A pressure core and differential pressure sensor

Abstract

The application discloses a pressure core and a differential pressure sensor, comprising a center pressure sensing diaphragm, wherein a strain layer is arranged on the surface of the center pressure sensing diaphragm, the strain layer is a NiCrAlMnSiWTa layer, and the NiCrAlMnSiWTa layer comprises the following mass fractions of elements: Ni 65%~75%, Cr 10%~20%, Al 1%~5%, Mn 5%~10%, Si 0.5%~1%, W 0.5%~1.5% and Ta 4%~6%. The application optimizes the film layer material and the film plating process of the pressure core, simultaneously optimizes the structure of the center pressure sensing diaphragm, essentially solves the problem of poor measurement accuracy of the differential pressure sensor, reduces the influence of static pressure through the single diaphragm pressure sensing design, and is particularly suitable for the differential pressure measurement in high-temperature occasions.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically relating to a pressure core and a differential pressure sensor. Background Technology

[0002] Existing differential pressure sensors or transmitters include pressure cores such as capacitive differential pressure cores, single-crystal silicon resonant differential pressure cores, single-crystal silicon piezoresistive pressure cores, and nanofilm pressure cores. Nanofilm pressure cores have advantages such as low hysteresis, low drift, and high temperature resistance, but their application is limited due to problems such as relatively low sensitivity, difficulty in implementing overload protection, and significant influence from static pressure.

[0003] The applicant's previously disclosed solutions related to nanofilm pressure cores, such as Chinese patent publications CN117433674A, CN117433675A, CN117387823A, and CN117330235A, can achieve high-precision differential pressure measurement. However, due to the very small deformation of the bridge arm and the small gap between the protective block and the diaphragm (approximately 0.02~0.08 mm), the sensor is prone to failure when the measured medium contains impurities or crystals. Furthermore, the tiny gap places extremely high demands on machining, leading to a sharp increase in cost. In addition, the asymmetric design of the high-pressure and low-pressure sensing sides in existing differential pressure sensors also means that static pressure has a significant impact on the sensor. Summary of the Invention

[0004] The purpose of this invention is to provide a pressure core and a differential pressure sensor to solve at least one aspect of the problems and defects mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A pressure core, comprising a central pressure-sensitive diaphragm; A strain layer is provided on the surface of the central pressure-sensitive diaphragm, and the strain layer is a NiCrAlMnSiWTa layer. The NiCrAlMnSiWTa layer comprises the following elements by mass fraction: Ni 65%~75%, Cr 10%~20%, Al 1%~5%, Mn 5%~10%, Si 0.5%~1%, W 0.5%~1.5% and Ta4%~6%.

[0006] Adding W to the strain layer can improve the creep resistance of the film.

[0007] As a further embodiment of the present invention, the mass fraction of Ni element in the strain layer is 65%~68%.

[0008] As a further embodiment of the present invention, the mass fraction of Cr element in the strain layer is 15%~17%.

[0009] As a further embodiment of the present invention, the mass fraction of Al element in the strain layer is 2% to 4%.

[0010] As a further embodiment of the present invention, the mass fraction of Mn element in the strain layer is 6%~8%.

[0011] As a further embodiment of the present invention, the mass fraction of Si element in the strain layer is 0.6% to 0.8%.

[0012] As a further embodiment of the present invention, the mass fraction of W element in the strain layer is 0.8% to 1.1%.

[0013] As a further embodiment of the present invention, the mass fraction of Ta element in the strain layer is 4.0% to 4.5%.

[0014] As a further embodiment of the present invention, the strain layer comprises the following elements by mass fraction: Ni 68%, Cr 16%, Al 3%, Mn 7%, Si 0.8%, W 1%, and Ta 4.2%.

[0015] As a further embodiment of the present invention, the thickness of the strain layer is 50~200nm, preferably 100~150nm, and more preferably 120nm.

[0016] As a further embodiment of the present invention, the surface of the central pressure-sensitive diaphragm is further provided with a transition layer, an insulating layer, a pad layer and a protective layer.

