Submerged metal capacitive differential pressure sensor

Abstract

The utility model provides a kind of immersed metal capacitive differential pressure sensor, comprising: shell, enclosed and hold cavity;Sensing element, hold in the holding cavity, and the gap between the sensing element and the inner wall surface of shell;Wherein, the holding cavity and gap are used to hold filling liquid, to make static pressure via the filling liquid each direction evenly conducted to the sensing element, and then make the sensing element be in static pressure equilibrium state.The utility model solves the problem that metal capacitive differential pressure transmitter generates static pressure influence error under high static pressure condition, improves the output stability and measurement reliability of metal capacitive differential pressure transmitter under high static pressure condition.

Description

Technical Field

[0001] This utility model relates to the field of fluid pressure sensors, specifically to an immersion-type metal capacitive differential pressure sensor. Background Technology

[0002] Existing metal capacitive differential pressure sensors suffer from the following problems, severely impacting their performance: 1. Static pressure significantly affects the error, which is difficult to completely eliminate. Due to the inherent structure of the metal capacitive differential pressure sensor, it is extremely sensitive to operating static pressure. As the operating static pressure increases, the sensor's output error increases significantly, especially at full-scale output. This error exhibits a linear growth trend with the static pressure value; 2. The zero-point drift direction is uncertain and cannot be regularly calibrated. Under static pressure, the sensor's zero-point output exhibits random shifts, and the direction and magnitude of these shifts are not fixed. 1. This offset is related to factors such as individual sensor differences, residual welding stress, and minor assembly defects in components. It cannot be compensated for through uniform calibration methods and may lead to misjudgment or miscontrol during long-term use. 2. The diaphragm tension effect will suppress sensitivity and compress the output. Under high static pressure conditions, the central diaphragm will become excessively tensile due to increased structural stress, resulting in reduced movable deflection and weakened sensitivity to differential pressure. This will lead to a decrease in the amplitude of differential capacitance change and overall compression of the output signal, especially in small differential pressure scenarios, which will affect the linearity of low-end measurements. 3. Structural stress concentration and the induction of local variations 5. The structure is limited, which is not conducive to high-precision compensation design. The traditional metal capacitive sensor has a complex structure and large differences in rigidity between its components, making it difficult to achieve accurate correction through integrated compensation methods (such as adding pressure-sensitive elements). 6. The linear output characteristics degrade severely under high static pressure. Under high static pressure, not only is the overall output low, but the originally linear capacitance response curve is compressed and deformed, which aggravates the output distortion. This nonlinear output limits the applicability of the sensor in applications with high linear accuracy requirements, such as flow measurement. 7. It cannot meet the requirements of long-term operation under harsh conditions. Due to the stress concentration and fatigue risk of the sensor shell, the reliability and consistency of metal capacitive sensors are poor in long-term high temperature and high pressure working scenarios. It is prone to performance drift and shortened life, especially in continuous operation applications such as power plants and chemical plants, where performance limitations are obvious.

[0003] As the market demands for the accuracy of differential pressure transmitters continue to rise, various contradictions caused by the static pressure effect of differential pressure transmitters are becoming increasingly prominent. Currently available metal capacitor differential pressure transmitters can no longer meet the high-precision measurement requirements under multi-point static pressure.

[0004] Therefore, how to obtain high-precision measurement requirements that can meet the requirements of multi-point static pressure needs to be studied urgently. Utility Model Content

[0005] The purpose of this invention is to provide an immersion-type metal capacitive differential pressure sensor to solve the problem of static pressure influence error in metal capacitive differential pressure transmitters under high static pressure conditions, thereby improving the output stability and measurement reliability of metal capacitive differential pressure transmitters under high static pressure conditions.

[0006] To achieve the above objectives, this utility model provides the following technical solution: An immersion-type metal capacitive differential pressure sensor, the differential pressure sensor comprising: The outer shell encloses the receiving cavity; A sensitive element is housed in the accommodating cavity, and there is a gap between the sensitive element and the inner wall surface of the housing; The cavity and the slit are both used to contain the filling fluid, so that the static pressure is uniformly transmitted to the sensitive element through the filling fluid, thereby putting the sensitive element into a static pressure equilibrium state.

[0007] Other applicable fields will become apparent from the description provided herein.

[0008] The descriptions and specific examples in this utility model are intended to be illustrative only and are not intended to limit the scope of this utility model.

[0009] Compared with the prior art, the technical solution provided by this utility model has the following beneficial effects: This invention solves the problem of static pressure error in metal capacitive differential pressure sensors under high static pressure conditions. Specifically, it optimizes the structural design of the metal capacitive differential pressure sensor by immersing the sensitive element in the sensor with a filling liquid that has incompressible properties and uniform conduction in all directions. This significantly reduces or even eliminates static pressure error and improves the output stability and measurement reliability of the metal capacitive differential pressure sensor under high static pressure conditions. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some implementation schemes of this utility model. For those skilled in the art, other solutions can be obtained based on these drawings without creative effort.

