Pipeline internal state detection device

Abstract

The invention relates to a pipeline internal state detection device which comprises a middle detection mechanism, a front end detection mechanism and an emergency exit mechanism, the front end detection mechanism and the emergency exit mechanism are detachably arranged at the front end and the rear end of a reducing mechanism respectively, and the middle detection mechanism comprises the reducing mechanism, a second camera and a third camera. The second camera and the third camera are both used for rotating by 360 degrees along the periphery of the telescopic rod to shoot images of the inner side of the pipeline and automatically storing the images, the front-end detection mechanism comprises an extension rod and a first camera, the first camera is arranged at the front end of the extension rod, and the front-end detection mechanism is used for shooting images of the front-end area of the pipeline through the first camera at the front end and automatically storing the images. The third camera can shoot an image of a pipeline opening area which cannot be shot by the second camera, and the extension rod and the first camera can extend into a narrow space in front of the pipeline to shoot the image, so that full-coverage shooting of the internal area of the pipeline is realized, and the detection requirements of gas pushing and shooting equipment for pipelines with different inner diameters can be met.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline internal detection, in particular to a pipeline internal state detection device. Background Art

[0002] Traditional in-pipe testing methods (pipeline measurement inspection, strength test, and injection accuracy test) cannot obtain complete pipeline inner wall damage information, and pipeline reliability assessment lacks important data on the inner wall damage status. Application units rarely detect pipeline status during the use of pipeline injection equipment, and some use wall peep instruments to perform simple detection of the internal status of the pipeline. In fact, the wall peep instrument can only view the current status of the pipeline, mainly to observe whether there are large cracks, look for foreign objects, etc., and fail to obtain full pipeline information. It also does not have an autonomous detection function, which greatly reduces the detection efficiency and cannot scientifically and effectively evaluate the pipeline status. At the same time, the pipeline crawling robots designed by various research teams failed to display the entire picture of the pipe (including the combustion chamber, slope and spiral groove), and the operation was complicated and the autonomy was not strong, so they were not actually used on a large scale in application units.

[0003] At present, the technology for detecting mechanical surface defects is developing rapidly, and there are relatively mature technologies for image feature extraction and damage type judgment. However, in the field of equipment use inspection, the technology for detecting the inner wall of pipelines has not been widely used. Obtaining a complete picture of the inner wall of the pipeline is an important link. Summary of the invention

[0004] In order to effectively solve the above problems, the present invention provides a pipeline internal state detection device.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A pipeline internal state detection device comprises a middle detection mechanism, a front detection mechanism and an emergency exit mechanism, wherein the front detection mechanism and the emergency exit mechanism are detachably arranged at the front end and the rear end of a diameter-changing mechanism, respectively; the middle detection mechanism comprises a diameter-changing mechanism, a second camera and a third camera, wherein the second camera and the third camera are arranged at the front end and the rear end of the diameter-changing mechanism, respectively; the diameter-changing mechanism comprises a telescopic rod, a diameter-changing bracket and a walking mechanism, wherein a plurality of diameter-changing brackets are evenly arranged radially on the outside of the telescopic rod, the walking mechanism is arranged on the diameter-changing bracket, the telescopic rod is used to adjust the width of the diameter-changing bracket by telescoping so that the walking mechanism contacts and fits the inner side surface of the pipeline, the walking mechanism is used to drive the entire detection device to translate forward along the inner side surface of the pipeline, the second camera and the third camera are both used to rotate 360° along the outer circumference of the telescopic rod to shoot an image of the inner side of the pipeline and automatically store it, the front detection mechanism comprises an extension rod and a first camera, the first camera is arranged at the front end of the extension rod, the front detection mechanism is used to shoot an image of a narrow area at the front end of the pipeline through the first camera at the front end and automatically store it, and the emergency exit mechanism comprises a pull rope, one end of which is connected to the rear end of the telescopic rod, and the other end extends to the outside of the pipeline.

