A temperature-compensated diaphragm and its preparation method and application

Abstract

This invention discloses a temperature-compensated diaphragm, its preparation method, and its application. The temperature-compensated diaphragm includes a diaphragm body made of a metal sheet, comprising a left half-diaphragm and a right half-diaphragm. Corrugated rotating bodies are disposed on the left and right half-diaphragms, and the left and right half-diaphragms are symmetrical about the centerline of the diaphragm body. The diaphragm body as a whole is either a positive or negative cone shape. By redesigning the diaphragm structure, this invention changes the temperature compensation of the diaphragm sensor from structural component compensation to diaphragm self-compensation. The compensation value range can be expanded from -15 to 15 μm in the prior art to -30 to 40 μm, resulting in a more significant compensation effect. Furthermore, it ensures temperature compensation while miniaturizing the diaphragm sensor, and significantly reduces the difficulty of selecting structural components and diaphragm materials, making sensor design simpler.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically relating to a diaphragm capable of temperature compensation, its preparation method, and its application. Background Technology

[0002] Most current electromechanical sensors use metallic elastic elements (diaphragms) as sensing elements to measure the parameters being measured. Sensors using diaphragms as sensing elements possess strong resistance to electromagnetic interference and overload, while their high temperature, high pressure, and corrosion resistance allow them to operate in high-temperature and high-pressure environments, making them suitable for measuring flammable and explosive media. Diaphragm sensors have short production cycles, low cost, simple structure, and high reliability, and are widely used in aerospace and other fields, being one of the most widely used sensor categories in aerospace. Diaphragm sensors use a diaphragm as the sensing element to sense changes in external air pressure and hydraulic pressure, causing elastic deformation. This deformation is then transmitted to the calculation system to calculate the pressure value of the measured medium.

[0003] Currently, diaphragm sensors are widely used in high-temperature environments in the aerospace field due to their high-temperature resistance. However, the diaphragm, as the sensing element, is made of metal. The elasticity of a metal diaphragm changes with the temperature of the medium. Even with constant sensing pressure, changes in medium temperature cause changes in the diaphragm's output displacement, resulting in output discrepancies in the diaphragm sensor. Current solutions address this issue by adjusting the material of structural components based on the differences in the thermal expansion coefficients of the metals. The elongation of these components due to thermal expansion is used to balance the displacement caused by changes in the diaphragm's elastic modulus. However, this control method still faces challenges. The sensor's tolerance to ambient temperature and medium pressure limits the selection of materials for both the structural components and the elastic element, typically limiting the compensation range to -15 to 15 μm. In increasingly miniaturized sensors, the size of the structural components decreases, further reducing the compensation effect of thermal expansion. This makes it difficult for the thermal expansion of the structural components to completely compensate for the displacement changes caused by variations in the diaphragm's elastic modulus.

[0004] As the sensitive element of a diaphragm sensor, the diaphragm's displacement increases or decreases due to changes in its elastic modulus under high and low temperature environments. It also possesses the thermal expansion rate, an indicator affected by ambient temperature. As a thin-film component, the diaphragm will also stretch under high and low temperature environments due to its inherent thermal expansion rate. However, because the diaphragm's boundary conditions are limited by the structural components, the diaphragm itself will warp due to thermal expansion. As long as the warping direction and warping deformation of the diaphragm under high and low temperature environments can be controlled, the displacement increase or decrease caused by high and low temperature environments can be naturally compensated, thereby reducing the difficulties in selecting structural component materials and matching high and low temperatures. Summary of the Invention

[0005] In view of the above-mentioned prior art, the present invention provides a diaphragm capable of temperature compensation, its preparation method and application, so as to solve the problems of difficult selection of structural materials and difficulty in achieving high and low temperature matching in the temperature compensation process of diaphragm sensors in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is to provide a diaphragm capable of temperature compensation, comprising a diaphragm body made of a metal sheet, the diaphragm body comprising a left half-diaphragm and a right half-diaphragm, wherein corrugated rotating bodies are disposed on the left half-diaphragm and the left half-diaphragm and the right half-diaphragm are centrally symmetrical about the centerline of the diaphragm body; the diaphragm body as a whole is in the shape of a positive cone or a negative cone, wherein in a positive cone the angle between the corrugated outline of the corrugated rotating body and the centerline of the diaphragm body is greater than 90°, and in a negative cone the angle between the corrugated outline of the corrugated rotating body and the centerline of the diaphragm body is less than 90°.

[0007] Based on the above technical solution, the present invention can be further improved as follows.