[0011] Figure 1 A cross-sectional view of an immersion metal capacitive differential pressure sensor provided in one embodiment of the present invention; Figure 2 for Figure 1 A cross-sectional view of the differential pressure sensor after some components have been removed. Figure 3 This is a schematic diagram of the structure of an immersion metal capacitive differential pressure sensor provided for another embodiment of the present invention.

[0012] Explanation of reference numerals in the attached figures 1-Outer shell; 10-Receiving cavity; 101-First receiving cavity; 102-Second receiving cavity; 11-Liquid channel; 2-Sensitive element; 21-Curved base; 211-Base; 212-Insulating substrate; 213-Fixed electrode; 2131-High voltage chamber; 2132-Low voltage chamber; 214-Ceramic core; 2140-Through hole; 22-Common electrode; 3- Gap; 4-Weld lip; 5- Tighten the boss; 6-Separation membrane; 7-Insulator; 71-Metallic body; 72-Insulating layer; 73-Metallic tube; 8-Lead electrode. Detailed Implementation

[0013] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model. It should be understood that the specific embodiments described herein are only for illustration and explanation of this utility model, and are not intended to limit this utility model.

[0014] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0015] The terminology used in this invention is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” as used herein are intended to include the plural forms as well. The terms “comprising,” “including,” “containing,” and “having” are inclusive and thus describe the presence of said features, elements, compositions, steps, integers, operations, and / or components, but do not exclude the presence or inclusion of one or more other features, integers, steps, operations, elements, components, and / or sets thereof. Although the open-ended term “comprising” should be understood as a non-limiting term used to describe and claim the various embodiments described in this invention, in some aspects it may instead be understood as a more restrictive and limiting term, such as “consisting of” or “substantially consisting of.” Thus, for any given embodiment describing compositions, materials, components, elements, features, integers, operations, and / or process steps, this invention also particularly includes embodiments consisting of or substantially consisting of such compositions, materials, components, elements, features, integers, operations, and / or process steps. In the case of “consisting of…”, the alternative embodiments exclude any additional compositions, materials, components, elements, features, integers, operations and / or process steps. In the case of “essentially composed of…”, any additional compositions, materials, components, elements, features, integers, operations and / or process steps that substantially affect the essential and novel characteristics are excluded from such embodiments. However, any compositions, materials, components, elements, features, integers, operations and / or process steps that do not substantially affect the essential and novel characteristics may be included in the embodiments.

[0016] Any method steps, processes, and operations described in this invention should not be construed as necessarily requiring them to be performed in the specific order discussed or shown, unless explicitly specified as such. It should also be understood that, unless otherwise stated, additional or alternative steps may be used.

[0017] In this utility model, except for the contents explicitly stated, any matters or matters not mentioned are directly applicable to those known in the art without any changes. Furthermore, any embodiment described in this utility model can be freely combined with one or more other embodiments described in this utility model, and the resulting technical solutions or concepts are considered part of the original disclosure or original record of this utility model, and should not be regarded as new content not disclosed or anticipated by this utility model, unless those skilled in the art consider the combination to be clearly unreasonable.

[0018] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0019] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0020] It is worth noting that the linear calibration of differential pressure sensors is usually performed at atmospheric pressure, i.e., a static pressure of 1 atmosphere. However, in actual operating conditions, the actual static pressure is much greater than 1 atmosphere. Extensive practical experience has shown that static pressure causes offsets in the zero point and range of differential pressure sensors; the combined offset is called static pressure effect error. More specifically, the aforementioned static pressure error often manifests as zero-point drift, full-scale output offset, and nonlinear distortion in the measurement results, severely affecting measurement accuracy, especially in high static pressure and low differential pressure applications.

[0021] Example See Figure 1 and Figure 2 This embodiment provides an immersion-type metal capacitive differential pressure sensor, including: a housing 1 enclosing a cavity 10; a sensing element 2 housed in the cavity 10, with a gap 3 between the sensing element 2 and the inner wall of the housing 1; wherein the cavity 10 and the gap 3 are both used to house a filling liquid, so that static pressure is uniformly transmitted to the sensing element 2 via the filling liquid, thereby putting the sensing element 2 into a static pressure equilibrium state.

