An electrical conversion unit for a valve positioner

Abstract

The application belongs to the technical field of intelligent valve positioner, and particularly discloses an electrical conversion unit of a valve positioner, which comprises a seat body, the seat body comprises a top seat, a middle seat and a bottom seat connected in sequence, a first stop mechanism is arranged between a gas source cavity and an air inlet cavity, a second stop mechanism is arranged between the air inlet cavity and an output cavity, and a third stop mechanism is arranged between the output cavity and an air outlet cavity; a driver and a filtering and pressure reducing mechanism are arranged. The piezoelectric valve, the valve core and the air path are respectively designed in three independent modules through the three-layer stacked structure, which is convenient for assembly and sealing, is favorable for maintenance and disassembly in the later period, and through the filtering and pressure reducing device, the input pressure of the piezoelectric valve can be regulated to a specified pressure range, most impurities in the gas source can be filtered out, the piezoelectric valve is protected to a certain extent, and the service life of the piezoelectric valve is prolonged.

Description

Technical Field

[0001] This invention relates to the field of intelligent valve positioner technology, and in particular to an electrical conversion unit for a valve positioner. Background Technology

[0002] The electrical conversion unit is the core component of a valve positioner. Currently, there are two main structural forms of electrical conversion units in intelligent valve positioners: electromagnetic coil type and piezoelectric valve type. Electromagnetic coil type conversion units consume more power and have a longer response time compared to piezoelectric valve type conversion units. Piezoelectric valve type conversion units have high requirements for sealing and air source cleanliness. In the control system, if there is leakage at the air source input or output port of the electrical conversion unit, it will cause the valve positioner to oscillate continuously, resulting in instability of the medium transported in the control pipeline, affecting product quality or causing danger. Furthermore, poor air source cleanliness can lead to the failure of the electrical conversion unit, causing the valve positioner to malfunction. In view of this, the applicant has proposed an electrical conversion unit for a valve positioner. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an electrical conversion unit for a valve positioner to solve the problem of unstable air source input in the prior art.

[0004] To achieve the above and other related objectives, the present invention provides an electrical conversion unit for a valve positioner, comprising:

[0005] The base includes a top seat, a middle seat, and a base connected in sequence. An isolation diaphragm is provided between the top seat and the middle seat. The base is provided with an air source chamber, an air inlet chamber, an air outlet chamber, and an exhaust chamber. A first stop mechanism is provided between the air source chamber and the air inlet chamber. A second stop mechanism is provided between the air inlet chamber and the air outlet chamber. A third stop mechanism is provided between the air outlet chamber and the exhaust chamber.

[0006] A driver is disposed within the top seat and is used to control the opening and closing of the first stop mechanism and the third stop mechanism;

[0007] A filtration and pressure reduction mechanism is disposed in the housing. The filtration and pressure reduction mechanism includes an air intake component and an adjustment component. The output end of the filtration and pressure reduction mechanism is connected to the driver.

[0008] Optionally, the middle seat has an input chamber communicating with the air source chamber. The air intake assembly includes an air resistance adjustment component and a pressure plate. The end of the air resistance adjustment component near the isolation diaphragm abuts against the isolation diaphragm. The end of the air resistance adjustment component away from the top seat is provided with a return spring. The air resistance adjustment component abuts against the pressure plate through the return spring. An air intake gap is provided between the air resistance adjustment component and the pressure plate. The pressure plate is provided with an air intake channel communicating with the air intake gap. Symmetrical connecting holes are opened on the pressure plate.

[0009] Optionally, the filter assembly includes a filter screen and a filter chamber disposed in the middle seat, and a back pressure chamber exists between the filter screen and the isolation membrane. The back pressure chamber can be connected to the air source chamber through the pressure plate, wherein the gas in the back pressure chamber passes through the filter screen and enters the filter chamber, and the output end of the filter chamber is connected to the driver.

