A small pressure transmitter

Abstract

This invention relates to the field of pressure transmitter technology and discloses a small pressure transmitter, including a housing and a circuit board, a signal generator, an isolation diaphragm, and a measuring diaphragm installed inside the housing. It also includes an isolation chamber, with the isolation diaphragm and measuring diaphragm fixedly connected within the housing. An isolation chamber filled with sealing fluid is formed between the isolation diaphragm and the measuring diaphragm, preventing the pressure of the measured medium from directly contacting and impacting the signal generator. An isolation plate is provided at the upper end of the housing, and the upper end of the isolation plate is sealed with a glue block formed by potting. A connecting pipe is provided at the upper end of the housing, and a threaded connecting pipe is integrally formed at the lower end of the housing. This small pressure transmitter can effectively isolate high temperatures and prevent clogging. Furthermore, it can be modularly assembled according to different media, thus providing a modular solution for easy disassembly and calibration of the transmitter, meeting the comprehensive requirements of high reliability, easy maintenance, and economy.

Description

Technical Field

[0001] This invention relates to the field of pressure transmitter technology, specifically a small pressure transmitter. Background Technology

[0002] Pressure transmitters are indispensable core sensors in industrial process control. They sense pressure changes and convert them into standard electrical signals to achieve real-time monitoring of fluid (liquid or gas) pressure in pipelines, containers, and other equipment. However, in practical applications, especially in industries such as petroleum, chemical, pharmaceutical, and energy, pressure transmitters face two major challenges. First, high-temperature media pose a significant threat to the reliability of the transmitters. When measuring steam, high-temperature oil, or reactive materials, the high temperature of the process medium (usually exceeding 100°C or even 200°C) is directly conducted to the sensor core of the transmitter through the process connectors. Long-term high-temperature operation will accelerate the aging and denaturation of the internal filling fluid, causing changes in its bulk modulus and introducing unpredictable measurement errors. At the same time, high temperatures will also cause irreversible thermal damage to the electronic components and sealing materials (such as O-rings) inside the sensor, significantly shortening the transmitter's service life and even leading to permanent failure. Secondly, traditional transmitters are usually connected to the system pipeline using threads or flanges with pressure taps. These tiny holes and cavities are easily blocked by polymers, crystals, or particles, preventing pressure from being effectively transmitted to the sensor and causing measurement failure. Maintenance personnel must frequently perform time-consuming and laborious cleaning work, and may even need to remove the entire transmitter from the pipeline, seriously affecting production continuity and increasing maintenance costs.

[0003] To cope with high-temperature operating conditions, existing technologies typically employ two solutions: First, using transmitters with higher temperature ratings, but this is extremely expensive and still has an upper limit; second, adding independent heat sinks or condensation bends, the latter having some effect but increasing system complexity and potential leakage points, and failing to solve the clogging problem. To address the clogging issue, the industry commonly uses enlarged pressure taps; however, while this can alleviate clogging, fluctuations in medium pressure increase the impact on core sensor components, and still cannot avoid the problem of high-temperature conduction. Summary of the Invention

[0004] Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a small pressure transmitter that solves the problems of the core sensor core of the pressure transmitter aging and denaturation due to long-term high-temperature operation, which leads to changes in its bulk modulus and introduces unpredictable measurement errors, as well as the problem that the tiny holes and cavities on the transmitter are easily blocked by crystals or particles formed by the medium at high temperatures.

[0006] Technical solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a small pressure transmitter, comprising a housing and a circuit board, a signal generator, an isolation diaphragm, and a measuring diaphragm installed within the housing, and further comprising:

[0008] An isolation chamber is formed between the isolation diaphragm and the measuring diaphragm, which are both fixedly connected inside the housing. The isolation chamber is filled with sealing fluid, so that the pressure of the measured medium cannot directly contact and impact the signal generator. An isolation plate is provided at the upper end of the housing, and the upper end of the isolation plate is sealed by forming a glue block through glue injection.

[0009] The housing has a connecting pipe at its upper end and a threaded connector integrally formed at its lower end. The upper end of the connecting pipe is connected to the threaded connector. The lower end of the housing has an external threaded pipe with the same thread structure as the threaded connector. Multiple extension pipes for heat dissipation and cooling are installed between the external threaded pipe and the connecting pipe. The temperature of the measured medium can be effectively reduced through the extension pipes.

