Mooring-free rigid robot for evaporator inter-tube detection

Abstract

The invention relates to the field of rigid non-mooring detection robots, in particular to a non-mooring rigid robot for evaporator inter-tube detection, which comprises a ball screw forward module and electromagnetic steering joint modules, and the electromagnetic steering joint modules are mounted on the front side and the rear side of the ball screw forward module. The ball screw advancing module comprises a micro direct current motor and a sleeve buckle installed on an output shaft of the micro direct current motor, and the sleeve buckle is connected with a screw guide rail through threads. The micro direct current motor is fixedly connected to the movable joint, and the movable joint and the lead screw guide rail are each provided with a limiting mechanism. The limiting mechanism comprises two hinge shafts and two hinge hinges hinged to the two hinge shafts, hinge torsion springs are fixedly connected between the hinge hinges and the hinge shafts, and the two hinge torsion springs drive the two hinge hinges to have the trend of unfolding movement. The inter-tube environment of the evaporator can be effectively traversed, and the inter-tube environment can be detected in real time.

Description

A tetherless rigid robot for inter-tube inspection of evaporators Technical Field

[0001] This invention relates to the field of rigid untethered inspection robots, and more specifically to an untethered rigid robot for inspection between evaporator tubes. Background Technology

[0002] Nuclear power, as a relatively mature energy source, boasts numerous advantages such as economic efficiency, environmental friendliness, high energy density, and safety and stability. It can effectively alleviate energy problems, making its development of extremely important strategic significance. The evaporator plays a crucial role in a nuclear power plant. As the hub between the primary and secondary loops, it promptly transfers the heat generated by nuclear fission in the primary reactor to the secondary loop, causing the secondary loop energy to evaporate. Inside, steam with a specific temperature and pressure is formed. This steam is then fed into the turbine to perform work, converting it into electrical or mechanical energy.

[0003] During normal operation, due to various reasons, corrosion products, namely sludge, will inevitably form in the evaporator and water supply system. A considerable portion of this sludge will accumulate on the horizontal and vertical solid surfaces inside the secondary side of the steam generator, such as the surface of the secondary side tube sheet, the surface of the distribution plate, the surface of the support plate, and the outer surface of the heat exchange tubes.

[0004] The environment between evaporator tubes in a nuclear power plant consists of a dense and complex array of tube bundles. Compared to other external environments, it presents challenges such as limited space, dense tube bundles, and restricted movement. To address these challenges, the company has implemented measures such as improving management practices, using endoscopes for inspection through handholes, and employing fixed cameras and quick-release devices for regular maintenance. However, these methods often involve large-scale shutdowns for maintenance, requiring workers to continue working in environments with nuclear contamination. This not only reduces the company's production efficiency but also exposes nuclear power plant workers to greater health risks. Furthermore, traditional methods struggle to accurately cover the entire complex and confined tube bundle environment. Therefore, there is an urgent need to design a tube-between inspection robot capable of effectively traversing the evaporator tube-between environment and performing real-time inspections. Summary of the Invention

[0005] The purpose of this invention is to provide an untethered rigid robot for evaporator tube inspection, which can effectively traverse the evaporator tube environment and inspect the tube environment in real time, thereby solving the problems of movement, detection, and calibration in confined spaces.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An untethered rigid robot for evaporator tube inspection includes a ball screw forward module and an electromagnetic steering joint module, wherein electromagnetic steering joint modules are installed on both the front and rear sides of the ball screw forward module.

[0008] The ball screw forward module includes a micro DC motor and a sleeve mounted on the output shaft of the micro DC motor, with a screw guide rail connected to the sleeve via threads.

[0009] The micro DC motor is fixedly connected to the movable joint, and limit mechanisms are provided on both the movable joint and the lead screw guide rail.

[0010] The limiting mechanism includes two hinge shafts and two hinged hinges hinged to the two hinge shafts. A hinge torsion spring is fixedly connected between the hinged hinges and the hinge shafts. The two hinge torsion springs drive the two hinged hinges to tend to unfold.

