Self-unblocking variable-diameter pig suitable for gas transmission pipeline

Abstract

This invention is a self-dissolving variable diameter pig suitable for gas pipelines, comprising: a skeleton sealing assembly, a tracked deceleration assembly, a rotary cleaning assembly, a sealing cup, and a deblocking and pressure relief assembly. The skeleton sealing assembly has a sealing cup at its rear end, which is sealed to the pipeline. When high-pressure gas is introduced into the pipeline, a pressure difference is generated between the propulsion chamber and the cleaning chamber, propelling the skeleton sealing assembly along the pipeline. The variable diameter support assembly drives the tracked deceleration assembly to change diameter, adapting to variations in pipeline inner diameter and always keeping the tracked deceleration assembly in close contact with the pipeline inner wall. The rotary cleaning assembly can rotate to deeply clean the scale buildup on the pipeline inner wall. When blockage occurs, high-pressure gas is delivered through the deblocking and pressure relief assembly, passing through the skeleton sealing assembly to the rotary cleaning assembly. The high-pressure airflow at the rear end of the skeleton sealing assembly flushes away the scale, achieving the self-dissolving function.

Description

Technical Field

[0001] This invention relates to the field of pipeline cleaning technology, specifically a self-unblocking variable diameter pig suitable for gas pipelines. Background Technology

[0002] Oil and natural gas are the most widely used energy sources in the world today, and their transportation is mainly achieved through long-distance pipelines. After hundreds of years of development, the pipeline transportation industry has become a massive industrial system, playing an increasingly important role in the oil and gas industry and even the global economy. However, after prolonged use, oil and gas pipelines gradually accumulate deposits such as paraffin wax and oil stains on their walls. The formation of these deposits not only reduces pipeline transportation efficiency but can also cause serious accidents such as fires and explosions due to their corrosive and flammable properties, posing a severe threat to the natural environment and human life. Therefore, it is urgent to regularly clean oil and gas pipelines.

[0003] Currently, gas pipelines generally use methods such as sending cleaning balls or cup-type cleaning machines to remove scale from the pipes. For example, Chinese Patent 202121057163.5, entitled "A Cleaning Ball for Natural Gas Uneven Pipelines," designs a new type of cleaning ball to address problems encountered when cleaning pipelines with large undulations. This cleaning ball device has good elasticity and plasticity, which can effectively avoid blockage accidents. However, it suffers severe wear during the cleaning process, greatly increasing the risk of corrosion and breakage. To solve the corrosion and breakage problem during the cleaning process, Chinese Patent 202321295454.7, entitled "A Natural Gas Pipeline Cleaning Machine," designs a double-cup cleaning machine. This device adds highly wear-resistant cups at both the front and rear ends. This method uses steam to soften the hardened scale on the inner wall of natural gas pipelines, and then uses a cleaning structure to scrape the softened scale to ensure thorough cleaning and improve the reliability and effectiveness of scale removal. However, this device lacks an anti-clogging function; if a blockage occurs in the pipeline, it will cease operation. To address the blockage problem, Chinese Patent 201820139600.X, entitled "A Pipeline Cleaning Device Applicable to Variable Diameter Pipelines," designed a pipeline cleaning device that uses the fluid medium in the pipeline to disperse impurities, thus relieving the blockage. However, this device ignores the impact of the fluid used to disperse impurities on the operation of the pipeline cleaning device, and its structure is too large, making it only suitable for large-diameter pipelines. Small-diameter pipelines have limited internal space, resulting in fewer types of pipeline cleaning devices available. Furthermore, pipeline cleaning devices are prone to blockage in small-diameter pipelines, leading to incomplete cleaning and affecting the cleaning effect. Therefore, pipeline cleaning devices have certain limitations for small-diameter pipelines.