[0010] As a further description of the above technical solution, the housing is internally threaded with a locking nut, the lower end of the locking nut is provided with a fixing part, the circuit board is fixedly mounted on the fixing part, the locking nut is provided with a round hole for the signal line installed on the circuit board to pass through, the isolation plate is provided with a vent tube, the lower end of the vent tube is provided with a waterproof and breathable sticker, and the isolation plate is provided with a wire through hole for the signal line to pass through.

[0011] The housing has a step with a slot. The isolation diaphragm is sealed in the slot. A fixing frame is provided on the step. The upper end of the fixing frame has a support part that contacts the lower end of the locking nut. The lower end of the fixing frame presses against the upper end of the isolation diaphragm. The signal generator is installed at the lower end of the fixing frame and contacts the isolation diaphragm.

[0012] As a further description of the above technical solution, a cylindrical damper is provided inside the threaded pipe, a channel is provided at the center of the damper, and multiple bypass holes are opened circumferentially around the channel, and a baffle plate is fixedly connected inside the isolation cavity.

[0013] As a further description of the above technical solution, the upper end of the connecting pipe is provided with an annular base, the annular base is in contact with the lower end of the shell, the lower end of the shell is fixedly connected with a sealing gasket through an annular groove, the upper end of the annular base is provided with a groove that matches the sealing gasket, and the edge of the annular base is provided with a flange that matches the outer diameter of the shell.

[0014] As a further description of the above technical solution, the side wall of the threaded connector is provided with a smooth surface, the diameter of which is smaller than the outer diameter of the threaded connector, and the inner wall of the threaded connector is fitted with a sealing ring through an annular groove, the sealing ring being sleeved with the smooth surface on the threaded connector.

[0015] As a further description of the above technical solution, the connecting pipe has a first threaded hole on its wall, and a venting bolt is threaded into the first threaded hole. The external threaded pipe has a second threaded hole on its wall, and a sealing bolt is threaded into the second threaded hole. Both the venting bolt and the sealing bolt are provided with sealing gaskets.

[0016] As a further description of the above technical solution, a circular plate is fixedly connected inside the connecting pipe, and multiple circular holes are opened on the side wall of the circular plate. A guide post is sleeved at the center of the circular plate through a guide hole. A cross is fixedly connected to the upper end of the guide post. A ring is fixedly connected to the cross, and multiple semi-circular vents are opened at the upper end of the ring. A sealing plate is fixedly connected to the lower end of the guide post. A rubber pad is fixedly connected to the upper end of the sealing plate, and two annular protrusions are provided at the upper end of the rubber pad. A spring is sleeved on the side wall of the guide post. The upper end of the spring contacts the lower end of the cross, and the lower end of the spring contacts the upper end of the circular plate.

[0017] As a further description of the above technical solution, a cover is fixedly connected to the opposite sides of the shell. One side of each of the two covers extends into the shell and is fixedly connected to a heat-conducting plate by bolts. The heat-conducting plate is disposed on one side of multiple extension tubes for timely discharge of the temperature of the measured medium inside the extension tubes. The upper and lower ends of the shell are sealed structures. The upper end of the extension tube passes through the upper end of the shell and is connected to the heat-conducting plate. As a further description of the above technical solution, two thermoelectric cooling elements are fixedly connected to one side of the heat-conducting plate. A rectangular plate is fixedly connected to one side of the cover. Two miniature fans are fixedly connected to one side of the rectangular plate. A temperature measuring element is fixedly connected to the upper end of the shell.

[0018] As a further description of the above technical solution, multiple fins are fixedly connected to the walls of the multiple extension tubes, and copper sheets are fixedly connected to both sides of the multiple fins. One side of the copper sheet is in contact with the heat-conducting plate, and thermal grease is applied at the joint.