[0017] As a further embodiment of the present invention: the central pressure-sensitive diaphragm is a metal elastomer, preferably a stainless steel metal elastomer, and the stainless steel can be selected from 17-4PH stainless steel, 17-7PH stainless steel, 316 / 316L stainless steel, 304 / 304L stainless steel, 15-5PH stainless steel, etc.

[0018] As a further embodiment of the present invention: the transition layer includes an NbZr1 alloy layer, which uses an NbZr1 alloy whose coefficient of thermal expansion is between that of stainless steel and common insulating materials (SiO2, Si3O4), and is used to match the thermal mismatch coefficient between stainless steel and the insulating layer.

[0019] As a further embodiment of the present invention, the thickness of the transition layer is 50~200nm, preferably 80~120nm, and more preferably 100nm.

[0020] As a further solution of the present invention: the insulating layer comprises a first high dielectric constant material layer made of a high dielectric constant material, and the first high dielectric constant material includes at least one of Si3N4, SiO2, and PI (polyimide), preferably Si3N4 material.

[0021] As a further solution of the present invention: the thickness of the insulating layer is 0.5~6um, preferably 1~3um, and more preferably 2um.

[0022] As a further solution of the present invention: the pad layer comprises a gold pad layer made of gold, with a thickness of 0.5~5um, preferably 0.5~1.5um, and more preferably 1um.

[0023] As a further solution of the present invention: the protective layer comprises a second high dielectric constant material layer made of a high dielectric constant material, and the second high dielectric constant material includes at least one of Si3N4, SiO2, and PI (polyimide), preferably PI material.

[0024] As a further solution of the present invention: the thickness of the protective layer is 0.5~50um, preferably 4.5~5.5um, and more preferably 5um.

[0025] As a further solution of the present invention: the first high dielectric constant material layer and the second high dielectric constant material layer are each independently selected from at least one of a Si3N4 layer, a SiO2 layer, and a PI layer.

[0026] As a further solution of the present invention: the strain layer, the transition layer, the insulating layer, the pad layer and the protective layer are formed by one of a magnetron sputtering method, a chemical vapor deposition method, and an atomic layer deposition method.

[0027] As a further solution of the present invention: the central pressure-sensitive diaphragm further comprises a base body and a recessed area, the recessed area is circular, with a diameter of 10mm≤D≤25mm, preferably 15mm≤D≤25mm, and more preferably 21mm.

[0028] As a further solution of the present invention: the thickness of the bottom wall of the recessed area is 0.05mm≤t1≤0.2mm, preferably 0.1mm≤t1≤0.16mm, and more preferably 0.15mm.

[0029] As a further solution of the present invention: a circular boss is arranged at the center of the recessed area.

[0030] As a further solution of the present invention: the top surface diameter of the circular boss is 0<D1≤20mm, preferably 13mm≤D1≤20mm, and more preferably 13mm≤D1≤15mm.

[0031] As a further solution of the present invention: the thickness of the circular boss is 0<t2≤0.7mm, preferably 0.4mm≤t2≤0.5mm.

[0032] As a further solution of the present invention: an included angle α is formed between the side generatrix of the circular boss and the surface of the base body, where 0<α≤20°, preferably 10°≤α≤16°, and more preferably 15°.

[0033] As a further solution of the present invention: the recessed area is arranged on one side surface of the base body, the other side surface of the base body is a functional film layer, and the functional film layer is formed sequentially from the inside to the outside by the transition layer, the insulating layer, the strain layer, the pad layer and the protective layer.

[0034] As a further solution of the present invention: strain resistors and circuits are etched on the functional film layer to form a Wheatstone bridge.

[0035] As a further solution of the present invention: there are 4 strain resistors, which are etched at 4 positions with the maximum strain on the central pressure-sensitive diaphragm, and circuits are etched out to connect the strain resistors to form a Wheatstone bridge.