[0008] Furthermore, the diaphragm body is integrally molded.

[0009] Furthermore, the number of corrugations in the corrugated rotating body is 3 to 5.

[0010] Furthermore, the height of the ripples is 0.53–0.57 mm.

[0011] Furthermore, the height of the corrugations on the left and right halves of the membrane decreases sequentially from the inside to the outside, with the height difference between two adjacent corrugations being 0.1–0.15 mm.

[0012] Furthermore, the convexity of the corrugations is -0.15 to 0.25 mm.

[0013] This invention also discloses a method for preparing a temperature-compensated membrane, the method comprising the following steps:

[0014] S1: Based on the already determined diaphragm substrate, structural component materials, and operating environment temperature of the diaphragm sensor, calculate the displacement difference of the diaphragm substrate caused by temperature influence. The calculation formula is as follows:

[0015] Displacement difference = Change in elastic modulus of diaphragm substrate - Change in thermal expansion of structural component;

[0016] S2: The overall shape of the diaphragm body is determined by the positive or negative value of the displacement difference. When the displacement difference is positive, the diaphragm body is a positive cone shape, and when the displacement difference is negative, the diaphragm body is a negative cone shape. The size of the cone is proportional to the absolute value of the displacement difference.

[0017] S3: Place the diaphragm substrate into the molding die to form it;

[0018] S4: Place the formed membrane body in an aging fixture and perform heat treatment to obtain the final product.

[0019] Furthermore, the diaphragm substrate is made of 30Cr13 stainless steel. The heat treatment method in S4 is as follows: first, quench at 650-700℃ for 2 hours, then refrigerate at -70℃ for 4 hours, and then temper at 1000-1050℃ for 40 minutes to obtain the final product.

[0020] The present invention also discloses the application of temperature-compensated diaphragms in the fabrication of sensors.

[0021] The beneficial effects of this invention are:

[0022] This invention redesigns the diaphragm structure, changing the temperature compensation of the diaphragm sensor from structural component compensation to diaphragm self-compensation. The compensation value range can be expanded from -15 to 15 μm in the prior art to -30 to 40 μm, resulting in a more significant compensation effect. Furthermore, it can ensure temperature compensation while miniaturizing the diaphragm sensor, and significantly reduce the difficulty of selecting structural components and diaphragm materials, making sensor design simpler. Attached Figure Description

[0023] Figure 1 A front view of a diaphragm capable of temperature compensation;

[0024] Figure 2 This is a magnified view of a portion of the corrugated rotating body on the diaphragm body;

[0025] Wherein, 1, diaphragm body; 2, left half of diaphragm; 3, right half of diaphragm; 4, corrugated rotating body; 5, corrugated outline of corrugated rotating body; 6, centerline of diaphragm body; α, angle between corrugated outline of corrugated rotating body and centerline of diaphragm body; h, height of corrugation; r, convexity of corrugation. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0027] Example 1

[0028] A temperature-compensating diaphragm is prepared by the following steps:

[0029] S1: Based on the operating environment of the diaphragm sensor, a steel sheet made of 30Cr13 stainless steel is selected as the diaphragm substrate, and the displacement difference caused by temperature influence on the diaphragm substrate is calculated according to the following formula:

[0030] Displacement difference = Change in elastic modulus of diaphragm substrate - Change in thermal expansion of structural component;

[0031] S2: The overall shape of the diaphragm body 1 is determined by the positive or negative value of the displacement difference. When the displacement difference is positive, the diaphragm body 1 is a positive cone shape, and when the displacement difference is negative, the diaphragm body 1 is a negative cone shape. The size of the cone (the size of the included angle) is proportional to the absolute value of the displacement difference.

[0032] After calculation, the displacement difference (200℃) of the diaphragm substrate is about 35μm. Therefore, the diaphragm body 1 of the final diaphragm is determined to be a positive cone shape, that is, the angle between the corrugated outline 5 of the corrugated rotating body on the diaphragm body 1 and the center line 6 of the diaphragm body is greater than 90° and the angle is about 115°.

[0033] S3: A male and female mold is used as the diaphragm forming mold. The male and female molds have 4 forming ribs, and the height difference between each rib is 0.15mm. After forming, the outer dimension of the diaphragm is φ48mm. The height of the innermost corrugation is 0.55mm, and the height of the remaining corrugations decreases from the inside to the outside, with a corrugation height difference of 0.15mm. The diaphragm substrate is placed in the forming mold and hydraulically formed.