[0011] The rear side of the movable joint is fixedly connected to two hinge shafts, and the front side of the movable joint and the hinged joint are in contact, restricting the two hinged joints to swing only to the rear.

[0012] Two hinge shafts are fixedly connected to the front side of the lead screw guide rail. The front side of the lead screw guide rail and the hinge joints are in contact, restricting the two hinge joints to swing only to the rear.

[0013] A control backpack is mounted on the lead screw guide rail. The control backpack is used to carry the robot's wireless communication control board, lithium battery power supply, Bluetooth module and UWB positioning module.

[0014] The electromagnetic steering joint module includes a micro steering motor and a micro electromagnet. A steering motor bushing is installed on the output shaft of the micro steering motor, and a steering connecting block is fixedly connected between the micro steering motor and the micro electromagnet.

[0015] Steering connecting blocks are fixedly connected to the rear end of the movable joint and the front end of the lead screw guide rail.

[0016] The micro electromagnet is installed inside the electromagnet sleeve via a threaded shaft and a bearing. The outer ring of the bearing and the electromagnet sleeve are fitted together, and the threaded shaft of the bearing is fitted together with the threaded shaft rod, enabling the electromagnet sleeve to complete the steering motion. The electromagnet sleeve is installed on the lower side of the moving joint and the lead screw guide rail.

[0017] The beneficial effects of this invention are as follows:

[0018] With an extremely compact structure and strong geometric mobility: Through a highly integrated flat body design, the robot's lateral width is strictly controlled within 8mm, successfully adapting to the nuclear power plant's evaporator with a limit tube gap of only 8.38mm; combined with a chamfered design and modular serial configuration, it effectively utilizes the tube gallery space and solves the problem of non-destructive entry and flexible turning in narrow and restricted environments.

[0019] High support stiffness and excellent anti-overturning ability: The innovative torsion spring-double block self-locking hinge mechanism cleverly balances the contradiction between motion flexibility and support stiffness. It forms mechanical self-locking in telescopic movement and cantilever state, effectively eliminating the risk of "soft leg" collapse of multi-joint series structure in the absence of guide rails, and ensuring the stability of robot posture.

[0020] High driving thrust and precise displacement control: The micro DC motor, ball screw pair and multi-stage telescopic sleeve transmission provide higher transmission rigidity and axial thrust compared with traditional rope drive or pure wheel structure. It can effectively overcome the frictional resistance of the pipe wall and achieve millimeter-level precise control of the crawling step distance to meet the needs of fixed point detection.

[0021] Stable adsorption and anchoring with good operational adaptability: Utilizing the environmental characteristics of the evaporator tube bundle, alternating adsorption and anchoring are achieved using DC suction cup electromagnets, eliminating the reliance on complex external guide rails or traction cables; and the split modular design facilitates quick disassembly and maintenance for different tube environments, significantly improving the reliability and practicality of the system. Attached Figure Description

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific implementation methods.

[0023] Figure 1 is a schematic diagram of the untethered rigid robot structure for inter-tube inspection of evaporators according to the present invention.

[0024] Figure 2 is a front view of the untethered rigid robot for inter-tube inspection of evaporators according to the present invention;

[0025] Figure 3 is a side view of the untethered rigid robot for inter-tube inspection of evaporators according to the present invention;

[0026] Figure 4 is a top view of the untethered rigid robot for inter-tube inspection of evaporators according to the present invention;

[0027] Figure 5 is a schematic diagram of the ball screw forward module structure of the present invention;

[0028] Figure 6 is a schematic diagram of the electromagnetic steering joint module structure of the present invention;

[0029] Figure 7 is a schematic diagram of the micro DC motor structure of the present invention;

[0030] Figure 8 is a top view of the micro DC motor of the present invention;

[0031] Figure 9 is a schematic diagram of the micro electromagnet structure of the present invention;

[0032] Figure 10 is a schematic diagram of the principle of the untethered rigid robot for evaporator tube detection moving between tubes in the first moment according to the present invention.

