Non-magnetic-loss ceramic composite structure flowmeter

Abstract

The invention relates to the technical field of flow measurement, and discloses a non-magnetic-loss type ceramic composite structure flowmeter which comprises a flange, a shell, a magnet exciting coil and a composite measuring tube, and the composite measuring tube is composed of an integrally-formed ceramic guide tube and a sintering electrode integrally sintered with the ceramic guide tube. A carbon fiber coating structure is compounded on the outer wall of the ceramic conduit to enhance the mechanical strength; the shell is designed to be of a windowing or segmented structure in a magnetic field covering area of the excitation coil, lossless transmission of a magnetic circuit is jointly achieved through the shell and the nonmetal composite measuring pipe, the sintering electrode is in a cone frustum shape, self-locking is achieved through fluid pressure, the inner surface of the sintering electrode is flush with the pipe wall, and it is guaranteed that a flow field is stable while the high-pressure sealing problem is solved. Through the collaborative design of the non-magnetic-loss structure, the composite reinforced pipe body and the integrated self-locking electrode, the measuring precision, the structural reliability and the environmental adaptability of the flowmeter are remarkably improved, and the flowmeter can be suitable for high-temperature, high-pressure and other harsh occasions.

Description

Technical Field

[0001] This invention relates to the field of flow measurement technology, specifically to a non-magnetic loss ceramic composite structure flow meter. Background Technology

[0002] Electromagnetic flow meters are widely used instruments in the industrial field. Their working principle strictly follows Faraday's law of electromagnetic induction, accurately calculating the volumetric flow rate of the liquid by measuring the induced electromotive force generated by a conductive liquid flowing in a magnetic field. Traditionally, a complete electromagnetic flow meter consists of two parts: a sensor and a converter. The sensor is the core component that directly contacts the liquid being measured; its function is to convert the flow velocity signal into a weak induced electromotive force signal through electromagnetic induction. The converter is responsible for receiving this signal, amplifying it, processing it, and converting it into a standard industrial signal output. This invention mainly focuses on improving and innovating the technical solution of the sensor component.

[0003] In existing technical solutions, the typical structure of an electromagnetic flowmeter sensor usually includes a measuring tube, electrodes, an excitation coil, a lining, and a housing. The measuring tube is generally made of non-magnetic stainless steel or other round metal tubing, or rolled from sheet metal. The electrodes are often made of stainless steel or other corrosion-resistant alloys. The lining is mostly made of polytetrafluoroethylene (PTFE) or rubber, providing electrical insulation and corrosion protection for the inner wall of the pipe. The housing is often formed by metal welding to protect the internal components. Some designs, aiming for higher wear and corrosion resistance, use ceramic as the lining. However, this method of combining a ceramic tube with a metal measuring tube via a heat-shrink process is not only costly to manufacture, but also makes the ceramic material extremely susceptible to damage during installation and transportation due to its inherent brittleness.

[0004] However, these conventional technical solutions have revealed a series of inherent defects in practical applications, severely restricting further improvements in the measurement accuracy and reliability of electromagnetic flowmeters. A core problem lies in the enormous losses in the magnetic circuit. Although the measuring tube uses so-called "non-magnetic" metal, as a metallic material, it still absorbs and interferes with the magnetic field, causing distortion of the magnetic field lines. This results in a severe deficiency in the effective magnetic flux penetrating the measured fluid, with the magnetic flux utilization rate often below 30%. This fundamentally weakens the strength of the original induced signal and affects the measurement accuracy.

[0005] Meanwhile, the structural stability and internal flow field smoothness of the flowmeter also face challenges. During pipeline installation, the stress generated at the flange connection can easily be transmitted to the metal measuring tube, causing slight elliptical deformation and compromising the geometric accuracy of the measuring section. Furthermore, due to manufacturing tolerances in industrial pipelines, their inner diameter dimensions are difficult to guarantee with high precision. In addition, traditional assembled electrodes typically extend partially into the pipeline. These factors combined make it highly susceptible to localized flow field disturbances and abrupt changes when the measured medium flows within the pipeline, thus introducing measurement errors.

