A pressure transmitter and its manufacturing method

Abstract

The present invention relates to the technical field of pressure transmitters, and provides a pressure diaphragm made of elastic material and having micro-strain, wherein a diaphragm pressure-inducing hole is provided in the pressure diaphragm, and a flat circular diaphragm is provided at the extended end of the diaphragm pressure-inducing hole; a strain gauge is solidified on the surface of the flat circular diaphragm, and the deformation of the flat circular diaphragm causes the resistance change of the strain gauge; an amplifier circuit board is electrically connected to the strain gauge, and the amplifier circuit board is used to collect resistance signals, perform temperature compensation calculations on the strain gauge, and output an amplified voltage signal; a signal conversion circuit board is electrically connected to the amplifier circuit board, and the signal conversion circuit board is used to convert the input amplified voltage signal into a standard signal of the pressure transmitter, and output it to an external device electrically connected to the signal conversion circuit board. The present invention also provides a method for manufacturing a pressure transmitter. The maximum measurement pressure of the present invention is up to 1000Mpa, and it can withstand 10 million times of 1.5 times full-scale pressure cycle loading, which greatly reduces the temperature drift coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure transmitters, and in particular to a pressure transmitter and a manufacturing method thereof. Background Art

[0002] Pressure transmitter is a device that converts pressure into electric signals for control and remote transmission. It can convert physical pressure parameters such as gas and liquid sensed by the pressure measuring element sensor into standard electrical signals (such as 4~20mADC, etc.) to supply secondary instruments such as indicator alarms, recorders, and regulators for measurement, indication, and process adjustment. The measurement accuracy of the pressure transmitter directly affects the stability and safety of the control system. Various types of pressure transmitters in the prior art have the following common problems: 1. The pressure resistance is low, and it is impossible to stably measure ultra-high pressures above 300MPa. The overload capacity is low. After being affected by pressure overload, the pressure element will be damaged and the output signal will be abnormal; 2. The movement amplitude of the measuring mechanism such as the diaphragm is too large, which is easy to fatigue and deform, with a short working life and poor long-term stability; 3. The temperature drift coefficient is high. Affected by temperature changes, it will produce a large temperature drift and reduce the measurement accuracy. Summary of the invention

[0003] The present invention aims at solving the problems existing in the prior art and provides a pressure transmitter and a manufacturing method thereof, so as to solve the technical problems existing in the prior art of the pressure transmitter, namely, low pressure resistance, easy fatigue deformation of the diaphragm and high temperature drift coefficient.

[0004] The technical solution proposed by the present invention for the above-mentioned technical problem is as follows:

[0005] A pressure transmitter, comprising:

[0006] A pressure diaphragm made of elastic material and having micro-strain, wherein a diaphragm pressure induction hole is provided in the pressure diaphragm, and a flat circular diaphragm is provided at the extended end of the diaphragm pressure induction hole;

[0007] A strain gauge is solidified on the surface of the planar circular diaphragm, and the deformation of the planar circular diaphragm causes the resistance of the strain gauge to change;

[0008] an amplifying circuit board, electrically connected to the strain gauge, and used for collecting resistance signals, performing temperature compensation calculation on the strain gauge, and outputting amplified voltage signals;

[0009] A signal conversion circuit board is electrically connected to the amplification circuit board, and is used to convert the input amplified voltage signal into a standard signal of the pressure transmitter and output it to an external device electrically connected to the signal conversion circuit board.

[0010] According to the pressure transmitter described above, a buffer plug is provided at the opening of the diaphragm pressure inlet hole, and the buffer plug is provided at the opening of the diaphragm pressure inlet hole and is detachably connected to the pressure diaphragm through the diaphragm pressure inlet hole; the buffer plug is provided with a buffer plug pressure inlet hole which passes through the entire buffer plug, and the buffer plug pressure inlet hole is connected to the diaphragm pressure inlet hole.

[0011] According to the pressure transmitter described above, the outer side wall of the pressure diaphragm is provided with a stress blocking groove, and the stress blocking groove is used to block the installation stress from being transmitted to the flat circular diaphragm.

[0012] According to the pressure transmitter described above, the outer side wall of the pressure diaphragm is provided with a process interface, and the process interface and the pressure diaphragm are an integrated structure.

[0013] According to the pressure transmitter described above, the strain gauge is sintered and solidified on the surface of the planar circular diaphragm through a connecting layer, and the connecting layer is made of a silicate material.