[0004] In summary, how to clean small-diameter gas pipelines has become an urgent problem for researchers in this field. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to clean small-diameter gas transmission pipelines;

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] This invention relates to a self-unblocking variable diameter pig suitable for gas pipelines, comprising: a skeleton sealing assembly; multiple tracked deceleration assemblies connected to a base on the outer wall of the skeleton sealing assembly via a corresponding variable diameter support assembly; a rotating cleaning assembly rotatably disposed at the front end of the skeleton sealing assembly, adapted to rotate and clean the inner wall of the pipeline; a sealing cup disposed at the rear end of the skeleton sealing assembly, dividing the pipeline into a propulsion chamber and a cleaning chamber; and an unblocking and pressure relief assembly disposed within the skeleton sealing assembly, adapted to introduce high-pressure gas into the skeleton sealing assembly and discharge it from the rotating cleaning assembly to unblock the inner wall of the pipeline; wherein, the tracked deceleration assembly can reduce the forward speed of the pig, and the variable diameter support assembly can keep the tracked deceleration assembly in constant contact with the inner wall of pipelines of different diameters;

[0008] In this design, a sealing cup is installed at the rear end of the skeleton sealing assembly, which is sealed to the pipeline. When high-pressure gas is introduced into the pipeline, a pressure difference is generated between the propulsion chamber and the cleaning chamber, propelling the skeleton sealing assembly along the pipeline. The tracked deceleration assembly not only serves as a moving mechanism but also slows down the movement speed of the skeleton sealing assembly within the pipeline, achieving fine cleaning of the pipeline's inner wall. The variable diameter support assembly enables the tracked deceleration assembly to change diameter to adapt to variations in the inner diameter of different pipelines, ensuring that the tracked deceleration assembly remains in close contact with the pipeline's inner wall. The rotary cleaning assembly can rotate to deeply clean the scale buildup on the pipeline's inner wall. When blockage occurs, the high-pressure gas is delivered through the unblocking and pressure relief assembly, passing through the skeleton sealing assembly to the rotary cleaning assembly. The high-pressure airflow at the rear end of the skeleton sealing assembly flushes away the scale, achieving a self-unblocking function.

[0009] To illustrate the specific structure of the skeleton sealing assembly, the present invention uses a skeleton sealing assembly comprising: a skeleton; and a conical fixing part, which is fixedly disposed within the skeleton, forming a conical pressure relief channel with the inner wall of the skeleton; the conical pressure relief channel forms an air inlet with the rear end of the skeleton, and the conical pressure relief channel forms an air outlet with the front end of the skeleton;

[0010] In this solution, the skeleton sealing assembly includes a base, a sealing cup, and a conical pressure relief channel inside the skeleton. The conical pressure relief channel allows high-pressure airflow to enter through the inlet and exit through the outlet.

[0011] To illustrate, the unblocking and pressure relief assembly includes: a spring seat, which is fixedly disposed within the conical fixing part; an annular cover plate, which covers and is fixed at the air inlet; a valve cover, which is disposed on the front side of the annular cover plate; a second spring, which is compressed and disposed between the valve cover and the spring seat, and is adapted to press the valve cover against the annular cover plate; and a fan-shaped groove, which is formed at the valve cover, and under the action of the second spring, the annular cover plate covers the fan-shaped groove.

[0012] In this design, an annular cover plate, a valve cover, a second spring, and a spring seat are sequentially arranged along the axial direction of the frame. Under the action of the second spring, the valve cover is always pressed against the annular cover plate when no external force is applied, thus covering the fan-shaped groove and preventing gas from entering the conical pressure relief channel. When the entire device cannot move forward due to blockage, the high-pressure gas drives the second spring to compress, separating the valve cover and the annular cover plate and creating a gap between them. Gas can then enter the conical pressure relief channel through the gap and the fan-shaped groove, allowing the gas to be introduced into the rotating cleaning component to flush away the accumulated dirt and achieve the self-unblocking function.

[0013] To illustrate the specific structure of the rotary cleaning assembly, the present invention employs a rotary cleaning assembly comprising: a motor, which is fixedly mounted within the conical fixing portion and has a rotating shaft, one end of which passes through the front end of the frame and is connected to the output shaft of the motor via a coupling; multiple connecting shafts, one end of which is perpendicular to the rotating shaft and the other end of which is fixed with a steel brush; both the rotating shaft and the connecting shafts have interconnected internal cavities; a second air inlet is provided at the rotating shaft located at the air outlet; and multiple second air outlets are provided at the connecting shafts.

[0014] In this scheme, the motor drives the rotating shaft to rotate through the coupling, and the rotating shaft drives the connecting shaft to rotate. The steel brush at the end of the connecting shaft is always in contact with the inner wall of the pipe for cleaning. High-pressure gas enters the second air inlet through the outlet hole and then exits from the second air outlet hole. In this way, the high-pressure gas acts on the inner wall of the pipe to unblock it.