[0006] Further, the telescopic rod includes a fixed rod and a rotating screw rod, the variable diameter bracket includes a U-shaped frame and a support rod, both ends of the U-shaped frame are hinged to the fixed rod, and form a parallelogram frame with the fixed rod, an adjusting nut is provided on the rotating screw rod, the fixed section is used to drive the adjusting nut to translate by rotating the rotating screw rod, one end of the support rod is hinged to the rear side of the U-shaped frame, and the other end is hinged to the adjusting nut through a spring pre-tightening mechanism. Further, the U-shaped frame, the support rod is connected to the rotating screw rod through a spring pre-tightening mechanism, the spring pre-tightening mechanism includes a connecting base and a spring, the spring is sleeved on the outside of the rotating screw rod, and one end is connected to the base, and the other end is connected to the adjusting nut.

[0007] Furthermore, the position of the second camera after the detection device completely enters the pipeline from the pipeline outlet end is assumed to be the dividing point, the third camera is started when the detection device completely enters the pipeline outlet end, and is turned off after the third camera reaches the dividing point, and is used to rotate 360° to shoot the image of the inside of the pipeline between the pipeline outlet end and the dividing point, the second camera is started when the detection device completely enters the pipeline outlet end, and is used to rotate 360° to shoot the image of the inside of the pipeline after the inner dividing point, the first camera is started when the detection device reaches the outside of the combustion chamber at the end of the gas pipeline, the first camera is extended into the inside of the combustion chamber, or is extended into other narrow spaces, and is used to rotate 360° to shoot images in the combustion chamber or a narrow space.

[0008] Furthermore, the number of the variable diameter brackets is at least three.

[0009] Furthermore, fill lights are arranged outside the first camera, the second camera and the third camera for fill lighting when the cameras are shooting.

[0010] Furthermore, the telescopic rod can adjust the width of the variable diameter bracket in real time according to the inner diameter of the pipeline under remote control of the remote control end, so that the walking mechanism contacts and fits the inner side of the pipeline during detection and detaches from the inner side of the pipeline when exiting the pipeline.

[0011] Furthermore, it also includes a position sensor, which is used to detect the real-time position of the detection device and send it to the remote control terminal.

[0012] After adopting the above technical solution, the present invention has the following advantages compared with the prior art: The present invention proposes a detection robot structural design scheme for pipeline equipment, which can adapt to different pipeline inner diameters and realize automatic and smooth crawling in and out of the pipeline. Taking the gas pipeline as an example, the entire pipeline including the spiral groove, slope and combustion chamber can be completely photographed, and the image of the inner wall of the pipeline can be automatically stored. The present invention has the following main advantages: 1. The degree of automation is relatively high, and it can enter the pipeline autonomously to obtain images of various parts of the inner wall of the pipeline; 2. The third camera can capture images of the pipeline mouth area that the second camera cannot capture, and the extension rod and the first camera can be extended into the narrow space in front of the pipeline to capture images, so as to achieve full coverage of the internal area of ​​the pipeline; 3. The structure is relatively simple and the control is relatively convenient; 4. The design of the walking wheel suitable for the inner diameter makes the movement in the pipeline relatively stable; 5. It can meet the detection needs of gas injection equipment for pipelines with different inner diameters.

[0013] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural cross-sectional view of the present invention during pipeline detection; Figure 2 Schematic diagram of the spring preload mechanism structure; Figure 3 is the control hardware logic diagram of the present invention; Figure 4 It is the full-automatic mode control logic diagram of the present invention.

[0015] In the accompanying drawings, the components represented by the reference numerals are as follows: 1. First camera; 2. Second camera; 3. Fixed rod; 4. Rotating screw; 5. Adjusting nut; 6. U-shaped frame; 7. Support rod; 8. Third camera; 9. Travel mechanism; 10. Spring; 11. Base DETAILED DESCRIPTION

[0016] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0017] 1. Detection objects and requirements of detection robots (detection devices) According to actual detection requirements, the main technical performance indicators required by the detection robot detection system are as follows: Detection target: 76mm-155mm inner diameter gas injection pipeline.

[0018] Detection purpose: To obtain the full image of the inner wall of the pipeline.

[0019] Detection accuracy: axis center deviation 2mm.

[0020] Detection system dimensions: L≤600mm, 70mm≤D≤160mm.

[0021] Control mode: fully automatic / wireless control.

[0022] Working environment temperature: -20°C-40°C.

[0023] Power source: lithium battery.