[0006] The product also suffers from significant drawbacks in terms of durability and environmental adaptability. Particularly in ceramic-lined structures, the substantial difference in thermal expansion coefficients between the metal pipe and the ceramic material causes significant thermal stress at the interface when the flow meter experiences temperature fluctuations. Over time, this can easily lead to cracking of the ceramic lining, shortening the product's lifespan. Furthermore, the sealing of traditional assembled electrodes remains a long-standing technical challenge. Sealing structures relying on O-rings or gaskets are prone to loosening and fatigue under continuous fluid pressure within the pipe, leading to seal failure and media leakage. This makes them particularly unsuitable for measuring high-pressure media.

[0007] While existing technologies have attempted to improve sealing performance by using methods such as secondary sintering to fabricate electrodes and ceramic conduits, this step-by-step sintering process often fails to achieve the density and bonding strength of integrated sintering. Furthermore, the difference in thermal expansion between the metal and ceramic during sintering remains a potential risk of thermal cracking. In addition, the pure ceramic measuring tubes obtained through these solutions do not fundamentally solve the problems of low mechanical strength, fragility, and installation difficulties. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a non-magnetic-loss ceramic composite flow meter, which solves the problems of high magnetic circuit loss, limited measurement accuracy, low structural strength of the measuring tube, and poor electrode sealing reliability in existing electromagnetic flow meters.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a non-magnetic loss ceramic composite flow meter, comprising: Flange; The housing is connected to the flange; The excitation coil is disposed inside the housing; A composite measuring tube is positioned within the magnetic field range of the excitation coil; The composite measuring tube includes an integrally formed ceramic conduit and a sintered electrode integrated with the ceramic conduit through a sintering process. The housing has a windowed or segmented structure in the magnetic field coverage area of ​​the excitation coil, so that the composite measuring tube is not covered by any metal parts in this area.

[0010] Preferably, the composite measuring tube further includes a carbon fiber coating structure, which is a reinforcing layer formed by roughening the outer surface of the ceramic conduit, coating it with an adhesive, and then winding carbon fiber material around it.

[0011] Preferably, the carbon fiber material is cross-wound along the axial direction of the ceramic conduit at an angle of ±45°.

[0012] Preferably, the sintered electrode is frustoconical in shape, with its large end facing the inner wall of the ceramic conduit, and the inner surface of the sintered electrode is flush with the inner wall of the ceramic conduit.

[0013] Preferably, the inner wall of the hole on the ceramic conduit for accommodating the sintered electrode is engraved with a circumferential groove.

[0014] Preferably, it further includes an extraction structure for extracting signals from the sintered electrode, the extraction structure including conductive silver paste filled in a borehole in the outer wall of the ceramic conduit, a conductive copper pillar electrically connected to the conductive silver paste, and a fastening screw for clamping the signal line.

[0015] Preferably, the outer edge of the flange is integrally connected with radial reinforcing ribs.

[0016] Preferably, the excitation coil is an arc-shaped coil made of self-adhesive wire and is vacuum-cast and encapsulated with high-temperature resistant resin.

[0017] Preferably, an insulating gasket is provided between the excitation coil and the composite measuring tube.

[0018] Preferably, the ceramic conduit is an alumina ceramic conduit, and the sintered electrode is a platinum-iridium alloy electrode.