[0015] Conventional pipeline cleaning pigs operate at a speed of 20 m / s within pipelines. This speed is too fast to effectively clean the inner walls of the pipeline. To reduce the speed of the cleaning pig within the pipeline, this invention employs a tracked deceleration assembly comprising: a frame; a track rotatably mounted on the frame; a drive gear and a driven gear, both rotatably mounted within the frame and located on opposite sides of the frame, meshing with the inner teeth of the track; wherein, a first conical tooth is provided between the two drive gears and between the two driven gears; and a conical driven gear has second conical teeth at both ends, meshing with corresponding first conical teeth.

[0016] The outer surface of the track has a trapezoidal pattern to increase sliding friction with the inner wall of the pipe, thereby achieving the goal of deceleration. The friction of the track drives the drive gear and driven gear to rotate. The second bevel teeth at both ends of the bevel driven gear achieve synchronization and consistency of the rotation speed of the drive gear and driven gear, ensuring that the track will not slip off from the drive gear and driven gear.

[0017] To illustrate the specific structure of the variable diameter support assembly, the present invention uses a variable diameter support assembly comprising two support assemblies arranged opposite to each other; each support assembly includes: a long connecting rod, one end of which is slidably disposed on the base, and the other end of which is slidably disposed in a waist hole in the frame via a limiting pin; a first spring, which is sleeved on the base, one end of which abuts against the end of the base, and the other end of which abuts against the bottom end of the long connecting rod; and a short connecting rod, one end of which is hinged to the base, and the other end of which is hinged to the middle of the long connecting rod;

[0018] In this design, when the pipe diameter decreases, the angle between the short and long connecting rods increases, the first spring is compressed, and the limiting pin moves towards the inside of the waist hole, causing the tracked reduction assembly to move closer to the outer wall of the frame to accommodate the small pipe diameter; conversely, when the pipe diameter increases, the first spring returns to its original position, the angle between the short and long connecting rods decreases, causing the tracked reduction assembly to move away from the outer wall of the frame to accommodate the large pipe diameter.

[0019] To prevent high-pressure gas from entering the conical fixing part and thus affecting the motor and to depressurize the gas, the present invention employs an annular guide on the valve cover, which is sealed and inserted into the conical fixing part.

[0020] The annular guide serves three purposes: 1. It provides a sealing connection to prevent gas from entering the conical fixed part; 2. It ensures that the valve cover only moves axially; 3. It provides an installation position for the other end of the second spring.

[0021] The beneficial effects of this invention are as follows: This invention is a self-unblocking variable diameter pig suitable for gas pipelines. A sealing cup is installed at the rear end of the skeleton sealing assembly, and the sealing cup is sealed to the pipeline. When high-pressure gas is introduced into the pipeline, a pressure difference is generated between the propulsion chamber and the cleaning chamber, pushing the skeleton sealing assembly to move along the pipeline. The tracked deceleration assembly not only serves as a walking mechanism but also slows down the movement speed of the skeleton sealing assembly within the pipeline, achieving fine cleaning of the pipeline's inner wall. The variable diameter support assembly can drive the tracked deceleration assembly to change diameter to adapt to changes in the inner diameter of different pipelines, always keeping the tracked deceleration assembly in close contact with the pipeline's inner wall. The rotating cleaning assembly can rotate to deeply clean the scale buildup on the pipeline's inner wall. When blockage occurs, high-pressure gas is delivered through the unblocking and pressure relief assembly, passing through the skeleton sealing assembly to the rotating cleaning assembly. The high-pressure airflow at the rear end of the skeleton sealing assembly flushes away the scale, achieving the self-unblocking function. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a schematic diagram of the structure of the present invention;

[0024] Figure 2 This is a cross-sectional view of the present invention;

[0025] Figure 3 It is a cross-sectional view of the skeleton;

[0026] Figure 4 This is an exploded view of the unblocking and pressure relief component;

[0027] Figure 5 This is a schematic diagram of the valve cover structure;

[0028] Figure 6 This is a schematic diagram showing the flow direction of gas into the skeleton sealing assembly when a blockage occurs;