[0024] 2. Robot motion component design 2.1. Selection of drive motor Regarding the selection of drive motors for equipment operating in small inner diameter pipes, we comprehensively considered its needs and the current status of motor development, including the size, efficiency, life and control accuracy of the drive motors. In view of the adaptability of the operating scenarios in pipelines, we finally decided to choose a DC hybrid stepper motor as the drive motor and add a planetary gear reducer.

[0025] The biggest advantage of the stepper motor is its precise control. It can control the coil time according to the change of control pulse and direction, ensure the normal power supply of the motor winding, and perform precise control through closed-loop control of current and pulse. This closed-loop control can ensure the accuracy of each step and avoid the accumulation of errors, thereby improving the accuracy of the operation and ensuring the integrity and efficiency of the detected image. The stepper motor has a good response speed, which can be more flexibly controlled to accurately control the motion state of the detection robot, ensure the quality of the photos of each part of the pipeline, improve the robot's operation efficiency and the effect of the later image synthesis life analysis. Compared with other types of motors, the stepper motor does not need to consume energy when it is stationary, and consumes less energy when running at low speed, which can effectively reduce energy consumption and improve the efficiency and working time of the robot. This high-efficiency feature can maintain long-term operation, especially for the detection robot with small size and limited energy. In addition, the price of the stepper motor is more affordable than other high-precision drivers, the circuit is simple and easy to integrate and control, and the life span is long and the size is small, which has great advantages in the design of this robot.

[0026] Due to the design requirements of the robot, the motor size is required to be small, and the robot has high requirements for the motor torque, so the Plant 20 series planetary gear reduction stepper motor is selected. Due to the small size and space required for the motor, the 20mm series motor with a vertical 90° output shaft is not directly found, so a small 90-degree 1:1 gear right-angle turner is used, one of which is connected to the 20 series hollow stepper motor through a coupling, and the other is directly connected to the transmission gear of the drive wheel to achieve a 90-degree output conversion.

[0027] 2.2. Driving wheel design and transmission structure design Three sets of driving wheels are set on the three sets of variable inner diameter mechanisms of the robot. In the design of the driving wheels, it is considered that since the inner wall of the pipeline is a cylindrical surface, the normal wheel and the arc surface contact mode is point contact. If a normal walking wheel is used, the robot will be affected by the negative and positive lines of the wall line during walking in the wall, affecting the stability of the robot. According to the needs of the detection robot to adapt to pipelines with different inner diameters, walking wheels suitable for pipelines with different inner diameters are designed. The contact arc curvature of each type of walking wheel is adapted to the inner diameter of the pipeline to ensure that the walking wheel and the inner wall of the pipeline are always in line contact. The horizontal design size of each walking wheel is designed to be 8mm to ensure that the walking wheel always crosses more than two positive lines, so that the robot always walks on the positive line to ensure the stability of movement. The rubber material used on the outer surface of the driving wheel can increase the friction coefficient between the driving wheel and the inner wall of the pipeline, increase the drag force, and ensure the normal operation of the drive in the pipeline.

[0028] The drive motor is set on the connecting rod, and the transmission of the drive motor and the drive wheel force is realized through gear meshing. Due to the small working space in the tube, the size of the motor is limited if it is parallel to the drive wheel. To solve this problem, a 90° transmission shaft commutator is added between the rotating gear and the motor to place the motor along the direction of the connecting rod. The control board controls the speed and angle of the synchronous rotation of the drive motor to control the movement of the robot.

[0029] 2.3、Appropriate inner diameter structure design According to the design scheme of the suitable inner diameter structure, a parallel double-link mechanism is adopted. The connecting rod is hinged by two parallel support rods. The front and rear sets of wheels on the connecting rod are in contact with the inner wall support of the pipe. The push rod is designed to be hinged with the rear end support rod. The support rod is pushed by the push rod to adjust the opening angle. The push rod is fixed on the adjusting nut. The adjusting nut cooperates with the screw. The opening angle of the push rod is changed by rotating the adjusting nut, and then the support rod is pushed to adjust the opening angle to realize the function of variable inner diameter, ensuring that the stability of the robot can be adjusted within the inner diameter range of 76mm-155mm.