[0019] Beneficial effects

[0020] Compared with the prior art, the present invention provides a small pressure transmitter with the following advantages:

[0021] 1. This invention miniaturizes the pressure transmitter structure and directly seals the inlet of the housing with the measuring diaphragm, preventing the measured medium from entering the housing. Furthermore, the bottom of the housing is nearly flush, preventing malfunctions such as pressure port blockage during measurement. Simultaneously, the measuring diaphragm is in direct contact with the measured medium, transmitting pressure non-destructively to the sensor chip of the signal generator through the filling fluid. This isolates the sensor chip from the measured medium, preventing corrosion, blockage, or contamination. Moreover, the separate design of the signal generator and circuit board, with a certain space between them, allows the filling fluid to provide some cooling, preventing damage to the electronic components on the circuit board.

[0022] 2. When the measured medium passes through the extension tube, the temperature of the medium is transferred to the outside through the extension tube, fins, copper sheet and heat conduction plate, achieving a natural cooling effect. In addition, the airflow on the surface of the heat conduction plate can be accelerated by the micro fan, so that the heat can be dissipated into the air in time, thereby achieving a rapid cooling effect. When the temperature is too high, the thermoelectric cooling element can be turned on. The thermoelectric cooling element is a semiconductor cooling chip, with the cold side attached to the surface of the heat conduction plate, which can achieve efficient cooling at high temperatures and cope with the temperature fluctuation of the measured medium.

[0023] 3. When using the extension tube, the housing is installed on the connecting tube via a threaded connector. At this time, the lower end of the threaded connector presses down on the ring, causing the guide post to move downward. As the guide post moves downward, the sealing plate and rubber gasket move away from the circular plate, allowing the medium to pass through the circular hole on the circular plate and contact the measuring diaphragm. When the pressure transmitter is removed, the threaded connector moves upward. Under the action of the spring, the sealing plate and rubber gasket move upward to contact the lower end of the circular plate, preventing the medium from passing through the circular hole. This achieves a sealing effect. During the upward movement, the smooth surface of the threaded connector remains in contact with the sealing ring. When the sealing plate is not in contact with the circular plate, it achieves a sealing effect, preventing the measured medium inside from being ejected. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a small pressure transmitter proposed in this invention;

[0025] Figure 2 This is a schematic diagram of a small pressure transmitter mounted on a housing according to the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of the housing and extension tube in a small pressure transmitter proposed in this invention. Figure 1 ;

[0027] Figure 4 This is a schematic diagram of the structure of the housing and extension tube in a small pressure transmitter proposed in this invention. Figure 2 ;

[0028] Figure 5This is a schematic diagram of the structure of the housing and cover in a small pressure transmitter proposed in this invention;

[0029] Figure 6 This is a schematic diagram of the structure of the housing, heat-conducting plate, and thermoelectric cooling element in a small pressure transmitter proposed in this invention.

[0030] Figure 7 This is a schematic diagram of the structure of the housing and connecting pipe in a small pressure transmitter proposed in this invention. Figure 1 ;

[0031] Figure 8 This is a schematic diagram of the structure of the housing and connecting pipe in a small pressure transmitter proposed in this invention. Figure 2 ;

[0032] Figure 9 This is a schematic diagram of the housing structure in a small pressure transmitter proposed in this invention;

[0033] Figure 10 This is a schematic diagram of the damper structure in a small pressure transmitter proposed in this invention;

[0034] Figure 11 This is a schematic diagram of the structure of the ring, circular plate, sealing plate, guide column and spring in a small pressure transmitter proposed in this invention.

[0035] In the diagram: 1. Housing; 2. Threaded connector; 3. Rubber block; 4. Signal line; 5. Vent pipe; 6. Connecting pipe; 7. Outer shell; 8. Rectangular plate; 9. Cover; 10. External threaded pipe; 11. Sealing bolt; 12. Extension pipe; 13. Miniature fan; 14. Vent bolt; 15. Ring; 16. Circular plate; 17. Sealing plate; 18. Copper sheet; 19. Annular base; 20. Temperature sensing element; 21. Thermoelectric cooling element; 22. Heat-conducting plate; 23. Isolation chamber; 24. Baffle plate; 25. Sealing gasket; 26. Damper; 27. Sealing ring; 28. Measuring diaphragm; 29. ​​Spring; 30. Guide post; 31. Signal generator; 32. Circuit board; 33. Locking nut; 34. Step; 35. Isolation diaphragm; 36. Fixing bracket; 37. Isolation plate. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example:

