Small pressure transmitter

Abstract

The invention relates to the technical field of pressure transmitters, and discloses a small pressure transmitter, which comprises a shell, a circuit board, a signal generator, an isolation diaphragm and a measurement diaphragm which are arranged in the shell, and an isolation cavity, the isolation diaphragm and the measurement diaphragm are fixedly connected in the shell, an isolation cavity filled with sealing liquid is formed between the isolation diaphragm and the measuring diaphragm, so that the pressure of a measured medium cannot be in direct contact with and impact the signal generator, an isolation plate is arranged at the upper end of the shell, the upper end of the isolation plate is sealed by forming a glue block through glue pouring, and a connecting pipe is arranged at the upper end of the shell; a threaded connection pipe is integrally formed at the lower end of the shell. According to the small pressure transmitter, high temperature can be effectively isolated, blockage can be prevented, modular assembly can be carried out according to different media, a modular solution convenient for quick disassembly and verification of the transmitter can be further provided, and the comprehensive requirements of high reliability, easy maintainability and economical efficiency are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pressure transmitters, in particular to a small pressure transmitter. BACKGROUND

[0002] The pressure transmitter is an indispensable core sensor in industrial process control, which converts the pressure change into a standard electrical signal to realize real-time monitoring of the fluid (liquid, gas) pressure in the pipeline, container and other equipment. However, in practical applications, especially in the oil, chemical, pharmaceutical, energy and other industries, the pressure transmitter faces two major challenges. First, high-temperature media pose a great threat to the reliability of the transmitter. When measuring steam, high-temperature oil or reaction materials, the high temperature (usually more than 100°C or even 200°C) of the process medium will be directly conducted to the sensor core of the transmitter through the process connection. Long-term high-temperature work will accelerate the aging and denaturation of the internal filling liquid, causing changes in its bulk modulus and introducing unpredictable measurement errors. At the same time, high temperature will also cause irreversible thermal damage to the electronic components and sealing materials (such as O-rings) inside the sensor, significantly shortening the service life of the transmitter and even causing permanent failure. Second, the traditional transmitter is usually connected to the system pipeline with a threaded or flanged connection with a pressure introduction hole. These small holes and cavities are easily blocked by polymers, crystalline substances or particulate matter, preventing the pressure from being effectively transmitted to the sensor, causing measurement failure. Maintenance personnel must frequently perform time-consuming and labor-intensive cleaning work, or even need to remove the entire transmitter from the pipeline, which seriously affects the production continuity and increases the maintenance cost.

[0003] To cope with high-temperature working conditions, the existing technology usually adopts two schemes: one is to choose a transmitter with a higher temperature rating, but the cost is extremely high, and there is still an upper limit. The second is to install an independent radiator or condensing elbow. The latter has some effect, but increases the system complexity and leakage points, and cannot solve the blockage problem. To cope with the blockage problem, the industry usually adopts the scheme of increasing the pressure introduction hole. However, although it can alleviate the blockage problem, the fluctuation of the medium pressure will increase the impact force on the core sensor components, and the high-temperature conduction problem cannot be avoided. SUMMARY

[0004] Technical problems solved In view of the deficiencies of the prior art, the present application provides a small pressure transmitter, which solves the problems of the core sensor of the pressure transmitter in the prior art, i.e. long-term high-temperature work of the core sensor will accelerate the aging and denaturation of the internal filling liquid, causing changes in its bulk modulus and introducing unpredictable measurement errors, and the small holes and cavities on the transmitter are easily blocked by crystalline substances or particulate matter formed by the medium at high temperature.