[0036] A differential pressure sensor, comprising the pressure core body according to any one of the above items.

[0037] As a further solution of the present invention: the differential pressure sensor further comprises a protection block; The protection surface of the protection block is configured as a curved surface, and the curved surface is complementary to the deformation profile of the central pressure-sensitive diaphragm when a single-side overload of 1 to 2 times is applied, so that when the central pressure-sensitive diaphragm is subjected to a unidirectional pressure exceeding a threshold value, the deformation of the central pressure-sensitive diaphragm is blocked by the curved surface to limit further displacement.

[0038] As a further solution of the present invention: the curved surface is complementary to the deformation profile of the central pressure-sensitive diaphragm when a single-side overload of 1.5 times is applied. When the pressure is too high, the central pressure-sensitive diaphragm is completely attached to the protective curved surface and no longer deforms, thereby achieving a protective effect.

[0039] As a further solution of the present invention: the protection block is arranged on the side of the central pressure-sensitive diaphragm where the functional film layer is provided; One end of the protection block is a fixed end, which is connected to the central pressure-sensitive diaphragm through a filling block; The other end of the protection block is a free end, and when the central pressure-sensitive diaphragm is not under pressure, a gap exists between the protection surface of the protection block and the surface of the central pressure-sensitive diaphragm.

[0040] As a further solution of the present invention: the high-pressure side and the low-pressure side of the differential pressure sensor are of a symmetrical structure.

[0041] As a further embodiment of the present invention: the differential pressure sensor further includes a high-pressure cavity and a low-pressure cavity, the high-pressure cavity and the low-pressure cavity are respectively disposed on both sides of the central pressure-sensing diaphragm, the high-pressure cavity is filled with medium oil and hydraulically coupled to the high-pressure side surface of the central pressure-sensing diaphragm; The low-pressure cavity is filled with medium oil and hydraulically coupled to the low-pressure side surface of the central pressure-sensing diaphragm.

[0042] As a further embodiment of the present invention, the medium oil may be selected from silicone oil, fluorinated oil, etc., and is preferably silicone oil.

[0043] As a further embodiment of the present invention: an electrical signal pin is provided on the low-pressure cavity, which can be used for input of excitation voltage and output of pressure electrical signal.

[0044] As a further embodiment of the present invention: a high-pressure side isolation diaphragm is provided on the side of the high-pressure cavity away from the central pressure-sensing diaphragm, and the high-pressure side isolation diaphragm and the high-pressure side pressure-inducing cavity together form a high-pressure side pressure-inducing channel; The low-pressure cavity is provided with a low-pressure side isolation diaphragm on the side away from the central pressure-sensing diaphragm. The low-pressure side isolation diaphragm and the low-pressure side pressure-inducing cavity together form a low-pressure side pressure-inducing channel.

[0045] As a further embodiment of the present invention: the high-pressure side pressure-inlet cavity is provided with a high-pressure side pressure-inlet port and a high-pressure side exhaust port, and the high-pressure side exhaust port is located at the highest point of the high-pressure side pressure-inlet channel; The low-pressure side pressure-inlet cavity is provided with a low-pressure side pressure-inlet port and a low-pressure side exhaust port, and the low-pressure side exhaust port is located at the highest point of the low-pressure side pressure-inlet channel.

[0046] The present invention has at least the following technical effects: (1) Optimize the functional film material, introduce W element into the strain layer to increase the creep resistance of the film, use NbZr1 alloy in the transition layer to match the thermal mismatch coefficient on both sides; adopt nano-coating technology to generate functional film at the atomic level. All film materials have high melting point and thermal stability, which fundamentally solves the problem of high stability measurement accuracy and is particularly suitable for differential pressure measurement in high temperature applications. (2) The strain gauge pressure sensing core is produced by using an independently controllable nano-coating process. The pressure sensing core is encapsulated in the medium oil to isolate the pressure sensing core from the liquid being measured, thus avoiding sensor failure caused by impurities and crystals in the medium being measured. This protects the pressure core and enables stable and high-precision measurement. (3) Using a single diaphragm for pressure sensing, optimizing the design of the high-pressure side and the low-pressure side, effectively reducing the impact of static pressure; (4) By setting a curved protective block on one side of the pressure-sensitive diaphragm, unilateral overload protection is achieved; (5) It can perform high-precision differential pressure measurement with an accuracy better than 0.1%FS. Attached Figure Description