[0010] Optionally, the filtration and pressure reduction mechanism further includes an adjustment component, which includes an adjustment screw and an elastic compression member. The adjustment component is disposed within the top seat and threadedly connected to the top seat. The elastic compression member is disposed between the adjustment screw and the isolation diaphragm. The adjustment screw can drive the air resistance adjustment member to move through the elastic compression member.

[0011] Optionally, the elastic extruder includes a tray and a support plate, the support plate being fixedly connected to one end of the tray near the adjusting screw, and the tray being placed on the surface of the isolation diaphragm.

[0012] Optionally, the filter chamber is provided with a detection head for detecting the pressure of the filter chamber.

[0013] Optionally, the first stop mechanism includes a valve core assembly and a first spring. The first spring is disposed within the air source chamber. The valve core assembly includes an upper valve core, a sealing plate, and a movable valve core. The movable valve core is disposed between the upper valve core and the sealing plate. The end of the upper valve core away from the sealing plate abuts against the isolation diaphragm. The end of the sealing plate away from the upper valve core is connected to the free end of the first spring. The actuator can push the valve core assembly to move axially along the movable valve core to open or close the input end of the air intake chamber.

[0014] Optionally, the second stop mechanism includes a second spring and an elastic seal. The second spring is disposed in the output cavity, and the elastic seal is disposed at the free end of the second spring. The elastic seal abuts against the output end of the intake cavity via the second spring.

[0015] Optionally, the third stop mechanism includes an exhaust valve core and a sealing diaphragm. The exhaust valve core is connected to the sealing diaphragm, the sealing diaphragm abuts against the output end of the output cavity, and the end of the exhaust valve core away from the sealing diaphragm abuts against the isolation diaphragm. A third spring is provided in the middle seat, and the free end of the third spring is connected to the exhaust valve core.

[0016] Optionally, the actuator is a piezoelectric valve, which is connected to the filter chamber and used to control the flow of gas in the filter chamber.

[0017] As described above, the electrical conversion unit for a valve positioner proposed in this invention has the following beneficial effects:

[0018] (1) In this invention, by adopting a three-layer structure with separate air circuits for the driver, valve core and base, the structure is simple and easy to seal. At the same time, it improves the corrosion resistance and resistance to permanent compression deformation of the valve core, ensures the sealing effect between each chamber, avoids the plastic deformation caused by long-term stress of the valve core affecting the sealing effect, ensures the service life of the electrical conversion unit, and improves the service life of the valve positioner.

[0019] (2) In this invention, the sensitivity of the actuator to the air source is reduced by setting a filter pressure reducing device, and the air source is depressurized by using adjustment components and air intake components to improve the stability of the input air source, so that the driving force of the actuator can remain constant, thereby ensuring the stable operation of the valve positioner, extending the service life and safety performance of the conversion unit. Attached Figure Description

[0020] Figure 1 The diagram shown is a schematic diagram of air intake in one embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram showing the output being maintained in one embodiment of the present invention;

[0022] Figure 3 The diagram shown is a schematic diagram of exhaust in one embodiment of the present invention;

[0023] Figure 4 The diagram shown is a schematic diagram of a filtration and pressure reduction mechanism in one embodiment of the present invention;

[0024] Figure 5 The image shown is a top view of the pressure plate in one embodiment of the present invention;

[0025] Figure 6 The image shown is an enlarged view of point A in one embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] Top seat 1, driver 2, upper valve core 3, sealing plate 4, moving valve core 5, middle seat 6, first spring 7, elastic seal 8, second spring 9, isolation diaphragm 10, exhaust valve core 11, third spring 12, sealing diaphragm 13, base 14, support plate 15, tray 16, pressure plate 17, air inlet gap 1701, connecting hole 1702, air inlet channel 1703, first sealing ring 18, adjusting screw 19, filter screen 20, second sealing ring 21, air resistance adjusting component 22, reset spring 23, third sealing ring 24, detection head 25, air source chamber p1, air inlet chamber p2, output chamber p3, exhaust chamber p4, input chamber Q1, back pressure chamber Q2, filter chamber Q3. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components relevant to the present invention and are not drawn according to the actual number, shape, and size of components in implementation. In actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the component layout may be more complex. The structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effects and objectives of the present invention, should still fall within the scope of the technical content disclosed in the present invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0030] like Figures 1-6 As shown, the present invention proposes an electrical conversion unit for a valve positioner.

