High-pressure corrosion-resistant alloy diaphragm of pressure transmitter

Abstract

The invention discloses a pressure transmitter high-pressure corrosion-resistant alloy diaphragm, and relates to the technical field of alloy diaphragms.The pressure transmitter high-pressure corrosion-resistant alloy diaphragm comprises a diaphragm body, the front face of the diaphragm body is used for making contact with a medium in a pressure transmitter, the back face of the diaphragm body is used for being connected with a sensor rear cover in an assembled mode, and an oil cavity is formed in the sensor rear cover; the edge of the back face of the diaphragm body is welded to the edge of the oil cavity, the thickness of the back face of the diaphragm body is gradually increased from the center to the edge, a plurality of corrugated grooves are formed in the center area of the back face of the diaphragm body, an integrally-formed honeycomb rib plate is arranged at the edge of the back face of the diaphragm body, and the opening end of the honeycomb rib plate is communicated with the oil cavity. At least one fiber bragg grating is embedded in the back surface of the diaphragm body. Through the state that the center is thin and the edge is thick and the arrangement of the corrugated grooves, the sensitivity is improved, the diaphragm body can be monitored in real time through the arrangement of the fiber bragg grating, and the diaphragm can work safely and accurately for a long time under the severe high-pressure corrosion working condition.

Description

Technical Field

[0001] This invention relates to the field of alloy diaphragm technology, and in particular to a high-pressure corrosion-resistant alloy diaphragm for pressure transmitters. Background Technology

[0002] A pressure transmitter is a field measuring instrument that converts the pressure of the measured medium (gas, liquid, or steam) into a standard electrical signal, such as 4–20mA, 0–10V, RS-485, or digital bus signal, and outputs it to the control system or instrument. It contains both a pressure-sensitive element and integrated signal conditioning and amplification circuits, and can be directly installed on pipelines or containers to realize real-time monitoring and remote transmission of process pressure, gauge pressure, absolute pressure, or differential pressure. The transmitter front end relies on a metal diaphragm to transmit the medium pressure to the silicon piezoresistive, capacitive, or resonant sensing element via an oil-filled system. The pressure of the measured medium first acts on the corrosion-resistant alloy isolation diaphragm located at the front end of the transmitter. While the diaphragm undergoes slight elastic deformation, it transmits the pressure to the internal silicon piezoresistive sensing chip through the oil-filled cavity behind it. The chip converts the mechanical strain into a millivolt-level electrical signal, which is amplified, temperature-compensated, and linearized before outputting a 4-20mA or digital bus signal. The alloy diaphragm serves as an isolation barrier between the medium and the electronic components, preventing high pressure, high temperature, or corrosive fluids from directly damaging the chip. Furthermore, its ultra-thin, high-strength structure allows it to accurately and distortion-free "replicate" pressure changes, achieving a balance between measurement safety and accuracy. However, in the existing technology, most of them use 316L stainless steel or Hastelloy flat diaphragms of equal thickness. The thickness usually needs to be ≥80µm to meet the strength requirements of 40MPa or more. However, such a structure has three major shortcomings: (1) The thicker the diaphragm, the smaller the center displacement, which leads to a decrease in sensitivity; (2) High pressure liquid medium impacts the diaphragm, which can easily cause the diaphragm to bulge in the center or the edges to be knocked and rolled up, which will reduce the service life of the pressure transmitter; (3) It is impossible to detect the health status of the diaphragm in advance. Once pitting and perforation occur, it can only rely on passive shutdown and maintenance after leakage. Summary of the Invention

[0003] In view of the aforementioned existing problems, the present invention is proposed.

[0004] The purpose of this invention is to solve the problems of low sensitivity of traditional diaphragms in the prior art, and structural instability or even damage caused by long-term impact from the medium.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: On one hand, the present invention provides a high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter, comprising a diaphragm body, the front side of which is used to contact the internal medium of the pressure transmitter, the back side of which is used to be assembled and connected to a sensor rear cover, the sensor rear cover having an oil cavity, the edge of the back side of the diaphragm body being welded to the edge of the oil cavity, the thickness of the back side of the diaphragm body gradually increasing from the center to the edge, the central area of ​​the back side of the diaphragm body having multiple corrugated grooves, the edge of the back side of the diaphragm body having an integrally formed honeycomb rib, the opening end of the honeycomb rib communicating with the oil cavity, and at least one fiber Bragg grating embedded in the back side of the diaphragm body.