[0047] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0048] Figure 1 This is a schematic diagram of the functional membrane structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a central pressure-sensitive diaphragm structure according to an embodiment of the present invention; Figure 3 This is a schematic diagram of another central pressure-sensitive diaphragm structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the differential pressure sensor structure according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the surface etching circuit according to an embodiment of the present invention; Figure 6 This is a schematic diagram showing the location of maximum strain on the central pressure-sensitive diaphragm in an embodiment of the present invention; Figure 7 This is a schematic diagram of the electrical signal pin structure according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the protective block structure according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the coordinates of the protective block surface according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the differential pressure sensor structure as a comparative example of the present invention.

[0049] Figure label: 1. High-voltage side pressure tapping chamber; 2. High-voltage side isolation diaphragm; 3. High-voltage side oil filling pipe; 4. Central pressure sensing diaphragm; 5. Low-voltage side oil filling pipe; 6. Low-pressure chamber; 7. Low-pressure side isolation diaphragm; 8. Low-pressure side pressure tapping chamber; 9. Protective block; 10. Filler block; 11. High-voltage chamber; 12. Transition layer; 13. Insulating layer; 14. Strain layer; 15. Pad layer; 16. Protective layer; 1-1. High-voltage side pressure tap; 1-2. High-voltage side exhaust port; 8-1. Low-voltage side pressure tap; 8-2. Low-voltage side exhaust port; 17. Electrical signal pin; 18. Elastic diaphragm; 19. Bridge arm. Detailed Implementation

[0050] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0051] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0052] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0053] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0056] Example 1 A pressure core includes a central pressure-sensitive diaphragm 4, the surface of which is deposited with a functional film layer by atomic-level deposition, the functional film layer being grown at the atomic level on the surface of the central pressure-sensitive diaphragm 4.

[0057] Please see Figure 1 The functional film layer is divided into 5 layers, which are, from the inside out, a transition layer 12, an insulating layer 13, a strain layer 14, a pad layer 15, and a protective layer 16.

[0058] The transition layer 12 is made of NbZr1 alloy and has a film thickness of 100 nm.

[0059] The insulating layer 13 is made of Si3N4, a material with a high dielectric constant, and the film thickness is 2µm.

[0060] The strain layer 14 is made of optimized Ni-Cr material NiCrAlMnSiWTa, with a mass fraction of Ni 68%, Cr 16%, Al 3%, Mn 7%, Si 0.8%, W 1% and Ta 4.2%, and a film thickness of 120 nm.

[0061] The pad layer 15 is made of gold, and the film thickness is 1µm.

[0062] The protective layer 16 is made of PI (polyimide), a material with a high dielectric constant, and the film thickness is 5 μm.

[0063] Example 2 The difference from Example 1 is that the strain layer 14 does not contain W element, and the mass composition is Ni 69%, Cr 16%, Al 3%, Mn 7%, Si 0.8% and Ta 4.2%.

[0064] Test Example 1 Five pressure cores were fabricated for each of Examples 1 and 2 for testing. A pressure of 100 kPa and an excitation voltage of 10 V were applied. The output voltage and creep value at different holding times are shown in Table 1.

[0065] The results showed that after the pressure stabilized for 30 min and 60 min, the creep value of the pressure core obtained in Example 1 was significantly lower than that of the pressure core in Example 2, and the creep value of the pressure core in Example 1 did not exceed 0.05%, indicating that the creep resistance of the film was improved by adding W element to the strain layer.