[0031] In one exemplary embodiment, the electrical conversion unit of the valve positioner includes:

[0032] The base includes a top seat 1, a middle seat 6 and a base 14 connected in sequence. An isolation diaphragm 10 is provided between the top seat 1 and the middle seat 6. The base is provided with an air source chamber p1, an air inlet chamber p2, an air outlet chamber p3 and an exhaust chamber p4. A first stop mechanism is provided between the air source chamber p1 and the air inlet chamber p2. A second stop mechanism is provided between the air inlet chamber p2 and the air outlet chamber p3. A third stop mechanism is provided between the air outlet chamber p3 and the exhaust chamber p4.

[0033] Driver 2 is located inside the top seat 1 and is used to control the opening and closing of the first stop mechanism and the third stop mechanism.

[0034] The filter pressure reduction mechanism is located inside the housing and includes an intake component and an adjustment component. The output end of the filter pressure reduction mechanism is connected to the driver 2.

[0035] In this embodiment, a three-layer structure with separate air circuits for the actuator 2, valve core, and base 14 is adopted. The structure is simple and easy to seal. At the same time, it improves the corrosion resistance and resistance to permanent compression deformation of the valve core, ensures the sealing effect between each chamber, avoids plastic deformation of the valve core due to long-term stress affecting the sealing effect, ensures the service life of the electrical conversion unit, and improves the service life of the valve positioner.

[0036] In this invention, a filter pressure reducing device is used to reduce the sensitivity of the actuator 2 to the air source. An adjustment component and an air intake component are used to reduce the pressure of the air source and improve the stability of the input air source. This allows the driving force of the actuator 2 to remain constant, thereby ensuring the stable operation of the valve positioner and extending the service life and safety performance of the conversion unit.

[0037] In an exemplary embodiment, the middle seat 6 is provided with an input cavity Q1 that communicates with the air source cavity p1. The air intake assembly includes an air resistance adjustment component 22 and a pressure plate 17. The upper end of the air resistance adjustment component 22 abuts against the isolation diaphragm 10. The end of the air resistance adjustment component 22 away from the top seat 1 is provided with a return spring 23. The air resistance adjustment component 22 abuts against the pressure plate 17 through the return spring 23. An air intake gap 1701 is provided between the air resistance adjustment component 22 and the pressure plate 17. The pressure plate 17 is provided with an air intake channel 1703 that communicates with the air intake gap 1701. The pressure plate 17 is symmetrically provided with connecting holes 1702.

[0038] Meanwhile, an adjustment assembly is provided in the top seat 1. The adjustment assembly includes an adjustment screw 19 and an elastic pressing member. The adjustment assembly is located in the top seat 1 and is threadedly connected to the top seat 1. The elastic pressing member is located between the adjustment screw 19 and the isolation diaphragm 10. The adjustment screw 19 can drive the air resistance adjustment member 22 to move through the elastic pressing member.

[0039] In this embodiment, the input cavity Q1 allows the gas source in the gas source cavity p1 to be introduced into the filter and pressure reduction mechanism. The processed gas source is then driven by the driver 2 to control the movement of the first stop mechanism and the third stop mechanism. In this embodiment, the adjusting screw 19, the air resistance adjusting component 22, and the pressure plate 17 are used to achieve the cut-off of the pressurized gas. The degree of opening of the air inlet gap 1701 is controlled by manual adjustment, which facilitates the adjustment of the air inlet pressure, so that the gas entering the back pressure cavity Q2 achieves pressure stability. When the gas source enters the air resistance adjusting component 22 from the air inlet gap 1701, the pressure plate 17 abuts against the isolation diaphragm 10. At this time, the gas source is guided to the connecting hole 1702 through the air inlet channel 1703 on the pressure plate 17, passes through the connecting hole 1702, and then passes through the filter screen 20 before entering the filter cavity Q3.