[0030] The layout of each group of variable diameter support mechanisms refers to the three-claw mechanism widely used on lathes. This design enables the three claw edges to be on a circle with the three claws as the center, and the three support legs to be distributed at 120°, and to shrink or stretch synchronously to ensure the uniformity of the variable diameter process. The three-claw linkage design can ensure that the distance between the edge of each claw and the center is always consistent, and the robot and the pipeline axis coincide. The sensor is arranged on the robot axis, and the center of each part of the pipeline is coincident.

[0031] like Figure 2 As shown, in order to ensure the movement of the robot inside the wall, a certain preload force is applied to the support wheel. A preload spring is arranged between the connecting base of the push rod and the adjusting nut. The preload force of the spring is transmitted to the rubber wheel through the connecting base, the push rod and the support rod. This ensures a certain positive pressure between the rubber wheel and the inner wall of the pipe, thereby ensuring the friction between the rubber wheel and the inner wall of the pipe. When the driving motor drives the rubber wheel to rotate, the robot is driven to move by the dynamic friction between the rubber wheel and the inner wall of the pipe.

[0032] 3. Design of robot detection device 3.1、Detection module solution The detection module of the detection robot is equipped with three cameras, one panoramic camera and two macro cameras, to capture the complete image of the pipeline.

[0033] The panoramic camera is set at the front end, and the center of the camera sensor is set on the robot axis. It is named the first camera 1. It mainly takes pictures of the combustion chamber or other narrow parts that are inconvenient for the robot to enter. At the same time, it assists in rotating the camera to view the internal state of the pipeline in remote control mode. Since the panoramic camera can take pictures in a wide range, especially in the pipeline with smooth inner wall and large inner diameter, the panoramic camera can be used to obtain images of the inner wall of the pipeline in a larger depth range, thereby improving the efficiency and quality of detection.

[0034] According to the design requirements, the front-end camera uses Ruierweishi RER-USB48MP02. This model has high pixel lens, fast focusing speed, and large depth of field, which is suitable for detecting the internal conditions of the remote combustion chamber. In addition to realizing the normal photography function requirements, the camera can be directly matched with the existing communication transmission module and wirelessly connected to the external computer, so that the internal status can be directly observed in real time. The rotating camera is set at the rear end, and the two cameras are respectively set before and after the diameter reducing mechanism. The camera in front of the diameter reducing mechanism is named the second camera 2, and the camera at the rear end of the diameter reducing mechanism is named the third camera 8. The two rotating cameras drive the camera base to rotate 360° through the motor to completely shoot the inner wall of the pipe where the rotating camera is located. Due to the size of the rotating camera mechanism, the distance between the camera and the inner wall of the pipe is small. If you want to capture the largest width of the inner wall each time and improve the detection efficiency, you need to choose a camera with a larger field of view to expand the detection range.

[0035] The rotating camera is a camera with high pixel, small size, strong macro capability and large field of view, model: DH-L2112.K314L. Since the light in the pipeline is dim and the selected camera component does not have a fill light function, LED components are installed on the sides of the three cameras for fill light, which is synchronized with the camera control.

[0036] 3.2 Image Detection Control In the fully automatic mode, after the robot is placed at the pipe opening, the robot is started, the second camera and the third camera start working, the first camera stops working, and the wall line part is photographed. When the robot steps to the initial position of the third camera at the second camera, the third camera stops working, and the remaining wall line is photographed by the second camera. When the robot steps from the first camera to the combustion chamber, the first camera starts working. When the second camera steps to the slope wall part, the second camera stops working, and the images of the wall line and the slope wall part are acquired. When the first camera completes the acquisition of the image of the entire combustion chamber, the first camera stops working, the image of the entire pipeline is acquired, and the robot is ready to return to the pipe opening.

[0037] In remote control mode, the three cameras are turned on and off according to computer instructions, but detection is mainly carried out through the first camera set on the front end axis of the robot, and the second and third cameras are used for auxiliary photography.

[0038] 3.3 Camera mechanism design Since the selected detection scheme has certain requirements for the mechanism design, especially the design of the rotating camera, the following is the specific design of the support structure of the three cameras: 1) Front-end panoramic camera structure design The first camera is set on the pipeline axis, located at the front extension rod, with modular design, and the mounting frame is designed according to the shape of the camera shell. The first camera mainly detects the combustion chamber part. Since the depth of the combustion chamber of each inner diameter pipeline is different, the extension rod is replaced for adaptation.