[0038] See attached document Figure 1-11 This invention provides a small pressure transmitter that can be assembled in parts. The assembly method can be freely selected according to the different measured media. The short-distance, miniaturized assembly method can be used for measured media at low temperatures of 0°C-80°C. The specific technical solution of the pressure transmitter is as follows:

[0039] The pressure transmitter structure includes a housing 1 and a circuit board 32, a signal generator 31, an isolation diaphragm 35, and a measuring diaphragm 28 installed inside the housing 1. Both the isolation diaphragm 35 and the measuring diaphragm 28 are fixedly connected inside the housing 1. An isolation cavity 23 filled with sealing fluid is formed between the isolation diaphragm 35 and the measuring diaphragm 28. The isolation cavity 23 is filled with high-purity, chemically stable silicone oil or fluorinated oil, transmitting the pressure borne by the external measuring diaphragm 28 to the internal signal generator 31 without loss, preventing the pressure of the measured medium from directly contacting and impacting the signal generator 31. An isolation plate 37 is provided at the upper end of the housing 1. The upper end of the isolation plate 37 is sealed by a glue block 3 formed by potting adhesive. The potting adhesive can be a synthetic resin material. A locking nut 33 is threaded inside the housing 1, and a locking nut 33 is provided at its lower end. The circuit board 32 is fixedly mounted on the fixing part. The locking nut 33 has a round hole for the signal line 4 installed on the circuit board 32 to pass through. The isolation plate 37 is equipped with a vent tube 5, and the lower end of the vent tube 5 is provided with a waterproof and breathable sticker. The isolation plate 37 is provided with a wire through hole for the signal line 4 to pass through. The signal generator 31 is made of single-crystal silicon material and is the core component for sensing pressure and generating electrical signals. It senses the pressure transmitted from the internal silicone oil. The signal generator 31 is separately packaged and designed to be separate from the circuit board 32 and connected by a busbar, so that the signal generator 31 can withstand higher temperatures and keeps the circuit board 32 away from the measured medium to avoid damage to the electronic components on the circuit board 32, such as analog-to-digital converters, filter circuits and microprocessors, due to excessive temperature.

[0040] A step 34 is provided inside the housing 1, and a slot is provided on the step 34. An isolation diaphragm 35 is sealed and connected in the slot. The isolation diaphragm 35 is directly welded to the slot using laser welding technology. Both the isolation diaphragm 35 and the measuring diaphragm 28 are made of elastic thin metal sheets, typically 316L stainless steel, Hastelloy, or tantalum. A fixing bracket 36 is provided on the step 34. A support part is provided at the upper end of the fixing bracket 36. The support part contacts the lower end of the locking nut 33. The lower end of the fixing bracket 36 presses against the upper end of the isolation diaphragm 35. The signal generator 31 is installed at the lower end of the fixing bracket 36 and contacts the isolation diaphragm 35. A cylindrical damper 26 is provided inside the threaded connector 2. A channel with a diameter of 3mm is provided at the center of the damper 26. Multiple bypass holes are provided around the center. The bypass holes are made by drilling holes at a 15° angle at both ends of the damper 26, forming an inflection point at the connection. A baffle plate 24 is fixedly connected inside the isolation cavity 23. An annular base 19 is provided at the upper end of the connecting pipe 6. The annular base 19 contacts the lower end of the housing 1. A sealing gasket 25 is fixedly connected to the lower end of the housing 1 through an annular groove. A groove that matches the sealing gasket 25 is provided at the upper end of the annular base 19. A flange that matches the outer diameter of the housing 1 is provided at the edge of the annular base 19. A smooth part is provided on the side wall of the threaded pipe 2. The diameter of the smooth part is smaller than the outer diameter of the threaded pipe 2. A sealing ring 27 is embedded in the inner wall of the threaded connecting pipe 6 through an annular groove. The sealing ring 27 is sleeved with the smooth part on the threaded pipe 2.