[0040] For example, in this embodiment, the operator can rotate the adjusting screw 19 to drive the adjusting screw 19 up or down through the set adjustment component, thereby driving the elastic extrusion member to move synchronously, and then driving the air resistance adjustment member 22 to move synchronously. During the process of the air resistance adjustment member 22 moving down, the air intake gap 1701 will be opened. The degree of descent of the elastic extrusion member, that is, the downward movement distance of the adjusting screw 19, determines the opening size of the air intake gap 1701, which in turn determines the air intake volume in the back pressure chamber Q2.

[0041] For example, in this embodiment, the elastic compression member includes a tray 16 and a support plate 15. The tray 16 and the support plate 15 are connected by screws. The support plate 15 is fixedly connected to the upper end of the tray 16. The tray 16 is placed on the surface of the isolation diaphragm 10.

[0042] For example, in this embodiment, a first sealing ring 18 is provided in the back pressure chamber Q2, which abuts against the bottom surface of the pressure plate 17 to prevent the pressurized gas in the input chamber Q1 from directly entering the back pressure chamber Q2. At the same time, a second sealing ring 21 is also provided in the back pressure chamber Q2 to achieve the functions of sealing between the back pressure chamber Q2 and the filter chamber Q3 and fixing the filter screen 20.

[0043] In this embodiment, by rotating the adjusting screw 19 downwards, the elastic support plate 15 undergoes downward elastic deformation under pressure. The elastic deformation of the support plate 15 transmits the pressure to the isolation diaphragm 10 through the tray 16, causing the isolation diaphragm 10 to undergo elastic deformation. Under the action of this elastic deformation, the pressure plate 17 pushes the air resistance adjusting component 22 to overcome the elastic force of the return spring 23 and produce a downward displacement. At this time, the channel for gas in the input chamber Q1 to enter the back pressure chamber Q2 is opened. The gas in the back pressure chamber Q2 enters the filter chamber Q3 through the connecting hole 1702 on the pressure plate 17. The gas in this chamber will directly serve as the input air source for the driver 2. When the pressure in the back pressure chamber Q2 reaches the preset pressure balance, under the combined action of the larger air source pressure and the return spring 23, the air resistance adjusting component 22 is pushed to produce an upward displacement, closing the air intake gap 1701 of the input chamber Q1.

[0044] In an exemplary embodiment, the filter assembly includes a filter screen 20 and a filter chamber Q3 disposed within the middle seat 6. A back pressure chamber Q2 exists between the filter screen 20 and the isolation diaphragm 10. The back pressure chamber Q2 can be connected to the gas source chamber p1 via the pressure plate 17. Gas in the back pressure chamber Q2 passes through the filter screen 20 and enters the filter chamber Q3. The output end of the filter chamber Q3 is connected to the driver 2.

[0045] In this embodiment, the air source entering the driver 2 is filtered by the filter component to prevent impurities in the air source from entering the driver 2 and causing damage to the driver 2.

[0046] For example, the filter in this embodiment only allows substances with a diameter of less than 5 micrometers to pass through, and has a significant filtering effect on impurities such as water and oil. Therefore, based on the above description of features, the filter pressure reduction mechanism in this embodiment ensures the cleanliness and pressure requirements of the input air source for the driver 2.