[0019] Working Principle: When the flow meter is powered on, its excitation coil generates a stable magnetic field perpendicular to the fluid flow direction around the composite measuring tube. The conductive liquid being measured, acting as a moving conductor, cuts the magnetic field lines as it flows through this magnetic field, thus generating an induced electromotive force (EMF) proportional to the average flow velocity within the liquid. This magnetic field achieves zero magnetic loss when penetrating the tube wall and acting on the liquid. The composite measuring tube is composed of a non-magnetic ceramic conduit and a carbon fiber-clad structure, with an open window design in the magnetic field region of the outer casing. This ensures that the magnetic field lines are not obstructed or lost by any metal components along their transmission path, guaranteeing that the magnetic field acts on the liquid without attenuation or distortion, thereby obtaining a stronger and more accurate induced signal. The induced EMF is generated by a pair of sintered cores integrally formed with the ceramic conduit. The electrodes perform precise data acquisition. Because the inner surface of the electrodes is completely flush with the inner wall of the pipe, any disturbance to the flow field is avoided, ensuring the stability of signal acquisition. The acquired signal is then stably transmitted to the outside through a three-stage lead-out structure consisting of conductive silver paste, conductive copper pillars, and fastening screws. This lead-out structure is sealed with resin to effectively isolate interference from the external environment, ensuring signal integrity and zero-point stability. Finally, the signal is sent to the converter, which amplifies, processes, and calculates the signal based on the proportional relationship between the induced electromotive force and the flow velocity, accurately converting it into the volumetric flow rate of the fluid, and outputting it as a standard industrial signal.

[0020] This invention provides a non-magnetic-loss ceramic composite flow meter. It has the following beneficial effects: 1. This invention uses a non-metallic composite measuring tube composed of a ceramic conduit and a carbon fiber coated structure, and a housing with an open or segmented design in the magnetic field coverage area of ​​the excitation coil. This completely eliminates magnetic circuit loss and magnetic field distortion caused by metal components, resulting in a significant increase in magnetic flux utilization and a stronger and more stable sensing signal. This significantly improves the measurement accuracy of the flow meter and its response sensitivity to weak flow rates.

[0021] 2. This invention greatly enhances the overall mechanical strength and structural stability of the product by winding a carbon fiber-coated structure around the outer surface of the ceramic conduit and combining it with radial reinforcing ribs on the flange. The carbon fiber composite layer effectively solves the problem of the fragility of ceramic materials and improves the impact resistance and thermal shock resistance. The reinforcing ribs can disperse the installation stress of the pipeline and prevent the measuring tube from deforming under stress, thus ensuring the long-term reliable operation of the flow meter under high temperature, high pressure and complex working conditions.

[0022] 3. This invention fundamentally solves the sealing failure and leakage problems of traditional assembled electrodes by adopting a structure in which a sintered electrode in the shape of a truncated cone and a ceramic conduit are sintered together. The conical structure can generate a self-locking effect under high pressure, enabling the product to be stably applied to high-pressure media. At the same time, the smooth transition between the inner surface of the electrode and the tube wall ensures a stable and undisturbed flow field. Combined with the electrode lead-out structure that is completely sealed by resin, it effectively ensures the stability of signal acquisition and transmission and prevents zero-point drift. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the main structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the present invention; Figure 3 This is a schematic diagram of the excitation coil structure of the present invention; Figure 4 This is a schematic diagram of the composite measuring tube structure of the present invention; Figure 5 This is a schematic diagram of the electrode signal extraction structure of the present invention.

[0024] Among them, 1. Converter; 2. Flange; 3. Housing; 4. Composite measuring tube; 4-1: Ceramic conduit; 4-2: Carbon fiber coated structure; 4-3: Conductive copper pillar; 4-4: Fastening screw; 4-5: Sintered electrode; 5. Excitation coil; 5-1: Arc-shaped coil; 5-2: High temperature resin. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example: Please see the appendix Figure 1 - Appendix Figure 5 This invention provides a non-magnetic loss ceramic composite flow meter, comprising: Flange 2; The housing 3 is connected to the flange 2; The excitation coil 5 is located inside the housing 3; The composite measuring tube 4 is positioned within the magnetic field range of the excitation coil 5; The composite measuring tube 4 includes an integrally formed ceramic conduit 4-1 and a sintered electrode 4-5 integrated with the ceramic conduit 4-1 through a sintering process. Among them, the housing 3 has an open window or segmented structure in the magnetic field coverage area of ​​the excitation coil 5, so that the composite measuring tube 4 has no metal parts covering this area.

[0027] In this embodiment, the non-magnetic loss ceramic composite flow meter includes a flange 2 as a pipe connection component and a housing 3 that provides installation space and external protection for the internal core components. The flange 2 and housing 3 are preferably fixed together by laser welding or other methods to form a robust external frame.