[0022] For details, see Figure 1 and Figure 2The immersion-type metal capacitive differential pressure sensor provided by this invention has a housing 1 enclosing a cavity 10, in which the sensitive element 2 is housed. It should be noted that in this invention, a gap 3 is left between the sensitive element 2 and the inner wall of the housing 1, whereas in traditional metal capacitive differential pressure sensors, the sensitive element 2 and the inner wall of the housing 1 are tightly fitted without this gap 3. Furthermore, this gap 3 is designed to accommodate the filling liquid, allowing it to fill the surface of the sensitive element 2 as comprehensively as possible. That is, the filling liquid acts as a buffer and transition between the sensitive element 2 and the inner wall of the housing 1, or it can be said to completely immerse the sensitive element 2 in the filling liquid, thereby minimizing the impact of hydrostatic pressure on the measuring diaphragm inside the sensitive element 2 (i.e., the...). Figure 1 The interference of the deflection of the fixed electrode 213 and the common electrode 22 in the sensor; after the static pressure is weakened by the gap 3 and the filling liquid filling the gap 3, the influence of static pressure on the deflection of the measuring diaphragm can be significantly reduced, thereby improving the measurement reliability and stability of the sensor in a high static pressure environment. It is understood that the immersion metal capacitive differential pressure sensor provided by this utility model, since the sensitive element 2 is almost completely immersed in the filling liquid located in the accommodating cavity 10, when the sensor housing 1 is subjected to external force impact, the liquid filling liquid can provide considerable buffer protection for the sensitive element 2 contained therein, and can evenly disperse the external force impact and instantaneous overload energy, avoiding direct stress concentration on the sensitive element 2, thereby preventing the measuring diaphragm in the sensitive element 2 from being damaged or deformed under external force impact or instantaneous overload energy impact. This deformation sometimes manifests as plastic deformation, that is, the measuring diaphragm cannot automatically recover after such plastic deformation, and needs to be disassembled and maintained by the staff, which requires a considerable cost.

[0023] It is worth noting that the immersion-type metal capacitive differential pressure sensor provided by this utility model preferably uses a rigid material, especially a rigid metal material, to make its housing 1; because rigid materials, especially rigid metal materials, have significant defense and resistance to external impact or instantaneous external overload energy, thereby avoiding impact damage to the sensitive element 2 located inside the housing 1.

[0024] This utility model provides an immersion-type metal capacitive differential pressure sensor that adopts a modular design. The sensitive element 2 is assembled within a cavity 10 enclosed by a housing 1. Specifically, a gap 3 is left between the outer surface of the sensitive element 2 and the inner wall of the housing 1. This gap 3 is used to fill a filling fluid, which disperses external impacts and the effect of static pressure on the sensitive element 2, particularly minimizing the impact of static pressure on the measuring diaphragm inside the sensitive element 2 (specifically, as shown in the diagram). Figure 1The effect of the fixed electrode 213 and the common electrode 22 shown is that by constructing a fully enclosed filling liquid cavity, i.e., the gap 3, around the sensitive element 2, the incompressibility of the liquid and the uniform pressure transmission characteristics in all directions are utilized to achieve force balance under static pressure, thereby improving the stability and reliability of the sensor.

[0025] In addition, the aforementioned filling fluid, being incompressible, can also reduce the stress on the measuring diaphragm (i.e., due to micro-deformation of the outer shell 1 or the release of residual stress) caused by micro-deformation of the outer shell 1. Figure 1 The measurement accuracy of the fixed electrode 213 and the common electrode 22 shown is affected, and the zero drift is reduced, thereby improving the measurement stability, output consistency and anti-interference ability of the sensor in long-term operation.

[0026] It is understood that the specific chemical composition of the filling fluid varies in some embodiments, using silicone oil, while in other embodiments, other liquid media with good incompressibility and good isotropic pressure transmission characteristics are used.

[0027] The sensor housing 1 and the immersion structure provided by this utility model together constitute a protective unit. When the sensor housing 1 is subjected to extreme conditions such as overpressure or sudden pressure changes, the filling fluid (such as silicone oil, fluorinated oil, etc.) has high viscosity and low compressibility, which can uniformly transmit external pressure to the diaphragm and avoid local stress concentration. When the pressure changes suddenly, the viscous damping of the liquid slows down the transmission speed of the pressure wave, reduces the instantaneous impact load on the diaphragm, which is equivalent to providing "dynamic shock absorption" for the diaphragm and helps protect the pressure-sensing diaphragm in the sensitive element 2 (i.e., the pressure-sensing diaphragm). Figure 1 The fixed electrode plate 213 and the common electrode plate 22 shown are not damaged, which improves the absolute pressure resistance and overload resistance of the sensor, thereby extending its service life.