[0047] For example, in this embodiment, the middle seat 6 is provided with a detection channel, which is connected to the filter chamber Q3. It is used to detect the pressure of the gas source entering the filter chamber Q3. A detection head 25 is provided at the end of the detection channel. The detection head 25 is a detection device that can detect the gas source pressure, or a device that can detect the gas source pressure and cleanliness. It is indirectly connected to the filter chamber Q3. A third sealing ring 24 is provided at the end of the detection channel to prevent gas leakage in the filter chamber Q3.

[0048] In this embodiment, the filtered and depressurized gas finally enters the actuator 2 through the channels opened in the middle seat 6 and the top seat 1. The actuator 2 in this embodiment is a piezoelectric valve, which uses pressurized gas as power and controls the opening and closing of the pressurized gas through the control program, so as to squeeze the isolation diaphragm 10 and control the opening or closing of the first and third disconnection mechanisms.

[0049] In an exemplary embodiment, the first stop mechanism includes a valve core assembly and a first spring 7. The first spring 7 is disposed in the air source chamber p1. The valve core assembly includes an upper valve core 3, a sealing plate 4, and a movable valve core 5. The movable valve core 5 is disposed between the upper valve core 3 and the sealing plate 4. The end of the upper valve core 3 away from the sealing plate 4 abuts against the isolation diaphragm 10. The end of the sealing plate 4 away from the upper valve core 3 is connected to the free end of the first spring 7. The actuator 2 can push the valve core assembly to move axially along the movable valve core 5 to open or close the input end of the air intake chamber p2.

[0050] In this embodiment, the right-side driver 2 operates under the action of the control pulse, which increases the pressure in the back pressure chamber Q2. The isolation diaphragm 10 deforms under the action of the pressure, thereby pushing the valve core assembly in contact with it to overcome the elastic force of the first spring 7 and displace downward, opening the input port from the air source chamber p1 to the air inlet chamber p2.

[0051] For example, in this embodiment, the first spring 7 is a conical spring, which can effectively reduce the space occupied by the spring, facilitate installation in narrow spaces, and provide stable elastic force.

[0052] In an exemplary embodiment, the second stop mechanism includes a second spring 9 and an elastic seal 8. The second spring 9 is disposed in the output cavity p3, and the elastic seal 8 is disposed at the free end of the second spring 9. The elastic seal 8 abuts against the output end of the intake cavity p2 via the second spring 9.

[0053] In this embodiment, when pressurized gas enters the intake chamber p2, it will squeeze the elastic seal 8, causing the elastic extruder to move downward and simultaneously squeeze the second spring 9. At this time, the pressurized gas in the intake chamber p2 enters the output chamber p3, achieving stable pressure output.

[0054] For example, in this embodiment, the elastic seal 8 is a sealing ball with a diameter larger than the output end of the air inlet chamber p2 to achieve a sealing function.

[0055] In an exemplary embodiment, the third stop mechanism includes an exhaust valve core 11 and a sealing diaphragm 13. The exhaust valve core 11 is connected to the sealing diaphragm 13. The sealing diaphragm 13 abuts against the output end of the output cavity p3. The end of the exhaust valve core 11 away from the sealing diaphragm 13 abuts against the isolation diaphragm 10. A third spring 12 is provided in the middle seat 6. The free end of the third spring 12 is connected to the exhaust valve core 11.

[0056] In this embodiment, before the air source enters from the air source chamber p1, the left-side driver 2 operates under the action of the control pulse, which increases the pressure in the back pressure chamber Q2. The isolation diaphragm 10 deforms under this pressure, thereby pushing the exhaust valve core 11 in contact with it to overcome the elastic force of the third spring 12 and move downward. As the sealing diaphragm 13 also moves downward, it eventually cuts off the input port from the output chamber p3 to the exhaust chamber p4.