[0033] Figure 11 is a schematic diagram of the second moment of movement of the untethered rigid robot for evaporator tube detection according to the present invention between tubes.

[0034] Figure 12 is a schematic diagram of the principle of the untethered rigid robot for evaporator tube detection moving between tubes at the third moment according to the present invention.

[0035] Figure 13 is a schematic diagram of the fourth moment of the movement principle of the untethered rigid robot for evaporator tube detection according to the present invention.

[0036] Figure 14 is a schematic diagram of the front joint steering motion of the untethered rigid robot for inter-tube detection of evaporators according to the present invention.

[0037] Figure 15 is a schematic diagram of the rear joint steering motion of the untethered rigid robot for evaporator tube detection according to the present invention.

[0038] In the diagram: 1. Ball screw forward module; 2. Electromagnetic steering joint module; 3. Sleeve; 4. Screw guide rail; 5. Hinge joint; 6. Hinge shaft; 7. Hinge torsion spring; 8. Micro DC motor; 9. Moving joint; 10. Micro steering motor; 11. Micro electromagnet; 12. Steering connecting block; 13. Steering motor bushing; 14. Control backpack; 15. Electromagnet sleeve; 16. Bearing; 17. Threaded shaft. Detailed Implementation

[0039] The present invention will now be described in further detail with reference to the accompanying drawings.

[0040] As shown in Figures 1 to 15, the structure and function of an untethered rigid robot for evaporator tube inspection are described in detail below.

[0041] As shown in Figure 1, an untethered rigid robot for evaporator tube inspection includes a ball screw forward module 1 and an electromagnetic steering joint module 2. The electromagnetic steering joint module 2 is installed on both the front and rear sides of the ball screw forward module 1.

[0042] In use, the electromagnetic steering joint module 2 located at the rear is attached to the tube sheet of the nuclear power plant evaporator tubes. The ball screw forward module 1 can extend or retract. When the ball screw forward module 1 extends, it pushes the electromagnetic steering joint module 2 located at the front to move forward. After the electromagnetic steering joint module 2 located at the front moves to the designated position, it is attached to the tube sheet. The electromagnetic steering joint module 2 located at the rear relaxes, and the ball screw forward module 1 retracts. The electromagnetic steering joint module 2 located at the rear is pulled forward by the ball screw forward module 1 to move forward. After the electromagnetic steering joint module 2 located at the rear moves to the designated position, one movement is completed. Repeated movement completes the forward movement of the untethered rigid robot facing the evaporator tube inspection.

[0043] When a turn is required, the electromagnetic steering joint module 2 located at the rear attaches to the tube sheet of the nuclear power plant evaporator tube, the electromagnetic steering joint module 2 located at the front releases, and the electromagnetic steering joint module 2 located at the rear activates, driving the ball screw forward module 1 to rotate around the rotation axis of the electromagnetic steering joint module 2 to complete the turn.

[0044] The electromagnetic steering joint module 2 located at the front is attached to the tube sheet of the nuclear power plant evaporator tube. The electromagnetic steering joint module 2 located at the rear is released, and the electromagnetic steering joint module 2 located at the front is activated, driving the ball screw forward module 1 to rotate around the rotation axis of the electromagnetic steering joint module 2 to complete the steering.

[0045] As shown in Figure 5, the ball screw forward module 1 includes a micro DC motor 8 and a sleeve 3 mounted on the output shaft of the micro DC motor 8. The D-shaped shaft of the micro DC motor 8 has a 7mm external thread, which is interference-fitted with the sleeve 3. A screw guide rail 4 is threadedly connected to the sleeve 3. The micro DC motor 8 is glued to the moving joint 9. The moving joint 9 is manufactured by CNC milling and laser cutting. Both the moving joint 9 and the screw guide rail 4 are equipped with limit mechanisms. The screw guide rail 4 has a width of 8mm and a 7mm internal thread, which is used for transmission in conjunction with the external thread of the sleeve 3. The screw guide rail 4 is obtained by CNC milling, tapping, and laser drilling.