[0005] Technical scheme To achieve the above object, the application provides the following technical scheme: a small pressure transmitter, comprising a shell and a circuit board, a signal generator, an isolation diaphragm and a measuring diaphragm installed in the shell, further comprising: an isolation cavity, the isolation diaphragm and the measuring diaphragm are fixedly connected in the shell, and the isolation cavity filled with sealing liquid is formed between the isolation diaphragm and the measuring diaphragm, so that the pressure of the measured medium cannot directly contact and impact the signal generator, and the upper end of the shell is provided with an isolation plate, the upper end of the isolation plate is sealed by a glue block formed by glue pouring; an outer shell, the upper end of the outer shell is provided with a connecting pipe, the lower end of the shell is integrally provided with a threaded connecting pipe, the upper end of the connecting pipe is connected with the threaded connecting pipe, the lower end of the outer shell is provided with an outer thread pipe with the same thread structure as the threaded connecting pipe, a plurality of extension pipes capable of dissipating heat are installed between the outer thread pipe and the connecting pipe, and the temperature of the measured medium can be effectively reduced through the extension pipes.

[0006] As a further description of the above technical scheme, the shell is threadedly connected with a locking nut, the lower end of the locking nut is provided with a fixed portion, the circuit board is fixedly installed on the fixed portion, a circular hole is formed in the locking nut for passing the signal line installed on the circuit board, a breathable pipe is installed on the isolation plate, the lower end of the breathable pipe is provided with a waterproof and breathable sticker, and a wire through hole is formed in the isolation plate for passing the signal line; a step is arranged in the shell, a clamping groove is arranged on the step, the isolation diaphragm is sealingly connected in the clamping groove, a fixing frame is arranged on the step, the upper end of the fixing frame is provided with a supporting portion, the supporting portion is in contact with the lower end of the locking nut, the lower end of the fixing frame is in pressure contact with the upper end of the isolation diaphragm, and the signal generator is installed at the lower end of the fixing frame and in contact with the isolation diaphragm.

[0007] As a further description of the above technical scheme, a damper with a cylindrical structure is arranged in the threaded connecting pipe, a channel is arranged at the center of the damper, a plurality of bypass holes are circumferentially formed in the channel as the center, and a partition plate is fixedly connected in the isolation cavity.

[0008] As a further description of the above technical scheme, 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 matched with the sealing gasket, and the edge of the annular base is provided with a flange matched with the outer diameter of the shell.

[0009] As a further description of the above technical scheme, a light surface portion is arranged on the side wall of the threaded connecting pipe, the diameter of the light surface portion is smaller than the outer diameter of the threaded connecting pipe, a sealing ring is embedded in the inner wall of the threaded connecting pipe through an annular groove, and the sealing ring is sleeved with the light surface portion on the threaded connecting pipe.

[0010] As a further description of the above technical scheme, a first threaded hole is formed in the wall of the connecting pipe, a deflation bolt is threadedly connected in the first threaded hole, a second threaded hole is formed in the wall of the outer threaded pipe, and a sealing bolt is connected in the second threaded hole, and a sealing rubber pad is arranged on the deflation bolt and the sealing bolt.

[0011] As a further description of the above technical scheme, a circular plate is fixedly connected in the connecting pipe, a plurality of circular holes are formed in the sidewall of the circular plate, a guide column is sleeved with a guide hole in the center of the circular plate, a cross is fixedly connected to the upper end of the guide column, a circular ring is fixedly connected to the cross, a plurality of semicircular exhaust ports are formed in the upper end of the circular ring, a sealing plate is fixedly connected to the lower end of the guide column, a rubber pad is fixedly connected to the upper end of the sealing plate, two annular protrusions are arranged on the upper end of the rubber pad, a spring is sleeved with the sidewall of the guide column, the upper end of the spring is in contact with the lower end of the cross, and the lower end of the spring is in contact with the upper end of the circular plate.

[0012] As a further description of the above technical scheme, the opposite two sides of the shell are fixedly connected with cover bodies, one side of each of the two cover bodies extends into the outer shell and is fixedly connected with a heat-conducting plate through a bolt, the heat-conducting plate is arranged on one side of the plurality of extension pipes and is used for timely conducting away the temperature of the measured medium in the extension pipe, the upper and lower ends of the outer shell are both in a sealed structure, the upper end of the extension pipe passes through the upper end of the outer shell and is connected with the lower end of the extension pipe, as a further description of the above technical scheme, one side of the heat-conducting plate is fixedly connected with two thermoelectric cooling elements, one side of the cover body is fixedly connected with a rectangular plate, one side of the rectangular plate is fixedly connected with two micro fans, and the upper end of the shell is fixedly connected with a temperature measuring element.