[0029] In the diagram: 1-Skeleton sealing assembly, 11-Base, 12-Sealing cup, 13-Skeleton, 14-Conical fixing part, 15-Conical pressure relief channel, 16-Air inlet, 17-Air outlet, 2-Crawler-type reduction assembly, 21-Frame, 22-Crawler, 23-Drive gear, 24-Driven gear, 25-First conical tooth, 26-Conical driven gear, 3-Variable diameter support assembly, 31-Long connecting rod, 32-Limit pin, 33-Waist hole, 34-First spring, 35-Short connecting rod, 4-Rotating cleaning assembly, 41-Motor, 42-Rotating shaft, 43-Connecting shaft, 44-Steel brush, 45-Steel brush, 46-Second air inlet, 47-Second air outlet, 5-Unblocking and pressure relief assembly, 51-Spring seat, 52-Annular cover plate, 53-Valve cover, 54-Second spring, 55-Sector groove. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0031] like Figure 1 , 2As shown in Figure 6, this invention is a self-unblocking variable diameter pig suitable for gas pipelines, comprising: a skeleton sealing assembly 1; multiple tracked deceleration assemblies 2, which are connected to a base 11 on the outer wall of the skeleton sealing assembly 1 via corresponding variable diameter support assemblies 3; a rotating cleaning assembly 4, which is rotatably disposed at the front end of the skeleton sealing assembly 1 and is adapted to rotate and clean the inner wall of the pipeline; a sealing cup 12, which is disposed at the rear end of the skeleton sealing assembly 1 and divides the pipeline into a propulsion chamber and a cleaning chamber; and an unblocking and pressure relief assembly 5, which is disposed within the skeleton sealing assembly 1 and is adapted to introduce high-pressure gas into the skeleton sealing assembly 1 and discharge it from the rotating cleaning assembly 4 to unblock the inner wall of the pipeline; wherein, the tracked deceleration assemblies 2 can reduce the forward speed of the pig, and the variable diameter support assemblies 3 can keep the tracked deceleration assemblies 2 in contact with the inner wall of pipelines of different diameters;

[0032] In this design, a sealing cup is installed at the rear end of the skeleton sealing assembly, which is sealed to the pipeline. When high-pressure gas is introduced into the pipeline, a pressure difference is generated between the propulsion chamber and the cleaning chamber, propelling the skeleton sealing assembly along the pipeline. The tracked deceleration assembly not only serves as a moving mechanism but also slows down the movement speed of the skeleton sealing assembly within the pipeline, achieving fine cleaning of the pipeline's inner wall. The variable diameter support assembly enables the tracked deceleration assembly to change diameter to adapt to variations in the inner diameter of different pipelines, ensuring that the tracked deceleration assembly remains in close contact with the pipeline's inner wall. The rotary cleaning assembly can rotate to deeply clean the scale buildup on the pipeline's inner wall. When blockage occurs, the high-pressure gas is delivered through the unblocking and pressure relief assembly, passing through the skeleton sealing assembly to the rotary cleaning assembly. The high-pressure airflow at the rear end of the skeleton sealing assembly flushes away the scale, achieving a self-unblocking function.

[0033] like Figure 1 , 2 As shown in Figure 3, in order to illustrate the specific structure of the skeleton sealing assembly, the present invention adopts a skeleton sealing assembly 1 including: a skeleton 13; and a conical fixing part 14, which is fixedly disposed in the skeleton 13, and forms a conical pressure relief channel 15 with the inner wall of the skeleton 13; the conical pressure relief channel 15 forms an air inlet 16 with the rear end of the skeleton 12, and the conical pressure relief channel 15 forms an air outlet 17 with the front end of the skeleton 13;

[0034] In this solution, the skeleton sealing assembly includes a base, a sealing cup, and a conical pressure relief channel inside the skeleton. The conical pressure relief channel allows high-pressure airflow to enter through the inlet and exit through the outlet.

[0035] like Figure 2 , 4As shown in Figure 5, to illustrate the unblocking and pressure relief assembly, it includes: a spring seat 51, which is fixedly disposed within the conical fixing part 14; an annular cover plate 52, which covers and is fixed at the air inlet 16; a valve cover 53, which is disposed on the front side of the annular cover plate 52; a second spring 54, which is pressurized and disposed between the valve cover 53 and the spring seat 51, and is adapted to press the valve cover 53 against the annular cover plate 52; and a fan-shaped groove 55, which is formed at the valve cover 53, and under the action of the second spring 54, the annular cover plate 52 covers the fan-shaped groove 55.