[0066] Table 1

[0067] Example 3 Please see Figure 2 A pressure core includes a central pressure-sensitive diaphragm 4, the central pressure-sensitive diaphragm 4 including a substrate, a functional membrane layer and a recessed area, the functional membrane layer being disposed on one side surface of the substrate and the recessed area being disposed on the other side surface of the substrate.

[0068] The structure of the central pressure-sensitive diaphragm 4 was optimized. The diameter of the recessed area of ​​the central pressure-sensitive diaphragm 4 is D, and the thickness of the bottom wall is t1. The values ​​of D and t1 in analysis groups 1 to 5 are shown in Table 2.

[0069] Table 2

[0070] Example 4 Please see Figure 3 A pressure core includes a central pressure-sensitive diaphragm 4, which includes a substrate, a functional membrane layer, and a recessed area. The functional membrane layer is disposed on one side surface of the substrate, and the recessed area is disposed on the other side surface of the substrate. A circular boss is disposed at the center of the recessed area.

[0071] The structure of the central pressure-sensitive diaphragm 4 was optimized: The diameter of the recessed area is D, and the thickness of the bottom wall is t1; The diameter of the top surface of the circular boss is D1, the thickness is t2, and the side generatrix forms an angle α with the surface of the base.

[0072] In analysis groups 6-10, the values ​​of D, t1, D1, t2, and α are shown in Table 3.

[0073] Table 3

[0074] Test Example 2 The performance of the central pressure-sensitive diaphragm 4 in analysis groups 1-10 was analyzed and tested. The objectives of the analysis were: comprehensive nonlinearity <1%FS, and the smaller the better; strain ≥500 microstrain; maximum diaphragm displacement ≥0.25mm. The results of the finite element analysis optimization are shown in Table 4.

[0075] The results show that the nonlinearity in analysis groups 1, 2, 3, and 5 is very large and does not meet the requirements; the strain and displacement in analysis group 4 do not meet the requirements. Some data in analysis groups 8, 9, and 10 meet the requirements, but the overall nonlinearity is not optimal.

[0076] Although one strain data point in analysis group 6 did not meet the requirement of ≥500 microstrain, it was quite close, and the overall nonlinearity was the smallest. All data in analysis group 7 met the requirements, and the overall nonlinearity was comparable to that of analysis group 6, while the remaining parameters were superior to those of analysis group 6. Therefore, analysis group 7 is the optimal data group.

[0077] Table 4

[0078] Example 5 Please see Figure 1 , 3 A pressure core includes a central pressure-sensitive diaphragm 4, which includes a substrate, a functional membrane layer, and a recessed area. The functional membrane layer is disposed on one side surface of the substrate, and the recessed area is disposed on the other side surface of the substrate. A circular boss is disposed at the center of the recessed area.

[0079] The diameter of the recessed area is 21 mm, and the thickness of the bottom wall is 0.15 mm.

[0080] The top surface of the circular boss has a diameter of 13mm and a thickness of 0.5mm, and the angle between the side generatrix and the surface of the base is 15°.

[0081] Test Example 3 The performance of the pressure core of Example 5 was tested, and the results are shown in Table 5. The results show that the pressure core of Example 5, under the test condition of 100 kPa, exhibits good detection performance with nonlinearity in the range of 0.01% to 0.07%FS, hysteresis in the range of 0.03% to 0.06%FS, and sensitivity in the range of 1.4 to 2.1 mV / V.

[0082] Table 5

[0083] Example 6 Please see Figure 4 As shown, a differential pressure sensor includes a pressure core, a high-pressure chamber 11, and a low-pressure chamber 6. The pressure core includes a central pressure-sensing diaphragm 4, and a functional membrane layer is disposed on the surface of the central pressure-sensing diaphragm 4.

[0084] The high-pressure chamber 11 is located on one side of the central pressure-sensing diaphragm 4, and is filled with medium oil through the high-pressure side oil filling pipe 3 and hydraulically coupled to the high-pressure side surface of the central pressure-sensing diaphragm 4. The low-pressure chamber 6 is located on the other side of the central pressure-sensing diaphragm 4. It is filled with medium oil through the low-pressure side oil filling pipe 5 and hydraulically coupled to the low-pressure side surface of the central pressure-sensing diaphragm 4.