[0014] According to the pressure transmitter described above, the pressure transmitter further comprises a housing, the pressure diaphragm is fixedly connected to the housing, a circuit board bracket is provided inside the housing, and the pressure diaphragm is fixedly connected to the circuit board bracket;

[0015] The circuit board bracket is provided with a bonding circuit board, the bonding circuit board is fixedly connected to the circuit board bracket, and an insulating gasket is provided between the bonding circuit board and the circuit board bracket, the insulating gasket is used to protect the bonding circuit board and prevent the bonding circuit board and the circuit board bracket from short circuiting.

[0016] According to the pressure transmitter described above, the strain gauge is connected to the bonding circuit board through a wire, the wire is used to transmit signals between the strain gauge and the bonding circuit board, the bonding circuit board is connected to the amplifying circuit board through a first pin, the amplifying circuit board is connected to the signal conversion circuit board through a second pin, and the signal conversion circuit board is connected to an external device through an electrical connector;

[0017] The outside of the electrical connector is fixedly connected with an electrical connector, and the electrical connector is connected to the housing.

[0018] According to the pressure transmitter described above, a protective cover for covering the strain gauge and the wire is provided on the bonding circuit board, and the protective cover is fixedly connected to the bonding circuit board.

[0019] Another object of the present invention is to provide a method for manufacturing the pressure transmitter described above, comprising:

[0020] Step S100: processing the pressure diaphragm, specifically: processing the pressure diaphragm according to the design drawing, placing the processed pressure diaphragm into a vacuum furnace for heat treatment, and grinding the heat-treated pressure diaphragm to ensure that the parallelism of the pressure diaphragm meets the preset requirements;

[0021] Step S200: silicate screen printing, specifically: fix the qualified pressure diaphragm on the base, cover the prepared steel mesh on the pressure diaphragm, and place the milky silicate on the steel mesh, scrape the silicate evenly along the surface of the steel mesh with a scraper, then take out the steel mesh, and remove the pressure diaphragm from the base;

[0022] Step S300: positioning the strain gauge, specifically: placing the strain gauge in the silicate covered area on the surface of the pressure diaphragm;

[0023] Step S400: silicate sintering and curing, specifically: loading the silk-screened pressure diaphragms into the fixing fixtures in batches, and sequentially placing the fixing fixtures into the multi-temperature zone vacuum tunnel furnace for silicate sintering. After the silicate sintering is completed, the silicate solidifies the strain gauge on the surface of the pressure diaphragm;

[0024] Step S500, installing the bonding circuit board, specifically: welding the circuit board bracket and the pressure diaphragm, and then fixing the bonding circuit board on the circuit board bracket by high-temperature adhesive, and baking and curing;

[0025] Step S600, circuit assembly, specifically: using an ultrasonic wire bonding machine to weld the two ends of the wire to the strain gauge and the bonding circuit board respectively, and using a protective cover to cover the wire and the strain gauge; using a first pin to connect the bonding circuit board to the amplifying circuit board, using a second plug-in to connect the amplifying circuit board to the signal conversion circuit board, and using an electrical connector to connect the signal conversion circuit board to an external device;

[0026] Step S700, assembling the housing and the electrical connector, specifically: inserting the electrical connector outside the electrical connector and fixing it with glue, and then welding the electrical connector to the housing.

[0027] According to the manufacturing method of the pressure transmitter described above, after step S700, the method further includes step S800, pressure cycle shock, specifically: performing pressure loading and unloading cycle shock on the assembled pressure transmitter.

[0028] According to the present invention of the above scheme, its beneficial effects are at least:

[0029] (1) The pressure transmitter provided by the present invention has a maximum measuring pressure of up to 1000 MPa. The overload capacity of the standard product reaches 3 times the full-scale pressure, and the maximum bursting pressure can reach 20 times.

[0030] (2) The pressure transmitter provided by the present invention adopts a pressure sensing mode of micro-strain of the pressure diaphragm, which avoids the risk of material fatigue deformation, prolongs the working life of the pressure diaphragm, and can withstand 10 million times of 1.5 times full-scale pressure cycle loading.

[0031] (3) The pressure transmitter provided by the present invention uses the pressure sensing full-bridge equivalent resistor as a temperature measuring element to measure the medium temperature more accurately, perform multi-order temperature compensation, greatly reduce the temperature drift coefficient of the transmitter, and improve the measurement accuracy.

[0032] (4) The strain gauge of the pressure transmitter provided by the present invention can collect pressure signals and temperature signals, thereby reducing the temperature collection data error and achieving a better temperature compensation effect.