[0028] See Figure 1 It is understood that in this invention, the differential pressure sensing element 2 is completely immersed in an incompressible filling fluid (such as silicone oil). When high static pressure is transmitted to the filling fluid through the isolation diaphragm 6, the filling fluid distributes the pressure evenly to all locations on the sensing element 2, forming a stable hydraulic balance for the sensing element 2. This can effectively eliminate or reduce the impact of static pressure on the pressure-sensing diaphragm (i.e., the pressure sensor diaphragm located inside the sensing element 2). Figure 1 The influence of the deflection of the fixed electrode 213 and the common electrode 22 shown is reduced, thereby reducing the capacitance change and output drift caused by static voltage coupling, thus ensuring measurement accuracy and stability.

[0029] The immersion structure provided by this utility model simplifies the assembly and calibration requirements in the manufacturing process, reduces the complexity of manual debugging, and improves the consistency and pass rate of batch products.

[0030] See Figure 1 and Figure 3In some embodiments of this invention, the sensitive element 2 is fixedly connected to the inner wall of the outer casing 1 via a weld lip 4, so that the sensitive element 2 and the inner wall of the outer casing 1 are pressed together for fixation. It is understood that, theoretically, if the sensitive element 2 could be completely immersed in the liquid filling fluid, the influence of hydrostatic pressure could be perfectly avoided. However, it is impossible to completely eliminate the rigid connection between the sensitive element 2 and the inner wall of the outer casing 1; otherwise, the sensitive element 2 would shake or vibrate when the sensor moves or is impacted, leading to collision or even damage between the sensitive element 2 and the inner wall of the outer casing 1. Therefore, it is necessary to establish a rigid connection between the sensitive element 2 and the inner wall of the outer casing 1 to prevent collision. Of course, even with this rigid connection, due to the above approach, a large portion of the outer surface of the sensitive element 2 provided by this invention is still separated from the inner wall of the outer casing 1 and isolated by the liquid filling fluid to minimize the influence of hydrostatic pressure. Therefore, the rigid connection can be established using the aforementioned weld lip 4, which involves welding a small area between the sensitive element 2 and the inner wall of the housing 1 for fixation, thereby preventing the sensitive element 2 from sloshing within the accommodating cavity 10 and the filling fluid. In other words, the solution provided by this invention establishes a rigid connection with a small contact area but high strength and reliability between the inner wall of the housing 1 and the outer surface of the sensitive element 2. This achieves both immersion protection of the sensitive element 2 from the effects of static pressure and temperature fluctuations and prevents the sensitive element 2 from sloshing in the filling fluid.

[0031] Based on the above-mentioned approach to preventing shaking, this utility model also provides the following solution: a fixed connection between the sensitive element 2 and the inner wall of the outer casing 1 is achieved through a solid clamping structure. See details below. Figure 1 or Figure 3 In some embodiments of this utility model, a clamping boss 5 or clamping protrusion is provided between the sensitive element 2 and the inner wall surface of the outer shell 1, so that the sensitive element 2 and the inner wall surface of the outer shell 1 are clamped together for fixation.

[0032] It is understood that the specific shape and size of the aforementioned clamping boss 5 and clamping protrusion can be adjusted according to the actual application standards. The radial cross-sectional shape of the clamping boss 5 can be circular or polygonal, and the radial cross-sectional shape of the clamping protrusion can be circular or polygonal. The volume of the clamping boss 5 and clamping protrusion should be as small as possible, or in other words, the contact area between the clamping boss 5 and clamping protrusion and the sensitive element 2 should be as small as possible, so as to ensure that the outer surface of the sensitive element 2 is more directly immersed in the filling liquid, and to avoid direct and rigid contact between the sensitive element 2 and the inner wall of the outer shell 1 as much as possible.

[0033] In summary, by using the welding and fixing method of the welding lip 4 and the clamping boss 5 and clamping protrusion of the smallest possible size, the sensitive element 2 is ensured to be submerged in the filling liquid as much as possible, while also ensuring that the sensitive element 2 has the necessary rigid contact with the inner wall of the outer shell 1 to prevent the sensitive element 2 from sloshing in the accommodating cavity 10 and the filling liquid. At this time, the purpose of the filling liquid in dispersing external impact force and reducing the influence of static pressure can still be guaranteed.

[0034] See Figure 1 and Figure 2 In some embodiments of this invention, the sensitive element 2 is cylindrical and has two circular end faces along its axial direction, with the area between these two end faces forming the outer circumferential surface of the sensitive element 2. Correspondingly, the shape of the accommodating cavity 10 in some embodiments of this invention can be adapted to the shape of the sensitive element 2, and specifically, it can also be a cylindrical accommodating cavity 10, as long as a gap 3 can be left between the sensitive element 2 and the inner wall of the outer shell 1 to accommodate the filling liquid.

[0035] In some embodiments of this utility model, the welding lip 4 is disposed on at least one end face of the sensing element 2. In this case, one side of the welding lip 4 located on the end face of the cylindrical sensing element 2 is fixed to the inner wall surface of the outer casing 1 by welding.