[0006] Furthermore, the outer wall of the diaphragm body is provided with a transition layer, a hard layer, and a corrosion-resistant and wear-resistant layer from the inside out. The diaphragm body is a nickel-based alloy metal with a yield strength ≥700MPa. When the yield strength is ≥700MPa, the diaphragm body can maintain full elasticity under high pressure without permanent bulging or cracking. The transition layer, hard layer, and corrosion-resistant and wear-resistant layer are respectively a deposited Ti layer, a TiN layer, and a diamond-like carbon layer. The Ti layer is used to improve the metallurgical adhesion to the diaphragm body. The TiN layer is used to provide high hardness and low friction, resist particle erosion and scratches, and initially block chloride ion penetration. The diamond-like carbon layer has an ultra-low coefficient of friction and extremely low hydrogen permeability, achieving long-term corrosion protection and wear reduction, and is used to improve surface hardness and chemical inertness.

[0007] Furthermore, the back of the diaphragm body is provided with a central area and an edge area, the corrugated groove is formed in the central area, the honeycomb rib is provided in the edge area, the thickness of the central area is 40–60µm, and the thickness of the edge area is 70–120µm.

[0008] Furthermore, the honeycomb rib plate is configured with a honeycomb structure, the honeycomb rib plate has a honeycomb aperture of 0.3-0.8mm, a wall thickness of 0.05-0.15mm, and a honeycomb height of 0.5-1.5mm.

[0009] Furthermore, the sensor back cover is provided with a feed hole that is sealed and connected to the oil cavity. The oil cavity is used to fill silicone oil. During installation, the edge of the diaphragm body is first welded to the sensor back cover, and then silicone oil is injected into the oil cavity through the feed hole via a pinhole until the silicone oil fills the oil cavity and the honeycomb rib plate. Finally, the feed hole is welded and sealed.

[0010] Furthermore, the center wavelength of the fiber Bragg grating is located at 1526–1560 nm. The fiber Bragg grating communicates with the transmitter motherboard. The outer wall of the fiber Bragg grating is coated with a 5–10 µm protective varnish, which is a polyimide protective varnish. The fiber Bragg grating is used to realize real-time diagnosis of the health status of the diaphragm and early warning of corrosion and fatigue. When the center wavelength drift of the grating exceeds the set threshold, an alarm signal is automatically sent to the control system.

[0011] Furthermore, a wire groove is provided between the honeycomb ribs, and the connection end of the fiber Bragg grating passes through the wire groove and exits from the sensor back cover to be electrically connected to an external power source.

[0012] Furthermore, the outer surface of the membrane body has a roughness Ra≤0.20µm after electrochemical polishing, and a hydrophobic layer is provided in the corrosion-resistant and wear-resistant layer to make the water contact angle ≥120°, so as to reduce liquid residue.

[0013] Furthermore, the corrugation pitch of adjacent corrugated grooves is 300–400µm and the corrugation depth is 200–300µm, in order to improve sensitivity and reduce the maximum stress in the membrane.

[0014] The beneficial effects of this invention are: This invention features a thinner diaphragm body in the middle to improve sensitivity and a thicker periphery to resist high pressure and prevent bulging. Multiple corrugated grooves transform the diaphragm body into a soft spring structure, making pressure changes easier to detect. Honeycomb ribs act like a skeleton to support the surrounding area, resisting impacts and extending service life. Silicone oil is filled into the oil cavity, forming an oil column that can suppress diaphragm bulging under high pressure. The process is simple. A fiber Bragg grating is used to achieve real-time diagnosis of the diaphragm body's health status and early warning of corrosion and fatigue. When the center wavelength drift of the grating exceeds a set threshold, an alarm signal is automatically sent to the control system. Specifically, when the diaphragm body bulges, the optical fiber inside the fiber Bragg grating is stretched or compressed accordingly, and its wavelength changes with the stretching, directly converting the minute strain of the diaphragm body into an optical signal. This achieves high-precision pressure sensing, health status monitoring, and overload warning, unaffected by electromagnetic interference or corrosive environments. The entire transmission uses light, making it resistant to electromagnetic interference and corrosion by the medium. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1A schematic diagram of the assembly of the diaphragm body and the sensor back cover of a high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter provided by the present invention. Figure 2 A cross-sectional view of the assembly of the diaphragm body and the sensor back cover of a high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter provided by the present invention. Figure 3 This invention provides a high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter. Figure 2 Enlarged schematic diagram of the structure at point A in the middle; Figure 4 A cross-sectional view of the diaphragm body of a high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter provided by the present invention; Figure 5 This invention provides a high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter. Figure 4 Enlarged schematic diagram of the structure at point B.