[0033] (5) The pressure transmitter provided by the present invention has a simple structure, a high degree of automation in the production process, high production efficiency, and realizes mass production. The daily output of a single set of production equipment can reach 3,000 units. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 A schematic cross-sectional structure diagram of a pressure transmitter provided in an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of the enlarged structure of the connection between the pressure diaphragm and the strain gauge in the pressure transmitter provided by an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of the structure of a pressure diaphragm in a pressure transmitter provided in an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the structure of auxiliary silicate coated on the pressure diaphragm in the pressure transmitter provided by an embodiment of the present invention;

[0039] Figure 5 A schematic structural diagram of another perspective of the auxiliary silicate coated on the pressure diaphragm in the pressure transmitter provided by an embodiment of the present invention;

[0040] Figure 6 The manufacturing method of the pressure transmitter provided by the embodiment of the present invention is as follows: Figure 1 ;

[0041] Figure 7A schematic diagram of the positioning structure of a strain gauge in a pressure transmitter provided in an embodiment of the present invention;

[0042] Figure 8 The present invention provides a method for manufacturing a pressure transmitter. Figure 2 .

[0043] Among them, the reference numerals in the figure are:

[0044] DETAILED DESCRIPTION

[0045] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly or indirectly located on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The directions or positions indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the accompanying drawings and are only for the convenience of description and cannot be understood as limitations on the present technical solution. The terms "first" and "second" are only used for the convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0046] In order to solve the technical problems of low pressure resistance, easy fatigue deformation of diaphragm and high temperature drift coefficient in the existing pressure transmitter in the prior art. The present invention aims to provide a pressure transmitter and its manufacturing method, the core idea of ​​which is: a pressure diaphragm 11 made of elastic material and having micro-strain is adopted, the deformation of the pressure diaphragm 11 causes the resistance change of the strain gauge solidified thereon, the amplifier circuit board 13 is used to collect the resistance signal, perform temperature compensation operation on the strain gauge 12, and output the amplified voltage signal, the signal conversion circuit board 14 is used to convert the input amplified voltage signal into the standard signal of the pressure transmitter and output it to the external device. In order to achieve a maximum measurement pressure of up to 1000Mpa, withstand 10 million times of 1.5 times full-scale pressure cycle loading, and greatly reduce the temperature drift coefficient.

[0047] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] See also Figure 1 This embodiment provides a pressure transmitter 10, including:

[0049] A pressure diaphragm 11 is made of high-strength elastic material and has micro-strain. A diaphragm pressure-inducing hole 111 is provided in the pressure diaphragm 11. A flat circular diaphragm 112 is provided at the extended end of the diaphragm pressure-inducing hole 111. The intersection of the flat circular diaphragm 112 and the diaphragm pressure-inducing hole 111 is an arc surface, which increases the pressure resistance of the pressure diaphragm 11 and avoids overload rupture or permanent deformation during the measurement process.

[0050] The strain gauge 12 is solidified on the surface of the planar circular diaphragm 112. The deformation of the planar circular diaphragm 112 causes the resistance of the strain gauge 12 to change (please refer to Figure 2 ).

[0051] The amplifier circuit board 13 is electrically connected to the strain gauge 12 . The amplifier circuit board 13 is used to collect the resistance signal, perform temperature compensation calculation on the strain gauge 12 , and output an amplified voltage signal.

[0052] The signal conversion circuit board 14 is electrically connected to the amplification circuit board 13 . The signal conversion circuit board 14 is used to convert the input amplified voltage signal into a standard signal of the pressure transmitter and output it to an external device electrically connected to the signal conversion circuit board 14 .

[0053] The working principle of the pressure transmitter 10 provided in this embodiment may be:

[0054] The strain gauge 12 can collect pressure signals and temperature signals. When the strain gauge 12 is subjected to pressure, the differential voltage signal will change, and the full-bridge equivalent resistance will remain unchanged; when the strain gauge 12 is subjected to temperature, the differential voltage signal remains basically unchanged, and the full-bridge equivalent resistance changes; the amplifier circuit board 13 collects the differential voltage signal of the strain gauge 12 to obtain the pressure value, and the amplifier circuit board 13 collects the full-bridge equivalent resistance of the strain gauge 12 to obtain the temperature value.