[0057] Specific implementation steps: First, pressurized gas is introduced into the gas source chamber p1. At the same time, part of the pressurized gas in the gas source chamber p1 is diverted through the channel in the middle seat 6 and enters the input chamber Q1 of the filter pressure reduction mechanism. The gas source in the filter pressure reduction mechanism is depressurized. The depressurization process is as follows: By rotating the adjusting screw 19 downward, the elastic support plate 15 is subjected to downward elastic deformation under pressure. The elastic deformation of the support plate 15 transmits the pressure to the isolation diaphragm 10 through the tray 16, causing the isolation diaphragm 10 to undergo elastic deformation. Under the action of this elastic deformation, the pressure plate 17 pushes the air resistance adjustment component 22 to overcome the elastic force of the return spring 23 and produce a downward displacement. At this time, the channel for the gas in the input chamber Q1 to enter the back pressure chamber Q2 is opened. The gas in the back pressure chamber Q2 enters the filter chamber Q3 through the connecting hole 1702 on the pressure plate 17. The gas in this chamber will be directly used as the input gas source of the driver 2. When the pressure in the back pressure chamber Q2 reaches the preset pressure balance, under the combined action of the larger air source pressure and the return spring 23, the air resistance adjustment component 22 is pushed to produce an upward displacement to close the air intake gap 1701 of the input chamber Q1. At the same time, the pressure can be detected by the detection head 25 to see if the pressure reaches the required standard.

[0058] In the second step, after the filtered and depressurized air source enters the driver 2, the driver 2 on the left drives the corresponding isolation diaphragm 10 to move down, which in turn moves the valve core assembly down, opening the channel between the air source chamber p1 and the input power. The pressurized air source enters the intake chamber p2 and pushes the elastic seal 8 into the output chamber p3. The base 14 has an output port that communicates with the output chamber p3. Finally, the compressed air pushes the pneumatic actuator to the designated position through the output port.

[0059] Third, after the pneumatic actuator reaches the designated position, the control pulse of the right piezoelectric valve is removed, reducing the pressure in its back pressure chamber Q2. The intake valve core assembly is reset under the combined action of the first spring 7 and the air source pressure. The sealing plate 4 contacts the input port of the middle seat 6, isolating the air source chamber p1 and the intake chamber p2. The air source disappears, and the pressure in the intake chamber p2 becomes zero. The elastic seal 8 is reset under the elastic force of the second spring 9, so that the upper end of the elastic seal 8 contacts the middle seat 6 to form a line seal, isolating the intake chamber p2 and the output chamber p3, so that the output chamber p3 and the actuator maintain a certain pressure, and the valve stem of the pneumatic actuator is kept in the required position.

[0060] Fourth step: If it is necessary to reset the valve stem of the pneumatic actuator, the pressure in the output chamber p3 needs to be released. The control pulse of the left piezoelectric valve can be removed to reduce the pressure in the back pressure chamber Q2. The exhaust valve core 11 is reset under the action of the third spring 12, opening the input port from the output chamber p3 to the exhaust chamber p4, and releasing the pressure from the exhaust chamber p4 to the atmosphere.