[0036] See Figure 3 In some embodiments of this utility model, the welding lip 4 is disposed on the outer peripheral surface of the sensing element 2. In this case, one side of the welding lip 4 located on the outer peripheral surface of the cylindrical sensing element 2 is fixed to the inner wall surface of the outer casing 1 by welding.

[0037] It is worth noting that the specific form of the welding lip 4 set on the outer peripheral surface of the cylindrical sensitive element 2 can be a complete ring welding lip 4 set around the circumference of the sensitive element 2, or multiple welding lips set intermittently along the circumference of the sensitive element 2.

[0038] See Figure 3 In some embodiments of this utility model, the clamping boss 5 or clamping protrusion is provided on at least one end face of the sensitive element 2. At this time, the clamping boss 5 or clamping protrusion on the end face of the cylindrical sensitive element 2 faces the inner wall surface of the outer shell 1 and clamps against the inner wall surface of the outer shell 1.

[0039] In some embodiments of this utility model, the clamping boss 5 or clamping protrusion is provided on the outer peripheral surface of the sensitive element 2. At this time, the clamping boss 5 or clamping protrusion located on the outer peripheral surface of the cylindrical sensitive element 2 faces the inner wall surface of the outer casing 1 and clamps against the inner wall surface of the outer casing 1.

[0040] In some embodiments of this utility model, the clamping boss 5 or clamping protrusion is provided on the inner wall surface of the outer shell 1, and abuts against and clamps the sensitive element 2 at least one end face of the sensitive element 2.

[0041] In some embodiments of this utility model, the clamping boss 5 or clamping protrusion is provided on the inner wall surface of the outer shell 1, and abuts against and clamps the outer peripheral surface of the sensitive element 2.

[0042] In summary, the clamping bosses 5 and clamping protrusions located at different positions described above are all used to fix the sensitive element 2 to the inner wall of the outer casing 1 by clamping.

[0043] See Figure 1 In some embodiments of this utility model, the sensitive element 2 includes: two curved seats 21, with their ports facing each other; and a common electrode plate 22 disposed between the ports of the two curved seats 21. In other words, as Figure 1 As shown, the two curved seats 21 have their ports facing each other, and a common electrode plate 22 is sandwiched between the ports of the two curved seats 21.

[0044] See Figure 1 In some embodiments of this utility model, each curved seat 21 includes: a base 211, which is cup-shaped or bowl-shaped and housed in the curved seat 21, with the cup-shaped or bowl-shaped port of the base 211 facing away from the curved seat 21; an insulating substrate 212, one end of which has a curved structure and is housed in the base 211, with the curved end of the insulating substrate 212 located at the cup-shaped or bowl-shaped port of the base 211; and a fixed electrode plate 213 disposed on the curved surface of the insulating substrate 212; wherein, the common electrode plate 22 is located between the fixed electrode plates 213 of the two curved seats 21. In other words, each curved seat 21 can be further disassembled into three components: a base 211, an insulating substrate 212, and a fixed electrode plate 213, which are assembled according to the above connection relationship to obtain the curved seat 21. It is worth noting that the fixed electrode 213 mentioned above is the aforementioned measuring diaphragm. The fixed electrode 213 can function as a pressure transmitter. The material of the fixed electrode 213 is a material known to those skilled in the art and will not be described in detail here.

[0045] It is understood that in some embodiments, electronic glass can be used as the material for manufacturing the insulating substrate 212, and electronic glass can provide good insulation and is easy to process.

[0046] See Figure 1In some embodiments of this invention, a fixed electrode plate 213 of one curved seat 21 and a common electrode plate 22 together enclose a high-pressure chamber 2131, and a fixed electrode plate 213 of another curved seat 21 and a common electrode plate 22 together enclose a low-pressure chamber 2132. The high-pressure chamber 2131 and the low-pressure chamber 2132 are not connected to each other, and both the high-pressure chamber 2131 and the low-pressure chamber 2132 are used to contain filling liquid. The high-pressure chamber 2131 is used to conduct high pressure in the measured medium, and the low-pressure chamber 2132 is used to conduct low pressure in the measured medium. This sensor simultaneously measures the high and low pressures of the measured medium and calculates the pressure data of the measured medium through differential pressure. In practical applications, the positions of the high-pressure chamber and the low-pressure chamber are not fixed and depend on the comparison results of the capacitance after filling: the chamber with the larger capacitance value is defined as the high-pressure chamber, and the chamber with the smaller capacitance value is defined as the low-pressure chamber. For ease of description, this article uses the attached figure as a reference, and the left chamber is defined as the high-pressure chamber and the right chamber as the low-pressure chamber.