[0055] The amplifier circuit board 13 has a built-in data storage and compensation program, and uses software algorithms to compensate and correct the data correctness. During the production process, the strain gauge 12 collects data at multiple temperature points and multiple pressure points, and the collected data is stored in the data storage. The compensation program calls the characteristic data in the data storage to perform compensation operations on the pressure transmitter 10, reduce the temperature drift coefficient, and optimize the nonlinearity. The specific implementation process can be: during the production process, apply ambient temperatures of -20°C, 25°C, and 70°C to the pressure transmitter 10, and under different ambient temperatures, apply zero pressure, half pressure, and full pressure to the pressure transmitter 10, and record the characteristic data such as the temperature value and pressure value measured by the amplifier circuit board 13, and finally download the recorded characteristic data to the data storage of the amplifier circuit board 13. When the pressure transmitter 10 is working, it first reads the temperature and pressure characteristic data stored in the data storage device, and then compensates and corrects the converted current pressure and temperature values. The basis for compensation and correction is to download the pressure and temperature characteristic data stored in the data storage device when the pressure transmitter 10 is produced. The temperature drift error of the pressure transmitter 10 is first compensated by the temperature drift coefficient interpolation algorithm to reduce the temperature error of the pressure transmitter 10, and then the nonlinearity of the pressure transmitter 10 is corrected by the nonlinearity interpolation algorithm to improve the linearity of the sensor.

[0056] The external medium applies pressure to the pressure diaphragm 11, causing micro-strain to be generated in the strain area of ​​the pressure diaphragm 11, that is, the plane circular diaphragm 112 generates micro-strain, tensile deformation is generated in the center of the strain area, and compression is generated at the edge of the strain area. The micro-strain is transmitted to the strain gauge 12, and the amplifier circuit board 13 provides an excitation power supply to the strain gauge 12. The strain gauge 12 inputs a differential voltage signal to the amplifier circuit board 13, and the amplifier circuit board 13 amplifies the input differential voltage signal. The signal output by the amplifier circuit board 13 is converted into a standard signal of the pressure transmitter by the signal conversion circuit board 14 and output to the external device.

[0057] The beneficial effects of the pressure transmitter 10 provided in this embodiment are at least:

[0058] (1) The pressure transmitter 10 provided in this embodiment adopts high-strength elastic material and anti-overload structure, and the maximum measuring pressure is up to 1000Mpa. The overload capacity of the standard product reaches 3 times the full-scale pressure, and the bursting pressure can reach up to 20 times.

[0059] (2) The pressure transmitter 10 provided in this embodiment adopts a micro-strain pressure sensing mode of the pressure diaphragm 11, thereby avoiding the risk of material fatigue deformation, extending the working life of the pressure diaphragm 11, and being able to withstand 10 million times of 1.5 times full-scale pressure cycle loading.

[0060] (3) The pressure transmitter 10 provided in this embodiment uses the pressure sensing full-bridge equivalent resistor as a temperature measuring element to measure the medium temperature more accurately, perform multi-order temperature compensation, greatly reduce the temperature drift coefficient of the transmitter, and improve the measurement accuracy.

[0061] (4) In the pressure transmitter provided in this embodiment, the strain gauge 12 can collect pressure signals and temperature signals, thereby reducing the temperature collection data error and achieving a better temperature compensation effect.

[0062] (5) The pressure transmitter provided in this embodiment has a simple structure, a high degree of automation in the production process, high production efficiency, and realizes mass production. The daily output of a single set of production equipment can reach 3,000 units.

[0063] Please continue reading Figure 1 Specifically, a buffer plug 16 is provided at the opening of the diaphragm pressure-inducing hole 111. The buffer plug 16 is provided at the opening of the diaphragm pressure-inducing hole 111 and is detachably connected to the pressure diaphragm 11 through the diaphragm pressure-inducing hole 111. The function of the buffer plug 16 is to protect the pressure diaphragm 11. When a pulse pressure such as a water hammer effect occurs during pressure measurement, the buffer plug 16 acts as a buffer to prevent the instantaneous high pressure from damaging the pressure diaphragm 11. Optionally, the buffer plug 16 is threadedly connected to the inner side wall 111 of the diaphragm pressure-inducing hole 111, so that the buffer plug 16 can be firmly connected to the pressure diaphragm 11 and is convenient to disassemble. The buffer plug 16 is provided with a buffer plug pressure-inducing hole 161 that runs through the entire buffer plug 16, and the buffer plug pressure-inducing hole 161 is connected to the diaphragm pressure-inducing hole 111. As a result, the external medium (liquid or gas) flows to the diaphragm pressure-inducing hole 111 through the buffer plug pressure-inducing hole 161 provided on the buffer plug 16, thereby realizing that the external medium enters the diaphragm pressure-inducing hole 111.