[0061] In summary, this invention successfully integrates the piezoelectric valve, valve core, and air circuit into three independent modules through a three-layer stacked structure. This not only facilitates assembly and sealing but also benefits subsequent maintenance and disassembly. All valve cores are made of corrosion-resistant rubber material with high resistance to compression set, improving long-term sealing and extending service life. A rubber sealing ball with a diameter larger than the air circuit diameter is used between the piezoelectric valve seat 6 and base 14 to ensure unidirectional sealing. Its bottom is spring-loaded against the air inlet, forming a line seal and further ensuring sealing performance. Integrating the plastic air circuit components into the electrical conversion unit not only increases the ease of positioner maintenance but also improves sealing reliability. Furthermore, the pressure-reducing filter not only regulates the pressure of the air source input to the piezoelectric valve to the specified range but also filters out most impurities in the air source, providing protection for the piezoelectric valve and extending its service life. The above embodiments are merely illustrative of the principles and effects of this invention and are not intended to limit the invention. Anyone skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. An electrical conversion unit for a valve positioner, characterized in that, include: The base includes a top seat, a middle seat, and a base connected in sequence. An isolation diaphragm is provided between the top seat and the middle seat. The base is provided with an air source chamber, an air inlet chamber, an air outlet chamber, and an exhaust chamber. A first stop mechanism is provided between the air source chamber and the air inlet chamber. A second stop mechanism is provided between the air inlet chamber and the air outlet chamber. A third stop mechanism is provided between the air outlet chamber and the exhaust chamber. A driver is disposed within the top seat and is used to control the opening and closing of the first stop mechanism and the third stop mechanism; A filtration and pressure reduction mechanism is disposed within the base. The filtration and pressure reduction mechanism includes an air intake component and an adjustment component. The output end of the filtration and pressure reduction mechanism is connected to the driver. The air intake component includes an air resistance adjustment component and a pressure plate. The end of the air resistance adjustment component near the isolation diaphragm abuts against the isolation diaphragm. The end of the air resistance adjustment component away from the top base is provided with a return spring. The air resistance adjustment component abuts against the pressure plate through the return spring. An air intake gap is provided between the air resistance adjustment component and the pressure plate. The pressure plate is provided with an air intake channel communicating with the air intake gap. Symmetrical connecting holes are opened on the pressure plate. The output end of the filtration and pressure reduction mechanism is also provided with a detection device. It also includes a filter assembly, which includes a filter screen and a filter chamber disposed in the middle seat. There is a back pressure chamber between the filter screen and the isolation membrane. The back pressure chamber can be connected to the air source chamber through the pressure plate. The gas in the back pressure chamber passes through the filter screen and enters the filter chamber. The output end of the filter chamber is connected to the driver. The filtration and pressure reduction mechanism further includes an adjustment component, which includes an adjustment screw and an elastic compression member. The adjustment component is disposed inside the top seat and threadedly connected to the top seat. The elastic compression member is disposed between the adjustment screw and the isolation diaphragm. The adjustment screw can drive the air resistance adjustment member to move through the elastic compression member.

2. The electrical conversion unit of the valve positioner according to claim 1, characterized in that: The elastic extrusion member includes a tray and a support plate, the support plate being fixedly connected to one end of the tray near the adjusting screw, and the tray being placed on the surface of the isolation diaphragm.

3. The electrical conversion unit of the valve positioner according to claim 1, characterized in that: The back pressure chamber is equipped with a first sealing ring and a second sealing ring.

4. The electrical conversion unit of the valve positioner according to claim 1, characterized in that: The first stop mechanism includes a valve core assembly and a first spring. The first spring is disposed in the air source chamber. The valve core assembly includes an upper valve core, a sealing plate, and a movable valve core. The movable valve core is disposed between the upper valve core and the sealing plate. The end of the upper valve core away from the sealing plate abuts against the isolation diaphragm. The end of the sealing plate away from the upper valve core is connected to the free end of the first spring. The actuator can push the valve core assembly to move axially along the movable valve core to open or close the input end of the air intake chamber.

5. The electrical conversion unit of the valve positioner according to claim 1, characterized in that: The second stop mechanism includes a second spring and an elastic seal. The second spring is disposed in the output cavity, and the elastic seal is disposed at the free end of the second spring. The elastic seal abuts against the output end of the intake cavity through the second spring.

6. The electrical conversion unit of the valve positioner according to claim 1, characterized in that: The third stop mechanism includes an exhaust valve core and a sealing diaphragm. The exhaust valve core is connected to the sealing diaphragm, the sealing diaphragm abuts against the output end of the output cavity, and the end of the exhaust valve core away from the sealing diaphragm abuts against the isolation diaphragm. A third spring is provided in the middle seat, and the free end of the third spring is connected to the exhaust valve core.

7. The electrical conversion unit of the valve positioner according to any one of claims 1-6, characterized in that: The actuator is a piezoelectric valve, which is connected to the filter chamber and is used to control the flow of gas in the filter chamber.

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