[0041] As described above, this invention miniaturizes the pressure transmitter and directly seals the inlet of the housing 1 with the measuring diaphragm 28, preventing the measured medium from entering the housing 1 (traditionally, the medium needs to enter the device through a pressure inlet to contact the sensitive element in order to measure pressure changes). Furthermore, the bottom of the housing 1 is nearly flush, preventing malfunctions such as pressure inlet blockage during measurement. Simultaneously, the measuring diaphragm 28 directly contacts the measured medium, transmitting the pressure non-destructively to the sensor chip of the signal generator 31 through the filling liquid. This isolates the sensor chip from the measured medium, preventing corrosion, blockage, or contamination. Moreover, the separate design of the signal generator 31 and the circuit board 32, with a certain space between them, allows the filling liquid to provide some cooling, preventing damage to the electronic components on the circuit board 32.

[0042] During measurement, the pressure of the measured medium acts on the measuring diaphragm 28. The deformation of the diaphragm squeezes the filling liquid in the isolation chamber 23, and the filling liquid transmits the pressure to the isolation diaphragm 35. The sensor chip senses the deformation of the silicon diaphragm and generates a change in the resistance of the piezoresistor. The millivolt signal is output through the Wheatstone bridge. The millivolt signal, combined with the temperature data, is sent to the ASIC for amplification, temperature compensation, and linearization. Finally, a standard signal (such as 4-20mA) is output.

[0043] like Figures 3-6and Figure 11 As shown, the long-distance assembly method can be used for measured media with high temperatures of 80°C-150°C. The specific technical solution of the pressure transmitter is as follows: A connecting pipe 6 is provided at the upper end of the housing 7, and a threaded connecting pipe 2 is integrally formed at the lower end of the housing 1. The upper end of the connecting pipe 6 is connected to the threaded connecting pipe 2. An external threaded pipe 10 with the same thread structure as the threaded connecting pipe 2 is provided at the lower end of the housing 7. Multiple extension pipes 12 for heat dissipation and cooling are installed between the external threaded pipe 10 and the connecting pipe 6. The inner diameter of the extension pipe 12 is 5mm and the wall thickness is 2mm. The temperature of the measured medium can be effectively reduced through the extension pipes 12. The specific technical solution is as follows:

[0044] Covers 9 are fixedly connected to opposite sides of the housing 1. One side of each cover 9 extends into the housing 7 and is fixedly connected to a heat-conducting plate 22 by bolts. The heat-conducting plate 22 is set on one side of multiple extension tubes 12 to promptly discharge the temperature of the measured medium inside the extension tubes 12. Both the upper and lower ends of the housing 7 are sealed structures. The upper end of the extension tube 12 passes through the upper end of the housing 7 and communicates with the connecting pipe 6. The lower end of the extension tube 12 passes through the lower end of the housing 7 and communicates with the external threaded pipe 10.

[0045] Two thermoelectric cooling elements 21 are fixedly connected to one side of the heat-conducting plate 22. A rectangular plate 8 is fixedly connected to one side of the cover 9. Two miniature fans 13 are fixedly connected to one side of the rectangular plate 8. A temperature measuring element 20 is fixedly connected to the upper end of the shell 1. The temperature measuring element 20 is a temperature sensor used to directly measure the temperature of the medium after cooling, as a signal to start different cooling modes. Multiple fins are fixedly connected to the walls of multiple extension tubes 12. Copper sheets 18 are fixedly connected to both sides of the multiple fins. One side of the copper sheet 18 is in contact with the heat-conducting plate 22, and thermal grease is applied at the joint.

[0046] like Figure 3 and Figure 4 As shown, when the measured medium passes through the extension tube 12, the temperature of the medium is ultimately transferred to the outside through the extension tube 12, fins, copper sheet 18, and heat-conducting plate 22, achieving a natural cooling effect. Furthermore, the micro fan 13 accelerates the airflow on the surface of the heat-conducting plate 22, allowing heat to be dissipated into the air in a timely manner, thus achieving a rapid cooling effect. When the temperature is too high, the thermoelectric cooling element 21 can be activated. The thermoelectric cooling element 21 is a semiconductor refrigeration chip. When direct current passes through a thermocouple composed of two different semiconductor materials connected in series, heat can be absorbed and released at the two ends of the thermocouple, achieving the purpose of cooling. Here, the cold side is attached to the surface of the heat-conducting plate 22, which can achieve efficient cooling at high temperatures and cope with temperature fluctuations of the measured medium.

