressure or relative pressure sensor with a capacitive transducer |
| CN105841875A (en) * | 2014-09-30 | 2016-08-10 | 罗斯蒙特公司 | Differential pressure sensor with high pressure capabilities |
| CN109900415A (en) * | 2019-03-26 | 2019-06-18 | 大庆市镁华仪仪表衡器有限公司 | A kind of pressure pressure difference transmitter |
| CN111982383A (en) * | 2020-07-06 | 2020-11-24 | 厦门大学 | Differential pressure contact type MEMS capacitance film vacuum gauge |
Non-Patent Citations (2)
| Title |
|---|
| 王淑坤 等: "《传感器原理及应用》", 31 August 2021, 厦门大学出版社, pages: 79 - 80 * |
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