[0013] As a further description of the above technical scheme, a plurality of fins are fixedly connected on the walls of the plurality of extension pipes, and copper sheets are fixedly connected on the opposite two sides of the plurality of fins, one side of the copper sheet is in contact with the heat-conducting plate, and heat-conducting silicone grease is applied at the joint.

[0014] Advantages Compared with the prior art, the present application provides a small-sized pressure transmitter, which has the following advantages: 1、The present application is small in size by the structure of the pressure transmitter, and the measuring diaphragm directly blocks the entrance of the shell, so that the measured medium does not enter the shell, and the bottom of the shell is almost flush, so that the measuring process will not cause the pressure hole to be blocked and other failures occur, at the same time, the measuring diaphragm is directly contacted with the measured medium, the pressure is transmitted to the sensor chip of the signal generator without damage through the filling liquid, so that the sensor chip can be isolated from the measured medium, and corrosion, blockage or pollution can be prevented, and the signal generator and the circuit board are designed separately, and there is a certain space between them, and the filling liquid can also play a certain cooling effect, and the electronic components on the circuit board will not be damaged.

[0015] 2、When the measured medium passes through the extension pipe, the temperature of the medium is finally transmitted to the outside through the extension pipe, fin, copper sheet and heat conduction plate, realizing the effect of natural cooling, and the airflow flow on the surface of the heat conduction plate can be accelerated through the micro fan, so that the heat can be dissipated to the air in time, thereby realizing the effect of rapid cooling, when the temperature is too high, the thermoelectric cooling element can be started, the thermoelectric cooling element is a semiconductor refrigerating sheet, and the cold surface is attached to the surface of the heat conduction plate, so that the purpose of efficient cooling can be achieved at high temperature, and the temperature fluctuation of the measured medium can be coped with.

[0016] 3、When the extension pipe is used, the shell is installed on the connecting pipe through the threaded pipe, at this time, the lower end of the threaded pipe presses the ring to make the guide column move down, and the sealing plate and the rubber pad move away from the circular plate when the guide column moves down, at this time, the medium can pass through the circular hole on the circular plate to contact the measuring diaphragm, when the pressure transmitter is disassembled, the threaded pipe moves up, and under the action of the spring, the sealing plate and the rubber pad move up to contact the lower end of the circular plate, so that the medium cannot pass through the circular hole, at this time, the sealing effect can be achieved, and in the process of moving up, the smooth surface of the threaded pipe keeps in contact with the sealing ring, and when the sealing plate does not contact the circular plate, the sealing effect is achieved, preventing the measured medium inside from being sprayed out. DETAILED DESCRIPTION

[0017] Figure 1 A structure diagram of a small pressure transmitter is provided for the present application; Figure 2 A structure diagram of a small pressure transmitter installed on the shell is provided for the present application; Figure 3 A structure diagram of a small pressure transmitter is provided for the present application; Figure 1 ; Figure 4 A structure diagram of a small pressure transmitter is provided for the present application; Figure 2 ; Figure 5 A structure diagram of a small pressure transmitter is provided for the present application; Figure 6This 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. 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 ; 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 ; Figure 9 This is a schematic diagram of the housing structure in a small pressure transmitter proposed in this invention; Figure 10 This is a schematic diagram of the damper structure in a small pressure transmitter proposed in this invention; 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.

[0018] 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

[0019] 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.