[0046] When in use, start the micro DC motor 8. The output shaft of the micro DC motor 8 drives the sleeve 3 to rotate. When the sleeve 3 rotates, it pushes the lead screw guide 4 to move laterally through the thread, so that the ball screw forward module 1 extends or retracts.

[0047] As shown in Figure 5, the limiting mechanism includes two hinge shafts 6 and two hinged hinges 5 hinged to the two hinge shafts 6. A hinge torsion spring 7 is fixedly connected between the hinged hinges 5 and the hinge shafts 6. One end of the hinge torsion spring 7 is fixedly connected to the hinged hinges 5, and the other end of the hinge torsion spring 7 is fixedly connected to the hinge shafts 6. The two hinge torsion springs 7 drive the two hinged hinges 5 to tend to unfold.

[0048] The rear side of the movable joint 9 is fixedly connected to two hinge shafts 6. The movable joint 9 and the front side of the hinged joint 5 are in contact, restricting the two hinged joints 5 to swing only to the rear.

[0049] Two hinge shafts 6 are fixedly connected to the front side of the lead screw guide rail 4. The front side of the lead screw guide rail 4 and the hinge joint 5 are in contact, restricting the two hinge joint 5 to swing only to the rear.

[0050] When the robot performs a linear motion task, the micro DC motor 8 receives commands from the main control board and rotates forward to drive the ball screw forward module 1 to move in one direction. At the same time, the rear electromagnetic steering joint module 2 is attracted to the tube plate. At this time, the rear hinge joint 5 is locked and fixed between the rear and the evaporator tube under the action of the hinge torsion spring 7 and the mechanical limit, providing forward thrust for the robot, so that the robot moves forward under the ball screw forward module 1. When the front end moves to the designated position, the front hinge joint 5 and the hinge torsion spring 7 are locked with the tube limit, and the front electromagnetic steering joint module 2 is attracted, the rear electromagnetic steering joint module 2 is released, the micro DC motor 8 reverses, and the rear end of the robot moves to the designated position under the drive of the ball screw forward module 1.

[0051] As shown in Figure 5, a control backpack 14 is mounted on the lead screw guide rail 4. The control backpack 14 is used to carry the robot's wireless communication control board, lithium battery power supply, Bluetooth module, and UWB positioning module. These control modules effectively control the robot's movement between tubes. At the same time, the reasonable distribution of the PCB circuit board and battery position within the control backpack can adjust the robot's center of gravity, making the robot's movement more stable.

[0052] As shown in Figure 6, the electromagnetic steering joint module 2 includes a micro steering motor 10 and a micro electromagnet 11. A steering motor bushing 13 is mounted on the output shaft of the micro steering motor 10. A steering connecting block 12 is fixedly connected between the micro steering motor 10 and the micro electromagnet 11. The steering connecting block 12 is manufactured using 3D printing technology and is made of PLA. The steering connecting block 12 is fixed to the micro steering motor 10 and the micro electromagnet 11 by adhesive. The steering motor bushing 13 is manufactured by wire cutting and is interference-fitted with the micro steering motor 10. The rear end of the moving joint 9 and the front end of the lead screw guide 4 are both fixedly connected to the steering connecting block 12 by adhesive.

[0053] The micro electromagnet 11 is installed inside the electromagnet sleeve 15 via a threaded shaft 17 and a bearing 16. The outer ring of the bearing 16 and the electromagnet sleeve 15 are engaged, and the threaded shaft 17 of the bearing 16 is engaged with the threaded shaft rod, so that the electromagnet sleeve 15 can complete the turning motion. The electromagnet sleeve 15 is installed on the lower side of the moving joint 9 and the lead screw guide rail 4.

[0054] This allows the electromagnet sleeve 15 to support the movable joint 9 and the lead screw guide rail 4, and the electromagnet sleeve 15 can rotate with the movable joint 9 or the lead screw guide rail 4.