[0039] 2) Rotating camera structure design The second and third cameras are set at both ends of the variable diameter mechanism, and take pictures by rotating. They adopt a modular design and are set on the main shaft of the robot to rotate and take pictures. The main components include a bearing seat, gears, a small motor, a camera holder and a camera. The bearing seat is sleeved on the main shaft of the robot, the inner ring is fixed to the main shaft, the camera base is fixed on the outer ring, the camera is installed on the base, and a circle of gears is set on the outer ring of the bearing. The motor is fixed on the main shaft, and the gear installed on the motor power output shaft is meshed with the gear on the outer ring of the bearing to realize the rotational photography function of the camera. Since the rotating camera requires a certain amount of power to drive, considering that the driven component has a small moment of inertia, the required torque is small, and the structural size requirements are small, a 6mm four-stage hollow cup planetary reduction motor is selected.

[0040] 4. Robot control system design 4.1 Motion control module design According to actual needs, the robot mainly controls the movement and photography parts. The robot is designed to use a microcontroller as the control center to control the drive motor and camera. The robot's position is measured by a laser ranging module, and it moves according to the set step interval. According to the robot's movement logic and detection logic, it is divided into two directions: fully automatic control and wireless remote control.

[0041] Since the detection robot has a small working space, the STM32F103C8T6 board with a high degree of integration and small size is selected. In the fully automatic mode, by writing an automatic control algorithm, the robot's motion state is obtained according to the laser position sensor, and the camera is controlled to take pictures according to the motion position. The first camera takes pictures directly, and the second and third cameras rotate the camera around the robot's main axis through the driving motor to take pictures; the laser rangefinder provides position information, the data processing system calculates the position deviation, and controls the driving motor through negative feedback regulation to ensure the accuracy of the robot's stepping. Figure 3 This is the control hardware logic diagram.

[0042] In remote control mode, the robot is directly connected to the computer wirelessly through the HC-05 Bluetooth module, and the robot position information and the images taken by the camera are transmitted in real time by moving and shooting on the APP. Considering the problem of electromagnetic shielding inside the pipeline, a small signal amplifier is installed at the outlet to facilitate control by external equipment. At the same time, the width of the variable diameter support mechanism can be controlled by remote control.

[0043] 4.2 Fully automatic control logic During the robot's in-pipe detection process, the entire pipe is divided into three parts, and the detection logic is designed according to the three parts. First, the robot starts, initializes each motor and camera, and prepares to start detection. When detecting the inner wall of the first part of the pipe, the two rotating cameras work simultaneously. The camera first captures the image of the inner wall of the pipe at the current position, and then, driven by the motor, the rotating camera rotates to a new angle and shoots again to obtain images of the inner wall of the pipe at different angles. This process is repeated until the inner wall image of the pipe around the current position of the robot is completely acquired.

[0044] After completing the detection of the current position, the robot's drive motor is activated, and the robot moves forward to the next detection position and repeats the above rotation and photo-taking process until the first part of the pipeline is completely detected.

[0045] The robot then turns off the rotating third camera and uses the rotating second camera to detect the second section of the pipe. The detection logic is the same as the first section, ensuring that the second section of the pipe is also accurately detected.

[0046] After the second part of the pipeline is detected, both rotating cameras are turned off and the panoramic camera at the front is turned on. The panoramic camera takes a one-time shot of the axial direction of the third part of the pipeline to obtain a comprehensive image of that part. After the shooting is completed, the detection process ends, and the robot's drive motor reverses, allowing the robot to safely return to the pipe mouth position. The entire detection process follows strict logic and precise operating steps to ensure the accuracy and comprehensiveness of data collection. The overall control logic is as follows Figure 4 .

[0047] V. Other Institutional Design Schemes Power supply: Due to the small working space and size limitations of the robot, a customized 12V DC battery pack is now used with a long strip design that is directly installed inside the spindle.