[0028] In the region corresponding to the magnetic field of the excitation coil 5, the housing 3 is specially designed as a discontinuous structure with windows or segments. This means that the magnetic field lines generated by the excitation coil 5 will not encounter any magnetic or conductive metal parts on their path through the composite measuring tube 4, thus ensuring that the magnetic field can act on the measured fluid without attenuation or distortion, laying the foundation for high-precision flow measurement.

[0029] The outer edge of flange 2 is integrally connected with multiple sets of radial reinforcing ribs. This reinforcing rib design effectively disperses and resists installation stress from the external piping system and vibrations during operation, preventing stress transmission from causing deformation of the core measuring component, the composite measuring tube 4, thus ensuring the flowmeter's measurement accuracy during long-term use. The main body of the composite measuring tube 4 is a high-purity alumina ceramic conduit 4-1 formed by isostatic pressing, with a smooth inner wall and excellent wear and corrosion resistance. This invention incorporates a carbon fiber coating structure 4-2 on the outside of the ceramic conduit 4-1.

[0030] First, the outer surface of the ceramic conduit 4-1 is roughened by sandblasting to significantly increase its surface area and roughness, providing an excellent physical basis for subsequent bonding. Next, a layer of high-temperature resistant polyimide adhesive is uniformly coated on its surface; Then, high-performance carbon fiber prepreg is used, preferably cross-wound at an angle of ±45° along the axial direction of the ceramic conduit 4-1, and finally cured by hot pressing to form a reinforcing layer. The directionally wound carbon fiber coating structure greatly improves the bending strength, impact toughness and thermal shock resistance of the composite measuring tube, enabling it to adapt to harsh industrial environments.

[0031] The integrated assembly of the sintered electrode 4-5 and the ceramic conduit 4-1 is another core technology of this invention. Instead of traditional post-assembly, it employs powder metallurgy technology, pre-placing metal powders such as platinum-iridium alloy within the blank of the ceramic conduit 4-1. Through a one-time gradient sintering process, a completely dense metallurgical bond is formed between the metal and the ceramic. The sintered electrode 4-5 is specially designed in a frustum-shaped cone, with its larger end facing the inner wall of the ceramic conduit 4-1 and its smaller end facing the outer wall. When the fluid inside the conduit generates pressure, this pressure acts on the larger end face of the electrode, generating a radial self-locking force on the conical structure. This ensures that the higher the fluid pressure, the tighter the engagement between the electrode and the ceramic tube, fundamentally eliminating the risk of the electrode loosening or detaching under high pressure.

[0032] Preferably, circumferential grooves are engraved on the inner wall of the hole in the ceramic conduit 4-1 used to accommodate the sintered electrode 4-5, further increasing the mechanical interlocking force. After sintering, through precision machining, the inner surface of the sintered electrode 4-5 is made completely flush with the inner wall of the ceramic conduit 4-1, forming a smooth and continuous inner cavity. This design eliminates any protrusions or depressions that may cause fluid disturbance, ensuring the stability of the flow field of the measured medium, which is key to improving measurement accuracy. Precision drilling is performed on the outside of the ceramic conduit 4-1 at the position corresponding to the sintered electrode 4-5 to expose its metal substrate; Then, conductive silver paste is filled into the hole, and a conductive copper post 4-3 is pressed in to achieve a low-resistance electrical connection. Finally, the external signal line is firmly pressed onto the conductive copper post 4-3 using fastening screws 4-4. The entire lead-out structure area is finally filled and sealed with insulating materials such as epoxy resin, effectively isolating it from interference from environmental factors such as external moisture and temperature changes, ensuring long-term stable signal transmission, and preventing zero-point drift.

[0033] The excitation coil 5 serves as the source of the magnetic field. It is wound with self-adhesive wire into an arc-shaped coil saddle that matches the outer wall of the composite measuring tube 4 to ensure the uniformity of the magnetic field. After winding, it is encapsulated using a vacuum casting process with a high-temperature resistant resin such as polyphenylene sulfide.