[0017] Legend: 1. Diaphragm body; 2. Sensor back cover; 3. Oil cavity; 4. Corrugated groove; 5. Honeycomb rib; 6. Fiber Bragg grating; 711. Transition layer; 712. Hard layer; 713. Corrosion and wear resistant layer; 8. Feed hole; 9. Wire groove. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0020] Secondly, as used herein, "an embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0021] Please see Figures 1-5This invention provides a technical solution: a high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter, comprising a diaphragm body 1, the front of the diaphragm body 1 for contacting the internal medium of the pressure transmitter, the back of the diaphragm body 1 for assembly and connection with a sensor rear cover 2, an oil cavity 3 on the sensor rear cover 2, the edge of the back of the diaphragm body 1 being welded to the edge of the oil cavity 3, the thickness of the back of the diaphragm body 1 gradually increasing from the center to the edge, a plurality of corrugated grooves 4 being formed in the central area of ​​the back of the diaphragm body 1, an integrally formed honeycomb rib 5 being provided at the edge of the back of the diaphragm body 1, the opening end of the honeycomb rib 5 communicating with the oil cavity 3, and at least one fiber Bragg grating 6 being embedded in the back of the diaphragm body 1.

[0022] like Figures 1-5 As shown, the outer wall of the diaphragm body 1 is provided with a transition layer 711, a hard layer 712, and a corrosion-resistant and wear-resistant layer 713 from the inside to the outside. The diaphragm body 1 is a nickel-based alloy metal with a yield strength ≥700MPa. When the yield strength is ≥700MPa, the diaphragm body 1 can maintain full elasticity under high pressure without permanent bulging or cracking. The transition layer 711, the hard layer 712, and the corrosion-resistant and wear-resistant layer 713 are respectively a deposited Ti layer, a TiN layer, and a diamond-like carbon layer. The Ti layer is used to improve the metallurgical adhesion to the diaphragm body 1. The TiN layer is used to provide high hardness and low friction, resist particle erosion and scratches, and initially block chloride ion penetration. The diamond-like carbon layer has an ultra-low coefficient of friction and extremely low hydrogen permeability, achieving long-term corrosion protection and wear reduction, and is used to improve surface hardness and chemical inertness.

[0023] like Figures 1-5 As shown, the back of the diaphragm body 1 has a central area and an edge area. The corrugated groove 4 is opened in the central area, and the honeycomb rib plate 5 is set in the edge area. The thickness of the central area is 40–60µm, and the thickness of the edge area is 70–120µm.

[0024] like Figures 1-5 As shown, the honeycomb rib plate 5 is configured with a honeycomb structure. The honeycomb pore diameter of the honeycomb rib plate 5 is 0.3-0.8mm, the wall thickness is 0.05-0.15mm, and the honeycomb height is 0.5-1.5mm.

[0025] like Figures 1-5 As shown, the sensor back cover 2 has a feed hole 8 that is sealed and connected to the oil cavity 3. The oil cavity 3 is used to fill silicone oil. During the installation, the edge of the diaphragm body 1 is first welded to the sensor back cover 2, and then silicone oil is injected into the oil cavity 3 through the feed hole 8 through the pinhole until the silicone oil fills the oil cavity 3 and the honeycomb rib plate 5. Finally, the feed hole 8 is welded and sealed.

[0026] like Figures 1-5As shown, the center wavelength of the fiber Bragg grating 6 is located at 1526–1560 nm. The fiber Bragg grating 6 communicates with the transmitter main board. The outer wall of the fiber Bragg grating 6 is coated with a 5–10 µm protective varnish, which is a polyimide protective varnish. The fiber Bragg grating 6 is used to realize real-time diagnosis of the health status of the diaphragm body 1 and early warning of corrosion and fatigue. When the center wavelength drift of the grating exceeds the set threshold, an alarm signal is automatically sent to the control system.

[0027] like Figures 1-5 As shown, a wire groove 9 is provided between the honeycomb ribs 5. The connection end of the fiber Bragg grating 6 passes through the wire groove 9 and exits from the sensor back cover 2 to be electrically connected to the external power supply.

[0028] like Figures 1-5 As shown, the outer surface of the diaphragm body 1 has a roughness Ra≤0.20µm after electrochemical polishing, and a hydrophobic layer is provided in the corrosion-resistant and wear-resistant layer 713 to make the water contact angle ≥120° in order to reduce liquid residue.