[0064] See also Figure 3 , the center thickness T of the plane circular diaphragm 112> , P is the rated pressure of the pressure transmitter test (unit: MPa), and d is the diameter of the diaphragm pressure inlet hole 111. Optionally, the center thickness T of the flat circular diaphragm 112 is 0.18 mm to 3.5 mm. The center thickness T of the flat circular diaphragm 112 is determined by the measured pressure. The greater the pressure, the thicker the center thickness T.

[0065] The diameter d of the diaphragm pressure-inducing hole 111 is 3 mm to 5 mm. Optionally, the diameter d of the diaphragm pressure-inducing hole 111 is 3.3 mm. Under the action of pressure, the plane circular diaphragm 112 produces micro-strain, tensile deformation occurs at the center, and compression deformation occurs in the area d / 2 away from the center (half the diameter of the diaphragm pressure-inducing hole 111).

[0066] The side wall thickness L of the planar circular diaphragm 112 is 3 mm to 8 mm. Optionally, the side wall thickness L of the planar circular diaphragm 112 is 3.35 mm. The side wall thickness L of the planar circular diaphragm 112 supports the central area. The larger the value of the side wall thickness L, the more stable the support to the center, and the higher the stability of the pressure diaphragm 11.

[0067] The outer wall of the pressure diaphragm 11 is provided with a stress blocking groove 113, which is used to block the installation stress from being transmitted to the flat circular diaphragm 112 to eliminate the influence of the installation stress on the measurement accuracy. The inner diameter D of the bottom of the stress blocking groove 113 is 5 mm to 15.2 mm. Optionally, the inner diameter D of the bottom of the stress blocking groove 113 is 7.6 mm. The smaller the inner diameter D of the bottom of the groove, the smaller the measurement error caused by the installation stress.

[0068] Optionally, when used to measure relatively low pressure, a protruding platform (not shown in the figure) is provided at the center of the flat circular diaphragm 112 on the side close to the diaphragm pressure-inducing hole 111 to effectively improve the linearity of low-pressure measurement.

[0069] Specifically, the outer wall of the pressure diaphragm 11 is provided with a process interface 17, which is an integrated structure with the pressure diaphragm 11, achieving no welds, no need for seals, and avoiding leakage risks. Optionally, the pressure diaphragm 11 and the process interface 17 are both integrally processed from stainless steel bars.

[0070] Optionally, the strain gauge 12 is sintered and solidified on the surface of the planar circular diaphragm 112 through the connecting layer 15, and the connecting layer 15 is made of silicate material. The microstrain generated by the pressure diaphragm 11 is transferred to the strain gauge 12 through the connecting layer made of silicate material. Figure 4 and Figure 5The pressure diaphragm 11 is fixedly placed on the base 27, and the prepared steel mesh 18 is covered on the pressure diaphragm 11, and then the silicate is coated on the pressure diaphragm 11. The silicate is coated on the pressure diaphragm 11 by screen printing using the steel mesh 18 to improve the accuracy of the silicate coating position and control the thickness of the silicate coating. The coating operation using the steel mesh 18 screen printing method can improve the consistency of the operation, avoid the problems of inaccurate manual coating position and unqualified coating thickness, and the coating operation using the steel mesh 18 screen printing method has a higher efficiency advantage than manual coating. The pressure diaphragm 11 after screen printing is sintered with silicate in a multi-temperature zone vacuum tunnel furnace, and the strain gauge 12 is solidified on the surface of the pressure diaphragm 11. The role of the silicate is to solidify the strain gauge 12 on the pressure diaphragm 11 and transmit strain between the pressure diaphragm 11 and the strain gauge 12. When the pressure diaphragm 11 is deformed by pressure, the strain gauge 12 generates corresponding strain through the silicate transmission, so that the resistance value of the strain gauge 12 changes. Temperature control and time control are very necessary in the silicate sintering and curing process. The use of a multi-temperature zone vacuum tunnel furnace can make the temperature change in the silicate sintering and curing process smoother, which can effectively avoid the problem of poor sintering caused by sudden cooling and heating. At the same time, the multi-temperature zone vacuum tunnel furnace also avoids the oxidation of the workpiece and improves the yield rate.