[0034] S4: Based on the 0.15mm difference in corrugation height of the diaphragm body 1, an aging pad is designed. To ensure that the pad and the diaphragm body 1 do not interfere with each other, the step height of the aging pad is 0.15mm. After the aging pad and the diaphragm body 1 are clamped together, they are placed in a vacuum furnace for quenching at 680℃ for 2 hours. Then, they are placed in a -70℃ cold box for 4 hours and then placed back in a vacuum aging furnace for tempering at 1020℃ for 40 minutes to strengthen the diaphragm and achieve a hardness value of 540HV, thus solidifying the surface.

[0035] The membrane structure capable of temperature compensation was prepared using the preparation method described in this embodiment. Figure 1 and 2 As shown, the diaphragm body 1 is made of metal sheet. The diaphragm body 1 is composed of an integrally formed left half diaphragm 2 and right half diaphragm 3. The left half diaphragm 2 and right half diaphragm 3 have corrugated rotating bodies 4, and the left half diaphragm 2 and right half diaphragm 3 are symmetrical about the center line 6 of the diaphragm body. In this embodiment, the diaphragm body 1 is generally conical. The angle between the corrugated outline 5 of the corrugated rotating body on the diaphragm body 1 and the center line 6 of the diaphragm body is about 115°. The number of corrugations in the corrugated rotating bodies 4 on the left half diaphragm 2 and right half diaphragm 3 is 4. The height of the corrugations decreases from the inside to the outside. The height of the innermost corrugation is 0.55 mm, and the height difference between two adjacent corrugations is 0.15 mm.

[0036] Example 2

[0037] A temperature-compensating diaphragm is prepared by the following steps:

[0038] S1: Based on the operating environment of the diaphragm sensor, a steel sheet made of 30Cr13 stainless steel is selected as the diaphragm substrate, and the displacement difference caused by temperature influence on the diaphragm substrate is calculated according to the following formula:

[0039] Displacement difference = Change in elastic modulus of diaphragm substrate - Change in thermal expansion of structural component;

[0040] S2: The overall shape of the diaphragm body 1 is determined by the positive or negative value of the displacement difference. When the displacement difference is positive, the diaphragm body 1 is a positive cone shape, and when the displacement difference is negative, the diaphragm body 1 is a negative cone shape. The size of the cone (the size of the included angle) is proportional to the absolute value of the displacement difference.

[0041] After calculation, the displacement difference of the diaphragm substrate is approximately -30μm. Therefore, the diaphragm body 1 of the final diaphragm is determined to be a negative cone shape, that is, the angle between the corrugated outline 5 of the corrugated rotating body on the diaphragm body 1 and the centerline 6 of the diaphragm body is less than 90° and is about 75°.

[0042] S3: A male and female mold is used as the diaphragm forming mold. The male and female molds have 4 forming ribs, and the height between each rib is 0.55mm. The diaphragm substrate is placed in the forming mold and hydraulically formed.

[0043] S4: Design an aging pad according to the corrugation height of the diaphragm body 1; after clamping the aging pad and the diaphragm body 1, place them together in a vacuum furnace for quenching at 650℃ for 2 hours, then place them in a -70℃ cold box for 4 hours, and then place them back in a vacuum aging furnace for tempering at 1050℃ for 40 minutes to strengthen the diaphragm and solidify the surface.

[0044] The membrane structure capable of temperature compensation was prepared using the preparation method described in this embodiment. Figure 1 and 2 As shown, the diaphragm body 1 is made of metal sheet. The diaphragm body 1 is composed of an integrally formed left half diaphragm 2 and right half diaphragm 3. The left half diaphragm 2 and right half diaphragm 3 have corrugated rotating bodies 4, and the left half diaphragm 2 and right half diaphragm 3 are symmetrical about the center line 6 of the diaphragm body. In this embodiment, the diaphragm body 1 is generally negatively conical. The angle between the corrugated outline 5 of the corrugated rotating body on the diaphragm body 1 and the center line 6 of the diaphragm body is about 75°. The number of corrugations in the corrugated rotating bodies 4 on the left half diaphragm 2 and right half diaphragm 3 is 4, and the height of each corrugation is 0.55mm.

[0045] Experimental Example

[0046] Temperature-compensated membranes were prepared using the fabrication process described in Example 1. Membranes with the convexity (r) shown in Table 1 were obtained. The relationship between the convexity and the compensation value was then determined using the following process:

[0047] (1) First, the convexity of the diaphragm was measured and the value was recorded at room temperature using a micrometer with an accuracy of 1 μm;

[0048] (2) Install diaphragms of various convexities into a special test fixture, ensuring that the displacement sensor fixed in the fixture is coaxial with the diaphragm, so that the displacement sensor can monitor the displacement change of the diaphragm axis region in real time (the displacement sensor accuracy is not less than 0.5μm).