[0047] A first threaded hole is provided on the wall of the connecting pipe 6, and a venting bolt 14 is connected to the inner thread of the first threaded hole. A second threaded hole is provided on the wall of the external threaded pipe 10, and a sealing bolt 11 is connected to the inner thread. Both the venting bolt 14 and the sealing bolt 11 are provided with sealing gaskets.

[0048] like Figure 3 As shown, after initial installation or disassembly and maintenance, due to the presence of air inside the extension tube 12, direct installation will result in compressible air inside. A large amount of air will affect the pressure of the final medium contacting the measuring diaphragm 28. Therefore, the residual air in the extension tube 12 can be discharged during assembly by using the venting bolt 14, so that the medium can directly contact the measuring diaphragm 28.

[0049] Secondly, a circular plate 16 is fixedly connected inside the connecting pipe 6, and multiple circular holes are opened on the side wall of the circular plate 16. A guide post 30 is sleeved at the center of the circular plate 16 through a guide hole. A cross is fixedly connected to the upper end of the guide post 30. A ring 15 is fixedly connected to the cross, and multiple semi-circular vents are opened at the upper end of the ring 15. A sealing plate 17 is fixedly connected to the lower end of the guide post 30. A rubber pad is fixedly connected to the upper end of the sealing plate 17, and two annular protrusions are provided at the upper end of the rubber pad. A spring 29 is sleeved on the side wall of the guide post 30. The upper end of the spring 29 contacts the lower end of the cross, and the lower end of the spring 29 contacts the upper end of the circular plate 16.

[0050] like Figure 7 and Figure 8 As shown, when using the extension tube 12, the housing 1 is installed on the connecting tube 6 through the threaded connector 2. At this time, the lower end of the threaded connector 2 presses down on the ring 15, causing the guide post 30 to move down. When the guide post 30 moves down, the sealing plate 17 and the rubber pad move away from the circular plate 16. At this time, the medium can pass through the circular hole on the circular plate 16 and contact the measuring diaphragm 28. When the pressure transmitter is removed, the threaded connector 2 moves up. Under the action of the spring 29, the sealing plate 17 and the rubber pad move up and contact the lower end of the circular plate 16, preventing the medium from passing through the circular hole. This can achieve the sealing effect. During the upward movement, the smooth surface on the threaded connector 2 remains in contact with the sealing ring 27. When the sealing plate 17 and the circular plate 16 are not in contact, it can achieve the sealing effect and prevent the measured medium inside from being ejected.

[0051] It should be noted that the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A small pressure transmitter, comprising a housing (1) and a circuit board (32), a signal generator (31), an isolation diaphragm (35), and a measuring diaphragm (28) mounted within the housing (1), characterized in that, Also includes: The isolation chamber (23) is fixedly connected to the isolation diaphragm (35) and the measuring diaphragm (28) in the housing (1). An isolation chamber (23) filled with sealing liquid is formed between the isolation diaphragm (35) and the measuring diaphragm (28) so that the pressure of the measured medium cannot directly contact and impact the signal generator (31). An isolation plate (37) is provided at the upper end of the housing (1). The upper end of the isolation plate (37) is sealed by forming a glue block (3) through glue injection. The outer shell (7) has a connecting pipe (6) at its upper end. A first threaded hole is provided on the wall of the connecting pipe (6), and a vent bolt (14) is threaded into the first threaded hole. A second threaded hole is provided on the wall of the external threaded pipe (10), and a sealing bolt (11) is connected inside it. Both the vent bolt (14) and the sealing bolt (11) are provided with sealing gaskets. A threaded connector (2) is integrally formed at the lower end of the outer shell (1). The upper end of the connecting pipe (6) is connected to the threaded connector (2). A circular plate (16) is fixedly connected inside the connecting pipe (6), and multiple circular holes are provided on the side wall of the circular plate (16). A guide post (30) is sleeved at the center of the circular plate (16) through a guide hole. A cross is fixedly connected to the upper end of the guide post (30). A ring (15) is fixedly connected to the cross. The upper end of the ring (15) is provided with multiple semi-circular openings for venting. A sealing plate (17) is fixedly connected to the lower end of the guide post (30). A rubber pad is fixedly connected to the upper end of the sealing plate (17). The upper end of the rubber pad is provided with two annular protrusions. A spring (29) is sleeved on the side wall of the guide post (30). The upper end of the spring (29) contacts the lower end of the cross. The lower end of the spring (29) contacts the upper end of the circular plate (16). The lower end of the outer shell (7) is provided with an external threaded pipe (10) with the same thread structure as the threaded connector (2). Multiple extension pipes (12) for heat dissipation and cooling are installed between the external threaded pipe (10) and the connecting pipe (6). The temperature of the measured medium can be effectively reduced through the extension pipes (12).