[0047] See Figure 1 In some embodiments of this utility model, each curved seat 21 further includes a ceramic core 214, the ceramic core 214 having a through hole 2140; the ceramic core 214 in each curved seat 21 sequentially penetrates the base 211 and the insulating substrate 212 in the curved seat 21. For example... Figure 1 As shown, the through hole 2140 in the ceramic core 214 connects the liquid guiding channel 11 on the outer shell 1 to a fixed electrode plate 213. Specifically, the side of each fixed electrode plate 213 facing away from the common electrode plate 22 abuts against one end of a ceramic core 214, specifically against one end of the through hole 2140 of that ceramic core 214. The other end of the ceramic core 214 is directly opposite the liquid guiding channel 11. Furthermore, as... Figure 1 As shown, the end of the ceramic core 214 facing the liquid guiding channel 11 is connected to the gap 3, that is, the through hole 2140 in the ceramic core 214 is connected to the gap 3. In other words, the filling liquid located in the gap 3 can flow into the through hole 2140, and then flow to the side of the fixed electrode 213 facing away from the common electrode 22. It should be noted that in the prior art, the filling liquid of the sensor is only located in the through hole 2140 of the ceramic core 214, while the filling liquid of the sensor provided by this utility model is located in both the through hole 2140 of the ceramic core 214 and the gap 3, so that the outer surface of the sensitive element 2 is immersed in the filling liquid as much as possible. This filling liquid weakens the effect of static pressure, ensuring that the deflection of the common electrode 22 and the fixed electrode 213 in the sensitive element 2 is not affected by static pressure, thereby ensuring that the measurement results of the sensor have sufficiently high accuracy, reliability and stability.

[0048] See Figure 1 and Figure 3In some embodiments of this utility model, the receiving cavity 10 is divided into a first receiving cavity 101 and a second receiving cavity 102 that are not interconnected by the welding lip 4; both fixed electrode plates 213 are provided with through holes so that the through hole 2140 of one ceramic core 214, the first receiving cavity 101 and the high pressure cavity 2131 are interconnected, and the through hole 2140 of the other ceramic core 214, the second receiving cavity 102 and the low pressure cavity 2132 are interconnected. It should be noted that, because the first accommodating cavity 101, the through hole 2140 of the ceramic core 214 connected to it, and the high-pressure cavity 2131 are interconnected, especially the high-pressure cavity 2131 is connected to the first accommodating cavity 101 and the through hole of the corresponding ceramic core 214 through the perforation on the fixed electrode plate 213, the pressure of the filling fluid in the above three areas is equal; because the second accommodating cavity 102, the through hole 2140 of the ceramic core 214 connected to it, and the low-pressure cavity 2132 are interconnected, especially the low-pressure cavity 2132 is connected to the second accommodating cavity 102 and the through hole 2140 of the corresponding ceramic core 214 through the perforation on the fixed electrode plate 213, the pressure of the filling fluid in the above three areas is equal.

[0049] See Figure 1 and Figure 3 In some embodiments of this utility model, the welding lip 4 divides the accommodating cavity 10 into two independent cavities, namely the first accommodating cavity 101 and the second accommodating cavity 102, with the following specific connection relationships: 1) High-pressure side: The first accommodating cavity 101, the through hole 2140 of a ceramic core 214, and the high-pressure cavity 2131 are interconnected; wherein, the high-pressure cavity 2131 is connected to the first accommodating cavity 101 and the through hole 2140 of the ceramic core 214 through a perforation on its fixed electrode plate 213; this structure ensures that the filling fluid pressure in these three areas remains consistent; 2) Low-pressure side: The second accommodating cavity 102, the through hole 2140 of another ceramic core 214, and the low-pressure cavity 2132 are interconnected; similarly, the low-pressure cavity 2132 is connected to the second accommodating cavity 102 and the through hole 2140 of the ceramic core 214 through a perforation on its fixed electrode plate 213; this structure ensures that the filling fluid pressure in these three areas also remains consistent.

[0050] See Figure 1In some embodiments of this invention, the differential pressure sensor further includes two isolation membranes 6, which are respectively disposed at both ends of the axial direction of the housing 1. Each isolation membrane 6 has a corrugated structure. Obviously, the structure of this isolation membrane 6 can be adjusted by those skilled in the art according to actual conditions. The side of the isolation membrane 6 facing away from the sensor is used to contact the measured medium, so that the pressure of the measured medium is transmitted through the isolation membrane 6 to the other side of the isolation membrane 6, and then further transmitted through the filling liquid in the liquid channel 11 to the filling liquid in the gap 3 and the filling liquid in the through hole 2140 in the ceramic core 214. The latter filling liquid further transmits the pressure of the measured medium to the fixed electrode plate 213.