[0071] Please continue reading Figure 1 Specifically, the pressure transmitter 10 also includes a housing 19, and the pressure diaphragm 11 is fixedly connected to the housing 19. Optionally, the pressure diaphragm 11 is welded to the housing 19. A circuit board bracket 20 is provided inside the housing 19, and the pressure diaphragm 11 is fixedly connected to the circuit board bracket 20. Optionally, the pressure diaphragm 11 and the circuit board bracket 20 are welded. A bonding circuit board 21 is provided on the circuit board bracket 20, and the bonding circuit board 21 is fixedly connected to the circuit board bracket 20. The function of the circuit board bracket 20 is to fix the bonding circuit board 21 to prevent the bonding circuit board 21 from exerting stress on the pressure diaphragm 11. Optionally, the bonding circuit board 21 is adhered to the circuit board bracket 20 by a high-temperature adhesive 28. An insulating gasket 22 is provided between the bonding circuit board 21 and the circuit board bracket 20, and the insulating gasket 22 is used to protect the bonding circuit board 21 and prevent the bonding circuit board 21 and the circuit board bracket 20 from short-circuiting.

[0072] Specifically, the strain gauge 12 is connected to the bonding circuit board 21 through a wire 23, and the wire 23 is used to transmit signals between the strain gauge 12 and the bonding circuit board 21. Optionally, the wire 23 is an aluminum wire. It should be understood that the wire 23 can also be other, not limited to the above situation, and is not limited here. The bonding circuit board 21 is connected to the amplifying circuit board 13 through a first pin, the amplifying circuit board 13 is connected to the signal conversion circuit board 14 through a second pin, and the signal conversion circuit board 14 is connected to an external device through an electrical connector 24. The electrical connector 24 serves to connect the output signal of the pressure transmitter with the signal of the external device. Optionally, the output end of the signal conversion circuit board 14 is connected to the electrical connector 24 by cable soldering. The outside of the electrical connector 24 is fixedly connected with an electrical connector 25, and the electrical connector 25 is connected to the housing 19. Optionally, the electrical connector 24 is glued to the electrical connector 25, and the electrical connector 25 is welded to the housing 19.

[0073] Specifically, a protective cover 26 is provided on the bonding circuit board 21 to cover the strain gauge 12 and the wire 23, and the protective cover 26 is fixedly connected to the bonding circuit board 21. The setting of the protective cover 26 is used to protect the wire 23 and the strain gauge 12 from being touched, thereby reducing the damage rate during production turnover. Optionally, the protective cover 26 is glued to the center of the bonding circuit board 21. Optionally, the protective cover 26 and the bonding circuit board 21 are glued.

[0074] See also Figure 6 The embodiment of the present invention further provides a method for manufacturing a pressure transmitter, comprising:

[0075] Step S100: Processing the pressure diaphragm 11, specifically: processing the pressure diaphragm 11 according to the design drawings, and placing the processed pressure diaphragm 11 in a vacuum furnace for heat treatment. The vacuum heat treatment prevents the workpiece from being oxidized. The heat-treated pressure diaphragm can withstand 10 million pressure cycle shocks and can measure a maximum pressure of 1000MPa. Grind the heat-treated pressure diaphragm 11 to ensure that the parallelism of the pressure diaphragm 11 meets the preset requirements. Optionally, the parallelism of the ground pressure diaphragm is not greater than 0.005mm.

[0076] Step S200: Silicate screen printing, specifically: fix the qualified pressure diaphragm 11 on the base 27, cover the prepared steel mesh 18 on the pressure diaphragm 11, and place the milky silicate on the steel mesh 18, use a scraper to evenly scrape the silicate along the surface of the steel mesh 18, then take out the steel mesh 18, and remove the pressure diaphragm 11 from the base 27, and the screen printing is completed. The steel mesh 18 needs to be designed according to the size of the strain gauge 12 and the pressure diaphragm 11. The thickness of the steel mesh 18 determines the thickness of the silicate after screen printing, which affects the stability and insulation performance of the pressure sensor. The opening position of the steel mesh 18 determines the assembly position of the strain gauge 12 (please refer to Figure 4 and Figure 5 ).

[0077] Step S300: Positioning the strain gauge 12, specifically: placing the strain gauge 12 in the silicate covered area on the surface of the pressure diaphragm 11 (see Figure 7 ).

[0078] Step S400: Silicate sintering and curing, specifically: load the silk-screened pressure diaphragm 11 into the fixing fixture in batches, put the fixing fixture into the multi-temperature zone vacuum tunnel furnace in turn for silicate sintering, and after the silicate sintering is completed, the silicate solidifies the strain gauge 12 on the surface of the pressure diaphragm 11. Temperature control and time control in the silicate sintering and curing process are very necessary. The use of a multi-temperature zone vacuum tunnel furnace can make the temperature change of the silicate sintering and curing process smoother, which can effectively avoid the problem of poor sintering caused by sudden cooling and heating. At the same time, the multi-temperature zone vacuum tunnel furnace also avoids the oxidation of the workpiece and improves the yield rate. The multi-temperature zone vacuum sintering furnace adopts a chain conveying mechanism. The workpiece is put in at the entrance and taken out at the exit. The furnace temperature of each temperature zone does not need to be adjusted back and forth, which improves the sintering efficiency.