[0085] A high-pressure isolation diaphragm 2 is provided on the side of the high-pressure chamber 11 away from the central pressure-sensing diaphragm 4. The high-pressure isolation diaphragm 2 and the high-pressure pressure-sensing chamber 1 together form a high-pressure pressure-sensing channel. A low-pressure side isolation diaphragm 7 is provided on the side of the low-pressure cavity 6 away from the central pressure-sensing diaphragm 4. The low-pressure side isolation diaphragm 7 and the low-pressure side pressure-sensing cavity 8 together form a low-pressure side pressure-sensing channel.

[0086] The high-pressure side pressure-inlet chamber 1 is provided with a high-pressure side pressure-inlet 1-1 and a high-pressure side exhaust port 1-2, with the high-pressure side exhaust port 1-2 located at the highest point of the high-pressure side pressure-inlet channel; The low-pressure side pressure chamber 8 is provided with a low-pressure side pressure inlet 8-1 and a low-pressure side exhaust outlet 8-2. The low-pressure side exhaust outlet 8-2 is located at the highest point of the low-pressure side pressure channel.

[0087] Please see Figure 5 As shown, strain gauges and circuits are fabricated on the functional film layer of the central pressure-sensitive diaphragm 4 using photolithography and etching processes. There are four strain gauges, positioned at the locations of maximum strain on the central pressure-sensitive diaphragm 4, forming a Wheatstone bridge with the etched circuitry. The locations of maximum strain on the central pressure-sensitive diaphragm 4 are shown in the diagram. Figure 6 As shown.

[0088] When a constant excitation voltage or current is applied to the V+ and V- terminals, a voltage signal that varies with pressure will be output at the S+ and S- terminals, thus realizing the conversion of pressure into an electrical signal.

[0089] Please see Figure 7 As shown, an electrical signal pin 17 is provided on the low-pressure cavity 6 for inputting the excitation voltage and outputting the pressure electrical signal.

[0090] Working principle: First, silicone oil is filled into the high-pressure chamber 11 and the low-pressure chamber 6 through the high-pressure side oil filling pipe 3 and the low-pressure side oil filling pipe 5, so that the space between the isolation diaphragms on both sides and the central pressure-sensing diaphragm 4 is filled with silicone oil, which is used to transmit pressure and realize hydraulic coupling.

[0091] The high-pressure side pressure inlet 1-1 introduces pressure into the high-pressure side pressure inlet chamber 1, and discharges the air inside through the high-pressure side exhaust port 1-2 to prevent air from affecting the measurement. The high-pressure side pressure acts on the high-pressure side isolation diaphragm 2 inside the high-pressure side pressure inlet chamber 1. The isolation diaphragm transmits the pressure to the internal silicone oil, and the silicone oil then transmits the pressure to the high-pressure side surface of the central pressure-sensing diaphragm 4.

[0092] The low-pressure side pressure inlet 8-1 introduces pressure into the low-pressure side pressure inlet chamber 8, and discharges the air inside through the low-pressure side exhaust port 8-2 to prevent air from affecting the measurement. The low-pressure side pressure acts on the low-pressure side isolation diaphragm 7 within the low-pressure side pressure inlet chamber 8. The isolation diaphragm transmits the pressure to the internal silicone oil, and the silicone oil then transmits the pressure to the low-pressure side surface of the central pressure-sensing diaphragm 4.

[0093] The pressure on both sides of the central pressure-sensitive diaphragm 4 acts simultaneously on the central pressure-sensitive diaphragm 4, creating a pressure difference that deforms the central pressure-sensitive diaphragm 4. The deformation of the central pressure-sensitive diaphragm 4 causes the four strain gauges to stretch or compress, thereby producing changes in their resistance values.