[0051] See Figure 1 and Figure 2 In some embodiments of this utility model, the outer shell 1 has two liquid guiding channels 11 that are arranged through it along its axial direction. One end of each liquid guiding channel 11 is arranged opposite to a separation membrane 6, and the other end is arranged opposite to a ceramic core 214 and is connected to the through hole 2140 of the ceramic core 214. Specifically, the test medium transmits pressure to the isolation membrane 6. The filling liquid on the side of the isolation membrane 6 away from the test medium transmits pressure to the filling liquid in the liquid channel 11, and further transmits pressure to the filling liquid in the gap 3 and the filling liquid in the through hole 2140 in the ceramic core 214. The filling liquid in the through hole 2140 of the ceramic core 214 transmits the pressure of the test medium to the fixed electrode plate 213. One fixed electrode plate 213 is connected to the high pressure chamber 2131, and the other fixed electrode plate 213 is connected to the low pressure chamber 2132. The pressure of the filling liquid in the through hole 2140 of one ceramic core 214 is transmitted to the high pressure chamber 2131, and the pressure of the filling liquid in the through hole 2140 of the other ceramic core 214 is transmitted to the low pressure chamber 2132.

[0052] See Figure 1 and Figure 2 In some embodiments of this utility model, the differential pressure sensor further includes two insulators 7 and two lead-out electrodes 8; both insulators 7 penetrate the outer shell 1, one end of each insulator 7 faces the sensitive element 2, and the other end faces away from the sensitive element 2; each lead-out electrode 8 penetrates one insulator 7, one end of each lead-out electrode 8 is connected to one of the fixed electrode plates 213, and the other end is connected to the demodulation module of the differential pressure sensor.

[0053] See Figure 1In some embodiments of this utility model, each insulator 7 includes: a metal body 71, which is welded and fixed to the outer shell 1; an insulating layer 72, which penetrates the metal body 71; and a metal tube 73, which penetrates the insulating layer 72. Each lead-out electrode 8 is connected to a fixed electrode plate 213 and the demodulation module of the differential pressure sensor via the metal tube 73 of one of the insulators 7.

[0054] See Figure 1 and Figure 2 The core design concept of the immersion metal capacitive sensor provided by this utility model is as follows: a gap 3 is left between the inner wall of the outer shell 1 and the outer surface of the sensitive element 2 containing the measuring diaphragm (i.e., the fixed electrode 213 and the common electrode 22 mentioned above). This gap is used to fill the filling liquid. By utilizing the incompressible properties of the liquid filling liquid and its ability to uniformly transmit external force in all directions, the impact of external force and static pressure on the sensitive element 2 is reduced as much as possible. In other words, the filling liquid is used as a transition buffer medium to protect the sensitive element 2. In existing technologies, the sensitive element 2 and the inner wall of the outer shell 1 are almost perfectly sealed, with a large area of ​​rigid contact between them. This large-area rigid connection transmits all external force impacts and static pressure effects on the outer shell 1 to the sensitive element 2 without reservation. This causes the sensitive element 2 and its internal measuring diaphragm to be severely affected by external force impacts and static pressure, resulting in the measurement results of existing sensors being greatly affected by static pressure fluctuations, leading to poor reliability and accuracy. In contrast, the immersion design provided by this invention makes good use of the incompressible properties of the filling fluid and its ability to uniformly transmit pressure in all directions, significantly reducing the impact of external force and static pressure on the sensitive element 2, thereby obtaining measurement results with high accuracy and good reliability.

[0055] See Figure 1 and Figure 2 The housing 1 of the immersion metal capacitive sensor can be made of rigid material, especially rigid metal material, and the metal body 71 of the insulator 7 can be sealed and fixed to the housing 1 by welding.

[0056] See Figure 1 The two fixed plates 213 have a certain curvature and are curved structures, which is a practice and principle known to those skilled in the art.

[0057] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims. Furthermore, specific examples have been used in the specification to illustrate the principles and implementation methods of this utility model. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model, and the content of this specification should not be construed as a limitation of this utility model.

Claims

1. An immersion-type metal capacitive differential pressure sensor, characterized in that, The differential pressure sensor includes: The outer shell (1) encloses the receiving cavity (10); The sensitive element (2) is housed in the accommodating cavity (10), and there is a gap (3) between the sensitive element (2) and the inner wall surface of the outer shell (1). The cavity (10) and the slit (3) are both used to contain the filling liquid so that the static pressure is uniformly transmitted to the sensitive element (2) through the filling liquid, thereby making the sensitive element (2) in a static pressure balance state.

2. The differential pressure sensor according to claim 1, characterized in that, The sensitive element (2) is fixedly connected to the inner wall of the outer casing (1) via a welding lip (4); And / or, a clamping boss (5) or clamping protrusion is provided between the sensitive element (2) and the inner wall surface of the housing (1) to clamp the sensitive element (2) and the inner wall surface of the housing (1) for fixation.