[0048] Emergency fault handling mechanism: If the robot stops moving due to a fault in the pipe, an emergency exit mechanism is designed. Three trunnions are set at the base of the reducer at the rear end of the robot. The trunnions are reserved outside the pipe through thin nylon lines. When a fault occurs, the nylon line is pulled outside the pipe to pull the robot out of the pipe and check the robot fault. This ensures that the robot can be pulled out of the pipe in case of a fault.

[0049] Module splicing mechanism: Since the first camera meets the needs of detecting the combustion chamber, the overall size of the robot is relatively large. The main shaft with the first camera, the front extension rod, and the rear extension rod are designed to be detachable, fastened with bolts, and line interfaces are set at the joints to connect with each part.

[0050] 6. Robot overall platform structure design Overall structure According to the specific design plan of each part, the position distribution of each module of the design robot is as follows Figure 1 shown.

[0051] According to the characteristics of each module of the robot and the overall layout of the robot, special consideration is given to positioning the center of gravity of the robot as far back as possible, at the intersection of the section where the midpoint of the driving wheel is located and the center axis of the robot.

[0052] Camera module: The first camera is located at the front end of the robot and has an extension rod to take pictures of the combustion chamber. The second camera is located at the front end of the variable diameter mechanism to take pictures of part of the wall line and slope wall. The third camera is located at the rear end of the variable diameter mechanism to take pictures of the wall line part (exit part) photographed by the second camera.

[0053] Driving motor: It is arranged on the connecting rod of the reducing mechanism, close to the rear driving wheel, and outputs torque to the rear driving wheel.

[0054] Battery: It is installed on the robot spindle where the diameter reducing mechanism is located.

[0055] Control panel: set at the rear end of the second camera.

[0056] In summary, the overall structural design of the present invention is as follows, including a middle detection mechanism, a front detection mechanism and an emergency exit mechanism, the front detection mechanism and the emergency exit mechanism are detachably arranged at the front end and the rear end of the diameter-changing mechanism, respectively, the middle detection mechanism includes a diameter-changing mechanism, a second camera 2 and a third camera 8, the second camera 2 and the third camera 8 are respectively arranged at the front end and the rear end of the diameter-changing mechanism, the diameter-changing mechanism includes a telescopic rod, a diameter-changing bracket and a walking mechanism 9, a plurality of diameter-changing brackets are uniformly arranged radially on the outside of the telescopic rod, the walking mechanism 9 is arranged on the diameter-changing bracket, the telescopic rod is used to adjust the width of the diameter-changing bracket by telescoping, The walking mechanism 9 is made to contact and fit the inner side surface of the pipeline, and the walking mechanism 9 is used to drive the entire detection device to move forward along the inner side surface of the pipeline. The second camera 2 and the third camera 8 are both used to rotate 360° along the outer circumference of the telescopic rod to capture the image of the inner side of the pipeline and automatically store it. The front-end detection mechanism includes an extension rod and a first camera 1, and the first camera 1 is arranged at the front end of the extension rod. The front-end detection mechanism is used to capture the image of the narrow area at the front end of the pipeline through the first camera 1 at the front end and automatically store it. The emergency exit mechanism includes a pull rope, one end of which is connected to the rear end of the telescopic rod, and the other end extends to the outside of the pipeline.

[0057] The telescopic rod includes a fixed rod 3 and a rotating screw 4, and the variable diameter bracket includes a U-shaped frame 6 and a support rod 7. Both ends of the U-shaped frame 6 are hinged to the fixed rod 3, and form a parallelogram frame with the fixed rod 3. An adjusting nut 5 is provided on the rotating screw 4, and the rotating screw 4 is used to drive the adjusting nut 5 to translate by rotation. One end of the support rod 7 is hinged to the rear side of the U-shaped frame 6, and the other end is hinged to the adjusting nut 5 through a spring pre-tightening mechanism.

[0058] The above is an example of the best implementation of the present invention, and the parts not described in detail are common knowledge of ordinary technicians in the field. The protection scope of the present invention shall be based on the content of the claims, and any equivalent transformation based on the technical enlightenment of the present invention is also within the protection scope of the present invention.