[0055] When the robot performs a turning motion task, the micro steering motor 10 receives commands from the main control board, the rear micro electromagnet 11 is energized and attaches to the cast iron tube sheet of the evaporator. At this time, under the action of the rear micro steering motor 10, the robot turns the whole body by a specified angle. Then the front micro electromagnet 11 attaches to the cast iron tube sheet of the evaporator, the rear micro electromagnet 11 is de-energized, and the robot rotates by the specified angle, so that the robot enters another row of tube bundles for exploration.

[0056] As shown in Figures 1 to 15, the following is a detailed embodiment illustrating the detailed implementation of this untethered rigid robot for evaporator tube inspection.

[0057] Overall Working Process – Forward Motion: The robot's straight-line forward movement is driven by alternating anchoring "inchworm-like" stepping. When the robot performs a straight-line motion task, it includes the following two stages:

[0058] As shown in Figure 10, the first step is the front-end extension: the micro electromagnet 11 located at the rear of the robot is energized and firmly adheres to the cast iron base plate of the evaporator, providing an absolute anchoring point. Simultaneously, the rear hinge 5 opens under the tension of the hinge torsion spring 7 and is firmly secured between the rear tubes, providing auxiliary anti-slip thrust. At this time, the main control board sends a forward rotation command to the micro DC motor 8. The D-shaped shaft of the micro DC motor 8 drives the sleeve 3 to rotate. Because the sleeve 3 has external threads and precisely matches the internal threads of the lead screw guide rail 4, it is completely fixed at the rear. With the double anchoring of the electromagnet and the hinge, the rotational motion of the sleeve 3 is converted into a forward linear thrust of the lead screw guide rail 4, thereby propelling the front end of the robot to smoothly slide forward and extend between the tubes.

[0059] The technical principle behind the hinged hinge 5 locking between tubes is as follows: The two sides of the hinged torsion spring 7 are fixed to the folds of the hinged hinge 5. Utilizing the normal elastic force of the torsion spring, the hinged hinge 5 is forced to maintain an outward-opening tendency. When the robot enters the narrow space between the evaporator tube bundles, the outward-opening edges of the hinged hinge 5 will tightly press against the tube walls on both sides. Combined with the mechanical limiting design, the hinged hinge 5 can only fold backward in the contraction direction and cannot fold forward. Therefore, when the ball screw forward module 1 pushes forward and generates a backward reaction force, the hinged hinge 5 will act like a wedge, firmly locking between the tube walls on both sides, forming a stable static friction anchor point, completely preventing the robot body from sliding backward.

[0060] As shown in Figure 11, the second step is rear-end follow-up: After the front end is pushed to the designated single-step displacement, the front-end micro electromagnet 11 is energized and attracted to the base plate, and the front-end hinge 5 opens and locks in the tube gap, establishing a new anchoring point at the front. Subsequently, the rear-end micro electromagnet 11 is de-energized and released. At this time, the main control board instructs the micro DC motor 8 to reverse. With the front end firmly anchored, the reverse transmission of the micro DC motor 8 generates a forward pulling force, pulling the robot's rear-end moving joint 9, micro DC motor 8, and rear-end electromagnetic steering joint module 2 forward as a whole, retracting them to approach the front end, thus completing a complete forward movement cycle. By continuously repeating this process, the robot can be driven to move smoothly forward in the tube gap.