[0034] It not only ensures a precise fit between the coil and the measuring tube, guaranteeing geometric accuracy, but also provides excellent insulation, waterproofing, and heat dissipation.

[0035] Preferably, an insulating gasket made of alumina ceramic or similar material is placed between the excitation coil 5 and the composite measuring tube 4 to further prevent heat conduction from the high-temperature medium to the coil through the tube wall, ensuring the normal operation and service life of the coil under high-temperature conditions. During operation, the excitation coil 5 generates a stable magnetic field, which penetrates the composite measuring tube 4 without loss and acts on the conductive liquid inside. The liquid flow cuts the magnetic field lines, generating an induced electromotive force proportional to the flow velocity. This electromotive force is precisely collected by the integrally sintered electrode 4-5 and transmitted to the external converter 1 through a stable lead-out structure, ultimately being converted into a standard flow signal.

[0036] Please see the appendix Figure 4 and attached Figure 5 The composite measuring tube 4 also includes a carbon fiber coated structure 4-2, which is a reinforcing layer formed by roughening the outer surface of the ceramic conduit 4-1, coating it with an adhesive, and then winding carbon fiber material around it. The carbon fiber material is cross-wound along the axial direction of the ceramic conduit 4-1 at an angle of ±45°. The sintered electrode 4-5 is frustoconical, with its large end facing the inner wall of the ceramic conduit 4-1, and its inner surface is flush with the inner wall of the ceramic conduit 4-1. Circumferential grooves are engraved on the inner wall of the hole on the ceramic conduit 4-1 used to accommodate the sintered electrode 4-5.

[0037] In this embodiment, firstly, to fundamentally improve the inherent defects of the ceramic conduit 4-1, such as high brittleness and weak impact resistance, the present invention introduces a carbon fiber coated structure 4-2 as a reinforcing layer. The formation process of this structure is rigorous and precise: The first step is to roughen the outer surface of the ceramic conduit 4-1, for example, by using a sandblasting process. The purpose of this is to disrupt the smoothness of the ceramic surface and create a microscopic uneven structure, thereby greatly increasing its specific surface area and providing an excellent mechanical locking basis for the subsequent adhesion of the adhesive.

[0038] The second step involves uniformly coating a high-performance adhesive onto the roughened outer surface of the ceramic conduit 4-1. This adhesive serves as a crucial transition layer, achieving a strong chemical and physical bond with the ceramic surface while simultaneously ensuring thorough wetting and cross-linking with the resin matrix of the subsequently wound carbon fiber composite material. Preferably, a high-temperature resistant polyimide or similar adhesive is used to ensure stable bonding performance within the wide temperature range of the flowmeter's operation, effectively buffering interfacial stress arising from the difference in thermal expansion coefficients between the ceramic and carbon fiber layers.

[0039] The third step involves using high-performance carbon fiber material, which is then wrapped around the outside of the ceramic conduit 4-1 coated with adhesive through an automated winding process. A key technical aspect of this solution is that the carbon fiber material is cross-wound along the axial direction of the ceramic conduit 4-1 at an angle of ±45°.

[0040] The purpose of this design is that the ±45° layup angle can create a quasi-isotropic mechanical property in the tube structure, which can effectively resist axial tension, bending and shear stress from torsion of the tube, thereby comprehensively improving the overall mechanical strength and structural rigidity of the composite measuring tube, and enabling it to effectively resist pipeline installation stress and external impact vibration.

[0041] In terms of electrode structure design, this invention also incorporates profound innovations to improve its sealing reliability and measurement performance. The sintered electrode 4-5 is specially designed as a frustum conical shape, with its large end facing the inner wall of the ceramic conduit 4-1, i.e., the fluid side, and its small end facing the outer wall.

[0042] This structure creates a clever self-locking mechanism: When the fluid in the pipe generates pressure, the pressure acts uniformly on the large end face inside the electrode, forming an outward thrust. Due to the presence of the conical surface, this axial thrust is decomposed into a normal pressure perpendicular to the conical surface. This pressure increases the contact normal pressure and friction between the electrode and the conical hole wall of the ceramic conduit.