[0094] A constant excitation voltage or current is applied by the electrical signal pin 17 on the low-pressure chamber. The change in resistance is converted into a change in voltage. The changed voltage is then output through the electrical signal pin 17 on the low-pressure chamber, thus completing the measurement process of converting the change in pressure difference between the two ends into a change in electrical signal.

[0095] Example 7 Please see Figure 8 As shown, a differential pressure sensor has the components shown in Embodiment 6, and also includes a protection block 9.

[0096] One end of the protective block 9 is a fixed end, which is connected to the central pressure-sensitive diaphragm 4 through the filling block 10; The other end of the protective block 9 is a free end. When the central pressure-sensitive diaphragm 4 is not under pressure, there is a gap between the protective surface of the protective block 9 and the surface of the central pressure-sensitive diaphragm 4.

[0097] Example 8 A differential pressure sensor has the components shown in Embodiment 7. The protective surface of the protective block 9 is configured as a curved surface, which is complementary to the deformation profile of the central pressure-sensing diaphragm 4 when subjected to a unilateral overload of 1.5 times. This ensures that when the central pressure-sensing diaphragm 4 is subjected to a unidirectional pressure exceeding a threshold, the deformation of the central pressure-sensing diaphragm 4 is blocked by the protective block to limit further displacement, effectively achieving unilateral overload.

[0098] The coordinates of the protective surface of the protective block 9 are shown in Table 6. The coordinate data are the surface coordinates formed by the deformation design of the central pressure-sensing diaphragm under 1.5 times overload.

[0099] When the applied pressure is ≥1.5 times the design pressure, the curved surface of the central pressure-sensing diaphragm 4 and the protective block 9 are completely in contact, and the central pressure-sensing diaphragm 4 no longer deforms, thus protecting the central pressure-sensing diaphragm 4 from damage under overpressure conditions.

[0100] Table 6

[0101] Example 9 A differential pressure sensor has the components shown in Embodiment 7. The central pressure-sensing diaphragm 4 includes a substrate, a functional membrane layer, and a recessed area. The functional membrane layer is disposed on one side surface of the substrate, and the recessed area is disposed on the other side surface of the substrate.

[0102] Example 10 A differential pressure sensor having the components shown in Embodiment 9, wherein a circular boss is provided at the center of the recessed area.

[0103] Example 11 A differential pressure sensor having the components shown in Example 10, wherein the functional diaphragm layer is as shown in Example 1.

[0104] Example 12 A differential pressure sensor having the components shown in Example 11, wherein the structure of the central pressure-sensing diaphragm 4 is as shown in analysis group 6 in Example 4.

[0105] Example 13 A differential pressure sensor having the components shown in Example 11, wherein the structure of the central pressure-sensing diaphragm 4 is as shown in analysis group 7 in Example 4.

[0106] Example 14 A differential pressure sensor having the components shown in Embodiment 8, wherein the central pressure-sensing diaphragm 4 includes a substrate, a functional membrane layer and a recessed area, the functional membrane layer being disposed on one side surface of the substrate and the recessed area being disposed on the other side surface of the substrate.

[0107] Example 15 A differential pressure sensor having the components shown in Embodiment 14, wherein a circular boss is provided at the center of the recessed area.

[0108] Example 16 A differential pressure sensor having the components shown in Example 15, wherein the functional diaphragm layer is as shown in Example 1.

[0109] Example 17 A differential pressure sensor having the components shown in Example 16, wherein the structure of the central pressure-sensing diaphragm 4 is as shown in analysis group 6 in Example 4.

[0110] Example 18 A differential pressure sensor has the components shown in Example 16, wherein the structure of the central pressure-sensing diaphragm 4 is as shown in analysis group 7 of Example 4. This differential pressure sensor employs a single-diaphragm pressure-sensing structure, with the pressures of the high-pressure chamber 11 and the low-pressure chamber 6 acting on both sides of the central pressure-sensing diaphragm 4, respectively. A circuit is plated on one side of the central pressure-sensing diaphragm 4 for direct pressure sensing.