[0020] Example: See attached document Figures 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: The structure of the pressure transmitter comprises a shell 1, a circuit board 32, a signal generator 31, an isolation diaphragm 35 and a measuring diaphragm 28 installed in the shell 1, the isolation diaphragm 35 and the measuring diaphragm 28 are fixedly connected in the shell 1, an isolation cavity 23 filled with sealing liquid is formed between the isolation diaphragm 35 and the measuring diaphragm 28, the isolation cavity 23 is filled with high-purity, chemically stable silicon oil or fluorine oil, the pressure borne by the external measuring diaphragm 28 is transmitted to the internal signal generator 31 without loss, so that the pressure of the measured medium cannot directly contact and impact the signal generator 31, the upper end of the shell 1 is provided with an isolation plate 37, the upper end of the isolation plate 37 is sealed by a glue block 3 formed by pouring glue, the glue can be synthetic resin material, a locking nut 33 is threadedly connected in the shell 1, the lower end of the locking nut 33 is provided with a fixed part, the circuit board 32 is fixedly installed on the fixed part, a circular hole is formed in the locking nut 33 for passing the signal line 4 installed on the circuit board 32, a breather pipe 5 is installed on the isolation plate 37, the lower end of the breather pipe 5 is provided with a waterproof and breathable sticker, the isolation plate 37 is provided with a wire hole for passing the signal line 4, the signal generator 31 adopts a silicon diaphragm made of monocrystalline silicon, which is a core element for sensing pressure and generating an electric signal, it senses the pressure transmitted from the internal silicon oil, and the signal generator 31 is separately packaged and designed separately from the circuit board 32 and connected through a wire harness, so that the signal generator 31 can withstand high temperature, the circuit board 32 is away from the measured medium, and damage to electronic components on the circuit board 32, such as an analog-to-digital converter, a filter circuit and a microprocessor, caused by excessively high temperature is avoided.

[0021] The shell 1 is provided with a step 34, the step 34 is provided with a clamping groove, the isolation diaphragm 35 is sealed and connected in the clamping groove, the isolation diaphragm 35 is directly welded in the clamping groove by using laser welding technology, the isolation diaphragm 35 and the measuring diaphragm 28 are thin metal sheets with elasticity, usually 316L stainless steel, hastelloy or tantalum material, the step 34 is provided with a fixing frame 36, the upper end of the fixing frame 36 is provided with a supporting part, the supporting part is in contact with the lower end of the locking nut 33, the lower end of the fixing frame 36 is in close contact with 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, the threaded connector pipe 2 is provided with a damper 26 with a cylindrical structure, the damper 26 is provided with a channel at the center, the channel has a diameter of 3mm, a plurality of bypass holes are formed in the channel in a circumferential direction, the bypass holes are formed by inclinedly punching at both ends of the damper 26 by 15°, a turning point is formed at the connection, the isolation baffle plate 24 is fixedly connected in the isolation cavity 23, the upper end of the connecting pipe 6 is provided with an annular base 19, the annular base 19 is in contact with the lower end of the shell 1, the lower end of the shell 1 is fixedly connected with the sealing gasket 25 through the annular groove, the upper end of the annular base 19 is provided with a groove matched with the sealing gasket 25, the edge of the annular base 19 is provided with a flange matched with the outer diameter of the shell 1, a light surface part is arranged on the side wall of the threaded connector pipe 2, the diameter of the light surface part is smaller than the outer diameter of the threaded connector pipe 2, the inner wall of the threaded connector pipe 6 is embedded with the sealing ring 27 through the annular groove, and the sealing ring 27 is sleeved with the light surface part on the threaded connector pipe 2.

[0022] As the above technical scheme, the pressure transmitter is miniaturized, the measuring diaphragm 28 directly blocks the inlet of the shell 1, the measured medium cannot enter the shell 1 (in the traditional mode, the medium needs to enter the device through the pressure introduction hole to contact the sensitive element, and the pressure change can be measured), the bottom of the shell 1 is almost flush, so that the pressure introduction hole is not blocked during the measurement, and the dam failure is avoided, at the same time, the measuring diaphragm 28 is directly in contact with the measured medium, the pressure is transmitted to the sensor chip of the signal generator 31 through the filling liquid without damage, so that the sensor chip is isolated from the measured medium, and corrosion, blockage or pollution is prevented, the signal generator 31 and the circuit board 32 are designed separately, and there is a certain space between them, the filling liquid can also play a certain cooling effect, and the electronic components on the circuit board 32 are not damaged.