[0061] As shown in Figures 14 and 15, the overall working process—turning motion—is as follows: When the robot reaches the end of the tube bundle or needs to switch to another row of tubes for exploration, it performs the following turning motion task: First, the micro electromagnet 11 at the rear end is energized and strongly attracted to the cast iron base plate of the evaporator, firmly fixing the tail of the robot. This attraction point serves as the physical rotation center point for the entire robot's turning. Second, the main control board sends a rotation command to the micro steering motor 10 at the rear end. The power of the micro steering motor 10 is directly transmitted to the robot's ball screw forward module 1 through the interference fit steering motor bushing 13. Driven by the torque of the micro steering motor 10, since the micro electromagnet 11 at the rear end is attracted and locked by the base plate, the body of the micro steering motor 10 and the steering connecting block 12 remain relatively stationary, thereby forcing the entire front end of the robot to swing in an arc around the center point of the micro electromagnet 11 at the rear end, smoothly turning to the set specified angle. Finally, after the robot's front end swings to align with the gap in the pipe in the target direction, the micro electromagnet 11 at the front end is energized and attracts to the cast iron base plate to lock the new posture. Subsequently, the micro electromagnet 11 at the rear end is de-energized and released. At this point, the robot has completely completed a turning maneuver and is ready to continue its stepping forward exploration mission in the new direction.

[0062] It should be noted that while preferred embodiments of this application are provided in the specification and accompanying drawings, this application can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of this application; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of this application. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of this specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A tetherless rigid robot for evaporator tube inspection, comprising a ball screw forward module (1) and an electromagnetic steering joint module (2), characterized in that: Electromagnetic steering joint modules (2) are installed on both the front and rear sides of the ball screw forward module (1).

2. The untethered rigid robot for inter-tube inspection of evaporators according to claim 1, characterized in that: The ball screw forward module (1) includes a micro DC motor (8) and a sleeve (3) mounted on the output shaft of the micro DC motor (8). A screw guide rail (4) is threaded onto the sleeve (3).

3. The untethered rigid robot for inter-tube inspection of evaporators according to claim 2, characterized in that: The micro DC motor (8) is fixedly connected to the movable joint (9), and both the movable joint (9) and the lead screw guide (4) are equipped with limit mechanisms.

4. The untethered rigid robot for evaporator tube inspection according to claim 3, characterized in that: The limiting mechanism includes two hinge shafts (6) and two hinged hinges (5) hinged on the two hinge shafts (6). A hinge torsion spring (7) is fixedly connected between the hinged hinges (5) and the hinge shafts (6). The two hinge torsion springs (7) drive the two hinged hinges (5) to have an unfolding motion.

5. The untethered rigid robot for evaporator tube inspection according to claim 4, characterized in that: The rear side of the movable joint (9) is fixedly connected to two hinge shafts (6), and the front side of the movable joint (9) and the hinged joint (5) are in contact, restricting the two hinged joints (5) to swing only to the rear.

6. The untethered rigid robot for inter-tube inspection of evaporators according to claim 4, characterized in that: The front side of the lead screw guide (4) is fixedly connected to two hinge shafts (6). The front side of the lead screw guide (4) and the hinge joint (5) are in contact, restricting the two hinge joints (5) to swing only to the rear.

7. The untethered rigid robot for inter-tube inspection of evaporators according to claim 2, characterized in that: The lead screw guide (4) is equipped with a control backpack (14), which is used to carry the robot's wireless communication control board, lithium battery power supply, Bluetooth module and UWB positioning module.

8. The untethered rigid robot for inter-tube inspection of evaporators according to claim 3, characterized in that: The electromagnetic steering joint module (2) includes a micro steering motor (10) and a micro electromagnet (11). A steering motor bushing (13) is installed on the output shaft of the micro steering motor (10). A steering connection block (12) is fixedly connected between the micro steering motor (10) and the micro electromagnet (11).

9. A tetherless rigid robot for evaporator tube inspection according to claim 8, characterized in that: Steering connecting blocks (12) are fixedly connected to the rear end of the movable joint (9) and the front end of the lead screw guide (4).

10. A tetherless rigid robot for evaporator tube inspection according to claim 8, characterized in that: The micro electromagnet (11) is installed inside the electromagnet sleeve (15) via a threaded shaft (17) and a bearing (16). The outer ring of the bearing (16) and the electromagnet sleeve (15) are engaged. The threaded shaft (17) of the bearing (16) is engaged with the threaded shaft rod, so that the electromagnet sleeve (15) can complete the turning motion. The electromagnet sleeve (15) is installed on the lower side of the moving joint (9) and the lead screw guide (4).

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