[0043] Therefore, the higher the fluid pressure, the tighter the electrode is locked, thus achieving a highly reliable physical seal under high pressure conditions and completely avoiding the risk of traditional electrodes being pushed out under high pressure.

[0044] To further enhance the bonding force between the electrode and the ceramic conduit, the present invention pre-machines circumferential grooves on the inner wall of the hole in the ceramic conduit 4-1 for accommodating the sintered electrode 4-5. During integrated sintering, the molten or semi-molten metal electrode powder fills these circumferential grooves.

[0045] After cooling and solidification, the metal filling the groove forms a solid mechanical interlock, greatly enhancing the electrode's resistance to axial pull and torsion, providing double protection for the permanent, integrated bonding of the electrode and the ceramic conduit. Furthermore, to ensure the highest measurement accuracy, the inner surface of the sintered electrode 4-5 is precisely flush with the inner wall of the ceramic conduit 4-1 after sintering and processing, together forming a complete and smooth inner cavity.

[0046] Please see the appendix Figure 3 - Appendix Figure 5It also includes an output structure for extracting signals from the sintered electrode 4-5. The output structure includes conductive silver paste filled in a drilled hole in the outer wall of the ceramic conduit 4-1, a conductive copper pillar 4-3 electrically connected to the conductive silver paste, and a fastening screw 4-4 for clamping the signal line. Radial reinforcing ribs are integrally connected to the outer edge of the flange 2. The excitation coil 5 is an arc-shaped coil wound with self-adhesive wire and vacuum-cast and encapsulated with high-temperature resistant resin 5-2. A heat-insulating gasket is provided between the excitation coil 5 and the composite measuring tube 4. The ceramic conduit 4-1 is an alumina ceramic conduit, and the sintered electrode 4-5 is a platinum-iridium alloy electrode.

[0047] In this embodiment, a precision hole is drilled on the outside of the ceramic conduit 4-1 at the position corresponding to the sintered electrode 4-5, and the hole is filled with conductive silver paste.

[0048] Conductive silver paste possesses excellent conductivity and filling properties, enabling it to form a large-area, low-resistance flexible electrical connection with the metal substrate of the sintered electrode. The second stage of the lead-out structure involves pressing a conductive copper pillar 4-3 into the hole filled with conductive silver paste, ensuring tight contact between it and the paste. This conductive copper pillar acts as a robust intermediate conductor, stably guiding weak electrical signals from the ceramic interior to the exterior. The third stage of the lead-out structure uses a fastening screw 4-4 to firmly press the terminals of the external signal line onto the conductive copper pillar 4-3, forming a reliable mechanical electrical connection and effectively avoiding the risk of poor soldering or detachment. After the entire lead-out structure is connected, its cavity is locally sealed with insulating materials such as epoxy resin, completely isolating the connection point from external moisture, dust, and corrosive gases, ensuring long-term stability of signal transmission.

[0049] In terms of structural strength and installation reliability, the outer edge of flange 2 is designed with multiple sets of radial reinforcing ribs.

[0050] The purpose is that when the flow meter is bolted to the field pipeline via a flange, these reinforcing ribs can greatly improve the bending and torsional stiffness of the flange, effectively disperse and resist the stress caused by pipeline misalignment or uneven tightening force, prevent the stress from being transmitted to the core composite measuring tube 4-4, avoid deformation or damage to it, and thus ensure that the measurement accuracy is not affected by the installation.

[0051] In terms of the magnetic field system, the stability and protection performance of the Lijia coil 5, as the source of the working magnetic field, are of paramount importance.

[0052] In this embodiment, the Lijia coil 5 is preferably wound with self-adhesive wire to form an arc-shaped coil that matches the outer contour of the composite measuring tube 4, ensuring the uniformity of the magnetic field distribution. After winding, a vacuum casting process is used to encapsulate it entirely with high-temperature resistant resin 5-2. The vacuum environment ensures that the resin completely fills the gaps in the coil windings without any air bubbles remaining. The cured resin forms a dense and robust whole, protecting the excitation coil 5 from high temperatures. In this invention, a heat-insulating gasket is provided between the excitation coil 5 and the composite measuring tube 4. The heat-insulating gasket is preferably made of alumina ceramic or other low thermal conductivity materials. Its function is to establish a thermal barrier between the high-temperature fluid and the excitation coil, effectively blocking the conduction of heat from the tube wall to the coil, ensuring that the operating temperature of the excitation coil is maintained within a safe range, and preventing the coil insulation from aging or resistance change due to overheating. This ensures the measurement accuracy and service life of the flow meter under high-temperature conditions.