[0029] like Figures 1-5 As shown, the corrugation pitch of adjacent corrugated grooves 4 is 300–400µm and the corrugation depth is 200–300µm, in order to improve sensitivity and reduce the maximum stress in the membrane.

[0030] Working principle: The diaphragm body 1 is thinned in the middle to improve sensitivity and thickened around the perimeter to resist high pressure and prevent bulging. Multiple corrugated grooves 4 transform the diaphragm body 1 into a soft spring structure, making pressure changes easier to detect. Honeycomb ribs 5 act like a skeleton to support the surrounding area, resisting impact and extending service life. Silicone oil is filled in the oil cavity 3, and the formed oil column can suppress bulging of the diaphragm body 1 under high pressure. The process is simple. Fiber Bragg grating 6 is used to realize real-time diagnosis of the health status of the diaphragm body 1 and early warning of corrosion and fatigue. When the center wavelength drift of the grating exceeds the set threshold, an alarm signal is automatically sent to the control system. Specifically, when the diaphragm body 1 bulges, the optical fiber inside the fiber Bragg grating 6 is stretched or compressed accordingly, and its wavelength changes with the stretching. The tiny strain of the diaphragm body 1 is directly converted into an optical signal, thereby realizing high-precision pressure sensing, health status monitoring and overload warning, without being affected by electromagnetic interference or corrosive environment. The entire process uses light for signal transmission, so it is not afraid of electromagnetic interference and will not be corroded by the medium.

[0031] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter, comprising a diaphragm body (1), wherein the front side of the diaphragm body (1) is for contacting the internal medium of the pressure transmitter, and the back side of the diaphragm body (1) is for assembly and connection with a sensor rear cover (2), characterized in that: The sensor back cover (2) has an oil cavity (3). The back edge of the diaphragm body (1) is welded to the edge of the oil cavity (3). The thickness of the back of the diaphragm body (1) gradually increases from the center to the edge. Multiple corrugated grooves (4) are provided in the central area of ​​the back of the diaphragm body (1). An integrally formed honeycomb rib plate (5) is provided at the edge of the back of the diaphragm body (1). The opening end of the honeycomb rib plate (5) is connected to the oil cavity (3). At least one fiber Bragg grating (6) is embedded on the back of the diaphragm body (1).

2. The high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter according to claim 1, characterized in that, The outer wall of the diaphragm body (1) is provided with a transition layer (711), a hard layer (712) and a corrosion-resistant and wear-resistant layer (713) from the inside to the outside.

3. The high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter according to claim 2, characterized in that, The back of the diaphragm body (1) is provided with a central area and an edge area. The corrugated groove (4) is opened in the central area, and the honeycomb rib (5) is provided in the edge area. The thickness of the central area is 40–60µm, and the thickness of the edge area is 70–120µm.

4. The high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter according to claim 3, characterized in that, The honeycomb rib plate (5) is configured with a honeycomb structure. The honeycomb rib plate (5) has a honeycomb aperture of 0.3-0.8 mm, a wall thickness of 0.05-0.15 mm, and a honeycomb height of 0.5-1.5 mm.

5. A high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter according to claim 4, characterized in that, The sensor back cover (2) has a feed hole (8) that is sealed and connected to the oil chamber (3), and the oil chamber (3) is used to fill silicone oil.

6. The high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter according to claim 1, characterized in that, The fiber Bragg grating (6) has a center wavelength of 1526–1560 nm. The fiber Bragg grating (6) communicates with the transmitter motherboard. The outer wall of the fiber Bragg grating (6) is coated with a 5–10 µm protective varnish.

7. A high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter according to claim 6, characterized in that, The honeycomb ribs (5) are provided with wire grooves (9), and the connection end of the fiber Bragg grating (6) passes through the wire grooves (9) and exits from the sensor back cover (2) to be electrically connected to the external power supply.

8. A high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter according to claim 7, characterized in that, The outer surface of the diaphragm body (1) has a roughness Ra≤0.20µm after electrochemical polishing, and a hydrophobic layer is provided on the corrosion-resistant and wear-resistant layer (713).

9. A high-pressure corrosion-resistant alloy diaphragm for a pressure transmitter according to claim 1, characterized in that, The corrugated pitch of the adjacent corrugated grooves (4) is 300–400µm and the corrugated depth is 200–300µm.

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