[0111] Comparative Example 1 Please see Figure 10 A differential pressure sensor with an asymmetric structure.

[0112] The pressure in the high-pressure chamber 11 is fully applied to the elastic diaphragm 18. A bridge arm 19 is added to the elastic diaphragm 18 on the side of the low-pressure chamber 6. The pressure is applied to the elastic diaphragm 18 and the bridge arm 19. The circuit is plated on the bridge arm 19. The elastic diaphragm 18 drives the bridge arm 19 to deform, indirectly sensing the pressure and forming an asymmetric structure.

[0113] Test Example 4 The performance of the differential pressure sensor shown in Example 18 and Comparative Example 1 was tested, and the results are shown in Table 7.

[0114] The results show that as the applied static pressure gradually increases from 2 MPa to 25 MPa, the effect on the differential pressure sensors shown in Example 18 and Comparative Example 1 also gradually increases; however, the effect of static pressure on the differential pressure sensor shown in Example 18 is less than that on the differential pressure sensor shown in Comparative Example 1, indicating that the differential pressure sensor with a symmetrical structure on the high-pressure side and the low-pressure side of the present invention can significantly reduce the effect of static pressure.

[0115] Table 7

[0116] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A pressure core, characterized in that, Including a central pressure-sensitive diaphragm; A strain layer is provided on the surface of the central pressure-sensitive diaphragm, and the strain layer is a NiCrAlMnSiWTa layer. The NiCrAlMnSiWTa layer comprises elements with the following mass fractions: Ni 65%~75%, Cr 10%~20%, Al 1%~5%, Mn 5%~10%, Si 0.5%~1%, W0.5%~1.5% and Ta 4%~6%.

2. The pressure core according to claim 1, characterized in that, The surface of the central pressure-sensitive diaphragm is further provided with a transition layer, an insulating layer, a pad layer, and a protective layer, satisfying at least one of the following characteristics (1) to (10): (1) The thickness of the strain layer is 50~200nm; (2) The transition layer includes an NbZr1 alloy layer; (3) The thickness of the transition layer is 50~200nm; (4) The insulating layer includes a first high dielectric constant material layer; (5) The thickness of the insulating layer is 0.5~6 μm; (6) The pad layer includes a gold pad layer; (7) The thickness of the pad layer is 0.5~5um; (8) The protective layer includes a second high dielectric constant material layer; (9) The thickness of the protective layer is 0.5~50um; (10) The first high dielectric constant material layer and the second high dielectric constant material layer are independently selected from at least one of Si3N4 layer, SiO2 layer and PI layer.

3. The pressure core according to claim 2, characterized in that, The strain layer, transition layer, insulating layer, pad layer, and protective layer are formed by one of the following methods: magnetron sputtering, chemical vapor deposition, and atomic deposition.

4. The pressure core according to any one of claims 1 to 3, characterized in that, The central pressure-sensitive diaphragm also includes a substrate and a recessed area, wherein the recessed area is circular and has a diameter of 10mm≤D≤25mm.

5. The pressure core according to claim 4, characterized in that, The thickness of the bottom wall of the recessed area is 0.05mm≤t1≤0.2mm.

6. The pressure core according to claim 4, characterized in that, A circular protrusion is provided at the center of the recessed area, and the top diameter of the circular protrusion is 0. <D1≤20mm。 7. The pressure core according to claim 6, characterized in that, The thickness of the circular boss is 0. <t2≤0.7mm。 8. The pressure core according to claim 6, characterized in that, The side generatrix of the circular boss forms an angle α with the surface of the base, wherein 0 < α ≤ 20°.

9. A differential pressure sensor, characterized in that, Includes the pressure core as described in any one of claims 1 to 8.

10. The differential pressure sensor according to claim 9, characterized in that, It also includes a protective block, the protective surface of which is set as a curved surface, and the curved surface is complementary to the deformation profile of the central pressure-sensitive diaphragm when it is overloaded by 1 to 2 times on one side.

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