3. The differential pressure sensor according to claim 2, characterized in that, The sensitive element (2) is cylindrical and has two circular end faces in its axial direction, with the outer peripheral surface of the sensitive element (2) between the two end faces.

4. The differential pressure sensor according to claim 3, characterized in that, The welding lip (4) is provided on at least one end face of the sensitive element (2); And / or, the welding lip (4) is provided on the outer peripheral surface of the sensitive element (2).

5. The differential pressure sensor according to claim 3, characterized in that, It has at least one of the following characteristics: The clamping boss (5) or clamping protrusion is provided on at least one end face of the sensitive element (2); The clamping boss (5) or clamping protrusion is provided on the outer peripheral surface of the sensitive element (2); The clamping boss (5) or clamping protrusion is provided on the inner wall surface of the outer shell (1) and abuts against at least one end face of the sensitive element (2) and clamps the sensitive element (2). The clamping boss (5) or clamping protrusion is provided on the inner wall surface of the outer shell (1) and abuts against and clamps the outer peripheral surface of the sensitive element (2).

6. The differential pressure sensor according to claim 3, characterized in that, The sensitive element (2) includes: Two curved supports (21) are positioned with their ports facing each other. A common electrode plate (22) is located between the ports of the two curved seats (21).

7. The differential pressure sensor according to claim 6, characterized in that, Each of the aforementioned curved surface seats (21) includes: The base (211) is cup-shaped or bowl-shaped and is housed in the curved seat (21), with the cup-shaped or bowl-shaped port of the base (211) facing away from the curved seat (21). An insulating substrate (212) has a curved structure at one end and is housed in the base (211). The curved end of the insulating substrate (212) is located at the cup-shaped port or bowl-shaped port of the base (211). A fixed electrode plate (213) is disposed on the curved surface of the insulating substrate (212); The common electrode plate (22) is located between the fixed electrode plates (213) of the two curved seats (21).

8. The differential pressure sensor according to claim 7, characterized in that, One of the curved bases (21) has a fixed electrode plate (213) and a common electrode plate (22) together forming a high-pressure chamber (2131), and the other curved base (21) has a fixed electrode plate (213) and a common electrode plate (22) together forming a low-pressure chamber (2132). The high-pressure chamber (2131) and the low-pressure chamber (2132) are not connected to each other, and both the high-pressure chamber (2131) and the low-pressure chamber (2132) are used to contain filling fluid.

9. The differential pressure sensor according to claim 8, characterized in that, Each of the curved seat (21) also includes a ceramic core (214) having a through hole (2140). The ceramic core (214) in each of the curved seats (21) passes through the base (211) and the insulating substrate (212) in the curved seat (21).

10. The differential pressure sensor according to claim 9, characterized in that, The accommodating cavity (10) is divided into a first accommodating cavity (101) and a second accommodating cavity (102) that are not connected to each other by the welding lip (4). Both of the fixed electrode plates (213) are provided with through holes so that the through hole (2140), the first accommodating cavity (101), and the high-pressure cavity (2131) of one ceramic core (214) are interconnected, and the through hole (2140), the second accommodating cavity (102), and the low-pressure cavity (2132) of the other ceramic core (214) are interconnected.

11. The differential pressure sensor according to claim 10, characterized in that, The differential pressure sensor also includes two isolation membranes (6), which are respectively disposed at both ends of the housing (1) along the axial direction. The isolation membranes (6) have a corrugated structure.

12. The differential pressure sensor according to claim 11, characterized in that, The outer shell (1) has two liquid guiding channels (11) that extend through it along its axial direction. One end of each liquid guiding channel (11) is directly opposite to one of the isolation membranes (6), and the other end is directly opposite to one of the ceramic cores (214) and connected to the through hole (2140) of the ceramic core (214).

13. The differential pressure sensor according to claim 12, characterized in that, The differential pressure sensor also includes two insulators (7) and two lead-out electrodes (8). Both insulators (7) penetrate the outer shell (1), with one end of each insulator (7) facing the sensitive element (2) and the other end facing away from the sensitive element (2); Each of the lead-out electrodes (8) passes through an insulator (7), and one end of each lead-out electrode (8) is connected to a fixed electrode plate (213), and the other end is connected to the demodulation module of the differential pressure sensor.

14. The differential pressure sensor according to claim 13, characterized in that, Each of the insulators (7) includes: The metal body (71) is welded and fixed to the outer shell (1); An insulating layer (72) penetrates the metal body (71); A metal tube (73) penetrates the insulating layer (72); Each of the lead-out electrodes (8) is connected to a fixed electrode plate (213) and the demodulation module of the differential pressure sensor via a metal tube (73) of an insulator (7).

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