[0079] Step S500, installing the bonding circuit board 21, specifically: welding the circuit board bracket 20 to the pressure diaphragm 11, and then fixing the bonding circuit board 21 to the circuit board bracket 20 by means of high temperature adhesive 28, and baking and curing. The bonding circuit board 21 is fixed to the circuit board bracket 20 by means of high temperature adhesive 28, eliminating the influence of the bonding circuit board 21 on the pressure diaphragm 11 (see Figure 1 ).

[0080] Step S600, circuit assembly, specifically: using an ultrasonic wire bonding machine to weld the two ends of the wire 23 to the strain gauge 12 and the bonding circuit board 21 respectively, and using a protective cover 26 to cover the wire 23 and the strain gauge 12. The setting of the protective cover 26 prevents damage due to touch, and reduces the damage rate during production turnover. Use a first pin to connect the bonding circuit board 21 and the amplifier circuit board 13, use a second plug-in to connect the amplifier circuit board 13 and the signal conversion circuit board 14, and use an electrical connector 24 to connect the signal conversion circuit board 14 to an external device;

[0081] Step S700 , assembling the housing 19 and the electrical connector 25 , specifically: inserting the electrical connector 25 outside the electrical connector 24 , fixing it with glue, and then welding the electrical connector 25 to the housing 19 .

[0082] See also Figure 8After step S700, the method further includes step S800, pressure cycle shock, specifically, performing pressure loading and unloading cycle shock on the assembled pressure transmitter 10. The pressure cycle shock can eliminate the residual stress generated during the machining and workpiece assembly process, and the loading pressure is 2 times the full scale pressure.

[0083] The manufacturing method of the pressure transmitter provided in this embodiment has at least the following beneficial effects:

[0084] The manufacturing method of the pressure transmitter provided in this embodiment has a simple structure, a high degree of automation in the production process, high production efficiency, and mass production. The daily output of a single set of production equipment can reach 3,000 units. The pressure transmitter 10 manufactured by this method has high pressure resistance. The pressure diaphragm 11 after heat treatment can withstand 10 million pressure cycle shocks and can measure 1000MPa pressure. The temperature drift coefficient is low, which improves the measurement accuracy. The pressure diaphragm 11 adopts a micro-strain pressure sensing mode to avoid the risk of material fatigue deformation, extend the working life of the pressure diaphragm 11, and can withstand 10 million times of 1.5 times the full-scale pressure cycle loading.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A pressure transmitter (10), characterized in that: include: A pressure diaphragm (11) made of elastic material and having micro-strain, wherein a diaphragm pressure induction hole (111) is provided in the pressure diaphragm (11), a flat circular diaphragm (112) is provided at an extended end of the diaphragm pressure induction hole (111), and a stress blocking groove (113) is provided on the outer wall of the pressure diaphragm (11), wherein the stress blocking groove (113) is used to block the transmission of installation stress to the flat circular diaphragm (112); when used to measure relatively low pressure, a protruding platform is provided at the center of the flat circular diaphragm (112) on a side close to the diaphragm pressure induction hole (111) to improve the linearity during low pressure measurement; The strain gauge (12) is sintered and solidified on the surface of the planar circular diaphragm (112) through a connection layer (15) made of a silicate material, and the deformation of the planar circular diaphragm (112) causes the resistance of the strain gauge (12) to change; wherein the silicate is screen-printed on the pressure diaphragm (11) using a steel mesh (18) in the following manner: a qualified pressure diaphragm (11) is fixed on a base (27), a prepared steel mesh (18) is covered on the pressure diaphragm (11), and a milky silicate is placed on the steel mesh (18), and the silicate is evenly scraped along the surface of the steel mesh (18) with a scraper, and then the steel mesh (18) is removed, and the pressure diaphragm (11) is removed from the base (27); an amplifying circuit board (13), electrically connected to the strain gauge (12), the amplifying circuit board (13) being used to collect resistance signals, perform temperature compensation calculations on the strain gauge (12), and output an amplified voltage signal; A signal conversion circuit board (14) is electrically connected to the amplifying circuit board (13), and the signal conversion circuit board (14) is used to convert the input amplified voltage signal into a standard signal of the pressure transmitter, and output it to an external device electrically connected to the signal conversion circuit board (14); A housing (19), the pressure diaphragm (11) is fixedly connected to the housing (19), a circuit board bracket (20) is provided inside the housing (19), the pressure diaphragm (11) is fixedly connected to the circuit board bracket (20), and the contact surface of the two is farther away from the flat circular diaphragm (112) than the stress blocking groove (113), a bonding circuit board (21) is fixedly connected to the circuit board bracket (20), and an insulating gasket (22) is provided between the bonding circuit board (21) and the circuit board bracket (20), and the insulating gasket (22) is used to protect the bonding circuit board (21) to prevent the bonding circuit board (21) and the circuit board bracket (20) from short-circuiting; the strain gauge (12) is connected to the bonding circuit board (21) via a wire (23), and the wire (23) is used to transmit signals between the strain gauge (12) and the bonding circuit board (21); a protective cover (26) is provided on the bonding circuit board (21) to cover the strain gauge (12) and the wire (23), and the protective cover (26) is fixedly connected to the bonding circuit board (21).