2. The miniature pressure transmitter according to claim 1, characterized in that: The housing (1) is internally threaded with a locking nut (33). The lower end of the locking nut (33) is provided with a fixing part. The circuit board (32) is fixedly installed on the fixing part. The locking nut (33) has a round hole for the signal line (4) installed on the circuit board (32) to pass through. The isolation plate (37) is equipped with a vent pipe (5). The lower end of the vent pipe (5) is provided with a waterproof and breathable sticker. The isolation plate (37) is provided with a wire through hole for the signal line (4) to pass through. The housing (1) is provided with a step (34), and a slot is provided on the step (34). The isolation diaphragm (35) is sealed and connected in the slot. A fixing frame (36) is provided on the step (34). A support part is provided at the upper end of the fixing frame (36). The support part is in contact with the lower end of the locking nut (33). The lower end of the fixing frame (36) presses against the upper end of the isolation diaphragm (35). The signal generator (31) is installed at the lower end of the fixing frame (36) and is in contact with the isolation diaphragm (35).

3. A small pressure transmitter according to claim 1, characterized in that: The threaded connector (2) is provided with a columnar damper (26), the damper (26) has a channel at its center and multiple bypass holes are provided around the channel, and a baffle plate (24) is fixedly connected inside the isolation cavity (23).

4. A small pressure transmitter according to claim 1, characterized in that: The upper end of the connecting pipe (6) is provided with an annular base (19), which is in contact with the lower end of the housing (1). The lower end of the housing (1) is fixedly connected with a sealing gasket (25) through an annular groove. The upper end of the annular base (19) is provided with a groove that matches the sealing gasket (25). The edge of the annular base (19) is provided with a flange that matches the outer diameter of the housing (1).

5. A small pressure transmitter according to claim 1, characterized in that: The threaded connector (2) has a smooth surface on its side wall. The diameter of the smooth surface is smaller than the outer diameter of the threaded connector (2). The inner wall of the connecting pipe (6) is fitted with a sealing ring (27) through an annular groove. The sealing ring (27) is sleeved with the smooth surface on the threaded connector (2).

6. A miniature pressure transmitter according to claim 1, characterized in that: The shell (1) is fixedly connected to the opposite sides of the cover (9). One side of each of the two covers (9) extends into the shell (7) and is fixedly connected to a heat-conducting plate (22) by bolts. The heat-conducting plate (22) is set on one side of multiple extension tubes (12) to timely discharge the temperature of the measured medium in the extension tube (12). The upper and lower ends of the shell (7) are sealed structures. The upper end of the extension tube (12) passes through the upper end of the shell (7) and communicates with the connecting pipe (6). The lower end of the extension tube (12) passes through the lower end of the shell (7) and communicates with the external threaded pipe (10).

7. A miniature pressure transmitter according to claim 6, characterized in that: Two thermoelectric cooling elements (21) are fixedly connected to one side of the heat-conducting plate (22), a rectangular plate (8) is fixedly connected to one side of the cover (9), two miniature fans (13) are fixedly connected to one side of the rectangular plate (8), and a temperature measuring element (20) is fixedly connected to the upper end of the outer shell (7).

8. A miniature pressure transmitter according to claim 6, characterized in that: Multiple fins are fixedly connected to the walls of the multiple extension tubes (12), and copper sheets (18) are fixedly connected to the opposite sides of the multiple fins. One side of the copper sheet (18) is in contact with the heat-conducting plate (22), and thermal grease is applied at the joint.

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