[0049] (3) Place the diaphragm along with the assembled test fixture in the high temperature chamber, turn on the heating system, and raise the temperature from 20℃ to 200℃. During the process, the diaphragm axis area is affected by the diaphragm convexity and the displacement changes with the temperature. The displacement sensor samples and displays the displacement of the diaphragm axis area in real time, and records the current temperature and displacement values ​​of the equipment in real time to form temperature-displacement data of the heating section.

[0050] (4) Cool down the high temperature chamber. The test fixture and diaphragm are cooled down with the chamber. Continue to record the real-time data of the temperature and displacement sensors in real time according to the above method to form the temperature-displacement data of the cooling section. The temperature-displacement curve of the heating section and the temperature-displacement curve of the cooling section basically coincide, indicating that the test data is stable and reliable.

[0051] (5) The convexity of the diaphragm and the temperature-displacement data (the average value of the heating and cooling sections) are compiled to obtain Table 1.

[0052] Table 1. Relationship between convexity of a diaphragm and temperature compensation at 200℃

[0053] Diaphragm convexity / mm -0.15 -0.1 -0.05～0.05 0.1 0.15 0.25 Compensation value / μm -30～-20 -15～-5 0～10 10～20 30～40 53～58

[0054] Although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this patent.

Claims

1. A method for preparing a temperature-compensated diaphragm, characterized in that: The diaphragm body (1) is made of metal sheet. The diaphragm body (1) includes a left half-diaphragm (2) and a right half-diaphragm (3). Corrugated rotating bodies (4) are provided on the left half-diaphragm (2) and the right half-diaphragm (3). The left half-diaphragm (2) and the right half-diaphragm (3) are centrally symmetrical about the center line (6) of the diaphragm body. The diaphragm body (1) is generally in the shape of a positive cone or a negative cone. The positive cone is the one in which the angle between the corrugated outline (5) of the corrugated rotating body and the center line (6) of the diaphragm body is greater than 90°. The negative cone is the one in which the angle between the corrugated outline (5) of the corrugated rotating body and the center line (6) of the diaphragm body is less than 90°. The method for preparing the temperature-compensated membrane includes the following steps: S1: Based on the already determined diaphragm substrate, structural component materials, and operating environment temperature of the diaphragm sensor, calculate the displacement difference of the diaphragm substrate caused by temperature influence. The calculation formula is as follows: Displacement difference = Change in elastic modulus of diaphragm substrate - Change in thermal expansion of structural component; S2: The overall shape of the diaphragm body is determined by the positive or negative value of the displacement difference. When the displacement difference is positive, the diaphragm body is a positive cone shape, and when the displacement difference is negative, the diaphragm body is a negative cone shape. The size of the cone is proportional to the absolute value of the displacement difference. S3: Place the diaphragm substrate into the molding die to form it; S4: Place the formed membrane body in an aging fixture and perform heat treatment to obtain the final product.

2. The method for preparing a temperature-compensated diaphragm according to claim 1, characterized in that: The diaphragm body (1) is integrally formed.

3. The method for preparing a temperature-compensated diaphragm according to claim 2, characterized in that: The number of corrugations in the corrugated rotating body (4) is 3 to 5.

4. The method for preparing a temperature-compensated diaphragm according to claim 3, characterized in that: The height of the ripples is 0.53~0.57mm.

5. The method for preparing a temperature-compensated diaphragm according to claim 3, characterized in that: The height of the corrugations on the left half membrane (2) and the right half membrane (3) decreases sequentially from the inside to the outside, and the height difference between two adjacent corrugations is 0.1~0.15mm.

6. The method for preparing a temperature-compensated diaphragm according to claim 4 or 5, characterized in that: The convexity of the corrugations is -0.15~0.25mm.

7. The method for preparing a temperature-compensated diaphragm according to claim 1, characterized in that, The diaphragm substrate is made of 30Cr13 stainless steel. The heat treatment method in S4 is as follows: first, quench at 650~700℃ for 2 hours, then refrigerate at -70℃ for 4 hours, and then temper at 1000~1050℃ for 40 minutes to obtain the final product.

8. The application of the method for preparing a temperature-compensated diaphragm according to any one of claims 1 to 7 in the preparation of sensors.

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