Claims

1. A pipeline internal state detection device, characterized in that: The invention comprises a middle detection mechanism, a front detection mechanism and an emergency exit mechanism, wherein the front detection mechanism and the emergency exit mechanism are detachably arranged at the front end and the rear end of the diameter-changing mechanism, respectively; the middle detection mechanism comprises the diameter-changing mechanism, a second camera (2) and a third camera (8), wherein the second camera (2) and the third camera (8) are arranged at the front end and the rear end of the diameter-changing mechanism, respectively; the diameter-changing mechanism comprises a telescopic rod, a diameter-changing bracket and a walking mechanism (9), wherein a plurality of diameter-changing brackets are evenly arranged radially outside the telescopic rod, and the walking mechanism (9) is arranged on the diameter-changing bracket, and the telescopic rod is used to adjust the width of the diameter-changing bracket by telescoping so that the walking mechanism (9) ) contacts and fits the inner side of the pipeline, the walking mechanism (9) is used to drive the entire detection device to move forward along the inner side of the pipeline, the second camera (2) and the third camera (8) are used to rotate 360 ​​degrees along the outer circumference of the telescopic rod to capture the image of the inner side of the pipeline and automatically store it, the front-end detection mechanism includes an extension rod and a first camera (1), the first camera (1) is arranged at the front end of the extension rod, the front-end detection mechanism is used to capture the image of the narrow area at the front end of the pipeline through the first camera (1) at the front end and automatically store it, and the emergency exit mechanism includes a pull rope, one end of the pull rope is connected to the rear end of the telescopic rod, and the other end extends to the outside of the pipeline.

2. The pipeline internal state detection device according to claim 1, characterized in that: The telescopic rod comprises a fixed rod (3) and a rotating screw rod (4); the variable diameter bracket comprises a U-shaped frame (6) and a support rod (7); both ends of the U-shaped frame (6) are hinged to the fixed rod (3) and form a parallelogram frame with the fixed rod (3); an adjusting nut (5) is arranged on the rotating screw rod (4); the rotating screw rod (4) is used to drive the adjusting nut (5) to translate by rotation; one end of the support rod (7) is hinged to the rear side of the U-shaped frame (6); and the other end is hinged to the adjusting nut (5) through a spring preload mechanism.

3. The pipeline internal state detection device according to claim 2, characterized in that: The support rod (7) is connected to the rotating screw (4) via a spring pre-tightening mechanism, wherein the spring pre-tightening mechanism comprises a connecting base (11) and a spring (10), wherein the spring (10) is sleeved on the outside of the rotating screw (4), and one end of the spring is connected to the base (11), and the other end is connected to the adjusting nut (5).

4. The pipeline internal state detection device according to claim 1, characterized in that: The position of the second camera (2) after the detection device completely enters the pipeline from the pipeline outlet is assumed to be the demarcation point; the third camera (8) is activated when the detection device completely enters the pipeline outlet, and is closed after the third camera (8) reaches the demarcation point, and is used to rotate 360 ​​degrees to photograph the image of the inside of the pipeline between the pipeline outlet and the demarcation point; the second camera (2) is activated when the detection device completely enters the pipeline outlet, and is used to rotate 360 ​​degrees to photograph the image of the inside of the pipeline after the inner demarcation point; the first camera (1) is activated when the detection device reaches the outside of the combustion chamber at the end of the gas pipeline, after the first camera (1) is extended into the inside of the combustion chamber, or after the first camera (1) is extended into other narrow spaces, and is used to rotate 360 ​​degrees to photograph the image of the combustion chamber or the narrow space.

5. The pipeline internal state detection device according to claim 1, characterized in that: The number of the variable diameter brackets is at least three.

6. The pipeline internal state detection device according to claim 1, characterized in that: Fill-in lights are arranged on the outside of the first camera (1), the second camera (2) and the third camera (8) for providing fill-in light when the cameras are shooting.

7. The pipeline internal state detection device according to claim 1, characterized in that: The telescopic rod can adjust the width of the variable diameter bracket in real time according to the inner diameter of the pipeline under remote control of the remote control end, so that the walking mechanism (9) contacts and fits the inner side of the pipeline during detection, and detaches from the inner side of the pipeline when exiting the pipeline.

8. The pipeline internal state detection device according to claim 1, characterized in that: It also includes a position sensor, which is used to detect the real-time position of the detection device and send it to the remote control terminal.

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