[0023] During measurement, the measured medium pressure acts on the measuring diaphragm 28, the diaphragm is deformed to extrude the filling liquid in the isolation cavity 23, the filling liquid transmits the pressure to the isolation diaphragm 35, the sensor chip senses the pressure sensitive resistance value change caused by the silicon diaphragm deformation, outputs a millivolt signal through the wheatstone bridge, and the millivolt signal is combined with temperature data and sent to the ASIC for amplification, temperature compensation and linearization, and finally a standard signal (such as 4-20mA) is output.

[0024] As Figures 3-6And Figure 11 As shown in the long distance assembly mode can be used for high temperature 80 °-150 ° measured medium, the specific technical scheme of pressure transmitter as follows, the upper end of the shell 7 is provided with a connecting pipe 6, the lower end of the shell 1 is integrally formed with a threaded pipe 2, the upper end of the connecting pipe 6 is connected with the threaded pipe 2, the lower end of the shell 7 is provided with an outer thread pipe 10 with the same threaded structure as the threaded pipe 2, a plurality of extension pipes 12 capable of heat dissipation are installed between the outer thread pipe 10 and the connecting pipe 6, the inner diameter of the extension pipe 12 is 5 mm, the wall thickness is 2 mm, the temperature of the measured medium can be effectively reduced through the extension pipe 12, and the specific technical scheme is as follows: The opposite sides of the shell 1 are fixedly connected with cover bodies 9, one side of each of the two cover bodies 9 extends into the shell 7 and is fixedly connected with a heat conduction plate 22 through bolts, the heat conduction plate 22 is arranged on one side of the plurality of extension pipes 12, and is used for timely conducting away the temperature of the measured medium in the extension pipe 12. The upper and lower ends of the shell 7 are both sealing structures, the upper end of the extension pipe 12 communicates with the connecting pipe 6 through the upper end of the shell 7, and the lower end of the extension pipe 12 communicates with the outer thread pipe 10 through the lower end of the shell 7.

[0025] One side of the heat conduction plate 22 is fixedly connected with two thermoelectric cooling elements 21, one side of the cover body 9 is fixedly connected with a rectangular plate 8, one side of the rectangular plate 8 is fixedly connected with two micro fans 13, the upper end of the shell 1 is fixedly connected with a temperature measuring element 20, the temperature measuring element 20 is a temperature sensor, which is used for directly measuring the temperature of the medium after cooling, as a signal for starting different cooling modes, a plurality of fins are fixedly connected on the pipe wall of the plurality of extension pipes 12, the opposite sides of the plurality of fins are both fixedly connected with copper sheets 18, one side of the copper sheet 18 is in contact with the heat conduction plate 22, and the joint is coated with heat conduction silicone grease; As Figure 3 And Figure 4 As shown in the measured medium passes through the extension pipe 12, the temperature of the medium is finally transmitted to the outside through the extension pipe 12, the fin, the copper sheet 18 and the heat conduction plate 22, realizing the effect of natural cooling, and the airflow on the surface of the heat conduction plate 22 can be accelerated through the micro fan 13, so that the heat can be dissipated to the air in time, thereby realizing the effect of rapid cooling. When the temperature is too high, the thermoelectric cooling element 21 can be started, the thermoelectric cooling element 21 is a semiconductor refrigerating sheet, when direct current passes through the electric couple formed by the series connection of two different semiconductor materials, heat can be absorbed and heat can be emitted at both ends of the electric couple, so that the purpose of refrigeration can be achieved. Here, the cold surface is attached to the surface of the heat conduction plate 22, which can play the purpose of efficient cooling at high temperature, and can realize the purpose of coping with the temperature fluctuation of the measured medium.