[0053] The ceramic conduit 4-1 is preferably a high-purity alumina ceramic conduit, which is known for its extremely high hardness, excellent wear resistance and corrosion resistance to most chemical media.

[0054] The sintered electrodes 4-5 are preferably platinum-iridium alloy electrodes. The choice of this alloy material is not only due to its excellent corrosion resistance, which can resist the erosion of various strong acid and alkali media, but more importantly, its coefficient of thermal expansion is highly matched with that of alumina ceramic.

[0055] This matching effectively reduces the internal stress generated at the interface between the electrode and the ceramic due to inconsistent thermal expansion and contraction during the sintering cooling process and subsequent temperature cycling, fundamentally preventing microcracks or peeling at the interface and ensuring the long-term reliability of the integrated structure of the electrode and the tube.

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A non-magnetic loss ceramic composite structure flowmeter characterized by, It comprises: a flange (2); a shell (3) connected with the flange (2); an excitation coil (5) arranged inside the shell (3); a composite measuring tube (4) arranged in the magnetic field range of the excitation coil (5); the composite measuring tube (4) comprises a ceramic guide tube (4-1) and a sintered electrode (4-5) integrated with the ceramic guide tube (4-1); wherein the shell (3) is in a windowed or segmented structure in the magnetic field coverage area of the excitation coil (5), so that the composite measuring tube (4) is not covered by metal parts in this area.

2. A non-magnetic loss ceramic composite structure flowmeter according to claim 1, characterized in that, The composite measuring tube (4) further comprises a carbon fiber cladding structure (4-2), which is a reinforcing layer formed by roughening the outer surface of the ceramic guide tube (4-1), coating adhesive, and then winding carbon fiber material.

3. A non-magnetic loss ceramic composite flowmeter according to claim 2, wherein The carbon fiber material is cross-wound at an angle of ±45° along the axial direction of the ceramic guide tube (4-1).

4. The non-magnetic loss ceramic composite flow meter of claim 1, wherein, The sintered electrode (4-5) is in the shape of a truncated cone, with the large end facing the inner wall of the ceramic guide tube (4-1), and the inner surface of the sintered electrode (4-5) is flush with the inner wall of the ceramic guide tube (4-1).

5. A non-magnetic loss ceramic composite flowmeter according to claim 4, wherein The inner wall of the hole on the ceramic guide tube (4-1) for accommodating the sintered electrode (4-5) is engraved with a circumferential groove.

6. A non-magnetic loss ceramic composite flowmeter according to claim 1, wherein It also includes a lead-out structure for leading out signals from the sintered electrode (4-5), which includes conductive silver paste filled in the hole drilled on the outer wall of the ceramic guide tube (4-1), conductive copper columns (4-3) electrically connected with the conductive silver paste, and fastening screws (4-4) for compressing signal lines.

7. A non-magnetic loss ceramic composite flowmeter according to claim 1, wherein The outer edge of the flange (2) is integrally connected with a radial reinforcing rib.

8. The non-magnetic loss ceramic composite flow meter of claim 1, wherein, The excitation coil (5) is a circular arc type coil wound with self-adhesive wire, and is packaged by vacuum casting with high temperature resistant resin (5-2).

9. A non-magnetic loss ceramic composite flowmeter according to claim 8, wherein, An insulating gasket is arranged between the excitation coil (5) and the composite measuring tube (4).

10. The non-magnetic loss ceramic composite structure flow meter of claim 1, wherein, The ceramic guide tube (4-1) is an alumina ceramic guide tube, and the sintered electrode (4-5) is a platinum-iridium alloy electrode.

Images