[0036] In this design, an annular cover plate, a valve cover, a second spring, and a spring seat are sequentially arranged along the axial direction of the frame. Under the action of the second spring, the valve cover is always pressed against the annular cover plate when no external force is applied, thus covering the fan-shaped groove and preventing gas from entering the conical pressure relief channel. When the entire device cannot move forward due to blockage, the high-pressure gas drives the second spring to compress, separating the valve cover and the annular cover plate and creating a gap between them. Gas can then enter the conical pressure relief channel through the gap and the fan-shaped groove, allowing the gas to be introduced into the rotating cleaning component to flush away the accumulated dirt and achieve the self-unblocking function.

[0037] like Figure 1-2 As shown, to illustrate the specific structure of the rotary cleaning assembly, the present invention employs a rotary cleaning assembly 4 comprising: a motor 41, which is fixedly disposed within the conical fixing part 14; a rotating shaft 42, one end of which passes through the front end of the frame 13 and is connected to the output shaft of the motor 41 via a coupling; multiple connecting shafts 43, one end of which is perpendicular to the rotating shaft 42, and the other end of which is fixed with a steel brush 44, wherein four steel brushes 44 are configured to cover the inner wall of the pipe 360°, and the size and shape of the steel brushes can be changed according to the actual pipe conditions to achieve a comprehensive pipe cleaning function; both the rotating shaft 42 and the connecting shafts 43 are provided with interconnected inner cavities 45; a second air inlet 46 is provided at the rotating shaft 42 located at the air outlet 17; and multiple second air outlets 47 are provided at the connecting shafts 43;

[0038] In this scheme, the motor drives the rotating shaft to rotate through the coupling, and the rotating shaft drives the connecting shaft to rotate. The steel brush at the end of the connecting shaft is always in contact with the inner wall of the pipe for cleaning. High-pressure gas enters the second air inlet through the outlet hole and then exits from the second air outlet hole. In this way, the high-pressure gas acts on the inner wall of the pipe to unblock it.

[0039] like Figure 1-2As shown, the conventional pipeline cleaning machine operates at a speed of 20 m / s inside the pipeline. This speed is too fast to achieve the desired cleaning effect on the inner wall of the pipeline. To reduce the speed of the pipeline cleaning machine inside the pipeline, the present invention employs the tracked deceleration assembly 2, which includes: a frame 21; a track 22 rotatably mounted around the frame 21; a drive gear 23 and a driven gear 24, both rotatably mounted inside the frame 21 and located on opposite sides of the frame 21, meshing with the inner teeth of the track 22; wherein, a first conical tooth 25 is provided between the two drive gears 23 and between the two driven gears 24; a conical driven gear 26 has a second conical tooth 27 at both ends, which meshes with the corresponding first conical tooth 25.

[0040] The outer surface of the track has a trapezoidal pattern to increase sliding friction with the inner wall of the pipe, thereby achieving the goal of deceleration. The friction of the track drives the drive gear and driven gear to rotate. The second bevel teeth at both ends of the bevel driven gear achieve synchronization and consistency of the rotation speed of the drive gear and driven gear, ensuring that the track will not slip off from the drive gear and driven gear.

[0041] like Figure 1-2 As shown, to illustrate the specific structure of the variable diameter support assembly, the present invention uses the variable diameter support assembly 3, which includes two support assemblies arranged opposite to each other; each support assembly includes: a long connecting rod 31, one end of which is slidably disposed on the base 11 (this can be achieved by the slider fixed to the bottom of the long connecting rod cooperating with the slide rail on the base), and the other end is slidably disposed in the frame 21 with a waist hole 33 opened therein through a limiting pin 32; a first spring 34, which is sleeved on the base 11, one end of which abuts against the end of the base 11, and the other end of which abuts against the bottom end of the long connecting rod 31; a short connecting rod 35, one end of which is hinged to the base 11, and the other end of which is hinged to the middle of the long connecting rod 31;

[0042] In this design, when the pipe diameter decreases, the angle between the short and long connecting rods increases, the first spring is compressed, and the limiting pin moves towards the inside of the waist hole, causing the tracked reduction assembly to move closer to the outer wall of the frame to accommodate the small pipe diameter; conversely, when the pipe diameter increases, the first spring returns to its original position, the angle between the short and long connecting rods decreases, causing the tracked reduction assembly to move away from the outer wall of the frame to accommodate the large pipe diameter.