[0026] The pipe wall of the connecting pipe 6 is provided with a first threaded hole, a deflation bolt 14 is threadedly connected in the first threaded hole, the pipe wall of the outer threaded pipe 10 is provided with a second threaded hole, and a sealing bolt 11 is connected in the second threaded hole; the deflation bolt 14 and the sealing bolt 11 are both provided with sealing rubber pads; As Figure 3 shown, during initial installation or after disassembly for maintenance, because air exists in the extension pipe 12, direct installation will cause the presence of compressible air inside, and a large amount of air will affect the pressure of the final medium contact measuring diaphragm 28, therefore, the residual air in the extension pipe 12 can be discharged during assembly through the deflation bolt 14, so that the medium can directly contact the measuring diaphragm 28.

[0027] Secondly, the connecting pipe 6 is fixedly connected with a circular plate 16, a plurality of round holes are provided in the side wall of the circular plate 16, a guide column 30 is sleeved in the center of the circular plate 16 through a guide hole, the upper end of the guide column 30 is fixedly connected with a cross, the cross is fixedly connected with a circular ring 15, a plurality of semicircular exhaust ports are provided in the upper end of the circular ring 15, the lower end of the guide column 30 is fixedly connected with a sealing plate 17, the upper end of the sealing plate 17 is fixedly connected with a rubber pad, two annular protrusions are provided in the upper end of the rubber pad, a spring 29 is sleeved in the side wall of the guide column 30, the upper end of the spring 29 is in contact with the lower end of the cross, and the lower end of the spring 29 is in contact with the upper end of the circular plate 16.

[0028] As Figure 7 and Figure 8 shown, when the extension pipe 12 is used, the shell 1 is installed on the connecting pipe 6 through the threaded connecting pipe 2, at this time, the lower end of the threaded connecting pipe 2 presses the circular ring 15 downward to move the guide column 30 downward, when the guide column 30 moves downward, the sealing plate 17 and the rubber pad move away from the circular plate 16, at this time, the medium can pass through the round holes in the circular plate 16 to contact the measuring diaphragm 28, when the pressure transmitter is disassembled, the threaded connecting pipe 2 moves upward, under the action of the spring 29, the sealing plate 17 and the rubber pad move upward to contact the lower end of the circular plate 16, so that the medium cannot pass through the round holes, at this time, the sealing effect is achieved, and in the upward movement process, the smooth surface part of the threaded connecting pipe 2 keeps in contact with the sealing ring 27, when the sealing plate 17 does not contact the circular plate 16, the sealing effect is achieved, and the internal measured medium is prevented from being sprayed out.

[0029] It should be noted that the term "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus that includes the element.

[0030] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A small pressure transmitter comprising a housing (1) and a circuit board (32), a signal generator (31), an isolating diaphragm (35) and a measuring diaphragm (28) mounted in the housing (1), characterized in that Also include: The isolation chamber (23), the isolation diaphragm (35) and the measuring diaphragm (28) are fixedly connected in the shell (1), the 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), the upper end of the shell (1) is provided with an isolation plate (37), and the upper end of the isolation plate (37) is sealed by a glue block (3) formed by pouring glue; The outer shell (7) is provided with a connecting pipe (6) at the upper end, and the lower end of the shell (1) is integrally provided with a threaded connecting pipe (2), the upper end of the connecting pipe (6) is connected with the threaded connecting pipe (2), the lower end of the outer shell (7) is provided with an outer thread pipe (10) with the same thread structure as the threaded connecting pipe (2), a plurality of extension pipes (12) capable of dissipating heat are installed between the outer thread pipe (10) and the connecting pipe (6), and the temperature of the measured medium can be effectively reduced through the extension pipe (12).

2. A small pressure transmitter according to claim 1, characterized in that: The shell (1) is threadedly connected with a locking nut (33), the lower end of the locking nut (33) is provided with a fixed portion, the circuit board (32) is fixedly installed on the fixed portion, a circular hole is formed in the locking nut (33) for the signal line (4) installed on the circuit board (32), the isolation plate (37) is provided with a breathable pipe (5), the lower end of the breathable pipe (5) is provided with a waterproof breathable sticker, and the isolation plate (37) is provided with a wire through hole for passing through the signal line (4); The shell (1) is provided with a step (34), the step (34) is provided with a clamping groove, the isolation diaphragm (35) is sealingly connected in the clamping groove, the step (34) is provided with a fixing frame (36), the upper end of the fixing frame (36) is provided with a supporting portion, the supporting portion is in contact with the lower end of the locking nut (33), the lower end of the fixing frame (36) is in contact with the upper end of the isolation diaphragm (35), and the signal generator (31) is installed at the lower end of the fixing frame (36) and in contact with the isolation diaphragm (35).