2. The pressure transmitter according to claim 1, characterized in that: A buffer plug (16) is provided at the opening of the diaphragm pressure-inducing hole (111); the buffer plug (16) is provided at the opening of the diaphragm pressure-inducing hole (111) and is detachably connected to the pressure diaphragm (11) through the diaphragm pressure-inducing hole (111); the buffer plug (16) is provided with a buffer plug pressure-inducing hole (161) that passes through the entire buffer plug (16); the buffer plug pressure-inducing hole (161) is in communication with the diaphragm pressure-inducing hole (111).

3. The pressure transmitter according to claim 1, characterized in that: The outer side wall of the pressure diaphragm (11) is provided with a process interface (17), and the process interface (17) and the pressure diaphragm (11) are an integrated structure.

4. The pressure transmitter according to claim 1, characterized in that: The bonding circuit board (21) is connected to the amplifying circuit board (13) via a first pin, the amplifying circuit board (13) is connected to the signal conversion circuit board (14) via a second pin, and the signal conversion circuit board (14) is connected to an external device via an electrical connector (24); An electrical connector (25) is fixedly connected to the outside of the electrical connector (24), and the electrical connector (25) is connected to the housing (19).

5. A method for manufacturing a pressure transmitter according to any one of claims 1 to 4, characterized in that: include: Step S100: processing the pressure diaphragm (11), specifically: processing the pressure diaphragm (11) according to the design drawing, placing the processed pressure diaphragm (11) in a vacuum furnace for heat treatment, and grinding the heat-treated pressure diaphragm (11) to ensure that the parallelism of the pressure diaphragm (11) meets the preset requirements; Step S200: silicate screen printing, specifically: fixing a qualified pressure diaphragm (11) on a base (27), covering the prepared steel mesh (18) on the pressure diaphragm (11), placing a milky silicate on the steel mesh (18), scraping the silicate evenly along the surface of the steel mesh (18) with a scraper, then taking out the steel mesh (18), and removing the pressure diaphragm (11) from the base (27); Step S300: positioning the strain gauge (12), specifically: placing the strain gauge (12) in the silicate covered area on the surface of the pressure diaphragm (11); Step S400: silicate sintering and curing, specifically: loading the silk-screened pressure diaphragm (11) into a fixing fixture in batches, and sequentially placing the fixing fixture into a multi-temperature zone vacuum tunnel furnace for silicate sintering. After the silicate sintering is completed, the silicate solidifies the strain gauge (12) on the surface of the pressure diaphragm (11); Step S500, installing the bonding circuit board (21), specifically: welding the circuit board bracket (20) and the pressure diaphragm (11), then fixing the bonding circuit board (21) on the circuit board bracket (20) by means of high-temperature adhesive (28), and baking and curing; Step S600, circuit assembly, specifically: using an ultrasonic wire bonding machine to weld the two ends of the wire (23) to the strain gauge (12) and the bonding circuit board (21) respectively, and using a protective cover (26) to cover the wire (23) and the strain gauge (12); using a first pin to connect the bonding circuit board (21) and the amplifying circuit board (13), using a second plug-in to connect the amplifying circuit board (13) and the signal conversion circuit board (14), and using an electrical connector (24) to connect the signal conversion circuit board (14) and an external device; Step S700, assembling the housing (19) and the electrical connector (25), specifically: inserting the electrical connector (25) outside the electrical connector (24), fixing it with glue, and then welding the electrical connector (25) to the housing (19).

6. The method for manufacturing a pressure transmitter according to claim 5, characterized in that: After step S700, the method further includes step S800, pressure cycle shock, specifically: performing pressure loading and unloading cycle shock on the assembled pressure transmitter (10).

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