[0043] like Figure 5-6 As shown, in order to prevent high-pressure gas from entering the conical fixing part and thus affecting the motor and to depressurize the gas, the present invention uses an annular guide 53 on the valve cover 53, and the annular guide 53 is sealed and inserted into the conical fixing part 14.

[0044] The annular guide serves three purposes: 1. It provides a sealing connection to prevent gas from entering the conical fixed part; 2. It ensures that the valve cover only moves axially; 3. It provides an installation position for the other end of the second spring.

[0045] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A self-unblocking variable diameter pig suitable for gas pipelines, characterized in that, include: Skeleton sealing assembly; Multiple tracked reduction gears are connected to a base on the outer wall of the skeleton sealing assembly via a strain gauge support assembly; A rotary cleaning assembly, which is rotatably disposed at the front end of the skeleton sealing assembly, is adapted to perform rotary cleaning of the inner wall of the pipe; A sealing cup, located at the rear end of the skeleton sealing assembly, divides the pipe into a propulsion chamber and a cleaning chamber; And a deblocking and pressure relief component, which is disposed within the skeleton sealing component, is adapted to introduce high-pressure gas into the skeleton sealing component and discharge it from the rotary cleaning component to deblock the inner wall of the pipe; The tracked deceleration assembly can reduce the forward speed of the pig, and the variable diameter support assembly can keep the tracked deceleration assembly always in contact with the inner wall of pipes of different diameters. The tracked reduction gear includes: frame; Tracks, which are rotatably mounted around the frame; The driving gear and the driven gear are both rotatably mounted inside the frame and are located on both sides of the frame, respectively, and mesh with the inner teeth of the track. A first conical tooth is provided between the two driving gears and between the two driven gears; The bevel driven gear has a second bevel tooth at each end, which meshes with the corresponding first bevel tooth.

2. The self-unblocking reducing pig for gas pipelines according to claim 1, characterized in that, The skeleton sealing assembly includes: skeleton; And a conical fixing part, which is fixedly installed inside the frame, forming a conical pressure relief channel with the inner wall of the frame; The conical pressure relief channel forms an air inlet with the rear end of the frame, and the conical pressure relief channel forms an air outlet with the front end of the frame.

3. A self-unblocking variable diameter pig for gas pipelines according to claim 2, characterized in that, The unblocking and pressure relief assembly includes: A spring seat is fixedly disposed within the conical fixing part; An annular cover plate is fixedly installed over the air inlet. A valve cover is disposed on the front side of the annular cover plate; The second spring is compressed and disposed between the valve cover and the spring seat, and is adapted to press the valve cover against the annular cover plate. A sector-shaped groove is formed at the valve cover, and under the action of the second spring, the annular cover plate covers the sector-shaped groove.

4. A self-unblocking variable diameter pig for gas pipelines according to claim 2, wherein the rotating cleaning assembly comprises: The motor is fixedly installed inside the conical fixing part; A rotating shaft, one end of which passes through the front end of the frame and is connected to the output shaft of the motor via a coupling; Multiple connecting shafts, one end of which is perpendicular to the rotating shaft, and the other end of which is fixed with a steel brush; Both the rotating shaft and the connecting shaft have interconnected internal cavities. A second air inlet is provided at the rotating shaft located at the air outlet; Multiple second air vents are provided at the connecting shaft.

5. A self-unblocking reducing pig for gas pipelines according to claim 1, characterized in that, The variable diameter support assembly includes two support components arranged opposite to each other; Each support component includes: A long connecting rod, one end of which is slidably mounted on the base, and the other end of which is slidably mounted in the waist hole of the frame through a limiting pin; The first spring is sleeved on the base, with one end abutting against the end of the base and the other end abutting against the bottom end of the long connecting rod; The short connecting rod has one end hinged to the base and the other end hinged to the middle of the long connecting rod.

6. A self-unblocking variable diameter pig for gas pipelines according to claim 3, characterized in that, The valve cover is provided with an annular guide, which is sealed and inserted into the conical fixing part.

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