3. The compact pressure transmitter of claim 1, wherein: The threaded connecting pipe (2) is provided with a damper (26) of cylindrical structure, the center of the damper (26) is provided with a channel, a plurality of bypass holes are formed in the channel, and the isolation chamber (23) is fixedly connected with a partition plate (24).

4. The compact pressure transmitter of claim 1, wherein: The upper end of the connecting pipe (6) is provided with an annular base (19), the annular base (19) is in contact with the lower end of the shell (1), the lower end of the shell (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 matched with the sealing gasket (25), and the edge of the annular base (19) is provided with a flange matched with the outer diameter of the shell (1).

5. The compact pressure transmitter of claim 1, wherein: The side wall of the threaded connecting pipe (2) is provided with a smooth surface part, the diameter of the smooth surface part is smaller than the outer diameter of the threaded connecting pipe (2), the inner wall of the threaded connecting pipe (6) is embedded with a sealing ring (27) through an annular groove, and the sealing ring (27) is sleeved with the smooth surface part on the threaded connecting pipe (2).

6. A small pressure transmitter according to claim 1, characterized in that: The pipe wall of the connecting pipe (6) is provided with a first threaded hole, a deflation bolt (14) is threadedly connected in the first threaded hole, the pipe wall of the outer threaded pipe (10) is provided with a second threaded hole, and a sealing bolt (11) is connected in the second threaded hole.

7. The compact pressure transmitter of claim 1, wherein: The connecting pipe (6) is fixedly connected with a circular plate (16), a plurality of circular holes are formed in the side wall of the circular plate (16), a guide column (30) is sleeved in the center of the circular plate (16) through a guide hole, a cross is fixedly connected to the upper end of the guide column (30), a circular ring (15) is fixedly connected to the cross, a plurality of semicircular openings for exhausting are formed in the upper end of the circular ring (15), a sealing plate (17) is fixedly connected to the lower end of the guide column (30), a rubber pad is fixedly connected to the upper end of the sealing plate (17), two annular protrusions are arranged on the upper end of the rubber pad, a spring (29) is sleeved on the side wall of the guide column (30), the upper end of the spring (29) is in contact with the lower end of the cross, and the lower end of the spring (29) is in contact with the upper end of the circular plate (16).

8. The compact pressure transmitter of claim 1, wherein: The opposite sides of the shell (1) are fixedly connected with cover bodies (9), one side of each of the two cover bodies (9) extends into the outer shell (7) and is fixedly connected with a heat conducting plate (22) through a bolt, the heat conducting plate (22) is arranged on one side of a plurality of extension pipes (12) and is used for timely conducting away the temperature of the measured medium in the extension pipe (12), the upper and lower ends of the outer shell (7) are in a sealed structure, the upper end of the extension pipe (12) penetrates through the upper end of the outer shell (7) and communicates with the connecting pipe (6), and the lower end of the extension pipe (12) penetrates through the lower end of the outer shell (7) and communicates with the outer threaded pipe (10).

9. A small pressure transmitter according to claim 8, characterized in that: One side of the heat conducting plate (22) is fixedly connected with two thermoelectric cooling elements (21), one side of the cover body (9) is fixedly connected with a rectangular plate (8), one side of the rectangular plate (8) is fixedly connected with two micro fans (13), and the upper end of the shell (1) is fixedly connected with a temperature measuring element (20).

10. The compact pressure transmitter of claim 8, wherein: The pipe walls of the plurality of extension pipes (12) are fixedly connected with a plurality of fins, the opposite sides of the plurality of fins are fixedly connected with copper sheets (18), one side of the copper sheet (18) is in contact with the heat conducting plate (22), and heat-conducting silicone grease is applied at the joint.

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